Time-Scale Domain Characterization of Time-Varying Ultrawideband Infostation Channel

The time-scale domain geometrical-based method for the characterization of the time varying ultrawideband (UWB) channel typical of an infostation channel is presented. Compared to methods that use Doppler shift as a measure of time-variation in the channel this model provides a more reliable measure of frequency dispersion caused by terminal mobility in the UWB infostation channel. Particularly, it offers carrier frequency independent method of computing wideband channel responses and parameters which are important for ultrawideband systems. Results show that the frequency dispersion of the channel depends on the frequency and not on the choice of bandwidth. And time dispersion depends on bandwidth and not on the frequency. It is also shown that for time-varying UWB, frame length defined over the coherence time obtained with reference to the carrier frequency results in an error margin which can be reduced by using the coherence time defined with respect to the maximum frequency in a given frequency band. And the estimation of the frequency offset using the time-scale domain (wideband) model presented here (especially in the case of multiband UWB frequency synchronization) is more accurate than using frequency offset estimate obtained from narrowband models

Evacuation of the Pleural Cavity With an Infant Feeding Catheter Following en Bloc Resection of Hepatocellular Carcinoma and Involved Diaphragm–an Institutional Experience

En bloc resection of hepatocellular carcinoma and the involved diaphragm will, towards the end of operation, require evacuation of the pleural cavity, usually with a chest drain. We describe our method and experience of evacuating the pleural cavity, at the time of diaphragmatic repair, with an infant feeding catheter without the need of a chest drain. We have found the method safe and efficacious

Cholangiographic Features in the Diagnosis and Management of Obstructive Icteric Type Hepatocellular Carcinoma

In 11 years and 3 months, 2037 patients with HCC were seen and 48 patients (2.4%) were diagnosed to have obstructive icteric type HCC. Five patients were terminally ill and were not investigated further. Forty three patients were initially investigated by endoscopic retrograde cholangiography (ERC) or percutaneous transhepatic cholangiogram (PTC) and classified as having obstructive icteric type 1, 2, or 3 HCC based on the cholangiographic findings. The obstruction in type 1 HCC was due to intraluminal tumour casts and/or tumour fragments obstructing the hepatic ductal confluence or common bile duct, while intraluminal blood clots, from haemobilia, filling the biliary tree was the cause in type 2 HCC. The pathology in type 3 HCC was extraluminal obstruction by extensive tumour encasement of the intra–hepatic biliary ductal system and/or extrinsic compression of the hepatic and common bile ducts by tumour(s) and/or malignant lymph nodes. At the initial ERC/PTC, 10 patients (5 resected, 50%) had obstructive icteric type 1 and 23 patients (0 resected) had obstructive icteric type 3 HCC. Of the 10 patients initially classified according to cholangiography to have obstructive icteric type 2 HCC, subsequent investigations revealed that 6 patients had type 1 HCC (4 resectable, 67%) and 4 patients had type 3 HCC (0 resectable). The classification of the obstructive icteric type HCC into types 1, 2, and 3, based on the initial cholangiographic appearances has simplified and rationalized our management strategy for this condition

Alterations in Leg Extensor Muscle-Tendon Unit Biomechanical Properties With Ageing and Mechanical Loading.

Tendons transfer forces produced by muscle to the skeletal system and can therefore have a large influence on movement effectiveness and safety. Tendons are mechanosensitive, meaning that they adapt their material, morphological and hence their mechanical properties in response to mechanical loading. Therefore, unloading due to immobilization or inactivity could lead to changes in tendon mechanical properties. Additionally, ageing may influence tendon biomechanical properties directly, as a result of biological changes in the tendon, and indirectly, due to reduced muscle strength and physical activity. This review aimed to examine age-related differences in human leg extensor (triceps surae and quadriceps femoris) muscle-tendon unit biomechanical properties. Additionally, this review aimed to assess if, and to what extent mechanical loading interventions could counteract these changes in older adults. There appear to be consistent reductions in human triceps surae and quadriceps femoris muscle strength, accompanied by similar reductions in tendon stiffness and elastic modulus with ageing, whereas the effect on tendon cross sectional area is unclear. Therefore, the observed age-related changes in tendon stiffness are predominantly due to changes in tendon material rather than size with age. However, human tendons appear to retain their mechanosensitivity with age, as intervention studies report alterations in tendon biomechanical properties in older adults of similar magnitudes to younger adults over 12-14 weeks of training. Interventions should implement tendon strains corresponding to high mechanical loads (i.e., 80-90% MVC) with repetitive loading for up to 3-4 months to successfully counteract age-related changes in leg extensor muscle-tendon unit biomechanical properties. CM was funded by the Kootstra Talent Fellowship awarded by the Centre for Research Innovation, Support and Policy (CRISP) and by the NUTRIM Graduate Programme, both of Maastricht University Medical Center+. MK was supported by the German Social Accident Insurance (Deutsche Gesetzliche Unfallversicherung, Postgraduate Scholarship)

Charging management protocol for near field communication charging

The current multiplicity of mobile communication devices has provided an impetus for the research into new mechanisms to supplement battery charge. Wireless charging is a solution that serves to eliminate the cable requirements of typical battery charging implementations. Numerous wireless charging implementations are based on inductive coupling, similar to existing non-radiative short range communication systems. This study proposes incorporating a charge management protocol into the existing Near Field Communication Interface and Protocol-1 (NFCIP-1) specification to achieve NFC-enabled wireless charging. To this end, the original NFCIP-1 protocol has been modified through a time-sharing arrangement to support a charging task within the protocol cycle. Simulations of the modified protocol cycle were implemented using an appropriate battery model and charging algorithm. Numerical results show that the modified protocol is able to charge the target battery with minimum communication overhead. Satisfactory performance is also observed for charging up to 2 target devices in a single session

Application of NOMA for cellular-connected UAVs: opportunities and challenges

Unmanned aerial vehicles (UAVs) have gained considerable interests in numerous civil applications. To push forward its potentials, cellular-connected UAVs have been introduced. Nevertheless, cellular networks face several bottlenecks such as spectrum scarcity and limited concurrent connectivity. To address these issues, non-orthogonal multiple access (NOMA) can be adopted. NOMA provides several opportunities for cellular-connected UAVs such as larger rate region, balanced performance between system throughput and fairness, and reduced delay. In this paper, we review important findings of the related studies, and outline new opportunities and challenges in NOMA for cellular-connected UAVs. Monte-Carlo simulations are then performed to analyze the new aerial user’s (AU)’s signal characteristics and evaluate the NOMA performance for co-existence of AU and terrestrial user (TU). Our preliminary results show that NOMA is a promising strategy for cellular-connected UAVs

Acoustic wave sparsely activated localization microscopy (AWSALM): super-resolution ultrasound imaging using acoustic activation and deactivation of nanodroplets

Photo-activated localization microscopy (PALM) has revolutionized the field of fluorescence microscopy by breaking the diffraction limit in spatial resolution. In this study, “acoustic wave sparsely activated localization microscopy (AWSALM),” an acoustic counterpart of PALM, is developed to super-resolve structures which cannot be resolved by conventional B-mode imaging. AWSALM utilizes acoustic waves to sparsely and stochastically activate decafluorobutane nanodroplets by acoustic vaporization and to simultaneously deactivate the existing vaporized nanodroplets via acoustic destruction. In this method, activation, imaging, and deactivation are all performed using acoustic waves. Experimental results show that sub-wavelength micro-structures not resolvable by standard B-mode ultrasound images can be separated by AWSALM. This technique is flow independent and does not require a low concentration of contrast agents, as is required by current ultrasound super resolution techniques. Acoustic activation and deactivation can be controlled by adjusting the acoustic pressure, which remains well within the FDA approved safety range. In conclusion, this study shows the promise of a flow and contrast agent concentration independent super-resolution ultrasound technique which has potential to be faster and go beyond vascular imaging

Compact circularly polarized truncated square ring slot antenna with suppressed higher resonances

This paper presents a compact circularly polarized (CP) antenna with an integrated higher order harmonic rejection filter. The proposed design operates within the ISM band of 2.32 GHz± 2.63 GHz and is suitable for example for wireless power transfer applications. Asymmetrical truncated edges on a square ring create a defected ground structure to excite the CP property, simultaneously realizing compactness. It offers a 50.5% reduced patch area compared to a conventional design. Novel stubs and slot shapes are integrated in the transmission line to reduce higher (up to the third) order harmonics. The proposed prototype yields a -10 dB reflection coefficient (S11) impedance bandwidth of 12.53%, a 3 dB axial ratio bandwidth of 3.27%, and a gain of 5.64 dBi. Measurements also show good agreement with simulations. © 2017 Sabran et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited