RNA molecules in living cells form what look like liquid droplets formed by liquid/liquid phase separation. But unlike the molecules in conventional phase separating mixtures, RNA molecules are transported by molecular motors that consume energy and so are out of equilibrium. Motivated by this we consider what sort of simple rules for the dynamics of model mRNA molecules lead to liquid/liquid p...

For the large sparse block two-by-two real nonsingular matrices, we establish a general framework of practical and efficient structured preconditioners through matrix transformation and matrix approximations. For the specific versions such as modified block Jacobi-type, modified block GaussSeidel-type, and modified block unsymmetric (symmetric) Gauss-Seidel-type preconditioners, we precisely de...

Inhomogeneities in myocardial structure and action potential duration (APD) lead to dispersion of APD throughout the heart. APD gradients in the range of 20-125 ms/cm have been reported to produce functional block. In this study, a multicellular fiber model was used to examine the effect of structural and ionic inhomogeneities on the likelihood of premature stimuli to produce functional block. ...

Fig. 3.?Electrocardiogram, showing apparent bundle branch block (right-sided) and ventricular extra-systoles. The short duration' of P-R and the widening of the QRS complexes are characteristic. (Date of tracing : 22-4-40.) Fig. 3.?Electrocardiogram, showing apparent bundle branch block (right-sided) and ventricular extra-systoles. The short du of P-R and the widening of the QRS complexes are c...

A permanent pacemaker was implanted in an 80-year-old patient with complete heart block. The electrode had to be changed six times (endocardial, five and epicardial, one) due to a progressive rise in threshold with recurrent exit block. A porous, steroid eluting, endocardial electrode was implanted and has given 27 months of excellent service. This lead may be ideal for patients who have a prog...

A study has been made of the modifications of the shape of a nerve action potential dependent upon the placement of the two electrodes, always necessary for a lead. In a classic diphasic lead separation of the electrodes brings out, in addition to a separation of the phases, the appearance of a positive deflection traceable to the passage of an impulse between the electrodes. This phenomenon, c...

Routine implantation of pacemakers and implantable cardioverter defibrillators is not commonly associated with complications. However, in some cases we see misplacement of pacemaker leads which is most often related to the presence of underlying cardiac anomalies. We report the case of misplacement of a pacemaker lead into the left ventricle of a 56-year-old patient paced in VVI/R mode and with...

Permanent His bundle pacing (HBP) is a physiological alternative to right ventricular pacing. Acute injury to the His bundle can occur during permanent HBP in the form of transient or permanent bundle branch blocks. Observations of mechanical injury to the His bundle during HBP lead fixation and electrophysiological response to HBP provides additional mechanistic insights into the pathology of ...