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In concurrent object models, objects encapsulate local state, schedule local processes, interact via asynchronous method calls, and methods of different objects are executed concurrently. In this paper, we introduce a compositional trace semantics for concurrent objects and provide an axiomatic characterization of the general properties of reachable traces, that is, traces that can be generated by a concurrent object program. The main result of this paper is a soundness and completeness proof of the axiomatic characterization.

Modern database-management systems permit the isolation level to be set on a per-transaction basis. In such a mixed-level setting, it is important to understand how transactions running at different levels interact. More fundamentally however, these levels are sometimes of different scopes. For example, READ COMMITTED and REPEATABLE READ are of local scope, since the defining properties depend upon only the transaction and its relationship to those running concurrently. On the other hand, SERIALIZABLE is of global scope; serializability is a property of a schedule of transactions, not of a single transaction. In this work, in addition to formalizing the interaction of transactions at different levels, the meaning of serializability within local scope is also addressed.

In traffic-management system (TMS) for existing lines of a metropolitan area, there was a limit in the control of a large station in the centralized TMS based on the conventional CTC (centralized traffic control). In the case of TMS, all information is gathered and judged based on train schedule, namely train diagram and traintracking data, in the center, and is controlled via CTC. For this reason, it is difficult to control all stations in a metropolitan area, which have many large stations, making introduction of the system difficult. Development to resolve this big issue was done in the Tokyo autonomous decentralized transport operation control system (ATOS). It is a total system that carries out transport operation control and signal control of the existing 24 lines in the Tokyo metropolitan area. It is the largest system in the world, covering complex and high-density operations of existing lines (minimum headway of about 2 min). Its features are as follows: (1) Including the electronic interlocking system into the transport operation control system, constituting an ATOS that arranges the diagram and route-control function at the station. This makes automatic control of line with complex large stations possible. (2) Even when the diagram is disturbed by any accident, it is a system that can quickly recover the diagram by the operation adjustment function that the operator can operate with the diagram-based operation*. (3) When the concept of new interlocking logic which integrates maintenance work management function was considered, the management of occupancy information of track was adopted to interlocking logic by the method of exclusively controlling this track occupancy information. (4) By adopting autonomous decentralized system (ADS), online testing of the system and step by step system construction of the system became possible, it became easier to construct a large scale system step by step and to partially replace. In this way, ATOS contributes greatly to the system construction of large-scale and complicated line sections.

A block replacement schedule can be optimized simultaneously with a spare parts ordering schedule, since all items are replaced at a constant interval. The solution of joint optimization for spare parts ordering time and block replacement gives lower costs compared to separate optimization of ordering time and replacement time. The spare parts for replacement can be classified as stochastic demand for failure replacement and deterministic demand for block replacement. In this paper, we propose a simulation model for a separate spare parts ordering schedule. The solution was compared to the solution for a model with common spare parts for both failure and block replacement. The system has N identical components, each with a Weibull lifetime distribution. The costs of failure and block replacements, and also the costs of ordering, holding and shortage of spare parts are given. The proposed model was shown to perform better than the common order model. Also, compared to the age replacement model, the solution of the proposed model is relatively similar, yet the economies of scale would be an advantage for the block replacement over age replacement.

We consider a sequential inspection game where an inspector uses a limited number of inspections over a larger number of time periods to detect a violation (an illegal act) of an inspectee. Compared with earlier models, we allow varying rewards to the inspectee for successful violations. As one possible example, the most valuable reward may be the completion of a sequence of thefts of nuclear material needed to build a nuclear bomb. The inspectee can observe the inspector, but the inspector can only determine if a violation happens during a stage where he inspects, which terminates the game; otherwise the game continues. Under reasonable assumptions for the payoffs, the inspector's strategy is independent of the number of successful violations. This allows to apply a recursive description of the game, even though this normally assumes fully informed players after each stage. The resulting recursive equation in three variables for the equilibrium payoff of the game, which generalizes several other known equations of this kind, is solved explicitly in terms of sums of binomial coefficients. We also extend this approach to non-zero-sum games and, similar to Maschler (1966), "inspector leadership" where the inspector commits to (the same) randomized inspection schedule, but the inspectee acts legally (rather than mixes as in the simultaneous game) as long as inspections remain., final version for Mathematics of Operations Research, new Theorem 2

Context: Inconsistency detection and resolution is critical for context-aware applications to ensure their normal execution. Contexts, which refer to pieces of environmental information used by applications, are checked against consistency constraints for potential errors. However, not all detected inconsistencies are caused by real context problems. Instead, they might be triggered by improper checking timing. Such inconsistencies are ephemeral and usually harmless. Their detection and resolution is unnecessary, and may even be detrimental. We name them inconsistency hazards.Objective: Inconsistency hazards should be prevented from being detected or resolved, but it is not straightforward since their occurrences resemble real inconsistencies. In this article, we present SHAP, a pattern-learning based approach to suppressing the detection of such hazards automatically.Method: Our key insight is that detection of inconsistency hazards is subject to certain patterns of context changes. Although such patterns can be difficult to specify manually, they may be learned effectively with data mining techniques. With these patterns, we can reasonably schedule inconsistency detections.Results: The experimental results show that SHAP can effectively suppress the detection of most inconsistency hazards (over 90%) with negligible overhead.Conclusions: Comparing with other approaches, our approach can effectively suppress the detection of inconsistency hazards, and at the same time allow real inconsistencies to be detected and resolved timely.

The aim of the study is to implement bar coding system as mechanism for the PUP ECE Laboratory Transaction recording and monitoring. The study was concerned on proper documenting and managing the daily transaction of the ECE Laboratory particularly to automate the existing manual mechanism procedure with the proposed AutoLab System. The study used QuasiExperimental method as it included both experimental and descriptive method to gather data for the study. Experimental in a way that the system was subjected to series of experiments to test its accuracy, efficiency, effectiveness and reliability using the singlegroup design. Two main experiments have been conducted the test for accuracy of the system in transaction recording and the equipment inventory monitoring. Test for accuracy was divided into four parts namely (1) Borrowing of Key; (2) Borrowing of Equipment; (3) Returning of Keys; and, (4) Returning of Equipment. On the other hand, the equipment inventory monitoring incorporates the analysis of the equipment utilization; from such as what equipments are usually borrowed, in what subjects a certain equipment is being used and the history of usage for a given equipment. The descriptive part was used to evaluate the system in three variables the Graphical User Interface, the Accuracy of Information displayed and the Transaction Recording duly rated from scales 1 to 5; 5 being the highest through survey among the ECE students and faculty members. The ECE Room Utilization Log Book, ECE Transaction Log Book and the Borrower’s Slips have been analyzed to assess the existing transaction recording and inventory monitoring. Results showed that the AutoLab System effectively automated the recording of transactions merging the existing manual method into one recording mechanism. Manual transaction recording cannot provide a 100% effectivity since there were percentages of 9.39% of the 2300 ECE Room Utilization Log Book transactions, 41.38% of the 742 Borrower’s Slip transactions and 45.94% of the 603 ECE Transactions Log Book entries that were analyzed. A 100% complete data being filled-out on the ECE Borrower’s Slip and the ECE Transactions Log Book permits a more comprehensive study of equipment inventory monitoring which gives a detailed room utilization for the ECE Room Utilization Log Book. The Automated Laboratory coined as AutoLab merged the ECE Room Utilization Log Book, ECE Borrower’s Slip and the ECE Transaction Log Book into one complete package in terms of transaction recording and equipment inventory monitoring incorporating four databases– the class list, the room utilization, the class schedule and the equipments. As PUP Student Identification Cards have bar codes that embed the student number, the system utilized the information to extract details regarding the identity of the student necessary for transaction and equipment inventory monitoring. Two hundred sixty seven (267) ECE students from the 1142 ECE student population and 19 ECE Faculty Members served as respondents for the study. The respondents assessed the system in three areas – the Graphical User Interface (GUI), the Accuracy of Information Displayed and the Transaction Recording. Respondents rated the GUI in terms of design, user friendliness, minimal amount of time to perform its function and reliability. Overall rating of the system in terms of design was 4.22 (Effective); user friendliness was 4.50 (Effective); minimal amount of time to perform function was 4.51 (Highly Effective) and reliability to be 4.50(Effective). In terms of the Accuracy of Information Displayed, the overall assessment for accuracy of reading of student Identification card was 4.72 (Highly Effective), accuracy of information being displayed was 4.71 (Highly Effective), accuracy of reading for room key to be 4.74 (Highly Effective) and equipment with 4.75 (Highly Effective). Overall rating of the system in terms of recording of borrower’s information as 4.72 (Highly Effective), recording of key 4.71(Highly Effective), recording of equipment 4.68(Highly Effective) and updating of record to be 4.70 (Highly Effective). The result from the faculty and student respondents were subjected to T-test analysis to determine whether there is a significant difference between their assessments. Result have shown that there was no significant difference between student and faculty assessment.

Software transactional memory (STM) is a transactional mechanism of controlling access to shared resources in memory. This transactional mechanism is similar to the abort-and-restart execution model in a functional reactive system (FRS). Due to its abort-and-restart nature, the execution semantics of STM are different from the classic preemptive or nonpreemptive model. Some research has strong constraints for its worst case response time (WCRT) analysis. In this paper, we research on worst case response time and schedulability analysis for real-time software transactional memory-lazy conflict detection (STM-LCD). Specifically, we introduce a parameter the remainder factor m , formally derive an exact WCRT for a 2-task set on STM systems using lazy conflict detection (LCD), propose an exact schedulability test for a 2-task set. Also, we present a near-exact WCRT for an n -task set on STM-LCD, and propose a new necessary condition and a new sufficient condition to schedule an n -task set. Finally, we show that experimental results are accordant with the aforementioned analysis.

BACKGROUND As part of ongoing perioperative surgical home implantation process, we applied a previously published algorithm for creation of a maximum surgical blood order schedule (MSBOS) to our operating rooms. We hypothesized that using the MSBOS we could show a reduction in unnecessary preoperative blood testing and associated costs. STUDY DESIGN AND METHODS Data regarding all surgical cases done at UC Irvine Health's operating rooms from January 1, 2011, to January 1, 2014 were extracted from the anesthesia information management systems (AIMS). After the data were organized into surgical specialties and operative sites, blood order recommendations were generated based on five specific case characteristics of the group. Next, we assessed current ordering practices in comparison to actual blood utilization to identify potential areas of wastage and performed a cost analysis comparing the annual hospital costs from preoperative blood orders if the blood order schedule were to be followed to historical practices. RESULTS Of the 19,138 patients who were categorized by the MSBOS as needing no blood sample, 2694 (14.0%) had a type and screen (T/S) ordered and 1116 (5.8%) had a type and crossmatch ordered. Of the 6073 procedures where MSBOS recommended only a T/S, 2355 (38.8%) had blood crossmatched. The cost analysis demonstrated an annual reduction in actual hospital costs of $57,335 with the MSBOS compared to historical blood ordering practices. CONCLUSION We showed that the algorithm for development of a multispecialty blood order schedule is transferable and yielded reductions in preoperative blood product screening at our institution.

Time pressure is not usually seen as an advantage in front end innovation (subsequently referred to as “FEI”), but rather it is believed that ideas should be left to develop freely without a tight schedule. Instead of strictly formalized operations, creating ideas generally necessitates a certain level of freedom. The starting point for this research was to challenge this general view by imposing severe time pressure in FEI. The FEI process was reviewed from recognizing problems/creating ideas up until the selection of the best concept for further development. The research was executed as a qualitative in-depth investigation of a case. In the case, FEI took place over a three-week period, and the target for the FEI was to generate concepts of digital jewelry with business potential. The time pressure was seen as appropriate – with certain conditions – in FEI. The results also present the advantages and disadvantages of time pressure, combining it to the stress theory.

In this paper, we address daily reading practices of the general public in Russia analyzing 10 months of log data from the commercial ebook site Bookmate. We study different reading characteristics with ebooks, i.e. the reading volume and preferences, reading schedule, reading speed and reading style (including parallel reading patterns and book abandonment rates), with respect to reader gender, book length and genre of the book. We find that book genres impact certain reading behaviors, while gender differences or book length seem to play less of a role in ebook reading. Parallel book reading and book abandonment occur very frequently, possibly pointing towards changing reading behaviors in the ebook environment. The obtained insights demonstrate the high potential of log analysis for book reading studies.

Background Fewer than 25 simultaneous heart-liver-kidney transplants (SHLKTxs) have been performed in the U.S. This highly complex operation was performed nine times by only four centers from 2018 to 2019. However, one institution, the University of Chicago Medical Center (UCMC), is responsible for two-thirds of all SHLKTxs performed in that period. There is a paucity of literature regarding the logistics and infrastructure of performing SHKLTxs. The development of a standardized, effective protocol would improve outcomes in the high-risk patients who undergo this operation. We assessed the unique strategies that this center employs to successfully perform a high volume of SHLKTxs to understand possible programmatic procedures. Methods We reviewed the logistical methods and infrastructure of the UCMC concerning the process of SHLKTx, spanning the stages from patient selection to operating room (OR) management. Additionally, we attempted to identify areas of future improvement. Results The UCMC employs strict patient selection criteria, as potential candidates must meet the listing criteria for each organ independently. The severity of illness, however, must also indicate the potential for a successful outcome, and the age limit for candidates is typically 60 years. Donor selection and organ allocation are critical to ensure that all organs are received from the same donor, which can require negotiation when the procurement is not in a local area. The technically challenging surgery requires the transplant teams to move quickly in order to minimize ischemic time for the heart and prevent reperfusion injury in the liver, while the kidney is perfused. Due to the risk of these events, the transplant team recommends the use of mechanical support, such as extra-corporeal membrane oxygenation (ECMO). The key element of the UCMC's success was found to be the team's ability to procure and achieve success with organs that many other centers would turn down. The team is willing to accept undersized hearts, travel further distances, use DCD organs, and transplant Hepatitis C seropositive non-viremic (HCV Ab+/NAT-) livers to an HCV seronegative recipient in pursuit of an expeditious and successful SHLKTx. The combined efforts of a skilled, multidisciplinary team are also essential. The various teams see the patients together in a structured rounding schedule, and the operation itself consists of three distinct phases with choreographed and planned handoffs. Areas identified for future improvement included standardizing the approach used in the OR, particularly team transfer and timing. Conclusion The UCMC owes its established track record of successful SHLKTxs to the internal infrastructure of its program. In particular, its willingness to accept organs that other centers refuse allows it to perform a high volume of expeditious and successful SHLKTxs. Future steps include protocolizing OR management along with identifying parameters that allow for a structured system of team transfer.

The act of retrieval yields benefits for memory. However, according to the reconsolidation account, reactivation could render a memory amenable to modifications. The present study investigated how the retrieval frequency of a previously learned vocabulary list and the temporal distance of a subsequently encoded list affected retention of the prior list. Recruited from six intact sessions of a college intensive English course, participants learned two unrelated lists of novel words and took cued-recall tests. The results revealed an interaction between the retrieval of list 1 (single vs. repeated) and the encoding of list 2 (close vs. far vs. no). Noteworthy, the repeated-retrievals groups outperformed single-retrieval groups only when list 2 encoding was spaced far apart (i.e., 3-day interval). The memory impairment effect emerged in the presence of list 2 whereas the memory strengthening effect occurred in the absence of list 2. These results suggest that the interplay between repeated retrievals and an extended temporal distance functions in a way that may attenuate memory’s susceptibility to new learning rather than abolish it. Situated in the naturalistic classroom setting, these findings have pedagogical significance for instructors to schedule testing and learning sessions to help learners optimize vocabulary retention.

In the present paper, we investigate a preventive replacement policy based on multiple attributes. A system is subject to two types of shocks which arrive according to a non-homogeneous Poisson process. Type 1 shocks are minor and cause a random amount of damage to the system. We use a minimal repair to fix type 1 shock. Type 2 shocks are catastrophic and the system is correctively replaced at its occurrence. The probabilities of type 1 shock and type 2 shock are assumed to depend on age. A system fails (in a catastrophic failure type) once the cumulative damage reaches a failure level K or a type 2 shock happens. In addition, the system with cumulative damage of level z may fail (in a minor failure type) with probability ω z at each type 1 shock occurrence and be rectified by a minimal repair. A replacement policy based on nature of failure, cumulative damage, system age and number of type 1 shocks is formulated. Under this policy, preventive replacement is made before catastrophic failure when the age of the system reaches T or the number of occurrences of type 1 shock achieves N or the accumulative damage exceeds a level Z but less than K, whichever occurs first, and corrective replacement is immediately carried out whenever the catastrophic failure of the system happens. We determine the optimum preventive replacement schedule such that the expected cost per unit time is minimized. The proposed model extends many existing models since the framework and analysis are general. Finally, the numerical example is provided.

Tax evasion is an illegal practice where a person or a business entity intentionally avoids paying his/her true tax liability. Any business entity is required by the law to file their tax return statements following a periodical schedule. Avoiding to file the tax return statement is one among the most rudimentary forms of tax evasion. The dealers committing tax evasion in such a way are called return defaulters. In this paper, we construct a logistic regression model that predicts with high accuracy whether a business entity is a potential return defaulter for the upcoming tax-filing period. For the same, we analyzed the effect of the amount of sales/purchases transactions among the business entities (dealers) and the mean absolute deviation (MAD) value of the first digit Benford's law on sales transactions by a business entity. We developed this model for the commercial taxes department, government of Telangana, India.

The article has been withdrawn on the request of the editor of the journal, Current Drug Targets. Bentham Science apologizes to the readers of the journal for any inconvenience this may have caused. Bentham science disclaimer Articles in Press (articles that have been accepted for publication or published as E-pub Ahead of Schedule but which have not been formally published with volume/issue/page information) that include errors, or are determined to violate the publishing ethics guidelines such as multiple submission, fake claims of authorship, plagiarism, fraudulent use of data or the like, maybe “Withdrawn” from the journal. Withdrawal means that the article files are removed and replaced with a PDF stating that the article has been withdrawn from the journal in accordance with BSP Editorial Policies.

Understanding the runtime behavior of concurrent programs is a challenging task. A popular approach is to establish a happens-before relation via vector clocks. Thus, we can identify bugs and performance bottlenecks, for example, by checking if two conflicting events may happen concurrently. We employ a two-phase method to derive vector clock information for a wide range of concurrency features that includes all of the message-passing features in Go. The first phase (instrumentation and tracing) yields a runtime trace that records all events related to message-passing concurrency that took place. The second phase (trace replay) is carried out of fline and replays the recorded traces to infer vector clock information. Trace replay operates on thread-local traces. Thus, we can observe behavior that might result from some alternative schedule. Our approach is not tied to any specific language. We have built a prototype for the Go programming language and provide empirical evidence of the usefulness of our method.

As we saw in the previous chapter, it's very straightforward to construct LCC call-marks. In most cases, the subject part of the call-mark is lifted from the schedule without any alteration. The only real intellectual work for the classifier is the creation of the Cutter number, deciding whether it should be for the author or for another aspect of the work, and contriving a number that will fit in with the existing sequence. Very often, even this isn't required, as LCC is so fond of lists that it offers thousands of ready-made subject Cutters. There are, however, some areas where more detail can be achieved by a limited sort of number building, and you normally do this by using tables. Tables in LCC LCC is quite unlike any other classification in its use of tables. In most schemes you would expect to find commonly occurring concepts, such as place, time or form, provided for in a general table to be used throughout the system. This is what happens in DDC and UDC, and of course has its equivalent in LCSH in the free-floating subdivisions. In LCC every table is special to the place where it is applied. Even where a table is used frequently in a particular main class (as happens in Class H, Social sciences) it can still be used only where the instructions permit. For example, in the part of the schedule shown in Figure 16.1, Table 21 can be used to expand the classes for Bisons (sic), Edible birds’ nests, Edible caterpillars, Edible snails and Kangaroos, but Table 23 must be used for Goats. You can't use a table to expand Rabbits since there is no instruction to do so, but some enumerated classes are provided. This means that adding notation from tables is a laborious business since there is no single consistently used table for common concepts, nor is there any mnemonic value in the notation, since it hardly ever remains the same in two different classmarks. In the online version of LCC the tables are very easy to use: when you click on the link to a table it pops up and inserts itself into the schedule, working out the numbers for you.

Currently, The unprecedented increasing of mobile data traffic challenges the performance of current cellular networks. To meet this explosive demands of mobile traffic, the mobile data offloading technology has been proposed to alleviate the traffic load by moving traffic load of cellular networks to other wireless networks provided by infrastructures such as small-cell base stations. In this work, an infrastructure-free offloading method is proposed, which realizes the data transaction among mobile users by applying the hotspot function of smartphones. In this transaction, mobile users with redundant data perform as accessible Wi-Fi hotspots, and sell their mobile data to users with data requirements. Considering the scenarios with multiple data sellers, a networked auction model is introduced to model the process of data transaction. Additionally, high efficient data allocation mechanisms are designed in this work, which decide how to schedule the data transaction in different time slots, based on the establish edauction model. Simulation results indicate that introducing the prediction information of user behaviors can effectively improve the performance of data allocation, and achieve a high efficient data transaction operation.

This work addresses the need for efficient key-range validation for a composite OLTP and bulk processing workload characterized by modern enterprise applications. In-memory database system (IMDB), mostly adopting the optimistic concurrency control (OCC) mechanism, performs well if the contention of conventional OLTP workloads is low and each transaction only contains point read/write query with primary key. In this work we present the performance problem of IMDBs under mixed OLTP and bulk processing workloads. The reason is that existing OCC protocols take expensive cost to generate a serializable schedule if the OLTP workload contains bulk processing operations with key-range scan. To this end, we develop an efficient and scalable range optimistic concurrency control (ROCC) which uses logical ranges to track the potential conflicting transactions and to reduce the number of transactions to be validated. At the read phase, a transaction keeps a set of predicates to remember the version and precise scope of scanned ranges, which eliminates the cost of maintaining scanned records. Before entering the validation phase, if the transaction intends to update records in the logical range, it needs to register to the corresponding lock-free list implemented by a circular array. Finally, ROCC filters out unrelated transactions and validates the bulk operation at range level. Experimental results show that ROCC has good performance and scalability under heterogeneous workloads mixed with point access and bulk processing.

Wedding Organizer is a service that works personally to help bride and groom in planning and supervision of the implementation of the wedding party in accordance with schedule and bugdet that have been set. Wedding organizer information system created using web-based information technology, with the aim to expand the area of promotion and sale of wedding packages and simplify the ordering process . System Design Information Ordering Wedding Organizer is UML modeling visualization (Unified Modeling Language) by using some object-oriented visualization diagram. The programming language used is the PHP programming language (PHP Hypertext Preprocessor) based on the Laravel framework as well as Javascript, with MySQL as the Database Management System (DBMS), and Atom as an editor. Wedding organizer information system is very helpful for people who do not want to bother with their wedding planning issues. With the development of technology today, wedding Organizer has begun to move from the manual process into the online process of wedding information system-based organizer web. Keywords: Information System , booking Wedding Organizer , web, Laravel

Enterprises have paid attention to blockchain (BC), recently permissioned BC characterized with smart-contract, where busi-ness transactions among inter-authorized companies (forming consortium) can automatically be executed based on distributed consensus protocol over user-defined business logics pre-built with program codes. A single BC system will be built across mul-tiple management domains having different operational policies, e.g., datacenter of each organization; this will trigger a problem that its system operations (e.g., backup) will become time-consuming and costly due to the difficulty in unifying and/or adjusting operational policy, schedule, etc. Toward solving the problem, we propose an operations execution method for BC systems; a primary idea is to define operations as smart-contract so that unified and synchronized cross-organizational operations can be executed effectively by using BC-native features. We de-sign the proposed method as hybrid architecture including in-BC consensus establishment and out-BC event-based instruction execution, in order to be adaptable to the recent heterogeneous BC architecture. Performance evaluation using a prototype with Hyperledger Fabric v1.0 shows that the proposed method can start executing operations within 5 seconds. Furthermore, cost evaluation using model-based estimation shows that the total yearly cost of monthly operations on a 5-organizational BC sys-tem could be reduced by 61 percent compared to a conventional manual method.

The consensus number of a synchronization primitive is the maximum number of processes for which the primitive can solve consensus. This has been the traditional measure of power of a synchronization primitive. Thus, the compare-and-swap primitive, which has infinite consensus number, is considered most powerful and has been the primitive of choice for implementing concurrent data structures. In this work, we show that the synchronization primitives with low consensus numbers can also be potentially powerful by using them along with the compare-and-swap primitive to design an O (√n) time wait-free and linearizable concurrent queue. The best known time bound for a wait-free and linearizable concurrent queue using only the compare-and-swap primitive is O(n). Here, n is the total number of processes that can access the queue.The queue object maintains a sequence of elements and supports the operations enqueue(x) and dequeue(). The wait-free property implies that every call to enqueue(x) and dequeue() finishes in a bounded number of steps irrespective of the schedule of other n --1 processes. The linearizable property implies that the enqueue(x) and dequeue() calls appear to be instantaneously applied within the duration of respective calls. We design a wait-free and a linearizable concurrent queue using shared memory registers that support the compare-and-swap primitive and two other primitives of consensus number one and two respectively. The enqueue(x) and dequeue() operations take O (√n) steps each. The total number of registers required are O(nm) of O (max{log n, log m }) bits each, where m is a bound on the total number of enqueue(x) operations.

In-memory transaction processing has gained fast development in recent years. Previous works usually assume the one-shot transaction model, where transactions are run as stored procedures. Though many systems have shown impressive throughputs in handling one-shot transactions, it is hard for developers to debug and maintain stored procedures. According to a recent survey, most applications still prefer to operate the database using the JDBC/ODBC interface. Upon realizing this, the work targets on the problem of interactive transaction processing for in-memory database system. Our key contributions are: (1) we address several important design considerations for supporting interaction transaction processing; (2) a coroutine-based execution engine is proposed to handle different kinds of blocking efficiently and improve the CPU usage; (3) a lightweight and latch-free lock manager is designed to schedule transaction conflicts without introducing many overhead; (4) experiments on both the TPC-C and a micro benchmark show that our method achieves better performance than existing solutions.

There are a number of definitions for delay: (1) something that happens later than expected; (2) something that is performed later than planned; and (3) an action that is not timely. Each of these definitions can describe a delay to an activity of work in a schedule. On construction projects, it is not uncommon for delays to occur. It is what is being delayed that determines if a project or some other deadline, such as a milestone, will be completed late. Before any discussion of delay analysis can begin, a clear understanding of the general types of delays is necessary.

Synchronous languages have been introduced as programming languages that directly reflect the nature of reactive systems: Their execution is divided into discrete reaction steps such that in each reaction step, inputs are read from the environment and outputs are instantaneously computed. Reaction steps, which are also called macro steps, consist thereby of a set of atomic micro step actions that are executed in the variable environment associated with the macro step. At the beginning of the macro step, only the values of the input variables are known in this variable environment, and the values of the remaining variables have to be computed according to the data-dependencies. Since the micro step actions depend on the variable environment that they also create, it might be the case that there are cyclic dependencies. Whether such cyclic dependencies can be constructively resolved has to be checked by a compile-time causality analysis which will ensure that there is for all inputs a suitable schedule of the micro steps. If the synchronous programs are converted to guarded actions as done in the author’s Averest system, some relationships with logic programs can be found: In particular, the concepts of reaction-to-absence of synchronous languages and negation-to-failure of logic programs seem to be the same; another analogy is found for the generation of equation-based code of synchronous programs and the completion of logic programs, and also for the fix-point analyses defined in both paradigms. This paper outlines these analogies between the two paradigms of programming languages and discusses whether further known semantics of logic programs like well-founded and stable models may find useful counterparts in the synchronous world in future.

In this paper, we present a very fast and simple protocol for polling tags in an RFID system formed by one or more readers, and a multitude of tags. Actually, the protocol is time-optimal for single reader systems, while being very fast for multiple readers systems. The main idea of the protocol described in this paper, is to associate a short and unique number (called “nickname” in the following) to each tag in the reader’s range, and by using such nicknames as the polling order. We first describe the single reader version of the protocol. For this version, the used nicknames are the integers 1 , 2 , … , n if the set of tags to be polled is formed by n tags. They can be seen as the time slot in which a tag has to communicate with the reader. We also provide a procedure to assign a nickname for a new tag, as well as a way to delete a tag from the polling order, while keeping the above consecutivity property about nicknames. When polled, the tags transmit a proper (usually short) message. Polling protocols, sometime with little changes, sometime with no change, can be efficiently used for solving several practical problems related to the use of RFID systems. Some of the most prominent ones, and those considered in this paper, are the problems of exactly determine missing tags, the collection of information associated to the tags, the probabilistic determination of missing tags (useful for raising a warning), and the determination of the presence of cloned tags, again for raising a proper warning. We formally show that the protocol is time-optimal. Besides, the protocol is privacy preserving since tags ID’s are never transmitted during the polling procedure. In the protocol version for large, multireader RFID systems, we take an approach completely different from that used so far for any multireader protocol. Up to now, in the proposed protocols for this and related problems, first readers are scheduled so that those with overlapping ranges never operate at the same time. Then, single reader protocol for each so scheduled reader are applied. Here, we schedule the tags instead of the readers so that tags whose transmission can be received by a common reader, never operate at the same time. Then, we show that our polling protocol for single reader systems can be effectively used along with such a tags scheduling strategy, in multireader systems. The time performance improvement of our protocol over the known ones for multireader systems is very large, going from two to seven times, as shown by a simulation experiment we set up, and whose results are also presented.

Doodle polls allow people to schedule meetings or events based on time preferences of participants. Each participant indicates on a web-based poll form which time slots they find acceptable and a time slot with the most votes is chosen. This is a social choice mechanism known as approval voting, in which a standard assumption is that all voters vote sincerely—no one votes “no” on a time slot they prefer to a time slot they have voted “yes” on. We take a game-theoretic approach to understanding what happens in Doodle polls assuming participants vote sincerely. First we characterize Doodle poll instances where sincere pure Nash Equilibria (NE) exist, both under lexicographic tie-breaking and randomized tie-breaking. We then study the quality of such NE voting profiles in Doodle polls, showing the price of anarchy and price of stability are both unbounded, even when a time slot that many participants vote yes for is selected. Finally, we find some reasonable conditions under which the quality of the NE (and strong NE) is good.

It can be difficult for people to keep a secret at the best of times, and this is particularly true in the world of cyber-security. The whole industry rests on secrets, but some of them must be disclosed to make the user community safer. Disclosure of security flaws is a complicated and tense process, both for the researchers that discover them, and for the vendors that must fix them. Approaches range from full disclosure, where everything is made open immediately, through to fair disclosure, where information is made available on an agreed schedule. There are many nuances in between. Danny Bradbury explores the continuum of disclosure, and analyses some strengths and weaknesses along the way.

College students must regulate much of their learning and hence it is important to discover whether they use effective study techniques, such as testing with feedback. We conducted three experiments to evaluate the degree to which college students use testing with feedback as they are learning key concept definitions. The three main issues of interest concerned (a) whether students tested themselves during practice, (b) whether they followed tests with feedback, and (c) whether they continued to practice until they could correctly recall each definition one or more times. In each experiment, students in the self-regulated group could choose to engage in three activities (test, study, or evaluate test responses) in whatever order or dosage they wanted during practice. For purposes of comparison in each experiment, a Criterion 3 group completed an experimenter-controlled schedule of test-study practice until each definition was correctly recalled three times. All participants completed a final test one week later. Among the key outcomes, students who self-regulated their learning used tests and often sought feedback soon after. When students incorrectly recalled a definition, they typically chose to study the definition, whereas when they recalled some of a definition correctly, they typically chose to evaluate the quality of their response. Although students on average continued to test themselves until they correctly recalled each definition once, they underperformed on the final test as compared to the Criterion 3 group. Thus, in the present context, students do use testing while learning, but results also suggest that they do not take full advantage of this effective study technique.

The various stages of the separation are carefully planned but despite this, variations which will change the schedule of the procedure may exist. In general the operation commences on the opposite side from the main procedure and then the twins are turned for the remainder of the operation. Each type of conjoined twin is different but basically thoracopagus involves the hearts, omphalopagus involves the liver and small intestine and ischiopagus involves the large intestine and genito-urinary system. Our results are presented together with interesting cases from which lessons have been learned.

Microfluidic-based biochips are replacing the conventional biochemical analyzers, and are able to integrate all the necessary functions for biochemical analysis. The digital microfluidic biochips are based on the manipulation of liquids not as a continuous flow, but as discrete droplets. Several approaches have been proposed for the synthesis of digital microfluidic biochips, which, starting from a biochemical application and a given biochip architecture, determine the allocation, resource binding, scheduling, placement and routing of the operations in the application. Researchers have assumed that each biochemical operation in an application is characterized by a worst-case execution time (wcet). However, during the execution of the application, due to variability and randomness in biochemical reactions, operations may finish earlier than their wcetswcets, resulting in unexploited slack in the schedule. In this paper, we first propose an online synthesis strategy that re-synthesizes the application at runtime when operations experience variability in their execution time, exploiting thus the slack to obtain shorter application completion times. We also propose a quasi-static synthesis strategy that determines offline a database of alternative implementations. During the execution of the application, several implementations are selected based on the current execution scenario with operation execution time variability. The proposed strategies have been evaluated using several benchmarks and compared to related work.

Heuristic algorithms are developed to solve the parallel-machine job-shop problems , where the criterion is the minimisation of the makespan, , or the sum of completion times, . The developed algorithms include sequencing and assigning stages. At the sequencing stage, the job-shop problem is solved, where job is available for processing from time . The problem is modelled by a mixed graph , where the vertices are the operations to be processed. The precedence constraints on the set are determined by the arc set . The resource constraints are determined by the edge set . In order to resolve a conflict arising between two operations processed on the same machine, the algorithm should substitute a conflict edge from the set by an arc incident to the same vertices from the set . The resulting digraph determines a heuristic solution to the problem , where all machines are different. The digraph determines a semi-active schedule for the problem . A mixed graph model is used for solving the problem , which allow...

Background: Recently, operation technology and health care environment are continuously improving and changing. An updated MSBOS using current blood usage data is necessary for efficient blood management in the hospital blood bank. Methods: This study was a retrospective analysis based on operation names according to the ICD-9-CM at Severance hospital in 2013. We calculated the average units of red blood cells according to each operation, as well as the total units of RBCs used per each operation and patient. Finally an average unit of RBCs was set for the MSBOS, which were ordered before surgical operation. These analyzed results were compared with the previous reports of our hospital and other hospitals. Results: Transfusion episodes occurred in 3,092 cases, which is only 8.6% of all patients. Total transfused units were 8,230 units, 27% of total RBCs (2,270 units) transfused were used in cardiovascular surgery. Compared with the previous data, the usage of RBCs during surgery was decreased. Conclusion: The MSBOS investigated in this study showed some differences in the indicators in 2007. Therefore, regular update of the MSBOS is necessary in each hospital to reflect the advancement of surgical technology. (Korean J Blood Transfus 2015;26:38-46)

Background. Excess ordering of blood products for surgical cases is expensive and wasteful. Evidence has shown that institution-specific versions of the Maximum Surgical Blood Order Schedule (MSBOS) lead to better ordering practices. Most MSBOSs recommend a crossmatch for a minimum of 2 units of packed red blood cells (PRBCs) for cardiac surgical cases; however, studies have shown that >50% of these patients receive no transfusions. Our aim was to create a blood order algorithm for cardiac surgical cases that would decrease unnecessary crossmatching. Methods. Retrospective data was collected for 264 patients from January 2011 through April 2012. The crossmatch-to-transfusion ratio (C:tx), transfusion probability (%T), and transfusion index (TI) were calculated for each type of procedure. Results. All 264 patients were crossmatched and 98 patients were transfused, resulting in an overall transfusion probability (%T) of 37.12% (95% confidence interval 31.52-43.09). A total of 1175 units of blood were crossmatched, but only 370 units of blood were transfused, resulting in a C:tx of 3.17 (95% confidence interval 2.61-4.03). The average number of units transfused per procedure (transfusion index) was 1.40. C:tx was highest and TI was lowest for CABG, where approximately 11 units of blood were ordered for every 1 unit transfused (C:tx =11.70 ± 3.04), and the TI was 0.32. Conclusions. Using the gold standard C:tx of >2:1 as an indicator of inappropriate blood utilization, our analysis confirmed that excessive crossmatching occurred for several procedures. Now a subset of cardiac surgical cases only requires a type and screen order prior to surgery.

In this article we examine the possibility of hardware support for functions of mobile device management platform (MDM-platform) using a Multiple Instructions and Single Data stream computer system, developed within the framework of the project in Bauman Moscow State Technical University. At the universities the MDM-platform is used to provide various mobile services for the faculty, students and administration to facilitate the learning process: a mobile schedule, document sharing, text messages, and other interactive activities. Most of these services are provided by the extensive use of data stored in MDM-platform databases. When accessing the databases SQL- queries are commonly used. These queries comprise operators of SQL-language that are based on mathematical sets theory. Hardware support for operations on sets is implemented in Multiple Instructions and Single Data stream computer system (MISD System). This allows performance improvement of algorithms and operations on sets. Thus, the hardware support for the processing of SQL-queries in MISD system allows us to benefit from the implementation of SQL-queries in the MISD paradigm.The scientific novelty of the work lies in the fact that it is the first time a set of algorithms for basic SQL statements has been presented in a format supported by MISD system. In addition, for the first time operators INNER JOIN, LEFT JOIN and LEFT OUTER JOIN have been implemented for MISD system and tested for it (testing was done for FPGA Xilinx Virtex-II Pro XC2VP30 implementation of MISD system). The practical significance of the work lies in the fact that the results of the study will be used in the project "Development of the Russian analogue of the system software for centralized management of personal devices and platforms in enterprise networks" of the St. Petersburg Polytechnic University (with the financial support of the state represented by the Ministry of Education and Science of the Russian Federation).In this study, we have conducted the testing on the basis of data structures obtained during the approbation of MDM-platform in SPbPU. Test results have shown that on average MISD system provides a two-fold gain for SQL-operators such as INNER JOIN and LEFT JOIN. However, it was found that MISD system does not give gain in cycles for SQL-operator LEFT OUTER JOIN. A comparison was carried out with the processing of requests on Intel Core 2 Duo.The results of this work are areas of further development and improvement of MISD system, including the area of hardware support for new operations.

The concept of incorporating “ilities” into systems seems a self-evidently good idea, as expressed by both written and spoken positions by technical and political leaders. Indeed, incorporating lifecycle properties such as flexibility, adaptability, and recently affordability and resilience, into systems is touted as the solution to modern day's ever increasing complexity, schedule and budget pressures, and the need for finding sustainable solutions. While expressing desires for ilities seems straightforward, tracing these desires to verifiable system instantiations remains ambiguous at best. This paper describes the semantic challenge underlying the concept of a coherent set of system properties, a sampling of various efforts to ascribe meaning to particular ilities, and proposes a prescriptive 20 category semantic basis for specifying a set of ilities, while avoiding the assertion of new definitions. The intention for this first pass prescriptive semantic basis is to begin a structured approach for exploring the existence of one or more semantic fields, which together form a coherent semantic framework for tracing desired ilities into verifiable system requirements and specifications. Preliminary results indicate that at least three semantic fields exist within the larger set of system lifecycle properties including change-type, architecture-type, and new ability-type ilities.

There is a trend in recent database research to pursue coordination avoidance and weaker transaction isolation under a long-standing assumption: concurrent serializable transactions under read-write or write-write conflicts require costly synchronization, and thus may incur a steep price in terms of performance. In particular, distributed transactions, which access multiple data items atomically, are considered inherently costly. They require concurrency control for transaction isolation since both read-write and write-write conflicts are possible, and they rely on distributed commitment protocols to ensure atomicity in the presence of failures. This paper presents serializable read-only and write-only distributed transactions as a counterexample to show that concurrent transactions can be processed in parallel with low-overhead despite conflicts. Inspired by the slotted ALOHA network protocol, we propose a simpler and leaner protocol for serializable read-only write-only transactions, which uses only one round trip to commit a transaction in the absence of failures irrespective of contention. Our design is centered around an epoch-based concurrency control (ECC) mechanism that minimizes synchronization conflicts and uses a small number of additional messages whose cost is amortized across many transactions. We integrate this protocol into ALOHA-KV, a scalable distributed key-value store for read-only write-only transactions, and demonstrate that the system can process close to 15 million read/write operations per second per server when each transaction batches together thousands of such operations.

A recent randomised control trial compared the effects of three rehabilitation programmes for patellofemoral pain: education, education and exercises and education and gait retraining.1 I was excited to read this, as I consider gait retraining an important component of patellofemoral pain treatment. Physical therapists are movement experts and in the best position to address faulty movement patterns. Many running-related injuries, especially those more chronic and requiring medical attention, are associated with faulty running mechanics.2 Muscle strengthening alone may not address faulty mechanics.3 While muscle strength is important and can be considered the ‘hardware’ of movementit is the motor pattern, or the ‘software’, that dictates the movement quality. When movement patterns become habitual, altering them during high demand, functional activities such as running takes time and practice and can be challenging. The goal of gait retraining is to adopt and retain a new motor pattern. Research suggests that this requires an acquisition phase , where extrinsic feedback is provided on a predetermined schedule so that the learner can associated the feedback with their proprioceptive input.4 This is followed by …

Concurrent systems may fail in the field due to various elusive faults such as race conditions. Reproducing such failures is hard because (1) concurrency failures at the system level often involve multiple processes or event handlers (e.g., software signals), which cannot be handled by existing tools for reproducing intra-process (thread-level) failures; (2) detailed field data, such as user input, file content and interleaving schedule, may not be available to developers; and (3) the debugging environment may differ from the deployed environment, which further complicates failure reproduction. To address these problems, we present DESCRY, the first fully automated tool for reproducing system-level concurrency failures based only on default log messages collected from the field. DESCRY uses a combination of static and dynamic analysis techniques, together with symbolic execution, to synthesize both the failure-inducing data input and the interleaving schedule, and leverages them to deterministically replay the failed execution using existing virtual platforms. We have evaluated DESCRY on 22 real-world multi-process Linux applications with a total of 236,875 lines of code to demonstrate both its effectiveness and its efficiency in reproducing failures that no other tool can reproduce.

Modern cryptocurrency systems, such as the Ethereum project, permit complex financial transactions through scripts called smart contracts. These smart contracts are executed many, many times, always without real concurrency. First, all smart contracts are serially executed by miners before appending them to the blockchain. Later, those contracts are serially re-executed by validators to verify that the smart contracts were executed correctly by miners. Serial execution limits system throughput and fails to exploit today’s concurrent multicore and cluster architectures. Nevertheless, serial execution appears to be required: contracts share state, and contract programming languages have a serial semantics. This paper presents a novel way to permit miners and validators to execute smart contracts in parallel, based on techniques adapted from software transactional memory. Miners execute smart contracts speculatively in parallel, allowing non-conflicting contracts to proceed concurrently, and “discovering” a serializable concurrent schedule for a block’s transactions, This schedule is captured and encoded as a deterministic fork-join program used by validators to re-execute the miner’s parallel schedule deterministically but concurrently. We have proved that the validator’s execution is equivalent to miner’s execution. Smart contract benchmarks run on a JVM with ScalaSTM show that a speedup of 1.39$$\times $$ can be obtained for miners and 1.59$$\times $$ for validators with just three concurrent threads.

Design and construction of projects is complex endeavor that requires the coordination of a multitude of human, physical, and natural resources. The technical design and construction complexities are frequently outweighed by the uncertainties and risks with the social, financial, and political aspects of the projects. To address these risks and uncertainties, project participants have turned to a series of cost and schedule risk management tools over the past 50 years. This paper summarizes the evolution of probabilistic cost estimating and scheduling tools. It also provides examples of applications on complex projects from the US Department of Energy, the US Federal Highway Administration/Washington State Department of Transportation, the Panama Canal Authority, and the international ITER fusion generator. The paper concludes with a discussion of the remaining cost and schedule risk management challenges, which inhibit project participants from achieving their project performance goals.

This article discusses the characteristics of effective readers in reading course books and their learning achievement. It is based on a research at English Education Department of FKIP UNS Surakarta 2013/ 2014. The research used qualitative approach in term of case study that deeply describes the case. It employed purposive sampling. The data were collected through observations, interviews, and documents analysis. The effective readers are influenced by their family, friends, lecturers, and their motivation. They read for getting something new and as background knowledge in learning process. They usually read alone, plan the schedule and prefer to read English books. Reading strategies of the effective readers are text books marking to the key points, making notes, keep reading, find easy readings, focus and understand by the context or read multiple sources. They are aware that appropriate reading give positive effects to their learning achievement. So, they always use their own reading strategies and it makes their better achievement.

The maximum surgical blood ordering schedule (MSBOS) provides guidelines for pre-operative pre-transfusion testing for elective surgical procedures. This study compared blood ordering and utilization during the period when the MSBOS was created by achieving consensus between the blood bank and the various surgical specialties, and after the introduction of an MSBOS created by using department-specific red blood cell (RBC) transfusion data (data driven MSBOS, dMSBOS).The dMSBOS was created by analyzing 12 months of RBC transfusion data for each procedure across a regional health system. Pre-transfusion testing and the RBC crossmatch:transfusion (C:T) ratios at 8 of the hospitals were compared between the 12 month period before the dMSBOS was introduced, and the 15 months after its introduction.There were significant reductions in the median monthly number of type and screens not associated with RBC crossmatches (10 714-10 061; p 0.0001) and the median number of type and screens associated with RBC crossmatches (10 127-9 349; p = 0.0014) on surgical patients after dMSBOS implementation. There were significant decreases in the median number of monthly RBC units crossmatched (2 981-2 444; p 0.0001) and transfused (890-791; p 0.0001) to surgical patients after implementing the dMSBOS. The overall system-wide C:T ratio trended down after dMSBOS implementation (from 3.34 to 3.17, p = 0.067).Crossmatching fewer RBC units facilitates more efficient management of the blood bank's inventory.The dMSBOS was effective in reducing the extent of unnecessary pre-transfusion testing before surgery and reduced the number of RBCs that were crossmatched for specific patients.

Presence of students of the Master of Telecommunications Engineering Study Program majoring in Electrical Engineering Semarang State Polytechnic is currently still managed and carried out manually. This does not rule out the possibility of errors in managing data attendance and cheating students in faking their presence, and also with the development of science and technology that is currently completely automated. From this background, it was made the Presence Using RFID Based Raspberry Pi System where the PBM became Admin to be able to access all the attendance data of the S2 Telecommunications Engineering students. Student attendance recording is done by PBM by opening a MySQL database that has been created and stored, then processed and adjusted to existing student data as student ID. The end result obtained is a tool and system that are integrated automatically and also precisely, so that students are required to arrive on time so that they do not get the Compensation if they have passed the deadline and PBM admin can manage the recapitulation data through the website including student data, data lecturer, course data, room data, lecture schedule, attendance activities, and print reports in PDF format. The trial was carried out in the Computer Lab of the Semarang State Polytechnic Applied Science Master. The conclusion is that this tool and system is able to educate students to come and have a scheduled presence and can also record attendance automatically.

We will focused the concept of serializability in order to ensure the correct processing of transactions. However, both serializability and relevant properties within transaction-based applications might be affected. Ensure transaction serialization in corrupt systems is one of the demands that can handle properly interrelated transactions, which prevents blocking situations that involve the inability to commit either transaction or related sub-transactions. In addition some transactions has been marked as malicious and they compromise the serialization of running system. In such context, this paper proposes an approach for the processing of transactions in a cloud of databases environment able to secure serializability in running transactions whether the system is compromised or not. We propose also an intrusion tolerant scheme to ensure the continuity of the running transactions. A case study and a simulation result are shown to illustrate the capabilities of the suggested system.

Now that you have the necessary information about how to create digital faces for law enforcement, it is time to assemble the pieces and get to work creating facial composites. But, what are the steps one takes to begin the process? In this chapter, the author explains how to begin the process from making an appointment, greeting the eyewitness, walking them through the facial composite interview, constructing, refining, and finalizing the image for use by detectives. Though the goal in each process is the same, the two different techniques for creating facial composites, using proprietary software versus the digital pen, are explored in great detail. By the time this chapter is completed both the technician and the artist will have a clear understanding of how to engage their eyewitness in a synergistic relationship that turns a blank electronic canvas into a criminally good facial image.

The computational representational theory of mind conceptualized by Jerry Fodor has dominated the schedule of cognitive science for many years. Fodor defended it as an empirical theory whose plausibility depends on facts about how the mind works. However, current developments in philosophy, psycholinguistics and neurosciences present a challenge to this received view. These developments assume embodied and situated cognition. This paper reviews and assesses the prospects of these new accounts, focusing on processing verbs and on the role of emotions in language processing.

Recently web service composition has become a very cost-effective way to develop business applications. However, owing to the unreliable nature of web services, providing the transactional support in execution of a service composition is an important design requirement. To guarantee the transactional execution of service compositions, a fault-handling routine has to be started once a service failure occurs in order to undo the effect of previously completed services by calling their corresponding compensation operations. Currently this fault-handling mechanism is implemented by means of low-level programming constructs such as exception-handling mechanism in languages such as WS-BPEL. However, since the logic of handling service failures might become very complex in some applications, this concern should be separated from the normal flow of the composition workflow based on the separation of concerns principle. To achieve this, in this study we have proposed an orchestration pattern for building a transactional service composition in which the failure-recovery logic is imposed on the composition workflow by a Labelled Transition System (LTS) as a separate module. It is assumed that each service within the composition is associated with two known transactional properties: (i) a rollback cost that indicates the cost of undoing (compensating) the service and (ii) a failure probability. The transactional logic of the service composition is also specified using the rollback dependencies represented in a rollback graph. An LTS then is generated to schedule the execution of services within the composition based on the composition transactional logic and properties such that upon a service failure, a recovery path with the lowest cost is followed.

Six pigeons were studied in a token economy in which tokens could be produced and exchanged for food on one side of an experimental chamber and for water on the opposite side of the chamber. Responses on one key produced tokens according to a token-production fixed ratio (FR) schedule. Responses on a second key produced an exchange period during which tokens were exchanged for water or food. In Experiment 1a, food tokens could be earned and exchanged under restricted food budgets, and water tokens could be earned and exchanged under water restricted budgets. In Experiment 1b, a third (generalized) token type could be earned and exchanged for either food or water under water restricted budgets. Across Experiments 1a and 1b, the number of tokens accumulated prior to exchange increased as the exchange-production schedule was increased. In Experiment 1b, pigeons produced more generalized than specific tokens, suggesting enhanced reinforcing efficacy of generalized tokens. In Experiment 2, the FR token-production price was manipulated under water restriction and then under food restriction. Production of each token type generally declined as a function of its own price and increased as a function of the price of the alternate type, demonstrating own-price and cross-price elasticity. Production of food and water tokens often changed together, indicating complementarity. Production of specific and generalized tokens changed in opposite directions, indicating substitutability. This is the first demonstration of sustained generalized functions of tokens in nonhumans, and illustrates a promising method for exploring economic contingencies in a controlled environment.