SICILIAN NATURALISTIC NEWS: 22 Dilophus bispinosus; 23 Leptometopa latipes; 24 Syntormon mikii; 25 Morophaga morella.

Diptera Bibionidae, Diptera Milichiidae, Diptera Dolichopodidae, Lepidoptera Tineida

Una nuova popolazione isolata di xenopo liscio in Sicilia sud-occidentale

African clawed frog is a sub-saharan native anuran that has been introduced in various states of the old and the new world. The only Italian population of this species is located in western Sicily, and it is known as the European clawed frog population with wider distribution area. This paper describes a new Sicilian population of this species, and sets out to verify the effective isolation from the currently known distribution. The new site is a disused swimming pool, located near the mouth of the Belice River (province of Trapani), 31 km away from the nearest edge of the African clawed frog distribution area. To test whether this new population is the result of natural expansion of its range have been checked 21 control sites, arranged in a suitable area near the new site and along the basin of the Belice River, whose upper course is included in the Sicilian range of this species. The surveys in the control sites did not reveal the presence of clawed frogs, therefore, it seems doubtful the hypothesis of natural expansion along the Belice River basin and plausible the occurrence of a man-mediated introduction event

Clathrin mediates both internalization and vesicular release of triggered T cell receptor at the immunological synapse

Ligation of T cell receptor (TCR) to peptide-MHC (pMHC) complexes initiates signaling leading to T cell activation and TCR ubiquitination. Ubiquitinated TCR is then either internalized by the T cell or released toward the antigen-presenting cell (APC) in extracellular vesicles. How these distinct fates are orchestrated is unknown. Here, we show that clathrin is first recruited to TCR microclusters by HRS and STAM2 to initiate release of TCR in extracellular vesicles through clathrin- and ESCRT-mediated ectocytosis directly from the plasma membrane. Subsequently, EPN1 recruits clathrin to remaining TCR microclusters to enable trans-endocytosis of pMHC-TCR conjugates from the APC. With these results, we demonstrate how clathrin governs bidirectional membrane exchange at the immunological synapse through two topologically opposite processes coordinated by the sequential recruitment of ecto- and endocytic adaptors. This provides a scaffold for direct two-way communication between T cells and APCs

Ion Cyclotron Waves in Field-aligned Solar Wind Turbulence

The nature of the solar wind parallel fluctuations is investigated in this Letter by using magnetic helicity to characterize their polarization state at proton scales. Our aim is to assess the role of the proton cyclotron instability as a mechanism for generating ion cyclotron waves (ICWs) in solar wind turbulence. The wave polarization is found to depend strongly on the proton temperature anisotropy and on the power level of magnetic fluctuations at fluid scales. The results indicate a clear link between fluid and kinetic scales in the solar wind turbulence, allowing for a picture in which the resonant dissipation of high-frequency Alfvn waves heats protons in a direction perpendicular to the magnetic field, increasing their temperature anisotropy. The velocity distribution thus becomes unstable to the proton cyclotron instability, which then drives the local generation of ICWs in the solar wind

Membrane nanoclusters of FcγRI segregate from inhibitory SIRPα upon activation of human macrophages

Signal integration between activating Fc receptors and inhibitory signal regulatory protein α (SIRPα) controls macrophage phagocytosis. Here, using dual-color direct stochastic optical reconstruction microscopy, we report that Fcγ receptor I (FcγRI), FcγRII, and SIRPα are not homogeneously distributed at macrophage surfaces but are organized in discrete nanoclusters, with a mean radius of 71 ± 11 nm, 60 ± 6 nm, and 48 ± 3 nm, respectively. Nanoclusters of FcγRI, but not FcγRII, are constitutively associated with nanoclusters of SIRPα, within 62 ± 5 nm, mediated by the actin cytoskeleton. Upon Fc receptor activation, Src-family kinase signaling leads to segregation of FcγRI and SIRPα nanoclusters to be 197 ± 3 nm apart. Co-ligation of SIRPα with CD47 abrogates nanocluster segregation. If the balance of signals favors activation, FcγRI nanoclusters reorganize into periodically spaced concentric rings. Thus, a nanometer- and micron-scale reorganization of activating and inhibitory receptors occurs at the surface of human macrophages concurrent with signal integration

A self-adaptive strategy for uniformly accurate tracing of the equilibrium paths of elastic reticulated structures

The paper describes an incremental procedure for tracing with uniform accuracy the equilibrium paths of elastic reticulated structures subject to conservative proportional loads. Like most traditional are-length methods, the length of the secant vector is chosen as the increment of the representation parameter, but in contrast to them, here, in order to obtain finer sampling along arcs of greater curvature, its initial assigned value is susceptible to stepwise reduction along the path. This is accomplished by requiring the secant vector at each step to lie inside a prescribed 'cone of admissible directions'. As a consequence, where the path is almost rectilinear, the description of curves remains identical to that furnished by conventional procedures, while for increasing curvature the tracing becomes more and more detailed. This strategy proves to be very effective in dealing with reticulated systems whose equilibrium paths are characterized by sharp turns and/or winding loops. Likewise, when dealing with 'perfect' systems, the method provides simpler, more efficient and unambiguous tracing of both the primary and secondary branches in the neighbourhood of bifurcation points

Large displacement analysis of elastic pyramidal trusses

The paper examines the equilibrium stability problem for a simple class of elastic space trusses in the shape of a regular pyramid. Joints located at the vertices of the base polygon are fixed while the joint at the apex is subjected to a proportionally increasing load acting in either the vertical direction, in the horizontal plane, or along a generic oblique direction. Exact closed-form solutions are derived for each load condition under the common hypotheses of linear material law, small or moderate axial deformation in bars and large nodal displacements. Despite their seeming simplicity, these mechanical systems exhibit a wide variety of post-critical responses, not exhausted by the classical snapping and bifurcation phenomena. In addition to regular primary and secondary branches, the equilibrium paths may include neutral branches, namely branches entirely composed of bifurcation or limit points. Besides their immediate theoretical interest, these branches are particularly difficult to handle by the standard numerical procedures of non-linear analysis, so the given solutions may represent severe benchmark tests

Tracing the equilibrium paths of elastic reticulated systems by means of the 'admissible directions cone' method

Standard arc-length methods, which use a constant step-length, may encounter serious difficulties when tracing the equilibrium paths of ‘perfect’ or ‘quasi-perfect’ structural systems. In these cases, in the neighbourhood of bifurcation or sharp turning points, erroneous jumps of the algorithm onto different branches are always possible. These drawbacks can be efficiently overcome by using a self-adapting strategy able to reduce the assigned step-length according to the complexity of the curve. In particular, based on the concept of osculating circle, an inequality constraint is introduced, which forces the secant vector to fall within a prescribed ‘cone of admissible directions’ at each incremental step. The main advantage of this strategy is that it naturally leads to a uniformly accurate sampling of points along the path. The method’s effectiveness is moreover illustrated through its application to the stability analysis of complex reticulated systems, such as Schwedler domes and three-dimensional masts. In particular, the influence of different bracing patterns on their post-critical behaviour is examined

Desertificazione:criteri e metodi di valutazione e riduzione del rischio

Dottorato di Ricerca in Scienze della terra, XVII Ciclo,a.a. 2005-2006Università della calabri

A technical note on an experimental device to measure friction coefficient in sheet metal forming

In the paper the authors present the results of several experimental tests aimed to determine the Coulomb friction coefficient in sheet metal forming operations at the varying of the sheet metal material and for different operative conditions. In particular a few pressure and lubricating conditions have been investigated. In order to develop such experiments a dedicated fixture was designed and set-up starting from the one proposed by Wilson