Envelope Width Research Articles

On the Three-dimensional Structure of Local Molecular Clouds

Abstract We leverage the 1 pc spatial resolution of the Leike et al. three-dimensional (3D) dust map to characterize the 3D structure of nearby molecular clouds (d ≲ 400 pc). We start by “skeletonizing” the clouds in 3D volume density space to determine their “spines,” which we project on the sky to constrain cloud distances with ≈1% uncertainty. For each cloud, we determine an average radial volume density profile around its 3D spine and fit the profiles using Gaussian and Plummer functions. The radial volume density profiles are well described by a two-component Gaussian function, consistent with clouds having broad, lower-density outer envelopes and narrow, higher-density inner layers. The ratio of the outer to inner envelope widths is ≈3:1. We hypothesize that these two components may be tracing a transition between atomic and diffuse molecular gas or between the unstable and cold neutral medium. Plummer-like models can also provide a good fit, with molecular clouds exhibiting shallow power-law wings with density, n, falling off like n −2 at large radii. Using Bayesian model selection, we find that parameterizing the clouds’ profiles using a single Gaussian is disfavored. We compare our results with two-dimensional dust extinction maps, finding that the 3D dust recovers the total cloud mass from integrated approaches with fidelity, deviating only at higher levels of extinction (A V ≳ 2–3 mag). The 3D cloud structure described here will enable comparisons with synthetic clouds generated in simulations, offering unprecedented insight into the origins and fates of molecular clouds in the interstellar medium.

Influence of aging and increased blood pressure on oscillometric cuff pressure waveform characteristics.

The oscillometric blood pressure (BP) measurement technique estimates BPs from analyzing the envelop of oscillometric cuff pressure waveform. The oscillometric waveform envelope shape is associated with physiological changes and influences BP measurement accuracy. The aim of this study was to comprehensively quantify BP- and age-related changes of oscillometric waveform envelope characteristics. Manual systolic and diastolic BPs were measured from 472 patients (219 female, 253 male), and the cuff pressure were digitally recorded during linear cuff deflation that was used to derive oscillometric waveform envelopes. All patients were divided into different categories according to their BP level and age. The envelope width in high-pressure region (above mean arterial pressure, MAP) and low-pressure region (below MAP) were compared between different BP and age categories to qualify their changes with increased BP and aging. The envelop widths increased significantly with increased BPs (P < 0.001 between optimal, normotensive and hypertensive groups) and aging (P < 0.001 for >50 years old group in comparison with younger groups). The envelope widths in high-pressure region were significantly larger than in low-pressure region in normal and hypertensive categories (all P < 0.05) and elderly patients aged over 60 years (all P < 0.001), and the envelope width ratios between them increased with increased BP and aging. This study has concluded an asymmetrical oscillometric waveform envelope in normotensive and hypertensive categories, as well as in elderly group (aged over 60 years), and their asymmetrical features were significantly more obvious with increased BP and aging.

Multimode oscillation Q-switched mode-locking fiber laser based on gain equalized few-mode Er-doped fiber

We propose and demonstrate experimentally multimode Q-switched mode-locking (QML) fiber laser signal generation based on a long few-mode Er-doped fiber (FM-EDF). The erbium-doped profile of the fiber has been optimized to equalize the modal gain. The fiber supporting six modes has a total length of 5.5 m, a part of the fiber is used as a gain medium, and the unpumped part of the fiber is used as a saturable absorber. Multimode oscillation lasers in the state of the continuous wave laser operation, Q-switching, and QML state pulse laser operation were observed and measured at different pump powers by adjusting the polarization controller. A 1570-nm multimode QML pulse train was obtained, when the pump power was about 2.4 W. The width of the Q-switched envelope was 19 μs, and the repetition rate was 17.4 kHz. The stable mode-locked pulses repetition rate in Q-switched envelopes was 13.18 MHz. These temporal pulses can also be observed under the case of partly blocking the beam profile, and the part of the spectral signal gradually disappeared. The mode number in the laser was checked by a homemade mode selection photonic lantern. The results showed that the fiber laser had multimode oscillation, and the modes in generated signal were ≥5. The multiple transverse modes of the generated lasers are all in QML state at the same time. To the best of our knowledge, this is the first experimental demonstration of a multimode QML fiber laser using a long FM-EDF.

Lower Extremity Girth Does Not Predict Complications in TKA

BackgroundObese patients have increased complications after total knee arthroplasty (TKA). A body mass index (BMI) cutoff of 40 is frequently used to determine eligibility for TKA. Patients with a BMI <40 and extremely large legs which may predispose them to complications are approved for surgery because they fall below this cutoff. Alternatively, patients with truncal obesity and a BMI >40 are accepted because they have thin legs. We sought to determine whether BMI or girth should be used to determine eligibility. Methods453 patients who underwent TKA were included. A lower extremity girth (LEG) ratio was calculated dividing the width of the soft tissue envelope by bone width on lateral radiographs. Receiver operator curves were generated to predict 90-day complications. ResultsThere was no difference in median LEG ratio between patients with or without a complication (P = .08). Receiver operator curves indicated that size of the soft tissue envelope had no utility in predicting complications. There was no correlation between LEG ratio and specific complications such as infection, malalignment, or wound complications. Using a LEG ratio threshold of 4.834, the sensitivity and specificity for predicting complications were 48% and 64%, respectively. The median BMI for patients with no complication was 32.3 and 35 for patients with a complication (P = .07). ConclusionComplications are not necessarily associated with size of the soft tissue envelope in TKA.Decisions concerning TKA should not be made solely on the size of a patient’s leg. Level of EvidenceLevel III (retrospective comparative study).

10 µJ noise-like pulse generated from all fiberized Tm-doped fiber oscillator and amplifier.

Herein, we presented a high energy noise-like (NL) pulse Tm-doped fiber laser (TDFL) system. Relying on the nonlinear amplifying loop mirror (NALM), stable noise-like pulses with coherence spike width of ∼317 fs and envelope width of ∼4.2 ns were obtained from an all polarization-maintaining fiberized oscillator at central wavelength of ∼1946.4 nm with 3 dB bandwidth of ∼24.9 nm. After the amplification in an all-fiberized TDF amplifier system, the maximum average output power of ∼32.8 W and pulse energy of ∼10.1 µJ were obtained, which represents the highest pulse energy of NL pulse at ∼2 µm, to the best of our knowledge. We believe that the high energy NL pulse source has the potential application in mid-infrared supercontinuum generation.

Q-Switched and Noise-Like Mode Locked Er-Doped Fiber Laser Based on Nb2AlC Saturable Absorber

Nb 2 AlC is a kind of ternary ceramic material whose special crystal structure makes it both the advantages of metal and ceramics. And it has good electrical conductivity and strong stability at room temperature. In this article, the saturable absorption of Nb 2 AlC based thin film have been investigated, showing that it has saturated light intensity of 0.21 MW/cm 2 and the modulation depth of 2.62%. Noise-like mode locked and Q-switched pulses output based on Nb 2 AlC thin film have been achieved in erbium-doped fiber laser cavity. The narrowest width of noise-like mode-locked pulses' envelope is 13 ns, the maximum single pulse energy is 1.5 nJ, and the full width at half-maximum (FWHM) of the narrowest coherent spike is 2.34 ps. The minimum pulse width of the Q-switched pulse is 8.6 μs and the maximum single pulse energy is 66 nJ. As far as we know, this is the first report of Nb 2 AlC's application in ultrafast optics.

Scattering and Attenuation Characteristics at Volcanoes Inferred From Envelope Widths of Natural and Active Seismic Sources

AbstractSeismic scattering and attenuation at volcanoes, thought to be strongest on the Earth, can be used to map volcanic feeding systems. We systematically analyzed high‐frequency (5–10 Hz) seismograms of volcano‐tectonic earthquakes at Galeras volcano (Colombia) and active sources at Kirishima, Unzen, Bandai, and Iwate volcanoes (Japan) to investigate their scattering and attenuation characteristics. The envelope widths estimated from these seismograms were compared with those calculated by Monte Carlo envelope simulations for 1D layered models parameterized by the scattering mean free path and the quality factor of medium attenuation for S waves. Our results indicated a surficial, highly heterogeneous, and attenuative layer up to around 1 km thickness at all studied volcanoes. The strongest heterogeneities at volcanoes thus exist in a thin surface layer, likely comprising unconsolidated and/or highly fractured materials. Using the space‐weighting function for diffusive wavefields, we mapped the residuals between observed envelope widths and those calculated with our estimated 1D models at Kirishima, Unzen, Bandai, and Iwate. These maps showed spatial distributions of the envelope‐width residuals were unique to each volcano and correlated with P wave velocity tomographic images. Areas of positive residuals correspond to low‐velocity anomalies and thus to heterogeneous, strongly scattering rocks, whereas areas of negative residuals correspond to high‐velocity anomalies and thus less heterogeneous volcanic or basement rocks. Our results demonstrate that envelope widths can improve the characterization of scattering and attenuation structures beneath volcanoes.

Noise-like pulses with an h-shape from a 2 μm semiconductor saturable-absorber mirror mode-locked fiber oscillator

We report on a novel type of h-shaped pulse with femtosecond substructures from a linear-cavity semiconductor saturable-absorber mirror mode-locked thulium-doped fiber laser. It yields a stable nanosecond h-shaped pulse-train with a pulse envelope width ranging from 880 ps to 1.41 ns with a typical substructure pulse duration around 440 fs. The obtained h-shaped pulse is a noise-like pulse with strong robustness to pump power changes and environmental perturbation. It can also operate in the harmonic mode-locking regime. The scheme makes the structure compact and stable, and can obtain a MHz repetition rate, which is advantageous for real-life applications

Mode-locked and Q-switched mode-locked fiber laser based on a ferroferric-oxide nanoparticles saturable absorber.

We demonstrated an ultrafast erbium-doped fiber laser (EDFL) based on ferroferric-oxide (Fe3O4) nanoparticles as a saturable absorber (SA). The investigated SA was based on magnetic fluid deposited on the end face of a fiber ferrule connector. When the SA was inserted into an EDFL cavity, a stable 2.93 ps mode-locked pulse can be achieved by adjusting the intra-cavity polarization controller. The pulse had a central wavelength of 1572.39 nm and a 3 dB bandwidth of 1.39 nm. We also obtained Q-switched mode-locked pulses at 1593.4 nm. The repetition frequency and the temporal width of the Q-switched pulse envelope varied with the pump power. When the pump power reached 225 mW, the maximum average output power and the pulse envelope energy were up to 4.51 mW and 235.5 nJ. To the best of our knowledge, this is the first time that mode-locked and Q-switched mode-locked pulses have been obtained in a fiber laser based on Fe3O4 nanoparticles.

Generation of Flat-Top Q-Switched Envelope Dissipative Soliton Resonance Pulse in Passively Mode-Locked Fiber Laser

We present demonstration of an erbium-doped fiber laser based on the nonlinear amplifying loop mirror mechanism, with a stable phenomenon of flat-top Q-switched mode-locked (FT-QML) dissipative soliton resonance (DSR) pulse, for the first time. In the experiment, we can observe both the flat-top Q-switched envelope and square-wave pulse by the peak power clamping effect inside the cavity. The characteristics of both continuous DSR pulse and flat-top Q-switched mode-locked square-wave are analyzed comprehensively. With the maximum pump power of 363 mW, single pulse energy in the FT-QML envelope can be up to 14 nJ as three times high as the one of continuous DSR. Essentially, the temporal width of the Q-switched mode-locked envelope can reach 4.6 μs with flat-top duration of 3.5 μs. The amplitude fluctuation of the sub-pulse inside the flat-top is stable at about 0.12% by using the formula of RMSE. Therefore, the laser can provide flat-top burst mode pulse sequence, and the pulse width can be controlled by tuning the pump power.

A Synchronously Self-Q-Switched and Self-Mode-Locked Fiber Laser with a Compound Resonator

We demonstrate a synchronously self-Q-switched and self-mode-locked output pulse fiber laser based on a linear compound resonator and an LD cladding-pumped Yb-doped double-clad fiber. A maximum average output power of 332.1 mW is achieved. We observe that the maximum pulse envelope width is 8 μs, and the pulse energy is 3.83 μJ for the self-Q-switched pulse envelope. At the same time, the achieved maximum pulse width is 37.8 ns and pulse energy is 17.61 nJ for the self-mode-locked pulse. We observe the pulse splitting of the self-Q-switched envelope as well and achieve 14 subpulse packets for L1 = 180 mm. There are 75 self-mode-locked pulses in single packets.

Calumenin-1 Interacts with Climp63 to Cooperatively Determine the Luminal Width and Distribution of Endoplasmic Reticulum Sheets.

SummaryThe ER is composed of distinct structures like tubules, matrices, and sheets, all of which are important for its various functions. However, how these distinct ER structures, especially the perinuclear ER sheets, are formed remains unclear. We report here that the ER membrane protein Climp63 and the ER luminal protein calumenin-1 (Calu1) collaboratively maintain ER sheet morphology. We show that the luminal length of Climp63 is positively correlated with the luminal width of ER sheets. Moreover, the lumen-only mutant of Climp63 dominant-negatively narrows the lumen of ER sheets, demonstrating that Climp63 acts as an ER luminal bridge. We also reveal that Calu1 specifically interacts with Climp63 and antagonizes Climp63 in terms of both ER sheet distribution and luminal width. Together, our data provide insight into how the structure of ER sheets is maintained and regulated.

A model for the influence of plastic deformation on Magnetic Barkhausen Noise in carbon steel

In this work, a model for the influence of tensile plastic deformation on Barkhausen Noise is proposed. This model is based on a previous model that allows to explain the influence of magnetizing parameters, applied field frequency and electric conductivity on Barkhausen Noise. In order to analyze the effects of plastic deformation on Barkhausen Noise, the model was modified to include the presence of dislocations tangles, the change of the mean coercivity and the change of local coercive field standard deviation as a function of the tensile plastic deformation. The simulations of the model are compared with Barkhausen signal, obtained from three different steel subjected to six levels of plastic deformation. The experimental results show that the amplitude of Barkhausen signal decreases, the main peak field increases and the signal envelope width increases with the increase of tensile plastic deformation. The simulated Barkhausen envelope shows the same behavior as the experimental envelope considering that the number of dislocation tangles increase, the mean value of the local coercive field increases and the standard deviation of the local coercive field increases with the increase of plastic deformation.

Field measurement of nonlinear changes to large gravity wave groups

The dynamics of large gravity waves are known to be modified from the linear model by nonlinear physics. In this paper we analyse Eulerian surface elevation time histories measured from two sites, Lake George (Australia) and the North Sea, to examine how weak nonlinearity has modified the shape of extreme wave groups relative to linear theory. We analyse the asymmetry of the extreme wave groups and find that, on average, the wave in front of an extreme wave is smaller than the wave following it. We also observe a contraction in the envelope width of the wave group relative to linear theory. The departures from linear theory are strongly correlated with the steepness of the underlying sea state and are generally consistent with theoretical expectations, providing strong evidence that such nonlinear phenomena arise in naturally occurring water waves.

Can quantum fluctuation enhance diffusion in a corrugated plane?

By means of the effective diffusion coefficient of a particle be determined by the envelope width of its spatial distribution, we study the influence of quantum fluctuation upon the diffusion of the particle in a corrugated plane. The model allows for a power-spectrum quantum noise and a biased periodic potential. A comprehensive method is developed, which includes three techniques: the fast Fourier transform is used to generate quantum colored noise, solving numerically the generalized Langevin equation by the Monte-Carlo method, and the quantum-averaging correction of nonlinear force is taken account into the calculation. The prominent result is demonstrated that the effective diffusion coefficient of the particle driven by quantum thermal noise is less than the classical one when the biased force arrives at its critical value, where the local minima of potential vanish just. Moreover, the time index of the position variance of a super-Ohmic damping particle varies with the biased force. This is due to a fact that the motion of particle exhibits mixing of the locked and running states in such potential, however, the quantum fluctuation increases mobility but decreases the probability of the particle in a locked state.

What is the maximum differential group delay achievable by a space-time wave packet in free space?

The group velocity of 'space-time' wave packets - propagation-invariant pulsed beams endowed with tight spatio-temporal spectral correlations - can take on arbitrary values in free space. Here we investigate theoretically and experimentally the maximum achievable group delay that realistic finite-energy space-time wave packets can achieve with respect to a reference pulse traveling at the speed of light. We find that this delay is determined solely by the spectral uncertainty in the association between the spatial frequencies and wavelengths underlying the wave packet spatio-temporal spectrum - and not by the beam size, bandwidth, or pulse width. We show experimentally that the propagation of space-time wave packets is delimited by a spectral-uncertainty-induced 'pilot envelope' that travels at a group velocity equal to the speed of light in vacuum. Temporal walk-off between the space-time wave packet and the pilot envelope limits the maximum achievable differential group delay to the width of the pilot envelope. Within this pilot envelope the space-time wave packet can locally travel at an arbitrary group velocity and yet not violate relativistic causality because the leading or trailing edge of superluminal and subluminal space-time wave packets, respectively, are suppressed once they reach the envelope edge. Using pulses of width ∼ 4 ps and a spectral uncertainty of ∼ 20 pm, we measure maximum differential group delays of approximately ±150 ps, which exceed previously reported measurements by at least three orders of magnitude.

Reaction norm analysis reveals rapid shifts toward delayed maturation in harvested Lake Erie yellow perch (Perca flavescens).

Harvested marine fish stocks often show a rapid and substantial decline in the age and size at maturation. Such changes can arise from multiple processes including fisheries‐induced evolution, phenotypic plasticity, and responses to environmental factors other than harvest. The relative importance of these processes could differ systematically between marine and freshwater systems. We tested for temporal shifts in the mean and within‐cohort variability of age‐ and size‐based maturation probabilities of female yellow perch (Perca flavescens Mitchill) from four management units (MUs) in Lake Erie. Lake Erie yellow perch have been commercially harvested for more than a century, and age and size at maturation have varied since sampling began in the 1980s. Our analysis compared probabilistic maturation reaction norms (PMRNs) for cohorts when abundance was lower and harvest higher (1993–1998) to cohorts when abundance was higher and harvest lower (2005–2010). PMRNs have been used in previous studies to detect signs of evolutionary change in response to harvest. Maturation size threshold increased between the early and late cohorts, and the increases were statistically significant for the youngest age in the western MU1 and for older ages in the eastern MU3. Maturation envelope widths, a measure of the variability in maturation among individuals in a cohort, also increased between early and late cohorts in the western MUs where harvest was highest. The highest rates of change in size at maturation for a given age were as large or larger than rates reported for harvested marine fishes where declines in age and size at maturation have been observed. Contrary to the general observation of earlier maturation evolving in harvested stocks, female yellow perch in Lake Erie may be rapidly evolving delayed maturation since harvest was relaxed in the late 1990s, providing a rare example of possible evolutionary recovery.

Envelope Widths of Volcano‐Seismic Events and Seismic Scattering Characteristics Beneath Volcanoes

AbstractVolcanoes produce highly scattered seismic wavefields, which are characterized by the scattering mean free path (l0) and the quality factor of medium attenuation for S waves (Qi). Previous studies have estimated scattering mean free paths at various volcanoes to be around 100–1,000 m, but their depth distributions remain to be determined. We estimated one‐dimensional l0 and Qi structures using the envelope widths of volcano‐seismic events at Taal (Philippines) and at Nevado del Ruiz (Colombia) in a high‐frequency band (5–10 Hz). We performed Monte Carlo envelope simulations in various one‐dimensional models, and compared the simulated and observed envelope widths. Our results indicate that a highly heterogeneous (l0 = 1,000 m) and attenuative (Qi = 100) surface layer exists to a depth of 1 km, below which l0 and Qi are comparable to those in the normal crust. The surface layer may consist of unconsolidated materials with hydrothermal fluids and/or altered clay minerals, which cause strong scattering and attenuation effects beneath these volcanoes. Our results suggest that strong heterogeneities observed at volcanoes exist only in a thin surface layer.

Investigation on the enhancement phenomenon of biased-diffusion in periodic potential

The noise-induced diffusion of a particle in a two-dimensional (2D) periodic potential is studied by simulating a general-damping Langevin equation, where the particle is subjected especially to both a constant force along a direction and an Ornstein–Uhlenbeck (OU) colored noise. The effective diffusion coefficient is determined by the envelope width of the spatial distribution of the particle. The enhancement phenomenon of diffusion from fluctuation-controlled one to bias-plus-correlation-controlled one is investigated. A scheme of local harmonic approximation for the OU colored noise is used to analyze our numerical findings, showing that the correlation effect of noise is beneficial to biased diffusion. Moreover, the dimensional effect is discussed by comparing the 1D and 2D treatments. The prominent result is demonstrated in the tilted periodic potential, namely, the motion of particle exhibits two modes: the locked state and the running state, thus the effective diffusion coefficient can be enhanced if the probability of a particle locked in local minima of the potential increases or the space distribution of the particle can be disintegrated into many small pieces.

Passively Q-switched and mode-locked YVO4/Nd:YVO4/Nd:YVO4 laser based on a MoS2 saturable absorber at 1342.5 nm

We demonstrate a passively Q-switched and mode-locked (QML) laser with both YVO4/Nd:YVO4/Nd:YVO4 crystal and MoS2 saturable absorber (MoS2-SA) at ∼1342.5 nm. The MoS2-SA is fabricated with the liquid phase exfoliation (LPE) method. By inserting MoS2-SA into a Z-type resonator, we obtain a QML laser operation with the maximum average output power of 600 mW, the shortest envelope duration of 800 ns and the highest repetition rate of 98 kHz at 9 W. The energy of a Q-switched envelope is estimated to be about 6.12 μJ and the peak power is 39 W. The obtained envelope width and repetition rate are both superior to the results obtained from QML lasers with V3+:YAG and graphene at 1.34 μm. So far as we know, it is the first report on the QML laser at 1.34 μm with MoS2-SA, which proves the MoS2-SA is a good candidate for solid-state QML laser at 1.34 μm.