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Topic Review
SU(2)/SU(3) Quantum Yang-Mills theory Thermodynamics
An outline of the main, purely theoretical ideas involved in Quantum Yang-Mills thermodynamics is given and implications thereof for applications in cosmology, particle, plasma, and condensed-matter physics are sketched. On the theoretical side, we elucidate the concepts of the thermal ground states of the deconfining and preconfining phases together with their gauge-mode excitations , and we discuss the quantum vacuum of the confining phase including its finite-extent excitations. On the application side, we briefly mention how deconfining SU(2) Yang-Mills thermodynamics, when postulated to describe thermal photon gases, predicts a modified temperature (T) -redshift (z) relation for the Cosmic Microwave Background (CMB) which, in turn, implies a rearrangement of the dark sector well before the onset of nonlinear structure formation. All-z fits of the ensuing cosmological model to the observed angular power spectra  (CMB) yield a value for the present Hubble parameter H0 agreeing with that extracted from local distance measurements, a baryon density of the present Universe being about 30% smaller than the standard value obtained from Big-Bang-Nucleosynthesis (BBN) but matching direct censuses, and a late onset of reionisation of the Universe agreeing with the observation of the Gunn-Peterson trough in high-z quasar spectra. We also mention how the three lepton families of the Standard Model of Particle Physics (SMPP) could emerge as solitons immersed into the confining  phases of three SU(2) Yang-Mills theories, subject to mixing of their Cartan subalgebras. In particular, the electron and its neutrino would be represented by 1-fold selfintersecting and single, stable center-vortex loops with a wealth of implications for strongly correlated charge carriers in the two spatial dimensions of  certain condensed-matter systems as well as ultra hot plasmas.
  • 1.9K
  • 30 Oct 2020
Topic Review
Near-Infrared Graphene/Silicon Photodetectors
In recent years, graphene has attracted much interest due to its unique properties of flexibility, strong light-matter interaction, high carrier mobility and broadband absorption. In addition, graphene can be deposited on many substrates including silicon with which is able to form Schottky junctions, opening the path to the realization of near-infrared photodetectors based on the internal photoemission effect where graphene plays the role of the metal.
  • 1.1K
  • 29 Oct 2020
Topic Review
Standard and Alternative Cosmology
The Standard and The Alternative Cosmological Models, Distances Calculation to Galaxies without Hubble Constant For the alternative cosmological models considered in the extended version of this entry, the distances  are calculated for galaxies without using the Hubble constant. This process is mentioned in the second narrative, and described in detail in the third narration. According to the third narrative, as the density of the relativistic mass of the universe decreases while the universe expands, new matter is created by a phase transition process which results in a continuously constant ordinary density of matter. While the universe develops on the basis of this postulate of the emergence of new matter, it is "assumed that matter arises as a result of such a phase transition of dark energy into both new dark and visible matter. It is somewhat irrelevant how we describe dark energy, calling it aether, or vice versa, the changing of aether into dark energy. It should be clear to everyone that this renaming does not change the essence of this phase transition phenomena. It should be noted that, unlike all well‐known geometric models of the Euclidean space of our existence, this phase transition of dark energy into matter would accordingly be a stereographic projection of a three‐dimensional surface on to a four‐dimensional globe.
  • 1.5K
  • 29 Oct 2020
Topic Review
Wearable Body Sensors
The use of wearable body sensors for health monitoring is a quickly growing field with the potential of offering a reliable means for clinical and remote health management. This includes both real-time monitoring and health trend monitoring with the aim to detect/predict health deterioration and also to act as a prevention tool. The aim of this systematic review was to provide a qualitative synthesis of studies using wearable body sensors for health monitoring. The synthesis and analysis have pointed out a number of shortcomings in prior research. Major shortcomings are demonstrated by the majority of the studies adopting an observational research design, too small sample sizes, poorly presented, and/or non-representative participant demographics (i.e., age, gender, patient/healthy). These aspects need to be considered in future research work.
  • 1.5K
  • 29 Oct 2020
Topic Review
Gabor-Domain Optical Coherence Microscopy
Gabor-domain optical coherence microscopy (GDOCM) is a high transverse resolution variant of spectral domain optical coherence tomography (SD-OCT). It was proposed to break the cellular resolution limit of optical coherence tomography (OCT). GDOCM achieves invariant transverse and axial resolutions of 2 micron in 3D by fusing together multiple volumetric images that are acquired employing a liquid lens to dynamically refocus at different depths inside the sample with no moving parts.
  • 2.6K
  • 29 Oct 2020
Topic Review
Optical Coherence Angiography Imaging in Ocular Vascular Diseases
Optical coherence tomography angiography (OCTA) provides us with a non-invasive and efficient means of imaging anterior and posterior segment vasculature in the eye. OCTA has been shown to be effective in imaging diseases such as diabetic retinopathy, retinal vein occlusions, retinal artery occlusions, ocular ischemic syndrome and neovascularization of the iris. It is especially useful with depth-resolved imaging of the superficial, intermediate, and deep capillary plexi in the retina, which enables us to study and closely monitor disease progression and response to treatment. With further advances in technology, OCTA has the potential to become a more widely used tool in the clinical setting and may even supersede ocular angiography in some areas.
  • 1.5K
  • 29 Oct 2020
Topic Review
Quantum Measurement
The Special State Theory of Quantum MeasurementL. S. Schulman1   There is only pure unitary time evolution in the special state theory of quantum measurement. In this, it resembles the Many Worlds Interpretation. Nevertheless, there is only one world. This is accomplished by means of “special states” and significant modification the arrow of time. Experimental tests are described, although they have yet to be done.
  • 937
  • 29 Oct 2020
Topic Review
Quantification of 5f Delocalization
By using M4,5 X-ray Emission Spectroscopy (XES) in the tender X-ray regime, it is possible to quantify 5f delocalization in the actinides. Previous analyses, utilizing the Branching Ratio (BR) in the N4,5 X-ray Absorption Spectroscopy (XAS), could not discriminate between the cases of localized n = 2 and delocalized n = 3, in uranium materials, where n is the number of 5f electrons on the U entity. Here, it is shown that, by employing the ubiquitous 6p→3d XES as a point of normalization, the localized n = 2 and delocalized n = 3 cases can be easily distinguished and quantified.
  • 850
  • 29 Oct 2020
Topic Review
RFID Sensors for IoT
Abstract: Radio-frequency identification (RFID) sensors are one of the fundamental components of the Internet of Things.  Within this framework, chipless RFIDs are a breakthrough technology because, removing the cost associated with the chip, are at the same time printable, passive, low-power and suitable for harsh environments. For this reason, there is a clear motivation and interest to extend the chipless sensing functionality to physical, chemical, structural and environmental parameters. Temperature and humidity sensors, as well as localization, proximity, and structural health prototypes, have already been produced, and many other sensing applications are on the way. In this review, architectural approaches and requirements related to the materials employed for chipless RFID sensing are summarized. The state-of-the-art of many categories of sensors and their applications is reported and an analysis of the current limitations and possible solution strategies are given, together with an overview of expected future developments.
  • 1.7K
  • 29 Oct 2020
Topic Review
Gyrotrons
Gyrotrons are among the most powerful sources of coherent radiation that operate in CW and long pulse regimes in the sub-THz and the THz frequency ranges of the electromagnetic spectrum, i.e. between 0.3 THz and 3.0 THz (corresponding to wavelengths from 1.0 to 0.1 mm). This region, which spans between the frequency bands occupied by various electronic and photonic devices, respectively, is habitually called a THz power gap. The underlying mechanism of the operation of the gyrotron involves a formation of bunches of electrons gyrating in a helical electron beam and their synchronous interaction with a fast (i.e. having a superluminal phase velocity) electromagnetic wave, producing a bremsstrahlung radiation. In contrast to the slow-wave tubes, which utilize tiny structures with dimensions comparable to the wavelength of the radiation, the gyrotrons have a simpler resonant system (cavity resonator) with dimensions that are much greater than the wavelength. This allows much more powerful electron beams to be used and thus higher output powers to be achieved. Although in comparison with the classical microwave tubes the gyrotrons are characterized by greater volume and weight due to the presence of bulky parts (such as superconducting magnets and massive collectors where the energy of the spent electron beam is dissipated) they are much more compact and can easily be embedded in a sophisticated laboratory equipment (e.g. spectrometers, technological systems, etc.) than other devices such as free-electron lasers (FEL) and radiation sources based on electron accelerators. Nowadays, the gyrotrons are used as powerful sources of coherent radiation in the wide fields of high-power sub-THz and THz science and technologies [1][2][3].
  • 1.9K
  • 29 Oct 2020
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