Total Occupation Time Research Articles

Economic impact of anaesthesia methods used in hand surgery: Global costs and operating room's throughput

Recently, local anaesthesia has become popular among hand surgeons. We hypothesized that using the "wide awake local anaesthesia no tourniquet" (WALANT) approach would result in lower global costs and in an increase in the operating room (OR)'s efficiency. All cases of carpal tunnel (CTR) and trigger finger releases (TFR) performed over 2016 and 2017 were divided into four groups, following which the anaesthesia method was used. Total OR occupation time, surgical time and the "all but surgery" time were analysed. A common minimum bill per anaesthesia was generated. WALANT or local anaesthesia and tourniquet increase the OR's throughput by having shorter operation room occupation times than other methods (17.5-33%). Costs of the two procedures are reduced by 21-31% when using local anaesthesia methods. Preferring those techniques for CTR and TFR has a notable beneficial impact on the costs and on the OR's efficiency. This effect is more evident on short surgical procedures. LOE: Level of evidence III, economic analysis.

Multiple Radiocarbon Dating of Human remains: Clarifying the Chronology and Sequences of Burials in the late Neolithic Dolmen of Oberbipp (Switzerland)

ABSTRACTUndisturbed megalithic burials are extremely rare because in addition to human activities, natural disturbances due to water influence and erosion or faunal activity are likely to occur over time. The dolmen of Oberbipp discovered in 2011 provides a unique opportunity for multidisciplinary research since anthropogenic and natural disturbances are minor. Morphological analysis indicates that approximately 42 individuals were buried in the grave chamber. Using archaeological methods alone, it would not have been possible to determine different occupation periods within the inhumations. Neolithic communities often reused dolmen over centuries. Therefore, radiocarbon (14C) dating is the only method that can solve the question of temporal resolution. Fragments of the same bone element (right femora) were analyzed by two (in some cases three) different laboratories to date all inhumations individually. The aim of this study was threefold: (1) to determine the total occupation time of the dolmen (2) to evaluate the sequence of the burials, and (3) to compare the results of the same skeletal element from different laboratories. In total, 79 radiocarbon dating results from three different laboratories of the right femora (n = 32) were obtained. The total time span of the occupation of the dolmen was between 3350 and 2650 BC. The broad application of radiocarbon dating allowed the determination of two occupation periods within the burial.

Track Allocation Optimization in Multi-Direction High-Speed Railway Stations

Track allocation optimization in railway stations is one of the most fundamental problems for scheduling trains, especially in multi-direction high-speed railway stations. With the construction of high-speed rail networks, this kind of station has become increasingly common. However, the track allocation depends not only on the station tracks, train timetable, and rolling stock plan, but also on the resources in the station throat area. As a result, an effective track allocation plan becomes significant but also difficult. In this paper, we consider all these factors to make the results more practicable and an integer linear model that minimizes the total occupation time of resources in the throat area is presented. A flexible track utilization rule is also adopted to this model to fit the characteristics of the multi-direction station. Meanwhile, a detailed explanation of resources’ occupation time is illustrated to facilitate the representation of the conflicting constraints. To resolve these issues, we use a commercial solver with its default parameters. A computational experiment of a station is conducted to verify the effectiveness of the proposed model. The resources utilization plan indicates that the capacity of a station is limited by the throat area, rather than by the station tracks.

Evolutionary 4G/5G Network Architecture Assisted Efficient Handover Signaling

Future wireless networks are expected to be ultra-dense and heterogeneous not just in terms of the number and type of base stations but also in terms of the number of users and the application types they access. Such a network architecture will require mobility management mechanisms that adapt rapidly to these highly dynamic network characteristics. In particular, the optimality of the handover signaling within these future network architectures will be extremely critical given their density and heterogeneity. In this paper, the optimality is relevant for both the total amount of signaling created and the total delay per handover process. In this paper, we first present a novel and optimized message mapping and signaling mechanism for the handover preparation and failure phases. We also develop a novel handover failure aware preparation signaling methodology, which accounts for the possibility of a handover failure and grants additional enhancements to the handover preparation and failure signaling phases. Through the analytical framework provided in this paper, we conduct studies to quantify the performance gains promised by the proposed mechanisms. These studies cover myriad handover scenarios as identified by 3GPP and use the statistics from cellular network operators and vendors. We then develop the idea and analytical framework for network wide analysis, in which the network wide processing cost and network occupation time for various handover failure rates are computed. Finally, we propose an evolutionary network architecture that facilitates the proposed signaling mechanism as well as assists operators in maintaining a manageable capital expenditure. It combines the current day and 3GPP proposed 5G network architecture with the software-defined networking approach. As a result, we argue that the proposed mechanisms are viable and outperform the legacy handover signaling mechanisms in terms of latency incurred, total network occupation time, number of messages generated, and total bytes transferred.

A Multiobjective Optimization for Train Routing at the High-Speed Railway Station Based on Tabu Search Algorithm

This paper focuses on the train routing problem at a high-speed railway station to improve the railway station capacity and operational efficiency. We first describe a node-based railway network by defining the turnout node and the arrival-departure line node for the mathematical formulation. Both considering potential collisions of trains and convenience for passengers’ transfer in the station, the train routing problem at a high-speed railway station is formulated as a multiobjective mixed integer nonlinear programming model, which aims to minimize trains’ departure time deviations and total occupation time of all tracks and keep the most balanced utilization of arrival-departure lines. Since massive decision variables for the large-scale real-life train routing problem exist, a fast heuristic algorithm is proposed based on the tabu search to solve it. Two sets of numerical experiments are implemented to demonstrate the rationality and effectiveness of proposed method: the small-scale case confirms the accuracy of the algorithm; the resulting heuristic proved able to obtain excellent solution quality within 254 seconds of computing time on a standard personal computer for the large-scale station involving up to 17 arrival-departure lines and 46 trains.

Retrial multi-server queuing system with PHF service time distribution as a model of a channel with unreliable transmission of information

• A multi-server retrial queueing system with unreliable service is analyzed. • The ergodicity condition is derived. • New effective algorithm for computing the stationary distribution of level-dependent AQTMC is developed. • Performance measures of the system are computed. • Numerical results showing advantages of the proposed algorithm are presented. A multi-server retrial queue with a Markovian arrival process , as well as possible customer non-persistency and unreliable operation of servers, is analysed. The service of a customer (transmission of information) consists of a random number of phases. During a transmission, a failure can occur. The failure does not cause server breakdown or its subsequent recovery. The failure occurrence during service of a customer implies either that the departure of the customer from the server (the customer joins an orbit and retries later), the customer re-starts complete service immediately, or the customer resumes the service from the phase at which the failure occurred. The total occupation time of a server by a customer has a so-called PHF (phase-type with failures) distribution. The dynamics of the system are described by a multi-dimensional level-dependent Markov chain . An infinitesimal generator of the chain is derived. To obtain the ergodicity condition, we prove that the Markov chain belongs to the class of asymptotically quasi-Toeplitz Markov chains. Because we consider a multi-server queuing system, the dimensions of the blocks of the generator can be large. Thus, the use of a standard algorithm to find a stationary distribution of an asymptotically quasi-Toeplitz Markov chain can face problems in the stage of computer implementation. We develop a new efficient iterative algorithm for approximate computation of the stationary distribution that computes many times faster and requires much fewer computer resources than the standard algorithm. The advantages of the new algorithm and some features of the model under consideration are numerically demonstrated.

Multi-objective optimization of the integrated problem of location assignment and straddle carrier scheduling in maritime container terminal at import

Maritime terminals need more efficiency in their handling operations due to the phenomenal evolution of world container traffic, and to the increase of the container ship capacity. In this work, we propose a new integrated modeling considering the optimization of maritime container terminals using straddle carriers. The problem is considered at import. We study a combination between two known problems, the first is the storage location assignment problem, and the second is the straddle carrier scheduling problem. This approach, which combines between two chronologically successive problems, leads to the use of multi‐objective optimization. In fact, we study the multi‐objective integrated problem of location assignment and Straddle carrier Scheduling (IPLASS) in maritime container terminal at import. We prove that the problem is NP‐Complete. The objective is to minimize the operating cost which we evaluate according to eight components: the date of last task called makespan, the total vehicle operating time, the total storage bay occupation time, the number of vehicles used, the number of storage bays used, the number of storage locations used, and two different costs of storage location assignment. The location assignment costs are evaluated in order to facilitate the containers transfer for deliveries. We assume that the operating cost is a function of these components and that the influence of each component is variable and dependent on different parameters. These parameters are essentially: the number of quays in the terminal, the straddle carrier traffic layout, the number of container ships to serve in the terminal, the influence of concurrent operations in the terminal, the storage space configuration, the number of free storage bays, the number of free straddle carriers, the number of free quay cranes, the mobility of quay cranes, etc. To solve IPLASS efficiently, we propose an adapted multi‐objective Tabu Search algorithm. Lower‐bound evaluations are introduced to perform approximation of Pareto Front. To explore efficiently the non‐convex Pareto Front Region, we evaluate also a maximized distance adapted to the set of objectives. Indicators of efficiency are developed to propose distinguished solutions to operator. 2D‐projections of approximated Pareto Frontier are given to more understand the efficiency of proposed solutions.

Real-Time Track Reallocation for Emergency Incidents at Large Railway Stations

After track capacity breakdowns at a railway station, train dispatchers need to generate appropriate track reallocation plans to recover the impacted train schedule and minimize the expected total train delay time under stochastic scenarios. This paper focuses on the real-time track reallocation problem when tracks break down at large railway stations. To represent these cases, virtual trains are introduced and activated to occupy the accident tracks. A mathematical programming model is developed, which aims at minimizing the total occupation time of station bottleneck sections to avoid train delays. In addition, a hybrid algorithm between the genetic algorithm and the simulated annealing algorithm is designed. The case study from the Baoji railway station in China verifies the efficiency of the proposed model and the algorithm. Numerical results indicate that, during a daily and shift transport plan from 8:00 to 8:30, if five tracks break down simultaneously, this will disturb train schedules (result in train arrival and departure delays).

Operations scheduling in building tunnels of mining projects

This article proposes a heuristic algorithm to solve a problem of sequencing jobs in the mining tunnel construction, from input data, such as: the number of machines, the number of jobs, the number of stages and the time preparation and operation of the works in each of the stages, with the objective of minimizing the total occupation time processing all stages, resulting in increased operational efficiency of this type of project. The results obtained using the algorithm developed have a total time of occupancy to three jobs with three stages of 39 units of time compare to 59 units of time by an arbitrary solution, thus confirming that it is significant in implementing the algorithm to a problem that exhibits these characteristics.

Asymptotic analysis of risk quantities conditional on ruin for multidimensional heavy-tailed random walks

In this paper we consider a multidimensional renewal risk model with regularly varying claims. This model may be used to describe the surplus of an insurance company possessing several lines of business where a large claim possibly puts multiple lines in a risky condition. Conditional on the occurrence of ruin, we develop asymptotic approximations for the average accumulated number of claims leading the process to a rare set, and the expected total amount of shortfalls to this set in finite and infinite horizons. Furthermore, for the continuous time case, asymptotic results regarding the total occupation time of the process in a rare set and time-integrated amount of shortfalls to a rare set are obtained.

Mapping absorption processes onto a Markov chain, conserving the mean first passage time

The dynamics of a multidimensional system is projected onto a discrete state master equation using the transition rates W(k → k′; t, t + dt) between a set of states {k} represented by the regions {ζk} in phase or discrete state space. Depending on the dynamics Γi(t) of the original process and the choice of ζk, the discretized process can be Markovian or non-Markovian. For absorption processes, it is shown that irrespective of these properties of the projection, a master equation with time-independent transition rates can be obtained, which conserves the total occupation time of the partitions of the phase or discrete state space of the original process. An expression for the transition probabilities is derived based on either time-discrete measurements {ti} with variable time stepping Δ(i + 1)i = ti + 1 − ti or the theoretical knowledge at continuous times t. This allows computational methods of absorbing Markov chains to be used to obtain the mean first passage time (MFPT) of the system. To illustrate this approach, the procedure is applied to obtain the MFPT for the overdamped Brownian motion of particles subject to a system with dichotomous noise and the escape from an entropic barrier. The high accuracy of the simulation results confirms with the theory.

Using Simulated Annealing in a Bottleneck Optimization Model at Railway Stations

The bottleneck section of a railway passenger station is very complex, and many frequent technical and shunting operations are performed over a long time. The connection of station tracks, locomotive depots, and passenger train stock servicing yards also have great effects on the carrying capacity of a railway passenger station. Therefore, there have been many optimization problems in engineering projects and practices. This paper proposes a bottleneck optimization model to enhance the carrying capacity by reasonably arranging routes and groups of turnouts with the consideration of proportionality and minimized total occupation time. The simulated annealing algorithm is provided to solve this programming, and the optimized strategy is given. A case study focused on the bottleneck section optimization in the passenger station of China illustrates the application of the proposed model.

Almost sure finiteness for the total occupation time of an $(d,\alpha,\beta)$-superprocess

For $0<\alpha\leq 2$ and $0<\beta\leq 1$ let $X$ be the $(d,\alpha,\beta)$-superprocess, i.e. the superprocess with $\alpha$-stable spatial movement in $R^d$ and $(1+\beta)$-stable branching. Given that the initial measure $X_0$ is Lebesgue on $R^d$, Iscoe conjectured in [7] that the total occupational time $\int_0^\infty X_t(B)dt$ is a.s. finite if and only if $d\beta < \alpha$, where $B$ denotes any bounded Borel set in $R^d$ with non-empty interior.<br /> <br /> In this note we give a partial answer to Iscoe's conjecture by showing that $\int_0^\infty X_t(B)dt<\infty$ a.s. if $2d\beta < \alpha$ and, on the other hand, $\int_0^\infty X_t(B)dt=\infty$ a.s. if $d\beta > \alpha$.<br /> <br /> For $2d\beta< \alpha$, our result can also imply the a.s. finiteness of the total occupation time (over any bounded Borel set) and the a.s. local extinction for the empirical measure process of the $(d,\alpha,\beta)$-branching particle system with Lebesgue initial intensity measure.

Some properties of superprocesses conditioned on non-extinction

We simply call a superprocess conditioned on non-extinction a conditioned superprocess. In this study, we investigate some properties of the conditioned superprocesses (subcritical or critical). Firstly, we give an equivalent description of the probability of the event that the total occupation time measure on a compact set is finite and some applications of this equivalent description. Our results are extensions of those of Krone (1995) from particular branching mechanisms to general branching mechanisms. We also prove a claim of Krone for the cases of d = 3, 4. Secondly, we study the local extinction property of the conditioned binary super-Brownian motion {Xt, Pµ∞}. When d = 1, as t goes to infinity, Xt/\( \sqrt t \) converges to ηλ in weak sense under Pµ∞, where η is a nonnegative random variable and λ is the Lebesgue measure on ℝ. When d ⩾ 2, the conditioned binary super-Brownian motion is locally extinct under Pµ∞.

The use of “harmonic scalpel” versus “knot tying” for conventional “open” thyroidectomy: results of a prospective randomized study

We evaluated the safety and cost-effectiveness of the harmonic scalpel (HS) during conventional "open" thyroidectomy (CT). Two hundred patients scheduled for conventional total thyroidectomy (TT) were included in the study and randomly assigned to TT with the use of HS (HS group) or with knot tying technique (KT group). Mean operative time was significantly shorter in the HS group (P < 0.001), as well as the total operative room occupation time (P < 0.001). The cost of the disposable materials is significantly higher in the HS group (420.1 +/- 23.2 vs 137.8 +/- 25.3 euros; P < 0.001). Conversely, drugs, personnel and operative room charges were significantly higher in KT group patients (P < 0.001). Overall, no significant difference was found between the two groups concerning the charges of the hospitalisation (P = NS). HS is a safe alternative to KT, allowing for a significant reduction of operative time without increasing complications rate and overall costs and probably better utilization of health resources.

Basic human needs achievement by nursing undergraduate students basic human needs achievement by nursing undergraduate students

The fourteen human basic needs (HBN) described by Henderson define the Nursing care spectrum. It is a nurse duty, regarding the basic human needs, to support and improve the health status, in helping the patient to raise self awareness of the HBN. The present article is the result of a descriptive-exploratory study that aims at evaluating the time that the first year-students of the Nursing course from the Health School of the University of Aveiro - Portugal, spend to satisfy their basic human needs throughout a week. An exploratory study was developed based on a quantitative approach. For data collection, a diary instrument built of seven record sheets for registering of the student time was elaborated. By the data analyses, it was concluded that students had spent more time to sleep, resting and learning, reaching 60,06% of the weekly total occupation time. Although variations in the time spent for the satisfaction of the diverse needs throughout the week do exist, those are not significant. The need to prevent harm and to follow according to beliefs and values were the ones that students had spent less time.

Heuristics for scheduling in a no-wait open shop with movable dedicated machines

In this paper, we address a scheduling problem related to people's livelihood, such as road construction works that include laying pipes for gas, water and phone. The problem is a multi-processing-stage open shop with the characteristics of movable dedicated machines and no-wait restriction, also known as no intermediate queue. The objective is to schedule the jobs such that the total occupation time for all the processing stages is minimized. Some two-phase heuristic algorithms are proposed for solving the problem. Computational results show that the heuristic is fairly effective in finding an optimal or a near-optimal solution for small-sized problems. Results of the heuristic for experiments tallied with the real-life environment demonstrate the potential of the heuristic to efficiently deal with the scheduling problems.

Basic human needs achievement by nursing undergraduate students basic human needs achievement by nursing undergraduate students

The fourteen human basic needs (HBN) described by Henderson define the Nursing care spectrum. It is a nurse duty, regarding the basic human needs, to support and improve the health status, in helping the patient to raise self awareness of the HBN. The present article is the result of a descriptive-exploratory study that aims at evaluating the time that the first year-students of the Nursing course from the Health School of the University of Aveiro - Portugal, spend to satisfy their basic human needs throughout a week. An exploratory study was developed based on a quantitative approach. For data collection, a diary instrument built of seven record sheets for registering of the student time was elaborated. By the data analyses, it was concluded that students had spent more time to sleep, resting and learning, reaching 60,06% of the weekly total occupation time. Although variations in the time spent for the satisfaction of the diverse needs throughout the week do exist, those are not significant. The need to prevent harm and to follow according to beliefs and values were the ones that students had spent less time.

Valleys and the Maximum Local Time for Random Walk in Random Environment

Let ξ (n, x) be the local time at x for a recurrent one-dimensional random walk in random environment after n steps, and consider the maximum ξ*(n) = max x ξ(n, x). It is known that lim sup $$_n\xi^*(n)/n$$ is a positive constant a.s. We prove that lim inf $$_n(log\!!!log\!!!log\!!!n) \xi^*(n)/n$$ is a positive constant a.s. this answers a question of P. Révész [5]. The proof is based on an analysis of the valleys in the environment, defined as the potential wells of record depth. In particular, we show that almost surely, at any time n large enough, the random walker has spent almost all of its lifetime in the two deepest valleys of the environment it has encountered. We also prove a uniform exponential tail bound for the ratio of the expected total occupation time of a valley and the expected local time at its bottom.

A new approach to the single point catalytic super-Brownian motion

A new approach is provided to the super-Brownian motionX with a single point-catalyst δc as branching rate. We start from a superprocessU with constant branching rate and spatial motion given by the 1/2-stable subordinator. We prove that the occupation density measure λc ofX at the catalystc is distributed as the total occupation time measure ofU. Furthermore, we show thatXt is determined from λc by an explicit representation formula. Heuristically, a mass λc(ds) of “particles” leaves the catalyst at times and then evolves according to Ito's Brownian excursion measure. As a consequence of our representation formula, the density fieldx ofX satisfies the heat equation outside ofc, with a noisy boundary condition atc given by the singularly continuous random measure λc. In particular,x isC outside the catalyst. We also provide a new derivation of the singularity of the measure λc.