The effect of augmented reality training on percutaneous needle placement in spinal facet joint injections

The purpose of this study was to determine if augmented reality image overlay and laser guidance systems can assist medical trainees in learning the correct placement of a needle for percutaneous facet joint injection. The Perk Station training suite was used to conduct and record the needle insertion procedures. A total of 40 volunteers were randomized into two groups of 20. 1) The Overlay group received a training session that consisted of four insertions with image and laser guidance, followed by two insertions with laser overlay only. 2) The Control group received a training session of six classical freehand insertions. Both groups then conducted two freehand insertions. The movement of the needle was tracked during the series of insertions. The final insertion procedure was assessed to determine if there was a benefit to the overlay method compared to the freehand insertions. The Overlay group had a better success rate (83.3% versus 68.4%, p=0.002), and potential for less tissue damage as measured by the amount of needle movement inside the phantom (3077.6 mm(2) versus 5607.9 mm(2) , p =0.01). These results suggest that an augmented reality overlay guidance system can assist medical trainees in acquiring technical competence in a percutaneous needle insertion procedure.     

Inexpensive digital imaging?

The capture of digital images through the use of a frame grabber provides tremendous advantages to scanning electron microscopy. Accessory frame grabbers can range in price from very inexpensive to several thousand dollars. This work investigates the application of one inexpensive “consumer product” frame grabber which has recently been introduced to scanning electron microscope (SEM) imaging. The application of this frame grabber to the SEM as a low-cost, entry-level digital imaging tool is explored, and its performance is compared with a more expensive system.     

Plasma‐enhanced deposition of silver nanoparticles onto polymer and metal surfaces for the generation of antimicrobial characteristics

Silver nanoparticle thin layers were deposited onto formaldehyde‐radio frequency (RF)‐plasma‐functionalized medical‐ and food‐grade silicone rubber, stainless steel, and paper surfaces. The silver deposition was carried out under ex situ plasma conditions using the Tollen's reaction. Results from survey and high‐resolution electron spectroscopy for chemical analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X‐ray spectroscopy investigations confirmed the presence of thin silver layers on the plasma‐exposed and subsequently modified substrate surfaces. In addition, SEM and AFM demonstrated the nanoparticle‐based morphology of the deposited layers. Our results showed that thin macromolecular layers bearing aldehyde functionalities can be deposited onto silicone rubber, stainless steel, and paper surfaces. The bactericidal properties of the silver‐coated surfaces were demonstrated by exposing them to Listeria monocytogenes. No viable bacteria were detected after 12 to 18 h on silver‐coated silicone rubber surfaces. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1411–1422, 2004     

Generation of antifouling layers on stainless steel surfaces by plasma‐enhanced crosslinking of polyethylene glycol

Polyethylene glycol (PEG) structures were deposited onto stainless steel (SS) surfaces by spin coating and argon radio frequency (RF)‐plasma mediated crosslinking. Electron spectroscopy for chemical analysis (ESCA) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) indicated the presence of  CH₂ CH₂ O structure and C C C linkage, as a result of the plasma crosslinking, on PEG‐modified SS surfaces. Scanning electron microscopy (SEM) indicated complete deposition, and water contact angle analysis revealed higher hydrophilicity on PEG‐modified surfaces compared to unmodified SS surfaces. Surface morphology and roughness analysis by atomic force microscopy (AFM) revealed smoother SS surfaces after PEG modification. The evaluation of antifouling ability of the PEG‐modified SS surfaces was carried out. Compared to the unmodified SS, PEG‐modified surfaces showed about 81–96% decrease in Listeria monocytogenes attachment and biofilm formation (p < 0.05). This cold plasma mediated PEG crosslinking provided a promising technique to reduce bacterial contamination on surfaces encountered in food‐processing environments. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 485–497, 2005     

Asymptotic Distribution of Eigenvalues for Damped String Equation: Numerical Approach

In the present paper, we consider a one-parameter family of the nonself-adjoint operators, which are the dynamics generators for systems governed by the wave equations containing dissipative terms. The equations contain viscous damping terms and are equipped with the boundary conditions involving an arbitrary complex parameter. In the current engineering literature, this type of boundary condition is used to model the action of smart materials (self-sensing/self-straining actuators). In the previous research of the first writer, the aforementioned dynamics generators have been studied analytically and precise asymptotic formulas for the eigenvalues have been derived (the asymptotic when the number of the eigenvalues tends to infinity). The goal of the present paper is to demonstrate that the analytic formulas are not only important theoretically, but also extremely efficient practically. Namely, we show that the leading terms in the asymptotic formulas approximate the actual eigenvalues with excellent accuracy. To justify the results, we use two methods, i.e., the Newton method and the Tchebychev method. First, Newton’s method is applied to the characteristic equation using asymptotic formulas as initial guesses to find the eigenvalues. The convergence of Newton’s method is improved by modifying the asymptotic formula. Second, we use Tchebychev discretization to circumvent the nonlinear characteristic equation and to obtain a finite-dimensional generalized eigenvalue problem that approximates the infinite-dimensional one. Finally, to solve the generalized eigenvalue problem, we use the QT algorithm.     

Modular construction of extended DNA recognition surfaces: mutant DNA-binding domains of the 434 repressor as building blocks

Single-chain derivatives of the 434 repressor containing onewild-type and one mutant DNA-binding domain recognize the generaloperator ACAA–6 base pairs–NNNN, where the ACAAoperator subsite is contacted by the wild-type and the NNNNtetramer by the mutant domain. The DNA-binding specificitiesof several single-chain mutants were studied in detail and theoptimal subsites of the mutant domains were determined. Thecharacterized mutant domains were used as building units toobtain homo- and heterodimeric single-chain derivatives. TheDNA-binding properties of these domain-shuffled derivativeswere tested with a series of designed operators of NNNN–6base pairs–NNNN type. It was found that the binding specificitiesof the mutant domains were generally maintained in the new environmentsand the binding affinities for the optimal DNA ligands werehigh (with K_d values in the range of 10^–11–10^–10M). Considering that only certain sequence motifs in place ofthe six base pair spacer can support optimal contacts betweenthe mutant domains and their subsites, the single-chain 434repressor mutants are highly specific for a limited subset of14 base pair long DNA targets.     

Formalizing the construction of populations in multi-agent simulations

In individual-centered simulations, the variety and consistency of agents' behaviors reinforce the realism and validity of the simulation. Variety increases the diversity of behaviors that users meet during the simulation. Consistency ensures that these behaviors improve the users' feeling of immersion. In this work, we address the issue of the simultaneous influence of these two elements. We propose a formalization of the construction of populations for agent-based simulations, which provides the basis for a generic and non-intrusive tool allowing an out-of-the-agent design. First, the model uses behavioral patterns to describe standards of behaviors for the agents. They provide a behavioral archetype during agents' creation, and are also a compliance reference, that allows to detect deviant behaviors and address them. Then, a specific process instantiates the agents by using the specification provided by the patterns. Finally, inference enables to automate behavioral patterns configuration from real or simulated data. This formalization allows for the easy introduction of variety in agents' behaviors, while controlling the conformity to specifications. We applied the model to traffic simulation, in order to introduce driving styles specified using behavioral patterns (e.g. cautious or aggressive drivers). The behavioral realism of the traffic was therefore improved, and the experimentations we conducted show how the model contributes to increase the variety and the representativeness of the behaviors.