Implantable photonic probes are of increasing interest to the field of biophotonics and in particular, optogenetic neural stimulation. Active probes with onboard light emissive elements allow for electronic multiplexing and can be manufactured through existing microelectronics methods. However, as the optogenetics field moves towards clinical practice, an important question arises as to whether such probes will cause excessive thermal heating of the surrounding tissue. Light emitting diodes typically produce more heat than light. The resultant temperature rise of the probe surface therefore needs to be maintained under the regulatory limit of 2°C. This work combines optical and thermal modelling, which have been experimental verified. Analysis has been performed on the effect of probe/emitter geometries, emitter, and radiance requirements. Finally, the effective illumination volume has been calculated within thermal limits for different probe emitter types and required thresholds.
We aimed at investigating the effect of carbon dots on the BALB/c mice immune system. Mice were respectively treated with different doses of carbon dots and saline. At 1 and 9 days after intravenous administration of carbon dots, splenocyte proliferation, subpopulation of the peripheral lymphocytes, and induction of primary immune responses in mice were investigated. The results showed that high dose of carbon dots could promote the percentages of CD3+ and interferon-γ (IFN-γ) secretion and decrease the proportions of CD4+/CD8+ on the first day after administration. At 9 days post exposure, the proliferation of splenocytes had a significant increase. IFN-γ secretion and proportions of CD3+/CD19+ were also found to have an obvious promotion, and both the percentages of CD4+ and CD8+ T lymphocytes were raised, whereas the expression of cytokines made little change in the treated groups, except for IL-12 which had a slight increase in the 50-mg/kg group. The weight coefficients and histological analysis of the spleen and thymus of the treated mice exerted fewer differences compared with those from the control mice. It suggests that carbon dots could influence the immune functions of normal BALB/c mice by inducing Th1 and Tc responses and that these effects were not enough to induce the morphological change of the immune organs.
There is a growing demand for the development of new types of implantable optoelectronics to support both basic neuroscience and optogenetic treatments for neurological disorders. Target specification requirements include multi-site optical stimulation, programmable radiance profile, safe operation, and miniaturization. It is also preferable to have a simple serial interface rather than large numbers of control lines. This paper demonstrates an optrode structure comprising of a standard complementary metal-oxide-semiconductor process with 18 optical stimulation drivers. Furthermore, diagnostic sensing circuitry is incorporated to determine the long-term functionality of the photonic elements. A digital control system is incorporated to allow independent multisite control and serial communication with external control units.
This paper analyzes the problems and contradictions that occur when the traditional special theory of relativity which uses the speed of light in a vacuum as an invariant constant, studies the propagation of light in media. These problems are re-examined and discussed with the special theory of relativity of variable speed of light. The transformation relationship of the characteristic quantities describing light wave frequency ν, phase velocity w and the direction angle α of the wave normal between the two inertial coordinate systems in vacuum S and in medium S' were derived; combining the transformation of the light ray speed u which describes light granular motion, the de Broglie wave-particle velocity relationship in the vacuum u w = c2 is νextended to the medium to become u' w' = c'2. Corrected the approach of the traditional special theory of relativity when dealing with these problems, in which the transformation from the space-time coordinates to the relevant physical quantity is limited to the half-sided transformation of the media into the vacuum (not two sided transformation), so that the resulting contradictions and problems are all solved. Optical experiments that support the traditional special theory of relativity, such as the Fizeau experiment and the Michelson-Morley experiment, not only still support and agree with the generalized special theory of relativity with variable speed of light, but also obtain a more correct and satisfactory interpretation from it.
In this paper, the special theory of relativity in different media is established, based on the fundamental invariant of the space-time four-dimensional space x2 + y2 + z2 - c2 t2 = x'2 + y'2 + z'2 - c' t'2 . First of all, the inertial coordinate system is strictly defined in mathematical language. The inertial coordinate system that uses the actual measured different speeds of light as the limit speed still retains its most basic characteristics as an inertial coordinate system. Then, the space-time coordinate transformation and velocity transformation formulas between inertial coordinate systems with different light velocity are derived. These results not only break through the limitation of "vacuum", but also all are exactly the same as the conclusions of the traditional special theory of relativity when c = c' ; and when c ≠ c' give the new physical content. This all lifted the threat of the theory of relativity by the speed of light experiment, making c = c' ; and c ≠ c' both inclusively under the basic point of view of the theory of relativity; which will inevitably broaden the way of using relativity to deal with physics problems and clarify many problems left over in the study of relativity. The article discusses the problem of relativistic kinematics involving the measurement of time and space, correctly interprets the effects of “ruler contraction” and “clock retardation”, and uncovers and correctly answers the “clock paradox” that accompanied the birth of relativity. For two motion systems S and S', that are separated from each other by constant velocity, at any time and where, the product of the proper time elapsed evenly and uniformly and the speed of light in the respective system are equal, cτ = c' τ'; and the product of the coordinates time read out in observing and recognizing the other party's proper time and the speed of light in the respective system are also equal, ct = c' t' . It is confirmed that the product of any moving individual's uniform disappearance proper time and its measured speed of light remain unchanged; and the proper time cannot be determined purely by the individual's subjective way. Deduced the uncertain relationship between the proper time and the coordinate time for an inertial coordinate system which was not noticed by the traditional special theory of relativity. Remind the practical astronomy workers who do the time measurement and the time service work to understand that it is impossible to equate practical scientific coordinate time and the proper time of ideal uniform disappearance (the so-called “Ephemeris Time”). Thereby pay attention to the impact of this uncertain relationship on the time measurement and the time service work, and propose ways to verify. Subsequent work will use this expanded special theory of relativity to conduct a comprehensive review of related physics, which will inevitably extend to issues that have not been or cannot be examined by traditional special theory of relativity.
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