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Systemic inflammation has been proposed as a relevant factor of vascular remodeling and dysfunction. We aimed to identify circulating inflammatory biomarkers that could predict future arteriovenous fistula (AVF) dysfunction in patients undergoing hemodialysis. A total of 282 hemodialysis patients were enrolled in this prospective multicenter cohort study. Plasma cytokine levels were measured at the time of data collection. The primary outcome was the occurrence of AVF stenosis and/or thrombosis requiring percutaneous transluminal angioplasty or surgery within the first year of enrollment. AVF dysfunction occurred in 38 (13.5%) patients during the study period. Plasma interleukin-6 (IL-6) levels were significantly higher in patients with AVF dysfunction than those without. Diabetes mellitus, low systolic blood pressure, and statin use were also associated with AVF dysfunction. The cumulative event rate of AVF dysfunction was the highest in IL-6 tertile 3 (p = 0.05), and patients in tertile 3 were independently associated with an increased risk of AVF dysfunction after multivariable adjustments (adjusted hazard ratio = 3.06, p = 0.015). In conclusion, circulating IL-6 levels are positively associated with the occurrence of incident AVF dysfunction in hemodialysis patients. Our data suggest that IL-6 may help clinicians identify those at high risk of impending AVF failure.

Osteoporosis, characterized by low bone mass and a disruption of bone microarchitecture, is traditionally treated using drugs or lifestyle modifications. Recently, several preclinical and clinical studies have investigated the effects of selenium on bone health, although the results are controversial. Selenium, an important trace element, is required for selenoprotein synthesis and acts crucially for proper growth and skeletal development. However, the intake of an optimum amount of selenium is critical, as both selenium deficiency and toxicity are hazardous for health. In this review, we have systematically analyzed the existing literature in this field to determine whether dietary or serum selenium concentrations are associated with bone health. In addition, the mode of administration of selenium as a supplement for treating bone disease is important. We have also highlighted the importance of using green-synthesized selenium nanoparticles as therapeutics for bone disease. Novel nanobiotechnology will be a bridgehead for clinical applications of trace elements and natural products.

Background PTEN-induced kinase 1 (PINK1) is a serine/threonine-protein kinase in mitochondria that is critical for mitochondrial quality control. PINK1 triggers mitophagy, a selective autophagy of mitochondria, and is involved in mitochondrial regeneration. Although increments of mitochondrial biogenesis and activity are known to be crucial during differentiation, data regarding the specific role of PINK1 in osteogenic maturation and bone remodeling are limited. Methods We adopted an ovariectomy model in female wildtype and Pink1−/− mice. Ovariectomized mice were analyzed using micro-CT, H&E staining, Masson’s trichrome staining. RT-PCR, western blot, immunofluorescence, alkaline phosphatase, and alizarin red staining were performed to assess the expression of PINK1 and osteogenic markers in silencing of PINK1 MC3T3-E1 cells. Clinical relevance of PINK1 expression levels was determined via qRT-PCR analysis in normal and osteoporosis patients. Results A significant decrease in bone mass and collagen deposition was observed in the femurs of Pink1−/− mice after ovariectomy. Ex vivo, differentiation of osteoblasts was inhibited upon Pink1 downregulation, accompanied by impaired mitochondrial homeostasis, increased mitochondrial reactive oxygen species production, and defects in mitochondrial calcium handling. Furthermore, PINK1 expression was reduced in bones from patients with osteoporosis, which supports the practical role of PINK1 in human bone disease. Conclusions In this study, we demonstrated that activation of PINK1 is a requisite in osteoblasts during differentiation, which is related to mitochondrial quality control and low reactive oxygen species production. Enhancing PINK1 activity might be a possible treatment target in bone diseases as it can promote a healthy pool of functional mitochondria in osteoblasts.

In cognitive radio networks, secondary users (SUs) can use a frequency band when the primary user (PU) of the band is not transmitting. Spectrum sensing is one of the methods that SUs employ to know if the PU has stopped transmitting. Accurate spectrum sensing boosts the likelihood that an SU detects a spectrum opportunity. However, it will be challenging for affordable receivers to support accurate spectrum sensing due to receiver impairments, including IQ imbalance and aliasing. Several other papers have developed methods that can address the effects of IQ imbalance in spectrum sensing. This paper presents a technique that can address not only IQ imbalance but the effects of aliasing on multiband spectrum sensing as well. We use channelized spectrum-domain modeling of receivers to develop the technique. This paper presents the theoretical development of the receiver modeling technique and the proposed spectrum sensing mechanism. The performance of the proposed mechanism is evaluated using simulations and hardware-based measurements. The results demonstrate that the proposed mechanism significantly enhances the opportunity detection probability of affordable cognitive radios with high IQ imbalance and poor antialiasing filter selectivity performances.

This research was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (NRF-2015R1A1A1A05027848). K. Kim was supported by the Occasional Technology Development Project for Industrial Site Core Technology of the Ministry of Trade, Industry and Energy (No. 10054694).

This paper presents a pioneering study based on a series of experiments on the operation of commercial Time-Division Long-Term Evolution (TD-LTE) systems in the presence of pulsed interfering signals in the 3550-3650 MHz band. TD-LTE operations were carried out in channels overlapping and adjacent to the high power SPN-43 radar with various frequency offsets between the two systems to evaluate the susceptibility of LTE to a high power interfering signal. Our results demonstrate that LTE communication using low antenna heights was not adversely affected by the pulsed interfering signal operating on adjacent frequencies irrespective of the distance of interfering transmitter. Performance was degraded only for very close distances (1-2 km) of overlapping frequencies of interfering transmitter., Accepted for publication in IEEE Wireless Communications Letters

As a part of the global effort to address the overwhelming demand for wireless broadband capacity, the wireless communities in the United States have undertaken innovative initiatives such as tiered-access to shared spectrum. The Federal Communications Commission has proposed a dynamic spectrum management framework for a Citizen Broadband Radio Service (CBRS) governed by a spectrum access system (SAS). The implementation of a SAS capable of dynamic frequency assignment and interference management is critical for the success of the proposed framework. In this paper we present the efforts toward a spectrum sharing system in the U.S. context by summarizing different interest groups’ standpoint on the FCC proposed framework. We also present an example SAS architecture that accommodates the tiered access to shared spectrum and example approaches to achieve important SAS capabilities.

Medication administration is one pathway by which Adverse Drug Events (ADE) can occur. While Electronic Medical Administration Record (eMAR) systems help reduce the number of ADEs, current eMAR implementations suffer from workarounds that defeat safety and verification mechanisms meant to limit the number of potential ADEs that occur during medication administration. In this paper, we introduce Multi-Element ChipLess (MECL) RFID tags which enable real-time event notifications through event signatures. Event signatures correspond to the physical configuration of different RFID elements in a chipless RFID tag. Augmenting physical objects, such as a pill container, with MECL-RFID can allow caregivers to detect the moment a particular pill container is opened or closed. We present the fundamentals behind real-time event detection using MECL-RFID and propose a cyber-physical intervention system that can be used to reduce ADEs through realtime event monitoring and notifications sent to clinicians administering medication. We also present a prototype MECL-RFID to demonstrate potential future improvements to eMAR systems that minimize ADEs., Comment: Proceedings of the Wireless Health 2014 on National Institutes of Health

We report an ultraviolet (UV) photodetector with a universally transferable monolayer film with ordered hollow TiO

The policy of permanently assigning a frequency band to a single application has led to extremely low utilization of the available spectrum. Cognitive radio, with its ability to be both intelligent and frequency agile, is thought to be one of the prime contenders to provide the necessary capabilities needed for dynamic spectrum access systems. With this in mind, this paper discusses the practical issues inherent to the deployment of spectrum management systems utilizing cognitive radios.

This paper proposes the use of a cognitive engine to control the local oscillator and sampling frequencies in a flexible receiver RF front-end. The analysis in this paper shows that this cognitive engine has the potential to relax selectivity requirement of the pre-selector filter in receiver RF front-end. The cognitive engine is designed by modeling the RF front-end in channelized spectrum domain. The paper also develops a new spectrum occupancy model to evaluate the performance of the approach. Theoretical analysis and simulations are also carried out using the developed model. The results show that the designed cognitive engine can enable a poorly selective receiver to behave similar to highly selective receiver. Furthermore, this paper analyzes the computational complexity of the designed cognitive engine.

Antennas are a key enabling technology for software-defined radio (SDR). Although software is extremely flexible, SDR's potential is limited by antenna size and performance. In this paper, we review typical antenna miniaturization techniques and fundamental theories that limit antenna size and performance including operational bandwidth, gain (or range), and radiation pattern. Possible antenna design strategies are discussed to meet the desired specifications in SDR based on observations from the limit theories. The application of strategies to enable multiband (resonant), continuous multiband (frequency independent), and instantaneous, ultra-wideband antennas are discussed qualitatively. Advantages, disadvantages, and design trade-off strategies for different types of antennas are compared from a system-level perspective. A design example for a compact ultra-wideband (UWB) antenna is presented for a software-defined platform. The example involves a direct-conversion radio developed in Wireless@VT that uses a Motorola RFIC having a 100 MHz---6 GHz operational frequency range with a 9 kHz---20 MHz channel bandwidth. The example antenna covers frequencies from 450 MHz to 6 GHz instantaneously with approximately 5-dBi realized gain over a finite-size ground plane, including return loss and omni-directional coverage.

In this paper, we report on an ultraviolet (UV) photodetector based on a pn junction structure hollow anatase n-TiO2 nanosphere monolayer film on a p-GaN template. In order to form and transfer the well-arrayed hollow TiO2 nanosphere monolayer film onto polydimethylsiloxane (PDMS), a facile rubbing method and polyvinyl alcohol (PVA) aqueous solution was used. To investigate the effects of different-sized hollow TiO2 nanospheres, anatase-TiO2 spheres of various diameters were prepared by combining template synthesis and thermal treatment. The responsiveness of the fabricated UV photodetectors using anatase n-TiO2 monolayer/p-GaN was increased from 0.17 to 0.21 A W−1 upon reducing the size of the anatase-phased hollow n-TiO2 spheres from 660 to 360 nm. Our suggested transferable anatase-TiO2 monolayer film is a new n-type single-layer material for electronic and optical device fields developed through the universal usage of displaceable material for targeted hetero-templates.

With the introduction of digital cellular phones, hearing-aid users have experienced a severe buzzing noise caused by the interaction between digital cellular phones and hearing aids. The cellular-phone industry, the hearing-aid industry, and consumers have been seeking a solution for the interference issue. Efforts reported in the literature have focused on measurements, modeling, and evaluation of interference and RF emission, but not on methods to solve the problem. In this paper, we focus on the causes of the interference and an understanding of the problem. We also present a method to reduce near-field electromagnetic energy around a cellular phone, mitigating the interference between cellular phones and hearing aids. The theoretical investigation of both the radiation mechanisms and fundamental limits on antennas suggested that a low-g antenna, such as an ultra-wideband antenna, could reduce the near-field intensity. Simulations and measurements were performed at 900 and 1880 MHz, using both low- and high-Q test antennas mounted on a mock cellular phone. The results showed that the peak electric and magnetic near-field strengths of the low-g test antenna were lower than those of a high-Q test antenna by at least 5 dBV/m and 4 dBA/m, respectively. The improvement in the near-field performance for the low-g antenna was without any sacrifice in far-field performance. Furthermore, in the presence of a human head, the simulation results showed that the radiation efficiency of the low-Q test antenna was better than that of the high-Q test antenna.

Objective Acute subdural hematoma (ASDH) patients are treated conservatively or surgically according to the guidelines for surgical treatment. Many patients with thin ASDH and mild neurologic deficit are managed conservatively, but sometimes aggravation of thin ASDH to chronic subdural hematoma (CSDH) results in exacerbated clinical symtoms and consequently requires surgery. The aim of this study is to evaluate risk factors that indicate progression of initially non-operated ASDH to CSDH. Methods We divided 177 patients, presenting with ASDH (managed conservatively initially) between January 2008 to December 2013, into two groups; 'CSDH progression group' (n=16) and 'non-CSDH progression group' (n=161). Patient's data including age, sex, past medical history, medication were collected and brain computed tomography was used for radiologic analysis. Results Our data demonstrated that no significant intergroup difference with respect to age, sex ratio, co-morbid conditions, medication history, ischemic heart disease, liver disease and end-stage renal disease was found. However, Hounsfield unit (hematoma density) and mixed density was higher in the 'ASDH progression group' (67.50±7.63) than in the 'non-CSDH progression group' (61.53±10.69) (p=0.031). Midline shifting and hematoma depth in the 'CSDH progression group' were significantly greater than the 'non-CSDH progression group' (p=0.067, p=0.005). Conclusion Based on the results of this study, the risk factors that are related to progression of initially non-operated ASDH to CSDH are higher Hounsfield unit and hematoma depth. Therefore, we suggest that ASDH patients, who have bigger hematoma depth and higher Hounsfield unit, should be monitored and managed carefully during the follow-up period.

This paper reports on an investigation of spherical, disc, and half-disc antennas in the frequency and time domains with the objective of developing small planar versions of the antennas. These antennas have an omni-directional impulse response in azimuth and a pulse duration of 0.5 - 0.65 nanoseconds. In addition, the measured data show a reasonable peak received signal in a pulse communication link using two identical antennas.

Purpose: The purpose of this study was to identify the factors contributing to diabetic foot ulcers (DFU) among patients with type 2 diabetes mellitus (DM). Methods: Data were collected from 131 patients who had been diagnosed with DM for more than six months. Patients recruited from three hospitals in Gwangju city were given both a foot examination to confirm the presence of a foot ulcer and an individual time of survey using questionnaires about foot care knowledge and self management behavior. Results: Factors contributing to DFU were male (adjusted odds ratio [aOR]=4.86, 95% confidence interval [CI]=1.16~20.44), history of DM-related hospitalization (aOR= 4.56, 95% CI=1.17~17.84), duration of DM (aOR=13.75, 95% CI=2.31~82.66 for those with time since diagnosis of 11~15 years; aOR=6.37, 95% CI=1.09~37.36 for those with time since diagnosis of 16-20 years; aOR=12.97, 95% CI=2.26~74.32 for those with time since diagnosis of over 21 years), DM diet (aOR=0.13, 95% CI=0.03-0.64 for those who did not practice dietary control), and exercise (aOR=15.59, 95% CI=3.49~69.64 for those who did not engage in regular exercise). Conclusion: The factors identified in this study provided strategic information for developing educational program targeting patients with DM to prevent DFC.

We report an ultraviolet (UV) photodetector with a universally transferable monolayer film with ordered hollow TiO2 spheres on p-GaN. After forming a TiO2 monolayer film by unidirectional rubbing of hollow TiO2 spheres on a polydimethylsiloxane (PDMS) supporting plate, we used a 5% polyvinyl alcohol (PVA) aqueous solution to transfer the film onto the target substrate. The PVA/TiO2 monolayer film was detached from the PDMS film and transferred to the p-GaN/Al2O3 substrate. To investigate the effects of crystallized phases of the TiO2 hollow spheres, anatase and rutile TiO2 sphere monolayers prepared by combining template synthesis and thermal treatment. The responsiveness of the UV photodetectors using anatase and rutile hollow n-TiO2 monolayer/p-GaN was 0.203 A/W at 312 nm and 0.093 A/W at 327 nm, respectively.

This paper explores an alternative to the previous remote impedance measurement of antennas to improve the dynamic range of the needed data for the measurements. Previous work evaluated the refection coefficient of a source antenna as a function of the termination on the antenna under test (AUT). The loads used in the measurement are the classic open-short-load, with measured data used for the actual termination impedances. The impedance of the AUT is determined by a standard calibration approach. For current vector network analyzers, the dynamic range of the analog-to-digital converter limits the impedance estimate, particularly if the distance between the source and AUT is increased to reduce interaction affecting the impedance of the AUT. The new approach separates the transmit and receive functions to allow the use of a LNA to improve the receive signal strength and offer the opportunity to overcome some of the limitations of the reflection approach.

Improving health care, while managing and reducing costs, requires a more efficient health care system. Adopting smart health-monitoring sensors, in- or on-body, will play a key role in successfully addressing the challenges. Currently, smart health-monitoring sensors and medical devices exist in implantable, ingestible, and wearable forms. On the other hand, artificial organs, such as artificial hearts and limbs, are now becoming a reality to replace unhealthy organs. Together all these devices are about to transform the medical care that once was either unimaginable or was categorized as a science fiction.

A passive wireless sensor is disclosed. The sensor has at least a measurand sensitive member and an electromagnetically resonant member positioned proximate to each other. The resonant member comprises a preselected resonance frequency, such that it scatters at least a portion of an interrogating signal as a scattered signal proximate to its resonance frequency, and the measurand sensitive member alters the scattered signal as a function of the measurand to change the shape of the scattered signal. The reactive field of the sensor is kept within the sensor to minimize environment interference and to maximize its signal strength. Almost bond-free packaging mitigates problems with delamination or internal stresses due to differing coefficients of thermal expansion.

Far-field radiation-pattern estimation is explored for the case of partially-scanned spherical near-field data resulting from physical limitations of an antenna under test or associated measurement systems. A direct matrix approach, based on spherical-wave expansions, is found to be simple and effective for constructing the 3-D radiation pattern from partially-scanned near-field data. Criteria to determine the minimum near-field data for full 3-D pattern reconstruction is explained. The concept of the direct matrix approach is demonstrated for a mobile antenna and a horn antenna. An additional benefit of this approach is the reduction of the scan time for antenna measurements.

The limit curve of fundamental-limit theory provides a critical evaluation tool in terms of antenna size and performance for both systems and antenna engineers. Because the limit curve varies with source configurations and antenna geometry, one can not use the limit curve blindly. In this paper, we demonstrated the change of the minimum radiation-Q for difference source configurations and mode excitations, along with explanations of radiation physics. The results were also explained through various examples. The provided observations and concepts are useful for the design of an antenna close to the theoretical limit.

Many antenna ranges are limited in operation by the effects of multipath propagation due to reflection from adjacent structures. Such structures include buildings, range walls, floors, and ceilings. Diffraction fences and absorber provide the classic methods for reducing these effects. With modern processing capabilities, new methods can be incorporated to reduce multipath effects. In this paper, we review the results of Davis and Licul's approach [1] that push the limits of an antenna range due to multipath from unavoidable adjacent scatterers. Their approach only considered boresight interaction. The radiation pattern of a 4 GHz Yagi-Uda antenna was measured inside an anechoic chamber with a metal plate present to introduce a multipath environment. A time gating approach based on the singularity expansion method (SEM) was used to mitigate the multipath effects and to estimate the radiation pattern in free space environment based on the boresight SEM poles. The results showed that some complex poles of a test antenna might not be excited strongly at certain angles, as with the use of boresight poles in the previous work. To resolve the problem, combined poles were extracted from multiple angles to remove the multipath effects and obtain non-distorted radiation patterns.

[1] The fundamental-limit theory of antennas provides a theoretical limit to assist in the evaluation of antenna performance in terms of antenna size, fractional impedance bandwidth, and gain. The limit is very useful in practice, giving a basis for restricting the design search to a class of realizable antennas based on size and performance. Previous research on the limit theory focused on electrically small, resonant antennas. In this paper, we discuss how the classical fundamental-limit theory can be interpreted for ultrawideband antennas. The frequency response of Chu's equivalent circuit model for spherical modes suggests the concept of an ideal antenna. The transfer function of the ideal antenna, showing ultrawideband antenna characteristics, simply has an entire function and two complex poles. In this paper, an antenna design strategy is developed based on observations of ideal antenna characteristics. A process is presented for evaluating how well an ultrawideband antenna can approach the theoretical size limit based on the 3-dB cutoff frequencies of spherical modes.

In this paper, we introduce the folded-notch half-disk antenna to support dual band operation covering 2.4-2.5 and 3.1-10.6 GHz without increasing the antenna size greater than needed for the 3.1 to 10.6 GHz band. Results of a parametric study demonstrate that the frequency notch can be controlled. In addition, antenna characterization results are provided in both the frequency and time domains

A new top-loaded ultra-wideband antenna covering the 2.4-10.6 GHz impedance bandwidth (VSWR

We investigate the feasibility of ultra-wideband half-disk structures as wearable antennas for indoor and outdoor applications of ultra-wideband bodyworn devices (3.1-10.6 GHz). First, we characterize camouflage cloth in terms of relative permittivity and loss tangent. Then, based on the estimated substrate information, we design wearable half-disk antennas and compare the performance of solid copper and woven versions in the frequency and time domains.

Printed antennas are cheap, lightweight, easy to-fabricate with high precision, and adaptable to mass production. These features are desirable for both indoor and outdoor handheld UWB antenna applications. In this paper, we consider planar versions of the half-disk antenna with different feed structures. These versions are compared with respect to radiated pulse width (to get higher data throughput), pulse amplitude (for a better efficiency), phase linearity (to prevent distortion), and omnidirectional radiation characteristics. A 1"/spl times/1"/spl times/31 mil size microstrip-fed half-disk antenna is presented as a solution to these needs.

In this study, previous theories on the minimum radiation- Q against antenna size are examined, basic assumptions are reviewed and an alternate formulation is presented. The radiation- Q limit varies with the amount of an estimated non-radiating energy, which is directly related to the energy velocity. The classic approximate Q formula of Chu is found to be equivalent to using the group velocity for the energy velocity. Other previous approaches implicitly assumed that the radiated-energy travels in the radial direction at the speed of light from the antenna sphere to the far-field region, which is not true. Based on this observation of the incorrect energy velocity, a time-domain approach is used to derive the fundamental limit on radiation- Q against electrical size of an antenna. A new form of radiation- Q is presented that provides a bound lower than all the previous results. The new limit, which is just below the Chu limit, holds for any antenna size, not just electrically-small antennas. The new radiation- Q limit provides antenna designers with a simple guide to estimate the minimum required antenna size for a given bandwidth and efficiency, thereby avoiding the search for an impractical antenna.