Flow-sensitive Leakage Analysis in Mobile Ambients

In this paper, we present a refinement of a Control Flow Analysis aimed at studying information flow security in the the calculus of Mobile Ambients. The improvements are achieved by making the analysis be flow-sensitive: the analysis is able to keep track of temporal dependencies of capabilities application when computing a safe approximation of the run-time topology of Mobile Ambient processes.     

Design and Modelling of Photonic Band-Gap Resonance Cavity

An optimal design of Photonic Band-Gap (PBG) based resonance cavities has been carried out and optimal design rules have been drawn by a very fast and accurate computer code, developed by the authors, implementing a new model of one-dimensional finite-size PBG materials. The model also takes into account the presence of defects; it allows to accurately determine the mode propagation constants, electromagnetic harmonics and total field distribution, transmission and reflection coefficients, forward and backward power flow, guided and radiated power and total losses due to radiation, Bragg scattering and out of plane scattering. The design of resonance cavities advancing the state of the art of commercial Dense Wavelength Division Multiplexing (DWDM) filters is performed. A great number of optical cavities have been designed and quickly simulated thanks to the fastness of the code, allowing optimal design rules to be drawn.     

Preface by the section editors

The papers in this special section present a sample of recent approaches to modeling and verification of software-based systems. This research was initially presented at the 4th International Conference on Verification, Model Checking, and Abstract Interpretation (VMCAI 03). The choice of papers for the issue was based on their merit as well as on the fact that, as a group, they represent the main current research areas in the field of software-based systems.     

Molecular basis of phospholipase A2 inhibition by petrosaspongiolide M

Petrosaspongiolide M (PM) is an anti-inflammatory marine metabolite that displays a potent inhibitory activity toward group II and III secretory phospholipase A(2) (PLA(2)) enzymes. The details of the mechanism, which leads to a covalent adduct between PLA(2) and gamma-hydroxybutenolide-containing molecules such as PM, are still a matter of debate. In this paper the covalent binding of PM to bee venom PLA(2) has been investigated by mass spectrometry and molecular modeling. The mass increment observed for the PM-PLA(2) adduct is consistent with the formation of a Schiff base by reaction of a PLA(2) amino group with the hemiacetal function (masked aldehyde) at the C-25 atom of the PM gamma-hydroxybutenolide ring. Proteolysis of the modified PLA(2) by the endoprotease LysC followed by HPLC MS analysis allowed us to establish that the PLA(2) alpha-amino terminal group of the Ile-1 residue was the only covalent binding site for PM. The stoichiometry of the reaction between PM and PLA(2) was also monitored and results showed that even with excess inhibitor, the prevalent product is a 1:1 (inhibitor:enzyme) adduct, although a 2:1 adduct is present as a minor component. The 2:1 adduct was also characterized, which showed that the second site of reaction is located at the epsilon -amino group of the Lys-85 residue. Similar results in terms of the reaction profile, mass increments, and location of the PLA(2) binding site were obtained for manoalide, a paradigm for irreversible PLA(2) inhibitors, which suggests that the present results may be considered of more general interest within the field of anti-inflammatory sesterterpenes that contain the gamma-hydroxybutenolide pharmacophore. Finally, a 3D model, constrained by the above experimental results, was obtained by docking the inhibitor molecule into the PLA(2) binding site through AFFINITY calculations. The model provides an interesting insight into the PM-PLA(2) inhibition process and may prove useful in the design of new anti-inflammatory agents that target PLA(2) secretory enzymes.     

Theoretical characterization of multilayer photonic crystals having a 2D periodicity

We present a new, very accurate and fast model of photonic bandgap (PBG) structure characterized by a two‐dimensional (2D) periodic change of the refractive index and finite height, therefore named quasi 3D PBG. The new model is based on the Floquet–Bloch formalism and allows to find all the propagation characteristics including the space harmonics and the total field distribution, the propagation constants, the guided and radiated power and modal loss induced by the 2D grating. A clear explanation of the physical phenomena occurring when a wave propagates inside the 2D periodic structure is presented, including the photonic bandgap formation and the radiation effects. The approach does not require any theoretical approximation, and can be applied to study rigorously any PBG‐based multilayer structures. We have applied the model to investigate several structures for both optical and microwave applications. Copyright © 2005 John Wiley & Sons, Ltd.     

Personalized emergency medical assistance for disabled people

Being able to promptly and accurately choose a proper course of action in the field is a crucial aspect of emergency response. For this reason, emergency medical services (EMS) rely on well established procedures that apply to the most frequent cases first responders encounter in their practice, but do not include special cases concerning (sensory, motor or cognitive) disabled persons. In these cases, first responders may end up applying suboptimal or possibly wrong procedures or lose precious time trying to adapt on-the-fly to the special case. This paper proposes both (i) a detailed patient model for EMS that can account for peculiar aspects of the many existing disabilities and (ii) an adaptive information system called PRESYDIUM (Personalized Emergency System for Disabled Humans) that provides tailored instructions in the field for helping medical first responders in dealing with disabled persons. More precisely, we will illustrate and discuss: (i) the design and development process of PRESYDIUM, (ii) the patient model, which is partly based on the ICF (International Classification of Functioning, Disability and Health) standard proposed by the World Health Organization, (iii) the knowledge base used by the system to provide tailored instructions to medical first responders, (iv) the Web-based architecture of the system, (v) the different interfaces??including one for mobile devices??the system provides to enable all the identified stakeholders (disabled persons, their families, clinicians, EMS call center operators, medical first responders) to easily access and possibly provide data to the system, (vi) the evaluation of the validity of the patient model and of the system usability which has been conducted with end users.     

Acellular Dermal Matrix Used in Diabetic Foot Ulcers: Clinical Outcomes Supported by Biochemical and Histological Analyses

Diabetic foot ulcer (DFU) is a diabetes complication which greatly impacts the patient’s quality of life, often leading to amputation of the affected limb unless there is a timely and adequate management of the patient. DFUs have a high economic impact for the national health system. Data have indeed shown that DFUs are a major cause of hospitalization for patients with diabetes. Based on that, DFUs represent a very important challenge for the national health system. Especially in developed countries diabetic patients are increasing at a very high rate and as expected, also the incidence of DFUs is increasing due to longevity of diabetic patients in the western population. Herein, the surgical approach focused on the targeted use of the acellular dermal matrix has been integrated with biochemical and morphological/histological analyses to obtain evidence-based information on the mechanisms underlying tissue regeneration. In this research report, the clinical results indicated decreased postoperative wound infection levels and a short healing time, with a sound regeneration of tissues. Here we demonstrate that the key biomarkers of wound healing process are activated at gene expression level and also synthesis of collagen I, collagen III and elastin is prompted and modulated within the 28-day period of observation. These analyses were run on five patients treated with Integra^® sheet and five treated with the injectable matrix Integra^® Flowable, for cavitary lesions. In fact, clinical evaluation of improved healing was, for the first time, supported by biochemical and histological analyses. For these reasons, the present work opens a new scenario in DFUs treatment and follow-up, laying the foundation for a tailored protocol towards complete healing in severe pathological conditions.     

Nano-scaled chalcogenide-based memories

Today phase change memory (PCM) technology has reached product maturity at 90 and 65 nm nodes, while the 45 nm node is under development and is expected to enter in the market soon. The continuous decrease of the cell size with scaling leads to an effective active area as small as 150 nm(2) and an active volume involved in the phase transformation of about 10(4) nm(3), thus entering definitively into the nanotechnology world. At this extremely reduced dimension, the reliability of the device must be carefully investigated. In this work we show that the cycling performance of the device is well maintained, not being a problem for either the bipolar transistor or the storage element. The phase transition from the amorphous to the crystalline state is, of course, one of the most interesting phenomena, impacting cell retention capability and device performance. The stochastic nature of nano-nuclei percolation in the amorphous matrix is shown as an important ingredient in the retention of PCM devices. The related dispersion in crystallization times is analyzed through a crystallization Monte Carlo model and a physical insight into nucleation and growth mechanisms is provided.     

Meiotic progression of isolated mouse spermatocytes under simulated microgravity

Progression through the prophase of the first meiotic division can be obtained in culture by treatment of mouse spermatocytes with the serine/threonine phosphatase inhibitor okadaic acid. Chromosome condensation during this G2/M transition involves the activation of the MAPK pathway, which causes the activation of Nek2 and the phosphorylation of the chromatin architectural protein Hmga2. In an effort to set up conditions to allow a spontaneous progression of mouse spermatocytes through meiosis, we have investigated the cell-cycle features of these cells cultured for 24 h with a rotary cell culture system in a humidified atmosphere in a thermostatic incubator to simulate a microgravity environment. Morphological analysis of nuclear squashes indicated a 2-fold increase in late-pachytene spermatocytes with highly condensed chromosomes, and a contemporaneous decrease of mid-pachytene cells with less condensed chromatin. Microgravity induced a 2-fold activation of the cyclinB-cdc2 complex, confirming at the molecular level that cell-cycle progression had occurred. Moreover, using immuno-kinase assays with specific substrates we have demonstrated that the meiotic progression obtained under microgravity conditions is accompanied by activation of the Erk1/p90Rsk2 pathway. These data indicated that activation of the MAPK pathway correlates with chromatin condensation even under conditions in which meiotic progression occurs spontaneously and is not induced by a drug. We suggest that culture under microgravity conditions might help to release the block that inhibits isolated spermatocytes from progressing through prophase at unit gravity, and to study the physiological events of germ cell differentiation in vitro.