Littérature scientifique sur le sujet « Iben »

Over the past decade a comprehensive, semiquantitative theoretical scenario for the final evolutionary stages of low and intermediate mass stars has been progressively elaborated and refined. It concerns the envelope ejection terminating the Asymptotic Giant Branch (AGB) phase, the AGB to Planetary Nebula (PN) transition, the fading and possible rejuvenation of PN nuclei, the formation processes of hydrogen-deficient stars, and the final production of white dwarfs (WD) of the DA and non-DA varieties (Renzini 1979, 1981a, 1981b, 1982, 1983, Iben & Renzini 1983, Iben et al. 1983, Iben 1984, 1985, 1987, Iben & Tutukov 1984, Iben & MacDonald 1985, 1986). In developing this scenario several important results of stellar evolution and hydrodynamical calculations have been incorporated, including in particular those of Paczynski (1971), Wood (1974), Härm & Schwarzschild (1975), Schönberner (1979, 1983), and Tuchman, Sack & Barkat (1979).

The present investigation reports the results of a content analysis of U.S. newspaper portrayals of the 1991 earthquake prediction by Dr. Iben Browning. Results suggest that journalists wrote stories which readers may have interpreted as advocating a belief in Browning's prediction. Specifically, news stories were found to be more subjective than objective, and more supportive than critical, of both Iben Browning and his theory.

Ever since the pioneering work of Schönberner (1979, A&A, 79, 108) and Iben (1984, ApJ, 277, 333) who showed that the evolution of post-AGB remnants might be affected by late thermal pulses of the helium-burning shell, resulting in a temporary growth of these objects to red giant dimensions, many attempts were made to explain a number of puzzling objects, among them the well-known variable central star FG Sge as well as the R CrB and PG 1159 stars, by this so-called “born-again AGB” scenario (Iben et al. 1983, ApJ, 264, 605; Iben & MacDonald 1995, in: White Dwarfs, Springer, p. 48). However, it is still not clear if the frequency of occurrence of such events is high enough as to be consistent with the number of born-again candidates. This is due to the very short evolutionary timescales during the pulse and the character of the post-pulse evolution which resembles the first post-AGB phase and makes it difficult for an observer to distinguish such objects from “normal” central stars.

The hypothesis that Type I supernova explosions originate in binary stars, in which the secondary overflows its Roche lobe and causes a white dwarf primary to pass a critical threshold for dynamical collapse, has gained in popularity over the last decade and a half (Truran and Cameron 1971; Whelan and Iben 1973; Wheeler 1982). During this period attention has also focussed on double-degenerate binary precursors of such systems, in which gravitational radiation of orbital angular momentum causes two white dwarf stars to spiral slowly together until the less massive of the stars begins to overflow its Roche lobe (Tutukov and Yungelson 1979; Webbink 1979; Iben and Tutukov 1984; Paczyński 1985). Cameron and Iben (1986) discussed the stability of such systems as the threshold of Roche lobe overflow was approached and for low mass ratios in which gravitational radiation can maintain a low rate of such overflow. Benz, Bowers, Cameron, and Press (1988, hereafter BBCP) computed the actual merging of a binary system composed of a 1.2M© primary and a 0.9M© secondary using a fully three-dimensional SPH code. Their simulation did not include the effect of nuclear energy release despite the fact that the temperature in the accretion shock reached the carbon ignition threshold, and therefore their conclusions about the structure of the merged object remained uncertain.

Our understanding of the evolution of Central Stars of Planetary Nebulae (CPN) has made considerable progress during the last years. This was possible since consistent computations through the asymptotic giant branch (AGB), with thermal pulses and (in some cases) mass loss taken into account, became available (Schönberner, 1979, 1983; Kovetz and Harpaz, 1981; Harpaz and Kovetz, 1981; Iben, 1982, 1984; Wood and Faulkner, 1986). It turned out that the evolution depends very sensitively on the inital conditions on the AGB. More precisely, the evolution of an AGB remnant is a function of the phase of the thermal-pulse cycle during which this remnant was created on the tip of the AGB by the planetary-nebula (PN) formation process (Iben, 1984, 1987). This was first shown by Schönberner (1979), and then fully explored by Iben (1984). In short, two major modes of PAGB evolution to the white dwarf stage are possible, according to the two main phases of a thermally pulsing AGB star: the hydrogen-burning or helium-burning mode. If, for instance, the PN formation, i.e. the removal of the stellar envelope by mass loss, happens during a luminosity peak that follows a thermal pulse of the helium-burning shell, the remnant leaves the AGB while still burning helium as the main energy supplier (Härm and Schwarzschild, 1975). On the other hand, PN formation may also occur during the quiescent hydrogen-burning phase on the AGB, and the remnant continues then to burn mainly hydrogen on its way to becoming a white dwarf.

From 21 October to 6 November 2005, Odin Teatret, comprising director Eugenio Barba, actors Augusto Omolù, Julia Varley, Iben Nagel Rasmussen, Roberta Carreri, Torgeir Wethal, Tage Larsen, Jan Ferslev, Kai Bredholt, Frans Winther, and administrator Patricia Braga Alves, toured the UK with their ensemble performance Inside the Skeleton of the Whale. The company also presented performance demonstrations, workshops, masterclasses, conferences, seminars, and lectures.

We examine the results of s-Processlng occurring in a low mass star of low metallicity during the pulsed He-instability in AGB phases by comparing them with the s-Classical analysis. Neutron exposures are provided by the C13(Alpha, N)016 reaction, according to the mechanism suggested by Iben and Renzini (1983) for the formation in the interpulse phase of a small zone rich of C13 and its subsequent ingestion in the next pulse.

Examination of 227 samples of milk and dairy products for Listeria monocytogenes showed that raw milk and some Moroccan traditionally made dairy products such as Iben and raib (fermented milks) and jben (fresh cheese) were contaminated with this pathogen. L. monocytogenes was the only Listeria species isolated except in one case in which it was associated with Listeria innocua. Pasteurized milk, fresh cream, and fresh and ripened cheeses (industrially made) were free from L. monocytogenes.

A study of three newspapers that primarily serve the New Madrid Fault area shows that the press and public officials probably share the blame for public panic surrounding the 1990 Iben Browning earthquake prediction. The press failed to report soon enough scientists’ views that refuted Browning's prediction, and some public officials used mass media to promote earthquake awareness even though the tactics fed public misperceptions about the likelihood of Browning's prediction coming to pass.

Escherichia coli est une espèce bactérienne à multiples facettes. En effet, certaines souches sont présentes à l’état commensal au niveau intestinal, ou sont utilisées comme probiotiques. À l’inverse, d’autres souches sont responsables d’infections intestinales ou extra-intestinales chez l’Homme et les animaux à sang chaud. Les souches d’E. coli pathogènes extra-intestinales (ExPEC) sont responsables de nombreuses maladies infectieuses (méningites néo-natales, infections urinaires, septicémies ou infections respiratoires). Plusieurs facteurs de virulence ont été identifiés chez les souches ExPEC (adhésines, invasines…) et notamment la protéine IbeA, mise en évidence dans une souche isolée d’un cas de méningite néo-natale humaine. Le gène ibeA est retrouvé chez différentes souches ExPEC, dont certaines d’origine aviaire. Il est localisé au sein de l’îlot génomique GimA, sur un des quatre opérons de cet îlot, entre ibeR codant un potentiel régulateur et ibeT codant un potentiel antiporteur. La protéine IbeA a été décrite comme jouant un rôle dans l’invasion bactérienne des cellules endothéliales microvasculaires de cerveau humain (HBMEC). Afin de mieux comprendre le rôle d’IbeA dans le processus infectieux et l’invasion cellulaire, nous avons étudié l’implication d’IbeA dans l’adhésion de la souche ExPEC d’origine aviaire BEN2908 puis tenté de déterminer la localisation de cette protéine et son lien avec la protéine IbeT. L’étude phénotypique comparative de la souche BEN2908 et de son mutant ?ibeA nous a montré qu’IbeA intervenait dès le stade de l’adhésion aux HBMEC. Des tests d’adhésion en absence des fimbriae de type 1 (adhésine majeure de notre souche) nous ont montré que dans ce contexte, IbeA n’avait pas d’action sur l’adhésion. Ce résultat nous a suggéré qu’il pouvait y avoir une baisse d’expression des fimbriae de type 1 à la surface bactérienne dans un mutant ?ibeA, ce que nous avons montré par dots blots. Pour comprendre comment IbeA entraînait une modification de l’expression des fimbriae de type 1, nous nous sommes intéressés au contrôle de l’expression des gènes de l’opéron fim. Nous avons ainsi montré que le promoteur de ces gènes, localisé sur un élément invertible, était préférentiellement dans une orientation ne permettant pas la transcription des gènes fim dans un mutant ?ibeA. Nous avons ensuite mis en évidence chez le mutant ?ibeA une baisse de l’expression des gènes fimB et fimE qui codent pour deux recombinases participant au contrôle de l’orientation de l’élément invertible. Ces baisses d’expression de fimB et fimE pourraient expliquer la diminution d’expression des fimbriae de type 1 dans le mutant ?ibeA. Enfin, des phénotypes similaires à ceux du mutant ?ibeA ont été observés chez un mutant ?ibeT. La localisation d’IbeA est indispensable pour comprendre comment cette protéine peut agir sur l’expression des recombinases FimB et FimE. Nous avons localisé IbeA dans le compartiment cytoplasmique, mais l’incertitude sur la fonctionnalité d’IbeA dans les constructions génétiques utilisées nécessite de confirmer ces premiers résultats. Enfin, nous avons recherché un rôle métabolique pour IbeA et IbeT étant données les homologies d’IbeT avec des transporteurs de composés carbonés. Nous avons observé qu’un mutant ?ibeT présentait un retard de croissance par rapport à la souche sauvage et au mutant ?ibeA dans des cultures en milieu minimum avec du fumarate, du succinate, du malate ou de l’aspartate comme seule source de carbone. Ces résultats suggèrent un lien entre le métabolisme de certains dicarboxylates, l’expression des fimbriae de type 1 et les protéines IbeA et IbeT. Ils ouvrent de nombreuses perspectives pour la compréhension du mécanisme d’action d’IbeA et IbeT
Escherichia coli is bacterial species with multiple facets. Indeed, some strains are present at a commensal state in the intestinal tract of humans and warm-blooded animals, or are used as probiotics. Conversely, other strains are responsible for intestinal or extra-intestinal infections in Humans and warm-blooded animals. Extra-intestinal pathogenic E. coli (ExPEC) strains are responsible for multiple infectious diseases (neonatal meningitis, urinary tract infections, septicaemias or respiratory infections). Several virulence factors have been identified in ExPEC strains (adhesins, invasins,…) and notably the IbeA protein, originally identified in a strain isolated from a case of human neonatal meningitis. The ibeA gene is found in different ExPEC strains, of including strains avian origin. It is located on one of the four operon of the GimA genomic island, between ibeR coding a putative regulator and ibeT coding a putative antiporter. The IbeA protein is known for its role in bacterial invasion of human brain microvascular endothelial cells (HBMEC). In order to better understand the role of IbeA in the infectious process and cellular invasion, we have studied the involvement of IbeA in adhesion of the avian pathogenic E. coli strain BEN2908 and attempted to determine the localisation of this protein and its link with the IbeT protein. The comparative henotypic study of strain BEN2908 and its ?ibeA mutant showed that IbeA was involved in the adhesion to HBMEC. Adhesion tests in the absence of type 1 fimbriae ( the major adhesin of our strain) showed that IbeA did not have a direct role in adhesion in this context. This result suggested there could be a decrease in type 1 fimbriae expression at the bacterial surface in the ?ibeA mutant. This was demonstrated by dot blots. To understand how IbeA led to a modification of type 1 fimbriae, we investigated the role of IbeA in the control of the expression of genes that belong to the fim operon. Thus we showed that the promoter of these genes, located on an invertible element, was preferentially in an orientation preventing transcription of the fim genes in the ?ibeA mutant. Then, we highlighted in the ?ibeA mutant, a decrease of expression of the fimB and fimE genes encoding two recombinases involved in the orientational control of invertible element. These decreases of fimB and fimE expression could explain the reduction of type 1 fimbriae expression in the ?ibeA mutant. Lastly, phenotypes similar to that of the ?ibeA mutant were observed in a ?ibeT mutant. The localisation of IbeA is necessary to understand how this protein can act on fimB and fimE expression. We localised IbeA in the bacterial cytoplasm, but the doubt on the functionality of IbeA in the genetic constructions used demands that these results be confirmed. Finally, we have looked for a metabolic role for IbeA and IbeT, given the IbeT homology with carbon compound transporters. We have observed that, in minimal broth with fumarate, succinate, malate or aspartate as sole carbon sources, the ?ibeT mutant presented a lower growth rate than the wild type strain and ?ibeA mutant. Altogether, these results suggest a link between metabolism of dicarboxylates, type 1 fimbriae expression and IbeA and IbeT proteins. They open numerous perspectives for the comprehension of IbeA and IbeT mechanisms

The three studies reported in this thesis have been conducted on the Alpine ibex population of the Marmolada-Monzoni, in the north-eastearn Italian Alps. A summary for each study is given below. Chapter I: Land morphology, season and individual activity influence GPS fix acquisition rates and location error in an alpine ungulate. The use of GPS technologies in wildlife research has greatly increased the opportunities for addressing ecological issues that affect ultimately the conservation of the species. However, in order to formulate accurate and unbiased conclusions in studies of movement ecology with GPS-tracking systems, it is necessary to understand the sources of potential bias and error associated with this technology, under specific environmental conditions and taking into account the behavioural patterns of the species monitored. In chapter I, I first present the results of a field trial with stationary collars scheduled to attempt a location fix every 30 min during 24 hours cycles. The collars were positioned in 64 locations throughout the study area in order to sample different land cover categories and topographic conditions. GPS collars performances were influenced mainly by available sky view. When sky view was higher than 70%, acquired as respect to scheduled locations were close to 100%, and location accuracy was within 10 m for 75% of acquired locations. When sky view was below 70 %, the proportion of acquired locations dropped to 75% and location error increased to within 20 m for 75% of locations acquired. I then examined a database of more than 90.000 attempted locations from 11 GPS-tagged females of Alpine ibex to assess the temporal trends in fix acquisition rate, and how it was influenced by habitat features of daily areas used, by individual activity, and by climate and weather variables. I found that fix acquisition rate was very good and scarcely variable in summer, but could drop to less than 85% during the coldest months and at night in winter. Fix acquisition rate was strongly and positively influenced by individual activity and declined, especially in winter, in periods of adverse weather and lower than average temperatures. Most probably female ibex, when inactive and seeking for shelter, use microhabitats providing cover that obstructs the satellites signal, so reducing fix acquisition rate. I concluded that, although with an adequate screening procedure for identifying outliers the accuracy of locations received from different habitat conditions may remain good, the acquired locations underestimate the use of habitats providing shelter and the periods of adverse weather. In general, the results underline the importance of combining stationary tests with tests on free-ranging animals when assessing GPS bias and accuracy in field conditions. Chapter II: Determinants of home range size across spatio-temporal scales in a high mountain ungulate. The high seasonality of Alpine habitats might have strong effects on the spatial strategies of large herbivores. In the second chapter, I obtained a database of 672 estimates of weekly home ranges (232 in summer and 440 in winter) and 160 estimates of monthly home ranges (64 in summer and 96 in winter) from 15 female ibexes, and analysed it to describe intra-annual patterns of spatial use and to asses how it was influenced by climate, food resources and individual conditions. I used the k-LoCoH method to calculate the areas used at two spatial scales: the home range (HR; calculated on 95% of locations) and the core area (CA, calculated on 50% of the locations). At all temporal and spatial scales, the areas used by females were very small in deep winter, progressively increased until a peak in mid-summer, and then dropped again. This pattern was very marked, with a 15-20-fold increase in size from the winter minimum to the summer maximum. The HR and CA size was positively correlated with daylight, but was more synchronized with indexes of climate and vegetation phenology, as absolute temperature and average NDVI of the study area. After having defined biologically meaningful seasons with a clustering approach based on step distances and habitat features associated with locations, I then analysed, within seasons and correcting for temporal trends, the effects of the stochastic variability of climatic and weather conditions and of food resources on the size of ranges used. I found that, in winter, HRs and CAs at all temporal scales decreased strongly when snow was deeper, or precipitations more abundant, while in summer they decreased with increasing food resources (indexed by the average NDVI value or proportion of vegetation in the HRs or CAs). Also slope, which I used as an index of refuge areas from predators but also of snow accumulation, had a marked negative effect on the size of areas used. In contrast, individual conditions, as age class and reproductive status, did not influence with consistent patterns the spatial behaviour of females. These results highlight the peculiar strategy of spatial use of female ibex, which appear to be extremely energy conservative in winter and aimed at optimizing the use of food resources in summer. The understanding of factors driving spatial behaviour of female ibex is fundamental to conserve key wintering areas and habitats, and to predict how future climate changes might impact on the species. Chapter III: Validation of a non-invasive technique for estimating diet quality in an alpine ungulate. In seasonal environments, the behavioural patterns of large herbivores are shaped by the availability of forage resources, which affect the individual performance and reproduction success. Faecal nitrogen (FN) and Faecal Neutral Detergent Fibre (FNDF) have been proposed as indicators of diet quality in wildlife species. In the study reported in chapter III, I aimed at evaluating the use of faecal N, and secondarily of faceal NDF, to describe patterns of diet quality in Alpine ibex. Since chemical analyses are costly and time consuming, I also verificed whether NIRS estimates of faecal N might provide results as accurate as those of chemical analyses. From late June to November, I collected fresh samples of female and male ibex faeces, which were analyzed for FN and FNDF using Chemical analysis and three different NIRS instruments with variable wavelength ranges and approach (reflectance or transmittance). In order to verify possible relationships, I also associated to each sample the NDVI index of greenness of a surrounding buffer area. NIRS analyses gave good predictions for N, and only slightly lower for NDF, provided that the instrument used operated over a wide spectral range and in reflectance. Faecal N decreased, and FNDF increased, with Julian date, suggesting a reduction in diet quality thorugh summer and autumn. Females tended to have higher FN and lower FNDF contents than males, suggesting the ability to select a diet of better quality. These patterns were best described by data from chemical analyses, but were closely approximated by those from the best NIRS method. The NDVI of the buffer area surrounding faecal samples did not influence indexes of diet quality. I concluded that FN estimated with NIRS techniques could be a useful tool for studying patterns of diet quality in Alpine ibex. The declining FN and increasing FNDF values from summer to autumn suggest that ibex do not have the ability to contrast, with alternative food sources or with increasing selectivity, the decline in vegetation quality. This emphasizes the importance of energy-saving strategies during the winter, and of exploiting the short availability of good food resources in spring.
Questa tesi riporta I risultati di tre studi condotti sulla colonia di stambecco alpino dei gruppi “Marmolada-Monzoni”. Una sintesi per ciascuno studio è riportata di seguito. Contributo I: Morfologia del suolo, stagione e attività individuale influenzano la probabilità di acquisizione e l’errore associato alle localizzazioni con sistema GPS in un ungulato alpino. L'applicazione della tecnologia “GPS-tracking” nella ricerca sulla fauna selvatica ha offerto nuove, ampie opportunità per affrontare questioni ecologiche che riguardano in definitiva la conservazione delle specie. Tuttavia, per sfruttare a pieno le potenzialità della tecnologia e formulare conclusioni corrette, è necessario approfondire le conoscenze sulle cause di errore in essa implicite, nelle specifiche condizioni ambientali e con le specie su cui si opera. Nel primo capitolo, ho studiato come le peculiarità dell’ambiente alpino e il comportamento di femmine di stambecco influiscano sulla probabilità di acquisizione delle localizzazioni e sulla loro accuratezza. Ho prima condotto una prova sul campo, utilizzando collari programmati a tentare una localizzazione (fix) ogni 30 minuti durante cicli di 24 ore, e posizionati in 64 punti, di cui era stata determinata la posizione con un errore di 2.0 (ds = 2.8) m, scelti in modo da rappresentare le diverse condizioni di cielo visibile e di vegetazione (bosco o area aperta) dell’area occupata dalle femmine di stambecco oggetto del mio studio. Le prestazioni dei collari sono state influenzate soprattutto dalla percentuale di cielo visibile (skyview). Con skyview superiori al 70%, le localizzazioni acquisite sono state prossime al 100% di quelle attese, e l’errore di localizzazione si è mantenuto entro i 10 m per il 75% di esse. Con skyview minori di tale soglia, tuttavia, le localizzazioni acuisite sono scese al 75% di quelle attese e l’errore è aumentato fino a 20 m, sempre per il 75% delle localizzazioni. Ho poi analizzato un database di oltre 85.000 localizzazioni tentate, su 11 femmine munite di collare GPS durante un periodo di tre anni, al fine di individuare l’effetto delle caratteristiche ambientali dell’area usata giornalmente, del livello di attività degli animali (misurato dai sensori di movimento dei collari), e della variabilità climatica e meteorologica sulla probabilità di acquisizione delle localizzazioni attese. In estate, tale probabilità è rimasta molto buona (intorno al 95%) durante tutti i mesi e nell’arco di tutta la giornata. In inverno, invece, è diminuita fino a meno dell’85% nei mesi più freddi e nelle ore notturne. L’attività degli animali ha influenzato positivamente la probabilità di acquisizione delle localizzazioni, che è stata invece penalizzata dalle giornate con precipitazioni e da temperature inferiori alla media del periodo, soprattutto d’inverno. L’effetto positivo dell’attività si spiega molto probabilmente con il fatto che gli animali, quando sono attivi per spostarsi o per alimentarsi, tendono a frequentare aree aperte, mentre quando sono inattivi, sia di notte che di giorno se cercano rifugio dalle intemperie, tendono a frequentare aree riparate dove la skyview diminuisce. In conclusione, sebbene con un adeguato screening per eliminare gli outliers dalle localizzazioni ricevute sia possibile assicurare una buona accuratezza dei fix provenienti da habitat diversi, le localizzazioni ricevute sottostimano l’uso di habitat che forniscono riparo e i periodi climaticamente sfavorevoli. In generale, inoltre, i risultati di questo contributo sottolineano l’importanza di abbinare alle prove con collari statici anche l’analisi di database provenienti dagli animali oggetto di studio, al fine di individuare meglio i fattori che influiscono sulle prestazioni della tecnologia. Contributo II: Fattori determinanti le variazioni dell’home range a diverse scale spazio-tamporali in un ungulato Alpino L'elevata stagionalità degli ambienti alpini può incidere fortemente sulle strategie di uso dello spazio da parte dei grandi erbivori che le abitano. Nel secondo contributo ho prodotto e utilizzato un database di 672 home range settimanali (232 in estate and 440 in inverno) e uno di 160 home range mensili (64 in estate e 96 in inverno), derivante dal monitoraggio con collari GPS di 15 femmine di stambecco alpino nell’arco di tre anni, per individuare i pattern di variazione intra-annuale delle aree usate individualmente e per verificare come le variabili climatiche, gli indici di disponibilità alimentare, e fattori individuali agissero su tali pattern. Ho utilizzato, per il calcolo delle aree usate, il metodo k-LoCoH con due scale spaziali: l’home range (HR, calcolato sul 95% delle localizzazioni) e la core area (CA, calcolata sul 50% delle localizzazioni). Con tutte le scale temporali e spaziali, le aree usate dalle femmine sono risultate molto ridotte in inverno, per aumentare poi progressivamente fino a un picco in estate, e diminuire poi nuovamente. Questo andamento si è rivelato molto marcato, con un aumento fino a 15-20 volte di dimensione degli HR e delle CA passando dal minimo invernale al massimo estivo. L’area degli HR e delle CA è risultata così correlata positivamente con il fotoperiodo, ma le sue variazioni si sono sincronizzate maggiormente con l’andamento della temperatura e dell’indice NDVI medio dell’area di studio. Successivamente, dopo aver individuato stagioni biologicamente sensate sulla base di una cluster analisi della “step distance” e delle variabili ambientali associate alle localizzazioni, ho analizzato HR e CA, entro stagione e correggendo per il trend temporale, al fine di verificare gli efetti della varibilità stocastica degli indici climatici, degli indici di abbondanza trofica, e delle caratteristiche individuali degli animali. Le aree di HR a CA sono risultate negativamente influenzate dalla variabilità del manto nevoso o dall’abbondanza delle precipitazioni in inverno, e dalla disponibilità alimentare individuale (indicizzata dall’NDVI medio o dalla prevalenza di vegetazione su rocce e ghiaioni entro HR e CA). Anche la pendenza, che può indicare la disponibilità di zone di rifugio, ha influito negativamente sull’area di HR e CA. Invece, i fattori individuali, cioè la classe di età e lo stato di lattazione o meno, non hanno influito in misura apprezzabile sul comportamento spaziale. Questi risultati sottolineano la peculiarità delle strategie di uso dello spazio da parte delle femmine di stambecco alpino, che appaiono estremamente conservative nei riguardi dei dispendi energetici d’inverno e improntate a ottimizzare l’uso delle risorse alimentari, anche con rilevanti spostamenti, durante l’estate. La comprensione dei fattori che determinano tali strategie è di fondamentale importanza per la conservazione di aree e habitat chiave e per prevedere come la specie possa reagire al loro modificarsi, ad esempio in seguito al cambiamento climatico. Contributo III: Validazione di una tecnica non invasiva per la stima indiretta della qualità della dieta in un ungulato alpino Uno dei principali fattori che determinano i modelli di comportamento dei grandi erbivori è il variare stagionale della disponibilità di risorse alimentari, soprattutto in ambienti estremi come quelli frequentati dallo stambecco alpino. I contenuti fecali di azoto (FN) e, in minor misura, di NDF (FNDF) sono stati suggeriti come indicatori della qualità della dieta negli erbivori selvatici. Lo studio considerato dal terzo contributo ha valutato l’uso di questi indicatori per descrivere i pattern di qualità della dieta di stambecchi maschi e femmine dall’inizio dell’estate all’autunno. Dato che le analisi chimiche sono onerose in termini di costi e tempo richiesto, lo studio ha anche verificato in che misura i dati provenienti da strumenti NIRS diversi per ampiezza della gamma spettrale e per principio (riflettanza o assorbanza) potessero sostituire quelli dell’analisi chimica. Da giugno avanzato fino a novembre ho raccolto campioni freschi di feci di stambecchi maschi e femmine, su tutta l’area occupata dalla colonia. I campioni sono stati poi analizzati per N e NDF con metodo chimico tradizionale e con NIRS. Le predizioni NIRS sono risultate soddisfacenti, soprattutto per l’N, solo con lo strumento caratterizzato da ampia banda (350-1050 nm) e basato sulla riflettanza. I valori di FN sono diminuiti con il crescere della data giuliana, e quelli di FNDF sono aumentati, suggerendo un progressivo peggioramento della qualità della dieta ingerita da entrambi i sessi. Le femmine hanno tuttavia tendenzialmente mostrato valori di FN superiori e di FNDF inferiori a quelli dei maschi. Anche se questi andamenti sono stati descritti nella maniera più puntuale dai dati dell’analisi chimica, i dati prodotti dallo strumento NIRS rivelatosi più affidabile hanno prodotto patterns molto simili. Al fine di evidenziare eventuali correlazioni, ciascun campione fecale era stato caratterizzato anche con il valore medio dell’indice NDVI di un’area buffer circostante la sua localizzazione. Tuttavia, nessuna relazione è stata trovata tra indici di qualità della dieta e NDVI. In conclusione, i risultati ottenuti dimostrano che adeguate tecnologie NIRS possono sostituire le analisi chimiche per la stima dell’N e dell’NDF fecali. I patterns osservati per questi indicatori suggeriscono che, anche se le femmine sembrano capaci di selezionare una dieta migliore di quella dei maschi, entrambi i sessi sperimentano nel corso dell’estate e dell’autunno un declino progressivo della qualità della dieta ingerita. Questo risultato sottolinea l’importanza delle strategie di riduzione dei dispendi energetici messe in atto dalla specie in inverno, sia di quelle intese a massimizzare l’uso delle risorse trofiche messe in atto durante la primavera.

Abstract The boundary element method (BEM) has been utilized extensively in numerical simulations of engineering acoustics problems. The indirect boundary element formulation (IBEM) allows the simulatneous modeling of the acoustic spaces on both sides of a thin vibrating structure. In order to exploit the full potential of the IBEF a new formulation was developed in this work, allowing the application of separate impedance boundary conditions on each side of the vibrating structure. This situation is often encountered in practical applications (engine enclosures, computer boxes, car bodies, etc.), where noise isolation material is applied on only one side of a vibrating structure.

Gender equality is a debate that is becoming more and more integrated into everyday life, both politically, economically and socially. This paper analyses the situation of gender equality in 10 Spanish listed companies in IBEX 35, the Spanish stock market index par excellence. Specifically, 10 companies from different sectors were chosen in order to find out, firstly, whether there are differences in behaviour between industries within their organisations in this area. Secondly, various common indicators are proposed to be sought in the non-financial reports of the companies, in order to subsequently compare the transparency of data and the way in which they are communicated offered by each of the selected corporations.