Additional Delay Research Articles

Female little brown bats require both building and natural roosts in a mountainous environment with short summers

AbstractThe little brown bat (Myotis lucifugus) is an endangered species that occurs throughout most of North America. The recovery strategy for little brown bats in Canada identifies a need to understand habitat use and protect important bat habitat across the species' Canadian range; however, bat roosting habitat requirements have not been well studied in mountainous environments within the northern part of the species' range. Our objective was to understand the use of building and natural roosts by female little brown bats in the Canadian Rocky Mountains. Over two summers, we captured little brown bats in Banff, Yoho, and Kootenay National Parks, in Alberta and British Columbia, Canada, and tracked 49 females to their day roosts. Buildings were the only roost type used by radio‐tagged bats of all reproductive stages, the dominant roost type used throughout the reproductive period, and the only structures in which we located maternity colonies. Buildings also appeared to shape the distribution of foraging female and reproductive female bats such that few were captured at long distances from towns and building clusters. Compared with bats in more southern and in non‐mountainous areas, bats in our study area had delayed juvenile weaning and volancy, began hibernation early, and had low reproductive rates. We suggest that buildings are a key habitat for female little brown bats to persist at their current levels in our study area, by providing thermal conditions that promote overwinter survival; additional reproductive delays caused by torpor use in cool natural roosts would likely reduce juvenile and adult female overwinter survival below the levels required to sustain populations. Nevertheless, building colonies were unusually small, and bats had relatively low fidelity to particular building roosts, suggesting that building roosts may not consistently meet bats' needs. Some nonreproductive and pregnant females also frequently used natural roosts, particularly after colder nights; these roosts may be important in facilitating torpor and energy conservation for these bats. Because bats are long‐lived with low reproductive output and low juvenile survival, addressing the needs of both reproductive and nonreproductive individuals is important for population persistence.

Abstract A025: Combination of anti-CTLA4 and radiation induce synergistic tumor control in radiorecurrent prostate cancer

Abstract Background: Advanced prostate cancer (PCa) is a leading cause in cancer death and can elicit significant morbidity and mortality. A common treatment modality for advanced PCa is radiation therapy (RT). Currently, salvage of local disease recurrence after RT is a major clinical problem. Emerging evidence indicates the importance of the immune system in governing RT response. In support of this, immune checkpoint inhibitors (ICIs), which enhance immune activation, have demonstrated clinical therapeutic promise in combination with RT in certain advanced cancers. Irradiation (IR) combined with ICIs may prime the immune system to recognize and target recurrent cancer. Purpose: Investigate the therapeutic efficacy of ICIs in combination with RT for radiorecurrent PCa in a syngeneic pre-clinical model. Methods: TRAMP-C2 cells were treated with 10 Gy of radiation over 5 fractions (similar to clinical hypofractionated (HF) schedule) to generate TRAMP-C2 HF cells. Immune-competent mice were transplanted subcutaneously with TRAMP-C2 HF cells. Once tumors reached palpable size, mice were administered either ICIs (αPDL1 or αCTLA4) alone or in combination with RT. Tumor volume was monitored to determine the treatment effect. Correlative studies on excised tumors and secondary lymphoid organs included flow cytometry and NanoString gene expression panel to evaluate immunological mechanisms that contribute to anti-tumor effects[SL1]. Results: TRAMP-C2 HF cells were validated for radiation resistance and exhibited a more aggressive phenotype (reduction in senescence, increase in clonogenicity) similar to clinically recurrent PCa. Radiation resistance of TRAMP-C2 HF tumors was validated in vivo. Administration of αPDL1 and αCTLA4 as monotherapy or in combination did not achieve significant tumor growth delay compared to control. IR alone produced an observable tumor growth delay compared to ICIs alone. The combination of αPDL1 and IR did not yield additional growth delay compared to IR alone. Strikingly, significant tumor growth delay was seen with the combination of IR and αCTLA4 compared to IR alone, while also resulting in complete cure in a third of the mice. NanoString analysis of lymph nodes from mice treated with αCTLA4 and IR vs. IR alone demonstrated differential expression of genes regulating CD molecules, interleukins, and T-cell functions. Furthermore, enrichment of CD45 and CD8a RNA following αCTLA4 and IR was observed. Validation by flow cytometry is currently ongoing. Conclusion: We generated the first syngeneic radiorecurrent PCa model and demonstrated that combining αCTLA4 and IR results in synergistic tumor response. Combined therapy resulted in augmented immune response, most notably enhancement of CD8 T cell activity. Significance: These findings contribute to our understanding of immunological events associated with RT and ICIs in the context of radiorecurrent PCa and support new avenues for salvage therapy in clinical trials. Citation Format: Hanzhi Wang, Xiaoyong Huang, Stepahnie D White, Linsey Gong, Tera N Petchiny, Hans Chung, Emmanouil Fokas, Robert S Kerbel, Stanley K Liu. Combination of anti-CTLA4 and radiation induce synergistic tumor control in radiorecurrent prostate cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A025.

Powder bed defect classification methods: deep learning vs traditional machine learning

PurposeThis paper aims to discuss the development of a defect classification system that can be used to detect and classify powder bed surface defects from captured layer images without the need for specialised computational hardware. The idea is to develop this system by making use of more traditional machine learning (ML) models instead of using computationally intensive deep learning (DL) models.Design/methodology/approachThe approach that is used by this study is to use traditional image processing and classification techniques that can be applied to captured layer images to detect and classify defects without the need for DL algorithms.FindingsThe study proved that a defect classification algorithm could be developed by making use of traditional ML models with a high degree of accuracy and the images could be processed at higher speeds than typically reported in literature when making use of DL models.Originality/valueThis paper addresses a need that has been identified for a high-speed defect classification algorithm that can detect and classify defects without the need for specialised hardware that is typically used when making use of DL technologies. This is because when developing closed-loop feedback systems for these additive manufacturing machines, it is important to detect and classify defects without inducing additional delays to the control system.

Decentralised IOTA-Based Concepts of Digital Trust for Securing Remote Driving in an Urban Environment

The novel contribution of this research is decentralised IOTA-based concepts of digital trust for securing remote driving in an urban environment. The conceptual solutions are studied and described, and respective experimental solutions are developed relying on digital identities, public key cryptography with a decentralised approach using decentralised identifiers (DIDs) and verifiable credentials (VCs), and an IOTA-based distributed ledger. The provided digital trust solutions were validated by executing them according to the remote driving scenario but with a simulated vehicle and simulated remote driving system. The hybrid simulation mainly focused on the validation of functional, causal temporal correctness, feasibility, and capabilities of the provided solutions. The evaluations indicate that the concepts of digital trust fulfil the purpose and contribute towards making remote driving more trustable. A supervisory stakeholder was used as a verifier, requiring a set of example verifiable credentials from the vehicle and the remote driver, and accepting them to the security control channel. The separation of control and data planes from each other was found to be a good solution because the delays caused by required security control can be limited to the initiation of the remote driving session without causing additional delays in the actual real-time remote driving control data flow. The application of the IOTA Tangle as the verifiable data registry was found to be sufficient for security control purposes. During the evaluations, the need for further studies related to scalability, application of wallets, dynamic trust situations, time-sensitive behaviour, and autonomous operations, as well as smart contract(s) between multiple stakeholders, were detected. As the next step of this research, the provided digital trust solutions will be integrated with a vehicle, remote driving system and traffic infrastructure for evaluation of the performance, reliability, scalability, and flexibility in real-world experiments of remote driving of an electric bus in an urban environment.

HDAC Inhibitor CS014 Attenuates Thrombosis Alone and in Combination with Rivaroxaban without Increased Risk of Bleeding

Introduction: Targeting the human platelet for prevention of occlusive thrombotic events remains an active area of research due to the high incidence of myocardial infarction and stroke due to platelet-rich thrombotic clots. While, many patients taking FXa anticoagulant therapy require further inhibition of thrombosis, dual therapy including anticoagulant plus antiplatelet drugs result in an increased risk for bleeding. The current study sought to determine if a histone deacetylase (HDAC) inhibitor, either alone or in combination with the FXa inhibitor rivaroxaban, is able to effectively inhibit platelet and fibrin formation at the site of vascular injury without causing a significant increase in the bleeding risk in mice. Methods and Results: Thrombosis and bleeding models in the mouse were assessed in the presence of the HDAC inhibitors valproic acid (VPA) or the newly developed HDAC inhibitor, CS014. Both CS014 and VPA significantly, dose-dependently inhibit platelet accumulation and fibrin formation at the site of a vascular injury using the laser-induced cremaster thrombosis assay model. Further, to determine if CS014 has the potential to be used in conditions where an anticoagulant is already on board, mice were dosed for 5 days with rivaroxaban alone or in combination with CS014 and were assessed for prevention of laser-induced thrombosis in the cremaster arteriole. Both rivaroxaban and CS014 alone cause significant attenuation of clot formation. To determine if the combination results in an increased risk for bleeding, blood from mice treated with CS014 or rivaroxaban alone, or in combination was assessed for coagulation activity and clot strength using thromboelestography (TEG). Rivaroxaban was found to significantly delay onset of clotting in TEG whereas CS014 did not show any delay in coagulation or clotting with TEG. In combination CS014 was not observed to cause any additional delay in clotting time or decrease in maximal clot strength compared to rivaroxaban alone. Finally, a tail vein bleeding assay was conducted to determine if CS014 alone or in combination with rivaroxaban result in an increased risk for bleeding. Neither CS014 alone, rivaroxaban alone, or the combination of CS014 plus rivaroxaban resulted in increased bleeding time in the resected tail experiment. Conclusions: The data presented here suggests that while CS014 and rivaroxaban are each effective antithrombotic agents, they work well together to minimize clot formation without altering coagulation or clotting compared to rivaroxaban alone. Hence, CS014 has the potential to enrich the toolbox of anticoagulant therapies in patients with a high risk of thrombotic events.

Network Layer Privacy Protection Using Format-Preserving Encryption

Format-Preserving Encryption (FPE) algorithms are symmetric cryptographic algorithms that encrypt an arbitrary-length plaintext into a ciphertext of the same size. Standardisation bodies recognised the first FPE algorithms (FEA-1, FEA-2, FF1 and FF3-1) in the last decade, and they have not been used for network layer privacy protection so far. However, their ability to encrypt arbitrary-length plaintext makes them suitable for encrypting selected packet header fields and replacing their original value with ciphertext of the same size without storing excessive information on the network element. If the encrypted fields carry personally identifiable information, it is possible to protect the privacy of the endpoints in the communication. This paper presents our research on using FPE for network layer privacy protection and describes LISPP, a lightweight, stateless network layer privacy protection system. The system was developed for programmable smart network interface cards (NIC) and thoroughly tested in a real network environment. We have created several implementations ranging from pure P4 to a mix of P4 and C implementations, exploring their performance and the suitability of target-independent P4 language for such processor-intensive applications. Finally, LISPP achieved line rate TCP throughput, up to 4.5 million packets per second, with the penalty of only 30 to 60 microseconds of additional one-way delay, proving that it is adequate for use in production networks. The most efficient implementation was with the FF3-1 algorithm developed in C and carefully adapted to the specific hardware configuration of the NIC.

Leveraging the edge and cloud for V2X-based real-time object detection in autonomous driving

Environmental perception is a key element of autonomous driving because the information received from the perception module influences core driving decisions. An outstanding challenge in real-time perception for autonomous driving lies in finding the best trade-off between detection quality and latency. Major constraints on both computation and power must be taken into account for real-time perception in autonomous vehicles. Larger detection models tend to produce the best results but are also slower at runtime. Since the most accurate detectors may not run in real-time locally, we investigate the possibility of offloading computation to edge and cloud platforms, which are less resource-constrained. We create a synthetic dataset to train object detection models and evaluate different offloading strategies. We measure inference and processing times for object detection on real hardware, and we rely on a network simulation framework to estimate data transmission latency. Our study compares different trade-offs between prediction quality and end-to-end delay. Following the existing literature, we aim to perform object detection at a rate of 20Hz. Since sending raw frames over the network implies additional transmission delays, we also explore the use of JPEG and H.265 compression at varying qualities and measure their impact on prediction. We show that models with adequate compression can be run in real-time on the edge/cloud while outperforming local detection performance.

Distributed soft video transmission based on hybrid digital and analog scheme

This study presents a novel distributed soft video delivery scheme using hybrid digital and analog framework, which realizes a relatively lightweight encoder as well as good robustness. Specifically, after applying scalar quantization to the interframes, the scaled analog information (quantization error) and the scaled digital information (quantized source) are superimposed and then transmitted. In this way, the proposed scheme directly delivers pseudo-analog symbols over the orthogonal frequency division multiplexing (OFDM) channels and involves no complicated digital codec. Moreover, we utilize cross-frame correlation to implement a distributed paradigm which further reduces the encoder complexity since the complex motion estimation and compensation algorithms are transferred to the decoder. Accordingly, the power distortion optimization scheme, which resolve the allocation of power and the parameters optimization to achieve minimum transmission distortion, is proposed. To solve it, first, we formulate the power distortion expressions regarding quantization parameters and power allocation coefficients. Subsequently, we divide the problem into two sub-problems based on the fast coordinate descent method and further propose a greedy iterative algorithm to optimize them. We also develop a data-driven optimization algorithm based on deep learning that reduces the additional delay brought by the iterative optimization method. At the receiver, we estimate the quantization output and quantization error by the modified linear least squares estimation with the virtual noise variance. Based on the simulation results, the proposed framework has a better performance in terms of peak signal-to-noise ratio and structural similarity than the relevant cutting-edge schemes while maintaining good robustness.

Delays between Uveal Melanoma Diagnosis and Treatment Increase the Risk of Metastatic Death

To investigate if the interval between diagnosis and treatment of posterior uveal melanoma (UM) is associated with metastatic death. Retrospective, single-center cohort study. A total of 1145 patients consecutively diagnosed with posterior UM at St. Erik Eye Hospital, Stockholm, Sweden, from 2012 to 2022, with recorded dates of diagnosis and primary treatment. This cohort represents 81% of all diagnosed patients in Sweden during this period. Data on the interval between diagnosis and treatment were collected for all patients. Its prognostic importance was examined with univariate and multivariate competing risks regressions, and cumulative incidence analyses. Incidence of metastatic death (UM mortality) for patients with prompt (< 1 month from diagnosis) versus delayed treatment (≥ 1 month) and subdistribution hazard ratios (exp(βj)) for every additional 10-day delay in treatment. The mean interval between diagnosis and treatment was 34 days (SD, 56, range, 0-932). Patients treated promptly had larger tumors at diagnosis, but there were no differences in patient age, tumor distance to the optic disc, rates of ciliary body involvement (CBI) or extraocular extension (EXE), or symptom duration before diagnosis. Those who were treated more than 1 month after diagnosis had greater UM mortality in American Joint Committee on Cancer (AJCC) stage II and III. In stage I, UM mortality for delayed treatment was lower for the first 10 years, followed by a marked spike in the 11th year. In multivariate competing risks regressions of all 1145 patients with tumor diameter, thickness, CBI, and EXE as covariates, the risk for UM mortality increased with 1% for every additional 10-day delay in treatment (exp(βj) 1.01). Among 355 patients treated with enucleation, this delay was associated with UM mortality, independent of AJCC stage, cytomorphology, and level of immunohistochemical BAP-1 expression. Increasing time between diagnosis and treatment of UM is associated with a higher risk of metastatic death. These results challenge a central concept in the understanding of metastatic progression and may indicate the existence of late metastatic seeding. They also underscore the importance of prompt treatment. Validation in independent cohorts is recommended. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The R'' wave in V1 and the terminal QRS vector in aVF combine to a novel 12-lead ECG algorithm to identify slow conducting anatomical isthmus 3 in patients with tetralogy of Fallot

Abstract Background Patients with repaired tetralogy of Fallot (rTOF) have an increased risk for ventricular tachycardia (VT), with slow conducting anatomical isthmus (SCAI) 3 as the dominant VT substrate. Right bundle branch block (RBBB) is common in these patients. SCAI 3 can lead to additional activation delay affecting the terminal RV activation.(1) We hypothesize that these alterations can be detected by sinus rhythm (SR) 12-lead ECG. Purpose To develop a novel algorithm to non-invasively identify SCAI 3 with the SR 12-lead ECG in rTOF patients with RBBB. Methods Consecutive rTOF patients aged ≥16 years old with RBBB who underwent electroanatomical mapping (EAM) at our institution between 2017-2022, and 2010-2016, comprised the derivation, and validation cohort, respectively. 12-lead ECGs in SR were analyzed for presence of R’’ wave in V1 (any positive deflection after R’ in V1) and for duration of a negative terminal QRS portion (NTP) in aVF (ms between QRS complex traversing the isoelectric line from positive to negative vector until QRS offset) (Figure, A). Results Forty-six rTOF patients (aged 40±15 years, 70% male) comprised the derivation cohort. Patients were repaired at a median age of 3.3 [IQR 1.2-6.6] years via a ventricular incision in 21 (55%). Mean QRS duration was 165±23ms and 12 (26%) had a QRS duration of ≥180ms. SCAI 3 was detected in 31 (67%) patients and 15 (33%) had a normal conducting AI 3. Monomorphic sustained VT was inducible in 16 (35%). Among patients with SCAI 3, 17 (55%), and 16 (52%), had an R’’ in V1, and NTP ≥80ms in aVF, respectively, compared to only 1 (7%), and 1 (7%) patients with normal conducting AIs. Of the 24 patients with an R’’ in V1 and/or NTP ≥80ms in aVF, 22 (92%) had a SCAI 3. In univariable analysis an R’’ in V1 had an odds ratio (OR) of 17.0 (p=0.010), a NTP ≥80ms in aVF had an OR of 14.9 (p=0.014), and QRS duration had an OR of 1.04 (per ms, p=0.030) in identifying SCAI 3. After correction for QRS duration, R’’ in V1 and NTP ≥80ms in aVF both remained independently predictive of SCAI 3 (OR 15.4, p=0.017, and OR 10.0, p=0.042, respectively). Combining R’’ in V1 and NTP ≥80ms in aVF into a diagnostic algorithm (Figure, B) yielded a sensitivity of 71% and specificity of 87% in detecting SCAI 3. In the validation cohort (n=34, age 44±14 years, 19 (56%) with SCAI 3 and 15 (44%) with normal conducting AI 3) the diagnostic algorithm had a sensitivity of 84% and specificity of 80% for a SCAI. Conclusion A diagnostic algorithm including R’’ in V1 and NTP ≥80ms in aVF had excellent sensitivity and specificity in detecting SCAI 3 in rTOF patients with RBBB in SR. These ECGs characteristics likely represent a delayed terminal RV activation directed towards the lateral RVOT caused by slow infundibular conduction. Whether this algorithm can contribute to non-invasive risk stratification for VT in a general rTOF population requires additional studies.Diagnostic algorithm to identify SCAI 3

A Resource Allocation Scheme for Packet Delay Minimization in Multi-Tier Cellular-Based IoT Networks

With advances in Internet of Things (IoT) technologies, billions of devices are becoming connected, which can result in the unprecedented sensing and control of the physical environments. IoT devices have diverse quality of service (QoS) requirements, including data rate, latency, reliability, and energy consumption. Meeting the diverse QoS requirements presents great challenges to existing fifth-generation (5G) cellular networks, especially in unprecedented scenarios in 5G networks, such as connected vehicle networks, where strict data packet latency may be required. The IoT devices with these scenarios have higher requirements on the packet latency in networking, which is essential to the utilization of 5G networks. In this paper, we propose a multi-tier cellular-based IoT network to address this challenge, with a particular focus on meeting application latency requirements. In the multi-tier network, access points (APs) can relay and forward packets from IoT devices or other APs, which can support higher data rates with multi-hops between IoT devices and cellular base stations. However, as multiple-hop relaying may cause additional delay, which is crucial to delay-sensitive applications, we develop new schemes to mitigate the adverse impact. Firstly, we design a traffic-prioritization scheduling scheme to classify packets with different priorities in each AP based on the age of information (AoI). Then, we design different channel-access protocols for the transmission of packets according to their priorities to ensure the QoS in networking and the effective utilization of the limited network resources. A queuing-theory-based theoretical model is proposed to analyze the packet delay for each type of packet at each tier of the multi-tier IoT networks. An optimal algorithm for the distribution of spectrum and power resources is developed to reduce the overall packet delay in a multi-tier way. The numerical results achieved in a two-tier cellular-based IoT network show that the target packet delay for delay-sensitive applications can be achieved without a large cost in terms of traffic fairness.

Observer-based fuzzy integral sliding mode control for bilateral teleoperation systems with time-varying delays

This paper aims to examine the stability and tracking performance of a bilateral teleoperation system. The Takagi–Sugeno fuzzy method is utilized, through which the nonlinear master–slave dynamics is converted as a fuzzy-based system. The state observers are designed for the linearized fuzzy teleoperation systems, and the corresponding estimation errors are formulated. Importantly, a novel observer-based fuzzy integral sliding mode control is developed by deliberately introducing the delay term into the sliding surfaces. As such, advanced delay-product type of Lyapunov–Krasovskii functionals are constructed for the augmented state vectors, in order to acquire the additional delay information. In addition, the Wirtinger-based integral inequality along with an extended reciprocally convex matrix inequality is applied to the Lyapunov derivatives to establish the delay-dependent stability conditions. Numerical results are provided to demonstrate efficacy of the developed control mechanism.

AC zero crossing compensation for thermal stress linear birefringence in optical voltage transducer

The optical voltage transducer (OVT) based on the Pockels effect has a perennial issue of the thermal stress linear birefringence (TSLB) in the electro-optic crystal being overlapped with the electro-optic phase delay, which is difficult to be eliminated and seriously affects the measurement accuracy and reliability. In this paper an AC zero crossing compensation method for TSLB is proposed. It is based on that when the steady-state AC voltage crosses zero points the electric field is zero, and the electro-optic crystal does not have any electro-optic effect, so the electro-optic phase delay is zero. In this case, the output of the OVT is an additional phase delay caused by the TSLB, which can be separated and compensated by the linear demodulation OVT and the AC zero crossing detection circuit. The experimental results show that in the temperature range of −40 °C to 70 °C, the measurement accuracy of the OVT after TSLB compensation is improved from 0.5 class to 0.2 class. This method is helpful for the practicality of the OVT.

Convection compensation in 3D iDOSY-HMBC 1H–13C-correlation experiments

3D iDOSY-HMBC (3D incorporated Diffusion Ordered SpectroscopY-Heteronuclear Multiple Bond Correlation) pulse sequences were modified to incorporate convection compensation element. No additional delays were required, and convection compensation was directly constructed within the existing delay periods in 3D iDOSY-HMBC pulse sequence. Convection compensation was achieved by pulsed field gradient double echo, thus avoiding the intensity loss normally related to stimulated echo methods. The incorporated convection compensation element improves the usability of 3D iDOSY-HMBC. In case of elevated temperatures, thermal convection leads to loss of resolution in DOSY-dimension or even to severe decrease of signal intensity, thus making convection uncompensated 3D iDOSY-HMBC infeasible. Aforementioned problems can be circumvented via utilization of the presented convection compensated 3D iDOSY-HMBC-versions.

Harmonic Disturbance Compensation of a System With Long Dead-Time, Design and Experimental Validation

An internal model control scheme is proposed to compensate both a long dead-time of a system and a harmonic disturbance. The controller is based on an inversion of the first-order model used to approximate the system dynamics together with an input delay. Two other components of the controller consist of a filter and an additional delay by which the harmonic modes are targeted via adjusting the control loop gain and phase shift. The design of the filter-delay pair is fully analytical and the implementation of the scheme is straightforward. The main attention is paid to the complete compensation of a single-harmonic disturbance. Besides, an extension of the scheme is proposed to target a double harmonic disturbance. Increased attention is paid to the robustness aspects of the schemes. Outstanding performance in terms of harmonic disturbance compensation of the proposed schemes is demonstrated on a series of laboratory experiments.

Optimizing aircrew recovery considering long connections: A column generation based approach

Severe weather and air traffic flow control can often cause flight delays and disrupt the crew schedules, resulting in a too-short or a too-long connection between flights. Short connections need to be adjusted to ensure the airline’s smooth operations, while the long connection whose duration is only a bit lower than the threshold enabling the crew to leave the flying zone for a rest at airport terminals can be quite inefficient, as the crew’s ground standby is viewed as working all the time without executing any flight which adds to the shortage of crew resources. Thus, we propose a method of delaying flights to the point enabling crews to leave for a rest, which helps save the available working hours. The difficulty lies in the trade-off between the additional swap or delay cost in creating long connections and the possible global cost decrease due to savings in available working hours brought by long connections, which calls for optimization. In this paper, we introduce the crew recovery problem for one day of operation taking long connections into account. The problem is mathematically formulated as an arc-based integer programming model and a set partitioning model in order to determine the optimal flight recovery schedule and the crew reassignment. A column generation based solution approach is developed and the sub-problems consisting of the resource-constrained shortest path problem are solved by a labeling algorithm. Computational experiments based on real-world data from a major Chinese airline confirm the effectiveness and efficiency of the solution approaches. It is also demonstrated the save of available working hours resulting from adaptively creating long connections would decrease the recovery cost by about 18.87%–74.88%.

The Diagnostic Yield and Clinical Impact of Systematic Screening of Kidney Transplant Candidates by Cardiac Computed Tomography: A Cohort Study

Although cardiovascular screening of kidney transplant candidates is recommended, the optimal approach is debated. Previous studies show that noninvasive imaging provides prognostic information, but systematic screening may have less recognized effects, such as additional investigations, incidental findings, procedural complications, and delay of transplantation. To address this, we characterized the diagnostic yield and clinical implications of systematic screening for cardiovascular disease using cardiac computed tomography (CT) in potential kidney transplant candidates. This was a single-center, observational cohort study including all potential kidney transplant candidates >40 years of age or with diabetes or on dialysis treatment for >5 years, systematically referred to cardiac computed tomography (CT; non-contrast CT and coronary CT angiography) between 2014 and 2019 before evaluation for kidney transplantation at Aarhus University Hospital. Patient records were examined for data on baseline characteristics, additional investigations and complications, plasma creatinine, dialysis initiation, time until wait-listing, and incidental findings. Of 473 patients who underwent cardiac CT, additional cardiac investigations were performed in 156 (33%), and 32 (7%) were revascularized. Twenty-two patients had significant incidental nonvascular findings on cardiac CT. No patient was rejected for transplantation based on cardiac CT. In patients not yet on dialysis, the slope in the estimated glomerular filtration rate decline did not change significantly after coronary CT angiography. Screening by cardiac CT led to additional cardiac investigations in one-third of patients; only a few patients were revascularized, with unknown benefits in asymptomatic patients. Cardiac CT was safe in this population; however, the clinical consequences of the screening were limited.

Roughness induced transition delay in a swept-wing boundary layer in presence of freestream disturbances, Part 2: Acoustic stabilization

Results of experimental investigations on control of the laminar–turbulent transition location in a 45-degree swept-wing boundary layer by the distributed micro-sized roughness (MSR) elements in presence of freestream perturbations are discussed in this two-part work. Part 1 of this study Borodulin et al. (2023) is devoted to the freestream turbulence effects, while Part 2 (the present paper) concentrates on consideration of the acoustic waves’ effects. This paper contains: (i) a complementary description of the experimental setup and measurement techniques related to the acoustic excitation and (ii) the results of studies of the freestream acoustic-field effects on the MSR transition control. The robustness of the MSR transition-control mechanism has been studied by altering the wind-tunnel flow quality: by introducing a significant background sound and/or by simultaneous variation of both the freestream turbulence level and the level of the acoustic wave excitation. At enhanced freestream turbulence, the laminar–turbulent transition is found to move upstream regardless of the sound level and frequency, while the MSR-elements lost their effectiveness in transition control in all cases. At low freestream turbulence levels and in absence of the MSR, the acoustic waves did not affect basically the transition location. However, if the laminar–turbulent transition was delayed by the MSR, the sound of a certain frequency was found to be able to cause a significant additional transition delay.

Дослідження показників якості організації дорожнього руху в умовах міста методом GPS-треків

The choice of rational quality criteria for the organization of road traffic in cities is an urgent task for scientists in the field of road transport, as it directly affects the effectiveness of activities in the field of ensuring the safety and comfort of car traffic in urban conditions. Depending on the goals of the analysis, the complexity of the network, and technical capabilities, the quality of traffic management can be assessed by indicators of the economic efficiency of the transport process, the level of accidents, environmental safety, social attractiveness, etc. The modern level of development of geo-information technologies allows for constant monitoring of the vehicle's speed mode. To obtain characteristics of the quality of traffic organization, experimental studies were conducted on a section of the street-road network of the city of Kharkiv, which corresponds to a typical route of personal transport from a remote sleeping area to the central part of the city.&#x0D; As a result of data processing of the GPS track, a histogram of the distribution of instantaneous speed and graphs of the car’s movement in the coordinates “time-distance”, “time-speed”, "distance-speed” were built, which allow you to visually assess the mode of movement along the entire route and determine potential "bottlenecks". Such spatio-temporal characteristics as average technical speed, specific time in motion, specific idle time, as well as energy indicators of the quality of traffic management were also calculated: acceleration noise, speed gradient, energy gradient. After dividing the experimental route into separate kilometer sections, changes in the characteristics of the quality of traffic organization, as it approached the city center, were analyzed. On the first half of the route, when moving along the main street, the instability of the speed regime was observed due to stops and idling in the zone of regulated intersections. The presence of a trend towards a decrease in the average technical speed when approaching the city center is explained by an increase in the loading of VDM within the central business part of the city and, as a result, the appearance of additional traffic delays. As we approached the city center, the specific time in motion increased with a slight increase in the specific idle time, and an increase in the speed gradient was also observed with a slight decrease in the energy gradient.

The utility of all-freeze IVF cycles depends on the composition of study populations

BackgroundBecause often introduced without proper validation studies, so-called “add-ons” to IVF have adversely affected in vitro fertilization (IVF) outcomes worldwide. All-freeze cycles (embryo banking, EB) with subsequently deferred thaw cycles are such an “add-on” and, because of greatly diverging reported outcomes, have become increasingly controversial. Based on “modeling” with selected patient populations, we in this study investigated whether reported outcome discrepancies may be the consequence of biased patient selection.ResultsIn four distinct retrospective case control studies, we modeled in four cohort pairings how cryopreservation with subsequent thaw cycles affects outcomes differently in good-, average- and poor-prognosis patients: (i) 127 fresh vs. 193 frozen donor-recipient cycles to model best-prognosis patients; (ii) 741 autologous fresh non-donor IVF cycles vs. 217 autologous frozen non-donor IVF cycles to model average prognosis patients; (iii) 143 favorably selected autologous non-donor IVF cycles vs. the same 217 frozen autologous cycles non-donor to monitor good- vs. average-prognosis patients; and (iv) 598 average and poor-prognosis autologous non-donor cycles vs. the same 217 frozen autologous non-donor cycles to model poor vs. average prognosis patients. In best-prognosis patients, EB marginally improved IVF outcomes. In unselected patients, EB had no effects. In poor-prognosis patients, EB adversely affected IVF outcomes. Unexpectedly, the study also discovered independent-of-age-associated chromosomal abnormalities, a previously unreported effect of recipient age on miscarriage risk in donor-egg recipients.ConclusionsIn poor-prognosis patients, EB cycles should be considered contraindicated. In intermediate-prognosis patients EB does not appear to change outcomes, not warranting additional cost and time delays. Therefore, only good-prognosis patients are candidates for EB, though they will experience only marginal benefits that may not be cost-effective.