Bringing Scheme programming to the iPhone—Experience

The iPhone SDK provides a powerful platform for the development of applications that make use of iPhone capabilities, such as sensors, GPS, Wi‐Fi, or Bluetooth connectivity. We observe that so far the development of iPhone applications has mostly been restricted to using Objective‐C. However, developing applications in plain Objective‐C on the iPhone OS suffers from limitations, such as the need for explicit memory management and lack of syntactic extension mechanism. Moreover, when developing distributed applications in Objective‐C, programmers have to manually deal with distribution concerns, such as service discovery, remote communication, and failure handling. In this paper, we discuss our experience in porting the Scheme programming language to the iPhone OS and how it can be used together with Objective‐C to develop iPhone applications. To support the interaction between Scheme programs and the underlying iPhone APIs, we have implemented a language symbiosis layer that enables programmers to access the iPhone SDK libraries from Scheme. In addition, we have designed high‐level distribution constructs to ease the development of distributed iPhone applications in an event‐driven style. We validate and discuss these constructs with a series of examples, including an iPod controller, a maps application, and a distributed multiplayer Scrabble‐like game. We discuss the lessons learned from this experience for other programming language ports to mobile platforms. Copyright © 2011 John Wiley & Sons, Ltd.     

Predictor-based stabilization of discrete time-varying input-delay systems

This paper adapts some literature results on stabilizing discrete time-varying input delay systems to the case of having a predictor-based controller. The objective of the paper is showing that the incorporation of predictors to the referred results is relatively simple and, by means of such predictors, robustness against delay mismatch in the input channel may be improved. In this way, larger delay variation margins are proved with predictors when compared to standard memoryless state feedback, as intuitively expected, due to the extra past information available.     

Oxidation State of Titanium in CaO‐SiO2‐TiOx Slags at 1873K

Oxidation state of titanium was determined in CaO‐SiO₂‐TiO_x slags in the composition range 25‐53 percent CaO, 27‐46 percent SiO₂, 10‐55 percent TiO_x at 1873K using gas equilibration method. In the experiments, slags with different titanium oxide contents were equilibrated with a known carbon monoxide and carbon dioxide ratio. The results were used to determine the Ti³⁺ and Ti⁴⁺ contents as well as the activity coefficient ratio of corresponding oxides in the slag. The dependence of the activity coefficient ratio as a function of oxygen partial pressure was determined.     

An efficient algorithm for gossiping in the multicasting communication environment

We present an algorithm for the gossiping problem defined over an n processor communication network, N, where message multicasting is allowed. The algorithm generates a communication schedule with a total communication time at most N+r, where r is the radius of the network. Our algorithm begins by constructing a spanning tree (or tree network T) with the least possible radius. Then, all the communications are carried out in the tree network as follows: each processor waits its turn to transmit "almost" consecutively to its parent and children all the messages in its subtree. During other times, each processor transmits to its children all the messages emanating elsewhere in the network.     

Successful Management of Valproate Overdose by a Combination of Extracorporeal Therapies

Valproic acid toxicity is not infrequent and is difficult to treat, as there is no specific antidote. In the past, this drug was considered unremovable by extracorporeal methods because of the highly protein bound state (90–95%). However, recent reports suggest that the toxicokinetics of valproate vary considerably from the pharmacokinetics at therapeutic levels, and at higher concentrations protein‐binding sites become saturated. The drug's relatively low molecular weight (144 Da), small volume of distribution (0.13–0.23 L/kg), and saturable protein binding render it potentially amenable to extracorporeal removal, but published experience is scant and there are only a few reported instances in which patients were successfully treated with extracorporeal methods. Here we report the case of a patient with serious valproate toxicity treated with simultaneous “in series” hemodialysis and hemoperfusion followed by continuous veno‐venous hemodiafiltration. A 35‐year‐old homeless male presented to the emergency department after ingesting 120 pills of valproic acid. Initial valproic acid level was 59 µg/mL. Urine drug screen was negative and serum chemistries including LFTs were normal. He was treated with activated charcoal and admitted to the intensive care unit. 4 h later, he developed respiratory failure and became hemodynamically unstable. He was intubated and successfully resuscitated. Subsequently, the valproic acid level was found to be 553 µg/mL and a decision was made to employ extracorporeal methods for drug removal. “In series” hemodialysis and hemoperfusion were done for 4 h and simultaneous blood samples for measurement of valproic acid levels were obtained as blood entered the hemoperfusion column (arterial) and as it exited the hemodialysis membrane (venous). Extraction ratio, whole blood, and plasma clearances were calculated and they compared substantially with the published data. The above measures decreased valproate levels from 572.6 (pre‐dialysis level) to 203.2 µg/mL. This was followed by continuous veno‐venous hemodiafiltration for 18 h, which sustained the drug removal and prevented significant post‐dialytic rebound. This is the first reported instance in which these three methods were administered together successfully in the management of valproic acid toxicity.     

Synthetic Modular Antibody Construction by Using the SpyTag/SpyCatcher Protein-Ligase System

Efforts to engineer recombinant antibodies for specific diagnostic and therapy applications are time consuming and expensive, as each new recombinant antibody needs to be optimized for expression, stability, bio-distribution, and pharmacokinetics. We have developed a new way to construct recombinant antibody-like “devices” by using a bottom-up approach to build them from well-behaved discrete recombinant antibody domains or “parts”. Studies on antibody structure and function have identified antibody constant and variable domains with specific functions that can be expressed in isolation. We used the SpyTag/SpyCatcher protein ligase to join these parts together, thereby creating devices with desired properties based on summed properties of parts and in configurations that cannot be obtained by using genetic engineering. This strategy will create optimized recombinant antibody devices at reduced costs and with shortened development times.     

Morphological contrast index based on the Weber's law

In this article, a morphological contrast index based on the Weber's law is proposed to quantify the contrast in a processed image. This measure involves the contours of the image along with its background. The proposal made here is applied to detect the image with higher contrast, and also identify the enhanced image most similar to the original. Moreover, the contrast index is compared with other four indexes reported in the current literature. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 137–144, 2012     

Corrosion in alkanolamine used for acid gas removal: From natural gas processing to CO2 capture

The aim of this paper is to review some of the parameters influencing the corrosivity of alkanolamine solvents used for natural gas purification or for CO₂ capture. In the light of literature data and of new experimental results, the influences of temperature and of acid gas loading are discussed. These two parameters appear to have a strong impact on corrosion rates of carbon steel, with extrapolated corrosion rates of several tens of mm/year for the highest temperature and acid gas loading condition. It is then proposed to discuss about similarities and differences between natural gas processing and CO₂ capture from flue gas. For both applications, alkanolamine processes are used. Still, differences can be found in operating parameters. The most significant gap concerns the lean amine sections. In acid gas treatment, the regeneration of the solvent is often performed down to zero loading. Under these conditions, an extremely low corrosivity of the lean solvent is expected. On the contrary, CO₂ capture from flue gas requires only a partial stripping of the CO₂ in the regeneration section, due to energy efficiency reasons. Then, the lean solvent still contains some acid gas, and subsequently a higher corrosivity. Finally, the general principles for material selection for the different parts of acid gas removal units are discussed, considering both cases of natural gas processing or CO₂ capture.     

S-Ribosylhomocysteine analogues modified at the ribosyl C-4 position

4-C-Alkyl/aryl-S-ribosylhomocysteine (SRH) analogues were prepared by coupling of homocysteine with 4-substituted ribofuranose derivatives. The diastereoselective incorporation of the methyl substituent into the 4 position of the ribose ring was accomplished by the addition of methylmagnesium bromide to the protected ribitol-4-ulose yielding the 4-C-methylribitol in 85% yield as single 4R diastereomer. The 4-C hexyl, octyl, vinyl, and aryl ribitols were prepared analogously. Chelation controlled addition of a carbanion to ketones from the Si-face was responsible for the observed stereochemical outcome. Oxidation of the primary alcohol of the 4-C ribitols with catalytic amounts of tetrapropylammonium perruthenate in the presence of N-methylmorpholine N-oxide produced 4-C-alkylribono-1,4-lactones in high yields. Mesylation of the latter compounds at the 5-hydroxyl position and treatment with a protected homocysteine thiolate afforded protected 4-C-alkyl/aryl-SRH analogues as the lactones. Reduction with lithium triethylborohydride and successive global deprotections with TFA afforded 4-C-alkyl/aryl SRH analogues. These analogues might impede the S-ribosylhomocysteinase(LuxS)-catalyzed reaction by preventing β-elimination of a homocysteine molecule, and thus depleting the production of quorum sensing signaling molecule AI-2.