Magnetically guided fast electrons in cylindrically compressed matter

Fast electrons produced by a 10 ps, 160 J laser pulse through laser-compressed plastic cylinders are studied experimentally and numerically in the context of fast ignition. K(α)-emission images reveal a collimated or scattered electron beam depending on the initial density and the compression timing. A numerical transport model shows that implosion-driven electrical resistivity gradients induce strong magnetic fields able to guide the electrons. The good agreement with measured beam sizes provides the first experimental evidence for fast-electron magnetic collimation in laser-compressed matter.     

Determination of free salsolinol concentrations in human urine using gas chromatography-mass spectrometry.

The urine concentrations of free salsolinol were determined in six healthy volunteers, using a gas chromatographic-mass spectrometric method with electron-capture negative-ion chemical ionization after derivatization with pentafluoropropionyl anhydride. The sensitivity of this method allows the quantification of salsolinol concentrations of 0.55 pmol/ml. The synthesis of [2H4]salsolinol from dopamine and [2H4]acetaldehyde via a Pictet-Spengler condensation is described; [2H4]salsolinol was used as the internal standard for salsolinol quantification. The urine concentrations of free salsolinol ranged from ca. 1 to 6 pmol/ml.     

Electrical transport and magnetic ordering in R 2Ti3Ge4 (R=Dy, Ho and Er) compounds

New R ₂Ti₃Ge₄ (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize in the parent, Sm₅Ge₄-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series. The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects.     

Mechanisms of inter- and intramolecular communication in GPCRs and G proteins

This study represents the first attempt to couple, by computational experiments, the mechanisms of intramolecular and intermolecular communication concerning a guanidine nucleotide exchange factor (GEF), the thromboxane A2 receptor (TXA2R), and the cognate G protein (Gq) in its heterotrimeric GDP-bound state. Two-way pathways mediate the communication between the receptor-G protein interface and both the agonist binding site of the receptor and the nucleotide binding site of the G protein. The increase in solvent accessibility in the neighborhoods of the highly conserved E/DRY receptor motif, in response to agonist binding, is instrumental in favoring the penetration of the C-terminus of Gqalpha in between the cytosolic ends of H3, H5, and H6. The arginine of the E/DRY motif is predicted to be an important mediator of the intramolecular and intermolecular communication involving the TXA2R. The receptor-G protein interface is predicted to involve multiple regions from the receptor and the G protein alpha-subunit. However, receptor contacts with the C-terminus of the alpha5-helix seem to be the major players in the receptor-catalyzed motion of the alpha-helical domain with respect to the Ras-like domain and in the formation of a nucleotide exit route in between the alphaF-helix and beta6/alpha5 loop of Gqalpha. The inferences from this study are of wide interest, as they are expected to apply to the whole rhodopsin family, given also the considerable G protein promiscuity.     

Regulating Hartshorne’s connectedness theorem

The tensor square conjecture states that for \(n \ge 10\), there is an irreducible representation V of the symmetric group \(S_n\) such that \(V \otimes V\) contains every irreducible representation of \(S_n\). Our main result is that for large enough n, there exists an irreducible representation V such that \(V^{\otimes 4}\) contains every irreducible representation. We also show that tensor squares of certain irreducible representations contain \((1-o(1))\)-fraction of irreducible representations with respect to two natural probability distributions. Our main tool is the semigroup property, which allows us to break partitions down into smaller ones.     

Two-point b.v.p. for multivalued equations with weakly regular r.h.s.

A two-point boundary value problem associated to a semilinear multivalued evolution equation is investigated, in reflexive and separable Banach spaces. To this aim, an original method is proposed based on the use of weak topologies and on a suitable continuation principle in Fréchet spaces. Lyapunov-like functions are introduced, for proving the required transversality condition. The linear part can also depend on the state variable x and the discussion comprises the cases of a nonlinearity with sublinear growth in x or of a noncompact valued one. Some applications are given, to the study of periodic and Floquet boundary value problems of partial integro-differential equations and inclusions appearing in dispersal population models. Comparisons are included, with recent related achievements.     

Aldolase activity of serum albumins

Bovine and human serum albumins catalyze the aldol reaction of aromatic aldehyedes and acetone, with saturation kinetics and moderate and opposite enantioselectivity. The reaction occurs at the binding site in domain IIa, and is inhibited by warfarin. Kinetic data are consistent with an enamine mechanism. The activity is conserved in a 103 aminoacid peptide derived from the albumin sequence.