180 research outputs found
Spinning Fast Iterative Data Flows
Parallel dataflow systems are a central part of most analytic pipelines for
big data. The iterative nature of many analysis and machine learning
algorithms, however, is still a challenge for current systems. While certain
types of bulk iterative algorithms are supported by novel dataflow frameworks,
these systems cannot exploit computational dependencies present in many
algorithms, such as graph algorithms. As a result, these algorithms are
inefficiently executed and have led to specialized systems based on other
paradigms, such as message passing or shared memory. We propose a method to
integrate incremental iterations, a form of workset iterations, with parallel
dataflows. After showing how to integrate bulk iterations into a dataflow
system and its optimizer, we present an extension to the programming model for
incremental iterations. The extension alleviates for the lack of mutable state
in dataflows and allows for exploiting the sparse computational dependencies
inherent in many iterative algorithms. The evaluation of a prototypical
implementation shows that those aspects lead to up to two orders of magnitude
speedup in algorithm runtime, when exploited. In our experiments, the improved
dataflow system is highly competitive with specialized systems while
maintaining a transparent and unified dataflow abstraction.Comment: VLDB201
ΠΠ΅Π΄Π°Π³ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ΅Ρ Π½ΠΎΠ»ΠΎΠ³ΠΈΠΈ ΠΊΠ°ΠΊ Π΄ΠΈΠ΄Π°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΈΠ½ΡΡΡΡΠΌΠ΅Π½ΡΠ°ΡΠΈΠΉ ΠΏΠΎΠ΄Π³ΠΎΡΠΎΠ²ΠΊΠΈ ΡΠΏΠ΅ΡΠΈΠ°Π»ΠΈΡΡΠ° Π² ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠΌ Π²ΡΠ·Π΅
Π Π°ΡΡΠΌΠΎΡΡΠ΅Π½ΠΎ ΠΏΠΎΠ½ΡΡΠΈΠ΅ ΠΏΠ΅Π΄Π°Π³ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΈ, ΡΠ°ΡΠΊΡΡΡΠ° ΡΡΡΠ½ΠΎΡΡΡ ΠΊΠΎΠ½ΡΠ΅ΠΊΡΡΠ½ΠΎΠΉ ΠΈ Π·Π°Π΄Π°ΡΠ½ΠΎΠΉ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ, ΠΎΠ±ΠΎΡΠ½ΠΎΠ²Π°Π½ Π²ΡΠ±ΠΎΡ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ, Π°Π΄Π΅ΠΊΠ²Π°ΡΠ½ΡΡ
ΠΏΡΠΎΡΠΈΠ»Ρ ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎΠ³ΠΎ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ
Assessment of transcriptional reprogramming of lettuce roots in response to chitin soil amendment
Chitin soil amendment is known to improve soil quality, plant growth and stress resilience, but the underlying mechanisms are not well understood. In this study, we monitored chitin's effect on lettuce physiology every two weeks through an eight-week growth period, analyzed the early transcriptional reprogramming and related metabolomic changes of lettuce, in response to crab chitin treatment in peat-based potting soil. In commercial growth conditions, chitin amendment still promoted lettuce growth, increased chlorophyll content, the number of leaves and crop head weight from week six. The flavonoid content in lettuce leaves was altered as well, showing an increase at week two but a decrease from week six. Transcriptomic analysis showed that over 300 genes in lettuce root were significantly differentially expressed after chitin soil treatment. Gene Ontology-term (GO) enrichment analysis revealed statistical overrepresentation of GO terms linked to photosynthesis, pigment metabolic process and phenylpropanoid metabolic process. Further analysis of the differentially expressed genes (DEGs) showed that the flavonoid pathway was mostly upregulated whereas the bifurcation of upstream phenylpropanoid pathway towards lignin biosynthesis was mostly downregulated. Metabolomic analysis revealed the upregulation of salicylic acid, chlorogenic acid, ferulic acid, and p-coumaric acid in chitin-treated lettuce seedlings. These phenolic compounds (PCs) mainly influence the phenylpropanoid biosynthesis pathway and may play important roles in plant defense reactions. Our results suggest that chitin soil amendments might activate induced resistance by priming lettuce plants and promote lettuce growth via transcriptional changes
The Severity of Human Peri-Implantitis Lesions Correlates with the Level of Submucosal Microbial Dysbiosis
AIM
To cross-sectionally analyse the submucosal microbiome of peri-implantitis (PI) lesions at different severity levels.
MATERIALS AND METHODS
Microbial signatures of 45 submucosal plaque samples from untreated PI lesions obtained from 30 non-smoking, systemically healthy subjects were assessed by 16s sequencing. Linear mixed models were used to identify taxa with differential abundance by probing depth, after correction for age, gender, and multiple samples per subject. Network analyses were performed to identify groups of taxa with mutual occurrence or exclusion. Subsequently, the effects of peri-implant probing depth on submucosal microbial dysbiosis were calculated using the microbial dysbiosis index.
RESULTS
In total, we identified 337 different taxa in the submucosal microbiome of PI. Total abundance of 12 taxa correlated significantly with increasing probing depth; a significant relationship with lower probing depth was found for 16 taxa. Network analysis identified two mutually exclusive complexes associated with shallow pockets and deeper pockets, respectively. Deeper peri-implant pockets were associated with significantly increased dysbiosis.
CONCLUSION
Increases in peri-implant pocket depth are associated with substantial changes in the submucosal microbiome and increasing levels of dysbiosis
Diagnostic Value of Fully Automated Artificial Intelligence Powered Coronary Artery Calcium Scoring from 18F-FDG PET/CT
OBJECTIVES
The objective of this study was to assess the feasibility and accuracy of a fully automated artificial intelligence (AI) powered coronary artery calcium scoring (CACS) method on ungated CT in oncologic patients undergoing 18F-FDG PET/CT.
METHODS
A total of 100 oncologic patients examined between 2007 and 2015 were retrospectively included. All patients underwent 18F-FDG PET/CT and cardiac SPECT myocardial perfusion imaging (MPI) by 99mTc-tetrofosmin within 6 months. CACS was manually performed on non-contrast ECG-gated CT scans obtained from SPECT-MPI (i.e., reference standard). Additionally, CACS was performed using a cloud-based, user-independent tool (AI-CACS) on ungated CT scans from 18F-FDG-PET/CT examinations. Agatston scores from the manual CACS and AI-CACS were compared.
RESULTS
On a per-patient basis, the AI-CACS tool achieved a sensitivity and specificity of 85% and 90% for the detection of CAC. Interscore agreement of CACS between manual CACS and AI-CACS was 0.88 (95% CI: 0.827, 0.918). Interclass agreement of risk categories was 0.8 in weighted Kappa analysis, with a reclassification rate of 44% and an underestimation of one risk category by AI-CACS in 39% of cases. On a per-vessel basis, interscore agreement of CAC scores ranged from 0.716 for the circumflex artery to 0.863 for the left anterior descending artery.
CONCLUSIONS
Fully automated AI-CACS as performed on non-contrast free-breathing, ungated CT scans from 18F-FDG-PET/CT examinations is feasible and provides an acceptable to good estimation of CAC burden. CAC load on ungated CT is, however, generally underestimated by AI-CACS, which should be taken into account when interpreting imaging findings
Splenic switch-off as a predictor for coronary adenosine response: validation against 13N-ammonia during co-injection myocardial perfusion imaging on a hybrid PET/CMRΒ scanner
BACKGROUND
Inadequate coronary adenosine response is a potential cause for false negative ischemia testing. Recently, the splenic switch-off (SSO) sign has been identified as a promising tool to ascertain the efficacy of adenosine during vasodilator stress cardiovascular magnetic resonance imaging (CMR). We assessed the value of SSO to predict adenosine response, defined as an increase in myocardial blood flow (MBF) during quantitative stress myocardial perfusion 13Β N-ammonia positron emission tomography (PET).
METHODS
We prospectively enrolled 64 patients who underwent simultaneous CMR and PET myocardial perfusion imaging on a hybrid PET/CMR scanner with co-injection of gadolinium based contrast agent (GBCA) and 13N-ammonia during rest and adenosine-induced stress. A myocardial flow reserve (MFR) ofβΒ >β1.5 or ischemia as assessed by PET were defined as markers for adequate coronary adenosine response. The presence or absence of SSO was visually assessed. The stress-to-rest intensity ratio (SIR) was calculated as the ratio of stress over rest peak signal intensity for splenic tissue. Additionally, the spleen-to-myocardium ratio, defined as the relative change of spleen to myocardial signal, was calculated for stress (SMR) and rest.
RESULTS
Sixty-one (95%) patients were coronary adenosine responders, but SSO was absent in 18 (28%) patients. SIR and SMR were significantly lower in patients with SSO (SIR: 0.56βΒ±β0.13 vs. 0.93βΒ±β0.23; pβ<β0.001 and SMR: 1.09βΒ±β0.47 vs. 1.68βΒ±β0.62; pβ<β0.001). Mean hyperemic and rest MBF were 2.12βΒ±β0.68Β ml/min/g and 0.78βΒ±β0.26Β ml/min/g, respectively. MFR was significantly higher in patients with vs. patients without presence of SSO (3.07βΒ±β1.03 vs. 2.48βΒ±β0.96; pβ=β0.038), but there was only a weak inverse correlation between SMR and MFR (Rβ=β-0.378; pβ=β0.02) as well as between SIR and MFR (Rβ=β-0.356; pβ=β0.004).
CONCLUSIONS
The presence of SSO implies adequate coronary adenosine-induced MBF response. Its absence, however, is not a reliable indicator for failed adenosine-induced coronary vasodilatation
Fulani cattle productivity and management in the Kachia grazing reserve, Nigeria
Kachia Grazing Reserve (KGR) in northern Nigeria was home to some 10,000 Fulani pastoralists and their 40,000 cattle in June 2011. This study examines productivity and management of cattle belonging to livestock keepers within the reserve before and after a mass immigration event when 3,000 refugees moved into the reserve with their cattle to escape inter-community violence during May 2011. Data, on livestock management strategies (transhumance) and production parameters (herd size, composition, fertility, dynamics), were collected in March, June and October 2011.Cattle productivity in KGR is geared to supporting Fulani households while maintaining herd wealth. High offtake of young animals, especially the selling of heifers, was an unusual finding and may indicate that KGR pastoralists have been restricting their herd size voluntarily as well as limiting milk production to household requirements. This is probably due to the absence of a commercial milk market and a higher reliance on the sale of young stock to meet cash needs.Despite the widespread perception that grazing reserves are promoting sedentarisation of Fulani pastoralists and curbing transhumance, the inhabitants of the KGR were observed to practise wide-ranging transhumance both during wet and dry seasons driven by the limited availability of grazing. Some households selected a sub-sample of animals for transhumance rather than sending their whole herd, and some maintained cattle on alternative land-holdings outside the reserve. KGR households described modifying their usual transhumance practices in response to the mass immigration event and insecurity.Nevertheless, the herd demography results from this study are broadly similar to data obtained from other studies over the past 40 years, indicating that productivity and management practices have remained relatively unchanged
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