Measurement of the Near Field Distribution of a Microwave Horn Using a Resonant Atomic Probe

We measure the near field distribution of a microwave horn with a resonant atomic probe. The microwave field emitted by a standard microwave horn is investigated utilizing Rydberg electromagnetically inducted transparency (EIT), an all-optical Rydberg detection, in a room temperature caesium vapor cell. The ground 6S1/2 , excited 6P3/2 , and Rydberg 56D5/2 states constitute a three-level system, used as an atomic probe to detect microwave electric fields by analyzing microwave dressed Autler–Townes (AT) splitting. We present a measurement of the electric field distribution of the microwave horn operating at 3.99 GHz in the near field, coupling the transition 56D5/2→57P3/2 . The microwave dressed AT spectrum reveals information on both the strength and polarization of the field emitted from the microwave horn simultaneously. The measurements are compared with field measurements obtained using a dipole metal probe, and with simulations of the electromagnetic simulated software (EMSS). The atomic probe measurement is in better agreement with the simulations than the metal probe. The deviation from the simulation of measurements taken with the atomic probe is smaller than the metal probe, improving by 1.6 dB. The symmetry of the amplitude distribution of the measured field is studied by comparing the measurements taken on either side of the field maxima

A Tale of Two Fractals: The Hofstadter Butterfly and The Integral Apollonian Gaskets

This paper unveils a mapping between a quantum fractal that describes a physical phenomena, and an abstract geometrical fractal. The quantum fractal is the Hofstadter butterfly discovered in 1976 in an iconic condensed matter problem of electrons moving in a two-dimensional lattice in a transverse magnetic field. The geometric fractal is the integer Apollonian gasket characterized in terms of a 300 BC problem of mutually tangent circles. Both of these fractals are made up of integers. In the Hofstadter butterfly, these integers encode the topological quantum numbers of quantum Hall conductivity. In the Apollonian gaskets an infinite number of mutually tangent circles are nested inside each other, where each circle has integer curvature. The mapping between these two fractals reveals a hidden threefold symmetry embedded in the kaleidoscopic images that describe the asymptotic scaling properties of the butterfly. This paper also serves as a mini review of these fractals, emphasizing their hierarchical aspects in terms of Farey fractions

Association Between Episodic Memory and Genetic Risk Factors for Alzheimer’s Disease in South Asians from the Longitudinal Aging Study in India–Diagnostic Assessment of Dementia (LASI‐DAD)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156473/3/jgs16735-sup-0001-supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156473/2/jgs16735_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156473/1/jgs16735.pd

Performance analysis of the generalised projection identification for time-varying systems

© The Institution of Engineering and Technology 2016. The least mean square methods include two typical parameter estimation algorithms, which are the projection algorithm and the stochastic gradient algorithm, the former is sensitive to noise and the latter is not capable of tracking the timevarying parameters. On the basis of these two typical algorithms, this study presents a generalised projection identification algorithm (or a finite data window stochastic gradient identification algorithm) for time-varying systems and studies its convergence by using the stochastic process theory. The analysis indicates that the generalised projection algorithm can track the time-varying parameters and requires less computational effort compared with the forgetting factor recursive least squares algorithm. The way of choosing the data window length is stated so that the minimum parameter estimation error upper bound can be obtained. The numerical examples are provided

Origin of the X-Ray-Induced Damage in Perovskite Solar Cells

Perovskite solar cells (PSCs) are promising candidates for not only terrestrial but also space applications. The remarkable power-per-weight of nearly 30 W/g makes them attractive to be deployed on a spacecraft. However, the high-energy radiation in outer space could damage the PSCs, making it crucial to understand their degradation mechanism. Here, we investigated the PSCs' response to X-ray radiation, and proposed that the X-ray-induced damage was attributed to the displacement of I-, creating lattice defects by the radiation-generated secondary electrons. We verified the hypothesis by simulating the energy deposition of X-rays in PSCs and investigating the PSCs' in situ electronic responses to the X-ray and electron beam. Furthermore, we studied the variation in spatial distribution of trap densities under X-ray radiation, which revealed that the defect-abundant perovskite/Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) interface was the most rapidly degraded site in PSCs

Biomedical and therapeutic applications of biosurfactants

During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases and as therapeutic agents due to their antibacterial, antifungal and antiviral activities. Furthermore, their role as anti-adhesive agents against several pathogens illustrate their utility as suitable anti-adhesive coating agents for medical insertional materials leading to a reduction of a large number of hospital infections without the use of synthetic drugs and chemicals. Biomedical and therapeutic perspectives of biosurfactants applications are presented and discussed in this chapter

Low defects density CsPbBr3single crystals grown by an additive assisted method for gamma-ray detection

Metal halide perovskites have arisen as a new family of semiconductors for radiation detectors due to their high stopping power, large and balanced electron-hole mobility-lifetime (μτ) product, and tunable bandgap. Here, we report a simple and low-cost solution processing approach using additive-assisted inverse temperature crystallization (ITC) to grow cesium lead bromide (CsPbBr3) single crystals with low-defect density. Crystals grown from precursor solutions without additives tend to grow fastest along the [002] direction, resulting in crystals shaped as small elongated bars. The addition of choline bromide (CB) proves to mediate the crystallization process to produce large single crystals with a cuboid shape, allowing for more practical fabrication of gamma-ray detectors. This new additive-assisted growth method also improves the resulting crystal quality to yield a reduction in the density of trap states by over one order of magnitude, relative to a crystal grown without CB. The detector fabricated from a CB-assisted solution-grown perovskite CsPbBr3 single crystal is able to acquire an energy spectrum from a cesium-137 (137Cs) source with a resolution of 5.5% at 662 keV

Mitochondrial DNA Copy Number and Incident Heart Failure: The Atherosclerosis Risk in Communities (ARIC) Study

Heart failure (HF) is a leading clinical and public health concern because of its high prevalence and poor prognosis. It is thus critical to identify novel risk factors for developing HF. Mitochondrial DNA copy number (mtDNA-CN), an indirect biomarker of mitochondrial dysfunction, is associated with atherosclerotic cardiovascular disease endpoints, cardiovascular risk factors, all-cause mortality, and sudden cardiac death. The association between mtDNA-CN and the risk of incident HF, however, is unknown. We examined this association in the Atherosclerosis Risk in Communities (ARIC) cohort

Modeling the Subsurface Structure of Sunspots

While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this paper, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out an helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by \citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic

On the Nature and Genesis of EUV Waves: A Synthesis of Observations from SOHO, STEREO, SDO, and Hinode

A major, albeit serendipitous, discovery of the SOlar and Heliospheric Observatory mission was the observation by the Extreme Ultraviolet Telescope (EIT) of large-scale Extreme Ultraviolet (EUV) intensity fronts propagating over a significant fraction of the Sun's surface. These so-called EIT or EUV waves are associated with eruptive phenomena and have been studied intensely. However, their wave nature has been challenged by non-wave (or pseudo-wave) interpretations and the subject remains under debate. A string of recent solar missions has provided a wealth of detailed EUV observations of these waves bringing us closer to resolving their nature. With this review, we gather the current state-of-art knowledge in the field and synthesize it into a picture of an EUV wave driven by the lateral expansion of the CME. This picture can account for both wave and pseudo-wave interpretations of the observations, thus resolving the controversy over the nature of EUV waves to a large degree but not completely. We close with a discussion of several remaining open questions in the field of EUV waves research.Comment: Solar Physics, Special Issue "The Sun in 360",2012, accepted for publicatio