3,815 research outputs found

    Blockchain, Leadership And Management: Business AS Usual Or Radical Disruption?

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    The Internet provided the world with interconnection. However, it did not provide it with trust. Trust is lacking everywhere in our society and is the reason for the existence of powerful intermediaries aggregating power. Trust is what prevents the digital world to take over. This has consequences for organisations: they are inefficient because time, energy, money and passion are wasted on verifying everything happens as decided. Managers play the role of intermediaries in such case: they connect experts with each others and instruct them of what to do. As a result, in our expert society, people's engagement is low because no one is there to inspire and empower them. In other words, our society faces an unprecedented lack of leadership. Provided all those shortcomings, the study imagines the potential repercussions, especially in the context of management, of implementing a blockchain infrastructure in any type of organisation. Indeed, the blockchain technology seems to be able to remedy to those issues, for this distributed and immutable ledger provides security, decentralisation and transparency. In the context of a blockchain economy, the findings show that value creation will be rearranged, with experts directly collaborating with each others, and hierarchy being eliminated. This could, in turn, render managers obsolete, as a blockchain infrastructure will automate most of the tasks. As a result, only a strong, action-oriented, leadership would maintain the organisation together. This leadership-in-action would consist in igniting people to take action; coach members of the organisations so that their contribution makes sense in the greater context of life

    Représenter la nature ? : ONG et biodiversité

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    Ray model and ray-wave correspondence in coupled optical microdisks

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    We introduce a ray model for coupled optical microdisks, in which we select coupling-efficient rays among the splitting rays. We investigate the resulting phase-space structure and report island structures arising from the ray-coupling between the two microdisks. We find the microdisks's refractive index to influence the phase-space structure and calculate the stability and decay rates of the islands. Turning to ray-wave correspondence, we find many resonances to be directly related to the presence of these islands. We study the relation between the (ray-picture originating) island structures and the (wave-picture originating) spectral properties of resonances, especially the leakiness of the resonances which is represented as the imaginary part of the complex wave vector.Comment: 9 pages, 8 figure

    Reducing the Effects of Unequal Number of Games on Rankings

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    Ranking is an important mathematical process in a variety of contexts such as information retrieval, sports and business. Sports ranking methods can be applied both in and beyond the context of athletics. In both settings, once the concept of a game has been defined, teams (or individuals) accumulate wins, losses, and ties, which are then factored into the ranking computation. Many settings involve an unequal number of games between competitors. This paper demonstrates how to adapt two sports rankings methods, the Colley and Massey ranking methods, to settings where an unequal number of games are played between the teams. In such settings, the standard derivations of the methods can produce nonsensical rankings. This paper introduces the idea of including a super-user into the rankings and considers the effect of this fictitious player on the ratings. We apply such techniques to rank batters and pitchers in Major League baseball, professional tennis players, and participants in a free online social game. The ideas introduced in this paper can further the scope that such methods are applied and the depth of insight they offer

    A Nonnegative Analysis of Politics

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    The article investigates how linear algebra can recover mathematical information from the electronic messages using the Enron Email Sets in Pennsylvania. It states that a term-by-email matrix has been created to cluster algorithm, which allows one to mine through data and discover meaning. Moreover, nonnegative matrix factorization (NMF) enables one to interpret the resulting factorization in terms of the original problem

    Comorbidities and Race/Ethnicity Among Adults with Stimulant Use Disorders in Residential Treatment

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    Comorbid physical and mental health problems are associated with poorer substance abuse treatment outcomes; however, little is known about these conditions among stimulant abusers at treatment entry. This study compared racial and ethnic groups on baseline measures of drug use patterns, comorbid physical and mental health disorders, quality of life, and daily functioning among cocaine and stimulant abusing/dependent patients. Baseline data from a multi-site randomized clinical trial of vigorous exercise as a treatment strategy for a diverse population of stimulant abusers (N = 290) were analyzed. Significant differences between groups were found on drug use characteristics, stimulant use disorders, and comorbid mental and physical health conditions. Findings highlight the importance of integrating health and mental health services into substance abuse treatment and could help identify potential areas for intervention to improve treatment outcomes for racial and ethnic minority groups

    Étude de l'enlèvement du Cd, Cu, Mn et Zn par solubilisation biologique dans les sédiments lacustres fortement contaminés

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    Des essais en erlenmeyers de 0,5 L ont été faits afin d'évaluer les possibilités d'application d'un procédé de solubilisation biologique aux sédiments. Ce procédé utilise la capacité des thiobacilles de lixivier les métaux en milieu acide. Au cours des essais, l'influence, sur la solubilisation des métaux, de la quantité de substrat (FeSO4 × 7H2O), du pourcentage d'inoculum et de la teneur en solides totaux a été suivie. La concentration de substrat n'a pas d'effet sur l'enlèvement du Cd, du Zn, du Mn et du Cu. Les taux d'enlèvement moyens pour le Cd, Zn et Mn, sont, après 46 heures, de 70 à 90 %, 90 à 100 % et 64 à 72 % pour des concentrations de substrat variant de 0 à 30 % FeSO4 × 7H2O (poids sec/poids sec). A 29 et 46 heures, des coefficients de détermination (r2) de 0,46 et 0,59 entre le pH et la concentration de FeSO4 × 7H2O, et de 0,92 et 0,55 entre le POR et la concentration de FeSO4 × 7H2O ont été trouvés. A plus forte teneur en FeSO4 × 7H2O, le POR est moins élevé, surtout au début des essais. La présence des ions ferreux en plus grande quantité expliquerait les plus faibles valeurs du potentiel-rédox. A 20 % d'inoculum, la solubilisation des métaux est optimale avec une solubili- sation de 86 % pour le Cd et 73 % pour le Cu et le Mn. La forte corrélation entre le POR, le pH et le pourcentage d'inoculum (r2 à 29, 46 et 70 heures de 0,94, 0,94 et 0,63 pour le POR et le pourcentage d'inoculum et de 0,80, 0,69 et 0,60 pour le pH et le pourcentage d'inoculum), a permis d'établir une corrélation entre le POR, le pH et la solubilisation du Cu. Les seuils trouvés permettant une solubilisation du Cu supérieure à 10 % sont un pH de 3,75 et un POR de 260 mV.L'augmentation des solides totaux (ST) semble limiter le développement des thiobacilles et diminue les rendements de solubilisation du Cd (à 21 heures) et du Zn (à 45 heures). Ainsi, pour le Cd, les pourcentages de solubilisation passent de 71 % à 24 % pour 3 et 15 % ST, alors que dans le cas du Zn, ils diminuent de 94 % à 81 % pour 3 et 15 % ST. La solubilisation du Mn serait, pour sa part, plutôt de type chimique.In the province of Québec, the St-Lawrence Seaway as well as the harbour areas undergo frequent dredging. Each year, more than 106 cubic metres of sediments must be dredged from the st-Lawrence river. The dredged sedirnents are generally dispersed in the water column. However, heavy metal contamination of these sediments may preclude open-water disposal and necessitate their confinement.The research work presented in this article applies to dredged sediments that are too contaminated for open-water disposal. In order to permit their safe disposal, it is necessary to have a method which effectively removes metals from these sediments. One of the effective methods of metal removal from contaminated sediments could be a microbial solubilization process, which was developed at INRS-Eau for sewage sludge decontamination and which has been tested on a pilot scale during the past year. In order to appty such a process to decontaminate sediments, it was necessary to study the influence of various factors affecting the microbial leaching process. This research verified the possibility of using a modified microbial leaching process to decontaminate sediments and also studied the influence of the enerry substrate, the microbial inoculum and the sediment total solids concentration on such a modified process.The experimental methodology consisted of mixing the contaminated sediment in a 500 ml Erlenmeyer flask for a period of 96 hours in the presence of thiobacillus inoculum and ferrous sulfate (FeSO4 • 7H2O) as the enerry substrate. Before each experiment sediments were adjusted to the desired total solids concentration with deionized water and were acidified with sulfuric acid to obtain the starting pH conditions.The solubilization of Cd, Cu, Zn and Mn was monitored at regular intervals in order to evaluate the influence of the various factors studied. Subsamples were removed, the sediments were digested and the metals were analyzed by inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The elements analyzed were Al, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb,Zn as well as S, P and C. All the digestions and analyses performed made according to the APHA guidelines. The total solids, both volatile and inert, were also determined according to APHA method no.209F (APHA, 1985).Regarding the influence of the ferrous sulfate concentration on the application of the microbial leaching process, the removal rates of Cd, Zn and Mn did not vary more than 12 %. For all experiments, the final pH value approached 2,5. The oxidation-reduction potential (ORP) varied for all experiments from 462 to 560 mV. An energy source could therefore be present in the sediments, which would support the growth of thiobacillus bacteria.During the experiments conducted to study the influence of inoculum concentration on the microbial leaching process, it was found that the pH decreased from 3.5 to 2.4 and the ORP increased from 284 to 593 mV when the inoculum addition increased from 0 to 30 % (v/v). This tendency was also observed during the removal of Cd and above all, Cu. Between 0 and 20 % (v/v) inoculum concentration, Cd removal increased from 64 to 86 % whereas Cu removal increased from 20 to73 %. However, these two metals did not show any appreciable increase in solubilization when the inoculum was increased from 20 to 30 % (v/v). In the case of Mn, it was not possible to determine the solubilization pattern since the inoculum concentration did not influence the solubilization of this element, Between 0 and 30 % inoculum, the Mn removal varied from 56 to 73 %. Hence the microbial influence on Mn solubilization may be negligible.The study on the influence of total solids content on the microbial leaching process showed that the total solids concentration had an influence on pH and ORP. The final pH increased from 2.43 to 3.32 and ORP decreasedfrom 492 to 321 mV when the total solids content was varied from 3 to 15 % . The percent solubilization of Cd after 21 h was 7l %, 69 %, 43 %, 44 % and, 24 % at 3, 5, 7, 10 and 15 % total solids respectively, On the other hand, Zn solubilization after 45 h was 94 %, 90 %, 84 %, 97 % and 8l % for the same concentrations of total solids. An increase in total solids content decreased the solubilization efficiency of Cd (at t=2l h) and, to a lesser extent, Zn (att=48h). However,in the case of Mn, the maximum solubilization was achieved right at the beginning and varied little with time. Its solubilization varied between 61 and 70 % for 3 % total solids, between 67 and, 79 % for 5 % total dolids, between 52 and,62 % for 7 % totaf solids, between 57 and, 75 % for l0 % total solids and tretween 40 and 63 % for 15 % total solids. In general, for the sediments studied here, total solids content has little influence on Mn solubilization.In conclusion, use of a microbial leaching process to remove metals from contaminated sediments seems to be less complex than for sewage sludges, since the maximum removal of metals is achieved in less than 48 h in a bench-scale experiment. The average metal solubilization was above 80 % for Cd, 73 % for Cu, 90 % for Zn and 65 % for Mn. The development of thiobacillus does not seem to be dependent upon the presence of an added energy substrate. Only a minimal quantity of substrate, say 5 % ferrous sulfate (dry wt./dry wt.), is required in order to assure optimal conditions for thiobacillus growth. It is probable that with time, without ferrous sulfate, the microbial conditions would deteriorate due to exhaustion ofthe enerry substrate. A 20 % microbial inoculum seems to be enough to assure an efficient metal solubilization process. Except for Mn, the increase in total solids concentration had a negative influence on the metal solubilization. It is hence preferable to work with a total solids concentration of less than 5 %. Nevertheless, it should be noted that this percentage is more than that used for sewage sludge decontaminaton (around 2 % total solids)

    BLOCKCHAIN, LEADERSHIP AND MANAGEMENT: BUSINESS AS USUAL OR RADICAL DISRUPTION?

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    The Internet provided the world with interconnection. However, it did not provide it with trust. Trust is lacking everywhere in our society and is the reason for the existence of powerful intermediaries aggregating power. Trust is what prevents the digital world to take over. This has consequences for organisations: they are inefficient because time, energy, money and passion are wasted on verifying everything happens as decided. Managers play the role of intermediaries in such case: they connect experts with each others and instruct them of what to do. As a result, in our expert society, people’s engagement is low because no one is there to inspire and empower them. In other words, our society faces an unprecedented lack of leadership. Provided all those shortcomings, the study imagines the potential repercussions, especially in the context of management, of implementing a blockchain infrastructure in any type of organisation. Indeed, the blockchain technology seems to be able to remedy to those issues, for this distributed and immutable ledger provides security, decentralisation and transparency. In the context of a blockchain economy, the findings show that value creation will be rearranged, with experts directly collaborating with each others, and hierarchy being eliminated. This could, in turn, render managers obsolete, as a blockchain infrastructure will automate most of the tasks. As a result, only a strong, action-oriented, leadership would maintain the organisation together. This leadership-in-action would consist in igniting people to take action; coach members of the organisations so that their contribution makes sense in the greater context of life

    Thick films of YSZ electrolytes by dip-coating process

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    Yttria stabilized zirconia (YSZ, 8% Y2O3) thick films were coated on porous Ni-YSZ substrates using the dip-coating process and a suspension with a new formulation. The suspension was obtained by addition of a polymeric matrix in a stable suspension of a commercial YSZ (Tosoh) powders dispersed in an azeotropic MEK-EtOH mixture. The green layers were densified after an optimization of the suspension composition. YSZ Tosoh particles encapsulated by a zirconium alkoxide sol and added with colloidal alkoxide precursor are used to load the suspension. The in situ growth of these colloids increases significantly the layers density after an appropriated heat treatment. The obtained films are continuous, homogeneous and 20 μm thick. Different microstructures are obtained depending on the synthesis parameters of the suspension

    Backward error analysis and the substitution law for Lie group integrators

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    Butcher series are combinatorial devices used in the study of numerical methods for differential equations evolving on vector spaces. More precisely, they are formal series developments of differential operators indexed over rooted trees, and can be used to represent a large class of numerical methods. The theory of backward error analysis for differential equations has a particularly nice description when applied to methods represented by Butcher series. For the study of differential equations evolving on more general manifolds, a generalization of Butcher series has been introduced, called Lie--Butcher series. This paper presents the theory of backward error analysis for methods based on Lie--Butcher series.Comment: Minor corrections and additions. Final versio
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