Strong magnetic field enhancement of spin triplet pairing arising from coexisting 2kF2k_F spin and 2kF2k_F charge fluctuations

We study the effect of the magnetic field (Zeeman splitting) on the triplet pairing. We show generally that the enhancement of spin triplet pairing mediated by coexisting $2k_F$ spin and $2k_F$ charge fluctuations can be much larger than in the case of triplet pairing mediated by ferromagnetic spin fluctuations. We propose that this may be related to the recent experiment for (TMTSF)$_2$ClO$_4$, in which a possibility of singlet to triplet pairing transition has been suggested.Comment: 5 page

Accurate multi-robot targeting for keyhole neurosurgery based on external sensors monitoring

Robotics has recently been introduced in surgery to improve intervention accuracy, to reduce invasiveness and to allow new surgical procedures. In this framework, the ROBOCAST system is an optically surveyed multi-robot chain aimed at enhancing the accuracy of surgical probe insertion during keyhole neurosurgery procedures. The system encompasses three robots, connected as a multiple kinematic chain (serial and parallel), totalling 13 degrees of freedom, and it is used to automatically align the probe onto a desired planned trajectory. The probe is then inserted in the brain, towards the planned target, by means of a haptic interface. This paper presents a new iterative targeting approach to be used in surgical robotic navigation, where the multi-robot chain is used to align the surgical probe to the planned pose, and an external sensor is used to decrease the alignment errors. The iterative targeting was tested in an operating room environment using a skull phantom, and the targets were selected on magnetic resonance images. The proposed targeting procedure allows about 0.3 mm to be obtained as the residual median Euclidean distance between the planned and the desired targets, thus satisfying the surgical accuracy requirements (1 mm), due to the resolution of the diffused medical images. The performances proved to be independent of the robot optical sensor calibration accuracy

A practice-based approach to examining knowledge management repository use

Though knowledge has become an increasingly important resource for modern businesses, it was not until the mid-1990's that the 'knowledge management' research stream emerged in the business and information systems literature. Initial research on how to manage knowledge came from an objectivist epistemology of knowledge that viewed it as something that was capable of captured, stored and transferred via information to increase organisational efficiency. This study is grounded in a more recent and alternative perspective that takes a practice based epistemology seeing knowledge as embedded in and inseparable from practice. The practices of interest relate to how knowledge work is performed in environments where there is heavy reliance on information systems. Using an interpretive case study this research analyses the practices of a product support centre of a US multinational. Data was collected through semi-structured interviews and internal documentation, including access to the firms „knowledge management‟ repository. Two central practices were examined: how product support engineers made sense of problems to develop fix procedures and how these were subsequently documented. Even within a work environment where client fixes were verifiable, suggesting an objectivist epistemology, this research found that the practice based perspective could be used to provide a different perspective and develop alternative and useful insights. The study contributes to the practice based perspective on knowledge management by providing an analysis of context specific knowledge work practices by analysing how even in procedural repetitive work agency can be exhibited as actors enact practices. It also helps develop the application of Structuration Theory by aiding an understanding of how meanings, norms and resources are developed, drawn upon, conflict, and are changed as everyday work is accomplished. The study is of relevance by providing an understanding of informal knowledge work practices rather than their formal description.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Safety and feasibility of robotic-assisted drainage of symptomatic pancreatic pseudocysts: A case-series analysis (with video)

The surgical treatment of pancreatic pseudocysts (PPs) in patients who fail nonoperative management has evolved from aggressive open to a minimally invasive approach. The application of robotic surgery in this setting is scarcely reported. The aim of this study is to analyze the safety and feasibility of the robotic approach to pancreatic pseudocyst drainage. A single centre retrospective review of consecutive patients undergoing robotic-assisted pancreatic pseudocyst surgeries in an academic tertiary institution was performed. There were 14 patients studied, of whom 10 underwent cystogastrostomy and 4 Roux-En-Y cystojejunostomy. Eight patients had gallstone pancreatitis and 3 patients alcoholic pancreatitis. The mean size of cyst was 8.9±1cm and 57.1% located at the pancreatic body. The overall operative time of the procedure was 135±34 minutes. There were no open conversions. The overall success rate was 92.8%, while the primary success rate 85.7%. The major morbidity rate was 14.3% and there was no 30-day mortality. The mean post-operative hospital stay was 7±3 days with one recurrence of the pancreatic pseudocyst on follow-up requiring endoscopic drainage without further recurrence. The robotic approach for the drainage of symptomatic pancreatic pseudocyst is safe and feasible and can be considered as a viable modality for operative intervention in well-selected patient

Phase Fluctuations and Vortex Lattice Melting in Triplet Quasi-One-Dimensional Superconductors at High Magnetic Fields

Assuming that the order parameter corresponds to an equal spin triplet pairing symmetry state, we calculate the effect of phase fluctuations in quasi-one-dimensional superconductors at high magnetic fields applied along the y (b') axis. We show that phase fluctuations can destroy the theoretically predicted triplet reentrant superconducting state, and that they are responsible for melting the magnetic field induced Josephson vortex lattice above a magnetic field dependent melting temperature Tm.Comment: 4 pages (double column), 1 eps figur

Spin-Triplet Superconductivity Mediated by Phonons in Quasi-One-Dimensional Systems

We investigate the spin-triplet superconductivity mediated by phonons in quasi-one-dimensional (Q1D) systems with open Fermi surfaces. We obtain the ground state phase diagrams. It is found that spin-triplet superconductivity occurs for weak screening and strong on-site Coulomb interaction, even in the absence of any additional nonphonon pairing interactions. We find that the nodeless spin-triplet state is more favorable than the spin-triplet state with line nodes, for the parameter values of the Q1D superconductors (TMTSF)_2X. We also find that Q1D open Fermi surface, which is the specific feature of this system, plays an essential role in the pairing symmetry. We discuss the compatibility of the present results with the experimental results in these compounds.Comment: 8 pages, 15 figures, with jpsj2.cl