How to Tango: a manual for implementing Spine Tango

The generic approach of the Spine Tango documentation system, which uses web-based technologies, is a necessity for reaching a maximum number of participants. This, in turn, reduces the potential for customising the Tango according to the individual needs of each user. However, a number of possibilities still exist for tailoring the data collection processes to the user's own hospital workflow. One can choose between a purely paper-based set-up (with in-house scanning, data punching or mailing of forms to the data centre at the University of Bern) and completely paper-free online data entry. Many users work in a hybrid mode with online entry of surgical data and paper-based recording of the patients' perspectives using the Core Outcome Measures Index (COMI) questionnaires. Preoperatively, patients can complete their questionnaires in the outpatient clinic at the time of taking the decision about surgery or simply at the time of hospitalisation. Postoperative administration of patient data can involve questionnaire completion in the outpatient clinic, the handing over the forms at the time of discharge for their mailing back to the hospital later, sending out of questionnaires by post with a stamped addressed envelope for their return or, in exceptional circumstances, conducting telephone interviews. Eurospine encourages documentation of patient-based information before the hospitalisation period and surgeon-based information both before and during hospitalisation; both patient and surgeon data should be acquired for at least one follow-up, at a minimum of three to six months after surgery. In addition, all complications that occur after discharge, and their consequences should be recorded.

Ethnography of a Land-Deal. Local Perceptions and Vertical Perspectives of a Large Scale Land Acquisition Project in Northern Sierra Leone

Despite an increased scientific interest in the relatively new phenomenon of large-scale land acquisition (LSLA), data on processes on the local level remain sparse and superficial. However, knowledge about the concrete implementation of LSLA projects and the different impacts they have on the heterogeneous group of project affected people is indispensable for a deepened understanding of the phenomenon. In order to address this research gap, a team of two anthropologists and a human geographer conducted in-depth fieldwork on the LSLA project of Swiss based Addax Bioenergy in Sierra Leone. After the devastating civil war, the Sierra Leonean government created favourable conditions for foreign investors willing to lease large areas of land and to bring “development” to the country. Being one of the numerous investing companies, Addax Bioenergy has leased 57’000 hectares of land to develop a sugarcane plantation and an ethanol factory to produce biofuel for the export to the European market. Based on participatory observation, qualitative interview techniques and a network analysis, the research team aimed a) at identifying the different actors that were necessary for the implementation of this project on a vertical level and b) exploring various impacts of the project in the local context of two villages on a horizontal level. The network analysis reveals a complex pattern of companies, institutions, nongovernmental organisations and prominent personalities acting within a shifting technological and discursive framework linking global scales to a unique local context. Findings from the latter indicate that affected people initially welcomed the project but now remain frustrated since many promises and expectations have not been fulfilled. Although some local people are able to benefit from the project, the loss of natural resources that comes along with the land lease affects livelihoods of vulnerable groups – especially women and land users – considerably. However, this research doesn’t only disclose impacts on local people’s previous lives but also addresses strategies they adopt in the newly created situation that has opened up alternative spaces for renegotiations of power and legitimatisation. Therewith, this explorative study reveals new aspects of LSLA that have not been considered adequately by the investing company nor by the general academic discourse on LSLA.

Atomic force microscopy for the study of membrane proteins

Fundamental biological processes such as cell-cell communication, signal transduction, molecular transport and energy conversion are performed by membrane proteins. These important proteins are studied best in their native environment, the lipid bilayer. The atomic force microscope (AFM) is the instrument of choice to determine the native surface structure, supramolecular organization, conformational changes and dynamics of membrane-embedded proteins under near-physiological conditions. In addition, membrane proteins are imaged at subnanometer resolution and at the single molecule level with the AFM. This review highlights the major advances and results achieved on reconstituted membrane proteins and native membranes as well as the recent developments of the AFM for imaging.

Statistical analysis of multichannel scalp field data

High density spatial and temporal sampling of EEG data enhances the quality of results of electrophysiological experiments. Because EEG sources typically produce widespread electric fields (see Chapter 3) and operate at frequencies well below the sampling rate, increasing the number of electrodes and time samples will not necessarily increase the number of observed processes, but mainly increase the accuracy of the representation of these processes. This is namely the case when inverse solutions are computed. As a consequence, increasing the sampling in space and time increases the redundancy of the data (in space, because electrodes are correlated due to volume conduction, and time, because neighboring time points are correlated), while the degrees of freedom of the data change only little. This has to be taken into account when statistical inferences are to be made from the data. However, in many ERP studies, the intrinsic correlation structure of the data has been disregarded. Often, some electrodes or groups of electrodes are a priori selected as the analysis entity and considered as repeated (within subject) measures that are analyzed using standard univariate statistics. The increased spatial resolution obtained with more electrodes is thus poorly represented by the resulting statistics. In addition, the assumptions made (e.g. in terms of what constitutes a repeated measure) are not supported by what we know about the properties of EEG data. From the point of view of physics (see Chapter 3), the natural “atomic” analysis entity of EEG and ERP data is the scalp electric field

Self-supporting CVD diamond charge state conversion surfaces for high resolution imaging of low-energy neutral atoms in space plasmas

Two polycrystalline diamond surfaces, manufactured by chemical vapour deposition (CVD) technique, are investigated regarding their applicability as charge state conversion surfaces (CS) for use in a low energy neutral atom imaging instrument in space research. The capability of the surfaces for converting neutral atoms into negative ions via surface ionisation processes was measured for hydrogen and oxygen with particle energies in the range from 100 eV to 1 keV and for angles of incidence between 6 deg and 15 deg. We observed surface charging during the surface ionisation processes for one of the CVD samples due to low electrical conductivity of the material. Measurements on the other CVD diamond sample resulted in ionisation efficiencies of ~2 % for H and up to 12 % for O. Analysis of the angular scattering revealed very narrow and almost circular scattering distributions. Comparison of the results with the data of the CS of the IBEX-Lo sensor shows that CVD diamond has great potential as CS material for future space missions.

Towards a data-driven analysis of hadronic light-by-light scattering

The hadronic light-by-light contribution to the anomalous magnetic moment of the muon was recently analyzed in the framework of dispersion theory, providing a systematic formalism where all input quantities are expressed in terms of on-shell form factors and scattering amplitudes that are in principle accessible in experiment. We briefly review the main ideas behind this framework and discuss the various experimental ingredients needed for the evaluation of one- and two-pion intermediate states. In particular, we identify processes that in the absence of data for doubly-virtual pion–photon interactions can help constrain parameters in the dispersive reconstruction of the relevant input quantities, the pion transition form factor and the helicity partial waves for γ⁎γ⁎→ππ.

Atomic mutagenesis of the ribosomal Sarcin-Ricin-Loop to study EF-G GTPase activation

Translocation factor EF-G, possesses a low basal GTPase activity, which is stimulated by the ribosome. One potential region of the ribosome that triggers GTPase activity of EF-G is the Sarcin-Ricin-Loop (SRL) (helix 95) in domain VI of the 23S rRNA. Structural data showed that the tip of the SRL closely approaches GTP in the active center of EF-G, structural probing data confirmed that EF-G interacts with nucleotides G2655, A2660, G2661 and A2662.1-3 The exocyclic group of adenine at A2660 is required for stimulation of EF-G GTPase activity by the ribosome as demonstrated using atomic mutagenesis.4 Recent crystal structures of EF-G on the ribosome, gave more insights into the molecular mechanism of EF-G GTPase activity.5 Based on the structure of EF-Tu on the ribosome1, the following mechanism of GTPase activation was proposed: upon binding of EF-G to the ribosome, the conserved His92 (E.coli) changes its position, pointing to the γ-phosphate of GTP. In this activated state, the phosphate of residue A2662 of the SRL positions the catalytic His in its active conformation. It was further proposed that the phosphate oxygen of A2662 is involved in a charge-relay system, enabling GTP hydrolysis. In order to test this mechanism, we use the atomic mutagenesis approach, which allows introducing non-natural modifications in the SRL, in the context of the complete 70S ribosome. Therefore, we replaced one of the non-bridging oxygens of A2662 by a methyl group. A methylphosphonat is not able to position or activate a histidine, as it has no free electrons and therefore no proton acceptor function. These modified ribosomes were then tested for stimulation of EF-G GTPase activity. First experiments show that one of the two stereoisomers incorporated into ribosomes does not stimulate GTPase activity of EF-G, whereas the other is active. From this we conclude that indeed the non-bridging phosphate oxygen of A2662 is involved in EF-G GTPase activation by the ribosome. Ongoing experiments aim at revealing the contribution of this non-bridging oxygen at A2662 to the mechanism of EF-G GTPase activation at the atomic level.

Atomic mutagenesis of the ribosomal Sarcin-Ricin-Loop to study EF-G GTPase activation

Translocation factor EF-G, possesses a low basal GTPase activity, which is stimulated by the ribosome. One potential region of the ribosome that triggers GTPase activity of EF-G is the Sarcin-Ricin-Loop (SRL) (helix 95) in domain VI of the 23S rRNA. Structural data showed that the tip of the SRL closely approaches GTP in the active center of EF-G, structural probing data confirmed that EF-G interacts with nucleotides G2655, A2660, G2661 and A2662.1-3 The exocyclic group of adenine at A2660 is required for stimulation of EF-G GTPase activity by the ribosome as demonstrated using atomic mutagenesis.4 Recent crystal structures of EF-G on the ribosome, gave more insights into the molecular mechanism of EF-G GTPase activity.5 Based on the structure of EF-Tu on the ribosome1, the following mechanism of GTPase activation was proposed: upon binding of EF-G to the ribosome, the conserved His92 (E.coli) changes its position, pointing to the γ-phosphate of GTP. In this activated state, the phosphate of residue A2662 of the SRL positions the catalytic His in its active conformation. It was further proposed that the phosphate oxygen of A2662 is involved in a charge-relay system, enabling GTP hydrolysis. In order to test this mechanism, we use the atomic mutagenesis approach, which allows introducing non-natural modifications in the SRL, in the context of the complete 70S ribosome. Therefore, we replaced one of the non-bridging oxygens of A2662 by a methyl group. A methylphosphonat is not able to position or activate a histidine, as it has no free electrons and therefore no proton acceptor function. These modified ribosomes were then tested for stimulation of EF-G GTPase activity. First experiments show that one of the two stereoisomers incorporated into ribosomes does not stimulate GTPase activity of EF-G, whereas the other is active. From this we conclude that indeed the non-bridging phosphate oxygen of A2662 is involved in EF-G GTPase activation by the ribosome. Ongoing experiments aim at revealing the contribution of this non-bridging oxygen at A2662 to the mechanism of EF-G GTPase activation at the atomic level.

High-resolution imaging of 2D outer membrane protein F (OmpF) crystals by atomic force microscopy

In this chapter the methodological bases are provided to achieve subnanometer resolution on two-dimensional (2D) membrane protein crystals by atomic force microscopy (AFM). This is outlined in detail with the example of AFM studies of the outer membrane protein F (OmpF) from the bacterium Escherichia coli (E. coli). We describe in detail the high-resolution imaging of 2D OmpF crystals in aqueous solution and under near-physiological conditions. The topographs of OmpF, and stylus effects and artifacts encountered when imaging by AFM are discussed.