Search

The problem of beam alignment (BA) in a cell-free massive multiple-input multiple-output (CF-mMIMO) system operating at millimeter wave (mmWaves) carrier frequencies is considered in this paper. Two estimation algorithms are proposed, in association with a protocol that permits simultaneous estimation, on a shared set of frequencies, for each user equipment (UE), of the direction of arrival and departure of the radio waves associated to the strongest propagation paths from each of the surrounding access points (APs), so that UE-AP association can take place. The proposed procedure relies on the existence of a reliable control channel at sub-6 GHz frequency, so as to enable exchange of estimated values between the UEs and the network, and assumes that APs can be identifies based on the prior knowledge of the orthogonal channels and transmit beamforming codebook. A strategy for assigning codebook entries to the several APs is also proposed, with the aim of minimizing the mutual interference between APs that are assigned the same entry. Numerical results show the effectiveness of the proposed detection strategy, thus enabling one shot fast BA for CF-mMIMO systems., Comment: 6 pages, 3 figures, submitted to the 2021 IEEE Global Communications Conference (GLOBECOM)

El siguiente trabajo constituye una aproximación, mediante un enfoque semiótico, a la significación cultural otorgada a los adornos cefálicos andinos. Múltiples son las evidencias referentes a este particular elemento, pero pocos los estudios respecto de su significación en el pasado. Teniendo en cuenta su materialidad específica y la larga continuidad de tradiciones andinas, que aún incluyen los adornos plumarios en su ritualidad y cotidianidad, logramos una aproximación al rol jugado por estos objetos/agentes dentro de la sociedad inca. El análisis de un contexto incaico particular, la practica ritual conocida como Capacocha, en la cual participó una joven aclla en el volcán Llullaillaco, permite adentrarnos en la comprensión de los procesos de constitución de la identidad personal y el rol de los adornos cefálicos en una interacción constante entre persona/objeto. Son estas relaciones las que van a definir el significado de estos elementos plumarios dentro de las sociedades pasadas. The following work constitutes an approximation, through a semiotic approach, to the cultural significance of the Andean cephalic adornments. There are many evidences concerning this particular element, but few studies on its significance in the past. Considering them as corporate emblems, taking into account their specific materiality and the long continuity of Andean traditions, which still include feather adornments in their rituality and daily life, we achieve an approximation to the role played by these objects / agents within Inca society. The analysis of a particular Inca context, the ritual practice known as Capacocha, in which a young woman took part in the volcano Llullaillaco, allows us to enter into the understanding of the processes of constitution of personal identity, and the sacredness of objects in a constant interaction between person/object. It is these relationships that will define the role and meaning of feather adornments within past societies.

The 5G CHAMPION Consortium will provide the first fully integrated and operational 5G prototype in 2018 — this effort is a major leap ahead compared to existing punctual technology trials, such as, e.g., Proof-of-Concept platforms focusing on mmWave communication in specific bands, etc. This paper describes the overall set-up including a synergetic combination of technologies such as beamforming based mmWave & Satellite service provisioning, virtualized infrastructure, software reconfiguration across the entire stack, accurate positioning and high-speed solutions. The key enablers are described in detail and related efforts in standards and regulation organizations are discussed.

This paper discusses transceiver radio architectures for the 5G immersive experience and for three extended use cases that will be studied in the WP5 of the EU funded mmMAGIC project. The need to provide multi-antenna and multi-node solutions in the mm-wave spectrum is emphasized, as well as the need to encompass legacy and other complementary RATs in this 5G system. The hardware imperfections that should be tackled or worked around in these challenging radio systems are also highlighted.

Background: Progression of Parkinson’s disease (PD) is frequently characterized by the occurrence of freezing of gait (FOG), which generally does not improve with dopaminergic therapy and with current available surgical therapies. Recent evidences show that motor symptoms may be ameliorated by means of non-invasive brain stimulation techiniques in PD (transcranial current direct stimulation, TDCS; repetitive transcranial magnetic stimulation, RTMS). Objective: To investigate the efficacy of anodal TDCS in the treatment of FOG in PD. Excitatory anodal tDCS was applied unilaterally to the motor and premotor cortices controlateral to the most affected leg. Methods: randomized, double-blind, sham-controlled study. TDCS was applied consecutively for 5 days to 8 patients who were randomly assigned to anodal or sham TDCS. Efficacy of the interventions was investigated after the 1st, the 5th stimulation, 1 week, 2 weeks and 1 month after the start of the trial. Clinical assessment was performed by Stand Walk Sit test (SWS), UPDRS, Freezing of Gait Questionnaire (FOG-Q), Gait and Falls Questionnaire (GFQ), and the Parkinson's Disease Questionnaire (PDQ-39). 5 patients also underwent gait analysis. All patients received stimulation when “on” medication. Results: anodal TDCS compared to the sham significantly improved gait and FOG starting from the first stimulation. The effect was evident up to 1 month from the first treatment. Conclusion: Anodal TDCS of the motor and premotor cortex is safe and it may have therapeutic potential for FOG in patients with PD. TDCS might determine release of dopamine in the caudate and putamen. Alternatively excitation of the less active motor cortex may restore an inter-hemispheric balance, as it has been recently hypothesized as possible mechanism at the origin of FOG.

Background: Dysphagia in the elderly, known as presbydysphagia, has become a relevant public health problem in several countries. Swallowing disorders may be a consequence of different neurological disorders (secondary presbydysphagia) or the expression of the aging process itself (primary presbydysphagia). We aimed to test the therapeutic potential of two different non-invasive brain stimulation (NIBS) techniques in subjects with primary or secondary presbydysphagia. Methods: A blinded randomized controlled trial with crossover design was carried out in 42 patients, randomly assigned to anodal transcranial direct current stimulation (tDCS) or intermittent theta-burst stimulation (TBS) group. Both tDCS and TBS were applied for 5 consecutive days over the right swallowing motor cortex. The swallowing function was assessed before and 1 and 3months after the stimulation using the Dysphagia Outcome and Severity Scale (DOSS), scored based on clinical assessment and fiberoptic endoscopic evaluation of swallowing. An electrophysiological method was also applied to evaluate changes in the reproducibility of the swallowing behavior. Key Results: Both real tDCS and TBS had beneficial effects on the swallowing function in patients with primary and secondary presbydysphagia. Anodal tDCS resulted in an improvement of 0.5 points in DOSS at 1-month follow-up (P=.014), whereas intermittent TBS induced an increase of 0.7 and 0.6 points at 1- and 3-month follow-up evaluations, respectively (P=.0001 and P=.005, respectively). Reproducibility of both the oral and pharyngeal phases of swallowing significantly increased at 1-month follow-up. Conclusions and Inferences: Our results suggest that non-invasive cortical stimulation may be useful for dysphagia recovery in elderly patients.

This dissertation starts from an empirical observation and an intellectual assumption. The former dates from 2013: during a research trip in Burkina Faso I heard and observed humanitarian workers distinguish (in both discourse and practice) between who they thought were 'real refugees' and those who were not, regardless of their legal status. The intellectual assumption is that a category and a label are not only imposed on people designated as such, but are negotiated by the actors themselves and within their interactions with other actors and their social and political economies. Building on these elements, the questions at the centre of this work are: how are hierarchies of refugeeness (re-)produced? And how, when, and why can this (re-) production create or reinforce inequalities among the refugees? I answer these questions by relying on three empirical chapters which focus on different aspects of the construction of refugeeness and the experiences people have and make of 'the refugee' category in the context of Malian forced migration in urban Burkina Faso. More specifically, I look at the encounter of the refugee regime and the refugees' lives through the study of the reproduction, negotiation, and representation of 'the refugee' status and category. What I found and show is how hierarchies of refugeeness can create or reinforce inequalities among the refugees, and how refugeeness, and the possibilities to negotiate with it are unequally produced and distributed, locally but also globally. By unpacking refugeeness through the notion of commodification and relying on ethnographic methods and economic anthropology to study humanitarian interventions, I analyse how the encounter between the refugee regime and the refugees' complex, situated, and varied lives can produce inequalities and is experienced unequally by the refugees themselves.

Objective To investigate electrophysiologically the reproducibility of oropharyngeal swallowing in patients with ALS. Methods We enrolled 26 ALS patients, both with and without clinical signs of dysphagia, and 30 age-matched controls. The reproducibility of the electrophysiological signals related to the oral phase (electromyographic activity of the submental/suprahyoid muscles) and the pharyngeal phase (laryngeal-pharyngeal mechanogram) of swallowing across repeated swallows was assessed. To do this we computed two similarity indexes (SI) by using previously described mathematical algorithms. Results The reproducibility of oropharyngeal swallowing was significantly reduced both in patients with and in those without clinical signs of dysphagia, with more marked alterations being detected in the dysphagic group. The SI of both phases of swallowing, oral and pharyngeal, correlated significantly with dysphagia severity and disease severity. Conclusions In ALS different pathophysiological mechanisms can alter the stereotyped motor behaviors underlying normal swallowing, thus reducing the reproducibility of the swallowing act. A decrease in swallowing reproducibility could be a preclinical sign of dysphagia and, beyond a certain threshold, a pathological hallmark of oropharyngeal dysphagia. Significance Electrophysiological assessment is a simple and useful tool for the early detection of swallowing abnormalities, and for the management of overt dysphagia in ALS.

Electrophysiological assessment provides valuable information on physiological and pathophysiological characteristics of human swallowing. Here, new electrophysiological measures for the evaluation of oropharyngeal swallowing were assessed: (1) the activation pattern of the submental/suprahyoid EMG activity (SHEMG); (2) the reproducibility of the oral and pharyngeal phases of swallowing, by calculating the similarity index (SI) of the SHEMG (SI-SHEMG) and of the laryngeal-pharyngeal mechanogram (SI-LPM) during repeated swallows; and (3) kinesiological measures related to the LPM. An electrophysiological-mechanical method for measuring the activation pattern of the SHEMG, the SI-SHEMG, and the SI-LPM, and maximal LPM velocity and acceleration during swallowing was applied in 65 healthy subjects divided into three age groups (18-39, 40-59, 60 years or over). All the measures were assessed during three trials of eight consecutive swallows of different liquid bolus volumes (3, 12, and 20 ml). A high overall reproducibility of oropharyngeal swallowing in healthy humans was recorded. However, while values of SI-SHEMG were similar in all the age groups, the SI-LPM was found to fall significantly in the older age group. Both the SI-SHEMG and the SI-LPM were found to fall with increasing bolus volumes. The activation pattern of the SHEMG and the LPM kinesiological measures were differently modified by bolus volume and age in the older subjects with respect to the others. We describe a new approach to the electrophysiological study of swallowing based on computed semi-automatic analyses. Our findings provide insight into some previously uninvestigated aspects of oropharyngeal swallowing physiology, considered in relation to bolus volume and age. The new electrophysiological measures here described could prove useful in the clinical setting, as it is likely that they could be differently affected in patients with different kinds of dysphagia.

Background Transcranial direct current stimulation (tDCS) is a non-invasive technique used for modulating cortical excitability in vivo in humans. Here we evaluated the effect of tDCS on behavioral and electrophysiological aspects of physiological sucking and swallowing. Methods Twelve healthy subjects underwent three tDCS sessions (anodal, cathodal and sham stimulation) on separate days in a double-blind randomized order. The active electrode was placed over the right swallowing motor cortex. Repeated sucking and swallowing acts were performed at baseline and at 15 and 60 min after each tDCS session and the mean liquid bolus volume ingested at each time point was measured. We also calculated average values of the following electrophysiological parameters: 1) area and 2) duration of the rectified EMG signal from the suprahyoid/submental muscles related to the sucking and swallowing phases; 3) EMG peak amplitude for the sucking and swallowing phases; 4) area and peak amplitude of the laryngeal-pharyngeal mechanogram; 5) oropharyngeal delay. Results The volume of the ingested bolus significantly increased (by an average of about 30% compared with the baseline value) both at 15 and at 60 min after the end of anodal tDCS. The electrophysiological evaluation after anodal tDCS showed a significant increase in area and duration of the sucking phase-related EMG signal. Conclusions Anodal tDCS leads to stronger sucking of a liquid bolus in healthy subjects, likely by increasing recruitment of cortical areas of the swallowing network. This finding might open up interesting perspectives for the treatment of patients suffering from dysphagia due to various pathological conditions.

The process of extraversion is in the heart of the functioning of the Mauritanian State. In the long lasting, it produced a political and commercial elite which knew how to value the mining and fishing resources of the country. With the stake in exploitation of new resources (oil and gold), the extraversion recently strengthened. The international connections multiply, in particular with the countries of the Gulf, and facilitate businessmen powerful and inserted well into the first circles of the power. The " offshore Mauritania " dominates henceforth on the inside of the country and the society, from which elites disconnect gradually.; Le processus d'extraversion est au cœur du fonctionnement de l'État mauritanien. Dans la longue durée, il a produit une élite politico-commerciale qui a su valoriser les richesses minières et halieutiques du pays. Avec la mise en exploitation de nouvelles ressources (pétrole et or), l'extraversion s'est récemment renforcée. Les connexions internationales se multiplient, en particulier avec les pays du Golfe, et favorisent des hommes d'affaires puissants et bien insérés dans les premiers cercles du pouvoir. La " Mauritanie offshore " prime désormais sur l'intérieur du pays et sur la société, desquels les élites se déconnectent progressivement.

L’Afrique de l’Ouest et ses villes n’echappent pas a la « priorite d’etude » de la migration internationale du fait de commandes publiques de recherche et d’un interet croissant pour les experiences transnationales. L’article examine la survisibilite ainsi conferee aux investissements et aux retours des migrants « de l’exterieur » orientes vers les pays du Nord, tandis qu’est negligee la contribution des migrations internes aux pays et a l’Afrique. Face a ce defaut d’articulation des connaissances, les exemples de Bamako et d’Accra sont mis a profit pour preciser les circulations residentielles croisees, les concurrences d’acces aux ressources, notamment foncieres, et de legitimation politique a l’œuvre dans les villes.