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Scheduling Memory Transactions in Distributed SystemsKim, Junwhan 15 October 2013 (has links)
Distributed transactional memory (DTM) is an emerging, alternative concurrency control model that promises to alleviate the difficulties of lock-based distributed synchronization. In DTM, transactional conflicts are traditionally resolved by a contention manager. A complementary approach for handling conflicts is through a transactional scheduler, which orders transactional requests to avoid or minimize conflicts. We present a suite of transactional schedulers: Bi-interval, Commutative Requests First (CRF), Reactive Transactional Scheduler (RTS), Dependency-Aware Transactional Scheduler} (DATS), Scheduling-based Parallel Nesting} (SPN), Cluster-based Transactional Scheduler} (CTS), and Locality-aware Transactional Scheduler} (LTS). The schedulers consider Herlihy and Sun's dataflow execution model, where transactions are immobile and objects are migrated to invoking transactions, relying on directory-based cache-coherence protocols to locate and move objects. Within this execution model, the proposed schedulers target different DTM models.
Bi-interval considers the single object copy DTM model, and categorizes concurrent requests into read and write intervals to maximize the concurrency of read transactions. This allows an object to be simultaneously sent to read transactions, improving transactional makespan. We show that Bi-interval improves the makespan competitive ratio of DTM without such a scheduler to O(log(N)) for the worst-case and (log(N - k) for the average-case, for N nodes and k read transactions. Our implementation reveals that Bi-interval enhances transactional throughput over the no-scheduler case by as much as 1.71x, on average.
CRF considers multi-versioned DTM. Traditional multi-versioned TM models use multiple object versions to guarantee commits of read transactions, but limit concurrency of write transactions. CRF relies on the notion of commutative transactions, i.e., those that ensure consistency of the shared data-set even when they are validated and committed concurrently. CRF detects conflicts between commutative and non-commutative write transactions and then schedules them according to the execution state, enhancing the concurrency of write transactions. Our implementation shows that transactional throughput is improved by up to 5x over a state-of-the-art competitor (DecentSTM).
RTS and DATS consider transactional nesting in DTM, and focus on the closed and open nesting models, respectively. RTS determines whether a conflicting outer transaction must be aborted or enqueued according to the level of contention. If a transaction is enqueued, its closed-nested transactions do not have to retrieve objects again, resulting in reduced communication delays. DATS's goal is to boost the throughput of open-nested transactions by reducing the overhead of running expensive compensating actions and acquiring/releasing abstract locks when the outer transaction aborts. The contribution of DATS is twofold. First, it allows commutable outer transactions to be validated concurrently and allows non-commutable outer transactions -- depending on their inner transactions -- to be committed before others without dependencies. Implementations reveal effectiveness: RTS and DATS improve throughput (over the no-scheduler case), by as much as 1.88x and 2.2x, respectively.
SPN considers parallel nested transactions in DTM. The idea of parallel nesting is to execute the inner transactions that access different objects concurrently, and execute the inner transactions that access the same objects serially, increasing performance. However, the parallel nesting model may be ineffective if all inner transactions access the same object due to the additional overheads needed to identify both types of inner transactions. SPN avoids this overhead and allows inner transactions to request objects and to execute them in parallel. Implementations reveal that SPN outperforms non-parallel nesting (i.e., closed nesting) by up to 3.5x and 4.5x on a micro-benchmark (bank) and the TPC-C transactional benchmark, respectively.
CTS considers the replicated DTM model: object replicas are distributed across clusters of nodes, where clusters are determined based on inter-node distance, to maximize locality and fault-tolerance, and to minimize memory usage and communication overhead. CTS enqueues transactions that are aborted due to early validation over clusters and assigns their backoff times, reducing communication overhead. Implementation reveals that CTS improves throughput over competitor replicated DTM solutions including GenRSTM and DecentSTM by as much as 1.64x, on average.
LTS considers the genuine partial replicated DTM model. In this model, LTS exploits locality by: 1) employing a transaction scheduler, which enables/disables object ownership changes depending on workload fluctuations, and 2) splitting hot-spot objects into multiple replicas for reducing contention. Our implementation reveals that LTS outperforms state-of-the-art competitors (Score and CTS) by up to 2.6x on micro-benchmarks (Linked List and Skip List) and by up to 2.2x on TPC-C. / Ph. D.
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Leadership in the 2008 financial crisis : Understanding dimensions of Transformational & Transactional leadership during financial crisis in financial institutionsCho, Suna, Tseng, Pei-Fan January 2009 (has links)
<p>Problem: -The 2008 Financial crisis has caused global impact on business market and led to question leader's competence. Prior study has found that leadership contributes certain effects to organizations' performace under a crisis situation, however there is lit-tle study which has been made regarding to identifying crisis leadership and its compe-tence and management during crisis.</p><p>Purpose: - The purpose in this thesis is to bridge the gap between crisis management and leadership by finding answers of five research questions. Which are ; How this 2008 financial crisis has affected the international financial institutions, what leadership dimensions are performed by leaders during the financial crisis, which leadership style do leaders tend to rely on in international financial companies during the 2008 financial crisis, why do leaders tend to rely on the dimensions of transformational leadership or transactional leadership and what are the implications in this study that could lead to fu-ture research.</p><p>Method: - The study employs qualitative methods to fulfill better and deeper understanding about 'how' and 'why' on leadership dimension during the 2008 financial crisis. Data were collected by personal interviews to support and act as a foundation of the analysis to answer the research questions. The choice of interviewees is middle managers of large international companies in the financial sector in Sweden and South Korea.</p><p>Conclusions: - The finding of this study indicates that 2008 financial crisis has af-fected on large international financial corporations in Sweden and South Korea. More-over, three dimensions of transformational leadership are strongly performed by the middle managers during the 2008 financial crisis. The three strongly performed dimen-sions are (1) Inspirational Motivation, (2) Charisma/ Idealized Influence and (3) Indivi-dualized consideration.</p>
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Can Leaders Influence a Learning Organization? An Exploratory Study of the Relationship Between Leadership, Organizational Learning Capability and the Mediating Role of TrustGrover, Ira Ann 13 September 2012 (has links)
The purpose of this research is to study how organizations maintain their competitive advantage in today’s turbulent and highly competitive business environment, by striving to become a learning organization. The impact of factors such as leadership (both transformational and transactional leadership) and trust on an organization’s learning capability is empirically examined. This research adds to the existing body of literature in two ways. First, it argues that a transactional leadership style can influence learning, despite research spanning the last decade that has focused on transformational leadership theory as the dominant model of effective leadership. Therefore, the importance of both leadership styles, each having valuable differential effects is emphasized in this study. Second, the previously untested role of trust as mediating the relationship between leadership and organizational learning capability is examined. It is argued that without supervisor trust, the opportunities for a learning organization to reach its full potential and to subsequently develop learning capabilities is reduced. Findings from this study support the influence of both leadership styles on learning. Trust in one’s supervisor was also found to fully mediate the relationship between leadership and learning.
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Knowledge conversion processes and leadership : an exploratory study of Taiwanese managersChen, Yen-Hao January 2007 (has links)
This research explored the extent to which different knowledge conversion processes require different kinds of leadership. The research was inspired by Nonaka and Konno (1998) and proposed that knowledge conversion processes may each require their own form of leadership because they are conducted under different bas or contexts. Vera and Crossan's (2004) work provided a foundation for this research through the argument that knowledge conversion processes need not only transformational but also transactional leadership. The leadership framework based upon transformational and transactional leadership was therefore adopted for the study. Semi-structured interviews and the Multifactor Leadership Questionnaire (MLQ), developed by Bernard Bass and Bruce Avolio to assess leadership under the transformational and transactional leadership framework, were used to gauge the opinions of participants about leadership and knowledge conversion processes. Scenarios/descriptions derived from Nonaka and Takeuchi (1995) were used to focus the mindset of the participants involved in the interviews and the questionnaire, which was administered at the time of the interviews to support triangulation. Findings suggested that knowledge conversion processes do not differ to the extent that they require both transformational and transactional leadership. However, qualitative evidence indicated that knowledge conversion processes were somewhat different in terms of certain dimensions of transformational leadership. These differences related to the need for a strong sense of purpose, a compelling vision of the future and long-termism in some but not all situations involving the leadership of knowledge conversion processes.
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Exploring transactions between supply chain entities : a psychological study of buyer-supplier relationshipsDani, Samir January 2005 (has links)
The research presented in this thesis has focussed on exploring buyer- supplier relationships from a human perspective. To date, researchers across the globe have studied buyer-supplier relationships and endeavoured to find means to try to make them better. This has led to many new relationship development programmes initiated by companies and new concepts introduced by academics for the betterment of buyersupplier relationships. The focus of academics has been in trying to study buyersupplier relationships from various factors, viz. power, opportunistic behaviour, unethical behaviour, partnerships, collaborations, etc. All these endeavours have focussed on using technology or business processes in order to streamline operations and create environments, which would foster partnerships or collaborations. One aspect not usually given prominence in these studies has been the presence of humans in the relationship as representatives of the transacting companies. Giving this more focus, the researcher feels that organisational culture plays a very strong role in the way organisations operate, and when two organisations transact with each other the individual culture is bound to play a role in the way the transaction is conducted. The individual culture of the organisation also depends upon the humans in the organisation. Since, the focus of the research was on exploring the buyer-supplier relationships from a human perspective, the research sought this perspective from people working in purchasing or sales functions in different companies. The information was collected by conducting "Phenomenological Interviews" with focus on "critical incidents" affecting the relationship. The information was analysed for themes which led to the need to study buyer-supplier relationships from two perspectives: 1) game-like behaviour, 2) discretion, humans have in the relationship. The presence of game-like behaviour and humans in the relationship led the researcher to study the concepts of "Transactional Analysis" and check for the feasibility to transfer the concepts from a therapeutic setting to buyer- supplier relationships. The research has been successful in exploring issues affecting buyer-supplier relationships. A methodology for aligning supply chains by taking into account human issues has been proposed. The methodology comprises a relationship framework that is used for studying buyer-supplier relationships on a macro- level based on the levels of satisfaction the entities have with each other. Since high levels of dissatisfaction lead to various change- inducing transactions or game-like behaviour between the entities, the framework identifies the status of the relationship, and can be used to gauge what's going to happen to it, once the transaction is over. The concepts of Transactional Analysis and the tools associated with it, viz. Drama Triangle analysis and structural modelling are useful in studying the dynamics of the transactions from the human perspective and also from a psychological perspective.
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Biblioteksverksamhet som distansverksamhet : En analys av UH-bibliotekens roll för distansstudenter / Library activities as distance activities : An analysis of university libraries role for distance learnersLaében-Rosén Stark, Josef January 2016 (has links)
The purpose of this bachelor thesis is to gainknowledge in how some Swedish university librariesexpresses their work regarding web based servicesfor distance learners via activity documents andwebb pages. A qualitative content analysis isconducted to investigate this. The empirical materialconsists of nineteen different documents and elevenselected parts of websites related to eleven differentuniversity libraries. The results show that there is avariation in how and to what degree differentuniversity libraries expresses their services todistance learners. Three main themes emerge fromthe content: ”the electronic library resources”, ”thevirtual library room” and ”the librarian's pedagogicalrole”, all in different ways connected to distancelearners. The results is discussed based on “thetheory of transactional distance”. The principalfindings is that the libraries expresses greatenthusiasm for digital development and web basedservices. Some in more explicit ways and some inmore implicit ways. Based on the findings from thisstudy and from the previous research and literatureon the subject, the conclusion is that it is notpossible to completely distinguish the distancestudents' needs from other students and it is notentirely possible to distinguish the role of theuniversity library in a psysical or a virtualenvironment.
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GROWING UP IN IRELAND: FACTORS IMPACTING SLEEP PATTERNS OF PRETERM INFANTSFallon, Joanne 01 January 2015 (has links)
GROWING UP IN IRELAND: FACTORS IMPACTING SLEEP PATTERNS OF PRETERM INFANTS
By Joanne Fallon MS, OT, PhD
A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University
Virginia Commonwealth University, 2015.
Major Director: Shelly J. Lane, PhD, Professor, Department of Occupational Therapy
Preterm infants represent the largest child patient group in the European Union (EU), accounting for 5.5-11.4% of all births (European Foundation for the Care of Newborn Infants, 2011b). Preterm birth is defined as birth prior to 37 weeks gestation. Infants born late preterm (34-36 weeks) are considered more similar to early preterm (> 34 weeks) than to full-term infants, despite previously regarded as near-term (Raju Higgins, Stark, & Leveno, 2006). For preterm infants, sleeping functions are critical as they demonstrate the ability to adjust to biological and social rhythms and support emotional regulation, learning, and memory. Many studies have focused on sleep patterns of full-term infants; however, few have investigated preterm infants and none have compared early and late preterm infants with a population from the Republic of Ireland. The purpose of this study was to identify infant and parent characteristics that promote optimal sleep in preterm infants and to establish whether the parent-infant relationship mediates this association. A secondary purpose was to test the transactional model of sleep. Parent report of infant sleep
was taken from a recent population-based dataset from the Republic of Ireland. A comparison of the day and nighttime sleep patterns of early and late preterm infants found no difference between groups. There was also no difference in infant temperament, breast-feeding, parental stress, depression, or sociodemographics. A difference was found between groups in infant development, weight at 9 months, and age infant began solid foods. This finding was not surprising as infants born early preterm are at greater at greater risk of developmental delay and disability. Results of this study suggest that the paternal-infant relationship has a mediating impact on the relationship between infant temperament and nighttime waking in the early preterm group only, while the maternal-infant relationship has a mediating role in both groups. These findings add to the body of knowledge on the transactional model of sleep, and are the first to identify infant temperament and the paternal-infant relationship as important factors. Implications of these results are discussed in the context of the transactional model of sleep and recommendations for future research are presented.
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HEALTHY AND MALADAPTIVE COPING STRATEGIES AMONG MASTER OF SOCIAL WORK STUDENTSLopez, Jody D 01 June 2014 (has links)
The purpose of this study was to explore healthy and maladaptive coping strategies among MSW students. The data was collected using self‑reported questionnaires. A total of 47 students participated in this study. Using the Transactional Model of Stress and Coping as a theoretical framework, this study assessed stress levels using the Perceived Stress Scale. The Brief COPE instrument measured coping strategies. The study found relationships between stressors and maladaptive coping and perceived stress. The study recommends that future research on coping strategies among MSW students include greater attention to training MSW students how to deal with stress during their MSW educational programs.
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The poetry of response : adolescent experiences of two class novelsClarke, Penny L., n/a January 1993 (has links)
This study, conducted in a junior high school in Canberra, used
naturalistic research methodology and idiographic data analysis. As the
results obtained in the study were time and context specific, the object
was to reveal the personal factors which affected the nature of the
reading experience for individual research participants. The theoretical
basis of the research was derived from Louise Rosenblatt's transactional
theory and focused on the reading experiences of adolescents with whole
class novels.
Three research techniques were employed in the exploration of aesthetic
reader responses to two whole class novels. The techniques: reading
journals, small group discussions and creative written responses to the
text were implemented sequentially and revealed different levels and
stages of individual and group responses from the 'primary spontaneous'
to a considered reflective response. Data was explored through the case
study mode of analysis which included information relevant to the
individual research participants and the study context.
The research explored the integration of the individual's evocation of the
text with the individual's awareness of self, text, literature and the wider
social context. The research data concluded that the employment of
classroom practices which focus on a full, individual transaction with a
text promotes the development of critical awareness of and familiarity
with the text. This sound understanding of the individual's evocation of
the text forms a self-aware and firm basis for the development of active,
engaged and critical readers of texts.
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台灣企業網絡-由交易成本經濟學的觀點出發 / The Interorganizational Networks in Taiwan: From the Viewpoint of Transactional Cost Economy簡岳佐, Chien, Yueh Tso Unknown Date (has links)
本研究嘗試從企業界中實際的現象切入,觀察並探討近年來相當熱門的研究課題─企業網絡。主要研究問題有:
1.是否存在不同類型的企業網絡?若存在,則不同的企業網絡應有何不同的競爭策略?
2.是否能為學術上企業網絡問題的研究,尋求一個簡單易用的架構?
3.身處企業網絡中的廠商,應如何制訂競爭策略?
4.對於台灣以企業網絡為主的競爭方式,政府在制訂政策時,應該有哪些特別考量?
選取作為研究對象的產業為台灣自行車產業、工具機產業,而主要研究結論如下:
1.企業網絡型態可依資產特殊性程度的不同,區分為資產特殊性程度較低的市場型網絡,與資產特殊性程度較高的組織型網絡。
2.市場型網絡體系的結構傾向於開放式;更換網絡成員的成本較低;中心廠傾向於讓協力廠自由發展;個別協力廠產生危機對中心廠衝擊較小;協力廠對中心廠的依賴程度較低。
3.組織型網絡體系的結構傾向於封閉式;更換網絡成員的成本較高;中心廠傾向於涉入協力廠的管理活動;個別協力廠產生危機對中心廠衝擊較大;協力廠對中心廠的依賴程度較高。
4.當客觀環境改變時,市場型網絡有轉變為組織型網絡的可能,而組織型網絡亦有轉變為市場型網絡的可能。
5.市場型網絡的策略是所謂的「同中求異」,而組織型網絡則是「異中求同」。
6.在從事產業升級的努力時,市場型網絡體系中傾向於由廠商個別做升級的努力,而組織型網絡體系則傾向於由中心廠與協力廠共同合作。
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