124 research outputs found
CernVM Online and Cloud Gateway: a uniform interface for CernVM contextualization and deployment
In a virtualized environment, contextualization is the process of configuring
a VM instance for the needs of various deployment use cases. Contextualization
in CernVM can be done by passing a handwritten context to the user data field
of cloud APIs, when running CernVM on the cloud, or by using CernVM web
interface when running the VM locally. CernVM Online is a publicly accessible
web interface that unifies these two procedures. A user is able to define,
store and share CernVM contexts using CernVM Online and then apply them either
in a cloud by using CernVM Cloud Gateway or on a local VM with the single-step
pairing mechanism. CernVM Cloud Gateway is a distributed system that provides a
single interface to use multiple and different clouds (by location or type,
private or public). Cloud gateway has been so far integrated with OpenNebula,
CloudStack and EC2 tools interfaces. A user, with access to a number of clouds,
can run CernVM cloud agents that will communicate with these clouds using their
interfaces, and then use one single interface to deploy and scale CernVM
clusters. CernVM clusters are defined in CernVM Online and consist of a set of
CernVM instances that are contextualized and can communicate with each other.Comment: Conference paper at the 2013 Computing in High Energy Physics (CHEP)
Conference, Amsterda
Micro-CernVM: Slashing the Cost of Building and Deploying Virtual Machines
The traditional virtual machine building and and deployment process is
centered around the virtual machine hard disk image. The packages comprising
the VM operating system are carefully selected, hard disk images are built for
a variety of different hypervisors, and images have to be distributed and
decompressed in order to instantiate a virtual machine. Within the HEP
community, the CernVM File System has been established in order to decouple the
distribution from the experiment software from the building and distribution of
the VM hard disk images.
We show how to get rid of such pre-built hard disk images altogether. Due to
the high requirements on POSIX compliance imposed by HEP application software,
CernVM-FS can also be used to host and boot a Linux operating system. This
allows the use of a tiny bootable CD image that comprises only a Linux kernel
while the rest of the operating system is provided on demand by CernVM-FS. This
approach speeds up the initial instantiation time and reduces virtual machine
image sizes by an order of magnitude. Furthermore, security updates can be
distributed instantaneously through CernVM-FS. By leveraging the fact that
CernVM-FS is a versioning file system, a historic analysis environment can be
easily re-spawned by selecting the corresponding CernVM-FS file system
snapshot.Comment: Conference paper at the 2013 Computing in High Energy Physics (CHEP)
Conference, Amsterda
Averages of Fourier coefficients of Siegel modular forms and representation of binary quadratic forms by quadratic forms in four variables
Let be a a negative discriminant and let vary over a set of
representatives of the integral equivalence classes of integral binary
quadratic forms of discriminant . We prove an asymptotic formula for for the average over of the number of representations of by an
integral positive definite quaternary quadratic form and obtain results on
averages of Fourier coefficients of linear combinations of Siegel theta series.
We also find an asymptotic bound from below on the number of binary forms of
fixed discriminant which are represented by a given quaternary form. In
particular, we can show that for growing a positive proportion of the
binary quadratic forms of discriminant is represented by the given
quaternary quadratic form.Comment: v5: Some typos correcte
The subconvexity problem for \GL_{2}
Generalizing and unifying prior results, we solve the subconvexity problem
for the -functions of \GL_{1} and \GL_{2} automorphic representations
over a fixed number field, uniformly in all aspects. A novel feature of the
present method is the softness of our arguments; this is largely due to a
consistent use of canonically normalized period relations, such as those
supplied by the work of Waldspurger and Ichino--Ikeda.Comment: Almost final version to appear in Publ. Math IHES. References
updated
Mass equidistribution of Hilbert modular eigenforms
Let F be a totally real number field, and let f traverse a sequence of
non-dihedral holomorphic eigencuspforms on GL(2)/F of weight (k_1,...,k_n),
trivial central character and full level. We show that the mass of f
equidistributes on the Hilbert modular variety as max(k_1,...,k_n) tends to
infinity.
Our result answers affirmatively a natural analogue of a conjecture of
Rudnick and Sarnak (1994). Our proof generalizes the argument of
Holowinsky-Soundararajan (2008) who established the case F = Q. The essential
difficulty in doing so is to adapt Holowinsky's bounds for the Weyl periods of
the equidistribution problem in terms of manageable shifted convolution sums of
Fourier coefficients to the case of a number field with nontrivial unit group.Comment: 40 pages; typos corrected, nearly accepted for
Dynamic Analysis of Vascular Morphogenesis Using Transgenic Quail Embryos
Background: One of the least understood and most central questions confronting biologists is how initially simple clusters or sheet-like cell collectives can assemble into highly complex three-dimensional functional tissues and organs. Due to the limits of oxygen diffusion, blood vessels are an essential and ubiquitous presence in all amniote tissues and organs. Vasculogenesis, the de novo self-assembly of endothelial cell (EC) precursors into endothelial tubes, is the first step in blood vessel formation [1]. Static imaging and in vitro models are wholly inadequate to capture many aspects of vascular pattern formation in vivo, because vasculogenesis involves dynamic changes of the endothelial cells and of the forming blood vessels, in an embryo that is changing size and shape.
Methodology/Principal Findings: We have generated Tie1 transgenic quail lines Tg(tie1:H2B-eYFP) that express H2B-eYFP in all of their endothelial cells which permit investigations into early embryonic vascular morphogenesis with unprecedented clarity and insight. By combining the power of molecular genetics with the elegance of dynamic imaging, we follow the precise patterning of endothelial cells in space and time. We show that during vasculogenesis within the vascular plexus, ECs move independently to form the rudiments of blood vessels, all while collectively moving with gastrulating tissues that flow toward the embryo midline. The aortae are a composite of somatic derived ECs forming its dorsal regions and the splanchnic derived ECs forming its ventral region. The ECs in the dorsal regions of the forming aortae exhibit variable mediolateral motions as they move rostrally; those in more ventral regions show significant lateral-to-medial movement as they course rostrally.
Conclusions/Significance: The present results offer a powerful approach to the major challenge of studying the relative role(s) of the mechanical, molecular, and cellular mechanisms of vascular development. In past studies, the advantages of the molecular genetic tools available in mouse were counterbalanced by the limited experimental accessibility needed for imaging and perturbation studies. Avian embryos provide the needed accessibility, but few genetic resources. The creation of transgenic quail with labeled endothelia builds upon the important roles that avian embryos have played in previous studies of vascular development
Ubiquitous robust communications for emergency response using multi-operator heterogeneous networks
A number of disasters in various places of the planet have caused an extensive loss of lives, severe damages to properties and the environment, as well as a tremendous shock to the survivors. For relief and mitigation operations, emergency responders are immediately dispatched to the disaster areas. Ubiquitous and robust communications during the emergency response operations are of paramount importance. Nevertheless, various reports have highlighted that after many devastating events, the current technologies used, failed to support the mission critical communications, resulting in further loss of lives. Inefficiencies of the current communications used for emergency response include lack of technology inter-operability between different jurisdictions, and high vulnerability due to their centralized infrastructure. In this article, we propose a flexible network architecture that provides a common networking platform for heterogeneous multi-operator networks, for interoperation in case of emergencies. A wireless mesh network is the main part of the proposed architecture and this provides a back-up network in case of emergencies. We first describe the shortcomings and limitations of the current technologies, and then we address issues related to the applications and functionalities a future emergency response network should support. Furthermore, we describe the necessary requirements for a flexible, secure, robust, and QoS-aware emergency response multi-operator architecture, and then we suggest several schemes that can be adopted by our proposed architecture to meet those requirements. In addition, we suggest several methods for the re-tasking of communication means owned by independent individuals to provide support during emergencies. In order to investigate the feasibility of multimedia transmission over a wireless mesh network, we measured the performance of a video streaming application in a real wireless metropolitan multi-radio mesh network, showing that the mesh network can meet the requirements for high quality video transmissions
Effective in vivo and ex vivo gene transfer to intestinal mucosa by VSV-G-pseudotyped lentiviral vectors
<p>Abstract</p> <p>Background</p> <p>Gene transfer to the gastrointestinal (GI) mucosa is a therapeutic strategy which could prove particularly advantageous for treatment of various hereditary and acquired intestinal disorders, including inflammatory bowel disease (IBD), GI infections, and cancer.</p> <p>Methods</p> <p>We evaluated vesicular stomatitis virus glycoprotein envelope (VSV-G)-pseudotyped lentiviral vectors (LV) for efficacy of gene transfer to both murine rectosigmoid colon <it>in vivo </it>and human colon explants <it>ex vivo</it>. LV encoding beta-galactosidase (LV-β-Gal) or firefly-luciferase (LV-fLuc) reporter genes were administered by intrarectal instillation in mice, or applied topically for <it>ex vivo </it>transduction of human colorectal explant tissues from normal individuals. Macroscopic and histological evaluations were performed to assess any tissue damage or inflammation. Transduction efficiency and systemic biodistribution were evaluated by real-time quantitative PCR. LV-fLuc expression was evaluated by <it>ex vivo </it>bioluminescence imaging. LV-β-Gal expression and identity of transduced cell types were examined by histochemical and immunofluorescence staining.</p> <p>Results</p> <p>Imaging studies showed positive fLuc signals in murine distal colon; β-Gal-positive cells were found in both murine and human intestinal tissue. In the murine model, β-Gal-positive epithelial and lamina propria cells were found to express cytokeratin, CD45, and CD4. LV-transduced β-Gal-positive cells were also seen in human colorectal explants, consisting mainly of CD45, CD4, and CD11c-positive cells confined to the LP.</p> <p>Conclusions</p> <p>We have demonstrated the feasibility of LV-mediated gene transfer into colonic mucosa. We also identified differential patterns of mucosal gene transfer dependent on whether murine or human tissue was used. Within the limitations of the study, the LV did not appear to induce mucosal damage and were not distributed beyond the distal colon.</p
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