Search for a Lorentz invariance violation in atmospheric neutrino oscillations using MACRO data

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of special relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of nu_mu nu_tau transitions. The data disfavour these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameters. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.Comment: 8 pages, 5 EPS figures, uses article.sty. Invited talk at C2CR 2005, From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 September 200

Sediment compaction rates and subsidence in deltaic plains : numerical constraints and stratigraphic influences

This paper is not subject to U.S. copyright. The definitive version was published in Basin Research 19 (2007): 19-31, doi:10.1111/j.1365-2117.2006.00310.x.Natural sediment compaction in deltaic plains influences subsidence rates and the evolution of deltaic morphology. Determining compaction rates requires detailed knowledge of subsurface geotechnical properties and depositional history, neither of which is often readily available. To overcome this lack of knowledge, we numerically forward model the incremental sedimentation and compaction of stochastically generated stratigraphies with geotechnical properties typical of modern depositional environments in the Mississippi River delta plain. Using a Monte Carlo approach, the range of probable compaction rates for stratigraphies with compacted thicknesses <150 m and accumulation times <20 kyr. varies, but maximum values rarely exceed a few mm yr-1. The fastest compacting stratigraphies are composed primarily of peat and bar sand, whereas the slowest compacting stratigraphies are composed of prodelta mud and natural levee deposits. These results suggest that compaction rates can significantly influence vertical and lateral stratigraphic trends during deltaic evolution

Effects of neoadjuvant chemotherapy with or without zoledronic acid on pathological response: A meta-analysis of randomised trials

Purpose The addition of bisphosphonates to adjuvant therapy improves survival in postmenopausal breast cancer (BC) patients. We report a meta-analysis of four randomised trials of neoadjuvant chemotherapy (CT) +/– zoledronic acid (ZA) in stage II/III BC to investigate the potential for enhancing the pathological response. Methods Individual patient data from four prospective randomised clinical trials reporting the effect of the addition of ZA on the pathological response after neoadjuvant CT were pooled. Primary outcomes were pathological complete response in the breast (pCRb) and in the breast and lymph nodes (pCR). Trial-level and individual patient data meta-analyses were done. Predefined subgroup-analyses were performed for postmenopausal women and patients with triple-negative BC. Results pCRb and pCR data were available in 735 and 552 patients respectively. In the total study population ZA addition to neoadjuvant CT did not increase pCRb or pCR rates. However, in postmenopausal patients, the addition of ZA resulted in a significant, near doubling of the pCRb rate (10.8% for CT only versus 17.7% with CT+ZA; odds ratio [OR] 2.14, 95% confidence interval [CI] 1.01–4.55) and a non-significant benefit of the pCR rate (7.8% for CT only versus 14.6% with CT+ZA; OR 2.62, 95% CI 0.90–7.62). In patients with triple-negative BC a trend was observed favouring CT+ZA. Conclusion This meta-analysis shows no impact from the addition of ZA to neoadjuvant CT on pCR. However, as has been seen in the adjuvant setting, the addition of ZA to neoadjuvant CT may augment the effects of CT in postmenopausal patients with BC

Geomorphological effectiveness of floods to rework gravel bars:insight from hyperscale topography and hydraulic modelling

Bars are key morphological units in river systems, fashioning the sediment regime and bedload transport processes within a reach. Reworking of these features underpins channel adjustment at larger scales, thereby acting as a key determinant of channel stability. Despite their importance to channel evolution, few investigations have acquired spatially continuous data on bar morphology and sediment‐size to investigate bar reworking. To this end, four bars along a 10 km reach of a wandering gravel‐bed river were surveyed with Terrestrial Laser Scanning (TLS), capturing downstream changes in slope, bed material size and channel planform. Detrended standard deviations (σz) were extracted from TLS point clouds and correlated to underlying physically measured median grain‐size (D50), across a greater range of σz values than have hitherto been reported. The resulting linear regression model was used to create a 1 m resolution median grain‐size map. A fusion of airborne LiDAR and optical‐empirical bathymetric mapping was used to develop reach‐scale Digital Elevation Models (DEMs) for rapid two‐dimensional hydraulic modelling using JFlow® software. The ratio of dimensionless shear stress over critical shear stress was calculated for each raster cell to calculate the effectiveness of a range of flood events (2.33‐100 year recurrence intervals) to entrain sediment and rework bar units. Results show that multiple bar forming discharges exist, whereby frequent flood flows rework tail and back‐channel areas, whilst much larger, less frequent floods are required to mobilise the coarser sediment fraction on bar heads. Valley confinement is shown to exert a primary influence on patterns of bar reworking. Historical aerial photography, hyperscale DEMs and hydraulic modelling are used to explain channel adjustment at the reach scale. The proportion of the bar comprised of more frequently entrained units (tail, back channel, supra‐platform) relative to more static units (bar head) exerts a direct influence upon geomorphic sensitivity

A realisation of Lorentz algebra in Lorentz violating theory

A Lorentz non-invariant higher derivative effective action in flat spacetime, characterised by a constant vector, can be made invariant under infinitesimal Lorentz transformations by restricting the allowed field configurations. These restricted fields are defined as functions of the background vector in such a way that background dependance of the dynamics of the physical system is no longer manifest. We show here that they also provide a field basis for the realisation of Lorentz algebra and allow the construction of a Poincar\'e invariant symplectic two form on the covariant phase space of the theory.Comment: text body edited, reference adde

Studying Paths of Participation in Viral Diffusion Process

Authors propose a conceptual model of participation in viral diffusion process composed of four stages: awareness, infection, engagement and action. To verify the model it has been applied and studied in the virtual social chat environment settings. The study investigates the behavioral paths of actions that reflect the stages of participation in the diffusion and presents shortcuts, that lead to the final action, i.e. the attendance in a virtual event. The results show that the participation in each stage of the process increases the probability of reaching the final action. Nevertheless, the majority of users involved in the virtual event did not go through each stage of the process but followed the shortcuts. That suggests that the viral diffusion process is not necessarily a linear sequence of human actions but rather a dynamic system.Comment: In proceedings of the 4th International Conference on Social Informatics, SocInfo 201

Moduli and (un)attractor black hole thermodynamics

We investigate four-dimensional spherically symmetric black hole solutions in gravity theories with massless, neutral scalars non-minimally coupled to gauge fields. In the non-extremal case, we explicitly show that, under the variation of the moduli, the scalar charges appear in the first law of black hole thermodynamics. In the extremal limit, the near horizon geometry is $AdS_2\times S^2$ and the entropy does not depend on the values of moduli at infinity. We discuss the attractor behaviour by using Sen's entropy function formalism as well as the effective potential approach and their relation with the results previously obtained through special geometry method. We also argue that the attractor mechanism is at the basis of the matching between the microscopic and macroscopic entropies for the extremal non-BPS Kaluza-Klein black hole.Comment: 36 pages, no figures, V2: minor changes, misprints corrected, expanded references; V3: sections 4.3 and 4.5 added; V4: minor changes, matches the published versio

Energy band structure and intrinsic coherent properties in two weakly linked Bose Einstein Condensates

The energy band structure and energy splitting due to quantum tunneling in two weakly linked Bose-Einstein condensates were calculated by using the instanton method. The intrinsic coherent properties of Bose Josephson junction were investigated in terms of energy splitting. For $E_{C}/E_{J}\ll 1$, the energy splitting is small and the system is globally phase coherent. In the opposite limit, $E_{C}/E_{J}\gg 1$, the energy splitting is large and the system becomes a phase dissipation. Our reslults suggest that one should investigate the coherence phenomna of BJJ in proper condition such as $E_{C}/E_{J}\sim 1$.Comment: to appear in Phys. Rev. A, 2 figure

Gamma Ray Bursts as Probes of Quantum Gravity

Gamma ray bursts (GRBs) are short and intense pulses of $\gamma$-rays arriving from random directions in the sky. Several years ago Amelino-Camelia et al. pointed out that a comparison of time of arrival of photons at different energies from a GRB could be used to measure (or obtain a limit on) possible deviations from a constant speed of light at high photons energies. I review here our current understanding of GRBs and reconsider the possibility of performing these observations.Comment: Lectures given at the 40th winter school of theretical physics: Quantum Gravity and Phenomenology, Feb. 2004 Polan

Extracting Br(omega->pi^+ pi^-) from the Time-like Pion Form-factor

We extract the G-parity-violating branching ratio Br(omega->pi^+ pi^-) from the effective rho-omega mixing matrix element Pi_{rho omega}(s), determined from e^+e^- -> pi^+ pi^- data. The omega->pi^+ pi^- partial width can be determined either from the time-like pion form factor or through the constraint that the mixed physical propagator D_{rho omega}^{mu nu}(s) possesses no poles. The two procedures are inequivalent in practice, and we show why the first is preferred, to find finally Br(omega->pi^+ pi^-) = 1.9 +/- 0.3%.Comment: 12 pages (published version