19,424 research outputs found
Multispecies Fruit Flower Detection Using a Refined Semantic Segmentation Network
In fruit production, critical crop management decisions are guided by bloom intensity, i.e., the number of flowers present in an orchard. Despite its importance, bloom intensity is still typically estimated by means of human visual inspection. Existing automated computer vision systems for flower identification are based on hand-engineered techniques that work only under specific conditions and with limited performance. This letter proposes an automated technique for flower identification that is robust to uncontrolled environments and applicable to different flower species. Our method relies on an end-to-end residual convolutional neural network (CNN) that represents the state-of-the-art in semantic segmentation. To enhance its sensitivity to flowers, we fine-tune this network using a single dataset of apple flower images. Since CNNs tend to produce coarse segmentations, we employ a refinement method to better distinguish between individual flower instances. Without any preprocessing or dataset-specific training, experimental results on images of apple, peach, and pear flowers, acquired under different conditions demonstrate the robustness and broad applicability of our method
Upper limit on mh in the MSSM and M-SUGRA vs. prospective reach of LEP
The upper limit on the lightest CP-even Higgs boson mass, mh, is analyzed
within the MSSM as a function of tan(beta) for fixed mtop and Msusy. The impact
of recent diagrammatic two-loop results on this limit is investigated. We
compare the MSSM theoretical upper bound on mh with the lower bound obtained
from experimental searches at LEP. We estimate that with the LEP data taken
until the end of 1999, the region mh < 108.2 GeV can be excluded at the 95%
confidence level. This corresponds to an excluded region 0.6 <= tan(beta) <=
1.9 within the MSSM for mtop = 174.3 GeV and Msusy <= 1 TeV. The final
exclusion sensitivity after the end of LEP, in the year 2000, is also briefly
discussed. Finally, we determine the upper limit on mh within the Minimal
Supergravity (M-SUGRA) scenario up to the two-loop level, consistent with
radiative electroweak symmetry breaking. We find an upper bound of mh \approx
127 GeV for mtop = 174.3 GeV in this scenario, which is slightly below the
bound in the unconstrained MSSM.Comment: 10 pages, 3 figure
The Quest for an Intermediate-Scale Accidental Axion and Further ALPs
The recent detection of the cosmic microwave background polarimeter
experiment BICEP2 of tensor fluctuations in the B-mode power spectrum basically
excludes all plausible axion models where its decay constant is above
GeV. Moreover, there are strong theoretical, astrophysical, and cosmological
motivations for models involving, in addition to the axion, also axion-like
particles (ALPs), with decay constants in the intermediate scale range, between
GeV and GeV. Here, we present a general analysis of models
with an axion and further ALPs and derive bounds on the relative size of the
axion and ALP photon (and electron) coupling. We discuss what we can learn from
measurements of the axion and ALP photon couplings about the fundamental
parameters of the underlying ultraviolet completion of the theory. For the
latter we consider extensions of the Standard Model in which the axion and the
ALP(s) appear as pseudo Nambu-Goldstone bosons from the breaking of global
chiral (Peccei-Quinn (PQ)) symmetries, occuring accidentally as low
energy remnants from exact discrete symmetries. In such models, the axion and
the further ALP are protected from disastrous explicit symmetry breaking
effects due to Planck-scale suppressed operators. The scenarios considered
exploit heavy right handed neutrinos getting their mass via PQ symmetry
breaking and thus explain the small mass of the active neutrinos via a seesaw
relation between the electroweak and an intermediate PQ symmetry breaking
scale. We show some models that can accommodate simultaneously an axion dark
matter candidate, an ALP explaining the anomalous transparency of the universe
for -rays, and an ALP explaining the recently reported 3.55 keV gamma
line from galaxies and clusters of galaxies, if the respective decay constants
are of intermediate scale.Comment: 43pp, 4 figures. v2: version accepted for publication in JHE
Resistivity and Thermopower of Ni2.19Mn0.81Ga
In this paper, we report results of the first studies on the thermoelectric
power (TEP) of the magnetic heusler alloy NiMnGa. We explain
the observed temperature dependence of the TEP in terms of the crystal field
(CF) splitting and compare the observed behavior to that of the stoichiometric
system NiMnGa. The resistivity as a function of temperature of the two
systems serves to define the structural transition temperature, T, which is
the transition from the high temperature austenitic phase to low temperatures
the martensitic phase. Occurrence of magnetic (Curie-Weiss) and the martensitic
transition at almost the same temperature in NiMnGa has been
explained from TEP to be due to changes in the density of states (DOS) at the
Fermi level.Comment: 12 pages, 4 figures, Accepted in Physical Review B vol 70, Issue 1
Hamiltonian thermodynamics of three-dimensional dilatonic black holes
The action for a class of three-dimensional dilaton-gravity theories with a
cosmological constant can be recast in a Brans-Dicke type action, with its free
parameter. These theories have static spherically symmetric black
holes. Those with well formulated asymptotics are studied through a Hamiltonian
formalism, and their thermodynamical properties are found out. The theories
studied are general relativity (), a dimensionally reduced
cylindrical four-dimensional general relativity theory (), and a
theory representing a class of theories (). The Hamiltonian
formalism is setup in three dimensions through foliations on the right region
of the Carter-Penrose diagram, with the bifurcation 1-sphere as the left
boundary, and anti-de Sitter infinity as the right boundary. The metric
functions on the foliated hypersurfaces are the canonical coordinates. The
Hamiltonian action is written, the Hamiltonian being a sum of constraints. One
finds a new action which yields an unconstrained theory with one pair of
canonical coordinates , being the mass parameter and its
conjugate momenta The resulting Hamiltonian is a sum of boundary terms only. A
quantization of the theory is performed. The Schr\"odinger evolution operator
is constructed, the trace is taken, and the partition function of the canonical
ensemble is obtained. The black hole entropies differ, in general, from the
usual quarter of the horizon area due to the dilaton.Comment: 34 pages, 3 figures, references added, minor changes in the revised
versio
Monte Carlo Simulations of Ultrathin Magnetic Dots
In this work we study the thermodynamic properties of ultrathin ferromagnetic
dots using Monte Carlo simulations. We investigate the vortex density as a
function of the temperature and the vortex structure in monolayer dots with
perpendicular anisotropy and long-range dipole interaction. The interplay
between these two terms in the hamiltonian leads to an interesting behavior of
the thermodynamic quantities as well as the vortex density.Comment: 10 figure
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