726 research outputs found
Does the complexity in temporal precipitation disaggregation matter for a lumped hydrological model?
Flood peaks and volumes are essential design variables and can be simulated by precipitation–runoff (P–R) modelling. The high-resolution precipitation time series that are often required for this purpose can be generated by various temporal disaggregation methods. Here, we compare a simple method (M1, one parameter), focusing on the effective precipitation duration for flood simulations, with a multiplicative cascade model (M2, 32/36 parameters). While M2 aims at generating realistic characteristics of precipitation time series, M1 aims only at accurately reproducing flood variables by P–R modelling. Both disaggregation methods were tested on precipitation time series of nine Swiss mesoscale catchments. The generated high-resolution time series served as input for P–R modelling using a lumped HBV model. The results indicate that differences identified in precipitation characteristics of disaggregated time series vanish when introduced into the lumped hydrological model. Moreover, flood peaks were more sensitive than flood volumes to the choice of disaggregation method. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
Non-minimal Wu-Yang monopole
We discuss new exact spherically symmetric static solutions to non-minimally
extended Einstein-Yang-Mills equations. The obtained solution to the Yang-Mills
subsystem is interpreted as a non-minimal Wu-Yang monopole solution. We focus
on the analysis of two classes of the exact solutions to the gravitational
field equations. Solutions of the first class belong to the
Reissner-Nordstr{\"o}m type, i.e., they are characterized by horizons and by
the singularity at the point of origin. The solutions of the second class are
regular ones. The horizons and singularities of a new type, the non-minimal
ones, are indicated.Comment: 10 pages, no figures, typos correcte
CIRRUS-HL: Overview of LIM contributions
From June to July 2021, the Leipzig Institute for Meteorology (LIM)
participated in the Cirrus in High Latitudes (CIRRUS-HL) campaign. Utilizing the
German High Altitude Long Range Research Aircraft (HALO), 24 research flights were
conducted out of Oberpfaffenhofen, Germany. The initial goal of the campaign was
to sample high-latitude cirrus clouds with a combination of in-situ and remote sensing
instrumentation. However, due to the global coronavirus pandemic, the flights had to
be carried out from southern Germany instead of northern Sweden. Thus, the flight
time in Arctic latitudes was limited. Therefore, more objectives concerning midlatitude
cirrus were included in the campaign goals. LIM contributed to CIRRUS-HL with
measurements by the Broadband AirCrAft RaDiometer Instrumentation (BACARDI)
and the Spectral Modular Airborne Radiation measurement sysTem (SMART). While
BACARDI measured broadband solar and terrestrial upward and downward irradiance,
SMART measured spectrally resolved solar upward radiance as well as upward and
downward irradiance.Von Juni bis Juli 2021 nahmen einige Mitarbeitende des LIM
an der CIRRUS-HL Kampagne teil. Mit dem deutschen Forschungsflugzeug HALO
(High Altitude Long Range Research Aircraft) wurden 24 Forschungsflüge von Oberpfaffenhofen,
Deutschland, aus durchgeführt. Ursprüngliches Ziel der Kampagne war es,
Zirruswolken in hohen Breitengraden mit einer Kombination aus In-situ- und Fernerkundungsinstrumenten
zu untersuchen. Aufgrund der weltweiten Corona-Pandemie mussten
die Flüge jedoch von Süddeutschland statt von Nordschweden aus durchgeführt werden.
Daher wurden weitere Ziele in Bezug auf Zirruswolken in mittleren Breiten in die Ziele
der Kampagne aufgenommen. Das LIM-Team betrieb die breitbandigen und spektralen
Strahlungssensoren BACARDI (Broadband AirCrAft RaDiometer Instrumentation) und
SMART (Spectral Modular Airborne Radiation measurement sysTem), wobeiBACARDI
die breitbandige solare und terrestrische Auf- und Abwärtsstrahlung und SMART die
spektral aufgelöste solareAuf- undAbwärtsstrahlung sowie dieAufwärtsstrahlungsdichte
maß
Considerations on the quantum double-exchange Hamiltonian
Schwinger bosons allow for an advantageous representation of quantum
double-exchange. We review this subject, comment on previous results, and
address the transition to the semiclassical limit. We derive an effective
fermionic Hamiltonian for the spin-dependent hopping of holes interacting with
a background of local spins, which is used in a related publication within a
two-phase description of colossal magnetoresistant manganites.Comment: 7 pages, 3 figure
Distance transform: a tool for the study of animal colour patterns
Summary
The information in animal colour patterns plays a key role in many ecological interactions; quantification would help us to study them, but this is problematic. Comparing patterns using human judgement is subjective and inconsistent. Traditional shape analysis is unsuitable as patterns do not usually contain conserved landmarks. Alternative statistical approaches also have weaknesses, particularly as they are generally based on summary measures that discard most or all of the spatial information in a pattern.
We present a method for quantifying the similarity of a pair of patterns based on the distance transform of a binary image. The method compares the whole pattern, pixel by pixel, while being robust to small spatial variations among images.
We demonstrate the utility of the distance transform method using three ecological examples. We generate a measure of mimetic accuracy between hoverflies (Diptera: Syrphidae) and wasps (Hymenoptera) based on abdominal pattern and show that this correlates strongly with the perception of a model predator (humans). We calculate similarity values within a group of mimetic butterflies and compare this with proposed pairings of Müllerian comimics. Finally, we characterise variation in clypeal badges of a paper wasp (Polistes dominula) and compare this with previous measures of variation.
While our results generally support the findings of existing studies that have used simpler ad hoc methods for measuring differences between patterns, our method is able to detect more subtle variation and hence reveal previously overlooked trends
Volatilization of parathion and chlorothalonil after spraying onto a potato crop
At fourteen times after application of parathion and chlorothalonil to a potato crop their rates of volatilization were determined by the aerodynamic and Bowen ratio methods. The highest volatilization rate of parathion occurred shortly after application. In the first hours after application its volatilization rate decreased sharply; thereafter it decreased more gradually. The volatilization rate of chlorothalonil at one week after application did not differ much from that shortly after application. Weather conditions in the first twenty-four hours after application of both pesticides were simulated in a chamber. The volatilization of parathion in the chamber had the same order of magnitude as that determined in the field
Surface Effects in Magnetic Microtraps
We have investigated Bose-Einstein condensates and ultra cold atoms in the
vicinity of a surface of a magnetic microtrap. The atoms are prepared along
copper conductors at distances to the surface between 300 um and 20 um. In this
range, the lifetime decreases from 20 s to 0.7 s showing a linear dependence on
the distance to the surface. The atoms manifest a weak thermal coupling to the
surface, with measured heating rates remaining below 500 nK/s. In addition, we
observe a periodic fragmentation of the condensate and thermal clouds when the
surface is approached.Comment: 4 pages, 4 figures; v2: corrected references; v3: final versio
Effective metrics in the non-minimal Einstein-Yang-Mills-Higgs theory
We formulate a self-consistent non-minimal five-parameter
Einstein-Yang-Mills-Higgs (EYMH) model and analyse it in terms of effective
(associated, color and color-acoustic) metrics. We use a formalism of
constitutive tensors in order to reformulate master equations for the gauge,
scalar and gravitational fields and reconstruct in the algebraic manner the
so-called associated metrics for the Yang-Mills field. Using WKB-approximation
we find color metrics for the Yang-Mills field and color-acoustic metric for
the Higgs field in the framework of five-parameter EYMH model. Based on
explicit representation of these effective metrics for the EYMH system with
uniaxial symmetry, we consider cosmological applications for Bianchi-I, FLRW
and de Sitter models. We focus on the analysis of the obtained expressions for
velocities of propagation of longitudinal and transversal color and
color-acoustic waves in a (quasi)vacuum interacting with curvature; we show
that curvature coupling results in time variations of these velocities. We
show, that the effective metrics can be regular or can possess singularities
depending on the choice of the parameters of non-minimal coupling in the
cosmological models under discussion. We consider a physical interpretation of
such singularities in terms of phase velocities of color and color-acoustic
waves, using the terms ``wave stopping'' and ``trapped surface''.Comment: 25 pages, no figures, accepted to Annals of Physic
Microscopic theory of single-electron tunneling through molecular-assembled metallic nanoparticles
We present a microscopic theory of single-electron tunneling through metallic
nanoparticles connected to the electrodes through molecular bridges. It
combines the theory of electron transport through molecular junctions with the
description of the charging dynamics on the nanoparticles. We apply the theory
to study single-electron tunneling through a gold nanoparticle connected to the
gold electrodes through two representative benzene-based molecules. We
calculate the background charge on the nanoparticle induced by the charge
transfer between the nanoparticle and linker molecules, the capacitance and
resistance of molecular junction using a first-principles based Non-Equilibrium
Green's Function theory. We demonstrate the variety of transport
characteristics that can be achieved through ``engineering'' of the
metal-molecule interaction.Comment: To appear in Phys. Rev.
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