In vivo laser Doppler holography of the human retina

The eye offers a unique opportunity for non-invasive exploration of cardiovascular diseases. Optical angiography in the retina requires sensitive measurements, which hinders conventional full-field laser Doppler imaging schemes. To overcome this limitation, we used digital holography to perform laser Doppler perfusion imaging of the human retina in vivo with near-infrared light. Wideband measurements of the beat frequency spectrum of optical interferograms recorded with a 39 kHz CMOS camera are analyzed by short-time Fourier transformation. Power Doppler images and movies drawn from the zeroth moment of the power spectrum density reveal blood flows in retinal and choroidal vessels over 512 $\times$ 512 pixels covering 2.4 $\times$ 2.4 mm$^2$ on the retina with a 13 ms temporal resolution.Comment: 5 pages, 5 figure

Multi-domain service orchestration over networks and clouds: a unified approach

End-to-end service delivery often includes transparently inserted Network Functions (NFs) in the path. Flexible service chaining will require dynamic instantiation of both NFs and traffic forwarding overlays. Virtualization techniques in compute and networking, like cloud and Software Defined Networking (SDN), promise such flexibility for service providers. However, patching together existing cloud and network control mechanisms necessarily puts one over the above, e.g., OpenDaylight under an OpenStack controller. We designed and implemented a joint cloud and network resource virtualization and programming API. In this demonstration, we show that our abstraction is capable for flexible service chaining control over any technology domain

A multi-dimension taxonomy of insider threats in cloud computing

Security is considered a significant deficiency in cloud computing, and insider threats problem exacerbate security concerns in the cloud. In addition to that, cloud computing is very complex by itself, because it encompasses numerous technologies and concepts. Apparently, overcoming these challenges requires substantial efforts from information security researchers to develop powerful mitigation solutions for this emerging problem. This entails developing a taxonomy of insider threats in cloud environments encompassing all potential abnormal activities in the cloud, and can be useful for conducting security assessment. This paper describes the first phase of an ongoing research to develop a framework for mitigating insider threats in cloud computing environments. Primarily, it presents a multidimensional taxonomy of insider threats in cloud computing, and demonstrates its viability. The taxonomy provides a fundamental understanding for this complicated problem by identifying five dimensions, it also supports security engineers in identifying hidden paths, thus determining proper countermeasures, and presents a guidance covers all bounders of insiders threats issue in clouds, hence it facilitates researchers’ endeavours in tackling this problem. For instance, according to the hierarchical taxonomy, clearly many significant issues exist in public cloud, while conventional insider mitigation solutions can be used in private clouds. Finally, the taxonomy assists in identifying future research directions in this emerging area

Pulsatile microvascular blood flow imaging by short-time Fourier transform analysis of ultrafast laser holographic interferometry

We report on wide-field imaging of pulsatile microvascular blood flow in the exposed cerebral cortex of a mouse by holographic interferometry. We recorded interferograms of laser light backscattered by the tissue, beating against an off-axis reference beam with a 50 kHz framerate camera. Videos of local Doppler contrasts were rendered numerically by Fresnel transformation and short-time Fourier transform analysis. This approach enabled instantaneous imaging of pulsatile blood flow contrasts in superficial blood vessels over 256 x 256 pixels with a spatial resolution of 10 microns and a temporal resolution of 20 ms.Comment: 4 page

Translational Retinal Research and Therapies.

The following review summarizes the state of the art in representative aspects of gene therapy/translational medicine and evolves from a symposium held at the School of Veterinary Medicine, University of Pennsylvania on November 16, 2017 honoring Dr. Gustavo Aguirre, recipient of ARVO's 2017 Proctor Medal. Focusing on the retina, speakers highlighted current work on moving therapies for inherited retinal degenerative diseases from the laboratory bench to the clinic

Scalable architecture for service function chain orchestration

Network Function Virtualization (NFV) enables to implement network functions in software, high-speed packet processing functions which traditionally are dominated by hardware implementations. Virtualized Network Functions (NFs) may be deployed on generic-purpose servers, e.g., in datacenters. The latter enables flexibility and scalability which previously were only possible for web services deployed on cloud platforms. The merit of NFV is challenged by control challenges related to the selection of NF implementations, discovery and reservation of sufficient network and server resources, and interconnecting both in a way which fulfills SLAs related to reliability and scalability. This paper details the role of a scalable orchestrator in charge of finding and reserving adequate resources. The latter will steer network and cloud control and management platforms to actually reserve and deploy requested services. We highlight the role of involved interfaces, propose elements of algorithmic components, and will identify major blocks in orchestration time in a proof of concept prototype which accounts for most functional parts in the considered architecture. Based on these evaluations, we propose several architectural enhancements in order to implement a highly scalable network orchestrator for carrier and cloud networks

On the experimentation of the novel GCMR multicast routing in a large-scale testbed

Originally defined in the 90s, multicast is nowadays (re)gaining interest given the increasing popularity of multimedia streaming/content traffic and the explosion of cloud services. In fact, multicast yields bandwidth savings complementing cached content distribution techniques and its potential benefits have been verified by studies several times since then (see e.g. [1]). By multicast routing, we refer to a distributed algorithm that, given a group identifier, allows any node to route multicast traffic to a group of destination nodes, usually called multicast group. To enable one-to-many traffic distribution, the multicast routing protocol configures the involved routers to build a (logical) delivery tree between the source and the multicast group, commonly referred to as the Multicast Distribution Tree (MDT). Nevertheless, the scaling problems faced in the 90s still remain mostly unaddressed and worst-case projections predict indeed that routing engines could have to process and maintain in the order of 1 million active routes within the next 5 years [2].This work has been partially funded by the EULER FP7-258307 and DOMINO (TEC2010-18522) projects.Peer ReviewedPostprint (author's final draft

Implementing general measurements on linear optical and solid-state qubits

We show a systematic construction for implementing general measurements on a single qubit, including both strong (or projection) and weak measurements. We mainly focus on linear optical qubits. The present approach is composed of simple and feasible elements, i.e., beam splitters, wave plates, and polarizing beam splitters. We show how the parameters characterizing the measurement operators are controlled by the linear optical elements. We also propose a method for the implementation of general measurements in solid-state qubits.Comment: 8 pages, 3 figure

Rabi oscillations in a qubit coupled to a quantum two-level system

We consider the problem of a qubit driven by a harmonically oscillating external field while it is coupled to a quantum two-level system (TLS). We perform a systematic numerical analysis of the problem by varying the relevant parameters. The numerical calculations agree with the predictions of a simple intuitive picture, namely one that takes into consideration the four-level energy spectrum, the simple principles of Rabi oscillations and the basic effects of decoherence. Furthermore, they reveal a number of other interesting phenomena. We provide explanations for the various features that we observe in the numerical calculations and discuss how they can be used in experiment. In particular, we suggest an experimental procedure to characterize an environment of TLSs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49057/2/njp6_6_103.pd