9,728 research outputs found
Hybrid Materialization in a Disk-Based Column-Store
In column-oriented query processing, a materialization strategy determines
when lightweight positions (row IDs) are translated into tuples. It is an
important part of column-store architecture, since it defines the class of
supported query plans, and, therefore, impacts the overall system performance.
In this paper we continue investigating materialization strategies for a
distributed disk-based column-store. We start with demonstrating cases when
existing approaches impose fundamental limitations on the resulting system
performance. Then, in order to address them, we propose a new hybrid
materialization model. The main feature of hybrid materialization is the
ability to manipulate both positions and values at the same time. This way,
query engine can flexibly combine advantages of all the existing strategies and
support a new class of query plans. Moreover, hybrid materialization allows the
query engine to flexibly customize the materialization policy of individual
attributes.
We describe our vision of how hybrid materialization can be implemented in a
columnar system. As an example, we use PosDB~ -- a distributed, disk-based
column-store. We present necessary data structures, the internals of a hybrid
operator, and describe the algebra of such operators. Based on this
implementation, we evaluate performance of late, ultra-late, and hybrid
materialization strategies in several scenarios based on TPC-H queries. Our
experiments demonstrate that hybrid materialization is almost two times faster
than its counterparts, while providing a more flexible query model
Examples of works to practice staccato technique in clarinet instrument
Klarnetin staccato tekniğini güçlendirme aşamaları eser çalışmalarıyla uygulanmıştır. Staccato
geçişlerini hızlandıracak ritim ve nüans çalışmalarına yer verilmiştir. Çalışmanın en önemli amacı
sadece staccato çalışması değil parmak-dilin eş zamanlı uyumunun hassasiyeti üzerinde de
durulmasıdır. Staccato çalışmalarını daha verimli hale getirmek için eser çalışmasının içinde etüt
çalışmasına da yer verilmiştir. Çalışmaların üzerinde titizlikle durulması staccato çalışmasının ilham
verici etkisi ile müzikal kimliğe yeni bir boyut kazandırmıştır. Sekiz özgün eser çalışmasının her
aşaması anlatılmıştır. Her aşamanın bir sonraki performans ve tekniği güçlendirmesi esas alınmıştır.
Bu çalışmada staccato tekniğinin hangi alanlarda kullanıldığı, nasıl sonuçlar elde edildiği bilgisine
yer verilmiştir. Notaların parmak ve dil uyumu ile nasıl şekilleneceği ve nasıl bir çalışma disiplini
içinde gerçekleşeceği planlanmıştır. Kamış-nota-diyafram-parmak-dil-nüans ve disiplin
kavramlarının staccato tekniğinde ayrılmaz bir bütün olduğu saptanmıştır. Araştırmada literatür
taraması yapılarak staccato ile ilgili çalışmalar taranmıştır. Tarama sonucunda klarnet tekniğin de
kullanılan staccato eser çalışmasının az olduğu tespit edilmiştir. Metot taramasında da etüt
çalışmasının daha çok olduğu saptanmıştır. Böylelikle klarnetin staccato tekniğini hızlandırma ve
güçlendirme çalışmaları sunulmuştur. Staccato etüt çalışmaları yapılırken, araya eser çalışmasının
girmesi beyni rahatlattığı ve istekliliği daha arttırdığı gözlemlenmiştir. Staccato çalışmasını yaparken
doğru bir kamış seçimi üzerinde de durulmuştur. Staccato tekniğini doğru çalışmak için doğru bir
kamışın dil hızını arttırdığı saptanmıştır. Doğru bir kamış seçimi kamıştan rahat ses çıkmasına
bağlıdır. Kamış, dil atma gücünü vermiyorsa daha doğru bir kamış seçiminin yapılması gerekliliği
vurgulanmıştır. Staccato çalışmalarında baştan sona bir eseri yorumlamak zor olabilir. Bu açıdan
çalışma, verilen müzikal nüanslara uymanın, dil atış performansını rahatlattığını ortaya koymuştur.
Gelecek nesillere edinilen bilgi ve birikimlerin aktarılması ve geliştirici olması teşvik edilmiştir.
Çıkacak eserlerin nasıl çözüleceği, staccato tekniğinin nasıl üstesinden gelinebileceği anlatılmıştır.
Staccato tekniğinin daha kısa sürede çözüme kavuşturulması amaç edinilmiştir. Parmakların
yerlerini öğrettiğimiz kadar belleğimize de çalışmaların kaydedilmesi önemlidir. Gösterilen azmin ve
sabrın sonucu olarak ortaya çıkan yapıt başarıyı daha da yukarı seviyelere çıkaracaktır
Estudo da remodelagem reversa miocárdica através da análise proteómica do miocárdio e do líquido pericárdico
Valve replacement remains as the standard therapeutic option for aortic
stenosis patients, aiming at abolishing pressure overload and triggering
myocardial reverse remodeling. However, despite the instant hemodynamic
benefit, not all patients show complete regression of myocardial hypertrophy,
being at higher risk for adverse outcomes, such as heart failure. The current
comprehension of the biological mechanisms underlying an incomplete reverse
remodeling is far from complete. Furthermore, definitive prognostic tools and
ancillary therapies to improve the outcome of the patients undergoing valve
replacement are missing. To help abridge these gaps, a combined myocardial
(phospho)proteomics and pericardial fluid proteomics approach was followed,
taking advantage of human biopsies and pericardial fluid collected during
surgery and whose origin anticipated a wealth of molecular information
contained therein.
From over 1800 and 750 proteins identified, respectively, in the myocardium
and in the pericardial fluid of aortic stenosis patients, a total of 90 dysregulated
proteins were detected. Gene annotation and pathway enrichment analyses,
together with discriminant analysis, are compatible with a scenario of increased
pro-hypertrophic gene expression and protein synthesis, defective ubiquitinproteasome system activity, proclivity to cell death (potentially fed by
complement activity and other extrinsic factors, such as death receptor
activators), acute-phase response, immune system activation and fibrosis.
Specific validation of some targets through immunoblot techniques and
correlation with clinical data pointed to complement C3 β chain, Muscle Ring
Finger protein 1 (MuRF1) and the dual-specificity Tyr-phosphorylation
regulated kinase 1A (DYRK1A) as potential markers of an incomplete
response. In addition, kinase prediction from phosphoproteome data suggests
that the modulation of casein kinase 2, the family of IκB kinases, glycogen
synthase kinase 3 and DYRK1A may help improve the outcome of patients
undergoing valve replacement. Particularly, functional studies with DYRK1A+/-
cardiomyocytes show that this kinase may be an important target to treat
cardiac dysfunction, provided that mutant cells presented a different response
to stretch and reduced ability to develop force (active tension).
This study opens many avenues in post-aortic valve replacement reverse
remodeling research. In the future, gain-of-function and/or loss-of-function
studies with isolated cardiomyocytes or with animal models of aortic bandingdebanding will help disclose the efficacy of targeting the surrogate therapeutic
targets. Besides, clinical studies in larger cohorts will bring definitive proof of
complement C3, MuRF1 and DYRK1A prognostic value.A substituição da válvula aórtica continua a ser a opção terapêutica de
referência para doentes com estenose aórtica e visa a eliminação da
sobrecarga de pressão, desencadeando a remodelagem reversa miocárdica.
Contudo, apesar do benefício hemodinâmico imediato, nem todos os pacientes
apresentam regressão completa da hipertrofia do miocárdio, ficando com maior
risco de eventos adversos, como a insuficiência cardíaca. Atualmente, os
mecanismos biológicos subjacentes a uma remodelagem reversa incompleta
ainda não são claros. Além disso, não dispomos de ferramentas de
prognóstico definitivos nem de terapias auxiliares para melhorar a condição
dos pacientes indicados para substituição da válvula. Para ajudar a resolver
estas lacunas, uma abordagem combinada de (fosfo)proteómica e proteómica
para a caracterização, respetivamente, do miocárdio e do líquido pericárdico
foi seguida, tomando partido de biópsias e líquidos pericárdicos recolhidos em
ambiente cirúrgico.
Das mais de 1800 e 750 proteínas identificadas, respetivamente, no miocárdio
e no líquido pericárdico dos pacientes com estenose aórtica, um total de 90
proteínas desreguladas foram detetadas. As análises de anotação de genes,
de enriquecimento de vias celulares e discriminativa corroboram um cenário de
aumento da expressão de genes pro-hipertróficos e de síntese proteica, um
sistema ubiquitina-proteassoma ineficiente, uma tendência para morte celular
(potencialmente acelerada pela atividade do complemento e por outros fatores
extrínsecos que ativam death receptors), com ativação da resposta de fase
aguda e do sistema imune, assim como da fibrose.
A validação de alguns alvos específicos através de immunoblot e correlação
com dados clínicos apontou para a cadeia β do complemento C3, a Muscle
Ring Finger protein 1 (MuRF1) e a dual-specificity Tyr-phosphoylation
regulated kinase 1A (DYRK1A) como potenciais marcadores de uma resposta
incompleta. Por outro lado, a predição de cinases a partir do fosfoproteoma,
sugere que a modulação da caseína cinase 2, a família de cinases do IκB, a
glicogénio sintase cinase 3 e da DYRK1A pode ajudar a melhorar a condição
dos pacientes indicados para intervenção. Em particular, a avaliação funcional
de cardiomiócitos DYRK1A+/- mostraram que esta cinase pode ser um alvo
importante para tratar a disfunção cardíaca, uma vez que os miócitos mutantes
responderam de forma diferente ao estiramento e mostraram uma menor
capacidade para desenvolver força (tensão ativa).
Este estudo levanta várias hipóteses na investigação da remodelagem reversa.
No futuro, estudos de ganho e/ou perda de função realizados em
cardiomiócitos isolados ou em modelos animais de banding-debanding da
aorta ajudarão a testar a eficácia de modular os potenciais alvos terapêuticos
encontrados. Além disso, estudos clínicos em coortes de maior dimensão
trarão conclusões definitivas quanto ao valor de prognóstico do complemento
C3, MuRF1 e DYRK1A.Programa Doutoral em Biomedicin
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Antecedents of business intelligence system use
This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.Organisational reliance on information has become vital for organisational competitiveness. With increasing data volumes, Business Intelligence (BI) becomes a cornerstone of the decision-support system. However, employee resistance to use Business Intelligence Systems (BIS) is evident. This creates a problem to organisations in realising the benefits of BIS. It is thus important to study the enablers of sustained use of BIS amongst employees.
This thesis identifies existing theories that can be used to study BI system use. It integrates and extends technology use theories through a framework focusing on Business Intelligence System Use (BISU). Empirical research is then conducted in Kuwait’s telecom and banking industries through a close-ended, self-administered questionnaire using a five-point Likert scale. Responses were received from 211 BI users. The data was analysed using SmartPLS to study the convergent and discriminant validity and reliability. Partial least squares structural equation modelling (PLS-SEM) was used to study the direct and indirect relationships between constructs and answer the hypotheses. In addition to SmartPLS, SPSS was used for descriptive analysis.
The results indicated that UTAUT factors consisting of performance expectancy, effort expectancy and social influence positively impact BI system use. Voluntariness of use was found to positively moderate the relationship between social influence and BI system use. Furthermore, BI system quality positively impacts both performance expectancy and effort expectancy. The BI user’s self-efficacy also positively impacts effort expectancy. In addition, social influence was found to be positively influenced by organisational factors, namely top management support and information culture.
The findings of this research contribute to literature by determining and quantifying the factors that influence BISU through the lens of employee perspectives. This thesis also explains how employees’ object-based beliefs about BI affect their behavioural beliefs, which in turn impact BISU. Limitations of this research include the omission of UTAUT’s facilitating conditions and the limited variance of respondent demographics
Maternal obesity and offspring metabolic outcomes : focus on sex differences
Obesity is a worldwide health issue affecting all ages and both sexes, and its prevalence is progressively increasing among adults and children. The predisposition to metabolic complications caused by obesity is sex dependent. Intrauterine environmental changes such as overnutrition before conception, during pregnancy and lactation, have been recognized as factors predisposing offspring to metabolic complications later in life. Interestingly, sex specific differences in the adaptation to maternal obesity have been observed, but the underlying mechanism is still unclear.
The general aim of the current thesis was to investigate the sexual dimorphism in metabolism during obesity and to elucidate the sex-dependent impact of maternal obesity on offspring, with particular emphasis on liver and adipose tissue metabolism. For this purpose, we used a combination of both in vivo and ex vivo advanced techniques, including nuclear magnetic resonance, transcriptomic and lipidomic analysis in key tissues regulating lipid metabolism; namely liver, subcutaneous (SAT), visceral (VAT), and brown (BAT) adipose tissues.
In PAPER I we investigated the sex-specific response to obesity-induced metabolic syndrome and aimed to identify sex-specific characteristic lipid molecular species in liver, VAT and SAT in female and male ob/ob mice. We showed that upon overfeeding, males accumulated less total fat with a distribution towards more VAT and less SAT compared to females. Males presented higher lipid accumulation in liver and circulating lipids and were more insulin resistant compared to females. Males induced inflammation in adipose tissue while females presented higher pro-inflammatory markers in liver in response to overeating. Furthermore, the fatty acid and triglyceride profile in both adipose depots were diverse between the two sexes. Males had longer chain fatty acids and triglycerides compared to females. Additionally, here we showed that the hepatic phospholipid profile was sex- dependent with more abundant lipotoxic fatty acids in males than in females. The fatty acid and triglyceride synthesis pathways was highly sex-dependent at the transcriptional level, which may contribute to the sex-dependent metabolic profile. Our results provide a unique description of sexual dimorphic lipid profile in metabolic organs corelated to obesity and could be a contribution for future and more precise treatment of obesity.
In PAPER II we investigated the sex-dependent long-term adaptation to maternal obesity in offspring on control diet after weaning with focus on the liver. Males from obese mothers had higher adiposity and were more insulin resistant at short-term but on the long-term post- weaning control diet reversed these effects. Our results demonstrated that maternal obesity influenced differently the hepatic lipid synthesis pathways in female and male offspring and caused a more dysfunctional metabolic profile in males than in females. We observed a sex- specific alteration in the fatty acid, triglyceride, and phospholipid profile together with a sex- specific transcriptional regulation of metabolic pathways in liver.
In PAPER III we explored how maternal obesity can predispose white and brown adipose tissue in obese offspring to metabolic dysfunctions in the long-term. We showed that in utero high fat diet environment in offspring on obesogenic diet, altered the triglyceride profile between adipose depots and sexes. Maternal obesity caused changes in triglyceride composition in SAT and BAT and increased the thermogenic activity in BAT in female offspring only. In males, maternal obesity caused whitening of BAT and increased the adipocyte number in VAT and generally impaired their metabolic profile. Our results show that maternal obesity programs the transcriptional activity in white and brown adipose tissue in a sex- and adipose depot- dependent manner.
The PAPER IV is a continuation of the study in PAPER III where we investigated the sex- dependent metabolic response to maternal obesity in offspring on obesogenic diet with special focus on liver. Here we showed that maternal obesity caused hepatic insulin resistance in females, and hepatic steatosis and inflammation in males. Moreover, we observed that maternal obesity caused changes in the transcriptional activity and triglyceride profile in female offspring that might prevent the adverse effects of in utero exposure to obesity.
In conclusion, our results demonstrate that there is an in utero metabolic programming in offspring born from obese mothers that is sex and tissue specific. Given that the prevalence of obesity among women of reproductive age is increasing drastically, it is crucial to better define the in utero changes in offspring and its consequences. An important outcome of studying the sex differences in offspring metabolism is to understand the underlying mechanisms and paved the way to precision medicine to develop potential interventions and tackle future diseases in subsequent generations
'Exarcheia doesn't exist': Authenticity, Resistance and Archival Politics in Athens
My thesis investigates the ways people, materialities and urban spaces interact to form affective ecologies and produce historicity. It focuses on the neighbourhood of Exarcheia, Athens’ contested political topography par excellence, known for its production of radical politics of discontent and resistance to state oppression and eoliberal capitalism. Embracing Exarcheia’s controversial status within Greek vernacular, media and state discourses, this thesis aims to unpick the neighbourhoods’ socio-spatial assemblage imbued with affect and formed through the numerous (mis)understandings and (mis)interpretations rooted in its turbulent political history. Drawing on theory on urban spaces, affect, hauntology and archival politics, I argue for Exarcheia as an unwavering archival space composed of affective chronotopes – (in)tangible loci that defy space and temporality. I posit that the interwoven narratives and materialities emerging in my fieldwork are persistently – and perhaps obsessively – reiterating themselves and remaining imprinted on the neighbourhood’s landscape as an incessant reminder of violent histories that the state often seeks to erase and forget. Through this analysis, I contribute to understandings of place as a primary ethnographic ‘object’ and the ways in which place forms complex interactions and relationships with social actors, shapes their subjectivities, retains and bestows their memories and senses of historicity
The Future of Work and Digital Skills
The theme for the events was "The Future of Work and Digital Skills". The 4IR caused a
hollowing out of middle-income jobs (Frey & Osborne, 2017) but COVID-19 exposed the digital gap as survival depended mainly on digital infrastructure and connectivity. Almost overnight, organizations that had not invested in a digital strategy suddenly realized the need for such a strategy and the associated digital skills. The effects have been profound for those who struggled to adapt, while those who stepped up have reaped quite the reward.Therefore, there are no longer certainties about what the world will look like in a few years from now. However, there are certain ways to anticipate the changes that are occurring and plan on how to continually adapt to an increasingly changing world. Certain jobs will soon be lost and will not come back; other new jobs will however be created. Using data science and other predictive sciences, it is possible to anticipate, to the extent possible, the rate at which certain jobs will be replaced and new jobs created in different industries. Accordingly, the collocated events sought to bring together government, international organizations, academia, industry, organized labour and civil society to deliberate on how these changes are occurring in South Africa, how fast they are occurring and what needs to change in order to prepare society for the changes.Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ)
British High Commission (BHC)School of Computin
The interpretation of Islam and nationalism by the elite through the English language media in Pakistan.
The media is constructed and interpreted through what people 'know'. That knowledge is, forthe most part, created through day to day experiences. In Pakistan, Islam and nationalism aretwo components of this social knowledge which are intrinsically tied to the experiences of thePakistani people. Censorship and selection are means through which this knowledge isarticulated and interpreted.General conceptions of partially shared large scale bodies of knowledge and ideas reinforce,and are reinforced by, general medium of mass communication: the print and electronic media.Focusing on the govermnent, media institutions and Pakistani elites, I describe and analyse thedifferent, sometimes conflicting, interpretations of Islam and Pakistani nationalism manifest inand through media productions presented in Pakistan.The media means many things, not least of which is power. It is the media as a source ofpower that is so frequently controlled, directed and manipulated. The terminology may beslightly different according to the context within which one is talking - propaganda, selection,etc. - but ultimately it comes down to the same thing - censorship. Each of the three groups:government, media institutions and Pakistani elites - have the power to interpret and censormedia content and consideration must be taken of each of the other power holders consequentlyrestricting the power of each group in relation to the other two. The processes of thismanipulation and their consequences form the major themes of this thesis
Statistical Learning for Gene Expression Biomarker Detection in Neurodegenerative Diseases
In this work, statistical learning approaches are used to detect biomarkers for neurodegenerative diseases (NDs). NDs are becoming increasingly prevalent as populations age, making understanding of disease and identification of biomarkers progressively important for facilitating early diagnosis and the screening of individuals for clinical trials. Advancements in gene expression profiling has enabled the exploration of disease biomarkers at an unprecedented scale. The work presented here demonstrates the value of gene expression data in understanding the underlying processes and detection of biomarkers of NDs. The value of novel approaches to previously collected -omics data is shown and it is demonstrated that new therapeutic targets can be identified. Additionally, the importance of meta-analysis to improve power of multiple small studies is demonstrated. The value of blood transcriptomics data is shown in applications to researching NDs to understand underlying processes using network analysis and a novel hub detection method. Finally, after demonstrating the value of blood gene expression data for investigating NDs, a combination of feature selection and classification algorithms were used to identify novel accurate biomarker signatures for the diagnosis and prognosis of Parkinson’s disease (PD) and Alzheimer’s disease (AD). Additionally, the use of feature pools based on previous knowledge of disease and the viability of neural networks in dimensionality reduction and biomarker detection is demonstrated and discussed. In summary, gene expression data is shown to be valuable for the investigation of ND and novel gene biomarker signatures for the diagnosis and prognosis of PD and AD
Measuring RocksDB performance and adaptive sampling for model estimation
This thesis focuses on two topics, namely statistical learning and the prediction of key performance indicators in the performance evaluation of a storage engine.
The part on statistical learning presents a novel algorithm adjusting the sampling size for the Monte Carlo approximation of the function to be minimized, allowing a reduction of the true function at a given probability and this, at a lower numerical cost.
The sampling strategy is embedded in a trust-region algorithm, using the Fisher Information matrix, also called BHHH approximation, to approximate the Hessian matrix. The sampling strategy is tested on a logit model generated from synthetic data.
Numerical results exhibit a significant reduction in the time required to optimize the model when an adequate smoothing is applied to the function.
The key performance indicator prediction part describes a novel strategy to select better settings for RocksDB that optimize its throughput, using the log files to analyze and identify suboptimal parameters, opening the possibility to greatly accelerate modern storage engine tuning.Ce mémoire s’intéresse à deux sujets, un relié à l’apprentisage statistique et le second à la
prédiction d’indicateurs de performance dans un système de stockage de type clé-valeur.
La partie sur l’apprentissage statistique développe un algorithme ajustant la taille
d’échantillonnage pour l’approximation Monte Carlo de la fonction à minimiser, permettant
une réduction de la véritable fonction avec une probabilité donnée, et ce à un coût
numérique moindre. La stratégie d’échantillonnage est développée dans un contexte de région
de confiance en utilisant la matrice d’information de Fisher, aussi appelée approximation
BHHH de la matrice hessienne. La stratégie d’échantillonnage est testée sur un modèle logit
généré à partir de données synthétiques suivant le même modèle. Les résultats numériques
montrent une réduction siginificative du temps requis pour optimiser le modèle lorsqu’un
lissage adéquat est appliqué.
La partie de prédiction d’indicateurs de performance décrit une nouvelle approche pour
optimiser la vitesse maximale d’insertion de paire clé-valeur dans le système de stockage
RocksDB. Les fichiers journaux sont utilisés pour identifier les paramètres sous-optimaux du
système et accélérer la recherche de paramètres optimaux
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