1,741 research outputs found
Owls (Strigiformes) in Parque Nacional Peneda-Gerês (PNPG) – Portugal
Owls (Strigiformes) are particularly difficult to study and the existing information is still scarce. In PNPG
area there are records of the seven species present in Portugal; the Long-eared Owl and the Short-eared Owl are
here occasional species. This work aims to determine the distribution, density and abundance of Strigiformes in
PNPG (Northwest of Portugal). Between December 2007 and June 2008, 106 passive hearing point counts of
15 minutes each were done in the centre of each of 106 squares (2x2 km). Distribution maps for each species
were obtained. Therefore, we recorded a total of 98 contacts for Tawny Owl and 67 contacts for Scops Owl.
We also obtained 7 contacts of Little Owl, 2 contacts of Barn Owl and one of Eagle Owl. The habitat selection
by Scops Owl and Tawny Owl was also studied. Scops Owls seems to avoid low shrub and preferred forested
areas. Tawny Owls also avoid low shrub areas, preferring forested areas, and were found in urban areas. The
populations of these two species in PNPG show a considerable expansion, while the other ones reveal a marked
decline regarding the previous situation. The implementation of monitoring and conservation measures is suggested
to stop the decline of these three species
Gas Emissions From the Western Aleutians Volcanic Arc
The Aleutian Arc is remote and highly active volcanically. Its 4,000 km extent from mainland Alaska to Russia\u2019s Kamchatka peninsula hosts over 140 volcanic centers of which about 50 have erupted in historic times. We present data of volcanic gas samples and gas emission measurements obtained during an expedition to the western-most segment of the arc in September 2015 in order to extend the sparse knowledge on volatile emissions from this remote but volcanically active region. Some of the volcanoes investigated here have not been sampled for gases before this writing. Our data show that all volcanoes host high-temperature magmatic-hydrothermal systems and have gas discharges typical of volcanoes in oceanic arcs. Based on helium isotopes, the western Aleutian Arc segment has minimal volatile contributions from the overriding crust. Volcanic CO2 fluxes from this arc segment are small, compared to the emissions from volcanoes on the Alaska Peninsula and mainland Alaska. The comparatively low CO2 emissions may be related to the lower sediment flux delivered to the trench in this part of the arc
Collective edge modes in fractional quantum Hall systems
Over the past few years one of us (Murthy) in collaboration with R. Shankar
has developed an extended Hamiltonian formalism capable of describing the
ground state and low energy excitations in the fractional quantum Hall regime.
The Hamiltonian, expressed in terms of Composite Fermion operators,
incorporates all the nonperturbative features of the fractional Hall regime, so
that conventional many-body approximations such as Hartree-Fock and
time-dependent Hartree-Fock are applicable. We apply this formalism to develop
a microscopic theory of the collective edge modes in fractional quantum Hall
regime. We present the results for edge mode dispersions at principal filling
factors and for systems with unreconstructed edges. The
primary advantage of the method is that one works in the thermodynamic limit
right from the beginning, thus avoiding the finite-size effects which
ultimately limit exact diagonalization studies.Comment: 12 pages, 9 figures, See cond-mat/0303359 for related result
Invariant Measures and Decay of Correlations for a Class of Ergodic Probabilistic Cellular Automata
We give new sufficient ergodicity conditions for two-state probabilistic
cellular automata (PCA) of any dimension and any radius. The proof of this
result is based on an extended version of the duality concept. Under these
assumptions, in the one dimensional case, we study some properties of the
unique invariant measure and show that it is shift-mixing. Also, the decay of
correlation is studied in detail. In this sense, the extended concept of
duality gives exponential decay of correlation and allows to compute
explicitily all the constants involved
Variability type classification of multi-epoch surveys
The classification of time series from photometric large scale surveys into
variability types and the description of their properties is difficult for
various reasons including but not limited to the irregular sampling, the
usually few available photometric bands, and the diversity of variable objects.
Furthermore, it can be seen that different physical processes may sometimes
produce similar behavior which may end up to be represented as same models. In
this article we will also be presenting our approach for processing the data
resulting from the Gaia space mission. The approach may be classified into
following three broader categories: supervised classification, unsupervised
classifications, and "so-called" extractor methods i.e. algorithms that are
specialized for particular type of sources. The whole process of
classification- from classification attribute extraction to actual
classification- is done in an automated manner.Comment: 6 pages, 2 figures. Version with figures as sent to the Editor/AIP
(though not as published). Minor corrections mad
Hamiltonian Description of Composite Fermions: Magnetoexciton Dispersions
A microscopic Hamiltonian theory of the FQHE, developed by Shankar and myself
based on the fermionic Chern-Simons approach, has recently been quite
successful in calculating gaps in Fractional Quantum Hall states, and in
predicting approximate scaling relations between the gaps of different
fractions. I now apply this formalism towards computing magnetoexciton
dispersions (including spin-flip dispersions) in the , 2/5, and 3/7
gapped fractions, and find approximate agreement with numerical results. I also
analyse the evolution of these dispersions with increasing sample thickness,
modelled by a potential soft at high momenta. New results are obtained for
instabilities as a function of thickness for 2/5 and 3/7, and it is shown that
the spin-polarized 2/5 state, in contrast to the spin-polarized 1/3 state,
cannot be described as a simple quantum ferromagnet.Comment: 18 pages, 18 encapsulated ps figure
Star formation histories in mergers: the spatially resolved properties of the early-stage merger luminous infrared galaxies IC 1623 and NGC 6090
The role of major mergers in galaxy evolution is investigated through a detailed characterization of the stellar populations, ionized gas properties and star formation rates (SFR) in the early-stage merger luminous infrared galaxies (LIRGs) IC 1623 W and NGC 6090, by analysing optical integral field spectroscopy and high-resolution Hubble Space Telescope imaging. The spectra were processed with the starlight full spectral fitting code, and the emission lines measured in the residual spectra. The results are compared with non-interacting control spiral galaxies from the Calar Alto Legacy Integral Field Area survey. Merger-induced star formation is extended and recent, as revealed by the young ages (50–80 Myr) and high contributions to light of young stellar populations (50–90 per cent), in agreement with merger simulations in the literature. These early-stage mergers have positive central gradients of the stellar metallicity, with an average ∼0.6 Z⊙. Compared to non-interacting spirals, they have lower central nebular metallicity, and flatter profiles, in agreement with the gas inflow scenario. We find that they are dominated by star formation, although shock excitation cannot be discarded in some regions, where high velocity dispersion is found (170–200 km s−1). The average SFR in these early-stage mergers (∼23–32 M⊙ yr−1) is enhanced with respect to main-sequence Sbc galaxies by factors of 6–9, slightly above the predictions from classical merger simulations, but still possible in about 15 per cent of major galaxy mergers, where U/LIRGs belong
Journalism, journalism education and a region's integration: The case of Southeast Asia
The 50-year-old Association of Southeast Asian Nations (ASEAN) is now in its third year implementing the mechanics of regional integration. How does this region-wide development affect journalism in individual countries and in the region? This qualitative research sought to find out the meaning and implications of regional integration to journalism practice and education in Southeast Asia. There is enthusiasm over developing a model on ‘ASEAN-centered journalism and journalism education’, however there are country-level realities that news organisations and journalism schools face before proceeding to even attuning reportage and journalism instruction to the needs of ASEAN.Jeremaiah M. Opiniano, Aira L. Bagtas, Karl C. Basco, Raplh J. Hernandez,
Elyssa C. Lopez, Michael C. Rodolfo and Anne K. Vich
Hamiltonian theory of gaps, masses and polarization in quantum Hall states: full disclosure
I furnish details of the hamiltonian theory of the FQHE developed with Murthy
for the infrared, which I subsequently extended to all distances and apply it
to Jain fractions \nu = p/(2ps + 1). The explicit operator description in terms
of the CF allows one to answer quantitative and qualitative issues, some of
which cannot even be posed otherwise. I compute activation gaps for several
potentials, exhibit their particle hole symmetry, the profiles of charge
density in states with a quasiparticles or hole, (all in closed form) and
compare to results from trial wavefunctions and exact diagonalization. The
Hartree-Fock approximation is used since much of the nonperturbative physics is
built in at tree level. I compare the gaps to experiment and comment on the
rough equality of normalized masses near half and quarter filling. I compute
the critical fields at which the Hall system will jump from one quantized value
of polarization to another, and the polarization and relaxation rates for half
filling as a function of temperature and propose a Korringa like law. After
providing some plausibility arguments, I explore the possibility of describing
several magnetic phenomena in dirty systems with an effective potential, by
extracting a free parameter describing the potential from one data point and
then using it to predict all the others from that sample. This works to the
accuracy typical of this theory (10 -20 percent). I explain why the CF behaves
like free particle in some magnetic experiments when it is not, what exactly
the CF is made of, what one means by its dipole moment, and how the comparison
of theory to experiment must be modified to fit the peculiarities of the
quantized Hall problem
Distinct roles of SNARE-mimicking lipopeptides during initial steps of membrane fusion
NWOSupramolecular & Biomaterials Chemistr
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