X-ray Diffraction Tomographic Imaging and Reconstruction

Material discrimination based on conventional or dual energy X-ray computed tomography (CT) imaging can be ambiguous. X-ray diffraction imaging (XDI) can be used to construct diffraction profiles of objects, providing new molecular signature information that can be used to characterize the presence of specific materials. Combining X-ray CT and diffraction imaging can lead to enhanced detection and identification of explosives in luggage screening. In this work we are investigating techniques for joint reconstruction of CT absorption and X-ray diffraction profile images of objects to achieve improved image quality and enhanced material classification. The initial results have been validated via simulation of X-ray absorption and coherent scattering in 2 dimensions.U. S. Department of Homeland Security (2008-ST-061-ED0001

Asynchronous Auction for Distributed Nonlinear Resource Allocation Problem

Resource Allocation Problems (RAPs) are concerned with the optimal allocation of resources to tasks. Problems in fields such as search theory, statistics, finance, economics, logistics, sensor & wireless networks fit this formulation. In literature, several centralized/synchronous algorithms have been proposed including recently proposed auction algorithm, RAP Auction. Here we present asynchronous implementation of RAP Auction for distributed RAPs.Air Force Office of Scientific Research (FA9550-07-1-0361) and Office of the Director, Defense Research and Engineering (Multidisciplinary University Research Initiative Grant FA9550-06-1-0324

Exploratory search through large video corpora

Activity retrieval is a growing field in electrical engineering that specializes in the search and retrieval of relevant activities and events in video corpora. With the affordability and popularity of cameras for government, personal and retail use, the quantity of available video data is rapidly outscaling our ability to reason over it. Towards the end of empowering users to navigate and interact with the contents of these video corpora, we propose a framework for exploratory search that emphasizes activity structure and search space reduction over complex feature representations. Exploratory search is a user driven process wherein a person provides a system with a query describing the activity, event, or object he is interested in finding. Typically, this description takes the implicit form of one or more exemplar videos, but it can also involve an explicit description. The system returns candidate matches, followed by query refinement and iteration. System performance is judged by the run-time of the system and the precision/recall curve of of the query matches returned. Scaling is one of the primary challenges in video search. From vast web-video archives like youtube (1 billion videos and counting) to the 30 million active surveillance cameras shooting an estimated 4 billion hours of footage every week in the United States, trying to find a set of matches can be like looking for a needle in a haystack. Our goal is to create an efficient archival representation of video corpora that can be calculated in real-time as video streams in, and then enables a user to quickly get a set of results that match. First, we design a system for rapidly identifying simple queries in large-scale video corpora. Instead of focusing on feature design, our system focuses on the spatiotemporal relationships between those features as a means of disambiguating an activity of interest from background. We define a semantic feature vocabulary of concepts that are both readily extracted from video and easily understood by an operator. As data streams in, features are hashed to an inverted index and retrieved in constant time after the system is presented with a user's query. We take a zero-shot approach to exploratory search: the user manually assembles vocabulary elements like color, speed, size and type into a graph. Given that information, we perform an initial downsampling of the archived data, and design a novel dynamic programming approach based on genome-sequencing to search for similar patterns. Experimental results indicate that this approach outperforms other methods for detecting activities in surveillance video datasets. Second, we address the problem of representing complex activities that take place over long spans of space and time. Subgraph and graph matching methods have seen limited use in exploratory search because both problems are provably NP-hard. In this work, we render these problems computationally tractable by identifying the maximally discriminative spanning tree (MDST), and using dynamic programming to optimally reduce the archive data based on a custom algorithm for tree-matching in attributed relational graphs. We demonstrate the efficacy of this approach on popular surveillance video datasets in several modalities. Finally, we design an approach for successive search space reduction in subgraph matching problems. Given a query graph and archival data, our algorithm iteratively selects spanning trees from the query graph that optimize the expected search space reduction at each step until the archive converges. We use this approach to efficiently reason over video surveillance datasets, simulated data, as well as large graphs of protein data

Beyond Binomial and Negative Binomial: Adaptation in Bernoulli Parameter Estimation

Estimating the parameter of a Bernoulli process arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. Motivated by acquisition efficiency when multiple Bernoulli processes are of interest, we formulate the allocation of trials under a constraint on the mean as an optimal resource allocation problem. An oracle-aided trial allocation demonstrates that there can be a significant advantage from varying the allocation for different processes and inspires a simple trial allocation gain quantity. Motivated by realizing this gain without an oracle, we present a trellis-based framework for representing and optimizing stopping rules. Considering the convenient case of Beta priors, three implementable stopping rules with similar performances are explored, and the simplest of these is shown to asymptotically achieve the oracle-aided trial allocation. These approaches are further extended to estimating functions of a Bernoulli parameter. In simulations inspired by realistic active imaging scenarios, we demonstrate significant mean-squared error improvements: up to 4.36 dB for the estimation of p and up to 1.80 dB for the estimation of log p.Comment: 13 pages, 16 figure

An ultra-sensitive aptasensor on optical fibre for the direct detection of Bisphenol A

We present a plasmonic biosensor capable of detecting the presence of bisphenol A in ultralow concentrations, yielding a wavelength shift of 0.15±0.01 nm in response to a solution of 1 fM concentration with limit of detection of 330±70 aM. The biosensing device consists of an array of gold nano-antennae with a total length of 2.3cm that generate coupled localised surface plasmons (cLSPs) and is covalently modified with an aptamer specific for bisphenol A recognition. The array of nanoantennae is fabricated on a lapped section of standard telecommunication optical fibre, allowing for potential multiplexing and its use in remote sensing applications. These results have been achieved without the use of enhancement techniques and therefore the approach allows the direct detection of bisphenol A, a low molecular weight (228 Da) target usually detectable only by indirect detection strategies. Its detection at such levels is a significant step forward in measuring small molecules at ultralow concentrations. Furthermore, this new sensing platform paves the way for the development of portable systems for in-situ agricultural measurements capable of retrieving data on a substance of very high concern at ultra-low concentrations

Relevance of infections on the outcomes of patients with myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia treated with hypomethylating agents: a cohort study from the GESMD

Hypomethylating agent; Infection; Myelodysplastic syndromeAgente hipometilante; Infección; Síndrome mielodisplásicoAgent hipometilant; Infecció; Síndrome mielodisplàsticBackground: The consequences of infectious toxicity of hypomethylating agents (HMAs) on overall survival (OS) of patients diagnosed with high-risk myeloid neoplasms have not been thoroughly investigated. Objectives: We aimed to evaluate whether infectious events (IEs) negatively influenced the results of HMA treatment in a real-world setting. Design: Observational study. Methods: We obtained data from 412 non-selected consecutive patients from 23 Spanish hospitals who were diagnosed with high-risk myelodysplastic syndrome, chronic myelomonocytic leukemia, or acute myeloid leukemia and were treated with HMA. HMAs received after chemotherapy or stem cell transplant were excluded. All IEs were recorded. Outcomes included OS, modifications to the pre-planned treatment, incidence and characteristics of IEs, hospitalization, red blood cell transfusions, and factors associated with infection. Results: The rate of infection was 1.2 per patient/year. Next-cycle delay (p = 0.001) and hospitalizations (p = 0.001) were significantly influenced by IEs. Transfusion requirements during each cycle were significantly higher after infection compared with cycles without infection (coefficient = 1.55 [95% confidence interval (CI) = 1.26–1.84], p 20% (HR = 1.57 [95% CI = 1.19–2.01], p 9 g/dl (HR = 0.65 [95% CI = 0.51–0.82], p < 0.001) and higher platelet count (HR = 0.997 [95% CI = 0.996–0.998], p = 0.016) protected from it. Conclusion: HMA infectious toxicity worsens OS, hinders the adherence to antineoplastic treatment and results in significant morbidity. Preventive strategies are fundamental in vulnerable patients

Generation of a Conjoint Surface Plasmon by an Infrared Nano‐antenna Array

Localized surface plasmons (LSP) excited by optical fields have many potential applications resulting from their ability in detecting ultra‐small, ambient refractive index change. Current methods using surface nano‐patterning by means of lithography have given rise to LSP of limited propagation and interaction lengths, meaning that practical applications remain challenging. This paper describes a new all‐optical method of generating LSP by means of a carefully fabricated low dimensional nano‐structured material by using a direct‐write photochemical lithography. It is shown that the resulting array of localized surface plasmons combine or “Conjoin” to have an unprecedented large interaction length, via coupled evanescent fields, giving rise to superior spectral sensitivities; several orders of magnitude better than those quoted elsewhere and reaching 6×103 nm/RIU in the aqueous regime and 104 nm/RIU in the gaseous regime. Numerical modeling was performed that showed this design of plasmonic platform is capable of producing sensitivities of 105‐106 nm/RIU. We believe the results achieved in this investigation show that a unique conjoint surface plasmon operational mode will significantly impact areas of interest, such as single molecular dynamics, drug delivery systems etc

3D numerical simulation of slope-flexible system interaction using a mixed FEM-SPH model

Flexible membranes are light structures anchored to the ground that protect infrastructures or dwellings from rock or soil sliding. One alternative to design these structures is by using numerical simulations. However, very few models were found until date and most of them are in 2D and do not include all their components. This paper presents the development of a numerical model combining Finite Element Modelling (FEM) with Smooth Particle Hydrodynamics (SPH) formulation. Both cylindrical and spherical failure of the slope were simulated. One reference geometry of the slope was designed and a total of 21 slip circles were calculated considering different soil parameters, phreatic level position and drainage solutions. Four case studies were extracted from these scenarios and simulated using different dimensions of the components of the system. As a validation model, an experimental test that imitates the soil detachment and its retention by the steel membrane was successfully reproduced

Síntesis y análisis estructural de la perovskita inorgánico libre de plomo Bi0.5Na0.5TiO3 dopada con praseodimio al 0.4% mol por el método de citratos

Bi0.5Na0.5TiO3 praseodymium doped at 0.4% mol was synthesized by the citrates method, structure characterization show the secondary phase, identifying it in the structural analysis, it was also found that the rhombohedral phase promoted by bismuth as opposed to the cubic phase corresponding to that formed by sodium. These results show the importance of materials science for the design of new functional materials with application in photovoltaic devicesResumen: Se sintetizo el material Bi0.5Na0.5TiO3 dopado con praseodimio al 0.4% mol por el método de citratos, para posteriormente caracterizar su estructura encontrando la presencia de fase secundaria e identificándola en el análisis estructural, asimismo se encontró que predomina la fase romboédrica promovida por el bismuto en contraposición a la fase cubica correspondiente a la formada por el sodio. Estos resultados muestran la importancia de la ciencia de materiales para el diseño de nuevos materiales funcionales con aplicación en dispositivos fotovoltaicos