Arbitrary Time Windows Research Articles

On Querying Historical Connectivity in Temporal Graphs

We study the historical connectivity query in temporal graphs where edges continuously arrive. Given an arbitrary time window, and two query vertices, the problem aims to identify if two vertices are connected by a path in the snapshot of the window. The state-of-the-art method designs an index based on the two-hop cover, and updating the index is costly when new edges arrive. In this paper, we propose a new framework and design a novel forest-based index for historical connectivity queries. The index enables us to answer queries by searching if two vertices are connected in the forest. We update the index by modifying a forest structure. Our techniques also work for connectivity query processing in a sliding window of temporal graphs. Extensive experiments have been conducted to show the considerable advantages of our approach compared with the state-of-the-art methods in both historical connectivity queries and sliding-window connectivity queries.

ChainDash: An Ad-Hoc Blockchain Data Analytics System

The emergence of digital asset applications, driven by Web 3.0 and powered by blockchain technology, has led to a growing demand for blockchain-specific graph analytics to unearth the insights. However, current blockchain data analytics systems are unable to perform efficient ad-hoc graph analytics over both live and past time windows due to their inefficient data synchronization and slow graph snapshots retrieval capability. To address these issues, we propose ChainDash, a blockchain data analytics system that dedicates a highly-parallelized data synchronization component and a retrieval-optimized temporal graph store. By leveraging these techniques, ChainDash supports efficient ad-hoc graph analytics of smart contract activities over arbitrary time windows. In the demonstration, we showcase the interactive visualization interfaces of ChainDash, where attendees will execute customized queries for ad-hoc graph analytics of blockchain data.

Classification of Standing and Walking States Using Ground Reaction Forces.

The operation of wearable robots, such as gait rehabilitation robots, requires real-time classification of the standing or walking state of the wearer. This report explains a technique that measures the ground reaction force (GRF) using an insole device equipped with force sensing resistors, and detects whether the insole wearer is standing or walking based on the measured results. The technique developed in the present study uses the waveform length that represents the sum of the changes in the center of pressure within an arbitrary time window as the determining factor, and applies this factor to a conventional threshold method and an artificial neural network (ANN) model for classification of the standing and walking states. The results showed that applying the newly developed technique could significantly reduce classification errors due to shuffling movements of the patient, typically noticed in the conventional threshold method using GRF, i.e., real-time classification of the standing and walking states is possible in the ANN model. The insole device used in the present study can be applied not only to gait analysis systems used in wearable robot operations, but also as a device for remotely monitoring the activities of daily living of the wearer.

Variability of Millennial‐Scale Trends in the Geomagnetic Axial Dipole

AbstractThe historical trend in the axial dipole is sufficient to reverse the field in less than 2 kyr. Assessing the prospect of an imminent polarity reversal depends on the probability of sustaining the historical trend for long enough to produce a reversal. We use a stochastic model to predict the variability of trends for arbitrary time windows. Our predictions agree well with the trends computed from paleomagnetic models. Applying these predictions to the historical record shows that the current trend is likely due to natural variability. Furthermore, an extrapolation of the current trend for the next 1 to 2 kyr is highly unlikely. Instead, we compute the trend and time window needed to reverse the field with a specified probability. We find that the dipole could reverse in the next 20 kyr with a probability of 2%.

CR10-A PUBLIC DATABASE OF COSMIC RADIATION MEASUREMENTS AT AVIATION ALTITUDES OF ABOUT 10 KM.

Long-term measurements using silicon radiation spectrometer Liulin on board commercial aircraft have been performed since 2001; results were put into a new database, which covers more than 4500 flights with more than 130 000 measurements. Methodology and tools were developed to normalize the data with respect to latitude and altitude and thus enable comparison with other radiation detectors and with model calculations. This capability is demonstrated using data from the neutron monitor at Lomnický štít. Instead of providing data files for individual measurement period, two software solutions are delivered. First is a web-based user interface for visualizing and downloading arbitrary time window of interest from the database hosted at http://cr10.odz.ujf.cas.cz. The second is a set of interactive Python notebooks available at GitHub. Those implement the calibration, normalization and visualization methods-so the outputs can be tailored to user needs. The software and data are provided under GNU/CC license.

Real-time hierarchical systems with arbitrary scheduling at global level

Partitioned architectures isolate software components into independent partitions whose execution will not interfere with other partitions, preserving temporal and spatial isolation. Hierarchical scheduling can effectively be used to schedule these systems. Schedulability analysis of hierarchical real-time systems is based on prior knowledge of the local and the global scheduling algorithms.In a partitioned system with safety and security issues and certification assurance levels, global scheduling is usually generated using a static table. Therefore, each partition must allocate task jobs only in the temporal windows reserved for that partition. Even if the static table can come originally from a periodic server or other scheduling policy, the final plan may be modified due to changes in the system requirements. As a consequence, the CPU assignment to a partition does not have to correspond to any known policy. In this case, it is not possible to use existing scheduling analysis for hierarchical systems.This paper studies a new scheduling problem: a hierarchical system in which global policy is not known but provided as a set of arbitrary time windows.

Acute ischemic stroke treatment, part 1: patient selection "the 50% barrier and the capillary index score".

The current strategy for intra-arterial treatment (IAT) of acute ischemic stroke focuses on minimizing time from ictus to revascularization and maximizing revascularization. Employing this strategy has yet to lead to improved rates of successful outcomes. However, the collateral blood supply likely plays a significant role in maintaining viable brain tissue during ischemia. Based on our prior work, we believe that only approximately 50% of patients are genetically predisposed to have sufficient collaterals for a good outcome following treatment, a concept we call the 50% barrier. The Capillary Index Score (CIS) has been developed as a tool to identify patients with a sufficient collateral blood supply to maintain tissue viability prior to treatment. Patients with a favorable CIS (f CIS) may be able to achieve a good outcome with IAT beyond an arbitrary time window. The CIS is incorporated into a proposed patient treatment algorithm. For patients suffering from a large stroke without aphasia, a non-enhanced head CT should be followed by CT angiography (CTA). For patients without signs of stroke mimics or visible signs of structural changes due to large irreversible ischemia, CTA can help confirm the vascular occlusion and location. The CIS can be obtained from a diagnostic cerebral angiogram, with IAT offered to patients categorized as f CIS.

Schedulability Analysis of Hierarchical Systems with Arbitrary Scheduling in the Global Level

Schedulability analysis of hierarchical real-time systems is based in the previous knowledge of the scheduling algorithms both in the local and the global levels.In a partitioned system with safety and security issues and certification assurance levels, the global scheduling is usually generated using a static table. Therefore, each partition must allocate task jobs only in the temporal windows reserved for that partition. Even if the static table can come originally from a periodic server or other scheduling policy, the final plan can suffer from modifications due to changes in the system requirements. As a consequence, the CPU assignment to a partition does not have to correspond to any known policy. In this case, it is not possible to use existing scheduling analysis for hierarchical systems. This paper provides a schedulability analysis when the global level policy is not known but provided as a set of arbitrary time windows. The paper also provides a method to determine the more restrictive CPU assignment for a task set, as a mean of stablishing minimum temporal requirements for the partition.

Network representation of dynamical systems: Connectivity patterns, information and predictability

The present work elaborates on predictability and information aspects of dynamical systems, in connection with the connectivity features of their network representation. The basic idea underlying this work is to map the set of coarse-grained states of a dynamical system onto a set of network nodes and transitions between them onto a set of network links. Based on the vertex centrality of these nodes, we define (a) a local indicator of predictability, (b) a measure of the information that is available about the state of the system after one transition occurring within an arbitrary long time window and (c) an upper bound for the time horizon of predictability. We address the cases of the tent and the cusp maps, as representative examples of Markov and non-Markov processes. An analytical exact result for the horizon of predictability is obtained for the tent map, as well as for its higher iterates, and its connection with the corresponding network diameters is discussed. Similarly, analytical expressions are derived for the bounds of the predictability horizon in the case of the cusp map.

A Job Monitoring and Accounting Tool for the LSF Batch System

This paper presents a web based job monitoring and group-and-user accounting tool for the LSF Batch System. The user oriented job monitoring displays a simple and compact quasi real-time overview of the batch farm for both local and Grid jobs. For Grid jobs the Distinguished Name (DN) of the Grid users is shown. The overview monitor provides the most up-to-date status of a batch farm at any time. The accounting tool works with the LSF accounting log files. The accounting information is shown for a few pre-defined time periods by default. However, one can also compute the same information for any arbitrary time window. The tool already proved to be an extremely useful means to validate more extensive accounting tools available in the Grid world. Several sites have already been using the present tool and more sites running the LSF batch system have shown interest. We shall discuss the various aspects that make the tool essential for site administrators and end-users alike and outline the current status of development as well as future plans.

One channel spatio-temporal inversion of acoustic wave in reverberant cavities

It has been recently shown that it was possible to optimally recover the Green functions from a complex wave field despite of a non-isotropic distribution of the noise sources. The method used is based on a particular use of the inverse filter (IF) formalism which is called the passive IF. Based on this formalism, we have investigated the possibility to control the spatio-temporal degrees of freedom in a reverberant cavity for the focusing of waves (active processes). The understanding of this phenomenon can be very useful in a lot of different applications like in acoustical imaging, seismology, or telecommunications. In the present work, the spatio-temporal focalization of ultrasounds in reverberant cavities is studied using medical arrays and water tanks. Through experiments, a complete spatio-temporal inversion is realized to synthesize optimized emitting signals. The result generalizes the focalization control over a spatial vector and during an arbitrary time window.

Direct measurement of power during one single sprint on treadmill

We tested the validity of an instrumented treadmill dynamometer for measuring maximal propulsive power during sprint running, and sought to verify whether this could be done over one single sprint, as shown during sprint cycling. The treadmill dynamometer modified towards sprint use (constant motor torque) allows vertical and horizontal forces to be measured at the same location as velocity, i.e. at the foot, which is novel compared to existing methods in which power is computed as the product of belt velocity and horizontal force measured by transducers placed in the tethering system. Twelve males performed 6 s sprints against default, high and low loads set from the motor torque necessary to overcome the friction due to subjects’ weight on the belt (default load), and 20% higher and lower motor torque values. Horizontal ground reaction force, belt velocity, propulsive power and linear force–velocity relationships were compared between the default load condition and when taking all conditions together. Force and velocity traces and values were reproducible and consistent with the literature, and no significant difference was found between maximal power and force–velocity relationships obtained in the default load condition only vs. adding data from all conditions. The presented method allows one to measure maximal propulsive power and calculate linear force–velocity relationships from one single sprint data. The main novelties are that both force and velocity are measured at the same location, and that instantaneous values are averaged over one contact period, and not over a constant arbitrary time-window.

Thrombolytic therapy for stroke

This review article describes thrombolysis as an effective treatment for acute ischemic stroke. The aim of acute thrombolytic therapy is to break up the thrombus or embolus occluding a cerebral artery and restore perfusion to reversibly ischemic brain. Current evidence from randomized, controlled trials limits the therapeutic time window for thrombolysis to 4.5 h for intravenous treatment and 6 h for intra-arterial treatment. Guidelines emphasize the need to identify acute stroke as a clinical priority, and to develop ‘fast-track’ protocols for the early assessment and treatment of stroke patients. The use of advanced imaging techniques and adjuncts to thrombolysis that may have the potential to improve the ability to select patients who may benefit from reperfusion therapy, and allow treatment decisions to be based on individual brain pathophysiology rather than arbitrary time windows, are discussed.

Runway sequencing with holding patterns

We study a scheduling problem, motivated by air-traffic control. When aircraft reach the final descent in the “Terminal Radar Approach CONontrol” area ( tracon), a set of disjoint time windows in which the landing is possible, can be automatically assigned to each aircraft. The objective is then to determine landing times, within these time windows, which maximize the minimum time elapsed between consecutive landings. We study the complexity of the problem and describe several special cases that can be solved in polynomial time. We also provide a compact Mixed Integer Programming formulation that allows us to solve large instances of the general problem when all time windows have the same size. Finally, we introduce a general hybrid branch and cut framework to solve the problem with arbitrary time windows. Experimental results show that our approach outperforms earlier formulation of the problem.

The single-machine early-tardy Problem with Idle Time and Time Windows Permitted

In this article, a single-machine weighted earliness and tardiness problem with arbitrary time windows is considered. Idle time between two adjacent jobs is permitted and the due dates of jobs may be unequal. The dominance rules can be utilized to develop a relationship matrix which allows the branching algorithm to eliminate a high percentage of nonfeasible solutions. After this matrix is combined with a branching strategy, a procedure which can solve the problem is proposed.

An Efficient Format for Nearly Constant-Time Access to Arbitrary Time Intervals in Large Trace Files

A powerful method to aid in understanding the performance of parallel applications uses log or trace files containing time-stamped events and states (pairs of events). These trace files can be very large, often hundreds or even thousands of megabytes. Because of the cost of accessing and displaying such files, other methods are often used that reduce the size of the tracefiles at the cost of sacrificing detail or other information. This paper describes a hierarchical trace file format that provides for display of an arbitrary time window in a time independent of the total size of the file and roughly proportional to the number of events within the time window. This format eliminates the need to sacrifice data to achieve a smaller trace file size (since storage is inexpensive, it is necessary only to make efficient use of bandwidth to that storage). The format can be used to organize a trace file or to create a separate file ofannotationsthat may be used with conventional trace files. We present an analysis of the time to access all of the events relevant to an interval of time and we describe experiments demonstrating the performance of this file format.

Advances in Interventional Neuroradiology 2006

Although the traditional use of intravenous (IV) thrombolytics is restricted to within 3 hours of stroke onset, the use of intra-arterial (IA) therapy is proving to be more flexible, with the ultimate time window yet to be determined. Anecdotal evidence suggests that thrombectomy may be effective beyond the 6-hour window in properly selected patients.1 Clinical success and the incidence of complications may be more dependent on the results of perfusion-imaging and the presence of large-vessel occlusion and less on an arbitrary time window. Multimodality strategies are becoming more popular. A combination of mechanical clot retrieval and adjunctive thrombolytic therapies in 111 patients participating in the Multi MERCI trial resulted in successful recanalization in 69% of vessels versus 54% with the retriever alone.2 The preliminary results of the IMS II trial indicate that the MicroLysus ultrasound device (EKOS Corp) may improve recanalization rates compared with standard microcatheter techniques.3,4 Multimodal therapy combining IV or IA abciximab and intracranial angioplasty has been reported to achieve high recanalization rates,5 and preliminary experience with intracranial stenting in acute stroke suggests that this may be an attractive adjunct to IA thrombolytics.6,7 A retrospective review of 168 patients treated with a combination of IA thrombolytics and mechanical interventions reported recanalization in 63% and improvement in NIHSS of at least 4 points in 21% of patients at 24-hour follow-up,8 with the highest recanalization rates seen in patients in whom 3 or more IA modalities …

Photon Counting Histograms for Diffusing Fluorophores

The theory of photon counting histograms for fluorescent molecules diffusing through a laser spot is presented. Analytic expressions for the factorial cumulants of photon counts are obtained. For an arbitrary counting time window, it is shown how the exact histograms can be obtained by solving an appropriate reaction-diffusion equation. Our formalism reduces correctly when the molecules are immobile. The approximation used in fluorescence intensity multiple distribution analysis (FIMDA) is tested against the exact numerical solution of the problem. FIMDA works very well for a wide range of parameters except for small concentrations and long time windows.

Analysis of long-term variations in the geomagnetic poloidal field intensity and evaluation of their relationship with global geodynamics

SUMMARY The 1167 published cooling unit (CU) palaeointensity estimates contained in the 400‐10 Ma portion of the PINT global database were rigorously filtered according to accurate age determinations, palaeodirectional reliability, recognition of polarity and the method of palaeointensity acquisition. The remaining 865 estimates (group 1) were further filtered to ensure self-consistency, reducing the data set to 425 estimates (group 2). Group 1 and 2 data were clustered into temporally and/or spatially distinct rock suites (RS) enabling each part of the record to be assessed for potential biasing by overrepresentation of palaeosecular variation (PSV). The record was segmented according to the distribution of the data, rather than using arbitrary time windows, to ensure quasi-consistent behaviour within each segment. Differences between these segments clearly indicate that a significant long-timescale (10 7 and 10 8 yr) variation of the mean geomagnetic poloidal field intensity (GPFI) occurred during the 400‐10 Ma period and hence that changing lowermost mantle conditions affect the capacity of the geodynamo to generate a poloidal field. Both the mean dipole moment and its standard deviation appear to be a function of the range of values each CU may adopt at one particular time. This range is itself controlled by the variation of the maximum limit of dipole moment, while the value of the minimum limit remains relatively constant. Tentative support is provided for the recent suggestion that PSV may have been reduced during the Cretaceous normal superchron (CNS), though more data are needed in the range 120‐60 Ma to confirm this. No conclusive evidence was found to support the suggestion that the GPFI record may be biased towards low or high values by palaeointensity determinations obtained using methods that do not adopt pTRM checks. Indeed, offsets caused by unreliable data in well-represented parts of the record are likely to be random and cancel one another out. When GPFI variation is analysed at a sufficiently high resolution to allow comparisons with the geomagnetic polarity reversal frequency (RF), it is not possible to confirm whether the two parameters are anticorrelated, decoupled or related in some more complex way. However, it is clear that GPFI and RF are definitely not positively correlated as has been previously suggested. The present database documents sharp increases in GPFI around the onset times of the two recognized superchrons, itself implying an anticorrelation. The implications, for geodynamo and mantle modelling, of both an anticorrelation and a decoupling of the geomagnetic parameters are discussed briefly. A generic geodynamic model is proposed to explain the relationship between observed longterm changes in GPFI and global geodynamic processes. The model predicts that changes in GPFI result from a chain of geodynamic processes extending from crust to core, beginning with plate reorganizations at the surface and culminating in increases in the vigour of outer core convection. Supercontinents are transient surface expressions of such geodynamic processes and provide the potential to test the generic model. Four time stages are proposed to describe the major long-term changes in GPFI since the Early Devonian: 400‐350, 350‐250, 250‐175

Single-machine scheduling with time windows and earliness/tardiness penalties

We study the single machine earliness/tardiness problem with arbitrary time windows (STW). We show that STW is NP-hard and then decompose it into the subproblems of finding a good job sequence and optimally inserting idle time into a given sequence. We propose heuristics for the sequencing subproblem by appropriately modifying heuristics originally developed for other single machine scheduling problems. Experimentation with randomly generated problems shows that one of the proposed heuristics is computationally efficient and capable of finding good solutions to problems of arbitrary size. We also propose an algorithm to optimally insert idle time into a given job sequence.