Positional Delta Trees to reconcile updates with read-optimized data storage

We investigate techniques that marry the high readonly analytical query performance of compressed, replicated column storage (“read-optimized” databases) with the ability to handle a high-throughput update workload. Today’s large RAM sizes and the growing gap between sequential vs. random IO disk throughput, bring this once elusive goal in reach, as it has become possible to buffer enough updates in memory to allow background migration of these updates to disk, where efficient sequential IO is amortized among many updates. Our key goal is that read-only queries always see the latest database state, yet are not (significantly) slowed down by the update processing. To this end, we propose the Positional Delta Tree (PDT), that is designed to minimize the overhead of on-the-fly merging of differential updates into (index) scans on stale disk-based data. We describe the PDT data structure and its basic operations (lookup, insert, delete, modify) and provide an in-detail study of their performance. Further, we propose a storage architecture called Replicated Mirrors, that replicates tables in multiple orders, storing each table copy mirrored in both column- and row-wise data formats, and uses PDTs to handle updates. Experiments in the MonetDB/X100 system show that this integrated architecture is able to achieve our main goals

Super-Scalar RAM-CPU Cache Compression

High-performance data-intensive query processing tasks like OLAP, data mining or scientific data analysis can be severely I/O bound, even whe

Super-scalar RAM-CPU cache compression

High-performance data-intensive query processing tasks like OLAP, data mining or scientific data analysis can be severely I/O bound, even when high-e

MonetDB/X100 - A DBMS in the CPU cache

X100 is a new execution engine for the MonetDB system, that improves execution speed and overcomes its main memory limitation. It introduces t

Potential Risk Factors for, and Clinical Implications of, Delirium during Inpatient Rehabilitation: A Matched Case-Control Study

To investigate the association between a wide set of baseline characteristics (age, sex, rehabilitation discipline), functional scores [Functional Independence Measure (FIM), cumulative Illness Rating Scale (CIRS)], diseases, and administered drugs and incident delirium in rehabilitation inpatients and, furthermore, to assess clinical implications of developing delirium during rehabilitation.; Matched case-control study based on electronic health record data.; We studied rehabilitation stays of inpatients admitted between January 1, 2015, and December 31, 2018, to ZURZACH Care, Rehaklinik Bad Zurzach, an inpatient rehabilitation clinic in Switzerland.; We conducted unconditional logistic regression analyses to estimate adjusted odds ratios (AORs) with 95% CIs of exposures that were recorded in ≥5 cases and controls.; Among a total of 10,503 rehabilitation stays, we identified 125 validated cases. Older age, undergoing neurologic rehabilitation, a low FIM, and a high CIRS were associated with an increased risk of incident delirium. Being diagnosed with a bacterial infection (AOR 2.62, 95% CI 1.06-6.49), a disorder of fluid, electrolyte, or acid-base balance (AOR 2.76, 95% CI 1.19-6.38), Parkinson's disease (AOR 5.68, 95% CI 2.54-12.68), and administration of antipsychotic drugs (AOR 8.06, 95% CI 4.26-15.22), antiparkinson drugs (AOR 2.86, 95% CI 1.42-5.77), drugs for constipation (AOR 2.11, 95% CI 1.25-3.58), heparins (AOR 2.04, 95% CI 1.29-3.24), or antidepressant drugs (AOR 1.88, 95% CI 1.14-3.10) during rehabilitation, or an increased anticholinergic burden (ACB ≥ 3) (AOR 2.59, 95% CI 1.41-4.73) were also associated with an increased risk of incident delirium.; We identified a set of factors associated with an increased risk of incident delirium during inpatient rehabilitation. Our findings contribute to detect patients at risk of delirium during inpatient rehabilitation

Flexible and efficient IR using array databases

The Matrix Framework is a recent proposal by IR researchers to flexibly represent all important information retrieval models in a single multi-dimensional array framework. Computational support for exactly this framework is provided by the array database system SRAM (Sparse Relational Array Mapping) that works on top of a DBMS. Information retrieval models can be specified in its comprehension-based array query language, in a way that directly corresponds to the underlying mathematical formulas. SRAM efficiently stores sparse arrays in (compressed) relational tables and translates and optimizes array queries into relational queries. In this work, we describe a number of array query optimization rules and demonstrate their effect on text retrieval in the TREC TeraByte track (TREC-TB) efficiency task, using the Okapi BM25 model as our example. It turns out that these optimization rules enable SRAM to automatically translate the BM25 array queries into the relational equivalent of inverted list processing including compression, score materialization and quantization, such as employed by custom-built IR systems. The use of the high-performance MonetDB/X100 relational backend, that provides transparent database compression, allows the system to achieve very fast response times with good precision and low resource usage

Detecting Incident Delirium within Routinely Collected Inpatient Rehabilitation Data: Validation of a Chart-Based Method

Delirium is a brain condition associated with poor outcomes in rehabilitation. It is therefore important to assess delirium incidence in rehabilitation.; To develop and validate a chart-based method to identify incident delirium episodes within the electronic database of a Swiss rehabilitation clinic, and to identify a study population of validated incident delirium episodes for further research purposes.; Retrospective validation study.; Routinely collected inpatient clinical data from ZURZACH Care.; All patients undergoing rehabilitation at ZURZACH Care, Rehaklinik Bad Zurzach between 2015 and 2018 were included.; Within the study population, we identified all rehabilitation stays for which ≥2 delirium-predictive key words (common terms used to describe delirious patients) were recorded in the medical charts. We excluded all prevalent delirium episodes and defined the remaining episodes to be potentially incident. At least two physicians independently confirmed or refuted each potential incident delirium episode by reviewing the patient charts. We calculated the positive predictive value (PPV) with 95% confidence interval (95% CI) for all potential incident delirium episodes and for specific subgroups.; Within 10,515 rehabilitation stays we identified 554 potential incident delirium episodes. Overall, 125 potential incident delirium episodes were confirmed by expert review. The PPV of the chart-based method varied from 0.23 (95% CI 0.19-0.26) overall to 0.69 (95% CI 0.56-0.79) in specific subgroups.; Our chart-based method was able to capture incident delirium episodes with low to moderate accuracy. By conducting an additional expert review of the medical charts, we identified a study population of validated incident delirium episodes. Our chart-based method contributes towards an automated detection of potential incident delirium episodes that, supplemented with expert review, efficiently yields a validated population of incident delirium episodes for research purposes

Awareness of headache and of National Headache Society activities among primary care physicians - a qualitative study

BACKGROUND Headache is one of the most common symptoms in primary care. To improve the quality of headache diagnosis and management with the largest possible benefit for the general population, headache and pain societies around the world have recently been devoting more attention to headache in primary care.The aim of the study was to investigate the potential contribution that national societies can make toward raising the awareness of primary headaches in general practice. FINDINGS In a qualitative telephone survey, targeting primary care practices (PCP), we asked about the frequency of headache patients in their practices and inquired about their treatment and referral strategies.A total of 1000 telephone interviews with PCP have been conducted. Three-hundred and fifty physicians have been directly interviewed, 95% of them see headache patients every week, 23% daily. Direct MRI referral is done by 84%. Sixty-two per cent of the physicians knew the Swiss headache society, 73% were interested in further education about headaches. CONCLUSION The survey yielded information about the physicians' awareness of the Swiss Headache Society and its activities, and about their desire for continuing education in the area of headache. National headache societies should work to improve the cooperation between headache specialists and PCP, aiming for a better care for our patients with headache

Microsatellite analysis to estimate genetic relationships among five bulgarian sheep breeds

Herein, genetic relationships among five breeds of Bulgarian sheep were estimated using microsatellite markers. The total number of alleles identified was 226 at the 16 loci examined. DA distance values were used for phylogenetic tree construction with the UPGMA algorithm. The two Tsigai and two Maritza populations were found to be geneticallvery closely related to each other y (0.198, and 0.258 respectively). The Pleven Black Head population was distinct from the other four. These results could be useful for preserving genes in these breeds, thereby ensuring their preservation in Bulgaria

Performances in cerebellar and neuromuscular transmission tests are correlated in migraine with aura

In previous studies, we described subclinical abnormalities of neuromuscular transmission and cerebellar functions in migraineurs. The aim of this study was to search if these two functions are correlated in the same patient. Thirteen migraineurs [five without aura (MO) and eight with aura (MA)] underwent both stimulation-SFEMG and 3D-movement analysis. Single fiber EMG (SFEMG) results were expressed as the “mean value of consecutive differences” (mean MCD). Precision of arm-reaching movements (measured with an infrared optoelectronic tracking system) was expressed as the average deviation in the horizontal plane. Median values of mean MCD and mean horizontal deviation were not different between MO and MA. However, in MA, but not in MO, both variables were positively correlated. Thus, we conclude that neuromuscular transmission and cerebellar functions are correlated in the same patient when affected by migraine with aura. We suggest that this correlation might be due to a common molecular abnormality