1,525 research outputs found
The detailed mechanism of the eta production in pp scattering up to the Tlab = 4.5 GeV
Contrary to very early beliefs, the experimental cross section data for the
eta production in proton-proton scattering are well described if pi and only
eta meson exchange diagrams are used to calculate the Born term. The inclusion
of initial and final state interactions is done in the factorization
approximation by using the inverse square of the Jost function. The two body
Jost functions are obtained from the S matrices in the low energy effective
range approximation. The danger of double counting in the p-eta final state
interaction is discussed. It is shown that higher partial waves in
meson-nucleon amplitudes do not contribute significantly bellow excess energy
of Q=100 MeV. Known difficulties of reducing the multi resonance model to a
single resonance one are illustrated.Comment: 10 pages, 5 figures, corrected typos in relation (3), changed content
(added section with differential cross sections
Multichannel Anomaly of the Resonance Pole Parameters Resolved
Inspired by anomalies which the standard scattering matrix pole-extraction
procedures have produced in a mathematically well defined coupled-channel
model, we have developed a new method based solely on the assumption of
partial-wave analyticity. The new method is simple and applicable not only to
theoretical predictions but to the empirical partial-wave data as well. Since
the standard pole-extraction procedures turn out to be the lowest-order term of
the proposed method the anomalies are understood and resolved.Comment: 5 page
Spatially-Aware Autoencoders for Detecting Contextual Anomalies in Geo-Distributed Data
The huge amount of data generated by sensor networks enables many potential analyses. However, one important limiting factor for the analyses of sensor data is the possible presence of anomalies, which may affect the validity of any conclusion we could draw. This aspect motivates the adoption of a preliminary anomaly detection method. Existing methods usually do not consider the spatial nature of data generated by sensor networks. Properly modeling the spatial nature of the data, by explicitly considering spatial autocorrelation phenomena, has the potential to highlight the degree of agreement or disagreement of multiple sensor measurements located in different geographical positions. The intuition is that one could improve anomaly detection performance by considering the spatial context. In this paper, we propose a spatially-aware anomaly detection method based on a stacked auto-encoder architecture. Specifically, the proposed architecture includes a specific encoding stage that models the spatial autocorrelation in data observed at different locations. Finally, a distance-based approach leverages the embedding features returned by the auto-encoder to identify possible anomalies. Our experimental evaluation on real-world geo-distributed data collected from renewable energy plants shows the effectiveness of the proposed method, also when compared to state-of-the-art anomaly detection methods
Direct numerical simulations of turbulent pipe flow at high Reynolds number
This paper is associated with a video winner of a 2021 American Physical Society’s
Division of Fluid Dynamics (DFD) Gallery of Fluid Motion Award for work presented at
the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of
Fluid Motion, https://doi.org/10.1103/APS.DFD.2021.GFM.V005
Pilot study of the relationship between deck level and journey duration on plasma cortisol, epinephrine and norepinephrine levels in italian heavy pigs
The aim of this pilot study was to evaluate the relationship between journey duration, deck level and activation patterns of the hypothalamic-pituitary-adrenocortical axis (HPA) and sympathetic adrenal medullary system (SAM) in pigs. A total of 90 pigs were examined. The animals came from three different Italian farms associated with the same slaughterhouse located in Bari (Apulia region-Italy). A group of thirty animals was transported from Pordenone (11 h journey); a second group was transported from Terni (6.5 h journey); a third group was transported from Benevento (3 h journey). The animals were transported in the same vehicle, which complied with the structural characteristics indicated in the Council Regulation (EC) No. 1/2005. The truck was composed of a lorry and a trailer, each one divided into three decks. Only the animals transported in the trailer were tested for the study. Before transportation, blood samples were collected on each farm, at 6:00 a.m., from 30 pigs randomly selected out of 135 pigs ready to be transported. Blood samples were also collected during slaughter to evaluate plasma cortisol, epinephrine and norepinephrine, around 6:00 a.m. A journey duration of 11 h was associated with significantly higher plasma concentrations of stress hormones compared with shorter journeys. This increase was proportional to the journey duration, with the pigs travelling for 6.5 h displaying intermediate concentrations between those noticed after 3 h and 11 h journeys. The interaction between deck and journey distance was not significant on epinephrine, norepinephrine or cortisol levels collected at arrival. There was a significant effect of deck level on norepinephrine levels (p < 0.0001), a tendency to influence epinephrine levels (p = 0.073) but no effect on cortisol levels (p = 0.945). Overall, we observed that an 11 h-long journey seemed to impact negatively on pigs\u2019 HPA-SAM activity, likely requiring the animals to spend more time in the lairage facilities to recover
Phenomenology of pp->pp eta reaction close to threshold
The recent high statistics measurement of the pp -> pp eta reaction at an
excess energy Q=15.5 MeV has been analysed by means of partial wave
decomposition of the cross section. Guided by the dominance of the final state
1S0 pp interaction (FSI), we keep only terms involving the FSI enhancement
factor. The measured p-p and p-eta effective mass spectra can be well
reproduced by lifting the standard on-shell approximation in the enhancement
factor and by allowing for a linear energy dependence in the leading 3P0->1S0,s
partial wave amplitude. Higher partial waves seem to play only a marginal role
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