Apparent Propagation Research Articles

Where is "Out There"?

Experimental evidence and verified individual accounts show that visual and other types of information from distant minds and environments can enter the conscious as well as the unconscious mind of an individual and can measurably affect brain and body function. The information appears to pass through every physical obstacle and does not degrade in quality with increasing distance in the path between source and receiver. No signal can be detected with current physical instrumentation. What is the medium in which this “psi-encoded information” appears to propagate? What is its format? What is its lifetime? Selected examples of apparent psi information propagation from differing types of sources are presented and analyzed. In order to account for the behavior observed in the examples, a worldview developed in the Advaitic thought tradition is considered, in which a non-physical domain interacts with the physical domain of matter-energy and spacetime. A main currency of the non-physical domain is postulated to be psi-encoded information. It is concluded that this information does not propagate through space. Other characteristics of the non-physical domain and its content are inferred from the examples. They provide a framework in which the nature of psi-encoded information and its processing may be further explored.

Propagation velocity measurements of substrate phonon bursts using MKIDs for superconducting circuits

High-energy bursts in superconducting quantum circuits from various radiation sources have recently become a practical concern due to induced errors and their propagation in the chip. The speed and distance of these disturbances have practical implications. We used a linear array of multiplexed MKIDs on a single silicon chip to measure the propagation velocity of a localized high-energy burst, introduced by driving a normal metal-insulator-superconductor (NIS) junction. We observed a reduction in the apparent propagation velocity with NIS power, which is due to the combined effect of reduced phonon flux with distance and the existence of a minimum detectable QP density in the MKIDs. A simple theoretical model is fitted to extract the longitudinal phonon velocity in the substrate and the conversion efficiency of phonons to QPs in the superconductor.

Hydrogen Bond Donors in the Catalytic Pocket: The Case of the Ring-Opening Polymerization of Cyclic Esters Catalyzed by an Amino-Propoxide Aluminum Complex.

A new aluminum complex (NSO)AlMe2 featuring a hydrogen bond donor on the ligand backbone has been synthesized via the reaction of AlMe3 with 1-((2-(isopropylamino)phenyl)thio)propan-2-ol (NSO-H) and spectroscopically characterized. In the complex, the aluminum atom is in a distorted tetrahedral coordination sphere determined by the anionic oxygen and neutral nitrogen atoms of the ligand and by the two carbon atoms of the alkyl groups. After proper activation, the complex (NSO)AlMe2 was able to promote the ring-opening polymerization of L-, rac-lactide, ε-caprolactone and rac-β-butyrolactone. The polymerization of rac-lactide was faster than that of L-lactide: in a toluene solution at 80 °C, the high monomer conversion of 100 equivalents was achieved in 1.5 h, reaching a turnover frequency of 63 molLA·molAl-1·h-1. The experimental molecular weights of the obtained polymers were close to those calculated, assuming the growth of one polymer chain for one added alcohol equivalent and the polydispersity indexes were monomodal and narrow. The kinetic investigation of the polymerization led to the determination of the apparent propagation constants and the Gibbs free energies of activation for the reaction; the terminal groups of the polymers were also identified. The complex (NSO)AlMe2 was active in harsh conditions such as at a very low concentration or in the melt using technical-grade rac-lactide. A relatively high level of activity was observed in the ring-opening polymerization of ε-caprolactone and rac-β-butyrolactone. DFT calculations were performed and revealed the central role of the NH function of the coordinated ligand. Acting as a hydrogen bond donor, it docks the monomer in the proximity of the metal center and activates it toward the nucleophilic attack of the growing polymer chain.

Kelvin-Helmholtz instability and heating in oscillating loops perturbed by power-law transverse wave drivers

Context. Instabilities in oscillating loops are believed to be essential for dissipating the wave energy and heating the solar coronal plasma. Aims. Our aim is to study the development of the Kelvin-Helmholtz (KH) instability in an oscillating loop that is driven by random footpoint motions. Methods. Using the PLUTO code, we performed 3D simulations of a straight gravitationally stratified flux tube. The loop footpoints are embedded in chromospheric plasma, in the presence of thermal conduction and an artificially broadened transition region. Using drivers with a power-law spectrum, one with a red noise spectrum and one with the low-frequency part subtracted, we excited standing oscillations and the KH instability in our loops, after one-and-a-half periods of the oscillation. Results. We see that our broadband drivers lead to fully deformed, turbulent loop cross-sections over the entire coronal part of the loop due to the spatially extended KH instability. The low RMS velocity of our driver without the low-frequency components supports the working hypothesis that the KH instability can easily manifest in oscillating coronal loops. We report for the first time in driven transverse oscillations of loops the apparent propagation of density perturbations due to the onset of the KH instability, from the apex towards the footpoints. Both drivers input sufficient energy to drive enthalpy and mass flux fluctuations along the loop, while also causing heating near the driven footpoint of the oscillating loop, which becomes more prominent when a low-frequency component is included in the velocity driver. Finally, our power-law driver with the low-frequency component provides a RMS input Poynting flux of the same order as the radiative losses of the quiet-Sun corona, giving us promising prospects for the contribution of decayless oscillations in coronal heating.

A model of umbral oscillations inherited from subphotospheric fast-body modes

Recently, complex horizontal patterns of umbral oscillations have been reported, but their physical nature and origin are still not fully understood. Here we show that the two-dimensional patterns of umbral oscillations of slow waves are inherited from the subphotospheric fast-body modes. Using a simple analytic model, we successfully reproduced the temporal evolution of oscillation patterns with a finite number of fast-body modes. In this model, the radial apparent propagation of the pattern is associated with the appropriate combination of the amplitudes in radial modes. We also find that the oscillation patterns are dependent on the oscillation period. This result indicates that there is a cutoff radial mode, which is a unique characteristic of the model of fast-body modes. In principle, both internal and external sources can excite these fast-body modes and produce horizontal patterns of umbral oscillations.

Superluminal propagation along the brane in space with extra dimensions

We demonstrate that a model with extra dimensions formulated in Csaki et al. (Phys Rev D 62:045015, 2000), which fatefully reproduces Friedmann–Robertson–Walker (FRW) equations on the brane, allows for an apparent superluminal propagation of massless signals. Namely, a massive brane curves the spacetime and affects the trajectory of a signal in a way that allows a signal sent from the brane through the bulk to arrive (upon returning) to a distant point on the brane faster than the light can propagate along the brane. In particular, the signal sent along the brane suffers a greater gravitational time delay than the bulk signal due to the presence of matter on the brane. While the bulk signal never moves with the speed greater than the speed of light in its own locality, this effect still enables one to send signals faster than light from the brane observer’s perspective. For example, this effect might be used to resolve the cosmological horizon problem. In addition, one of the striking observational signatures would be arrival of the same gravitational wave signal at two different times, where the first signals arrives before its electromagnetic counterpart. We used GW170104 gravitational wave event to impose a strong limit on the model with extra dimensions in question.

Influence of the reaction conditions on the Ziegler-Natta catalyzed ethylene polymerization: Kinetics and properties of the resulting polymers

This work conducts an investigation into how the polymerization conditions affect the kinetics of ethylene homopolymerization and the properties of the final polyethylene using a commercially available Ziegler-Natta catalyst with the formula TiCl4/MgCl2. By employing a mathematical model, we estimated the apparent propagation (kp), activation (ka), and deactivation (kd) rate constants under different reaction conditions, including cocatalyst and catalyst concentration, hydrogen/ethylene ratio, and polymerization temperature. Additionally, we examined the properties of the resulting polyethylene products, such as particle size, molecular weight (Mw), melting temperature, and % crystallinity. We found that the trend of polymer particle size was similar to that of the propagation rate constant under the employed polymerization conditions. Our results indicated that parameters enhancing the polymerization rate also increased kp and reduced crystallinity. The quantitative rate constants and polymer characteristics reported in this study provide valuable insights for industrial polyethylene manufacturers, allowing them to fine-tune plant operation conditions and achieve precise control over polymer particle properties. Furthermore, Density Functional Theory (DFT) calculations provided additional insights into the polymerization process, particularly regarding the role of hydrogen as a chain transfer agent and the fundamental significance of MgCl2, emphasizing the need for a minimal-dimensional model to evaluate this role.

The role of 2‐iminopyrrolyl copper(I) complexes in the Reversible‐Deactivation Radical Polymerization of methyl methacrylate

The role of 2‐iminopyrrolyl copper(I) complexes in the Reversible‐Deactivation Radical Polymerization (RDRP) of methyl methacrylate (MMA) is described. Mononuclear 2‐iminopyrrolyl copper(I) complexes [Cu{κ2N,N′‐NC4H3‐2‐C(H)=NR′}Ln] 1–7 (R′ = C6H5, Ln = (PPh3)2 (1); R′ = 2,6‐Me2C6H3, Ln = (PPh3)2 (2); R′ = 2,6‐iPr2C6H3, Ln = (PPh3)2 (3); R′ = 4‐NMe2C6H4, Ln = (PPh3)2 (4); R′ = CH3, Ln = (PPh3)2 (5); R′ = CH3, Ln = (PMe3)2 (6); R′ = CH3, Ln = PiPr3 (7)) were synthesized by the reaction of the in situ prepared sodium salts of precursors HL1–5 with [Cu(NCMe)4]BF4 with the respective phosphines. In their absence, the binuclear complex [Cu{κN,κN'‐NC4H3‐2‐C(H)=NCH3}]2 8 was formed instead, which, when treated with one equivalent of PR3 yielded the binuclear complexes [Cu2{κN,κN'‐NC4H3‐2‐C(H)=NCH3}2PR3] 9 (R = Ph) and 10 (R = Me).All complexes, except 8, were active in the RDRP of MMA using the initiator tert‐butyl‐α‐bromoisobutyrate (tBiB‐Br), achieving apparent propagation kinetic constants (kp') in the range of 0.5–7.5 × 10−5 s−1, at 90 °C and with a [MMA]0:[complex]0:[tBiB‐Br]0 ratio of 500:1:1. All reactions yielded poly (methyl methacrylate)s with molecular weights ( ) and dispersities higher than expected for Controlled Radical Polymerization processes. Complex 7 achieved the best results, with values being only 1.2‐fold higher than theoretically expected. Experimental and density functional theory (DFT) studies suggest that this system operates via Atom Transfer Radical Polymerization/Organometallic Mediated Radical Polymerization (ATRP/OMRP) mechanisms interplay.

Mechanistic study on hydrogen effects in propylene polymerization with MgCl2-supported Ziegler-Natta catalysts: New evidences from active center counting and reaction kinetics

Propylene polymerizations catalyzed by MgCl2/Di/TiCl4-AlEt3/siloxane in the absence and presence of hydrogen were studied by determining the time-dependent changes of catalytic activity, number of active centers and active center distribution. Three types of active centers with high, medium and very low stereoselectivity were differentiated by fractionating the polymer into three parts. Chain propagation rate constant of each type of active centers was estimated by linear fitting/extrapolating the time-dependent change of apparent propagation rate constant. The centers with high (Ci*), medium (Cm*) and low (Ca*) stereoselectivity responded to addition of hydrogen differently. Adding hydrogen caused marked increase of Ci*, but its propagation rate constant (kpi) was evidently reduced. In contrast, numbers of Cm* and Ca* were only slightly affected, but their propagation rate constants were evidently enhanced by hydrogen. The different hydrogen responses of Ci* with those of Cm* and Ca* were explained by two kinds of hydrogen activation mechanisms.

Effects of Internal Electron Donor on Distribution and Reactivity of Active Centers in Ethylene/1‐Hexene Copolymerization with MgCl2‐Supported Ziegler‐Natta Catalyst

AbstractEthylene/1‐hexene copolymerization with two MgCl2‐supported Ziegler‐Natta catalysts containing no internal electron donor or diethylphthalate (DEP) is conducted for different polymerization time . Effects of DEP on active center distribution are studied by fractionating each copolymer sample into boiling n‐heptane soluble (C7‐sol) and insoluble (C7‐ins) fractions, and counting the number of active centers in the copolymer fractions . The main effect of introducing DEP in the catalyst are reduction in the Ti content and significant increase in the proportion of active centers producing C7‐ins fraction. The propagation rate constants of ethylene insertion (kpE) and 1‐hexene insertion (kpH) are respectively estimated by linear fitting/extrapolating the change of apparent propagation rate constants (kpi)a with polymer yield according to a simplified multi‐grain particle model. In both catalysts, kpE in the C7‐ins fraction is 9–12 times larger than that in the C7‐sol fraction, and kpH in the C7‐ins fraction is 3–4 times larger than that in the C7‐sol fraction. The two groups of active centers have distinctly different catalytic properties. Introducing DEP reduced the kpE and kpH values and the extent of diffusion limitation . In summary, addition of electron donor in MgCl2‐supported Z‐N catalyst significantly changed the active center distribution and catalytic properties of its two groups of active centers.

Effects of aquitard windows on groundwater fluctuations within a coastal leaky aquifer system: An analytical and experimental study

Low-permeability aquitards are important sedimentary units that protect the underlying confined aquifers from contamination by seawater and anthropogenic sources in coastal leaky aquifer systems. Therefore, the integrity of the aquitard is of crucial importance. However, the aquitard integrity may be vulnerable to horizontal heterogeneities in the form of aquitard windows. In this study, an innovative analytical model was developed to describe groundwater flow in a coastal leaky aquifer system with horizontal heterogeneities in hydraulic properties of either the aquitard or the confined aquifer. Consequently, the effects of aquitard windows, which manifest as horizontally local heterogeneities in hydraulic conductivity and/or specific storage, on the tidal wave propagation can be considered in the analysis. Analytical solutions were derived for tidal-head or constant-flux inland boundary conditions. The derivation process avoided previous methodologies that involved the assembly of large-size matrices. The newly developed analytical model can cover multiple existing analytical models that are associated with the assumptions of homogeneity in hydraulic properties of the aquifer and the aquitard, infinite horizontal extent of the coastal leaky aquifer system, impermeability of the aquitard, or ignorance of aquitard storativity. Analytical investigations revealed that high-permeability aquitard windows acting as preferential-flow conduits tended to dampen the tide-induced head propagation within the underlying confined aquifer. Moreover, an aquitard with a higher storativity (but the same permeability) and of considerable size can result in an apparent propagation bias. The newly developed analytical model in this study was further corroborated through sandbox experiments. Both piezometer measurements and parameter estimates indicated the non-negligible effects of high-permeability aquitard windows on the tidal wave propagation. The sandbox investigation also highlighted the importance of geostatistical inverse modeling in characterizing local heterogeneities within the confined aquifer and in detecting the location and size of aquitard windows, when measurement data of tide-induced aquifer head fluctuations were provided.

Estimation of the chain propagation rate constants of propylene polymerization and ethylene‐1‐hexene copolymerization catalyzed with MgCl2‐supported Ziegler–Natta catalysts

AbstractIn olefin polymerization with MgCl2‐supported Ziegler–Natta (Z–N) catalysts, the apparent propagation rate constant (kp)a calculated by Rp = (kp)a [C*] CMe (CMe is equilibrium monomer concentration in the reaction system) declines with reaction time for gradually developed monomer diffusion limitation in the polymer/catalyst particles. In this work, a simplified multi‐grain particle model was proposed to build correlation between (kp)a and other kinetic parameters that can be determined experimentally. Rate profiles of propylene polymerization and ethylene‐1‐hexene copolymerization by three MgCl2‐supported Z–N catalysts were determined, and the (kp)a data was calculated using [C*] determined by quench‐labelling the propagation chains with acyl chloride. Decline of (kp)a in each polymerization process was precisely fitted by the linear correlation between lg(kp)a and [(ρcatmp)/(ρpmcat) + 1]1/3 developed on the particle model. Real propagation rate constant (kp) was estimated by extrapolating the fitting line to the starting point of polymerization, where no concentration gradient exists. According to the particle model, the slope of the lg(kp)a versus [(ρcatmp)/(ρpmcat) + 1]1/3 line (lgd) represents the degree of monomer diffusion limitation. Variations of parameter d found in the studied reaction systems can be reasonably explained based on the knowledge of olefin diffusion in the polymer phase.

Comparison of Madden-Julian oscillation in three super El Niño events

This paper investigated the characteristics of Madden-Julian Oscillation (MJO) in three super El Niño events (i.e., 1982/83, 1997/98 and 2015/16 El Niño events) based on reanalysis data. MJO with apparent eastward propagation can be observed during the developing stages of these three super El Niño events. Enhanced MJO zonal wind was observed over the western Pacific, especially in 1997/98 and 2015/16 El Niño events, which is mainly attributed to the effects of tropical background circulation and extratropical anomalous circulation. During the mature stages of 1982/83 and 1997/98 El Niño events, MJO with noticeable eastward propagation cannot be observed, and the MJO zonal wind amplitude at 850 hPa was weakened (enhanced) over the Indian Ocean and western Pacific (central and eastern Pacific). However, MJO zonal wind amplitude over the central and eastern Pacific was enhanced and the prominent eastward propagation was also found in the mature stage of 2015/16 El Niño. The eastward propagation of MJO was also observed during the decaying stages of the three super El Niño events, but its intensity was weaker compared with the developing and mature stages. The abnormal activity of MJO during the mature and decaying stages may be closely related to the characteristics in circulation and moisture anomalies caused by El Niño and the seasonal cycle of circulation and moisture. In addition, this study found that the RMM index and MJO zonal wind amplitude may lead to contradictory results in identifying the characteristics of MJO activity, especially during the developing and decaying stages.

Observational and numerical characterization of a recurrent arc-shaped front propagating along a coronal fan

Context. Recurrent, arc-shaped intensity disturbances were detected by extreme-ultraviolet channels in an active region. The fronts were observed to propagate along a coronal loop bundle rooted in a small area within a sunspot umbra. Previous works have linked these intensity disturbances to slow magnetoacoustic waves that propagate from the lower atmosphere to the corona along the magnetic field. Aims. The slow magnetoacoustic waves propagate at the local cusp speed, which is equivalent to the sound speed in a low-β-regime plasma. However, the measured propagation speeds from the intensity images are usually smaller as they are subject to projection effects due to the inclination of the magnetic field with respect to the line of sight. We aim to understand the effect of projection by comparing observed speeds with those from a numerical model. Methods. Using multi-wavelength data, we determined the periods present in the observations at different heights of the solar atmosphere through Fourier analysis. We calculated the plane-of-sky speeds along one of the loops from the cross-correlation time-lags obtained as a function of distance along the loop. We performed a 2D ideal magnetohydrodynamic simulation of an active region embedded in a stratified atmosphere. We drove slow waves from the photosphere with a three-minute periodicity. Synthetic time–distance maps were generated from the forward-modelled intensities in coronal wavelengths and the projected propagation speeds were calculated. Results. The intensity disturbances show a dominant period between 2 and 3 min at different heights of the atmosphere. The apparent propagation speeds calculated for coronal channels exhibit an accelerated pattern with values increasing from 40 to 120 km s−1 as the distance along the loop rises. The propagation speeds obtained from the synthetic time–distance maps also exhibit accelerated profiles within a similar range of speeds. Conclusions. We conclude that the accelerated propagation in our observations is due to the projection effect.

Near‐Real‐Time Analysis of the Ionospheric Response to the 15 January 2022 Hunga Tonga‐Hunga Ha'apai Volcanic Eruption

AbstractWe present a near‐real‐time (NRT) scenario of analysis of ionospheric response to the 15 January 2022 Hunga Tonga‐Hunga Ha'apai eruption by using Global Navigation Satellite Systems data in the near‐field (in the vicinity of the volcano), and in the far‐field (Japan, North America, and South America). We introduce a new method to determine instantaneous velocities using an interferometric approach and using the time derivative of the total electron content (TEC). Moreover, for the first time, we propose a novel method that automatically estimates the apparent propagation velocity of ionospheric disturbances from NRT travel‐time diagrams. By using our new methods, we analyzed the dynamics of co‐volcanic ionospheric disturbances generated by the Hunga‐Tonga eruption, and we estimated the first propagation velocity in the near‐field to be ∼800–950 m/s, subsequently decreasing to ∼600 m/s. Based on these values, we conclude that in the near‐field, we detect ionospheric signatures of acoustic waves. In the far field, the apparent velocity of ionospheric disturbances was estimated to be between 277 and 365 m/s, which corresponds to the propagation of the Lamb wave. It is important to note that our new methods can successfully perform at low spatial resolution networks and with 30‐s cadence data. Also, they enable NRT spatio‐temporal analysis of ionospheric TEC response to smaller‐amplitude events.

Properties of ubiquitous magnetic reconnection events in the lower solar atmosphere

Context.Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon referred to as Ellerman bombs. Recent high-quality Hβobservations indicate that Ellerman bombs are more common than previously thought, and it was estimated that at any time, about half a million Ellerman bombs are present in the quiet Sun.Aims.We performed an extensive statistical characterization of the quiet-Sun Ellerman bombs (QSEBs) in these new Hβobservations.Methods.We analyzed a 1 h dataset of the quiet Sun observed with the Swedish 1-m Solar Telescope that consists of spectral imaging in the Hβand Hαlines as well as spectropolarimetric imaging in Fe I6173 Å. We used thek-means clustering and the 3D connected component labeling techniques to automatically detect QSEBs.Results.We detected a total of 2809 QSEBs. The lifetimes vary between 9 s and 20.5 min, with a median of 1.14 min. The maximum area ranges between 0.0016 and 0.2603 Mm2, with a median of 0.018 Mm2. The maximum brightness in the Hβwing varies between 1.06 and 2.76 with respect to the average wing intensity. A subset (14%) of the QSEBs displays enhancement of the Hβline core. On average, the line core brightening appears 0.88 min after the onset of brightening in the wings, and the distance between these brightenings is 243 km. This gives rise to an apparent propagation speed ranging between −14.3 and +23.5 km s−1, with an average that is upward propagating at +4.4 km s−1. The average orientation is nearly parallel to the limbward direction. QSEBs are nearly uniformly distributed over the field of view, but we find empty areas with the size of mesogranulation. QSEBs are located more frequently near the magnetic network, where they are often larger, live longer, and are brighter.Conclusions.We conclude that QSEBs are ubiquitous in the quiet Sun and appear everywhere, except in areas of mesogranular size with the weakest magnetic fields (BLOS ≲ 50 G). Our observations support the interpretation of reconnection along vertically extended current sheets.

Evaluation of diffuse glioma grade and proliferation activity by different diffusion-weighted-imaging models including diffusion kurtosis imaging (DKI) and mean apparent propagator (MAP) MRI.

To evaluate two advanced diffusion models, diffusion kurtosis imaging and the newly proposed mean apparent propagation factor-magnetic resonance imaging, in the grading of gliomas and the assessing of their proliferative activity. Fifty-nine patients with clinically diagnosed and pathologically proven gliomas were enrolled in this retrospective study. All patients underwent DKI and MAP-MRI scans. Manually outline the ROI of the tumour parenchyma. After delineation, the imaging parameters were extracted using only the data from within the ROI including mean diffusion kurtosis (MK), return-to-origin probability (RTOP), Q-space inverse variance (QIV) and non-Gaussian index (NG), and the differences in each parameter in the classification of glioma were compared. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of these parameters. MK, NG, RTOP and QIV were significantly different amongst the different grades of glioma. MK, NG and RTOP had excellent diagnostic value in differentiating high-grade from low-grade glioma, with largest areas under the curve (AUCs; 0.929, 0.933 and 0.819, respectively; P < 0.01). MK and NG had the largest AUCs (0.912 and 0.904) when differentiating grade II tumours from III tumours (P < 0.01) and large AUCs (0.791 and 0.786) when differentiating grade III from grade IV tumours. Correlation analysis of tumour proliferation activity showed that MK, NG and QIV were strongly correlated with the Ki-67 LI (P < 0.001). MK, RTOP and NG can effectively represent the microstructure of these altered tumours. Multimodal diffusion-weighted imaging is valuable for the preoperative evaluation of glioma grade and tumour proliferative activity.

Fine Structures of an EUV Wave Event from Multi-viewpoint Observations

Abstract In this study, we investigate an extreme ultraviolet (EUV) wave event on 2010 February 11, which occurred as a limb event from the Earth viewpoint and a disk event from the Solar Terrestrial Relations Observatory-Behind viewpoint. We use the data obtained by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory in various EUV channels. The EUV wave event was launched by a partial prominence eruption. Compared with some EUV wave events in previous works, this EUV wave event contains a faster wave with a speed of ∼445 ± 6 km s−1, which we call a coronal Moreton wave, and a slower wave with a speed of ∼298 ± 5 km s−1, which we call the Extreme Ultraviolet Imaging Telescope (EIT) wave. The coronal Moreton wave is identified as a fast-mode wave and the EIT wave is identified as an apparent propagation due to successive field-line stretching. We also observe a stationary front associated with the fast-mode EUV wave. This stationary front is explained as mode conversion from the coronal Moreton wave to a slow-mode wave near a streamer.

Study of mechanical behavior of salt rock with prefabricated fissures under different confining pressures

To study the mechanical behavior of apparent fissures in salt rock, tests on the rock mechanics were conducted on an RMT-150B multifunctional system. The effects of the apparent fissures on the strength and deformation, as well as the apparent fissure propagation behavior of the salt rock and its coalescence pattern, were analyzed. The propagation evolution of the apparent fissures was divided into two types. The main fissures extending from the initial apparent fissures of the salt rock specimens comprised the first type. The second type was that the initial apparent fissures of specimens were closed. Then, new microfissures initiated from the initial apparent fissures gathered together, and formed main fissures. Simultaneously, the secondary fissures grew slowly. The tensile coalescence pattern and tension-shear coalescence pattern are the main coalescence patterns of salt rock with apparent fissures. Pressured coalescence patterns and other coalescence patterns did not appear. Owing to the compactness of the structure, the paths of fissure coalescence present an obvious zigzag line. The influence of vertical transfixion fissures on the deformation modulus of salt rock is greater than the influence of inclined fissures.

Diurnal Variations of Precipitation over the Steep Slopes of the Himalayas Observed by TRMM PR and VIRS

This study investigates diurnal variations of precipitation during May–August, 1998–2012, over the steep slopes of the Himalayas and adjacent regions (flat Gangetic Plains–FGP, foothills of the Himalayas–FHH, the steep slope of the southern Himalayas–SSSH, and the Himalayas-Tibetan Plateau tableland–HTPT). Diurnal variations are analyzed at the pixel level utilizing collocated TRMM precipitation radar and visible infrared data. The results indicate that rain parameters (including rain frequency, rain rate, and storm top altitude) are predominantly characterized by afternoon maxima and morning minima at HTPT and FGP, whereas, maximum rain parameters at FHH typically occur in the early morning. Rain parameters at SSSH are characterized by double peaks; one in the afternoon and one at midnight. Over HTPT and FGP, convective activity is strongest in the afternoon with the thickest crystallization layer. Over FHH, the vertical structure of precipitation develops most vigorously in the early morning when the most intense collision and growth of precipitation particles occurs. Over SSSH, moist convection is stronger in the afternoon and at midnight with strong mixing of ice and water particles. The results of harmonic analysis show that rain bands move southward from lower elevation of SSSH to FHH with apparent southward propagation of the harmonic phase from midnight to early morning. Moreover, the strongest diurnal harmonic is located at HTPT, having a diurnal harmonic percentage variance of up to 90%. Large-scale atmospheric circulation patterns exhibit obvious diurnal variability and correspond well to the distribution of precipitation.