Extraordinary all-dielectric light enhancement over large volumes

We present resonant dielectric structures exhibiting arbitrarily large optical field enhancement, only limited by fabrication imperfections. Three different arrangements are investigated, based upon dielectric waveguides, dielectric particle arrays, and a combination of these two structures. Experimental confirmation of enhancement in a waveguide resonator is achieved by measuring the luminescence of quantum dots dispersed in the hot optical region of the structure. The performance of these systems can be readily controlled by simply changing geometrical parameters, which allows obtaining remarkable values of the intensity enhancement approaching 105 relative to the incident intensity over large volumes under feasible experimental conditions. This opens new avenues for all-optical switching and biosensing.     

Controlling light localization and light-matter interactions with nanoplasmonics

Nanoplasmonics is the emerging research field that studies light-matter interactions mediated by resonant excitations of surface plasmons in metallic nanostructures. It allows the manipulation of the flow of light and its interaction with matter at the nanoscale (10(-9) m). One of the most promising characteristics of plasmonic resonances is that they occur at frequencies corresponding to typical electronic excitations in matter. This leads to the appearance of strong interactions between localized surface plasmons and light emitters (such as molecules, dyes, or quantum dots) placed in the vicinity of metals. Recent advances in nanofabrication and the development of novel concepts in theoretical nanophotonics have opened the way to the design of structures aimed to reduce the lifetime and enhance the decay rate and quantum efficiency of available emitters. In this article, some of the most relevant experimental and theoretical achievements accomplished over the last several years are presented and analyzed.     

The Fibrillar Matrix: Novel Avenues for Breast Cancer Detection and Treatment

Breast cancer is marked by large increases in the protein fibers around tumor cells. These fibers increase the mechanical stiffness of the tissue, which has long been used for tumor diagnosis by manual palpation. Recent research in bioengineering has led to the development of novel biomaterials that model the mechanical and architectural properties of the tumor microenvironment and can be used to understand how these cues regulate the growth and spread of breast cancer. Herein, we provide an overview of how the mechanical properties of breast tumor tissues differ from those of normal breast tissue and non-cancerous lesions. We also describe how biomaterial models make it possible to understand how the stiffness and viscosity of the extracellular environment regulate cell migration and breast cancer metastasis. We highlight the need for biomaterial models that allow independent analysis of the individual and different mechanical properties of the tumor microenvironment and that use cells derived from different regions within tumors. These models will guide the development of novel mechano-based therapies against breast cancer metastasis.     

Confocal laser scanning microscopy for the study of the morphological changes of the postextraction sites

A better understanding of the remodeling process of postextraction sockets is essential in dental treatment planning. The aim of this study was to evaluate whether confocal laser scanning microscopy (CLSM) can be applied to imaging contour changes of postextraction sites, as well as to its quantification with image analysis of obtained three‐dimensional images. This work describes a new application of the CLSM technique. The system used was the OLS3100‐USS, LEXT model (Olympus®). CLSM was used for the surface analysis of the extraction site. The measurements taken with CLSM were: (1) mesio‐distal distance, (2) alveolar ridge thickness, and (3) vestibular and lingual alveolar ridge height. Results of study cast scanning at baseline, 1 and 3 months after tooth extraction, with CLSM are well‐detailed images of postextraction areas. The CLSM technique used in study casts is a valid method to measure the dimensional changes that happen in the edentulous area after tooth extraction. This technique allows the evaluation of changes in mesio‐distal distance, thickness of the alveolar ridge and alveolar ridge height based on the measurements on the alveolar contours. Microsc. Res. Tech., 2011. © 2011 Wiley‐Liss, Inc.     

Wastewater treatment from biodiesel production via a coupled photo-Fenton-aerobic sequential batch reactor (SBR) system

A coupled system of the photo-Fenton advanced oxidation technique and an aerobic sequential batch reactor (SBR) was used to treat wastewater from biodiesel production using either palm or castor oil. The photo-Fenton reaction and biological process were evaluated individually and were effective at treating the wastewater; nevertheless, each process required longer degradation times for the wastewater pollutants compared with the coupled system. The proposed coupled photo-Fenton/aerobic SBR system obtained a 90% reduction of the chemical oxygen demand (COD) in half of the time required for the biological system individually.     

立洲拱坝坝肩稳定破坏试验研究

立洲水电站是木里河干流水电规划的重要梯级电站,该工程的大坝为碾压混凝土双曲拱坝,最大坝高132m,坝址区地质条件较为复杂。为了研究该拱坝与地基的整体稳定问题,采用了三维地质力学模型超载法试验,在模型中充分反映断层、层间剪切带、长大裂隙及裂隙带等复杂地质构造对坝与地基整体稳定的影响,而且在试验过程中将光纤光栅传感器布置在坝顶及上游坝面,监测坝体超载过程中的应变,从而分析坝体的开裂破坏过程。试验研究获得了坝肩抗力体变位分布特征,确定了拱坝与地基的超载安全系数和坝肩破坏形态,为工程的设计和施工提供了科学依据。     

基于流固耦合的垂直轴风机受力分析

为了通过流固耦合分析,探讨风机建筑一体化中垂直轴风力机叶片和主轴的受力情况,结合实际工程,在结构分析软件ANSYS Workbench[l1]中运用单向流固耦合的方法分别对风速是10m/s和50m/s时的风机叶片和主轴的静应力进行了计算分析和比较。结果表明:各种工况下,风力机叶片的最大静应力出现在叶片与主轴连接处,风力发电机叶片和主轴的最大静应力随着风速的增加而变大。静应力最高值远小于材料的屈服极限,所以静应力不会使风机叶片和主轴结构产生破坏。叶片与主轴的连接处都出现了应力集中现象,为了防止疲劳破坏,可以适当地加厚叶片和主轴连接处的厚度。     

Software architecture for multi-bed FDK-based reconstruction in X-ray CT scanners

Most small-animal X-ray computed tomography (CT) scanners are based on cone-beam geometry with a flat-panel detector orbiting in a circular trajectory. Image reconstruction in these systems is usually performed by approximate methods based on the algorithm proposed by Feldkamp et al. (FDK). Besides the implementation of the reconstruction algorithm itself, in order to design a real system it is necessary to take into account numerous issues so as to obtain the best quality images from the acquired data. This work presents a comprehensive, novel software architecture for small-animal CT scanners based on cone-beam geometry with circular scanning trajectory. The proposed architecture covers all the steps from the system calibration to the volume reconstruction and conversion into Hounsfield units. It includes an efficient implementation of an FDK-based reconstruction algorithm that takes advantage of system symmetries and allows for parallel reconstruction using a multiprocessor computer. Strategies for calibration and artifact correction are discussed to justify the strategies adopted. New procedures for multi-bed misalignment, beam-hardening, and Housfield units calibration are proposed. Experiments with phantoms and real data showed the suitability of the proposed software architecture for an X-ray small animal CT based on cone-beam geometry.     

Effcient Handling of Lock Hand-off in DSM Multiprocessors with Buffering Coherence Controllers

Synchronization in parallel programs is a major performance bottleneck in multiprocessor systems. Shared data is protected by locks and a lot of time is spent on the competition arising at the lock hand-off. In order to be serialized, requests to the same cache line can either be bounced (NACKed) or buffered in the coherence controller. In this paper, we focus mainly on systems whose coherence controllers buffer requests. In a lock hand-off, a burst of requests to the same line arrive at the coherence controller. During lock hand-off only the requests from the winning processor contribute to progress of the computation, since the winning processor is the only one that will advance the work. This key observation leads us to propose a hardware mechanism we call request bypassing, which allows requests from the winning processor to bypass the requests buffered in the coherence controller keeping the lock line. We present an inexpensive implementation of request bypassing that reduces the time spent on all the execution phases of a critical section (acquiring the lock, accessing shared data, and releasing the lock) and which, as a consequence, speeds up the whole parallel computation. This mechanism requires neither compiler or programmer support nor ISA or coherence protocol changes. By simulating a 32-processor system, we show that using request bypassing does not degrade but rather improves performance in three applications with low synchronization rates, while in those having a large amount of synchronization activity (the remaining four), we see reductions in execution time and in lock stall time ranging from 14% to 39% and from 52% to 71%, respectively. We compare request bypassing with a previously proposed technique called read combining and with a system that bounces requests, observing a significantly lower execution time with the bypassing scheme. Finally, we analyze the sensitivity of our results to some key hardware and software parameters.