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Let X be a closed subspace of a metric space M. It is well known that, under mild hypotheses, one can estimate the Betti numbers of X from a finite set P⊂ M of points approximating X. In this paper, we show that one can also use P to estimate much more detailed topological properties of X. We achieve this by proving the stability of A-persistent homology. In its most general case, this stability means that given a continuous function f: Y→ R on a topological space Y, small perturbations in the function f imply at most small perturbations in the family of A-barcodes. This work can be viewed as a proof of the stability of cup-product and generalized-Massey-products persistence. The technical key of this paper consists of figuring out a setting which makes A-persistence functorial., We would like to thank Justin Curry for valuable feedback on previous versions of this paper. F. Belchí was partially supported by the EPSRC grant EPSRC EP/N014189/1 (Joining the dots) to the University of Southampton and by the Spanish State Research Agency through the María de Maeztu Seal of Excellence to IRI (MDM-2016-0656). A. Stefanou was partially supported by the National Science Foundation through grants CCF-1740761 (TRIPODS TGDA@OSU) and DMS-1440386 (Mathematical Biosciences Institute at the Ohio State University).

Analysis of cardiac ultrasound images is commonly performed in routine clinical practice for quantification of cardiac function. Its increasing automation frequently employs deep learning networks that are trained to predict disease or detect image features. However, such models are extremely data-hungry and training requires labelling of many thousands of images by experienced clinicians. Here we propose the use of contrastive learning to mitigate the labelling bottleneck. We train view classification models for imbalanced cardiac ultrasound datasets and show improved performance for views/classes for which minimal labelled data is available. Compared to a naive baseline model, we achieve an improvement in F1 score of up to 26% in those views while maintaining state-of-the-art performance for the views with sufficiently many labelled training observations., Accepted in ASMUS workshop of MICCAI 2021

Migration monitoring may allow us to detect population trends over large geographic areas because the pattern of change in migrant counts may be expected to follow the pattern of change in population size. We analysed recent regional European population trends of migratory soaring birds from rates of change in migration counts over the Strait of Gibraltar (Spain) during the years (1999–2013). An additional bottleneck (Organbidexka, France) within the same migratory route and period was also considered. We estimated count trends by fitting a log-generalized linear model to the time series of each species counts. The counts in Organbidexka were used to test the consistency in the observed trends over the Strait of Gibraltar. Migration counts of White and Black Storks, Black Kites, Short-toed and Booted Eagles as well as Egyptian Vultures showed a linear increase over the Strait of Gibraltar throughout the 15-year period. In contrast, Honey Buzzard numbers remained stable. Trends were highly consistent with those recorded in Organbidexka. We suggest that the larger slopes for the trends in Organbidexka when compared with the Strait reflect an increasing tendency in these species to overwinter in southern Europe. A combination of complementary data sets collected at different bottleneck sites within the European–African flyway system may become a fundamental tool for the investigation of migratory patterns and population trends and changes of soaring migrant birds all over Europe.https://doi.org/10.1007/s10531-016-1047-4, The data counts from the Strait of Gibraltar analyzed in the study were collected in field monitoring campaigns 1999/2012 funded by grants of the Consejeria de Medio Ambiente of the Junta de Andalucía (Spain)

© The Editor(s) (if applicable) and the Author(s) 2015. While many innovations in Technology Enhanced Learning (TEL) have emerged over the last two decades, the uptake of these innovations has not always been very successful, particularly in schools. The transition from proof of concept to integration into learning activities has been recognized as a bottleneck for quite some time. This major problem, which is affecting many TEL stakeholders, is the focus of the 4-year iTEC project that is developing a comprehensive approach involving 15 ministries of education and is organizing a large scale validator with more than a thousand classrooms. This chapter reports on how the information provision on events of interest in learning as well as on persons that can contribute to learning activities, supports novel scenarios and is key for the introduction of open education in the K12 education. ispartof: Re-engineering the Uptake of ICT in Schools pages:115-139 ispartof: pages:115-139 status: published

This paper presents an adaptive resource control mechanism for multi-hop ad-hoc network systems, which avoids bottleneck problems caused by the node-fairness property of IEEE 802.11. In our proposal, the feedback information from the downstream bottleneck, derived from Request-To-Send (RTS) and Clear-To-Send (CTS) messages is utilized to control the Transmission Opportunity (TXOP) limit of the upstream nodes for traffic balancing. The proposed mechanism is modelled control-theoretically using the 20-sim control system modelling tool, which has the advantage that results can be obtained in a fast and efficient way. Compared to systems without resource control, a higher throughput and lower delay can be achieved under a variety of traffic load conditions as well as in dynamic network environments.

Two-hop ad-hoc networks, in which some nodes forward traffic for multiple sources, with which they also compete for channel access suffer from large queues building up in bottleneck nodes. This problem can often be alleviated by using IEEE 802.11e to give preferential treatment to bottleneck nodes. Previous results have shown that differentiation parameters can be used to allocate capacity in a more efficient way in the two-hop scenario. However, the overall throughput of the bottleneck may differ considerably, depending on the differentiation method used. By applying a very fast and accurate analysis method, based on steady-state analysis of an QBD-type infinite Markov chain, we find the maximum throughput that is possible per differentiation parameter. All possible parameter settings are explored with respect to the maximum throughput conditioned on a maximum buffer occupancy. This design space exploration cannot be done with network simulators like NS2 or Opnet, as each simulation run simply takes to long. The results, which have been validated by detailed simulations, show that by differentiating TXOP it is possible to achieve a throughput that is about 50% larger than when differentiating AIFS and $\text{CW}_{\text{min}}$.

This chapter presents a design space exploration method for mixed event-triggered and time-triggered real-time systems in the automotive domain. A design space exploration model is used that is capable of modeling and optimizing state-of-the-art automotive systems including the resource allocation, task distribution, message routing, and scheduling. The optimization is based on a heuristic approach that iteratively improves the system design. Within this iterative optimization it is necessary to analyze each system design where one of the major design objectives that needs to be evaluated is the timing behavior. Since timing analysis is a very complex design task with high computational demands, it might become a bottleneck within the design space exploration. As a remedy, a clustering strategy is presented that is capable of reducing the complexity and minimizing the runtime of the timing analysis. A case study gives evidence of the efficiency of the proposed approach.

Decreased hatchability is a common consequence of inbreeding in oviparous organisms and it has been generally considered a useful measure of the effects of reduced genetic diversity on embryological development. Here, we examined the pattern of hatching failure in a wild population of the endangered Lesser Kestrel (Falco naumanni). Particularly, we first analyzed long-term changes of hatching failure over a 16-year study period (1991-2006), in which the study population experienced a concurrent demographic and genetic recovery, and then we determined the consequences of parental genetic characteristics on hatching success. Long-term data analyses revealed a significant decline of hatching failure over time, with annual average hatching failure decreasing from rates characterizing species that have passed a severe population bottleneck to levels generally reported for outbred bird populations. Partial purging of deleterious recessive alleles after the species population decline, the increase of heterozygosity over time reported in a previous study and/or the selection for efficient mechanisms of inbreeding avoidance could be responsible of the observed temporal pattern. In contrast to previous studies, we found no effect of parental genetic characteristics on hatching success. Even though we analyzed an extensive dataset, the 11 neutral markers typed may have had low power to detect such an association. Further, this analysis was limited to the last 5 years (2002-2006) of the whole study period, when DNA samples for genetic analyses were available. During these years, hatching rates were like those typically reported for non-inbred populations, suggesting that the absence of association could be explained by a reduction of the genetic load or consequence of the genetic recover reported in the study population in recent years., This work received financial support from the projects: PAI05-053 (Junta de Comunidades de Castilla-La Mancha) and CGL2005-05611-C02-02/BOS (Ministerio de Educación Ciencia). During this work, J.O and G.C. were supported by predoctoral fellowships from the Junta de Comunidades de Castilla-La Mancha and the European Social Fund.

Data integration has been a challenging problem for decades. In an ambient environment, where many autonomous devices have their own information sources and network connectivity is ad hoc and peer-to-peer, it even becomes a serious bottleneck. In addition, the number of information sources per device, as well as in total, increases as well. To enable devices to exchange information without the need for interaction with a user at data integration time and without the need for extensive semantic annotations, a probabilistic approach seems rather promising. It simply teaches the device how to cope with the uncertainty occurring during data integration. Unfortunately,without any kind of world knowledge, almost everything becomes uncertain, hence maintaining all possibilities produces huge integrated information sources. Automatically integrating data sources, using very simple knowledge rules to rule out most of the nonsense possibilities, combined with storing the remaining possibilities as uncertainty in the database and resolving these during querying by means of user feedback, seems the promising solution. In this chapter we introduce this “good is good-enough” integration approach and explain the uncertainty model that is used to capture the remaining integration possibilities. We show that using this strategy, the time necessary to integrate documents drastically decreases, while the accuracy of the integrated document increases over time.

Trabajo presentado en la International Conference on Computer Aided Systems Theory (EUROCAST 2011), celebrada en Las Palmas de Gran Canaria (España), del 6 al 11 de febrero de 2011, Dealing with urban traffic is a highly complex task since it involves the coordination of many actors. Traditional approaches attempt to optimize traffic signal control for a particular vehicle density; the main disadvantage lies in the fact that traffic changes constantly. Managing traffic congestion seems to be a problem of adaptation rather than of optimization. In this work we present an agent-based traffic simulator which represents a traffic grid with two-way roads of three exclusive lanes per direction, with intersections regulated by signals. We study the repercussions on traffic flow of simple parametric behaviours when each light operates independently. A dominance analysis is applied to compare the strategies.

Discrete & Computational Geometry, 24 (4), ISSN:0179-5376, ISSN:1432-0444

This study aims to determine whether the application of cattle manure and associated bioturbation by dung beetles and other invertebrates can increase oak seedling establishment in the high biodiversity Mediterranean silvopastoral systems known as "dehesas", which are comprised of scattered oaks and a grassland layer and are used for livestock rearing. A two-year study was conducted in a representative dehesa in southern Spain. Firstly, the effect of cattle dung pads on acorn consumption by livestock and wild predators was monitored, along with dung beetle abundance and plot bioturbation. Secondly, the indirect effects of bioturbation on acorn burial, acorn predation by rodents and oak seedling establishment were assessed under the condition of livestock exclusion. The results consistently demonstrate a high positive indirect effect of the presence of cattle manure on the persistence of acorns, as well as on seedling establishment, as a result of reduced predation by rodents and improved microhabitat conditions for the acorns and seedlings. These processes were mediated by bioturbation. Tunneler dung beetles, which move a great amount of soil material, were dominant in our records, which suggest their importance for passive acorn burial, without disregarding the influence of other edaphic invertebrates present. We conclude that the presence of cattle manure significantly improves oak seedling establishment in Mediterranean dehesas through the passive burial of acorns by bioturbation, which acts to protect them from predation by rodents, desiccation and other damage. Passive acorn burial by dung beetles and other invertebrates thus emerges as an important ecosystem service that has been little-studied to date. Appropriate rotational management of livestock could therefore contribute to addressing the bottleneck of oak regeneration in Mediterranean dehesas. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Partial financial support was provided by the Regional Government of Andalucia, Ministry of Economy and Revenues (2017/00000634).

Producción Científica, Data centers are a fundamental infrastructure in the Big-Data era, where applications and services demand a high amount of data and minimum response times. The interconnection network is an essential subsystem in the data center, as it must guarantee high communication bandwidth and low latency to the communication operations of applications, otherwise becoming the system bottleneck. Simulation is widely used to model the network functionality and to evaluate its performance under specific workloads. Apart from the network modeling, it is essential to characterize the end-nodes communication pattern, which will help identify bottlenecks and flaws in the network architecture. In previous works, we proposed the VEF traces framework: a set of tools to capture communication traffic of MPI-based applications and generate traffic traces used to feed network simulator tools. In this paper, we extend the VEF traces framework with new communication workloads such as deep-learning training applications and online data-intensive workloads., Ministerio de Ciencia e Innovación y Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033) R &D Project Grant (PID2019-109001RA-I00), Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

Using self-supervision in anomaly detection can increase sensitivity to subtle irregularities. However, increasing sensitivity to certain classes of outliers could result in decreased sensitivity to other types. While a single model may have limited coverage, an adaptive method could help detect a broader range of outliers. Our proposed method explores whether meta learning can increase the adaptability of self-supervised methods. Meta learning is often employed in few-shot settings with labelled examples. To use it for anomaly detection, where labelled support data is usually not available, we instead construct a self-supervised task using the test input itself and reference samples from the normal training data. Specifically, patches from the test image are introduced into normal reference images. This forms the basis of the few-shot task. During training, the same few-shot process is used, but the test/query image is substituted with a normal training image that contains a synthetic irregularity. Meta learning is then used to learn how to learn from the few-shot task by computing second order gradients. Given the importance of screening applications, e.g. in healthcare or security, any adaptability in the method must be counterbalanced with robustness. As such, we add strong regularization by i) restricting meta learning to only layers near the bottleneck of our encoder-decoder architecture and ii) computing the loss at multiple points during the few-shot process.

Nowadays underwater vision systems are being widely applied in ocean research. However, the largest portion of the ocean - the deep sea - still remains mostly unexplored. Only relatively few image sets have been taken from the deep sea due to the physical limitations caused by technical challenges and enormous costs. Deep sea images are very different from the images taken in shallow waters and this area did not get much attention from the community. The shortage of deep sea images and the corresponding ground truth data for evaluation and training is becoming a bottleneck for the development of underwater computer vision methods. Thus, this paper presents a physical model-based image simulation solution, which uses an in-air texture and depth information as inputs, to generate underwater image sequences taken by robots in deep ocean scenarios. Different from shallow water conditions, artificial illumination plays a vital role in deep sea image formation as it strongly affects the scene appearance. Our radiometric image formation model considers both attenuation and scattering effects with co-moving spotlights in the dark. By detailed analysis and evaluation of the underwater image formation model, we propose a 3D lookup table structure in combination with a novel rendering strategy to improve simulation performance. This enables us to integrate an interactive deep sea robotic vision simulation in the Unmanned Underwater Vehicles simulator. To inspire further deep sea vision research by the community, we release the source code of our deep sea image converter to the public (https://www.geomar.de/en/omv-research/robotic-imaging-simulator).

Este artículo contiene 9 páginas, 2 tablas, 1 figura, Antarctic bottoms harbor stable, benthic communities, subjected to low temperatures. Environmental stability may promote the asexual (clonal) reproduction of sponges to maintain adapted genotypes to those particular conditions. Stylocordyla chupachups forms patchy populations across the Antarctic continental shelf. Individuals are mostly similar in size without distinct cohorts, which indicates fast growth of the new recruits. Settlement of incubated (clonal?) functional sponges may accelerate sponge growth and success at early colonization phases. To analyze the weight of clonal reproduction in the species, a genetic study was performed on three close populations using eight polymorphic microsatellite loci that were designed from massive sequencing. The three study populations showed a relatively low genetic diversity and low loci polymorphism (from 2 to 6 alleles). The estimators of genetic structure, the Analysis of the Molecular Variance (AMOVA), and the presence of private alleles indicated low but significant structure between the populations. A relatively high rate of asexual reproduction (ca. 25% of the individuals) was detected. The program MLGsim found five identical multilocus genotypes (MLGs) with an asexual origin. An excess of heterozygotes (in five out of the eight loci genotyped) was found, which suggests a positive selection mechanism for heterozygotes. The relatively high rates of asexual reproduction may be the result of adaptation to the environmental stability, while heterozygote selection would help maintain some genetic diversity in the populations. S. chupachups has been reported to be one of the first sponge species recolonizing bare areas resulting from iceberg scouring, which indicates a high species fitness and adaptation to Antarctic bottoms. Two out of the three study populations showed bottleneck, which may indicate a recent founder effect and supports the pioneer nature of this species., The study has been partially funded by MarSymBiomics project (Spanish FECYT agency grant ref. CTM2013-43286-P), Benthic Ecology Consolidate Award (Generalitat of Catalonian ref. 2017SGR-378), PopComics (CTM88080AEI/FEDER/VE) from the Spanish Government, and BluePharmTrain FP7 People-INT no: 607786 to MJU.

Book Review., Sample preparation is a key aspect of the total analytical process with a profound effect on the accuracy and precision of the final result. Unless a highly selective separation-plus-detection technique is used for final analyte determination, current sample treatment procedures commonly involve a number of steps for quantitative extraction of the target compounds from the matrix and subsequent isolation and enrichment from co-extracted material. These several treatments frequently result in tedious, time-consuming and highly manipulative protocols, and frequently sample preparation is still the bottleneck of the analytical process in many application areas.

5th International Symposium, ISVC 2009, Las Vegas, NV, USA, November 30 - December 2, 2009, Proceedings, Part I. LNAI 5875. Springer, In this paper we present a pixel-level object categorization method suitable to be applied under real-time constraints. Since pixels are categorized using a bag of features scheme, the major bottleneck of such an approach would be the feature pooling in local histograms of visual words. Therefore, we propose to bypass this time-consuming step and directly obtain the score of a linear Support Vector Machine classiffier. This is achieved by creating an integral image of the components of the SVM which can readily obtain the classification score for any image sub-window with only 10 additions and 2 products, regardless of its size. Besides, we evaluated the performance of two efficient feature quantization methods: the Hierarchical K-Means and the Extremely Randomized Forest. All experiments have been done in the Graz02 database, showing comparable, or even better results to related work with a lower computational cost., This work was supported by TIN 2006-15308-C02-02 project grant of the Ministry of Education of Spain, the CSD2007-00018 and the MIPRCV Consolider Ingenio 2010, the European Social Fund, the project grant 200450E550, FEDER funds, and the grant 2009-SGR-1434.

BDDC method is the most advanced method from the Balancing family of iterative substructuring methods for the solution of large systems of linear algebraic equations arising from discretization of elliptic boundary value problems. In the case of many substructures, solving the coarse problem exactly becomes a bottleneck. Since the coarse problem in BDDC has the same structure as the original problem, it is straightforward to apply the BDDC method recursively to solve the coarse problem only approximately. In this paper, we formulate a new family of abstract Multispace BDDC methods and give condition number bounds from the abstract additive Schwarz preconditioning theory. The Multilevel BDDC is then treated as a special case of the Multispace BDDC and abstract multilevel condition number bounds are given. The abstract bounds yield polylogarithmic condition number bounds for an arbitrary fixed number of levels and scalar elliptic problems discretized by finite elements in two and three spatial dimensions. Numerical experiments confirm the theory., Comment: 26 pages, 3 figures, 2 tables, 20 references. Formal changes only

The technology trends of Microelectronics and Microsystems are mainly characterized by miniaturization down to the nano-scale, increasing levels of system and function integration, and the introduction of new materials, while the business trends are mainly characterized by cost reduction, shorter-time-to market and outsourcing. Combination of these trends leads to increasing design complexity, dramatically decreasing design margins and process windows, reducing product development and qualification times, increasing risks of failures, and increasing difficulties to meet quality, robustness and reliability requirements. Consequentially, thermo-mechanical related failures, accounting for more than 65% of the total reliability failures, become the bottleneck for both current and future product and technology developments. From a mechanical engineering point of view, Microelectronics and Microsystems are multi-scale in both geometric and time domains, multi-process, multi-functionality, multi-disciplinary, multi-material/interface, multi-damage and multi-failure mode. Their responses in manufacturing, assembling, qualification tests and application conditions are strongly nonlinear and stochastic. Mechanics of Microelectronics is extremely important and challenging, in terms of both industrial applications and academic research. Written by the leading experts with both profound knowledge and rich practical experience in advanced mechanics and microelectronics industry, this book aims to provide the cutting edge knowledge and solutions for various mechanical related problems, in a systematic way. It contains essential and detailed information about the state-of-the-art theories, methodologies, the way of working and real case studies, covering the contents of: The trends in Microelectronics and Microsystems Reliability engineering and practices Thermal management Advanced mechanics Thermo-mechanics of integrated circuits and packages Characterization and modelling of moisture behaviour Characterization and modelling of solder joint reliability Virtual thermo-mechanical prototyping Challenges and future perspectives.

Discontinuous Galerkin (DG) method is presented for numerical modeling of melt migration in a chemically reactive and viscously deforming upwelling mantle column. DG methods for both advection and elliptic equations provide a robust and efficient solution to the problems of melt migration in the asthenospheric upper mantle. Assembling and solving the elliptic equation is the major bottleneck in these computations. To address this issue, adaptive mesh refinement and local timestepping methods have been proposed to significantly improve the computational wall time. The robustness of DG methods is demonstrated through two benchmark problems by modeling detailed structure of high-porosity dissolution channels and compaction-dissolution waves.

Biomolecular computing is the field of engineering where computation, storage, communication, and coding are obtained by exploiting interactions between biomolecules, especially DNA, RNA, and enzymes. They are a promising solution in a long-term vision, bringing huge parallelism and negligible power consumption. Despite significant efforts in taking advantage of the massive computational power of biomolecules, many issues are still open along the way for considering biomolecular circuits as an alternative or a complement to competing with complementary metal-oxide-semiconductor (CMOS) architectures. According to the Von Neumann architecture, computing systems are composed of a central processing unit, a storage unit, and input and output (I/O). I/O operations are crucial to drive and read the computing core and to interface it to other devices. In emerging technologies, the complexity overhead and the bottleneck of I/O systems are usually limiting factors. While computing units and memories based on biomolecular systems have been successfully presented in literature, the published I/O operations are still based on laboratory equipment without a real development of integrated I/O. Biosensors are suitable devices for transducing biomolecular interactions by converting them into electrical signals. In this work, we explore the latest advancements in biomolecular computing, as well as in biosensors, with focus on technology suitable to provide the required and still missing I/O devices. Therefore, our goal is to picture out the present and future perspectives about DNA, RNA, and enzymatic-based computing according to the progression in its I/O technologies, and to understand how the field of biosensors contributes to the research beyond CMOS.

Presented at World Congress on Medical Physics and Biomedical Engineering; 2012 May 26-31; Beijing, China. Miniaturization of implantable medical elec-tronic devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants – batteries and inductive cou-plers – comprise bulky parts which, in most cases, are signifi-cantly larger than the circuitry they feed. For overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, we recently proposed and demonstrated a method based on making the implants operate as rectifiers of bursts of high frequency current supplied by remote electrodes. In this way, low frequency current is generated locally around the implant and this low frequency current performs stimulation of excitable tissues whereas the high frequency current only causes innocuous heating. The present paper reports further progress in this technology. We first describe construction and functional test of an injectable stimulator consisting of a single miniature diode (300 μm × 300 μm × 600 μm) and two thin electrodes which is implanted trough a 19G needle into an anesthetized earthworm. We then propose a circuit architec-ture for implementing smart implants based on this technol-ogy. Both accomplishments are steps towards the implementa-tion of injectable addressable microsystems for neuroprosthetics. These systems based on the proposed tech-nology will look like short pieces of flexible thread rather than rigid capsules, as it was the case of previous miniature electri-cal stimulation implants. With currently available microelec-tronic techniques, very thin stimulation implants (diameter < 200 μm) are easily conceivable. This technology may be foun-dational to a broad range of new developments in the field of implantable medical devices with applications ranging from wound healing to nerve stimulation for pain relief. In addition, other non-medical devices could also emerge such as implant-able identification devices. AI’s research is supported by a Ramón y Cajal fellow-ship from the Spanish Ministry for Science and Innovation and a Marie Curie IRG from the European Commission

The massive addition of cores on a chip is adding more pressure to the accesses to main memory. In order to avoid this bottleneck, we propose the use of a simple producer-consumer model, which allows for the temporary results to be transferred directly from one task to another. These data transfer operations are performed within the chip, using on-chip memory, thus avoiding costly off-chip memory accesses. We implement this model on a real many-core processor, the 48-core Intel Single-chip Cloud Computer processor using its on-chip memory facilities. We find that the Producer-Consumer model adapts to such architectures and allow to achieve good task and data parallelism. For the evaluation of the proposed platform we implement a graph-based application using the Producer- Consumer model. Our tests show that the model scales very well as it takes advantage of the on-chip memory. The execution times of our implementation are up to 9 times faster than the baseline implementation, which relies on storing the temporary results to main memory.