Capturing the Laws of (Data) Nature

Model fitting is at the core of many scientific and industrial applications. These models encode a wealth of domain knowledge, something a database decidedly lacks. Except for simple cases, databases could not hope to achieve a deeper understanding of the hidden relationships in the data yet. We propose to harvest the statistical models that users fit to the stored data as part of their analysis and use them to advance physical data storage and approximate query answering to unprecedented levels of performance. We motivate our approach with an astronomical use case and discuss its pote

Peak Performance – Remote Memory Revisited

Many database systems share a need for large amounts of fast storage. However, economies of scale limit the utility of extending a single machine with an arbitrary amount of memory. The recent broad availability of the zero-copy data transfer protocol RDMA over low-latency and high throughput network connections such as InfiniBand prompts us to revisit the long-proposed usage of memory provided by remote machines. In this paper, we present a solution to make use of remote memory without manipulation of the operating system, and investigate the impact on database performance

Quantum Maxwell-Bloch equations for spatially inhomogeneous semiconductor lasers

We present quantum Maxwell-Bloch equations (QMBE) for spatially inhomogeneous semiconductor laser devices. The QMBE are derived from fully quantum mechanical operator dynamics describing the interaction of the light field with the quantum states of the electrons and the holes near the band gap. By taking into account field-field correlations and field-dipole correlations, the QMBE include quantum noise effects which cause spontaneous emission and amplified spontaneous emission. In particular, the source of spontaneous emission is obtained by factorizing the dipole-dipole correlations into a product of electron and hole densities. The QMBE are formulated for general devices, for edge emitting lasers and for vertical cavity surface emitting lasers, providing a starting point for the detailed analysis of spatial coherence in the near field and far field patterns of such laser diodes. Analytical expressions are given for the spectra of gain and spontaneous emission described by the QMBE. These results are applied to the case of a broad area laser, for which the frequency and carrier density dependent spontaneous emission factor beta and the evolution of the far field pattern near threshold are derived.Comment: 22 pages RevTex and 7 figures, submitted to Phys.Rev.A, revisions in abstract and in the discussion of temporal coherenc

After total knee arthroplasty, many people are not active enough to maintain their health and fitness: an observational study

AbstractQuestionsWhat proportion of people after total knee arthroplasty adheres to the physical activity regimen recommended for maintenance of health (moderate intensity physical activity for at least 30min on 5 days/week)? What proportion adheres to the activity regimen recommended to improve fitness (vigorous intensity physical activity for at least 20min on 3 days/week)? What factors are associated with adherence to these recommendations?DesignAn observational study.Participants830 adults who underwent a total knee arthroplasty between 2002 and 2006 at University Medical Center Gronigen or Martini Hospital Gronigen, the Netherlands.Outcome measuresThe Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH) was used to measure the physical activity behaviour of the participants. These data were analysed as adherence to each recommendation.ResultsThe health recommendation was adhered to by 51% of the participants. The fitness recommendation was adhered to by 53% of participants. Almost half (46%) of the participants fulfilled both recommendations, and 42% did not fulfil either recommendation. Males and more educated participants had higher odds of meeting the health, fitness, and both recommendations. Respondents living with family had higher odds of meeting the fitness recommendation.ConclusionAfter total knee arthroplasty, 42% of people are not active enough to maintain their health and fitness. Physiotherapists should encourage people with a total knee arthroplasty to undertake the recommended exercise regimens to maintain health and fitness, with particular attention to those people with characteristics known to be associated with poor adherence to the recommendations

Performance of IMPACT, CRASH and Nijmegen models in predicting six month outcome of patients with severe or moderate TBI: An external validation study

Background: External validation on different TBI populations is important in order to assess the generalizability of prognostic models to different settings. We aimed to externally validate recently developed models for prediction of six month unfavourable outcome and six month mortality. Methods: The International Neurotrauma Research Organization - Prehospital dataset (INRO-PH) was collected within an observational study between 2009-2012 in Austria and includes 778 patients with TBI of GCS < = 12. Three sets of prognostic models were externally validated: the IMPACT core and extended models, CRASH basic models and the Nijmegen models developed by Jacobs et al - all for prediction of six month unfavourable outcome and six month mortality. The external validity of the models was assessed by discrimination (Area Under the receiver operating characteristic Curve, AUC) and calibration (calibration statistics and plots). Results: Median age in the validation cohort was 50 years and 44% had an admission GSC motor score of 1-3. Six-month mortality was 27%. Mortality could better be predicted (AUCs around 0.85) than unfavourable outcome (AUCs around 0.80). Calibration plots showed that the o

Single-click to data insights: transaction replication and deployment automation made simple for the cloud age

In this report we present out initial work on making the MonetDB column-store analytical database ready for Cloud deployment. As we stand in the new space between research and industry we have tried to combine approaches from both worlds. We provide details how we utilize modern technologies and tools for automating building of virtual machine image for Cloud, datacentre and desktop use. We also explain our solution to asynchronous transaction replication MonetDB. The report concludes with how this all ties together with our efforts to make MonetDB ready for the age where high-performance data analytics is available in a single-click

Fast in-database cross-matching of high-cadence, high-density source lists with an up-to-date sky model

Coming high-cadence wide-field optical telescopes will image hundreds of thousands of sources per minute. Besides inspecting the near real-time data streams for transient and variability events, the accumulated data archive is a wealthy laboratory for making complementary scientific discoveries. The goal of this work is to optimise column-oriented database techniques to enable the construction of a full-source and light-curve database for large-scale surveys, that is accessible by the astronomical community. We adopted LOFAR's Transients Pipeline as the baseline and modified it to enable the processing of optical images that have much higher source densities. The pipeline adds new source lists to the archive database, while cross-matching them with the known cataloguedsources in order to build a full light-curve archive. We investigated several techniques of indexing and partitioning the largest tables, allowing for faster positional source look-ups in the cross matching algorithms. We monitored all query run times in long-term pipeline runs where we processed a subset of IPHAS data that have image source density peaks over 170,000 per field of view (500,000 deg−2). Our analysis demonstrates that horizontal table partitions of declination widths of one-degree control the query run times. Usage of an index strategy where the partitions are densely sorted according to source declination yields ano

Nutritional status of Lusitano broodmares on extensive feeding systems: body condition, live weight and metabolic indicators

Articles in International JournalsThe present research aimed to evaluate the effects of foaling season and feeding management in extensive systems on the nutritional status of Lusitano broodmares throughout the gestation/lactation cycle, by assessment of body condition (BC), body weight (BW), and some blood metabolic indicators. Four groups of Lusitano broodmares (A, B, C, D) were monitored during four years, in a total of 119 gestation/lactation cycles. All mares were kept on pasture, and A and B mares were daily supplemented. Monthly, mares were weighed and BC evaluated. Suckling foals from these mares were also monitored for BW and withers height. Glucose, non-esterified fatty acids, urea and albumin concentrations were determined in blood. BW changes were influenced by reproductive stage and foaling season (P<0.001), reflecting also pasture availability. Changes on BC were observed (P<0.05), although with small amplitudes within each group. Higher scores were reached at the end of spring, decreasing 0.25 point until late summer. Early foaling had also a marked effect, hindering the recovery of BC along the cycle. Glucose values decreased from late gestation to early lactation (P<0.05) and lower levels were recorded during the summer months. Uremia was mainly influenced by the reproductive stage (P<0.05). Under nutrition was not detected. Foals born in February-March had higher average daily gain than those born in April-May (P<0.05), probably reflecting differences in milk production of the mares. BC and BW changes and, particularly, blood indicators showed an overall balanced nutritional status, reflecting an adaptation to feed availability and climate.Portuguese Foundation for Science and Technolog

Enhancement of long-range magnetic order by magnetic field in superconducting La2CuO(4+y)

We report a detailed study, using neutron scattering, transport and magnetization measurements, of the interplay between superconducting (SC) and spin density wave (SDW) order in La2CuO(4+y). Both kinds of order set in below the same critical temperature. However, the SDW order grows with applied magnetic field, whereas SC order is suppressed. Most importantly, the field dependence of the SDW Bragg peak intensity has a cusp at zero field, as predicted by a recent theory of competing SDW and SC order. This leads us to conclude that there is a repulsive coupling between the two order parameters. The question of whether the two kinds of order coexist or microscopically phase separate is discussed.Comment: Version accepted for publication in Phys. Rev. B. Improved discussion in connection with the muSR result

On the origin of the A1g_{1g} and B1g_{1g} electronic Raman scattering peaks in the superconducting state of YBa2_{2}Cu3_{3}O7−δ_{7-\delta}

The electronic Raman scattering has been investigated in optimally oxygen doped YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ single crystals as well as in crystals with non-magnetic, Zn, and magnetic, Ni, impurities. We found that the intensity of the A$_{1g}$ peak is impurity independent and their energy to $T_{c}$ ratio is almost constant ($2\Delta/k_{B}T_{c}\sim5$). Moreover, the signal at the B$_{1g}$ channel is completely smeared out when non-magnetic Zn impurities are present. These results are qualitatively interpreted in terms of the Zeyher and Greco's theory that relates the electronic Raman scattering in the A$_{1g}$ and B$_{1g}$ channels to \textit{d}-CDW and superconducting order parameters fluctuations, respectively.Comment: Submited to Phys. Rev. Let