New constraint on the existence of the µ+ → e+ γ decay.

The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for the lepton flavor violating decay µ(+) → e(+)γ is presented. The data collected by the MEG experiment at the Paul Scherrer Institut show no excess of events compared to background expectations and yield a new upper limit on the branching ratio of this decay of 5.7 × 10(-13) (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.

New limit on the lepton-flavor-violating decay µ+→e+γ.

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay µ(+)e(+)γ. The likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the µ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.

Calculations of dose distributions in the lungs of a rat model irradiated in the thermal column of the TRIGA reactor in Pavia.

To test the possibility to apply boron neutron capture therapy (BNCT) to lung tumors, some rats are planned to be irradiated in the thermal column of the TRIGA reactor of the University of Pavia. Before the irradiation, lung metastases will be induced in BDIX rats, which will be subsequently infused with boronophenylalanine (BPA). During the irradiation, the rats will be positioned in a box designed to shield the whole animal except the thorax area. In order to optimize the irradiation set-up and to design a suitable shielding box, a set of calculations were performed with the MCNP Monte Carlo transport code. A rat model was constructed using the MCNP geometry capabilities and was positioned in a box with walls filled with lithium carbonate. A window was opened in front of the lung region. Different shapes of the holder and of the window were tested and analyzed in terms of the dose distribution obtained in the lungs and of the dose absorbed by the radiosensitive organs in the rat. The best configuration of the holder ensures an almost uniform thermal neutron flux inside the lungs (Phi(max)/Phi(min)=1.5), an irradiation time about 10 min long, to deliver at least 40 Gy(w) to the tumor, a mean lung dose of 5.9+/-0.4 Gy(w), and doses absorbed by all the other healthy tissues below the tolerance limits.

Direct measurement of the 7Be solar neutrino flux with 192 days of borexino data.

We report the direct measurement of the 7Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV 7Be neutrinos is 49+/-3stat+/-4syst counts/(day.100 ton). The hypothesis of no oscillation for 7Be solar neutrinos is inconsistent with our measurement at the 4sigma C.L. Our result is the first direct measurement of the survival probability for solar nu(e) in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of 7Be, pp, and CNO solar nu(e), and the limit on the effective neutrino magnetic moment using solar neutrinos.

Massive allografts in the treatment of osteosarcoma and Ewing sarcoma in children and adolescents.

A retrospective review was performed of the results of all allograft reconstructions that had been done after the resection of an osteosarcoma or an Ewing sarcoma in a skeletally immature patient between 1982 and 1989 at The Hospital for Sick Children in Toronto. There were twenty-six patients. Six reconstructions were intercalary, sixteen were resection arthrodeses, three followed resection of a bone segment including the epiphysis (osteoarticular reconstruction), and one was a replacement of the entire humerus. Resection arthrodesis about the knee was performed with a smooth intramedullary rod and with one growth plate left intact. Six procedures were performed in the upper extremity. Excluding the patients who died, the average duration of follow-up was five years and three months. Twenty-one of the twenty-six patients had reached skeletal maturity at the time of follow-up. Eighteen (69 per cent) of the patients had a good or excellent result, four (15 per cent) had a fair result, and four had a failure. Twenty patients (77 per cent) had at least one complication (other than a limb-length discrepancy), and fourteen (54 per cent) sustained at least one fracture of the allograft. Fifteen patients who had had a reconstruction in the lower extremity had survived with survival of the allograft at the time of the latest follow-up. A limb-length discrepancy of at least two centimeters developed in nine of the fifteen patients. Five were managed with a contralateral epiphyseodesis, and one of them had an unsuccessful attempt at limb-lengthening as well. The patients who had a limb-length discrepancy of more than three centimeters at the time of follow-up had been significantly younger (p < 0.05) at the time of the reconstruction than those who had a smaller discrepancy. Three allografts (12 per cent), two of which were implanted early in the series, became infected. Soft-tissue coverage is of paramount importance for the prevention of infection, and we now routinely perform primary muscle (gastrocnemius or latissimus dorsi) transfers when dealing with an inadequate muscle envelope. Twelve patients were followed for more than four years (average, six years and seven months); they had no complications other than increased limb-length discrepancy and one subluxation of the shoulder after the first four years following the reconstruction. Although the rate of complications is higher than in adults, allograft reconstruction remains a useful option for the management of skeletally immature individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Modified Van Nes rotationplasty for osteosarcoma of the proximal tibia in children.

Above-knee amputation has been the traditional treatment for osteosarcoma of the proximal tibia. Recent advances in chemotherapy have encouraged the development of limb-salvage techniques. Van Nes rotationplasty for malignant lesions of the distal femur has increased in popularity as a reconstructive technique, but no similar procedure has been described for lesions of the proximal tibia. We have developed a modified rotationplasty for this lesion and have performed it in four children. The surgical technique, postoperative management and results of the procedure are described. Two patients had delayed wound healing. No other complications have developed and our patients were disease-free at follow-up, while the appearance of the leg was well accepted by the patients and their parents. This procedure is a useful addition to the armamentarium of the tumour surgeon for the treatment of malignant lesions of the proximal tibia.

Biomedical responses of rats to chronic exposure to dietary cadmium fed in ad libitum and equalized regimes.

Forty 100 g male rats were fed, in groups of eight, either 0, 5, or 25 ppm cadmium in a purified diet for 14 wk. Three groups were fed each of the levels of cadmium on an ad libitum basis. Two other groups were fed either 0 or 5 ppm cadmium in amounts that were equalized to that consumed by the 25 ppm group fed ad libitum. Cadmium ingestion decreased daily diet consumption, weight gain, and terminal body weight. These parameters were not significantly different in rats whose diet consumption was equalized. Packed cell volume and serum iron as well as serum zinc were decreased in the rats fed 25 ppm cadmium. These effects were not related to diet intake. No major differences were observed in serum ceruloplasmin, glucose, protein, leucine aminopeptidase activity, or copper in any of the groups. Blood urea nitrogen and renal leucine aminopeptidase activity were decreased by cadmium ingestion in the rats fed ad libitum only. In contrast, serum alkaline phosphatase activity was elevated by cadmium in the equalized-intake groups only. Cadmium and zinc concentrations were elevated and the iron concentration was decreased in the kidney, liver, and intestinal mucosa of the cadmium-fed rats irrespective of level of diet consumption. The increased uptake of cadmium in these tissues was coincident with the increased content of the cadmium-binding protein, metallothionein, in the cytosol fraction. The results indicate that some parameters of chronic cadmium toxicity are associated with diet consumption whereas others are not.