Scheduling MapReduce Jobs and Data Shuffle on Unrelated Processors

We propose constant approximation algorithms for generalizations of the Flexible Flow Shop (FFS) problem which form a realistic model for non-preemptive scheduling in MapReduce systems. Our results concern the minimization of the total weighted completion time of a set of MapReduce jobs on unrelated processors and improve substantially on the model proposed by Moseley et al. (SPAA 2011) in two directions. First, we consider each job consisting of multiple Map and Reduce tasks, as this is the key idea behind MapReduce computations, and we propose a constant approximation algorithm. Then, we introduce into our model the crucial cost of data shuffle phase, i.e., the cost for the transmission of intermediate data from Map to Reduce tasks. In fact, we model this phase by an additional set of Shuffle tasks for each job and we manage to keep the same approximation ratio when they are scheduled on the same processors with the corresponding Reduce tasks and to provide also a constant ratio when they are scheduled on different processors. This is the most general setting of the FFS problem (with a special third stage) for which a constant approximation ratio is known

On the Approximability of Multistage Min-Sum Set Cover

We investigate the polynomial-time approximability of the multistage version of Min-Sum Set Cover ($\mathrm{DSSC}$), a natural and intriguing generalization of the classical List Update problem. In $\mathrm{DSSC}$, we maintain a sequence of permutations $(\pi^0, \pi^1, \ldots, \pi^T)$ on $n$ elements, based on a sequence of requests $(R^1, \ldots, R^T)$. We aim to minimize the total cost of updating $\pi^{t-1}$ to $\pi^{t}$, quantified by the Kendall tau distance $\mathrm{D}_{\mathrm{KT}}(\pi^{t-1}, \pi^t)$, plus the total cost of covering each request $R^t$ with the current permutation $\pi^t$, quantified by the position of the first element of $R^t$ in $\pi^t$. Using a reduction from Set Cover, we show that $\mathrm{DSSC}$ does not admit an $O(1)$-approximation, unless $\mathrm{P} = \mathrm{NP}$, and that any $o(\log n)$ (resp. $o(r)$) approximation to $\mathrm{DSSC}$ implies a sublogarithmic (resp. $o(r)$) approximation to Set Cover (resp. where each element appears at most $r$ times). Our main technical contribution is to show that $\mathrm{DSSC}$ can be approximated in polynomial-time within a factor of $O(\log^2 n)$ in general instances, by randomized rounding, and within a factor of $O(r^2)$, if all requests have cardinality at most $r$, by deterministic rounding

Comprehensive characterization of the prostate tumor microenvironment identifies CXCR4/CXCL12 crosstalk as a novel antiangiogenic therapeutic target in prostate cancer

Background: Crosstalk between neoplastic and stromal cells fosters prostate cancer (PCa) progression and dissemination. Insight in cell-to-cell communication networks provides new therapeutic avenues to mold processes that contribute to PCa tumor microenvironment (TME) alterations. Here we performed a detailed characterization of PCa tumor endothelial cells (TEC) to delineate intercellular crosstalk between TEC and the PCa TME. Methods: TEC isolated from 67 fresh radical prostatectomy (RP) specimens underwent multi-omic ex vivo characterization as well as orthogonal validation of both TEC functions and key markers by immunohistochemistry (IHC) and immunofluorescence (IF). To identify cell-cell interaction targets in TEC, we performed single-cell RNA sequencing (scRNA-seq) in four PCa patients who underwent a RP to catalogue cellular TME composition. Targets were cross-validated using IHC, publicly available datasets, cell culture expriments as well as a PCa xenograft mouse model. Results: Compared to adjacent normal endothelial cells (NEC) bulk RNA-seq analysis revealed upregulation of genes associated with tumor vasculature, collagen modification and extracellular matrix remodeling in TEC. PTGIR, PLAC9, CXCL12 and VDR were identified as TEC markers and confirmed by IF and IHC in an independent patient cohort. By scRNA-seq we identified 27 cell (sub)types, including endothelial cells (EC) with arterial, venous and immature signatures, as well as angiogenic tip EC. A focused molecular analysis revealed that arterial TEC displayed highest CXCL12 mRNA expression levels when compared to all other TME cell (sub)populations and showed a negative prognostic role. Receptor-ligand interaction analysis predicted interactions between arterial TEC derived CXCL12 and its cognate receptor CXCR4 on angiogenic tip EC. CXCL12 was in vitro and in vivo validated as actionable TEC target by highlighting the vessel number- and density- reducing activity of the CXCR4-inhibitor AMD3100 in murine PCa as well as by inhibition of TEC proliferation and migration in vitro. Conclusions: Overall, our comprehensive analysis identified novel PCa TEC targets and highlights CXCR4/CXCL12 interaction as a potential novel target to interfere with tumor angiogenesis in PCa

Efficient Online Scheduling of Electric Vehicle Charging Using a Service-Price Menu

Along with high penetration of Electric Vehicles (EVs), charging stations are required to service a large amount of charging requests while accounting for constraints on the station's peak electricity consumption. To this end, a charging station needs to make online charging scheduling decisions often under limited future information. An important challenge relates to the prioritization of EVs that have unknown valuations for different levels of charging services. In this paper, we take into consideration the inability of EV users to express these valuations explicitly. We consider a paradigm where a menu of possible charging schedules and corresponding prices is generated online. By letting the EV users pick their most preferable menu option, the proposed algorithm commits on each EV's charging completion time upon its arrival, achieves a near optimal total weighted charging completion time, and prevents the users from strategically misreporting their preferences, while offering a practical and implementable solution to the problem of EVs - charging station interaction

Maternal Dietary Protein Patterns and Neonatal Anthropometrics: A Prospective Study with Insights from NMR Metabolomics in Amniotic Fluid

This study aimed to characterize dietary protein patterns (DPPs) in a sample pool of 298 well-nourished pregnant women and explore potential associations between DPPs and neonatal anthropometrics. Maternal dietary data were collected using a validated food frequency questionnaire. Neonatal anthropometrics were abstracted from health booklets. A hierarchical cluster analysis identified three DPPs: “Dairy-focused”, “Med-fusion”, and “Traditional-inspired”. The “Dairy-focused” DPP exhibited the highest protein intake (p p p p p p p = 0.007) and the lowest ponderal index (p = 0.003). The NMR-metabolomics approach was implemented on a subset of women that provided amniotic fluid (AF) specimens (n = 62) to elucidate distinct metabolic signatures associated with DPPs. PCA and OPLS-DA models verified the adherence to three DPPs, revealing that the levels of several amino acids (AAs) were the highest in “Dairy-focused”, reflecting its protein-rich nature. The “Traditional-inspired” DPP showed decreased AAs and glucose levels. This knowledge may contribute to optimizing maternal dietary recommendations. Further research is needed to validate these findings and better understand the relationships between maternal diet, AF metabolic signature, and neonatal anthropometrics

Somatostatin Infusions Reduce Post-Operative Bile Leak after Hepatopancreatobiliary Surgery: An Observational Preliminary Study

Background: Bile leak is a complication of hepatopancreatobiliary surgery and results from injury to the bile ducts. Treatment usually consists of percutaneous drainage combined with the placement of a biliary stent or a nasobiliary draining tube in the biliary tree via endoscopic retrograde cholangiopancreatography. Animal experiments and studies in humans have shown that somatostatin reduces bile secretion. Objective: To evaluate the efficacy of somatostatin as a conservative monotherapy for the successful management of mild to moderate post-operative bile leak. Place and Duration of Study: 2nd Department of at the University General Hospital of Alexandroupolis, during the period of 2010 and 2012. Patients and Methods: Fifteen patients (11male/4 female) with a mean age of 70.1±4.2 years who developed uncomplicated post-operative bile leak with a daily output ranging from 100ml to 800ml were included in the study. Eleven patients were operated for benign diseases of the liver and biliary tract, while the rest 4 patients for pancreatic or biliary tract malignancies. Somatostatin was administered intravenously to all patients in continuous infusions of 3000μg/12hours until complete recession of bile leak along with total parenteral nutrition. Results: Somatostatin treatment was successful in 14 patients (93.3%), with success being defined as the complete cessation of bile leak. Overall, mean duration of bile leak was 13.8±3.9 days. No major adverse reactions or complications were observed and no patients died. Conclusions: Somatostatin appears to be effective in the treatment of post-operative bile leak. The efficacy of somatostatin is observed both in patients with benign or malignant disease