Counter Technique Research Articles

Quantifying the Extent of Calcification of a Coccolithophore Using a Coulter Counter.

Although, in principle, the Coulter Counter technique yields an absolute measure of particle volume, in practice, calibration is near-universally employed. For regularly shaped and non-biological samples, the use of latex beads for calibration can provide sufficient accuracy. However, this is not the case with particles encased in biogenically formed calcite. To date, there has been no effective route by which a Coulter Counter can be calibrated to enable the calcification of coccolithophores—single cells encrusted with biogenic calcite—to be quantified. Consequently, herein, we seek to answer the following question: to what extent can a Coulter Counter be used to provide accurate information regarding the calcite content of a single-species coccolithophore population? Through the development of a new calibration methodology, based on the measurement and dynamic tracking of the acid-driven calcite dissolution reaction, a route by which the cellular calcite content can be determined is presented. This new method allows, for the first time, a Coulter Counter to be used to yield an absolute measurement of the amount of calcite per cell.

Diurnal Variations of the Count Rates from Dark Photons in PHELEX

This paper reports the PHELEX experiment, i.e., PHoton–ELectron EXperiment, to search for the dark photons (DPs) of cold dark matter using a multicathode counter technique specifically developed for this purpose by the authors. The paper presents new data, a novel upper limit for the constant of kinetic mixing, and the first results of measurements of the diurnal variations in solar and stellar frames. The perspectives of this method are outlined in terms of the search for DPs.

Steganalysis of Compressed Speech Based on Association Rule Mining

Currently, steganography based on compressed speech streams is gathering more and more attention. Meanwhile, it poses a huge threat to cyber security. As a counter technique, steganalysis can detect whether an illegal secret message is embedded in a compressed speech. To further improve the detection performance of current methods, a novel steganalysis method based on codeword association rule mining (CARM) is proposed in this paper. Firstly, we analyzed the spatiotemporal relationships between codewords in compressed speech. Secondly, the steganography-sensitivity codeword association rule base in training set was built based on the confidence change of codeword association rules before and after steganography. Thirdly, the steganography characteristic index and the corresponding dynamic partition threshold in validation set were computed to determine whether the compressed speech segment contains covert communication or not. Finally, comprehensive experiments were conducted to evaluate the performance of the proposed CARM steganalysis method under various conditions, including different association rule patterns, whether to use dynamic partition threshold, different embedding rates, different speech lengths, etc. The experimental results verify that CARM can achieve better performance than the comparison methods. In addition, the detection accuracy of CARM method can be improved significantly by using dynamic partition threshold at low embedding rates.

AOIO: Application Oriented I/O Optimization for Buffer Management

Emerging scale-out I/O intensive applications are broadly used now, which process a large amount of data in buffer/cache for reorganization or analysis and their performances are greatly affected by the speed of the I/O system. Efficient management scheme of the limited kernel buffer plays a key role in improving I/O system performance, such as caching hinted data for reuse in future, prefetching hinted data, and expelling data not to be accessed again from a buffer, which are called proactive mechanisms in buffer management. However, most of the existing buffer management schemes cannot identify data reference regularities (i.e., sequential or looping patterns) that can benefit proactive mechanisms, and they also cannot perform in the application level for managing specified applications. In this paper, we present an A pplication Oriented I/O Optimization (AOIO) technique automatically benefiting the kernel buffer/cache by exploring the I/O regularities of applications based on program counter technique. In our design, the input/output data and the looping pattern are in strict symmetry. According to AOIO, each application can provide more appropriate predictions to operating system which achieve significantly better accuracy than other buffer management schemes. The trace-driven simulation experiment results show that the hit ratios are improved by an average of 25.9% and the execution times are reduced by as much as 20.2% compared to other schemes for the workloads we used.

Visualization of a novel fluorescent-tagged bisphosphonate behavior during reverse osmosis desalination of water with high sulfate content

Gypsum scaling during reverse osmosis desalination process is studied in presence of a novel fluorescent-tagged bisphphosphonate antiscalant: 1-hydroxy-7-(6-methoxy-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)heptane-1,1-diyldi(phosphonic acid), HEDP-F, by fluorescent microscopy, scanning electron microscopy (SEM) and a particle counter technique. A case study of gypsum scale formation revealed a nonconventional mechanism of antiscalant efficacy. It is found that scaling takes place in the bulk retentate phase via heterogeneous nucleation step. Herewith, the background solid particles (“nanodust”) play a key role as gypsum nucleation centers. It is demonstrated that contrary to popular belief, an antiscalant interacts not with gypsum nuclei, but with “nanodust” particles, isolating them from calcium and sulfate ions sorption. Therefore, the number of gypsum nucleation centers gets reduced, and in turn an overall scaling rate becomes diminished. It is demonstrated that the fluorescent-tagged antiscalants may become a very powerful tool in membranes scaling inhibition studies. It is also shown, that the scale formation scenario changes from the bulk medium in the beginning to the sediment crystals growth on the membrane surface at the end of desalination process.

Thresholded Monitoring in Distributed Data Streams

In this paper, we consider the problem of thresholded monitoring in distributed data streams, that is, given multiple distributed data streams observed by multiple monitors during a certain period, finding the items whose global frequencies over all data streams exceeding a given threshold. We first derive a lower bound of communication overhead for any deterministic algorithm for this problem. Then, we propose two different schemas, i.e. , Low-threshold Cascaded Cuckoo Filter (L-CCF) for low-threshold monitoring and High-threshold Cascaded Cuckoo Filter (H-CCF) for high-threshold monitoring. L-CCF and H-CCF can identify items whose frequencies are more than the given threshold while a desired false negative rate (FNR) is achieved and communication overhead is optimized. The key idea is to compress the communication overhead caused by transferring the ID and frequency information at the same time. First, to reduce the communication overhead of transferring IDs, we propose to encode the IDs into separate tiny parts and store these tiny parts in L-CCF or H-CCF. Second, to reduce the communication overhead of transferring frequencies, we adopt a carry-in counter technique in L-CCF and multiple sampling technique in H-CCF. We evaluated L-CCF and H-CCF on two real-world traces and compared their performance with two prior adapted algorithms. Our experimental results show that on average, L-CCF and H-CCF achieve FNRs with 55% and 65% better than that of comparison algorithms while FPRs is maintained at the level of 2%.

Gypsum Crystallization during Reverse Osmosis Desalination of Water with High Sulfate Content in Presence of a Novel Fluorescent-Tagged Polyacrylate

Gypsum scaling in reverse osmosis (RO) desalination process is studied in presence of a novel fluorescent 1,8-naphthalimide-tagged polyacrylate (PAA-F1) by fluorescent microscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS) and a particle counter technique. A comparison of PAA-F1 with a previously reported fluorescent bisphosphonate HEDP-F revealed a better PAA-F1 efficacy, and a similar behavior of polyacrylate and bisphosphonate inhibitors under the same RO experimental conditions. Despite expectations, PAA-F1 does not interact with gypsum. For both reagents, it is found that scaling takes place in the bulk retentate phase via heterogeneous nucleation step. The background “nanodust” plays a key role as a gypsum nucleation center. Contrary to popular belief, an antiscalant interacts with “nanodust” particles, isolating them from calcium and sulfate ions sorption. Therefore, the number of gypsum nucleation centers is reduced, and in turn, the overall scaling rate is diminished. It is also shown that, the scale formation scenario changes from the bulk medium, in the beginning, to the sediment crystals growth on the membrane surface, at the end of the desalination process. It is demonstrated that the fluorescent-tagged antiscalants may become very powerful tools in membrane scaling inhibition studies.

Multi-energy inter-pixel coincidence counters for charge sharing correction and compensation in photon counting detectors.

Smaller pixel sizes of x-ray photon counting detectors (PCDs) are advantageous for count rate capabilities but disadvantageous for charge sharing. With charge sharing, the energy of an x-ray photon may be split and one photon may produce two or more counts at adjacent pixels, both at lower energies than the incident energy. This "double-counting" increases noise variance and degrades the spectral response. Overall, it has a significantly negative impact on the performance of PCD-based computed tomography (CT). Charge sharing is induced by the detection physics and occurs regardless of count rates; thus, it is impossible to avoid. We propose in this paper a method that has a potential to address both noise and bias added by charge sharing. We propose applying a multi-energy inter-pixel coincidence counter (MEICC) technique, which uses energy-dependent coincidence counters, keeps the book of charge sharing events during data acquisition, and provides the exact number of charge sharing occurrences, which can be used to either correct or compensate for them after the acquisition is completed. MEICC does not interfere with the primary counting process; therefore, PCDs with MEICC will remain as fast as those without MEICC. MEICC can be implemented using current electronics technology because its inter-pixel coincidence counters used to handle digital data are rather simple. We evaluated Cramér-Rao lower bound (CRLB) of PCDs with and without MEICC using a Monte Carlo simulation. When the number of energy windows was four or larger and eight neighboring pixels were used, the CRLBs of 225-µm PCD with MEICC normalized by those of the current PCD with the same number of windows were 0.361-0.383 for water density images of two basis functions, which was only 5.7-16.4% worse than those of a PCD without charge sharing (which were at 0.329-0.358). In contrast, the normalized CRLBs of the PCD with one coincidence counter were 0.466-0.499, which were 37.3-45.6% worse than the PCD without charge sharing. The use of eight neighboring pixels provided ~10% better CRLB values than four neighboring pixels for MEICC. With four energy windows, decreasing the number of coincidence counters from 16 to 9 only slightly increased the CRLB from 0.255 to 0.269 (which corresponded to as little as a 5.5% change). The normalized CRLBs of MEICC for K-edge imaging (gold) were 0.295-0.426, while those of the one coincidence counter were 0.926-0.959 and the ideal PCDs were 0.126-0.146. The proposed MEICC provides spectral information that can be used to address charge sharing problems in PCDs and is expected to satisfy the requirements for clinical x-ray CT. MEICC is very effective, especially for K-edge imaging, which requires accurate spectral information.

Tracking Hg historical inputs by Pb-210 geochronology for the Itapessoca Estuarine Complex, Pernambuco, Brazil

The application of geochronology for tracking mercury contamination was remarkably demonstrated in the Itamaraca Estuarine Ecosystem, Pernambuco State, Brazil. Here, two sediment cores were sampled, layered and analyzed by the Gas Flow Proportional Counter technique for determining 210Pb, radionuclide applied to geochronology. Mercury was quantified in sediment samples by Cold Vapor Atomic Absorption Spectrometry, varying from 0.17 to 1.29 mg kg−1 in deep sediments. From 210Pb results, the sedimentation rates of 0.84 (0.07) cm year−1 and 1.03 (0.22) cm year−1 confirmed Hg contamination in Itamaraca since mid-1965. Events of extreme precipitation and drought have been also related to the distribution pattern for Hg concentrations in deep sediments.

Results from a hidden photon dark matter search using a multi-cathode counter

Here we present measurements of the rates of emission of single electrons from the cathode of a proportional counter filled with a mixture of Ar + CH4 (10%) at 1 bar. We interpret the results as a possible photoelectric effect associated with hidden photons (HPs). Our results set upper limits for HPs from cold dark matter (CDM). We also discuss future options for searches for HPs from CDM using a multi-cathode counter technique.

Does mean platelet volume (MPV) have a role in evaluation of erectile dysfunction and its severity?

PurposeThe mean platelet volume (MPV) has important role in the pathophysiology of vascular diseases as a marker of the platelet activity. To investigate the association between mean platelet volume and erectile dysfunction (ED) and to search whether this marker can be used for diagnosis of ED. Materials and methodsOf the 312 patients with ED of various degrees, 122 patients without ED (IIEF-5>21) were included in this prospective study. Severity of ED was determined according to IIEF-5 questionnaire. MPV, fasting serum glucose, cholesterol, low density lipoprotein (LDL) and serum testosterone levels are also recorded. The mean platelet volume was calculated by the Coulter counter technique and sexual function was determined by International Index of Erectile Function erectile function domain (IIEF-5). ResultsThe mean age of patients was 58.4 years. The mean MPV value of patients with ED was significantly higher compared to the non-ED patients (8.91 vs. 8.22, p=0.0001). The severity of ED was shown to have a positive strong correlation with MPV values (r=0.719, p=0.001). Mean serum triglyceride, glucose, total cholesterol and LDL cholesterol levels were noted higher in patients with ED. MPV values were found to be significantly higher in patients with ED. ConclusionMPV level shows significant correlation with severity of ED. This cheap laboratory test can have potential to be a marker of ED. Further prospective larger studies with vascular wall thickness measurements should be conducted.

Adaptive Interplay of DVS and DPM for Power Consumption Reduction in Real-Time Embedded Processors

Objectives: Processors are computing elements of most of the embedded systems. As the technology is growing day by day, processors that are released in the market are mostly embedded processors. Processors are designed to perform concurrent operations and execution at a higher clock rate to meet the performance demands result in large heat dissipation and energy consumption. Thus there is an emphasis on power and energy consumption reduction in real time embedded processors. This work targets to reduce the processor power consumption without violating the real time constraints. Method: In this work, a dynamic power management technique named dynamic counters is employed in real-time system to minimize power consumption. The proposed method facilitates bounding of the events conservatively for effective bounding of future workload. It also employs scheduling ON and OFF time of the devices based on workload bounding at run-time. Simulation analysis is carried out to confirm the performance enhancement of the proposed method. Findings: Energy consumed by the processor increases with the number of event arrivals and switching of modes facilitates significant energy savings. Improvement: Run-time and memory overheads are overcome by dynamic counter technique. Effective bounding of future workload enhances computational efficiency.

Rapid determination of gross alpha/beta activity in milk using liquid scintilation counter technique

Rapid determination of gross alpha and beta emitters in milk by liquid scintillation counter is discussed. This method is based on direct addition of different types of milk into scintillation cocktail and therefore it is very promising for fast determination of alpha/beta activity due to direct alpha and beta separation, measurement in close 4p geometry and without sample treatment. The selected group of radionuclides was chosen with the respect to military significance, radio-toxicity, and possibility of potential misuse. As model radionuclides 241Am, 239Pu, and 90Sr were selected. The Liquid Scintilation Counter Hidex 300 SL equipped with triple-double-coincidence-ratio technique was used for sample measurement. The aim of the work was focused on comparison of different cocktails produced by Hidex and Perkin Elmer, choosing the best cocktail based on our measurement results and adjustment of its appropriate volume. Furthermore, the optimization of ratio between the volume of scintillation cocktail and the volume of urine was investigated with the respect to the model radionuclides. According to the obtained results, the efficiency for alpha emitters was greater than 85% and for beta, greater than 95%. The obtained results allowed this method to be used for rapid determination of gross alpha/beta activity in cases where time is an essence, such as first responders or mass-scale samples, where ordinary means suffer from lack of capacity or simply collapse under the onslaught.

C-12: MEMS Coulter counters for dynamic impedance measurement of time sensitive cells

There is a long history of cryobiologists adapting a Coulter counter to measure cellular biophysical parameters including establishing that cells are ideal osmometers, estimating water and solute permeabilities and their activation energies, and measuring isosmotic volume. These techniques have been used in many cell types to facilitate prediction of optimal protocols for CPA addition and removal as well as optimal cooling and warming protocols. While it has advantages over other techniques in some aspects, the Coulter counter technique is also challenging in several scenarios. First, the technique requires large sample volumes and cell counts, and introduces a several second time lag between exposure to anisosmotic media and cell volume detection. In many cell types and at low temperatures, this lag may not critical, but for cells with very high surface area to volume ratios, or cells with very high water permeability, this lag makes accurate biophysical measurement nearly impossible. Moreover, it is experimentally challenging to perform measurements at temperatures other than ambient. Finally, volume measurements are taken from individual cells only once as they pass through an aperture. This yields a “population” permeability estimate, and requires considerable data reduction and advanced parameter estimation techniques to obtain mean biophysical parameter values. Here we describe the design, fabrication and testing of a MEMS Coulter counter specifically designed for dynamic biophysical measurements. In particular, as opposed to several existing MEMS Coulter counters that size static cells, ours has an ultrarapid mixing region in which individual cells are rapidly mixed with desired reagents (e.g. anisosmotic media) and their volumes are measured at ten specific time points. Our new approach allows initial measurement of cell responses in less than 100 ms, provides a much improved estimate of the population variance of water and solute permeability, and facilitates very simple temperature control of the system. We present initial data and analysis of system output.

Characterization of liposomes and silica nanoparticles using resistive pulse method

The ability to precisely count inorganic and organic nanoparticles and to measure their size distribution plays a major role in various applications such as drug delivery, nanoparticles counting, and many others. Here we employ a simple resistive pulse method that allows translocations, counting, and measuring size and velocity distribution of silica nanoparticles and liposomes with diameters from 50nm to 250nm. This technique is based on the Coulter counter technique but has nanometer size pores. It was found that ionic current drops when nanoparticles enter the nanopore of a pulled micropipette, producing a clear translocation signal. Pulled borosilicate micropipettes with opening 50–350nm were used as the detecting instrument. This method provides a direct, fast and cost-effective way to characterize inorganic and organic nanoparticles in a solution.

Nuclear and Coulomb interactions in coherent fragmentation of relativistic nuclei in a photoemulsion

The role of the nuclear and Coulomb interactions in coherent fragmentation of relativistic nuclei is discussed with the cluster-model analysis of the experimental data on the fragmentation of 7Li (P = 3A GeV/c) via the 3H + 4He channel in photoemulsion used as an example. The calculated electromagnetic contribution of ∼10% to the cross section is not in conflict with the photoemulsion data and the upper estimate of ∼40% derived from the earlier measurements of total cross sections for fragmentation of light nuclei using the counter technique. The observed irregularities in the differential cross section for 7Li fragmentation with a separated Coulomb peak at a very small momentum transfer Q are ascribed to the overlap of nuclear diffraction patterns arising from light (C, N, O) and heavy (Ag, Br) photoemulsion nuclei. The predicted diffraction cross sections in the inelastic channel drastically differ from the usual shape of nuclear diffraction in an elastic channel. For pure targets, they have a shape of oscillations with a few peaks of comparable intensity and show strong dependence on the form of the surface nuclear density and radii of the intranuclear cluster and target nucleus. The probability for two-body clustering in 7Li is estimated at about 0.7.

Impact of the non-uniform angular sampling on mechanical signals

Angular sampling is a useful tool to study cyclic rotating machine vibrations. It can be implemented by using computer order tracking, directly, or by extracting position information from an acceleration signal. Instantaneous speed can also be angularly sampled using a counter technique. Angular sampling is sensitive to hardware imperfections (optical encoder precision, electrical perturbation, etc.). Angular sampled signal quantification step or sampling frequency determination is not identical to time domain. Angular sampling is also not adapted to study time domain signals like impulse response. Some of these imperfections can be viewed as non-uniform sampling.Non-uniform sampling consists in introducing a jitter in an angular sampling position. This jitter is random and different for every position. This jitter can be caused physically by some inaccuracies in position sensor measurements. Sampling a time domain relative signal against the angle can also be viewed as a non-uniform sampling. In this case the jitter is caused by speed fluctuation (constant speed case). Non-uniform sampling introduces an additional noise (that can be cyclostationary at order 2 if the original signal is cyclostationary at order 1). Non-uniform sampling also acts as a low pass filter. Its cut-off frequency depends on jitter standard deviation.An experimental bench was built. This bench uses a synchronous data acquisition board, an arbitrary generator, and a non-uniform clock generator. Experimentations are performed using various jitter values (from 0.1% to 20%) and are corroborated by previous theoretical studies.

Polystyrene Beads as a Model System for Virus Particles Reveal Pore Substructure as they Translocate

Our research focuses on the extension of the resistive-pulse or Coulter counter technique to detect and analyze virus particles. Using polystyrene spheres as a model system, we show that particles can be distinguished not only by their size, but also by their charge, as they translocate through track-etched polyethylene terephthalate (PET) pores. In addition, we discovered that as a polystyrene sphere translocates, it reveals variations in the pore structure along its length as a series of peaks and valleys in the measured ionic current. This sequence of peaks and valleys is unique to a particular pore, but for that pore, we observed the same sequence for thousands of particle translocations, even particles of different size or with different charge. Also, particles translocating in the reverse direction through the pore give the reverse sequence of peaks and valleys in the ionic current.We analyzed this data to extract information about the particle velocity as it passes through the pore and examined how this effect could enhance virus sensing capabilities. For example, due to the unique pattern of peaks and valleys, it is possible to unambiguously detect when two particles are in the pore at the same time. In addition, we expect that this characteristic pattern will be modulated by the particle geometry. Therefore, it will likely be possible to distinguish between particles of the same size but different shapes. After these model system studies, we plan to test our system with actual virus particles.

Observation of Protein Adsorption Using a Synthetic Nanopore

Using the coulter counter technique with a single nanopore, we probed the non-specific adsorption of bovine serum albumin (BSA) to a silicon-based surface at the single molecule level. A potential bias was applied across a silicon nitride membrane containing a single nanopore that was immersed in KCl solution. Ionic current fluctuations across the nanopore revealed long-lived interactions of BSA with the silicon nitride. The nature of these interactions can be classified into two categories, suggesting that BSA adheres to the nitride surface in two distinct orientations. Knowing how proteins from the blood, like BSA, interact with silicon based materials is of growing importance as these materials are integrated into biosensors and medical devices. Acknowledgements: This research was supported by the NSF grant (DMR-0706517 and HRD-0703452) and the National Institutes of Health (R01 GM088403).

Wind Turbine Fault Detection Using Counter-Based Residual Thresholding

AbstractUp-down counters are commonly used in the aerospace industry for fault detection thresholding. This paper applies the up-down counter technique to detect wind turbine faults. The thresholding problem involves a tradeoff between false alarms and missed detections. Counter based thresholding can detect smaller faults with higher probability and lower false alarms than is possible using simple constant thresholds. This improvement is achieved by effectively introducing dynamics into the thresholding logic as opposed to decisioning based on a single time step. Up down counters are applied to the development of a fault detection system for a commercial sized 4.8MW wind turbine. Realistic fault scenarios in the sensing, actuation and drivetrain subsystems are considered. It is seen that most faults can be detected with fast detection times and minimal false alarms without implementation of more complex filtering and detection techniques on residuals.