Rozprawy doktorskie na temat „Nucleus and periphery of a field”

In this paper we discuss the diffusionist implications derived from centre-periphery relationships and the establishment of dependency links between western valley and circunpuna societies within the nuclear zone of the central and southern highlands during the Early and Middle Formative periods in northern Chile (1500 BC up to AD 400). By analyzing two complex settlements, Tulán-54 (located 3000 meters above sea level) and Caserones-1 (900 meters above sea level), we have observed that there has been an over-interpretation of foreign contributions in explaining the rise of sedentism that is associated with Formative Period developments. The identification of Archaic and Formative period components at the Tarapacá and Tulán loci supports an autochthonous development, which suggests the rise of local complex societies with early multidirectional links within a framework of highly diversified Formative responses in the Central-South Andean area.<br>En el presente trabajo se discuten las implicancias difusionistas derivadas del enfoque de las relaciones centro-periferia y la tendencia a establecer vínculos de dependencia entre las sociedades de las subáreas de los Valles Occidentales y la Circunpuna respecto de las tierras altas nucleares durante los periodos Formativo Temprano y Medio del norte de Chile (1500 a.C. a 400 d.C.). Mediante el análisis de dos asentamientos complejos, Tulán-54 (3000 metros sobre el nivel del mar) y Caserones-1 (900 metros sobre el nivel del mar), se advierte que ha existido una sobrevaloración de los aportes alóctonos para explicar el surgimiento del sedentarismo asociado a prácticas formativas. La identificación de componentes arcaico-formativos transicionales sustenta la tesis autoctonista, que valoriza, más bien, el surgimiento de tempranas sociedades complejas regionales que establecieron relaciones de interacción paritaria y multidireccional en el área centro-sur andina.

In this Thesis we present a description of α cluster nuclei, in particular focusing on the case of 9 Be, with αn and αα interactions derived from Cluster Effective Field Theory (EFT). The two-body potentials are regularized by a Gaussian cutoff which cures the short-distance dependence of the interaction and the potential parameters are found comparing the effective range expansion (ERE) with the calculated T-matrix. The calculation of the ground-state energies is carried out by diagonalizing the Hamiltonian on a Non symmetryzed Hyperspherical Harmonics basis in momentum space. Using only two body interactions a rather strong cutoff dependence appears. However, we are able to reproduce the experimental ground-state energies for selected cutoff values for most of the studied nuclei. The strong cutoff dependence indicates the lack of three-body forces, therefore we extend our Cluster EFT approach by including such many-body forces. Finally, the 9Be photoabsorption cross-section is studied via the Lorentz integral transform method (LIT), focusing on the low-energy resonances coming from the electric dipole transitions. By fine tuning the parameters of the three-body force, we are able to reproduce, up to 4 MeV, the considered experimental resonances. For the description of the spectrum at higher energies the inclusion of the αα D-wave potential seems to be necessary.

One way in which peripheral vision may acquire the functional role of the fovea, a part of the retina preferentially used for complex visual tasks (such as reading and face recognition) is by modulating the strength of intracortical connections in the humans’ visual areas with perceptual learning. Perceptual learning is a practice-dependent improvement in a visual task performance that can persist for several months, and is specific for stimulus, task, eye presentation and retinal locus of stimulation. These specificity effects have been explained on the basis of neural plasticity, consisting in long-term modifications of a number of mechanisms in the early visual cortices, that are selective for basic stimulus attributes (Karni & Sagi, 1991, 1993; Ahissar & Hochstein, 1993, 1996; Casco & Campana, 2001). Perceptual learning experiments with stimuli involving lateral masking (Polat & Sagi, 1994b, 1995; Polat, Ma-Naim, Belkin & Sagi, 2004) have suggested that practice is able to modulate short- and long-range lateral interactions between neurons responding to collinear elements. These studies showed that contrast thresholds for a target are modulated by the presence collinear flankers, and the type of modulation depends on the distance between the central target and the flankers: inhibitory for short target-to-flankers distance, and facilitatory for longer distances. With the training the suppression from the short target-flanker separation can be reduced and facilitation at relatively long target-flanker separation increases. These studies suggest that practice on lateral interactions increases the efficacy of the collinear interactions between neighbouring neurons, an effect that enhances connectivity with remote neurons via a cascade of local interactions. Most importantly, perceptual learning on lateral interactions has been showed to be useful for improving contrast sensitivity in people with normal low vision (Tan & Fong, 2008; Polat, 2009) or with impaired lateral interactions such as amblyopia (Polat et al., 2004). Notably, these studies showed that, differently from previous perceptual learning experiments where non transfer of learning to different stimulus attributes was observed, the effect of training on lateral interactions transferred to higher level visual tasks, like visual acuity (VA) (Tan & Fong, 2008) producing a long-lasting perceptual benefit in everyday visual tasks. However, in all these studies stimuli were presented in the fovea. This thesis aimed at investigating the possibility that the effect of training also improves lateral interaction in retinal regions eccentric with respect to the fovea. Lateral interactions strongly depend on eccentricity: in the periphery they are mostly inhibitory (Petrov, Carandini & McKee, 2005; Cavanaugh et al., 2002). These evidence leads to the hypothesis that peripheral vision may acquire some of the functional role of the fovea only if inhibition is reduced. Shani & Sagi (2005) showed that collinear facilitation in the near-periphery is weak and that perceptual learning seems not to be effective in modulating lateral interactions. However, in their study the training was very short, and only one target-to-flanker distance was tested. If lateral interactions could be modulated in the near periphery, and transfer to visual tasks such as VA and crowding was possible, this could be extremely important for rehabilitation of individuals with loss of central vision, such as in macular degeneration. These type of patients, after the loss of central vision, are forced to use the periphery of the visual field for the most demanding visual tasks like face recognition and reading. In Experiment 1, we were interested in verifying whether inhibitory lateral interactions in the near-periphery (4 degrees of eccentricity) may be reduced by training and if training transfers to other visual functions. Eight subjects were trained with different spatial frequencies (1, 2, 4, and 8 cycles per degree - cpd) and different target-to-flankers separations (2, 3, 4, and 8). Before the practice sessions subjects performed a series of pre-tests aimed at measuring their peripheral contrast sensitivity function (CSF), peripheral visual acuity (VA) and crowding effect. Consistently with previous studies (Petrov et al., 2005; Cavanagh et al., 2002), results of the Experiment 1 showed that, in the near periphery, lateral interactions are inhibitory even at target-to-flanker distances (4) where facilitatory interactions are found in central vision. Facilitation was reported for a target-to-flankers distance of 8, consistently with the most recent investigation on peripheral lateral interactions (Lev & Polat, 2011). Most importantly, Experiment 1 showed that lateral interactions in parafoveal vision can be modulated by training, reducing the inhibition, and that perceptual learning transfers to other visual abilities, leading to a reduction of crowding. Since learning specificity is viewed as the main indicator of the level of processing at which learning takes place, and since learning of lateral interaction has been shown to transfer to different visual functions, in Experiment 2 we tested the specificity of learning to basic stimulus features such as target-flankers local and global orientation and retinal position. We trained 4 new subjects in contrast detection of a collinearly flanked vertical target, and found a significant learning effect for the trained configuration but no transfer of learning to either the same stimulus presented in a symmetrical retinal location, nor to a 45 deg oriented collinear target-flankers configuration, presented in the same retinal position as the learning stimulus. The finding that these transfer stimuli are immune to perceptual learning of vertical orientations strongly suggests that the modulation of lateral interactions through perceptual learning is functionally specific, and that transfer to different visual functions can only occur when these are based on the specific early mechanism that is learned. In Experiment 3, we aimed at exploiting the effects of the perceptual learning of lateral interactions for improving peripheral vision in patients affected by macular degeneration. Training consisted in a contrast detection of a Gabor target with collinear high contrast Gabor flankers, at different target-to-flankers separations, located in their preferential retinal locus (PRL, the new fixation point that spontaneously emeges in this type of patients) and in a symmetrical location. The rationale behind the measuring or lateral interactions and the training in the PRL and in another retinal location was to point out possible differences in intracortical connectivity for this new fixation point respect to other retinal spots. Consistently with other studies (Dilks, Baker, Peli and Kanwisher, 2009), we did not find major differences in terms of lateral interactions and perceptual learning effects between PRL and the symmetrical locus. Training increased contrast sensitivity, and, despite not having any effect on crowding, improved visual acuity in the maculopathy subjects. The absence of crowding reduction could be due to a “roof effect”, since this type of patients naturally train their peripheral view, probably reaching their maximal performance even before the training.. Nevertheless, the improvement of visual acuity opens new perspectives for the rehabilitation of patients with macular degeneration, but also for improving peripheral vision in normal-sighted subjects, since recent studies showed the important role of the periphery of the visual field in tasks such as postural stability, locomotion and driving. In Experiment 4, we investigated the architecture of peripheral lateral interactions in a maculopathy patients, finding collinear facilitation at shorter target-to-flankers separation respect to normal-sighted subjects. Interestingly, collinear facilitation was reported for target presentation in the PRL but not in the No-PRL, where collinear interactions were only inhibitory. Moreover, perceptual learning training appeared to be effective in modulating lateral interactions only in the PRL, questioning the hypothesis of a “use-dependent” cortical reorganization, supported, among the others, by Dilks et al. (2009).<br>Un modo in cui la visione periferica può acquisire il ruolo funzionale della fovea, la parte della retina preferenzialmente utilizzata per compiti visivi complessi (come la lettura e il riconoscimento dei volti) è tramite la modulazione della forza delle connessioni intracorticali presenti nelle aree visive umane tramite apprendimento percettivo. L’apprendimento percettivo è un miglioramento della prestazione n un compito visivo in seguito alla pratica, può mantenersi per diversi mesi ed è specifico per lo stimolo, il computo e l’occhio utilizzato nel training e per il locus retinico in cui è avvenuta la stimolazione. Questi effetti di specificità sono stati spiegati sulla base della plasticità neurale, che consiste in una modifica a lungo termine di alcuni meccanismi presenti nelle prime aree visive corticali, selettive per caratteristiche basilari dello stimolo (Karni & Sagi, 1991, 1993; Ahissar & Hochstein, 1993, 1996; Casco & Campana, 2001). Esperimenti di apprendimento percettivo con stimoli di mascheramento laterale (Polat & Sagi, 1994b, 1995; Polat, Ma-Naim, Belkin & Sagi, 2004) hanno dimostrato che la pratica può modulare interazioni laterali a breve e lungo raggio tra neuroni che rispondono ad elementi collineari. Questi studi mostrano che le soglie di contrasto per un target centrale sono modulate dalla presenza di elementi vicini, orientati col linearmente, e che il tipo di modulazione dipende dalla distanza tra il target centrale e gli elementi vicini (flankers): inibitoria per brevi distanze tra target e flankers, facilitatoria per distanze maggiori. Con la pratica, l’inibizione per le brevi distanze target-flankers può essere ridotta e la facilitazione a maggiori distanze aumenta. Questi studi suggeriscono che la pratica sulle interazioni laterale può aumentare l’efficacia delle interazioni collineari tra neuroni vicini, un effetto che aumenta la connettività con neuroni più lontani in seguito ad una cascata di interazioni locali. Inoltre, è stato dimostrato che l’applicazione dell’apprendimento percettivo sulle interazioni laterali produce risultati effettivi nel miglioramento della sensibilità al contrasto in individui con miopia (Tan & Fong, 2008; Polat, 2009) o con interazioni laterali abnormali, come nel caso dell’ambliopia (Polat et al., 2004). Questi studi dimostrano che, a differenza dai precedenti esperimenti sull’apprendimento percettivo che non riportavano il trasferimento del miglioramento ad altri compiti, l’effetto della pratica sulle interazioni laterali si trasferisce ad abilità visive di più alto livello, come l’acuità visiva (Tan & Fong, 2008), dando luogo a benefici percettivi a lungo termine nella quotidianità di questi soggetti. Tuttavia, negli studi finora condotti, gli stimoli venivano presentati in fovea. In questa tesi, l’obiettivo è stato quello di studiare la possibilità che gli effetti del training possano migliorare le interazioni laterali in regioni retiniche periferiche rispetto alla fovea. Le interazioni laterali dipendono fortemente dall’eccentricità: nella periferia del campo visivo sono principalmente inibitorie (Petrov, Carandini & McKee, 2005; Cavanaugh et al., 2002). Questa evidenza porta ad ipotizzare che la visione periferica possa acquisire il ruolo funzionale della fovea solo se l’inibizione viene ridotta. Shani & Sagi (2005) hanno dimostrato che la facilitazione collineare nella periferia del campo visivo è debole e che l’apprendimento percettivo non sembra efficace nel modulare le interazioni laterali. Tuttavia, nel loro studio il periodo di pratica era molto breve, in più le distanze target-flankers testate erano ridotte. Se le interazioni laterali possono essere modulate nella periferia del campo visivo, e trasferire il miglioramento ad abilità visive come l’acuità visiva o il crowding (affollamento visivo), questo risultato sarebbe estremamente importante per la riabilitazione di individui con perdita della visione centrale, come nel caso della maculopatia. Questo tipo di pazienti, dopo la perdita della visione centrale, sono obbligati ad usare la periferia del campo visivo per i compiti visivi più complessi, come la lettura ed il riconoscimento dei volti. Nell’Esperimento 1, l’obiettivo era verificare se le interazioni laterali inibitorie nella periferia del campo visivo (4 gradi di eccentricità) potevano essere ridotte dall’apprendimento e se l’eventualmente miglioramento si trasferiva ad altre funzioni visive. I soggetti sono stati allenati con diverse frequenze spaziali (1, 2, 4, and 8 cicli per grado) e diverse distanze target-flankers (2, 3, 4 e 8). Prima delle sessioni di pratica, ai soggetti venivano misurate le prestazioni di base in una serie di compiti visivi, come la sensibilità al contrasto periferica (CSF), l’acuità visiva periferica (VA) e l’effetto di crowding (affollamento visivo).Coerentemente con studi precedenti (Petrov et al., 2005; Cavanagh et al., 2002), i risultati dell’Esperimento 1mostrano che, nella periferia del campo visivo, le interazioni laterali sono inibitorie anche a distanze target-flankers che producono facilitazione in visione centrale (4). La distanza alla quale è stata trovata la facilitazione in periferia (8), è coerente coi più recenti studi sulle interazioni laterali nella periferia del campo visivo (Lev & Polat, 2011). Soprattutto, l’Esperimento 1 mostra che le interazioni laterali in parafovea possono essere modulate dalla pratica, riducendo l’inibizione, e che l’apprendimento percettivo trasferisce il miglioramento ad altre abilità visive, portando alla riduzione del fenomeno di affollamento visivo (crowding). Dato che la specificità dell’apprendimento è considerata l’indicatore principale del livello di processamento dell’informazione in entrata a cui l’apprendimento si verifica, nell’Esperimento 2 abbiamo testato la specificità dell’apprendimento per caratteristiche base dello stimolo come l’orientamento locale e globale degli elementi utilizzati durante il training e la loro posizione spaziale. Un nuovo gruppo di soggetti è stato allenato in un compito di detezione del contrasto per uno stimolo centrale affiancato da elementi collineari, mostrano un effetto di apprendimento significativo per la configurazione allenata, ma non riportando alcun trasferimento per lo stesso stimolo presentato in una posizione retinica simmetrica, né per configurazioni con orientamento locale (tra gli elementi) o globale differente. L’evidenza che questi stimoli sono immuni all’apprendimento percettivo suggerisce in maniera decisa che la modulazione delle interazioni laterali tramite apprendimento percettivo sia specifica per la funzione, e che il trasferimento a diverse funzioni visive può avere luogo solo quando queste sono basate su specifici meccanismi precoci. Nell’Esperimento 3, abbiamo testato la possibilità di utilizzare gli effetti dell’apprendimento percettivo delle interazioni laterali per migliorare la vision periferica in pazienti affetti da degenerazione maculare. Il training consisteva in un compito di detezione del contrasto per uno stimolo centrale affiancato da elementi collineari, collocati a diverse distanze target-flankers, presentati nel locus retinico preferenziale (PRL, il nuovo punto di fissazione che spontaneamente questi pazienti sviluppano) ed in una posizione simmetrica. L’idea alla base della misurazione delle interazioni laterali e dell’apprendimento nel PRL ed in un’altra posizione retinica era di verificare se vi siano differenze nella connettività intracorticale tra il nuovo punto di fissazione periferico ed un altro locus retinico. Coerentemente con altri studi ((Dilks, Baker, Peli and Kanwisher, 2009), non abbiamo riscontrato evidenti differenze in termini di interazioni laterali ed effetti di apprendimento percettivo tra PRL e il locus retinico simmetrico.Il training ha migliorato la sensibilità al contrasto e, pur non avendo avuto effetto sul crowding, ha migliorato l’acuità visiva nei soggetti maculopatici. L’assenza di riduzione del crowding può essere dovuta ad un “effetto tetto”, dato che questo tipo di pazienti allenano “naturalmente”, nella quotidianità, la loro visione periferica, e probabilmente hanno raggiunto la massima prestazione possibile nella visione periferica prima di iniziare il training. Nondimeno, il miglioramento nell’acuità visiva apre nuove prospettive per la riabilitazione di pazienti con maculopatia, ma anche per migliorare la visione periferica in soggetti normovedenti, dato che studi recenti hanno mostrato l’importante ruolo della periferia del campo visivo in attività come la stabilità posturale, la locomozione e la guida. Nell’Esperimento 4, abbiamo studiato l’architettura delle interazioni laterali periferiche in un soggetto maculopatico, trovando facilitazione collineare a distanze target-flankers minori rispetto ai soggetti normovedenti. Il dato interessante è che la facilitazione collineare emerge solo per la presentazione del target nel PRL, mentre nel PRL le interazioni collineari sono solo inibitorie. Inoltre, l’apprendimento percettivo sembra efficace nel modulare le interazioni laterali solo nel PRL, mettendo in discussione l’ipotesi “uso-dipendente” per la riorganizzazione corticale, supportata, tra gli altri, da Dilks et al. (2009).

La maladie d’Alzheimer touche plus de 40 millions de personnes dans le monde et résulte de l’agrégation du peptide beta-amyloïde de 40/42 résidus. En dépit de nombreuses études expérimentales et théoriques, le mécanisme de formation des fibres et des plaques n’est pas élucidé, et les structures des espèces les plus toxiques restent à déterminer. Dans cette thèse, je me suis intéressée à deux aspects. (1) La détermination du noyau de nucléation (N*) de deux fragments (Aβ)16-22 et (Aβ)37-42. Mon approche consiste à déterminer les paramètres OPEP du dimère (Aβ)16-22 en comparant des simulations Monte Carlo sur réseau et des dynamiques moléculaires atomiques par échange de répliques. Les paramètres fonctionnant aussi sur le trimère (Aβ)16-22 et les dimères et trimères (Aβ)37-42, j’ai étudié la surface d’énergie libre des décamères et mes simulations montrent que N* est de 10 chaines pour (Aβ)16-22 et est supérieure à 20 chaines pour (Aβ)37-42. (2) J’ai ensuite étudié les structures du dimère (Aβ)1-40 par simulations de dynamique moléculaire atomistique par échanges de répliques. Cette étude, qui fournit les conformations d’équilibre du dimère Aβ1-40 en solution aqueuse, ouvre des perspectives pour une compréhension de l’impact des mutations pathogènes et protectrices au niveau moléculaire<br>The neurodegenerative Alzheimer's disease (AD) is affecting more than 40 million people worldwide and is linked to the aggregation of the amyloid-β proteins of 40/42 amino acids. Despite many experimental and theoretical studies, the mechanism by which amyloid fibrils form and the 3D structures of the early toxic species in aqueous solution remain to be determined. In this thesis, I studied the structures of the eraly formed oligomers of the amyloid-β peptide and the critical nucleus size of two amyloid-β peptide fragments using either coarse-grained or all-atom simulations. First, at the coarse-grained level, I developed a lattice model for amyloid protein, which allows us to study the nucleus sizes of two experimentally well-characterized peptide fragments (Aβ)16-22 and (Aβ)37-42 of the Alzheimer's peptide (Aβ)1-42. After presenting a comprehensive OPEP force-field parameterization using an on-lattice protein model with Monte Carlo simulations and atomistic simulations, I determined the nucleus sizes of the two fragments. My results show that the nucleation number is 10 chains for (Aβ)16-22 and larger than 20 chains for (Aβ)37-42. This knowledge is important to help design more effective drugs against AD. Second, I investigated the structures of the dimer (Aβ)1-40 using extensive atomistic REMD simulations. This study provides insights into the equilibrium structure of the (Aβ)1-40 dimer in aqueous solution, opening a new avenue for a comprehensive understanding of the impact of pathogenic and protective mutations in early-stage Alzheimer’s disease on a molecular level

La stimolazione cerebrale profonda (DBS) è una tecnica utilizzata in clinica per trattare alcune patologie come la malattia di Parkinson (PD) tramite un rilascio locale di corrente alternata ad alta frequenza (> 100 Hz), grazie all’utilizzo di elettrodi impiantati nei gangli della base durante una procedura di chirurgia stereotassica. Negli ultimi anni indagini neurofisiologiche svolte con la DBS hanno inoltre consentito la scoperta di potenziali marcatori neurali caratteristici del PD e il loro utilizzo per una stimolazione definita adattativa (aDBS) in cui l’ampiezza dello stimolo in tensione viene controllato dallo stato attuale del paziente. Una versione di aDBS è stata sviluppata da Newronika s.r.l. che è riuscita a implementare un algoritmo closed-loop basato sulla potenza delle oscillazioni beta come variabile di controllo del voltaggio della DBS. Numerosi studi con la aDBS sono stati effettuati prima su pazienti con PD a riposo e poi durante alcuni task di vita quotidiana come il cammino. Durante questi test è emerso che la aDBS non riusciva a performare bene durante l’attività di cammino per la presenza di artefatti a bassa frequenza (1-8 Hz) sul segnale LFP causati principalmente dal contatto del tallone sul terreno all’inizio della fase di stance del passo. Lo scopo di questa tesi è stato quello di proporre un algoritmo innovativo basato sulla Empirical Mode Decomposition per la rimozione di tale artefatto senza inficiare la performance della aDBS. L’algoritmo basato sulla EMD è stato capace di eliminare il rumore in maniera efficace, rimuovendo potenza spettrale non utile nella banda dell’artefatto e mantenendo intatto il contenuto in beta (fondamentale per la riuscita della aDBS). Inoltre, in questo lavoro è stata proposta un’implementazione real-time dell’algoritmo di pulizia del segnale nello stesso microcontrollore (MSP430FR5969) usato nel dispositivo AlphaDBS V-Imp di Newronika con la prospettiva di poter esser integrato in quest’ultimo in futuro.

Microscopy image processing is an emerging and quickly growing field in medical imaging research area. Recent advancements in technology including higher computation power, larger and cheaper storage modules, and more efficient and faster data acquisition devices such as whole-slide imaging scanners contributed to the recent microscopy image processing research advancement. Most of the methods in this research area either focus on automatically process images and make it easier for pathologists to direct their focus on the important regions in the image, or they aim to automate the whole job of experts including processing and classifying images or tissues that leads to disease diagnosis. This dissertation is consisted of four different frameworks to process microscopy images. All of them include methods for segmentation either as the whole suggested framework or the initial part of the framework for future feature extraction and classification. Specifically, the first proposed framework is a general segmentation method that works on histology images from different tissues and segments relatively solid nuclei in the image, and the next three frameworks work on cervical microscopy images, segmenting cervical nuclei/cells. Two of these frameworks focus on cervical tissue segmentation and classification using histology images and the last framework is a comprehensive segmentation framework that segments overlapping cervical cells in cervical cytology Pap smear images. One of the several commonalities among these frameworks is that they all work at the region level and use different region features to segment regions and later either expand, split or refine the segmented regions to produce the final segmentation output. Moreover, all proposed frameworks work relatively much faster than other methods on the same datasets. Finally, proving ground truth for datasets to be used in the training phase of microscopy image processing algorithms is relatively time-consuming, complicated and costly. Therefore, I designed the frameworks in such a way that they set most (if not all) of the parameters adaptively based on each image that is being processed at the time. All of the included frameworks either do not depend on training datasets at all (first three of the four discussed frameworks) or need very small training datasets to learn or set a few parameters.

This Minor Field Study was carried out during November and December in 2011 in the Mount Elgon District in Western Kenya. The objective was to examine nine small-scale farming household´s land use and socioeconomic situation when they have joined a non-governmental organization (NGO) project, which specifically targets small-scale farming households to improve land use system and socioeconomic situation by the extension of soil and water conservation measures. The survey has worked along three integral examinations methods which are mapping and processing data using GIS, semi structured interviews and literature studies.   This study has adopted a theoretical approach referred to as political ecology, in which landesque capital is a central concept. The result shows that all farmers, except one, have issues with land degradation. However, the extent of the problem and also implemented sustainable soil and water conservation measures were diverse among the farmers. The main causes of this can both be linked to how the farmers themselves utilized their farmland and how impacts from the climate change have modified the terms of the farmers working conditions. These factors have consequently resulted in impacts on the informants’ socioeconomic conditions. Furthermore it was also registered that social and economic elements, in some cases, were the causes of how the farmers manage their farmland. The farmer who had no significant problem with soil erosion had invested in trees and opportunities to irrigate the farmland. In addition, it was also recorded that certain farmers had invested in particular soil and water conservation measures without any significant result. This was probably due to the time span these land measures cover before they start to generate revenue.  The outcome of this study has traced how global, national and local elements exist in a context when it comes to the conditions of the farmers´ land use and their socioeconomic situation. The farmers atMt.Elgon are thereby a component of a wider context when they are both contributory to their socioeconomic situation, mainly due to their land management, and also exposed to core-periphery relationships on which the farmers themselves have no influence.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and DBS of the pedunculopontine nucleus (PPN) have been shown to be effective surgical therapies for Parkinson’s disease (PD). To better understand the PPN and STN as DBS targets for PD, this research compares the anatomy, electrophysiology, and motor control roles of these nuclei. PPN and STN connections were examined in vivo in human subjects and in the non-human primate using probabilistic diffusion tractography. Both the PPN and STN were connected with each other and with the motor cortex (M1) and basal ganglia. After studying these anatomical connections in primates, their functional significance was further explored in an anesthetized rat model of PD. Examination of the electrophysiological relationship between the PPN and basal ganglia in the presence of slow cortical oscillatory activity suggested that excitatory input from the STN may normally modulate PPN spike timing but that inhibitory oscillatory input from the basal ganglia output nuclei has a greater effect on PPN spike timing in the parkinsonian brain. To examine transmission and modulation of oscillatory activity between these structures at higher frequencies, LFP activity was recorded from the PPN and STN in PD patients performing simple voluntary movements. Movement-related modulation of oscillatory activity predominantly occurred in the α (8-12 Hz) and low β (12-20 Hz) frequencies in the STN but in the high β (20-35 Hz) frequencies in the PPN, supporting observations from rodent studies suggesting that oscillatory activity is not directly transmitted from the STN to the PPN in PD. Finally, to better understand the roles of the STN and PPN in large-scale movement, the effects of STN and PPN DBS on gait abnormalities in PD patients were studied. DBS of the STN appeared to improve gait by optimising executive gait control while DBS of the PPN appeared to restore autonomic gait control. These results have several implications for DBS patient selection, surgical targeting, and for understanding the mechanisms underlying DBS efficacy.

L’interaction spin-orbite a permis de reproduire dans les modèles nucléaires théoriques, les nombres magiques N=28 et 50 observés dans les noyaux atomiques. Ces dernières décennies, l’étude expérimentale de noyaux exotiques a mis en évidence une évolution des nombres magiques loin de la vallée de stabilité. On peut alors se poser la question de l’évolution des potentiels d’interaction eux-mêmes, et en particulier de l’interaction spin-orbite. Si cette interaction a été historiquement incluse « à la main » dans les modèles de champ moyen « classiques », elle émerge cependant naturellement dans les modèles relativistes. La description de l’interaction spin-orbite est très similaire dans ces deux types de modèles, mais il subsiste a priori un désaccord du point de vue de sa dépendance en isospin : les modèles non-relativistes de type Hartree-Fock présentent en effet un potentiel spin-orbite dépendant fortement de l’isospin, contrairement aux modèles de type Relativistic Mean Field.En 2009, des calculs mettant en œuvre différents modèles théoriques ont prédit l’existence d’une « bulle », caractérisée par une déplétion en densité protonique centrale, dans le ³⁴Si. Ce dernier aurait une densité protonique très exotique, et bien différente de sa densité neutronique. Le ³⁴Si constituerait alors une sonde idéale de l’évolution du potentiel spin-orbite dans les systèmes présentant une forte asymétrie protons-neutrons. L’émergence d’un tel effet trouverait son origine dans la déplétion de l’orbitale protonique2s½, les orbitales s étant les seules à contribuer à la densité nucléaire centrale.Une expérience réalisée en Septembre 2012 à NSCL (MSU, Etats-Unis), a permis de mettre en évidence pour la première fois un effet de bulle nucléaire dans le ³⁴Si. L’étude des facteurs spectroscopiques des états peuplés lors des réactions d’arrachage de proton ou de neutron ³⁴Si(-1p) ³³Al et ³⁴Si(-1n) ³³Si indique que sa structure neutronique est très proche d’un système sans corrélations au-delà du champ moyen, tandis que son orbitale protonique est très faiblement occupée : n(2s½) = 0,16(4).Les réactions ³⁶S(-1p) ³⁵P et ³⁶S(-1n) ³⁵S ont été étudiées dans les mêmes conditions expérimentales. L’évolution de l’occupation n(2s½) mesurée entre le ³⁶S et le ³⁴Si, ainsi que la variation de l’écart en énergie des partenaires spin-orbite neutroniques 2p½-2p^3/2, mesurée entre ces deux noyaux dans une expérience antérieure, sont en faveur des modèles de champ moyen non-relativistes. La partie théorique de cette thèse a cependant montré que la différence de comportement de l’interaction spin-orbite entre modèles relativistes et non-relativistes est en fait un artefact causé par l’omission du terme d’échange dans les calculs de type Relativistic Mean Field. En effet, l’inclusion du terme de Fock dans les modèles relativistes permet de rétablir la dépendance en isospin du potentiel spin-orbite observée dans le cas non-relativiste<br>The spin-orbit interaction is essential for the reproduction of magic numbers N=28 and 50 in theoretical nuclear models. Over the past few decades, the experimental study of exotic nuclei has highlighted an evolution of magic numbers far from stability. One can then wonder about the evolution of nuclear potentials themselves, and in particular the one of spin-orbit interaction. Historically, this interaction was included « by hand » in mean field models, whereas it naturally arises in relativistic mean field models. The description of the spin-orbit interaction happens to be very similar in those two kinds of models, but there remains a disagreement regarding its isospin dependance. Indeed, Hartree-Fock models exhibit a spin-orbit potential which strongly depends on isospin, contrary to relativistic mean field models.In 2009, a proton bubble was predicted in ³⁴Si by means of several different nuclear models. This effect consists in a central proton central density depletion. ³⁴Si would exhibit a quite exotic proton density, and very different from its neutron density. This nucleus would then constitute an ideal probe to test the behaviour of the spin-orbit potential in systems with strong proton-neutron asymmetry. The appearance of such an effect would originate from the depletion of proton 2s½ orbitals, as s orbitals are the only ones contributing to the central density.An experiment which was performed in September 2012 at NSCL (MSU, United States) highlighted for the first time a proton bubble in ³⁴Si. The spectroscopic strengths of states populated in the knockout reactions ³⁴Si(-1p)³³Al and ³⁴Si(-1n)³³Si reveal that the neutron structure of ³⁴Si is close to the one of a system without beyond-mean-field correlations, whereas its proton orbital is only weakly occupied : n(2s½) = 0,16(4).The reactions ³⁶S(-1p)³⁵P and ³⁶S(-1n)³⁵S were studied in similar experimental conditions. The change in occupancy n(2s½) measured between ³⁶S and ³⁴Si, as well as the variation in the neutron spin-orbit splitting 2p½-2p^3/2 measured in an earlier experiment, suggest that non-relativistic models exhibit the right isospin dependance. The theoretical part of this thesis showed however that the difference in behaviour of the spin-orbit interaction between relativistic and non-relativistic model is actually an artefact caused by the omission of the exchange term in relativistic mean field calculations. Indeed, including the Fock term in relativistic models enables to restore the isospin dependance observed in the non-relativistic case

Дана робота присвячена визначенню поняття лексико-семантичного поля, встановленню його структури, комплексному дослідженню поля, зокрема у семантичному, парадигматичному та структурному аспектах.<br>Данная работа посвящена определению понятия лексико-семантического поля, установлению его структуры, комплексному исследованию поля в семантическом, парадигматическом и структурном аспектах.<br>The paper deals with the determination of the structure of the lexical-semantic field, its complex study, particularly in the semantic, paradigmatic and structural aspects.

Par sa connectivité directe avec le cortex, le noyau subthalamique (NST) représente une des structures d'entrée du système des ganglions de la base, et se trouve impliqué dans différents aspects du comportement (contrôle moteur, cognitif et limbique). Néanmoins, les corrélats électrophysiologiques de ces processus restent débattus. Les études effectuées dans le cadre de cette thèse visent à éclaircir le rôle possible du NST dans trois fonctions exécutives, à savoir l'inhibition réactive (suppression d'un mouvement programmé), l'inhibition proactive (préparation à inhiber son mouvement) et l'attention soutenue. Pour ce faire, les activités extracellulaires et/ou en potentiels de champs locaux du NST ont été enregistrées chez 28 patients parkinsoniens pendant qu'ils effectuaient des taches cognitives, visant à dissocier les corrélats de ces différentes fonctions exécutives. Dans une première étude, les activités en potentiel de champs locaux du NST lors de l'inhibition réactive et proactive ont été étudiées à l'aide d'un paradigme modifié du « stop signal ». L'inhibition réactive se caractérise par une augmentation rapide de synchronisation relative de l'activité du NST dans la bande de fréquence β (13-35 Hz), tandis que l'inhibition proactive se caractérise par la maintenance tonique d'un niveau élevé d'activité β qui prédit les performances des patients lors de l'inhibition réactive. Dans la seconde étude, nous avons montré qu'une population neuronale (n=7 neurones) augmente rapidement sa fréquence de décharge lors de l'inhibition réactive. Enfin, dans la troisième étude, nous avons utilisé un paradigme permettant de moduler le niveau attentionnel requis pour réaliser un comportement simple. Nos résultats indiquent qu'une baisse d'activité β est observée uniquement lorsque le sujet maintient une attention soutenue pour encoder, retrouver en mémoire une information afin de produire une réponse. L'ensemble de ces résultats nous ont permis d'apporter des preuves électrophysiologiques de l'implication du NST dans ces différentes fonctions et de clarifier la dynamique temporelle des activités neuronales supportant ces processus. Ils suggèrent ainsi l'hypothèse d'une implémentation de différents aspects du contrôle exécutif dans le NST via des mécanismes communs et interactifs dont la dynamique temporelle permettrait la modulation fine du comportement<br>The subthalamic nucleus (STN) is an input structure of the basal ganglia implicated in many behavioral processes (motor, cognitive and limbic control). However the electrophysiological correlates of these processes remain unclear. This thesis aims to clarify the role of the STN during 3 executive functions: reactive inhibition (suppression of a prepotent move), proactive inhibition (preparation to inhibit a move) and sustained attention. To this end, extracellular and local field potential activities were recorded in 28 patients with Parkinson's disease while they performed cognitive tasks, aiming to dissociate the neural correlates of these executive functions In a first study, local field potentials β (13-35 Hz) activity was recorded in the STN during reactive and proactive inhibition. Reactive Inhibition was related to a relative increase of β activity, while proactive inhibition was related to maintenance of a tonic level of β activity predictive of reactive inhibitory performances. In a second study, we showed that reactive inhibition is related to a phasic increase of firing rate in a neuronal subpopulation (n=7 neurons). In a third study, we recorded Local field potentials in the STN while patients performed a sustained attention-demanding task (combining a visual search and a delayed match-to-sample paradigm) and found a systematic suppression of 15-35 Hz activity during each repetition of the task directly related to the amount of attention allocated by the participants. Altogether, these results present electrophysiological evidences of the implication of the STN in these functions and clarify the temporal dynamics of neuronal activities supporting these processes. These results may suggest an implementation of various executive functions in the STN via common and interactive mechanisms which temporal dynamics would mediate behavioral control

Les excitations d'échange de charge dans les noyaux constituent l'un des sujets importants et actuels en physique nucléaire et en astrophysique. En principe, une connaissance systématique de l'évolution du comportement de ces excitations à travers la table des éléments fournirait des informations directes sur les propriétés en spin et isospin de l'interaction entre nucléons dans le milieu nucléaire, et sur l'équation d'état de la matière nucléaire. Par ailleurs, une quantité d'importance essentielle pour la structure des noyaux, l'épaisseur de la peau de neutrons, peut être déterminée par la règle de somme de la résonance spin-dipolaire (RSD) ou par la séparation en énergie entre l'état isobarique analogue (ElA) et la résonance de Gamow-Teller (RGT). Plus généralement, les excitations d'échange de charge permettent d'aborder des probèmes d'inérêt général tels que l'étude de l'évolution des étoiles à neutrons et des supernovae, la décroissance des noyaux le long du processus r dans la nucléosynthèse stellaire, ou les interactions neutrino-noyau. Elles jouent aussi un rôle essentiel pour extraire la valeur de l'élément Vud de la matrice de Cabibbo-Kobayashi-Maskawa par le biais de la réaction de décroissance β super-permise 0 +→ 0+ dans les noyaux. Pour toutes ces raisons, il est important de d'evelopper des théories microscopiques des excitations d'échange de charge, et ceci constitue la principale motivation de notre recherche. Dans ce travail, nous établissons le formalisme et les méthodes numériques pour d' ecrire les excitations d'échange de charge dans le cadre de la Random Phase Approximation (RPA) self-consistante construite sur l'approximation de Hartree-Fock relativiste (RHF). Un test important de précision numérique est réalisé sur l'état isobarique analogue. La méthode est ensuite utilisée pour mener des applications numériques réalistes sur un certain nombre de questions physiques : les résonances de spin-isospin dans les noyaux proches des noyaux magiques, les corrections dûes aux mélanges d'isospin dans les transitions β super-permises, les interactions neutrino-noyau dans les voies de courants chargés. Pour les deux modes importants de spin-isospin que sont la RGT et la RSD nous trouvons qu'un excellent accord avec l'expérience est obtenu sans aucun réajustement des paramètres du modèle. De plus, les termes d'échange de l'interaction induite par les mésons isoscalaires jouent un rôle essentiel dans les excitations de spin-isospin, à la différence de la RPA construite sur l'approximation de Hartree relativiste. En ce qui concerne notre étude des transitions β 0+ → 0+ super-permises, l'une des conclusions est que les corrections δc dues aux violations de la symétrie d'isospin dépendent sensiblement du champ moyen d'échange produit par les interactions coulombiennes, mais ne changent pas sensiblement avec le modèle de Lagrangien utilisé. Nous utilisons ces valeurs de δc pour déduire des plus récentes valeurs expérimentales de ft dans les noyaux T = 1, et en tenant compte des corrections radiatives, les valeurs de Ft "indépendantes de noyaux". Nous obtenons ainsi des valeurs de l'élément de matrice ıVudı de Cabbibo-Kobayashi-Maskawa en bon accord avec les valeurs déduites des décroissances neutronique et pionique, et les transitions dans les noyaux miroirs, tandis que la somme des carrés des éléments de la première ligne dévie légèrement de la condition d'unitarité. Nous avons également utilisé nos fonctions d'onde RPA pour évaluer les amplitudes de transition correspondant à l'interaction faible lepton-hadron sous la forme standard courant-courant. Ainsi, les processus faibles semi-leptoniques tels que les réactions neutrino-noyau, capture leptonique chargée, désintégration β , peuvent être étudiés. Nos premières applications concernent la réaction 16 O(Ve , e - ) 16 F pour laquelle nous comparons nos prédictions avec celles d'autres auteurs. Dans la discussion des résultats nous nous efforçons en particulier de clarifier l'influence appréciable des différentes prescriptions que l'on peut adopter pour le choix de la constante de couplage vecteur axiale et l'inclusion ou non des états excités de basse énergie dans le noyau final<br>Nowadays, charge-exchange excitations in nuclei become one of the central topics in nuclear physics and astrophysics. Basically, a systematic pattern of the energy and collectivity of these excitations could provide direct information on the spin and isospin properties of the in-medium nuclear interaction, and the equation of state of asymmetric nuclear matter. Furthermore, a basic and critical quantity in nuclear structure, neutron skin thickness, can be determined indirectly by the sum rule of spin-dipole resonances (SOR) or the excitation energy spacing between the isobaric analog states (lAS) and Gamow-Teller resonances (GTR). More generally, charge-exchange excitations allow one to attack other kinds of problems outside the realm of nuclear structure, like the description of neutron star and supernova evolutions, the β-decay of nuclei which lie on the r-process path of stellar nucleosynthesis, and the neutrino-nucleus cross sections. They also play an essential role in extracting the value of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vud via the nuclear 0+→ 0 + superallowed Fermi β decays. For all these reasons, it is important to develop the microscopic theories of charge-exchange excitations and it is the main motivation of the present work. Ln this work, a fully self-consistent charge-exchange relativistic random phase approximation (RPA) based on the relativistic Hartree-Fock (RHF) approach is established. Its self-consistency is verified by the so-called lAS check. This approach is then applied to investigate the nuclear spin-isospin resonances, isospin symmetry-breaking corrections for the superallowed β decays, and the charged-current neutrino-nucleus cross sections. For two important spin-isospin resonances, GTR and SOR, it is shown that a very satisfactory agreement with the experimental data can be obtained without any readjustment of the energy functional. Furthermore, the isoscalar mesons are found to play an essential role in spin-isospin resonances via the exchange terms, which leads to a profound effect in the nuclear isovector properties, e. G. , the density dependence of the symmetry energy in nuclear matter. Ln the investigation of the isospin symmetry-breaking corrections for the superallowed β decays, it is found that the corrections δc are sensitive to the proper treatments of the Coulomb mean field, but not so much to specific effective interactions. With these corrections δc, the nucleus-independent Ft values are obtained in combination with the experimental ft values in the most recent survey and the improved radiative corrections. The values of Cabibbo-Kobayashi-Maskawa matrix element IVudI thus obtained weil agree with those obtained in neutron decay, pion decay, and nuclear mirror transitions, while the sum of squared top-row elements somehow deviates from the unitarity condition. Expressing the weak lepton-hadron interaction in the standard current-current form, the relevant transitions from the nuclear ground state to the excited states are calculated with RHF+RPA approach. Ln this way, the semileptonic weak interaction processes, e. G. , neutrino reactions, charged- lepton capture, β-decays, can be investigated microscopically and self-consistently. First illustrative calculations of the inclusive neutrino-nucleus cross section are performed for the 16 O(Ve ,e-)16 F reaction, and a good agreement with the previous theoretical studies is obtained. The main effort is dedicated to discussing the substantial influence of different recipes for the axial vector coupling strength and the theoretical low-Iying excited states of the daughter nucleus

L’incertitude est un processus cognitif communément expérimenté lors d’une prise de décision. Dansle trouble obsessionnel-compulsif (TOC), il est excessif et compromet les capacités décisionnelles del'individu.Ce travail avait comme objectif une meilleure compréhension des aspects physiologiques etphysiopathologiques de l’incertitude, au travers d'une double approche, comportementale etélectrophysiologique. Dans un premier temps, nous avons construit une tâche originale qui permetd'exprimer son incertitude au cours d'une prise de décision. Avec cette "tâche d’incertitude", nousavons exploré les relations entre mémoire de travail et incertitude. Nous avons montré que lescapacités de mémoire de travail prédisaient la propension à l'incertitude chez les volontaires sains alorsque l'incertitude était suivie d'une dégradation des performances mnésiques chez les patients TOC.Puis, nous avons trouvé une relation entre capacités mnésiques et incertitude dans une population depatients épileptiques caractérisée par des déficits mnésiques, confirmant ainsi le rôle des capacitésmnésiques dans la survenue de l'incertitude physiologique.Pour l'étude des corrélats neuronaux, nous avons mesuré l'activité électrophysiologique intracérébraledes régions impliquées dans la prise de décision au cours de la tâche d'incertitude, chez des patientsépileptiques pour les structures corticales et chez des patients TOC pour les structures sous-corticales.Nous avons montré que l'incertitude était associée à : 1/ une diminution d’amplitude des potentielsévoqués des régions préfrontales et prémotrices ; 2/ une moindre synchronisation des bandes defréquence alpha et bêta en temps-fréquence ; 3/ une augmentation de l'amplitude des potentielsévoqués dans le noyau sous-thalamique. Nos résultats suggèrent un défaut d'engagement des structurescorticales impliquées dans la prise de décision au cours de l'incertitude. Enfin, notre travail tend àconfirmer le rôle du noyau sous-thalamique dans la physiopathologie du TOC et dans les mécanismessous-tendant l’incertitude pathologique<br>Uncertainty is a cognitive process that frequently influences our decisions in everyday life. Inobsessive-compulsive disorder (OCD), the high level of uncertainty usually alters the decision-makingprocess.This work aimed to a better understanding of physiological and pathophysiological aspects ofuncertainty, by exploring its relationships with working memory abilities and its neural correlates. Anoriginal task derived from a delayed matching-to-sample task was created with the possibility toexpress felt uncertainty during decision-making. With this "uncertainty task", we demonstrated thatbaseline working memory abilities predicted the occurrence of uncertainty in healthy individualswhereas uncertainty was followed by a decrease in working memory abilities in OCD patients. Therole of working memory abilities in the occurrence of uncertainty was further confirmed in a clinicalpopulation of epileptic patients suffering from baseline working memory impairments.For the study of the neural correlates of uncertainty, we measured intracerebral local field potentials(LFPs) in regions involved in decision-making during the uncertainty task. Cortical and subcorticalLFPs were obtained in epileptic and OCD patients, respectively. We showed that uncertainty wasassociated with: 1/ a decreased amplitude of evoked responses in cortical prefrontal and premotorregions, 2/ a reduced synchronization of alpha-beta frequency bands in time-frequency analyses, 3/ anincreased amplitude of evoked responses in the subthalamic nucleus. Our findings suggested adiminished cortical activation in uncertain decision-making and confirmed the role of the subthalamicnucleus in OCD pathophysiology and in the mechanisms underlying the occurrence of pathologicaluncertainty

International lawyers are familiar with the question: “Is international law law?” But this thesis instead asks the question: “Is international law international?” Using a variety of methods, this work sheds light on some of the ways in which international law as a transnational legal field is constructed by international law academics, and is conceptualized in international law textbooks, in the five permanent members of the Security Council: the People’s Republic of China, the French Republic, the Russian Federation, the United Kingdom of Great Britain and Northern Ireland, and the United States of America. It explores how different national communities of international lawyers construct and pass on their understandings of “international law” in ways that belie the field’s claim to universality, perpetuating certain forms of difference and dominance. By adopting a comparative approach, it aims to make international lawyers more aware of the frames that shape their own understandings of and approaches to the field, as well as how these might be similar to or different from the frames adopted by those coming from other states, regions or geopolitical groupings. It also examines how some of these patterns might be disrupted as a result of shifts in geopolitical power, such as the movement from unipolar power toward greater multipolarity and the growing confrontations between Western liberal democratic states (like the United States, the United Kingdom, and France) and non-Western authoritarian states (like China and Russia).

The building blocks of atomic nuclei, protons and neutrons, interact via the strong force. The fundamental theory of the strong interaction, quantum chromodynamics (QCD), is non-perturbative at the energy scales relevant for nuclear physics. Calculations of low-energy observables based directly on QCD thus present a challenge. Effective field theories (EFTs) of QCD, such as chiral EFT, provide an alternative pathway to describe the nuclear force and the interaction of nuclei with external particles. In this thesis, chiral EFT is applied to studies of few-neutron systems as well as in calculations of nuclear structure factors relevant for dark matter searches. Currently, only lattice QCD calculations in finite volume allow for direct solutions of QCD at low energies. Matching results obtained in chiral EFT to lattice QCD calculations thus presents a promising avenue for the construction of nuclear forces directly based on QCD. This becomes especially relevant in the few-neutron sector, which is challenging to access experimentally so that input for effective field theories is scarce. In this thesis, we take first steps in this direction by performing quantum Monte Carlo (QMC) calculations of the ground and first excited states of two neutrons in finite volume. We analyze the finite-volume effects that are crucial for the determination of infinite-volume observables from finite-volume data. The interest in few-neutron states also stems from a recent measurement of a possible tetraneutron resonance. We present QMC calculations of three and four neutrons interacting via chiral EFT forces confined in an external potential well. By extrapolating to the physical case of vanishing external-potential strength, we obtain a quantitative estimate of possible three- and four neutron resonance energies. Our results suggest that a three-neutron resonance, if it exists, may be lower in energy than a tetraneutron resonance. Furthermore, we present an alternative approach to the extraction of resonance properties based on the volume dependence of the calculated discrete energy spectra in finite volume. Using a discrete variable representation based on plane waves, we show for both bosonic and fermionic systems of up to four particles that multi-body resonances appear as avoided level crossings in the energy spectra. Our results establish few-body finite-volume calculations as a new tool to study few-body resonances. The analysis of dark matter direct detection experiments depends crucially on nuclear structure factors that describe the coupling of proposed dark matter particles (WIMPs) to the target nuclei used in such searches. We present a chiral power counting scheme for operators describing various types of WIMP-nucleon interactions including both nuclear one- and two-body currents. In a second step, we evaluate the corresponding structure factors for different target nuclei and determine the dominant corrections to the standard spin-independent channel. Based on chiral EFT and nuclear structure effects, we propose an extension of the standard analysis applied in experimental searches. In addition, we find that two-body contributions help improve limits on the WIMP-nucleon cross section based on collider searches of Higgs-mediated dark-matter interactions. Finally, we investigate to what extent current and planned experiments are able to distinguish the subdominant WIMP-nucleon interaction channels from the standard spin-independent interaction based on their momentum dependence.

Gamma oscillations of local field potentials (LFP) in the basal ganglia and thalamus had not been studied during saccades. Eleven patients were studied during deep brain stimulation (DBS); 6 were in the subthalamic nucleus (STN); 3 in the globus pallidus interna (GPi); and 2 in the thalamic ventralis intermedius nucleus (Vim). Patients performed horizontal saccades to visual targets while LFPs from DBS electrodes, scalp electroencephalogram (EEG), and electrooculogram (EOG) were recorded. Wavelet spectrograms were generated and saccade onset and event-related gamma synchronizations (ERS) were compared to baseline without eye motion. ERS were recorded at and after saccade onset in the STN, GPi and Vim, EEGs and EOGs; but were absent during target light illumination without saccades. ERS were symmetric in all DBS contacts and appeared identical in DBS LFPs, frontal EEGs and EOGs. These findings indicate their origin from extraocular muscle spike potentials rather than brain neural activity.

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2021<br>Contextualização: Os Local Field Potentials (LFPs) permitem a medição da atividade neuroelétrica do núcleo subtalâmico (NST) e constituem promissores biomarcadores de parkinsonismo na doença de Parkinson (DP). Atividades voluntárias podem interferir com o grau de parkinsonismo. O registo de LFPs constitui uma oportunidade para investigar a influência de tarefas voluntárias sobre a atividade neuroelétrica do NST e sobre o funcionamento de sistemas de estimulação cerebral profunda (DBS) em circuito fechado. Objetivos: Investigar a interferência de atividades voluntárias no registo dos LFPs do NST. Objetivos secundários: investigar a relação entre manifestações clínicas e terapêutica instituída e o registo de LFPs do NST. Metodologia: Estudo n=1 transversal e prospetivo, com múltiplos cruzamentos de 3 tarefas (fala, movimentos das mãos e marcha), sob de 4 condições, consoante estimulação (STIM)/medicação (MED), ao 1º e 6 meses DBS, em doente implantado com elétrodos com capacidade de registo de LFPs. A avaliação clínica foi realizada utilizando a MDS-UPDRS III. As flutuações motoras e discinésias foram registadas num diário de Hauser. Realizou-se a análise descritiva dos resultados. Resultados: Identificou-se a interferência de atividades voluntárias sobre os registos de LFPs, preferencialmente em STIM OFF. A fala associou-se consistentemente à diminuição da intensidade da banda beta; os movimentos das mãos e marcha à diminuição de beta e a marcha ao aumento de gama. No período STIM OFF/MED ON, identificou-se uma diminuição da intensidade de low beta, concomitante à melhoria da MDS-UPDRS III relativamente a MED OFF. Conclusões: A atividade voluntária interfere no registo de LFPs do NST em STIM OFF. A ausência de interferência significativa em STIM ON não apoia a sua relevância em sistemas DBS em circuito fechado. O nosso estudo contribui para a investigação na fisiopatologia da DP e em DBS e suporta a realização de futuros estudos nesta área.<br>Background: Local Field Potentials (LFPs) allow the measurement of subthalamic nucleus´s (STN) neuroelectrical cerebral activity and constitute promising biomarkers of parkinsonism in Parkinson’s disease (PD). Voluntary activities may interfere with the parkinsonism level. Recording LFPs of STN constitutes an opportunity to investigate the influence of voluntary tasks on STN´s neuroelectric activity and on Deep Brain Stimulation (DBS) systems in closed loop. Objectives: Investigate the interference of voluntary movement in the LFPs recordings. Secondary objectives: Investigate the relationship between clinical manifestations and instituted therapeutics and the NST´s LFPs recordings. Methods: Cross-sectional and Prospective Study n=1, with multiple crossings of 3 tasks (speech, hand movements and gait) under 4 conditions, depending on stimulation (STIM)/ medication (MED), at first and sixth month after DBS, in a patient implanted with LFP´s recording capacity electrodes. The clinical evaluation was made through MDS-UPDRS III. Motor fluctuations and dyskinesias were registered in an Hauser´s diary. It was made a descriptive analysis of the results. Results: It was identified the interference of voluntary activities in the LFP´s recordings, mainly under STIM OFF. Speech was consistently associated with a beta band intensity’s decrease; hand movements and gait with beta band intensity’s decrease and gait also with gama band intensity´s increase. Under STIM OFF/MED ON, the beta band intensity’s decrease was simultaneously associated with an improvement in MDS-UPDRS III comparing with MED OFF. Conclusions: Voluntary activity interferes in NST´s LFPs recordings under STIM OFF. The absence of this interference under STIM ON doesn´t support its relevance in closed loop DBS systems. Our study contributed for the research on PD´s pathophysiology and DBS and supports the relevance of new studies in this field.

Predicting how the future climate of Earth will change as a result of increasing human emissions is one of the greatest problems facing science today. The earth’s climate is the result of a delicate balance between incoming and outgoing radiation. Anthropogenic emissions of aerosol particles into the atmosphere have the potential to affect the earth’s climate in significant ways through both direct and indirect effects on the earth’s radiative balance. One of the largest uncertainties in aerosol radiative forcing is associated with the relationship between atmospheric aerosols and cloud formation, properties, and lifetime. Clouds form by water condensing on small particles (aerosols) in the air (referred to as cloud condensation nuclei, or CCN), and how the increasing levels of atmospheric particles will affect Earth’s clouds and its hydrologic cycle represents one of the key problems in the science of climate. Through theoretical, field, and laboratory investigations, the results presented here reinforce the importance of atmospheric aerosol chemical composition in determining the ability of an aerosol particle to act as a CCN. A study that incorporates surface tension and limited solubility effects, especially of organic compounds, in parameterizations of cloud droplet activation indicate that these chemical effects can rival those of the meteorological environment. An inverse CCN/aerosol closure study of field measurements indicates that assumptions of simple chemistry and mixing state in the interpretation and analysis of field cloud condensation nuclei (CCN) measurements may not necessarily be sufficient and/or realistic, depending heavily on the location of the field study. Properties of organic compounds, such as functional groups, extent of dissociation, and solubility were found to influence the CCN activity of the compounds in laboratory experiments with pure organic aerosols. However, the importance of careful planning of laboratory experiments, in consideration of the properties of the organic compounds, was reinforced and results were carefully interpreted to avoid experimental bias in the conclusions.

Котелевець А. О. Лексико-семантичне поле «продукти харчування в сучасній англійській мові» : кваліфікаційна робота магістра спеціальності 035 "Філологія" / наук. керівник О. В. Шевчук. Запоріжжя : ЗНУ, 2021. 54 с.<br>EN : The work is presented on 54 pages of printed text. The list of references includes 89 sources.The present paper is dedicated to the analysis of the lexical-semantic field "Food" structure in modern English. The object of the research is the peculiarities of the lexical and semantic field "food" in modern English. The purpose of the research is to establish the peculiar features of the organization of the lexical and semantic field "food" in modern English. The theoretical and methodological background is the scientific works, which cover the given problem by V.V. Vinogradov, V.G. Admoni, N.D. Arutyunova, V.Yu. Apresyan, N.N. Boldirev, A. Vezhbytska, G.A. Ufimtseva, L.M. Vasiliev, I.M. Кобозева, О.О. Selivanova, Z.N. Verdiyev. The obtained results are the following: the structure, the composition, and the hierarchy of the semantic field "food", the semantic set of its units, their connotative potential is largely determined by the characteristics of the fragment of the world. The value is manifested in the specific selection of the linguistic means which describe the facts and the phenomena of the surrounding reality from a certain point of view that is ethnoculturally and socially determined. The nuclear zone of the lexical-semantic field "food" consists of the native vocabulary, i.e. words of the Anglo-Saxon origin. However, some borrowings have been so assimilated into the recipient language that they are perceived by the linguistic and cultural communities as the native vocabulary, which is characterized by the high usage frequency, and accordingly, they are located in the nuclear zone of the given semantic field.<br>UA : Робота викладена на 54 сторінках друкованого тексту. Перелік посилань включає 89 джерел. Об’єкт дослідження: лексико-семантичне поле «продукти харчування» в сучасній англійській мові. Мета роботи: встановлення особливостей організації лексико-семантичного поля «продукти харчування» в сучасній англійській мові. Теоретико-методологічні засади: наукові праці, де висвітлювалась подана проблема (В.В. Виноградов, В.Г. Адмони, Н.Д. Арутюнова, В.Ю. Апресян, Н. Н. Болдірев, А. Вежбицька , Г.А. Уфімцева, Л.М. Васильєв, І.М. Кобозева, О.О. Селіванова, З.Н. Вердієва). Отримані результати: Структура, склад і ієрархія семантичного поля «продукти харчування», семний набір його одиниць, їх конотативний потенціал значною мірою визначаються особливостями того фрагмента картини світу, яку покриває дане семантичне поле. Етнокультурно і соціально детермінована, цінність проявляється у специфічному відборі лінгвістичних засобів для опису фактів і явищ навколишньої дійсності під певним кутом зору. Таким чином, реципієнт отримує інформацію, яка є вже певним чином прагматично обробленої. Ядерну зону семантичного поля «продукти харчування» складає власномовна лексика, тобто слова англосаксонського походження. Проте, деякі запозичення настільки асимілювалися в мові-реципієнті, що сприймаються лінгвокультурними спільнотами як власно мовна лексика, характеризуються високою частотністю вживання та, відповідно, розташовані в ядерній зоні зіставлю вальних семантичних полів.

Saccades are rapid eye movements that we continually make (about 2-3 times per second) to look around and scan our visual environment. Though we effortlessly execute saccadic eye movements all the time, they are not just reflexive movements; saccades have been shown to involve multifaceted cognitive control mechanisms. This property of saccades, combined with the fact that saccadic parameters are easily measurable, and that the neural circuitry for saccade generation is fairly well established, has established saccadic eye movements to be an excellent tool to study motor planning and decision-making. However, much of the work done on saccade planning has been limited to understanding the production of single saccades. Natural behavior entails making multiple saccadic movements in a sequence to achieve day-to-day tasks such as reading a book. How are sequential saccades planned? This question forms the broad theme of this thesis. The neural correlates of sequential saccade planning were scouted for in the macaque frontal eye field (FEF), a prefrontal area containing neuronal populations that undertake saccadic decision-making. Visual-salience neurons of the FEF have been shown to encode targets for upcoming saccades and movement-related neurons of the FEF have been shown to control the time of saccade initiation, providing a good link between neural activity and behaviorally measured reaction times. However, much of the neural underpinnings of saccade programming in the FEF have been uncovered using tasks involving single, isolated saccades. Motivated by this, I explored the mechanisms by which FEF neurons contributed to the programming of saccade sequences for this thesis, using single-unit electrophysiological recordings from the FEF of two macaques as they performed a sequential saccade task. Sequential saccade programming can, in principle, operate through two major modes: serial or parallel. Behavioral measures, like short inter-saccadic intervals, strongly indicate that multiple saccade plans can proceed in parallel. However, direct neural evidence of parallel programming in the FEF neuronal population that strongly link to behavior, i.e. movement neurons, is lacking. First, I show that FEF movement-related activity can start ramping-up for the second saccade before the first saccade execution is complete, and much before visual feedback from the first saccade can reach FEF, thereby providing neural correlates of parallel programming of sequential saccades. Perceptual processing in the FEF has been shown to precede motor processing in visual search tasks, and consistent with that notion, FEF neurons with visual activity were also able to augment activity related to the second target whilst the first saccade plan was still underway. After finding neural evidence of parallel programming, I characterized the limits of parallel programming. Numerous studies have shown that when two motor plans overlap closely, processing bottlenecks arise to inhibit the programming of the second plan, and is behaviorally manifested by the progressive lengthening of the second task reaction time, as the temporal gap between the two tasks decreases. This feature of increase in the second task latency has been observed in sequential saccade tasks as well. Neural correlates of processing bottlenecks were found in the responses of FEF movement neurons, wherein for the second saccade plan, the rate of the growth of activity was perturbed and the threshold of saccade initiation was increased, in a degree proportional to the level of concurrence of the two saccade plans. The locus of processing bottlenecks was found to be at the level of FEF movement-related neurons, whereas the activity of the visual neurons indicated that visual processing for perceptually simple tasks might constitute a pre-bottleneck stage. Evidence of activity perturbations was also found for the first saccade plan, supporting capacity-sharing theories of processing bottlenecks, as opposed to single-channel bottleneck theories which postulate that only the second plan is gated by inhibitory control while the first can pass unabated. Together, the results suggest that processing bottlenecks in sequential saccades originate in the partitioning of the brain’s limited processing ‘capacity’ by simultaneously active motor plans, due to which, inhibitory control is applied on both the first and second saccade plans, to prevent straining of the aforesaid capacity. Finally, I have examined peripheral signatures of sequential saccade planning. Recent studies using single saccade paradigms have shown that the function of FEF as a center of cognitive control is not limited to saccade eye movements, but can be generalized to the control of eye-head gaze shifts. Rapid presaccadic recruitment of dorsal neck muscle activity has been shown to occur after FEF both with single-unit microstimulation and trans-cranial magnetic stimulation, even under head-restrained conditions where no overt head movement is being brought about by the neck muscles. To investigate whether such presaccadic recruitment occurs during sequential saccade planning or is gated out by inhibitory control, I recorded electromyographic (EMG) activity of motor units of the dorsal neck muscle as macaques performed the same sequential saccade task used for neural recordings. Neck muscle EMG showed leakage of FEF planning signals even for sequential saccades: peripheral correlates of parallel programming and processing bottlenecks were observed, with the activity mirroring that of FEF movement neurons. The correspondence of the results between the FEF and periphery suggest that a tight link exists between the eye and head systems, validating the hypothesis of a common gaze command originating in the FEF. The rapid recruitment of neck muscle activity observed for the second saccade before the completion of the first, also suggested that inhibitory control gates like basal ganglia do not preferentially intercept sequential saccade signals in the FEF-neck muscle circuit. In summary, the results in this thesis provide direct neurophysiological evidence of behaviorally established features of sequential saccade planning such as parallel programming and processing bottlenecks. The fact that signatures of FEF movement responses can be captured at the level of the dorsal neck muscle suggests that the functional channel connecting FEF and the motor periphery is preserved even during sequential saccade planning and allows central responses to rapidly pass downstream by default, and perhaps prepare for an anticipated head movement in conjunction with the upcoming saccade. In cases where no head movement is elicited or where the head is restrained, inhibitory control mechanisms might come into play later and prevent supra-threshold rise of neck muscle activity.

Cholinergic inputs from mesopontine tegmentum activate midbrain dopamine (DA) neurons via M5 muscarinic receptors. The M5 receptor is important for mesopontine stimulation-induced accumbal or striatal DA efflux, brain stimulation reward or morphine-induced conditioned place preference (CPP). M5 receptor knockout (KO) mice show 40-50% less morphine-induced locomotion. Pedunculopontine tegmental nucleus (PPT) lesions in rodents block morphine CPP, but are ineffective after 18 hours food deprivation, opiate dependence, or intra-VTA BDNF. Based on these findings, we investigated whether acute food deprivation or intra-VTA BDNF alters morphine-induced locomotion (3 and 10 mg/kg, i.p.) in C57BL/6 M5 KO mice. Non-deprived M5 KOs showed reduced morphine-induced locomotion, suggesting M5 receptors partly mediate morphine-induced locomotion. Morphine-induced locomotion was reversed in food-deprived mice, suggesting the stimulant effects of morphine were altered to bypass the PPT. Unexpectedly, intra-VTA BDNF infusions were ineffective in altering morphine-induced locomotion. Additionally, M5 KOs receiving intra-VTA saline showed no deficits in morphine-induced locomotion.

Στην παρούσα εργασία μελετάμε τη μοντελοποίηση του υποθαλαμικού πυρήνα των βασικών γαγγλίων με χρήση του μαθηματικού νευρωνικού μοντέλου Izhikevich. Βάση της μελέτης μας αποτελούν μικροηλεκτροδιακές καταγραφές, που έχουν ληφθεί κατά τη διάρκεια νευροχειρουργικών επεμβάσεων εν τω βάθει εγκεφαλικής διέγερσης, για τη συμπτωματική θεραπεία της νόσου Πάρκινσον. Θα ξεκινήσουμε με μια εισαγωγή στην φυσιολογία του νευρικού κυττάρου και στην ανατομία των βασικών γαγγλίων. Θα αναλύσουμε τα βασικά ποιοτικά μοντέλα που ερμηνεύουν τη συμμετοχή των τελευταίων σε κινητικές διεργασίες, αλλά και την εμπλοκή τους στη νόσο Πάρκινσον. Μετά από μια σύντομη αναφορά στη μέθοδο της εν τω βάθει διέγερσης και στις μικροηλεκτροδιακές καταγραφές, θα εστιάσουμε στα δυναμικά τοπικού πεδίου και στη νευροφυσιολογική σημασία τους. Συνεχίζοντας, θα κάνουμε μια περιεκτική ανασκόπηση των βασικότερων μαθηματικών μοντέλων νευρώνων και ύστερα θα επικεντρωθούμε στον υποθαλαμικό πυρήνα, περιγράφοντας δύο πρόσφατα μοντέλα που έχουν κατασκευαστεί για την προσομοίωση των νευρώνων αυτού. Έπειτα, θα περάσουμε στην περιγραφή του μοντέλου Izhikevich και στην τροποποίησή του για την αναπαραγωγή των χαρακτηριστικών του νευρώνα του υποθαλαμικού πυρήνα. Κατόπιν, θα αναλύσουμε τη μεθοδολογία που ακολουθήσαμε στην παρούσα υλοποίηση και τις βασικές θεωρήσεις της μοντελοποίησης μας. Θα ολοκληρώσουμε με την παρουσίαση των αποτελεσμάτων, το σχολιασμό αυτών και τις ιδέες για μελλοντική επέκταση της μεθόδου μας.<br>The main objective of this MSc thesis is the study of subthalamic nucleus, by using the Izhikevich neuron model. Microelectrode recordings, taken during deep brain stimulation operations for Parkinson’s disease, have been used for that purpose. In chapters 1-2, there is an introduction to the physiology of the neuron and the basal ganglia anatomy. In the two following chapters, we are analyzing the basic qualitative models that describe the involvement of the basal ganglia in movements and the pathophysiology of Parkinson’s disease. We are briefly discussing the method of deep brain stimulation, microelectrode recordings processing and the extraction of local field potentials. In chapter 5, the basic mathematical neuron models are discussed. We are focusing on the subthalamic nucleus and we are describing two recently developed mathematical models of the subthalamic neuron. In chapter 6, we are outlining Izhikevich neuron model and its modification in order to describe the subthalamic neuron. In addition, we are analyzing the methodology developed for the implementation of the modeling process and our basic considerations. In chapter 7, the results of the simulation are presented and discussed, so that our conclusions provide ideas for further research.

Radoslav P a s s i a Aesthetics of Periphery and Border (To Selected Aspects of Periphery and Border Phenomenon in Slovak Literature of the 20th Century in Central European Context) Abstract The dissertation deals with selected aspects of periphery and border phenomenon in Slovak literature of the 20th century in Central European context. In the preliminary chapter Border the author focuses particularly on selected texts by Central European writers which are thematically set in the Eastern Carpathians. This radically multiethnic region is considered to be one of the relatively independent cultural areas of Central Europe by the author. Narrative perspectives of a stranger, outcast, migrant in combination with the themes of border and conflict between vernacular and alien are characteristic for the literary image of the Eastern Carpathian border area in the 20th century. The author looks at the way the literary appearance of this area is ideologically deformed in the works of individual authors. The writers (mainly Czech and Polish) who do not come from the Eastern Carpathian border area use characters of strangers to reflect on the relationship between the modern and the traditional. Autochthonous authors often make use of the stranger characters to depict the area's self-colonial efforts in relation to the...