A Transdisciplinary Complex Adaptive Systems (T-CAS) Approach to Developing a National School-Based Culture of Prevention for Health Improvement: the School Health Research Network (SHRN) in Wales.

The paper reflects on a transdisciplinary complex adaptive systems (T-CAS) approach to the development of a school health research network (SHRN) in Wales for a national culture of prevention for health improvement in schools. A T-CAS approach focuses on key stages and activities within a continuous network cycle to facilitate systems level change. The theory highlights the importance of establishing transdisciplinary strategic partnerships to identify and develop opportunities for system reorientation. Investment in and the linking of resources develops the capacity for key social agents to take advantage of disruption points in the re-orientated system, and engagement activities develop the network to facilitate new social interactions and opportunities for transdisciplinary activities. A focus on transdisciplinary action research to co-produce interventions, generate research evidence and inform policy and practice is shown to play an important part in developing new normative processes that act to self-regulate the emerging system. Finally, the provision of reciprocal network benefits provides critical feedback loops that stabilise the emerging adaptive system and promote the network cycle. SHRN is shown to have embedded itself in the system by securing sustainability funding from health and education, a key role in national and regional planning and recruiting every eligible school to the network. It has begun to reorient the system to one of evidence generation (56 research studies co-produced) and opportunities for data-led practice at multiple levels. Further capacity development will be required to capitalise on these. The advantages of a complex systems approach to address barriers to change and the transferability of a T-CAS network approach across settings and cultures are highlighted.

Time-resolved ultrafast transient polarization spectroscopy to investigate nonlinear processes and dynamics in electronically excited molecules on the femtosecond time scale.

We report a novel experimental technique to investigate ultrafast dynamics in photoexcited molecules by probing the 3rd-order nonlinear optical susceptibility. A non-collinear 3-pulse scheme is developed to probe the ultrafast dynamics of excited electronic states using the optical Kerr effect. Optical homodyne and optical heterodyne detections are demonstrated to measure the 3rd-order nonlinear optical response for the S1 excited state of liquid nitrobenzene, which is populated by 2-photon absorption of a 780 nm 40 fs excitation pulse.

Ultrafast Dynamics of Excited Electronic States in Nitrobenzene Measured by Ultrafast Transient Polarization Spectroscopy.

We investigate ultrafast dynamics of the lowest singlet excited electronic state in liquid nitrobenzene using ultrafast transient polarization spectroscopy, extending the well-known technique of optical Kerr effect spectroscopy to excited electronic states. The third-order nonlinear response of the excited molecular ensemble is measured using a pair of femtosecond pulses following a third femtosecond pulse that populates the S1 excited state. By measuring this response, which is highly sensitive to details of the excited state character and structure, as a function of time delays between the three pulses involved, we extract the dephasing time of the wave packet on the excited state. The dephasing time, measured as a function of time delay after pump excitation, shows oscillations indicating oscillatory wave packet dynamics on the excited state. From the experimental measurements and supporting theoretical calculations, we deduce that the wave packet completely leaves the S1 state potential energy surface after three traversals of the intersystem crossing between the singlet S1 and triplet T2 states.

In Situ Analysis of Small Populations of Adherent Mammalian Cells Using Laser Ablation Electrospray Ionization Mass Spectrometry in Transmission Geometry.

Most cultured cells used for biomedical research are cultured adherently, and the requisite detachment prior to biochemical analysis might induce chemical changes. This is especially crucial if accurate metabolic measurements are desired, given the rapid turnover of metabolites in living organisms. There are only a few methods available for the nontargeted in situ analysis of small adherent cell populations. Here we show that laser ablation electrospray ionization (LAESI) mass spectrometry (MS) can be used to analyze adherent cells directly, while still attached to the culture surface. To reduce the size of the analyzed cell population, the spot size constraints of conventional focusing in reflection geometry (rg) LAESI had to be eliminated. By introducing transmission geometry (tg) LAESI and incorporating an objective with a high numerical aperture, spot sizes of 10-20 µm were readily achieved. As few as five adherent cells could be specifically selected for analysis in their culturing environment. The importance of in situ analysis was highlighted by comparing the metabolite composition of adherent versus suspended cells. For example, we observed that cells analyzed adherently yielded higher values for the adenylate energy charge (0.90 ± 0.09 for adherent cells vs 0.09 ± 0.03 for suspended cells). Additionally, due to the smaller focal spot size, tg-LAESI enabled the analysis of ∼20 times smaller cell populations compared to rg-LAESI.