5 research outputs found
Can skills assessment on a virtual reality trainer predict a surgical trainee's talent in laparoscopic surgery?
No full textBackground: A number of studies have investigated several aspects of feasibility and validity of performance assessments with virtual reality surgical simulators. However, the validity of performance assessments is limited by the reliability of such measurements, and some issues of reliability still need to be addressed. This study aimed to evaluate the hypothesis that test subjects show logarithmic performance curves on repetitive trials for a component task of laparoscopic cholecystectomy on a virtual reality simulator, and that interindividual differences in performance after considerable training are significant. According to kinesiologic theory, logarithmic performance curves are expected and an individual's learning capacity for a specific task can be extrapolated, allowing quantification of a person's innate ability to develop task-specific skills. Methods: In this study, 20 medical students at the University of Basel Medical School performed five trials of a standardized task on the LS 500 virtual reality simulator for laparoscopic surgery. Task completion time, number of errors, economy of instrument movements, and maximum speed of instrument movements were measured. Results: The hypothesis was confirmed by the fact that the performance curves for some of the simulator measurements were very close to logarithmic curves, and there were significant interindividual differences in performance at the end of the repetitive trials. Conclusions: Assessment of perceptual motor skills and the innate ability of an individual with no prior experience in laparoscopic surgery to develop such skills using the LS 500 VR surgical simulator is feasible and reliabl
Nonvanishing effect of detuning errors in dynamical-decoupling-based quantum sensing experiments
No full textCharacteristic dips appear in the coherence traces of a probe qubit when dynamical decoupling (DD) is applied in synchrony with the precession of target nuclear spins, forming the basis for nanoscale nuclear magnetic resonance (NMR). The frequency of the microwave control pulses is chosen to match the qubit transition but this can be detuned from resonance by experimental errors, hyperfine coupling intrinsic to the qubit, or inhomogeneous broadening. The detuning acts as an additional static field which is generally assumed to be completely removed in Hahn echo and DD experiments. Here we demonstrate that this is not the case in the presence of finite pulse-durations, where a detuning can drastically alter the coherence response of the probe qubit, with important implications for sensing applications. Using the electronic spin associated with a nitrogen-vacancy center in diamond as a test qubit system, we analytically and experimentally study the qubit coherence response under CPMG and XY8 dynamical decoupling control schemes in the presence of finite pulse-durations and static detunings. Most striking is the splitting of the NMR resonance under CPMG, whereas under XY8 the amplitude of the NMR signal is modulated. Our work shows that the detuning error must not be neglected when extracting data from quantum sensor coherence traces
Quantum Bath Control with Nuclear Spin State Selectivity via Pulse-Adjusted Dynamical Decoupling
No full textDynamical decoupling (DD) is a powerful method for controlling arbitrary open quantum systems. In quantum spin control, DD generally involves a sequence of timed spin flips (π rotations) arranged to either average out or selectively enhance coupling to the environment. Experimentally, errors in the spin flips are inevitably introduced, motivating efforts to optimize error-robust DD. Here we invert this paradigm: By introducing particular control "errors" in standard DD, namely, a small constant deviation from perfect π rotations (pulse adjustments), we show we obtain protocols that retain the advantages of DD while introducing the capabilities of quantum state readout and polarization transfer. We exploit this nuclear quantum state selectivity on an ensemble of nitrogen-vacancy centers in diamond to efficiently polarize the C13 quantum bath. The underlying physical mechanism is generic and paves the way to systematic engineering of pulse-adjusted protocols with nuclear state selectivity for quantum control applications
sj-pdf-1-vmj-10.1177_1358863X221140151 – Supplemental material for Demographic and regional trends of peripheral artery disease mortality in the United States, 2000 to 2019
No full textSupplemental material, sj-pdf-1-vmj-10.1177_1358863X221140151 for Demographic and regional trends of peripheral artery disease mortality in the United States, 2000 to 2019 by Rochell Issa, Salik Nazir, Abdul Mannan Khan Minhas, Jacob Lang, Robert W Ariss, Waleed Tallat Kayani, Mirza Umair Khalid, Laurence Sperling, Michael D Shapiro, Hani Jneid and Rajesh Gupta in Vascular Medicine</p
Improved methods for production and characterisation of Jembrana disease virus proteins
No full textJembrana disease is an acute disease of Bali cattle (Bos javanicus) in Indonesia caused by Jembrana disease virus (JDV), a lentivirus most closely related to Bovine immunodeficiency virus. Control of the disease in Bali cattle, which are important to the economy of Indonesia, is dependent on the continued availability of protein antigens for immunosurveillance procedures that have been developed. Further investigation is also required to characterise of the proteins of JDV and to provide methods of producing commercial quantities of recombinant proteins for vaccine manufacture.
A problem with the large scale production of viral proteins using recombinant technology was that the proteins have been mainly produced as insoluble products within inclusion bodies in bacterial cells and in that insoluble format they were unsuitable for use as antigens. A method for solubilisation of the insoluble proteins was developed that involved solubilisation of the inclusion bodies with low concentrations of urea in an alkaline solution and the method could be performed easily and at low cost without any detectable loss of antigenicity. The solubilised protein was successfully renatured without the formation of aggregates by dilution of the urea in the presence of the reducing agent dithiothreitol. The method would be suitable for use during the large scale production of recombinant viral proteins for vaccine manufacture.
To provide an additional reagent for diagnosis of the disease, mice were immunised with the recombinant capsid (CA) protein of JDV and a hybridoma was produced that secreted monoclonal antibodies reactive with the CA protein. This monoclonal antibody was effectively used in an immunoperoxidase assay to demonstrate virus in tissues. As an alternative to this technology, recombinant antibody fragments, scFv, reactive with the CA protein of JDV, were also produced by phage display technology. These scFv were expressed as soluble products in the periplasmic space of transfected host bacterial cells. The scFv reacted specifically with the CA protein in western immunoblots and although further optimisation of the methods of production of this scFv are required, the reagents developed can be for expression of the antibody when required, without the need for maintaining liquid nitrogen storage facilities that are necessary for storage of hybridomas.
The size and nature of the glycosylation of the envelope proteins SU and TM of JDV harvested from infected cattle was determined. Two proteins of 75 and 60 kDa were initially identified in SDS-PAGE as the SU and TM, respectively. They were initially identified using a specific glycoprotein stain and then matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometric (MS) analysis of the protein sequence. Further investigation on the unmatched mass value from MALDI-TOF/MS data suggested that post-translational glycosylation occurred on N-linked glycosylation sites of the JDV-SU and on O-linked glycosylation sites of the JDV-TM. This is the first report of the characteristics of the envelope proteins of JDV and their identification will facilitate further studies of the nature of the immune response to JDV infection using immunoblotting procedures
