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Copyright of Earthquake (1000-3274) is the property of Editorial Office of Earthquake Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rapid post-earthquake loss assessments require as input the ground motion footprint of the event. These footprints account for the geographical distribution of the seismic intensities, which, at the same time, depend on characteristics of the event such as magnitude, location, depth, focal mechanism, and orientation of the fault plane. For most earthquakes with MW ≥ 5, moment tensor solution and, hence, the characteristics of the two nodal-planes are available. This paper proposes a simple set of rules for choosing the likely fault plane from the two nodal planes, based on a previous characterization of the seismic sources in the area under study that are commonly used in probabilistic seismic hazard analyses. With the selection of the fault plane, a critically required information for generating the parametric ground motion footprint is at hand in a matter of minutes, to be later used in the loss assessment phase. These almost real-time loss assessments are useful for different disaster risk management activities ranging from emergency planning and management to triggers of parametric insurance instruments. The application of this methodology is illustrated for three events, two in Mexico and another in Guatemala, where loss results and their geographical distributions at country level in some cases are highly sensitive to the selection of the correct nodal plane as the fault plane, showing that the proposed rules yield congruent results with the observed and recorded ground motions. [ABSTRACT FROM AUTHOR]

The focal mechanisms of earthquakes in the Javakheti Highland for the period 1971–2015 were constructed for separate time intervals: 1971–1973, 2001–2004, 2006–2009, 2010–2012, and 2013–2015. The method of averaged mechanisms was used, which jointly processed data on the distribution of the signs of the first P-wave arrivals of Javakheti Highland earthquakes with various energies. As a result of comparing the obtained focal solutions with the tectonic structure of this region, five blocks with different directions of compression–extension forces were identified along the boundaries of active faults in the study area. The prevailing types of slip in earthquake foci in each block for each of the above time intervals were identified. The nature of the source mechanisms for weak earthquakes that preceded the 1986 Paravan earthquake was studied. It was established that shortly before this event, the prevailing type of slip changed from shear to reverse-fault with a shear component. [ABSTRACT FROM AUTHOR]

In this paper, we derive the sharp lower and upper bounds of nodal lengths of Laplacian eigenfunctions in the disc. [ABSTRACT FROM AUTHOR]

On 5 April 2017, an Mw6.1 earthquake occurred about 50 km NE of the city of Fariman, northeast Iran. Several hundreds of aftershocks including two M > 5 events followed the main shock. The quake struck numerous towns and villages across the region, killed one person, and injured tens of people. Many schools and universities were evacuated around the epicentral area, and a lot of people left their residences for a few days. The northeastward motion of the central Iran toward Eurasia influences the epicentral region. Regional movements occur by shortening on the northwest-trending reverse faults. We studied teleseismic source parameters of this earthquake by applying different moment tensor decomposition methods including grid search for the nodal planes of the best double couple; linear inversion for a deviatoric moment tensor; grid search for the best double-couple moment tensor; grid search for the best deviatoric moment tensor; and grid search for the best full moment. Based on the moment tensors, the event occurred on a reverse fault following the regional compressional motion. The results of this study will provide useful information for future regional seismotectonic investigations and are of significant use for applications such as regional seismic hazard evaluations. [ABSTRACT FROM AUTHOR]

Highlights • The dynamics of a highly nonlinear system containing a rigid element plus a very flexible link is derived using an accurate formulation which is called Absolute Nodal Coordinates. • The obtained equations of motion is highly stiff. To solve this difficulty, again a sophisticated method which is called alpha method is utilized. The obtained dynamics has been verified using the previous published papers. • The main contribution of the paper is comparison of various open-loop control methods which are all input-shaping based for the point-to-point transferring of the considered system's end-effector. The obtained results conclude which method is the best for such systems in terms of various metrics. Abstract Motion control of flexible robots is one of the concerns of the researchers in the field of robotics. When the deflection of the flexible arms increases, considerable complexity is imposed in the problem. In the current study, for the first time, various approaches based on the frequency shaping method will be analyzed in motion control of the very flexible robot, in the point to point paths. To this end, a precise system modeling, based on the Absolute Nodal Coordinates (ANC) method, will be employed to the motion study of the system, containing the rigid and the very flexible parts. The provided formulation is very accurate and does not consider any simplifying assumption. As a result, it can exhibit the system behavior once the system undergoes large deformation and the resulted system is highly nonlinear. Comparing the obtained results with the previous conducted researches, the system modeling will be verified. Since the resulted nonlinear differential equations are highly stiff, some sophisticated numerical dynamics model methods, such as alpha technique, are utilized to numerical simulation of the system. Despite of the various advantages of the ANC modeling method, the controller designing is complicated based on this method. Therefore, the Input Shaping (IS) method are utilized to this end, in the current study. The IS method is based on the identification of the excited frequency modes of the system during the motion, and reduction of these frequencies energy in the resulted shaped inputs. The various shaping methods, such as Zero Vibration (ZV), Zero Vibration Derivative (ZVD), Extra Insensitivity (EI), and negative shaping method, will be utilized in the motion control of the very flexible link. The performance of the aforementioned methods will be evaluated using some criteria such as, time duration for the system transferring, the control effort, the robustness, and the steady state vibrations. Finally, the advantages/disadvantages of the mentioned methods will be discussed. [ABSTRACT FROM AUTHOR]

Abstract When deriving nodal methods, the known process of transverse integration introduces additional unknowns to the problem, related to the leakage terms. Additional auxiliary equations must be proposed in order to close the system and to allow its solution. In this work, a study on approximations to those unknowns, fluxes on the contours of the nodes, is carried out. In particular, two-dimensional fixed-source problems are analyzed. Therefore, three alternative proposals of approximations are considered: constant, linear and exponential functions. Such approaches are employed along with of the ADO method, which is used to solve the one-dimensional transversely integrated equations. Numerical results for section averaged scalar fluxes are presented and compared with other nodal schemes, showing some differences among the various approximations, mainly for coarse meshes, although satisfactory comparisons are achieved in the source region. [ABSTRACT FROM AUTHOR]

Bangkok, Nonthaburi and Samut Prakan are the three most densely populated provinces in Thailand. They have a large drinking water consumption supplied by the Metropolitan Waterworks Authority (MWA). MWA's service area is over 2.42 km2 with 2.33 million customers (1 customer is 1 household) and it had to supply 5.843 million m3 of drinking water per day in the year 2017. Because the main pipe network is very complex and extremely large. For this reason, it is very difficult to manage the water supply. In order to decide a suitable supply, EPANET is one of the tools for managing a water supply in the main water piping network but it can lead to an error of nodal elevation in the pipe network. In this research, we have revised the nodal elevation on the pipe network by reference from Bangkok roads elevation map, it was found that the new pipe network has better accuracy of up to 87.63%, an improvement on the existing model of 3.95%. [ABSTRACT FROM AUTHOR]

As discovered in recent work, plasma fireballs have the ability to exert considerable force onto ions and neutrals and, hence, induce macroscopic gas flows. This property makes them interesting objects for fundamental scientific research. Furthermore, there are also the possibilities for applications in the field space propulsion. As there is a lack of fundamental understanding of these plasma phenomena, this article aims to enhance the physical knowledge of fireballs by presenting a mathematical model for the calculation of the force that can be provided by them. It will be shown that all the main plasma parameters such as the plasma potential and the electron density can be derived completely with the knowledge of the potential of the electrode and the radial electron temperature profile. The calculations show very good agreement with the experimental data if two species of electrons (i.e., fast and slow) are considered. Both electron populations have different temperature profiles as is shown with measurements. Furthermore, it will be demonstrated that the potential drop throughout the fireball is much larger than previously thought and that this larger potential drop can considerably contribute to the acceleration of ions in the double layer. This mechanism makes it more likely that the force exerted by the fireball is rather caused by heating of the neutrals via collisions with those accelerated ions and the high energetic ions themselves than by collisions between fast electrons and neutrals. [ABSTRACT FROM AUTHOR]

We study the volume distribution of nodal domains of families of naturally arising Gaussian random fields on generic manifolds, namely random band-limited functions. It is found that in the high energy limit a typical instance obeys a deterministic universal law, independent of the manifold. Some of the basic qualitative properties of this law, such as its support, monotonicity and continuity of the cumulative probability function, are established. [ABSTRACT FROM AUTHOR]

Micromagnetic simulations at room temperature (300K) have been carried out in order to analyse the magnetic eigenmodes (frequency and spatial profile) in elliptical dots with sub-100 nm lateral size. Features are found that are qualitatively different from those typical of larger dots because of the dominant role played by the exchange-energy. These features can be understood most simply in terms of nodal planes defined relative to the orientation of the static magnetization. A new, generalized labeling scheme is proposed that simplifies discussion and comparison of modes from different geometries. It is shown that the lowest-frequency mode for small dots is characterized by an in-phase precession of spins, without nodal planes, but with a maximum amplitude at the edges. This mode softens at an applied switching field with magnitude comparable to the coercive field and determines specific aspects of magnetization reversal. This characteristic behavior can be relevant for optimization of microwave assisting switching as well as for maximizing interdot coupling in dense arrays of dots. [ABSTRACT FROM AUTHOR]

The potential improvement of plenum window noise reduction by installing rigid circular cylinder arrays into the window cavity is investigated numerically using the finite-element method in this study. A two-dimensional approach is adopted. The sound transmission characteristics and propagation within the plenum window are also examined in detail. Results show that the installation of the cylinders in general gives rise to broadband improvement of noise reduction across a plenum window regardless of the direction of sound incidence. Such acoustical performance becomes better when more cylinder columns are installed, but it is suggested that the number of cylinder rows should not exceed two. Results also show that the cylinder positions relative to the nodal/anti-nodal planes of the acoustic modes are crucial in the noise reduction enhancement mechanisms. Noise reduction can further be enhanced by staggering the cylinder rows, such that each cylinder row supports the development of a different acoustic mode. For the simple cylinder arrangements considered in this study, the traffic noise reduction enhancement observed in this study can be as high as 4–5 dB, which is already comparable to or higher than the maximum achieved by installing sound absorption into a plenum window. [ABSTRACT FROM AUTHOR]

We propose a finite-difference time-domain (FDTD) scheme based on generalized sheet transition conditions (GSTCs) for the simulation of polychromatic, nonlinear, and space–time varying metasurfaces. This scheme consists in placing the metasurface at virtual nodal plane introduced between the regular nodes of the staggered Yee grid and inserting fields determined by GSTCs in this plane in the standard FDTD algorithm. The resulting update equations are an elegant generalization of the standard FDTD equations. Indeed, in the limiting case of a null surface susceptibility ( \chi \text {surf}=0 ), they reduce to the latter, while in the next limiting case of a time-invariant metasurface [\chi \text {surf}\neq \chi \text {surf}(t)] , they split in two terms, one corresponding to the standard equations for a one-cell ( $\Delta x$ ) thick slab with diluted volume susceptibility ( \chi =\chi _{\text {surf}}/(2\Delta x) ), and the other one reducing that slab to a quasi-zero-thickness mesh-less sheet. The proposed scheme is fully numerical and very easy to implement. Although it is explicitly derived for a monoisotropic metasurface, it may be straightforwardly extended to the bianisotropic case. Except for some particular cases, it is not applicable to dispersive metasurfaces, for which an efficient auxiliary different equation extension of the scheme is currently being developed by the authors. The scheme is validated and illustrated by five representative examples. [ABSTRACT FROM AUTHOR]

In this study, first, a formula for regularized sums of eigenvalues of a Sturm-Liouville problem with retarded argument at 2 points of discontinuity which contains a spectral parameter in the boundary conditions is obtained. After that, oscillation properties of the related problem is investigated. Finally, under the condition that a subset of nodal points is dense in definition set, the potential function is determined. [ABSTRACT FROM AUTHOR]

In this paper, a random field model based on nodal integration domain is presented to solve stochastic heat transfer problems. In the proposed model, the uncertainty of the inputs are considered as random field, which is discretized into a number of node-based subdomains and the properties of the uncertainties under random field can be considered at the nodes. The proposed method is efficient to model non-uniform material under random field with constitutive equation, meanwhile, the random field with arbitrary geometry can be simulated conveniently and efficiently by using the Karhunen-Loève expansion truncated in this work. The statistical moments of the structural responses using the perturbation method is also performed and compared with the solutions of Monte Carlo simulation. The proposed method is successfully applied to the steady-state heat transfer problem with spatially varying random material parameter introduced in the thermal conductivity in this work. Finally, we demonstrate the accuracy and performance of the proposed method through a series of numerical examples both in 2D and 3D steady-state heat transfer problems under different random fields. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotubes (N-CNTs) act as a metal-free catalyst for oxygen reduction reaction (ORR), but improving the ORR activity of N-CNTs remains challenging due to a lack of structural information. The N-CNTs with higher nitrogen concentration (an average surface nitrogen concentrations, 14.3 at.%) than the N-CNTs fabricated by conventional chemical vapor deposition method were synthesized using a dielectric barrier discharge in high pressure nitrogen and the spatial distribution of nitrogen in the N-CNTs was demonstrated by transmission electron microscopy in conjunction with electron energy loss spectroscopy. Nitrogen atoms were found to be concentrated at nodal regions in the bamboo-like structure, at concentrations above 23 at.%. At the point of the ORR, the highest onset potential was observed in the N-CNTs due to relatively highly incorporated pyridine-like nitrogen. [ABSTRACT FROM AUTHOR]

Long space tethers are becoming a rising concern as an alternate way for transportation in space. It benefits from fuel economizing. This paper focuses on the dynamics of the tether transportation system, which consists of two end satellites connected by a flexible tether, and a movable vehicle driven by the actuator carried by itself. The Absolute Nodal Coordinate Formulation is applied to the establishment of the equation of motion, so that the influence caused by the distributed mass and elasticity of the tether is introduced. Moreover, an approximated method for accelerating the calculation of the generalized gravitational forces on the tether is proposed by substituting the volume integral every step into summation of finite terms. Afterwards, dynamic evolutions of such a system in different configurations are illustrated using numerical simulations. The deflection of the tether and the trajectory of the crawler during the transportation is investigated. Finally, the effect on the orbit of the system due to the crawler is revealed. [ABSTRACT FROM AUTHOR]

In this paper, the relationships of the plunges and azimuths of T and P axes versus the strikes, dips, and rakes of two seismic nodal planes were derived to provide reference for earthquake researchers. The independence of the plunges and azimuths of T, B, and P axes in focal mechanism solution was discussed, and it was concluded that three parameters, i.e., the azimuths of T, B and P axes, are completely independent. The focal mechanism solution representation based on Euler rotation was introduced, using three Euler angles in place of the plunges and azimuths of T, B, and P axes, and three focal mechanism solution representations were briefly compared and analyzed in respect of accuracy on the basis of the assumption of rounding; it was concluded that the Euler angle representation has better accuracy, compared with the azimuth representation and the traditional representation with T, B, and P axes. [ABSTRACT FROM AUTHOR]

In this paper a novel variational method is developed to construct four-end solutions in R 2 for the Allen–Cahn equation. Four-end solutions have been constructed by Del Pino, Kowalczyk, Pacard and Wei when the angle θ of the ends is close to π / 2 or 0 using the Lyapunov–Schmid reduction method, and later by Kowalczyk, Liu and Pacard using a continuation method for general θ ∈ ( 0 , π / 2 ) . By a special mountain pass argument in a restricted space, namely a set of monotone paths of monotone functions, a family of solutions in bounded domain is constructed with very good control of their nodal sets, which then leads to a four-end solution after sending the domains to R 2 . In this way, not only a family of four end solutions is constructed for any angle θ ∈ ( 0 , π / 2 ) . The Morse index of such a four-end solution is also shown to be one. [ABSTRACT FROM AUTHOR]

In this paper, we prove certain basic results on the construction of a degeneration of the moduli space of Higgs bundles (and more generally Hitchin pairs) on smooth curves, as the smooth curve Xk degenerates to an irreducible nodal curve with a single node. As an application, we get new compactifications of the Picard variety for smooth curves degenerating to irreducible nodal curves. [ABSTRACT FROM AUTHOR]

In April 2015, a M7.8 earthquake occurred less than one month before a M7.3 earthquake near Kodari, Nepal. The Nepal earthquake sequences also include four larger (M > 6) aftershocks. To reveal the interrelation between the main shock and the aftershocks, we check the role of coseismic coulomb stress triggering on aftershocks that follow the M7.8 main shock. Based on the focal mechanisms of the aftershocks and source models of the main shock, the coulomb failure stress changes on both of the focal mechanism nodal planes are calculated. In addition, the coulomb stress changes on the focal sources of each aftershock are also calculated. A large proportion of the M > 6 aftershocks occurred in positive coulomb stress areas triggered by the M7.8 main shock. The secondary triggering effect of the M7.3 aftershock is also found in this paper. More specifically, the M7.3 aftershock promoted failure on the rupture plane of the M6.3 aftershock. Therefore, we may conclude that the majority of larger aftershocks, which accumulated positive coulomb stress changes during the sequence, were promoted or triggered by the main shock failure. It suggests that coulomb stress triggering contributed to the evolution of the Nepal M7.8 earthquake sequence. [ABSTRACT FROM AUTHOR]

Underground mining of coal seams in the Upper Silesian Coal Basin in Poland is accompanied by seismic activity of varying magnitude. The investigations which have been performed for several years distinguished high energy mine tremors connected directly with mining or coupled with geological structures, such as large faults. In mined seams, local fault zones occur. Faults in these zones are usually small, with throws comparable with coal seams thicknesses. Local fault zone may be responsible for the occurrence of high energy tremors as well as large faults, as presented in this article. An analysis of source mechanism of high energy tremors generated during longwall mining of the coal seam No. 510, with presence of a local fault zone, in one of the Polish hard coal mines in the Upper Silesian Coal Basin was performed. For this purpose, the seismic moment tensor inversion method was used. In most of foci, the process of shear predominated. Determined nodal plane parameters were correlated with parameters of faults forming the local fault zone. High energy tremors were generated mostly by dislocations on faults of the local fault zone. Weakening of roof rocks in the neighborhood of local fault zone takes an important role too, and was responsible for share of implosion in the focal mechanism. [ABSTRACT FROM AUTHOR]

In this paper we are interested in the following fourth order eigenvalue problem coming from the buckling of thin films on liquid substrates: where $$B_1$$ is the unit ball in $${\mathbb R}^N$$ . When $$\kappa > 0$$ is small, we show that the first eigenvalue is simple and the first eigenfunction, which gives the shape of the film for small displacements, is positive. However, when $$\kappa $$ increases, we establish that the first eigenvalue is not always simple and the first eigenfunction may change sign. More precisely, for any $$\kappa \in \mathopen ]0,+\infty \mathclose [$$ , we give the exact multiplicity of the first eigenvalue and the number of nodal regions of the first eigenfunction. [ABSTRACT FROM AUTHOR]

Over the past few years, considerable attention has been given to the role played by the Lamé's Wave Functions (LWFs) in various problems of mathematical physics and mechanics. The LWFs arise via the method of separation of variables for the wave equation in ellipsoidal coordinates. The present paper introduces the Lamé's Quaternionic Wave Functions (LQWFs), which extend the LWFs to a non-commutative framework. We show that the theory of the LQWFs is determined by the Moisil-Theodorescu type operator with quaternionic variable coefficients. As a result, we explain the connections between the solutions of the Lamé's wave equation, on one hand, and the quaternionic hyperholomorphic and antihyperholomorphic functions on the other.We establish analogues of the basic integral formulas of complex analysis such as Borel-Pompeiu's, Cauchy's, and so on, for this version of quaternionic function theory. We further obtain analogues of the boundary value properties of the LQWFs such as Sokhotski-Plemelj formulae, the Dα-hyperholomorphic extension of a given Hölder function and on the square of the singular integral operator.We address all the text mentioned earlier and explore some basic facts of the arising quaternionic function theory. We conclude the paper showing that the spherical, prolate, and oblate spheroidal quaternionic wave functions can be generated as particular cases of the LQWFs. [ABSTRACT FROM AUTHOR]

During March–April 2014 a series of earthquakes occurred around the Iquique city located in the northern Chile region. The two largest events of this sequence are the Mw8.2, April 1, 2014 and Mw7.7, April 4, 2014 quakes. Here we computed the nodal planes of eight of the large and well teleseismically recorded events of this series based on grid search, teleseismic moment tensors inversion, empirical Green's function deconvolution and its stack to average the deconvolutions for the Mw = 8.2, April 1, 2014, synthetic Green's function deconvolution and its stack to average the deconvolutions for the same event and 3D static deformation analysis of the above mentioned events based on the AK135 model. Grid search nodal planes and moment tensors suggest the dominance of reverse faulting. Almost all of the calculated teleseismic moment tensors represent a considerable amount of DC (usually more than 90%) and lower amount of CLVD for this sequence of events. Empirical and synthetic Green's function deconvolution showing down dip rupture propagation and 3D static deformation representing higher amount of vertical deformation in comparison with horizontal deformation components plus the existence of uplift and subsidence. According to the aftershocks distribution there is a bilateral distribution of the aftershocks around the first large event of this sequence that occurred March 16, 2014 (Mw6.7) so that they are approximately limited between the Mw8.2 (at north) and Mw7.7 (at south) quakes. Moreover there exist two bands of regional seismicity during early-mid 2014: a shallow off-shore band between the trench and coast and a deeper inland band under the active volcanic chain (both nearly parallel to the trench). [ABSTRACT FROM AUTHOR]

The review generalizes the studies devoted to the development of a new quantum chemistry method representing an alternative to the Hartree-Fock approximation. Based on the hypothesis of prohibition of equipotential surfaces, which clarifies the physical sense of the Pauli exclusion principle, and taking account of the condition for antisymmetrical wave function of the triplet state (3S) of He atom, the Hartree-Fock approximation is inappropriate for a priori determination of the nodal surfaces of many-electron wave functions (MWFs) for the test systems traditionally used in quantum chemistry, namely, excited triplet state of H molecule and the ground electronic states of Li atom and LiH molecule. The nodal surfaces of the wave functions corresponding to the minimum basis set of Slater orbitals in the Hartree-Fock approximation are constructed and analyzed. An alternative to the Hartree-Fock approximation is provided by the MWF quantum chemical method being developed by the authors. In the MWF method, the nodal surfaces for H(Σ ) and Li(S) are specified a priori. Some aspects of geometric interpretation of the Pauli exclusion principle are discussed. Unlike the MWF method, the Hartree-Fock approximation is unsuitable for taking account of the dependence of the MWF nodal surfaces on the nuclear charges and on correlation effects related to the motion of electrons with antiparallel spins because such nodal surfaces are predefined by the mathematical properties of Slater determinants rather than by physically clear and more practically valuable algebraic products of electrostatic potential differences. [ABSTRACT FROM AUTHOR]

The accuracy of the nodal patterns of combined degenerate mode shapes for a square membrane by previous researchers is investigated, and the nodal patterns of superimposed degenerate modes for square and non-square membranes and simply-supported plates are presented in a full range of amplitude ratios. [ABSTRACT FROM PUBLISHER]

An M6.5 earthquake occurred on August 3rd, 2014 in Ludian of Yunnan Province in China, causing severe casualty and economic loss. Local broadband waveform inversion with the CAP method demonstrates that the earthquake is a strike-slip event, with the strike along 70° and 160° for the two nodal planes respectively. However, the geological structure in the epicentral region is complicated with abundant active faults, and it is challenging to identify the seismogenic fault with the focal plane solutions due to nodal-plane ambiguity. We resolved the rupture directivity by measuring the difference between centroid location and hypocenter of the Ludian earthquake with the time shift from CAP inversion, and found that the nodal plane with the strike of 160° is the ruptured fault plane. Moreover, the rupture is found to propagate from northwest to southeast. [ABSTRACT FROM AUTHOR]

Earthquake waveform from a new temporary network of 21 seismic stations in South India has been used to significantly improve the detection threshold and parameters of small earthquakes near Idukki Reservoir, Kerala. We present here precise location of 16 earthquakes in this region with a local magnitude of 1.5-3.6 and focal depth 7.2-9.9 km. Fault plane solutions of the selected best six earthquakes show strikeslip faulting and right lateral movement. Reservoir loading usually leads to generation of stress and therefore earthquakes in the shallow depth (< 5 km), that are absent in the region of Idukki Reservoir. Recorded earthquakes are confined to a NW-SE trending fault close to Karur-Kamabam-Painavu-Trichur (KKPT) shear zone. These observations suggest that the earthquakes in Idukki region are tectonic in nature and have no linkage with the reservoir. [ABSTRACT FROM AUTHOR]

Stress inversions from focal mechanisms require knowledge of which nodal plane is the fault. If such information is missing, and faults and auxiliary nodal planes are interchanged, the stress inversions can produce inaccurate results. It is shown that the linear inversion method developed by Michael is reasonably accurate when retrieving the principal stress directions even when the selection of fault planes in focal mechanisms is incorrect. However, the shape ratio is more sensitive to the proper choice of the fault and substituting the faults by auxiliary nodal planes introduces significant errors. This difficulty is removed by modifying Michael's method and inverting jointly for stress and for fault orientations. The fault orientations are determined by applying the fault instability constraint and the stress is calculated in iterations. As a by-product, overall friction on faults is determined. Numerical tests show that the new iterative stress inversion is fast and accurate and performs much better than the standard linear inversion. The method is exemplified on real data from central Crete and from the West-Bohemia swarm area of the Czech Republic. The joint iterative inversion identified correctly 36 of 38 faults in the central Crete data. In the West Bohemia data, the faults identified by the inversion were close to the principal fault planes delineated by foci clustering. The overall friction on faults was estimated to be 0.75 and 0.85 for the central Crete and West Bohemia data, respectively. [ABSTRACT FROM PUBLISHER]

A kinematic finite-source study of the 11 May 2011 Mw 5.2 Lorca, Spain, earthquake has been performed using broadband data from the Spanish National Network. The nodal plane ambiguity of the double-couple solution was resolved from finite-source analysis, and a rupture velocity of 1.8 kms-1 and the northeast-southwest-striking northwest-dipping plane was found to best fit the data. This fault plane corresponds to the central sector of the Alhama de Murcia fault (AMF). The resulting slip distribution has a maximum of 19.3 cm and a total seismic moment of 6.25 x 1016 N- m. A Jackknife test has been performed to estimate the fault plane errors and their consequences in the slip distribution. Also synthetic tests have been performed to evaluate the errors in the finite-source modeling. From this model, a prediction of the strong ground motion near the fault, corrected for soil amplification, is given in terms of peak ground velocity (PGV), which fits with the observed value at the accelerograph in the city of Lorca. We also compared the PGV converted to modified Mercalli intensity at the surface with the intensity distribution, also showing good agreement. Finally we extracted the directivity pulse from the strong ground motion record at Lorca with 0.5 s period in the transverse component to the AMF direction and 33 cms-1 PGV. To further analyze the directivity effect, we estimate the duration and azimuthal amplitude distribution of the source time functions, finding them to be shorter and of greater amplitude in the direction of rupture and longer and smaller in amplitude in the opposite direction. [ABSTRACT FROM AUTHOR]

Abstract: The Al Hoceima Mw 6.4 earthquake of 24 February 2004 that occurred in the eastern Rif region of Morocco already hit by a large event in May 1994 (Mw 5.9) has been followed by numerous aftershocks in the months following the event. The aftershock sequence has been monitored by a temporary network of 17 autonomous seismic stations during 15 days (28 March–10 April) in addition to 5 permanent stations of the Moroccan seismic network (CNRST, SPG, Rabat). This network allowed locating accurately about 650 aftershocks that are aligned in two directions, about N10-20E and N110-120E, in rough agreement with the two nodal planes of the focal mechanism (Harvard). The aftershock alignments are long enough, about 20km or more, to correspond both to the main rupture plane. To further constrain the source of the earthquake main shock and aftershocks (mb>3.5) have been relocated thanks to regional seismic data from Morocco and Spain. While the main shock is located at the intersection of the aftershock clouds, most of the aftershocks are aligned along the N10-20E direction. This direction together with normal sinistral slip implied by the focal mechanism is similar with the direction and mechanisms of active faults in the region, particularly the N10E Trougout oblique normal fault. Indeed, the Al Hoceima region is dominated by an approximate ENE-SSW direction of extension, with oblique normal faults. Three major 10–30km-long faults, oriented NNE-SSW to NW-SE are particularly clear in the morphology, the Ajdir and Trougout faults, west and east of the Al Hoceima basin, respectively, and the NS Rouadi fault 20km to the west. These faults show clear evidence of recent vertical displacements during the late Quaternary such as uplifted alluvial terraces along Oued Rihs, offset fan surfaces by the Rouadi fault and also uplifted and tilted abandoned marine terraces on both sides of the Al Hoceima bay. However, the N20E direction is in contrast with seismic sources identified from geodetic inversions, which favour but not exclusively the N110-120E rupture directions, suggesting that the 1994 and 2004 events occurred on conjugate faults. In any event, the recent seismicity is thus concentrated on sinistral N10-20E or N110-120E dextral strike-slip faults, which surface expressions remain hidden below the 3–5km-thick Rif nappes, as shown by the tomographic images build from the aftershock sequence and the concentration of the seismicity below 3km. These observations may suggest that strain decoupling between the thrusted cover and the underlying bedrock and highlights the difficulty to determine the source properties of moderate events with blind faults even in the case of good quality recorded data. [Copyright &y& Elsevier]

The dynamics of scroll waves with a variable orientation to a vertically oriented gradient of excitability is studied by optical tomography in the ferroin-catalyzed Belousov-Zhabotinsky reaction. An almost perpendicular orientation between the scroll wave and gradient induces a pair of twists of opposite handedness on the scroll wave. The position of the nodal plane formed between the twists is governed by the time delay of the twist formation and therefore leads to a symmetric or asymmetric twisted scroll wave. Larger inclinations between scroll wave and gradient cause a drift of the filament along the reactor wall until it reaches the bottom of the reaction container. In this case, the scroll wave does not twist, suggesting that a drift acts as an alternative mechanism of responding to the gradient. [ABSTRACT FROM AUTHOR]

Experimental phasing of diffraction data from macromolecular crystals involves deriving phase probability distributions. These distributions are often bimodal, making their weighted average, the centroid phase, improbable, so that electron-density maps computed using centroid phases are often non-interpretable. Density modification brings in information about the characteristics of electron density in protein crystals. In successful cases, this allows a choice between the modes in the phase probability distributions, and the maps can cross the borderline between non-interpretable and interpretable. Based on the suggestions by Vekhter [Vekhter (2005), Acta Cryst. D 61, 899-902], the impact of identifying optimized phases for a small number of strong reflections prior to the density-modification process was investigated while using the centroid phase as a starting point for the remaining reflections. A genetic algorithm was developed that optimizes the quality of such phases using the skewness of the density map as a target function. Phases optimized in this way are then used in density modification. In most of the tests, the resulting maps were of higher quality than maps generated from the original centroid phases. In one of the test cases, the new method sufficiently improved a marginal set of experimental SAD phases to enable successful map interpretation. A computer program, SISA, has been developed to apply this method for phase improvement in macromolecular crystallography. [ABSTRACT FROM AUTHOR]

According to the theory of Kozai resonance, the initial mutual inclination between a small body and a massive planet in an outer circular orbit is as high as ∼39.◦ 2 for pumping the eccentricity of the inner small body. Here we show that with the presence of a residual gas disk outside two planetary orbits, the inclination can be reduced to as low as a few degrees. The presence of the disk changes the nodal precession rates and directions of the planet orbits. At the place where the two planets achieve the same nodal processing rate, vertical secular resonance (VSR) occurs so that the mutual inclination of the two planets will be excited, which might further trigger the Kozai resonance between the two planets. However, in order to pump an inner Jupiter-like planet, the conditions required for the disk and the outer planet are relatively strict. We develop a set of evolution equations, which can fit the N-body simulation quite well but can be integrated within a much shorter time. By scanning the parameter spaces using the evolution equations, we find that a massive planet (10MJ ) at 30AU with an inclination of 6◦ to a massive disk (50MJ ) can finally enter the Kozai resonance with an inner Jupiter around the snowline. An inclination of 20◦ of the outer planet to the disk is required for flipping the inner one to a retrograde orbit. In multiple planet systems, the mechanism can happen between two nonadjacent planets or can inspire a chain reaction among more than two planets. This mechanism could be the source of the observed giant planets in moderate eccentric and inclined orbits, or hot Jupiters in close-in, retrograde orbits after tidal damping. [ABSTRACT FROM AUTHOR]

Abstract: We use a triangular representation of the plunges of P, B, and T axes to compare the different ways tectonic regime is inferred from earthquake focal mechanisms in recent works. We argue that P, B, and T axes provide a reasonable estimate of principal stress directions when faulting is close to Andersonian conditions, and that this can be estimated from the location on a triangular diagram. We analyze the geometrical relationship between the plunges of P, B, and T axes on one hand, and the rake of slip and dip of nodal planes on the other hand. We show that the rake and dip level curves correspond to trajectories of the vertical direction along great and small circles with respect to the frame of the P, B, and T axes. This shows that dip-slip faulting is compatible with vertical P or T axes, but does not require it, and instead requires horizontal B axes. It also shows that strike-slip faulting does not require vertical B axes, but P and T axes with equal plunges. This also reveals that focal mechanisms where P, B, and T axes all have moderate plunge correspond to two very different types of nodal planes: a steeply dipping one with oblique slip and a moderately dipping one with strike-slip. Seismically active and moderately dipping strike-slip faults are to be found among these events. [Copyright &y& Elsevier]

Earthquakes fault plane solutions (FPSs) are routinely computed on the basis of various techniques and are reported in the literature with a wide range of formats and conventions. Although the equations relating the various parameters are well known and relatively simple, their practical application often arise to numerical singularities and indeterminations that sometimes are not well known by the authors and thus may result in wrong or inaccurate reporting of parameters. Such inaccuracies and mistakes affect about 40% of the published data we have examined to test our programs. Moreover the current use, in the seismological community, of at least two different coordinate systems to represent the Cartesian components of vectorial and tensorial quantities is a further cause of confusion. In order to simplify the management of such data, we have prepared a structured package of FORTRAN 77 subroutines performing almost all of the possible computations and conversions among different parameters and coordinate systems. The package has been extensively tested with the data of a revised database of FPS of Italy and surrounding regions (presented in a companion paper) as well as of CMT solutions included in the Harvard catalog. [Copyright &y& Elsevier]

Vibration modes in spherical geometry can be classified based on the number and position of nodal planes. However, the geometry of these planes is non-trivial and cannot be easily displayed in two dimensions. We present 3D-printed models of those vibration modes, enabling a haptic approach for understanding essential features of bound states in quantum physics and beyond. In particular, when applied to atomic physics, atomic orbitals are obtained in a natural manner. Applied to nuclear physics, the same patterns of vibration modes emerge as cornerstone for the nuclear shell model. These applications of the very same model in a range of more than 5 orders of magnitude in length scales leads to a general discussion of the applicability and limits of validity of physical models in general. [ABSTRACT FROM AUTHOR]

In this work, the Sturm-Liouville problem perturbated by a Volterra-type integro-differential operator is studied. We give a uniqueness theorem and an algorithm to reconstruct the potential of the problem from nodal points (zeros of eigenfunctions). [ABSTRACT FROM AUTHOR]

Topological nodal-line semimetals are characterized by one-dimensional lines of band crossing in the Brillouin zone. In contrast to nodal points, nodal lines can be in topologically nontrivial configurations. In this Rapid Communication, we introduce the concept of "nodal-knot semimetals," whose nodal lines form topologically nontrivial knots in the Brillouin zone. We introduce a generic construction of nodal-knot semimetals, which yields the simplest trefoil nodal knot and other more complicated nodal knots. The knotted-unknotted transitions by nodal-line reconnections are also studied. Our work brings the knot theory to the subject of topological semimetals. [ABSTRACT FROM AUTHOR]

We use a Kubo formalism to calculate both AC conductivity and DC transport properties of a dirty nodal loop semimetal. The optical conductivity as a function of photon energy Ω exhibits an extended flat background σBG as in graphene provided the scattering rate Γ is small as compared to the radius of the nodal ring b (in energy units). Modifications to the constant background arise for Ω ≤ Γ and the minimum DC conductivity σDC, which is approached as Ω²/Γ² as Ω → 0, is found to be proportional to ... with vF the Fermi velocity. For b = 0 we recover the known three-dimensional point node Dirac result σDC ~ Γ/vF while for b > Γ, σDC becomes independent of Γ (universal) and the ratio σDC/σBG = 8/π² where all reference to material parameters has dropped out. As b is reduced and becomes of the order Γ, the flat background is lost as the optical response evolves towards that of a three-dimensional point node Dirac semimetal which is linear in Ω for the clean limit. For finite Γ there are modifications from linearity in the photon region Ω ≤ Γ. When the chemical potential μ (temperature T) is nonzero the DC conductivity increases as μ²/Γ²(T²/Γ²) for μ/Γ (T/Γ) ≤ 1. Such laws apply as well for thermal conductivity and thermopower with coefficients of the quadratic law only slightly modified from their value in the three-dimensional point node Dirac case. However in the μ = T = 0 limit both have the same proportionality factor of √Γ²+b² as does σDC. Consequently the Lorentz number is largely unmodified. For larger values of μ > Γ away from the nodal region the conductivity shows a Drude-like contribution about Ω ≊ 0 which is followed by a dip in the Pauli blocked region Ω ≤ 2 μ after which it increases to merge with the flat background (two-dimensional graphene like) for μ < b and to the quasilinear (three-dimensional point node Dirac) law for μ > b. [ABSTRACT FROM AUTHOR]

Molecular-frame three-dimensional (3D) photoelectron momentum distributions (PMD) from strong-field ionization by circularly polarized laser pulses of 3D aligned naphthalene are obtained using tomographic reconstruction. The analysis of various two-dimensional (2D) cuts of the 3D PMD points to orbital modification in the presence of strong fields. The possibility of observing signatures of the molecular orbital nodal planes in the 2D projections of the 3D PMD is also discussed. [ABSTRACT FROM AUTHOR]