708 research outputs found
Assessment of coastal fish assemblages before the establishment of a new marine protected area in central Mediterranean: its role in formulating zoning proposal
The fish assemblages of the coastal area of the promontory of Cape Milazzo (Italy, Central Mediterranean), which has been recently designated by the Italian Law to become a national marine protected area (MPA), were characterized by visual censuses carried out over different habitats (rocky algal reef, Posidonia oceanica meadow and soft bottom) and depth ranges (0-3, 4-7, 12-16 and 24-30 m) to identify areas of major concern for the MPA zoning. The study area was divided into 6 sectors to assess spatial-related differences in the assemblage parameters, such as species composition and richness, and the size structure of species of recreational (e.g. SCUBA diving) interest. Fifty-eight taxa (56 species and 2 genera) and 20 families of fishes were totally recorded. Species composition was significantly affected by habitat and depth, whereas no significant changes were detected among sectors. Conversely, species richness and total density of fish showed no significant differences among sectors, habitat types and depth ranges. The majority of species of recreational value was recorded only off the northwestern part of the promontory. The implementation of fishing ban in such an area, characterized by the presence of a rocky bank, would contribute to the recovery of populations of some emblematic species (e.g. groupers and other large predator) and to the enhancement of environmentally sustainable activities such as scuba diving. Throughout the investigated area and, especially, in the eastern and southwestern coasts of the promontory, several species were almost exclusively represented by small and medium sized individuals, a likely consequence of an intense fishing pressure
A classical explanation of quantization
In the context of our recently developed emergent quantum mechanics, and, in
particular, based on an assumed sub-quantum thermodynamics, the necessity of
energy quantization as originally postulated by Max Planck is explained by
means of purely classical physics. Moreover, under the same premises, also the
energy spectrum of the quantum mechanical harmonic oscillator is derived.
Essentially, Planck's constant h is shown to be indicative of a particle's
"zitterbewegung" and thus of a fundamental angular momentum. The latter is
identified with quantum mechanical spin, a residue of which is thus present
even in the non-relativistic Schroedinger theory.Comment: 20 pages; version accepted for publication in Foundations of Physic
The Quantum as an Emergent System
Double slit interference is explained with the aid of what we call
"21stcentury classical physics". We model a particle as an oscillator
("bouncer") in a thermal context, which is given by some assumed "zero-point"
field of the vacuum. In this way, the quantum is understood as an emergent
system, i.e., a steady-state system maintained by a constant throughput of
(vacuum) energy. To account for the particle's thermal environment, we
introduce a "path excitation field", which derives from the thermodynamics of
the zero-point vacuum and which represents all possible paths a particle can
take via thermal path fluctuations. The intensity distribution on a screen
behind a double slit is calculated, as well as the corresponding trajectories
and the probability density current. Further, particular features of the
relative phase are shown to be responsible for nonlocal effects not only in
ordinary quantum theory, but also in our classical approach.Comment: 24 pages, 2 figures, based on a talk given at "Emergent Quantum
Mechanics (Heinz von Foerster Conference 2011)",
http://www.univie.ac.at/hvf11/congress/EmerQuM.htm
Dietary Fat Patterns and Outcomes in Acute Pancreatitis in Spain
Background/Objective: Evidence from basic and clinical studies suggests that unsaturated fatty acids (UFAs) might be relevant mediators of the development of complications in acute pancreatitis (AP). Objective: The aim of this study was to analyze outcomes in patients with AP from regions in Spain with different patterns of dietary fat intake.
Materials and Methods: A retrospective analysis was performed with data from 1,655 patients with AP from a Spanish prospective cohort study and regional nutritional data from a Spanish cross-sectional study. Nutritional data considered in the study concern the total lipid consumption, detailing total saturated fatty acids, UFAs and monounsaturated fatty acids (MUFAs) consumption derived from regional data and not from the patient prospective cohort. Two multivariable analysis models were used: (1) a model with the Charlson comorbidity index, sex, alcoholic etiology, and recurrent AP; (2) a model that included these variables plus obesity.
Results: In multivariable analysis, patients from regions with high UFA intake had a significantly increased frequency of local complications, persistent organ failure (POF), mortality, and moderate-to-severe disease in the model without obesity and a higher frequency of POF in the model with obesity. Patients from regions with high MUFA intake had significantly more local complications and moderate-to-severe disease; this significance remained for moderate-to-severe disease when obesity was added to the model.
Conclusions: Differences in dietary fat patterns could be associated with different outcomes in AP, and dietary fat patterns may be a pre-morbid factor that determines the severity of AP. UFAs, and particulary MUFAs, may influence the pathogenesis of the severity of AP
An explanation of interference effects in the double slit experiment: Classical trajectories plus ballistic diffusion caused by zero-point fluctuations
A classical explanation of interference effects in the double slit experiment
is proposed. We claim that for every single "particle" a thermal context can be
defined, which reflects its embedding within boundary conditions as given by
the totality of arrangements in an experimental apparatus. To account for this
context, we introduce a "path excitation field", which derives from the
thermodynamics of the zero-point vacuum and which represents all possible paths
a "particle" can take via thermal path fluctuations. The intensity distribution
on a screen behind a double slit is calculated, as well as the corresponding
trajectories and the probability density current. The trajectories are shown to
obey a "no crossing" rule with respect to the central line, i.e., between the
two slits and orthogonal to their connecting line. This agrees with the Bohmian
interpretation, but appears here without the necessity of invoking the quantum
potential.Comment: 26 pages, 6 figures; accepted version to be published in Annals of
Physics (2012
Semi-Dense 3D Reconstruction with a Stereo Event Camera
Event cameras are bio-inspired sensors that offer several advantages, such as
low latency, high-speed and high dynamic range, to tackle challenging scenarios
in computer vision. This paper presents a solution to the problem of 3D
reconstruction from data captured by a stereo event-camera rig moving in a
static scene, such as in the context of stereo Simultaneous Localization and
Mapping. The proposed method consists of the optimization of an energy function
designed to exploit small-baseline spatio-temporal consistency of events
triggered across both stereo image planes. To improve the density of the
reconstruction and to reduce the uncertainty of the estimation, a probabilistic
depth-fusion strategy is also developed. The resulting method has no special
requirements on either the motion of the stereo event-camera rig or on prior
knowledge about the scene. Experiments demonstrate our method can deal with
both texture-rich scenes as well as sparse scenes, outperforming
state-of-the-art stereo methods based on event data image representations.Comment: 19 pages, 8 figures, Video: https://youtu.be/Qrnpj2FD1e
Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip
The ATLAS Collaboration will upgrade its semiconductor pixel tracking
detector with a new Insertable B-layer (IBL) between the existing pixel
detector and the vacuum pipe of the Large Hadron Collider. The extreme
operating conditions at this location have necessitated the development of new
radiation hard pixel sensor technologies and a new front-end readout chip,
called the FE-I4. Planar pixel sensors and 3D pixel sensors have been
investigated to equip this new pixel layer, and prototype modules using the
FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN
SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test
results are presented, including charge collection efficiency, tracking
efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS
- …