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In this paper, we investigate whether board independence has an impact on the likelihood that a company reports weaknesses in internal controls. Using a sample of 11,226 firm-year observations spanning the period 2004-2012, we establish several findings. First, we document a negative relation between board independence and the disclosure of internal control weaknesses. We also document that the negative relation is stronger for firms with unitary leadership (combined positions of CEO and chairman) than for firms with dual leadership. Next, we show that board independence is associated with both fewer account-specific and companylevel weaknesses. Finally, we show that board independence is associated with timely remediation of internal control weaknesses and that the implementation of Auditing Standard No. 5 in 2007 weakens the effect of board independence on the disclosure of ICW. [ABSTRACT FROM AUTHOR]

By considering the elastic membrane's dissipation, the membrane-type acoustic metamaterial (MAM) has been demonstrated to be a super absorber for low-frequency sound. In the paper, a theoretical vibroacoustic plate model is developed to reveal the sound energy absorption mechanism within the MAM under a plane normal incidence. Based on the plate model in conjunction with the point matching method, the in-plane strain energy of the membrane due to the resonant and antiresonant motion of the attached masses can be accurately captured by solving the coupled vibroacoustic integrodifferential equation. The sound absorption ability of the MAM is quantitatively determined, which is also in good agreement with the prediction from the finite element method. In particular, microstructure effects including eccentricity of the attached masses, the depth, thickness, and loss factor of the membrane on sound absorption peak values are discussed. [ABSTRACT FROM AUTHOR]

An investigation has been conducted into the electron transport properties in carbon nanotube (CNT)-graphene contacts with a fully nonequilibrium Green's functions method combined with the density functional theory. Four different models are considered, where the contact geometries are varied. Their similar electron transmission characteristics are demonstrated with little dependence on the contact conditions at high energy and considerable dependence at low energy. The vacuum gap hinders the electron transport, resulting in an additional contact barrier. The electron transmission is mainly performed between the boundary carbon atoms of the CNT and the nearest graphene atoms, and the imperfection of the edge carbon atoms in a hexagonal lattice destroys the ballistic transport in graphene and the CNT at the contact. The current-voltage characteristics are presented as well. This reported work gives an insight into the electronic transport properties of the contacts and suggests that graphene is a suitable electrode material for applications in full-CNT devices. [ABSTRACT FROM AUTHOR]

Membrane-type acoustic metamaterials (MAMs) have demonstrated unusual capacity in controlling low-frequency sound transmission/reflection. In this paper, an analytical vibroacoustic membrane model is developed to study sound transmission behavior of the MAM under a normal incidence. The MAM is composed of a prestretched elastic membrane with attached rigid masses. To accurately capture finite-dimension rigid mass effects on the membrane deformation, the point matching approach is adopted by applying a set of distributed point forces along the interfacial boundary between masses and the membrane. The accuracy and capability of the theoretical model is verified through the comparison with the finite element method. In particular, microstructure effects such as weight, size, and eccentricity of the attached mass, pretension, and thickness of the membrane on the resulting transmission peak and dip frequencies of the MAM are quantitatively investigated. New peak and dip frequencies are found for the MAM with one and multiple eccentric attached masses. The developed model can be served as an efficient tool for design of such membrane-type metamaterials. [ABSTRACT FROM AUTHOR]

The predictive value of thymidine phosphorylase gene variants (TP, also called platelet-derived endothelial cell growth factor) and thrombocytosis were controversial and worthy of further study in gastrointestinal cancer (GIC) patients. We screened all of the common missense single nucleotide polymorphisms (MAF ≥ 0.1) in fluoropyrimidines (FU) pathway genes (including TP, TS, ENOSF1 and DPD). Three of them were selected and genotyped using Sequenom MassARRAY in 141 GIC patients. TP expression was assessed by immunohistochemistry. Our aim was to evaluate the prognostic significance of studied genes and platelet counts in GIC patients. Multivariate analyses indicated in rs11479-T allele carriers, platelet counts negatively correlated to overall survival. In addition, T allele of TP: rs11479 was associated with higher TP expression in cancer tissues. We suggest TP: rs11479 variant combined with platelet counts may be useful prognostic makers in GIC patients receiving first-line FU chemotherapy and thrombopoietin factor should be used with caution in the rs11479 T allele bearing patients. [ABSTRACT FROM AUTHOR]

Electrochemical biosensors have been studied intensively for several decades. Numerous sensing concepts and related interface architectures have been developed. However, all such architectures suffer a trade-off: simple architectures favour usability, whereas complex architectures favour better performance. To overcome this problem, we propose a novel concept by introducing a magneto-controlled moveable architecture (MCMA) instead of the conventional surface-fixed architecture. As a model, human breast cancer cells were used in this study. The results showed that a detection range from 100 to 1 x 106 cells could be achieved. Moreover, the whole detection cycle, including the measurement and the regeneration, could be completed in only 2 min. Thus, usability and excellent performance can be achieved in a single biosensor. [ABSTRACT FROM AUTHOR]

The development of suitable bioactive three-dimensional scaffold for the promotion of cellular proliferation and differentiation is critical in periodontal tissue engineering. In this study,porous β-tricalcium phosphate/chitosan composite scaffolds were prepared through a freeze-drying method. These scaffolds were evaluated by analysis of microscopic structure, porosity, and cytocompatibility. The gene expression of bone sialoprotein (BSP) and cementum attachment protein (CAP) was detected with RT-PCR after human periodontal ligament cells (HPLCs) were seeded in these scaffolds. Then cell–scaffold complexes were implanted subcutaneously into athymic mice. The protein expression of alkaline phosphatase (ALP) and osteopontin (OPN) was detected in vivo. Results indicated that composite scaffolds displayed a homogeneous three-dimensional microstructure; suitable pore size (120 μm) and high porosity (91.07%). The composite scaffold showed higher proliferation rate than the pure chitosan scaffold, and up-regulated the gene expression of BSP and CAP. In vivo, HPLCs in the composite scaffold not only proliferated but also recruited vascular tissue ingrowth. The protein expression of ALP and OPN was up-regulated in the composite scaffold. Therefore, it was suggested that the composite scaffold could promote the differentiation of HPLCs towards osteoblast and cementoblast phenotypes. [ABSTRACT FROM AUTHOR]

We propose and design a new adaptive sound absorption metamaterial targeting broadband airborne noise at extremely low frequencies. The metamaterial consists of two piezoelectric smart elements: a circular aluminum membrane with surface-bonded piezoelectric films controlled by shunting circuits enclosed with an air cavity for nearly total acoustic absorption at narrow-band frequencies; a hybrid-circuit shunted piezoelectric stack which is mechanically grounded attached to the center of the membrane for purely stiffness control to broaden this high-absorption bandwidth. A piezoelectric-structural-acoustic coupled model is firstly developed to evaluate the sound absorption of the metamaterial. We then perform analytical and numerical tests on metamaterials with and without the piezoelectric stack to design a metamaterial with broadband absorption at desired low frequencies. The underlying adaptive mechanism is to automatically regulate the effective acoustic resistance and reactance of the metamaterial to achieve impedance match conditions, according to different frequencies of inputs. Our numerical results demonstrate that the absorption coefficient of the adaptive metamaterial can be greater than 0.9 in the frequency region, 112–236 Hz with the relative bandwidth being around 0.7. The metamaterial thickness is 30 mm, which is nearly 1/65.6 wavelength of the central frequency of the absorption band. The proposed adaptive metamaterial may open a new avenue towards broadband sound absorption at extremely low frequencies. [ABSTRACT FROM AUTHOR]

With the aim to reduce the total structural weight, this paper presents a novel radial multi-layered elastic metamaterial (EM) shaft in which the scattering layer is circumferentially discretized into several arc-shaped sections with rotational symmetry. The dispersion relations and frequency-response-functions (FRF) of a finite structure are determined numerically first with different discretized geometries. To illustrate the mechanisms of band gaps, the eigenmodes were extracted and analyzed together with dispersion relations and FRF. The results show that in contrast to conventional multi-layered EM shafts, the proposed EM shaft with the weight being reduced by 34% can still yield broadband gaps at low-frequencies and by properly selecting the discretized geometry the band gap ranging from 139 to 197Hz exists for all three elastic wave modes. The results presented in this paper demonstrate a potential design strategy in stabilized shaft engineering. [ABSTRACT FROM AUTHOR]

Real-time engineering of elastic rays in solid materials is crucial for several applications relevant to active noise and vibration cancellation and to inverse methods aiming to either reveal or dissimulate the presence of foreign bodies. Here, we introduce a programmable elastic metasurface for the first time with sensing-and-actuating units, allowing to adapt and reprogram its wave control functionalities in real time. The active units behave following decoupled ‘feedforward’ sensor-to-actuator control loops governed by local transfer functions encoded into a digital circuit and offering highly flexible phase and amplitude engineering of transmitted and/or scattered waves. The proposed metasurface is concretized numerically and experimentally by achieving, for the first time, real-time tunable ray steering of flexural waves in a host plate. Various other significant demonstrations have been included to strongly illustrate the multifunctional adaptability of the design. In particular, one-way non-reciprocal blocking of waves is observed experimentally whereas skin cloaking of voids is tested numerically. Finally, operability across broad wave frequency ranges is demonstrated (5–45 kHz). The design will pave a new efficient way in the field of sensing and actuation of elastic waves. [ABSTRACT FROM AUTHOR]

Designing lightweight materials and/or structures for broadband low-frequency noise/vibration mitigation is an issue of fundamental importance both practically and theoretically. In this paper, by leveraging the concept of frequency-dependent effective stiffness control, we numerically and experimentally demonstrate, for the first time, a self-adaptive metamaterial beam with digital circuit controlled mechanical resonators for strong and broadband flexural wave attenuation at subwavelength scales. The digital controllers that are capable of feedback control of piezoelectric shunts are integrated into mechanical resonators in the metamaterial, and the transfer function is semi-analytically determined to realize an effective bending stiffness in a quadratic function of the wave frequency for adaptive band gaps. The digital as well as analog control circuits as the backbone of the system are experimentally realized with the guarantee stability of the whole electromechanical system in whole frequency regions, which is the most challenging problem so far. Our experimental results are in good agreement with numerical predictions and demonstrate the strong wave attenuation in almost a three times larger frequency region over the bandwidth of a passive metamaterial. The proposed metamaterial could be applied in a range of applications in the design of elastic wave control devices. [ABSTRACT FROM AUTHOR]

Background and Objectives: To evaluate the synergistic and individual associations of leisure-time physical activity (LTPA) intensity and the frequency of milk intake in adulthood with newly diagnosed pathoglycemia. Pathoglycemia comprised impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM).Methods and Study Design: This cross-sectional study of 3977 adults was conducted in Mentougou District, Beijing, China. After excluding ineligible individuals or those with missing data, 2977 participants were included in the final analysis. Data on LTPA, milk intake, and other demographic characteristics were obtained through previously designed questionnaires. Newly diagnosed pathoglycemia was determined based on fasting plasma glucose (FPG) concentration.Results: Among all participants, 21.4% had newly diagnosed pathoglycemia, 9.9% engaged in moderate to vigorous leisure-time physical activity (MVLTPA), and 63.7% drank milk more than once weekly. Relative to those who engaged in low-intensity LTPA and drank milk less than once weekly, those who engaged in MVLTPA (OR: 0.584, 95%CI: 0.410-0.810) and drank milk more than once weekly (OR: 0.734, 95% CI: 0.614-0.878) had a lower risk of pathoglycemia; this association was greater when both variables interacted (OR: 0.446, 95% CI: 0.287-0.669).Conclusions: MVLTPA and enough frequency of milk intake synergistically decreased the risk of pathoglycemia. A future interventional study including both factors should be performed. [ABSTRACT FROM AUTHOR]

Solids built out of active components have exhibited odd elastic stiffness tensors whose active moduli appear in the antisymmetric part and which give rise to non-Hermitian static and dynamic phenomena. Here, we present a class of active metamaterial featured with an odd mass density tensor whose asymmetric part arises from active and nonconservative forces. The odd mass density is realized using metamaterials with inner resonators connected by asymmetric and programmable feed-forward control on acceleration and active forces along the two perpendicular directions. The active forces produce unbalanced off-diagonal mass density coupling terms, leading to non-Hermiticity. The odd mass is then experimentally validated through a one-dimensional nonsymmetric wave coupling where propagating transverse waves are coupled with longitudinal ones whereas the reverse is forbidden. We reveal that the two-dimensional active metamaterials with the odd mass can perform in either energy-unbroken or energy-broken phases separated by exceptional points along principal directions of the mass density. The odd mass density contributes to the wave anisotropy in the energy-unbroken phase and directional wave energy gain in the energy-broken phase. We also numerically illustrate and experimentally demonstrate the two-dimensional wave propagation phenomena that arise from the odd mass in active solids. Finally, the existence of non-Hermitian skin effect is discussed in which boundaries host an extensive number of localized modes. It is our hope that the emergent concept of the odd mass can open up a new research platform for mechanical non-Hermitian system and pave the ways for developing next-generation wave steering devices. [ABSTRACT FROM AUTHOR]

WEE1 has emerged as an attractive target in epithelial ovarian cancer (EOC), but how EOC cells may alter sensitivity to WEE1 inhibition remains unclear. Here, through a cell cycle machinery-related gene RNAi screen, we found that targeting ODF2L is synthetic lethal with WEE1 kinase inhibition in EOC cells. Knockdown of ODF2L robustly sensitized cells to treatment of the WEE1 inhibitor AZD1775 in EOC cell lines in vitro, as well as xenografts in vivo. Mechanistically, the increased sensitivity to WEE1 inhibition upon ODF2L loss was accompanied by accumulated DNA damage. ODF2L licensed the recruitment of PKMYT1, a functionally redundant kinase of WEE1, to the CDK1/cyclin B complex and thus restricted the activity of CDK1 when WEE1 was inhibited. Clinically, upregulation of ODF2L correlated with CDK1 activity, DNA damage level, and sensitivity to WEE1 inhibition in patient-derived EOC cells. Moreover, the ODF2L level predicted the response to WEE1 inhibition in an EOC patient-derived xenograft model. Combination treatment with tumor-targeted lipid nanoparticles that package ODF2L siRNA and AZD1775 led to the synergistic attenuation of tumor growth in the ID8 ovarian cancer syngeneic mouse model. These data suggest that WEE1 inhibition is a promising precision therapeutic strategy for ODF2L-low-expressing EOC cells. [ABSTRACT FROM AUTHOR]

• Developed real-time hybrid model (RTHM) tests to reproduce Saige building vibration incident. • Developed RTHM testing system that includes the loading system, instrumentations, and the delay compensation component. • Wind loads tests of the masts were first carried out show that the dynamic characteristics of scaled mast models were conserved. • RTHM results demonstrate the capability of the developed testing method to reproduce the Saige building abnormal vibration. In May 2021, the 72-story Shenzhen Saige building experienced abnormal vibration that was strongly felt on many floors and triggered social panic. The tower was therefore closed for more than 2 months resulting in huge economic losses. A preliminary study consisting of field resonant excitation tests and a series of numerical simulations were carried out. It was concluded that the wind loads provoked the higher modes of the building vibration. Specifically, the vibration of the mast, which is located at the building top, induced this abnormal vibration. To validate this conclusion, real-time hybrid model (RTHM) tests was developed to reproduce this building vibration incident. This paper presents the details of the validation RTHM tests including testing design and result discussions. Structural vibration parameters obtained from the field tests were used in the numerical substructure building model, and the experimental substructures were the two scaled down mast models (the cantilever beam section of the masts). During RTHM test, the restoring force of the experimental substructure due to real wind loads induced by an air fan was measured and used in the numerical simulation to compute interface motions. A shaking table was then used to impose the interface motion back to the bottom of the mast model to reproduce the abnormal vibration incident. The demonstrated ability of the developed RTHM testing method to reproduce the resonant phenomenon of the wind-induced tower vibration provides an alternative experimental method to study vibration responses of high-rise buildings in future. [ABSTRACT FROM AUTHOR]

Pencils and papers are ubiquitous in our society and have been widely used for writing and drawing, because they are easy to use, low-cost, widely accessible, and disposable. However, their applications in emerging skin-interfaced health monitoring and interventions are still not well explored. Herein, we report a variety of pencil-paper-based on-skin electronic devices, including biophysical (temperature, biopotential) sensors, sweat biochemical (pH, uric acid, glucose) sensors, thermal stimulators, and humidity energy harvesters. Among these devices, pencil-drawn graphite patterns (or combined with other compounds) serve as conductive traces and sensing electrodes, and office-copy papers work as flexible supporting substrates. The enabled devices can perform real-time, continuous, and high-fidelity monitoring of a range of vital biophysical and biochemical signals from human bodies, including skin temperatures, electrocardiograms, electromyograms, alpha, beta, and theta rhythms, instantaneous heart rates, respiratory rates, and sweat pH, uric acid, and glucose, as well as deliver programmed thermal stimulations. Notably, the qualities of recorded signals are comparable to those measured with conventional methods. Moreover, humidity energy harvesters are prepared by creating a gradient distribution of oxygen-containing groups on office-copy papers between pencil-drawn electrodes. One single-unit device (0.87 cm²) can generate a sustained voltage of up to 480 mV for over 2 h from ambient humidity. Furthermore, a self-powered on-skin iontophoretic transdermal drug-delivery system is developed as an on-skin chemical intervention example. In addition, pencil-paper-based antennas, two-dimensional (2D) and three-dimensional (3D) circuits with light-emitting diodes (LEDs) and batteries, reconfigurable assembly and biodegradable electronics (based on water-soluble papers) are explored. [ABSTRACT FROM AUTHOR]

The article presents a study which demonstrates the spin superfluid ground state in canted antiferromagnetic chromium dioxide thin film at low temperatures via nonlocal spin transport. It mentions that spin superfluidity has been investigated in the canted antiferromagnetic phase of chromium dioxide film, where the magnetic field dependence of the associated critical temperature follows a power law near the critical point.

Research on breaking time-reversal symmetry to realize one-way wave propagation is a growing area in photonic and phononic crystals and metamaterials. In this Letter, we present physical realization of an acoustic waveguide with spatiotemporally modulated boundary conditions to realize nonreciprocal transport and acoustic topological pumping. The modulated waveguide inspired by a water wheel consists of a helical tube rotating around a slotted tube at a controllable speed. The rotation of the helical tube creates moving boundary conditions for the exposed waveguide sections at a constant speed. We experimentally demonstrate acoustic nonreciprocity and topologically robust bulk-edge correspondences for this system, which is in good agreement with analytical and numerical predictions. The nonreciprocal waveguide is a one-dimensional analog to the two-dimensional quantum Hall effect for acoustic circulators and is characterized by a robust integer-valued Chern number. These findings provide insight into practical implications of topological modes in acoustics and the implementation of higher-dimensional topological acoustics where time serves as a synthetic dimension. [ABSTRACT FROM AUTHOR]

An elastic cloak is a coating material that can be applied to an arbitrary inclusion to make it indistinguishable from the background medium. Cloaking against elastic disturbances, in particular, has been demonstrated using several designs and gauges. None, however, tolerate the coexistence of normal and shear stresses due to a shortage of physical realization of transformation-invariant elastic materials. Here, we overcome this limitation to design and fabricate a new class of polar materials with a distribution of body torque that exhibits asymmetric stresses. A static cloak for full two-dimensional elasticity is thus constructed based on the transformation method. The proposed cloak is made of a functionally graded multilayered lattice embedded in an isotropic continuum background. While one layer is tailored to produce a target elastic behavior, the other layers impose a set of kinematic constraints equivalent to a distribution of body torque that breaks the stress symmetry. Experimental testing under static compressive and shear loads demonstrates encouraging cloaking performance in good agreement with our theoretical prediction. The work sets a precedent in the field of transformation elasticity and should find applications in mechanical stress shielding and stealth technologies. [ABSTRACT FROM AUTHOR]

The search for long electron phase-coherence length, which is the length that an electron can keep its quantum wavelike properties, has attracted considerable interest in the last several decades. Here, we report the long phase-coherence length of ~3.7 μm in La-doped CdO thin films at 2 K. Systematical investigations of the La doping and the temperature dependences of the electron mobility and the electron phase-coherence length reveal contrasting scattering mechanisms for these two physical properties. Furthermore, these results show that the oxygen vacancies could be the dominant scatters in CdO thin films that break the electron phase coherence, which would shed light on further investigation of phase-coherence properties in oxide materials. [ABSTRACT FROM AUTHOR]