Circularly polarized implantable antenna characterization for retinal prosthesis systems

We describe a miniaturized antenna design for retinal prosthesis applications that enhances data transfer between the implant and external camera. The circularly polarized and conformal 2.4–2.48 GHz microstrip patch antenna was simulated inside the vitreous humor and is intended for biomedical applications. Modified Hilbert and serpentine geometries were used for the proposed implant antenna design. Capacitive radiator loading offered miniaturized dimensions of 5.8 × 6.5 × 2 mm³ (width × height × thickness mm³). A truncated design enhanced the intrinsic circular polarization characteristics to >3 dB axial ratio. Polydimethylsiloxane substrate and superstrate materials were used to achieve an S11 value below –15 dB across the frequency range with biocompatible characteristics. The simulated peak gains for left-hand circular polarization and right-hand circular polarization at 2.45 GHz were –50 dBi and –60 dBi, respectively. These relatively small values were due to the high conductivity of the vitreous humor (s = 1.53 S/m), which imposed significant losses. Overall, the proposed antenna had an omnidirectional radiation pattern and +8.45 dBm input to meet the specific absorption rate regulation limit

Electrometry of a single resonator mode at a Rydberg-atom–superconducting-circuit interface

The electric-field distribution in a single mode of a λ/4 superconducting coplanar waveguide (CPW) microwave resonator has been probed using beams of helium Rydberg atoms. In the experiments the atoms were prepared in the 1s55s3S1 Rydberg level by laser photoexcitation. They then traveled over the CPW resonator that was fabricated on a NbN superconducting chip operated at 3.8 K. The resonator was driven at its third-harmonic frequency, near resonant with the two-photon 1s55s3S1→1s56s3S1 transition at ω55s,56s/2=2π×19.556499 GHz. The coherence times of the atom–resonator-field interaction were determined at selected locations above the resonator by time-domain measurements of Rabi oscillations and found to be up to 0.8μs for Rabi frequencies of ∼2π×3 MHz. The coherence times of the atomic superposition states, generated following the interaction of the atoms with the microwave field in the resonator, were inferred from high-resolution cavity-enhanced Ramsey spectra to be ∼2.5μs. These Ramsey spectra also allowed the measurement of residual uncanceled dc electric fields of 26.6±0.6 mV/cm at the position of the atoms ∼300μm above the surface of the superconducting chip. These results represent an essential step toward applications of hybrid systems, comprising Rydberg atoms coherently coupled to superconducting microwave circuits, in quantum optics and quantum information processing

Bleed-induced distortion in axial compressors

In this paper, the influence of nonuniform bleed extraction on the stability of an axial flow compressor is quantified. Nonuniformity can be caused by several geometric factors (for example, plenum chamber size or number of off-take ducts), and a range of configurations is examined experimentally in a single stage compressor. It is shown that nonuniform bleed leads to a circumferential distribution of flow coefficient and swirl angle at inlet to the downstream stage. The resultant distribution of rotor incidence causes stall to occur at a higher flow coefficient than if the same total bleed rate had been extracted uniformly around the circumference. A connection is made between the analysis of nonuniform bleed extraction and the familiar DCθ criterion used to characterize inlet total pressure distortion. The loss of operating range caused by the nonuniform inlet flow correlates with the peak sector-averaged bleed nonuniformity for all the bleed configurations tested.This is a metadata record relating to an article that cannot be shared due to publisher copyright

Cavity-enhanced Ramsey spectroscopy at a Rydberg-atom–superconducting-circuit interface

The coherent interaction of Rydberg helium atoms with microwave fields in a λ/4 superconducting coplanar waveguide resonator has been exploited to probe the spectral characteristics of an individual resonator mode. This was achieved by preparing the atoms in the 1s55s 3S1 Rydberg level by resonance enhanced two-color two-photon excitation from the metastable 1s2s 3S1 level. The atoms then traveled over the resonator in which the third harmonic microwave field, at a frequency of ωres=2π×19.556 GHz, drove the two-photon 1s55s 3S1 → 1s56s 3S1 transition. By injecting a sequence of Ramsey pulses into the resonator and monitoring the coherent evolution of the Rydberg state population by state-selective pulsed electric field ionization as the frequency of the microwave field was tuned, spectra were recorded that allowed the resonator resonance frequency and quality factor to be determined with the atoms acting as microscopic quantum sensors

Implementation of 4kUHD HEVC-content transmission

The Internet of things (IoT) has received a great deal of attention in recent years, and is still being approached with a wide range of views. At the same time, video data now accounts for over half of the internet traffic. With the current availability of beyond high definition, it is worth understanding the performance effects, especially for real-time applications. High Efficiency Video Coding (HEVC) aims to provide reduction in bandwidth utilisation while maintaining perceived video quality in comparison with its predecessor codecs. Its adoption aims to provide for areas such as television broadcast, multimedia streaming/storage, and mobile communications with significant improvements. Although there have been attempts at HEVC streaming, the literature/implementations offered do not take into consideration changes in the HEVC specifications. Beyond this point, it seems little research exists on real-time HEVC coded content live streaming. Our contribution fills this current gap in enabling compliant and real-time networked HEVC visual applications. This is done implementing a technique for real-time HEVC encapsulation in MPEG-2 Transmission Stream (MPEG-2 TS) and HTTP Live Streaming (HLS), thereby removing the need for multi-platform clients to receive and decode HEVC streams. It is taken further by evaluating the transmission of 4k UHDTV HEVC-coded content in a typical wireless environment using both computers and mobile devices, while considering well-known factors such as obstruction, interference and other unseen factors that affect the network performance and video quality. Our results suggest that 4kUHD can be streamed at 13.5 Mb/s, and can be delivered to multiple devices without loss in perceived quality

National counter-terrorism (C-T) policies and challenges to human rights and civil liberties: Case study of United Kingdom

In the UK the rise post-2005 in “home-grown” terrorism, relying to a significant extent on strikes on soft targets by “self-starters,” means that the search for effective preventive measures remains a continuing concern. Below a number of the preventive counter-terror measures adopted post-9/11, and incrementally strengthened in response to the current threat, are found to fall into three categories and represent interventions at the stages in the path toward attacks. This chapter focuses on selected examples of these preventive measures. In terms of three key stages, firstly, there is the attempt to prevent radicalization, under the “Prevent” strategy. A second strategy relies on taking certain measures to control the activities of those considered likely – on the balance of probabilities – to engage in terrorist-related activity. A third preventive strategy relies on the special terrorism offences under the Terrorism Acts 2000 and 2006, as amended, intended to allow for intervention at a very early stage in terrorist plots and in preparing or instigating terrorist acts (“precursor” offences)

Age at death estimation from bone histology in Malaysian males.

Estimation of age from microscopic examination of human bone utilizes bone remodeling. This allows 2 regression equation to be determined in a specific population based on the variation in osteon turnover in different populations. The aim of this study was to provide age estimation for Malaysian males. Ground undecalcified cross sections were prepared from long limb bones of 50 deceased males aged between 21 and 78 years. Ten microstructural parameters were measured and subjected to multivariate regression analysis. Results showed that osteon count had the highest correlation with age (R = 0.43), and age was estimated to be within 10.94 years of the true value in 98% of males. Cross validation of the equation on 50 individuals showed close correspondence of true ages with estimated ages. Further studies are needed to validate and expand these results

Who consults chiropractors in Victoria, Australia?: Reasons for attending, general health and lifestyle habits of chiropractic patients

Background COAST (Chiropractic Observational and Analysis STudy) reported the clinical practices of chiropractors. The aims of this study were to: 1) describe the chiropractic patient demographic and health characteristics; 2) describe patient-stated reasons for visiting a chiropractor; 3) describe chiropractic patient lifestyle characteristics; 4) compare, where possible, chiropractic patient characteristics to the general Australian population. Methods Fifty-two chiropractors in Victoria, Australia, provided information for up to 100 consecutive encounters. If patients attended more than once during the 100 encounters, only data from their first encounter were included in this study. Where possible patient characteristics were compared with the general Australian population. Results Data were collected from December 2010 to September 2012. Data were provided for 4464 encounters, representing 3287 unique individuals. The majority of chiropractic encounters were for musculoskeletal conditions or for wellness/maintenance. The majority of patient comorbidities were musculoskeletal, circulatory or endocrine/metabolic in nature. Eight hundred chiropractic patients (57 %, 95 % CI: 53–61) described their self-reported health as excellent or very good and 138 patients (10 %, 95 % CI: 8–12) as fair or poor. Seventy-one percent of adult male patients (18 years and older), and 53 % of adult female patients, were overweight or obese. Fourteen percent (n = 188, 95 % CI: 12–16) were current smokers and 27 % (n  = 359, 95 % CI: 24–31) did not meet Australian alcohol consumption guidelines. Less than half of the chiropractic patients participated in vigorous exercise at least twice per week. Approximately 20 % ate one serving of vegetables or less each day, and approximately 50 % ate one serve of fruit or less each day. Compared to the general Australian population, chiropractic patients were less likely to smoke, less likely to be obese and more likely to describe their health in positive terms. However, many patients were less likely to meet alcohol consumption guidelines, drinking more than is recommended. Conclusions In general, chiropractic patients had more positive health and lifestyle characteristics than the Australian population. However, there were a significant proportion of chiropractic patients who did not meet guideline recommendations about lifestyle habits and there is an opportunity for chiropractors to reinforce public health messages with their patients

Screening for celiac disease in the general population and in high-risk groups

BACKGROUND: Celiac disease (CD) occurs in approximately 1% of the Western population. It is a lifelong disorder that is associated with impaired quality of life (QOL) and an excessive risk of comorbidity and death. OBJECTIVES: To review the literature on screening for CD in relation to the current World Health Organization (WHO) criteria for mass screening. METHODS: We performed a PubMed search to identify indexed papers on CD screening with a publication date from 1900 until 1 June 2014. When we deemed an abstract relevant, we read the corresponding paper in detail. RESULTS: CD fulfills several WHO criteria for mass screening (high prevalence, available treatment and difficult clinical detection), but it has not yet been established that treatment of asymptomatic CD may reduce the excessive risk of severe complications, leading to higher QOL nor that it is cost-effective. CONCLUSIONS: Current evidence is not sufficient to support mass screening for CD, but active case-finding may be appropriate, as we recognize that most patients with CD will still be missed by this strategy. Although proof of benefit is still lacking, screening for CD may be appropriate in high-risk groups