The relationship between the use of tumor necrosis factor antagonists and onset of granulomatous infection was examined using data collected through the Adverse Event Reporting System of the US Food and Drug Administration for January 1998-September 2002. Granulomatous infections were reported at rates of approximately 239 per 100,000 patients who received infliximab and approximately 74 per 100,000 patients who received etanercept (P<.001). Tuberculosis was the most frequently reported disease, occurring in approximately 144 and approximately 35 per 100,000 infliximab-treated and etanercept-treated patients, respectively (P<.001). Candidiasis, coccidioidomycosis, histoplasmosis, listeriosis, nocardiosis, and infections due to nontuberculous mycobacteria were reported with significantly greater frequency among infliximab-treated patients. Seventy-two percent of these infection occurred < or =90 days after starting infliximab treatment, and 28% occurred after starting etanercept treatment (P<.001). These data indicate a risk of granulomatous infection that was 3.25-fold greater among patients who received infliximab than among those who received etanercept. The clustering of reports shortly after initiation of treatment with infliximab is consistent with reactivation of latent infection.

In a magnetic field, spin-ladders undergo two zero-temperature phase transitions at the critical fields Hc1 and Hc2. An experimental review of static and dynamical properties of spin-ladders close to these critical points is presented. The scaling functions, universal to all quantum critical points in onedimension, are extracted from (a) the thermodynamic quantities (magnetization) and (b) the dynamical functions (NMR relaxation). A simple mapping of strongly coupled spin ladders in a magnetic field on the exactly solvable XXZ model enables to make detailed fits and gives an overall understanding of a broad class of quantum magnets in their gapless phase (between Hc1 and Hc2). In this phase, the low temperature divergence of the NMR relaxation demonstrates its Luttinger liquid nature as well as the novel quantum critical regime at higher temperature. The general behavior close these quantum critical points can be tied to known models of quantum magnetism.PACS. 75.10.Jm Quantized spin models -75.40.-s Critical-points effects, specific heats, short range order -76.60.-k Nuclear magnetic resonance and relaxation

We present an extensive NMR study of the spin-1/2 antiferromagnetic Heisenberg ladder Cu2(C5H12N2)2Cl4 in a magnetic field range 4.5 -16.7T. By measuring the proton NMR relaxation rate 1/T1 and varying the magnetic field around the critical field Hc1 = ∆/gµB ≈ 7.5T, we have studied the transition from a gapped spin liquid ground state to a gapless magnetic regime which can be described as a Luttinger liquid. We identify an intermediate regime T ≥ |H − Hc1|, where the spin dynamics is (possibly) only controlled by the T=0 critical point Hc1.75. 10Jm,75.40Cx, One of the most fascinating effect in quantum magnetism is perhaps the possibility to realize a T=0 phase transition [1] from a "quantum disordered" (gapped spin liquid) ground state to a Luttinger liquid state in one dimension (1D) [4] or to a Néel ordered state in two dimensions (2D) [2,3]. There are well known examples of gapped spin liquids in 1D: for integer-spin Heisenberg antiferromagnetic (HAF) chains [5,6] or spin-1/2 HAF even-leg ladders [7], quantum fluctuations induce a spin gap ∆ between a singlet (S=0) ground state and triplet (S=1) excited states. An external magnetic field lifts the triplet degeneracy and induces a second order T=0 phase transition at a critical field H c1 ≡ ∆ when the lowest branch of the triplet crosses the ground state. At this critical field, dynamical properties are defined by universal exponents [8][9][10]. Above H c1 , the ground state is magnetic with an algebraic decay of the correlation functions. Close to H c1 , the low frequency (ω < T ) spin dynamics should be governed in an universal way by the T=0 critical point H c1 . In the vicinity of this point, divergent quantum correlations are cut-off by thermal fluctuations at a length ξ T which become the only relevant length scale. This is the quantum critical regime (QCR) where the temperature is the only energy scale over the large intermediate regionThe true challenge to experiments is to observe in a single system, all the sequences of the T → 0 regimes as well as the finite temperature critical regime.In a gapped HAF, such quantum phase transition can be experimentally studied only if the gap ∆ is comparable to accessible magnetic fields. The situation is hopless in the S=1/2 spin ladder compound SrCu 2 O 3 (∆ ≥ 400K) [11]. On the other hand, it is now well established that the organo-metallic compound Cu 2 (C 5 H 12 N 2 ) 2 Cl 4 [12] is a unique representative of HAF S=1/2 ladders with small exchange constants (J ⊥ ≈ 13.2K, J ≈ 2.5K) and a spin gap (∆ k=π ≃ J ⊥ −J = 10

A novel method of Fourier transform spectroscopy of the transient signals from wide, inhomogeneously broadened magnetic resonance spectra is described and analyzed. It has the advantages of high resolution, high sensitivity, and freedom from the distortions introduced by the finite amplitude of the pulsed rf magnetic field and the finite bandwidth of the receiving system. It consists of recording the transient signal at a series of magnetic fields, shifting the frequency of the transient by the corresponding field step for each point, and summing the corresponding Fourier transformed signals. Although the primary emphasis is on pulsed NMR, the analysis also applies to pulsed ESR. Criteria for the range and step interval of the magnetic field variation are discussed. The accuracy and sensitivity of the method are compared with earlier methods of spin echo spectroscopy. A description of the corresponding measurement of NQR, NMR, and ESR spectra obtained by stepping the frequency of the spectrometer is also presented.