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.

[Effect of almitrine on arterial gases in patients with chronic respiratory insufficiency. Comparison with doxapram. Preliminary results]. / Invloed van almitrine op de arteriële gassen bij patiënten met chronische respiratoire insufficiëntie. Vergelijking met doxapram. Voorlopige resultaten.

We compared the effects of almitrine and doxapram on the arterial blood gases and ventilation of patients with chronic respiratory insufficiency and chronic hypercapnia and hypoxemia. Sixteen long-term in-patients were randomly allocated to one of the following treatment groups: the first group (8 patients) received IV almitrine 0.5 mg/kg and the second group (8 patients) IV doxapram 1 mg/kg by IV perfusion during 30 min. All gave their informed consent. Arterial blood gases and ventilation were measured 10 min and 5 min before treatment, at the 5th, 15th and 25th min of perfusion time, and 5, 10 and 15 min after infusion. There was a marked increase in paO2 in almitrine-treated patients, which was maximum at the 25th min of infusion (+ 14.6 mm Hg, p < 0.001), but only a slight improvement was observed in the doxapram group (+ 3.3 mm Hg, p < 0.05). After almitrine the maximum mean paCO2 decrease was at the 10th min after perfusion (-6.9 mm Hg, p < 0.001); after doxapram the maximum decrease, although highly significant, was much less (-2.8 mm Hg, p < 0.01). Thus, at the presently used and well-tolerated doses, almitrine is much more efficient than doxapram in improving gas exchange in patients with chronic hypoxemia and hypercapnia. However, complementary studies using higher dosage of doxapram are warranted.

Peliosis hepatis presenting as a multifocal hepatic pseudotumor: MR findings in two cases.

Two cases of pseudotumoral peliosis hepatis are presented with emphasis on MRI findings. One patient had four individual lesions, the other had two. Image characteristics in both were: heterogeneic signal intensity on T1-weighted images (T1WI) with areas of high-, intermediate, and low signal intensity; heterogeneic signal intensity on T2WI with presence of numerous intralesional "cystic" hyperintense areas with a hypointense border. Signal intensities on T1WI were iso- to hypointense in one case and mild central hyperintensities were demonstrated in the other case, probably due to intra-lesional hemorrhage or diffuse accumulation of fresh clotting within the sinusoids. One case demonstrated early enhancement of the peripheral borders in the arterial phase, and both demonstrated enhancement in the portovenous and late phases. One case was studied with Gd-BOPTA and iron oxides and demonstrated enhancement with both products, suggestive for the presence of hepatocytes and Kupffer cells. This is the first report of the use of hepato-specific contrast agents in this entity. Spontaneous regression of the lesions was demonstrated on a follow-up MR examination in one case.