Rewiring color categories: the neural consequences of language contact

In this thesis, through a combination of fieldwork, computational modeling, behavioral and neurophysiological (EEG) experimentation, we establish a neural precursor of the acquisition of lexical color categories. The thesis consists of 3 studies, each comprising a number of computational, behavioral and EEG experiments. The first study (Chapter 1) reports our field research on the color systems of Galician and Spanish, two geographically contiguous and historically related languages. Our aim here was to explore similarities and differences in the way speakers of these languages set boundaries between color categories in the green-yellow-brown and blue ranges. We provide preliminary evidence that regional color meanings can co-exist in neighboring and connected populations. In a series of computer simulations (Chapter 2) and laboratory experiments (Chapters 2-3), we recreated a minimal language contact scenario, in which speakers of different languages, with possibly different color systems, must coordinate and communicate by means of basic color terms used as signals. In the second study (Chapter 2), participants learned during two consecutive days an artificial color system by playing as receivers in a signaling game with a computer. In a series of computer simulations, we show that the artificial color system is learnable by agents endowed with minimal cognition and limited memory. The stimuli consisted of an array of 5 Munsell colors that varied along the hue dimension from brown to green, with the most ambiguous color occupying the middle position in the array. At the end of day two, the EEG was recorded while participants were shown color-term (CT) and term-color (TC) stimulus sequences that were either learned, as part of the artificial color system, or incongruent. We found similar evoked responses to color terms in CT sequences and to colors in TC sequences, with larger late negative ERPs in incongruent than in learned trials. This EEG evidence for category-level color representations was supported by two independent color discrimination studies. ERP effects were largest for the more ambiguous colors, suggesting the strongest neural changes in the brain occur at the boundary of two color categories. The second experiment was identical to the first, with the exception that color stimuli were different. Here, the five colors varied in lightness within the blue hue with an ambiguous blue/black color as the terminal color in the array. We obtained larger late negative ERPs, very similar to those observed in the first experiment, in incongruent than in learned trials in CT sequences for the most ambiguous color in the array. Our results indicate that these ERP effects may reflect the effort of rewiring the native color categorization of participants into the artificial color system they have learned

Nanoparticle drug delivery systems for inner ear therapy: An overview

open7noembargoed_20180701Valente, Filippo; Astolfi, Laura; Simoni, Edi; Danti, Serena; Franceschini, Valeria; Chicca, Milvia; Martini, AlessandroValente, Filippo; Astolfi, Laura; Simoni, Edi; Danti, Serena; Franceschini, Valeria; Chicca, Milvia; Martini, Alessandr

Evolution and architecture of a West Mediterranean Upper Pleistocene to Holocene coastal apron-fan system

The Quaternary deposits of tectonically stable areas are a powerful tool to investigate high-frequency climate variations (<10 ka) and to distinguish allogenic and autogenic factors controlling deposition. Therefore, an Upper Pleistocene—Holocene coastal apron-fan system in north—western Sardinia (Porto Palmas, Italy) was studied to investigate the relations between climate changes, sea-level fluctuations and sediment source-supply that controlled its development. The sedimentary sequence records the strong influence of local (wet/dry) and worldwide (sea-level) environmental variations in the sedimentation and preservation of the deposits. A multi-disciplinary approach allowed subdivision of the succession into four major, unconformity-bounded stratigraphic units: U1 U2, U3 and U4. Unit U1, tentatively dated to the warm and humid Marine Isotopic Stage (MIS) 5, consists of sandy, gravelly coastal/beach deposits developed during high sea-level in low-lying areas. Unit U2 consists of debris-flow dominated fan-deposits (ca 74 ka; MIS 4), preserved as partial fills of small valleys and coves. Unit U2 is mainly composed of reddish silty conglomerate to pebbly siltstones sourced from the Palaeozoic metamorphic inland hills (bedrock), superficially disintegrated during the preceding warm, vegetation-rich MIS 5. The cold and semi-arid climate strongly reduced vegetation cover along the valley flanks. Therefore, sediment gravity-flow processes, possibly activated by rainstorms, led to deposition of debris-flow dominated fans. Unit U3 consists of water-flow dominated alluvial-fan deposits (ca 47 to 23 ka; MIS 3), developed on a slightly inclined coastal plain. Unit U3 is composed of sandstone and sandy conglomerate fed from two main sediment sources: metamorphic inland bedrock and Quaternary bioclastic-rich shelf-derived sands. During this cold phase, sea-level dropped sufficiently to expose bioclastic sands accumulated on the shelf. Frequent climate fluctuations favoured inland aeolian transport of sand during dry phases, followed by reworking of the aeolian bodies by flash floods during wet phases. Bedrock-derived fragments mixed with water-reworked, wind-blown sands led to the development of water-flow dominated fans. The Dansgaard—Oeschger events possibly associated with sand landward deflation and main fan formations are Dansgaard—Oeschger 13 (ca 47 ka), Dansgaard—Oeschger 8 (ca 39 ka) and Dansgaard—Oeschger 2 (ca 23 ka). No record of sedimentation during MIS 2 was observed. Finally, bioclastic-rich aeolianites (Unit U4, ca 10 to 5 ka; MIS 1), preserved on a coastal slope, were developed during the Holocene transgression (ca 10 to 5 ka; MIS 1). The studied sequence shows strong similarities with those of other Mediterranean sites; it is, however, one of the few where the main MIS 4 and MIS 3 climatic fluctuations are registered in the sedimentary record

Evolution and architecture of a West Mediterranean upper Pleistocene to Holocene coastal apron-fan system

The Quaternary deposits of tectonically stable areas are a powerful tool to investigate high-frequency climate variations (&#60;10 ka) and to distinguish allogenic and autogenic factors controlling deposition. Therefore, an Upper Pleistocene&#8212;Holocene coastal apron-fan system in north&#8212;western Sardinia (Porto Palmas, Italy) was studied to investigate the relations between climate changes, sea-level fluctuations and sediment source-supply that controlled its development. The sedimentary sequence records the strong influence of local (wet/dry) and worldwide (sea-level) environmental variations in the sedimentation and preservation of the deposits. A multi-disciplinary approach allowed subdivision of the succession into four major, unconformity-bounded stratigraphic units: U1 U2, U3 and U4. Unit U1, tentatively dated to the warm and humid Marine Isotopic Stage (MIS) 5, consists of sandy, gravelly coastal/beach deposits developed during high sea-level in low-lying areas. Unit U2 consists of debris-flow dominated fan-deposits (ca 74 ka; MIS 4), preserved as partial fills of small valleys and coves. Unit U2 is mainly composed of reddish silty conglomerate to pebbly siltstones sourced from the Palaeozoic metamorphic inland hills (bedrock), superficially disintegrated during the preceding warm, vegetation-rich MIS 5. The cold and semi-arid climate strongly reduced vegetation cover along the valley flanks. Therefore, sediment gravity-flow processes, possibly activated by rainstorms, led to deposition of debris-flow dominated fans. Unit U3 consists of water-flow dominated alluvial-fan deposits (ca 47 to 23 ka; MIS 3), developed on a slightly inclined coastal plain. Unit U3 is composed of sandstone and sandy conglomerate fed from two main sediment sources: metamorphic inland bedrock and Quaternary bioclastic-rich shelf-derived sands. During this cold phase, sea-level dropped sufficiently to expose bioclastic sands accumulated on the shelf. Frequent climate fluctuations favoured inland aeolian transport of sand during dry phases, followed by reworking of the aeolian bodies by flash floods during wet phases. Bedrock-derived fragments mixed with water-reworked, wind-blown sands led to the development of water-flow dominated fans. The Dansgaard&#8212;Oeschger events possibly associated with sand landward deflation and main fan formations are Dansgaard&#8212;Oeschger 13 (ca 47 ka), Dansgaard&#8212;Oeschger 8 (ca 39 ka) and Dansgaard&#8212;Oeschger 2 (ca 23 ka). No record of sedimentation during MIS 2 was observed. Finally, bioclastic-rich aeolianites (Unit U4, ca 10 to 5 ka; MIS 1), preserved on a coastal slope, were developed during the Holocene transgression (ca 10 to 5 ka; MIS 1). The studied sequence shows strong similarities with those of other Mediterranean sites; it is, however, one of the few where the main MIS 4 and MIS 3 climatic fluctuations are registered in the sedimentary record

Q-Bounded Maximum Directivity of Self-Resonant Antennas

The upper limit on the directivity of self-resonant antennas that fit within a minimum sphere is determined for a given quality factor. This formulation is obtained by analytically solving a rigorous convex problem and is expressed as a rapidly converging analytical series. The total quality factor, inverse of the relative frequency bandwidth, is formulated by considering the quality factors of individual spherical waves. From the exact series, approximate closed-form formulas have been derived, which exhibit high accuracy in complementary ranges of the minimum circumscribed sphere’s radius. These ranges encompass small antennas as well as intermediate to large antennas. Special emphasis is given to small antennas, where the solution is interpreted as combination of dipolar and quadrupolar Huygens’ source contributions with appropriate closed form coefficients. The solution in this range provides continuity to the maximum directivity between 3 and 8 maintaining a constant Q