1,326 research outputs found
Study and Production of Special Targets for DCE Reactions with 0vbb-Decay Final States in the NUMEN Experiment
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
SPATIAL VARIABILITY AND ADAPTATION OF MEDITERRANEAN CORALLIGENOUS REEFS IN THE CURRENT AND GLOBAL WARMING SCENARIO
No full textVariability in temperature explains much of the spatial and temporal patterns we observe in the distribution and abundance of species worldwide. Taking advantage of the natural differences in temperature conditions between different biogeographical regions in Sardinia (Italy) the present Doctoral Dissertation aims to estimate the spatial variability, and adaptation of an iconic habitat of the Mediterranean Sea, the coralligenous reefs, both under current conditions and into global warming scenario, focusing in particular on one of the most important bio-constructor of the coralligenous habitat, the crustose coralline algae Lithophyllum stictiforme. The main questions that triggered my research hypothesis are: i) Does the structure of coralligenous assemblages change spatially in different biogeographic areas of Sardinia? ii) Is the spatial variation of the structure of coralligenous assemblages consistent through depth? iii) Is it possible to relate and thus predict differences in habitat structure based on thermal environment? iii) What is the response of one of the main builders of this habitat, the coralline algae L. stictiforme, to warming? In order to answer these questions, four studies, three descriptive and one manipulative, were conducted.In Chapters 1 and 2, the spatial variability of the deep coralligenous assemblages in different biogeographical areas around Sardinia and the vertical distribution of the coralligenous cliff in three different biogeographical areas of the Mediterranean Sea was evaluated, respectively. The observed variations seem largely related to biogeographic patterns rather than spatial distance and the results support the hypothesis that coralligenous assemblages, unaffected by local anthropogenic disturbance, may be relevantly different in structure and indicate that the lack of iconic species such as gorgonians and bryozoans, could merely be the result of biogeographic models probably related to the thermal environment.In Chapter 3, the knowledge of the subtidal climatology has been improved to be able to identify temperature descriptors that can be useful predictors in the structure of the coralligenous community and evaluate the relationship between the subtidal temperature and the change in the community structure. The aims were twofold: i) to evaluate if such heating descriptors can be useful predictors of the coralligenous reef community structure, ii) to identify the structure and the taxa of the community associated with the current heating events, so to provide tools to draw the trajectories of change of this community due to future warming scenarios. All the heating descriptors selected influenced several coralligenous response variables so that they all might be considered useful predictors for climate change investigations on the coralligenous reef.Finally, in Chapter 4, manipulative experiments on L. stictiforme were performed for the first time in the field to examine the temperature effects on the performance of the algae. Two experiments were done: in the first, algae were cross transplanted from a cold site to a warmer one and vice versa using two different depths, while in the second, transplants were done from 34 m to 15 m of depth within the same site to evaluate the influence of the thermocline, which is predicted to be increasingly deeper and persistent due to global warming. The main goal was to understand if L. stictiforme is adaptable to different thermal environments and identify the changes in thallus performance due to the different temperatures. An increase in temperature positively affected the alga responses, highlighting an unexpected adaptability of this crustose coralline alga and providing useful information to forecast the effects of warming and thermocline deepening on this habitat bio-constructor and to draw up future guidelines for restoration efforts of the coralligenous habitat
Automatic Extraction of Pinna Edges for Binaural Audio Customization
No full textThe contribution of the external ear to the headrelated transfer function (HRTF) heavily depends on the listener's unique anthropometry. In particular, the shape of the most prominent contours of the pinna defines the frequency location of the HRTF spectral notches along the elevation angle. This paper addresses the issue of automatically estimating the location of pinna edges starting from a set of pictures produced by a multi-flash imaging device. A basic image processing algorithm designed to obtain the principal edges and their distance to the ear canal entrance is described. The effectiveness of the designed hardware and software is preliminarily evaluated on a small number of test subjects
Structural modeling of pinna-related transfer functions.
No full textThis paper faces the general problem of modeling pinna-related transfer functions (PRTFs) for 3-D sound rendering. Following a structural modus operandi, we exploit an algorithm for the decomposition of PRTFs into ear resonances and frequency notches due to reflections over pinna cavities in order to deliver a method to extract the frequencies of the most important spectral notches. Ray-tracing analysis reveals a convincing correspondence between extracted frequencies and pinna cavities of a bunch of subjects. We then propose a model for PRTF synthesis which allows to control separately the evolution of resonances and spectral notches through the design of two distinct filter blocks. The resulting model is suitable for future integration into a structural head-related transfer function model, and for parametrization over anthropometrical measurements of a wide range of subjects
Frequency Estimation Of The First Pinna Notch In Head-Related Transfer Functions With A Linear Anthropometric Model
No full textThe relation between anthropometric parameters and Head-Related Transfer Function (HRTF) features, especially those due to the pinna, are not fully understood yet. In this paper we apply signal processing techniques to extract the frequencies of the main pinna notches (known as N1, N2, and N3) in the frontal part of the median plane and build a model relating them to 13 different anthropometric parameters of the pinna, some of which depend on the elevation angle of the sound source. Results show that while the considered anthropometric parameters are not able to approximate
with sufficient accuracy neither the N2 nor the N3 frequency, eight of them are sufficient for modeling the frequency of N1 within a psychoacoustically acceptable margin of error. In particular, distances between the ear canal and the outer helix border are the most important parameters for predicting N1
Estimation and modeling of pinna-related transfer functions.
No full textThis paper considers the problem of modeling pinna-related transfer functions (PRTFs) for 3-D sound rendering. Following a structural modus operandi, we present an algorithm for the decomposition of PRTFs into ear resonances and frequency notches due to reflections over pinna cavities. Such an approach allows to control the evolution of each physical phenomenon separately through the design of two distinct filter blocks during PRTF synthesis. The resulting model is suitable for future integration into a structural head-related transfer function model and parametrization over anthropometrical measurements of a wide range of subjects
Peritoneal seeding from appendiceal carcinoma: A case report and review of the literature
No full textNon-carcinoid appendiceal malignancies are rare entities, representing less than 0.5% of all gastrointestinal malignancies. Because of their rarity and particular biological behavior, a substantial number of patients affected by these neoplasms do not receive appropriate surgical resection. In this report, we describe a rare case of primary signet-ring cell carcinoma of the appendix with peritoneal seeding which occurred in a 40-year old man admitted at the Emergency Surgery Department with the clinical suspicion of acute appendicitis. After a surgical debulking and right hemicolectomy, the patient had systemic chemotherapy according to FOLFOX protocol. After completion of the latter, the patient underwent cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy. This report offers a brief review of the literature and suggests an algorithm for the management of non-carcinoid appendiceal tumors with peritoneal dissemination
Extraction of pinna features for customized binaural audio delivery on mobile devices
No full textThe paper presents a system for customized binaural audio delivery based on the extraction of the relevant features from a 2-D representation of the listener’s pinna. A procedure based on multi-flash imaging for recognizing the main contours of the pinna and their position with respect to the ear canal entrance is detailed. The resulting contours drive the parametrization of a structural head-related transfer function model that performs in real time the spatialization of a desired sound file according to the listener’s position with respect to the virtual sound source, tracked by sensor-equipped headphones. The low complexity of the model allows smooth implementation and delivery on any mobile device. The purpose of the desired system is to provide low-tech custom binaural audio to any user without the need of tedious and cumbersome subjective measurements
Realizzazione in tmpo rele di filtri IIR risonanti in un modello di filtraggio acustico dell'orecchio per il rendering spaziale del suono
No full textIl progetto presentato in questa tesi si inserisce all'interno di un progetto più ampio per il rendering spaziale del suono tramite tecniche binaurale e consiste nell'implementazione di due filtri di sintesi delle PRTF (Pinna-Related Transfer Function)
in Pure Data: un'ambiente di elaborazione digitale audio e video in tempo reale. Le PRTF sono delle funzioni che indicano il contributo della pinna nelle HRTF(Head-Related Transfer Function). Le HRTF hanno il compito di “catturare” le
trasformazioni subite da un'onda sonora nel tragitto dalla sorgente ai timpani, dovute ai fenomeni di diffrazione e riflessione del corpo dell'ascoltatore (testa, torso, pinna e
spalle). Poiché sono un insieme di diversi contributi molti complessi da valutare a livello globale, si cerca un'astrazione arrivando al modello strutturaleope
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