Slow-beat

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The spin echo decay under homonuclear couplings only (as opposed to decay by relaxation) is often called the slow beat, even if no periodic modulation is observed. A real beat usually occurs when a scalar coupling between unlike nuclei is the main decay mechanism, e.g., for Pt in dilute bulk alloys. Dipolar coupling usually leads to a monotonic decay, which initially is Gaussian (at the origin all its odd time derivatives are zero) and becomes more exponential at longer times. 

VMenthyl ester needles from EtOH. M.p. 58-62° (slow beat.), [a] — 89 1° in CgHg. 

Bradycardia Bradycardia is a slow heart rate (60 beats per minute or slower) that does not meet the body s metabolic demands. Symptoms of bradycardia include dizziness, extreme fatigue, shortness of breath, or fainting spells. This can be compared to tachycardia, which is an extremely rapid heart rate, usually signified by a pulse of over 100 beats per minute. Adults usually have a resting heart rate of 70-80 beats per minute, although well-trained athletes can have resting rates in the 50 s or 60 s. Newborn babies have a normal heart rate of 120-160 beats per minute. A slowed heart rate can lead to a variety of other problems. First aid treatment may include administration of oxygen. 

Nonciliated cells separate fields of ciliated epithelial cells from each other. Synchronized ciliary movement, with a beat frequency in human proximal airways under normal conditions of 8-15 EIz, propels mucus along the mucociliary escalator at a rate of up to 25 mm/min. Beat frequencies appear to slow to roughly 7 Hz in more distal airways. Cilia move in the same direction and in phase within each field but cilia in adjacent fields move in slightly different directions and are phase shifted. These beat patterns result in metachronal waves that steadily move mucus at higher velocities ( -12-18 mm/min) than would be achievable by summing the motion of individual cilia. 

In addition to the MD method, a wealth of Monte Carlo methods is used also at the atomistic level [6]. They use essentially the same models, force fields, for polymers. Their main advantage, however, is that by introduction of clever moves one can beat the slow physical dynamics of the systems and can run through phase space much faster than by MD. These methods are still in their infancy, but will certainly become more important. 

The process of reentry is depicted in Fig. 6-3.4 Under normal circumstances, when a premature impulse is initiated, it cannot be conducted in either direction down either pathway because the tissue is in its absolute refractory period from the previous beat. A premature impulse may be conducted down both pathways if it is only slightly premature and arrives after the tissue is no longer refractory. However, when refractoriness is prolonged down one of the pathways, a precisely timed premature beat may be conducted down one pathway, but cannot be conducted in either direction in the pathway with prolonged refractoriness because the tissue is still in its absolute refractory period (Fig. 6-3, panel la).4 When the third condition for reentry is present, that is, when the velocity of impulse conduction in the other pathway is slowed, the impulse traveling forward down the other pathway still cannot be conducted. However, because the impulse in the other pathway is traveling so slowly, by the time it circles around and travels upward down the other pathway, that pathway is no longer in its absolute refractory period, and now the impulse may travel upward in that pathway. In other words,... 

The sinoatrial (SA) node is located in the wall of the right atrium near the entrance of the superior vena cava. The specialized cells of the SA node spontaneously depolarize to threshold and generate 70 to 75 heart beats/ min. The "resting" membrane potential, or pacemaker potential, is different from that of neurons, which were discussed in Chapter 3 (Membrane Potential). First of all, this potential is approximately -55 mV, which is less negative than that found in neurons (-70 mV see Figure 13.2, panel A). Second, pacemaker potential is unstable and slowly depolarizes toward threshold (phase 4). Two important ion currents contribute to this slow depolarization. These cells are inherently leaky to sodium. The resulting influx of Na+ ions occurs through channels that differ from the fast Na+ channels that cause rapid depolarization in other types of excitable cells. Toward the end of phase... 

Similar to the TCAs, there have been reports of sudden deaths reported in children with ADHD who were taking both clonidine and a psychostimulant. For this reason, precautionary measures should be taken before starting a patient (particularly a child) on clonidine. A baseline EKG should be obtained before starting the medication. If the EKG shows any problems in the heart s electrical conduction system, then clonidine should not be used. In addition, if the patient has any history of known heart problems, fainting spells, slow heart rate (i.e., less than 60 beats per minute), or low blood pressure, we would recommend avoiding clonidine. When clonidine is used, the patient s blood pressure and pulse rate should be measured at each office visit, and an EKG should be periodically repeated. 

Beginning vertical strokes on the lower case t that go down and curve to the right (no beginning upstroke). This person wants people to stop beating around the bush and get to the point. Direct people don t like to be slowed down. 

Their efficacy in many illnesses is explained by the competitive binding of )3-adrenore-ceptors in the autonomic nervous system by basically any of the employed drags of the l-aryloxy-3-aminopropanol-2 class, which result in reduction of heart rate and strength of cardiac beats, slowing of atrioventricular conductivity, reduction of the level of renin in the plasma, and reduction of blood pressure. The main effects of 8-adrenoblockers are expressed at the level of the vasomotor center in the hypothalamus, which result in a slowing of the release of sympathetic, tonic impulses. Included in the main group of... 

Bradycardia. Brachycardia hradyrhythmia oligocardia slowness of the heartbeat under 60 beats per minute. 

Bradycardia can be due to depressed sinus automaticity and AV block. Bradyarrhythmias manifest as slow heart rate (less than 50 to 60 beats per minute in sleep). Depressed SA nodal automaticity lead to missing beats and bradycardia. AV block can be due to high vagal activity and side effect of certain drugs e.g. digitalis and P-blockers. 

Ventricular and supraventricular tachycardia (especially those due to re-entry phenomena), atrial fibrillation and flutter (can convert recent-onset fibrillation or flutter to sinus rhythm) Paroxysmal supraventricular tachycardia, atrial or ventricular premature beats, atrial fibrillation, or flutter (slows ventricular rate)... 

Strophanthus divaricatus (Lour.) Hook, et Arn. Yang Guo Nau (seed) Divaricoside, divostroside, sinoside, sinostroside, caudoside, caudostroside, sarmutoside.33 This herb is toxic. Cardiac stimulating action causing an increase of myocardiac contractility, slow the heart beat. 

Symptoms contracted pupils, diarrhea, bradycardia (slowed heart beat), nausea,... 

In normal individuals, the effects of toxic doses of digitoxin are extreme slowing of the heart (bradycardia) and atrial fibrillation. In cardiac patients, however, the effects could be fatal with ventricular fibrillation, but certainly arrythmias and extra beats will occur. 

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