The parameters of the nutations are now known with a good accuracy, and the theory accounts for most of their values. Dissipative friction at the core‐mantle boundary (CMB) and at the inner core ...boundary is an important ingredient of the theory. Up to now, viscous coupling at a smooth interface and electromagnetic coupling have been considered. In some cases they appear hardly strong enough to account for the observations. We advocate here that the CMB has a small‐scale roughness and estimate the dissipation resulting from the interaction of the fluid core motion with this topography. We conclude that it might be significant.
It is shown how a continuous wavelet technique may be used to locate and characterize homogeneous point sources from the field they generate measured in a distant hyperplane. For this a class of ...wavelets is introduced on which the Poisson semi-group essentially acts as a dilation.
In order to elucidate how structural heterogeneities affect the aftershock decay rate, we examine the aftershock sequences produced by a slider‐block model of seismicity. In this model, the geometry ...of the seismic zone is the only free parameter and all aspects of the system are known. The power law aftershock decay rate holds only for smooth faults. A band‐limited power law emerges at intermediate fault complexity. For rough faults, only a transient regime toward an exponential decay is observed. In all fault geometries examined, a band‐limited power law model fits the synthetic aftershock decay rate better than the Modified Omori Law. Then, as the connected seismic elements form a simpler localised surface, we show that the power law aftershock decay rate extends over longer time, and that the power law exponent increases. These results support the inference that the correlation time of the power law aftershock decay rate increases as the deformation localises along dominant major faults.
Anorectal Malformations in Children represents an international consensus in understanding and treating anorectal malformations. Interesting new topics include tethered cord, vaginal reconstruction, ...continent catherizable channels, and the impact on family studies by parents' organizations. The book not only carries on from the three previous editions by Douglas Stephens and Durham Smith (1963, 1971, and 1988) but assembles many new aspects in the broad field of anorectal and genitourinary malformations. Special attention is given to the new surgical techniques posterior sagittal anorectal plasty (PSARP), urogenital sinue advancement, and laparoscopy. A CD-ROM showing the laparoscopic pullthrough procedure is included. It also presents for the first time a series of autopsies performed by Stephens in the 1960s in children with imperforate anus, demonstrating the individual histological anatomy of each malformation. The results of an international workshop of 26 international authorities on congenital malformations of the organs of the pelvis and perineum are presented. The new classification proposed at the Krickenberg Conference will enable future studies comparing the types and the results of treatment of anorectal malformations. The book is an invaluable reference for all medical authorities with a special interest in anorectal and genitourinary malformations.
In this paper, we show how to estimate the phase velocities of multi-mode signals as present in 2-D shallow seismic surveys along a seismic line with the help of a method that is based on the ...deformation of the wavelet spectra of the seismic traces. In analogy with frequency-wavenumber (
f
–
k
) analysis, we perform “frequency-velocity” analysis using the correlations between phases of the wavelet spectra. Our method has two tuning parameters — the parameter of an analyzing wavelet and the parameter of a threshold operation. Numerical and experimental examples are presented to illustrate how the method accurately extracts the phase velocity from single- and multi-mode signals.
.
Earthquake simulators become increasingly important with respect to seismic hazard assessment. It is, therefore, a crucial question whether the imposed simplifications, e.g. reducing fully dynamic ...to quasi-dynamic rupture propagation, may lead to unrealistic results. In the present study, we focus on the role of rupture velocity
v
r
in an earthquake simulator governed by rate-and-state dependent friction as proposed by 8. In particular, we investigate the range of possible values of
v
r
within the model. As an end-member scenario, we consider the existence of a steady-state solution of a one-dimensional rupture front propagating with
v
r
on an idealized two-dimensional fault of infinite dimension discretized into uniform cells. We find that, in principle, values of
v
r
between 0 and ∞ are possible depending on the values of slip speed δ
0
and pre-stress τ
0
ahead of the rupture front. In this view, values of δ
0
close to the slip speed during an earthquake δ
EQ
lead to small values of the time-to-failure and can thus generate ruptures with unrealistic high values of
v
r
, if the model is close to the steady-state conditions. These results are useful to provide constraints for the parameter space of a reasonable earthquake simulator.
Intestinal neuronal dysplasia (IND B) is still a subject of controversy. The aim of this paper is to review the present state of knowledge on IND B. A summary is given of the technical and diagnostic ...criteria which have to be considered in order to arrive at a reliable diagnosis. In addition, the available therapeutic interventions are discussed.
Between 1992 and 2001, 3984 colonic mucosal biopsies from 1328 children were investigated. Nerve cell staining was performed on native tissue sections: 15 microm thick cryostat sections, which, after spreading and drying on a microscopic slide, have a final thickness of 4-5 microm, with dehydrogenase reactions (lactic dehydrogenase, nitroxide synthase, succinic dehydrogenase). The biopsies were taken 8-10 cm above the dentate line (proximal to the ampulla recti, because of the caudo-cranial increase of giant ganglia proximal to the 4 cm biopsy) with a sufficient amount of submucosa. The criteria for IND is 15-20 % submucosal giant ganglia with more than eight nerve cells in 30 sections of a single biopsy (i.e. four to seven giant ganglia).
The diagnosis of IND B is quantitative. A diagnosis of IND B was made over the past 10 years in 51 Hirschsprung resections (about 5 per year; 6 % of all Hirschsprung cases), and in 92 children with chronic constipation (about 9 children per year; 2.3 % incidence). Up to their fourth year of life, most children with isolated IND can be treated conservatively. This is due to the delayed maturation of the enteric nervous system which is characteristic of IND B. Only children who showed an additional hypoplastic hypoganglionosis were treated surgically. Children with Hirschsprung's disease (HD) and IND B proximal to the aganglionosis often showed, in those cases with a disseminated IND, postoperative disturbances in intestinal motility.
The diagnosis of IND B requires that biopsies are taken proximal to the ampulla recti (about 8-10 cm above the dentate line) with a sufficient amount of submucosa. The biopsies must be cut rectangular to the surface of the mucosa. A diagnosis of IND B can be made only if, in the submucosa of 30 serial sections, 15-20 % of all ganglia are giant ganglia with more than eight nerve cells. Ganglioneuromatosis (MEN2B) must be clearly differentiated from IND. The clinical course of IND B depends on the extent of disturbed bowel innervation, the severity of motility failure, and the coexistence of MH. The conservative management of isolated IND is possible in most children. In individual cases, however, a transient enterostomy or a segmental resection is unavoidable.
In the estimate of dispersion with the help of wavelet analysis considerable emphasis has been put on the extraction of the group velocity using the modulus of the wavelet transform. In this paper we ...give an asymptotic expression of the full propagator in wavelet space that comprises the phase velocity as well. This operator establishes a relationship between the observed signals at two different stations during wave propagation in a dispersive and attenuating medium. Numerical and experimental examples are presented to show that the method accurately models seismic wave dispersion and attenuation.
ABSTRACT
We introduce a method of wavefield separation from multicomponent data sets based on the use of the continuous wavelet transform. Our method is a further generalization of the approach ...proposed by Morozov and Smithson, in that by using the continuous wavelet transform, we can achieve a better separation of wave types by designing the filter in the time–frequency domain. Furthermore, using the instantaneous polarization attributes defined in the wavelet domain, we show how to construct filters tailored to separate different wave types (elliptically or linearly polarized), followed by an inverse wavelet transform to obtain the desired wave type in the time domain. Using synthetic and experimental data, we show how the present method can be used for wavefield separation.
Abstract
In this contribution, we extend a series of previous works focused on an investigation of signal’s polarization attributes using the continuous wavelet transform, where we proposed a method ...to map instantaneous polarization attributes of multicomponent signals in the wavelet domain and explicitly relate these attributes with the wavelet transform coefficients of the analyzed signal. In this work, we applied our polarization method to an examination of characteristics of Pi2 pulsations. We have shown some merits of the use of the continuous wavelet transform for the Pi2 pulsations’ analysis. First, we used our polarization method for the geomagnetic field data from the MSR, KAK, GUA, SMA, BLM and LAQ observatories and showed some correlations between the polarization parameters of pulsation and the station’s position (nightside or dayside). Secondly, we considered the signal’s north components of a pair of stations and demonstrated a time-frequency variations of the phase difference between two stations during the pulsation.
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