Middleware-based Database Replication: The Gaps between Theory and Practice

The need for high availability and performance in data management systems has been fueling a long running interest in database replication from both academia and industry. However, academic groups often attack replication problems in isolation, overlooking the need for completeness in their solutions, while commercial teams take a holistic approach that often misses opportunities for fundamental innovation. This has created over time a gap between academic research and industrial practice. This paper aims to characterize the gap along three axes: performance, availability, and administration. We build on our own experience developing and deploying replication systems in commercial and academic settings, as well as on a large body of prior related work. We sift through representative examples from the last decade of open-source, academic, and commercial database replication systems and combine this material with case studies from real systems deployed at Fortune 500 customers. We propose two agendas, one for academic research and one for industrial R&D, which we believe can bridge the gap within 5-10 years. This way, we hope to both motivate and help researchers in making the theory and practice of middleware-based database replication more relevant to each other.Comment: 14 pages. Appears in Proc. ACM SIGMOD International Conference on Management of Data, Vancouver, Canada, June 200

Redox Mediation at 11-Mercaptoundecanoic Acid Self-Assembled Monolayers on Gold

Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and digital simulation techniques were used to investigate quantitatively the mechanism of electron transfer (ET) through densely packed and well-ordered self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid on gold, either pristine or modified by physically adsorbed glucose oxidase (GOx). In the presence of ferrocenylmethanol (FcMeOH) as a redox mediator, ET kinetics involving either solution-phase hydrophilic redox probes such as [Fe(CN)6]3-/4- or surface-immobilized GOx is greatly accelerated: [Fe(CN)6]3-/4- undergoes diffusion-controlled ET, while the enzymatic electrochemical conversion of glucose to gluconolactone is efficiently sustained by FcMeOH. Analysis of the results, also including the digital simulation of CV and EIS data, showed the prevalence of an ET mechanism according to the so-called membrane model that comprises the permeation of the redox mediator within the SAM and the intermolecular ET to the redox probe located outside the monolayer. The analysis of the catalytic current generated at the GOx/SAM electrode in the presence of glucose and FcMeOH allowed the high surface protein coverage suggested by X-ray photoelectron spectroscopy (XPS) measurements to be confirmed.

Fungal communities isolated from dead apple leaves from orchards in Quebec

Le champignon causant la tavelure du pommier, Venturia inaequalis, hiverne dans les feuilles mortes de pommier (Malus pumila) sous forme de pseudothèces. Les objectifs de cette étude étaient de monter une collection de champignons afin de vérifier subséquemment leur résistance au froid et leur potentiel antagoniste contre V. inaequalis et d'acquérir des connaissances sur la microflore des feuilles mortes de pommiers. Des champignons ont été isolés sur des feuilles mortes de pommiers récoltées au printemps et à l'automne de 1993. Au total, 345 isolats fongiques provenant de 49 genres ont été identifiés. Quinze genres sont rapportés pour la première fois comme colonisateurs des feuilles de pommiers en Amérique du Nord.Venturia inaequalis, the causal agent of apple scab, overwinters in apple (Malus pumila) leaves on the orchard floor by producing pseudothecia. The objectives of this survey were to make a collection of fungi to be subsequently tested for their potential as psychrophile biocontrol agents against V. inaequalis and to acquire knowledge on the diversity of the microflora of dead apple leaves. Fungi were recovered from dead apple leaves collected in the spring and fall of 1993. A total of 345 isolates from 49 genera were identified. Fifteen gene were not previously recorded as colonizers of apple leaves in North America

The design and commissioning of the MICE upstream time-of-flight system

In the MICE experiment at RAL the upstream time-of-flight detectors are used for particle identification in the incoming muon beam, for the experiment trigger and for a precise timing (sigma_t ~ 50 ps) with respect to the accelerating RF cavities working at 201 MHz. The construction of the upstream section of the MICE time-of-flight system and the tests done to characterize its individual components are shown. Detector timing resolutions ~50-60 ps were achieved. Test beam performance and preliminary results obtained with beam at RAL are reported.Comment: accepted on Nuclear Instruments and Methods

The Speech of Athenagoras in Thucydides 6.36–40: Demagoguery and Democracy in Syracuse

Il presente contributo prende in esame il discorso di Atenagora di Siracusa in Tucidide 6.36-40. Tucidide costruisce la figura di Atenagora sul modello dei demagoghi ateniesi, ma anche basandosi su ciò che sapeva dell’opposizione interna a Ermocrate a Siracusa e, in generale, utilizzando le informazioni che aveva sulla democrazia di Siracusa. Sebbene il discorso sia frutto della creatività retorica di Tucidide, lo storico non trascura i principi dei τὰ δέοντα and della ξύμπασα γνώμη delineati nel famoso capitolo sul metodo (1.22). L’immagine della democrazia siracusana che emerge dalle parole di Atenagora non è semplicemente uno specchio della democrazia ateniese. Il discorso contiene interessanti indizi di un’idea e prassi della democrazia, del potere e della leadership che sono sostanzialmente diverse da quelle ateniesi. Il discorso del demagogo siracusano fornisce quindi elementi importanti, utili a comprendere per quali ragioni Aristotele, nella Politica, definisce Siracusa nel periodo tra il 466/5 e il 413 a.C. come una πολιτεία (ovvero una costituzione mista) e non come una δημοκρατία.This paper discusses the speech of Athenagoras in Thucydides 6.36–40. Thucydides sketches Athenagoras’ profile based on his knowledge of Athenian demagogues, his (probably scanty) knowledge of the Syracusan opposition to Hermocrates, and his knowledge of Syracusan democracy. I argue, first, that, despite freely composing Athenagoras’ speech, Thucydides does follow the principle of τὰ δέοντα and ξύμπασα γνώμη τῶν ἀληθῶς λεχθέντων that he introduces in his methodological chapter at 1.22.1. Second, that the picture of Syracusan democracy that Athenagoras provides in his excursus on democracy is not simply a mirror of Athenian democracy. The speech contains clues about a specific Syracusan view of democracy, power and leadership, which might also explain why Aristotle defines Syracuse in the period from 466/5 to 413 BC as a πολιτεία (i.e., a mixed constitution, halfway between oligarchy and democracy) and not as a δημοκρατία

Macroscopic transport by synthetic molecular machines

Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with—and perform physical tasks in—the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (‘molecular shuttles’) to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.

MICE: the Muon Ionization Cooling Experiment. Step I: First Measurement of Emittance with Particle Physics Detectors

The Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) detectors was performed. The analysis of these data was recently completed and is discussed in this paper. Future steps for MICE, where beam emittance and emittance reduction (cooling) are to be measured with greater accuracy, are also presented

Interpreter-Mediated Therapy for Refugees: A Need for Awareness and Training

This brief report discusses the challenges arising from interpreter-mediated therapy in the treatment of refugees with Post Traumatic Stress Disorder (PTSD). Although the refugee population continues to grow in the United States, the treatment competency of mental health professionals working with this population has not adequately responded to this growth. As a result of the trauma often experienced by refugees many present with PTSD symptomatology and require trauma-focused mental health care. Language disparities between clinical psychologists and refugees often result in the need for interpreter-mediated therapy, yet psychologists lack awareness and relevant training in working collaboratively with interpreters to provide competent care. The complex reality of interpreter-mediated therapy can involve substantial deviations from the refugee’s original message and deprive refugees from receiving adequate treatment