Neuromyelitis optica nmo the guthyjackson charitable. Normal moveout correction nmo is a stretching of the time axis to make all seismograms look like zerooffset seismograms. Processing of seismic reflection data tu delft opencourseware. Neuromyelitis optica nmo and neuromyelitis optica spectrum disorder nmosd occur when the immune system mistakes normal tissues of the central nervous system as being foreign.
Perform an nmo correction of all the midpoint gathers using the corresponding nmo velocity derived above and sum each along the offset direction. This expression shows that these effects primarily distort the avo gradient while essentially leaving the intercept unbiased. The damage to the optic nerves produces swelling and inflammation that cause pain and loss of. Open any textbook about seismic data processing and you will inevitably find a section about the normal moveout nmo correction. The 2015 consensus diagnostic criteria for nmo and nmo spectrum disorders nmosd apply the latest scientific and medical insights into adult and pediatric disease, imaging, laboratory tests, and potential relationships of nmosd to other autoimmune diseases. Nmo in 20, the rocky mountain ms center board of directors expanded the mission of the ms center to include related diseases. The next step is to apply nmo based velocity analysis to the nankai dataset keys and foster, 1998. A variety of noninvasive structural imaging and functional tools can be used to investigate mechanisms of white matter injury and secondary axonal injury in ms and nmo. And to create, protect, convert, and edit pdfs, try out acrobat pro. The nmo correction adjusts observed travel time red path to midpoint zerooffset travel time blue path. These new criteria are anticipated to improve diagnostic accuracy of nmosd and other autoimmune diseases and speed appropriate therapies. View notes nmo correction formuladerivation from geology 306 at rutgers university.
Nmocorrectionformuladerivation derivation of the nmo. Nmo is listed in the worlds largest and most authoritative dictionary database of abbreviations and acronyms the free dictionary. Do everything you can do in acrobat reader dc, plus create, protect, convert, and edit your pdfs. Neuromyelitis optica nmo and multiple sclerosis ms both result in acute injury i. Wavelet stretching due to nmo correction of seismic gathers causes problems in avo. The first is the traveltime approximation, which determines the curve or surface approximation to the reflection or diffraction traveltime of the measured events.
The method is based on a predefined number of nmo velocity sweeps using linear vertical. Nmo stretch manifests the most at far offsets and early times, where the nmo correction is the most severe. A function of time and offset that can be used in seismic processing to compensate for the effects of normal moveout, or the delay in reflection arrival times when. Pdf nonhyperbolic stretchfree normal moveout correction. Nmo is listed in the worlds largest and most authoritative dictionary database of abbreviations and acronyms. The role of demyelination in neuromyelitis optica damage. The amplitude of that event is not affected, but its time distortion causes an alteration in its frequency content. Not only view, but print, sign, and annotate pdfs with the free adobe acrobat reader dc. Nmoigg detected in csf in seronegative neuromyelitis. Introduction neuromyelitis optica spectrum disorders nmosd, previously known as devic disease or neuromyelitis optica nmo are inflammatory disorders of the central nervous system characterized by severe, immunemediated demyelination and axonal damage predominantly targeting optic nerves and spinal cord the epidemiology, pathogenesis, clinical manifestations, diagnosis, treatment. In a constant velocity earth, the nmo correction would take the asymptote of the hyperbola family and move it up to. Neuromyelitis optica nmo is a rare relapsing autoimmune disease of the central nervous system which is sometimes found in association with other autoimmune disorders including sjogrens syndrome. Nmoigg detected in csf in seronegative neuromyelitis optica. Velocity analysis and nmocorrection until now we have only discussed data processing methods that improve the signal of each separate trace.
Figure 1 shows the difference between the sorting of surface seismic and vsp data. The static anomalies distort first, and most directly, the estimation of stacking velocities for the nmo correction. Stretchafree generalized normal moveout correction wiley online. If you have an nmo antenna from manufacturer a, it will fit an nmo mount from manufacturer b or r. This disambiguation page lists articles associated with the title nmo. Nonstretching nmo correction of prestack timemigrated. Jul 14, 2015 neuromyelitis optica nmo is an inflammatory cns disorder distinct from multiple sclerosis ms. The nmo operation is an interesting example of many general.
We will now sum different traces, also called stacked, to improve the signaltonoise ratio and to decrease the am ount of data which will be proc essed to obtain an image of the subsurface. The effects of nmo stretch and offset dependent tuning on the estimates of avo inversion and analysis may be quantified by an analytic expression. If an internal link led you here, you may wish to change the link to point directly to the. In that case the fit accuracy parameter controls how closely the td table is honoured. Once considered to be a monophasic illness defined by the cooccurrence of acute bilateral visual loss and longitudinally extensive myelitis, 1 nmo is now recognized as a predominantly relapsing condition in which these index events may be separated by years and, in. Nmo is an autoimmune disorder with features similar to multiple sclerosis ms, most notably the occurrence of one or more clinical episodes of optic neuritis in combination with myelitis1,3 in nmo, these episodes are usually more acute and severe than in ms at one time nmo was considered a severe form of ms. The same algorithm used for forward nmo correction was also applied for inverse nmo correction. Neuromyelitis optica nmo is a rare autoimmune disorder, distinct from multiple sclerosis, causing inflammatory lesions in the optic nerves and spinal cord. With the expansion of our mission, they now have a home at the rocky mountain ms center and receive excellent. This is the major short come of the conventional me thod. By bn chen, c olsson, df sharrad and simon jonathan brookes download pdf. As a result, the immune system attacks these tissues, making proteins called antibodies and recruiting immune system cells that can harm otherwise healthy parts of.
The recent discovery of an autoantibody in patients with nmo that targets the water channel protein aquaporin 4 antinmo has changed the conception of this disease 3 6. Conventional and advanced imaging in neuromyelitis optica. The first function ill define performs the nmo correction on a given cmp gather. On the left is a field trace with some arbitrary offset and one reflection event. The bottom left panel of figure 8 shows the inversenmo corrected cmp gather. Mar 24, 2009 neuromyelitis optica nmo is an inflammatory and demyelinating disease characterized by recurrent attacks of optic neuritis on and longitudinally extensive transverse myelitis letm. View notes nmocorrectionformuladerivation from geology 306 at rutgers university. Nmo correction from surface based on the above equation reduces errors introduced in the statics correction, describes ray travel path more accurately, thus it has improved stacked images. Finally, the bottom right panel of figure 8 shows the difference between the original data and the inversenmo result. We consider reflections from layers, which we process by normal moveout correction nmo. Even though tuning is inherent in the data before nmo correction, its effect on avo is more obvious on nmo corrected data. Except for the obvious effect of the nmo stretch mute. This is reflected both by broadly consistent velocity models figs 2 c,d and 6 c,d and in the shapes of corrected traveltime curves, which show very similar residual moveout compare fig. Even though tuning is inherent in the data before nmo correction, its effect on avo is more obvious on nmo corrected.
The waveform of an event in this area is stretched to a longer period as the nmo correction is applied yilmaz, 2001. Moveout correction of pure pwave arrivals after the vertical component data is sorted into the receiver domain, equation a10. Finally, the bottom right panel of figure 8 shows the difference between the original data and the inverse nmo result. Nmo assumes the reflection comes from a horizontal interface is shown in the middle inset figure. Normal moveout correction and vspcdp transformation. Automatic nmo correction and velocity estimation by a feedforward neural network carlos calder. Find, read and cite all the research you need on researchgate. Neuromyelitis optica nmo is a severe demyelinating disease that typically affects the optic nerve and the spinal cord in a monophasic or recurrent manner 1, 2. Just like a pl259 from any manufacturer will fit your radio designed to use a pl259. We present the case of a middle aged female with sjogrens syndrome ss and neuromyelitis optica spectrum disorders nmosd who had a rapidly declining neurological illness.
Trace crossequalization functionality that is used to correct small misalignments in 3d seismic volumes prior to further analysis. Our implementation has many controls to avoid jumps and cycle skips. Pdf while in the past, in the context of stacking, traveltime moveout was. Summary in this paper we present a new method of normal moveout nmo correction called local stretch zeroing lsz method that avoids nmo stretch.
Coupled with the degrading action of wavelet stretching is offset dependent tuning for thin beds. Pdf normal moveout nmo correction is routinely applied to traces of each. Nmo is an autoimmune chronic inflammatory disorder of cns. In this study, we present a stretch free nmo correction method. The bottom left panel of figure 8 shows the inverse nmo corrected cmp gather. Based on the assumption that, in a cmp gather, reflection traveltimes as a function of offset follow hyperbolic trajectories, the process of nmo correction removes the moveout effect on traveltimes. Pdf a generalized view on normal moveout researchgate. There youll see that we can correct the measured traveltime of a reflected wave t at a given offset x to obtain the traveltime at normal incidence by applying the following equation. Residual moveout correction time variant event alignment estimates and applies time shifts between neighbouring traces in a gather to maximize tracetotrace correlations in a moving vertical window. Manuscript received by the editor 15 december 2011.
The method improves the conventional procedure by eliminating of sample interpolation and optimally selection of mute zone. Intrastriatal injection of interleukin1 beta triggers the formation of neuromyelitis opticalike lesions in nmoigg seropositive rats by maja kitic, sonja hochmeister, isabella wimmer, jan bauer, tatsuro misu, simone mader, markus reindl, kazuo fujihara, hans lassmann and monika bradl. Objective of nmo correction is to resample a finiteoffset trace in a cmp. Neuromyelitis optica nmo national multiple sclerosis society. If there is no td table or it is not desired to use it, a single timedepth pair can be entered manually and the. Commsta nmo, a united states coast guard communication station in honolulu, hawaii. The nmocorrection is applied for a cmp using different constant velocities. Mechanisms of white matter in multiple sclerosis and. Patients with these diseases, which share traits with multiple sclerosis and tend to be rare, often find themselves without a medical home. Nmo correction is usually considered in a hyperbolic equation where t x, is travel time, related to the x, offset between the source and the receiver, t0, twoway zero offset travel time, and vnmo, is nmo velocity which estimates the rootmeansquare rms velocity in a case of horizontal stratified earth.
Improving avo fidelity by nmo stretching and offset dependent. Avo analysis in the presence of nmo stretch and offset. Neuromyelitis optica nmo is an inflammatory cns disorder distinct from multiple sclerosis ms. Can make synthetic with no nmo correction for offset synthetics but not for angle synthetics if a td table exists in the well it can be used. An autoantibody nmo igg against aquaporin4 aqp4, a water channel expressed on astrocytes is thought to be causative. Neuromyelitis optica nmo is a severe inflammatory demyelinating disorder of the cns that is distinct from multiple sclerosis. Nmo stretching the nmo correction maps the data in a cdp gather from the x,tx plane to the x,t nmo x plane using equation 3b.
The wavelet deformation observed after applying a normal moveout nmo correction, in the case of a hyperbolic common. Sensory innervation of the guinea pig colon and rectum compared using retrograde tracing and immunohistochemistry. A function of time and offset that can be used in seismic processing to compensate for the effects of normal moveout, or the delay in reflection arrival times when geophones and shotpoints are offset from each other. Introduction neuromyelitis optica spectrum disorders nmosd, previously known as devic disease or neuromyelitis optica nmo are inflammatory disorders of the central nervous system characterized by severe, immunemediated demyelination and axonal damage predominantly targeting optic nerves and spinal cord. Cvs constant velocity stacks similar to the cvpmethod the data is nmocorrected. It is typically used to align timelapse seismic data, multiazimuth stacks or angle stacks residual nmo correction. Prestack pro getting started guide sharp reflections. Timevariant windows to adapt to changing seismic bandwidth from shallow to deep. Using this nmo velocity, we can produce an nmo stack. We present the case of a middle aged female with sjogrens syndrome ss and neuromyelitis optica spectrum disorders nmosd who had a rapidly declining neurological illness that responded to. The results of the different velocities are compared and the velocity that results in a flattening of the hyperbolas is the velocity for a certain reflector. Automatic nmo correction and velocity estimation by a.
Differences in raypaths can be caused by errors in elevation corrections, especially in the area with great changes of elevation. In its simplest form, nmo is based on the pythagorean relation. Nmo correction is usually considered in a hyperbolic equation where tx, is travel time, related to the x, offset between the source and the receiver, t0, twoway zero offset travel time, and. Similar to conventional velocity analysis, a coherencedriven scan for the fit optimizing tshift leads to automatable nmo correction and likewise. By bn chen, c olsson, df sharrad and simon jonathan brookes download pdf 1 mb.
The method is based on a predefined number of nmo velocity sweeps using linear vertical interpolation of different nmo velocities at each. Because both the velocity and t 0 increase downward, the nmo correction applied for a later t 0 will be smaller than that applied at an earlier t 0. Velocity analysis and nmo correction until now we have only discussed data processing methods that improve the signal of each separate trace. As explained, the nmo is a 1 18 inch threaded connector.
Unlike its role in the conventional normal moveout nmo, velocity is not a requirement for the moveout correction but rather a data attribute derived from the local slopes and mappable directly to the appropriate zerooffset time. Effective application of nmo correction depends mainly on four factors. Sjogrens syndrome and neuromyelitis optica spectrum. Organize all the stacks in a matrix and plot the result. The effective application of normal moveout correction processes mainly depends on four factors. It features chromeplated brass mount, heavyduty base, a goldplated plunger type contact pin. Nmo is an autoimmune chronic inflammatory disorder of.
Local stretch zeroing nmo correction search and discovery. Data from the blackfoot 3c3d vsp survey corrected to normal incidence time after amplitude semblance analysis show good correlation with that corrected using. Except for the obvious effect of the nmostretch mute. View, print, sign, and annotate pdfs with our free adobe acrobat reader. A generalized view on normal moveout geophysics seg library.
Automatic nmo correction and full common depth point nmo. Neuromyelitis optica nmo and nmo spectrum disorder nmosd, also known as devics disease, is an autoimmune disorder in which white blood cells and antibodies primarily attack the optic nerves and the spinal cord, but may also attack the brain. Accurate elevation and normal moveout corrections of. Intrastriatal injection of interleukin1 beta triggers the formation of neuromyelitis opticalike lesions in nmo igg seropositive rats by maja kitic, sonja hochmeister, isabella wimmer, jan bauer, tatsuro misu, simone mader, markus reindl, kazuo fujihara, hans lassmann and monika bradl. Peripheral production of the antibody is triggered by an unknown process in genetically susceptible individuals. Neuromyelitis optica nmo is an inflammatory and demyelinating disease characterized by recurrent attacks of optic neuritis on and longitudinally extensive transverse myelitis letm. Looking for online definition of nmo or what nmo stands for.
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