2,483 research outputs found
Measurements of electrical parameters of frog skin "in situ" as a function of environmental parameters
No full textElectrical parameters of the abdominal skin of the pithed frog (Rana esculenta) can be measured by means of a couple of double coaxial electrodes /1,2,3/. One of the double electrodes is inserted into the ventral lymphatic sac of the frog, between skin and muscles, and the second is placed in front of this, on the outer surface of the skin. The inner electrode of the coaxial pair measures the skin potential difference (pd), while the outer delivers a countercurrent, for modifying the pd. By this method, pd, short circuit current and skin DC resistance have been determined as a function of temperature (5 to 40 °C) and of pH (4 to 9) on the same living animal. The behaviour of the substrate bears both qualitative and quantitative similarities with the isolated skin in the lower temperature range, but no transport maximum exists around 27 °C /4/. The pH dependence of electrical parameters is also quite different than in the isolated substrate /5/. 1. G. Torelli, F. Celentano, G. Cortili, G. Guella: Boll. Soc. It. Biol. Sper. 44, 501 (1967); 2. F. Celentano, G. Cortili, G. Guella, G. Torelli: Boll. Soc. lt. Biol. Sper. 44, 504 (1967); 3. M. Bianchi, G. Torelli, F. Celentano, G. Cortili: Boll. Soc. It. Biol. Sper. 45, 385 (1968); 4. G.A. Poster: Biochim. Biophys. Acta 211, 487 (1970); 5. E. Schoffeniels: Arch. Int. Physiol. Biochim. 53, 513 (1955)
Rigidity of modular morphisms via Fujita decomposition
No full textWe prove that the Torelli, Prym and spin-Torelli morphisms, as well as covering maps between moduli stacks of smooth projective curves, cannot be deformed. The proofs use properties of the Fujita decomposition of the Hodge bundle of families of curves
Phenomenological description of selectivity in actively transporting membranes
No full textA phenomenological description of active and passive flows of solute and solvent across a biological membrane can be made explicitly considering the dependence of matter flows upon the rate of metabolic reactions /1/, or introducing a generalized chemical potential including a term accounting for active transport /2/, or making the hypothesis that solute flow can be splitten in two superimposed and thermodynamically couplet active and passive components. With the two latter approaches, by means of a transformation of flows and forces at constant temperature and in absence of electric field, two systems of three interacting flows, sustained by three different forces, can be obtained. The two systems lead to equivalent descriptions of volumetric flow and allow the determination of the reflection coefficient for solute passive transport /3/. The relationship between reflection coefficient and apparent reflection coefficient /4/ is also obtained. 1. A. Katchalsky, P. F. Curran. Nonequilbrium Thermodynamics in Biophysics, Cambridge Mass. (1965); 2. J. M. Diamond. J. Physiol. 161, 503 (1962); 3. F. Celentano, G. Monticelli, G. Torelli. Proc. Ist. Europ. Biophys. Congr. 3, 309 (1971); 4. C. J. Bentzel, M. Davies, W. N. Scott, M. Zatzman, A. K. Solomon. J. Gen. Physiol. 51, 517 (1968
R package 'ROSE': Random Over-Sampling Examples
No full textThe package provides functions to deal with binary classification problems in the presence of imbalanced classes. Synthetic balanced samples are generated according to ROSE (Menardi and Torelli, 2013). Functions that implement more traditional remedies to the class imbalance are also provided, as well as different metrics to evaluate a learner accuracy. These are estimated by holdout, bootstrap or cross-validation methods
An obstruction to the strong relative hyperbolicity of a group
No full textWe give a simple combinatorial criterion for a group that,
when satisfied, implies the group cannot be strongly relatively
hyperbolic. Our criterion applies to several classes of groups, such
as surface mapping class groups, Torelli groups, and automorphism
and outer automorphism groups of free groups
The cobordism group of homology cylinders
No full textGaroufalidis and Levine introduced the homology cobordism group of homology cylinders over a surface. This group can be regarded as an enlargement of the mapping class group. Using torsion invariants, we show that the abelianization of this group is infinitely generated provided that the first Betti number of the surface is positive. In particular, this shows that the group is not perfect. This answers questions of Garoufalidis and Levine, and Goda and Sakasai. Furthermore, we show that the abelianization of the group has infinite rank for the case that the surface has more than one boundary component. These results also hold for the homology cylinder analogue of the Torelli group
The TRANSMED Atlas: geological-geophysical fabric of the Mediterranean region - Final report of the Project
No full textTRANSMED PROJECT WORKING GROUPS: CARMINATI E., DOGLIONI C., ARGNANI A., CARRARA G., DABOVSKI C., DUMURDZHANOV N., GAETANI M., GEORGIEV G., MAUFFRET M., SARTORI R,; SCIONTI V., SCROCCA D., SRANNE M., TORELLI L., ZAGORCHEV I
Totally geodesic subvarieties in the moduli space of curves
No full textIn this paper, we study totally geodesic subvarieties Y Ag of the moduli space of principally polarized abelian varieties with respect to the Siegel metric, for g ≥ 4. We prove that if Y is generically contained in the Torelli locus, then dim Y ≤ (7g - 2)/3
Homological infiniteness of Torelli groups
No full textAbstractThe rational homology of the Torelli group of genus g relative to n distinguished points and r fixed embedded disks is proved to be infinite dimensional if g is sufficiently large relative to n+r. In particular, the rational homology of the (classical) Torelli group of genus g is infinite dimensional when g⩾7. In addition, the rational homology of the subgroup of the Torelli group of genus g generated by all the Dehn twists along separating simple closed curves is proved to be infinite dimensional when g⩾2
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The cohomology of Torelli groups is algebraic
No full textThe Torelli group of is the subgroup of the diffeomorphisms of fixing a disc which act trivially on . The rational cohomology groups of the Torelli group are representations of an arithmetic subgroup of or . In this paper we prove that for and , they are in fact algebraic representations. Combined with previous work, this determines the rational cohomology of the Torelli group in a stable range. We further prove that the classifying space of the Torelli group is nilpotent
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