COGNITIVE PROPERTIES OF APPROVAL VOTING. AN EXPERIMENTAL APPROACH

Atom lithography is a technique to structure layers of atoms during deposition, using interactions of near-resonant light fields with neutral atoms. The basic scheme uses a standing wave light field, aligned just above a substrate, while a beam of atoms impinges perpendicularly on the standing wave light field. The interaction of the light field and the atoms focuses the atoms towards the crests or troughs of the standing wave intensity, dependent on the tuning of the light field. The focused atoms are subsequently deposited on the substrate, resulting in an array of lines, whose periodicity is determined by the wavelength of the light field. The standing wave light field can therefore be seen as an array of lenses, focusing the atom beam into an array of lines. The first experiments on atom lithography were performed in the 1990s with sodium and chromium. In this thesis experiments with iron are described, which is a magnetic element and thus allows for the creation of magnetic nanostructures. To focus atom beams into structures using atom lithography, well-colimated atom beams are required. The most common technique to create collimated atom beams is transverse laser cooling, but iron has no closed optical transition suitable for laser cooling. Fortunately Smeets and Te Sligte found that even then atom lithography of iron is possible. If the standing wave light field is considered to be an array of lenses, the focusing of the atom beam on a single lens is determined by the local collimation of the atom beam at that position. This local collimation is determined by the geometry of the beam source and the distance of the beam source to the standing wave lens. Using a small beam source (e.g. 1 mm diameter) positioned far from the standing wave (e.g. 1 m), the geometrically collimated atom beam is suitable for atom lithography. Chapter 3 shows what the implications of geometric collimation are on the structure formation in atom lithography. The geometric effects that locally collimate the atom beam on the sample also introduce local offset angles of the atom beam with respect to the focusing light field. Structure formation has been observed with lines of up to 7 nm high on a background layer of 15 nm average height, over areas of up to 400 µm × 6 mm. This indicates that the offset angles can vary over an 8 mrad range, which is more than an order of magnitude larger than the local angle of collimation. The offset angle influence the local geometry of the deposited structures: an increasing offset angle decreases the local line height, increases the width and creates a skewness in the local line shape. The local geometry of the lines has been modelled with a Monte Carlo particle tracking model and the results were compared to experiments. It was found that the highest and narrowest lines suffer from significant broadening due to surface diffusion in experiments, limiting the achievable structure width of iron on SiOx samples to about 80 nm. We have also found that in atom lithography without laser cooling, each standing wave lens is effectively imaging the source geometry onto the substrate. We therefore propose using structured atom beam sources to image more complex patterns on sub-wavelength scales in a parallel way. The reason to use iron in atom lithography, is the option to create magnetic nanostructures. However, in previous experiments no clear magnetic signature of the atom lithographic structuring of iron was found. Therefore in Chapter 4 firstly the magnetic properties of unstructured layers of iron (Fe), nickel (Ni) and FexNi1-x are investigated. These layers are all ferromagnetic, but with a reduced magnetic moment compared to bulk values due to contaminations and crystal growth effects. As a reference for periodic atom lithography structures, periodic line structures are created with interference lithography in a polymer layer and onto these structures thin layers of FexNi1-x are shadow deposited, thereby creating a layer periodically modulated in both height and elemental composition. This periodic modulation in composition has been observed with SEM-EDX on sub-micron scales. The structures showed a clear magnetic anisotropy with an easy axis along the direction of the lines, in accordance with expectations. In Chapter 5, the magnetic properties of atom lithographic iron line structures are presented. Using MOKE microscopy, direct comparison of structured and unstructured parts of a sample is possible, which allows for the observation of clear magnetic signatures due to the atom lithographic structuring. In layers of an average thickness of about 15 nm, no anisotropy is induced by the line structures, while a magnetic easy axis along the direction of the lines is expected. The line structures introduce an isotropic increase in the coercivity of the layers, indicating that the line structures can be considered as isotropic corrugations instead of directional line structures. For layers of 30 nm average thickness and thus higher line structures, a clear magnetic anisotropy is observed for the highest line structures. This anisotropy can be seen as a magnetic easy axis along the direction of the lines, as expected for line structures. However, we also observe a sharp increase in coercivity for applied fields perpendicular to the lines. This phenomenon is intriguing and may be explained by a pinning of head-to-head domain walls along the direction of the lines. In Chapter 5, we also report on the first results of co-deposition of FexNi1-x, where the Fe is structured into lines using atom lithography, while the Ni is deposited uniformly, thereby creating an alloy of modulating composition. Magnetic analysis of these structures indicates that these structures are anisotropic, both the coercivity and the shape of domain walls is dependent on the angle of the applied field relative to the line structures. Finally in Chapter 6, we investigate the possibilities to focus a thermal beam of atoms into a single 100 nm spot using light fields, thereby creating a nanopencil suitable for deposition of nanostructures. A Monte Carlo particle tracking program was developed to model the all optical focusing or funneling of 10 µm sized atom beams to a 100 nm spot. This model included effects of initial beam divergence, magnetic substructure, laser cooling, and spontaneous as well as stimulated diffusion and it was applied to a number of promising light field configurations. The best results obtained for experimentally realistic settings are a beam focused to a full width at half maximum of FWHM = 0.55 µm in a blue detuned hollow beam where atoms are focused towards the dark center, or a FWHM = 0.31 µm in a red detuned axicon light field, where atoms are focused towards the maximum intensity at the heart line. However, in the latter case the focused beam has a flux only 25 times larger than the background flux, which is unpractical for applications. The limiting factors of all schemes are heating due to stimulated diffusion and the limited interaction time available for a thermal beam of atoms. A nanopencil could be possible if it were based on the focussing of a slow and / or monochromatic atom beam, but this would seriously complicate the practical application of such a device.

Game theoreticians usually deal with standard voting methods, such as plurality voting or approval voting. In reality however, some complicated non-standard voting methods are used. In this paper we shall present the voting method and rotation scheme used by the Governing Council of the European Central Bank (ECB), as it enlarges to accommodate new members of the economic and monetary union. We present game theoretical approaches to analyzing this method and different methods of computing the Shapley value for games connected with voting under such rotation schemes.

Study of the kinetics of condensation and evaporation of water vapor over atmospherically relevant pure and doped ice films

How does one’s food environment affect food purchase decisions? Food access has received significant political and academic attention, particularly under the Obama administration. Existing literature on food access and “food deserts” mainly focuses on geographic distance or the retail of fresh fruits & vegetables versus fast food within a neighborhood to determine and identify inequitable access. In this paper I attempt to develop an endogenous measure of food access by asking how geographic placement of food retail affects food expenditure, particularly of fruits & vegetables. I use novel data on 886 households matched to food prices from a census of geocoded food retailers in Champaign County to approach this question from two perspectives. I first estimate the household’s share of grocery expenditures allocated to fresh, frozen, and canned fruits & vegetables versus other grocery items. I then use data on a person’s residence and geocoded data on food retail locations in Champaign County to test for relationships between retailer proximity, and the share of expenditure on fruits & vegetables. The next perspective uses a choice experiment to measure the tradeoff among store characteristics that determine where a consumer shops. The demand estimation reveals how much fruits & vegetables a person is actually consuming, while the choice experiment reveals whether that individual is constrained in their consumption by their existing characteristic set of stores. I find that while proximity to a grocery store is positively correlated with healthier food consumption, policy response should focus on improving store quality and product quality to induce behavioral change. I further find policy response should be cognizant of endogenous locational sorting which may require alternative means to improve health other than changing the food geography.

Motor intention in the posterior parietal cortex

Investigations on temporal and spatial variation of slope-scale SOC erosion and deposition

Single molecule detection and fluorescence correlation spectroscopy on surfaces

The aim of the present study was to investigate the relationship between body measurements such as body weight, shank, comb and wattle length and semen traits. A total of 33 Indigenous cockerels (Naked Neck, Ovambo and Potchefstroom Koekoek) were used in this experiment. Semen was collected by abdominal massage technique from each individual cockerel. Semen was analysed macroscopically (colour, volume, and pH) and microscopically (sperm concentration and sperm motility) by Computer Aided Sperm Analysis. There were no significant differences on the shank length (SL), comb length (CL) and wattle length (WL) of Naked Neck, Ovambo and Potchefstroom Koekoek cockerels. However, the body weight of Ovambo was significantly (P < 0.05) higher compared to the Naked Neck and Potchefstroom Koekoek cockerels. Semen volume of the Naked Neck was significantly higher (P < 0.05) compared to Ovambo but similar to Potchefstroom Koekoek cockerels. Shank and wattle length were positively correlated with semen volume, sperm concentration and semen pH but negatively correlated with total motility. Furthermore, comb length was positively correlated with semen volume, sperm concentration, semen pH and total motility. In conclusion, South African indigenous cockerel’s body weight and comb length of all three indigenous breeds were positively correlated with total sperm motility, sperm concentration, semen pH and percentage of live normal sperm. However, shank and wattle length were negatively correlated with total sperm motility. Key words: Ovambo, naked neck, potchefstroom koekoek, phenotypic traits, sperm quality.

Single-grain Silicon Technology for Large Area X-ray Imaging

Today, more than 40 million people worldwide are affected by neurodegenerative disorders. Onset of these diseases is associated with insoluble fibrillar protein aggregates, termed amyloids. The molecular origin and the link between amyloid formation and disease aetiology are unclear and there are not are available therapies for these disorders. Strong evidence links propensity of proteins to misfolding and aggregation to the pathological biology implicated in the onset of these diseases. Despite its importance, unraveling amyloids properties and formation is still a formidable experimental challenge, mainly because of their nanoscale dimensions and their heterogeneous and transient nature. Therefore, the investigation of the misfolding of monomers and oligomers into fibrils and their mechanical and structural properties is central to understand their stability and toxicity in the body and to design new therapeutic strategies to the amyloid diseases problem. The main objective of this PhD thesis was the biophysical investigation of amyloids structure and formation at the single scale aggregate. This objective was pursed mainly by the use of both conventional and innovative Atomic Force Microscopy (AFM) methodologies, such as peak force quantitative nanomechanical mapping (PF-QNM) and infrared nanospectroscopy (nanoIR). These methods were assessed to resolve the complex and heterogeneous energy landscape of proteins aggregation and to provide direct information on aggregates properties. Initially, we used AFM to compare the kinetics of aggregation of wild type and mutated forms of huntingtin and a-synuclein. In the first case, we focused on the effects of N-terminal post-translation modifications in the fibrillization. We demonstrated that a phosphorylation of the protein significantly slowed down the aggregation. In the latter case, we investigated wild type and H50Q mutated form of a-synuclein. We demonstrated the strict link between the disease and the mutation, which enhanced aggregation. Successively, we studied the early stages of a-synuclein fibrillization and we showed that the amyloid assembly proceed directly through the formation of single monomeric strands, which hierarchically assembly into the mature fibrils. Moreover, we performed force spectroscopy experiments, which confirmed the non-mature structure of this species and enabled studying their force of interaction with surfaces. Successively, PF-QNM was applied to investigate the mechanical properties of single aggregates forming during fibrillization of amyloid proteins. We demonstrated that I²-sheet content is a major factor determining their intrinsic stiffness. Finally, nanoIR was applied to investigate at the nanoscale the misfolding process and the structure of the species present during the aggregation. The technique proved to be ideal to characterize individually the amyloid species formed by the Josephin domain of ataxin-3. For the first time, we were able to link their nanomechanical properties and secondary structure at the nanoscale. Innovative AFM-based techniques enabled correlating morphological and ultrastructural properties of amyloids at the single aggregate scale. Thus, they represent a future fruitful avenue to unravel protein misfolding process and the mechanisms of amyloid formation. The comprehension of these fundamental processes could allow the design of pharmacological approaches to contrast the onset of amyloid diseases.

Industrial chemical processes may involve thermal risks as most of the reactions performed are exothermic, the chemicals used are often thermally unstable, and the operating conditions are set to induce high conversion and throughput. Besides the reactive steps, all operations from mixing to storage and from processing to transport involving sensitive chemicals should be conducted under strictly controlled conditions ensuring safe operations. Performing an efficient risk assessment and implementing the proper risk mitigation measures are essential to avoid, or at least reduce, accidents and their potentially disastrous consequences. For optimal design and implementation of safety measures, it is important that these considerations are taken into account at early stages of process development. The required data should be made available at the appropriate time so it can be properly accounted for and efficiently serve the design. Yet, at early design phases, some information may be unavailable due to several reasons: the process design being still in development, some parameters can be unknown; experimental analysis of chemicals could be hindered or impossible due to products availability in required quantities; several alternatives are under investigation which raises the necessary resources (time and material) for experimental tests. Predictions would be the appropriate response to such scenario. The aim of this dissertation is to develop predictive models for two hazardous behaviors of chemicals: explosive sensitivity and thermal stability. For the models to be applicable at early development phases, it is preferable to minimize the information feed requirements, and therefore, structure-based approaches are applied. Two methods were identified: Quantitative Structure-Property Relationships (QSPR) and Group Contributions Method (GCM). The hazardous behaviors are studied through characteristic measurements: the Minimal Ignition Energy (MIE) to represent explosive sensitivity and Differential Scanning Calorimetry (DSC) for thermal stability. These measurements are widely employed in safety studies and deliver necessary information to identify potential hazards. Moreover, their specificities call for predictive models: MIE tests require repetitive analysis and hence are time and material consuming; regarding DSC experiments, experts have noted that they seem to exhibit structurally dependent features, and so far no study has comprehensively investigated this phenomenon. This work presents in a first part the structure-based approaches that are applied and the elements of Data Analysis necessary for developing predictive models and simulating experimental results. Secondly, both experimental analysis are detailed and the important information our models should be able to represent will be exposed. Finally, the third and last part is dedicated to the applications: the obtained predictive models are presented, evaluated and discussed. Most of the initial objectives are met as efficient solutions are proposed, nonetheless, some improvement strategies may also be considered.

Catalytic microstructured reactors are becoming widely recognized for their unique properties, such as high surface–to–volume ratios, isothermal conditions due to high heat transfer rates, enhanced safety, and potential applications in chemistry and in chemical industry. The efficient use of microreactors requires shaping of the catalyst usually by deposition of thin catalytic films on microchannel walls. Thin films with large internal surface area can considerably enhance the catalytic surface in the absence of internal mass transfer limitations in the porous structure. As the diffusion of large organic molecules in the porous network is much slower as compared to that observed in gas phase reactions, the maximum catalytic film thickness to avoid internal mass transfer limitations is estimated to be ca. 3 µm. Mesoporous titania thin films doped with metal nanoparticles attract considerable attention in catalysis due to their large surface areas, narrow pore (and particle) size distribution, and favorable surface properties. To obtain the mesostructured materials with required properties it is important to control accurately the synthesis conditions during the preparation of mesoporous catalytic films. Mesoporous films doped with metal nanoparticles were successfully used in a number of reactions, such as reduction of hydrogen peroxide, hydrogenation of acetylene alcohols and ??,??-unsaturated aldehydes and others. Due to a strong metal support interaction between catalytic nanoparticles (Au, Ag, Pd, Pt) and the support, mesostructured titania can prevent metal nanoparticles aggregation and thus improve catalyst stability. This thesis is devoted to preparation of noble metal doped titania films, deposited on the flat plates and within the fused silica microcapillaries. The mesoporous titania coatings were synthesized via the sol–gel method combined with evaporation induced self assembly, which is based on the self–assembling of the structures in the presence of ionic surfactants or block–copolymers. The catalytic films were obtained via direct adding of metal nanoparticles into the titania sol or by adsorption of the metal-organic compounds onto the mesostructured titania films. The catalytic films properties, such as thickness, porosity, particle and pore sizes, and structure, were investigated by a number of techniques (TEM, SEM, ellipsometry, IR, XRD, XPS). The particle size in a nanostructured catalyst, the pore size and the thickness of the mesoporous support can be independently controlled via a one-pot evaporation induced self assembly synthesis. Titania films doped with Au or Pt-Sn nanoparticles were tested in a model reaction of citral hydrogenation into unsaturated alcohols (UCOL). Citral (3,7-dimethyl-2,6-octadienal) is considered as an interesting model molecule since it has three hydrogenation targets: a carbonyl group, a C=C bond conjugated with the carbonyl group, and an isolated C=C bond. However, the citral hydrogenation reaction attracts not only scientific, but also practical interest, since the hydrogenation is an important step in many fine chemical processes. The synthesis of mesoporous TiO2 and Au/TiO2 films is described in Chapter 2. The influence of synthesis parameters, such as the ratio of templating agent/Ti-precursor and pH of initial sol on the structure of the films was studied. The films have been investigated by a number of physico-chemical methods in order to characterize the properties of the mesoporous films. It was found that highly ordered hexagonal mesostructures can be obtained at a certain range of pH values (1.5-1.8) and template/Ti ratios (0.006-0.009). The thickness of the mesoporous titania films was increased from 300 to 1000 nm by a deposition of multi-layer coatings. Gold nanoparticles with an average size of 4.5 nm were embedded in the mesoporous titania films by condensation of metal oxide species via self-assembly in the presence of a known amount of stabilized gold colloids. The complete surfactant removal was achieved at 573 K under a residual pressure of 10 mbar within 4 hrs without destroying the film structure. Under these conditions the Ti4+ sites were reduced to Ti3+ which might be responsible for a high selectivity to UCOL in the hydrogenation of citral over Au-containing supported catalysts. A 300 nm thick Au-containing film showed an initial TOF of 1.4 s-1 and selectivity towards UCOL as high as 90% in the hydrogenation of citral. Thicker films demonstrated a high selectivity towards the saturated aldehyde (above 55%) and a lower intrinsic catalytic activity (initial TOF of 0.7-0.9 s-1) in the absence of internal diffusion limitations. A new approach for predicting the pore size distribution of mesoporous thin films using ellipsometric porosimetry is described in Chapter 3. The method has been developed taking into account multilayer adsorption and capillary condensation phenomena. The improved Derjaguin - Broekhoff - de Boer model (IDBdB) was applied for determination of the mesopore size on titania and silica films with a thickness of ca. 200 nm deposited on a silicon substrates. This approach eliminates uncertainties related to the application of the statistical film thickness determined via t-plots in previous versions of the DBdB model. The deviation in the surface tension of ethanol in the mesopores from that of a flat interface was described by the Tolman parameter. An empirical expression for the disjoining pressure isotherm has been applied to represent the interaction between the adsorbate and the adsorbent. The parameters in the empirical expression have been obtained by fitting the multilayer region of an experimental isotherm on titania and silica films. Using these parameters, the adsorption and desorption isotherms of ethanol were predicted and adjusted to the experimental data by fitting the Tolman parameter of the model, characterizing the surface tension for a curved surface. The IDBdB desorption model with a positive value of the Tolman parameter of 0.2 nm was found to describe accurately (±1%) the pore diameter in a wide range of mesopores from 2.1 to 8.3 nm what was in a good agreement with results obtained by TEM and XRD. The synthesis and characterization of Pt-Sn/TiO2 powder catalysts and catalytic films is presented in Chapter 4. The processing parameters, such as Pt-Sn precursor types, impregnation techniques, adsorption time, were varied. The resulting catalysts were tested in citral hydrogenation reaction. The selectivity to the desired product (UCOL) was found to be ca. 90% at a citral conversion above 95%. A reaction rate in terms of TOF of 0.2 – 3.3 min-1 was observed in the citral hydrogenation over the Pt-Sn/TiO2 powder catalysts. The highest activity was observed in the case of catalysts prepared by co-impregnation in comparison with the catalysts prepared via organometallic route and successive impregnation, what could be attributed to an intimate contact between the metals. The Pt-Sn/TiO2 films were prepared via i) one-pot synthesis using Pt-Sn colloids or clusters, and ii) adsorption of Pt-Sn clusters into the mesoporous titania films. The activity and selectivity of Pt-Sn/TiO2 films strongly depend on the precursor type and adsorption time (in case of clusters). The highest UCOL yield (72%) was observed in the case of a two layer catalytic film obtained from Pt-Sn clusters solution with adsorption time of 5 hrs. Chapter 5 is focused on the demonstration of the potential of capillary microreactors by the results obtained in a selective hydrogenation of citral to UCOL. The Au/TiO2 sol was impregnated by dip-coating into the fused silica capillary with a length of 10 m and internal diameter of 250 µm. A Pt-Sn/TiO2 wall-coated capillary was made by an impregnation of Pt-Sn clusters into the capillary preliminary coated with a titania layer. Both capillaries were tested in the citral hydrogenation reaction. The influence of the reaction conditions, such as liquid flow, reaction temperature, hydrogen partial pressure, on the catalytic properties was investigated. The detailed analysis of kinetics is presented. The Pt-Sn/TiO2 coated capillary shows better catalytic properties in comparison with the Au/TiO2 coated one. The maximal yield of UCOL was found to be 79 and 29% for Pt-Sn/TiO2 and Au/TiO2 catalysts, respectively. The reaction has first and zero order in hydrogen and citral, respectively. The synthesis and characterization of a new type of catalyst – ZnO nanowires doped with Pd nanoparticles – is presented in Chapter 6. The ZnO nanowires were made by the atomic layer deposition technique. Pd nanoparticles with average sizes of 2.7 and 4.5 nm were impregnated from the Pd colloids solutions. The catalysts were tested in the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE). The effect of the solvent, hydrogen pressure and reaction temperature on the MBE yield was investigated. ZnO nanowires possess 88% selectivity to MBE at 99% MBY conversion at 5 bar hydrogen pressure and 323K and show no deactivation after 20 runs of the reaction. The Pd/ZnO nanowires catalyst shows 94% yield of MBE in the first run of the reaction. Catalytic tests performed in water and in a methanol–water (3:1 vol.) mixture led to sintering of the Pd particles decreasing both the activity and selectivity. The ZnO NWs were rather stable in water which is promising for further optimization of their activity and stability using highly polar solvents. A kinetic model is proposed to explain activity and selectivity of the ZnO and Pd/ZnO nanowires catalysts. Finally, in Chapter 7 the main conclusions of the previous chapters are summarized.

Objective To analyze and compare the correlation between thromboelastography and routine coagulation function, inflammatory index and blood gas analysis of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients during hospitalization. Methods From August 2016 to January 2019, a retrospective cross-sectional study was carried out on 40 AECOPD patients admitted to the emergency department of Shanghai Oriental Hospital or the Emergency Intensive Care Unit, including 23 males and 17 females, aged 58-95 years, with average 79.75 years in 23 males and 17 females to analyze the correlation between TEG and coagulation index, blood gas analysis, inflammatory index; kappa analysis was used to evaluate the consistency between TEG and coagulation function. Results The K value of AECOPD patients was negatively correlated with FIB (r=-0.42), positively correlated with APTT (r=0.67), TT (r=0.49); R value was positively correlated with APTT (r=0.49), α angle was positively correlated with FIB (r=0.39), and negatively correlated with APTT (r=-0.61); Ma was positively correlated with FIB (r=0.68), and negatively correlated with APTT (r=-0.60) and TT (r=-0.37); Ci was positively correlated with FIB (r=0.41), and negatively correlated with APTT (r=-0.69) and TT (r=-0.37). The difference was statistically significant (P<0.05). The kappa values of FIB, K and MA were 0.35 and 0.47, respectively, with statistical significance (P<0.05); The kappa values of APTT, K value, R value, Ma value and α angle were 0.48, 0.49, 0.31 and 0.33 respectively, the difference was statistically significant (P<0.05). In addition, MA was positively correlated with CRP (r=0.39). The indexes of TEG were also correlated with the indexes of arterial blood gas analysis: K value was negatively correlated with pH value of arterial blood (r=-0.36), positively correlated with PaCO2 (r=0.37) and Lac (r=0.48); R value was negatively correlated with pH value of arterial blood (r=-0.39), positively correlated with PaCO2 (r=0.35), and α angle was negatively correlated with lac level of arterial blood (r=-0.45); MA was positively correlated with PaO2 (r=0.33) and negatively correlated with lac (r=-0.42); CI was positively correlated with arterial pH (r=0.37), negatively correlated with PaO2 (r=-0.37) and Lac (r=-0.41), and the difference was statistically significant (P<0.05). Conclusion The thromboelastography of patients with AECOPD has a certain correlation with coagulation parameters, C-reactive protein, and blood gas analysis indicators, and it has practical implications for assessing coagulation, inflammation, and internal environmental conditions in patients with AECOPD. Key words: Thromboelastography; Acute exacerbation of chronic obstructive pulmonary disease; Coagulopathy dysfunction

Exciton-polarons in self-assembling helical aggregates: relating optical properties to supramolecular structure

In the Ulten Zone (Upper Austroalpine), small bodies of mantle peridotites are incorporated within high-grade basement rocks (gneisses and migmatites) which represent remnants of lower crust subducted and reequilibrated at eclogite- facies conditions during the Variscan orogenic cycle. The Ulten peridotites record a complex metamorphic and deformative evolution, which is testified by the transition from coarse-grained protogranular spinel-bearing peridotites, to fine-grained garnet and amphibole (Ca-hornblende) -bearing peridotites with porphyroclastic to mosaic granoblastic textures. Thermometric estimates on the coarse-type spinel lherzolites have yielded high temperatures of equilibration, in the range 1100-1300°C (Obata and Morten, 1987). In the porphyroclastic peridotites, the metamorphic recrystallization to (garnet + amphibole)-facies conditions is evidenced by the development of: i) garnet coronas around spinel, ii) fine-grained granoblastic aggregates made by olivine + garnet + Ca-hornblende + new pyroxenes, iii) garnet and Ca-hornblende exsolutions within primary spinel-facies clino- and ortho-pyroxenes. The P-T conditions of the high-pressure eclogitic recrystallization which produced the spinel- to garnet-facies transition have been recently estimated to 850°C and 27 kbar (Nimis and Morten, 1999). The peculiar thermobarometric reequilibration recorded by the Ulten peridotites has been interpreted as the result of a wedge to slab evolution (Nimis and Morten, 1999; Godard et al., 1996). In this scenario, the spinel peridotites represent portions of a mantle wedge which were incorporated (by convection ) in a downgoing slab of cold continental crust, and were then subducted together with the slab to depths of about 90 km. Entrainment in the cold slab and subduction caused the reequilibration of the peridotites at 850°C and 27 kbar. The metamorphic transition from spinel- to garnetbearing assemblage occurred therefore in a dynamic regime, and was accompanied by significant input of metasomatic fluids, as testified by the crystallization of abundant amphibole in the garnet-bearing high-pressure assemblage. Petrologic investigations on the host gneissic basement rocks have evidenced that they also experienced high-pressure recrystallization, which was accompanied by in-situ partial melting and migmatization (Godard et al., 1996). The particular geodynamic evolution of the Ulten peridotites thus offer the unique opportunity to investigate the effects of crustal-derived metasomatism on mantle rocks involved in a subducting environment. Previous whole-rock chemical and isotopic investigations on the Ulten peridotites have evidenced that the fine-type garnet-facies ultramafics are enriched in LREE, K, Sr and that the alkalis enrichment is positively correlated with the 87Sr/86Sr ratios. In this study, we present the results of detailed in situ investigations (performed by the ion microprobe operating at CSCC, Pavia, Italy) on the trace element chemistry of the main mineral phases (clinopyroxene, amphibole and garnets) from seven selected samples representative of the various stages of the tectonometamorphic evolution recorded by the peridotites. Major aims have been to investigate the geochemical signature of fluids responsible of the amphibole crystallization, and provide further constraints on the nature of the metasomatic processes. The data obtained are potentially usefull to characterize, by direct evidence, the chemical changes induced in mantle rocks by crustal metasomatism. The coarse-type spinel peridotites, which are relics of the “pre-subduction”, mantle-wedge equilibration stage, display modest metasomatic effects. In these samples, modal metasomatism is only recorded by the incipient crystallization of amphibole as rims around clinopyroxene. Clinopyroxenes have almost flat REE spectra (CeN/SmN = 0.76-0.87) at 4-8 x C1 values, or display concave shape with selective LREE enrichment (CeN/SmN = 2.50-4.50, SmN/YbN = 0.53-0.97). The REE concentrations of amphiboles are very similar to those of clinopyroxenes. Both amphiboles and clinopyroxenes in sample MK5D, a coarse-type garnet-bearing peridotite, exhibit a convex-upward REE pattern characterized by LREE and HREE depletion (CeN/SmN = 0.17-0.19; SmN/YbN = 3.07-6.13). Their low HREE abundances are due to the equilibration with garnet which, as expected, show severely fractionated patterns (CeN/YbN < 0.001; HREE at about 20-30 x C1). Amphiboles, in the coarse-type rocks, also show low Sr (18-35 ppm) and K (171-964 ppm) abundances. The most evident metasomatic effects are recorded by the eclogite-facies recrystallized fine-type peridotites. In these rocks, modal metasomatism is documented by abundant crystallization of amphibole (Ca-hornblende, Mg values: 90- 92) in equilibrium with garnet. In some samples, the gnt+cpx+amph+opx+ol assemblage is replaced by amph+opx+ol assemblages, this feature indicating progressive degrees of hydration. Amphiboles display significant LREE enrichment (CeN/YbN = 3.90-11.50; LREE in the range 20-50 x C1) and high Sr (150-250 ppm), K (1910- 7280 ppm) and Ba (280-800 ppm) contents. By contrast, they have relatively low concentrations in HFSE (e.g., Zr = 14-25 ppm, Y = 6.7-16 ppm, Ti = 1150-2500 ppm, Nb = 2-7 ppm). The geochemical signature recorded by amphibole in the fine-type peridotites, i.e. the strong enrichment in LILE relative to HFSE, is a peculiar feature of crustal-derived metasomatic agents. The lack of evidence of major element modifications in mantle minerals (e.g. Mg-value decrese, crystallization of orthopyroxene around olivine) strongly suggest that the metasomatic agent was an hydrous fluid rather than a silica-rich melt. Moreover, experimental studies have demonstrated that aqueous fluids preferentially partition elements like alkalies, Ba, Sr and Pb, whereas they have scarce affinity for HFSE. The results of our study therefore indicate that the chemical modifications occurred in the Ulten peridotites during the high-pressure reequilibration were most likely produced by the input of hydrous, LILE-enriched, fluids, which caused crystallization of abundant amphibole. Such H2O-rich fluids could represent the residual fluids left after the crystallization of leucosomes, starting from water-undersaturated melts produced during migmatization of the host gneisses.