Fission fragment angular distribution measurements of U-235 and U-238 at CERN n_TOF facility

Neutron-induced fission cross sections of U-238 and U-235 are used as standards in the fast neutron region up to 200 MeV. A high accuracy of the standards is relevant to experimentally determine other neutron reaction cross sections. Therefore, the detection efficiency should be corrected by using the angular distribution of the fission fragments (FFAD), which are barely known above 20 MeV. In addition, the angular distribution of the fragments produced in the fission of highly excited and deformed nuclei is an important observable to investigate the nuclear fission process. In order to measure the FFAD of neutron-induced reactions, a fission detection setup based on parallel-plate avalanche counters (PPACs) has been developed and successfully used at the CERN-n_TOF facility. In this work, we present the preliminary results on the analysis of new U-235(n,f) and U-238(n,f) data in the extended energy range up to 200 MeV compared to the existing experimental data.Postprint (published version

One year follow-up of a randomized trial with a dilemma-focused intervention for depression: Exploring an alternative to problem-oriented strategies

© 2018 Feixas et al.Cognitive behavioural therapy (CBT) is aimed to counteract cognitions and behaviours that are considered as dysfunctional. The aim of the study is to test whether the inclusion of a non-counteractive approach (dilemma-focused intervention, DFI) in combination with CBT group therapy will yield better short- and long-term outcomes than an intervention conducted entirely using CBT.Peer reviewedFinal Published versio

Study of the 234U(n,f) fission fragment angular distribution at the CERN n_TOF facility

The angular distribution of the f ssion fragments (FFAD) produced in neutron induced reactions of actinides have been measured with a fission detection setup based on parallel-plate avalanche counters (PPACs) at the Neutron Time-Of-Flight (n_TOF) facility at CERN. The main features of the setup and preliminary results are reported here for the 234U(n,f) reaction measurement showing a high concordance with previous data, while providing new results up to 100 MeV.Postprint (published version

External temperature effects on the hysteresis of NiTi wires in dampers for stay-cables

The use of NiTi wires, one of the Shape Memory Alloy (SMA) materials that permits efficient damping in stayed cables for bridges, requires an appropriate behavior when exposed to the external temperature effects. The Clausius-Clapeyron thermodynamic equation establishes a shift of the hysteretic cycle in the stress-temperature representation of about 6 MPa/K for the used wires of diameter 2.46 mm. Hence, an adequate experimental study is necessary to characterize the temperature effects in working conditions. The conducted analysis is twofold. First, the practical evolution of the hysteresis cycle is investigated. The results suggest that the wire permits a completely satisfactory use for temperatures as low as 253 K (i.e., -20 oC). Second, the focus is placed on the effects of extreme winter actions (i.e., as low as 233 K or -40 oC). A preliminary stress aging process at 373K seems adequate to this requirement. Indeed, after the stress aging, the SMA wire increases their working domain by 300 or 400 MPa and the temperature domain is expanded by 30 – 50 K. Measurements visualizing recoverable dynamical actions in the SMA alloys are also outlined.Peer ReviewedPostprint (published version

Factores pronósticos de recurrencia y progresión vesical en el tumor de vía urinaria superior

Objetivos: Estudiar factores asociados al tumor de urotelio superior (TUS) como predictores de recurrencia y progresión vesical. Pacientes y métodos: Estudio retrospectivo sobre 79 pacientes con tumor de urotelio superior (TUS) tratados con nefroureterectomía. El seguimiento medio es de 5.8 años (70 meses). Se ha estudiado la asociación de factores en el TUS como estadio y grado tumoral, tamaño, historia previa de tumor vesical, localización, sexo, edad y asociación con carcinoma in situ (CIS), en relación con recurrencia y progresión vesical. Para ello se ha realizado análisis univariante y multivariante, utilizando el método de Kaplan-Meier (log-rank) y regresión múltiple de Cox, respectivamente. Resultados: Observamos una recurrencia vesical de 54% (43 casos) (I.C 95%: 43-65) y una progresión vesical del 11% (9 casos). El CIS asociado a TUS (p = 0,020) (OR 2.3; IC 95%: 1,1-4,7) y estadio del TUS (p = 0,018) (OR 2.5; IC 95%: 1,1- 5,3) son variables independientes significativas en relación con recurrencia vesical. El CIS asociado a TUS (p = 0,006; OR 19 ; IC 95%: 2,3-157,6), y el tamaño del TUS (p = 0,060) (OR 3,8; IC 95%: 0,9-15,5) son variables independientes significativas relacionadas con progresión vesical. Conclusiones: El CIS asociado a TUS es el factor pronóstico independiente más importante para predecir la evolución vesical después de TUS, ya que se relaciona con recurrencia, y es factor más importante para predecir progresión vesical. El estadio del TUS es factor pronóstico independiente de recurrencia vesical. El tamaño del TUS (≥ 4 cm) es factor pronóstico independiente de progresión vesical. Los pacientes con estos factores son los que deberían tener un seguimiento más estricto de la vejiga, y plantearnos la necesidad de realizar instilaciones endovesicales posteriores al tratamiento del TUS.Purpose:We evaluated the prognostic factors of subsequent bladder recurrence and bladder progression in patients with transitional cell carcinoma of the upper urinary tract. Material and methods: We studied a cohort of 79 patients with upper urinary tract tumor (UUTT) treated with nephroureterectomy. Mean follow-up was 5.8 years. Statistical analysis was performed using the Kaplan-Meier method and multivariate analysis was done with Cox proportional hazards model with stepwise forward selection. All p-values were 2-sided, with odds ratios and 95% confidence interval. Results: Bladder recurrence was found in 54% (43 cases), bladder progression was found in 11% (9 cases). Carcinoma in situ of UUTT (odds ratio 2.3) and tumor stage of UUTT (greater than pT1) (odds ratio 2.5) increased the risk of subsequent bladder recurrence. Carcinoma in situ of UUTT (odds ratio 19.3) and tumor size (greater than 3 cm) (odds ratio 3.8) increased the risk of subsequent bladder progression. Conclusions: Neither tumor grade nor localization of UUTT influenced tumor evolution. Tumor stage of UUTT (greater than pT1) was a risk factor of bladder recurrence. Tumor size of UUTT (greater than 3 cm) was a risk factor of bladder progression. Finally, carcinoma in situ of UUTT influenced bladder recurrence and bladder progression. This finding could help identify patients at greater risk for disease recurrence and progression who would benefit from close followup and early adjuvant therapy after nephroureterectomy for upper urinary transitional cell carcinoma

The SMA: an effective damper in civil engineering that smoothes oscillations

The properties of SMA (Shape Memory Alloys, that are smart materials) are associated to a first order phase transition named martensitic transformation that occurs between metastable phases: austenite and martensite. At upper temperature or at lower stress the austenite is the metastable phase. The martensite appears at lower temperature or higher stresses. The hysteresis of the transformation permits different levels of applications, i.e., in their use as a damper. Two types of applications can be considered in damping of structures in Civil Engineering. The first one is related to diminishing the damage induced by earthquakes. The second one is a reduction of oscillation amplitude associate to an increase of the lifetime for the stayed cables in bridges.Peer Reviewe

A survey for water maser emission towards planetary nebulae. New detection in IRAS 17347-3139

We report on a water maser survey towards a sample of 27 planetary nebulae (PNe) using the Robledo de Chavela and Medicina single-dish antennas, as well as the Very Large Array (VLA). Two detections have been obtained: the already known water maser emission in K 3-35, and a new cluster of masers in IRAS 17347-3139. This low rate of detections is compatible with the short life-time of water molecules in PNe (~100 yr). The water maser cluster at IRAS 17347-3139 are distributed on a ellipse of size ~ 0.2" x 0.1", spatially associated with compact 1.3 cm continuum emission (simultaneously observed with the VLA). From archive VLA continuum data at 4.9, 8.4, and 14.9 GHz, a spectral index alpha = 0.76 +- 0.03 is derived for this radio source, which is consistent with either a partially optically thick ionized region or with an ionized wind. However, the latter scenario can be ruled out on mass-loss considerations, thus indicating that this source is probably a young PN. The spatial distribution and the radial velocities of the water masers are suggestive of a rotating and expanding maser ring, tracing the innermost regions of a torus formed at the end of the AGB phase. Given that the 1.3 cm continuum emission peak is located near one of the tips of the major axis of the ellipse of masers, we speculate on a possible binary nature of IRAS 17347-3139, where the radio continuum emission could belong to one of the components and the water masers would be associated with a companion.Comment: Accepted by The Astrophysical Journal. 25 pages, 6 figure

Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307

Context. The K2.5 dwarf HD 40307 has been reported to host three super-Earths. The system lacks massive planets and is therefore a potential candidate for having additional low-mass planetary companions. Aims. We re-derive Doppler measurements from public HARPS spectra of HD 40307 to confirm the significance of the reported signals using independent data analysis methods. We also investigate these measurements for additional low-amplitude signals. Methods. We used Bayesian analysis of our radial velocities to estimate the probability densities of different model parameters. We also estimated the relative probabilities of models with differing numbers of Keplerian signals and verified their significance using periodogram analyses. We investigated the relation of the detected signals with the chromospheric emission of the star. As previously reported for other objects, we found that radial velocity signals correlated with the S-index are strongly wavelength dependent. Results. We identify two additional clear signals with periods of 34 and 51 days, both corresponding to planet candidates with minimum masses a few times that of the Earth. An additional sixth candidate is initially found at a period of 320 days. However, this signal correlates strongly with the chromospheric emission from the star and is also strongly wavelength dependent. When analysing the red half of the spectra only, the five putative planetary signals are recovered together with a very significant periodicity at about 200 days. This signal has a similar amplitude as the other new signals reported in the current work and corresponds to a planet candidate with Msini ~ 7 M⊕ (HD 40307 g).Peer reviewe