This bachelor thesis evaluates the impact of datanode crashes on the performance of the read operations of a Hadoop Distributed File System, HDFS. The goal is to better understand how datanode crashes, as well as how certain parameters, affect the  performance of the read operation by looking at the execution time of the get command. The parameters used are the number of crashed nodes, block size and file size. By setting up a Linux test environment with ten virtual machines and Hadoop installed on them and running tests on it, data has been collected in order to answer these questions. From this data the average execution time and standard deviation of the get command was calculated. The network activity during the tests was also measured. The results showed that neither the number of crashed nodes nor block size had any significant effect on the execution time. It also demonstrated that the execution time of the get command was not directly proportional to the size of the fetched file. The execution time was up to 4.5 times as long when the file size was four times as large. A four times larger file did sometimes result in more than a four times as long execution time. Although, the consequences of a datanode crash while fetching a small file appear to be much greater than with a large file. The average execution time increased by up to 36% when a large file was fetched but it increased by as much as 85% when fetching a small file.

Dans cette thèse, nous étudions le problème d’optimisation du temps de transfert de données dans les systèmes de gestion de données distribuées, en nous focalisant sur la relation entre le temps de communication de données et la configuration du middleware. En réalité, le middleware détermine, entre autres, comment les données sont divisées en lots de F tuples et messages de M octets avant d’être communiqués à travers le réseau. Concrètement, nous nous concentrons sur la question de recherche suivante : étant donnée requête Q et l’environnement réseau, quelle est la meilleure configuration de F et M qui minimisent le temps de communication du résultat de la requête à travers le réseau?A notre connaissance, ce problème n’a jamais été étudié par la communauté de recherche en base de données.Premièrement, nous présentons une étude expérimentale qui met en évidence l’impact de la configuration du middleware sur le temps de transfert de données. Nous explorons deux paramètres du middleware que nous avons empiriquement identifiés comme ayant une influence importante sur le temps de transfert de données: (i) la taille du lot F (c’est-à-dire le nombre de tuples dans un lot qui est communiqué à la fois vers une application consommant des données) et (ii) la taille du message M (c’est-à-dire la taille en octets du tampon du middleware qui correspond à la quantité de données à transférer à partir du middleware vers la couche réseau). Ensuite, nous décrivons un modèle de coût permettant d’estimer le temps de transfert de données. Ce modèle de coût est basé sur la manière dont les données sont transférées entre les noeuds de traitement de données. Notre modèle de coût est basé sur deux observations cruciales: (i) les lots et les messages de données sont communiqués différemment sur le réseau : les lots sont communiqués de façon synchrone et les messages dans un lot sont communiqués en pipeline (asynchrone) et (ii) en raison de la latence réseau, le coût de transfert du premier message d’un lot est plus élevé que le coût de transfert des autres messages du même lot. Nous proposons une stratégie pour calibrer les poids du premier et non premier messages dans un lot. Ces poids sont des paramètres dépendant de l’environnement réseau et sont utilisés par la fonction d’estimation du temps de communication de données. Enfin, nous développons un algorithme d’optimisation permettant de calculer les valeurs des paramètres F et M qui fournissent un bon compromis entre un temps optimisé de communication de données et une consommation minimale de ressources. L’approche proposée dans cette thèse a été validée expérimentalement en utilisant des données issues d’une application en Astronomie. / In this thesis, we take a complementary look to the problem of optimizing the time for communicating query results in distributed query processing, by investigating the relationship between the communication time and the middleware configuration. Indeed, the middleware determines, among others, how data is divided into batches and messages before being communicated over the network. Concretely, we focus on the research question: given a query Q and a network environment, what is the best middleware configuration that minimizes the time for transferring the query result over the network? To the best of our knowledge, the database research community does not have well-established strategies for middleware tuning. We present first an intensive experimental study that emphasizes the crucial impact of middleware configuration on the time for communicating query results. We focus on two middleware parameters that we empirically identified as having an important influence on the communication time: (i) the fetch size F (i.e., the number of tuples in a batch that is communicated at once to an application consuming the data) and (ii) the message size M (i.e., the size in bytes of the middleware buffer, which corresponds to the amount of data that can be communicated at once from the middleware to the network layer; a batch of F tuples can be communicated via one or several messages of M bytes). Then, we describe a cost model for estimating the communication time, which is based on how data is communicated between computation nodes. Precisely, our cost model is based on two crucial observations: (i) batches and messages are communicated differently over the network: batches are communicated synchronously, whereas messages in a batch are communicated in pipeline (asynchronously), and (ii) due to network latency, it is more expensive to communicate the first message in a batch compared to any other message that is not the first in its batch. We propose an effective strategy for calibrating the network-dependent parameters of the communication time estimation function i.e, the costs of first message and non first message in their batch. Finally, we develop an optimization algorithm to effectively compute the values of the middleware parameters F and M that minimize the communication time. The proposed algorithm allows to quickly find (in small fraction of a second) the values of the middleware parameters F and M that translate a good trade-off between low resource consumption and low communication time. The proposed approach has been evaluated using a dataset issued from application in Astronomy.

No description available.

Abstract: Many regions of the cortex have been identified to be specifically selective for different features. For example, visually presented stimuli proceed, via both the dorsal “where” and ventral “what” streams, before converging in the frontal cortex for decision making processes. However, several subregions of both streams have been identified that demonstrate selectivity on many semantic dimensions, such as size. Most of the studies examining regions selectively activated in maintenance of semantic size have employed the use of visually presented images. In the present, however, study we provide a review of relevant literature, proposed techniques, and a list of word stimuli that may help elucidate the multivariate neural processing of several semantic dimensions.

Prey s'appuie sur les décisions d'évasion lorsqu'il est confronté à des prédateurs pour maximiser les avantages de rester en place tout en réduisant les coûts de la prédation. Ce compromis de l'histoire de vie peut être reflété par la distance d'initiation de vol (FID), la distance à laquelle un individu prend son envol lorsqu'il est approché par un humain. J'ai abordé les facteurs potentiels expliquant la variation FID avec des données d'espèces d'oiseaux en Europe. La variabilité génétique était liée au risque de prédation FID; les espèces d'oiseaux menacées avaient généralement une FID plus longue que les espèces proches non menacées; le caractère distinctif de l'évolution (ED), un indicateur reflétant l'isolement phylogénétique des taxons, était positivement lié à la FID chez les oiseaux d'eau; La FID moyenne de différentes espèces d'oiseaux était positivement corrélée avec les niveaux spécifiques de MDA (malondialdéhyde qui est un indice de stress oxydatif) et UA (acide urique, qui est une mesure de la capacité antioxydante) et FID augmentée avec la taille du troupeau chez les espèces grégaires mais pas chez les espèces non grégaires. Ces résultats peuvent contribuer à la compréhension des causes et des conséquences des différences interspécifiques dans le comportement de fuite des prédateurs contre les prédateurs, et, plus important encore, ils peuvent fournir des moyens de résoudre les problèmes de conservation. Mots-clés : masse corporelle, taille du cerveau, taille effective de la population, modèle linéaire phylogénétique, stress oxydatif, comportement social / Prey rely on escape decisions when confronted with predators to maximize the benefits of staying put while reducing the costs of predation. This life history compromise can be reflected by flight initiation distance (FID), the distance at which an individual takes flight when approached by a human. I addressed potential factors explaining variation FID with data from bird species in Europe. Genetic variability was related to predation risk FID; threatened bird species generally had a longer FID than non-threatened closely related species; evolutionary distinctiveness (ED), an indicator reflecting the phylogenetic isolation of taxa, was positively related to FID in waterbirds; mean FID of different species of birds was positively correlated with species-specific levels of MDA (malondialdehyde which is an index of oxidative stress) and UA (uric acid, which is a metric of antioxidant capacity) and FID increased with flock size in gregarious species but not in non-gregarious species. These findings may contribute to the understanding of the causes and consequences of interspecific differences in anti-predator escape behavior of birds, and, more importantly they may provide means for resolving conservation problems. Key words: body mass, brain size, effective population size, phylogenetic linear model, oxidative stress, social behavior

Effect sizes are the currency of psychological research. They quantify the results of a study to answer the research question and are used to calculate statistical power. The interpretation of effect sizes—when is an effect small, medium, or large?—has been guided by the recommendations Jacob Cohen gave in his pioneering writings starting in 1962: Either compare an effect with the effects found in past research or use certain conventional benchmarks. The present analysis shows that neither of these recommendations is currently applicable. From past publications without pre-registration, 900 effects were randomly drawn and compared with 93 effects from publications with pre-registration, revealing a large difference: Effects from the former (median r = 0.36) were much larger than effects from the latter (median r = 0.16). That is, certain biases, such as publication bias or questionable research practices, have caused a dramatic inflation in published effects, making it difficult to compare an actual effect with the real population effects (as these are unknown). In addition, there were very large differences in the mean effects between psychological sub-disciplines and between different study designs, making it impossible to apply any global benchmarks. Many more pre-registered studies are needed in the future to derive a reliable picture of real population effects.

Hösten 2017 introducerades en ny storleksstandard SS-EN 13402-3:2013 (Swedish Standards Institute 1922a). Standarden är tänkt att hjälpa klädföretag inom Europa att förtydliga för konsumenter vilken storlek som passar baserat på individens kroppsmått. Insatta nyckelpersoner intervjuades gällande standardens bakgrund och utformning i syfte att uppskatta storleksstandardens relevans för konfektionsindustrin. I enlighet med detta upprättades två enkäter vilka uppgav grundläggande information kring standardens avsikt. 230 konsumenter fick därefter ta ställning till att om den nya storleksstandarden implementeras av företag, hur skulle detta påverka processen till att hitta rätt klädstorlek medan befintliga yrkesverkande fick motsvarandefrågor om företagets syn på att införa detta i deras system. Denna studie beskriver den övervägande anledningen till konsumenternas svårigheter att hitta rätt klädstorlek och deras åsikter om företag skulle tillämpa denna standard. Utifrån analysering av svaren från företag, konsumenter och bistånd från tidigare forskning har en slutsats genomförts. Studien reflekterar över olika möjligheter för vidareforskning, hur företag kan gå tillväga för en effektiv storlekskonvertering och varför en storlekskonvertering kan gynna ett företag i längden. / The fall of 2017 a new size standard was introduced SS-EN 13402:3-2017 (Swedish Standards Institute 1922a). The standard is intended to help clothing companies in Europe to clarify for consumers what size is appropriate based on the individual’s body measurements. Well-informed influential people were interviewed regarding the background and configuration of the standard in order to estimate the relevance of the size standard for the clothing industry. In accordance with this, two questionnaires were established which explained the basic information about the purpose of the standard. 230 consumers were then asked about there view about if the new size standard was implemented by companies, how would this affect the process of finding the right size of clothing while existing professionals got similar questions about the company's view of introducing this into their system. This study discloses the predominant reason for the consumer's difficulty in finding the right clothing size and their thoughts if companies would apply this standard. Based on analysis of the responses from companies, consumers and reinforcement from previous research, a conclusion has been made. The study reflects on various possibilities for further research, how companies can proceed to make an effective size conversion and why a size conversion can benefit a company in the long run.

Trade-off between offspring size and number belongs to the most discussed concepts in the life history theory. The aim of this study was to elucidate the relationship between egg size, clutch size and female body mass at the family level in bird's and to examine whether there is the relationship between offspring size and number and life history traits specific for particular bird families. From published sources, I collected data about 5.073 species belong in 146 families. Most species of birds lay smaller clutches, on average three eggs. In 112 families from 130 tested eggs size was positively correlated with female body mass. There is evidence that egg size and clutch size are inversely related in 83 families from 130 tested but only for 34 families was significant. The relationship exists independently of female body mass across bird families and this suggests a trade-off between these traits. The relationship between the strength and shape of egg size-number correlations and life history characteristics of bird families was not frequent. According to results, the strength of correlation seems to be related to development mode and diet type. The negative egg size-number correlation is stronger when incubation period and fledging time is longer and in birds with longer lifespan. The...

Syfte: Syftet med denna studie är att undersöka om revisionsbyråns storlek, uppdragslängden hos klienten, klientens storlek och revisorns kön påverkar revisorns benägenhet att utfärda fortlevnadsvarningar och således har en påverkan på revisionskvaliteten. Metod: Studien utgår från en kvantitativ forskningsmetod där data samlats in genom innehållsanalys av sekundärdata i form av årsredovisningar och revisionsberättelser. Urvalet består av 301 onoterade aktiebolag som inlett konkurs under 2020 och 2021. Data har analyserats i statistikprogrammet SPSS genom en logistisk regression där sambandet mellan utfärdade fortlevnadsvarningar och utvalda faktorer studerats. Resultat och slutsats: Resultatet från den statistiska analysen visar att varken uppdragslängden hos klienten, klientens storlek eller revisorns kön har ett statistiskt signifikant samband med revisionskvalitet. Däremot uppvisas ett statistiskt signifikant samband mellan revisionskvalitet och mellanstora revisionsbyråer gentemot mindre revisionsbyråer. De mellanstora revisionsbyråerna uppvisade högre revisionskvalitet än de mindre revisionsbyråerna. Inget statistiskt signifikant samband uppmättes mellan revisionskvalitet och stora revisionsbyråer gentemot mindre revisionsbyråer. Examensarbetets bidrag: Studien har bidragit till ytterligare forskning inom revisionskvalitet i onoterade bolag i Sverige och världen. Fortsatt bidrar studien till kunskap om vilka faktorer som har/inte har en påverkan på revisionskvaliteten. Studien visar bland annat på att kvinnor och män utför revision av samma kvalitet samt att stora och mindre revisionsbyråer utför revision av samma kvalitet. Förslag till fortsatt forskning: Ett förslag till vidare forskning är att genomföra en jämförande studie där den levererade revisionskvaliteten innan respektive under och efter pandemin undersöks för att se om det skiljer sig åt mellan åren. Även att jämföra revisionskvaliteten mellan onoterade och noterade bolag är något som hade varit intressant. Vidare hade det till forskningen inom området varit givande om en studie genomförts som undersökte kvaliteten utifrån typ I-fel. / Aim: The purpose of this study is to examine whether audit firm size, audit tenure, client size and the audit gender affect the auditor’s ability to issue going concern warnings and through that has an impact on the audit quality. Method: The study was conducted with a quantitative research method where data has been collected through content analysis of secondary data from annual reports and audit reports. The sample consists of 301 unlisted companies that went bankrupt in 2020 and 2021. Data has been analysed in the statistical program SPSS through a logistic regression where the relationship between issued going concern warnings and selected factors has been studied. Results and conclusion: The result from the statistical analysis shows that neither the audit tenure, client company size or auditor gender have a statistically significant relationship with audit quality. In contrast, medium sized audit firms show a statistically significant relationship with audit quality in comparison with smaller audit firms where medium sized firms show higher audit quality than smaller audit firms. No statistically significant relationship was measured between audit quality and big sized audit firms in comparison with smaller audit firms. Contribution of the thesis: The study contributes to further research of audit quality in unlisted companies. The study also contributes to knowledge about which factors that have, or do not have an impact on audit quality. It shows that women and men perform audit of the same quality and that big and small audit firms perform audit of the same quality. Suggestion for future research: A proposal for further research is to implement a comparative study where the delivered audit quality before, during and after the pandemic is examined to see if it differs between the years. Comparing the audit quality between unlisted and listed companies is also something that would have been interesting. Furthermore, it would have been rewarding for the research in the field if a study had been carried out thar examined the quality based on type I errors.

Background: In the present competitive environment manufacturing firms have shifted their production from mass production to mass customization. In this line, a flexible manufacturing system (or FMS) has evolved to the changing requirements. The estimation of fleet size of AGVs has shown to be a critical decision to increase the efficiency of material handling systems by increasing throughput and reduce delay in manufacturing.[4] The initial investment cost and the total life cycle cost of AGV systems rely on the number of AGVs required.   Objectives: The objective of this study is to analyze the optimal fleet sizing of AGVs in terms of the capacity needs of machines/stations and the available capacity of the AGVs working in the production site. The aim of this study is to give potential users of AGVs an optimization model to consider when planning the optimal number of AGVs needed given their capacity needs.   Methods: The methodology presents our contribution to a general model for deciding fleet size with multiple AGV’s defined as a “big system”. In comparison to previous models, we consider how the capacity of AGV’s can change depending on several factors leading to congestion and delay. The study defines these factors, finds the cause behind them and categorizes them to be used as input variables for the model. The methodology explains the important factors needed for implementing the general model for specific cases when conducting the investigation. The final part of the methodology will discuss the reliability and validity of our approach.  Results: the result presents how the general model was applied at the manufacturing company of Emballator Växjöplast AB. The data gathered and information from the capacity analysis were used to measure the demand for transportation, the AGV capacity, and the factors affecting delay and congestion. The values were then used in the model to determine the optimal fleet size for the case. The result gave a high indication for accuracy and that the general model can be used in specific cases. Finally, we conducted an analysis of how delays and congestion affected the supply of transportation as fleet size increases. The result indicated that the optimal fleet size of AGVs that satisfy 35 machines/stations was 1,32 while the theoretical fleet size of AGVs was 1.3. This yielded a result of 98.84% accuracy in estimating the optimal fleet sizing of AGVs in terms of the capacity needs of machines/stations and the available capacity of the AGVs working in the production site. Conclusions: The result shows that the approach of analyzing the capacity needs of the production site and the capacity available to the AGV can accurately be used to estimate the optimal fleet sizing of AGVs. The implication of this study and the optimization model that considers capacity needs and capacity available rather than specific layout characteristics will allow users to cope with the changing requirements of mass customization. The users will consider their demand forecast and use the optimization model to help them plan the optimal fleet sizing of AGVs. / Bakgrund: I den nuvarande konkurrensenskraftiga miljön har tillverkningsföretag skiftat produktion från massproduktion till massanpassning. Därmed har flexible manufacturing system (eller FMS) växt fram till följd av de förändrade kraven. Estimation av fleet size av AGV har visat sig vara ett kritiskt beslut för att öka effektiviteten av materialhanteringssystem genom ökad genomströmning och minskad försening i produktionen.[4] Den initiala investeringskostnaden och den totala livscykelkostnaden beror på antalet AGVer som det finns behov av i produktionen.   Syfte: Syftet med här studien är att analysera det optimala antalet AGVer som det finns behov av i relation till kapacitetsbehovet hos maskiner/stationer och den tillgängliga kapaciteten hos AGV som arbetar i produktionsanläggningen. Målet med den här studien är att förse potentiella användare av AGV med en optimeringsmodell som de kan använda vid planering av antalet AGV som de har behov av givet deras kapacitetsbehov.   Metod: I metoden presenteras vårt bidrag till en generell modell för att bestämma antalet AGV: er för ett system med flera enheter som definieras som ett ”stort system”. Till skillnad från tidigare modeller, så tar vi hänsyn till flera faktorer som orsakar kongestion och fördröjningar. Studien definierar dessa faktorer, finner orsaken till dem, och kategoriserar dem för att kunna tillämpa dem i modellen. Metoden förklarar vikten av varför dess variabler är nödvändiga att mäta när den generella modellen tillämpas för specifika fall när man utför en utredning av fallet. Slutligen avslutas metoden med att diskutera dess trovärdighet och validitet.     Resultat: Resultatet presenterar hur den generella modellen tillämpats på ett produktionsföretag Emballator Växjöplast AB.  Datainsamlingen och information från kapacitet analysen har använts för att mäta transportbehovet, AGV: ens kapacitet och de påverkande faktorer som orsakar fördröjning och kongestion. Dessa värden användes sedan i den generella modellen för att avgöra det optimala antalet AGV: er för fallet. Resultatet indikerar tydligt på att det finns en hög precision av den generella modellen kan tillämpas för specifika fall. Slutligen utför vi en analys om hur fördröjningar och kongestion påverkar transportillförsen i samband med att antalet AGV: er ökar. Resultatet visar att det optimala antalet AGVer som det finns behov av för att förse kapacitetsbehovet av 35 maskiner/stationer var 1.32 medan det teoretiska svaret från optimeringsmodellen visade ett svar på 1.30 AGVer. Detta resulterade i en noggrannhet på 98.84% för att estimera antalet AGVer som det finns behov av givet kapacitetsbehovet från maskiner/stationer och den tillgängliga kapaciteten hos AGVerna som jobbar på produktionsanläggningen.   Slutsatser:  Resultatet av tillvägagångssättet som använts i denna studie, att analysera kapacitetsbehovet i produktionsanläggningen och den tillgängliga kapaciteten hos AGVerna, visade sig vara noggrann för att estimera det optimala behovet av AGVer. Detta innebär att optimeringsmodellen som presenteras i denna studie och som tar hänsyn till kapacitetbehovet snarare än de specifika layoutegenskaperna kommer göra det möjligt för användarna att kunna uppfylla de förändrade kraven på massanpassning. Användaren kommer kunna använda sin prognos på efterfrågan och i samspel med användning av optimeringsmodellen presenterad i denna studie kunna estimera det optimala antalet AGVer som det finns behov av.