Coupling DSM-based Parallel Applications

When coupling applications running on distributed memory architectures or clusters, the coupling library must adapt to the distribution of the data in the memory of each computation node. The library must be prepared to redistribute the data when the coupled applications use different data mappings or when the number of processors of the two architectures are different. Mome is a user-level software DSM which allows programs running on a distributed memory architecture or cluster to create segments and to share data objects through memory mapping. The segments of the DSM form a simple linear address space where all shared objects of applications are allocated. The Mome coupling library accesses the data through mappings of the DSM segments on the memories of the communication threads. The parallel communication threads are distributed on the computation nodes and exploit the communication capacity of each processor. The data are moved directly between the DSM segments and the transfers do not rely on any knowledge on the application use of these segments

Miniature, High Efficiency Transducers For Use IN Ultrasonic Flow Meters

This thesis is concerned with the development of a new type of miniature, high efficiency transducer for use in ultrasonic flow meters. The proposed transducer consists of a thin plate of a suitable piezoelectric material on which an inter-digital transducer is fabricated for the generation and detection of plate acoustic waves. When immersed in a fluid medium, this device can convert energy from plate acoustic waves (PAWs) into bulk acoustic waves (BAWs) and vice versa. It is shown that this mode coupling principle can be used to realize efficient transducers for use in ultrasonic flow meters. This transducer can be mounted flush with the walls of the pipe through which fluid is flowing, resulting in minimal disturbance of fluid flow. A prototype flow cell using these transducers has been designed and fabricated. The characteristics of this device have been measured over water flow rates varying from 0 to 7.5 liters per minute and found to be in good agreement with theory. Another attractive property of the new transducers is that they can be used to realize remotely read, passive, wireless flow meters. Details of methods that can be used to develop this wireless capability are described. The research carried out in this thesis has applications in several other areas such as ultrasonic nondestructive evaluation (NDE), noncontact or air coupled ultrasonics, and for developing wireless capability in a variety of other acoustic wave sensors

Photoacoustically guided wavefront shaping for enhanced optical focusing in scattering media

Non-invasively focusing light into strongly scattering media, such as biological tissue, is highly desirable but challenging. Recently, ultrasonically guided wavefront-shaping technologies have been developed to address this limitation. So far, the focusing resolution of most implementations has been limited by acoustic diffraction. Here, we introduce nonlinear photoacoustically guided wavefront shaping (PAWS), which achieves optical diffraction-limited focusing in scattering media. We develop an efficient dual-pulse excitation approach to generate strong nonlinear photoacoustic signals based on the Grueneisen relaxation effect. These nonlinear photoacoustic signals are used as feedback to guide iterative wavefront optimization. As a result, light is effectively focused to a single optical speckle grain on the scale of 5–7 μm, which is ∼10 times smaller than the acoustic focus, with an enhancement factor of ∼6,000 in peak fluence. This technology has the potential to benefit many applications that require a highly confined strong optical focus in tissue

Modularity for Large Virtual Reality Applications

International audienceThis paper focuses on the design of high performance VR applications. These applications usually involve various I/O devices and complex simulations. A parallel architecture or grid infrastructure is required to provide the necessary I/O and processing capabilities. Developing such applications faces several difficulties, two important ones being software engineering and performance issues. We argue that application modularity is a key concept to help the developer handle the complexity of these applications. We discuss how various approaches borrowed from other existing works can be combined to significantly improve the modularity of VR applications. This led to the development of the FlowVR middleware that associates a data-flow model with a hierarchical component model. Different case studies are presented to discuss the benefits of the approach proposed

Coupling DSM-based Parallel Applications

When coupling applications running on distributed memory architectures or clusters, the coupling library must adapt to the distribution of the data in the memory of each computation node. The library must be prepared to redistribute the data when the coupled applications use different data mappings or when the number of processors of the two architectures are different. Mome is a user-level software DSM which allows programs running on a distributed memory architecture or cluster to create segments and to share data objects through memory mapping. The segments of the DSM form a simple linear address space where all shared objects of applications are allocated. The Mome coupling library accesses the data through mappings of the DSM segments on the memories of the communication threads. The parallel communication threads are distributed on the computation nodes and exploit the communication capacity of each processor. The data are moved directly between the DSM segments and the transfers do not rely on any knowledge on the application use of these segments

Polyglycerol-opioid conjugate produces analgesia devoid of side effects

Novel painkillers are urgently needed. The activation of opioid receptors in peripheral inflamed tissue can reduce pain without central adverse effects such as sedation, apnoea, or addiction. Here, we use an unprecedented strategy and report the synthesis and analgesic efficacy of the standard opioid morphine covalently attached to hyperbranched polyglycerol (PG-M) by a cleavable linker. With its high-molecular weight and hydrophilicity, this conjugate is designed to selectively release morphine in injured tissue and to prevent blood-brain barrier permeation. In contrast to conventional morphine, intravenous PG-M exclusively activated peripheral opioid receptors to produce analgesia in inflamed rat paws without major side effects such as sedation or constipation. Concentrations of morphine in the brain, blood, paw tissue, and in vitro confirmed the selective release of morphine in the inflamed milieu. Thus, PG-M may serve as prototype of a peripherally restricted opioid formulation designed to forego central and intestinal side effects

Light manipulation through periodic plasmonic corrugations

textCollective oscillations of free electrons localized in a small volume have drawn a lot of attention for the past decades. These so-called plasmons have special optical properties that can be used in many applications ranging from optical modulators to sensing of small quantities of molecules. Large numbers of extensive plasmonic applications are being based on the capability of light manipulation proposed by the periodic nanostructure and its optical response. By controlling over the way in which plasmonic modes interact with incident radiation, periodic corrugation opens up the possibility of developing new and exciting photonic devices. The goal of doctoral research presented herein is to investigate at a fundamental level of several corrugated metallic structures which may offer effective control of the optical response by coupling radiation to plasmonic modes. By controlling morphologies and material compositions, sophisticatedly engineered nanostructure may allow the coupling of electromagnetic waves into desired spectral/spatial modes in a way that an effective tuning of macroscopic optical properties in desired domain can be achieved. This dissertation is dedicated to answer the following question, if and how one can manipulate the optical responses by use of different nanostructures and various materials. Based on devised analytical models proposed for various corrugated nanostructures, we show that I. spatial and II. spectral manipulation of light can be realized. Specifically, we investigate how the grating array interacts with light. To understand those periodic nanostructures showing inherently dispersive nature, firstly the diffraction of light and accompanying effects are studied with the analytical models and numerical simulation. On this basis, we show the optical response is readily tunable, and efficiently controlled by the morphology and dielectric property of the corrugations. The outline of doctoral research is broadly categorized into (1) theoretical considerations on the topic of plasmonics, (2) specific insight in the analytical model of the various nanostructures, and (3) investigation of the plasmonic properties of the fabricated structures. Lastly, the discussion of outlook to possibilities and future experiments will close the dissertation.Electrical and Computer Engineerin

The Boston University Photonics Center annual report 2013-2014

This repository item contains an annual report that summarizes activities of the Boston University Photonics Center in the 2013-2014 academic year. The report provides quantitative and descriptive information regarding photonics programs in education, interdisciplinary research, business innovation, and technology development. The Boston University Photonics Center (BUPC) is an interdisciplinary hub for education, research, scholarship, innovation, and technology development associated with practical uses of light.This annual report summarizes activities of the Boston University Photonics Center in the 2013–2014 academic year.This has been a good year for the Photonics Center. In the following pages, you will see that the center’s faculty received prodigious honors and awards, generated more than 100 notable scholarly publications in the leading journals in our field, and attracted $14.5M in new research grants and contracts this year. Faculty and staff also expanded their efforts in education and training, through National Science Foundation–sponsored sites for Research Experiences for Undergraduates and for Teachers. As a community, we hosted a compelling series of distinguished invited speakers, and emphasized the theme of Innovations at the Intersections of Micro/Nanofabrication Technology, Biology, and Biomedicine at our annual Future of Light Symposium. We took a leadership role in running national workshops on emerging photonic fields, including an OSA Incubator on Controlled Light Propagation through Complex Media, and an NSF Workshop on Noninvasive Imaging of Brain Function. Highlights of our research achievements for the year include a distinctive Presidential Early Career Award for Scientists and Engineers (PECASE) for Assistant Professor Xue Han, an ambitious new DoD-sponsored grant for Multi-Scale Multi-Disciplinary Modeling of Electronic Materials led by Professor Enrico Bellotti, launch of our NIH-sponsored Center for Innovation in Point of Care Technologies for the Future of Cancer Care led by Professor Cathy Klapperich, and successful completion of the ambitious IARPA-funded contract for Next Generation Solid Immersion Microscopy for Fault Isolation in Back-Side Circuit Analysis led by Professor Bennett Goldberg. These three programs, which represent more than$20M in research funding for the University, are indicative of the breadth of Photonics Center research interests: from fundamental modeling of optoelectronic materials to practical development of cancer diagnostics, from exciting new discoveries in optogenetics for understanding brain function to the achievement of world-record resolution in semiconductor circuit microscopy. Our community welcomed an auspicious cohort of new faculty members, including a newly hired assistant professor and a newly hired professor (and Chair of the Mechanical Engineering Department). The Industry/University Cooperative Research Center—the centerpiece of our translational biophotonics program—continues to focus on advancing the health care and medical device industries, and has entered its fourth year of operation with a strong record of achievement and with the support of an enthusiastic industrial membership base