The branching ratio (BR) for the decay K+ → π+ν is a sensitive probe for new physics. The NA62 experiment at the CERN SPS will measure this BR to within about 10 . To reject the background from ...dominant kaon decays with final state photons, the large-angle photon vetoes (LAVs) must detect photons of energy as low as 200 MeV with an inefficiency of less than 10−4. The LAV detectors make use of lead glass blocks recycled from the OPAL electromagnetic calorimeter barrel. We describe the mechanical design and challenges faced during construction, the characterization of the lead glass blocks and solutions adopted for monitoring their performance, and the development of front-end electronics to allow simultaneous time and energy measurements over an extended dynamic range using the time-over-threshold technique. Our results are based on test-beam data and are reproduced by a detailed Monte Carlo simulation that includes the readout chain.
The mechanism of conversion of the normal prion protein (PrPC) into aggregates of its pathological conformer (PrPSc) reamins unclear. The aim of this study was to evaluate the effects induced by ...exposure of biological samples containing PrPSC to a magnetic field induced prominent molecular changes of samples indicated by the IR spectra located in the region that contains contribution primarily from absorption of amides. This finding suggests the existence of a strong correlation between magnetism and PrPsc and supports a new hypothesis that explains the conversion of normal PrPc to abnormal isoform PrPsc.
The management of fetal ovarian cysts is still controversial despite the improvement in prenatal diagnosis with ultrasonography. Some studies suggest an aggressive management, while others opt for a ...conservative one. The prognosis of the majority of congenital ovarian cysts is good since they have a benign origin. Sometimes, however, complications such as torsion or rupture can occur which often require surgical intervention after delivery. In this paper we report our experience and a brief review of the literature.
The authors report on 32 pregnant women in whom ultrasonography revealed the presence of an echo-rare or echo-free area in the fetal abdomen suggestive of an ovarian cyst. All women were followed-up during pregnancy with serial ultrasound examinations. Postnatal ultrasound controls confirmed the prenatal diagnosis in all cases. The diameters of the cysts ranged from 2.7 to 7.5 cm.
In the 16 cases (50%) in which the cyst diameter was below 4 cm, periodic ultrasound examinations revealed a tendency towards spontaneous regression of the cysts. In the other 16 cases (50%) in which the cyst diameter exceeded 4 cm, cystectomy was necessary due to subsequent complications (torsion in 6 cases, 37.5%, and intracystic hemorrhage in the other 10, 62.5%).
The most appropriate clinical approach in the management of benign feto-neonatal ovarian cysts is to adopt a wait-and-see policy, assessing the course of the condition by means of periodic ultrasound monitoring. Only when tumefactions measure more than 4 cm in diameter with attendant complications is surgical therapy indicated. Without complications, however, aspiration of the cystic contents is possible even in ovarian cysts exceeding 4 cm in diameter.
The NA48/2 experiment at CERN reports the first observation of the $K^± → π^0π^0μ^±$ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay ...branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c4 is measured to be (0.65 ± 0.03) × 10–6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10–6, in agreement with chiral perturbation theory predictions.
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