Low Probability Of False Positives Research Articles

Detection of Atrazine and its metabolites by photonic molecularly imprinted polymers in aqueous solutions

Water contamination caused by atrazine (ATZ) application in agriculture is a risk to the environment and human health. Common analytical methods are expensive and complex. A sensor for low-cost and simple detection of ATZ and its metabolites, deethylatrazine (DEA) and deisopropylatrazine (DIA), in aqueous solutions was developed by combining colloidal crystal with molecular imprinting technique. The sensor is formed by 3D interconnected macroporous structure with numerous nanocavities derived from ATZ and its metabolites imprinting in a thin polymeric film. Molecularly Imprinted Polymers (MIPs) were characterized by Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) and were incubated in solutions at variable concentrations. Target molecules were specifically absorbed in nanocavities and caused swelling in the polymer resulting in changes of Bragg diffraction peak wavelength. Kinetic tests showed that rebinding equilibrium was reached within 20 minutes. The sensor had a dynamic range of 0.1 to 10 ppb for quantifying target analytes in aqueous solutions with limit of detection of 0.1, 0.2, and 0.3 ppb, and limit of quantification of 0.33, 0.66, and 1 ppb for ATZ, DEA, and DIA, respectively. Cross-reactivity tests were conducted in 1 and 5 ppb solutions combining all three targets and showed absence of positive interference effects and low probability of false positives given by individual sensors. MIPs were examined in natural waters containing ATZ and its metabolites contamination, showing good agreement with real concentrations of targets. The MIP yields rapid and efficient detection of target molecules in aqueous solutions close to environmentally relevant concentrations.

An Efficient Association Rule Mining Algorithm Based on Animal Migration Optimization Processing of Unknown Incidents in Crime Analysis Brance

A new protection scheme was proposed to avoid this problem. It is intended that each node uses a salted and a not salted HLL. If their estimates differ considerably, an attacker attempts to manipulate the estimates of HLL. In addition to avoiding manipulation, the proposed salted and unsalted (SNS) regime can also detect attempts at manipulation. A practical configuration showing how manipulation attempts can be detected in a low false positive probability has been shown to be applicable to this SNS scheme. Therefore, if merge ability is to be preserved it can be an interesting approach to protect HLLs from avoidance. In this paper the proposal for a new mining algorithm based on Animal Migration Optimization is made to decrease the number of Association Rules called ARM-AMO. The idea is to remove from the data rules which are not highly supportive and unnecessary. First of all, common item sets and association rules are generated with an Apriori algorithm. AMO also reduces the number of association rules incorporated in a new fitness function. In here, we provide a well-organized mechanism for incident derivation under the unwanted incident. This mechanism very useful for measure the heavy load of an incoming incident and exact calculation of the probability. In additional method is a Select-ability mechanism, which performs an important responsibility in incident derivation under the unwanted incident in both the settled and the unknown incident. A model for signifying derivative incident introduced jointly with an Advanced Sampling Technique that come close to the derived incident probabilities. This augmentation executed the prioritization techniques. In this prioritization techniques, recognize such cases in which the order of incident finding is strong-minded and mechanism for the definition of a settled detection execution.

Distributed SCFMBF Based Protocol for Integrity In Cloud Storage System (DPICS)

Cloud storage allowed the data owners to store their data without the burden of local hardware. There were some security concerns because of the cloud being untrusted. To make sure the stored data was intact since it was impractical to download the full data, a security mechanism named integrity check was used. Integrity check was achieved by probabilistic structures such as bloom filter and cuckoo filter. Uploading data file on to one cloud server could be a point of failure, instead the file could be distributed over l servers. Distributed SCFMBF Based Protocol for Integrity in Cloud Storage System (DPICS) was proposed to remotely check data integrity in a more effective way. Smart Cuckoo Filter Modified by Bloom Filter (SCFMBF) was a protocol that improved some of the performance properties of cuckoo filter such as false positive rate and insertion performance and solved some drawbacks of the cuckoo algorithm such as endless loop. Main characteristic of the bloom filter was used to improve cuckoo filter as the protocol name describes. First bloom filter was used as the integrity check method in cloud but bloom filter was not suitable for dynamic environment, SCFMBF was substituted for bloom filter because it had low false positive probability in integrity check and could cope well with dynamic data. How DPICS was more efficient than other previous works, was shown in terms of false positive probability, integrity check and retrievability.

A Feasibility Study on the Implementation of Visibility Algorithms for Fault Diagnosis in Aircraft Fuel Systems

This paper discusses the applicability of Visibility Algorithms to detect faults in condition monitoring applications. The general purpose of Visibility Algorithms is to transform time series into graphs and study them through the characterization of their associated network. Degradation of a component results in changes to the network. This technique has been applied using a test rig of an aircraft fuel system to show that there is a correlation between the values of key metrics of visibility graphs and the severity of four failure modes. We compare the results of using Horizontal Visibility algorithms against Natural Visibility algorithms. The results also show how the Kullback-Leibler divergence and statistical entropy can be used to produce condition indicators. Experimental results show that there is little dispersion in the values of condition indicators, leading to a low probability of false positives and false negatives.

A Bloom Filter for High Dimensional Vectors

Regardless of the type of data, traditional Bloom filters treat each element of a set as a string, and by iterating every character of the string, they discretize all data randomly and uniformly. However, with the data size and dimension increases, these variants are inefficient. To better discretize vectors with high numerical dimensions, this paper improves the string hashes to integer hashes. Based on the integer hashes and a counter array, we propose a new variant—high-dimensional bloom filter (HDBF)—to extend the Bloom filter into high-dimensional spaces, which can represent and query numerical vectors of a big set with a low false positive probability. This paper theoretically analyzes the feasibility of the integer hashes on discretizing data and discusses the relationship of parameters of the HDBF. The experiments illustrate that, in high-dimensional numerical spaces, the HDBF shows better randomness on distribution and entropy than that of the counting Bloom filter. Compared with the parallel Bloom filters, for a fixed false positive probability, the HDBF displays time-space overheads, and is more suitable to deal with the numerical vectors with high dimensions.

Efficient Multiset Synchronization

Set synchronization is an essential job for distributed applications. In many cases, given two sets $A$ and $B$ , applications need to identify those elements that appear in set $A$ but not in set $B$ , and vice versa. Bloom filter, a space-efficient data structure for representing a set and supporting membership queries, has been employed as a lightweight method to realize set synchronization with a low false positive probability. Unfortunately, bloom filters and their variants can only be applied to simple sets rather than more general multisets, which allow elements to appear multiple times. In this paper, we first examine the potential of addressing the multiset synchronization problem based on two existing variants of the bloom filters: the IBF and the counting bloom filter (CBF). We then design a novel data structure, invertible CBF (ICBF), which represents a multiset using a vector of cells. Each cell contains two fields, $id$ and $count$ , which record the identifiers and number of elements mapped into them, respectively. Given two multisets, based on the encoding results, the ICBF can execute the dedicated subtracting and decoding operations to recognize the different elements and differences in the multiplicities of elements between the two multisets. We conduct comprehensive experiments to evaluate and compare the three dedicated multiset synchronization approaches proposed in this paper. The evaluation results indicate that the ICBF-based approach outperforms the other two approaches in terms of synchronization accuracy, time-consumption, and communication overhead.

On the Charge Collection Efficiency of the PERCIVAL Detector

The PERCIVAL soft X-ray imager is being developed by DESY, RAL, Elettra, DLS, and PAL to address the challenges at high brilliance Light Sources such as new-generation Synchrotrons and Free Electron Lasers. Typical requirements for detector systems at these sources are high frame rates, large dynamic range, single-photon counting capability with low probability of false positives, high quantum efficiency, and (multi)-mega-pixel arrangements. PERCIVAL is a monolithic active pixel sensor, based on CMOS technology. It is designed for the soft X-ray regime and, therefore, it is post-processed in order to achieve high quantum efficiency in its primary energy range (250 eV to 1 keV) . This work will report on the latest experimental results on charge collection efficiency obtained for multiple back-side-illuminated test sensors during two campaigns, at the P04 beam-line at PETRA III, and the CiPo beam-line at Elettra, spanning most of the primary energy range as well as testing the performance for photon-energies below 250 eV . In addition, XPS surface analysis was used to cross-check the obtained results.

Characterisation of a PERCIVAL monolithic active pixel prototype using synchrotron radiation

PERCIVAL (“Pixelated Energy Resolving CMOS Imager, Versatile And Large”) is a monolithic active pixel sensor (MAPS) based on CMOS technology. Is being developed by DESY, RAL/STFC, Elettra, DLS, and PAL to address the various requirements of detectors at synchrotron radiation sources and Free Electron Lasers (FELs) in the soft X-ray regime. These requirements include high frame rates and FELs base-rate compatibility, large dynamic range, single-photon counting capability with low probability of false positives, high quantum efficiency (QE), and (multi-)megapixel arrangements with good spatial resolution. Small-scale back-side-illuminated (BSI) prototype systems are undergoing detailed testing with X-rays and optical photons, in preparation of submission of a larger sensor. A first BSI processed prototype was tested in 2014 and a preliminary result—first detection of 350eV photons with some pixel types of PERCIVAL—reported at this meeting a year ago. Subsequent more detailed analysis revealed a very low QE and pointed to contamination as a possible cause. In the past year, BSI-processed chips on two more wafers were tested and their response to soft X-ray evaluated. We report here the improved charge collection efficiency (CCE) of different PERCIVAL pixel types for 400eV soft X-rays together with Airy patterns, response to a flat field, and noise performance for such a newly BSI-processed prototype sensor.

Detector developments at DESY.

With the increased brilliance of state-of-the-art synchrotron radiation sources and the advent of free-electron lasers (FELs) enabling revolutionary science with EUV to X-ray photons comes an urgent need for suitable photon imaging detectors. Requirements include high frame rates, very large dynamic range, single-photon sensitivity with low probability of false positives and (multi)-megapixels. At DESY, one ongoing development project - in collaboration with RAL/STFC, Elettra Sincrotrone Trieste, Diamond, and Pohang Accelerator Laboratory - is the CMOS-based soft X-ray imager PERCIVAL. PERCIVAL is a monolithic active-pixel sensor back-thinned to access its primary energy range of 250 eV to 1 keV with target efficiencies above 90%. According to preliminary specifications, the roughly 10 cm × 10 cm, 3.5k × 3.7k monolithic sensor will operate at frame rates up to 120 Hz (commensurate with most FELs) and use multiple gains within 27 µm pixels to measure 1 to ∼100000 (500 eV) simultaneously arriving photons. DESY is also leading the development of the AGIPD, a high-speed detector based on hybrid pixel technology intended for use at the European XFEL. This system is being developed in collaboration with PSI, University of Hamburg, and University of Bonn. The AGIPD allows single-pulse imaging at 4.5 MHz frame rate into a 352-frame buffer, with a dynamic range allowing single-photon detection and detection of more than 10000 photons at 12.4 keV in the same image. Modules of 65k pixels each are configured to make up (multi)megapixel cameras. This review describes the AGIPD and the PERCIVAL concepts and systems, including some recent results and a summary of their current status. It also gives a short overview over other FEL-relevant developments where the Photon Science Detector Group at DESY is involved.

A Gesture Recognition Design Toolkit Everyday Gesture Library

Creating gestural recognition system is a challenging task which requires skills and updated applications. It is required for designer to be skillful and innovative in order to create interesting and acceptable gestures. Gesture Recognition Design Toolkit (GRDT) is set of tools designed to simplify the gesture creation process for non experts. From designing a new gesture, to suggesting the best fit, to test it for false positive activation, till final selection, are the step-by-step functions of Gesture Recognition Design Toolkit. Creating gestural recognition system, interface designers encounter many challenges throughout the process. Selecting the best gesture for a particular motion with low probability of false positives is one of many. This study explores ways to improve the functionality and enhance the efficiency of gestural library using machine learning techniques and data mining General Terms Multiple Action Gesture Interface Creation, Human computer interaction, Symbolic aggregate approximation, Nearest neighbor dynamic time wrapping, Hidden markov model, Dynamic time wrapping, Extract, transform and load

The PERCIVAL soft X-ray imager

With the increased brilliance of state-of-the-art Synchrotron radiation sources and the advent of Free Electron Lasers enabling revolutionary science on atomic length and time scales with EUV to X-ray photons comes an urgent need for suitable photon imaging detectors. Requirements include high frame rates, very large dynamic range, single-photon counting capability with low probability of false positives, and (multi)-megapixels. PERCIVAL (``Pixelated Energy Resolving CMOS Imager, Versatile And Large'') is currently being developed by a collaboration of DESY, RAL, Elettra, DLS and Pohang to address this need for the soft X-ray regime. PERCIVAL is a monolithic active pixel sensor (MAPS), i.e. based on CMOS technology. It will be back-thinned to access its primary energy range of 250 eV to 1 keV with target efficiencies above 90%. According to its preliminary specifications, the roughly 10 × 10 cm2, 3.5k × 3.7k monolithic ``PERCIVAL13M'' sensor will operate at frame rates up to 120 Hz (commensurate with most FELs) and use multiple gains within its 27 μm pixels to measure 1 to ∼ 105 (500 eV) simultaneously-arriving photons. A smaller ``PERCIVAL2M'' with ∼ 1.4k × 1.5k pixels is also planned. Currently, small-scale back-illuminated prototype systems (160 × 210 pixels of 25 μm pitch) are undergoing detailed testing with X-rays and optical photons. In March 2014, a prototype sensor was tested at 350 eV–2 keV at Elettra's TwinMic beamline. The data recorded include diffraction patterns at 350 eV and 400 eV, knife edge and sub-pixel pinhole illuminations, and comparisons of different pixel types. Another prototype chip will be submitted in fall 2014, first larger sensors could be in hand in late 2015.

The PERCIVAL soft X-ray imager

With the increased brilliance of state-of-the-art Synchrotron radiation sources and the advent of Free Electron Lasers enabling revolutionary science with EUV to X-ray photons comes an urgent need for suitable photon imaging detectors. Requirements include high frame rates, very large dynamic range, single-photon counting capability with low probability of false positives, and (multi)-megapixels.PERCIVAL (``Pixelated Energy Resolving CMOS Imager, Versatile and Large'') is currently being developed by a collaboration of DESY, RAL, Elettra and DLS to address this need for the soft X-ray regime. PERCIVAL is a monolithic active pixel sensor (MAPS), i.e. based on CMOS technology. It will be back-thinned to access its primary energy range of 250 eV to 1 keV with target efficiencies above 90%. According to its preliminary specifications, the roughly 10 × 10 cm2, 3520 × 3710 pixel monolithic sensor will operate at frame rates up to 120 Hz (commensurate with most FELs) and use multiple gains within its 27 μm pixels to measure (e.g. at 500 eV)1 to ∼ 105 simultaneously-arriving photons.Currently, small-scale front-illuminated prototype systems (160 × 210 pixels) are undergoing detailed testing with visible-light as well as X-ray photons.

A gossiping protocol for detecting global threshold crossings

We investigate the use of gossip protocols for the detection of network-wide threshold crossings. Our design goals are low protocol overhead, small detection delay, low probability of false positives and negatives, scalability, robustness to node failures and controllability of the trade-off between overhead and detection delay. Based on push-synopses, a gossip protocol introduced by Kempe et al., we present a protocol that indicates whether a global aggregate of static local values is above or below a given threshold. For this protocol, we prove correctness and show that it converges to a state with no overhead when the aggregate is sufficiently far from the threshold. Then, we introduce an extension we call TG-GAP, a protocol that (1) executes in a dynamic network environment where local values change and (2) implements hysteresis behavior with upper and lower thresholds. Key elements of its design are the construction of snapshots of the global aggregate for threshold detection and a mechanism for synchronizing local states, both of which are realized through the underlying gossip protocol. Simulation studies suggest that TG-GAP is efficient in that the protocol overhead is minimal when the aggregate is sufficiently far from the threshold, that its overhead and the detection delay are largely independent on the system size, and that the tradeoff between overhead and detection quality can be effectively controlled. Lastly, we perform a comparative evaluation of TG-GAP against a tree-based protocol. We conclude that, for detecting global threshold crossings in the type of scenarios investigated, the tree-based protocol incurs a significantly lower overhead and a smaller detection delay than a gossip protocol such as TG-GAP.

Research of Intelligent Rule-base Based on Multilayer Intrusion Detection

This paper presents a method to establish a rulebase based on multilayer intrusion detection. This rulebase contains two parts: the rulebase based on IP layer intrusion detection and the rulebase based on application layer intrusion detection. The former adopts a mixed quadratic network statistical model to test network traffic which has performances of dynamic principle and low False Positive Probability ( FPP) and low False Negative Probability ( FNP), and the rulebase is established using the twice-aggregation method. The latter is established by improved Snort. The simulation has proved that this intelligent rulebase can improve detection rate and ability to a large degree, and has low FPP and FNP.

High-sensitivity, high-selectivity detection of chemical warfare agents

We report high-sensitivity detection of chemical warfare agents (nerve gases) with very low probability of false positives (PFP). We demonstrate a detection threshold of 1.2ppb (7.7μg∕m3 equivalent of Sarin) with a PFP of <1:106 in the presence of many interfering gases present in an urban environment through the detection of diisopropyl methylphosphonate, an accepted relatively harmless surrogate for the nerve agents. For the current measurement time of ∼60s, a PFP of 1:106 corresponds to one false alarm approximately every 23months. The demonstrated performance satisfies most current homeland and military security requirements.

An asymmetric subspace watermarking method for copyright protection

We present an asymmetric watermarking method for copyright protection that uses different matrix operations to embed and extract a watermark. It allows for the public release of all information, except the secret key. We investigate the conditions for a high detection probability, a low false positive probability, and the possibility of unauthorized users successfully hacking into our system. The robustness of our method is demonstrated by the simulation of various attacks.

Intracellular staining for HIV-specific IFN-gamma production: statistical analyses establish reproducibility and criteria for distinguishing positive responses.

The cellular immune response plays a pivotal role in controlling the spread of HIV-1 infection by lysing virally infected cells and producing potent antiviral cytokines, such as interferon-gamma (IFN-gamma). Flow cytometric methods have been established to evaluate the contribution of both CD4 and CD8 subsets of T lymphocytes to the immune response to HIV by measuring their production of intracellular IFN-gamma following brief antigenic stimulation. We present a statistical treatment of intracellular cytokine staining (ICS) data that is aimed at establishing the reproducibility and robustness of this assay for use in HIV clinical trials. Comparisons of responses from HIV-seronegative and seropositive individuals were used to establish a 2-fold criterion for distinguishing positive responses with a low probability of false positives (<1%). Additional comparisons established that the reproducibility of the assay is between 1.4 and 2.0-fold depending on the magnitude of the response. Little variability was demonstrated between multiple operators for both the execution and analysis components of these experiments (<10% difference with 95% confidence). We conclude that the statistical criteria established by these analyses allow for the accurate detection and comparison of positive responses. Using these statistical criteria, the ICS assay is sufficiently robust for use in HIV-specific vaccine trials.

On-line determination of bipyridylium herbicides in water by HPLC

Selective on-line solid phase extraction (SPE) and liquid chromatography determination (HPLC) of diquat, paraquat and difenzoquat from environmental water samples has been accomplished with Graphitized Carbon Black (GCB) as both extraction and analytical columns. The method involved passing of 50 mL of water through a cartridge filled with Carbograph. In the elution step, the herbicides were transferred from the cartridge to the analytical column (Hypercarb) by mean of a gradient of pH 3 aqueous solution of tetramethylammonium hydroxide (TMAOH) and ammonium sulphate and methanol. Hypercarb columns were found to give a low probability of false positives for bypiridylium herbicides and are very selective for polar compounds. Recovery was better than 80 %. The breakthrough volume was studied with distilled water spiked with the herbicides at various concentration levels (from 0.1 to 20 μg L−1). The limits of quantification of the method were lower than 0.1 μg L−1. The total analytical method was applied to surface waters from Torreblanca Nature Park (Castello, Spain).

Trace determination of phenols in natural waters extraction by a new graphitized carbon black cartridge followed by liquid chromatography and re-analysis after phenol derivatization

Based upon solid-phase extraction, a sensitive, selective and robust liquid chromatography (LC) procedure for determining the U.S. EPA eleven priority pollutant phenols in natural waters is presented. The method involves passing 4 and 11, respectively, of drinking and river waters through a reversible cartridge filled with 0.5 g of a new example of graphitized carbon black (Carbograph 4) at flow-rates of about 100 ml/min. After washings, phenols are eluted by reversing the cartridge and back-flushing it with 6 ml of a CH 2Cl 2CH 3OH mixture containing tetrabutylammonium chloride, 10 mmol/1. The eluate is then divided in two equal portions that are taken to dryness. After reconstituting the residue of one portion of the extract with a suitable solution, phenols are separated and quantified by ion-suppression, reversed-phase LC with UV detection. The goal of analyzing phenols with a low probability of false positives can be easily reached by converting phenols in the second portion of the extract to acetyl derivatives. The reaction mixture is then injected into the same analytical column and confirmation of the eventual presence of certain phenols in the sample is obtained by observing the disappearance of the peaks for phenols and the simultaneous appearance of peaks for the corresponding acetyl derivatives. By this method, the presence of 1.3 μg/l of 2-chlorophenol in a surface water sample was ascertained. Recovery of phenols, including phenol itself, were higher than 90%. Conversion of phenols to acetyl derivatives was completed by reacting 40 μl of acetic anhydride for 6 min at 50°C, except for 4,6-dinitro-2-methylphenol (78% reaction yield).