Time-modulated multibeam phased arrays with periodic Nyquist pulses

We present a single sideband time-modulated multibeam phased array governed by periodic Nyquist pulsed signals. A Nyquist pulse is a physically realizable approach to the ideal sinc function. Hence, its low-pass spectrum suits particularly well for time-modulated arrays (TMAs) to perform harmonic beam steering. Contrarily to switched TMAs and standard solutions based on variable phase shifters, the performance and complexity of the proposed time modulation scheme is rather robust when increasing the number of multibeams.Comment: 4 pages, 4 figures, Published in IEEE Antennas and Wireless Propagation Letter

Time-modulated arrays with Haar wavelets

Time-modulated arrays (TMAs) can effectively perform beamsteering over the first positive harmonic pattern by applying progressively delayed versions of stair-step approximations of a sine waveform to the antenna excitations. In this letter, we consider synthesizing such stair-step sine approximations by means of Haar wavelets. Haar functions constitute a complete orthonormal set of rectangular waveforms, which have the ability to represent a given function with a high degree of accuracy using few constituent terms. Hence, when they are applied to the TMA synthesis, employing single-pole double-throw switches, such a feature leads to an excellent rejection level of the undesired harmonics as well as a bandwidth greater than that supported by conventional TMAs with on-off switches.Comment: 5 pages, 4 figures, Published in IEEE Antennas and Wireless Propagation Letter

Unleashing the Potential of LTE for Next Generation Railway Communications

In an increasingly demanding marketplace that will put great strain on railway services, research on broadband wireless communication must continue to strive for improvement. Based on the mature narrowband GSM technology, Global System for Mobile Communications-Railways (GSM-R) has been deployed both for operational and voice communications. Although GSM-R fulfills the requirements of current railway services, it imposes limited capacity and high costs that restrict enhancements of operational efficiency, passenger security and transport quality. 4G Long Term Evolution (LTE) is expected to be the natural successor of GSM-R not only for its technical advantages and increasing performance, but also due to the current evolution of general-purpose communication systems. This paper examines the key features of LTE as well as its technical ability to support both the migration of current railway services and the provisioning of future ones.Comment: This is a portion of the ACCEPTED VERSION of the published document in: Kassab, M., Berbineau,M., Vinel, A., Jonsson, M., Garcia, F., Soler, J. (eds) Communication Technologies for Vehicles. Nets4Cars/Nets4Trains/Nets4Aircraft 2015. Lecture Notes in Computer Science, vol 9066. Springer, Cham. https://doi.org/10.1007/978-3-319-17765-6_1

A feasibility analysis towards the simulation of hysteresis with spin-lattice dynamics

We use spin-lattice dynamics simulations to study the possibility of modeling the magnetic hysteresis behavior of a ferromagnetic material. The temporal evolution of the magnetic and mechanical degrees of freedom is obtained through a set of two coupled Langevin equations. Hysteresis loops are calculated for different angles between the external field and the magnetocrystalline anisotropy axes. The influence of several relevant parameters is studied, including the field frequency, magnetic damping, magnetic anisotropy (magnitude and type), magnetic exchange, and system size. The role played by a moving lattice is also discussed. For a perfect bulk ferromagnetic system we find that, at low temperatures, the exchange and lattice dynamics barely affect the loops, while the field frequency and magnetic damping have a large effect on it. The influence of the anisotropy magnitude and symmetry are found to follow the expected behavior. We show that a careful choice of simulation parameters allows for an excellent agreement between the spin-lattice dynamics measurements and the paradigmatic Stoner-Wohlfarth model. Furthermore, we extend this analysis to intermediate and high temperatures for the perfect bulk system and for spherical nanoparticles, with and without defects, reaching values close to the Curie temperature. In this temperature range, we find that lattice dynamics has a greater role on the magnetic behavior, especially in the evolution of the defective samples. The present study opens the possibility for more accurate inclusion of lattice defects and thermal effects in hysteresis simulation

An automated fluorescence videomicroscopy assay for the detection of mitotic catastrophe

Mitotic catastrophe can be defined as a cell death mode that occurs during or shortly after a prolonged/aberrant mitosis, and can show apoptotic or necrotic features. However, conventional procedures for the detection of apoptosis or necrosis, including biochemical bulk assays and cytofluorometric techniques, cannot discriminate among pre-mitotic, mitotic and post-mitotic death, and hence are inappropriate to monitor mitotic catastrophe. To address this issue, we generated isogenic human colon carcinoma cell lines that differ in ploidy and p53 status, yet express similar amounts of fluorescent biosensors that allow for the visualization of chromatin (histone H2B coupled to green fluorescent protein (GFP)) and centrosomes (centrin coupled to the Discosoma striata red fluorescent protein (DsRed)). By combining high-resolution fluorescence videomicroscopy and automated image analysis, we established protocols and settings for the simultaneous assessment of ploidy, mitosis, centrosome number and cell death (which in our model system occurs mainly by apoptosis). Time-lapse videomicroscopy showed that this approach can be used for the high-throughput detection of mitotic catastrophe induced by three mechanistically distinct anti-mitotic agents (dimethylenastron (DIMEN), nocodazole (NDZ) and paclitaxel (PTX)), and – in this context – revealed an important role of p53 in the control of centrosome number

Microarray in clinical practice – utility vs complexity. Mixed phenotype of duplication 15q11.2q13.1 and deletion 16p11.2

Introduction: There’s a consensus to perform chromosomal microarray technique as first-tier clinical diagnostic test for individuals with developmental disabilities. However, given the complexity of clinical presentations, often several diagnostic methods are held before conducting microarray. Method: We report the case of a 5 year-old boy referred to Medical Genetics due to short stature, developmental disabilities and facial dysmorphic features. He was born from eutocic delivery after an uneventful pregnancy. He had psychomotor milestones delayed like sitting at 9 months and walking at 24 months, holding an immature broad-based gait. There was history of learning difficulties from both parents, and the mother has also short stature. On examination it was noted some facial dysmorphic features like high forehead, conical canines and rarefaction of the distal portion of the eyebrows. Due to the history of an episode of transient ataxia, and suspicion of an inherited metabolic disorder, he had already performed various analytical and imaging screenings, all normal. Results: Chromosomal microarray analysis revealed two pathogenic Copy Number Variants (CNV’s): 16p11.2 deletion and 15q11.2q13.1 duplication. The 15q11q13 microduplication syndrome (OMIM # 608636) is a very rare clinical entity with about 30 reported cases with maternal origin, and it is characterized by neurobehavioral disorder, hypotonia, cognitive impairment, epilepsy and short stature. The 16p11.2 microdeletion syndrome (OMIM # 613444) is also a rare clinical entity, with high penetrance, associated with obesity and developmental disabilities. Discussion: Despite the unquestionable utility of microarray, the correlation of the CNV's with the phenotype is often difficult by the rarity of these new microdeletion/duplication clinical entities. In this case the interpretation has increased difficulty because of the simultaneous existence of two distinct clinical entities. Segregation studies, which in the first step include parental analysis, are essential for genetic counseling and determining the risk of recurrence but also for a more accurate correlation genotype-phenotype