Behavior of Generated Gas during Femtosecond Laser Lens Irradiation in Porcine Cadaver Eyes

(1) Background: We investigated the behavior of gas inside a lens and its influence on the lens capsule, which may cause complications by lens irradiation with a femtosecond laser cataract surgery device. (2) Methods: The crystalline lenses of 6-month-old porcine cadaver eyes were observed during laser irradiation. An intraocular endoscope in the vitreous cavity was used to measure the posterior capsule position. Optical coherence tomography measurements of the anterior chamber depth before and after the laser irradiation, as well as measurements of the equatorial perimeter of the extracted lens, were compared with those of the controls. (3) Results: Femtosecond laser-generated gas in the porcine lens was dependent on laser irradiation energy. Increases in the amount of laser irradiation energy caused the generated gas to coalesce, move backwards beyond the laser irradiation site, and expand the lens capsule and posterior capsule. (4) Conclusions: The present results suggest that laser irradiation-induced gas moves in the direction of the posterior capsule beyond the lens irradiation site and expands the lens capsule, which may be involved in the development of capsular block syndrome.

Multiobjective Core Reloading Pattern Optimization of PARR-1 Using Modified Genetic Algorithm Coupled with Monte Carlo Methods

In order to maximize both the life cycle and efficiency of a reactor core, it is essential to find the optimum loading pattern. In the case of research reactors, a loading pattern can also be optimized for flux at an irradiation site. Therefore, the development of a general-use methodology for core loading optimization would be very valuable. In this paper, general-use multiobjective core reloading pattern optimization is performed using modified genetic algorithms (MGA). The developed strategy can be applied for the constrained optimization of research and power reactor cores. For an optimal reactor core reloading design strategy, an intelligent technique GA is coupled with the Monte Carlo (MC) code SuperMC developed by the FDS team in China for nuclear reactor physics calculations. An optimal loading pattern can be depicted as a configuration that has the maximum keff and maximum thermal fluxes in the core of the given fuel inventory keeping in view the safety constraints such as limitation on power peaking factor. The optimized loading patterns for Pakistan Research Reactor-1 (PARR-1) have been recommended using the implemented strategy by considering the constraint optimization, i.e., to maximize the keff or maximum thermal neutron flux while maintaining low power peaking factor. It has been observed that the developed intelligent strategy performs these tasks with a reasonable computational cost.

LIPUS Setting and Combined Effect With Therapeutic Exercise for Knee Osteoarthritis: A Systematic Review

[PURPOSE] Knee osteoarthritis (OA) is a chronic progressive disorder characterized by pain and decreased joint function. In the conservative treatment for the knee OA, the physiotherapy is known to be a common intervention. Recently, low-intensity pulsed ultrasound therapy (LIPUS) which has an effect on knee pain of knee OA has been used with therapeutic exercise. However, the combined effect of LIPUS with therapeutic exercise did not have enough evidence.This study was conducted to assess both setting off the LIPUS and combined effect of the therapeutic exercise in the Knee OA.[METHODS] PubMed, PEDro, CENTRAL were searched for RCTs on published before September 2019. The irradiation intensity, irradiation site, and treatment period of LIPUS were examined. Meta-analysis was performed to analyze the short and long term combined effect which was LIPUS with therapeutic exercise on the VAS score. Statistical calculations of both LIPUS with therapeutic exercise group and only therapeutic exercise group were compared from detailed data of the all eligible studies [RESULTS] Seven RCTs were eligible. Both irradiation intensity and site were varied. Three RCTs were included in the meta-analysis, involving a total of 210 knees. There was no significant improvement in pain in the LIPUS with therapeutic exercise (LIPUS) group compared with the therapeutic exercise group in short-term (MD; -6.86, 95% CI; -18.70 to 4.99 , I2 = 74%, heterogeneity: P = 0.02) and long-term (MD; -16.01 95% CI; -32.03 to 0.01, I2 = 82%, heterogeneity: P = 0.004) effects.[CONCLUSIONS]We did not find consistent evidence of the effects of combined to LIPUS and therapeutic exercise for Knee OA. Because, selected trials were varied in intensity and irradiation site and treatment durations, which might contribute to the existence of heterogeneity. Furthermore, there were few RCTs that resulted in knee joint function.The LIPUS combined therapeutic exercise found no significant decrease the knee pain than therapeutic exercise. Therefore, RCTs were recommended by well-designed intensity and irradiation site.

Modeling and parameter identification for real-time temperature controlled retinal laser therapies

Laser photocoagulation is a widely used treatment for a variety of retinal diseases. Temperature-controlled irradiation is a promising approach to enable uniform heating, reduce the risks of over- or undertreatment, and unburden the ophthalmologists from a time consuming manual power titration. In this paper, an approach is proposed for the development of models with different levels of detail, which serve as a basis for improved, more accurate observer and control designs. To this end, we employ a heat diffusion model and propose a suitable discretization and subsequent model reduction procedures. Since the absorption of the laser light can vary strongly at each irradiation site, a method for identifying the absorption coefficient is presented. To identify a parameter in a reduced order model, an optimal interpolatory projection method for parametric systems is used. In order to provide an online identification of the absorption coefficient, we prove and exploit monotonicity of the parameter influence.

Highly reliable, targeted photothermal cancer therapy combined with thermal dosimetry using indocyanine green lactosome

Indocyanine green (ICG) is a near-infrared light-absorbing substance. Thus, when a tumor in which ICG has accumulated is irradiated with a near-infrared (NIR) laser, only the tumor can be heated by a photothermal reaction. We developed ICG lactosome, a novel drug delivery system (DDS) composed of polymeric micelles and ICG that shows selective accumulation in tumor based on an enhanced permeability and retention (EPR) effect. We showed that ICG lactosome accumulated in a tumor by using an intradermal tumor mouse model of a murine colon cancer cell line (Colon26) transfected with Nano lantern luminescent protein (NLC26). Two days after the administration of ICG lactosome, the tumor was irradiated with an 808-nm diode-laser while monitoring tumor temperature. The results showed that the treated tumors were cured when the peak of tumor temperature during NIR irradiation reached 43°C or higher. To verify these results, photothermal therapy (PTT) using ICG lactosome was carried out using a newly developed system that can control the temperature at the NIR irradiation site at a constant level. All of the tumors that had been kept at 43°C during irradiation were cured, while 2 of 5 tumors that had been kept at 42°C were not cured, and none of tumors that had been kept at a temperature below 41°C were cured. ICG lactosome-assisted PTT combined with thermal dosimetry is a highly reliable method for cancer treatment and may afford further clinical opportunities for PTT.

Temperature-controlled laser therapy of the retina via robust adaptive H ∞ {\mathcal{H}_{\infty }}-control

Recent studies demonstrate therapeutic benefits in retinal laser therapy even for non-visible effects of the irradiation. However, in practice, ophthalmologists often rely on the visual inspection of irradiation sites to manually set the laser power for subsequent ones. Since absorption properties vary strongly between sites, this procedure can lead to under- or over-treatment. To achieve safe automatic retinal laser therapy, this article proposes a robust control scheme based on photoacoustic feedback of the retinal temperature increase. The control scheme is further extended to adapt to real-time parameter estimates and associated bounds on the uncertainty of each irradiation site. Both approaches are successfully validated in ex vivo experiments on pigs’ eyes, achieving consistent irradiation durations of 55 ms despite the uncertainty in absorption properties.

Axial Flux Wire Measurements at the McMaster Nuclear Reactor

In a 2008 report on safety analysis for research reactors, the International Atomic Energy Agency (IAEA) identified experimentation as the preferred method of code validation [1]. However, many experiments currently used for code validation are performed under conditions that are not representative of real nuclear systems. Furthermore, the predominant uncertainties reported for reactor systems parameters are typically those associated with evaluated nuclear data libraries however, the significance of spatial uncertainties remains generally unknown. The magnitude of local flux measurement experimental uncertainties have not be investigated at length in the McMaster Nuclear Reactor (MNR). Such results can be used for validation of MNR models with both Monte Carlo N Particle (MCNP) and Serpent code packages. Flux wire measurements have previously been conducted at the center of an irradiation site (via the technique of neutron activation analysis), where a locally uniform flux distribution has been assumed. Early stage results show good agreement with three-dimensional neutron diffusion theory and demonstrate the viability of such measurements for continued analysis. However, the magnitude of the effects of Xenon buildup, control rod positions, and spatial sample positioning on the data remain unknown, and so a series of experiments is ongoing to address these areas of experimental variability. Full length flux wire irradiations at several high-power levels (500 kW, 800 kW, and 1 MW) are being conducted to quantify these effects. At each operating power level, several NiCr wires are irradiated, and the decay of 51Cr examined to determine the total neutron flux in the irradiation site. The use of multiple wires per irradiation provides insight into the spatial gradient of the neutron flux across one reactor site (approximately 8 × 8 cm).

Central origin of pinprick hyperalgesia adjacent to an UV-B induced inflammatory skin pain model in healthy volunteers

Background and purposeThe UV-B model is an established pain model of different types of hyperalgesia in animal and human pain research. Beside the skin region of the sunburn in human volunteers pinprick hyperalgesia has been described in a large zone of non-inflamed skin adjacent to the sunburn. However, there are opposing results on the existence of pinprick hyperalgesia and most notably a controversial discussion is still on-going whether this mechanical hyperalgesia in the undamaged tissue adjacent to and at some distance from the site of inflammation is of peripheral or central origin. We therefore addressed this in our study by hypothesising that pinprick hyperalgesia around a circular spot of UV-B inflamed skin is not reduced by a superficial local anaesthetic block and therefore underlies centrally mediated mechanisms.MethodsThis exploratory study was conducted in a prospective, controlled, randomised, single-blinded fashion in relation to the study hypothesis in 12 healthy volunteers. Before circular irradiation with UV-B light (3-times the individual minimal erythema dose at both thighs), a strip of continuous intradermal local anaesthetic block with lidocaine 2% was established via two single plasmaphoresis hollow fibres. These were positioned perpendicular to one thigh overlapping on the midline of the leg at the distal part of the planned irradiation site, and compared with the contralateral control side without anaesthetic block. The local anaesthetic block was established and then maintained via a syringe pump. The area of pinprick hyperalgesia was measured by pricking on a large skin surface including 360° around the circular irradiation site. This was done with a slightly painful pin (256 mN) until 8h after irradiation. Primary outcome was the area of pinprick hyperalgesia in the skin adjacent to the sunburn at 8h.ResultsLarge areas of mechanical hyperalgesia to pinprick surrounding the adjacent skin of the sunburn developed on both sides after 8h without any significant difference between the side of the anaesthetic strip showing an area of 72.6±39.7 cm2 (mean±SD) and the control side (59.1±20.1 cm2); p = 0.24. Moreover, mechanical hyperalgesia to various pin stimuli of different strength was unchanged by the anaesthetic block.ConclusionThis trial provides evidence that the development of mechanical hyperalgesia surrounding an experimental sunburn was not influenced by continuous peripheral afferent blockade with local anaesthetic at 8h after UV-B irradiation. Our data support the hypothesis that in the UV-B model peripheral nociceptive afferent input of inflamed skin may enhance central hypersensitivity of mechanosensitive nociceptors in a larger receptive field far beyond the inflamed skin. Furthermore, these findings are in line with other pain models demonstrating comparable central hypersensitivity around the site of injury.ImplicationsAs for other pain models this finding provides further evidence that the UV-B model offers secondary mechanical hyperalgesia in addition to its known primary hyperalgesia. Consequently, this is a further validation for the utilisation of the UV-B model in human pain research.