Spin-Echo Experiment with NMR Spectra only Partially Narrowed by an Insufficiently Fast Motion

2003 ◽  
Vol 68 (7) ◽  
pp. 1193-1205
Author(s):  
Jaromír Jakeš

The spin-echo experiment on a spin system with only partial motional narrowing and an exponential field autocorrelation function is considered. The pattern of the intensity decrease in the echo spectra depends on the ratio τ/τc of the time delay τ in the echo experiment to the correlation time τc of the narrowing motion. With the large ratios (fast motion), the decrease is the same as in the case of extreme narrowing; to obtain undistorted T2 values, the ratio should be at least several units in the single-echo experiment and at least few decades in the multiple-echo experiment. With the small ratios (slow motion), the logarithmic decrease depends non-linearly on τ, and the T2 value found by the linear least-squares adjustment is much longer than that obtained from the extreme narrowing approximation. At very small ratios, the multiple echo yields about 3τc/(ωpτ)2 for T2 as compared with 1/(ωp2rc) obtained from the extreme narrowing approximation; ωp2 is the second moment of the Gaussian line being narrowed. The expression for T2 in the multiple spin echo is similar to that previously found for T2e in the solid multiple spin echo. The echo experiment changes the line shape, which at large τ/τc approaches the Lorentzian one. The case of a multiexponential field autocorrelation function is also briefly considered.

1988 ◽  
Vol 110 (4) ◽  
pp. 382-388
Author(s):  
Liang-Wey Chang ◽  
James F. Hamilton

This paper presents a method for simulating systems with two inertially coupled motions, i.e., a slow motion and a fast motion. The equations of motion are separated into two sets of coupled nonlinear ordinary differential equations. For each time step, the two sets of equations are integrated sequentially rather than simultaneously. Explicit integration methods are used for integrating the slow motion since the stability of the integration is not a problem and the explicit methods are very convenient for nonlinear equations. For the fast motion, the equations are linear and the implicit integrations can be used with guaranteed stability. The size of time step only needs to be chosen to provide accuracy of the solution for the modes that are excited. The interaction between the two types of motion must be treated such that secular terms do not appear due to the sequential integration method. A lumped model of a flexible pendulum will be presented in this paper to illustrate the application of the method. Numerical results for both simultaneous and sequential integration are presented for comparison.


JOGED ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 547-562
Author(s):  
Jumiati Jumiati

Upacara Belian merupakan ritual pengobatan, membayar hutang, dan pembersihan kampung yang terdapat di Kabupaten Paser. Upacara Belian ini dilatar belakangi oleh sistem kepercayaan terhadap kekuatan-kekuatan gaib. Inti upacara Belian berupa gerak-gerak dan mantra-mantar. Gerak yang dihadiran pada upacara Belian ini menimbulkan inspirasi bagi seorang seniman bernama Irusmiati untuk mentransformasikan upacara Belian menjadi tari Gitang Paser.Gerak dalam tari Gitang ini terinspirasi dari dua motif gerak yang dilakukan oleh Mulung yaitu perambut (gerak lambat), kerkesek (gerak cepat) serta bunyi gitang. Kedua unsur ini dikembangkan dalam irama, ritme dan penggunaan tenaga sehingga menjadikannya lebih dinamisUntuk mengtahui aspek apa saja yang bertransformasi pada upacara Belian ke dalam tari Gitang Paser maka peneliti menggunakan konsep yang dikemukaka n oleh Djoharnurani yang mengemukakan bahwa proses transfomasi dapat dilalui dalam tiga tahap yaitu; 1) tahap pemahaman dan penghayatan makna; 2) tahap resepsi; dan 3) tahap tindak resepsi. Pada butir pertama adalah pemahaman dan penghayatan makna terhadap nilai-nilai yang ditransformasikan. Butir kedua adalah resepsi yang berarti penerimaan memang salah satu aspek yang ada dalam proses transformasi. Kemudian pada aspek tindak resepsilah transformasi membawa rangsangan idesional atau gagasan untuk membuat suatu yang baru. Maka melalui dari tiga tahap ini lah hasil transformasi antara upacara Belian dan tari Gitang Paser dari aspek rasa, bentuk, dan makna masing-masing bisa berubah, masih nampak ataupun menjadi samar-samar.Hasil analisis di atas menunjukkan adanya suatu perubahan bentuk penyajian, makna serta fungsi upacara Belian ke dalam tari Gitang. Hasil yang didapat memberikan nilai yang bersifat mengembangkan. Salah satu pengembangan yang dapat dilihat dari bentuk penyajian yaitu gerak, gerak pada upacara Belian lebih sederhana hanya menggunakan dua motif yaitu perambut dan kerkesek ketika berubah maka gerak tersebut lebih dinamis karena memiliki berbagai macam motif. Pengembangan yang terjadi pada bentuk penyajian memberikan dampak perubahan pula pada fungsi. Fungsi pada upacara lebih pada ritual pengobatan ketika berubah menjadi tari Gitang fungsi tersebut sebagai hiburan semata tanpa meninggalkan suasana magis. Ketika bentuk dan fungsi berubah mengakibatkan perubahan makna yang terjadi pada tari Gitang yaitu hilangnya kepercayaan masyarakat setempat terhadap upacara Belian.  Belian ceremony is a ritual of treatment, debt repayment, and cleaning of villages located in Paser District. This Belian ceremony is based on a belief system of supernatural powers. The core of the Belian ceremony is in the form of movements and mantras. The movement attended at this Belian ceremony inspired an artist named Irusmiati to transform the Belian ceremony into a Gitang Paser dance. Motion in Gitang dance is inspired by two motive motifs performed by Mulung that is perambut (slow motion) kerkesek (fast motion) and the sound of gitang. It is developed in rhythm, rhythm and use of power making it more dynamic. To know what aspects are transformed at Belian ceremony into Gitang Paser dance then the researcher uses the concept proposed by Djoharnurani which shows that the process of transfomation can be passed in three stages that is 1) Stage of understanding and appreciation of meaning 2) the reception stage and 3) stage of action. In the first point is the understanding and appreciation of the meaning of values that are transformed. The second point is acceptance which means acceptance is one of the aspects that exist in the transformation process. Then on the aspect stage of action transformation brings about an ational stimulus or an idea to create a new one. So through these three stages is the result of the transformation between Belian ceremonies into Gitang Paser dance from the aspect of taste, form, and meaning of each can change, remain visible or become blurred. The results of the above analysis indicate a change in the form of presentation, meaning and function of Belian ceremony into Gitang dance. The results obtained provide a value that is developing. One of the developments that can be seen from the form of motion presentation, motion at Belian ceremony is simpler by using only two motifs that is perambut and kerkesek When changed the motion is more dynamic because it has a variety of motives. The development that occurs in the form of presentation gives effect to changes also on the function. The function at this ceremony is more on the treatment ritual when it transforms into a Gitang dance function as a mere entertainment without leaving the magical atmosphere. When the form and function change resulted in a change of meaning that occurred in Gitang dance that is the loss of local belief in Belian ceremony. 


2009 ◽  
pp. 340-340-8
Author(s):  
B. L. Broadhead ◽  
M. L. Williams ◽  
J. J. Wagschal

2018 ◽  
Vol 30 (10) ◽  
pp. 1517-1531 ◽  
Author(s):  
Paolo A. Grasso ◽  
Elisabetta Làdavas ◽  
Caterina Bertini ◽  
Serena Caltabiano ◽  
Gregor Thut ◽  
...  

Motion information can reach V5/MT through two parallel routes: one conveying information at early latencies through a direct subcortical route and the other reaching V5 later via recurrent projections through V1. Here, we tested the hypothesis that input via the faster direct pathway depends on motion characteristics. To this end, we presented motion stimuli to healthy human observers at different velocities (4.4°/sec vs. 23°/sec) with static stimuli as controls while applying transcranial magnetic stimulation (TMS) pulses over V5 or V1. We probed for TMS interference with objective (two-alternative forced choice [2AFC]) and subjective (awareness) measures of motion processing at six TMS delays from stimulus onset (poststimulus window covered: ∼27–160 msec). Our results for V5–TMS showed earlier interference with objective performance for fast motion (53.3 msec) than slow motion (80 msec) stimuli. Importantly, TMS-induced decreases in objective measures of motion processing did correlate with decreases in subjective measures for slow but not fast motion stimuli. Moreover, V1–TMS induced a temporally unspecific interference with visual processing as it impaired the processing of both motion and static stimuli at the same delays. These results are in accordance with fast moving stimuli reaching V5 through a different route than slow moving stimuli. The differential latencies and coupling to awareness suggest distinct involvement of a direct (i.e., colliculo-extrastriate) connection bypassing V1 depending on stimulus velocity (fast vs. slow). Implication of a direct pathway in the early processing of fast motion may have evolved through its behavioral relevance.


1993 ◽  
Vol 07 (16n17) ◽  
pp. 2885-2907 ◽  
Author(s):  
FERENC MEZEI

Conventional resolution inelastic neutron scattering spectroscopy allows us to explore the behaviour of condensed matter essentially on the time scale of thermal atomic vibrations. By the application of the Neutron Spin Echo trick, which enables us to get around the Liouville theorem limitation of conventional methods, the resolution can be improved very substantially. This opened up the field for the study of a large variety of slow motion phenomena (critical slowing down, relaxation effects, disordered dynamics, soft matter), i.e. the investigation of processes on a mesoscopic time scale between microscopic collision times and macroscopic dynamics.


2001 ◽  
Vol 99 (11) ◽  
pp. 939-956
Author(s):  
DAISUKE KUWAHARA ◽  
TOSHIHITO NAKAI ◽  
JUN ASHIDA ◽  
SEIICHI MIYAJIMA

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