Staring into the abyss: An evaluation of concurrency control with one thousand cores

Computer architectures are moving towards an era dominated by many-core machines with dozens or even hundreds of cores on a single chip. This unprecedented level of on-chip parallelism introduces a new dimension to scalability that current database management systems (DBMSs) were not designed for. In particular, as the number of cores increases, the problem of concurrency control becomes extremely challenging. With hundreds of threads running in parallel, the complexity of coordinating competing accesses to data will likely diminish the gains from increased core counts. To better understand just how unprepared current DBMSs are for future CPU architectures, we performed an evaluation of concurrency control for on-line transaction processing (OLTP) workloads on many-core chips. We implemented seven concurrency control algorithms on a main-memory DBMS and using computer simulations scaled our system to 1024 cores. Our analysis shows that all algorithms fail to scale to this magnitude but for different reasons. In each case, we identify fundamental bottlenecks that are independent of the particular database implementation and argue that even state-of-the-art DBMSs suffer from these limitations. We conclude that rather than pursuing incremental solutions, many-core chips may require a completely redesigned DBMS architecture that is built from ground up and is tightly coupled with the hardware.Intel Corporation (Science and Technology Center for Big Data

Disparities in Health-Related Quality of Life among Adolescent and Young Adult (AYA) Cancer Survivors

https://openworks.mdanderson.org/sumexp22/1067/thumbnail.jp

Demonstrating Photon Ring Existence with Single-Baseline Polarimetry

Images of supermassive black hole accretion flows contain features of both curved spacetime and plasma structure. Inferring properties of the spacetime from images requires modeling the plasma properties, and vice versa. The Event Horizon Telescope Collaboration has imaged near-horizon millimeter emission from both Messier 87* (M87*) and Sagittarius A* (Sgr A*) with very-long-baseline interferometry (VLBI) and has found a preference for magnetically arrested disk (MAD) accretion in each case. MAD accretion enables spacetime measurements through future observations of the photon ring, the image feature composed of near-orbiting photons. The ordered fields and relatively weak Faraday rotation of MADs yield rotationally symmetric polarization when viewed at modest inclination. In this letter, we utilize this symmetry along with parallel transport symmetries to construct a gain-robust interferometric quantity that detects the transition between the weakly lensed accretion flow image and the strongly lensed photon ring. We predict a shift in polarimetric phases on long baselines and demonstrate that the photon rings in M87* and Sgr A* can be unambiguously detected {with sensitive, long-baseline measurements. For M87* we find that photon ring detection in snapshot observations requires $\sim1$ mJy sensitivity on $>15$ G$\lambda$ baselines at 230 GHz and above, which could be achieved with space-VLBI or higher-frequency ground-based VLBI. For Sgr A*, we find that interstellar scattering inhibits photon ring detectability at 230 GHz, but $\sim10$ mJy sensitivity on $>12$ G$\lambda$ baselines at 345 GHz is sufficient, which is accessible from the ground. For both sources, these sensitivity requirements may be relaxed by repeated observations and averaging.Comment: 14 pages, 7 figures, Accepted to ApJ

Libertà ed equità nei processi di scelta. Il capability approach nell'orientamento

I processi di scelta che indirizzano la vita di un individuo, quelli che orientano i suoi percorsi formativi e professionali, determinano la qualità del suo benessere personale, del suo star bene esistenziale. Il raggiungimento e il perseguimento di questo star bene, e la valorizzazione della qualità della vita per lo sviluppo umano, sono al centro delle riflessioni del capability approach di Amartya Sen. Nell'articolo si presentano i concetti fondamentali per i processi di scelta: - Functionings come stati “di essere e di fare” (being e doing) costitutivi dell'esistenza personale; - Capability come libertà / opportunità di una persona di acquisire i funzionamenti che reputa rilevanti per la propria esistenza; - Well-being (star-bene) come benessere soggettivo dato dai funzionamenti acquisiti; - Agency (agentività) come possibilità e abilità d’azione della persona nel voler raggiungere qualunque cosa essa decida, in quanto agente responsabile

Coexistence of Plasma Cell Dyscrasia with Prefibrotic Stage of Primary Myelofibrosis: A Case Report

Introduction. Coexistence of myeloproliferative neoplasms with lymphoproliferative syndromes has been described in the past, whereas plasma cell dyscrasias seem to be the most common cases. Case Presentation. We present a case of a 59-year-old Caucasian female of Greek origin who presented with thrombocytosis. Clinical and laboratory investigation disclosed the presence of a smoldering myeloma with coexisting histological and molecular characteristics of primary myelofibrosis. The patient had the acquired point mutation V617F in the JAK2 gene but not the bcr-abl rearrangement and was treated for myelofibrosis with subsequent improvement of all haematological parameters without evidence of myelomatic evolution. Conclusion. We present the first case in the literature of a smoldering myeloma coexisting with primary myelofibrosis. The underlying pathogenetic mechanism could be either related to the presence of a pluripotent neoplastic stem cell capable to differentiate into both lymphoid and myeloid cells or be related to two separate nosologic entities

The LOFAR Magnetism Key Science Project

Measuring radio waves at low frequencies offers a new window to study cosmic magnetism, and LOFAR is the ideal radio telescope to open this window widely. The LOFAR Magnetism Key Science Project (MKSP) draws together expertise from multiple fields of magnetism science and intends to use LOFAR to tackle fundamental questions on cosmic magnetism by exploiting a variety of observational techniques. Surveys will provide diffuse emission from the Milky Way and from nearby galaxies, tracking the propagation of long-lived cosmic-ray electrons through magnetic field structures, to search for radio halos around spiral and dwarf galaxies and for magnetic fields in intergalactic space. Targeted deep-field observations of selected nearby galaxies and suspected intergalactic filaments allow sensitive mapping of weak magnetic fields through Rotation Measure (RM) grids. High-resolution observations of protostellar jets and giant radio galaxies reveal structures on small physical scales and at high redshifts, whilst pulsar RMs map large-scale magnetic structures of the Galactic disk and halo in revolutionary detail. The MKSP is responsible for the development of polarization calibration and processing, thus widening the scientific power of LOFAR.Comment: Proceedings of "Magnetic Fields in the Universe: From Laboratory and Stars to Primordial Structures", 2011 Aug. 21-27 in Zakopane/Poland, eds. M. Soida et a

Protocol for the Reconstructing Consciousness and Cognition (ReCCognition) Study

Important scientific and clinical questions persist about general anesthesia despite the ubiquitous clinical use of anesthetic drugs in humans since their discovery. For example, it is not known how the brain reconstitutes consciousness and cognition after the profound functional perturbation of the anesthetized state, nor has a specific pattern of functional recovery been characterized. To date, there has been a lack of detailed investigation into rates of recovery and the potential orderly return of attention, sensorimotor function, memory, reasoning and logic, abstract thinking, and processing speed. Moreover, whether such neurobehavioral functions display an invariant sequence of return across individuals is similarly unknown. To address these questions, we designed a study of healthy volunteers undergoing general anesthesia with electroencephalography and serial testing of cognitive functions (NCT01911195). The aims of this study are to characterize the temporal patterns of neurobehavioral recovery over the first several hours following termination of a deep inhaled isoflurane general anesthetic and to identify common patterns of cognitive function recovery. Additionally, we will conduct spectral analysis and reconstruct functional networks from electroencephalographic data to identify any neural correlates (e.g., connectivity patterns, graph-theoretical variables) of cognitive recovery after the perturbation of general anesthesia. To accomplish these objectives, we will enroll a total of 60 consenting adults aged 20–40 across the three participating sites. Half of the study subjects will receive general anesthesia slowly titrated to loss of consciousness (LOC) with an intravenous infusion of propofol and thereafter be maintained for 3 h with 1.3 age adjusted minimum alveolar concentration of isoflurane, while the other half of subjects serves as awake controls to gauge effects of repeated neurobehavioral testing, spontaneous fatigue and endogenous rest-activity patterns

Wait times among patients with symptomatic carotid artery stenosis requiring carotid endarterectomy for stroke prevention

BackgroundCurrent Canadian and international guidelines suggest patients with transient ischemic attack (TIA) or nondisabling stroke and ipsilateral internal carotid artery stenosis of 50% to 99% should be offered carotid endarterectomy (CEA) ≤2 weeks of the incident TIA or stroke. The objective of the study was to identify whether these goals are being met and the factors that most influence wait times.MethodsPatients who underwent CEA at the Ottawa Hospital for symptomatic carotid artery stenosis from 2008 to 2010 were identified. Time intervals based on the dates of initial symptoms, referral to and visit with a vascular surgeon, the decision to operate, and the date of surgery were recorded for each patient. The influence of various factors on wait times was explored, including age, sex, type of index event, referring physician, distance from the surgical center, degree of stenosis, and surgeon assigned.ResultsOf the 117 patients who underwent CEA, 92 (78.6%) were symptomatic. The median time from onset of symptoms to surgery for all patients was 79 days (interquartile range [IQR], 34-161). The shortest wait times were observed in stroke patients (49 [IQR, 27-81] days) and inpatient referrals (66 [IQR, 25-103] days). Only 7 of the 92 symptomatic patients (8%) received care within the recommended 2 weeks. The median surgical wait time for all patients was 14 days (IQR, 8-25 days). In the multivariable analysis, significant predictors of longer wait times included retinal TIA (P = .003), outpatient referrals (P = .004), and distance from the center (P = .008). Patients who presented to the emergency department had the shortest delays in seeing a vascular surgeon and subsequently undergoing CEA (P < .0001). There was no difference between surgeons for wait times to be seen in the clinic; however, there were significant differences among surgeons once the decision was made to proceed with CEA.ConclusionsOur wait times for CEA currently do not fall within the recommended 2-week guideline nor does it appear feasible within the current system. Important factors contributing to delays include outpatient referrals, living farther from the hospital, and presenting with a retinal TIA (amaurosis fugax). Our findings also suggest better scheduling practices once a decision is made to operate can modestly improve overall and surgical wait times for CEA