Pre-logarithmic and logarithmic fields in a sandpile model

We consider the unoriented two-dimensional Abelian sandpile model on the half-plane with open and closed boundary conditions, and relate it to the boundary logarithmic conformal field theory with central charge c=-2. Building on previous results, we first perform a complementary lattice analysis of the operator effecting the change of boundary condition between open and closed, which confirms that this operator is a weight -1/8 boundary primary field, whose fusion agrees with lattice calculations. We then consider the operators corresponding to the unit height variable and to a mass insertion at an isolated site of the upper half plane and compute their one-point functions in presence of a boundary containing the two kinds of boundary conditions. We show that the scaling limit of the mass insertion operator is a weight zero logarithmic field.Comment: 18 pages, 9 figures. v2: minor corrections + added appendi

Height variables in the Abelian sandpile model: scaling fields and correlations

We compute the lattice 1-site probabilities, on the upper half-plane, of the four height variables in the two-dimensional Abelian sandpile model. We find their exact scaling form when the insertion point is far from the boundary, and when the boundary is either open or closed. Comparing with the predictions of a logarithmic conformal theory with central charge c=-2, we find a full compatibility with the following field assignments: the heights 2, 3 and 4 behave like (an unusual realization of) the logarithmic partner of a primary field with scaling dimension 2, the primary field itself being associated with the height 1 variable. Finite size corrections are also computed and successfully compared with numerical simulations. Relying on these field assignments, we formulate a conjecture for the scaling form of the lattice 2-point correlations of the height variables on the plane, which remain as yet unknown. The way conformal invariance is realized in this system points to a local field theory with c=-2 which is different from the triplet theory.Comment: 68 pages, 17 figures; v2: published version (minor corrections, one comment added

Prevalence of Bartonella henselae in blood donors and risk of blood transmission in Chile

Indexación: Scopus; Scielo.Bartonella henselae es el agente causal de la enfermedad del arañazo del gato en personas inmunocompetentes y de la angiomatosis bacilar y peliosis hepatis en inmunocomprometidos. En Chile la prevalencia de anticuerpos contra B. henselae en niños y adolescentes sanos es de 13,3%, en personas con riesgo ocupacional 60,5% y en gatos 85,6%. No existen datos publicados respecto de la seroprevalencia en donantes de sangre en nuestro país, por lo que determinar si B. henselae se encuentra presente en la sangre de los donantes al momento de la donación es muy importante, ya que este microorganismo puede sobrevivir hasta 35 días en los eritrocitos almacenados en banco de sangre a 4 °C. Objetivo: Determinar la prevalencia de B. henselae en donantes de sangre. Metodología: Se analizaron 140 muestras de sangre de donantes, para detectar la presencia de B. henselae, utilizando la técnica de la reacción de polimerasa en cadena (RPC). Resultados: Se obtuvo 13,6% de los donantes de sangre con RPC positiva para la B. henselae. La secuencia de los fragmentos amplificados presentó una identidad por sobre 98% con respecto a secuencias de B. henselae de referencia. Conclusión: El riesgo de transmisión sanguínea debiera ser considerado en un país con alta seroprevalencia de infección por B. henselae.Bartonella henselae is the causal agent of cat scratch disease in immunocompetent persons and bacterial angiomatosis in immunocompromised patients. In Chile, the prevalence of antibodies against B. henselae in healthy children and adolescents is 13.3%, in persons with occupational risk 60.5%, and in cats 85.6%. There are no published data regarding the seroprevalence in blood donors in our country, so determining if B. henselae is present in the blood of donors at the time of donation is very important, since this microorganism can survive up to 35 days in the red blood cells stored in a blood bank at 4 °C. Objective: To determine the prevalence of B. henselae in blood donors. Methodology: 140 donor blood samples were analyzed to detect the presence of B. henselae, using the polymerase chain reaction technique. Results: 13.6% of the blood donors with positive polymerase chain reaction for B. henselae were obtained. The sequence of the amplified fragments showed an identity of over 98% with respect to B. henselae reference sequences. Conclusion: The risk of blood transmission is due to a country with high B. henselae infection.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-10182017000600539&lng=en&nrm=iso&tlng=e

Prévalence des lombalgies et de leurs facteurs de risque professionnels chez les travailleurs de l'agriculture en France en 2010

Introduction La phase pilote du programme Coset-MSA a permis d’évaluer la prévalence des lombalgies et de leurs facteurs de risque professionnels chez les travailleurs de l’agriculture, et notamment les agriculteurs exploitants et les ouvriers agricoles. Méthodes Les travailleurs ont été recrutés, dans cinq départements, par tirage au sort dans les bases de données de la MSA et invités à remplir un auto-questionnaire portant sur les expositions et les lombalgies au cours des 12 derniers mois. L’échantillon d’analyse était constitué de 1130 travailleurs, âgés de 18 à 65 ans, exerçant dans le secteur agriculture, sylviculture et pêche, et en activité au moment de l’enquête. Résultats La prévalence des lombalgies au cours des 12 derniers mois était élevée, chez les hommes (65 %) comme chez les femmes (64 %). Chez ces dernières, la prévalence diminuait significativement avec l’âge (de 95 % chez les moins de 30 ans à 56 % chez les 50 ans et plus, p < 0,01). Des douleurs quotidiennes étaient rapportées par 10 % des hommes et 11 % des femmes, avec une prévalence qui augmentait avec l’âge, de façon significative chez les hommes (p < 0,001). La prévalence ne différait pas significativement selon la catégorie socioprofessionnelle (CSP). Cependant, soulignons la forte prévalence des lombalgies parmi les hommes artisans, commerçants et chefs d’entreprise (surtout des jardiniers, paysagistes…) malgré des effectifs faibles. Chez les femmes, les agricultrices exploitantes et les ouvrières agricoles étaient plus nombreuses à souffrir de lombalgies, quelle que soit la durée des symptômes. Le port de charges de plus de 25 kg plus de 2 heures par jour concernait 16 % des hommes et 5 % des femmes, se pencher en avant ou sur le côté plus de 4 heures par jour 15 % et 16 % respectivement et la conduite plus de 4 heures par jour 27 % et 10 %. Chez les hommes, les ouvriers non agricoles étaient les plus exposés aux trois facteurs (17 % au port de charges [p < 0,05], 22 % au fait de se pencher [p < 0,01], 32 % à la conduite [NS]). Chez les femmes, les ouvrières agricoles rapportaient les plus fortes expositions : 29 % se penchaient plus de 4 h/j (p < 0,001) et 16 % conduisaient plus de 4 h/j (NS). Conclusions La prévalence des lombalgies est particulièrement élevée dans l’agriculture, comparativement à des études portant sur tous secteurs d’activité (par exemple, l’étude Cosali menée auprès de salariés des Pays de la Loire). De plus, cette étude permet d’identifier les CSP les plus exposées aux facteurs de risque professionnels de lombalgie, qui devraient être ciblées prioritairement par les actions de prévention

Critical point network for drainage between rough surfaces

In this paper, we present a network method for computing two-phase flows between two rough surfaces with significant contact areas. Low-capillary number drainage is investigated here since one-phase flows have been previously investigated in other contributions. An invasion percolation algorithm is presented for modeling slow displacement of a wetting fluid by a non wetting one between two rough surfaces. Short-correlated Gaussian process is used to model random rough surfaces.The algorithm is based on a network description of the fracture aperture field. The network is constructed from the identification of critical points (saddles and maxima) of the aperture field. The invasion potential is determined from examining drainage process in a flat mini-channel. A direct comparison between numerical prediction and experimental visualizations on an identical geometry has been performed for one realization of an artificial fracture with a moderate fractional contact area of about 0.3. A good agreement is found between predictions and observations

Internal states of model isotropic granular packings. III. Elastic properties

In this third and final paper of a series, elastic properties of numerically simulated isotropic packings of spherical beads assembled by different procedures and subjected to a varying confining pressure P are investigated. In addition P, which determines the stiffness of contacts by Hertz's law, elastic moduli are chiefly sensitive to the coordination number, the possible values of which are not necessarily correlated with the density. Comparisons of numerical and experimental results for glass beads in the 10kPa-10MPa range reveal similar differences between dry samples compacted by vibrations and lubricated packings. The greater stiffness of the latter, in spite of their lower density, can hence be attributed to a larger coordination number. Voigt and Reuss bounds bracket bulk modulus B accurately, but simple estimation schemes fail for shear modulus G, especially in poorly coordinated configurations under low P. Tenuous, fragile networks respond differently to changes in load direction, as compared to load intensity. The shear modulus, in poorly coordinated packings, tends to vary proportionally to the degree of force indeterminacy per unit volume. The elastic range extends to small strain intervals, in agreement with experimental observations. The origins of nonelastic response are discussed. We conclude that elastic moduli provide access to mechanically important information about coordination numbers, which escape direct measurement techniques, and indicate further perspectives.Comment: Published in Physical Review E 25 page

Timing and chronicity of maternal depression symptoms and children's verbal abilities

ObjectiveTo test the associations between the timing and chronicity of maternal depression symptoms (MDS)and children’s long-term verbal abilities.Study designParticipants were 1073 mother-child pairs from a population-based birth cohort in Canada. MDSwere assessed at ages 5 months, 1.5, 3.5, and 5 years using the Center for Epidemiologic Studies DepressionScale. Verbal abilities were measured at 5, 6, and 10 years using the Peabody Picture Vocabulary Test-Revised(PPVT-R). Multiple linear regression models were used to estimate the association between timing (early: 5 monthsand/or 1.5 years vs late 3.5 and/or 5 years) and chronicity (5 months, 1.5, 3.5, and 5 years) of exposure to el-evated MDS and children’s mean PPVT-R scores.ResultsChildren exposed to chronic MDS had lower PPVT-R scores than children never exposed (mean differ-ence=9.04 [95% CI=2.28-15.80]), exposed early (10.08 [3.33-16.86]) and exposed late (8.69 [1.85-15.53]). Therewere no significant differences between scores of children in the early compared with the late exposure group. Weadjusted for mother-child interactions, family functioning, socioeconomic status, PPVT-R administration language,child’s birth order, and maternal IQ, psychopathology, education, native language, age at birth of child, and par-enting practices. Maternal IQ, (h2=0.028), native language (h2=0.009), and MDS (h2=0.007) were the main pre-dictors of children’s verbal abilities.ConclusionsExposure to chronic MDS in early childhood is associated with lower levels of verbal abilities inmiddle childhood. Further research is needed in larger community samples to test the association between MDSand children’s long-term language skills

Local ecological knowledge and multidisciplinary approach lead to discovery of hidden biodiversity in the deep ocean of Labrador, Canada

nternational commitments to preserve global biodiversity target the protection of 30% of marine habitats by 2030. The lack of even basic knowledge of many marine areas (e.g., deep oceans) combined with short timelines require integrative knowledge and multidisciplinary techniques to be used to efficiently identify areas worthy of protection. Here we outline a case study of the discovery of the Makkovik Hanging Gardens found in a deep-water trough in coastal Labrador, Canada. The area is of ecological significance because it supports high densities of vulnerable marine ecosystem indicator taxa, including the gorgonian coral Primnoa resedaeformis on portions of its vertical submarine walls. This study illustrates the exploratory process initiated by Nunatsiavut, which integrated local knowledge, scientific models, and a variety of technologies (such as remotely operated vehicles and multibeam sonar) to discover deep-water hidden biodiversity toward the advancement of both local Indigenous and global conservation goals

Associations between epigenetic aging and childhood peer victimization, depression, and suicidal ideation in adolescence and adulthood: A study of two population-based samples

Background: Prior studies indicate that peer victimization (including bullying) is associated with higher risk for depression and suicidal ideation across the life course. However, molecular mechanisms underlying these associations remain unclear. This two-cohort study proposes to test whether epigenetic aging and pace of aging, as well as a DNA methylation marker of responsive to glucocorticoids, are associated to childhood peer victimization and later depressive symptoms, or suicidal ideation. Methods: Cohort 1: Epigenome-wide DNA methylation (EPIC array) was measured in saliva collected when participants were 10.47 years (standard deviation = 0.35) in a subsample of the Quebec Longitudinal Study of Child Development (QLSCD, n = 149 participants), with self-reported peer victimization at 6-8 years, depressive symptoms (mean symptoms, and dichotomized top 30% symptoms) and suicidal ideation at 15-17 years. Cohort 2: Epigenome-wide DNA methylation (EPIC array) was measured in blood collected from participants aged 45.13 years (standard deviation = 0.37) in a subsample of the 1958 British Birth cohort (1958BBC, n = 238 participants) with information on mother-reported peer victimization at 7-11 years, self-reported depressive symptoms at 50 years, and suicidal ideation at 45 years. Five epigenetic indices were derived: three indicators of epigenetic aging [Horvath's pan-tissue (Horvath1), Horvath's Skin-and-Blood (Horvath2), Pediatric-Buccal-Epigenetic age (PedBE)], pace of aging (DunedinPACE), and stress response reactivity (Epistress). Results: Peer victimization was not associated with the epigenetic indices in either cohort. In the QLSCD, higher PedBE epigenetic aging and a slower pace of aging as measured by DunedinPACE predicted higher depressive symptoms scores. In contrast, neither the Horvath1, or Horvath2 epigenetic age estimates, nor the Epistress score were associated with depressive symptoms in either cohort, and none of the epigenetic indices predicted suicidal ideation. Conclusion: The findings are consistent with epigenome-wide and candidate gene studies suggesting that these epigenetic indices did not relate to peer victimization, challenging the hypothesis that cumulative epigenetic aging indices could translate vulnerability to depressive symptoms and suicidal ideation following peer victimization. Since some indices of epigenetic aging and pace of aging signaled higher risk for depressive symptoms, future studies should pursue this investigation to further evaluate the robustness and generalization of these preliminary findings

Simulating Powder Bed Based Additive Manufacturing Processes: From DEM Calibration to Experimental Validation

Powder flowability is a critical parameter for additive manufacturing techniques involving powders. In order to obtain thin and homogenous powder layers, a compromise between grain size and flowability has to be found. Unfortunately, when the grain size decreases, the cohesiveness increases and the flowability decreases. Too often, both the powder spreadability assessment and the optimization of printing parameters are costly empiric processes. In this paper, we describe an original method associating GranuDrum powder flow characterization instrument and DEM numerical simulations to asses the process-ability of powders and to optimize printing parameters like recoater speed, layer thickness or recoater geometry. The powder characterization allows to calibrate the simulation parameters and in particular to quantify the inter-grain cohesiveness. Then, the recoating process is simulated with the calibrated simulations to predict the behaviour of the powder inside the printer. In parallel, the results are validated by testing the powder in a printer equipped with an in-situ powder layer homogeneity tester based on image analysis