Laser spectroscopy for breath analysis : towards clinical implementation

Detection and analysis of volatile compounds in exhaled breath represents an attractive tool for monitoring the metabolic status of a patient and disease diagnosis, since it is non-invasive and fast. Numerous studies have already demonstrated the benefit of breath analysis in clinical settings/applications and encouraged multidisciplinary research to reveal new insights regarding the origins, pathways, and pathophysiological roles of breath components. Many breath analysis methods are currently available to help explore these directions, ranging from mass spectrometry to laser-based spectroscopy and sensor arrays. This review presents an update of the current status of optical methods, using near and mid-infrared sources, for clinical breath gas analysis over the last decade and describes recent technological developments and their applications. The review includes: tunable diode laser absorption spectroscopy, cavity ring-down spectroscopy, integrated cavity output spectroscopy, cavity-enhanced absorption spectroscopy, photoacoustic spectroscopy, quartz-enhanced photoacoustic spectroscopy, and optical frequency comb spectroscopy. A SWOT analysis (strengths, weaknesses, opportunities, and threats) is presented that describes the laser-based techniques within the clinical framework of breath research and their appealing features for clinical use.Peer reviewe

Gravitational Wave Detection by Interferometry (Ground and Space)

Significant progress has been made in recent years on the development of gravitational wave detectors. Sources such as coalescing compact binary systems, neutron stars in low-mass X-ray binaries, stellar collapses and pulsars are all possible candidates for detection. The most promising design of gravitational wave detector uses test masses a long distance apart and freely suspended as pendulums on Earth or in drag-free craft in space. The main theme of this review is a discussion of the mechanical and optical principles used in the various long baseline systems in operation around the world - LIGO (USA), Virgo (Italy/France), TAMA300 and LCGT (Japan), and GEO600 (Germany/U.K.) - and in LISA, a proposed space-borne interferometer. A review of recent science runs from the current generation of ground-based detectors will be discussed, in addition to highlighting the astrophysical results gained thus far. Looking to the future, the major upgrades to LIGO (Advanced LIGO), Virgo (Advanced Virgo), LCGT and GEO600 (GEO-HF) will be completed over the coming years, which will create a network of detectors with significantly improved sensitivity required to detect gravitational waves. Beyond this, the concept and design of possible future "third generation" gravitational wave detectors, such as the Einstein Telescope (ET), will be discussed.Comment: Published in Living Reviews in Relativit

Bridging borders in the global city: negotiating sameness and difference in Hong Kong’s skilled immigrants from mainland China

Immigration labor in global cities is often framed in a dichotomy of skilled and nonskilled and explained from different perspective. Based on narratives of skilled immigrants from mainland China in postcolonial Hong Kong, this study shifts the focus of attention from generalized dissimilarities between migrant groups determined by the level of skills to commonalities of experience shaped by the broader social and cultural forces of their spatial, economic and political environments. It points to the importance of “border” in shaping the mode of incorporation of skilled migrants to localities in global city. It shows that skilled mainland immigrants in Hong Kong are deeply embedded in an overarching xin yimin (new immigrants) discourse according to which the Hong Kong–China border distinguishes all mainland immigrants from Hong Kong citizens regardless of the level of skills they possess. This discourse is associated with and defined by the cultural meaning of border between Hong Kong and China produced in the colonial past and reproduced in the postcolonial present. Despite being highly educated and skilled, mainland Chinese professionals experienced countless negotiation of sameness and difference in their everyday encountering localities and making place. The stories presented here ask us to rethink the assumptions informing the analytical distinctions between skilled and non-skilled and call for “unifying” skilled and non-skilled migration in global cities methodologically and theoretically