68,171 research outputs found
Hollow core fiber with an octave spanning bandgap
No full textWe thoroughly compare the out-of-plane bandgaps generated by three realistic two-dimensional lattices: a triangular and a square arrangement of holes and a triangular arrangement of rods. We demonstrate that, for any given hole diameter-to-pitch ratio d/Λ, the triangular arrangement of interconnected resonators generates the widest possible bandgap along the air line, and we propose a physical interpretation explaining these results. The design of a hollow core photonic bandgap fiber based on such a lattice and able to transmit light with sub-decibel-per-meter losses over an octave of frequencies is presented for the first time, to the best of our knowledge
Dataset supporting the publication "End-capping hollow-core fibers with suppressed coupling into higher-order modes"
No full text*This dataset supporting the publication:
Zhong, A., Ding, M., Numkam Fokoua, E., Zvanovec, S., Poletti, F., Komanec, M., & Slavík, R. (in press). End-capping hollow-core fibers with suppressed coupling into higher-order modes. IEEE Journal of Selected Topics in Quantum Electronics.
https://doi.org/10.1109/JSTQE.2024.3381797</span
Differential diagnosis between usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) assessed by high-resolution computed tomography (HRCT)
No full textDifferential diagnosis between usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) assessed by high-resolution computed tomography (HRCT). Radiologia Medica, vol. 19, n. 5-6, 2005, pp. 472-487 Bna C, Zompatori M, Poletti V, Spaggiari E, Chetta A, Calabro E, Ormitti F, Berti E, Cancellieri A, Chilosi M. Sezione di Scienze Radiologiche, Dipartimento di Scienze Cliniche, Universita degli studi di Parma, Parma, Italy. PURPOSE: The aim of this study was to assess the accuracy of high-resolution CT in the differential diagnosis between UIP and NSIP, and the correlations with histological and functional findings. MATERIALS AND METHODS: Patients underwent thin-collimation spiral CT (1 mm), with 10-mm interval. Pulmonary function was assessed with a pneumotacograph and body plethysmograph connected with a computer for data analysis. Three pathologists, blinded to the clinical and functional data, provided a histological diagnosis based on established criteria reported in the literature. The study group only included patients with a histological diagnosis of either UIP or NSIP. RESULTS: We achieved a correct diagnosis of NSIP in 86.6% of cases (76.4% sensitivity; 84.6% specificity), whereas UIP was correctly diagnosed in 73.3% of cases (84.6% sensitivity; 76.5% specificity). An 80% agreement was achieved between the HRCT and histological findings in the whole case series (73% sensitivity, 87% specificity, p<0.01). CONCLUSIONS: The most important finding of our study was that a ground glass appearance equal to or greater than 15% is highly suggestive of NSIP. Therefore, our results could be useful to confirm a suggested diagnosis of NSIP
Multimode nonlinear fibre optics: theory and applications
No full textOptical fibres have been developed as an ideal medium for the delivery of optical pulses ever since their inception (Kao & Hockham, 1966). Much of that development has been focused on the transmission of low-energy pulses for communication purposes and thus fibres have been optimised for singlemode guidance with minimum propagation losses only limited by the intrinsic material absorption of silica glass of about 0.2dB/km in the near infrared part of the spectrum (Miya et al., 1979). The corresponding increase in accessible transmission length simultaneously started the interest in nonlinear fibre optics, for example with early work on the stimulated Raman effect (Stolen et al., 1972) and on optical solitons (Hasegawa & Tappert, 1973). Since the advent of fibre amplifiers (Mears et al., 1987), available fibre-coupled laser powers have been increasing dramatically and, in particular, fibre lasers now exceed kW levels in continuous wave (cw) operation (Jeong et al., 2004) and MW peak powers for pulses (Galvanauskas et al., 2007) in all-fibre systems. These developments are pushing the limits of current fibre technology, demanding fibres with larger mode areas and higher damage threshold. However, it is increasingly difficult to meet these requirements with fibres supporting one single optical mode and therefore often multiple modes are guided. Non-fibre-based laser systems are capable of delivering even larger peak powers, for example commercial Ti:sapphire fs lasers now reach the GW regime. Such extreme powers cannot be transmitted in conventional glass fibres at all without destroying them (Gaeta, 2000), but there is a range of applications for such pulses coupled into hollow-core capillaries, such as pulse compression (Sartania et al., 1997) and high-harmonic generation (Rundquist et al., 1998). For typical experimental parameters, these capillaries act as optical waveguides for a large number of spatial modes and modal interactions contribute significantly to the system dynamics.In order to design ever more efficient fibre lasers, to optimise pulse delivery and to control nonlinear applications in the high power regime, a thorough understanding of pulse propagation and nonlinear interactions in multimode fibres and waveguides is required. The conventional tools for modelling and investigating such systems are based on beam propagation methods (Okamoto, 2006). However, these are numerically expensive and provide little insight into the dependence of fundamental nonlinear processes on specific fibre properties, e.g., on transverse mode functions, dispersion and nonlinear mode coupling. For such an interpretation a multimode equivalent of the nonlinear Schrodinger equation, the standard and highly accurate method for describing singlemode nonlinear pulse propagation (Agrawal, 2001; Blow & Wood, 1989), is desirable. In this chapter, we discuss the basics of such a multimode generalised nonlinear Schrodinger equation (Poletti & Horak, 2008), its simplification to experimentally relevant situations and a few select applications. We start by introducing and discussing the theoretical framework for fibres with χ(3) nonlinearity in Sec. 2. The following sections are devoted to multimode nonlinear applications, presented in the order of increasing laser peak powers. A sample application in the multi-kW regime is supercontinuum generation, discussed in Sec. 3. Here we demonstrate how fibre mode symmetries and launching conditions affect intermodal power transfer and spectral broadening. For peak powers in the MW regime, self-focusing effects become significant and lead to strong mode coupling. The spatio-temporal evolution of pulses in this limit is the topic of Sec. 4. Finally, at GW peak power levels, optical pulses can only be delivered by propagation in gases. Still, intensities become so high that nonlinear effects related to ionisation must be taken into account. An extension of the multimode theory to include these extreme high power effects is presented in Sec. 5 and the significance of mode interaction is demonstrated by numerical examples pertaining to a recent experiment. Finally, we end this chapter with conclusions in Sec. 6
Dataset: Angle-spliced SMF to hollow core fiber connection with optimized back-reflection and insertion loss
No full textThis dataset supports the manuscript submitted to Journal of Lightwave Technology:
Cong Zhang, E. N. Fokoua, S. Fu, M. Ding, F. Poletti, D. J. Richardson, and R. Slavík
Angle-spliced SMF to hollow core fiber connection with optimized back-reflection and insertion loss. The dataset consists of an uploaded Archive (RAR) folder which includes 5 data files in Excel format.</span
Dataset for First demonstration of opposing thermal sensitivities in hollow core fibers with open and sealed ends
No full textThis dataset supports the publication:
R. Slavik, E.R. Numkam Fokoua, M. Bukhstab, Y. Chen,T.D. Bradley, S.R. Sandoghchi, M.N. Petrovich, F. Poletti, and D.J. Richardson,
First demonstration of opposing thermal sensitivities in hollow core fibers with open and sealed ends, Optics Letters
Uploaded Archive (ZIP) includes 12 data files that are purely numerical (.dat) and a README file.</span
La responsabilità per i danni da contaminazione genetica della produzione agricola
No full textIl contributo indaga la responsabilità per violazione della coesistenza tra coltivazioni agricole quale delineata dall'art. 5 della l. n. 5/2005, che ha tracciato un'ibrida e complicata ipotesi di responsabilità civile speciale, sottolineando i problemi interpretativi nascenti dalla sua imperfetta formulazione. Nel saggio viene indagato specificamente anche il rapporto tra la nuova fattispecie e le regole generali, in particolare il disposto dell'art. 2050 c.c
The role of the HSPB8-BAG3 complex in age-related protein misfolding diseases
No full textBackground and Purpose - The aggregation of misfolded, mutated proteins (SOD1, TDP-43) is a pathological hallmark of the familial forms of Amyotrophic Lateral Sclerosis (ALS). Cells have evolved an elaborate protein quality control system mediated by molecular chaperones, in order to facilitate folding/refolding of these misfolded species that can exert neurotoxicity. When folding is unsuccessful, chaperones can also target the misfolded proteins for degradation, thereby preventing protein aggregation. Intracellular degradation is primarily mediated by two proteolytic systems: the ubiquitin proteasome system and autophagy [1], and a proper balance and cross-talk between them is required for normal protein homeostasis, while their alteration may contribute to ageing and disease [2,3].
We already published that overexpression of the small heat shock protein HSPB8 (and its partner Bag3) in motoneuron cells (NSC34) prevents aggregation of mutated SOD1 and TDP-43, by either directly targeting them to the autophagic vacuoles for degradation and/or restoring/boosting the autophagy flux [4,5]. Moreover our recent data indicate that BAG3 upregulation, following proteasome inhibition, significantly contributes to the compensatory activation of autophagy and to the re-routing of (poly)ubiquitinated proteins to autophagy for degradation. Motoneurons are particularly sensitive to misfolded protein toxicity, but also other cell types could be affected. As an example, muscle-restricted expression of the mutSOD1, results in muscle atrophy associated with motoneuron death.
Methods and Results - We compared the potential mutSOD1 toxicity in motoneuron (NSC34) and muscle (C2C12) cells, and found that muscle ALS models possess much higher proteasome activity and autophagic power than motoneuron ALS models, which allow to better cope with misfolded protein aggregation [6]. The same results were also obtained with mutTDP43. These findings were further confirmed analyzing the expression of the LC3 and p62 genes (two well known autophagic markers) as well as of BAG3 and HSPB8 genes, which after proteasome inhibition are all higher activated in muscle cells than motoneuron cells. Finally we also found that the knock-down of HSPB8 increases the aggregation of both wt and mutTDP43 in C2C12, but only of mutTDP43 in NSC34, suggesting that HSPB8 plays a primary role in TDP43 turn-over especially in muscle cells.
Conclusions - These data together with the observation that HSPB8 and BAG3 are upregulated in muscles of ALS transgenic mice only at symptomatic stage and that HSPB8 is upregulated in surviving motor neurons in transgenic ALS mice during disease progression, strongly suggest that the boosting of this complex may serve to clear aggregates in chronic neurodegenerative diseases.
References
[1] Rubinsztein DC. 2006. The roles of intracellular protein-degradation pathways in neurodegeneration. Nature 443:780-786.
[2] Gamerdinger M, Hajieva P, Kaya AM, Wolfrum U, Hartl FU, Behl C. 2009. Protein quality control during aging involves recruitment of the macroautophagy pathway by BAG3. Embo J 28:889-901.
[3] Morimoto RI. 2008. Proteotoxic stress and inducible chaperone networks in neurodegenerative disease and aging. Genes Dev 22:1427-1438.
[4] Crippa V, Sau D, Rusmini P, Boncoraglio A, Onesto E, Bolzoni E, Galbiati M, Fontana E, Marino M, Carra S, Bendotti C, De Biasi S, Poletti A. 2010. The small heat shock protein B8 (HspB8) promotes autophagic removal of misfolded proteins involved in amyotrophic lateral sclerosis (ALS). Human molecular genetics 19:3440-3456.
[5] Carra S, Crippa V, Rusmini P, Boncoraglio A, Minoia M, Giorgetti E, Kampinga HH, Poletti A. 2011. Alteration of protein folding and degradation in motor neuron diseases: Implications and protective functions of small heat shock proteins. Prog Neurobiol 97:83-100.
[6] Onesto E, Rusmini P, Crippa V, Ferri N, Zito A, Galbiati M, Poletti A. 2011. Muscle cells and motoneurons differentially remove mutant SOD1 causing familial amyotrophic lateral sclerosis. Journal of Neurochemistry 118: 266–280
Politica energetica e politica ambientale: tanti interventi nessuna strategia
No full textAnalisi del bilancio energetico del sistema italiano e delle emissioni di gas serra nei settori economici.
Valutazione della capacità delle politiche settoriali nazionali (promozione delle energie rinnovabili, miglioramento dell'efficienza energetica nei consumi, ottimizzazione della produzione e degli usi di servizi energetici e di carburante) di perseguire gli obiettivi del Protocollo di Kyoto e del nuovo pacchetto Energia-Clima dell'UE.
Peso e valutazione degli strumenti cd flessibili e dei meccanismi di cooperazione tra Stati e tra imprese
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