A Cross-Layer Multi-Hop Simulator for IEEE 802.11e

In this work we simulate the ad hoc mode of IEEE 802.11e for routing optimisation. We simulate the behaviour of routing algorithms at the network layer by using a custom-made cross-layer network simulator developed by our team, which simultaneously considers the physical and Medium Access Control (MAC) layers. Although the simulator also supports the infrastructure mode, in this paper we focus on the ad hoc feature which was introduced by the authors. We opted for the simulator approach over the theoretical analysis, but we also present a mathematical model for IEEE 802.11 ad hoc networks. Some initial tests were performed by using a simple routing algorithm (to evaluate the behaviour of the system in terms of selection of the path between a source and a destination, and the correctness of the calculated metrics, which include end-to-end delay, packets lost, packets delivered), but more advanced cross-layer design solutions were also tested. When information from the physical and MAC layers is used as an input to the routing algorithm, improvements are achieved in the performance of the network. Several functions were compared and the algorithm that privileges shorter links accounting with the metric “collision rate” achieves the best results. When compared with a standard routing solution, this cross-layer approach allows to increase the number of packets delivered, while not significantly affecting the end-to-end delay of the packets.     

Fiber optic hot-wire flowmeter based on a metallic coated hybrid long period grating/fiber Bragg grating structure

In this work an all-optical hot-wire flowmeter based on a silver coated fiber combining a long period grating and a fiber Bragg grating (FBG) structure is proposed. Light from a pump laser at 1480 nm propagating down the fiber is coupled by the long period grating into the fiber cladding and is absorbed by the silver coating deposited on the fiber surface over the Bragg grating structure. This absorption acts like a hot wire raising the fiber temperature locally, which is effectively detected by the FBG resonance shift. The temperature increase depends on the flow speed of the surrounding air, which has the effect of cooling the fiber. It is demonstrated that the Bragg wavelength shift can be related to the flow speed. A flow speed resolution of 0.08 m/s is achieved using this new configuration.     

Counterfactual and Semifactual Conditionals Prime Alternative Possibilities.

The authors examined in 3 experiments the comprehension of counterfactuals, such as "If it had rained, the plants would have bloomed," and semifactuals, such as "Even if it had rained, the plants would have bloomed," compared with indicative conditionals, "If it rained, the plants bloomed." The first experiment showed that people read the negative conjunction, "not p and not q" faster when it was primed by a counterfactual than when it was primed by an indicative conditional. They read the affirmative conjunction, "p and q" equally quickly when it was primed by either conditional. The 2nd experiment showed that people read the negated-antecedent conjunction, "not p and q" faster when it was primed by a semifactual conditional. The 3rd experiment corroborated these results in a direct comparison of counterfactuals and semifactuals. The authors discuss the implications of the results for the mental representations of different conditionals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A semi-automatic system for the analysis of ecocardiographic tracings (author's transl)]

A semi-automatic system is described for analysis of echocardiographic traces of the left ventricle. Filtering interpolating and averaging processes are discussed and the overall accuracy evaluated. The program is able to calculate ventricular indexes (strake volume, ejection fraction, circumferential velocity of fiber shortening), continuous functions (istantaneous ventricular diameter and volume, wall thickness, velocity of cavity compression and dilation) and, correlating the echo data with pressure values, circumferential stresss and ventricular compliance. Pressure is obtained along the ejection phase only from the carotidal pulse calibrated by means of the brachial pressure values. Advantages and limits of the method are discussed.     

Subxiophoyd echocardiography: pulmonary artery or aorta (author's transl)

Six patients with chronic obstructive pulmonary diseases, have been examinated by subxiophoyd echocardiography associated with ultrasonic contrast of right heart. It is detected that the vessel placed behind anterior cavity is aorta. This is confirmed by study of calcific aortic stenosis too, where the calcifications allows sure localisation of the vessel. Main pulmonary artery, or its branches, is instead visible behind aorta.     

Discrete superconducting vortex flow transistors

We have fabricated an overdamped superconducting discrete vortex flow transistor (DVFT) which consists of an array of Josephson junctions coupled together in parallel. Measurements on this DVFT indicate a current gain of 1.2 when the control current is injected parallel to the array of junctions. We have developed a model that successfully predicts the performance of our low-T_c DVFT, including its current gain. When the current is injected parallel to the array, the gain is linear in the number of junctions and can be made much greater than 1. Except for the output voltage, the results of the DVFT are comparable to those of the present high-T_c devices     

Current distribution in superconducting thin-film strips

A closed-form expression is presented for the current distribution in an isolated strip made from a superconducting thin film with thickness less than a few penetration depths. This equation gives a good approximation within certain limits for the resistance and inductance per unit length of superconducting striplines and microstrip lines. Both the ac resistance of an isolated superconducting strip and the resistance per unit length of a superconducting stripline calculated using this closed-form expression agree well with the numerical results generated by the modified Weeks' method. The possibility of using this expression along with the integral equation method to develop an efficient full-wave method for analyzing superconducting planar transmission lines is discussed     

Urokinase protocol for free-flap salvage following prolonged venous thrombosis

The incidence of free-flap failure is reported at 4 to 5 percent. Often, these failures are attributed to postoperative venous thrombosis with salvage rates reported at 42 percent. The use of thrombolytics has been effective in laboratory protocols; however, there have been only case reports to substantiate their use in humans. In this study, we establish a protocol for the administration of urokinase for postoperative venous thrombosis. Upon clinical evidence of venous thrombosis, all patients were urgently returned to the operating room, where the venous anastomosis was resected and a new venous anastomosis was performed. A solution of 250,000 units of urokinase was then infused over 30 minutes through a 25-gauge butterfly inserted into the recipient artery just proximal to the arterial anastomosis. Patients were continued on a daily aspirin (325 mg). More than 600 free flaps have been performed by our group since 1990. In that group of patients, five were diagnosed with postoperative venous thrombosis. Flaps consisted of four radial forearm flaps and one free transverse rectus abdominis muscle flap. All patients were diagnosed late based upon significant changes within the flap. Thromboses were clinically apparent on postoperative days 1 through 6, with an average of 3.6 days. All five patients received urokinase as described. The average age of the patients treated was 43. There were no postoperative hematomas, blood transfusions, or bleeding complications. There were no allergic or anaphylactic reactions to the urokinase. All flaps survived (100 percent) with a mean follow-up of 27 months. The use of urokinase as described in our protocol has been an effective thrombolytic, capable of reversing clinically advanced venous thrombosis when combined with repeated venous anastomosis. We believe this protocol provides a viable option for the treatment of postoperative venous thrombosis.