Transmission Probability Research Articles

Bound states in the continuum in whispering gallery resonators with pointlike impurities.

Whispering gallery resonators offer a versatile platform for manipulating the photonic transmission. Here, we study such a system, including periodically distributed pointlike impurities along the resonator with ring geometry. Based on an exact expression for the transmission probability we obtain here, we demonstrate that the bound states in the continuum (BICs) form from the whispering gallery modes at the high-symmetry momenta in the ring's Brillouin zone. Furthermore, the presence of the inversion symmetry allows for a selective decoupling of resonant states, favoring the BIC generation and, therefore, allowing extra tunability in the optical transmission of the system.

Risk of introducing Zika virus in the Canadian cord blood supply: A risk analysis.

In Canada, as many as 24% of mothers are deferred from cord blood (CB) donation due to risk factors for Zika virus (ZIKV). However, the ZIKV epidemic has waned considerably since 2016, and there has not been any report of ZIKV transmission by CB transplantation, which questions this policy. Thus, we performed an analysis of the risk of introducing ZIKV in the CB supply maintained by Héma-Québec (HQ) and Canadian Blood Services (CBS). This simulation considered the following parameters: the risk of travel exposure in a high-risk ZIKV country, the duration of travel, the daily risk of acquiring ZIKV in a high-risk country, the probability of materno-fetal ZIKV transmission, the probability of asymptomatic fetal viremia, and the probability of sexual transmission. A hundred million Monte Carlo simulations were run. In the most-likely scenario (probability of traveling to a high-risk ZIKV country while pregnant = 0.178), the risk was estimated at 0.9 ZIKV-positive donations per million donations (95% confidence interval [CI] = 0.4-1.6)-or one every 868 years at HQ and one every 453 years at CBS. In the pessimistic model (probability of traveling to a high-risk ZIKV country while pregnant = 0.240), the risk was estimated at 1.2 ZIKV-positive donations per million donations (95% CI = 0.6-2.1)-or one every 644 years at HQ and one every 340 years at CBS. We conclude that the risk of introducing ZIKV in the Canadian CB supply is too small to justify maintaining the current policy.

Performance Analysis of Wireless Sensor Networks Using Damped Oscillation Functions for the Packet Transmission Probability

Wireless sensor networks are composed of many nodes distributed in a region of interest to monitor different environments and physical variables. In many cases, access to nodes is not easy or feasible. As such, the system lifetime is a primary design parameter to consider in the design of these networks. In this regard, for some applications, it is preferable to extend the system lifetime by actively reducing the number of packet transmissions and, thus, the number of reports. The system administrator can be aware of such reporting reduction to distinguish this final phase from a malfunction of the system or even an attack. Given this, we explore different mathematical functions that drastically reduce the number of packet transmissions when the residual energy in the system is low but still allow for an adequate number of transmissions. Indeed, in previous works, where the negative exponential distribution is used, the system reaches the point of zero transmissions extremely fast. Hence, we propose different dampening functions with different decreasing rates that present oscillations to allow for packet transmissions even at the end of the system lifetime. We compare the system performance under these mathematical functions, which, to the best of our knowledge, have never been used before, to find the most adequate transmission scheme for packet transmissions and system lifetime. We develop an analytical model based on a discrete-time Markov chain to show that a moderately decreasing function provides the best results. We also develop a discrete event simulator to validate the analytical results.

Quantization rule for transition suppression in dynamic two-level system

The transmission probability in a generic two-quasi-state system is addressed. An approximate expression for the transmission probability between the two quasi-states is derived for the case where the energy gap between the two states varies. Unlike the Landau-Zener formula, the temporal change can have a generic form and can vanish several times. In particular, when the energy gap vanishes twice, an analytical quantization rule for the suppression of transmission between two quasi-states is derived.

A canine onchocercosis report from the portuguese west region in 2024: implications for Public Health

Abstract Issue/problem Onchocerca lupi parasitosis, known as onchocercosis, affects dogs, sporadically cats and humans, posing a public health concern due to possible vectors in the environment. This neglected tropical disease(NTD), has no known human cases outside endemic areas. However, recent reports in non-endemic areas raise concerns about future implications. Climate change has increased the potential risk of disease vectors establishing themselves in previously unaffected areas. Description of the problem A case of canine onchocercosis in the West Region of Portugal, made the pet owner look for medical counselling. Primary health care providers contacted the Public Health Unit(PHU) for guidance and actions. There had been no previous reports in this region. In this case report, we explore the potential public health implications, through a one-health approach. Results History of the disease was collected, and travel history of the dog revealed that he had lived in the Algarve during 11 years with only a one-and-a-half-month travel to Italy in this period. Literature review revealed reports of previous cases of oncochercosis in the Iberian Peninsula. Collaboration between the PHU, research institutes, and veterinary authorities led to the assumption of probable transmission in the Algarve. Lessons Increased vector surveillance is needed, especially in areas associated with animal onchocercosis. Proactive measures reduce transmission risks, protecting both humans and animals. Tracking animal cases is vital for understanding regional environmental factors. PHU’s must conduct thorough risk evaluations and maintain assertive risk communication strategies to address public and pet owner concerns effectively. Adopting a One Health approach improves the understanding of the disease dynamics and enables targeted interventions. Key messages • NTD’s transmitted by vectors pose a potential future challenge. This report underscores the need for a One Health approach, with collaborative multidisciplinary efforts to address these challenges. • Furthermore, systematic interaction and reporting between human, animal, and environmental health authorities are crucial to ensure comprehensive surveillance and mitigation strategies.

Model-based estimates of age-structured SARS-CoV-2 epidemiology in households

BackgroundUnderstanding how infectious disease transmission varies from person to person, including associations with age and contact behavior, can help design effective control strategies. Within households, transmission may be highly variable because of differing transmission risks by age, household size, and individual contagiousness. Our aim was to disentangle those factors by fitting mathematical models to SARS-CoV-2 household survey and serologic data.MethodsWe surveyed members of 3,381 Utah households from January-April 2021 and performed SARS-CoV-2 antibody testing on all available members. We paired these data with a probabilistic model of household importation and transmission composed of a novel combination of transmission variability and age- and size-structured heterogeneity. We calculated maximum likelihood estimates of mean and variability of household transmission probability between household members in different age groups and different household sizes, simultaneously with importation probability and probabilities of false negative and false positive test results.Results12.8% of individual participants, residing in 17.4% of the participating households, showed serologic evidence of prior infection or reported a prior positive test on the survey. Serologically positive individuals in younger age groups were less likely than older adults to have tested positive during their infection according to our survey results. Our model results suggested that adolescents and young adults (ages 13–24) acquired SARS-CoV-2 infection outside the household at a rate substantially higher than younger children and older adults. Our estimate of the household secondary attack rate (HSAR) among adults aged 45 and older exceeded HSARs to and/or from younger age groups at a given household size. We found lower HSAR in households with more members, independent of age differences. The age-specific HSAR patterns we found could not be explained by age-dependent biological susceptibility and transmissibility alone, suggesting that age groups contacted each other at different rates within households.ConclusionsWe disentangled several factors contributing to age-specific infection risk, including non-household exposure, within-household exposure to specific age groups, and household size. Within-household contact rate differences played a significant role in driving household transmission epidemiology. These findings provide nuanced insights for understanding community outbreak patterns and mechanisms of differential infection risk.

Enhanced thermoelectric performance of silicon powder arrays by remotely doping

We report improved thermoelectric (TE) properties of mesostructured silicon powder arrays simply prepared by die-pressing without sintering. In contrast to bromoethane's modest effect, the symmetric dibromoethane molecule coupling could significantly increase the conductivity of Si powder array TE device, from 12.7 S cm−1 of a silicon powder array to 62.3 S cm−1, which is possibly caused by the high electronic transmission probability of symmetric organic molecule–Si crystal coupling, and additionally enhanced by Si bandgap narrowing and defect states of an organic–inorganic interface identified by UV–vis absorption spectra and photoluminescence spectroscopy. Boosted by the very low thermal conductivity (0.58 W m−1 K−1), the dimensionless figure of merit, the ZT value of an Si powder array remotely doped by dibromoethane, ∼0.173, was obtained at 385 K, which is about 17 times higher than that of the bulk Si. An Si–organic hybrid TE device shows potentials to approach the threshold of practical applications with moderate ZT performance and low cost.

Criterion for vanishing valley asymmetric transmission in dual-gated bilayer graphene

Abstract Realizing valley asymmetric transmission(VAT) for incoming valley unpolarized Dirac carriers across an electrostatically modulated confinement potential(ECP) step, which is located at the interface of the unipolar ($n-n'$) junction in dual-gated Bernal-bilayer graphene(BBG), has caught growing attention because it provides a platform to study the valley polarizer. Such a junction, however, seems to preclude from supporting vanishing VAT. Based on the effective two-band Hamiltonian of BBG with wave matching approach, we demonstrate theoretically that VAT through the $n$/$ n'$ interface vanishes in the following conditions: (i) the disappearing electrostatically modulated interlayer potential difference(EPD), or (ii) the invariance condition of the sum or difference of ECPs and EPDs, which physically corresponds to the zero band offset of the conduction or valence band in the band alignment of $n-n'$ junction. Guided by this, it is worth mentioning that the we can derive simple, analytical valley-independent expressions for the reflection and transmission probabilities. We further find the appearance of the nearly vanishing VAT for the four-band model in bilayer graphene with 'Mexican hat'-like band. As a byproduct, we apply these findings to suggest the best design for the valley-dependent selection of momenta based on dual-gated BBG connected to two pristine BBG electrodes in which ECPs of the two outer regions are distinguishable and show that the sign of valley polarization can be switched via varying EPD. We expect our results can provide guidance for future device applications relying on ballistic and valley-selective transport.

A scattering matrix approach to the effective mass dependence of tunneling current through heterojunctions

A scattering matrix technique is used to calculate the longitudinal and transverse energy dependence of the transmission probability through various heterostructures using both the BenDaniel–Duke (BD) and the lesser known Zhu–Kroemer (ZK) boundary conditions to take into account the spatial dependence of the effective mass. We first illustrate the large difference in the transmission probabilities calculated using both boundary conditions for the simple problems of tunneling through a potential step, a single rectangular barrier, and a resonant tunneling device. Then, we present numerical calculations of the external electric field dependence of the field emission (FE) current from a n-doped GaAs semiconductor/vacuum interface using both boundary conditions, showing that the BD boundary conditions underestimate the FE current for large values of the applied external electrostatic field. A comparison of calculated FE characteristics with FE data may be a way to determine the appropriate boundary conditions to solve tunneling problems through heterostructures with spatially varying effective mass.

Drug-resistance characteristics, genetic diversity, and transmission dynamics of multidrug-resistant or rifampicin-resistant Mycobacterium tuberculosis from 2019 to 2021 in Sichuan, China

BackgroundMultidrug- or rifampicin-resistant tuberculosis (TB; MDR/RR-TB) is a significant public health threat. However, the mechanisms involved in its transmission in Sichuan, China are unclear. To provide a scientific basis for MDR/RR-TB control and prevention, we investigated the drug-resistance characteristics, genetic diversity, and transmission dynamics and analyzed the demographic and clinical characteristics of patients to identify risk factors for the acquisition of MDR/RR-TB in Sichuan, Western China.MethodsWhole-genome sequencing was performed using a sample comprised of all MDR/RR-TB strains isolated from patients with pulmonary TB (≥ 15 years) at the 22 surveillance sites in Sichuan province between January 2019 and December 2021, to analyze genotypic drug resistance and genetic diversity. Moreover, we performed statistical analyses of the epidemiological characteristics and risk factors associated with the transmission dynamics of MDR/RR-TB.ResultsThe final analysis included 278 MDR/RR TB strains. Lineage 2.2, the major sub-lineage, accounted for 82.01% (228/278) of isolates, followed by lineage 4.5 (9.72%, 27/278), lineage 4.4 (6.83%, 19/278), and lineage 4.2 (1.44%, 4/278). The drug resistance rates, ranging from high to low, were as follows: isoniazid (229 [82.37%]), streptomycin (177 [63.67%]), ethambutol (144 [51.80%]), pyrazinamide (PZA, 119 [42.81%]), fluoroquinolones (FQs, 93 [33.45%]). Further, the clofazimine, bedaquiline, and delamanid resistance rates were 2.88, 2.88, and 1.04%, respectively. The gene composition cluster rate was 32.37% (90/278). In addition, 83.81% (233/278) of MDR/RR-TB cases were determined to be likely caused by transmission. Finally, patients infected with lineage two strains and strains with the KatG S315T amino acid substitution presented a higher risk of MDR/RR-TB transmission.ConclusionTransmission plays a significant role in the MDR/RR-TB burden in Sichuan province, and lineage 2 strains and strains harboring KatG S315T have a high probability of transmission. Further, high levels of FQ and PZA drug resistance suggest an urgent need for drug susceptibility testing prior to designing therapeutic regimens. New anti-TB drugs need to be used standardly and TB strains should be regularly monitored for resistance to these drugs.

Three-State Hidden Markov Model for Spectrum Prediction in Cognitive Radio Networks

The exponential growth and proliferation of wireless devices for different wireless applications have led to the emergence of cognitive radio network (CRN) for optimal utilization of scarce spectrum resources. However, these resources have grossly been under-utilized due to the inaccurate spectrum predictions. Existing spectrum occupancy and prediction techniques which rely on 2-state hidden Markov model (HMM) results in false alarm or missed detection caused by noisy or incomplete observable effects. In this paper, a 3-state HMM spectrum occupancy and prediction technique in CRNs is proposed. The transmission, emission and initial state probabilities of the proposed 3-state HMM parameters were derived based on the three canonical problems associated with HMM. The evaluation, decoding and learning problems were solved using Forward algorithm, Viterbi algorithm and the Baum-Welch algorithm, respectively. The performance of the proposed 3-state HMM spectrum prediction technique was evaluated using prediction accuracy, probability of detection and spectrum utilization efficiency. The simulation results obtained revealed that the 3-state HMM outperformed the 2-state HMM spectrum prediction technique by 24.1% in prediction accuracy.

Resonant tunneling properties of laser dressed hyperbolic Pöschl-Teller double barrier potential

We examine the resonant tunneling properties of the laser-dressed hyperbolic Pöschl-Teller double quantum barrier structure. We use the non-equilibrium Green's function method to investigate structure parameters and electric field bias on the transmission properties of the system. The transmission probabilities and resonance energy levels are significantly influenced by the well widths and barrier heights. The barrier height increases, resonance energy levels shift toward higher values, and the resonance peak width narrows, leading to sharper and more selective tunneling behavior. Our results show that increasing the electric field bias leads to a decrease in the transmission probability at the first resonance peak, but this effect is not as strong for the subsequent peaks. Moreover, we find that changes in the laser field's parameter and structure parameters allow for fine control over the electronic spectra, allowing for modifications like red or blue shifts based on particular needs. The significance of comprehending the interaction among structural factors, external fields, and transmission qualities in quantum barrier structures is highlighted by our research, providing valuable information for the development and enhancement of electronic and optoelectronic systems with customized functionality. Our findings show the laser field has a considerable impact on resonant tunneling properties, opening the door to new device applications.

Severe Acute Respiratory Syndrome Coronavirus 2 Household Transmission During the Omicron Era in Massachusetts: A Prospective, Case-Ascertained Study Using Genomic Epidemiology.

Households are a major setting for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, but there remains a lack of knowledge regarding the dynamics of viral transmission, particularly in the setting of preexisting SARS-CoV-2 immunity and evolving variants. We conducted a prospective, case-ascertained household transmission study in the greater Boston area in March-July 2022. Anterior nasal swabs, along with clinical and demographic data, were collected for 14 days. Nasal swabs were tested for SARS-CoV-2 by polymerase chain reaction (PCR). Whole genome sequencing was performed on high-titer samples. We enrolled 33 households in a primary analysis set, with a median participant age of 25 years (range, 2-66 years), 98% of whom had received at least 2 doses of a coronavirus disease 2019 (COVID-19) vaccine. Fifty-eight percent of households had a secondary case during follow-up and the secondary attack rate (SAR) for contacts was 39%. We further examined a strict analysis set of 21 households that had only 1 PCR-positive case at baseline, finding an SAR of 22.5%. Genomic epidemiology further determined that there were multiple sources of infection for household contacts, including the index case and outside introductions. When limiting estimates to only highly probable transmissions given epidemiologic and genomic data, the SAR was 18.4%. Household contacts of a person newly diagnosed with COVID-19 are at high risk for SARS-CoV-2 infection in the following 2 weeks. This is, however, not only due to infection from the household index case, but also because the presence of an infected household member implies increased SARS-CoV-2 community transmission.

Using the basic reproduction ratio to quantify transmission and identify data gaps for epizootic haemorrhagic disease virus.

Epizootic haemorrhagic disease virus (EHDV) is an arbovirus transmitted by Culicoides biting midges that has recently emerged in Europe. Here, the basic reproduction ratio (R 0) was used to quantify the transmission of EHDV and its dependence on temperature for cattle and deer. Using data from the published literature the parameters needed to calculate R 0 were estimated with Bayesian methods to incorporate uncertainty in the calculations. The Sobol method of sensitivity analysis was used to determine the parameters having the greatest influence on R 0 and, hence, to identify important data gaps. Depending on the strain, the maximum R 0 for EHDV varied from 0.7 to 2.5 in cattle and 1.3 to 4.3 in deer. The maximum R 0 occurred at temperatures between 22 and 25°C, while the lowest temperature at which R 0 exceeded one was between 16 and 20°C. The sensitivity analysis identified the threshold temperature for virus replication, the probability of transmission from host to vector and the vector- to- host ratio as the most important parameters influencing R 0. Furthermore, there are only limited data on EHDV in European deer species and on transmission in wildlife and at the livestock/wildlife interface. These data gaps should be the focus of future research.

Reliability and Security Performances Analysis of Rate Splitting Based VLC System With HARQ

This work first attempts to investigate the reliability and physical layer security (PLS) performances of a rate splitting (RS) based visible light communication (VLC) system with one trusted user and one untrusted user. Specifically, the hybrid automatic repeat request (HARQ) protocol is adopted at the trusted user and the movement of users is assumed to be subject to the random way point (RWP) model with four decoding strategies considered at receiver side. The exact closed-form expressions of outage probability (OP) for both users are then obtained, and the analytical expressions of secrecy outage probability (SOP), reliable and secure transmission probability (RSP), and effective secrecy throughput (EST) of trusted user are also mathematically derived. Through simulations, it is found that to guarantee the reliability and PLS performances, the trusted user should first decode the untrusted user’s private stream and the untrusted user should first decode the trusted user’s private stream. Besides, the reliability and PLS performances of RS-VLC system could be enhanced with the appropriate increase in the maximum transmission round of HARQ with the best decoding strategy. Moreover, they could be further enhanced by the proper common stream power allocation coefficient. This work will benefit the research and development of indoor VLC system.

Transmission coefficient and probability of intersubband transitions in [formula omitted] superlattices: Effect of non-parabolicity

Our study investigates optical transition energies in GaAs/AlGaAs quantum multiwell infrared photodetectors. These devices exploit transitions within subbands, necessitating accurate theoretical predictions to optimize their performance. We first determine the energetic positions of conduction minibands and investigate how band non-parabolicity influences the width of these minibands. Furthermore, we analyze the impact of non-parabolicity on transition probabilities within the quantum wells. Additionally, our study explores the transmission coefficient, which exhibits a decrease with increasing barrier height. This phenomenon affects electron transmission efficiency and is associated with quantum reflection processes. Higher barrier heights require greater energy for electrons to traverse, influencing device functionality. Understanding these factors is crucial for advancing the design and performance of GaAs/AlGaAs quantum multiwell photodetectors, offering insights into their operational limits and potential optimizations.

The impact of the environment factors on co-evolution process of information-emotions-epidemic dynamics in activity-driven multiplex networks

Abstract During public health emergencies, the diffusion of negative information can exacerbate the transmission of adverse emotions, such as fear and anxiety. These emotions can adversely affect immune function and consequently influence epidemic spreading. In this paper, we establish a coupled model incorporating environmental factors to explore the co-evolution dynamic process of information-emotions-epidemic dynamics in activity-driven multiplex networks. In this model, environmental factors refer to external conditions or pressures that affect the spread of information, emotions, and epidemics. These factors include media coverage, public opinion, and the prevalence of disease in the neighborhood. These layers are dynamically cross-coupled, where the environmental factors in the information layer are influenced by the emotional layer, and the higher levels of anxious states among neighboring individuals, the greater the likelihood of information diffusion. While environmental factors in the emotional layer are influenced by both the information layer and the epidemic layer, it comes from the factors of global information and the proportion of local infections among surrounding neighbors. Subsequently, we utilize the Microscopic Markov Chain Approach (MMCA) to describe the dynamical processes, thereby obtaining the epidemic threshold. Finally, we draw conclusions through numerical modeling and analysis. The conclusions suggest that when negative information heightens the probability of anxious states transmission across the population. The transmission of anxious states increases the final size of the disease and decreases the outbreak threshold. Reducing the impact of environmental factors at both the informational and emotional levels is beneficial in controlling the scale of the spread of the epidemic. Our findings can provide a reference for improving the public’s health awareness and behavioral decision-making, mitigating the adverse impacts of anxious states, and ultimately controlling the spreading of epidemics.

Spin/valley dependent dwell time in an 8-Pmmn borophene junction

Spin/valley dependent dwell time in 8-Pmmn borophene junction under Rashba spin–orbit interaction (RSOI) is studied. The dwell time as well as transmission probability for incident electrons with spin-up show a different behavior than the incident electrons with spin-down, and these quantities can be controlled effectively by the junction direction, incident angle, the RSOI strength and the barrier width. Also, the dwell time is dependent on the degree of freedom of the valley and shows oscillating behavior with the increase of the barrier width. The spin polarization and spin filtering in 8-Pmmn borophene junction under RSOI can be obtained in the time domain.

Proposition of Optimization of the Meetinthemiddle Protocol for Quantum Repeaters

Quantum computing relies on concepts derived from classical information theory and quantum physics. In order for quantum communications to be a reality, it is essential to have the most advanced infrastructures in place. In this paper, we explore the significance of quantum communication and the utilization of quantum repeaters, which rely on the phenomenon of quantum entanglement. We present the MeetInTheMiddle protocol for quantum repeaters and its total transmission probability, and then propose an improvement of this protocol based on the comparison of the total transmission probability.

Sufficiency of near-surface water ice as a driver of dust activity on comets

Context. Nearly all contemporary theoretical research on cometary dust activity relies on models depicting heat transfer and sublimation products within the near-surface porous layer. Gas flow exerts a pressure drag to the crust agglomerates, counteracting weak gravity and the tensile strength of that layer. Our interpretation of data from the Rosetta mission, and our broader comprehension of cometary activity, hinges significantly on the study of this process. Aims. We investigate the role played by the structure of the near-surface porous layer and its associated resistance to gas flow, tensile strength, pressure distribution, and other characteristics in the scenario of the potential release of dust agglomerates and the resulting dust activity. Methods. We employ a thermophysical model that factors in the microstructure of this layer and radiative heat conductivity. We consider gas flow in both the Knudsen and transition regimes. To accomplish this, we use methods such as test-particles Monte Carlo, direct-simulation Monte Carlo, and transmission probability. Our study encompasses a broad spectrum of dust-particle sizes. Results. We evaluated the permeability of a dust layer composed of porous aggregates in the submillimetre and millimetre ranges. We carried out comparisons among various models that describe gas diffusion in a porous dust layer. For both the transition and Knudsen regimes, we obtained pressure profiles within a non-isothermal layer. We discuss how the gaps in our understanding of the structure and composition could impact tensile strength estimates. We demonstrate that for particles in the millimetre range, the lifting force of the sublimation products of water ice is adequate to remove the layer. This scenario remains feasible even for particles on the scale of hundreds of microns. This finding is crucial as the sublimation of water ice continues to be the most probable mechanism for dust removal. Conclusions. This study partially overturns the previously held, pessimistic view regarding the possibility of dust removal via water sublimation. We demonstrate that a more precise consideration of various physical processes allows elevation of the matter of dust activity to a practical plane, necessitating a fresh quantitative analysis.