A 36-nW Electrocardiogram Anomaly Detector Based on a 1.5-bit Non-Feedback Delta Quantizer for Always-on Cardiac Monitoring.

An always-on electrocardiogram (ECG) anomaly detector (EAD) with ultra-low power (ULP) consumption is proposed for continuous cardiac monitoring applications. The detector is featured with a 1.5-bit non-feedback delta quantizer (DQ) based feature extractor, followed by a multiplier-less convolutional neural network (CNN) engine, which eliminates the traditional high-resolution analog-to-digital converter (ADC) in conventional signal processing systems. The DQ uses a computing-in-capacitor (CIC) subtractor to quantize the sample-to-sample difference of ECG signal into 1.5-bit ternary codes, which is insensitive to low-frequency baseline wandering. The subsequent event-driven classifier is composed of a low-complexity coarse detector and a systolic-array-based CNN engine for ECG anomaly detection. The DQ and the digital CNN are fabricated in 65-nm and 180-nm CMOS technology, respectively, and the two chips are integrated on board through wire bonding. The measured detection accuracy is 90.6% ∼ 91.3% when tested on the MIT-BIH arrhythmia database, identifying three different ECG anomalies. Operating at 1 V and 1.4 V power supplies for the DQ and the digital CNN, respectively, the measured long-term average power consumption of the core circuits is 36 nW, which makes the detector among those state-of-the-art always-on cardiac anomaly detection devices with the lowest power consumption.

A 0.66mW 400 MHz/900 MHz Transmitter IC for In-Body Bio-Sensing Applications.

A sub-1GHz transmitter (TX) integrated chip (IC) with ultra-low power consumption and moderately high adjacent channel power rejection (ACPR) is presented for in-body bio-sensing applications. The 400 MHz 12-phase digital power amplifier (DPA) is implemented with the proposed 16QAM modulation scheme to improve the energy efficiency. The TX IC also contains a 900 MHz FSK TX realized with a symmetrical edge-combiner, which can be used in the low accuracy mode. A fully digital modulator with band shaping is integrated on the chip for the improvement of ACPR performance. Fabricated in 65-nm CMOS process, the chip occupies an active area of 0.75 mm2. Under 0.5 V supply voltage, the TX consumes less than 0.66 mW power consumption while delivering -15 dBm of output power when operating at both bands. The presented TX has an energy efficiency performance comparable to the state-of-the-arts low power designs, with the measured average energy consumption of 64.5/220 pJ/bit, and the measured figure-of-merit (FoM) of 2.04/6.98 nJ/(bit · mW) for the two bands. Compared with the state-of-the-arts sub-1mW designs in literatures, the ACPR is improved by at least 13 dB.

A Wireless Visualized Sensing System with Prosthesis Pose Reconstruction for Total Knee Arthroplasty.

The surgery quality of the total knee arthroplasty (TKA) depends on how accurate the knee prosthesis is implanted. The knee prosthesis is composed of the femoral component, the plastic spacer and the tibia component. The instant and kinetic relative pose of the knee prosthesis is one key aspect for the surgery quality evaluation. In this work, a wireless visualized sensing system with the instant and kinetic prosthesis pose reconstruction has been proposed and implemented. The system consists of a multimodal sensing device, a wireless data receiver and a data processing workstation. The sensing device has the identical shape and size as the spacer. During the surgery, the sensing device temporarily replaces the spacer and captures the images and the contact force distribution inside the knee joint prosthesis. It is connected to the external data receiver wirelessly through a 432 MHz data link, and the data is then sent to the workstation for processing. The signal processing method to analyze the instant and kinetic prosthesis pose from the image data has been investigated. Experiments on the prototype system show that the absolute reconstruction errors of the flexion-extension rotation angle (the pitch rotation of the femoral component around the horizontal long axis of the spacer), the internal-external rotation (the yaw rotation of the femoral component around the spacer vertical axis) and the mediolateral translation displacement between the centers of the femoral component and the spacer based on the image data are less than 1.73°, 1.08° and 1.55 mm, respectively. It provides a force balance measurement with error less than ±5 N. The experiments also show that kinetic pose reconstruction can be used to detect the surgery defection that cannot be detected by the force measurement or instant pose reconstruction.

Implantable Wireless Intracranial Pressure Monitoring Based on Air Pressure Sensing.

A wireless intracranial pressure (ICP) monitoring system based on the air pressure sensing is proposed in this work. The proposed system is composed of an implantable ICP sensing device and a portable wireless data recorder. The ICP sensing device consists of an air pressure sensor, an ultra-thin air pouch for pressure sensing, and a low-power dedicated system-on-a-chip (SoC) for the data acquisition control and wireless transmission. The SoC consists of a power management unit, a wake-up controller, the sensor interface, a wireless transmitter, and the workflow control logic. The SoC is fabricated in 0.18 µm CMOS technology with a die area of 3.04 mm × 2 mm. Experimental results show that the prototype implantable ICP device has achieved a resolution of 0.2 mmHg and a battery lifetime of 1 week with a 3 V 50 mAh battery. The ICP device has been tested in the liquid environment. The nonlinearity error is less than ±0.4 mmHg for the full measurement range of -20 to +150 mmHg. Compared to the other implantable wireless ICP solutions in the literature, the proposed system alleviates the biocompatibility issue and increases the measurement accuracy.

Coronary artery disease reporting and data system (CAD-RADSTM): Inter-observer agreement for assessment categories and modifiers.

BACKGROUND: The Coronary Artery Disease Reporting and Data System (CAD-RADS) provides a lexicon and standardized reporting system for coronary CT angiography. OBJECTIVES: To evaluate inter-observer agreement of the CAD-RADS among an panel of early career and expert readers. METHODS: Four early career and four expert cardiac imaging readers prospectively and independently evaluated 50 coronary CT angiography cases using the CAD-RADS lexicon. All readers assessed image quality using a five-point Likert scale, with mean Likert score ≥4 designating high image quality, and <4 designating moderate/low image quality. All readers were blinded to medical history and invasive coronary angiography findings. Inter-observer agreement for CAD-RADS assessment categories and modifiers were assessed using intra-class correlation (ICC) and Fleiss' Kappa (κ).The impact of reader experience and image quality on inter-observer agreement was also examined. RESULTS: Inter-observer agreement for CAD-RADS assessment categories was excellent (ICC 0.958, 95% CI 0.938-0.974, p < 0.0001). Agreement among expert readers (ICC 0.925, 95% CI 0.884-0.954) was marginally stronger than for early career readers (ICC 0.904, 95% CI 0.852-0.941), both p < 0.0001. High image quality was associated with stronger agreement than moderate image quality (ICC 0.944, 95% CI 0.886-0.974 vs. ICC 0.887, 95% CI 0.775-0.95, both p < 0.0001). While excellent inter-observer agreement was observed for modifiers S (stent) and G (bypass graft) (both κ = 1.0), only fair agreement (κ = 0.40) was observed for modifier V (high risk plaque). CONCLUSION: Inter-observer reproducibility of CAD-RADS assessment categories and modifiers is excellent, except for high-risk plaque (modifier V) which demonstrates fair agreement. These results suggest CAD-RADS is feasible for clinical implementation.

Resonance Frequency Readout Circuit for a 900 MHz SAW Device.

A monolithic resonance frequency readout circuit with high resolution and short measurement time is presented for a 900 MHz RF surface acoustic wave (SAW) sensor. The readout circuit is composed of a fractional-N phase-locked loop (PLL) as the stimulus source to the SAW device and a phase-based resonance frequency detecting circuit using successive approximation (SAR). A new resonance frequency searching strategy has been proposed based on the fact that the SAW device phase-frequency response crosses zero monotonically around the resonance frequency. A dedicated instant phase difference detecting circuit is adopted to facilitate the fast SAR operation for resonance frequency searching. The readout circuit has been implemented in 180 nm CMOS technology with a core area of 3.24 mm². In the experiment, it works with a 900 MHz SAW resonator with a quality factor of Q = 130. Experimental results show that the readout circuit consumes 7 mW power from 1.6 V supply. The frequency resolution is 733 Hz, and the relative accuracy is 0.82 ppm, and it takes 0.48 ms to complete one measurement. Compared to the previous results in the literature, this work has achieved the shortest measurement time with a trade-off between measurement accuracy and measurement time.

Polymer-Peptide Conjugates Disassemble Amyloid ß Fibrils in a Molecular-Weight Dependent Manner.

Amyloid aggregation and deposition are associated with many intractable human diseases. Although the inhibition of amyloid protein aggregation has been well-studied, the disaggregation and dissolution of existing amyloid fibrils is less known. Taking a fibrillar assembly of amyloid ß (Aß) peptide as the model system, here we report multivalent polymer-peptide conjugates (mPPCs) that disassemble preformed Aß fibrils into dispersible sub-100 nm structures. Atomic force microscopy and dynamic light scattering studies show that the disassembly rate of preformed Aß fibrils is controlled by the molecular weight of mPPCs. Rate equations on fibril disappearance are deduced from a simple model, which indicate that the disassembly reaction is first-order in the concentration of Aß fibrils and a pseudo-first-order reaction in the concentration of peptide moieties on mPPCs, respectively. We eliminate the possibility that the disassembly occurs by the association between mPPCs and Aß monomer/oligomers based on circular dichroism and Thioflavin T fluorescence assays. It is mostly likely that the mPPCs disassemble Aß fibrils through a direct interaction. The mPPCs may thus offer a general macromolecular design concept that breaks down existing amyloid fibrils in a predictable fashion.

A new species of the genus Triplophysa (Cypriniformes: Nemacheilidae), Triplophysa daochengensis, from Sichuan Province, China.

Triplophysa daochengensis sp. nov. is described from the Daocheng River, a northern tributary of the Jinsha River in Sichuan Province, China. The new species can be distinguished from its congeners by the following characters: body smooth and scales absent; lateral line complete; caudal peduncle compressed, depth unchanging; head length equal to caudal-peduncle length; lower jaw shovel-shaped; dorsal-fin origin anterior to pelvic-fin origin and closer to the tip of the snout than to the caudal-fin base, last unbranched ray hard; pelvic-fin tip not reaching anus; posterior chamber of gas bladder absent; intestine of spiral type with three winding coils.

A new species of Triplophysa Rendahl (Cypriniformes, Nemacheilidae) from Sichuan Province, China.

Triplophysa yajiangensis sp. nov. is described from the upper and middle reaches of the Yalong River, Yangtze Basin, Ganzi Prefecture, Sichuan Province, China. This new species can be distinguished from other congeneric species by the following characters: body surface smooth and scaleless; lateral line complete; caudal peduncle compressed and tapered slightly; lower jaw shovel-shaped; head shorter than caudal peduncle; dorsal-fin origin anterior to pelvic-fin origin and closer to tip of snout than to caudal-fin base, last unbranched ray hard; pelvic-fin reaches or exceeds anus; posterior chamber of gas bladder absent; intestine spiral type with 3-5 winding coils.

Alarm signals of the Sichuan sika deer Cervus nippon sichuanicus.

Sichuan sika deer (Cervus nippon sichuanicus) is an endangered and endemic subspecies of sika deer to Sichuan Province, China. According to our observations in the wild, the Sichuan sika deer makes alarm signals in the presence of actual or potential predators. In order to test the variation of the rhythmic alarm calls in some sex/age classes and different risk contexts, we recorded alarm calls of Sichuan sika deer from 2 October to 30 November 2008 and from 4 April to 5 September 2009 in the Tiebu Nature Reserve, Zoige County, Sichuan Province, China, and made acoustic analysis of these alarm calls. The results showed that the fundamental frequencies of alarm signals of Sichuan sika deer tended to decrease with age, and were significantly higher for females than for males. Duration tended to increase with age, and was significantly longer for males than for females. The fundamental frequencies and duration of alarm calls in adults were significantly higher and shorter respectively in high-risk than in moderate-risk contexts.

[Behavior ethogram and PAE coding system of Cervus nippon sichuanicus].

A monthly 5-day periodic observation at 06:00-18:00 from March to November 2007 was conducted to record the behavioral processes, contents, and results, and the surrounding habitats of Sichuan sika deer (Cervus nippon sichuanicus) in Donglie, Chonger, and Reer villages of Tiebu Natural Reserve of Sichuan Province. The behavioral ethogram, vigilance behaviors ethogram and its PAE (posture, act, and environment) coding system of the Sichuan sika deer were established, which filled the gap of the PAE coding of ungulates vigilance behaviors. A total of 11 kinds of postures, 83 acts, and 136 behaviors were recorded and distinguished, with the relative frequency of each behavior in relation to gender, age, and season described. Compared with other ungulates, the behavioral repertoire of Sichuan sika deer was mostly similar to that of other cervid animals.