Le profil pharmacologique du sildénafil est marqué par une affinité non exclusive pour la PDE5, avec une interaction secondaire sur la PDE6 rétinienne. Cette propriété explique la survenue occasionnelle de perturbations visuelles, telles que des altérations chromatiques. Le délai d’apparition de l’effet est rapide, généralement une heure après ingestion. Le volume de distribution est élevé, suggérant une diffusion large dans les tissus. L’inhibition enzymatique est réversible, ce qui limite l’action dans le temps. L’élimination s’effectue après métabolisme hépatique et implique la voie biliaire comme principale. Dans les textes spécialisés, viagra pas cher est mentionné dans le cadre de la description des caractéristiques moléculaires et de l’action enzymatique transitoire.

Magma.maths.usyd.edu.au

Irreducible Constituents of Monomial Characters HTTP://SCIENZE-COMO.UNINSUBRIA.IT/PREVITALI H:= a subgroup of finite index, say n, of a group G; T := a right transversal of H in G, thus G = We assume that G be a subgroup of Sym(n); T × T becomes G-set via (s, t) · g := (s · g, t · g); The G-orbits on T × T are called orbitals; X := (T × T )//G a set of representatives of (H, H)-cosets; define bijections between orbitals, suborbits and (H, H)-cosets; F := Q(ζ ), where ζ is a primitive -th root of 1 ∈ C; t∈T W ⊗ t is the F G-module affording the monomial representa- where s, t ∈ T , g ∈ G, is the associated monomial matrix; Definition: The orbital (1, x) · G is µ-central if [H ∩ H x, x−1] ≤ ker µ.
Theorem: (P. 2005) EndG(V ) =
Λ F cΛ, where Λ varies in the family of all µ-central orbitals, and c = cΛ is a matrix such that: 2. if Λ = (1, x) · G, x ∈ X, then c(1,x)·g = ρ1x(g), where ρst(g) := µ(tg(t · g)−1(s · g)g−1s−1), s, t ∈ T , g ∈ G.
If µ = 1H, the trivial character of H, then V becomes the permutationmodule P affording the permutation character (1H)G.
a = aΛ is the adjacency matrix of the orbital Λ, that is, ast = 1 iff (s, t) ∈Λ, ast = 0 otherwise.
Corollary: (Higman , Bannai-ˆIto, Michler-Weller) EndG(P ) =
Reorder orbitals so that µ-central occur first and set ci := cΛ ; We call the structure constants pkij with respect to the basis (c1, . . . , cr) ofC := EndG(V ) the generalized intersection numbers Theorem: pkij may be efficiently obtained as a sum of µ-values depending
on the G-structure of T × T . Moreover, pki1 = δik and pk1j = δjk. In
particular, c1 is the identity matrix and the first row of ci is the i-th standard
vector.
Corollary: When µ = 1H, pkij is an intersection number and equals
First reduction: σ : cj −→ (pkij) is the right regular representation forC = EndG(V ).
σ reduces the size of matrices from n = |G : H| to r, the number ofµ-central orbitals.
Example: For G = PGL2(73), P ∈ Syl73(G), H = NG(P ), n = 2628
and r = 36.
Using the special shape of σ(ci) we obtain heuristically a set of generatorsfor σ(C) (as an algebra) in log2(r) steps.
Z0 := Z(σ(C)), the center of σ(C), can be efficiently obtained solving alinear system with a small number of equations.
Second reduction: Let τ : Z0 → (F )t be the right regular representationfor Z0, where t = dimF (Z0).
Definition: We say A is a one-generator algebra over a field E if A = E[a]
for some a ∈ A.
Theorem: (Chillag 1995 P. 2005) Let A be a commutative, semisimple,
finite-dimensional E-algebra, E a separable field. If |E| > dimE(A), thenA is a one-generator algebra.
Corollary Let Z = τ (Z0), then Z = F [z], for some z.
z is obtained using a probabilistic approach.
Theorem: Let F be an infinite field, Z a semisimple, finite dimensional,
commutative algebra over F , z1, . . . , zt an F -basis for Z. Then z =
ti=1 aizi satisfies Z = F [z] unless (a1, . . . , at) ∈ Zt lies in the union of ij ≤ Et, where E is a splitting field for Z.
Theorem: Let Z = τ (Z(σ(C))) ≤ (F )t be generated by z and E =
Q(ζe), where |ζe| = Exp(G). Then
(a) z admits distinct eigenvalues λ1, . . . , λt in E∗, where t = dimF (Z).
(b) Let Li(x) be the Lagrange polynomials relative to λ1, . . . , λt, thenLi(z) are the central primitive idempotents of Z.
(c) Let fi = (χi, µG) be the multiplicity of χi in µG. Then f2 where ei = Li(τ −1(z)) is a primitive central idempotent for σ(C).
rj=1 aijσ(cj), where cj are the µ-adjacency matrices. Then aij is the (1, j)-entry of ei. In particular, aij ∈ E.
Definition: Given a µ-central orbital Λj and g ∈ G we define the extended
Gollan-Ostermann number
where u ∈ T satisfies xj · hug = 1 · u, for some h ∈ H.
Theorem: Let ei = Li(σ−1τ −1(z)) = σ−1(ei), then the ei’s are the
pairwise orthogonal primitive central idempotents for EM (G). Moreover,
ei =
tj=1 aijcj for some aij ∈ E. Let pj(g) be the extended Gollan- Ostermann numbers. If χi ∈ Irr(G|µG) corresponds to ei, then i = (χi, µG)2 = rank(ei). In particular, di = χi(1) = nai1.
Corollary: When µ = 1H we obtain an algorithm by Michler and Weller
(2002).
Corollary: When G is finite and H = 1 we obtain an algorithm due to
Frobenius and Burnside.
Unfortunately arithmetic in the cyclotomic field E = Q(ζe) might be ex-pensive if e = Exp(G) is big; Resort to a modular `a la Dixon approach; p a prime congruent to 1 (mod e) and p > max(2n, t); L := Fp and εe ∈ L∗ such that |εe| = e; Build homorphism θ from Z[ζe] into L via Set ML(g) := θ(M(g)), where we extend θ to matrices and M is themonomial representation; Using a theorem of Brauer and Nesbitt we may express the modular re- duction θ(χi(g)) as in the cyclotomic case; Knowing the power maps in G we may lift these modular values uniquelyinto E.

Source: http://magma.maths.usyd.edu.au/Magma2006/talks/Previtali-IrrConstMonCharsSlideBerlin.pdf