Experimental Characterization of Actuators for Micro Air Vehicles

Mini-UAVs and RC slow flyers require compact, lightweight and responsive actuators. Shape memory alloy wires can be used to design ultra-light micro-servos. This technology relies on the reversible change in crystalline structure that a SMA wire undergoes when electricity runs through it. The resulting contraction is used to deflect the aircraft control surfaces. This paper introduces SMA wires technology and its application to the design of a small-size and light-weight actuator for elevon type controls. A conventional servo is taken as a reference to compare static and dynamic performance of the realized wire configuration prototype. A wind tunnel experiment is set up to test the behavior at different airspeeds and the servos response to variable frequency input is recorded. Extensive data analysis is performed to estimate the system models and to predict their bandwidth. In particular, Prediction-Error Minimization method is applied and Akaike's Final Prediction-Error is used to evaluate the model fitt..

2SLS with principal components: estimation of a nonlinear model of the Italian economy

The estimation method of Two Stage Least Squares (2SLS) with Principal Components (2SPC) is applied to a medium-sized nonlinear econometric model of the Italian Economy.Two stage least squares, 2SLS, principal components, econometric model, Italian economy

Updating the model and new simulations for 1974

A well known macroeconometric model of the Italian economy is updated to produce forecasts at 1974.Italian economy; macroeconometric model; simulation; forecast

Crystallographic studies on complexes between retinoids and plasma retinol-binding protein.

The three-dimensional structures of complexes between bovine plasma retinol-binding protein (RBP) and three retinol analogs with different end groups (fenretinide, all-trans retinoic acid, and axerophthene) have been determined to 1.8-1.9-A resolution. Their models are very similar to that of the bovine retinol.RBP complex: the root mean square deviations between equivalent alpha-carbons in the two proteins range from 0.17 to 0.24 A. The retinoid molecules fit in the beta-barrel cavity assuming the same conformation of the vitamin, and the substitutions have no consequences on the overall protein structure. While confirming that an intact hydroxyl end group is not an absolute requirement for a correct retinoid binding to RBP, this study has shown the occurrence of conformational changes, although limited, in the rather flexible loop region at the entrance of the beta-barrel upon fenretinide and retinoic acid binding. These changes are suitable for accommodating the end groups of the above retinoids. Instead, no such changes have been revealed in RBP complexed with axerophthene, a retinol analog bearing a hydrogen atom in place of the hydroxyl end group. The protein conformational changes in the above loop region, the steric hindrance of bulky end groups of bound retinoids, and the lack of the retinol hydroxyl group appear to be responsible for the possible reduced affinity of retinoids for RBP relative to retinol and, at the same time, for the abolished or reduced affinity of retinoid.RBP complexes for transthyretin relative to retinol-RBP

Stime 2SLS con componenti principali di un modello non lineare dell' economia italiana

The estimation method of Two Stage Least Squares (2SLS) with Principal Components (2SPC) is applied to a medium-sized nonlinear econometric model of the Italian Economy

Herpes simplex virus type 2 infection increases human immunodeficiency virus type 1 entry into human primary macrophages

Epidemiological and clinical data indicate that genital ulcer disease (GUD) pathogens are associated with an increased risk of human immunodeficiency virus type 1 (HIV-1) acquisition and/or transmission. Among them, genital herpes simplex virus type 2 (HSV-2) seems to play a relevant role. Indeed, the ability of HSV-2 to induce massive infiltration at the genital level of cells which are potential targets for HIV-1 infection may represent one of the mechanisms involved in this process. Here we show that infection of human primary macrophages (MDMs) by HSV-2 results in an increase of CCR5 expression levels on cell surface and allows higher efficiency of MDMs to support entry of R5 HIV-1 strains. This finding could strengthen, at the molecular level, the evidence linking HSV-2 infection to an increased susceptibility to HIV-1 acquisition

Prospective randomised pilot study of management of the pancreatic stump following distal resection

Background Numerous surgical techniques have been described in the literature for pancreatic stump management following left resection, but there is only one prospective, randomised study. A prospective randomised pilot study was designed to assess five different pancreatic stump management techniques after distal resection in an attempt to identify which was the most effective in terms of complications and ease of execution. Methods Sixty-nine consecutive patients were randomly assigned to five different treatment groups: manual suturing, suturing plus fibrin glue, suturing plus polypropylene mesh, pancreaticojejunostomy and suturing with a stapler. All presented a soft residual pancreas. Results The overall incidence of pancreatic fistula was 19%, ranging from 7% to 33% in the different treatment groups. None of the techniques Significantly reduced the incidence of postoperative complications. Discussion On weighing the complications observed against ease and speed of execution, the construction of a pancreaticojejunostomy and closure of the stump with a mechanical stapler may be regarded as the procedures to be tested in future

Unlocking Access to Enantiopure Fused Uracils by Chemodivergent [4+2] Cross‐Cycloadditions: DFT‐Supported Homo‐Synergistic Organocatalytic Approach

The discovery of chemical methods enabling the construction of carbocycle‐fused uracils which embody a three‐dimensional and functional‐group‐rich architecture is a useful tool in medicinal chemistry oriented synthesis. In this work, an unprecedented amine‐catalyzed [4+2] cross‐cycloaddition is documented; it involves remotely enolizable 6‐methyluracil‐5‐carbaldehydes and β‐aryl enals, and chemoselectively produces two novel bicyclic and tricyclic fused uracil chemotypes in good yields with a maximum level of enantiocontrol. In‐depth mechanistic investigations and control experiments support an intriguing homo‐synergistic organocatalytic approach, where the same amine organocatalyst concomitantly engages both aldehyde partners in a stepwise eliminative [4+2] cycloaddition, whose vinylogous iminium ion intermediate product may diverge—depending upon conditions—to either bicyclic targets by hydrolysis or tricyclic products by a second homo‐synergistic trienamine‐mediated stepwise [4+2] cycloaddition

Aggiornamento del modello al 1974 e nuove simulazioni

A well known macroeconometric model of the Italian economy is updated to produce forecasts at 1974