1,681 research outputs found

    Theory of photon coincidence statistics in photon-correlated beams

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    The statistics of photon coincidence counting in photon-correlated beams is thoroughly investigated considering the effect of the finite coincidence resolving time. The correlated beams are assumed to be generated using parametric downconversion, and the photon streams in the correlated beams are modeled by two partially correlated Poisson point processes. An exact expression for the mean rate of coincidence registration is developed using techniques from renewal theory. It is shown that the use of the traditional approximate rate, in certain situations, leads to the overestimation of the actual rate. The error between the exact and approximate coincidence rates increases as the coincidence-noise parameter, defined as the mean number of uncorrelated photons detected per coincidence resolving time, increases. The use of the exact statistics of the coincidence becomes crucial when the background noise is high or in cases when high precision measurement of coincidence is required. Such cases arise whenever the coincidence-noise parameter is even slightly in excess of zero. It is also shown that the probability distribution function of the time between consecutive coincidence registration can be well approximated by an exponential distribution function. The well-known and experimentally verified Poissonian model of the coincidence registration process is therefore theoretically justified. The theory is applied to an on-off keying communication system proposed by Mandel which has been shown to perform well in extremely noisy conditions. It is shown that the bit-error rate (BER) predicted by the approximate coincidence-rate theory can be significantly lower than the actual BER obtained using the exact theory

    Statistical algorithm for nonuniformity correction in focal-plane arrays

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    A statistical algorithm has been developed to compensate for the fixed-pattern noise associated with spatial nonuniformity and temporal drift in the response of focal-plane array infrared imaging systems. The algorithm uses initial scene data to generate initial estimates of the gain, the offset, and the variance of the additive electronic noise of each detector element. The algorithm then updates these parameters by use of subsequent frames and uses the updated parameters to restore the true image by use of a least-mean-square error finite-impulse-response filter. The algorithm is applied to infrared data, and the restored images compare favorably with those restored by use of a multiple-point calibration technique

    Scene-based nonuniformity correction for focal plane arrays by the method of the inverse covariance form

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    What is to our knowledge a new scene-based algorithm for nonuniformity correction in infrared focal-plane array sensors has been developed. The technique is based on the inverse covariance form of the Kalman filter (KF), which has been reported previously and used in estimating the gain and bias of each detector in the array from scene data. The gain and the bias of each detector in the focal-plane array are assumed constant within a given sequence of frames, corresponding to a certain time and operational conditions, but they are allowed to randomly drift from one sequence to another following a discrete-time Gauss-Markov process. The inverse covariance form filter estimates the gain and the bias of each detector in the focal-plane array and optimally updates them as they drift in time. The estimation is performed with considerably higher computational efficiency than the equivalent KF. The ability of the algorithm in compensating for fixed-pattern noise in infrared imagery and in reducing the computational complexity is demonstrated by use of both simulated and real data

    Penormaan Pengawasan Izin Lingkungan dalam Pencegahan Pencemaran dan Kerusakan Lingkungan Hidup dalam Eksploitasi Sumber Daya Alam

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    In environmental protection and management, the main effort is to prevent pollution and damage on environment instead of repressing the damages occurred. Permit is one of preventive measures and becomes a principle in Administrative Law. Permits can be seen as government\u27s tool as judicial preventive and used as an administrative instrument to control people\u27s behavior. Environmental permit can be seen as preventive measure, because it always related to orders and obligations that must be obeyed by the holder. On the other hand, environmental permit also function as repressive instrument to counter environmental problems due to human activities, including mining. The norm\u27s obscurity on the supervision of environmental permits in in Law No. 32 Year 2009 on Environmental Protection and Management (hereafter will refer as UUPPLH) is an indicator for the lack of the objective results.Based on type, this research focuses the study on the Environmental permit as an absolute requirement. Normatively, the principle of environmental permit as stipulated in Environmental Law regulates that every business and/or activity which required an Environmental Impact Analysis document or UKL-UPL should also hold an environmental permit. The purpose of Environmental permits is to maintain the preservation of environmental functions while also prevent and counter environmental pollution and damage due to human activities. Based on this construction, permits plays a very important role in environmental activity. Exploitation of natural resources has a significant impact on the environment, thus based on Article 22 paragraph (1) of Environmental Law these activities requires an Environment Impact Analysis. Important impacts as detailed in Article 22 paragraph (2) at empirical level still occurs so the goal of preventing pollution and damage as the objective of environmental permits still has not been achieved

    Gastrointestinal Symptoms in Marfan Syndrome and Hypermobile Ehlers-Danlos Syndrome.

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    Objective: Marfan syndrome (MS) is a multisystem disorder caused by a mutation in FBN1 gene. It shares some phenotypic features with hypermobile Ehlers-Danlos syndrome (EDS) such as joint hypermobility. EDS is a group of inherited heterogenous multisystem disorders characterized by skin hyperextensibility, atrophic scarring, joint hypermobility, and generalized tissue fragility. Hypermobile EDS (hEDS) is thought to be the most common type. Recent studies have suggested an association between connective tissue hypermobility and functional gastrointestinal disorders (FGDs). The aim of this study is to determine the prevalence of gastrointestinal symptoms in patients with Marfan syndrome and hypermobile EDS. Method: Patients with a diagnosis of either MS or hEDS attending cardiology or rheumatology outpatients at our hospital were asked to complete SF36 RAND and Rome IV Diagnostic questionnaires. Questionnaires were also completed by patients who are members of Marfan Association UK. The same questionnaires were also completed by age- and gender-matched controls attending fracture clinic without existing diagnoses of MS or hEDS. Results: Data were collected from 45 MS patients (12 males and 33 females, age range 19-41 years, mean 28 years) and 45 hEDS patients (6 males and 39 females, age range 18-32 years, mean 24 years). None had a previous organic gastrointestinal diagnosis. The control group was matched for age and sex (18 males and 72 females, age range 18-45, mean 29 years). Both MS and hEDS groups showed a higher prevalence of abdominal symptoms compared to the control group; however, the hEDS group not only showed a higher prevalence but more frequent and severe symptoms meeting Rome IV criteria for diagnosis of FGIDs. Nearly half of the hEDS patients met the criteria for more than one FGID. The hEDS group also scored lower on quality of life (QOL) scores in comparison to either of the other groups with a mean score of 48.6 as compared to 54.2 in the Marfan group and 78.6 in the control group. Conclusion: FGIDs are reported in both Marfan syndrome and hypermobile Ehlers-Danlos syndrome but appear to be more common and severe in hEDS. These patients score lower on quality of life scores as well despite hypermobility being a common feature of both conditions. Further work is needed to understand the impact of connective tissue disorders on gastrointestinal symptoms

    Multi-Model Kalman Filtering for Adaptive Nonuniformity: Correction in Infrared Sensors

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    This paper presents an adaptive technique for the estimation of nonuniformity parameters of infrared focal-plane arrays that is robust with respect to changes and uncertainties in scene and sensor characteristics. The proposed algorithm is based on using a bank of Kalman filters in parallel. Each filter independently estimates state variables comprising the gain and the bias matrices of the sensor, according to its own dynamical-model parameters, which underly the statistics of the scene and the nonuniformity as well as the temporal drift in the nonuniformity. The supervising component of the algorithm then generates the final estimates of the state variables by forming a weighted superposition of all the estimates rendered by each Kalman filter. The weights are obtained according to the a posteriori -likelihood principle, applied to the family of models by considering the output residual errors associated with each filter. These weights are updated iteratively between blocks of data, providing the estimator the means to follow the dynamics of the scenes and the sensor. The performance of the proposed estimator and its ability to compensate for fixed-pattern noise are tested using both real and simulated data. The real data is obtained using two cameras operating in the mid- and long-wave infrared regime

    Phylogenetic analysis of Artemisia L. (Asteraceae) based on micromorphological traits of pollen grains

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    The phylogenetic relationships within the genus Artemisia have been very controversial. In order to recognize the systematic inference of pollen grains in this genus, the micromorphological characteristics of pollens from 22 taxa were examined by means of light microscopy (LM) and scanningelectron microscopy (SEM). A phylogenetic analysis of Artemisia based on 9 micromorphological characters of pollens was conducted using Wagner parsimony method. In the resulting phylogenetic tree, relationships among different Artemisia species are shown. This study also presents thephylogenetic associations among 4 sections within the genus Artemisia. The reunion of genus Seriphidum with Artemisia was also confirmed

    Foliar epidermal anatomy and its systematic implication within the genus Sida L. (malvaceae)

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    Micro morphological investigations of the foliar epidermal anatomy, particularly the diversity and distribution of glandular and eglandular trichomes on leaves of Sida alba L., S. alii S. Abedin var. alii, S.cordata (Burm. F.) Brss, S. mysorensis Wight and Arn, S. ovata Forssk. S. spinosa L and S.yunnanensis S.Y.Hu have been carried out to assess the systematic relevance of epidermal features and trichome diversity within the genus Sida L. Configuration of epidermal cells is polygonal to irregular with smooth or undulating outline. Leaves are amphistomatic and amphitrichomic. Six diverse morphological types of glandular and eglandular foliar trichomes are described. Stellate and peltate types of trichomes are characteristically found in all taxa studied. S. alii and S.spinosa are distinct in having long-stalked and short-stalked capitate trichomes. S. mysorensis is characterized by multicellular uniseriate trichomes, but these are not observed in other taxa of genus Sida. The results of foliar epidermal anatomy, especially type, distribution and structure of foliar trichomes are of high systematic value in this genus of family Malvaceae

    Violation of Heisenberg's Measurement-Disturbance Relationship by Weak Measurements

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    While there is a rigorously proven relationship about uncertainties intrinsic to any quantum system, often referred to as "Heisenberg's Uncertainty Principle," Heisenberg originally formulated his ideas in terms of a relationship between the precision of a measurement and the disturbance it must create. Although this latter relationship is not rigorously proven, it is commonly believed (and taught) as an aspect of the broader uncertainty principle. Here, we experimentally observe a violation of Heisenberg's "measurement-disturbance relationship", using weak measurements to characterize a quantum system before and after it interacts with a measurement apparatus. Our experiment implements a 2010 proposal of Lund and Wiseman to confirm a revised measurement-disturbance relationship derived by Ozawa in 2003. Its results have broad implications for the foundations of quantum mechanics and for practical issues in quantum mechanics.Comment: 5 pages, 4 figure
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