A Multiband Printed Log-Periodic Dipole Array for Wireless Communications

A multiband printed Log-periodic dipole array (LPDA) antenna for wireless communications is presented. The antenna has been designed starting from Carrel's theory, optimized using CST Microwave Studio 2012, and then realized. The comparison between simulated and measured results shows that the proposed antenna can be used for wireless communications both in the S (2.4–3 GHz) and in the C (5.2–5.8 GHz) frequency bands, with very good input matching and a satisfactory end-fire radiation pattern. Moreover, it has a compact size, is very easy to realize, and presents an excellent out-of-band rejection, without the use of stop-band filters, thus avoiding interference out of its operating frequency band

THE COMBINED USE OF TRANSCRANIAL MAGNETIC STIMULATION AND ELECTROENCEPHALOGRAPHY IN THE INVESTIGATION OF REACTIVITY, CONNECTIVITY AND PLASTICITY OF THE PRIMARY MOTOR CORTEX

The present thesis comprises two main parts: one theoretical and one experimental. The first part, composed of two chapters, is an in-depth introduction to transcranial magnetic stimulation (TMS) and its simultaneous use with neuroimaging techniques (coregistration). The second part is composed of some of the studies I conducted during my PhD. I chose to include three studies representing the different aspects of my research in the last three years, mainly regarding the study and the application of TMS-EEG coregistration in research (study 1), clinics (study 2) and technical methodology (study 3). The first study (study 1), conducted at the Department of General Psychology of Padova, was aimed to investigate the neuromodulatory effects of an rTMS protocol on healthy volunteers. The second study (study 2) was conducted at the Institute of Neurology of University College London in the context of the international “TrackOnHD” longitudinal project aimed to investigate Huntington disease (HD) in a multimodal approach. The target of this study was to investigate possible TMS-EEG markers of inhibition deficits in Huntington patients. The third study (study 3), conducted in collaboration with the Department of Information Engineering of Padova, was aimed to develop an algorithm of correction to remove an artefact induced by TMS during EEG recordings. CHAPTER I – TRANSCRANIAL MAGNETIC STIMULATION In the last twenty years the development of new techniques able to investigate the brain function in vivo during cognitive and motor tasks lead to impressive advances in understanding the human brain. Transcranial magnetic stimulation (TMS) is a tool whose popularity has grown progressively thanks to its ability to stimulate the brain in a focal and non-invasive way (Barker et al., 1985), permitting to establish a causal link in the brain-cognition/motor-behaviour relationship (Pascual-Leone et al., 2000). In the first chapter of this thesis the possible applications of TMS in the field of cognition, physiology and rehabilitation are discussed. Specifically, the first part focuses on the operating mechanisms of TMS and on the different stimulation parameters that define the effects of the stimulation. In the second part of the first chapter, the three main TMS protocols are discussed: single-pulse TMS, which is used in the temporal and spatial characterization of cognitive processes, in the study of motor cortex reactivity, and in the investigation of the cortico-spinal tract functioning; paired-pulse TMS, that investigates the connectivity and the interaction of cerebral networks at rest or during a task performance; and repetitive TMS (rTMS), that explores the cerebral plasticity processes both in relation to cognitive processing and for rehabilitation treatments. CHAPTER II – THE SIMULTANEOUS USE OF TRANSCRANIAL MAGNETIC STIMULATION WITH EEG AND OTHER NEUROIMAGING TECHNIQUES Despite the widespread use of TMS in current research, its mechanism of action is still poorly understood (Miniussi et al., 2010). This lack in comprehension results from missing a firsthand “visible” marker of cortical response and a need for secondary measures of primary motor and visual cortex stimulation. In the last twenty years, thanks to the progressive improvements in neuroimaging technology, the first attempts to simultaneously use TMS with other neuroimaging techniques have been made possible (e.g. TMS-EEG, Ilmoniemi et al., 1997; TMS-PET, Paus et al., 1997). On one hand, the possibility to actively stimulate the brain with TMS allows to establish “causal” inferences in neuroimaging studies, in which, traditionally, only “correlational” inferences were possible. On the other hand, neuroimaging techniques potentially provide an important contribution through the spatial and temporal information of the neural activation evoked by TMS. In the second chapter of this thesis, the strong and the weak points of different TMS-neuroimaging coregistration approaches are depicted. Specifically, the middle part of the chapter focuses on the main topic of this thesis, i.e. the TMS-EEG coregistration. TMS-EEG, among the different approaches, is the most successful and widespread, thanks to its promising value in the investigation of brain dynamics. Indeed, EEG is able to record the post-synaptic potentials following the neuronal depolarization evoked by TMS at a high temporal resolution (Ilmoniemi et al., 1997). The analysis of the TMS-evoked EEG activity in terms of time, space, frequency and power, potentially provides important and accurate information in the local activation induced by the stimulation (cerebral reactivity), in the spread of such activation (cerebral connectivity), and in the long-lasting neuromodulatory effects following rTMS protocols (cerebral plasticity). On the other hand, the TMS-EEG coregistration, presents several technical difficulties mainly due to the different artefacts that electromagnetic stimulation induces in the EEG signal. These aspects are discussed thoroughly in the second chapter. Finally, the last part of the second chapter is dedicated to the other TMS coregistration approaches with magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT) and near-infrared spectroscopy (NIRS). CHAPTER III – STUDY 1: NEUROMODULATORY EFFECTS OF LOW-FREQUENCY RTMS: INSIGHTS FROM TMS-EEG The neuromodulatory effects of rTMS have been mostly investigated by means of peripheral motor-evoked potentials (MEPs). However, MEPs are an indirect measure of cortical excitability, also being affected by spinal excitability. The development of new TMS-compatible EEG systems allowed the direct investigation of the stimulation effects through the cortical responses evoked by TMS (TEPs). In this study, we investigated the effects of a repetitive TMS (rTMS) protocol delivered at low frequency (1 Hz), which is known to produce an inhibitory effect on cortical excitability (Chen et al., 1997). The protocol was applied over the primary motor cortex of 15 healthy volunteers and, as a control, over the primary visual cortex of 15 different healthy volunteers to examine the spatial specificity of the stimulation. The effects of the stimulation were analyzed in both groups through the single-pulse stimulation of the primary motor cortex, before and immediately after the rTMS protocol. Different measures were tested: MEPs, TEPs, local mean field power and scalp maps of the activity distribution. Results on MEPs amplitude showed a significant reduction following the rTMS over the primary motor cortex. Results on TEPs, showed a well-known TEPs pattern evoked by single-pulse stimulation of the motor cortex: P30, N45, P60 and N100. Following the motor cortex rTMS, we observed a significant increase of P60 and N100 amplitude, whose origin has been linked to the GABAb-mediated inhibitory post-synaptic potentials (Ferreri et al., 2011; Premoli et al, 2014). Results on LMFP, showed an increase of general activity induced by the single-pulse stimulation of the motor cortex, starting from 90 ms after the TMS pulse. This latency actually corresponds to the peak of GABAb inhibition. No significant effects were detected after rTMS of the primary visual cortex. The results of this study are relevant in three main aspects: (1) we confirmed the inhibitory effect of 1-hz rTMS, also providing a central correlate of such effect (TEPs); (2) we defined the spatial specificity and the origin of the inhibitory effect of 1-Hz rTMS; (3) we confirmed the possible role of the TMS-evoked N100 as a cortical inhibitory marker. The present findings could be of relevance both for therapeutic purposes, especially for pathologies characterized by inhibitory deficits (e.g. Parkinson’s disease; Huntington’s disease); and for basic research, especially in studies aimed to correlate a behavioral performance to the amount of cerebral excitability. CHAPTER IV – STUDY 2: TMS-EEG MARKERS OF INHIBITORY DEFICIT IN HUNTINGTON’S DISEASE Recent studies have shown the potential value of combining TMS and EEG for clinical and diagnostic purposes. Several TMS-EEG measures in terms of evoked potentials (i.e. TEPs), brain sources analysis, oscillatory activity and global power has been used in the assessment of brain dynamics deficits in several pathologies, such as: schizophrenia (Ferrarelli et al., 2008); psychotic disorders (Hoppenbrouwers et al., 2008); depression (Kähkönen et al., 2005); awareness disorders (Massimini et al., 2005); epilepsy (Rotenborg et al., 2008) and autism (Sokhadze et al., 2012). For instance, the potential contribution of TEPs in the investigation of the cerebral facilitatory/inhibitory balance has been demonstrated, given their origin from different GABAergic neuronal populations (Ferreri et al., 2011; Premoli et al., 2014). In particular, the TMS-evoked N100 has been related to the amount of GABAergic inhibition, as shown by pharmacological (e.g. Kähkönen et al., 2003) and behavioral research (e.g. Bender et al., 2005; Bonnard et al., 2009) as well as studies in patients (e.g. Helfrich et al., 2013). As a part of the multi-site international “TrackOnHD” project, we used TMS-EEG to investigate the electrophysiological markers of motor cortex stimulation in Huntington patients. In Huntington’s disease (HD) the progressive degeneration of GABAergic neurons in the striatum lead to a strong reduction of inhibition, resulting in an excessive increase in glutamatergic excitability (i.e. excitoxicity). Our study compared a group of 12 HD patients with a group of 12 healthy volunteers over several different TMS-EEG, EMG, fMRI and clinical measures (in the chapter only the TMS-EEG results are reported). We found a specific and significant decrease of the N100 as assessed by the time point-by-time point permutation analysis of TEPs and from the analysis of the global activity from 90 to 104 ms after the TMS pulse. Scalp maps of the activity distribution showed a bilateral decrease of negativity, such effect was stronger over the site of stimulation. Event-related spectral perturbation and inter-trial coherence analysis showed a significant difference in the oscillatory activity of the two groups within the GABAb-ergic time window (i.e. 60-110 ms after the TMS pulse). We speculated that the observed results might be produced by the deficit in GABAergic inhibition as a consequence of the striatum neuronal degeneration in HD patients. Although preliminary, these results provided potentially useful TMS-EEG markers for inhibitory deficits in HD patients. Further analyses are needed to correlate the present findings with the other measures collected. CHAPTER V – STUDY 3: TMS-EEG ARTIFACTS: A NEW ADAPTIVE ALGORITHM FOR SIGNAL DETRENDING During EEG recording the discharge of the TMS coil may generate an artefact that can last for tens of milliseconds, known as “decay artefact” (Rogasch et al., 2014). This can represent a problem for the analysis of the TMS-evoked potentials (TEPs). So far, two main strategies of correction have been proposed involving the use of a linear detrend or independent component analysis (ICA). However, none of these solutions may be considered optimal: firstly, because in most of the cases the decay artefact shows a non-linear trend; secondly, because the ICA correction (1) might be influenced by individual researcher’s choices and (2) might cause the removal of physiological responses. Our aim is to verify the feasibility of a new adaptive detrend able to discriminate the different trends of the decay (linear or non-linear). Forty healthy volunteers were stimulated with 55 TMS pulses over the left M1. The TMS-EEG responses were compared among five conditions: RAW (no correction of the decay artefact was applied); INFOMAX29 (the decay components were extracted and removed by the INFOMAX ICA algorithm, using 31 electrodes); FASTICA (the decay components were extracted and removed by the fastICA ICA algorithm, using 31 electrodes); INFOMAX15 (the decay components were extracted and removed by the INFOMAX ICA algorithm, using 15 electrodes) and ALG (the decay artefact was corrected through the use of an adaptive algorithm). To assess whether the artefact correction significantly affected the physiological responses to TMS as well, we examined the differences in the -100 + 400 ms time window around the TMS pulse by means of a non-parametric, cluster-based, permutation statistical test. Then we compared the peak-to-peak TEPs amplitude within the detected time windows. The grand-averaged EEG response revealed five main peaks: P30, N45, P60, N100 and P180. Significant differences (i.e. Monte Carlo p-values < 0.05) were detected in a cluster nearby the TMS coil, and specifically over FC1, CP1, C3 and FC2. Repeated-measures ANOVA revealed a significant corruption of the peak-to-peak amplitude after INFOMAX29 (3 TEPs out of 8), FASTICA (4 TEPs out of 12), INFOMAX15 (5 TEPs out of 15) and ALG correction (2 TEPs out of 15), compared to the original signal. Furthermore, abnormal LMFP and TEPs scalp distribution were detected following the INFOMAX29 and FASTICA correction. When our algorithm was used, however, the TEPs amplitude, morphology and distribution was in line with the literature and not significantly different from the original signal. Also the decay artefact was correctly removed. The main contribution of this study is the proposal of a new adaptive algorithm to correct the decay artefact induced by TMS in the EEG signal. Our results demonstrated that the proposed adaptive detrend is a reliable solution for the correction of this artefact, especially considering that, contrary to ICA, (1) it is not dependent from the number of recording channels; (2) it does not affect the physiological responses and (3) it is completely independent from the experimenter’s choices

Transcranial Direct Corrent stimulation (tDCS) of the anterior prefrontal cortex (aPFC) modulates reinforcement learning and decision-making under uncertainty: A doubleblind crossover study

Reinforcement learning refers to the ability to acquire information from the outcomes of prior choices (i.e. positive and negative) in order to make predictions on the effect of future decision and adapt the behaviour basing on past experiences. The anterior prefrontal cortex (aPFC) is considered to play a key role in the representation of event value, reinforcement learning and decision-making. However, a causal evidence of the involvement of this area in these processes has not been provided yet. The aim of the study was to test the role of the orbitofrontal cortex in feedback processing, reinforcement learning and decision-making under uncertainly. Eighteen healthy individuals underwent three sessions of tDCS over the prefrontal pole (anodal, cathodal, sham) during a probabilistic learning (PL) task. In the PL task, participants were invited to learn the covert probabilistic stimulusoutcome association from positive and negative feedbacks in order to choose the best option. Afterwards, a probabilistic selection (PS) task was delivered to assess decisions based on the stimulus-reward associations acquired in the PL task. During cathodal tDCS, accuracy in the PL task was reduced and participants were less prone to maintain their choice after positive feedback or to change it after a negative one (i.e., winstay and lose-shift behavior). In addition, anodal tDCS affected the subsequent PS task by reducing the ability to choose the best alternative during hard probabilistic decisions. In conclusion, the present study suggests a causal role of aPFC in feedback trial-by-trial behavioral adaptation and decision-making under uncertainty

Exploring Less Invasive Visual Surveys to Assess the Spatial Distribution of Endangered Mediterranean Trout Population in a Small Intermittent Stream

Simple Summary This study explores the use of alternative and non-harmful methods for monitoring endangered Mediterranean trout in small intermittent streams. Specifically, two visual survey techniques were compared: a visual survey from streambanks and an underwater visual survey using underwater cameras. The main objective was to assess the effectiveness of detecting patterns in fish occupancy in relation to a set of environmental factors. The comparison revealed that underwater camera surveys performed similarity to visual surveys from streambanks during low-flow regimes. However, visual surveys from streambanks were less effective during the highest flow regimes. The volume of pools and the percentage cover of submerged macrophytes were found to be significant environmental variables affecting fish detection probability using underwater cameras. On the other hand, the analysis of data from visual observations from streambanks indicated a clear impact of high turbulence rates on pool occupancy. In conclusion, these findings demonstrate the utility of visual methods in describing the occupancy patterns of Mediterranean trout in small streams. Monitoring the conservation status of endangered freshwater fish using less invasive methods poses challenges for ecologists and conservationists. Visual surveys have been proposed as an alternative to electrofishing, which is a standard methodology that can cause injuries, physiological stress and post-release mortality in organisms. To test the efficacy of visual methods, a study was conducted in an intermittent stream of Sardinia (Italy). Two visual methods were employed: a visual survey from streambanks (VSS) and an underwater visual survey (UVS) using cameras. The aims of this study were (1) to compare the effectiveness of these methods in detecting patch occupancy patterns and (2) to investigate the effect of environmental variables on the detection probability of Mediterranean native trout. Environmental variables characterizing pool habitats were recorded, and generalized linear models (GLMs) were employed to assess the correlation between these variables and trout presence/absence. GLM analysis revealed that UVS had higher detection probability with larger pool volume, whereas submerged macrophytes negatively affected detection probability. Detection from streambanks (VVS) was negatively affected by a high turbulence rate. In conclusion, our study suggests the utility of visual methods to describe patterns of patch occupancy of Mediterranean trout. However, methods can be differently affected by environmental variables. Therefore, monitoring programs using these methods should consider these factors to ensure a reliable description of within-stream trout distribution in intermittent streams

A multiband proximity-coupled-fed flexible microstrip antenna for wireless systems

A multiband printed microstrip antenna for wireless communications is presented. The antenna is fed by a proximity-coupled microstrip line, and it is printed on a flexible substrate. The antenna has been designed using a general-purpose 3D computeraided design software (CAD), CST Microwave Studio, and then realized. The comparison between simulated and measured results shows that the proposed antenna can be used for wireless communications for WLAN systems, covering both the WLAN S-band (2.45GHz) and C-band (5.2GHz), and the Wi-Max 3.5GHz band, with satisfactory input matching and broadside radiation pattern. Moreover, it has a compact size, is very easy to realize, and presents a discrete out-of-band rejection, without requiring the use of stop-band filters. The proposed structure can be used also as a conformal antenna, and its frequency response and radiated field are satisfactory for curvatures up to 65°

Executive functions and symptom severity in an Italian sample of intellectually able preschoolers with autism spectrum disorder

A novel battery (BAFE; Valeri etal. 2015) was used in order to assess three executive function (EF) abilities (working memory, inhibition and shifting) in a sample of 27 intellectually able preschoolers with autism spectrum disorder (ASD) compared with 27 typically developing children matched on age and nonverbal IQ. Differences in EF skills were analyzed in participants with distinct ASD symptom severity. Children with ASD performed worse than typical controls on both set-shifting and inhibition, but not on visuo-spatial working memory. Additionally, children with more severe ASD symptoms showed a worse performance on inhibition than children with milder symptoms. These results confirm the presence of EF deficits and highlight a link between ASD symptoms and EF impairments in preschool age

hMAF, a Small Human Transcription Factor That Heterodimerizes Specifically with Nrf1 and Nrf2

A 1.6-kilobase pair full-length cDNA encoding a transcription factor homologous to the Maf family of proteins was isolated by screening a K562 cDNA library with the NFE2 tandem repeat probe derived from the globin locus control region. The protein, which was designated hMAF, contains a basic DNA binding domain and an extended leucine zipper but lacks any recognizable activation domain. Expressed in vitro, the hMAF protein is able to homodimerize in solution and band-shift the NFE2 tandem repeat probe. In addition to homodimers, hMAF can also form high affinity heterodimers with two members of the NFE2/CNC-bZip family (Nrf1 and Nrf2) but not with a third family member, p45-NFE2. Although hMAF/hMAF homodimers and hMAF/Nrf1 and hMAF/Nrf2 heterodimers bind to the same NFE2 site, they exert functionally opposite effects on the activity of a linked gamma-globin gene. In fact, whereas all hMAF/CNC-bZip heterodimers stimulate the activity of a gamma-promoter reporter construct in K562 cells, the association into homodimers that is induced by overexpressing hMAF inhibits the activity of the same construct. Thus variations in the expression of hMAF may account for the modulation in the activity of the genes that bear NFE2 recognition sites

Les facteurs à petite échelle affectent la taille des populations du Mulot (Apodemus sylvaticus) dans une île méditerranéenne (Sardaigne)

La variation de la taille des populations de Mulot (Apodemus sylvaticus) a été étudiée le long de30 transects indépendants sur l’île de Sardaigne (Italie), avec un accent mis sur la relation entre la taille de la population et les variables environnementales (type de boisement, épaisseur de la litière, diversité et taille des arbres, nombre de souches, couverture du sol, couverture buissonnante, bois mort). Les études ont été conduites selon un protocole de capture-marquage-recapture à l’aide de pièges placés le long des transects et surveillés au printemps et en automne. Sept variables environnementales ont été confrontées aux estimations de taille de population sur chaque transect, estimations obtenues à partir de cinq modèles démographiques distincts pour populations fermées. Des différences inter-saisonnières significatives ont été observées dans le nombre de spécimens capturés (pic au printemps) mais, en dépit de variations considérables selon les transects, la taille des populations de Mulot ne différait pas de manière significative entre les types d’habitats forestiers. La taille des populations de l’espèce est apparue positivement influencée par (i) la couverture au sol, (ii) le nombre de souches, et (iii) le % d’Erica arborea ; à l’inverse elle est apparue négativement influencée par (a) la hauteur des buissons de Rubus ulmifolius et (b) par le % de Rubus ulmifolius. Les raisons de ces patterns sont envisagées et discutéesThe variation of population size of the Wood Mouse (Apodemus sylvaticus) was studied across 30 independent transects in Sardinia island (Italy), with emphasis on the relationships between population size and environmental variables (type of wood, litter depth, tree diversity, tree size, number of stumps, ground cover, shrub cover, dead wood). Studies were conducted through a capture-mark-recapture protocol with live traps placed along line transects, and surveyed in both spring and autumn. Seven environmental variables were contrasted to population size estimates in each transect, with estimates of population size being obtained from five distinct demography models for close populations. There were significant inter-seasonal differences in the number of captured specimens (peak in springtime), but the population size of the Wood Mouse, despite varying considerably by transect, did not differ significantly among types of forest habitats. Population size of this species was positively influenced by (i) ground cover, (ii) number of stumps, and (iii) % Erica arborea; conversely, it was negatively influenced by (a) height of Rubus ulmifolius bushes and (b) by % Rubus ulmifolius. The possible reasons behind these patterns were explored and discusse

Veterinarski obilazak mliječnih farmi s povećanim brojem somatskih stanica i bakterija iznad zakonom dozvoljenih vrijednosti

The EU Directives 92/46 and 92/47 (D.P.R. 54/97 under national legislation) fix the agreed levels of somatic cell counts and total bacterial counts allowed in milk. Over a one year period, a total of 165farms which did not comply with one or more such legal requirements were visited and monitored. This was in order to check and, where necessary, correct the hygienic and sanitary management of the farm. A comparison of the bulk tank milk somatic cell count (BTMSCC) before and after the veterinary visit, shows improvements in all the farms which were tested. In a relatively short time, visited dairy farms with a somatic cell content between 401.000 and 500.000 cells/ml managed to comply with the parameters set down by law, achieving a mean of 304.000 cells/ml. However, those farms with a somatic cell counts between 501.000 and 800.000 cells/ml required further technical action. In fact, despite considerable improvements (mean somatic cell count decreasing from 638.000 cells/ml to 403.000 cells/ml), it was not possible to meet the required levels so rapidly. On these farms, a second veterinary visit was needed as well as more specific milk sampling for bacteriological assay and therapeutic guidelines in order to meet the specified requirements.Smjernicama 92/46. i 92/47. (D.P.R. 54/97). Europska unija je utvrdila maksimalno dozvoljene vrijednosti ukupnog broja bakterija i somatskih stanica u mlijeku. Unutar godine dana posjećeno je 165 farmi koje nisu zadovoljavale svim uvjetima. Posjet je obavljen s ciljem da se snimi postojeća situacija, i, ukoliko je neophodno, da se provedu adekvatne korekcije u higijenskom i sanitarnom vođenju farmi. Usporedbom broja somatskih stanica (BTMSCC) u dobavnim tankovima za mlijeko, prije i poslije veterinarske posjete, uočena su poboljšanja na svim ispitanim farmama. Ispitane mliječne farme s brojem somatskih stanica između 401000 i 500.000 stanica/mL u relativno kratkom vremenu uspjele su smanjiti taj broj na prosječnih 304.000 stanica/mL, što udovoljava propisanim vrijednostima. Međutim, na farmama s brojem somatskih stanica između 501.000 i 800.000 Stanica/mL potrebno je provesti dodatne tehničke mjere. Usprkos značajnom poboljšanju (prosječni broj somatskih stanica smanjene je sa 638.000 stanica/mL na 403.000 stanica/mL), nisu dobivene vrijednosti unutar zakonski propisanih. Ovim farmama bio je potreban dodatni veterinarski posjet kao i specifično bakteriološko ispitivanje te terapeutski naputci s ciljem da se postigne usuglašenost sa specifičnim zahtjevima

Sarcoma risk and dioxin emissions from incinerators and industrial plants: a population-based case-control study (Italy)

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