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The 3-D ultrasound (US) imaging addresses the limitation in field-of-view (FOV) in conventional 2-D US imaging by providing 3-D viewing of the anatomy. The 3-D US imaging has been extensively adapted for diagnosis and image-guided surgical intervention. However, conventional approaches to implement 3-D US imaging require either expensive and sophisticated 2-D array transducers or external actuation mechanisms to move a 1-D array mechanically. Here, we propose a 3-D US imaging mechanism using an actuated acoustic reflector instead of the sensor elements for volume acquisition with significantly extended 3-D FOV, which can be implemented with simple hardware and compact size. To improve image quality on the elevation plane, we implemented the synthetic aperture focusing (SAF) method according to the diagonal geometry of the virtual element array in the proposed imaging mechanism for elevation beamforming. We first evaluated the proposed imaging mechanism and SAF with simulated point targets and cyst targets. The results of point targets suggested improved image quality on the elevation plane, and the results of cysts targets demonstrated a potential to improve 3-D visualization of human anatomy. We built a prototype imaging system with a 3-D FOV of 38 mm (lateral) by 38 mm (elevation) by 50 mm (axial) and collected data in imaging experiments with phantoms. Experimental data showed consistency with simulation results. The SAF method enhanced quantifying the cyst volume size in the breast mimicking phantom compared with no elevation beamforming. These results suggested that the proposed 3-D US imaging mechanism could potentially be applied in clinical scenarios.

Copper matrix-matched calibration samples were prepared by doping high purity copper powders (99.999%, 500–600 μm) with multi-element standard solutions with a total of 72 elements, and then the relative sensitivity factors (RSFs) of the 72 elements in both microsecond-pulsed and continuous direct current (dc) modes were determined by using Element GD type glow discharge mass spectrometry (GD-MS). The ability of pulsed and continuous dc-GD-MS to quantitatively determine trace elements in copper was demonstrated after calibration using the RSFs. The results showed that the uncertainty level of GD-MS analysis after calibration was comparable with that of ICP-MS and ICP-OES analysis. In order to standardize calibration sample preparation procedures, the doping concentration, pressed powder tablet compactness and tablet homogeneity were optimized. Good recovery (85% to 115%) was obtained. Good pressed powder tablet compactness and tablet homogeneity were obtained, which were expressed as relative standard deviations (

The efficacy of ethiodized poppyseed oil in hysterosalpingography (HSG) image quality and fertility enhancement has been revealed, but whether this HSG modality has similar effects in the Chinese population is still unclear.Between July 18, 2017, and December 29, 2019, this multicentric, randomized, two-arm, clinical trial was performed involving 15 medical centers. Infertile women meeting HSG indications were randomly assigned to an oil group and a water group. The coprimary outcome included HSG image quality during HSG and fertility-enhancing effects of HSG. This study was registered on ClinicalTrials.gov (NCT03370575).A total of 1026 subjects were randomly assigned to an oil group (Ethiodized poppyseed oil-based contrast is superior to water-based contrast during HSG in terms of image quality improvement and fertility enhancement. This study indicates the priority of the application of ethiodized poppyseed oil-based contrast during the HSG procedure in infertile patients.No funding was received.

The needle intervention is required in many clinical procedures such as lumbar puncture and lymph node biopsy. Ultrasound (US) imaging has been applied widely to guide procedures involving needle insertion. However, conventional 2D US image guidance provides a limited field of view (FOV) for the region of interest (ROI), especially toward the outof-plane axis. Also, a high level of hand-eye coordination is required to accurately place the needle to the target in tissue because the needle path and the image plane are not registered to each other. This paper p roposes a needle insertion mechanism that enables 3D US imaging to provide a larger FOV and thus assists clinicians in making better decisions about where to insert the needle. Besides 3D imaging functionality, the image plane and needle path are co-registered in the proposed mechanism to facilitate needle insertion. The proposed mechanism uses actuated acoustic reflectors to redirect acoustic waves to different parts of ROI. 2D image slices are collected along the elevation direction and are then focused on the elevation plane. Elevation focusing is achieved with a synthetic aperture focusing algorithm that considers the acoustic path geometry in the actuated reflector system. Both software simulation and imaging experiments using a prototype are carried out to validate the 3D imaging performance.The simulation and experiment results of point and wire phantoms validate the 3D imaging capa bility and suggest that image quality on the elevation plane after applying elevation focusing improved in terms of both resolution and signal to noise ratio. By providing clinicians with an extended FOV with improved image quality, the proposed mechanism has the potential to enable needle insertion with better efficiency and a higher success rate.

The advancement in bio-engineering technology has enabled tissues to be artificially cultivated from human cells, providing the opportunity to model disease and discover potential treatments 1 . Blood vessel is an important category of human tissues that can be artificially engineered to facilitate the development of treatment plans for vascular diseases. The growth of tissue engineered blood vessels (TEBVs) is a costly procedure, and effective quality control during the growing process could help reduce waste and optimize the cultivation process. Imaging technologies, such as optical coherence tomography5,6 (OCT), have been applied to obtain cross-sectional images of TEBVs, which could be used as a nondestructive method to assess blood vessel during cultivation. Ultrasound (US) imaging has been widely accepted in clinical practice due to its real-time imaging capacity and zero radiation emission; and compared to optics-based imaging modality it is more accessible financially. We implemented an US computer tomography (USCT) based monitoring system on assisting quality control in TEBV growth. In this prototype, a single element transducer is placed in a circular stand that rotates around the TEBV bioreactor to collect A-lines from different angles. Mechatronics systems are used to actuate the transducer for circular motion. A circular back-projection method is used in image reconstruction. Experiments were carried out with point phantom and the bioreactor to validate the imaging functionality of the prototype. Reconstructed images provide validation to the feasibility of using USCT to monitor the growth of TEBV growth.

The pore ratio is an important parameter affecting the stability and safety of tailings reservoirs; however, the relationship between the pore ratio and physical properties of tailings sand has not been researched in-depth. In this paper, using the tailings from a tungsten mine in southern Shaanxi as a case study, the correlation between the minimum void ratio and related parameters is analyzed, based on laboratory test data, and the optimal marginal distribution function of the parameters is determined. The Gumbel-Hougard copula function that best describes the correlation between parameters is identified, and it is used to establish the joint probability distribution model of the three parameters, and the guarantee rate α is introduced to estimate and analyze the minimum void ratio. The results show that the optimal edge distribution of the fine particle content and specific gravity follows a truncated normal distribution, and the optimal edge distribution of the minimum void ratio follows a logarithmic normal distribution. According to AIC criterion, the Gumbel-Hougard copula is the best three-dimensional copula function to fit the minimum void ratio and related parameters. When the guarantee rate α is 0.485, the joint probability distribution model achieves optimal performance in terms of estimating the minimum void ratio. The maximum error of the estimation is 1.99%, which is verified through data, and the estimation meets the requirements for practical engineering. The method proposed in this paper uses the existing measured data to establish a joint probability distribution model and combines the collected fine particle content and specific gravity data with the guarantee rate to estimate the minimum void ratio, providing a novel basis for the study of the physical properties of tailings.

The hippocampus is critical for learning and memory and may be separated into anatomically-defined hippocampal subfields (aHPSFs). Many studies have shown that aHPSFs, and their respective functional networks, are differentially vulnerable to a variety of disorders. Hippocampal functional networks, particularly during resting state, are generally analyzed using aHPSFs as seed regions, with the underlying assumption that the function within a subfield is homogeneous, yet heterogeneous between subfields. However, several prior studies that have utilized aHPSFs and assessed brain-wide cortical connectivity have observed similar resting-state functional connectivity profiles between aHPSFs. Alternatively, data-driven approaches offer a means to investigate hippocampal functional organization without a priori assumptions. However, insufficient spatial resolution may lead to partial volume effects at the boundaries of hippocampal subfields, resulting in a number of caveats concerning the reliability of the results. Hence, we developed a functional Magnetic Resonance Imaging (fMRI) sequence on a 7T MR scanner achieving 0.94 mm isotropic resolution with a TR of 2s and brain-wide coverage to 1) investigate whether hippocampal functional segmentation with ultrahigh-resolution data demonstrate similar anatomical, lamellar structures in the hippocampus, and 2) define and compare the brain-wide FC associated with fine-grained aHPSFs and functionally-defined hippocampal subfields (fHPSFs). Using a spatially restricted hippocampal Independent Component Analysis (ICA) approach, this study showed that fHPSFs were arranged along the longitudinal axis of the hippocampus that were not comparable to the lamellar structures of aHPSFs. Contrary to the anatomically defined hippocampal subfields which are bilaterally symmetrical, 13 out of 20 fHPSFs were unilateral. For brain-wide FC, the fHPSFs rather than aHPSFs revealed that a number of fHPSFs connected specifically with some of the functional networks. The visual and sensorimotor networks preferentially connected with different portions of CA1, CA3 and CA4/DG. The DMN was also found to connect more extensively with posterior subfields rather than anterior subfields. Finally, the frontoparietal network (FPN) was anticorrelated with the head portion of CA1. The investigation of functional networks associated with the fHPSFs may enhance the sensitivity of biomarkers for a range of neurological disorders, as network-based approaches take into account disease-related alterations in brain-wide interconnections rather than measuring the regional changes of hippocampus.

The conventional transrectal ultrasound (TRUS) probe for transperineal needle insertion is typically a sagittal viewing linear array or combined with another transverse curvilinear array. Physicians are required to manually move and rotate the probe back and forth to determine the needle trajectory or to render 3D volume. For the hands-free 3D imaging guidance of transperineal needle insertion, this paper proposes a reflector-based 3D TRUS imaging probe. The proposed probe is enabled by motorizing rotation of a forward-viewing array transducer and bending the ultrasound beam to cover whole prostate utilizing an acoustic mirror as reflector. The proposed device is capable of providing an arbitrary angled B-mode slice with respect to prostate based on the motorized probe rotation angle adjustment, and enables to render 3D images with volume-based reconstruction. In the experimental validation with the cyst phantom, the contrast-noise ratios in the 0 and 90-degree of rotation angle were 4.36 and 4.05 dB in the image acquisition with reflector, and 4.26 and 5.07 dB in that without reflector, respectively. Also, the 3D appearance of cyst can be rendered with maximum intensity projection. These results demonstrated the limited image quality deterioration by adding reflector, and indicate the reflector-based TRUS probe has a potential to improve the guidance of transperineal needle insertion.

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. Also, working with other systems and organs, it is responsible for several important functions such as storing iron, detoxifying harmful substances, maintaining the hormonal balance, and producing immune factors to fight infections. Cattle seemed to be the most sensitive animal species with respect to some metal toxicities resulting from ingestion of feed material. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. Therefore, the IAWG has included the need for such a key comparison to maintain, expand and improve core capabilities, and to support specific CMCs claim in bio-sample analysis as well.

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. The purpose of CCQM-K145 is to ensure the comparable and traceable measurement results for essential and toxic elements such as P, S, Zn, Mn, Ni, Mo, Sr, Cr, Co, Pb, As and Hg in bovine liver among NMIs and other designated measurement bodies worldwide. The comparison was agreed by IAWG as 6th IAWG Benchmarking Exercise with Zn and Ni as exemplary elements at the meeting in Korea in the early October 2016. The results of CCQM-K145 are expected to cover the measurement capability and support CMCs claiming for inorganic elements in the similar biological tissue materials and food samples. 30 NMIs and DIs registered in CCQM-K145. With respect to the methodology, a variety of techniques such as IDMS, ICP-OES, ICP-MS(non-ID), AAS and NAA were adopted by the participants. For Zn, Ni, Sr, Pb and Hg measurements, most participants chose ID-ICP-MS method, which showed the better performance in terms of consistency and reliability of the measurement results. In aspect of the traceability for the measurement results in CCQM-K145, most participants used their own (in house) CRMs or other NMI's CRMs to guarantee trace to SI unit. Most participants used similar matrix CRMs for quality control or method validation. Base on different statistic way to calculate the reference mass fraction values and associated uncertainties for each measurand, removal of the suspected extreme values, and discussion at the IAWG meetings, the median values are proposed as the KCRV for Zn, Ni, Mn, Mo, Cr, Pb and Hg; the arithmetic mean values are proposed as the KCRV for P, S, Sr, Co and As. In general, the performances of the majority of CCQM-K145 participants are very good, illustrating their measurement capabilities for Zn, Ni, P, S, Mn, Mo, Sr, Cr, As, Co, Pb and Hg in a complex biological tissue matrix. Bovine liver contains many kinds of nutrients and microelements, it can be regarded as a typical representative material of biological tissue and food. In CCQM-K145, the analytes involved alkali metals and transition elements, metalloids / semi-metals and non metals with a range of mass fraction from mg/g to μg/kg. CCQM-K145 also tested the ability of NMIs/DIs to determine elements that were easy to be lost and polluted, and interfered significantly. The chemical pretreatment methods of samples used in the comparison is suitable for general food and biological matrix samples. A variety of measurement methods used in the comparison represent the main instrumental technology for elemental analysis. Therefore, for supporting CMC claim, CCQM-K145 is readily applicable to measurement of more elements in a wide range of biological materials (including liquids and solids) and meat products. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

High-purity silicon power was doped with standard solutions containing 15 elements, and a high-purity indium tablet was prepared by the melting of indium pellets. An In-Si tablet, which is mechanically stable and thus suitable as a calibration sample, was prepared by our pressing the doped silicon power on the high-purity indium tablet. The matrix effect was studied by our investigating the variations of measured mass fractions (standard relative sensitivity factor, StdRSF, calibration) of doped impurities in the In-Si tablet, which provides a series of matrixes with different mass ratios of In to Si. For all the elements, the relative standard deviations of the measured mass fractions of impurities were less than 30%. The RSFs of the glow discharge mass spectrometer (Element GD) were obtained, and the results showed that three RSFs derived from the In-Si tablet with low, intermediate and high mass ratios of In to Si, respectively, agreed with the mean RSF within an uncertainty interval of 30%. The measurement of Fe and Al matrix certified reference materials further demonstrated that the RSFs generated from a matrix can be used for the calibration of another matrix, and the uncertainty was within 30%. Finally, another doped silicon powder was measured with the glow discharge mass spectrometer, which was calibrated by the mean RSFs from the In-Si tablet, and the analytical results obtained by glow discharge mass spectrometry are in good agreement with the analytical results obtained by high-resolution inductively coupled plasma mass spectrometry. Graphical abstract ᅟ.

Methods for ''cleaning up'' (or recognizing) states of a neural network are crucial for the functioning of many neural cognitive models. This process takes a noisy approximation of a state and recovers the original information. As a particular example, we consider the cleanup required for the use of Vector Symbolic Architectures, which provide a method for manipulating symbols using a fixed-length vector representation. To recognize the result of these manipulations, a mechanism for cleaning up the resulting noisy representation is needed, as this noise increases with the number of symbols being combined. While these symbolic manipulations have previously been modelled with biologically plausible neurons, this paper presents the first spiking neuron model of the cleanup process. We demonstrate that it approaches ideal performance and that the neural requirements scale linearly with the number of distinct symbols in the system. While this result is relevant for any biological model requiring cleanup, it is crucial for VSAs, as it completes the set of mechanisms needed to provide a full neural implementation of symbolic reasoning.

Modeling the Brain Neurons are pretty complicated cells. They display an endless variety of shapes that sprout highly variable numbers of axons and dendrites; they sport time- and voltage-dependent ion channels along with an impressive array of neurotransmitter receptors; and they connect intimately with near neighbors as well as former neighbors who have since moved away. Simulating a sizeable chunk of brain tissue has recently become achievable, thanks to advances in computer hardware and software. Eliasmith et al. (p. 1202 ; see the Perspective by Machens ) present their million-neuron model of the brain and show that it can recognize numerals, remember lists of digits, and write down those lists—tasks that seem effortless for a human but that encompass the triad of perception, cognition, and behavior.

The triaxial creep compression tests of compacted loess samples are conducted with a new set of modified triaxial compression apparatus. With the new apparatus, the loess sample can be scanned with CT machine at the same time during compression process. The different damage process of compacted loess sample is directly observed for the first time with CT images and CT numbers. The initiation mechanisms of loess micro-crack during different creep compression processes are analyzed with CT images.