1,911 research outputs found

    Foreign Object Detection and Quantification of Fat Content Using A Novel Multiplexing Electric Field Sensor

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    There is an ever growing need to ensure the quality of food and assess specific quality parameters in all the links of the food chain, ranging from processing, distribution and retail to preparing food. Various imaging and sensing technologies, including X-ray imaging, ultrasound, and near infrared reflectance spectroscopy have been applied to the problem. Cost and other constraints restrict the application of some of these technologies. In this study we test a novel Multiplexing Electric Field Sensor (MEFS), an approach that allows for a completely non-invasive and non-destructive testing approach. Our experiments demonstrate the reliable detection of certain foreign objects and provide evidence that this sensor technology has the capability of measuring fat content in minced meat. Given the fact that this technology can already be deployed at very low cost, low maintenance and in various different form factors, we conclude that this type of MEFS is an extremely promising technology for addressing specific food quality issues

    50 Years of Spaceflight with Fourier Transform Spectrometers (FTS) Built at NASA GSFC

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    Over the past 50 years, NASA Goddard Space Flight Center (GSFC) has been developing, building, testing and flying a series of Fourier Transform Spectrometers (FTS). This began with the IRIS instruments on the Earth-orbiting Nimbus satellites and progressed to more sophisticated designs optimized for interplanetary spacecraft sent to Mars and later to the outer solar system. Adaptions have been made over time, including progressively higher spectral resolution, sensitivity, numbers of detectors and complexity. Instrument operating temperatures have decreased to enable remote sensing of the cold giant planet systems. In this paper we describe the historical evolution of this instrument line, comparing and contrasting different aspects such as optical design and materials, detector types and data handling. We conclude by looking towards the future. At present the CIRS-Lite prototype is being tested at NASA GSFC for potential use on a future mission to the ice giants, Uranus and Neptune. Surpassing the previous performance of the Voyager IRIS instruments remains challenging, and new technologies that could enable these measurements are discussed

    Specification and Simulation of Statistical Query Algorithms for Efficiency and Noise Tolerance

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    AbstractA recent innovation in computational learning theory is the statistical query (SQ) model. The advantage of specifying learning algorithms in this model is that SQ algorithms can be simulated in the probably approximately correct (PAC) model, both in the absenceandin the presence of noise. However, simulations of SQ algorithms in the PAC model have non-optimal time and sample complexities. In this paper, we introduce a new method for specifying statistical query algorithms based on a type ofrelative errorand provide simulations in the noise-free and noise-tolerant PAC models which yield more efficient algorithms. Requests for estimates of statistics in this new model take the following form: ā€œReturn an estimate of the statistic within a 1Ā±Ī¼factor, or return āŠ„, promising that the statistic is less thanĪø.ā€ In addition to showing that this is a very natural language for specifying learning algorithms, we also show that this new specification is polynomially equivalent to standard SQ, and thus, known learnability and hardness results for statistical query learning are preserved. We then give highly efficient PAC simulations of relative error SQ algorithms. We show that the learning algorithms obtained by simulating efficient relative error SQ algorithms both in the absence of noise and in the presence of malicious noise have roughly optimal sample complexity. We also show that the simulation of efficient relative error SQ algorithms in the presence of classification noise yields learning algorithms at least as efficient as those obtained through standard methods, and in some cases improved, roughly optimal results are achieved. The sample complexities for all of these simulations are based on thedĪ½metric, which is a type of relative error metric useful for quantities which are small or even zero. We show that uniform convergence with respect to thedĪ½metric yields ā€œuniform convergenceā€ with respect to (Ī¼,Ā Īø) accuracy. Finally, while we show that manyspecificlearning algorithms can be written as highly efficient relative error SQ algorithms, we also show, in fact, thatallSQ algorithms can be written efficiently by proving general upper bounds on the complexity of (Ī¼,Ā Īø) queries as a function of the accuracy parameterĪµ. As a consequence of this result, we give general upper bounds on the complexity of learning algorithms achieved through the use of relative error SQ algorithms and the simulations described above

    General Bounds on Statistical Query Learning and PAC Learning with Noise via Hypothesis Boosting

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    AbstractWe derive general bounds on the complexity of learning in the statistical query (SQ) model and in the PAC model with classification noise. We do so by considering the problem of boosting the accuracy of weak learning algorithms which fall within the SQ model. This new model was introduced by Kearns to provide a general framework for efficient PAC learning in the presence of classification noise. We first show a general scheme for boosting the accuracy of weak SQ learning algorithms, proving that weak SQ learning is equivalent to strong SQ learning. The boosting is efficient and is used to show our main result of the first general upper bounds on the complexity of strong SQ learning. Since all SQ algorithms can be simulated in the PAC model with classification noise, we also obtain general upper bounds on learning in the presence of classification noise for classes which can be learned in the SQ model

    A Near-Infrared and Thermal Imager for Mapping Titan's Surface Features

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    Approximately 10% of the solar insolation reaches the surface of Titan through atmospheric spectral windows. We will discuss a filter based imaging system for a future Titan orbiter that will exploit these windows mapping surface features, cloud regions, polar storms. In the near-infrared (NIR), two filters (1.28 micrometer and 1.6 micrometer), strategically positioned between CH1 absorption bands, and InSb linear array pixels will explore the solar reflected radiation. We propose to map the mid, infrared (MIR) region with two filters: 9.76 micrometer and 5.88-to-6.06 micrometers with MCT linear arrays. The first will map MIR thermal emission variations due to surface albedo differences in the atmospheric window between gas phase CH3D and C2H4 opacity sources. The latter spans the crossover spectral region where observed radiation transitions from being dominated by thermal emission to solar reflected light component. The passively cooled linear arrays will be incorporated into the focal plane of a light-weight thin film stretched membrane 10 cm telescope. A rad-hard ASIC together with an FPGA will be used for detector pixel readout and detector linear array selection depending on if the field-of-view (FOV) is looking at the day- or night-side of Titan. The instantaneous FOV corresponds to 3.1, 15.6, and 31.2 mrad for the 1, 5, and 10 micrometer channels, respectively. For a 1500 km orbit, a 5 micrometer channel pixel represents a spatial resolution of 91 m, with a FOV that spans 23 kilometers, and Titan is mapped in a push-broom manner as determined by the orbital path. The system mass and power requirements are estimated to be 6 kg and 5 W, respectively. The package is proposed for a polar orbiter with a lifetime matching two Saturn seasons

    Clinical radiology research in Pakistan: from evidence to practice

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    OBJECTIVE: To assess the clinical radiology research productivity in Pakistan by type of publication, sources of funding and name of journals. METHODS: A systematic search strategy using key words related to techniques and type of clinical radiology was carried out to identify various studies published in Indexed (Medline) and non-indexed (Pakmedinet) medical journals. RESULTS: Total of 397 studies were identified out of which 173(43%) from Medline (indexed database) and 220 (57%) from pakmedinet (Indexed and non- indexed database of Pakistan Medical journals). Original articles were 294 (74%) but most of them (68%) were published in non-indexed journals and significantly different from other articles types (case reports, short reports, review articles and letter to editors) (p-value \u3c 0.001). No Randomized Controlled Trial was identified. No research was funded by any formal financial agency. As high as 78% of indexed studies were published by radiology centers of Sind province. Private hospitals having radiology department contributed significantly in indexed journals compared to government hospitals (p-value \u3c 0.001). Majority (74%) of the studies were done by radiologists as compared to other non-radiology clinical colleagues (p-value \u3c 0.001). The most preferred journal for publication was the Journal of Pakistan Medical Association (JPMA; N = 43) followed by Annals of King Edward medical college (Ann KEMC; N = 20). Australasian journal of radiology was the most preferred international journal for publication (Australas Radiol N = 3). No significant difference was found in radiology research production in terms of number of publication from and before the year 2000 (p-value 0.51). CONCLUSION: Clinical radiology research production from Pakistan is low in terms of quality and number. Only few studies reach the standard of publication in international medical journals. There is an urgent need of building the foundation of research programmes in radiology and strengthen research capacity building at facility and health policy level

    Wave-dominated Shoreline Sediments in Early Cretaceous Surajdeval Formation, Saurashtra Basin, Gujarat Western India

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    The Early Cretaceous Surajdeval Formation of the Dhrangadhra group consists of the following three major facies: 1) a sand dominated facies (S), characterized by hummocky cross-stratification, planar and trough cross-bedding (Sp, St), and swaley cross stratification (SCS). 2) the hetro lithic facies (H) characterized by shatter red mudstone and fine-to very fine grained sandstone / red siltstone, exhibiting parallel and low-angle cross-laminations including symmetrical and interference ripples 3) sand matrix-supported conglomerate/pebbly facies (Cg-S) displaying an alternation of coarse (50mm), medium to fine (lt10-20 mm) pebbles in successive beds, and couplets of crudely graded conglomerate. nbspnbspnbspnbspnbsp The sedimentary facies and structures of the Surajdeval Formation reflect deposition by wave, and tide dominated events. Parallel-laminated and fine-grained sandstones are deposited in response to decrease incompetency and capacity of the flow. nbspnbspnbspnbspnbsp The conglomerates and couplets with sandstone may be the product of longshore deposits. Mudstone may have accumulated in protected lagoonal environment. Paleocurrent indicators, such as cross-bedding and pebble fabric show orientation toward south-south-west, and north-north-west, and may be attributed to ebb tidal (onshore), and those exhibiting north-north-west orientation to flood tidal/ longshore (off-shore) currents. Thus, the sedimentological features of the Surajdeval Formation suggest that wave tides and storm processes were involved during its deposition

    Deterministic and Probabilistic Binary Search in Graphs

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    We consider the following natural generalization of Binary Search: in a given undirected, positively weighted graph, one vertex is a target. The algorithm's task is to identify the target by adaptively querying vertices. In response to querying a node qq, the algorithm learns either that qq is the target, or is given an edge out of qq that lies on a shortest path from qq to the target. We study this problem in a general noisy model in which each query independently receives a correct answer with probability p>12p > \frac{1}{2} (a known constant), and an (adversarial) incorrect one with probability 1āˆ’p1-p. Our main positive result is that when p=1p = 1 (i.e., all answers are correct), logā”2n\log_2 n queries are always sufficient. For general pp, we give an (almost information-theoretically optimal) algorithm that uses, in expectation, no more than (1āˆ’Ī“)logā”2n1āˆ’H(p)+o(logā”n)+O(logā”2(1/Ī“))(1 - \delta)\frac{\log_2 n}{1 - H(p)} + o(\log n) + O(\log^2 (1/\delta)) queries, and identifies the target correctly with probability at leas 1āˆ’Ī“1-\delta. Here, H(p)=āˆ’(plogā”p+(1āˆ’p)logā”(1āˆ’p))H(p) = -(p \log p + (1-p) \log(1-p)) denotes the entropy. The first bound is achieved by the algorithm that iteratively queries a 1-median of the nodes not ruled out yet; the second bound by careful repeated invocations of a multiplicative weights algorithm. Even for p=1p = 1, we show several hardness results for the problem of determining whether a target can be found using KK queries. Our upper bound of logā”2n\log_2 n implies a quasipolynomial-time algorithm for undirected connected graphs; we show that this is best-possible under the Strong Exponential Time Hypothesis (SETH). Furthermore, for directed graphs, or for undirected graphs with non-uniform node querying costs, the problem is PSPACE-complete. For a semi-adaptive version, in which one may query rr nodes each in kk rounds, we show membership in Ī£2kāˆ’1\Sigma_{2k-1} in the polynomial hierarchy, and hardness for Ī£2kāˆ’5\Sigma_{2k-5}

    Melatonin treatment for newborns with hypoxic ischaemic encephalopathy

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    OBJECTIVES: This is a protocol for a Cochrane Review (intervention). The objectives are as follows:. To assess the effects and safety of melatonin compared to standard care, including therapeutic hypothermia, for improving survival and reducing neurological sequelae in newborns with neonatal encephalopathy

    Miniature, Low-Power, Waveguide Based Infrared Fourier Transform Spectrometer for Spacecraft Remote Sensing

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    Fourier transform spectrometers have a venerable heritage as flight instruments. However, obtaining an accurate spectrum exacts a penalty in instrument mass and power requirements. Recent advances in a broad class of non-scanning Fourier transform spectrometer (FTS) devices, generally called spatial heterodyne spectrometers, offer distinct advantages as flight optimized systems. We are developing a miniaturized system that employs photonics lightwave circuit principles and functions as an FTS operating in the 7-14 micrometer spectral region. The inteferogram is constructed from an ensemble of Mach-Zehnder interferometers with path length differences calibrated to mimic scan mirror sample positions of a classic Michelson type FTS. One potential long-term application of this technology in low cost planetary missions is the concept of a self-contained sensor system. We are developing a systems architecture concept for wide area in situ and remote monitoring of characteristic properties that are of scientific interest. The system will be based on wavelength- and resolution-independent spectroscopic sensors for studying atmospheric and surface chemistry, physics, and mineralogy. The self-contained sensor network is based on our concept of an Addressable Photonics Cube (APC) which has real-time flexibility and broad science applications. It is envisaged that a spatially distributed autonomous sensor web concept that integrates multiple APCs will be reactive and dynamically driven. The network is designed to respond in an event- or model-driven manner or reconfigured as needed
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