Opening Advanced Laboratories to School Students: Our Model for Structuring Round‐Trip Activities from School to University and Back

Collaboration with universities may assist secondary schools faced with challenges of promoting state‐of‐the‐art chemistry and biosciences education. This paper outlines university‐based programs in Israel (Belmonte) and Italy (CusMiBio) that enhance learning experiences by allowing classes of pupils to interact with academics and perform hands‐on experiments in advanced scientific laboratories. These programs facilitate a symbiotic relationship between secondary schools and the university. This paper outlines a conceptual model for university‐based science interventions. We describe the programs at Belmonte and CusMiBio, and explain how each program implements group activities for hybrid science laboratories that aim to enhance learning. Teacher training is also described, along with activities essential for establishing a round‐trip experience‐ whereby learning activities continue to have an impact after completion of these special trips to the university laboratory.     

The effect of individual variation on the structure and function of interaction networks in harvester ants

Social insects exhibit coordinated behaviour without central control. Local interactions among individuals determine their behaviour and regulate the activity of the colony. Harvester ants are recruited for outside work, using networks of brief antennal contacts, in the nest chamber closest to the nest exit: the entrance chamber. Here, we combine empirical observations, image analysis and computer simulations to investigate the structure and function of the interaction network in the entrance chamber. Ant interactions were distributed heterogeneously in the chamber, with an interaction hot-spot at the entrance leading further into the nest. The distribution of the total interactions per ant followed a right-skewed distribution, indicating the presence of highly connected individuals. Numbers of ant encounters observed positively correlated with the duration of observation. Individuals varied in interaction frequency, even after accounting for the duration of observation. An ant''s interaction frequency was explained by its path shape and location within the entrance chamber. Computer simulations demonstrate that variation among individuals in connectivity accelerates information flow to an extent equivalent to an increase in the total number of interactions. Individual variation in connectivity, arising from variation among ants in location and spatial behaviour, creates interaction centres, which may expedite information flow.     

Principles of remote attestation

Remote attestation is the activity of making a claim about properties of a target by supplying evidence to an appraiser over a network. We identify five central principles to guide development of attestation systems. We argue that (i) attestation must be able to deliver temporally fresh evidence; (ii) comprehensive information about the target should be accessible; (iii) the target, or its owner, should be able to constrain disclosure of information about the target; (iv) attestation claims should have explicit semantics to allow decisions to be derived from several claims; and (v) the underlying attestation mechanism must be trustworthy. We illustrate how to acquire evidence from a running system, and how to transport it via protocols to remote appraisers. We propose an architecture for attestation guided by these principles. Virtualized platforms, which are increasingly well supported on stock hardware, provide a natural basis for our attestation architecture.     

Stability of vitamin C derivatives in topical formulations containing lipoic acid,vitamins A and E

The stability of ascorbyl palmitate, sodium ascorbyl phosphate and magnesium ascorbyl phosphate in topical formulations was investigated by direct reverse phase high performance liquid chromatography after sample dilution with a suitable buffer – organic solvent mixture. Ascorbyl palmitate, sodium ascorbyl phosphate and magnesium ascorbyl phosphate are derivatives of ascorbic acid which differ in hydrolipophilic properties. They are widely used in cosmetic and pharmaceutical preparations. According to the results, ascorbyl esters showed significant differences: sodium ascorbyl phosphate and magnesium ascorbyl phosphate are more stable derivatives of vitamin C than ascorbyl palmitate and may be easily used in cosmetic products.     

Correlation between interfacial molecular structure and mechanics in CNT/epoxy nano-composites

We study the effect of the molecular nature of the interface between an epoxy matrix and multi-walled carbon nanotubes (CNTs) on the mechanical properties of the resultant nano-composites, with emphasis on toughness. A number of samples based on variously functionalized CNTs, namely, pristine, carboxylated, and aminated CNTs are examined, with different qualities of dispersion. Nano-composite toughness is found to increase with enhanced interfacial adhesion, an effect that is opposite to what is usually observed in traditional fiber-based composites. The classical pull-out energy model is shown to effectively explain this result. It is thus possible to tune the toughness of a nano-composite by adjusting the molecular nature of its interface and the CNT characteristics, namely its strength and its length relative to its critical length.     

Tools for multiple-CPU environments

A brief overview precedes ten separate tool reviews. Five of the tools address the problems of performance analysis, testing, and debugging in a multiple-CPU environment. The first set of tools-Graspin PPSE, and Integral-supports this activity by providing specification or design languages for concurrent applications. The next pair of tools-Pie and Total-supports the development of multiple-CPU software by representing the software's behavior in a parallel or concurrent environment. The next set of five tools is aimed at the problem of serial-to-parallel conversions. The first three tools-E/SP, Mimdizer, and PRETS-recapture the design of the original source code and display it in a graphical form for analysis. The remaining tools-Pat and Aspar-support direct source-to-source transformations. These ten tools are representative of current approaches being taken to address the problem of multiple-CPU computing     

High Performance Liquid Chromatographic Determination of Sodium Cromoglycate

A simple and precise liquid chromatographic method was developed for the estimation of sodium cromoglycate (SC) in pharmaceuticals. The drug was chroma-tographed on a reverse phase C18 column. The eluants were monitored at a wavelength of 325 nm utilizing a mixture (80:20) of solution A: 0.025 M 1-octane sulfonic acid sodium salt in acetic acid (1:100), and solution B: methanol, aceto-nitrile (3:2). Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for its linearity, accuracy, precision, selectivity, limit of detection and limit of quantitation. Due to its simplicity and accuracy, the authors believe that the method can be used for routine quality control analysis. It does not require any specific sample preparation except for the use of a column guard before the analytical column and a suitable profiler attached to the syringe prior to injection.     

Route Setup with Local Indentifiers

The paper introduces a reliable distributed procedure for establishing and cancelling routes in a circuit-switched data network that uses local path identifiers (LPID). The procedure ensures that the route is set up properly unless a failure is encountered, data messages are delivered to their destinations unless they encounter a cancellation process and the route is cancelled, and all LPID entries are released after a failure or session completion.     

A Three-Node Packet Radio Network

A two-hop packet radio network consisting of three nodes is considered. The three nodes have infinite buffers and share a common radio channel for transmitting their packets. Two of the nodes forward their packets to a third node that acts as a source of data as well as a relay that forwards all the packets entering the network to a main station. We assume that two of the nodes are granted full rights in accessing the channel while the third node uses a random access scheme. For this network we derive the condition for steady state and the generating function of the joint queue length distribution at the nodes in steady state. We also give several numerical examples and compare the performance of the network with and without a relay node.