Stimulated Neutrino Transformation with Sinusoidal Density Profiles

Large amplitude oscillations between the states of a quantum system can be stimulated by sinusoidal external potentials with frequencies that are similar to the energy level splitting of the states or a fraction thereof. Situations when the applied frequency is equal to an integer fraction of the energy level splittings are known as parametric resonances. We investigate this effect for neutrinos both analytically and numerically for the case of arbitrary numbers of neutrino flavors. We look for environments where the effect may be observed and find that supernova are the one realistic possibility due to the necessity of both large densities and large amplitude fluctuations. The comparison of numerical and analytic results of neutrino propagation through a model supernova reveals it is possible to predict the locations and strengths of the stimulated transitions that occur.Comment: 14 pages, 6 figure

The neutrino signal at HALO: learning about the primary supernova neutrino fluxes and neutrino properties

Core-collapse supernova neutrinos undergo a variety of phenomena when they travel from the high neutrino density region and large matter densities to the Earth. We perform analytical calculations of the supernova neutrino fluxes including collective effects due to the neutrino-neutrino interactions, the Mikheev-Smirnov-Wolfenstein (MSW) effect due to the neutrino interactions with the background matter and decoherence of the wave packets as they propagate in space. We predict the numbers of one- and two-neutron charged and neutral-current electron-neutrino scattering on lead events. We show that, due to the energy thresholds, the ratios of one- to two-neutron events are sensitive to the pinching parameters of neutrino fluxes at the neutrinosphere, almost independently of the presently unknown neutrino properties. Besides, such events have an interesting sensitivity to the spectral split features that depend upon the presence/absence of energy equipartition among neutrino flavors. Our calculations show that a lead-based observatory like the Helium And Lead Observatory (HALO) has the potential to pin down important characteristics of the neutrino fluxes at the neutrinosphere, and provide us with information on the neutrino transport in the supernova core.Comment: 30 pages, 12 figures, 6 tables, minor correction

Induction cisplatin–irinotecan followed by concurrent cisplatin–irinotecan and radiotherapy without surgery in oesophageal cancer: multicenter phase II FFCD trial

A recent phase I study showed that weekly cisplatin, irinotecan and concurrent radiotherapy can be administered with moderate toxicity in patients with oesophageal cancer. Patients with no prior treatment and oesophageal cancer stage I to III, performance status <3, caloric intake >1500 kcal day−1 were included. Chemotherapy, with cisplatin 30 mg m−2 and irinotecan 60 mg m−2, was administered at days 1, 8, 22, 29, and concurrently with radiotherapy at days 43, 50, 64 and 71. Radiotherapy was delivered with 50 or 50.4 Gy in 25 fractions/5 weeks. Forty-three patients were included, 10 stage I, 19 stage II and 14 stage III. Mean age was 59.2 years (range 44–79). A total of 30 out of 43 (69.8%) patients underwent all planned treatment. During induction chemotherapy, 14 severe toxicities of grade 3 or 4 in 10 patients (23.3%) were reported with 57.1% due to haematoxicity. During chemoradiotherapy, 31 severe toxicities of grade 3 or 4 with 64.5% due to haematotoxicity were reported in 18 patients. One toxic death occurred (diarrhoea grade 4). The complete clinical response rate was 58.1% (95% CI: 43.4–72.8%). Overall survival rate at 1 and 2 years was 62.8%, (95% CI, 58.3–77.3%) and 27.9% (95% CI, 13.4–41.3%), respectively. In conclusion, cisplatin–irinotecan–radiotherapy is an active and well-tolerated regimen feasible in out-patients

Effets de l'onde de choc et de l'auto-interaction des neutrinos sur la conversion de saveur des neutrinos dans l'environnement des supernovae

Since the discovery of the neutrino oscillation phenomenon by the Super-Kamiokande experiment and of the MSW effect as the solution of the solar neutrino deficit, the study of the neutrino propagation and of their flavor conversion in astrophysical environments is a very active field. This PhD thesis focuses upon flavor conversion phenomena of supernova neutrinos. In a first work, we performed the first complete calculation including the shock wave and the neutrino self-interaction to estimate the diffuse supernova neutrino background (DSNB) flux arriving on Earth. This neutrino flux comes from all the supernovae that exploded in the visible Universe. By varying the value of the third angle !13 of the mixing matrix UMNSP, our numerical results have shown that the shock wave has a significant impact on the DSNB flux. At the same time, we have proposed a simplified model that accounts for the shock wave effects to be used in future calculations of the DSNB flux. The second work of this thesis is focused on the first exact analytical derivation of the matter Hamiltonian in the presence of the neutrino self-interaction. We have underlined, in the two flavors case, the important role of the Dirac phase !& appearing in the matter basis and established a condition on the elements of the flavor Hamiltonian for the onset of bipolar oscillations. In the third work, using the polarization vector formalism, we have identified a correspondence between the "spectral split" and the magnetic resonance phenomena: the neutrino energies for which the magnetic resonance criteria are fulfilled undergo a flavor change at the location where the "spectral split" occurs. A preliminary study of the three flavors case indicates us that the correspondence between the "spectral split" and the magnetic resonance holds in this case aswell.Depuis la découverte du phénomène d'oscillation des neutrinos par l'expérience Super-Kamiokande et de l'effet de résonance MSW comme solution au déficit de neutrinos solaires, l'étude de la propagation des neutrinos et de leur conversion de saveur dans un contexte astrophysique est un domaine très actif. La présente thèse se focalise sur les phénomènes de conversion de saveur des neutrinos de supernova. Dans un premier travail, nous avons réalisé le premier calcul complet incluant l'onde de choc et l'auto-interaction des neutrinos pour estimer le flux du fond diffus de neutrinos de supernovae (DSNB) arrivant sur Terre. Ce flux de neutrinos provient de toutes les supernovae qui ont explosé dans l'Univers visible. En variant la valeur du troisième angle !13 de la matrice de mélange UMNSP, nos résultats numériques ont montré que l'onde de choc a un impact significatif sur le flux du DSNB. Nous avons par la même occasion proposé un modèle simplifié qui prend en compte les effets de l'onde de choc et qui pourrait être utilisé pour des calculs futurs de flux du DSNB. Le deuxième travail de cette thèse s'est concentré sur la première dérivation analytique exacte de l'Hamiltonien de matière en présence de l'auto-interaction des neutrinos. Nous avons souligné, pour le cas à deux saveurs, le rôle important tenu par la phase de Dirac !& apparaissant dans la base de matière et nous avons établi une condition sur les éléments de l'Hamiltonien de saveur pour le début des oscillations bipolaires. Dans le troisième travail, utilisant le formalisme des vecteurs polarisations, nous avons identifié une correspondance entre les phénomènes de "spectral split" et de résonance magnétique: les énergies pour lesquelles les critères de résonance magnétique sont remplis subissent une conversion de saveur à l'endroit où le "spectral split" a lieu. Une étude préliminaire du cas à trois saveurs nous indique que la correspondance entre le "spectral split" et la résonance magnétique est toujours présente

Effets de l'onde de choc et de l'auto-interaction des neutrinos sur la conversion de saveur des neutrinos dans l'environnement des supernovae

Since the discovery of the neutrino oscillation phenomenon by the Super-Kamiokande experiment and of the MSW effect as the solution of the solar neutrino deficit, the study of the neutrino propagation and of their flavor conversion in astrophysical environments is a very active field. This PhD thesis focuses upon flavor conversion phenomena of supernova neutrinos. In a first work, we performed the first complete calculation including the shock wave and the neutrino self-interaction to estimate the diffuse supernova neutrino background (DSNB) flux arriving on Earth. This neutrino flux comes from all the supernovae that exploded in the visible Universe. By varying the value of the third angle !13 of the mixing matrix UMNSP, our numerical results have shown that the shock wave has a significant impact on the DSNB flux. At the same time, we have proposed a simplified model that accounts for the shock wave effects to be used in future calculations of the DSNB flux. The second work of this thesis is focused on the first exact analytical derivation of the matter Hamiltonian in the presence of the neutrino self-interaction. We have underlined, in the two flavors case, the important role of the Dirac phase !& appearing in the matter basis and established a condition on the elements of the flavor Hamiltonian for the onset of bipolar oscillations. In the third work, using the polarization vector formalism, we have identified a correspondence between the "spectral split" and the magnetic resonance phenomena: the neutrino energies for which the magnetic resonance criteria are fulfilled undergo a flavor change at the location where the "spectral split" occurs. A preliminary study of the three flavors case indicates us that the correspondence between the "spectral split" and the magnetic resonance holds in this case aswell.Depuis la découverte du phénomène d'oscillation des neutrinos par l'expérience Super-Kamiokande et de l'effet de résonance MSW comme solution au déficit de neutrinos solaires, l'étude de la propagation des neutrinos et de leur conversion de saveur dans un contexte astrophysique est un domaine très actif. La présente thèse se focalise sur les phénomènes de conversion de saveur des neutrinos de supernova. Dans un premier travail, nous avons réalisé le premier calcul complet incluant l'onde de choc et l'auto-interaction des neutrinos pour estimer le flux du fond diffus de neutrinos de supernovae (DSNB) arrivant sur Terre. Ce flux de neutrinos provient de toutes les supernovae qui ont explosé dans l'Univers visible. En variant la valeur du troisième angle !13 de la matrice de mélange UMNSP, nos résultats numériques ont montré que l'onde de choc a un impact significatif sur le flux du DSNB. Nous avons par la même occasion proposé un modèle simplifié qui prend en compte les effets de l'onde de choc et qui pourrait être utilisé pour des calculs futurs de flux du DSNB. Le deuxième travail de cette thèse s'est concentré sur la première dérivation analytique exacte de l'Hamiltonien de matière en présence de l'auto-interaction des neutrinos. Nous avons souligné, pour le cas à deux saveurs, le rôle important tenu par la phase de Dirac !& apparaissant dans la base de matière et nous avons établi une condition sur les éléments de l'Hamiltonien de saveur pour le début des oscillations bipolaires. Dans le troisième travail, utilisant le formalisme des vecteurs polarisations, nous avons identifié une correspondance entre les phénomènes de "spectral split" et de résonance magnétique: les énergies pour lesquelles les critères de résonance magnétique sont remplis subissent une conversion de saveur à l'endroit où le "spectral split" a lieu. Une étude préliminaire du cas à trois saveurs nous indique que la correspondance entre le "spectral split" et la résonance magnétique est toujours présente

Digital Technologies and Selective Exposure: How Choice and Filter Bubbles Shape News Media Exposure

This paper analyzes the role of different origins to news media in selective exposure. We rely on a unique web-tracking online dataset from Spain to identify points of access to news outlets and study the influence of direct navigation and news-referred platforms (i.e., from Facebook and Google) on selective exposure. We also explore cross-level interactions between origins to news and political interest and ideology. We find that direct navigation increases selective exposure while Google reduces it. We also find that the relationship between origins to news and selective exposure is strongly moderated by ideology, suggesting that search engines and social media are not content neutral. Our findings suggest a rather complex picture regarding selective exposure online. digital technologies, online selective exposure, media exposure, platforms, filter bubble

The neutrino-neutrino interaction effects in supernovae: the point of view from the matter basis

10 pages, 5 figuresWe consider the Hamiltonian for neutrino oscillations in matter in the case of arbitrary potentials including off-diagonal complex terms. We derive the 'matter basis' Hamiltonian in terms of quantities one can derive from the flavor basis Hamiltonian and its derivative, for an arbitrary number of neutrino flavors. We make our expressions explicit for the two-neutrino flavor case and apply our results to the situation where the Hamiltonian includes both coupling to matter and to neutrinos, which describes neutrino propagation in core-collapse supernovae. We show that the neutrino flavour evolution depends on the mixing matrix derivatives involving not only the derivative of the matter mixing angles but also of the phases. In particular, we point out the important role of the phase derivatives, that appear due to the neutrino-neutrino interaction, and show how it can cause an oscillating degeneracy between the diagonal elements of the matter basis Hamiltonian. Our results also reveal, that the end of the synchronization regime is due to a rapid increase of the phase derivative, and identify the condition to be fulfilled for the onset of bipolar oscillations involving both the off-diagonal neutrino-neutrino interaction contributions and the vacuum terms

Is Facebook eroding the public agenda? Evidence from survey and web-tracking data

Preserving a common public agenda positively affects social integration, minimizing social cleavages and polarization. Although social media are known for fragmenting the media environment, research has not devoted much attention to their effect on the public agenda. This article addresses whether consuming news through Facebook shapes individual agendas that diverge from the set of most important problems (MIPs) as perceived by the general public. Our research design combines survey and Web-tracking data to analyze how Facebook-referred news consumption influences individual consumers’ agendas. We find that when Facebook is a relevant news referral, people are less likely to mention the top MIPs for a representative sample of the Spanish population. We discuss the implications of our findings for the public agenda

Digital Technologies and Selective Exposure: How Choice and Filter Bubbles Shape News Media Exposure

This paper analyzes the role of different origins to news media in selective exposure. We rely on a unique web-tracking online dataset from Spain to identify points of access to news outlets and study the influence of direct navigation and news-referred platforms (i.e., from Facebook and Google) on selective exposure. We also explore cross-level interactions between origins to news and political interest and ideology. We find that direct navigation increases selective exposure while Google reduces it. We also find that the relationship between origins to news and selective exposure is strongly moderated by ideology, suggesting that search engines and social media are not content neutral. Our findings suggest a rather complex picture regarding selective exposure online. digital technologies, online selective exposure, media exposure, platforms, filter bubble