A typical feature of sinoatrial (SA) nodal pacemaker cells is the presence of an ionic current that activates upon hyperpolarization. The contribution of this hyperpolarization-activated current, If, which is also known as the ‘funny current’ or ‘pacemaker current’, to the spontaneous pacemaker activity of SA nodal cells remains a matter of intense debate. We used experimentally recorded action...

The SCN5A gene encodes the pore-forming α-subunit of the ion channel that carries the cardiac fast sodium current (INa). The 1795insD mutation in SCN5A causes sinus bradycardia, with a mean heart rate of 70 beats/min in mutation carriers vs. 77 beats/min in non-carriers from the same family (lowest heart rate 41 vs. 47 beats/min). To unravel the underlying mechanism, we incorporated the mutatio...

Abstract In this note, we make a step towards the classification of toric surfaces admitting reducible Severi varieties. We provide two families The first family is general, and obtained by quotient construction. second exceptional, corresponds to certain narrow polygons, which call kites. introduce types invariants that distinguish between components varieties, allow us lower bounds on numbers...

We study the homogeneous irreducible Severi-Brauer varieties over an Abelian variety $A$. Such objects were classified by Brion, \cite{Bri}. Here we interpret that result within context of cubical structures and biextensions for certain $\G_m$-torsors finite subgroups Our results can be seen as instance theory developed Breen, \cite{Breen:1983}, Moret-Bailly, \cite{Moret-Bailly}.

We provide an alternative proof that the Chow group of $1$-cycles on a Severi--Brauer variety associated to biquaternion division algebra is torsion-free. There are three proofs this result in literature, all which due Karpenko and rely clever use $K$-theory. The we give here, by contrast, geometric uses degenerations quartic elliptic normal curves.