bluuebunny/crossref_metadata_2025 huggingface dataset:
A cellular process that includes asymmetric cytokinesis remodels the dorsal tracheal branches in Drosophila larvae
Authors: Denes Alexandru Stefan , Kanca Oguz , Affolter Markus
Published: May 2015

Tubular networks are central to the structure and function of many organs, such as the vertebrate lungs or the Drosophila tracheal system. Their component epithelial cells are able to proliferate and to undergo complex morphogenetic movements, while maintaining their barrier function. Little is known about the details of the mitotic process in tubular epithelia. Our study presents a comprehensive model of cellular remodeling and proliferation in the dorsal branches of third-instar Drosophila larvae. Through a combination of immunostaining and novel live imaging techniques, we identify the key steps in the transition from a unicellular to a multicellular tube. Junctional remodeling precedes mitosis and, as the cells divide, new junctions are formed through several variations of what we refer to as ‘asymmetric cytokinesis’. Depending on the spacing of cells along the dorsal branch, mitosis can occur either before or after the transition to a multicellular tube. In both instances, cell separation is accomplished through asymmetric cytokinesis, a process that is initiated by the ingression of the cytokinetic ring. Unequal cell compartments are a possible but rare outcome of completing mitosis through this mechanism. We also found that the Dpp signaling pathway is required but not sufficient for cell division in the dorsal branches.
Girdin-mediated interactions between cadherin and the actin cytoskeleton are required for epithelial morphogenesis in Drosophila
Authors: Houssin Elise , Tepass Ulrich , Laprise Patrick
Published: May 2015

E-cadherin-mediated cell-cell adhesion is fundamental for epithelial tissue morphogenesis, physiology and repair. E-cadherin is a core transmembrane constituent of the zonula adherens (ZA), a belt-like adherens junction located at the apicolateral border in epithelial cells. The anchorage of ZA components to cortical actin filaments strengthens cell-cell cohesion and allows for junction contractility, which shapes epithelial tissues during development. Here, we report that the cytoskeletal adaptor protein Girdin physically and functionally interacts with components of the cadherin-catenin complex during Drosophila embryogenesis. Fly Girdin is broadly expressed throughout embryonic development and enriched at the ZA in epithelial tissues. Girdin associates with the cytoskeleton and co-precipitates with the cadherin-catenin complex protein α-Catenin (α-Cat). Girdin mutations strongly enhance adhesion defects associated with reduced DE-cadherin (DE-Cad) expression. Moreover, the fraction of DE-Cad molecules associated with the cytoskeleton decreases in the absence of Girdin, thereby identifying Girdin as a positive regulator of adherens junction function. Girdin mutant embryos display isolated epithelial cell cysts and rupture of the ventral midline, consistent with defects in cell-cell cohesion. In addition, loss of Girdin impairs the collective migration of epithelial cells, resulting in dorsal closure defects. We propose that Girdin stabilizes epithelial cell adhesion and promotes morphogenesis by regulating the linkage of the cadherin-catenin complex to the cytoskeleton.
The juxtamembrane region of synaptotagmin 1 interacts with dynamin 1 and regulates vesicle fission during compensatory endocytosis in endocrine cells
Authors: McAdam Robyn L. , Varga Kelly T. , Jiang Zhongjiao , Young Fiona B. , Blandford Vanessa , McPherson Peter S. , Gong Liang-Wei , Sossin Wayne S.
Published: May 2015

Synaptotagmin 1 (Syt1) is a synaptic vesicle protein that is important for the kinetics of both exocytosis and endocytosis, and is thus a candidate molecule to link these two processes. Although the tandem Ca2+-binding C2 domains of Syt1 have important roles in exocytosis and endocytosis, the function of the conserved juxtamembrane (jxm) linker region has yet to be determined. We now demonstrate that the jxm region of Syt1 interacts directly with the pleckstrin homology (PH) domain of the endocytic protein dynamin 1. By using cell-attached capacitance recordings with millisecond time resolution to monitor clathrin-mediated endocytosis of single vesicles in neuroendocrine chromaffin cells, we find that loss of this interaction prolongs the lifetime of the fission pore leading to defects in the dynamics of vesicle fission. These results indicate a previously undescribed interaction between two major regulatory proteins in the secretory vesicle cycle and that this interaction regulates endocytosis.
Oxygen limited thermal tolerance is seen in a plastron breathing insect, and can be induced in a bimodal gas exchanger
Authors: Verberk Wilco C.E.P. , Bilton David T.
Published: May 2015

Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in gas exchange mechanism could reconcile the discrepancies found in previous studies. Here we test this suggestion by comparing the behavior of related insect taxa with different gas exchange mechanisms, with and without access to air. We demonstrate oxygen limited thermal tolerance in air-breathing adults of the plastron exchanging water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal gas exchanger, did not exhibit such oxygen limited thermal tolerance and relied increasingly on aerial gas exchange with warming. Intriguingly, however, when denied access to air, oxygen limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life history stages in these insects, with nymphs employing the same gas exchange mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits.
Catalytic Property of SAPO-18/SAPO-34 Intergrown Molecular Sieve in 1-Butene Cracking
Authors: Hu Yunfeng , Chen Huan , Hu Ying , Deng Jun , Lv Zhongyuan , Zhang Hongsheng
Published: May 2015

SAPO-18 (AEI)/SAPO-34 (CHA) intergrown molecular sieve (AC-HS) was prepared by hydrothermal synthesis. As evidenced by XRD, SEM, BET, and NH3-TPD analyses, AC-HS had unconventional physical and chemical properties such as crystal structure, crystal morphology, surface area, and acidity. Compared with SAPO-18 and SAPO-34 mechanical mixture (AC-MM), AC-HS showed better initial activity and higher selectivities of C3H6 and C2H4 + C3H6 in 1-butene cracking under the reaction conditions. The selectivities of C3H6 and C2H4 + C3H6 reached approximately 61.09% and 90.28%, respectively, when conversion was >70%. Regarding the SAPO-18/SAPO-34 intergrown molecular sieve, the relationship of acidity and catalytic performance was not close in 1-butene cracking, and the intergrowth structure should play a significant important role in the selectivity of olefins.
Preferential Removal of Perchlorate Ion from Water Using Self-assembled Constructions of Cationic 3D Coordination Frameworks with Methylene Units
Authors: Murakami Aya , Yamanishi Katsunori , Sone Eriko , Kondo Mitsuru
Published: May 2015

Four new Co(II)-coordination polymers have been prepared from treatments of a CoII source with bis[2-(1H-imidazol-1-yl)ethyl]ether (bie) or 1,5-bis(1H-imidazol-1-yl)pentane (bipen), which are bis-imidazole-type ligands with hydrophobic polymethylene units. Structural characterizations have shown that their compounds create hydrophobic cavities for anions in their cationic 3D coordination frameworks. The self-assembled construction of the frameworks in aqueous solutions containing various inorganic anions trapped perchlorate ion selectively in the cavities. Because the product is insoluble in water, perchlorate ion was selectively removed from the aqueous solutions.
Charge Distributions of Gas-phase SN2 Reactions: ABEEM-σπ Method Compared with Potential Acting on an Electron in a Molecule
Authors: Ding Yanli , Han Xiaojing , Sun Changliang , Mu Jirong
Published: May 2015

The SN2 reactions at C and Si have been investigated by ABEEM-σπ method compared with the potential acting on an electron in a molecule (PAEM). The ABEEM-σπ model demonstrates the charge distributions of the atom region, bond region, and lone-pair electron region during the course of the reaction. The differences between title reactions have been demonstrated. Studies indicate that there are good linear correlations among the charges obtained by ABEEM-σπ method, the force constants, the relative energies, the ionization potentials, etc. This study enhances our understanding of the electron transfer from the nucleophile to the leaving group.
Industrial Policy and the Management of Technological Development of the Industrial Complex of Russia in Conditions of Forced Autarchy
Authors: Быстров  , Bystrov Andrey , Свирчевский  , Svirchevskiy Vadim , Юсим  , Yusim Vyacheslav
Published: May 2015

As the history shows, those states are to survive, which within periods of

crises and external threats are able to put aside outworn stereotypes of their

previous existence. In the XXI century new challenges have put Russia to the

task of accelerating its technological and economic development; otherwise

Russia is to give up its status of a world’s great power. As it is quite clear

now, the efficient economy — is the economy based on intense use of new

knowledge. It is also clear enough, that the package of decisions, aimed to

provide transition to the efficient economy can be worked out on the basis

of ingenuous and unconventional decisions, especially since the prevailing

conditions of a present day seem to be extremely unfavorable.
Company Employees’ Labor Motivation As an Ongoing Cyclic Process: Analysis of Theories and How to Apply These in Practice
Authors: Альхименко  , Alkhimenko O.
Published: May 2015

The category of labor motivation is analyzed along with its features. It is also

considered, how this category relates to such economic terms, as “incentives”,

“motive”, “needs”, “interest”. The author’s interpretation of how to motivate

personnel together with detailed stage by stage description of the process

are given. Further, the arguments, proving that the labor motivation should

be classified as the ongoing cyclic process of labor activities are presented.

Considerable attention is given to theories of labor motivation, developed

both by national and foreign economists, and how these theories can be

applied in practice within this country’s realities. Conclusions made by the

author can be useful in practical work of present-day companies’ managers.
Revisiting the Issue of Economic Growth and Development...
Authors: Каленов  , Kalenov Oleg
Published: May 2015

The paper considers several theories concerning economic growth and

development, and makes an attempt to classify these theories, based on

growth and development driving forces. The author suggests arguments to

prove his proprietary approach to defining the concepts of “economic growth”

and “ economic development” and highlights specifics of the said concepts.
Model Counting of Monotone Conjunctive Normal Form Formulas with Spectra
Authors: Vaisman Radislav , Strichman Ofer , Gertsbakh Ilya
Published: May 2015

Model counting is the #P problem of counting the number of satisfying solutions of a given propositional formula. Here we focus on a restricted variant of this problem, where the input formula is monotone (i.e., there are no negations). A monotone conjunctive normal form (CNF) formula is sufficient for modeling various graph problems, e.g., the vertex covers of a graph. Even for this restricted case, there is no known efficient approximation scheme. We show that the classical Spectra technique that is widely used in network reliability can be adapted for counting monotone CNF formulas. We prove that the proposed algorithm is logarithmically efficient for random monotone 2-CNF instances. Although we do not prove the efficiency of Spectra for k-CNF where k > 2, our experiments show that it is effective in practice for such formulas.
A Scenario Decomposition Algorithm for Stochastic Programming Problems with a Class of Downside Risk Measures
Authors: Rysz Maciej , Vinel Alexander , Krokhmal Pavlo , Pasiliao Eduardo L.
Published: May 2015

We present an efficient scenario decomposition algorithm for solving large-scale convex stochastic programming problems that involve a particular class of downside risk measures. The considered risk functionals encompass coherent and convex measures of risk that can be represented as an infimal convolution of a convex certainty equivalent, and include well-known measures, such as conditional value-at-risk, as special cases. The resulting structure of the feasible set is then exploited via iterative solving of relaxed problems, and it is shown that the number of iterations is bounded by a parameter that depends on the problem size. The computational performance of the developed scenario decomposition method is illustrated on portfolio optimization problems involving two families of nonlinear measures of risk, the higher-moment coherent risk measures, and log-exponential convex risk measures. It is demonstrated that for large-scale nonlinear problems the proposed approach can provide up to an order-of-magnitude improvement in computational time in comparison to state-of-the-art solvers, such as CPLEX, Gurobi, and MOSEK.
Small Animal Review
Authors: Tennant Bryn
Published: May 2015

Introduction:

Histological grading of feline mammary carcinomas can provide an accurate estimation of survival times.
Changes in cardiac morphology seen on echocardiography
Authors: Pigott Jane , Martin Mike
Published: May 2015

The use of echocardiography in general practice can be an effective tool in the diagnosis and management of cardiac cases. Although the use of measurement to assess cardiac pathology on echo is a valuable method in the hands of the experienced echocardiographer, its use in first opinion practice may be limited. This article highlights the value of subjective assessment as a simple and effective tool when the practitioner judges the heart to be clearly normal or abnormal. Using a step-by-step approach to assess each chamber in the readily obtained right-sided long axis four chambered view, a logical list of differential diagnoses can be created.
Canine primary hypoadrenocorticism
Authors: Adamany Jessica , Dhumeaux Marc
Published: May 2015

Primary hypoadrenocorticism, also known as Addison's disease, is a relatively uncommon endocrinopathy with a reported prevalence of 0.06% to 0.28% in dogs ( Scott-Moncrieff, 2010 ). Although previously believed to be a well-described condition in veterinary medicine, the identification of cases of primary hypoadrenocorticism with normal electrolytes has revealed a paucity of literature in this area. Specialists are now focusing their attention on further characterising the variants of primary hypoadrenocorticism including signalment, presentation, and clinicopathologic abnormalities, as well as superior modalities to screen and diagnose the disease.
Pelvic fractures in cats
Authors: Perry Karen L
Published: May 2015

Pelvic fractures constitute 25% of fractures seen in cats and are usually the result of major trauma. Concomitant injuries are frequently present, which may involve multiple body systems, and management of these generally takes precedence as cats rarely die as a direct result of the pelvic fracture. Several criteria are used to establish whether an individual cat is a candidate for surgical or conservative management, but if surgery is to be performed this is best carried out within five days of the trauma where possible. When appropriate case selection is employed, the prognosis following either conservative or surgical management of pelvic fractures in cats is generally favourable
In-practice management of stress in cats and dogs — improving the welfare of companion animals and practice finances
Authors: Hargrave Claire
Published: May 2015

Stress-related behaviour problems remain the most common reason for the euthanasia, abandonment or rehoming of companion animals ( Overall, 2013 ). The aggressive and avoidance-related behaviours exhibited by companion animals that are overt responders to stress within the veterinary practice form a key factor in owners delaying or avoiding presenting companion animals for veterinary treatment ( Landsberg et al, 2013 ). The veterinary profession has access to the majority of these animals and their owners at the time when the young animals’ emotional and behavioural development is at its most sensitive to social and environmental influences, making the education of owners regarding stress, and its implications for their pet, a major responsibility of the veterinary team. The first article in this series explained the incidence and potential outcomes of stress on the companion animal. This article suggests practical interventions for the veterinary team. By demonstrating sensitivity to and effective management of stressed patients, the veterinary team become an effective teaching tool influencing owner behaviour towards their companion animals. 10.12968/coan.2015.20.5.292
School breakfast clubs – a fight for survival
Authors: Lepkowska Dorothy
Published: May 2015

Breakfast Clubs have become a core part of daily life for many schools, but are under threat due to squeezed school budgets. Dorothy Lepkowska looks at strategies for keeping them alive.
Tips on meeting the income generation challenge
Authors: Bannister Nick
Published: May 2015

The funding opportunities are there to help your school balance the books during an ongoing budget squeeze – as long as you do some serious groundwork first, ASCL's Val Andrew tells Nick Bannister.
What are Digital Leaders?
Authors: McKeown Sal
Published: May 2015

What are Digital Leaders? And what benefits can this idea bring to your school's ICT strategy and to your pupils' technology and wider skills, such as literacy and leadership? Sal McKeown finds out
Self-harm: What should school staff we aware of?
Authors: Mitchell Joanna
Published: May 2015

Self-harm is an increasing problem among children and young people and schools are on the front-line. Psychologist Dr Joanna Mitchell offers some advice on spotting the signs and how to respond
An exploratory study of child commercial sexual exploitation in the hospitality industry in the United States
Authors: Kalargyrou Valentini , Woods Robert
Published: May 2015

This study examines the phenomena of child sex trafficking and commercial sexual exploitation as well as how the hospitality industry can be proactive in fighting for human rights in the context of corporate social responsibility (CSR). Seven hospitality companies have signed End Child Prostitution and Trafficking (ECPAT)-USA’s Code of Conduct for the Protection of Children from Sexual Exploitation in Travel and Tourism, also referred to as The Code. The initiative of seven hospitality companies and the purpose of The Code is to provide awareness and tools to fight against the sexual exploitation of children in the hospitality and tourism contexts. Whether and how to become involved with this movement tests hospitality companies’ approach to strategic CSR. These companies can gain a competitive advantage by creating a safe and socially sustainable environment for their guests, employees and their community, as well as a good reputation by investing in strategic and long-term positive social responsibility activities related to combating child sex trafficking and commercial sexual exploitation.
A reconceptualization of gastronomy as relational and reflexive
Authors: Kesimoğlu Ayşegül
Published: May 2015

This article focuses on the increasing fashionableness of gastronomic forms: their ‘symbolic enhancement’, and the ensuing incorporation of their forms into tourism, policy, destination management and marketing. The symbolic (although also material) enhancement of gastronomy may also lead to its objectification rather than acknowledging that gastronomy is an abstraction, and something that is negotiated constantly amongst the members of a society. Unfortunately, the inadvertent consequence of some studies focusing on the promotion and management of gastronomy, with respect to tourism and destination management, has been the formalization of such a normative approach with a tendency to link gastronomy with the wider debates on heritage. This article proposes a different way of looking at gastronomy: one in which gastronomy is relational, reflexive and negotiable – not fixed. This is a multi-disciplinary approach that draws on sociological and cultural studies of ­tourism, gastronomy, identity, reflexivity and consumption.
Anomalous origin of the left vertebral artery in humans: A rare anatomical finding?
Authors: AragÃ£o JosÃ© Aderval , Claudino dos Santos JÃºlio CÃ©sar , Gama Cabral Dhayanna Rolemberg , Oliveira Filho Carlos Augusto de , Barros Henrique Pereira
Published: May 2015

Context: Anatomical and morphological variations of the aortic arch and its branches are important in relation to thoracic and neck surgery. However, developmental abnormalities of the vertebral arteries are generally considered to be very rare. They have mostly been described in single case reports or small series. Thus, there is a need for further knowledge as an aid in planning surgery on the aortic arch or endovascular interventions. Objective: To report on a case of anomalous origin in the left vertebral artery. Case report: In a male cadaver, a left vertebral artery with its origin in the aortic arch between the left common carotid and left subclavian arteries was observed. Its length was 120 mm, and its diameter was 5.5 mm. It entered the transverse foramen of the third cervical vertebra. Conclusion: Knowledge of the anatomical variation of the origin of the vertebral artery is important not only diagnostically but also in planning surgery on the aortic arch or endovascular interventions.
International Teaching Assistants’ Experiences in the U.S. Classrooms: Implications for Practice
Authors: Arshavskaya Ekaterina
Published: May 2015

Recently, a number of studies have examined the lived experiences of the international teaching assistants (ITAs) in the U.S. classrooms. The findings show that the ITAs face many challenges such as classroom management, instructional, linguistic, cultural and social challenges. Following this line of research, this interview-based study examined the lived experiences of a group of ITAs using a qualitative methodology. The qualitative approach was intentionally selected to add an interpretive stance to the quantitative analyses prevalent in the current research on the ITAs. The paper aims to: (1) to provide insights into the ITAs’ perspectives on their first semester of teaching in the U.S. including determining the challenges they face and (2) to consider possible revisions to existing ITAs’ preparation programs based on the ITAs’ own perspectives and a review of the available literature. This study contributes to the field by presenting information that has the potential to prompt future empirical investigations into educational cultures as they apply to novice instructors in international contexts and to inform and renew curricula for ITAs’ preparation programs at the U.S. universities.
Training final year students in data presentation skills with an iterative report-feedback cycle
Authors: Verkade Heather
Published: May 2015

Although practical laboratory activities are often considered the linchpin of science education, asking students to produce many large practical reports can be problematic Practical reports require diverse skills, and therefore do not focus the students’ attention on any one skill. They are also time-consuming to write and mark, limiting the speed at which feedback can be returned. To refocus students specifically on the skills of data presentation and interpretation I asked the students to produce a results figure, as would be found in a journal article, one for each of four practical topics. The students found this a challenge, but their skills improved markedly over the semester due to an efficient feedback cycle. Students were very engaged with this assessment, as it caused them to re-consider what they understood about the results of the practical. As this assessment is a small focused version of a practical report, it allows faster marking and return of practicals, and reduces the proportion of marks allocated to practicals, allowing more marks to be allocated to other components of the unit/class such as exams. This is therefore a successful method of focusing students’ attention on presenting and interpreting practical results, in an efficient and cost-effective manner.
Effects of Gamma Radiation (Co 60) in Cachaça containing grapes (Crimson)
Authors: Angelo Pires Juliana , Da Silva Delabio Aline , Prezotto Vicente Rafaela , Nalesso Costa Harder Marcia , Santos Silva Lucia Cristina Aparecida , Arthur Valter
Published: May 2015

The current study deals with cachaça irradiation in the presences of grapes, with the use of gamma radiation (Co 60) to evaluate its effects on the physical and chemical characteristics of this beverage. The research had as objective to assess the effects of irradiation in cachaças, in the extraction of compounds present in the pickled grapes in the cachaça. Samples were prepared with grapes type Crimson, in polypropylene bottles, with and without grapes. Both types of samples were irradiated with doses of 0 (control) and 300Gy. Later were performed physical and chemical analyzes (pH, titratable acidity, soluble solids) during a 5-day span after irradiation treatment. Significative statistical difference was noticed in titratable acidity of the samples that contained grapes, larger values when compared with pure samples. However, there was no statistical difference when comparing the pure beverage with control or the beverage containing grapes and control. For pH the values for the samples with grapes is statistically lower than the others. The results for soluble solids (ºBrix) displayed an increase on both types of samples comparing with their respective controls. In conclusion, the 300Gy dose was effective for increasing soluble solids quantity both in pure cachaças as in presences of grapes. Relating to pH and acidity, this dose shows interference when grapes are presents.

 

DOI: 10.14685/rebrapa.v6i1.199
An approach towards the study of symmetric queries
Authors: Gyssens Marc , Paredaens Jan , Van Gucht Dirk , Wijsen Jef , Wu Yuqing
Published: May 2015

Many data-intensive applications have to query a database that involves sequences of sets of objects. It is not uncommon that the order of the sets in such a sequence does not affect the result of the query. Such queries are called
symmetric.
In this paper, the authors wish to initiate research on symmetric queries.

Thereto, a data model is proposed in which a binary relation between objects and set names encodes set membership. On this data model, two query languages are introduced, QuineCALC and SyCALC. They are correlated in a manner that is made precise with the symmetric Boolean functions of Quine, respectively symmetric relational functions, on sequences of sets of given length. The latter do not only involve the Boolean operations union, intersection, and complement, but also projection and Cartesian product. Quine's characterization of symmetric Boolean functions in terms of incidence information is generalized to QuineCALC queries. In the process, an incidence-based normal form for QuineCALC queries is proposed.

Inspired by these desirable incidence-related properties of QuineCALC queries,
counting-only
queries are introduced as SyCALC queries for which the result only depends on incidence information. Counting-only queries are then characterized as quantified Boolean combinations of QuineCALC queries, and a normal form is proposed for them as well. Finally, it is shown that, while it is undecidable whether a SyCALC query is counting-only, it is decidable whether a counting-only query is a QuineCALC query.
Finding shortest paths on terrains by killing two birds with one stone
Authors: Kaul Manohar , Wong Raymond Chi-Wing , Yang Bin , Jensen Christian S.
Published: May 2015

With the increasing availability of terrain data, e.g., from aerial laser scans, the management of such data is attracting increasing attention in both industry and academia. In particular, spatial queries, e.g.,
k
-nearest neighbor and reverse nearest neighbor queries, in Euclidean and spatial network spaces are being extended to terrains. Such queries all rely on an important operation, that of finding shortest surface distances. However, shortest surface distance computation is very time consuming. We propose techniques that enable efficient computation of lower and upper bounds of the shortest surface distance, which enable faster query processing by eliminating expensive distance computations. Empirical studies show that our bounds are much tighter than the best-known bounds in many cases and that they enable speedups of up to 43 times for some well-known spatial queries.
The uncracked pieces in database cracking
Authors: Schuhknecht Felix Martin , Jindal Alekh , Dittrich Jens
Published: May 2015

Database cracking has been an area of active research in recent years. The core idea of database cracking is to create indexes adaptively and incrementally as a side-product of query processing. Several works have proposed different cracking techniques for different aspects including updates, tuple-reconstruction, convergence, concurrency-control, and robustness. However, there is a lack of any comparative study of these different methods by an independent group. In this paper, we conduct an experimental study on database cracking. Our goal is to critically review several aspects, identify the potential, and propose promising directions in database cracking. With this study, we hope to expand the scope of database cracking and possibly leverage cracking in database engines other than MonetDB.

We repeat several prior database cracking works including the core cracking algorithms as well as three other works on convergence (hybrid cracking), tuple-reconstruction (sideways cracking), and robustness (stochastic cracking) respectively. We evaluate these works and show possible directions to do even better. We further test cracking under a variety of experimental settings, including high selectivity queries, low selectivity queries, and multiple query access patterns. Finally, we compare cracking against different sorting algorithms as well as against different main-memory optimised indexes, including the recently proposed Adaptive Radix Tree (ART). Our results show that: (i) the previously proposed cracking algorithms are repeatable, (ii) there is still enough room to significantly improve the previously proposed cracking algorithms, (iii) cracking depends heavily on query selectivity, (iv) cracking needs to catch up with modern indexing trends, and (v) different indexing algorithms have different indexing signatures.
Probabilistic nearest neighbor queries on uncertain moving object trajectories
Authors: Niedermayer Johannes , Züfle Andreas , Emrich Tobias , Renz Matthias , Mamoulis Nikos , Chen Lei , Kriegel Hans-Peter
Published: May 2015

Nearest neighbor (NN) queries in trajectory databases have received significant attention in the past, due to their applications in spatio-temporal data analysis. More recent work has considered the realistic case where the trajectories are uncertain; however, only simple uncertainty models have been proposed, which do not allow for accurate probabilistic search. In this paper, we fill this gap by addressing probabilistic nearest neighbor queries in databases with uncertain trajectories modeled by stochastic processes, specifically the Markov chain model. We study three nearest neighbor query semantics that take as input a query state or trajectory
q
and a time interval, and theoretically evaluate their runtime complexity. Furthermore we propose a sampling approach which uses Bayesian inference to guarantee that sampled trajectories conform to the observation data stored in the database. This sampling approach can be used in Monte-Carlo based approximation solutions. We include an extensive experimental study to support our theoretical results.
Earth mover's distance based similarity search at scale
Authors: Tang Yu , U Leong Hou , Cai Yilun , Mamoulis Nikos , Cheng Reynold
Published: May 2015

Earth Mover's Distance (EMD), as a similarity measure, has received a lot of attention in the fields of multimedia and probabilistic databases, computer vision, image retrieval, machine learning, etc. EMD on multidimensional histograms provides better distinguishability between the objects approximated by the histograms (e.g., images), compared to classic measures like Euclidean distance. Despite its usefulness, EMD has a high computational cost; therefore, a number of effective filtering methods have been proposed, to reduce the pairs of histograms for which the exact EMD has to be computed, during similarity search. Still, EMD calculations in the refinement step remain the bottleneck of the whole similarity search process. In this paper, we focus on optimizing the refinement phase of EMD-based similarity search by (i) adapting an efficient min-cost flow algorithm (SIA) for EMD computation, (ii) proposing a dynamic distance bound, which can be used to terminate an EMD refinement early, and (iii) proposing a dynamic refinement order for the candidates which, paired with a concurrent EMD refinement strategy, reduces the amount of needless computations. Our proposed techniques are orthogonal to and can be easily integrated with the state-of-the-art filtering techniques, reducing the cost of EMD-based similarity queries by orders of magnitude.
A data- and workload-aware algorithm for range queries under differential privacy
Authors: Li Chao , Hay Michael , Miklau Gerome , Wang Yue
Published: May 2015

We describe a new algorithm for answering a given set of range queries under ε-differential privacy which often achieves substantially lower error than competing methods. Our algorithm satisfies differential privacy by adding noise that is adapted to the input data
and
to the given query set. We first privately learn a partitioning of the domain into buckets that suit the input data well. Then we privately estimate counts for each bucket, doing so in a manner well-suited for the given query set. Since the performance of the algorithm depends on the input database, we evaluate it on a wide range of real datasets, showing that we can achieve the benefits of data-dependence on both "easy" and "hard" databases.
Support the data enthusiast
Authors: Morton Kristi , Balazinska Magdalena , Grossman Dan , Mackinlay Jock
Published: May 2015

We present a vision of next-generation visual analytics services. We argue that these services should have three related capabilities: support visual and interactive data exploration as they do today, but also suggest relevant data to enrich visualizations, and facilitate the integration and cleaning of that data. Most importantly, they should provide all these capabilities seamlessly in the context of an uninterrupted data analysis cycle. We present the challenges and opportunities in building next-generation visual analytics services.
Rank join queries in NoSQL databases
Authors: Ntarmos Nikos , Patlakas Ioannis , Triantafillou Peter
Published: May 2015

Rank (i.e., top-
k
) join queries play a key role in modern analytics tasks. However, despite their importance and unlike centralized settings, they have been completely overlooked in cloud NoSQL settings. We attempt to fill this gap: We contribute a suite of solutions and study their performance comprehensively. Baseline solutions are offered using SQL-like languages (like Hive and Pig), based on MapReduce jobs. We first provide solutions that are based on specialized indices, which may themselves be accessed using either MapReduce or coordinator-based strategies. The first index-based solution is based on inverted indices, which are accessed with MapReduce jobs. The second index-based solution adapts a popular centralized rank-join algorithm. We further contribute a novel statistical structure comprising histograms and Bloom filters, which forms the basis for the third index-based solution. We provide (i) MapReduce algorithms showing how to build these indices and statistical structures, (ii) algorithms to allow for online updates to these indices, and (iii) query processing algorithms utilizing them. We implemented all algorithms in Hadoop (HDFS) and HBase and tested them on TPC-H datasets of various scales, utilizing different queries on tables of various sizes and different score-attribute distributions. We ported our implementations to Amazon EC2 and "in-house" lab clusters of various scales. We provide performance results for three metrics: query execution time, network bandwidth consumption, and dollar-cost for query execution.
A principled approach to bridging the gap between graph data and their schemas
Authors: Arenas Marcelo , Díaz Gonzalo , Fokoue Achille , Kementsietsidis Anastasios , Srinivas Kavitha
Published: May 2015

Although RDF graph data often come with an associated schema, recent studies have proven that real RDF data rarely conform to their perceived schemas. Since a number of data management decisions, including storage layouts, indexing, and efficient query processing, use schemas to guide the decision making, it is imperative to have an accurate description of the
structuredness
of the data at hand (how well the data conform to the schema).

In this paper, we have approached the study of the structuredness of an RDF graph in a principled way: we propose a framework for specifying structuredness functions, which gauge the degree to which an RDF graph conforms to a schema. In particular, we first define a formal language for specifying structuredness functions with expressions we call rules. This language allows a user to state a rule to which an RDF graph may fully or partially conform. Then we consider the issue of discovering a refinement of a sort (type) by partitioning the dataset into subsets whose structuredness is over a specified threshold. In particular, we prove that the natural decision problem associated to this refinement problem is NP-complete, and we provide a natural translation of this problem into Integer Linear Programming (ILP). Finally, we test this ILP solution with three real world datasets and three different and intuitive rules, which gauge the structuredness in different ways. We show that the rules give meaningful refinements of the datasets, showing that our language can be a powerful tool for understanding the structure of RDF data, and we show that the ILP solution is practical for a large fraction of existing data.
M4
Authors: Jugel Uwe , Jerzak Zbigniew , Hackenbroich Gregor , Markl Volker
Published: May 2015

Visual analysis of high-volume time series data is ubiquitous in many industries, including finance, banking, and discrete manufacturing. Contemporary, RDBMS-based systems for visualization of high-volume time series data have difficulty to cope with the hard latency requirements and high ingestion rates of interactive visualizations. Existing solutions for lowering the volume of time series data disregard the semantics of visualizations and result in visualization errors.

In this work, we introduce M4, an aggregation-based time series dimensionality reduction technique that provides error-free visualizations at high data reduction rates. Focusing on line charts, as the predominant form of time series visualization, we explain in detail the drawbacks of existing data reduction techniques and how our approach outperforms state of the art, by respecting the process of line rasterization.

We describe how to incorporate aggregation-based dimensionality reduction at the query level in a visualization-driven query rewriting system. Our approach is generic and applicable to any visualization system that uses an RDBMS as data source. Using real world data sets from high tech manufacturing, stock markets, and sports analytics domains we demonstrate that our visualization-oriented data aggregation can reduce data volumes by up to two orders of magnitude, while preserving perfect visualizations.
Continuous matrix approximation on distributed data
Authors: Ghashami Mina , Phillips Jeff M. , Li Feifei
Published: May 2015

Tracking and approximating data matrices in streaming fashion is a fundamental challenge. The problem requires more care and attention when data comes from multiple distributed sites, each receiving a stream of data. This paper considers the problem of "tracking approximations to a matrix" in the distributed streaming model. In this model, there are
m
distributed sites each observing a distinct stream of data (where each element is a row of a distributed matrix) and has a communication channel with a coordinator, and the goal is to track an ε-approximation to the norm of the matrix along any direction. To that end, we present novel algorithms to address the matrix approximation problem. Our algorithms maintain a smaller matrix
B
, as an approximation to a distributed streaming matrix
A
, such that for any unit vector
x
: |||
Ax
||
2
− ||
Bx
||
2
| ≤ ε||
A
||
2

F

. Our algorithms work in streaming fashion and incur small communication, which is critical for distributed computation. Our best method is deterministic and uses only
O
((
m
/ε) log(β
N
)) communication, where
N
is the size of stream (at the time of the query) and β is an upperbound on the squared norm of any row of the matrix. In addition to proving all algorithmic properties theoretically, extensive experiments with real large datasets demonstrate the efficiency of these protocols.
An evaluation of the advantages and disadvantages of deterministic database systems
Authors: Ren Kun , Thomson Alexander , Abadi Daniel J.
Published: May 2015

Recent proposals for deterministic database system designs argue that deterministic database systems facilitate replication since the same input can be independently sent to two different replicas without concern for replica divergence. In addition, they argue that determinism yields performance benefits due to (1) the introduction of deadlock avoidance techniques, (2) the reduction (or elimination) of distributed commit protocols, and (3) light-weight locking. However, these performance benefits are not universally applicable, and there exist several disadvantages of determinism, including (1) the additional overhead of processing transactions for which it is not known in advance what data will be accessed, (2) an inability to abort transactions arbitrarily (e.g., in the case of database or partition overload), and (3) the increased latency required by a preprocessing layer that ensures that the same input is sent to every replica. This paper presents a thorough experimental study that carefully investigates both the advantages and disadvantages of determinism, in order to give a database user a more complete understanding of which database to use for a given database workload and cluster configuration.
Workload matters
Authors: Aluç Güneş , Özsu M. Tamer , Daudjee Khuzaima
Published: May 2015

The Resource Description Framework (RDF) is a standard for conceptually describing data on the Web, and SPARQL is the query language for RDF. As RDF is becoming widely utilized, RDF data management systems are being exposed to more diverse and dynamic workloads. Existing systems are workload-oblivious, and are therefore unable to provide consistently good performance. We propose a vision for a workload-aware and adaptive system. To realize this vision, we re-evaluate relevant existing physical design criteria for RDF and address the resulting set of new challenges.
When data management systems meet approximate hardware
Authors: He Bingsheng
Published: May 2015

Recently, approximate hardware designs have got many research interests in the computer architecture community. The essential idea of approximate hardware is that the hardware components such as CPU, memory and storage can trade off the accuracy of results for increased performance, reduced energy consumption, or both. We propose a DBMS
ApproxiDB
with its design, implementation and optimization aware of the underlying approximate hardware. ApproxiDB will run on a hybrid machine consisting of both approximate hardware and precise hardware (i.e., the conventional hardware without sacrificing the accuracy). With approximate hardware, ApproxiDB can efficiently support the concept of approximate query processing, without the overhead of pre-computed synopses or sampling techniques. More importantly, ApproxiDB is also beneficial to precise query processing, by developing non-trivial hybrid execution mechanisms on both precise and approximate hardware. In this vision paper, we sketch the initial design of ApproxiDB, discuss the technical challenges in building this system and outline an agenda for future research.
The case for data visualization management systems
Authors: Wu Eugene , Battle Leilani , Madden Samuel R.
Published: May 2015

Most visualizations today are produced by retrieving data from a database and using a specialized visualization tool to render it. This decoupled approach results in significant duplication of functionality, such as aggregation and filters, and misses tremendous opportunities for cross-layer optimizations. In this paper, we present the case for an integrated Data Visualization Management System (DVMS) based on a declarative visualization language that fully compiles the end-to-end visualization pipeline into a set of relational algebra queries. Thus the DVMS can be both
expressive
via the visualization language, and
performant
by lever-aging traditional and visualization-specific optimizations to scale interactive visualizations to massive datasets.
WideTable
Authors: Li Yinan , Patel Jignesh M.
Published: May 2015

This paper presents a technique called WideTable that aims to improve the speed of analytical data processing systems. A WideTable is built by denormalizing the database, and then converting complex queries into simple scans on the underlying (wide) table. To avoid the pitfalls associated with denormalization, e.g. space overheads, WideTable uses a combination of techniques including dictionary encoding and columnar storage. When denormalizing the data, WideTable uses outer joins to ensure that queries on tables in the schema graph, which are now nested as embedded tables in the WideTable, are processed correctly. Then, using a packed code scan technique, even complex queries on the original database can be answered by using simple scans on the WideTable(s). We experimentally evaluate our methods in a main memory setting using the queries in TPC-H, and demonstrate the effectiveness of our methods, both in terms of raw query performance and scalability when running on many-core machines.