\u3ci\u3eMedicine Meets Virtual Reality 15\u3c/i\u3e

Chapter, Virtual Reality for Robotic Laparoscopic Surgical Training, co-authored by Nicholas Stergiou, UNO faculty member. Our culture is obsessed with design. Sometimes designers can fuse utility and fantasy to make the mundane appear fresh—a cosmetic repackaging of the same old thing. Because of this, medicine—grounded in the unforgiving realities of the scientific method and peer review, and of flesh, blood, and pain—can sometimes confuse “design” with mere “prettifying.” Design solves real problems, however. This collection of papers underwrites the importance of design for the MMVR community, within three different environments: in vivo, in vitro and in silico. in vivo: we design machines to explore our living bodies. Imaging devices, robots, and sensors move constantly inward, operating within smaller dimensions: system, organ, cell, DNA. in vitro: Using test tubes and Petri dishes, we isolate in vivo to better manipulate and measure biological conditions and reactions. in silico: We step out of the controlled in vitro environment and into a virtual reality. The silica mini-worlds of test tubes and Petri dishes are translated into mini-worlds contained within silicon chips. The future of medicine remains within all three environments: in vivo, in vitro, and in silico. Design is what makes these pieces fit together—the biological, the informational, the physical/material—into something new and more useful.https://digitalcommons.unomaha.edu/facultybooks/1235/thumbnail.jp

Experimental and Numerical Analysis of the Flow Inside a Configuration Including an Axial Pump and a Tubular Exchanger

In centrifugal and axial pumps, the flow is characterized by a turbulent and complex behavior and also by physical mechanisms such as cavitation and pressure fluctuations that are mainly due to the strong interactions between the fixed and mobile parts and the operating conditions. These fluctuations are more important at the tip clearance and propagate upstream and downstream of the rotor. The control of the fluctuating signal amplitudes can be achieved by incrementing the distance between the components mentioned above. This paper presents experimental and numerical results concerning the operation of a configuration that includes an axial pump and a bundle of tubes that mimics the cool source of a heat exchanger. The pump used in the tests has a low solidity and two blades designed in forced vortex, the tip clearance is approximately 3.87% of tip radius. The experimental measures were carried out using a test bench built for this purpose at the DynFluid Laboratory which was accomodated conveniently with a variety of instruments. Firstly, the characteristic curves were drawn for the pump at 1500 rpm and then a set of measurements concerning the use of pressure sensors was done in order to recover for different flow rates the static pressure signals upstream and downstream the pump and the exchanger. The pressure fluctuations and the performance curve were compared to the numerical results. The numerical simulations were carried out by using a Fluent code, the URANS (Unsteady Reynolds Averaged Navier-Stokes) approach and the k-ω SST turbulence model were applied to solve the unsteady, incompressible and turbulent flow. To record the fluctuating pressure signal, virtual sensors were necessary and placed at the same positions as in the experiments

Collisionless reconnection: The sub-microscale mechanism of magnetic field line interaction

Magnetic field lines are quantum objects carrying one quantum $\Phi_0=2\pi\hbar/e$ of magnetic flux and have finite radius $\lambda_m$. Here we argue that they possess a very specific dynamical interaction. Parallel field lines reject each other. When confined to a certain area they form two-dimensional lattices of hexagonal structure. We estimate the filling factor of such an area. Antiparallel field lines, on the other hand, attract each other. We identify the physical mechanism as being due to the action of the gauge potential field which we determine quantum mechanically for two parallel and two antiparallel field lines. The distortion of the quantum electrodynamic vacuum causes a cloud of virtual pairs. We calculate the virtual pair production rate from quantum electrodynamics and estimate the virtual pair cloud density, pair current and Lorentz force density acting on the field lines via the pair cloud. These properties of field line dynamics become important in collisionless reconnection, consistently explaining why and how reconnection can spontaneously set on in the field-free centre of a current sheet below the electron-inertial scale.Comment: 13 journal pages, 6 figures, submitted to Ann. Geophy

Virtual Braids

In the present paper we give a new method for converting virtual knots and links to virtual braids. Indeed the braiding method given in this paper is quite general, and applies to all the categories in which braiding can be accomplished. We give a unifying topological interpretation of virtuals and flats (virtual strings) and their isotopies via ribbon surfaces and abstract link diagrams. We also give reduced presentations for the virtual braid group, the flat virtual braid group, the welded braid group and several other categories of braids. The paper includes a discussion of the topological intepretation of the welded braid group in terms of tubes embedded in four-space. A sequel to this paper will give a new proof of a Markov Theorem for virtual braids (and related categories) via the L-move (a technique pioneered for classical braids and braids in three-manifolds by the second author).Comment: 31 pages, 22 figures, LaTeX documen

Design and Test of a Forward Neutron Calorimeter for the ZEUS Experiment

A lead scintillator sandwich sampling calorimeter has been installed in the HERA tunnel 105.6 m from the central ZEUS detector in the proton beam direction. It is designed to measure the energy and scattering angle of neutrons produced in charge exchange ep collisions. Before installation the calorimeter was tested and calibrated in the H6 beam at CERN where 120 GeV electrons, muons, pions and protons were made incident on the calorimeter. In addition, the spectrum of fast neutrons from charge exchange proton-lucite collisions was measured. The design and construction of the calorimeter is described, and the results of the CERN test reported. Special attention is paid to the measurement of shower position, shower width, and the separation of electromagnetic showers from hadronic showers. The overall energy scale as determined from the energy spectrum of charge exchange neutrons is compared to that obtained from direct beam hadrons.Comment: 45 pages, 22 Encapsulated Postscript figures, submitted to Nuclear Instruments and Method