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Accurate and reliable information about three-dimensional (3D) knee joint laxity can prevent misdiagnosis and avoid incorrect treatments. Nevertheless, knee laxity assessments presented in the literature suffer from significant drawbacks such as soft tissue artifacts, restricting the knee within the measurement, and the absence of quantitative knee ligament property information. In this study, we demonstrated the applicability of a novel methodology for measuring 3D knee laxity, combining robotics- and image-based technology. As such technology has never been applied to healthy living subjects, the aims of this study were to develop novel technology to measure 3D knee laxity in vivo and to provide proof-of-concept 3D knee laxity measurements. To measure tibiofemoral movements, four healthy subjects were placed on a custom-built arthrometer located inside a low dose biplanar X-ray system with an approximately 60 deg knee flexion angle. Anteroposterior and mediolateral translation as well as internal and external rotation loads were subsequently applied to the unconstrained leg, which was placed inside a pneumatic cast boot. Bone contours were segmented in the obtained X-rays, to which subject-specific bone geometries from magnetic resonance imaging (MRI) scans were registered. Afterward, tibiofemoral poses were computed. Measurements of primary and secondary laxity revealed considerable interpersonal differences. The method differs from those available by the ability to accurately track secondary laxity of the unrestricted knee and to apply coupled forces in multiple planes. Our methodology can provide reliable information for academic knee ligament research as well as for clinical diagnostics in the future.

The complement system represents a powerful part of the innate immune system capable of removing pathogens and damaged host cells. Nevertheless, only a subset of therapeutic antibodies are capable of inducing complement dependent cytotoxicity, which has fuelled the search for new strategies to potentiate complement activation. Properdin (FP) functions as a positive complement regulator by stabilizing the alternative pathway C3 convertase. Here, we explore a novel strategy for direct activation of the alternative pathway of complement using bi-specific single domain antibodies (nanobodies) that recruit endogenous FP to a cell surface. As a proof-of-principle, we generated bi-specific nanobodies with specificity toward FP and the validated cancer antigen epidermal growth factor receptor (EGFR) and tested their ability to activate complement onto cancer cell lines expressing EGFR. Treatment led to recruitment of FP, complement activation and significant deposition of C3 fragments on the cells in a manner sensitive to the geometry of FP recruitment. The bi-specific nanobodies induced complement dependent lysis of baby hamster kidney cells expressing human EGFR but were unable to lyse human tumour cells due to the presence of complement regulators. Our results confirm that FP can function as a surface bound focal point for initiation of complement activation independent of prior C3b deposition. However, recruitment of FP by bi-specific nanobodies appears insufficient for overcoming the inhibitory action of the negative complement regulators overexpressed by many human tumour cell lines. Our data provide general information on the efficacy of properdin as an initiator of complement but suggest that properdin recruitment on its own may have limited utility as a platform for potent complement activation on regulated cell surfaces.

Laxity tests are performed to diagnose ligament injuries or to estimate subject-specific ligament properties. While the current laxity tests are easy to perform, they are not optimized to isolate specific ligament bundles. Therefore, we developed a methodology to identify optimal laxity tests to either stretch specific ligaments relatively more than other ligaments or maximally stretch a specific ligament within the boundaries of maximally applied loads to the knee. The method was applied to a subject-specific knee model and the identified optimal laxity tests compared against standard tests. For the laxity tests isolating the stretch in a specific ligament, we found laxity tests that performed better for all ligament bundles except a few where neither the optimal nor standard laxity tests could isolate the ligament. We found force ratios, between the force change in the ligament of interest compared to the maximal force change in the other ligaments, of over 2.0 for six ligament bundles with the optimized load cases whereas the standard laxity tests only resulted in one bundle over 2.0. For the tests to maximally load the ligament of interest, increased force changes were seen for all optimal load cases and force changes of over 200 N were seen for six ligament bundles whereas only one bundle had a force change over 200N with the standard laxity tests. Our results show that there is a potential to develop better laxity tests than those performed today and emerging laxity test equipment enable implementation of such tests.

Factor D (also known as adipsin) is a serine protease and part of the complement system, involved in innate immune responses and effector functions of antibodies. Factor D cleaves factor B complexed with C3b, leading to the C3 convertase C3bBb. This C3 convertase is central in the alternative activation pathway and the amplification loop, which amplifies the two other complement activation pathways: the classical pathway and the lectin pathway. Adipocytes synthesize factor D as a pro-form comprising 6 additional residues that must be cleaved off to generate a mature form. The MBL-associated serine protease 3 (MASP-3), found in complex with the pattern recognition molecules of lectin activation pathway, converts the pro-form to mature factor D, which reportedly is the most abundant form found in the circulation at concentrations of 1-2 μg/ml among healthy individuals. The mature factor D is rate-limiting for complement activation, but little is known about the distribution of pro vs. mature factor D in the circulation, the regulation hereof and the potential activation stimuli of the lectin pathway, responsible for activation of MASP-3 and subsequent conversion of pro-form of factor D. In this light we established and validated an ELISA specific for measuring the pro-form of complement factor D. With a working range of 0.82-25 ng/ml, acceptable intra and inter assay CVs, and a relative recovery rate above 90%, we found that the median plasma concentration in Danish blood donors was 134 ng/ml; corresponding to that 8-15% factor D circulates as pro-form. We also found that blood sampling procedures affect conversion and hence the levels measured in serum and plasma.

Knee joint laxity or instability is a common problem that may have detrimental consequences for patients. Unfortunately, assessment of knee joint laxity is limited by current methodologies resulting in suboptimal diagnostics and treatment. This paper presents a novel method for accurately measuring non-invasive knee joint laxity in four degrees-of-freedom (DOF). An arthrometer, combining a parallel manipulator and a six-axis force/moment sensor, was developed to be used in combination with a low-dose biplanar x-ray system and 3D image data to reconstruct tibiofemoral position and orientation of laxity measurements. As proof-of-concept, four cadaveric knees were tested in the device. Each cadaveric knee was mounted in the device at approximately 30° of flexion and twelve monoplanar anteroposterior, mediolateral and internal/external load cases were applied. Additionally, four biplanar load cases were applied, consisting of different combinations of anteroposterior and internal/external loads. The arthrometer was limited to four DOF to address the specific measurements. For validation purposes, the pose reconstructions of tibia and femur were compared with pose reconstructions of bone pin marker frames mounted on each bone. The measurements from the arthrometer in terms of translation and rotations displayed comparable values to what have previously been presented in the literature. Furthermore, the measurements revealed coupled motions in multiple planes, demonstrating the importance of multi DOF laxity measurements. The validation displayed an average mean difference for translations of 0.08 mm and an average limit of agreement between −1.64 mm and 1.80 mm. The average mean difference for rotations was 0.10° and the limit of agreement was between −0.85° and 1.05°. The presented method eliminates several limitations present in current methods and may prove a valuable tool for assessing knee joint ispartof: Journal Of Biomechanics vol:82 pages:62-69 ispartof: location:United States status: published

Ligaments are important joint stabilizers but assessing their mechanical properties remain challenging. We developed a methodology to investigate the effects of kinematic measurement uncertainty during laxity tests on optimization-based estimation of ligament properties. We applied this methodology to a subject-specific knee model with known ligament properties as inputs and compared the estimated to the known knee ligament properties under the influence of noise. Four different sets of laxity tests were simulated with an increasing number of load cases, capturing anterior/posterior, varus/valgus, and internal/external rotation loads at 0 deg and 30 deg of knee flexion. 20 samples of uniform random noise ([−0.5,0.5] mm and degrees) were added to each set and fed into an optimization routine that subsequently estimated the ligament properties based on the noise targets. We found a large range of estimated ligament properties (stiffness ranges of 5.97 kN, 7.64 kN, 8.72 kN, and 3.86 kN; reference strain ranges of 3.11%, 2.53%, 1.88%, and 1.58% for anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medical collateral ligament (MCL), and lateral collateral ligament (LCL), respectively) for three sets of laxity tests, including up to 22 load cases. A set of laxity tests with 60 load cases kept the stiffness and reference strain ranges below 470 N per unit strain and 0.85%, respectively. These results illustrate that kinematic measurement noise have a large impact on estimated ligament properties and we recommend that future studies assess and report both the estimated ligament properties and the associated uncertainties due to kinematic measurement noise.

The complement system is an intricate cascade of the innate immune system and plays a key role in microbial defense, inflammation, organ development, and tissue regeneration. There is increasing interest in developing complement regulatory and inhibitory agents to treat complement dysfunction. In this study, we describe the nanobody hC3Nb3, which is specific for the C-terminal C345c domain of human and mouse complement component C3/C3b/C3c and potently inhibits C3 cleavage by the alternative pathway. A high-resolution structure of the hC3Nb3–C345c complex explains how the nanobody blocks proconvertase assembly. Surprisingly, although the nanobody does not affect classical pathway–mediated C3 cleavage, hC3Nb3 inhibits classical pathway–driven hemolysis, suggesting that the C-terminal domain of C3b has an important function in classical pathway C5 convertase activity. The hC3Nb3 nanobody binds C3 with low nanomolar affinity in an SDS-resistant complex, and the nanobody is demonstrated to be a powerful reagent for C3 detection in immunohistochemistry and flow cytometry. Overall, the hC3Nb3 nanobody represents a potent inhibitor of both the alternative pathway and the terminal pathway, with possible applications in complement research, diagnostics, and therapeutics.

Properdin stabilizes the alternative C3 convertase (C3bBb), whereas its role as pattern-recognition molecule mediating complement activation is disputed for decades. Previously, we have found that soluble collectin-12 (sCL-12) synergizes complement alternative pathway (AP) activation. However, whether this observation is C3 dependent is unknown. By application of the C3-inhibitor Cp40, we found that properdin in normal human serum bound to Aspergillus fumigatus solely in a C3b-dependent manner. Cp40 also prevented properdin binding when properdin-depleted serum reconstituted with purified properdin was applied, in analogy with the findings achieved by C3-depleted serum. However, when opsonized with sCL-12, properdin bound in a C3-independent manner exclusively via its tetrameric structure and directed in situ C3bBb assembly. In conclusion, a prerequisite for properdin binding and in situ C3bBb assembly was the initial docking of sCL-12. This implies a new important function of properdin in host defense bridging pattern recognition and specific AP activation. Copyright Zhang et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.

Properdin (FP) is an essential positive regulator of the complement alternative pathway (AP) providing stabilization of the C3 and C5 convertases, but its oligomeric nature challenges structural analysis. We describe here a novel FP deficiency (E244K) caused by a single point mutation which results in a very low level of AP activity. Recombinant FP E244K is monomeric, fails to support bacteriolysis, and binds weakly to C3 products. We compare this to a monomeric unit excised from oligomeric FP, which is also dysfunctional in bacteriolysis but binds the AP proconvertase, C3 convertase, C3 products and partially stabilizes the convertase. The crystal structure of such a FP‐convertase complex suggests that the major contact between FP and the AP convertase is mediated by a single FP thrombospondin repeat and a small region in C3b. Small angle X‐ray scattering indicates that FP E244K is trapped in a compact conformation preventing its oligomerization. Our studies demonstrate an essential role of FP oligomerization in vivo while our monomers enable detailed structural insight paving the way for novel modulators of complement. ![][1] Functional studies of oligomeric and two different monomeric forms of the complement regulator FP demonstrate an essential role of oligomerization, while structural studies suggest that the contact between FP and the alternative pathway convertase is mainly mediated by a single FP thrombospondin repeat and a small region in C3b. [1]: /embed/graphic-1.gif

International audience; Properdin (FP) is a positive regulator of the immune system stimulating the activity of the proteolytically active C3 convertase C3bBb in the alternative pathway of the complement system. Here we present two crystal structures of FP and two structures of convertase bound FP. A structural core formed by three thrombospondin repeats (TSRs) and a TB domain harbors the convertase binding site in FP that mainly interacts with C3b. Stabilization of the interaction between the C3b C-terminus and the MIDAS bound Mg2+ in the Bb protease by FP TSR5 is proposed to underlie FP convertase stabilization. Intermolecular contacts between FP and the convertase subunits suggested by the structure were confirmed by binding experiments. FP is shown to inhibit C3b degradation by FI due to a direct competition for a common binding site on C3b. FP oligomers are held together by two sets of intermolecular contacts, where the first is formed by the TB domain from one FP molecule and TSR4 from another. The second and largest interface is formed by TSR1 and TSR6 from the same two FP molecules. Flexibility at four hinges between thrombospondin repeats is suggested to enable the oligomeric, polydisperse, and extended architecture of FP. Our structures rationalize the effects of mutations associated with FP deficiencies and provide a structural basis for the analysis of FP function in convertases and its possible role in pattern recognition.

The 54 kDa protein properdin, also known as factor P (FP), plays a major role in the complement system through the stabilization of the alternative pathway convertases. FP circulates in the blood as cyclic dimers, trimers and tetramers, and this heterogeneity challenges detailed structural insight into the mechanism of convertase stabilization by FP. Here, the generation of an intact FP monomer and a variant monomer with the third thrombospondin repeat liberated is described. Both FP monomers were excised from recombinant full-length FP containing internal cleavage sites for TEV protease. These FP monomers could be crystallized, and complete data sets extending to 2.8 Å resolution for the intact FP monomer and to 3.5 Å resolution for the truncated variant were collected. The principle of specific monomer excision and domain removal by the insertion of a protease cleavage site may be broadly applicable to structural studies of oligomeric, flexible and modular proteins.

Aim To assess the relative roles of geologically defined terrain types ( environmental heterogeneity) and a major river ( physical dispersal barrier) as predictors of ecological structuring and biogeographical differentiation within Amazonian forests.Location Western Brazilian Amazonia, where the Jurua river and its terraces cross a 1000-km-long boundary between two geological formations ( the Solimoes and Ica Formations).Methods We sampled a 500-km stretch of the Jurua with 71 transects ( 5 m by 500 m) that spanned both the river and the geological boundary. All transects were inventoried for pteridophytes ( ferns and lycophytes) and Melastomataceae, and a subset of 39 transects also for palms and Zingiberales. Three surface soil samples were collected from each transect. The data were analysed using ordinations, regression trees, indicator species analyses and Mantel tests.Results All plant groups showed congruent species turnover between geologically defined terrain types, but little evidence of isolation by the river or geographical distance. Soil cation concentration differed between the Solimoes Formation and other terrain types and emerged as the main explanatory factor for species turnover. A large proportion of the plant species were significant indicators for specific parts of the soil cation concentration gradient, and these edaphic associations were congruent with those found in other parts of Amazonia. Pteridophytes had a larger proportion of species in the cation-rich soils than the other plant groups did, and palms had a higher proportion of generalists.Main conclusions The geological boundary between the Solimoes and Ica formations is confirmed as significant floristic turnover zone. As it runs in a north-south orientation for more than 1000 km, the edaphic differences associated with this boundary have wide-ranging implications for speciation and biogeographical patterns in Amazonia.

We studied diversity and abundance of palms in the eastern Colombian Amazon in 71 transects, 61 measuring 5×500 m and 10 transects measuring 4×500 m, innventoring a total of 17.25 hectares. We found a total of 74 species in 21 genera. In terra firme we found 68 species in 20 genera and an average density of 2900 individuals per hectare; there were six different growh forms among which small understory palms was the most important followed by tall canopy palms. On the floodplains and terraces we found 60 species in 19 genera and an average density of 3737 individuals per hectare. Of the 74 palms encountered 25 species (33%) were solitary and 43 species (58%) were cespitose and the remaining six species (8%) were colonial. The dominant leaf form was the pinnate and only few species had costapalmate (Mauritia flexuosa, Mauritiella armata) or palmate leaves (Lepidocaryum tenue). The dominant species found in this study (Euterpe precatoria, Oenocarpus bataua, Attalea butyracea, Iriartella setigera) coincide with dominant species in other Amazonian palm communities.

The complement system is a highly complex and carefully regulated proteolytic cascade activated through three different pathways depending on the activator recognized. The structural knowledge regarding the intricate proteolytic enzymes that activate and control complement has increased dramatically over the last decade. This development has been pivotal for understanding how mutations within complement proteins might contribute to pathogenesis and has spurred new strategies for development of complement therapeutics. Here we describe and discuss the complement system from a structural perspective and integrate the most recent findings obtained by crystallography, small-angle X-ray scattering, and electron microscopy. In particular, we focus on the proteolytic enzymes governing activation and their products carrying the biological effector functions. Additionally, we present the structural basis for some of the best known complement inhibitors. The large number of accumulated molecular structures enables us to visualize the relative size, position, and overall orientation of many of the most interesting complement proteins and assembled complexes on activator surfaces and in membranes.

We studied palm communities, in particular species-richness and abundance, in the tropical rainforests in southeastern Peru in 54 transects (5×500m) covering an area of 13.5 hectares in flood plain, terra firme, terrace and premontane hills. We found 42 palm species in 18 genera in the transects. Terra firme forest had the highest species richness (38 species) followed by floodplain and premontane hills with 27 species and terrace forests with 26 species. The highest palm abundances were found in premontane hill forest which had 3243 palms per hectare and terra firme forest which had 2968 palms per hectare. The floodplain forests were intermediate in palm abundance with 2647 and the terrace forests had the lowest abundance with 1709 palms per hectare. Intermediate sized palms were the most common being represented by 18 species, while large palms were represented with 16 species. There were only eight species of small palms of which one was acaulescent. Only one species of liana palm was registered. Of the 42 species observed in the 54 transects, 20 were cespitose, 21 solitary and two had colonial growth. Seven species were found 40–320 km outside of their previously known range., Estudiamos las comunidades de palmas de los bosques pluviales tropicales del sur de Perú, con especial énfasis en su riqueza de especies y abundancia, utilizando 54 transectas (5×500m), que cubrieron un área de 13.5 hectáreas en planicie inundable, terra firme, terraza y colinas premontanas. Encontramos 42 especies de palmas en las transectas. En el bosque de terra firme se encontró la mayor riqueza de especies (38 especies), seguido por la planicie inundable y las colinas premontanas con 27 especies y los bosques de terraza con 26 especies. Las mayores abundancias se encontraron en el bosque de colinas premontanas, con 3243 palmas por hectárea, y en el bosque de terra firme con 2968 palmas por hectárea. Los bosques de la planicie inundable presentaron una abundancia intermedia con 2647 palmas por hectárea y los bosques de terraza presentaron la menor abundancia con 1709. Las palmas de tamaño intermedio fueron las más comunes, estando representadas por 18 especies, mientras que las palmas grandes estuvieron representadas por 16 especies. Se encontraron solamente ocho especies de palmas pequeñas, una de las cuales era acaulescente. Sólo se registró una especie de palma trepadora. De las 42 especies observadas en las 54 transectas, 20 fueron cespitosas, 21 solitarias y dos presentaron crecimiento colonial. Siete especies se encontraron 40–320 km fuera del rango de distribución conocido previamente.

Aim It is a central issue in ecology and biogeography to understand what governs community assembly and the maintenance of biodiversity in tropical rain forest ecosystems. A key question is the relative importance of environmental species sorting (niche assembly) and dispersal limitation (dispersal assembly), which we investigate using a large dataset from diverse palm communities. Location Lowland rain forest, western Amazon River Basin, Peru. Methods We inventoried palm communities, registering all palm individuals and recording environmental conditions in 149 transects of 5 m × 500 m. We used ordination, Mantel tests and indicator species analysis (ISA) to assess compositional patterns, species responses to geographical location and environmental factors. Mantel tests were used to assess the relative importance of geographical distance (as a proxy for dispersal limitation) and environmental differences as possible drivers of dissimilarity in palm species composition. We repeated the Mantel tests for subsets of species that differ in traits of likely importance for habitat specialization and dispersal (height and range size). Results We found a strong relationship between compositional dissimilarity and environmental distance and a weaker but also significant relationship between compositional dissimilarity and geographical distance. Consistent with expectations, relationships with environmental and geographical distance were stronger for understorey species than for canopy species. Geographical distance had a higher correlation with compositional dissimilarity for small-ranged species compared with large-ranged species, whereas the opposite was true for environmental distance. The main environmental correlates were inundation and soil nutrient levels. Main conclusions The assembly of palm communities in the western Amazon appears to be driven primarily by species sorting according to hydrology and soil, but with dispersal limitation also playing an important role. The importance of environmental characteristics and geographical distance varies depending on plant height and geographical range size in agreement with functional predictions, increasing our confidence in the inferred assembly mechanisms.

To advance our understanding of the processes that govern the assembly of palm communities and the local coexistence of numerous palm species, we here synthesize available information in the literature on species diversity and growth-form composition in palm communities across the Americas. American palm communities surveyed had 4–48 (median 16) species in study plots covering 0.09–7.2 ha. Climate, soils, hydrology, and topography are the main factors determining palm community species richness. Tropical lowland terra firme rain forests are the most species-rich whereas forests that are inundated or grow on sandy soils or in areas with seasonal climate have much fewer species. Palm communities in the central-western Amazon and in Central America are significantly richer than the average region and those in the Caribbean significantly poorer in species. As for branching, the 789 species of tropical American palms belong to Corner’s model (solitary, 268 species, 33%), Tomlinsons model (cespitose, 521 species, 66%) and Schoute’s model (dichotomous branching, three species

Summary 1. Local and regional patterns of plant species richness in tropical rain forests, as well as their possible drivers, remain largely unexplored. The main hypotheses for local species richness (alpha diversity) are (i) local environmental determinism with species-saturated communities, and (ii) regional control, in which the immigration of species from the regional species pool (gamma diversity) determines how many species coexist locally. The species pool hypothesis suggests a combined influence of local and regional drivers on alpha diversity. Differences in gamma diversity may arise from divergent environmental conditions or biogeographic histories. 2. We investigated the cross-scale determinants of palm alpha and gamma diversity across the western Amazon using a large field-based data set: a census of all palm individuals in 312 transects, totalling 98 species. We used regression-based variation partitioning to understand how habitat, topography and region influence alpha diversity, and correlations to assess the importance of the present environment (climate, soil, regional topography) and history (long-term habitat stability) for average regional alpha diversity and gamma diversity, including the link between these two diversity measures (species pool effect). 3. Variation in alpha diversity was primarily explained by region (36%) and habitat (18%), whereas the effect of topography was negligible (1%). Within habitats, region was even more important (up to 69% explained variation). Within regions, habitat and topography covaried and had a variable but an important influence. The pure effect of topography remained of minor importance (up to 13%). 4. Average regional alpha diversity was related to gamma diversity, precipitation seasonality and possibly long-term habitat stability. Gamma diversity was related to long-term habitat stability, and possibly current climate. 5. Synthesis. Gamma diversity strongly influenced alpha diversity, although a clear influence of local environment was also evident, notably habitat type, with a minor, more geographically variable effect of small-scale topography. Apart from gamma diversity, the factor most strongly related to regional alpha diversity was precipitation seasonality, while gamma diversity itself was strongly linked to long-term habitat stability. These results imply that plant species richness is contingent on both contemporary and historical factors with a strong link between local species richness and the regional species pool.

Cloud intelligence is a collection of technologies emerging from the migration of business intelligence and analytics technologies to a cloud computing environment combined with exploiting the massive range of new intelligence opportunities opened up by cloud computing. Cloud computing introduces several trends which require traditional business intelligence techniques to be re-thought, including agility, the ability to assemble resources, e.g., data sources, on-demand, and virtualization, e.g., that data are provided as a service over the web rather than stored in local databases. This paper focuses on the combination of data source agility and data-as-a-service virtualization and its use for cloud intelligence. After presenting the novel vision of the Cloud Warehouse, the paper goes on to present a comprehensive semantic foundation for on-demand multidimensional data integration, including formal data models, a range of query operators and re-write rules for optimization. This semantic foundation provides a sound formal basis for on-demand multidimensional data integration, which is a cornerstone of cloud intelligence.

Introduction of biofuels to the fuel matrix poses new questions and challenges. The present study investigates the microbiological stability of biodiesel blends in small scale microcosms. The study presents results from incubations of diesel-biodiesel blends with contaminated inoculation water collected from diesel storage tanks to ensure the presence of relevant fuel degrading bacteria. DAPI and qPCR analyses has subsequently shown an increased bacterial growth and activity in the microcosms containing biodiesel blends as the carbon source compared to those microcosms where neat fossil diesel made up the carbon source. Several anaerobic microorganisms have been identified after incubation. Presence of methanogens, sulfate-reducing bacteria and nitrate reducing bacteria has furthermore been confirmed by chemical analyses, supplemented by observations of methane formation in biodiesel incubations. The findings will contribute to the knowledge base for a safer introduction of biodiesel in the fuel matrix by employment of proper house-keeping and monitoring methods.

This paper presents the results of industrial work on the logical integration of Online Analytical Processing (OLAP) and eXtensible Markup Language (XML) data sources, carried out in cooperation between TARGIT, a Danish OLAP client vendor, and Aalborg University. A prototype has been developed that allows XML data stored outside the OLAP system to be used as dimensions and measures in the OLAP system in the same way as ordinary dimensions and measures. This provides a powerful and flexible way to handle unexpected or short-term data requirements as well as rapidly changing data. Compared to earlier work, this paper presents several major extensions that resulted from TARGIT'S requirements. These include the ability to use XML data as measures, as well as a novel multigranular data model and query language that formalises and extends the TARGIT data model and query language. Experiments indicate that our approach is often a feasible alternative to physical integration.

The rapidly changing data requirements of today's dynamic business environments are not handled well by current online analytical processing (OLAP) systems. Physically integrating data from new sources into OLAP systems is a long and time-consuming process, making logical integration the better choice in many situations. The increasing use of Extended Markup Language (XML) suggests that the required external data will most often be available in XML format. We present a theoretically well-founded approach to the logical federation of OLAP and XML data sources. The approach allows external XML data to be presented along with dimensional data in OLAP query results and enables the use of external XML data for selection and grouping. Special care is taken to ensure that semantic problems do not occur in the integration process. This opens up many new application areas for OLAP. A number of effective optimization techniques for OLAP-XML federations are presented. Performance results from the prototype implementation show that the approach is an attractive alternative to physical integration. The approach is exemplified using a real-world case study from the B2B domain.

The changing data requirements of today's dynamic business environments are not handled well by current OLAP systems. Physically integrating unexpected data into such systems is a long and time-consuming process making logical integration, i.e., federation, the better choice in many situations. The increasing use of Extended Markup Language (XML), e.g. in business-to-business (B2B) applications, suggests that the required data will often be available as XML data. This means that logical federations of OLAP and XML databases will be very attractive in many cases. However, for such OLAP-XML federations to be useful, effective optimization techniques for such systems are needed.In this paper we present novel techniques for query optimization in federations of OLAP and XML databases. The techniques include so-called inlining of XML data in OLAP predicates, caching, and pre-fetching. Experiments show that the proposed optimization techniques improve query execution times significantly. Furthermore, the performance of the optimized federation queries is comparable to the performance achieved with physical integration of the data, showing that our federated OLAP approach is indeed a feasible alternative to physical integration.

The ever-changing data requirements of today's dynamic businesses are not handled well by current OLAP systems. Physical integration of data into OLAP systems is a time-consuming process, making logical federations the better choice in many cases. The increasing use of XML suggests that the required data will often be available in XML format. Thus, federations of OLAP and XML databases will be very attractive in many situations. In an efficient implementation of OLAP-XML federations, cost-based optimization is a must, creating a need for an effective cost model for OLAP-XML federations.In this paper we present a cost model for OLAP-XML federations, and outline techniques for estimating the cost model parameters in a federated OLAP-XML environment. The paper also outlines the cost models for the OLAP and XML components in the federation on which the federation cost model is built. The cost model has been used as the basis for effective cost-based query optimization in OLAP-XML federations. Experiments show that the cost model is precise enough to make a substantial difference in the query optimization process.