A momentum-space representation of Feynman propagator in Riemann-Cartan spacetime

We first construct generalized Riemann-normal coordinates by using autoparallels, instead of geodesics, in an arbitrary Riemann-Cartan spacetime. With the aid of generalized Riemann-normal coordinates and their associated orthonormal frames, we obtain a momentum-space representation of the Feynman propagator for scalar fields, which is a direct generalization of Bunch and Parker's works to curved spacetime with torsion. We further derive the proper-time representation in $n$ dimensional Riemann-Cartan spacetime from the momentum-space representation. It leads us to obtain the renormalization of one-loop effective Lagrangians of free scalar fields by using dimensional regularization. When torsion tensor vanishes, our resulting momentum-space representation returns to the standard Riemannian results.Comment: 12 page

Spin relaxation dynamics of quasiclassical electrons in ballistic quantum dots with strong spin-orbit coupling

We performed path integral simulations of spin evolution controlled by the Rashba spin-orbit interaction in the semiclassical regime for chaotic and regular quantum dots. The spin polarization dynamics have been found to be strikingly different from the D'yakonov-Perel' (DP) spin relaxation in bulk systems. Also an important distinction have been found between long time spin evolutions in classically chaotic and regular systems. In the former case the spin polarization relaxes to zero within relaxation time much larger than the DP relaxation, while in the latter case it evolves to a time independent residual value. The quantum mechanical analysis of the spin evolution based on the exact solution of the Schroedinger equation with Rashba SOI has confirmed the results of the classical simulations for the circular dot, which is expected to be valid in general regular systems. In contrast, the spin relaxation down to zero in chaotic dots contradicts to what have to be expected from quantum mechanics. This signals on importance at long time of the mesoscopic echo effect missed in the semiclassical simulations.Comment: 14 pages, 9 figure

Evidence of early multi-strange hadron freeze-out in high energy nuclear collisions

Recently reported transverse momentum distributions of strange hadrons produced in Pb(158AGeV) on Pb collisions and corresponding results from the relativistic quantum molecular dynamics (RQMD) approach are examined. We argue that the experimental observations favor a scenario in which multi-strange hadrons are formed and decouple from the system rather early at large energy densities (around 1 GeV/fm$^3$). The systematics of the strange and non-strange particle spectra indicate that the observed transverse flow develops mainly in the late hadronic stages of these reactions.Comment: 4 pages, 4 figure

Synthesis, structure and dioxygen reactivity of a bis(µ-iodo)dicopper(I) complex supported by the [N-(3,5-di-tert-butyl-2-hydroxybenzyl)-N,N-di-(2-pyridylmethyl)]amine ligand

The air-sensitive bis(µ-iodo)dicopper(I) complex 1 supported by [N-(3,5-di-tert-butyl-2-hydroxybenzyl)-N,N-di-(2-pyridylmethyl)]amine (L) has been prepared by treating copper(I) iodide with L in anhydrous THF. Compound 1 crystallizes as a dimer in space group C2/c. Each copper(I) center has distorted tetrahedral N2I2 coordination geometry with Cu–N(pyridyl) distances 2.061(3) and 2.063(3) Å, Cu–I distances 2.6162(5) and 2.7817(5) and a CuCu distance of 2.9086(8) Å. Complex 1 is rapidly oxidized by dioxygen in CH2Cl2 with a 1 : 1 stoichiometry giving the bis(µ-iodo)peroxodicopper(II) complex [Cu(L)(µ-I)]2O2 (2). The reaction of 1 with dioxygen has been characterized by UV-vis, mass spectrometry, EPR and Cu K-edge X-ray absorption spectroscopy at low temperature (193 K) and above. The mass spectrometry and low temperature EPR measurements suggested an equilibrium between the bis(µ-iodo)peroxodicopper(II) complex 2 and its dimer, namely, the tetranuclear (peroxodicopper(II))2 complex [Cu(L)(µ-I)]4O4 (2). Complex 2 undergoes an effective oxo-transfer reaction converting PPh3 into OPPh3 under anaerobic conditions. At sufficiently high concentration of PPh3, the oxygen atom transfer from 2 to PPh3 was followed by the formation of [Cu(PPh3)3I]. The dioxygen reactivity of 1 was compared with that known for other halo(amine)copper(I) dimers

Long-term safety study of infliximab in moderate-to-severe chronic obstructive pulmonary disease

SummaryRationaleThere was an increased number of malignancies in infliximab-treated (5.7%) over placebo-treated (1.3%) patients in a 44-week, phase 2 clinical study of 234 patients with moderate-to-severe chronic obstructive pulmonary disease (COPD).ObjectivesTo collect malignancy and mortality data from completed clinical studies of infliximab in COPD treatment.MethodsThe multicenter, observational Remicade Safety Under Long-Term Study in COPD (RESULTS COPD) collected malignancy and mortality data every six months for five years from patients who received ≥1 study-agent dose in a phase 2 study. Co-primary endpoints were the number of patients with malignancy and the number of deaths. Secondary endpoints included the number of patients with a malignancy according to malignancy type.ResultsThere was a gap period between the end of the phase 2 study and the initiation of RESULTS COPD, during which six malignancies and 14 deaths were reported spontaneously for the 107 (45.7%) of 234 patients with long-term safety information. Twenty-eight patients (overall 12.0%; placebo 10.4%, infliximab 12.7%) reported malignancies, including 12 patients during RESULTS COPD. Twenty-six patients (overall 11.1%; placebo 9.1%, infliximab 12.1%) died, including nine during RESULTS COPD. Lung cancer was the most common malignancy type (placebo n = 2; infliximab n = 10).ConclusionsThe greater proportion of malignancies observed with infliximab versus placebo in a phase 2 study diminished over the long-term follow-up. Due to the observational nature, limited patient participation, potential reporting bias from the interim spontaneous reporting period, and unblinding of all patients, more definitive conclusions cannot be drawn.Trial Registration Number: NCT00056264

Mass-Varying Neutrinos from a Variable Cosmological Constant

We consider, in a completely model-independent way, the transfer of energy between the components of the dark energy sector consisting of the cosmological constant (CC) and that of relic neutrinos. We show that such a cosmological setup may promote neutrinos to mass-varying particles, thus resembling a recently proposed scenario of Fardon, Nelson, and Weiner (FNW), but now without introducing any acceleronlike scalar fields. Although a formal similarity of the FNW scenario with the variable CC one can be easily established, one nevertheless finds different laws for neutrino mass variation in each scenario. We show that as long as the neutrino number density dilutes canonically, only a very slow variation of the neutrino mass is possible. For neutrino masses to vary significantly (as in the FNW scenario), a considerable deviation from the canonical dilution of the neutrino number density is also needed. We note that the present `coincidence' between the dark energy density and the neutrino energy density can be obtained in our scenario even for static neutrino masses.Comment: 8 pages, minor corrections, two references added, to apear in JCA

Rhenium mixed-ligand complexes with S,N,S-tridentate thiosemicarbazone/thiosemicarbazide ligands

Rhenium(V) complexes containing tridentate thiosemicarbazones/thiosemicarbazides (H2L1) derived from N-[N′,N′-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with 4,4-dialkylthiosemicarbazides have been synthesized by ligand-exchange reactions starting from [ReOCl(L1)]. The chlorido ligand of [ReOCl(L1)] (4) is readily replaced and reactions with ammonium thiocyanate or potassium cyanide give [ReO(NCS)(L1)] (6) and [ReO(CN)(L1)] (7), respectively. The reaction of (NBu4)[ReOCl4] with H2L1 and two equivalents of ammonium thiocyanate, however, gives in a one-pot reaction [ReO(NCS)2(HL1)] (8), in which the pro-ligand H2L1 is only singly deprotonated. An oxo-bridged, dimeric nitridorhenium(V) compound of the composition [{ReN(HL1)}2O] (11) is obtained from a reaction of (NBu4)[ReOCl4], H2L1 and sodium azide. The six-coordinate complexes [ReO(L1)(Ph2btu)] (12), where HPh2btu is N,N-diphenyl-N′-benzoylthiourea, can be obtained by treatment of [ReOCl(L1)] with HPh2btu in the presence of NEt3. Studies of the antiproliferative effects of the [ReOX(L1)] system (X = Cl−, NCS− or CN−) on breast cancer cells show that the lability of a monodentate ligand seems to play a key role in the cytotoxic activity of the metal complexes, while the substitution of this ligand by the chelating ligand Ph2btu− completely terminates the cytotoxicity