Non-uniform Patterns Research Articles

Study of MFL signal identification in pipelines based on non-uniform magnetic charge distribution patterns

Magnetic flux leakage (MFL), a pipeline internal detection, is the mainstream technology for international oil and gas pipeline safety maintenance. To address the problem of large errors in the assessment of defects in pipeline inspection by existing theoretical analysis models, this paper introduces the charge density parameter to establish a mathematical model of non-uniform magnetic charge for pipeline leakage detection and calculates the non-uniform distribution pattern of magnetic charge on the defect side wall. The contour plot method is proposed to visually analyze the size of defects. To compare the error between uniform and non-uniform models, and verify the correctness of the theoretical model, experiments were systematically conducted on the X70 pipeline with internal MFL technology. The results show that: the magnetic charge distribution curve is symmetrically shaped at the center of the defect, with a valley at the center and two peaks at the defect edge. As the defect depth and width increase, the magnetic charge density increases sharply near the surface and edge. The peak-to-valley spacing and peak-to-valley values in the contour map of the MFL signal can directly reflect the location and size of defects. The signal characteristic values follow the trend of a first-order decreasing exponential function as the value of the lift-off increases. The first-order derivative of the signal characteristic value tends to decrease and then increase as the mesh size decreases, and the extreme point of the derivative curve is the best mesh size.

Improving the Power Output of a Partially Shaded Photovoltaic Array through a Hybrid Magic Square Configuration with Differential Evolution based Adaptive P&O MPPT Method

Abstract A partially shaded photovoltaic (PV) array's characteristic curve is convoluted due to disparity in irradiance levels between shaded and unshaded PV panels, resulting in power mismatch losses. This work presents a new hybrid approach combining the Magic Square (MS) array configuration and Differential Evolution based adaptive perturb and observe (DEAPO) MPPT methodology to overcome the abovementioned problem. The proposed hybrid methodology is implemented in two steps: first, repositioning the PV panels as per the MS configuration to decrease the power losses of partial shading. In MS configuration, the concentrated shadow on a single row or column can spread over to the entire PV array equally without any physical or electrical switching of PV panels. Second, the DEAPO MPPT method is developed to find the global peak power point on the PV characteristic curve. PID controller coefficients are optimized by DE to enhance the tracking speed and convergence of the adaptive P&O MPPT. The simulation study of this work has been implemented using PV arrays in MATLAB/SIMULINK environment and the real-time validation is done through a 5 kW PV array. The proficiency of the proposed hybrid approach is tested by creating various non-uniform and uniform shading patterns on the PV array. The simulation and experimental results prove that the proposed hybrid approach increases the power output by 19% and 20% higher than the existing Total Cross Tie (TCT) configuration under non-uniform and uniform shading cases respectively.

Disparities in Fertility-Sparing Treatment and Use of Assisted Reproductive Technology After a Diagnosis of Cervical, Ovarian, or Endometrial Cancer.

To assess the presence of sociodemographic and clinical disparities in fertility-sparing treatment and assisted reproductive technology (ART) use among patients with a history of cervical, endometrial, or ovarian cancer. We conducted a population-based cohort study of patients aged 18-45 years who were diagnosed with cervical cancer (stage IA, IB), endometrial cancer (grade 1, stage IA, IB), or ovarian cancer (stage IA, IC) between January 1, 2000, and December 31, 2015, using linked data from the CCR (California Cancer Registry), the California Office of Statewide Health Planning and Development, and the Society for Assisted Reproductive Technology. The primary outcome was receipt of fertility-sparing treatment , defined as surgical or medical treatment to preserve the uterus and at least one ovary. The secondary outcome was fertility preservation , defined as ART use after cancer diagnosis. Multivariable logistic regression analysis was used to estimate odds ratios and 95% CIs for the association between fertility-sparing treatment and exposures of interest: age at diagnosis, race and ethnicity, health insurance, socioeconomic status, rurality, and parity. We identified 7,736 patients who were diagnosed with cervical, endometrial, or ovarian cancer with eligible histology. There were 850 (18.8%) fertility-sparing procedures among 4,521 cases of cervical cancer, 108 (7.2%) among 1,504 cases of endometrial cancer, and 741 (43.3%) among 1,711 cases of ovarian cancer. Analyses demonstrated nonuniform patterns of sociodemographic disparities by cancer type for fertility-sparing treatment, and ART. Fertility-sparing treatment was more likely among young patients, overall, and of those in racial and ethnic minority groups among survivors of cervical and ovarian cancer. Use of ART was low (n=52) and was associated with a non-Hispanic White race and ethnicity designation, being of younger age (18-35 years), and having private insurance. This study demonstrates that clinical and sociodemographic disparities exist in the receipt of fertility-sparing treatment and ART use among patients with a history of cervical, endometrial, or ovarian cancer.

Probabilistic Similarity of Non-Uniform Corrosion Pattern between Natural Corrosion and Accelerated Experiment

Probabilistic Similarity of Non-Uniform Corrosion Pattern between Natural Corrosion and Accelerated Experiment

Numerical study on the thermal-hydraulic characteristic of an automotive parallel-flow condenser under non-uniform airflow

The performance of an automotive parallel-flow condenser was numerically investigated considering both airside and refrigerant-side flow mal-distributions, the thermal-hydraulic characteristic of the condenser under the air-side blockage of each tube pass was first studied, then the influence of the form and degree of uneven airflow that may be revealed in vehicles on the performance of the condenser was analyzed. At last, using the simulation model combined with the measurements of the vehicle in the climatic wind tunnel, the thermal-hydraulic features of the condenser as well as the performance of the A/C system under various front-end status and vehicle conditions was evaluated. It was found that the performance degradation of the condenser resulting from the air-side blockage of the first pass exceeds that caused by the obstruction of all the other three passes together. According to the performance deterioration sequence of the condenser from high to low, the order of the four possible non-uniform airflow patterns in vehicles is low on the top and high at the bottom (LTHB), low in the middle (LM), high in the middle (HM), and high on the top and low at the bottom (HTLB), and the last two forms could even enhance the performance of the condenser under certain working conditions. The rule of cooling airflow optimization is to arrange large/small air velocity on the area with intrinsically large/small refrigerant side heat transfer coefficient of the condenser. The possible direction of cooling airflow design in vehicles is inferred.

Improving the Yearly Profit of Wind Farm with Artificial Intelligence Technique

Owing to the escalating environmental and social problems linked to climate change and the hastily depleting stock of hydrocarbon-based fuels, renewable power generation modes have attained massive prominence. Wind power is an important renewable energy generation technology that contributed to 5% of the planet’s power generation in 2020. However, for sustaining the Paris Agreement targets, the global wind power generation sector necessitates evolving at a fleeter pace. To expand the green switch of the worldwide power generation businesses, wind farms are expected to remain financially more advantageous than fossil fuel-based power plants. The present work focused on elevating the annual profit of wind farms by employing an amended genetic algorithm (GA). A fresh approach to dynamically apportioning the crossover and mutation prospects for a GA-enabled profit growth algorithm was suggested to amplify the capability of the GA. Three dissimilar terrain conditions with diverse obstruction configurations and a randomly generated non-uniform wind flow pattern were used for assessing the competence of the proposed algorithm for profit maximization. The results showed that the annual yields for Terrain Layouts 1, 2 and 3 obtained by the amended GA were higher by 10.34, 5.09 and 0.51%, respectively, than the typical one, which substantiated the superior proficiency of the former.

Energy Availability Factors Drive the Geographical Pattern of Tenebrionidae (Coleoptera) in the Arid and Semiarid Areas of China

Species richness is regarded as the core index of biogeography. Estimating the correlation between species richness and modern environmental factors will be of great significance for species conservation. The arid and semiarid areas of China present serious desertification, but there are rich biodiversity resources of high value. In this study, we evaluated species diversity, species richness, and the correlation between species richness and modern environmental factors using the species of Tenebrionidae in arid and semiarid areas of China, which will provide basic data for species conservation. The species richness was measured using 1° × 1° grid cells, and its determinants were explored based on generalized linear models (GLMs) and random forest models. A total of 696 species, belonging to 125 genera of 38 tribes and 7 subfamilies, were recorded in the study area. The non-uniform species richness pattern was presented, with more species in Altai, Tianshan, Nyenchen Thanglha and Helan Mountains. The species richness was affected by a variety of environmental factors. The variables representing energy availability and climate stability had stronger explanatory power, especially the annual mean temperature (BIO1) and the mean temperature of warmest quarter (BIO10). In contrast, water availability and habitat heterogeneity have relatively little correlation with species richness.

Polarization-Sensitive Patterning of Azopolymer Thin Films Using Multiple Structured Laser Beams

The polarization sensitivity of azopolymers is well known. Therefore, these materials are actively used in many applications of photonics. Recently, the unique possibilities of processing such materials using a structured laser beam were demonstrated, which revealed the key role of the distribution of polarization and the longitudinal component of light in determining the shape of the nano- and microstructures formed on the surfaces of thin azopolymer films. Here, we present numerical and experimental results demonstrating the high polarization sensitivity of thin azopolymer films to the local polarization state of an illuminating structured laser beam consisting of a set of light spots. To form such arrays of spots with a controlled distribution of polarization, different polarization states of laser beams, both homogeneous and locally inhomogeneous, were used. The results obtained show the possibility of implementing a parallel non-uniform patterning of thin azopolymer films depending on the polarization distribution of the illuminating laser beam. We believe that the demonstrated results will not only make it possible to implement the simultaneous detection of local polarization states of complex-shaped light fields but will also be used for the high-performance fabrication of diffractive optical elements and metasurfaces.

Combined Distributed Shared-Buffered and Diagonally-Linked Mesh Topology for High-Performance Interconnect.

Networks-on-Chip (NoCs) have become the de-facto on-chip interconnect for multi/manycore systems. A typical NoC router is made up of buffers used to store packets that are unable to advance to their desired destination. However, buffers consume significant power/area and are often underutilized, especially in cases of applications with non-uniform traffic patterns thus leading to performance degradation for such applications. To improve network performance, the Roundabout NoC (R-NoC) concept is considered. R-NoC is inspired by real-life multi-lane traffic roundabouts and consists of lanes that are shared by multiple input/output ports to maximize buffering resource utilization. R-NoC relies on router-internal adaptive routing that decides the lane path based on back pressure. Back pressure makes it possible to assess lane utilization and route packets accordingly. This is made possible thanks to the use of elastic buffers for control flow, a clever type of handshaking in a way similar to asynchronous circuits. Another prominent feature of R-NoC is that internal routing and arbitration are completely distributed which allows for significant freedom in deciding internal router topology and parameters. This work leverages this property and proposes novel yet unexplored configurations for which an in-depth evaluation of corresponding implementations on 45 nm CMOS technology is given. Each configuration is evaluated performance and power-wise on both synthetic and real application traffic. Several R-NoC configurations are identified and demonstrated to provide very significant performance improvements over standard mesh configurations and a typical input-buffered router, without compromising area and power consumption. Exploiting the distributed nature of R-NoC routers, a diagonally-linked configuration is then proposed which incurs moderate area overhead and features yet better performance and energy efficiency.

An inelastic-state based procedure to calculate the force demands along building height for recentering steel building frames

To eliminate the residual deformation of conventional seismic-resistant steel building frames, numerous resilient building frames with recentering capacities were developed. However, prior researches indicated the severe higher mode effect of such structural systems may lead to nonuniform deformation pattern. To improve the seismic performance of recentering building frames, this paper develops a practice-oriented procedure to calculate the force demands along building height. The procedure includes the effect of hysteretic principle based on the expected structural inelastic-state. To validate the proposed procedure, multiple designs were performed on 27 demonstration building frames. Nonlinear response history analyses were conducted to evaluate the applicability of the proposed procedure. Based on the results of numerical analyses conducted in this research, it was found that the considered system designed in line with the prevailing design procedure may lead to unsatisfactory deformation in top or bottom stories. Using the force demands from the proposed procedure will help the considered structural system develop a more uniform deformation pattern along building height.

Matching Traffic Demand in GEO Multibeam Satellites: The Joint Use of Dynamic Beamforming and Precoding Under Practical Constraints

To adjust for the non-uniform spatiotemporal nature of traffic patterns, next-generation high throughput satellite (HTS) systems can benefit from recent technological advancements in the space-segment in order to dynamically design traffic-adaptive beam layout plans (ABLPs). In this work, we propose a framework for dynamic beamforming (DBF) optimization and adaptation in dynamic environments. Given realistic traffic patterns and a limited power budget, we propose a feasible DBF operation for a geostationary multibeam HTS network. The goal is to minimize the mismatch between the traffic demand and the offered capacity under practical constraints. These constraints are dictated by the traffic-aware design requirements, the on-board antenna system limitations, and the signaling considerations in the K-band. Noting that the ABLP is agnostic about the inherent inter-beam interference (IBI), we construct an interference simulation environment using irregularly shaped beams for a large-scale multibeam HTS system. To cope with IBI, the combination of on-board DBF and on-ground precoding is considered. For precoded and non-precoded HTS configurations, the proposed design shows better traffic-matching capabilities in comparison to a regular beam layout plan. Lastly, we provide trade-off analyses between system-level key performance indicators for different realistic non-uniform traffic patterns.

Mapping of quench front propagation in a heated cylindrical particle bed – MONET tests

In case of a severe accident in nuclear reactor, a debris bed may be formed from the fragmentation of the molten core at different stages of the accident. Debris bed coolability is an important issue, as it will determine the accident progression, its termination, and mitigation. One of the major concerns of debris bed coolability investigations is to understand and evaluate the effect of water re-flooding. Many experiments have been conducted to study the two-phase flow and heat transfer in porous medium configuration. However, the understanding of debris bed quenching with multi-dimensional characteristics are limited. Here, a test facility MCCI-mitigatiON through passive cooling Effect Test (MONET) apparatus is established to conduct the porous debris bed re-flooding investigation. The objective is to understand the mechanism of heat transfer and quench front movement inside the cylindrical heated debris bed during quenching by cooling water supplied from the bottom of the bed. Specifically, the effect of Homogeneous bed (with different external boundary conditions) and radially stratified bed (with different internal porosity configurations) conditions of the cylindrical debris bed on the quench front movement has been investigated. The particulate debris bed is formed with two different types of particles (SS 304, alumina) and sizes (2–3.5 mm). The effect on the quench front movement inside the particle bed has been reported by using temperature measurements together with direct visualizations. Present findings suggest non-uniform quench front propagation pattern even for the homogeneous bed conditions. While the tests with the stratified bed indicate a clear influence of low porosity region on the quench front and vapor movement.

Specific isotopic labelling and reverse labelling for protein NMR spectroscopy: using metabolic precursors in sample preparation.

The study of protein structure, dynamics and function by NMR spectroscopy commonly requires samples that have been enriched ('labelled') with the stable isotopes 13C and/or 15N. The standard approach is to uniformly label a protein with one or both of these nuclei such that all C and/or N sites are in principle 'NMR-visible'. NMR spectra of uniformly labelled proteins can be highly complicated and suffer from signal overlap. Moreover, as molecular size increases the linewidths of NMR signals broaden, which decreases sensitivity and causes further spectral congestion. Both effects can limit the type and quality of information available from NMR data. Problems associated with signal overlap and signal broadening can often be alleviated though the use of alternative, non-uniform isotopic labelling patterns. Specific isotopic labelling 'turns on' signals at selected sites while the rest of the protein is NMR-invisible. Conversely, specific isotopic unlabelling (also called 'reverse' labelling) 'turns off' selected signals while the rest of the protein remains NMR-visible. Both approaches can simplify NMR spectra, improve sensitivity, facilitate resonance assignment and permit a range of different NMR strategies when combined with other labelling tools and NMR experiments. Here, we review methods for producing proteins with enrichment of stable NMR-visible isotopes, with particular focus on residue-specific labelling and reverse labelling using Escherichia coli expression systems. We also explore how these approaches can aid NMR studies of proteins.

Integrated Single Cell Analysis Reveals Co-Evolution of Malignant B Cells and the Tumor Microenvironment in Transformed Follicular Lymphoma

Introduction: The transformation of follicular lymphoma (FL) is believed to follow a divergent evolutionary model. However, the relationship between clonal (genetic) evolution and phenotype has been largely unexplored. Similarly, it is unknown if transformation arises from the expansion of a pre-existing clone with a transformed genotype, or if instead it requires the acquisition of genetic and phenotypic traits absent at diagnosis. In addition, previous bulk sequencing studies have provided only limited information about tumor microenvironment (TME) components. To address these shortcomings, we used single cell whole transcriptome (scWTS) and whole genome sequencing (scWGS) to characterize the clonal and phenotypic evolution of malignant B cells during transformation and elucidate interactions within TME. Methods: Our study included 11 transformed FL (tFL) patients with paired FL and DLBCL time point biopsies, and 11 indolent FL controls (>6y follow-up without progression/transformation). Combined scWTS and BCR sequencing was performed for all samples, along with scWGS for transformation pairs. We included two independent validation cohorts of pre-treatment FLs (N=125 treated with Rituximab-Bendamustine and N=154 with Rituximab-CVP (N=154)). Results: Phylogenetic analysis using scWGS showed a non-uniform pattern of evolution across the tFL pairs. In 3 pairs, all genetically-defined clones were composed of cells from both FL and DLBCL time points (called mixed-clones). Conversely, in 5 pairs fully divergent evolution was observed, featuring unique genetic clones at the DLBCL timepoint. Finally, 3 pairs had both mixed and unique DLBCL clones. Clustering of malignant B cells from tFL pairs using scWTS data indicated that the transcriptional similarity between the FL and DLBCL samples was inversely correlated with the time between sampling. Importantly, in the 6 pairs with well-separated FL and DLBCL clusters, some FL cells could always be found within the DLBCL clusters (so-called "DLBCL-like cells") and vice-versa. Integrative analysis of scWGS and scWTS data highlighted that samples with the fewest genomic changes showed the least transcriptional change. However, this correlation did not hold true for all tFL pairs. In particular, 2 pairs showed minimal genomic change but a high degree of phenotypic change, suggesting other determinants of cellular phenotype. Furthermore, in the 5 pairs with an extreme genomic clonal divergence, the strict co-evolution of malignant B-cell genotypes and phenotypes could not account for the presence of cells with a "DLBCL-like" phenotype in FL time point biopsies (Figure A). Differential expression and GSEA of malignant cells identified "MYC targets V1'', "mTORC1", and "OXPHOS" as pathways enriched in malignant B cells at the transformed time point compared to the earlier FL. Within these pathways, control non-tFL cells had significantly lower gene expression scores than pre-transformed FL, independent of cell-cycle state. At the TME level, a significant composition shift was observed from T cells with a TFH and central memory phenotype in FL samples, to cells with an exhausted phenotype at the time of transformation. The largest shift was an increase in the CD8+/LAG3+/PD1+ population (more than doubled, Figure B), confirmed by multicolour-IHC analysis. The magnitude of the TME shift was correlated with the magnitude of the malignant B-cell phenotypic evolution. A cell-cell interaction analysis highlighted MIF/CD44 and CD27/CD70 pathways as enriched at the time of transformation, while IL15/IL15RA signaling was more prominent in FLs. Finally, in two independent cohorts of pre-treatment FL, the proportion of CD8+/LAG3+ cells within the CD20-negative TME compartment was associated with time to transformation, time to progression and disease specific survival, independently of FLIPI score and FL histologic grade. Conclusion: By applying high-dimensional scWTS and scWGS techniques, we describe the range of possible relationships between cellular genotype and phenotype during FL transformation. We observed different modes of clonal evolution, from the expansion of a precursor cell population present at the time of diagnosis, to the emergence of novel clones present only at transformation. Shifts in the TME composition allowed us to identify a CD8+/LAG3+ population that could be used as a predictive marker of transformation risk. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Sensitivity and spectral control of network lasers

Recently, random lasing in complex networks has shown efficient lasing over more than 50 localised modes, promoted by multiple scattering over the underlying graph. If controlled, these network lasers can lead to fast-switching multifunctional light sources with synthesised spectrum. Here, we observe both in experiment and theory high sensitivity of the network laser spectrum to the spatial shape of the pump profile, with some modes for example increasing in intensity by 280% when switching off 7% of the pump beam. We solve the nonlinear equations within the steady state ab-initio laser theory (SALT) approximation over a graph and we show selective lasing of around 90% of the strongest intensity modes, effectively programming the spectrum of the lasing networks. In our experiments with polymer networks, this high sensitivity enables control of the lasing spectrum through non-uniform pump patterns. We propose the underlying complexity of the network modes as the key element behind efficient spectral control opening the way for the development of optical devices with wide impact for on-chip photonics for communication, sensing, and computation.

Thermal mechanical characteristics research of HL-2M vacuum vessel during baking

The medium-sized tokamak HL-2M has been built in Chengdu and get its first plasma in December 2020. The vacuum vessel was assembled and passed the 1 MPa pressure tests and the preliminary vacuum tests at the SWIP in 2019. To get a high quality vacuum condition, vacuum vessel and in-vessel components should be baked up to check the quality of all welds and remove all water vapor in the material. Due to baking the non-uniform temperature pattern on the vessel coupled with atmospheric pressure loading and self-weight give rise to high thermal-mechanical stresses, which needs to be analyzed in detail. Pre-baking should heat vacuum vessel up to 100–120 °C, the thermal insulation layers(micro porousmaterial) were applied on the outer surface of the vessel to reduce the heat loss. The surface temperature distribution of vessel was measured by thermocouples and displacement was measured by potentiometer and laser displacement sensors. The pre-baking experiments show that the temperature and displacement distribution over the vessel wall are with100±10 °C and ±2 mm. During natural cooling, it is predicted that the time constant τc of vacuum vessel is about 20 h and the total heat loss power is about 34 kW. The pre-baking experiment provides support for the safe operation of HL-2M device, and provides valuable experience for the future induction baking or high temperature baking experiment.

Extreme heat loss in the Northern Red Sea and associated atmospheric forcing

A regional, high-resolution reanalysis was analyzed to explore extreme heat loss events in the Northern Red Sea (NRS) and their links to specific regional atmospheric circulation patterns. Such events are determinant for the overturning circulation of the Red Sea and occur frequently between November and March, with maximum frequency during December and January. During these events, the most intense heat loss, often with daily-averaged values lower than -1000 W/m2, is found over the southern half of the Gulf of Aqaba and along the western coastline of the open NRS. Analyses of the spatial modes of variability of these events suggest that the majority of them extend over the entire NRS in an almost uniform way; however, secondary, nonuniform patterns related to regional adjustment in the wind field are also identified. The uniform cold outbursts are associated with distinct atmospheric circulation patterns, which favor the transfer of cold air masses from higher latitudes over the eastern Mediterranean Seaviaa strong northwest wind field. Nonuniform events affect considerable parts of the NRS and occur when cold and dry air masses reach the NRS through the Middle East and the northern part of the Arabian Peninsula. The regional sea level pressure drives a clockwise rotation of the wind field that ultimately blows from the northeast/east direction. This rotation of the wind field favors local intensification and lee areas defined by the complex topography and characteristic gaps in the mountain chain along the eastern coastline of the NRS, reflecting the differentiations in the spatial distribution of the heat flux minima.

Performance of upper-room ultraviolet germicidal irradiation (UVGI) system in learning environments: Effects of ventilation rate, UV fluence rate, and UV radiating volume

• We study performance of upper-room ultraviolet germicidal irradiation (UVGI) systems. • Performance of upper-room UVGI system in a classroom varies with ventilation rate. • Non-uniform airflow pattern meaningfully influences the UVGI system performance. • UV radiating volume is more crucial for virus disinfection than UV fluence rate. • Doubling UV fluence rate from 25 to 50 μW∙cm-2 yields only moderate benefit. Previous studies show that upper-room ultraviolet germicidal irradiation (UVGI) systems can help contain infectious airborne viruses indoors. However, there has been a lack of research on the performance of an upper-room UVGI system in learning environments such as a school classroom. Since classrooms are more vulnerable to airborne transmission of diseases due to high occupancy for long hours, airborne infection characteristics are different from other occupied indoor environments (e.g., offices and residences). The objective of this study is to investigate UVGI system performance in a classroom considering detailed effects of ventilation rate, UV fluence rate, and UV radiating volume. Two analytical models, a one-zone and a two-zone material balance model, along with computational fluid dynamics (CFD) simulations, were employed to analyze viral aerosol concentrations under a representative range of classroom operating conditions. The CFD results show that increasing ventilation rate from 1.1 h –1 to 5 h –1 yields about 85% of airborne disinfection while doubling UV radiating volume results in a 60% disinfection. However, increasing UV fluence rate from 25 μW∙cm –2 to 50 μW∙cm –2 yields a moderate additional disinfection of 18%. Overall, the study results reveal that operating a UVGI system in an occupied classroom can markedly disinfect airborne viruses up to 96%, which is as effective as increasing ventilation rate more than five times. Furthermore, the results suggest that the one-zone and two-zone analytical models used in several previous studies could result in notably meaningful errors in analyzing viral aerosol concentrations, especially in occupied rooms with a highly non-uniform airflow distribution.

Avoiding Dense and Dynamic Obstacles in Enclosed Spaces: Application to Moving in Crowds

This paper presents a closed-form approach to constrain a flow within a given volume and around objects. The flow is guaranteed to converge and to stop at a single fixed point. We show that the obstacle avoidance problem can be inverted to enforce that the flow remains enclosed within a volume defined by a polygonal surface. We formally guarantee that such a flow will never contact the boundaries of the enclosing volume and obstacles, and will asymptotically converge towards an attractor. We further create smooth motion fields around obstacles with edges (e.g. tables). Both obstacles and enclosures may be time-varying, i.e. moving, expanding and shrinking. The technique enables a robot to navigate within an enclosed corridor while avoiding static and moving obstacles. It was applied on an autonomous robot (QOLO) in a static complex indoor environment, and also tested in simulations with dense crowds. The final proof of concept was performed in an outdoor environment in Lausanne. The QOLO-robot successfully traversed a marketplace in the center of town in presence of a diverse crowd with a non-uniform motion pattern.

Perfusion-Based Fluorescent Dye Labeling to Sort Cancer Cells Based on Their Distance from Blood Vessels.

Tumor vasculature is the major extrinsic factor that shapes Intra-tumoral heterogeneity (ITH). Non-uniform exposure of microenvironmental cues greatly impacts cancer cell phenotypes leading to ITH, which exacerbates therapy resistance. This raises a need to study the influence of non-uniform perfusion patterns and the resulting heterogeneity that persists within the tumor microenvironment (TME). A method was developed to identify cancer cells based on their proximity to functional blood vessels (BVs) called perfusion-based fluorescent dye labeling of cells (PFDLC). PFDLC works on the principle of perfusion, where a freely diffusible nuclear binding fluorescent dye (Hoechst 33342) is injected intravenously (i.v.) through a tail vein into atumor-bearing mice. The tumors are retrieved post dye perfusion, dissociated into single cells, and sorted based on their dye uptake proportional to their distance from the nearest blood capillary. This method is amenable to multi-omics as well as functional assays.