Unexpected Giant Microwave Conductivity in a Nominally Silent BiFeO3 Domain Wall

Nanoelectronic devices based on ferroelectric domain walls (DWs), such as memories, transistors, and rectifiers, have been demonstrated in recent years. Practical high-speed electronics, on the other hand, usually demand operation frequencies in the gigahertz (GHz) regime, where the effect of dipolar oscillation is important. Herein, an unexpected giant GHz conductivity on the order of 10³ S m⁻¹ is observed in certain BiFeO₃ DWs, which is about 100 000 times greater than the carrier-induced direct current (dc) conductivity of the same walls. Surprisingly, the nominal configuration of the DWs precludes the alternating current (ac) conduction under an excitation electric field perpendicular to the surface. Theoretical analysis shows that the inclined DWs are stressed asymmetrically near the film surface, whereas the vertical walls in a control sample are not. The resultant imbalanced polarization profile can then couple to the out-of-plane microwave fields and induce power dissipation, which is confirmed by the phase-field modeling. Since the contributions from mobile-carrier conduction and bound-charge oscillation to the ac conductivity are equivalent in a microwave circuit, the research on local structural dynamics may open a new avenue to implement DW nano-devices for radio-frequency applications.     

Spin-Orbit Torque Magnetization Switching in MoTe2/Permalloy Heterostructures

The ability to switch magnetic elements by spin-orbit-induced torques has recently attracted much attention for a path toward high-performance, nonvolatile memories with low power consumption. Realizing efficient spin-orbit-based switching requires the harnessing of both new materials and novel physics to obtain high charge-to-spin conversion efficiencies, thus making the choice of spin source crucial. Here, the observation of spin-orbit torque switching in bilayers consisting of a semimetallic film of 1T′-MoTe₂ adjacent to permalloy is reported. Deterministic switching is achieved without external magnetic fields at room temperature, and the switching occurs with currents one order of magnitude smaller than those typical in devices using the best-performing heavy metals. The thickness-dependence can be understood if the interfacial spin-orbit contribution is considered in addition to the bulk spin Hall effect. Further threefold reduction in the switching current is demonstrated with resort to dumbbell-shaped magnetic elements. These findings foretell exciting prospects of using MoTe₂ for low-power semimetal-material-based spin devices.     

Abundance of heat shock proteins (hsp89, hsp60, and hsp27) in malignant cells of Hodgkin's disease

Heat shock proteins (HSPs) or stress proteins are synthesized by cells in response to environmental stress. Expression of HSPs by cells may have important physiological or pathological implications. In this study, we carried out an immunohistochemical and biochemical examination of low (hsp27), intermediate (hsp60), and high (hsp89) molecular weight HSP expression in reactive lymph nodes and in lymph nodes of patients with various types of lymphomas. In normal or reactive lymphoid tissues, hsp89 is abundant in large "transformed" lymphoid cells and immunoblasts. Hsp60 is widely distributed in lymphoid tissues, whereas hsp27 is absent in all lymphoid cells and histiocytes. Among lymphomas, the Hodgkin's Reed-Sternberg (H-RS) cells in Hodgkin's disease (HD) had the greatest abundance of hsp89 and hsp60 and, in 20% of cases, hsp27, in contrast to a much weaker staining of anti-hsp89 and -hsp60 in the background reactive lymphoid cells. The large lymphoid cells in small lymphocytic lymphoma are also rich in hsp89, but not hsp60 and hsp27. In contrast, the malignant cells in anaplastic large cell lymphoma and most high-grade tumors, including immunoblastic lymphomas, expressed minimal amounts of hsp89 and hsp60 and virtually no hsp27. Thus, the cellular level of HSPs was neither correlated with the proliferative capacity nor with the aggressiveness of the lymphomas. Hsp89, hsp60, and hsp27, as well, serve critical roles in the chaperoning of cellular proteins (e.g., a Mr 43,000 protein) in H-RS cells. The known interactions of HSPs with Rb, p53, peptide-MHC class II complexes, and cofactors of the glucocorticoid hormone receptor have further broadened the importance of HSPs in cell metabolism and in response to extracellular signals for proliferation, differentiation, or growth suppression (or apoptosis) of H-RS cells. Abundant HSP expression is seen only in HD, but not in other lymphomas. Such expression could have vital roles in the pathogenesis of HD.     

Vascular pathology of malignant cervical lymphadenopathy: qualitative and quantitative assessment with power Doppler ultrasound

BACKGROUND: Malignant vascular pathology has traditionally been studied with invasive angiography or in vitro immunohistochemistry. The objective of this study was to investigate the vascular patterns and vascular density of benign and malignant cervical lymphadenopathy using power Doppler ultrasound combined with a computed quantitative image processing system. METHODS: Investigations of 189 cervical lymph node lesions were undertaken prospectively using a 5-10 MHz linear array transducer in power mode. The types of vascular patterns displayed with power Doppler ultrasound, after sweep-scanning over the whole lymph node, were classified as hilar, spotted, peripheral, or mixed. Quantitative assessment of vascularity was made by sampling three parallel planes of each lymph node. A computed image processing system automatically calculated the density of vascular signals (called the "vascularity index" in this study) within the lymph node plane. RESULTS: Malignant lymph node lesions were shown to have higher vascularity indices (0.169+/-0.147, P < 0.01). The vascular patterns of benign lesions were mostly of avascular or hilar type (in 83% of cases). Malignant lesions were characterized by patterns of mixed (47%), spotted (20%), or peripheral type (11%). When vascular pattern (nonhilar type) and vascularity index (maximum > or = 0.09) were combined, the specificity for diagnosing malignant lymphadenopathy was as high as 97%. Variance in tumor vascularity was noted in both the benign and malignant groups. CONCLUSIONS: Power Doppler ultrasound combined with a computed image processing system provided an objective tool for assessing tumor vascularity quantitatively. Using this modality, the vascular pathology of malignant lymphadenopathy was found to be characterized by higher vascular density and aberrant vascular patterns.     

The Combined Use of Groundwater Quality,Drawdown Index and Land Use to Establish a Multi-Purpose Groundwater Utilization Plan

Groundwater is abundant and widely used for household consumption, irrigation, and aquaculture in the Lanyang Plain in northeastern Taiwan. However, it is subject to contamination by various anthropogenic activities and natural processes, as well as overexploitation, which has led to land subsidence in the eastern coastal area of this plain. It is becoming increasingly urgent to establish a sound plan for groundwater resource management in the Lanyang Plain to ensure the safe and sustainable use of groundwater to meet demands. The aim of this study is to develop a sound management plan for multipurpose groundwater utilization in the Lanyang Plain. This plan is developed with consideration of the quality and quantity of groundwater, as well as current land use practices. First, the groundwater quality parameters are spatially mapped followed by geographic determination of regions where groundwater quality is safe for different purposes, based on the water quality criteria for drinking, irrigation, and aquaculture. Subsequently, the drawdown index, defined as the ratio of the actual groundwater utilization rate to the transmissivity, is determined for each cell and low drawdown index regions are identified geographically. Information about regions where groundwater quality is safe for different purposes and the regions where the drawdown index is low is integrated to create a map which can be used for the production of a sound management plan for multi-purpose groundwater utilization in the Lanyang Plain. Comparisons between our newly created map and current land use for farmlands and fishponds can provide a basis to review the current land use practices in these regions.

     

Blind Channel Identification for Cyclic-Prefixed MIMO-OFDM Systems with Virtual Carriers

This paper applies the repetition index scheme(RIS)to the channel identification of cyclic prefixed(CP)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)systems with virtual carriers(VCs)in the environment of the number of receive antennas being no less than that of transmit antennas.The VCs will cause a rank deficiency problem in computing the subspace information.With the subcarrier mapping matrix,the received signal is simplified to remove the rank deficiency.We use the RIS scheme to generate many times of equivalent symbols so the channel identification can converge with few received OFDM blocks.The RIS scheme will convert the white noise into non-white noise.With the Cholesky factorization,a noise whitening technique is developed to turn the non-white noise back to white noise.We further analyze the necessary conditions of identifiability of channel estimation.Simulations are performed to show the superiority of the proposed method.     

Computer-assisted yoga training system

Multimedia Tools and Applications - Self-training is essential in sports exercise. However, without the instruction of a coach, a practitioner may progress to a limited extent. Improper postures...     

A framework for self‐regulated digital learning (SRDL)

This article develops a framework for self‐regulated digital learning, which supports for self‐regulated learning (SRL) in e‐learning systems. The framework emphasizes 8 features: learning plan, records/e‐portfolio and sharing, evaluation, human feedback, machine feedback, visualization of goals/procedures/concepts, scaffolding, and agents. Each feature facilitates or supports one or more SRL skills, including planning, monitoring and evaluating learning, applying appropriate cognitive strategies, and setting standards of products or performance. The implementation in domain‐general and ‐specific systems as illustrated by web‐based inquiry and problem‐solving are discussed. Examples and learning effects are elicited from the literature to demonstrate various designs. Approaches for designing SRL systems, educational implications, and new directions for future research incorporating SRL into digital learning are presented.     

Exploring Factors Affecting the Adoption of Internet of Things Services

The Internet of things (IoT) is seen as a potentially effective means of integrating multiple technologies to improve the quality of life. However, little attention has been paid to factors that may have a significant effect on a user’s intention to use the IoT services. This study applies the value-based adoption model to examine the influences of benefits (i.e. perceived usefulness and perceived enjoyment) and sacrifices (i.e. perceived privacy risk and perceived costs) on the user’s perceived value of and intention to use the IoT services. A structural equation modeling approach is applied to a survey of 489 IoT users, with results indicating that perceived usefulness and perceived enjoyment significantly affect behavioral intention through perceived value. Moreover, perceived privacy risk also plays a key factor in determining IoT adoption. The implications of this study are discussed.     

Numerical simulation and experimental validation of novel hyperelastic micro-motion manipulator for water conserving device

Microsystem Technologies - The aim of this study was to evaluate a novel water-conserving micro-motion manipulator (manipulator) for application in the fluid flow rate regulator of a faucet through...