Human-mobility enabled wireless networks for emergency communications during special events

During social gatherings or emergency situations, infrastructure-based communication networks have difficulty operating given either increased traffic demand or possible damage. Nevertheless, current communication networks still rely on centralized networking paradigms. The adoption of a peer-to-peer communication paradigm would be better adapted to these needs, especially if it relies on the mobile phones that people normally carry, since they are automatically distributed where the communication needs are. However a question arises: can the spatio-temporal distribution of mobile phones enable a partially-connected ad hoc network that allows emergency communications to happen with an acceptable delay? To try to answer this question, we defined a methodology composed of three steps. First, the positions of seven hundred humans, spread over a metropolitan area, have been anonymously traced during a special gathering event. Then, with a multi-disciplinary approach, we have inferred the contact events from the humans’ traces. Finally, we have assessed the effectiveness of an ad hoc network established by the mobile phones to disseminate emergency information to the population in a timely fashion. The results reveal that the humans’ mobility can effectively enable emergency communications among a significant subset of mobile phones, although the connectivity of the network strictly depends on the number of cooperating devices and on the maximum allowed delay.     

A framework for Resource-Aware Data Accumulation in sparse wireless sensor networks

Wireless sensor networks (WSNs) have become an enabling technology for a wide range of applications. In contrast with traditional scenarios where static sensor nodes are densely deployed, a sparse WSN architecture can also be used in many cases. In a sparse WSN, special mobile data collectors (MDCs) are used to gather data from ordinary sensor nodes. In general, sensor nodes do not know when they will be in contact with the MDC, hence they need to discover its presence in their communication range. To this end, discovery mechanisms based on periodic listening and a duty-cycle have shown to be effective in reducing the energy consumption of sensor nodes. However, if not properly tuned, such mechanisms can hinder the data collection process. In this paper, we introduce a Resource-Aware Data Accumulation (RADA), a novel and lightweight framework which allows nodes to learn the MDC arrival pattern, and tune the discovery duty-cycle accordingly. Furthermore, RADA is able to adapt to changes in the operating conditions, and is capable of effectively supporting a number of different MDC mobility patterns. Simulation results show that our solution obtains a higher discovery efficiency and a lower energy consumption than comparable schemes.     

A Survey of Specularity Removal Methods

The separation of reflection components is an important issue in computer graphics, computer vision and image processing. It provides useful information for the applications that need consistent object surface appearance, such as stereo reconstruction, visual recognition, tracking, objects re‐illumination and dichromatic editing. In this paper we will present a brief survey of recent advances in separation of reflection components, also known as specularity (highlights) removal. Several techniques that try to tackle the problem from different points of view have been proposed so far. In this survey, we will overview these methods and we will present a critical analysis of their benefits and drawbacks.     

On vehicle placement to intercept moving targets

We address optimal placement of vehicles with simple motion to intercept a mobile target that is generated stochastically on a line segment. The optimality of vehicle placement is measured through a cost function associated with intercepting the target. With a single vehicle, we assume that the target moves (i) with fixed speed and in a fixed direction perpendicular to the line segment, or (ii) to maximize the distance from the line segment, or (iii) to maximize intercept time. In each case, we show that the cost function is strictly convex, its gradient is smooth, and the optimal vehicle placement is obtained by a standard gradient-based optimization technique. With multiple vehicles, we assume that the target moves with fixed speed and in a fixed direction perpendicular to the line segment. We present a discrete-time partitioning and gradient-based algorithm, and characterize conditions under which the algorithm asymptotically leads the vehicles to a set of critical configurations of the cost function.     

Blind source extraction for robust speech recognition in multisource noisy environments

This paper proposes and describes a complete system for Blind Source Extraction (BSE). The goal is to extract a target signal source in order to recognize spoken commands uttered in reverberant and noisy environments, and acquired by a microphone array. The architecture of the BSE system is based on multiple stages: (a) TDOA estimation, (b) mixing system identification for the target source, (c) on-line semi-blind source separation and (d) source extraction. All the stages are effectively combined, allowing the estimation of the target signal with limited distortion.While a generalization of the BSE framework is described, here the proposed system is evaluated on the data provided for the CHiME Pascal 2011 competition, i.e. binaural recordings made in a real-world domestic environment. The CHiME mixtures are processed with the BSE and the recovered target signal is fed to a recognizer, which uses noise robust features based on Gammatone Frequency Cepstral Coefficients. Moreover, acoustic model adaptation is applied to further reduce the mismatch between training and testing data and improve the overall performance. A detailed comparison between different models and algorithmic settings is reported, showing that the approach is promising and the resulting system gives a significant reduction of the error rate.     

Contribution of electrospray mass spectrometry for the characterization, design, and development of nitrido technetium and rhenium heterocomplexes as potential radiopharmaceuticals

Diagnostic nuclear medicine (NM) is among the imaging procedures (together with X-ray, computerized tomography, magnetic resonance, and echography) the clinicians can routinely adopt to image organs or tissues and related disorders. (99m)Tc-based agents are the radiopharmaceuticals of election in diagnostic NM because of the ideal physical properties of the 99mTc nuclide (t1/2 6.01 hr; Egamma 142 keV), low cost, and easy availability through the commercial 99Mo/99mTc generator, and chemical versatility of the element. In the last two decades the synergistic work of clinics, pharmacologists, and coordination chemists has had a tremendous impact in the development of new 99mTc-based radiopharmaceuticals through the recognition of the structure at the molecular level of the agent utilized. This has been achieved by studying the physico-chemical properties of the long-lived 99gTc (t1/2 2.11 x 10(5) year; Ebeta 292 keV) and third-row congener Re isostructural compounds. Electrospray ionization mass spectrometry (ESI-MS) and collision experiments (MS/MS) represent valuable analytical techniques suitable for the characterization of both technetium and rhenium complexes relevant to NM. Unequivocal structural identification of these bioinorganic compounds, either simple coordination complexes ("essential radiopharmaceuticals") or more sophisticated structures carrying bioactive fragments ("receptor-specific" radiopharmaceuticals), can be realized in combination with multinuclear NMR spectroscopy. MS/MS experiments provide useful information on the different metal-ligand bond strength, and comparison of the fragmentation profiles of isostructural technetium and rhenium compounds give additional details on the role played by the metal in determining preferred decomposition channels. The analysis of these data contribute to design novel synthetic strategies for the obtainment of technetium and rhenium compounds relevant to NM. The chemistry underlying the production of a new class of potential radiopharmaceuticals including a terminal nitrogen bond and a mixed coordination sphere comprising heterodiphosphines and/or dithiocarbamates (DTC) is presented in detail together with the ESI-MS and MS/MS investigations.     

Muscle discretization affects the loading transferred to bones in lower-limb musculoskeletal models

Modelling the mechanical effect of muscles is important in several research and clinical contexts. However, few studies have investigated the effect of different muscle discretizations from a mechanical standpoint. The present study evaluated the errors of a reduced discretization of the lower-limb muscles in reproducing the muscle loading transferred to bones. Skeletal geometries and a muscle data collection were derived from clinical images and dissection studies of two cadaver specimens. The guidelines of a general method previously proposed for a different anatomical district were followed. The data collection was used to calculate the mechanical effect of muscles, i.e. the generalized force vectors, and the errors between a large and a reduced discretization, in a reference skeletal pose and in the extreme poses of the range of motion of joints. The results showed that the errors committed using a reduced representation of muscles could be significant and higher than those reported for a different anatomical region. In particular, the calculated errors were found to be dependent on the individual anatomy and on the skeletal pose. Since different biomechanical applications may require different discretization levels, care is suggested in identifying the number of muscle lines of action to be used in musculoskeletal models.     

X-ray microscopy of plant cells by using LiF crystal as a detector

A lithium fluoride (LiF) crystal has been utilized as a new soft X-ray detector to image different biological samples at a high spatial resolution. This new type of image detector for X-ray microscopy has many interesting properties: high resolution (nanometer scale), permanent storage of images, the ability to clear the image and reuse the LiF crystal, and high contrast with greater dynamic range. Cells of the unicellular green algae Chlamydomonas dysosmos and Chlorella sorokiniana, and pollen grains of Olea europea have been used as biological materials for imaging. The biological samples were imaged on LiF crystals by using the soft X-ray contact microscopy and contact micro-radiography techniques. The laser plasma soft X-ray source was generated using a Nd:YAG/Glass laser focused on a solid target. The X-ray energy range for image acquisition was in the water-window spectral range for single shot contact microscopy of very thin biological samples (single cells) and around 1 keV for multishots microradiography. The main aim of this article is to highlight the possibility of using a LiF crystal as a detector for the biological imaging using soft X-ray radiation and to demonstrate its ability to visualize the microstructure within living cells.     

High-resolution water window X-ray imaging of in vivo cells and their products using LiF crystal detectors

High contrast imaging of in vivo Chlorella sorokiniana cells with submicron spatial resolution was obtained with a contact water window X-ray microscopy technique using a point-like, laser-plasma produced, water-window X-ray radiation source, and LiF crystals as detectors. This novel type of X-ray imaging detectors is based on photoluminescence of stable electronic point defects, characterized by high intrinsic resolution. The fluorescence images obtained on LiF crystals exposed in single-shot experiments demonstrate the high sensitivity and dynamic range of this new detector. The powerful performances of LiF crystals allowed us to detect the exudates of Chlorella cells in their living medium and their spatial distribution in situ, without any special sample preparation.