Large Negative Peak Research Articles

Observation of the Liquid-Liquid Phase Separation of FUS-LC Using Vacuum-Ultraviolet Circular Dichroism Spectroscopy.

To reveal the structural mechanism by which the low-complexity domain of the fused in sarcoma protein (FUS-LC) mediates liquid-liquid phase separation (LLPS), we conducted a vacuum-ultraviolet circular dichroism (VUV-CD) spectroscopic study, a technique to analyze the secondary structures of proteins. The VUV-CD measurements were performed at the BL12 VUV-CD station at the Hiroshima Synchrotron Radiation Center (HiSOR) in Japan. CD spectra were measured between 180 and 260 nm while controlling the temperature of samples from 37°C to 5°C to obtain the LLPS of FUS-LC. The CD spectrum obtained at 37°C exhibited a large negative peak at 195 nm and a small negative shoulder near 220 nm. The peak intensity around 195 nm decreased as the sample temperature decreased. The spectral changes originated from the LLPS formation.

Hopping thermopower in FEGA3

A narrow-gap semiconductor FeGa3 has attracted much interest for its unusual physical properties, in particular, for its colossal thermopower at low temperatures for which the origin has not been elucidated yet. In this study, the temperature-dependence data of the conductivity, the Hall coefficient, and the Seebeck coefficient on FeGa3 samples reported by Wagner-Reetz et al. [Phys. Rev. B 90, 195206 (2014)] have been analyzed with including the effects of impurity Hubbard bands. As a result, it is shown that, contrary to the claim by Wagner-Reetz et al., the large negative peak of the Seebeck coefficient is not due to the phonon-drag effect but due to hopping conduction in the impurity Hubbard bands. The significant effect of nonpolar-optical-phonon scattering on free-electron conduction is also pointed out.

Electronic, optical, magneto-optical, and thermoelectric properties of the SrS graphene-like under Cr impurity

The Cr effects on electronic, optical, magneto-optical and thermoelectric properties of SrS graphene-like are discussed. The SrS graphene-like is a stable crystalline structure in static and dynamic viewpoints. The SrS graphene-like is a p-type semiconductor with 2.1 eV energy gap, and it is transformed into a half-metal with 100% spin polarization by substituting the Cr impurity. The static value of the dielectric function represents the semiconductor behavior for SrS–Cr graphene-like. The values of the dielectric function at energies between 7 and 10 eV reach one and less than one. Due to the magnetic nature of this compound, the Kerr angle in the range of 4 to 5 eV has a large negative peak, creating a large polarization. Moreover, from a thermoelectric point of view, the figure of merit is a significant number at temperatures above the room temperature in the range of 500 to 600 K and it is about 0.9 at 500 K.

Influence of Sprint Duration during Minimal Volume Exercise on Aerobic Capacity and Affect.

The aims of this study were to investigate the influence of reduced-exertion, high-intensity interval training (REHIT), comparing a novel shortened-sprint protocol (SSREHIT) against a traditional protocol (TREHIT), on perceptual responses and to determine if changes in peak oxygen uptake (V˙O2peak) are attenuated with shorter sprints. Twenty-four healthy men undertook 15 sessions of SSREHIT or TREHIT. V˙O2peak was determined at baseline and after completion of each exercise condition. Affective (pleasure-displeasure) responses and perceived exertion were assessed during exercise to capture peak responses. Enjoyment was recorded 5-min after cessation of exercise. Compared to baseline, V˙O2peak increased in both groups (6% for SSREHIT [d=- 0.36] and 9% for TREHIT [d=- 0.53], p=0.01). Affective responses were more favourable for SSREHIT (p=0.001, d=1.62), but both protocols avoided large negative peaks of displeasure. Peak ratings of perceived exertion were lower for SSREHIT (p=0.001, d=- 1.71), although there were no differences in enjoyment (d=0.25). The results demonstrate both exercise conditions can increase V˙O2peak without overly compromising perceptual responses. Decreased sprint duration might further circumvent negative perceptual responses but might also attenuate physiological adaptations.

A de-mixing approach for the management of large negative peaks in wind tunnel data

Large negative peak pressures commonly take place near the edges of buildings due to the presence of local corner vortices and impingement of shear layers. As a result, Probability Density Functions (PDF) of the measured pressure signals exhibit one or more components which contributes to the non-Gaussianity of the pressure loading. These mixed flows can be modeled with mixture models. Whenever several processes coexist, and when one of them is leading in the tail of the statistical distribution, it is natural to construct the extreme value model with only this process leading in the tail and not with the mixed observed pressures. In this paper, we propose a method that is based on the autocorrelation of the pressure coefficient to de-mix the measured signals. This information improves the de-mixing process where classical methods would struggle. Indeed, the two phenomena to be separated and identified might be characterized by significantly different time-scales, which are not reflected in the PDF. In this paper, the large negative pressures measured on a flat roof are analyzed and decomposed into two elementary processes, namely, the flapping corner vortex and the turbulent flow detaching from the sharp upstream edges. This paper finally shows that an accurate decomposition of the recorded pressures into their underlying modes provides a more meaningful evaluation of extreme pressures.

Numerical prediction of the slipstream caused by the trains with different marshalling forms entering a tunnel

Unsteady Reynolds-averaged Navier–Stokes (URANS) simulations were performed to simulate the flows around three different train types as they enter a tunnel. The three models—a short train, a double train, and a long train—were used to analyze the influence of the train configuration on the surrounding airflows and aerodynamic performance. The numerical predictions showed good agreement with existing experimental data. The maximum positive velocity peak induced by a short train passing through a tunnel was 140% larger than that produced in open air. The amplitudes of the slipstream velocity components decreased as the height from the ground increased. Large differences were found between the velocity fields produced by long and double trains. The velocity field had a large negative peak when a long train traversed the tunnel. This peak grew along the tunnel towards the exit. When a train is running in a double-track tunnel, the airflow above the two tracks moves in opposite directions. The double train induced a 53% higher velocity than the single train, but only a 6% higher velocity than the long train.

Systematic analysis of residual density suggests that a major limitation in well‐refined X‐ray structures of proteins is the omission of ordered solvent

In the residual electron density map of a fully refined X-ray protein model, there should be no peaks arising from modeling errors or missing atoms. Any residual peaks that do occur should be contributed by random residual intensity differences between the model and the data. If the model is incomplete (i.e., some atoms are missing), there will be more positive peaks than negative ones. On the other hand, if the model includes inappropriately located atoms, there will be an excess of negative peaks. In this study, random residual peaks are quantified using the probability density function P(x), which is defined as the probability for a peak having peak height between x and x + dx. It is found that P(x) is single-exponential and symmetric for both positive and negative peaks. Thus, P(x) can be used to discriminate residual peaks contributed by random noise in complete models from residual peaks being attributable to modeling errors in incomplete models. For a number of representative structures in the PDB it is found that P(x) has far more large (greater than 5 sigma) positive peaks than large negative peaks. This excess of large positive peaks suggests that the main defect in these refined structures is the omission of ordered water molecules.

Enhanced oscillatory rectification and negative differential resistance in pentamantane diamondoid-cumulene systems.

We propose a new functionality for diamondoids in nanoelectronics. Based on the nonequilibrium Green's function formalism and density functional theory, we reveal that when attached to gold electrodes, the pentamantane-cumulene molecular junction exhibits large and oscillatory rectification and negative differential resistance (NDR) - depending on the number of carbon atoms in cumulene (Cn). When n is odd rectification is greatly enhanced where the rectification ratio can reach ∼180 and a large negative differential resistance peak current of ∼3 μA. This oscillatory behavior is well rationalised in terms of the occupancy of the carbon 2p states in Cn. Interestingly, different layers of C atoms in the pentamantane molecule have different contributions to transmission. The first and third layers of C atoms in pentamantane have a slight contribution to rectification, and the fifth and sixth layers have a stronger contribution to both rectification and NDR. Thus, our results suggest potential avenues for controlling their functions by chemically manipulating various parts of the diamondoid molecule, thus extending the applications of diamondoids in nanoscale integrated circuits.

Recording of cord dorsum potentials in calves

Cord dorsum potentials are sensory evoked potentials being used to assess proximal sensory nerve, dorsal nerve root and spinal cord dorsal horn function. The purpose of the present study was to establish normal values for onset latency, peak latency and peak-to-peak amplitude of cord dorsum potentials after saphenous nerve stimulation in 15 healthy calves.Under general anesthesia, the saphenous nerve was stimulated in the periphery and cord dorsum potentials were recorded from the interarcuate space L3–L4, L4–L5, L5–L6 and L6–S1.Cord dorsum potentials were easily recorded at the different recording sites and consisted of a large negative peak followed by a long latency positive phase. The largest responses were recorded at the L5–L6 interarcuate space. Body temperature significantly influenced peak-to-peak amplitude. Onset latency prolonged with increasing limb length.

Utilizing electromagnetic spectrum for subsurface void detection—case studies

Three field projects are presented to demonstrate the application of electromagnetic spectrums for subsurface void detections. It was found that when the void is air-filled, a large negative peak will appear in the waveform, since the dielectric constant of air is much lower than for any surrounding material. Coring and drilling were used for verification purpose. Void sizes from 50 mm to 2 m were successfully detected in this study by using 400 MHz ground-coupled penetrating radar. There is a strong correlation for the arrival times and the size of the void. When the size of the voids increased, the arrival times for the top of voids become longer (e.g., approximately 8 to 10 %, depending on the size of voids). There are inversions and significant negative reflections in the ground-penetrating radar (GPR) image where the defect (air-filled void) is. In contrast, water-filled voids were detected and confirmed in case study 3 with positive peaks. The electromagnetic spectrum was able to locate voids in time. Otherwise, the voids would have grown in size and probably caused the pavement to collapse, which may have caused human casualties and property loss.

Applications of Electromagnetic Waves for Void and Anomaly Detections

Abstract Knowledge of the existing roadway condition is vital to transportation government agencies for management and safety purposes. Verifying the presence and extent of subsurface defects/voids is vital to prevent failures and accidents from occurring. A nondestructive and noninvasive geophysical method, ground penetrating radar (GPR), which utilizes electromagnetic waves, was employed in this study. Four field projects are presented in this study to demonstrate the application of electromagnetic waves for detection of voids and anomalies. Auguring and excavation were used to verify the suspicious areas that were located by the electromagnetic waves. Voids and different subsurface features, like rebar, geo-grid, and geo-textile, were successfully detected. A large negative peak that appears in the wave form is an indication of a dry void. Void sizes, ranging from a few centimeters to several meters, were successfully detected. Early identification of concealed subsurface voids under the roadway structure can prevent major failures from occurring. The methodologies presented in this study are applicable to many other projects.

Ultrafast Carbonyl Motion of the Photoactive Yellow Protein Chromophore Probed by Femtosecond Circular Dichroism

Motions of the trans-p-coumaric acid carbonyl group following the photoexcitation of the R52Q mutant of photoactive yellow protein (PYP) are investigated, for the first time, by ultrafast time-resolved circular dichroism (TRCD) spectroscopy. TRCD is monitored in the near-ultraviolet, over a time scale of 10 ps. Immediately after excitation, TRCD is found to exhibit a large negative peak, which decays within a few picoseconds. A quantitative analysis of the signals shows that, upon excitation, the carbonyl group undergoes a fast (≪0.8 ps) and unidirectional flipping motion in the excited state with an angle of ca. 17-53°. For the subset of proteins that do not enter the signaling photocycle, TRCD provides strong evidence that the carbonyl group moves back to its initial position, leading to the formation of a nonreactive ground-state intermediate of trans conformation. The initial ground state is then restored within ca. 3 ps. Comparative study of R52Q and wild-type PYP provides direct evidence that the absence of Arg52 has no effect on the conformational changes of the chromophore during those steps.

Thermoelectric Power Anomaly of PrTi2Al20and PrV2Al20with Non-Kramers Γ3Ground State

We investigated thermoelectric properties for PrTi2Al20 and PrV2Al20 below room temperature down to 0.13 K. A clear positive peak has been observed at 75 K in the thermoelectric power \(S\) for PrTi2Al20. Also for PrV2Al20, the similar \(S\) peak has been detected at 40 K. These peaks arise from the Kondo effect in the magnetic excited levels of the \(4f\)-electronic state under a cubic crystalline electric field (CEF). In addition, for PrTi2Al20, \(S\) takes a minimum with a negative sign at 10 K owing to the CEF effect, and shows an additional tiny negative hump below 2 K as a signature of quadrupole ordering. On the other hand, \(S\) for PrV2Al20 manifests a large negative peak at 3 K with the magnitude of 3 μV/K. This gives a large enhancement in absolute \(S\) divided by temperature \(T\), \(|S|/T\), approximately below 10 K on cooling. \(|S|/T\) reaches 4 μV/K2 at 0.2 K, which is larger than that in the zero-\(T\) limit for a heavy-electron compound CeRu2Si2. This observation strongly indicates that the heavy-electron state brought by the quadrupolar Kondo effect is realized in the non-Kramers Γ3 ground state of PrV2Al20.

Phase response properties of half-center oscillators

We examine the phase response properties of half-center oscillators (HCOs) that are modeled by a pair of Morris-Lecar-type neurons connected by strong fast inhibitory synapses. We find that the two basic mechanisms for half-center oscillations, "release" and "escape", give rise to strikingly different phase response curves (PRCs). Release-type HCOs are most sensitive to perturbations delivered to cells at times when they are about to transition from the active to the suppressed state, and PRCs are dominated by a large negative peak (phase delays) at corresponding phases. On the other hand, escape-type HCOs are most sensitive to perturbations delivered to cells at times when they are about to transition from the suppressed to the active state, and PRCs are dominated by a large positive peak (phase advances) at corresponding phases. By analyzing the phase space structure of Morris-Lecar-type HCO models with fast synaptic dynamics, we identify the dynamical mechanisms underlying the shapes of the PRCs. To demonstrate the significance of the different shapes of the PRCs for the release-type and escape-type HCOs, we link the shapes of the PRCs to the different frequency modulation properties of release-type and escape-type HCOs, and we show that the different shapes of the PRCs for the release-type and escape-type HCOs can lead to fundamentally different phase-locking dynamics.

Optically active dithiocarbamato Fe(II)–NO complex and its application for the NO detection

The presence of NO can be detected by circular dichroism (CD) spectroscopy, which is based on an asymmetric transformation in tris(dithiocarbamato)iron(II) complex. The complex [Fe(S-proOHdtc)3]4− {S-proOHdtc2− = 1-dithiocarboxyl-4-hydroxy-S-proline(2−)} in methanol shows a large negative CD peak at 600nm. It suggests that, in the epimerization equilibrium between Δ(S,S,S) and Λ(S,S,S), the Δ(S,S,S) complex is predominant species in methanol. The reaction of NO with Δ(S,S,S)-[Fe(S-proOHdtc)3]4− in methanol shows a decrease of the negative CD peak at 600nm. This phenomenon of the CD peak decrease shows the NO presence and it can be used for the detection of NO.

DETERMINING THE FOLDING DOMAIN OF LIPID FREE APOA-I IN SOLUTION BY MUTATION†

DETERMINING THE FOLDING DOMAIN OF LIPID FREE APOA-I IN SOLUTION BY MUTATION†

Steered molecular dynamics simulation of peeling a carbon nanotube on silicon substrate

Steered molecular dynamics (SMD) simulations are performed to study the peeling of a single wall carbon nanotube (8, 8) from a silicon surface at room temperature. There is a regular relationship between the average force probed by the ideal spring and the peeling distance when the carbon nanotube (CNT) is peeled from the silicon substrate. A large positive and a large negative peak value can be found in the peeling process. The average force for varying peeling velocities is investigated and their peak values are fitted to a function of the peeling velocity. The SMD simulation results show that there is a linear relationship between the peak value and the peeling velocity, which is consistent well with some biophysics peeling experiments. Compared with macromolecules, the CNT has a strong adhesion to the silicon surface. The influences of both radius and length as well as the defects of the CNT on the peeling process are also examined. The numerical results indicate that the peak value of the peeling force is independent of the length of the CNT but increases linearly with the radius of the CNT increasing. The peak value of the peeling force is almost independent of the 5-7-7-5 defect in the CNT but critically weakened by the radius defect of the CNT. The suggested method provides a theoretical prediction for the future experiment at atomic scale, which is helpful for the potential application of the CNT in the silicon-based microelectronics industry.

Recording of Spontaneous Activity in Cultured Superior Colliculus Slices Using Microelectrode Array

Retino-tectal projection is one of the pathways in visual information processing. During development, spontaneous electrical activity of superior colliculus (SC) probably plays an important role for proper network formation. In this study, SC slices were taken from new-born rats and cultured on microelectrode-array (MEA) substrates. Spontaneous activities of the cultured SC were recorded for four weeks. During the first week, most of the cultured SC slices generated sporadic spikes. These sporadic spikes gradually changed into periodic synchronized bursts. Spatially organized synchronized activity produced low frequency signals (local field potential: LFP). All of the test slices showed clear LFPs within three weeks. Large negative peaks were observed in the middle layer of the slices, while positive signals were obtained around the deep layers. Current source density (CSD) analysis revealed that middle layers acted as a current source and surface and deep layers were the sinks. These results suggested that layered structures of SC were well-maintained under the culture conditions and the cells in the middle layers played dominant roles in generating these periodic synchronized spontaneous activities.

EEG latency analysis for hemispheric lateralisation in Landau–Kleffner syndrome

Objective To determine the reliability of latency analysis in lateralising the origin of epileptiform discharges in pre-surgical assessment of Landau–Kleffner syndrome (LKS). Methods A computer aided-method was developed to identify leading regions and measure inter-hemispheric latencies before and after averaging discharges. Scalp and intracranial EEG recordings were studied from seven patients undergoing surgical treatment. The laterality suggested by latency analysis was compared with that suggested by pharmacological tests. Results Latency analysis of bilateral discharges showed a consistent leading hemisphere. The earliest low-amplitude deflections were located in temporal regions in all patients. Contralateral low-amplitude deflections, and ipsilateral and contralateral earliest large negative peaks were recorded in temporal and less frequently in parasagittal regions. Presurgical inter-hemispheric latencies ranged between 8 and 48 ms for the deflections and between 4 and 30 ms for the peaks. The leading hemisphere identified by latency analysis of the earliest low-amplitude deflections coincided with that suggested by pharmacological tests in all 7 patients, whereas latency of later components coincided in 6. Conclusions Latency analysis appears to be a reliable method to estimate the hemisphere driving bilateral discharges in LKS. Significance It can be carried out non-invasively and could be used to confirm, and eventually replace, results from pharmacological tests.

First observation of natural circular dichroism spectra in the extreme ultraviolet region using a polarizing undulator-based optical system and its polarization characteristics

Natural circular dichroism (CD) spectra in the extreme ultraviolet (EUV) region down to a wavelength of 80 nm have been observed for the first time, using an alanine thin film deposited on sodium salicylate coated glass as a sample. Calibrated EUV-CD spectra of L-alanine exhibited a large negative peak at around 120 nm and a positive CD signal below 90 nm, which were roughly predicted by theoretical calculations. A CD measurement system with an Onuki-type polarizing undulator was used to obtain the EUV-CD spectra. This CD system, the development of which took five years, can be used to observe even weak natural CD spectra. The polarization characteristics of this system were also evaluated in order to calibrate the recorded CD spectra.