Isotensor Dibaryon in the pp→ppπ

Exclusive measurements of the quasifree pp→ppπ^{+}π^{-} reaction have been carried out at WASA@COSY by means of pd collisions at T_{p}=1.2 GeV. Total and differential cross sections have been extracted covering the energy region T_{p}=1.08-1.36 GeV, which is the region of N^{*}(1440) and Δ(1232)Δ(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor ΔN dibaryon resonance with I(J^{P})=2(1^{+}) produced associatedly with a pion is able to overcome these deficiencies.

Spin Dependence of η Meson Production in Proton-Proton Collisions Close to Threshold.

Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction p[over →]p→ppη has been measured close to threshold to explore the analyzing power A_{y}. The angular distribution of A_{y} is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q=15 MeV, signaling s-wave production with no evidence for higher partial waves. At Q=72 MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)^{2} and Ss^{*}Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the η meson.

Abashian-Booth-Crowe effect in basic double-pionic fusion: a new resonance?

We report on an exclusive and kinematically complete high-statistics measurement of the basic double-pionic fusion reaction pn→dπ(0)π(0) over the full energy region of the ABC effect, a pronounced low-mass enhancement in the ππ-invariant mass spectrum. The measurements, which cover also the transition region to the conventional t-channel ΔΔ process, were performed with the upgraded WASA detector setup at COSY. The data reveal the Abashian-Booth-Crowe effect to be uniquely correlated with a Lorentzian energy dependence in the integral cross section. The observables are consistent with a narrow resonance with m=2.37 GeV, Γ≈70 MeV and I(J(P))=0(3(+)) in both pn and ΔΔ systems. Necessary further tests of the resonance interpretation are discussed.

Randomized PCR-based therapy and risk factors for invasive fungal infection following reduced-intensity conditioning and hematopoietic SCT.

Invasive fungal infections (IFIs) are major complications after allogeneic hematopoietic SCT (HSCT). PCR-based assays able to detect fungal DNA have been reported to precede clinical diagnosis of IFI. We performed a prospective study to evaluate a PCR-based pre-emptive approach. Ninety-nine patients undergoing reduced-intensity conditioning (RIC) HSCT were followed with fungal PCR during the first 100 days post transplantation. Patients who tested positive were randomized to receive liposomal amphotericin B, or to no intervention. After day 100, PCR tests were performed only on clinical suspicion of IFI. A single positive PCR test was not associated with IFI, irrespective of treatment. After day 100, PCR tests for Aspergillus did not contribute to diagnosis of invasive aspergillosis (IA). The cumulative incidence rates of proven or probable IA during the first year after transplantation were 9%. GVHD grades II-IV (P=0.0014), CMV-seronegative recipient with CMV-seropositive donor (P0.001), and conditioning with alemtuzumab (P=0.014) were significant risk factors for developing IA in a multivariate model. In this study, PCR on peripheral blood was a poor indicator of IFI early after RIC HSCT. Aspergillus PCR tests performed on clinical suspicion after day 100 were insufficiently sensitive to be diagnostically useful.

Double-pionic fusion of nuclear systems and the "ABC" effect: approaching a puzzle by exclusive and kinematically complete measurements.

The ABC effect-a puzzling low-mass enhancement in the pipi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn-->dpi;{0}pi;{0} at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pipi)_{I=L=0} channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a DeltaDelta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.

A prospective randomized study using N-acetyl-L-cysteine for early liver toxicity after allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (ASCT) and its conditioning with chemoradiotherapy often results in liver toxicity, the most severe form being veno-occlusive liver disease (VOD). N-acetyl-L-cysteine (NAC), an antioxidant glutathione precursor, may provide protection from liver toxicity. Patients with elevated bilirubin (>26 mmol/l) and/or elevated (ALT) (>1.4 microkat/l) and/or aspartate aminotransferase (AST) (>1.4 microkat/l) levels were randomized to treatment with NAC or no treatment. Among 522 transplanted patients, 160 were included in the trial. NAC was given, 100 mg/kg per day, as a 6-h i.v. infusion until normalization of bilirubin, ALT and AST values. Maximum bilirubin level was the same in patients randomized to NAC (n=72) or controls (n=88). Increase and recovery of ALT and AST were the same in patients randomized to NAC or controls. There were two patients in the NAC group who developed VOD, as compared to three of the controls. To conclude, NAC does not improve liver toxicity after ASCT.

Exclusive measurement of the pp --> pppi(+)pi(-) reaction near threshold.

The pp-->pp pi(+) pi(-) reaction has been measured exclusively near threshold at CELSIUS. The total cross sections are nearly an order of magnitude lower than expected from previous inclusive measurements. The differential cross sections reveal pp-->pp(*)(1440)-->pp sigma = pp(pi(+)pi(-))(I = l = 0) as the dominant process as well as significant contributions from p(*)-->Delta(++)pi(-)-->psigma. The observed anisotropy in the proton angular dependence is consistent with heavy-meson exchange. In the invariant mass spectra, no narrow structures of statistical relevance (3sigma) are found.

Spontaneous remission of dermatitis herpetiformis: dietary and gastrointestinal studies.

Out of 98 patients with dermatitis herpetiformis (DH) living in Gothenburg, 14 were in spontaneous remission (29% of the patients without gluten free diet). Eight of these volunteered for dietary interviews and further studies. They do not seem to differ from symptomatic DH patients in the frequency of HLA-B8, achlorhydria or small-bowel enteropathy. Their estimated mean daily intake of gluten was below 12 g in six. The mean gluten intake of the eight patients in remission is significantly less than in a group of 34 patients with dapsone-requiring DH on non-restricted diet. Urinary iodine excretion was low in five, all previously instructed to restrict their iodine intake. Dietary factors could thus be suspected to be responsible for some spontaneous remissions in DH.