Total Transmissions Research Articles

A combined analytical and Monte Carlo method for detailed simulations of antiscatter grids in x-ray medical imaging: implementing scatter within the grid

Objective. To implement a hybrid method, which combines analytical tracking and interaction simulation using Monte Carlo (MC) techniques, in order to model photon transport inside antiscatter grids (ASG) for x-ray imaging. Approach. A new tally was developed for PENELOPE (v.2018) and penEasy (v. 2020) MC code to simulate photon transmission through ASGs. Two established analytical algorithms from the literature were implemented in this tally. In addition, a new hybrid method was introduced by extending one of the analytical algorithms to include photon-interactions inside the grid, while preserving the imaged grid structure. Calculations of primary (TP), scatter (TS), and total (TT) grid transmissions in addition to the Q factor (Q = TP2/TT ) were performed. The new tally was validated for a quadric geometry ASG, and experimental measurements with a PMMA phantom of several thicknesses. In addition, the contribution of the scatter inside the grid was studied for three interspace materials, and a high resolution image of the grid was simulated. Main results. An excellent agreement was found between the two analytical models compared with the quadric grid without scatter, and the hybrid method with the geometrical grid with scatter. Average deviations of 0.2% and 1.4% were found between TP and TS for the hybrid method and quadric grid, while for the hybrid method and experimental measurements these values were 1% and 20%. Antiscatter grids with aluminium as interspace material had the highest amount of scatter from inside the grid to the final image, followed up by paper fibre and air. The high resolution image of the grid was equivalent using the quadric geometry or the hybrid mode. Significance. The hybrid method provides a means of studying scattered radiation from the antiscatter grid with the advantage of higher performance, with results that are consistent with a full quadric geometry simulation of the ASG.

965. Projecting the Potential Clinical and Economic Impact of HIV Prevention Resource Reallocation in Tennessee

Abstract Background In 2023, the State of Tennessee rejected $6.2M in US Centers for Disease Control and Prevention (CDC) HIV prevention funding, redirecting support away from men who have sex with men (MSM), transgender women (TGW), people who inject drugs (PWID), and heterosexual Black women (HSBW), and towards first responders (FR), pregnant people (PP), and survivors of sex trafficking (SST). Methods We used a microsimulation model of HIV to compare the clinical impact of Current, present allocation of condoms, pre-exposure prophylaxis (PrEP), and HIV testing to CDC priority risk groups (MSM/TGW/PWID/HSBW); with Reallocation, diverting funds to increase HIV testing and linkage of Tennessee-determined priority populations (FR/PP/SST). We simulated Tennesseans with undiagnosed and incident HIV. Model inputs included condom use (45-67%), PrEP use (0.2-8%), HIV testing frequency (every 2.5-4.8 years), and 30-day linkage to HIV care (56-65%). We assumed Reallocation would reduce condom use (-4%), PrEP provision (-26%), and HIV testing (-47%) in MSM/TGW/PWID/HSBW while it would increase HIV testing among FR (+47%) and 30-day linkage to HIV care (to 100%/90%) among PP/SST; we varied these assumptions in sensitivity analyses. We conservatively assumed no impact of Reallocation on people with HIV already in care. 10-year model outcomes included HIV transmissions, numbers diagnosed and virologically suppressed, deaths, life-years lost, and cost/death averted. Results Over 10 years, Current would lead to 6,678 total HIV transmissions, 1,989 deaths, and 85,270 life-years in Tennessee (Table 1). Reallocation would lead to 178 additional HIV transmissions, 219 additional HIV deaths, and 985 more life-years lost; more people would be undiagnosed and fewer would be virologically suppressed (Figure 1). Under Current, Tennessee would spend $263,830/death averted; under Reallocation, $4,133,330/death averted, a 1,470% increase in cost/death averted (Table 2). Results were most sensitive to reductions in HIV testing rates under Reallocation.Figure 1.Number of simulated people with HIV in Tennessee who have undiagnosed HIV, compared to people who have diagnosed HIV and are virologically suppressed at 10 years Figure 1 presents the projected number of people with HIV across each risk group who are undiagnosed (light shade) compared to those who are diagnosed and virologically suppressed (dark shade) at 10 years under the Current (blue) and Reallocation (gray) scenarios. Under Current, there are fewer total people with undiagnosed HIV, and more people with diagnosed HIV at year 10 compared with Reallocation. Reallocation does increase the number of people with HIV who are virologically suppressed amongst first responders, pregnant people, and survivors of sex trafficking; however, the increase is relatively small compared to the decrease in virologic suppression among men who have sex with men, transgender women, people who inject drugs, and heterosexual Black women. *Survivors of sex trafficking are assumed to be diagnosed when freed from sex trafficking in Current and Reallocation, but in Reallocation the linkage to HIV care is assumed to increase from 56% to 90%. Conclusion Reallocation of HIV prevention funding in Tennessee would greatly harm MSM/TGW/PWID/HSBW, confer minimal benefits for FR/PP/SST, and cannot be justified on either clinical or epidemiological grounds. Disclosures Allison Agwu, MD, MSc, Gilead: Board Member|Gilead: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|ViiV: Board Member

Efficient 1×2, 1×4, 1×8 and 1×16 photonic crystal filters/power splitters based ring resonators for modern passive optical network PON

In this paper, we propose a new architecture of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] optical filter/power splitters operating around 1.55[Formula: see text][Formula: see text]m, based on a CPs 2D photonic crystal ring resonator for Modern Passive Optical Network (PON). This type of functionality, filtering/power splitting is introduced in this work for the first-time according literature. The designed device consists of a square array of GaAs dielectric rods immersed in air. The structure is designed and successfully simulated by the finite element method using the software COMSOL Multiphysics. From the results obtained, we note that the beam is evenly distributed for all output ports with total efficient transmissions of about 99.6%, 98.8%, 97.1% and 96.8% and low insertion losses of about 0.017, 0.052, 0.128, and −0.14[Formula: see text]dB for the [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] filter power splitter successively.

PO-03-056 QUANTIFYING THE FREQUENCY AND ACCURACY OF DEVICE-INDICATED ATRIAL FIBRILLATION EPISODES ACROSS DEVICE MANUFACTURERS

Despite standardization efforts, cardiac implantable electronic devices (CIED) report atrial fibrillation (AF) episodes differently across device manufacturers. Similarly, traditional cardiac rhythm management (CRM) protocols have failed to standardize physician-indicated AF. Thus, few studies have characterized the frequency and accuracy of device-indicated AF. This study quantified and compared physician- (‘true’ AF incidence) and device-indicated AF across two patient segments and by CIED manufacturer. Baptist Health Network in Kentucky uses a CRM care platform (Murj, Santa Cruz, CA) to manage 12,000 patients across 14 clinics. Both device- and physician- indicated AF transmissions in 10,986 CIED patients (age 76+12 yrs) including pacemakers, ICD, CRT-P, CRT-D implants between 10/1/2020-5/31/2022 were assessed. AF transmissions were also analyzed in 3,290 (30% of 10,986 pts) pacer dependent or heart block (HB) patients (defined as AV block or had a non-CRT device with average RV pacing >90%) (age 80+11 yrs). True physician-indicated AF episodes represented 31% & 33% of all pts & HB transmissions corresponding with 72% & 68% all pacing/HB pts. Device-indicated AF represented 32% & 33% all pacing/HB transmissions. Overall, 19% & 20% all pacing/HB transmissions were true positives (TP=device- & physician-indicated AF). Device percentages by manufacturer were 35% Boston Scientific, 29% St. Jude, 27% Medtronic, and 8% Biotronik. Medtronic had the lowest device-indicated AF transmissions/pt, the highest true positive rate at 75% (TPR=true positives / total device-indicated AF transmissions) & highest false negative rate at 30% (FNR=false negatives/ total device-indicated normal transmissions). Biotronik had the highest false positive rate at 50% (FPR= false positives/ total device-indicated AF transmissions) & lowest false negative rate (FNR) at 14%. The mean TPR was 61%+11% per manufacturer. The Murj CRM system allows greater standardization of device- and physician-indicated AF episodes, enabling quantification of device-indication frequency and accuracy. In this study, physician-indicated AF was common (72% all pacing patients; 68% HB patients) with often inaccurate AF device classifications. Alternating high FPR and FNR by manufacturers highlight the optimization challenge of reducing false alarms while maintaining a high TPR. Studies like this provide critical context for clinicians interpreting device-indicated events across manufacturers required by CRM.

Stochastic dynamic programming solution to transmission scheduling: Multi sensor-multi process with wireless noisy channel

We investigate sensor scheduling for remote estimation when multiple smart sensors monitor multiple stochastic dynamical systems. The sensors transmit their measurements to a remote estimator through a noisy wireless communication channel. Such a remote estimator can receive multiple packets simultaneously sent by local sensors. Sensors transmit their measurements if their Signal Interference and Noise Ratio (SINR) is above a threshold. We compute the optimal policy for sensor scheduling by minimizing expected error covariance subject to total signal transmissions from all sensors. We model this problem as Markov Decision Process (MDP) with discounted cost per stage in the finite time horizon framework, then we employ stochastic Dynamic Programming as the optimization method. A novel algorithm based on sampling and machine learning techniques is proposed as the approximation. At each phase of the DP algorithm, samples are collected using a uniform probability distribution. The data is used to feed Neural Network (NN) and Random Forest (RF) models for cost function and policy approximation. The results of the proposed framework are supported by simulation examples comparing RF and NN as Approximate DP (ADP). Note that this idea builds a bridge among the recent advances in the area of data science, Machine Learning, and the ADP.

Topology Driven Cooperative Self Scheduling for Improved Lifetime Maximization in WSN

In Wireless Sensor Network (WSN), scheduling is one of the important issues that impacts the lifetime of entire WSN. Various scheduling schemes have been proposed earlier to increase the lifetime of the network. Still, the results from such methods are compromised in terms of achieving high lifetime. With this objective to increase the lifetime of network, an Efficient Topology driven Cooperative Self-Scheduling (TDCSS) model is recommended in this study. Instead of scheduling the network nodes in a centralized manner, a combined approach is proposed. Based on the situation, the proposed TDCSS approach performs scheduling in both the ways. By sharing the node statistics in a periodic manner, the overhead during the transmission of control packets gets reduced. This in turn impacts the lifetime of all the nodes. Further, this also reduces the number of idle conditions of each sensor node which is required for every cycle. The proposed method enables every sensor to schedule its own conditions according to duty cycle and topology constraints. Central scheduler monitors the network conditions whereas total transmissions occurs at every cycle. According to this, the source can infer the possible routes in a cycle and approximate the available routes. Further, based on the statistics of previous transmissions, the routes towards the sink are identified. Among the routes found, a single optimal route with energy efficiency is selected to perform data transmission. This cooperative approach improves the lifetime of entire network with high throughput performance.

Automatic fault identification in WSN‐based smart grid environment

SummaryWireless sensor network (WSN) plays a vital role in the smart grid (SG) environment. Due to the fault tolerance characteristics, cost reduction, and large‐scale convergence, SG introduces many unique challenges caused by system and functional devices. To solve this problem, a WSN‐based SG network is used to identify faults. During data transmission, faulty nodes occur in the transmission line. The node failures, calibration, network failures, low battery, dead nodes, environmental changes, software failures, and so on lead to the interruption in data delivery and spoil the entire WSN‐based SG network. In order to tackle these problems, the new WSN model is designed to detect the faults in the transmission line based on the SG environment. This paper uses the Adaptive Zigbee‐Aquila communication protocol (AZACP) to find the optimal shortest path for transferring data. AZACP finds the shortest optimal path for transmitting the sensed data to the base station with low cost and less time consumption. Fault detection automatically identifies the fault in the transmission line and isolates the faulty nodes to ensure efficient data transmission in WSN. Here, enhanced recurrent equilibrium neural network (ERENN) is introduced to identify the fault in data transmission. The proposed approach provides better performance in terms of evaluating performance metrics like throughput, delay, reliability, average residual energy, number of total transmissions, network lifetime, efficiency, and bit error rate (BER).

DISTRIBUTION OF FALSE ARRHYTHMIC ALERTS FROM IMPLANTABLE LOOP RECORDERS IN THE PHILIPS GENEVA HEALTH SOLUTIONS IMPLANTABLE DEVICE REMOTE MONITORING DATABASE

BackgroundImplantable loop recorders (ILR) are the gold standard for extended diagnostic cardiac monitoring. Accurate detection of arrhythmias is paramount to data integrity. Unnecessary remote transmissions generated due to oversensing or undersensing of the cardiac electrogram (EGM) is a significant source of data deluge in ILR monitoring.ObjectiveIllustrate the distribution of transmissions archived with False detection of Atrial Fibrillation (AF), Pause, Bradycardia, and Tachycardia due to oversensing or undersensing on ILR transmissions.MethodsA retrospective analysis of ILR transmissions processed in 2021 was performed utilizing discrete data from the Philips Geneva Health Solutions database. Transmissions were either forwarded to a practitioner for review or archived, if adjudicated as non-clinically actionable. Discrete data statements categorizing false triggers due to oversensing or undersensing were queried to obtain total transmissions with false events. In addition, data was stratified by manufacturer.ResultsIn 2021, 485,755 ILR transmissions were processed by Geneva Remote Technicians; 36% were forwarded to practitioners, 64% were archived. Transmissions archived due to oversensing or undersensing of the EGM were identified in 20% (97,691) of all processed transmissions; a False AF event occurred in 54% (59,661), False Pause in 33% (35,755), False Tachycardia in 10% (10,561), and False Bradycardia in 3% (3,673).ConclusionFigure 2: Distribution of ILR transmissions in 2021 archived due to oversensing or undersensing by event type.View Large Image Figure ViewerDownload Hi-res image Download (PPT) BackgroundImplantable loop recorders (ILR) are the gold standard for extended diagnostic cardiac monitoring. Accurate detection of arrhythmias is paramount to data integrity. Unnecessary remote transmissions generated due to oversensing or undersensing of the cardiac electrogram (EGM) is a significant source of data deluge in ILR monitoring. Implantable loop recorders (ILR) are the gold standard for extended diagnostic cardiac monitoring. Accurate detection of arrhythmias is paramount to data integrity. Unnecessary remote transmissions generated due to oversensing or undersensing of the cardiac electrogram (EGM) is a significant source of data deluge in ILR monitoring. ObjectiveIllustrate the distribution of transmissions archived with False detection of Atrial Fibrillation (AF), Pause, Bradycardia, and Tachycardia due to oversensing or undersensing on ILR transmissions. Illustrate the distribution of transmissions archived with False detection of Atrial Fibrillation (AF), Pause, Bradycardia, and Tachycardia due to oversensing or undersensing on ILR transmissions. MethodsA retrospective analysis of ILR transmissions processed in 2021 was performed utilizing discrete data from the Philips Geneva Health Solutions database. Transmissions were either forwarded to a practitioner for review or archived, if adjudicated as non-clinically actionable. Discrete data statements categorizing false triggers due to oversensing or undersensing were queried to obtain total transmissions with false events. In addition, data was stratified by manufacturer. A retrospective analysis of ILR transmissions processed in 2021 was performed utilizing discrete data from the Philips Geneva Health Solutions database. Transmissions were either forwarded to a practitioner for review or archived, if adjudicated as non-clinically actionable. Discrete data statements categorizing false triggers due to oversensing or undersensing were queried to obtain total transmissions with false events. In addition, data was stratified by manufacturer. ResultsIn 2021, 485,755 ILR transmissions were processed by Geneva Remote Technicians; 36% were forwarded to practitioners, 64% were archived. Transmissions archived due to oversensing or undersensing of the EGM were identified in 20% (97,691) of all processed transmissions; a False AF event occurred in 54% (59,661), False Pause in 33% (35,755), False Tachycardia in 10% (10,561), and False Bradycardia in 3% (3,673). In 2021, 485,755 ILR transmissions were processed by Geneva Remote Technicians; 36% were forwarded to practitioners, 64% were archived. Transmissions archived due to oversensing or undersensing of the EGM were identified in 20% (97,691) of all processed transmissions; a False AF event occurred in 54% (59,661), False Pause in 33% (35,755), False Tachycardia in 10% (10,561), and False Bradycardia in 3% (3,673). Conclusion

ENZ-metamaterial–induced perfect transparency for the highly directive plano-concave lens

We propose an ENZ-metamaterial–based transparent sandwich design consisting of periodic slits in a metal screen integrated with ENZ metamaterials for the exploration of superior transmissions. An equivalent circuit is proposed to reveal the interactions between the slit array and ENZ metamaterials when electromagnetic fields are penetrating through, and indicates that the involvement of ENZ metamaterials with the frequency dispersion behaviors can create the perfect match for total transmissions. On this basis, we further propose the design of plano-concave lens with the non-uniform ENZ metamaterial interlayer and demonstrate the superior collimation and focusing of electromagnetic fields at specific frequency points with perfect transparency. These findings may initiate the quest for building up more advanced electromagnetic devices tailored to specific applications with extreme parameter metamaterials.

Human Immunodeficiency Virus transmission by HIV Risk Group and Along the HIV Care Continuum: A Contrast of 6 US Cities.

Understanding the sources of HIV transmission provides a basis for prioritizing HIV prevention resources in specific geographic regions and populations. This study estimated the number, proportion, and rate of HIV transmissions attributable to individuals along the HIV care continuum within different HIV transmission risk groups in 6 US cities. We used a dynamic, compartmental HIV transmission model that draws on racial behavior-specific or ethnic behavior-specific and risk behavior-specific linkage to HIV care and use of HIV prevention services from local, state, and national surveillance sources. We estimated the rate and number of HIV transmissions attributable to individuals in the stage of acute undiagnosed HIV, nonacute undiagnosed HIV, HIV diagnosed but antiretroviral therapy (ART) naïve, off ART, and on ART, stratified by HIV transmission group for the 2019 calendar year. Individuals with undiagnosed nonacute HIV infection accounted for the highest proportion of total transmissions in every city, ranging from 36.8% (26.7%-44.9%) in New York City to 64.9% (47.0%-71.6%) in Baltimore. Individuals who had discontinued ART contributed to the second highest percentage of total infections in 4 of 6 cities. Individuals with acute HIV had the highest transmission rate per 100 person-years, ranging from 76.4 (58.9-135.9) in Miami to 160.2 (85.7-302.8) in Baltimore. These findings underline the importance of both early diagnosis and improved ART retention for ending the HIV epidemic in the United States. Differences in the sources of transmission across cities indicate that localized priority setting to effectively address diverse microepidemics at different stages of epidemic control is necessary.

Phononic crystals as a platform for experimental physics: The direct observation of Klein tunneling

Phononic crystals consist of periodic Mie scatterers that modulate the band structure through multi-scattering to control acoustic wave propagation. Recently, the Dirac cone dispersion of phononic crystals with triangular or hexagonal lattices has been used to demonstrate interesting physics such as topologically protected edge states and Zitterbewegung effects. In this work, we present phononic crystals with triangular lattices that can be used as a platform to directly observe Klein tunneling. Klein tunneling is an important quantum mechanical physics proposed in 1929 for high-energy electrons. Klein suggested that electrons that are accelerated to the relativistic regime will tunnel through potential barriers with 100% probability regardless the width and height of the potential barrier. However, Klein tunneling has never been directly observed in quantum mechanics and solid state physics due to the difficulties in satisfying the stringent requirements. Here, we designed phononic crystals with Dirac cone dispersion at which the phonons behave as quasi-particles in the relativistic regime. Near total transmissions of the phonons through potential barriers were measured that are independent from the width and height of the potential barrier. Our results provide the first direct observation of Klein tunneling. This work will inspire a new type of applications that uses phononic crystals as a platform for the experimental studies of wave mechanics and quantum physics.

Resource Use and Economic Implications of Remote Monitoring With SubcutaneousCardiacRhythm Monitors.

This study reports resource use and economic implications of rhythm monitoring with subcutaneous cardiac rhythm monitors (SCRMs). SCRMs generate a substantial amount of data that requires timely adjudication for appropriate clinical care. Resource use for SCRM monitoring is not known. The study included consecutive transmissions during 4weeks from 1,811 SCRMs. Resource use was quantified by assessment of time commitment of device clinic personnel and electrophysiologists for data adjudication. Incidence and characteristics of false positive (FP) episodes were assessed. Impact of custom programming for arrhythmia detection on incidence of FP episodes and resource use was analyzed. A total of 1,457 transmissions (alerts=462; full downloads=995) were received during study period. Average device clinic personnel time for adjudication of 1 transmission was 15 ± 6min. This totaled to 364h spent (2.3 full-time staff) over the 4-week period, which translated into a salary cost of $12,000 U.S. dollars (USD). Average time spent by an electrophysiologist for 1 transmission was 1.5 ± 1min and totaled to 37h for 4weeks, which translated into an estimated cost of $9,600 USD. Of 1,457 total transmissions, 512 (35%) represented multiple transmissions from the same patients, which resulted in no additional reimbursement. Incidence of FP episodes in the entire cohort was 50% and was variable in alert (60%) and full download (49%) (p=0.04) transmissions. When SCRMs with manufacturer suggested nominal programming and institutional custom programming were compared, there was a reduction in FP episodes (55% vs. 16%; p=0.01), which translated to a 34% reduction in resource use for data adjudication. SCRM data adjudication requires significant resources. Custom programming for SCRMs may overcome the data deluge.

Distributive Throughput Optimization for Massive Random Access of M2M Communications in LTE Networks

Machine-to-machine (M2M) communications, which aims to enable autonomous communication between machine devices with minimum human intervention, have experienced remarkable growth over the past few years. In massive M2M communications, random access (RA) collision is one of the critical problems at the network entry stage. To alleviate the channel contention during the network access stage, most existing RA solutions for M2M communications need the base station (BS) to determine backoff parameters, whose optimal values are hard to obtain and would also incur substantial signaling overhead, especially in dense scenarios. To address this issue, a distributive approach is highly desirable. In this paper, a new method for distributive estimation of optimal backoff parameters is proposed. Specifically, each machine type device (MTD) only needs to observe their own successful and total transmissions of access requests during an estimation interval, after which each MTD can obtain an estimation of the optimal backoff parameters according to an explicit expression of the observed statistics. It is found that the estimation interval determines the performance of the proposed scheme. When the number of MTDs in the network does not change or varies slowly, the network throughput can be maximized if the estimation interval is chosen properly. Compared to existing centralized methods, the proposed method can achieve similar performance with much lower signaling overhead. The proposed scheme can be applied for both homogeneous and heterogeneous scenarios and provide a practical access design method for M2M communications.

Data Collection Practices of Mobile Applications Played by Preschool-Aged Children

Child-directed mobile applications (apps) have been found to collect digital identifiers and transmit them to third-party companies, a potential violation of federal privacy rules. This study seeks to examine the differences in app data collection and sharing practices by evaluating the sociodemographic characteristics of the children who play them. To examine data collection and sharing practices of 451 apps played by young children and to test associations with child sociodemographic characteristics. This study used data from the baseline phase of the Preschooler Tablet Study, a prospective cohort study conducted from August 2018 to January 2020. This study used a population-based sample. A convenience sample of the parents of preschool-aged children was recruited from pediatric offices, childcare centers, social media posts, and an online participant registry. Eligibility criteria included (1) parent or guardian of a child aged 3 to 5 years, (2) parent or guardian who lived with the child at least 5 days per week, (3) participants who spoke English, and (4) a child who used an Android (Google LLC) device. All interactions with participants were through email, online surveys, and mobile device sampling. Sociodemographic characteristics were assessed by parental report. This study tested the hypothesis that data transmissions to third-party domains are more common in apps played by children from low-socioeconomic-status homes. Child app usage was assessed via a mobile sampling app for an average of 9 days. Persistent identifier data transmissions to third-party domains were quantified for each app using an instrumented Android environment with monitoring of network traffic; for each child, the counts of total data transmissions were calculated, and the total third-party domains were detected for the apps they played. Our sample comprised 124 children who used Android devices (35 tablets, 89 smartphones; 65 girls [52%]; mean [SD] age, 3.85 [0.57] years; 87 non-Hispanic White [71%]). One hundred twenty of participating parents (97%) were women. Of 451 apps tested, 303 (67%) transmitted persistent identifiers to 1 to 33 third-party domains. Child data transmission counts ranged from 0 to 614 (median [interquartile range], 5.0 [1-17.5]) and third-party domain counts from 0 to 399 (4.0 [1-12.5]). In multivariable negative binomial regression models, higher transmission and third-party domain rates per app were positively associated with older age (rate ratio, 1.67 [95% CI, 1.20-2.33]; P = .002 and 1.69 [95% CI, 1.26-2.27]; P < .001, respectively) and lower parent educational attainment (eg, high school or General Educational Development or less rate ratio, 2.29 [95% CI, 1.20-4.39]; P = .003 and 2.05 [95% CI, 1.13-3.70]; P < .02, respectively), but not with household income. This study found that apps used by young children had a high frequency of persistent identifier transmissions to third-party companies, suggesting that federal privacy rules are not being enforced. Older children, those with their own devices, or those from lower-education households may be at higher risk of potential privacy violations.

Wireless Subnanosecond RF Synchronization for Distributed Ultrawideband Software-Defined Radar Networks

In this article, we present a distributed and decentralized synchronization algorithm for wireless sensor networks (WSNs). The proposed method achieves subnanosecond synchronization using low-cost commercial-off-the-shelf (COTS) Universal Software Radio Peripheral (USRP) software-defined radios (SDRs) and is implemented entirely in software without the need for custom hardware or atomic clocks. In an N sensor network, the proposed protocol results in each sensor having full knowledge of baseband clock offsets, RF carrier phase offsets, and pairwise RF time of flight to subnanosecond precision for the entire network after 2N total transmissions, making this method efficiently extendible to larger sensor networks. The method is decentralized and does not rely on a hierarchical master-slave structure, making it robust to sensor dropout in contested or harsh environments. The proposed methodology is validated in simulation and tested in field experiments using a three-sensor network. This work has a wide range of applications, including transmit (TX) beamforming, distributed sensor localization, and coherent multistatic/multiple-input-multiple-output (MIMO) radar imaging for autonomous sensor swarms.

Transmission Scheduling for Remote Estimation with Multi-packet Reception under Multi-Sensor Interference

In networked control systems, due to competing demands on bandwidth and energy constraints, sensor scheduling is an important problem for remote estimation and control tasks. Traditionally, a single sensor is scheduled in each resource block to avoid interference or collisions so that the probability of packet loss is reduced. However, receiving multiple packets from different sources under interference is routinely achieved in wireless networks using multi-packet reception techniques. In this work, we explore the problem of sensor scheduling for remote estimation when the estimator is able to simultaneously receive multiple packets. We use the typical signal-to-interference-and-noise-ratio (SINR) based capture model to compute the packet arrival probabilities. Then an optimal scheduling policy is determined by minimizing expected estimation error covariance subject to a constraint on the average number of total transmissions. In the case of two sensors, for a scalar system and for a decoupled two-dimensional system, we show that allowing multiple simultaneous transmissions can improve the quality of the estimation achieving lower energy consumptions and we provide structural results on the optimal policies. Numerical results illustrate the benefits of multi-packet reception in remote estimation.

Sleep and wake are shared and transmitted between individuals with insomnia and their bed-sharing partners.

Patients with insomnia frequently report disturbing, or being disturbed by, their bedpartner. We aimed to (1) characterize how individuals with insomnia and their bedpartners influence each other's sleep and (2) identify characteristics predicting vulnerability to wake transmission. Fifty-two couples (aged 19-82 years), where one individual was diagnosed with insomnia, participated. Sleep/wake patterns were monitored via actigraphy and sleep diaries for seven nights. Minute-by-minute sleep and wake concordance (simultaneous sleep/wake epochs), number of wake transmissions received (awakenings immediately preceded by wakefulness in the bedpartner), percent wake transmissions received (percentage of total awakenings that were transmitted), and percent of bedpartner's wake minutes resistant to transmission (ability to sleep through bedpartner wakefulness) were calculated. Mixed-effects modeling assessed within-couple bedtime and chronotype differences as predictors of dyadic sleep. We described rates of sleep concordance (MPatient = 63.8%, MPartner = 65.6%), wake concordance (MPatient = 6.6%, MPartner = 6.6%), total transmissions received (MPatient = 5.5, MPartner = 6.9 per night), percent transmissions received (MPatient = 18.5%, MPartner = 23.4% of total awakenings), and percent minutes resistant (MPatient = 56.4%, MPartner = 58.6% of bedpartner's wake time). Partners received wake transmissions at 1.25 times the rate of patients. Percent transmissions received was increased in couples with concordant bedtimes and individuals with later chronotype than their bedpartner. Patterns of chronotype and bedtime order predicting percent minutes resistant to transmission differed across the length of the rest interval. Transmission provides a novel characterization of how bedpartners influence sleep and provide insight into mechanisms of insomnia generation and maintenance. Understanding modifiable risk factors may provide ways to personalize insomnia treatments. Clinical Trial Researching Effective Sleep Treatments (Project REST), ANZCTR Registration: ACTRN12616000586415.

Tracking Pseudomonas aeruginosa transmissions due to environmental contamination after discharge in ICUs using mathematical models

Pseudomonas aeruginosa (P. aeruginosa) is an important cause of healthcare-associated infections, particularly in immunocompromised patients. Understanding how this multi-drug resistant pathogen is transmitted within intensive care units (ICUs) is crucial for devising and evaluating successful control strategies. While it is known that moist environments serve as natural reservoirs for P. aeruginosa, there is little quantitative evidence regarding the contribution of environmental contamination to its transmission within ICUs. Previous studies on other nosocomial pathogens rely on deploying specific values for environmental parameters derived from costly and laborious genotyping. Using solely longitudinal surveillance data, we estimated the relative importance of P. aeruginosa transmission routes by exploiting the fact that different routes cause different pattern of fluctuations in the prevalence. We developed a mathematical model including background transmission, cross-transmission and environmental contamination. Patients contribute to a pool of pathogens by shedding bacteria to the environment. Natural decay and cleaning of the environment lead to a reduction of that pool. By assigning the bacterial load shed during an ICU stay to cross-transmission, we were able to disentangle environmental contamination during and after a patient’s stay. Based on a data-augmented Markov Chain Monte Carlo method the relative importance of the considered acquisition routes is determined for two ICUs of the University hospital in Besançon (France). We used information about the admission and discharge days, screening days and screening results of the ICU patients. Both background and cross-transmission play a significant role in the transmission process in both ICUs. In contrast, only about 1% of the total transmissions were due to environmental contamination after discharge. Based on longitudinal surveillance data, we conclude that cleaning improvement of the environment after discharge might have only a limited impact regarding the prevention of P.A. infections in the two considered ICUs of the University hospital in Besançon. Our model was developed for P. aeruginosa but can be easily applied to other pathogens as well.

Prioritize efficiently: Layer selection in network coding

Network coding simplifies routing decisions, improves throughput, and increases tolerance against packet loss. A fundamental limitation, however, is delay: decoding requires as many independent linear combinations as data blocks. Prioritized network coding reduces this delay problem by introducing a hierarchy of prioritization layers. What remains is the problem of choosing a layer to approach two often-contradicting goals: reduce delay until prioritized layers can be decoded and keep the total number of transmissions low. In this paper, we propose an algorithm for this problem that – based on limited feedback – primarily minimizes per-layer delay but identifies opportunities to reduce the required transmissions when per-layer delay is unaffected. Our evaluation shows that our algorithm improves per-layer delay compared to hierarchical network coding and is close to the theoretical optimum number of total transmissions. Moreover, we demonstrate how the proposed algorithm can benefit smart-factory applications that operationalize delay-sensitive information from the production process.

Atmospheric Transmission of Ultraviolet and Total Solar Radiation by Clouds, Aerosols, and Ozone in Seoul, Korea: a Comparison of Semi-Empirical Model Predictions with Observations

This study examines the semi-empirical models to evaluate the atmospheric broadband transmission of erythemally weighted ultraviolet (EUV), total ultraviolet (TUV), and global solar radiation (GS) by clouds, aerosols, and ozone in Seoul, Korea (37.57°N, 128.98°E). Climatological values of surface solar irradiance (SSI) for Seoul are briefly summarized, and atmospheric transmission is defined as the ratio of measured SSI to clear-sky irradiance calculated using harmonic analysis. Three multiple linear regression models are developed for the EUV, TUV, and GS spectral bands for all-sky (clear and cloudy conditions) transmission using three independent variables: cloud-cover amount, aerosol optical depth, and total ozone. The modeled total transmissions are 75%, 71%, and 67% for the EUV, TUV, and GS spectral bands, respectively, which are slightly overestimated than the measured values. The modeled annual mean clearness index, KT, is 1%, 45%, and 48% for the three spectral bands, respectively. Four semi-empirical models were developed to calculate transmission and were evaluated. Among the various empirical models, estimates from the exponential models were found to be the closest to measured values, having the lowest mean bias error (−0.3% to −2.4%) and highest explained variance (R2 = 0.17 to 0.50; p = 0.000), as was expected from their theoretical bases. The annual average transmissions of cloud, aerosol, ozone, and all three combined show decrease from the EUV to the TUV and GS bands.