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Experimental contributors to the field of superconducting materials share their informal views on the subject.

Objective: A computer vision method was developed for estimating the trunk flexion angle, angular speed, and angular acceleration by extracting simple features from the moving image during lifting., Background: Trunk kinematics is an important risk factor for lower back pain, but is often difficult to measure by practitioners for lifting risk assessments., Methods: Mannequins representing a wide range of hand locations for different lifting postures were systematically generated using the University of Michigan 3DSSPP software. A bounding box was drawn tightly around each mannequin and regression models estimated trunk angles. The estimates were validated against human posture data for 216 lifts collected using a laboratory-grade motion capture system and synchronized video recordings. Trunk kinematics, based on bounding box dimensions drawn around the subjects in the video recordings of the lifts, were modeled for consecutive video frames., Results: The mean absolute difference between predicted and motion capture measured trunk angles was 14.7°, and there was a significant linear relationship between predicted and measured trunk angles ( R 2 = .80, p < .001). The training error for the kinematics model was 2.3°., Conclusion: Using simple computer vision-extracted features, the bounding box method indirectly estimated trunk angle and associated kinematics, albeit with limited precision., Application: This computer vision method may be implemented on handheld devices such as smartphones to facilitate automatic lifting risk assessments in the workplace.

Objective: To examine the influence of competing voices or noise on the comprehension of spoken narratives for young adults., Design: First, an intelligibility assessment of the target narratives was conducted to establish a signal-to-noise ratio ensuring accurate initial speech recognition. Then, narrative comprehension for two target types ( fixed and varied target talker ) was measured in four listening conditions ( quiet, one-talker speech, speech babble, speech-shaped noise ). After hearing target narratives in each listening condition, participants completed a visual recognition memory task that assessed the comprehension of the narrative materials at three levels of representation ( surface form, propositional, event model )., Study Sample: Seventy adults (18-32 years of age)., Results: Narrative comprehension results revealed a main effect of listening condition at the event model level, indicating poorer narrative memory of described situations for all noise conditions compared to quiet. Increased positive responses to thematically consistent but situationally "wrong" memory probes drove this effect. No other significant effects were observed., Conclusion: Despite near-perfect speech recognition, background noise negatively influenced aspects of spoken narrative comprehension and memory. Specifically, noise did not disrupt memory for what was said (surface form and propositional memory), but only memory for what was talked about (event model memory).

According to conventional wisdom, the extraordinary properties of the cuprate high-temperature superconductors arise from doping a strongly correlated antiferromagnetic insulator. The highly overdoped cuprates-whose doping lies beyond the dome of superconductivity-are considered to be conventional Fermi liquid metals. We report the emergence of itinerant ferromagnetic order below 4 kelvin for doping beyond the superconducting dome in thin films of electron-doped La 2- x Ce x CuO 4 (LCCO). The existence of this ferromagnetic order is evidenced by negative, anisotropic, and hysteretic magnetoresistance, hysteretic magnetization, and the polar Kerr effect, all of which are standard signatures of itinerant ferromagnetism in metals. This surprising result suggests that the overdoped cuprates are strongly influenced by electron correlations., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Workers in hospitals, clinics, and contract research organizations who repetitively use syringes have an increased risk for musculoskeletal disorders. This study developed and tested a novel syringe adapter designed to reduce muscle strain associated with repetitive fluid draws. Three syringe plunger extension methods (ring-finger, middle-finger, and syringe adapter) were studied across twenty participants. Electromyogram signals for the flexor digitorum superficialis and extensor digitorum muscles were recorded. The syringe adapter required 31% of the 90th percentile flexor muscle activity as compared to the ring-finger syringe extension method, and 45% the 90th percentile flexor muscle activity as compared to the middle-finger method (p < 0.001). The greatest differences were observed when the syringe was near full extension. Although the syringe adapter took more time than the other syringe extension methods (1.5 times greater), it greatly helped reduce physical stress associated with repetitive, awkward syringe procedures., Competing Interests: Declaration of competing interest A patent for the syringe adapter presented was filed by the Wisconsin Alumni Research Foundation., (Copyright © 2020. Published by Elsevier Ltd.)

In 1928, Dirac proposed a wave equation to describe relativistic electrons 1 . Shortly afterwards, Klein solved a simple potential step problem for the Dirac equation and encountered an apparent paradox: the potential barrier becomes transparent when its height is larger than the electron energy. For massless particles, backscattering is completely forbidden in Klein tunnelling, leading to perfect transmission through any potential barrier 2,3 . The recent advent of condensed-matter systems with Dirac-like excitations, such as graphene and topological insulators, has opened up the possibility of observing Klein tunnelling experimentally 4-6 . In the surface states of topological insulators, fermions are bound by spin-momentum locking and are thus immune from backscattering, which is prohibited by time-reversal symmetry. Here we report the observation of perfect Andreev reflection in point-contact spectroscopy-a clear signature of Klein tunnelling and a manifestation of the underlying 'relativistic' physics of a proximity-induced superconducting state in a topological Kondo insulator. Our findings shed light on a previously overlooked aspect of topological superconductivity and can serve as the basis for a unique family of spintronic and superconducting devices, the interface transport phenomena of which are completely governed by their helical topological states.

An understanding of the normal state in the high-temperature superconducting cuprates is crucial to the ultimate understanding of the long-standing problem of the origin of the superconductivity itself. This so-called "strange metal" state is thought to be associated with a quantum critical point (QCP) hidden beneath the superconductivity. In electron-doped cuprates-in contrast to hole-doped cuprates-it is possible to access the normal state at very low temperatures and low magnetic fields to study this putative QCP and to probe the T ➔ 0 K state of these materials. We report measurements of the low-temperature normal-state magnetoresistance (MR) of the n-type cuprate system La 2- x Ce x CuO 4 and find that it is characterized by a linear-in-field behavior, which follows a scaling relation with applied field and temperature, for doping ( x ) above the putative QCP ( x = 0.14). The magnitude of the unconventional linear MR decreases as T c decreases and goes to zero at the end of the superconducting dome ( x ~ 0.175) above which a conventional quadratic MR is found. These results show that there is a strong correlation between the quantum critical excitations of the strange metal state and the high- T c superconductivity.

In the physics of condensed matter, quantum critical phenomena and unconventional superconductivity are two major themes. In electron-doped cuprates, the low critical field (H C2 ) allows one to study the putative quantum critical point (QCP) at low temperature and to understand its connection to the long-standing problem of the origin of the high- T C superconductivity. Here we present measurements of the low-temperature normal-state thermopower ( S ) of the electron-doped cuprate superconductor La 2- x Ce x CuO 4 (LCCO) from x = 0.11-0.19. We observe quantum critical [Formula: see text] versus [Formula: see text] behavior over an unexpectedly wide doping range x = 0.15-0.17 above the QCP ( x = 0.14), with a slope that scales monotonically with the superconducting transition temperature ( T C with H = 0). The presence of quantum criticality over a wide doping range provides a window on the criticality. The thermopower behavior also suggests that the critical fluctuations are linked with T C Above the superconductivity dome, at x = 0.19, a conventional Fermi-liquid [Formula: see text] behavior is found for [Formula: see text] 40 K., Competing Interests: The authors declare no conflict of interest.

Objective: A method for automatically classifying lifting postures from simple features in video recordings was developed and tested. We explored if an "elastic" rectangular bounding box, drawn tightly around the subject, can be used for classifying standing, stooping, and squatting at the lift origin and destination., Background: Current marker-less video tracking methods depend on a priori skeletal human models, which are prone to error from poor illumination, obstructions, and difficulty placing cameras in the field. Robust computer vision algorithms based on spatiotemporal features were previously applied for evaluating repetitive motion tasks, exertion frequency, and duty cycle., Methods: Mannequin poses were systematically generated using the Michigan 3DSSPP software for a wide range of hand locations and lifting postures. The stature-normalized height and width of a bounding box were measured in the sagittal plane and when rotated horizontally by 30°. After randomly ordering the data, a classification and regression tree algorithm was trained to classify the lifting postures., Results: The resulting tree had four levels and four splits, misclassifying 0.36% training-set cases. The algorithm was tested using 30 video clips of industrial lifting tasks, misclassifying 3.33% test-set cases. The sensitivity and specificity, respectively, were 100.0% and 100.0% for squatting, 90.0% and 100.0% for stooping, and 100.0% and 95.0% for standing., Conclusions: The tree classification algorithm is capable of classifying lifting postures based only on dimensions of bounding boxes., Applications: It is anticipated that this practical algorithm can be implemented on handheld devices such as a smartphone, making it readily accessible to practitioners.

High-temperature copper oxide superconductors consist of stacked CuO 2 planes, with electronic band structures and magnetic excitations that are primarily two-dimensional 1,2 , but with superconducting coherence that is three-dimensional. This dichotomy highlights the importance of out-of-plane charge dynamics, which has been found to be incoherent in the normal state 3,4 within the limited range of momenta accessible by optics. Here we use resonant inelastic X-ray scattering to explore the charge dynamics across all three dimensions of the Brillouin zone. Polarization analysis of recently discovered collective excitations (modes) in electron-doped copper oxides 5-7 reveals their charge origin, that is, without mixing with magnetic components 5-7 . The excitations disperse along both the in-plane and out-of-plane directions, revealing its three-dimensional nature. The periodicity of the out-of-plane dispersion corresponds to the distance between neighbouring CuO 2 planes rather than to the crystallographic c-axis lattice constant, suggesting that the interplane Coulomb interaction is responsible for the coherent out-of-plane charge dynamics. The observed properties are hallmarks of the long-sought 'acoustic plasmon', which is a branch of distinct charge collective modes predicted for layered systems 8-12 and argued to play a substantial part in mediating high-temperature superconductivity 10-12 .

Patterns of physical stress exposure are often difficult to measure, and the metrics of variation and techniques for identifying them is underdeveloped in the practice of occupational ergonomics. Computer vision has previously been used for evaluating repetitive motion tasks for hand activity level (HAL) utilizing conventional 2D videos. The approach was made practical by relaxing the need for high precision, and by adopting a semi-automatic approach for measuring spatiotemporal characteristics of the repetitive task. In this paper, a new method for visualizing task factors, using this computer vision approach, is demonstrated. After videos are made, the analyst selects a region of interest on the hand to track and the hand location and its associated kinematics are measured for every frame. The visualization method spatially deconstructs and displays the frequency, speed and duty cycle components of tasks that are part of the threshold limit value for hand activity for the purpose of identifying patterns of exposure associated with the specific job factors, as well as for suggesting task improvements. The localized variables are plotted as a heat map superimposed over the video, and displayed in the context of the task being performed. Based on the intensity of the specific variables used to calculate HAL, we can determine which task factors most contribute to HAL, and readily identify those work elements in the task that contribute more to increased risk for an injury. Work simulations and actual industrial examples are described. This method should help practitioners more readily measure and interpret temporal exposure patterns and identify potential task improvements., (Copyright © 2017. Published by Elsevier Ltd.)

Previous research has demonstrated a retrospective memory bias in metacognitive judgments regarding performance on general knowledge questions: Test-takers rate their own performance more optimistically when tests begin with easy questions than when tests begin with hard questions. An anchoring heuristic has been proposed to explain this finding, in which experience with the early questions constrains global performance evaluations of the test. In the current study we report on two experiments using tasks of item recognition and associative recognition to investigate the generality of question order bias. As predicted by an anchoring explanation, participants' estimates of performance were higher for item recognition tests beginning with easy items. However, the effect was reversed in the associative recognition task: Participants' estimates of performance were higher for tests beginning with hard items. Specific recollections, if present, may have a greater impact on test performance perception than more general global impressions.

Racial difference of religiosity in a heterogeneous older population had long been a focal point of gerontological research. However, most religiosity measures were developed from homogenous sample, few underwent rigorous psychometric validation, and studies on racial difference of religiosity had been obstructed. This cross-sectional study adapted a religiosity measure originally designed for blacks only to a heterogeneous older population of blacks and whites, validated its psychometric properties, and examined racial difference of religiosity. Based on qualitative research of concepts, intensive literature review, and abundant experiences in this field, we adapted the original measure. Then, using the data collected from a survey of 196 black and white Americans 55 years and older in Charlotte, North Carolina, we investigated full-scale psychometric properties of the adapted measure at the item-, domain-, and measure- level. These psychometric validations included item analysis, item-scale correlations, correlation matrix among items, confirmatory factor analysis (CFA) to determine if the original factor structure held after adaptation, and reliability analysis using Cronbach's alpha. Finally, using Multiple Indicators and MultIple Causes (MIMIC) models, we examined racial difference of religiosity through regression with latent variables, while potential measurement bias by race through differential item functioning (DIF) was adjusted in the MIMIC models. In result, we successfully adapted the original 12-item religiosity measure for blacks into an 8-item version for blacks and whites. Although sacrificed few reliability for brevity, the adapted measure demonstrated sound psychometric properties, and retained the original factor structure. We also found racial differences of religiosity in all three domains of the measure, even after adjustment of the detected measurement biases in two domains. In conclusion, the original measure can be adapted to and validated for a heterogeneous older population of blacks and whites. Although the adapted measure can be used to measure the three domains of religiosity in blacks and whites, the observed racial differences of religiosity need to be adjusted for measurement biases before meaningful comparisons.

Understanding the interplay between charge order (CO) and other phenomena (for example, pseudogap, antiferromagnetism, and superconductivity) is one of the central questions in the cuprate high-temperature superconductors. The discovery that similar forms of CO exist in both hole- and electron-doped cuprates opened a path to determine what subset of the CO phenomenology is universal to all the cuprates. We use resonant x-ray scattering to measure the CO correlations in electron-doped cuprates (La2-x Ce x CuO4 and Nd2-x Ce x CuO4) and their relationship to antiferromagnetism, pseudogap, and superconductivity. Detailed measurements of Nd2-x Ce x CuO4 show that CO is present in the x = 0.059 to 0.166 range and that its doping-dependent wave vector is consistent with the separation between straight segments of the Fermi surface. The CO onset temperature is highest between x = 0.106 and 0.166 but decreases at lower doping levels, indicating that it is not tied to the appearance of antiferromagnetic correlations or the pseudogap. Near optimal doping, where the CO wave vector is also consistent with a previously observed phonon anomaly, measurements of the CO below and above the superconducting transition temperature, or in a magnetic field, show that the CO is insensitive to superconductivity. Overall, these findings indicate that, although verified in the electron-doped cuprates, material-dependent details determine whether the CO correlations acquire sufficient strength to compete for the ground state of the cuprates.

The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2-xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of -2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected.

LiTi2O4 is a unique compound in that it is the only known spinel oxide superconductor. The lack of high quality single crystals has thus far prevented systematic investigations of its transport properties. Here we report a careful study of transport and tunnelling spectroscopy in epitaxial LiTi2O4 thin films. An unusual magnetoresistance is observed which changes from nearly isotropic negative to prominently anisotropic positive as the temperature is decreased. We present evidence that shows that the negative magnetoresistance likely stems from the suppression of local spin fluctuations or spin-orbit scattering centres. The positive magnetoresistance suggests the presence of an orbital-related state, also supported by the fact that the superconducting energy gap decreases as a quadratic function of magnetic field. These observations indicate that the spin-orbital fluctuations play an important role in LiTi2O4 in a manner similar to high-temperature superconductors.

Superconductivity is a striking example of a quantum phenomenon in which electrons move coherently over macroscopic distances without scattering. The high-temperature superconducting oxides (cuprates) are the most studied class of superconductors, composed of two-dimensional CuO2 planes separated by other layers that control the electron concentration in the planes. A key unresolved issue in cuprates is the relationship between superconductivity and magnetism. Here we report a sharp phase boundary of static three-dimensional magnetic order in the electron-doped superconductor La(2-x)Ce(x)CuO(4-δ), where small changes in doping or depth from the surface switch the material from superconducting to magnetic. Using low-energy spin-polarized muons, we find that static magnetism disappears close to where superconductivity begins and well below the doping level at which dramatic changes in the transport properties are reported. These results indicate a higher degree of symmetry between the electron and hole-doped cuprates than previously thought.

In cuprate high-temperature superconductors, an antiferromagnetic Mott insulating state can be destabilized toward unconventional superconductivity by either hole or electron doping. In hole-doped (p-type) cuprates, a charge ordering (CO) instability competes with superconductivity inside the pseudogap state. We report resonant x-ray scattering measurements that demonstrate the presence of charge ordering in the n-type cuprate Nd(2-x)Ce(x)CuO4 near optimal doping. We find that the CO in Nd(2-x)Ce(x)CuO4 occurs with similar periodicity, and along the same direction, as in p-type cuprates. However, in contrast to the latter, the CO onset in Nd(2-x)Ce(x)CuO4 is higher than the pseudogap temperature, and is in the temperature range where antiferromagnetic fluctuations are first detected. Our discovery opens a parallel path to the study of CO and its relationship to antiferromagnetism and superconductivity., (Copyright © 2015, American Association for the Advancement of Science.)