1,721,004 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Concurrency Control for High-Performance Storage Engines
Get PDFHistorically, storage engines were constrained by limited DRAM capacity and the slow hard disk drives, which led to the development of disk-based system architectures.
The emergence of many-core CPUs, along with the increased affordability and performance of PCIe-attached NVMe SSDs, has led to the development of high-performance storage engines.
These engines demonstrate that with a redesigned buffer manager, systems can achieve in-memory performance levels when the working set fits within the buffer pool, while gracefully degrading with larger data sets.
However, to fully exploit modern hardware, a complete redesign of all components of traditional storage engines is necessary.
In this thesis, we rethink concurrency control for this new emerging class of high-performance storage engines.
At a high level, we focus on Multi-Version Concurrency Control (MVCC), specifically snapshot isolation commit protocol, dependency tracking, version storage, and garbage collection.
On a lower level, we address the scalability and space utilization of B-Tree indexes in storage engines.
For scalable MVCC, we propose OSIC, a commit protocol for snapshot isolation that efficiently scales to more concurrent transactions than the number of CPU cores by minimizing cross-worker communication.
This allows us to harness the increasing number of IOPS that modern flash drives offer.
Additionally, we suggest a commit dependency tracking mechanism that combines distributed logging with Early Lock Release to reduce abort rate and latency.
For robust performance in mixed workloads, we propose a storage layer that automatically adjusts to user workloads at the tuple level without requiring manual user intervention.
This includes removing tombstones from the OLTP hot path and an adaptive version storage and garbage collection scheme.
We also address B-Tree node unnecessary write contention through node splitting and improve space utilization by merging underfull sibling nodes at eviction.Historisch gesehen waren Speichersysteme (Storage Engines) durch begrenzte DRAM-Kapazität und die langsame Festplattenlaufwerke eingeschränkt, was zur Entwicklung von diskbasierten Systemarchitekturen führte.
Das Aufkommen von Many-Core-CPUs sowie die gestiegene Erschwinglichkeit und Leistung von PCIe-gebundenen NVMe-SSDs führten zur Entwicklung von Hochleistungsspeichersystemen.
Diese Engines zeigen, dass Systeme mit einem neu gestalteten Puffermanager nahezu in-Memory-Performance erreichen können, wenn der Arbeitsdatensatz in den Puffer passt, und sich bei größeren Datensätzen mäßig verlangsamen.
Um jedoch die moderne Hardware voll auszuschöpfen, ist eine vollständige Neugestaltung aller Komponenten herkömmlicher Speichersysteme erforderlich.
In dieser Arbeit gestalten wir die Nebenläufigkeitskontrolle für diese aufstrebende Klasse von Speichersystemen neu.
Auf einer hohen Ebene konzentrieren wir uns auf die Multi-Version Concurrency Control (MVCC), insbesondere auf das Snapshot Isolation Commit Protokoll, die Speicherung von Versionen, die Abhängigkeitsverfolgung und Garbage Collection.
Auf einer niedrigeren Ebene adressieren wir die Skalierbarkeit und den Speicherplatzverbrauch von B-Baum Indexstrukturen in Speichersystemen.
Für skalierbare MVCC schlagen wir OSIC vor, ein Commit-Protokoll für Snapshot Isolation, das effizient skaliert und mehr nebenläufige Transaktionen als die Anzahl der CPU-Kerne ermöglicht, indem es die Kommunikation zwischen Workers minimiert.
Dies ermöglicht es uns, die steigende Zahl von IOPS zu nutzen, die moderne Flash-Laufwerke bieten.
Darüber hinaus schlagen wir einen Mechanismus zur Verfolgung von Commit-Abhängigkeiten vor, der verteiltes Logging mit Early Lock Release integriert, um die Abbruchrate und die Latenz der Transkationen zu reduzieren.
Für robuste Leistung in gemischten HTAP Workloads schlagen wir eine Storage Layer vor, die sich automatisch auf Benutzer-Workloads auf Tupel-Ebene anpasst, ohne manuelles Eingreifen des Benutzers zu erfordern.
Dies umfasst das Entfernen von Tombstones aus dem OLTP-Hot Path und ein adaptives Versions Storage und Garbage Collection Schema.
Wir adressieren auch unnötigen Schreibkonflikt auf B-Baum Knoten durch Knotenaufteilung und verbessern die Speichernutzung, indem wir unterausgelastete Geschwisterknoten beim Auslagern zusammenführen
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
MxTasks: a novel processing model to support data processing on modern hardware
Get PDFThe hardware landscape has changed rapidly in recent years. Modern hardware in today's servers is characterized by many CPU cores, multiple sockets, and vast amounts of main memory structured in NUMA hierarchies.
In order to benefit from these highly parallel systems, the software has to adapt and actively engage with newly available features.
However, the processing models forming the foundation for many performance-oriented applications have remained essentially unchanged.
Threads, which serve as the central processing abstractions, can be considered a "black box" that hardly allows any transparency between the application and the system underneath.
On the one hand, applications are aware of the knowledge that could assist the system in optimizing the execution, such as accessed data objects and access patterns.
On the other hand, the limited opportunities for information exchange cause operating systems to make assumptions about the applications' intentions to optimize their execution, e.g., for local data access.
Applications, on the contrary, implement optimizations tailored to specific situations, such as sophisticated synchronization mechanisms and hardware-conscious data structures.
This work presents MxTasking, a task-based runtime environment that assists the design of data structures and applications for contemporary hardware.
MxTasking rethinks the interfaces between performance-oriented applications and the execution substrate, streamlining the information exchange between both layers.
By breaking patterns of processing models designed with past generations of hardware in mind, MxTasking creates novel opportunities to manage resources in a hardware- and application-conscious way.
Accordingly, we question the granularity of "conventional" threads and show that fine-granular MxTasks are a viable abstraction unit for characterizing and optimizing the execution in a general way.
Using various demonstrators in the context of database management systems, we illustrate the practical benefits and explore how challenges like memory access latencies and error-prone synchronization of concurrency can be addressed straightforwardly and effectively
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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