Counting Efficiency Research Articles

Development of a 2D digital proton–proton scattering technique for hydrogen depth profiling

Measuring hydrogen concentration and determining its depth profile in different substrates has always been a major challenge for material science. Proton–proton scattering is a nondestructive technique for hydrogen analysis in thin samples. In this paper, the development of a 2D coincidence proton–proton spectroscopy was performed using a 3 MeV Van de Graaff accelerator. In the presented technique, the coincidence recording of the proton–proton scattering events by a waveform digitizer provides the sum‐difference energy spectrum of the correlated events. By determining the proton energy loss in the sample, the hydrogen depth profile was extracted. To correct the error in the counting efficiency due to the multiple scattering, the Monte Carlo simulation was performed using the Corteo code. The performance of the technique was tested by measuring the concentration of hydrogen on both sides of a thin layer of aluminum. The results confirmed that the established technique is sensitive enough to separate the hydrogen peaks of these two thin layers.

How to Improve the Efficiency of Check-In Counter: A Counter-Sharing Method

Improving the efficiency of check-in counters is a significant concern for airport operation management departments and airline companies. However, the existing studies mainly optimize the counter allocation based on the number of counters and airport demands, which needs more exploration on improving the utilization rate of check-in counters under the condition of unchanged resource allocation. In this paper, we propose a counter-sharing method to improve check-in efficiency by sharing the idle check-in counters in the adjacent check-in area. In the proposed counter-sharing method, we first define the passenger’s total walking distance and waiting time for queues as the metrics, then reassign the check-in areas and adjust the internal departure sequence of flights to maximize the counter-sharing rate. The numerical results indicate that the proposed counter-sharing method can improve the efficiency of check-in counters and reduce the passenger’s total walking distance and waiting time in the queue during the check-in process, which can enhance the airport’s operation efficiency and competitiveness.

Abstract A006: Loss of PMEPA1 gene isoform facilitates the development of hormone and radiation therapies resistance in prostate cancer cells

Abstract Introduction: Nearly all the patients receiving hormone treatment eventually progress into castration resistance stage. In addition, approximately 30% to 40% of patients receiving radiation treatment will develop resistance. The aberrant alterations of androgen receptor (AR) and transforming growth factor-β (TGF-β) signaling play critical roles in such processes. Our studies identified five PMEPA1 (Prostate Transmembrane Protein Androgen Induced 1) gene isoforms in prostate cancer cells. PMEPA1-b isoform was androgen responsive and inhibited androgen signaling. In contrast, PMEPA1 isoforms a and d were TGF-β inducible and suppressed TGF-β signaling. Loss or reduced expressions of PMEPA1 was detected in over 60% of prostate cancer samples. In this study, we investigated the impacts of PMEPA1 isoforms (a, b and d) on the development of hormone and radiation therapies resistance in prostate cancer. Methods: RNA-seq data of unmatched 50 benign and 499 malignant prostate samples from The Cancer Genome Atlas (TCGA) dataset, as well as 101 metastatic castration resistant prostate cancer (mCRPC) biopsy samples from Quigley lab at UCSF (WCDT dataset) were used to study the transcript levels of PMEPA1 isoforms (a, b and d) and their correlations to disease progression. Hormone dependent LNCaP cells and androgen independent PC-3, DU-145 cells were utilized to investigate the impacts of PMEPA1 isoforms (a, b and d) on the responses to of androgen inhibitors (enzalutamide and bicalutamide, 0, 5.0 and 25.0 nM) and radiation (0, 1.0 and 5.0 Gy). The vectors of pcDNA3.1-PMEPA1-a, -b and -d were transfected into prostate cancer cells via Lipofectamine, and endogenous PMEPA1 isoforms were knocked down by isoforms specific siRNAs. The cell growth was assessed by cell counting, BrdU incorporation and cell plating efficiency assays. The protein levels of AR and PSA were evaluated by immunoblotting. The transcript levels of PSA, NKX3.1, NEDD9 and THBS1 were assessed by RT-PCR technology. Results: The reduced transcript levels of PMEPA1 isoforms (a, b and d) were detected in mCRPC group. Lower expression of PMEPA1-b was significantly associated with earlier biochemical recurrence. The growth inhibition and androgen signaling blockage mediated by androgen inhibitors were explicitly reversed by depletion of PMEPA1-b in LNCaP cells. Ectopic PMEPA1-b in isoform b depleted LNCaP cells reinstituted the growth inhibition induced by androgen inhibitors. Knockdown of isoforms a and d conspicuously rescued the decreased cell proliferation and suppressed TGF-β signaling resulted from radiation treatment in PC-3 and DU-145 cells. Similarly, over-expression of PMEPA1-a and -d in siRNA treated cells recapitulated the growth inhibitory effects of radiation treatments. Conclusion: Loss of PMEPA1 gene isoforms (a, b and d) induced the development of resistance to hormone ablation and radiation treatments in prostate cancer cells in vitro through activating androgen and TGF-β signaling. Our research provided a new insight into treatment resistance mechanism of prostate cancer cells. Citation Format: Shashwat Sharad, Hua Li. Loss of PMEPA1 gene isoform facilitates the development of hormone and radiation therapies resistance in prostate cancer cells [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A006.

Surface grafted scintillation sensors for selective detection of low level plutonium alpha activity

In the present study, thin film based extractive scintillation sensors with improved pulse height and detection limits have been developed. This has been achieved by surface grafting of phosphate based monomer, bis[2-(methacryloyloxy) ethyl] phosphate) (BMEP) on different polyether sulfone (PES) polymer substrates such as sheet and scintillating polymer inclusion membrane (SPIM). The pulse height and counting efficiency has been observed to improve with increase in the fluor component, 2,5-diphenyloxazole (PPO) in SPIM, whose counting efficiency becomes comparable to PPO containing polystyrene film at 50% fluor component. The phosphate modified substrates have been characterized for their surface morphology and functional groups. The contact angle of water with poly(BMEP) grafted SPIM and PES sheet was found less compared to substrates without grafting, showing the surface to be distinctively hydrophilic, thereby confirming successful grafting of BMEP layer on PES sheet and SPIM. The substrates have been found to selectively extract Pu in presence of similar activity of 241Am from 2 molL-1 HNO3 and have been tested upto Pu activity level as low as 118 mBq. The polymeric substrates developed in present study are simple to use and can be easily deployed for field applications with remote monitoring for low level detection of Pu.

Research on the Method of Counting Wheat Ears via Video Based on Improved YOLOv7 and DeepSort.

The number of wheat ears in a field is an important parameter for accurately estimating wheat yield. In a large field, however, it is hard to conduct an automated and accurate counting of wheat ears because of their density and mutual overlay. Unlike the majority of the studies conducted on deep learning-based methods that usually count wheat ears via a collection of static images, this paper proposes a counting method based directly on a UAV video multi-objective tracking method and better counting efficiency results. Firstly, we optimized the YOLOv7 model because the basis of the multi-target tracking algorithm is target detection. Simultaneously, the omni-dimensional dynamic convolution (ODConv) design was applied to the network structure to significantly improve the feature-extraction capability of the model, strengthen the interaction between dimensions, and improve the performance of the detection model. Furthermore, the global context network (GCNet) and coordinate attention (CA) mechanisms were adopted in the backbone network to implement the effective utilization of wheat features. Secondly, this study improved the DeepSort multi-objective tracking algorithm by replacing the DeepSort feature extractor with a modified ResNet network structure to achieve a better extraction of wheat-ear-feature information, and the constructed dataset was then trained for the re-identification of wheat ears. Finally, the improved DeepSort algorithm was used to calculate the number of different IDs that appear in the video, and an improved method based on YOLOv7 and DeepSort algorithms was then created to calculate the number of wheat ears in large fields. The results show that the mean average precision (mAP) of the improved YOLOv7 detection model is 2.5% higher than that of the original YOLOv7 model, reaching 96.2%. The multiple-object tracking accuracy (MOTA) of the improved YOLOv7-DeepSort model reached 75.4%. By verifying the number of wheat ears captured by the UAV method, it can be determined that the average value of an L1 loss is 4.2 and the accuracy rate is between 95 and 98%; thus, detection and tracking methods can be effectively performed, and the efficient counting of wheat ears can be achieved according to the ID value in the video.

Demonstrating a Novel, Hidden Source of Spectral Distortion in X-ray Photon Counting Detectors and Assessing Novel Trigger Schemes Proposed to Avoid It.

X-ray photon counting spectral imaging (x-CSI) determines a detected photon's energy by comparing the charge it induces with several thresholds, counting how many times each is crossed (the standard method, STD). This paper is the first to demonstrate that this approach can unexpectedly delete counts from the recorded energy spectrum under some clinically relevant conditions: a process we call negative counting. Four alternative counting schemes are proposed and simulated for a wide range of sensor geometries (pixel pitch 100-600 µm, sensor thickness 1-3 mm), number of thresholds (3, 5, 8, 24 and 130) and medically relevant X-ray fluxes (106-109 photons mm-2 s-1). Spectral efficiency and counting efficiency are calculated for each simulation. Performance gains are explained mechanistically and correlated well with the improved suppression of "negative counting". The best performing scheme (Shift Register, SR) entirely eliminates negative counting, remaining close to an ideal scheme at fluxes of up to 108 photons mm-2 s-1. At the highest fluxes considered, the deviation from ideal behaviour is reduced by 2/3 in SR compared with STD. The results have significant implications both for generally improving spectral fidelity and as a possible path toward the 109 photons mm-2 s-1 goal in photon-counting CT.

Development and Application of Particle Transport Monte Carlo Simulation Modeling Toolkit

In particle transport Monte Carlo simulation, the manual modeling method is not suitable for complex geometric models. A Monte Carlo Simulation Modeling Toolkit (pyMCMT) is developed based on Python language. The toolkit can generate input card in several classical format such as MCNP and GDML format automatically. In this paper, two typical applications are presented based on the pyMCMT toolkit: 1, constructing a multilayer circular geometric model in complex density distribution by pyMCMT toolkit in order to satisfy the requirement of building large-space fine model with the influence of blast wave. A two-dimensional adaptive model is built for non-uniform atmospheric induced by blast wave. The number of the cells in this model is reduced vastly with the same model resolution; 2, producing the optimized weight window parameter using the mesh-based weight window variance reduction combined with density iteration method which is realized to solve the high statistical fluctuation and low counting efficiency problem in deep penetration process. The successful application of pyMCMT shows that pyMCMT is a modularized, parameterized, customizable and easy-to-debug toolkit for particle transport Monte Carlo simulation modeling, which can improve the modeling efficiency tremendously.

Aerosol optical properties calculated from size distribution measurements: An uncertainty study

We use Monte Carlo uncertainty propagation to estimate the uncertainty of aerosol scattering coefficients, σs, that have been derived from measured particle size distributions. We consider the particular case where the size distributions are measured using a combination of a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS). Uncertainties that are propagated include those intrinsic to the instruments and those that arise from variabilities in aerosol microphysical properties, including particle shape, density, and complex refractive index. Particular emphasis is put on the size dependent counting efficiency of both instruments which have weaknesses in a particle size range that dominates aerosol optical properties. The T-matrix method is utilized to simulate the effect of particle shapes on σs. To narrow the probability distribution of aerosol properties we discuss uncertainties for a single geographic location, which is the Southern Great Plains site (SGP) of the Department of Energy’s Atmospheric Radiation Measurement (ARM) User Facility. We estimate a 95% confidence interval for σs between −40% and +68%. A partial dependence analysis, for which we use generalized additive models, identifies uncertainties in counting efficiency and particle shapes as the dominant contributors to the size of the confidence interval.

Age-dating and assumptions testing of 226Ra and 228Ra decay series applied to barite chimneys and mud volcanoes in deepwater Gulf of Mexico

A chronological framework of ocean-based methane emissions is a prerequisite to identify the factors controlling the flux and duration of gas venting into the atmosphere.Here we report the results of a study of ubiquitous barite chimneys and barite-bearing mud volcanoes documented in association with methane seeps and gas hydrates at mid-bathyal depths in the Gulf of Mexico.The barites exhibit anomalously high 226Ra and 228Ra activities, orphans in the 238U/232Th decay chains, and are well suited for the application of 210Pb/226Ra and 228Th/228Ra dating methods. In order to account for the interference of impurities with the accuracy of the dates, gamma counts from paired raw and purified aliquots were evaluated. Chimneys yield a mean 228Th/228Ra age of 1.60 ± 0.25 yr (n = 16) and consistently younger 210Pb/226Ra ages. The biased 210Pb/226Ra ages are attributed to poor 210Pb counting efficiency, young chimneys with little 210Pb ingrowth and possibly an open system. Rapid vertical growth rates of 11.4 and 12.8 cm/yr established from 228Th/228Ra ages are comparable to barite chimney estimates from hydrothermal settings.In general mud volcanoes are distinguished from the chimneys by absence of 228Ra and 228Th and high 210Pb/226Ra ratios, occasionally >1 in the raw subsamples. A positive relation between 210Pb/226Ra and the amount of pyrite in the samples supports the contention that PbS, co-precipitated with pyrite in H2S-rich pore fluids, acts as the principal scavenger of external 210Pb resulting from decay of 222Rn in the pore fluids. The mud volcanoes 210Pb/226Ra assays yield consistent ages with a mean of 17.4 ± 1.8 yr (n = 9) after removal of the pyrite. The general absence of 228Ra and 228Th in the mud volcanoes, contrasting to their abundance in the chimneys, is attributed to the age difference between the barite geomorphic forms.The (228Ra/226Ra)o initial activities in the chimneys, representing the ratios in the fluids at the time of barite deposition, exhibit statistically distinct values of 1.084 ± 0.015 (n = 28) and 0.752 ± 0.023 (n = 4) at the two sampling sites separated by a 265 km stretch. These (228Ra/226Ra)o values match the range of oil-field brine values from deep siliciclastic reservoirs in the US Gulf Coast. The fluids maximum migration time from the source to the seafloor is estimated to be <20 yr on the basis of 228Ra presence in the chimneys. The assessment based on the radiometric ages supports the notion that barite deposition in the Gulf of Mexico is a relatively recent event.

Effects of the test aerosol on the performance of periodic technical inspection particle counters

A new scheme for periodical technical inspection (PTI) of diesel-engine exhaust based on the measurement of particle number (PN) concentration was recently introduced in several European countries. PN concentration is measured directly at the tailpipe using portable particle counters known as PN-PTI. The technical specifications of these instruments are defined at a national level, and the type-examination and verification procedures differ considerably among European countries. In this study, we examined how the choice of test aerosol can affect the counting efficiency profile of the PN-PTI sensors, the majority of which are based on diffusion charging (DC). Carbonaceous aerosols were produced by combustion and spark discharge generators, sodium chloride (NaCl) particles were generated from aqueous solutions using several commercially available nebulizers and silver particles were produced by a silver particle generator. In most cases, the response of DC-based sensors depended strongly on the morphology of the test particles. Comparison with a Euro 3 diesel engine without a diesel particle filter (DPF) indicated that the combustion aerosols generated by combustion generators were the best proxy for soot emitted by diesel vehicle engines. On the contrary, the use of NaCl and spark discharge particles as test aerosols led in some cases to an over- or underestimation of the PN concentration by up to about a factor of two. Moreover, our results showed that the response of each type of DC-based sensors is individual and, as a result, it is impossible to determine a generally applicable factor to correct for the impact of the test aerosol properties. We recommend that the verification of PN-PTI instruments be preferably performed with soot particles produced by a combustion generator (identical or similar to the one used during the type-examination) in order to avoid corrections for the impact of the material on the response of the instruments.

Laboratory measurements with solid particle number instruments designed for periodic technical inspection (PTI) of vehicles

Particulates emitted by vehicles can be significantly reduced with the use of particulate filters. In some European countries, the control of these filters’ efficiency during their lifetime is done with a recently introduced solid particle number (SPN) test at low idling performed during periodic technical inspection (PTI) of Diesel vehicles. This paper examines the counting efficiency, linearity, and volatile removal efficiency of seven SPN-PTI instruments with laboratory-based particle generators and with vehicle exhaust. Some challenges related to low monodisperse particles concentration were identified during counting efficiency tests and discussed in view of type examination procedures. In agreement with the current metrological requirements, the maximum error (i.e., deviation from reference) of all instruments at linearity checks was < 25 % in a wide range of concentrations when testing with carbonaceous particles but error levels depended on the particle material used for testing. Finally, tetracontane removal efficiency of all instruments was > 95 %.

Artificial neural network based coincidence correction for optical aerosol spectrometers

Many applications such as filter testing, healthcare, quality monitoring, and environmental measurements require precise aerosol quantification by optical aerosol spectrometers. This type of measurement equipment is capable of in-situ measurements and provides easy access to the size distribution of the particles. Due to the coincidence error, optical aerosol spectrometers are limited to applications with relatively low concentrations. At high concentrations, the counting efficiency is reduced, while the size distribution is shifted towards larger particles. In 1984 Raasch and Umhauer proposed an analytical correction method for the size distribution. Although the approach is easy to implement, it has some disadvantages. In this work, an alternative correction method for the size distribution is presented, which is based on neural networks. The performance of both correction methods is evaluated on the cumulative distribution of raw detector voltages. The relative error of the median, as well as an error integral over the whole distribution is used as a measure. The neural network-based method gives a correction result that shows approximately half the relative median error, and a third of the error integral compared to the method of Raasch and Umhauer, for high concentrations.

Experimental Counting Efficiency Calibration of In Situ Marine Radioactivity Monitoring Systems in Busan (Korea) Based on Seawater Salinity

Choi, Y.; Ji, Y.-Y., and Joung, S., 2023. Experimental counting efficiency calibration of in situ marine radioactivity monitoring systems in Busan (Korea) based on seawater salinity. Journal of Coastal Research, 39(2), 377–383. Charlotte (North Carolina), ISSN 0749-0208. In situ underwater gamma-ray spectrometry is an effective method for monitoring marine radioactivity. With in situ measurement, however, it is difficult to calibrate counting efficiency experimentally, and a simulation is thus generally used to calculate the theoretical efficiency without experimental verification. This paper proposes a method to establish experimental counting efficiency by estimating the radioactivity concentration of 40K, which is a natural radionuclide emitting a 1,461 keV gamma ray, based on the salinity of seawater. The measurement was performed in a marine monitoring system in Busan equipped with a 3″φ × 3″ NaI(Tl) detector in a tank filled with sampled seawater. The results were compared with the theoretical counting efficiency calculated by simulation to verify the validity of the simulation. The results confirmed the experimental efficiency and theoretical efficiency were in very good agreement. In addition, using the validated simulation, a theoretical efficiency curve according to the gamma-ray energy was obtained. For simpler application, the concept of radioactivity conversion factor in units of s–1 · Bq–1 · kg for each peak was proposed. If the ratio of the conversion factor of each peak to the factor of 40K is obtained, the conversion factors for artificial radionuclides, which are difficult to measure practically, can be estimated by multiplying these ratios by the 40K conversion factor.

Evolution of traceable radon emanation sources from MBq to few Bq

In the framework of the EMPIR project traceRadon, stable atmospheres with low-level radon activity concentrations have to be produced for calibrating radon detectors designed to measure outdoor air activity concentrations. The traceable calibration of these detectors at very low activity concentrations is of special interest to the radiation protection, climate observation, and atmospheric research communities.Radiation protection networks (such as the EUropean Radiological Data Exchange Platform (EURDEP)) and atmospheric monitoring networks (such as the Integrated Carbon Observation System (ICOS)) need reliable and accurate radon activity concentration measurements for a variety of reasons, including: the identification of Radon Priority Areas (RPA); improving the sensitivity and reliability of radiological emergency early warning systems (Melintescu et al., 2018); for more reliable application of the Radon Tracer Method (RTM) to estimate greenhouse gas (GHG) emissions; for improved global “baseline” monitoring of changing GHG concentrations and quantification of regional pollution transport (Chambers et al., 2016), (Chambers et al., 2018); and for evaluating mixing and transport parameterisations in regional or global chemical transport models (CTMs) (Zhang et al., 2021), (Chambers et al., 2019).To achieve this goal, low activity sources of radium with a variety of characteristics were produced using different methods. Sources ranging from MBq 226Ra down to several Bq 226Ra were developed and characterised during the evolution of production methods, and uncertainties below 2 % (k=1) were achieved through dedicated detection techniques, even for the lowest activity sources. The uncertainty of the lowest activity sources was improved using a new online measurement technique for which the source and detector were combined in the same device. This Integrated Radon Source Detector device, henceforth an IRSD, reaches a counting efficiency approaching 50 % through detection under quasi 2π sr solid-angle. At the time of this study the IRSD was already produced with 226Ra activities between 2 Bq and 440 Bq.To compare the working performance of the developed sources (i.e., to establish a reference atmosphere), study the stability of the sources, and to establish traceability to national standards, an intercomparison exercise was carried out at the PTB facility. Here we present the various source production techniques, the determination of their radium activity, and determination of their radon emanation (including assigned uncertainties). This includes details of the implementation of the intercomparison set-up, and a discussion of the results of the source characterisations.

Toward a simplified calibration method for 23 nm automotive particle counters using atomized inorganic salt particles

In 2011, the Euro 5b light-duty vehicle legislation introduced particle number (PN) limits for vehicle homologation. To measure PN concentrations, specific condensation particle counters (CPC) with a counting efficiency (CE) of 50% at 23 nm are required. The usage of such automotive CPCs will significantly increase with the upcoming legislation for PN measurements during periodic technical inspections, which comes along with the need for simple calibration methods for particle number counters using salt particles. In this work, we examined the counting characteristics of an automotive AVL 23 nm CPC with inorganic salt particles. We further investigated the usability of different atomized inorganic salt particles for calibration purposes focusing on CE and linearity. The CE varies greatly depending on the chemical salt composition: While NaI was fully activated down to 18 nm and linear over the full concentration range, the CE of other atomized salt solutions showed a strong concentration dependency with a d50 diameter ranging from 38.2 nm to 69.5 nm for atomized NaCl with increasing concentration. Such effects were not found for tube-furnace generated salt particles within similar concentration ranges. When a hot dilution was applied, the non-linear behavior was minimized and the CE overall increased, leading to a d50 of 27.3 nm for atomized NaCl. Based on those findings, we propose a simplified calibration method for automotive PN counters without the need for a differential mobility analyzer due to the high CE of atomized NaI particles.

Monte Carlo calculation of whole body counter efficiency factors for different computational phantoms

Individual monitoring can provide an estimate of the radioactivity present in the body of the exposed individuals. Periodic monitoring of occupationally exposed individuals is of great importance in case of accidental incorporation. Computational phantoms and Monte Carlo codes are often used to complement the calibration method of counting systems in internal dosimetry. Here, counting efficiency (CE) factors for a WBC system were calculated using MC simulations. The WBC system with a NaI(Tl) detector and the BOMAB phantom was modeled using three MC codes. After validation, the models were used to obtain CE values for a wide range of energies, and a CE curve was generated for the WBC system. To estimate the effects of anatomical differences on the measurement process, two anthropomorphic voxel phantoms were modeled using the VMC code. For the detector position with the highest CE value, the differences when comparing BOMAB results with the MaMP and Yale results were (-1 ± 6)% and (-1 ± 3)%, respectively. The results confirm that the use of the BOMAB phantom is a good approach for the calibration of the whole-body counter system. Measurements should be made at detector position with the highest CE values, and it is recommended to use the mean Monte Carlo CE values calculated in this work.

Platelet ve Ortalama Platelet Hacim Kinetiklerinin Ventilatör İlişkili Pnömoni İçin Prognostik Önemi

Objective: Platelets play an important role in cases of inflammation and infection, along with in the hemostatic process. The aim of study is to evaluate prognostic efficiency of platelet count (PC), mean platelet volume (MPV) and MPV/PC for mortality prediction in patients with ventilator-associated pneumonia (VAP). Methods: A total of 150 VAP patients were divided into two groups as Survivors (n=98) and Non-survivors (n=52) according to intensive care unit mortality. The PC and MPV on days 1 and 4 of VAP were evaluated. Results: Thirty (31%) patients in the survivors group and 35 (67%) patients in the non-survivor group had thrombocytopenia, respectively (p&lt;0.05). The non-survivor group had higher MPV and a higher MPV/PC on the 1st and 4th days, while the survivor group had higher PC levels, respectively (p&lt;0.05). Platelet count, MPV and MPV/PC had the highest AUC levels at day 4 (0.68, 0.80, 0.73, respectively). The prognostic values of day 4 MPV and MPV/PC measurements were similar (p=0.17). Day 4 PC were found to be negatively correlated with mortality (adjusted hazard ratio (aHR): 0.91, p=0.01). Day 4 MPV and MPV/PC values were the independent mortality predictors (aHR: 2.59, p&lt;0.01 and aHR: 1.63, p=0.01). The survival probability of VAP patients with &lt;9.25 fL of MPV day 4 was significantly higher than those with ≥9.25 fL (p=0.002, log-rank test) Conclusion: In addition to thrombocytopenia, MPV and MPV/PC are useful predictors of poor outcomes. Changes in MPV responses may be a more useful prognostic assessment tool for VAP patients than PC. Keywords: Immune response, mean platelet volume, platelets, prognosis, ventilator-associated pneumonia

Design and performance study of a proportional counter for low-energy X-rays

A cylindrical proportional counter based on a noble gas was designed to accurately measure low-energy X-ray radiation. The detection capability of the proportional counter with different gases and geometries was calculated through the Monte Carlo method. The optimal filling gas and applicable pipe diameter were determined according to the results of the Monte Carlo simulation. Then, energy calibration was performed at the monoenergetic X-ray radiation facility (MXRF) based on Bragg diffraction, and the energy calibration results were verified using the radionuclides 241Am and 129I. The relative deviation of the theoretical and measured values of the energy does not exceed 1.4%, and the energy resolution of the designed proportional counter is approximately 10%. It was proved that the linearity of the channel and energy of the proportional counter can be used for energy spectrum analysis, and the proportional counter has a good radionuclide recognition capability. Finally, the detection efficiency of the designed proportional counter was simulated and verified at multiple energy points. A detection efficiency calculation model was established through MCNP5, and the detection efficiency of the proportional counter was measured at the MXRF. The results of the experiment and simulation showed that the proportional counter could reach a highest detection efficiency of 92% in the low-energy region. The average deviation between the experiment and simulation was 1.63% at 10–34 keV and 3.90% at 34–75 keV. The proportional counter can be used for measurement and application of X-rays in the low-energy region.

Multiplexed Protein Detection and Parallel Binding Kinetics Analysis with Label-Free Digital Single-Molecule Counting.

Multiplexed protein detection is critical for improving the drug and biomarker screening efficiency. Here, we show that multiplexed protein detection and parallel protein interaction analysis can be realized by evanescent scattering microscopy (ESM). ESM enables binding kinetics measurement with label-free digital single-molecule counting. We implemented an automatic single-molecule counting strategy with high temporal resolution to precisely determine the binding time, which improves the counting efficiency and accuracy. We show that digital single-molecule counting can recognize proteins with different molecular weights, thus making it possible to monitor the protein binding processes in the solution by real-time tracking of the numbers of free and bound proteins landing on the sensor surface. Furthermore, we show that this strategy can simultaneously analyze the kinetics of two different protein interaction processes on the surface and in the solution. This work may pave a way to investigate complicated protein interactions, such as the competition of biomarker-antibody binding in biofluids with biomarker-protein binding on the cellular membrane.

ORGANIZATION OF MATHEMATICS LESSONS USING INFORMATION TOOLS

In order to improve the computer literacy of students, the organization of lessons using computer technologies, their impact on the efficiency of counting, memorization, quick work of students, and the development of creative skills are described. Currently, there are no educational institutions that do not use computers and the Internet during the period when digitalization activities are actively carried out in the fields of education in all regions of the Kyrgyz Republic. In this direction, every teacher, student and parent should be aware of information technology. Therefore, it is necessary to make it mandatory to use computer technologies, their types and means in educational processes. The article notes that the use of computer technology in the organization of lessons will undoubtedly increase students’ interest in the subject.