Prospects for atomic magnetometers employing hollow core optical fibre

Presently, among the most demanding applications for highly sensitive magnetometers are Magnetocardiography (MCG) and Magnetoencephalography (MEG), where sensitivities of around 1pT.Hz<sup>-1/2</sup> and 1fT.Hz<sup>-1/2</sup> are required. Cryogenic Superconducting Quantum Interference Devices (SQUIDs) are currently used as the magnetometers. However, there has been some recent work on replacing these devices with magnetometers based on atomic spectroscopy and operating at room temperature. There are demonstrations of MCG and MEG signals measured using atomic spectroscopy These atomic magnetometers are based on chip-scale microfabricated components. In this paper we discuss the prospects of using photonic crystal optical fibres or hollow core fibres (HCFs) loaded with Rb vapour in atomic magnetometer systems. We also consider new components for magnetometers based on mode-locked semiconductor lasers for measuring magnetic field via coherent population trapping (CPT) in Rb loaded HCFs

Output power limitations and improvements in passively mode locked GaAs/AlGaAs quantum well lasers

We report a novel approach for increasing the output power in passively mode locked semiconductor lasers. Our approach uses epitaxial structures with an optical trap in the bottom cladding that enlarges the vertical mode size to scale the pulse saturation energy. With this approach we demonstrate a very high peak power of 9.8 W per facet, at a repetition rate of 6.8 GHz and with pulse duration of 0.71 ps. In particular, we compare two GaAs/AlGaAs epilayer designs, a double quantum well design operating at 830 nm and a single quantum well design operating at 795 nm, with vertical mode sizes of 0.5 and 0.75 μm, respectively. We show that a larger mode size not only shifts the mode locking regime of operation toward higher powers, but also produces other improvements with respect to two main failure mechanisms that limit the output power, catastrophic optical mirror damage and catastrophic optical saturable absorber damage. For the 830-nm material structure, we also investigate the effect of nonabsorbing mirrors on output power and mode locked operation of colliding pulse mode locked lasers

Monolithic high power mode locked GaAs/AlGaAs quantum well lasers

In this thesis, approaches for increasing the output power in monolithically integrated semiconductor mode locked (ML) lasers were investigated. The wavelength range considered is the range of operation of low temperature grown GaAs photomixers, devices commonly used for THz generation. In particular, two GaAs/AlGaAs quantum well laser epistructures (operating at 830 nm and 795 nm) were considered, both with reduced optical confinement and elongated vertical optical mode size. In this work, such laser epistructures, commonly used by high power semiconductor laser manufacturers, were successfully employed, for the first time, for producing passively ML devices. Improved average powers (up to 48 mW) under ML operation were demonstrated, around ten times higher than values previously reported in monolithic GaAs/AlGaAs ML lasers. In continuous wave operation, the output power was limited by the catastrophic damage of the laser facets at around 50 mW. For this reason, facet passivation techniques were investigated, allowing for powers up to 124 mW to be achieved. In ML regime, the output power was instead limited by the catastrophic damage of the reverse biased section of the laser. This failure mechanism was investigated and explained considering thermal effects on the reverse biased section. Such effects limited the output power to around 27 mW in 830 nm devices, which was then improved by 70% in 795 nm devices with a 70% larger optical mode area. The larger mode size, combined to a small duty-cycle laser geometry, enabled a record peak power of 9.8 W to be achieved at 6.83 GHz. This particular repetition rate was specifically designed for coherent population trapping experiments in 87Rb vapors. Sub-picosecond transform limited pulses were achieved in both the laser materials considered, with a minimum duration of 0.43 ps at 126 GHz. With the values of peak power achieved, the developed devices may also be directly used for two-photon microscopy applications

Passively mode-locked semiconductor laser for coherent population trapping in ⁸⁷Rb

Passively mode-locked semiconductor laser for coherent population trapping in <sup>87</sup>Rb is reported. The laser material used is a 793nm GaAs/Al<sub>x</sub>Ga<sub>1-x</sub>As single quantum well (QW) graded index separate confinement heterostructure

First report of a gallbladder hemangioma coexisting with gallstones: a case report and literature review of a rare finding

BACKGROUND: Gallbladder hemangioma is an exceptionally rare entity, with only ten cases reported in literature hitherto. The here described case is the first report of a gallbladder hemangioma coexisting with gallstones. CASE PRESENTATION: A 76-year-old male was hospitalized following repeated episodes of epigastric pain. Patient’s medical history included primary hypertension, type 2 diabetes mellitus, dyslipidemia, obesity and hyperuricemia. Physical examination revealed marked pain in the right hypochondriac region, and laboratory workup was notable for mildly elevated glycemia (125 mg/dL) and pancreatic amylase (60 IU/L). Abdominal ultrasound showed multiple gallstones, a thickened gallbladder wall and mild edema of the perivisceral adipose tissue as well as a hepatic angioma. During surgery, an incidental subserosal nodule of about 1 cm was detected within the gallbladder fundus. After surgery, the clinical course was uneventful and the patient was discharged. Histopathological examination of the subserosal nodule showed multiple dilated vascular channels within a sclerosing matrix, a finding consistent with a cavernous hemangioma. Diffuse chronic cholecystitis was also present. CONCLUSIONS: Gallbladder hemangiomas represent a rare, likely underdiagnosed condition which can be undetected during the preoperative workup

"From the Hero's Journey to the Fool's Journey": models and devices for the screenplay.

openA partire dal successo di manuali quali "Il viaggio dell’eroe. La struttura del mito ad uso di scrittori di narrativa e di cinema" (Ediz. orig. in Vogler Christopher, The writer’s journey: mythic structure for writers, Michael Wiese Productions, Studio City, 1992) del famoso story-analyst hollywoodiano Chris Vogler, il presente elaborato recupera, da un lato, i contributi, precedenti e successivi, imperniati sul monomito, operando un’analisi comparativa, dall’altro approda ad altri dispositivi, quali il gioco, alla base della proposta Scrivere con i Tarocchi. Dal viaggio dell'eroe al viaggio del matto. Usare i tarocchi per raccontare una storia (Dino Audino Editore, Roma, 2018), di Alfonso Cometti e Grazia Giardiello, professionisti del settore televisivo e docenti di sceneggiatura. Nella seconda parte della tesi sarà quest’ultimo modello a essere messo alla prova rispetto a una delle forme narrative di maggior successo del contemporaneo, la serialità audiovisiva, attraverso studi di caso.Starting from the success of manuals such as "The Hero's Journey: The Mythic Structure for Writers" (Ediz. orig. in Vogler Christopher, The writer’s journey: mythic structure for writers, Michael Wiese Productions, Studio City, 1992) by the famous Hollywood story analyst Chris Vogler, this study incorporates, on one hand, previous and subsequent contributions centered around the monomyth, conducting a comparative analysis. On the other hand, it explores other approaches, such as the use of Tarot cards as a foundation for the proposal "Writing with Tarot: From the Hero's Journey to the Fool's Journey. Using Tarot Cards to Tell a Story"(Ediz. orig. in Cometti Alfonso, Giardiello Grazia, Scrivere con i Tarocchi: Dal viaggio dell'eroe al viaggio del matto. Usare i tarocchi per raccontare una storia, Dino Audino Editore, Roma, 2018) by Alfonso Cometti and Grazia Giardiello, industry professionals and screenwriting instructors. In the second part of the thesis, this latter model will be tested in relation to one of the most successful contemporary narrative forms, audiovisual serial storytelling, through case studies

"It's Not Just Writing": Negotiating Childness in Children's Literature Through Performance

This article reflects on insights gained from a larger study that explored how a class of ten to eleven-year olds read and responded to David Almond’s hybrid novel, My Name is Mina. Through focusing on the children’s performances of the poems contained within the text the discussion examines embodied aspects of the children’s engagement and suggests that these play a critical role in the children’s shared readership. The implications of this analysis are then considered in relation to Peter Hollindale’s definition of ‘childness’ and it is argued that a closer analysis of William Shakespeare’s The Winter’s Tale reveals tensions inherent between linguistic constructions of childness within the text and embodied performances on stage. Drawing on critical perspectives from children’s literature theory and research conducted on classroom dialogue, the article argues that children make use of their social and physical positioning to engage in fictive negotiations of childness and adultness and, in so doing, co-create the aesthetic experience that we refer to as children’s literature