High power GaN‐HEMT SPDT switches for microwave applications

In this article, the design, fabrication, and on‐wafer test of X‐Band and 2–18 GHz wideband high‐power SPDT MMIC switches in AlGaN/GaN technology are presented. The switches have demonstrated state‐of‐the‐art performance and RF fabrication yield better than 65%. Linear and power measurements for different control voltages have been reported and an explanation of the dependence of the power performances on the control voltage is given. In particular, the X‐band switch exhibits a 0.4 dB compression level at 10 GHz when driven by a 38 dBm input signal. The wideband switch shows a compression level of 1 dB at an input drive higher than 38 dBm across the entire bandwidth. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Rules and Strategies for Contextual Specialization of Constraint Logic Programs

We address the problem of specializing a constraint logic program w.r.t. a constrained atom which specifies the context of use of the program. We follow an approach based on transformation rules and strategies. We introduce a novel transformation rule, called contextual constraint replacement, to be combined with variants of the traditional unfolding and folding rules. We present a general Partial Evaluation Strategy for automating the application of these rules, and two additional strategies: the Context Propagation Strategy which is instrumental for the application of our contextual constraint replacement rule, and the Invariant Promotion Strategy for taking advantage of invariance properties of the computation. We show through some examples the power of our method and we compare it with existing methods for partial deduction of constraint logic programs based on extensions of Lloyd and Shepherdson's approach.     

Rocket seedling production on the international space station: Growth and nutritional properties

Producing sprouts directly during space missions may represent an interesting opportunity to offer high-quality fresh ready to eat food to the astronauts. The goal of this work was to compare, in terms of growth and nutritional quality, rocket (Eruca sativa Mill.) seedlings grown in the International Space Station during the ENEIDE mission with those grown in a ground-based experiment (in presence and absence of clinorotation). The rocket seedlings obtained from the space-experiment were thinner and more elongated than those obtained in the ground-based experiment. Cotyledons were often closed in the seedlings grown in the space experiment. Quantitative (germination, fresh and dry weight) and qualitative (glucose, fructose, sucrose and starch) traits of rocket seedling were negatively affected by micrograv-ity, especially those recorded on seedlings grown under real microgravity conditions The total chlorophyll, and carotenoids of seedlings obtained in the space experiment were strongly reduced in comparison to those obtained in the ground-based experiment (presence and absence of clinorotation). The results showed that it is possible to produce rocket seedlings in the ISS; however, further studies are needed to define the optimal environmental conditions for producing rocket seedlings with high nutritional value     

ATM layouts with bounded hop count and congestion

Summary. In this paper we introduce and analyze two new cost measures related to the communication overhead and the space requirements associated with virtual path layouts in ATM networks, that is the edge congestion and the node congestion. Informally, the edge congestion of a given edge e at an incident node u is defined as the number of VPs terminating at or starting from u and using e, while the node congestion of a node v is defined as the number of VPs having v as an endpoint. We investigate the problem of constructing virtual path layouts allowing to connect a specified root node to all the others in at most h hops and with maximum edge or node congestion c, for two given integers h and c. We first give tight results concerning the time complexity of the construction of such layouts for both the two congestion measures, that is we exactly determine all the tractable and intractable cases. Then, we provide some combinatorial bounds for arbitrary networks, together with optimal layouts for specific topologies such as chains, rings and grids. Received: December 1997 / Accepted: August 2000     

Reliability of RF MEMS switches due to charging effects and their circuital modelling

The reliability of RF MEMS switches is typically reduced by charging effects occurring in the dielectrics. The aim of this paper is to discuss these effects, and to propose analytical and equivalent circuit models which account for most of the physical contributions present in the structure.     

An optimal algorithm for decomposing a window into maximal quadtree blocks

Decomposing a two-dimensional window (i.e., the region specified by the cross product of two closed intervals over a given two-dimensional space) into its maximal quadtree blocks means to find the set of black quadrants that would be obtained by representing the region covered by the window using a quadtree. In this paper we propose an optimal O(n) time algorithm for decomposing a square window of size embedded in an image space of pixel elements, thus improving the O(n log log T) time algorithm of Aref and Samet [2]. As a direct consequence of this new faster algorithm, classical window operations on main memory quadtree based data structures can be solved more efficiently. In particular, we show that the exist and report queries on the incomplete pyramid [1] and on the up-down pyramid [8] can be solved in O(n) time, which is optimal. Received: 1 September 1997 / 28 October 1998     

Defined Conjugation of Glycans to the Lysines of CRM197 Guided by their Reactivity Mapping

Systematic characterisation of the reactivity of the lysine moieties in CRM₁₉₇ towards N‐hydroxysuccinimide linkers bearing alkynes or azides is described. This involves two‐step conjugation of various glycans to CRM₁₉₇ by click chemistry in a well‐defined manner. By semiquantitative LC‐MS/MS analysis of proteolytic digests of the conjugates formed, the reactivity of lysine residues in the protein was mapped and ranked. Computational analysis of the solvent accessibility of each lysine residue (based on the CRM₁₉₇ crystal structure) established a correlation between reactivity and surface exposure. By this approach, conjugation involving lysine residues (normally a random process) can be controlled. It enables the preparation of lysine‐mediated glycoconjugates with improved batch‐to‐batch reproducibility, thereby producing neo‐glycoconjugates with more‐consistent biological activity.     

Videolaparoscopic cholecystectomy. Experience, evolution, and comparison of techniques

The paper broadly outlines the technique of laparoscopic cholecystectomy used by the authors to treat patients suffering from calculosis of the gallbladder. Basing their comments on the French school, the authors review the literature to identify those innovations introduced by individual operators in elation to the original technique which have enabled this method to be extended to those cases complicated by acute cholecystitis, VBP calculosis or sequelae from abdominal surgery. The most important innovations include the use of a laparoscope with oblique 30-degrees vision, which is extremely useful during the dissection of Calot's triangle since it allows VBP to be identified with greater ease and precision, above all in the event of phlogistic sequelae enclosing the peduncle. In addition, laparoscopic suture or ligation using Roeder's running-knot, used by the Dundee school to treat the cystic duct and artery, presents considerable advantages compared to the conventional use of metal clips. The authors also emphasise the growing return to intraoperative cholangiography which is routinely performed by some authors and is of value in identifying anatomic anomalies, iatrogenic lesions and VBP calculi unnoticed by preoperative tests. A second innovation which is highlighted consists of the treatment of choledocholithiasis during the course of laparoscopic cholecystectomy, in addition to pre- and postoperative endoscopic papillo-sphincterotomy.