Measurements and Simulation Studies of Piezoceramics for Acoustic Particle Detection

Calibration sources are an indispensable tool for all detectors. In acoustic particle detection the goal of a calibration source is to mimic neutrino signatures as expected from hadronic cascades. A simple and promising method for the emulation of neutrino signals are piezo ceramics. We will present results of measruements and simulations on these piezo ceramics.Comment: 5 pages, 5 figure

Integrating Traditional and Scientific Knowledge through Collaborative Natural Science Field Research: Identifying Elements for Success

We discuss two recent projects to examine the role of collaborative environmental fieldwork both in research and in the interactions between academically trained researchers and experienced local residents. The Bidarki Project studied black leather chitons (Katharina tunicata) in the lower Kenai Peninsula, Alaska. Its conclusion that chiton declines are part of a serial decline of intertidal invertebrates drew on collaborative fieldwork, archaeological data, historical records, and interviews with local residents. The Siku-Inuit-Hila Project studied sea ice in Barrow, Alaska; Clyde River, Nunavut; and Qaanaaq, Greenland. Quantitative data from locally maintained observation sites were supplemented by knowledge exchanges among hunters from the communities and by discussion in local working groups to develop an understanding of the physical dynamics and human uses of sea ice at each locale. We conclude that careful planning and preparation, along with the effort to build strong personal relationships, can increase the likelihood that collaborative fieldwork will be productive, enjoyable, and rewarding.Nous discutons de deux récents projets ayant eu pour but d’examiner le rôle d’études environnementales collaboratives sur le terrain, tant sur le plan de la recherche que sur le plan des interactions entre les chercheurs universitaires et les résidents expérimentés des localités visées. Le projet Bidarki se penchait sur les chitons noirs (Katharina tunicata) de la basse péninsule Kenai, en Alaska. La conclusion selon laquelle le déclin des chitons fait partie d’un déclin en série d’invertébrés intertidaux s’appuie sur des études collaboratives sur le terrain, sur des données archéologiques, sur des dossiers historiques ainsi que sur des entrevues de résidents des localités. Pour sa part, le projet Siku-Inuit-Hila a eu comme objectif d’étudier la glace de mer à Barrow, en Alaska; à Clyde River, au Nunavut; et à Qaanaaq, au Groenland. Les données quantitatives provenant de lieux d’observation entretenus localement ont été supplémentées par les échanges de connaissances des chasseurs des collectivités et par les discussions de groupes de travail locaux visant à mieux comprendre la dynamique physique et l’utilisation humaine de la glace de mer à chaque endroit. Nous en concluons que des travaux de planification et de préparation attentionnés, accompagnés d’efforts visant à nouer des liens personnels étroits, peuvent accroître la possibilité que les études collaboratives sur le terrain soient productives, agréables et valorisantes

Metastability in spin polarised Fermi gases and quasiparticle decays

We investigate the metastability associated with the first order transition from normal to superfluid phases in the phase diagram of two-component polarised Fermi gases.We begin by detailing the dominant decay processes of single quasiparticles.Having determined the momentum thresholds of each process and calculated their rates, we apply this understanding to a Fermi sea of polarons by linking its metastability to the stability of individual polarons, and predicting a region of metastability for the normal partially polarised phase. In the limit of a single impurity, this region extends from the interaction strength at which a polarised phase of molecules becomes the groundstate, to the one at which the single quasiparticle groundstate changes character from polaronic to molecular. Our argument in terms of a Fermi sea of polarons naturally suggests their use as an experimental probe. We propose experiments to observe the threshold of the predicted region of metastability, the interaction strength at which the quasiparticle groundstate changes character, and the decay rate of polarons

Flexible epidemiological model for estimates and short-term projections in generalised HIV/AIDS epidemics

International audienceObjective UNAIDS and country analysts use a simple infectious disease model, embedded in the Estimation and Projection Package (EPP), to generate annual updates on the global HIV/AIDS epidemic. Our objective was to develop modifications to the current model that improve fit to recently observed prevalence trends across countries. Methods Our proposed alternative to the current EPP approach simplifies the model structure and explicitly models changes in average infection risk over time, operationalised using penalised B-splines in a Bayesian framework. We also present an alternative approach to initiating the epidemic that improves standardisation and efficiency, and add an informative prior distribution for changes in infection risk beyond the last data point that enhances the plausibility of short-term extrapolations. Results The spline-based model produces better fits than the current model to observed prevalence trends in settings that have recently experienced levelling or rising prevalence following a steep decline, such as Uganda and urban Rwanda. The model also predicts a deceleration of the decline in prevalence for countries with recent experience of steady declines, such as Kenya and Zimbabwe. Estimates and projections from our alternative model are comparable to those from the current model where the latter performs well. Conclusions A more flexible epidemiological model that accommodates changing infection risk over time can provide better estimates and short-term projections of HIV/AIDS incidence, prevalence and mortality than the current EPP model. The alternative model specification can be incorporated easily into existing analytical tools that are used to produce updates on the global HIV/AIDS epidemic

How do electronic carriers cross Si-bound alkyl monolayers?

Electron transport through Si-C bound alkyl chains, sandwiched between n-Si and Hg, is characterized by two distinct types of barriers, each dominating in a different voltage range. At low voltage, current depends strongly on temperature but not on molecular length, suggesting transport by thermionic emission over a barrier in the Si. At higher voltage, the current decreases exponentially with molecular length, suggesting tunneling through the molecules. The tunnel barrier is estimated, from transport and photoemission data, to be ~1.5 eV with a 0.25me effective mass.Comment: 13 pages, 3 figure

Variable interaction in multi-objective optimization problems

14th International Conference on Parallel Problem Solving from Nature – PPSN XIV, 2016-09-17, 2016-09-21, Edinburgh, UK, pp. 399 - 409This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The final publication is available at link.springer.comVariable interaction is an important aspect of a problem, which reflects its structure, and has implications on the design of efficient optimization algorithms. Although variable interaction has been widely studied in the global optimization community, it has rarely been explored in the multi-objective optimization literature. In this paper, we empirically and analytically study the variable interaction structures of some popular multi-objective benchmark problems. Our study uncovers nontrivial variable interaction structures for the ZDT and DTLZ benchmark problems which were thought to be either separable or non-separable

Integration of Acoustic Detection Equipment into ANTARES

The ANTARES group at the University of Erlangen is working towards the integration of a set of acoustic sensors into the ANTARES Neutrino Telescope. With this setup, tests of acoustic particle detection methods and background studies shall be performed. The ANTARES Neutrino Telescope, which is currently being constructed in the Mediterranean Sea, will be equipped with the infrastructure to accommodate a 3-dimensional array of photomultipliers for the detection of Cherenkov light. Within this infrastructure, the required resources for acoustic sensors are available: Bandwidth for the transmission of the acoustic data to the shore, electrical power for the off-shore electronics and physical space to install the acoustic sensors and to route the connecting cables (transmitting signals and power) into the electronics containers. It will be explained how the integration will be performed with minimal modifications of the existing ANTARES design and which setup is foreseen for the acquisition of the acoustic data.Comment: 5 pages, 1 figure, to appear in the proceedings of the 1st International ARENA Workshop, May 17-19th, 2005, DESY Zeuthen (Germany

Exclusion Statistics in a two-dimensional trapped Bose gas

We briefly explain the notion of exclusion statistics and in particular discuss the concept of an ideal exclusion statistics gas. We then review a recent work where it is demonstrated that a {\em two-dimensional} Bose gas with repulsive delta function interactions obeys ideal exclusion statistics, with a fractional parameter related to the interaction strength.Comment: 10 pages, RevTeX. Proceedings of the Salerno workshop "Theory of Quantum Gases and Quantum Coherence", to appear in a special issue of J.Phys. B, Dec. 200

Single-Cell Transcriptomics in Cancer Immunobiology: The Future of Precision Oncology.

Cancer is a heterogeneous and complex disease. Tumors are formed by cancer cells and a myriad of non-cancerous cell types that together with the extracellular matrix form the tumor microenvironment. These cancer-associated cells and components contribute to shape the progression of cancer and are deeply involved in patient outcome. The immune system is an essential part of the tumor microenvironment, and induction of cancer immunotolerance is a necessary step involved in tumor formation and growth. Immune mechanisms are intimately associated with cancer progression, invasion, and metastasis; as well as to tumor dormancy and modulation of sensitivity to drug therapy. Transcriptome analyses have been extensively used to understand the heterogeneity of tumors, classifying tumors into molecular subtypes and establishing signatures that predict response to therapy and patient outcomes. However, the classification of the tumor cell diversity and specially the identification of rare populations has been limited in these transcriptomic analyses of bulk tumor cell populations. Massively-parallel single-cell RNAseq analysis has emerged as a powerful method to unravel heterogeneity and to study rare cell populations in cancer, through unsupervised sampling and modeling of transcriptional states in single cells. In this context, the study of the role of the immune system in cancer would benefit from single cell approaches, as it will enable the characterization and/or discovery of the cell types and pathways involved in cancer immunotolerance otherwise missed in bulk transcriptomic information. Thus, the analysis of gene expression patterns at single cell resolution holds the potential to provide key information to develop precise and personalized cancer treatment including immunotherapy. This review is focused on the latest single-cell RNAseq methodologies able to agnostically study thousands of tumor cells as well as targeted single-cell RNAseq to study rare populations within tumors. In particular, we will discuss methods to study the immune system in cancer. We will also discuss the current challenges to the study of cancer at the single cell level and the potential solutions to the current approaches

Development of Acoustic Sensors for the ANTARES Experiment

In order to study the possibility of acoustic detection of ultra-high energy neutrinos in water, our group is planning to deploy and operate an array of acoustic sensors using the ANTARES Neutrino telescope in the Mediterranean Sea. Therefore, acoustic sensor hardware has to be developed which is both capable of operation under the hostile conditions of the deep sea and at the same time provides the high sensitivity necessary to detect the weak pressure signals resulting from the neutrino's interaction in water. In this paper, two different approaches to building such sensors, as well as performance studies in the laboratory and in situ, are presented.Comment: 5 pages, 3 figures. Proceedings of the ARENA 2005 Worksho