599 research outputs found
Edge-Of-Field Water And Phosphorus Losses In Surface And Subsurface Agricultural Runoff
Quantifying effectiveness of soil management practices on surface and subsurface water quality at the field scale is becoming increasingly important in the Lake Champlain Basin and other agricultural watersheds. During 2012 and 2013, field plots (22.9 x 45.7 m) were established at the Lake Alice Wildlife Area in Chazy, NY to begin a long-term water quality monitoring study. Plots were established in a cool season grass field (1 ha) leased and managed by the William H. Miner Agricultural Research Institute in Chazy, NY. The soil type transitions from an excessively drained outwash soil on the upslope to a very poorly drained silty clay series at the toeslope. Tile drainage lines were installed in each plot and drained to concrete manholes at the corner of each plot where water was sampled and measured. Plots were randomly assigned to a tile-drained (TD) or naturally-drained treatment (UD). Tile outlets were plugged in the UD treatment to enable natural drainage conditions. Surface runoff water was collected at the lower boundary of each plot by shallow PVC-lined trenches that outlet to the manholes. Continuous water flow from each hydrologic pathway was measured in 5-gallon buckets with v-notch weirs and pressure transducers. Total phosphorus (TP), soluble reactive phosphorus SRP), unreactive phosphorus (UP) and sediment (TSS) loads were estimated by multiplying the mean hourly runoff volume by the respective sample concentration for each hydrologic pathway.
Data were collected April 21, 2014 through June 30, 2015. Loading rates were unable to be calculated from February 22, 2015 through April 9, 2015 due to freeze/thaw cycles preventing accurate water flow data collection. Event-based loading for TP, SRP, UP, TSS, and water yield were calculated in addition to cumulative losses over the study duration. No significant differences in cumulative TP exports were found between treatments (UD = 230.9 g ha-1; TD = 233.9 g ha-1). Approximately 55% more SRP and 158% more TSS was exported by UD (130.8 g ha-1; 168.8 kg ha-1) than TD (84.2 g ha-1; 65.5 kg ha-1). Unreactive P exports from TD (149.7 g ha-1) were 50% greater than UD (100.1 g ha-1). Two runoff events dominated the treatment response. An intense rain storm on May 16, 2014 generated the greatest sediment losses in both treatments during an individual event, contributing 65 and 67% of the cumulative losses from TD and UD, respectively. This event was also responsible for 40% of UP losses from TD. A 3 d rain/snowmelt event beginning on December 24, 2014 resulted in 61 and 84% of all SRP losses for TD and UD, respectively. The results of this study indicate that tile drainage may not have a negative impact on water quality relative to a naturally drained field. However, additional years of data are needed to develop more robust conclusions as different management strategies and weather conditions could result in different outcomes
Non perturbative Adler-Bardeen Theorem
The Adler-Bardeen theorem has been proved only as a statement valid at all
orders in perturbation theory, without any control on the convergence of the
series. In this paper we prove a nonperturbative version of the Adler-Bardeen
theorem in by using recently developed technical tools in the theory of
Grassmann integration.Comment: 28 pages, 14 figure
Föderalismus ohne Insolvenz?
Die bestehenden Kreditbegrenzungen der öffentlichen Haushalte haben sich in der Vergangenheit als nicht wirksam erwiesen. Eine Reihe von Bundesländern kann mittelfristig die Finanzprobleme nicht mehr aus eigener Kraft lösen. Drei Länder klagen derzeit vor dem Bundesverfassungsgericht auf bundesstaatliche Hilfe. Wie kann eine übermäßige Verschuldung der Bundesländer verhindert werden? --
Relativistic strong-field ionization of hydrogen-like atomic systems in constant crossed electromagnetic fields
Relativistic strong-field ionization of hydrogen-like atoms or ions in a
constant crossed electromagnetic field is studied. The transition amplitude is
formulated within the strong-field approximation in G\"oppert-Mayer gauge, with
initial and final electron states being described by the corresponding
Dirac-Coulomb and Dirac-Volkov wave functions, respectively. Coulomb
corrections to the electron motion during tunneling are taken into account by
adjusting an established method to the present situation. Total and
energy-differential ionization rates are calculated and compared with
predictions from other theories in a wide range of atomic numbers and applied
field strengths.Comment: 9 pages, 4 figure
Relativistic ionization-rescattering with tailored laser pulses
The interaction of relativistically strong tailored laser pulses with an
atomic system is considered. Due to a special tailoring of the laser pulse, the
suppression of the relativistic drift of the ionized electron and a dramatic
enhancement of the rescattering probability is shown to be achievable. The high
harmonic generation rate in the relativistic regime is calculated and shown to
be increased by several orders of magnitude compared to the case of
conventional laser pulses. The energies of the revisiting electron at the
atomic core can approach the MeV domain, thus rendering hard x-ray harmonics
and nuclear reactions with single atoms feasible
Exact Asymptotic Behaviour of Fermion Correlation Functions in the Massive Thirring Model
We obtain an exact asymptotic expression for the two-point fermion
correlation functions in the massive Thirring model (MTM) and show that, for
, they reproduce the exactly known corresponding functions of the
massless theory, explicitly confirming the irrelevance of the mass term at this
point. This result is obtained by using the Coulomb gas representation of the
fermionic MTM correlators in the bipolar coordinate system.Comment: To appear in J. Phys. A: Math. Gen. 12 page
Quantum Electrodynamics in Two-Dimensions at Finite Temperature. Thermofield Bosonization Approach
The Schwinger model at finite temperature is analyzed using the Thermofield
Dynamics formalism. The operator solution due to Lowenstein and Swieca is
generalized to the case of finite temperature within the thermofield
bosonization approach. The general properties of the statistical-mechanical
ensemble averages of observables in the Hilbert subspace of gauge invariant
thermal states are discussed. The bare charge and chirality of the Fermi
thermofields are screened, giving rise to an infinite number of mutually
orthogonal thermal ground states. One consequence of the bare charge and
chirality selection rule at finite temperature is that there are innumerably
many thermal vacuum states with the same total charge and chirality of the
doubled system. The fermion charge and chirality selection rules at finite
temperature turn out to imply the existence of a family of thermal theta vacua
states parametrized with the same number of parameters as in zero temperature
case. We compute the thermal theta-vacuum expectation value of the mass
operator and show that the analytic expression of the chiral condensate for any
temperature is easily obtained within this approach, as well as, the
corresponding high-temperature behavior
Smooth Bosonization as a Quantum Canonical Transformation
We consider a 1+1 dimensional field theory which contains both a complex
fermion field and a real scalar field. We then construct a unitary operator
that, by a similarity transformation, gives a continuum of equivalent theories
which smoothly interpolate between the massive Thirring model and the
sine-Gordon model. This provides an implementation of smooth bosonization
proposed by Damgaard et al. as well as an example of a quantum canonical
transformation for a quantum field theory.Comment: 20 pages, revte
On renormalizability of the massless Thirring model
We discuss the renormalizability of the massless Thirring model in terms of
the causal fermion Green functions and correlation functions of left-right
fermion densities. We obtain the most general expressions for the causal
two-point Green function and correlation function of left-right fermion
densities with dynamical dimensions of fermion fields, parameterised by two
parameters. The region of variation of these parameters is constrained by the
positive definiteness of the norms of the wave functions of the states related
to components of the fermion vector current. We show that the dynamical
dimensions of fermion fields calculated for causal Green functions and
correlation functions of left-right fermion densities can be made equal. This
implies the renormalizability of the massless Thirring model in the sense that
the ultra-violet cut-off dependence, appearing in the causal fermion Green
functions and correlation functions of left-right fermion densities, can be
removed by renormalization of the wave function of the massless Thirring
fermion fields only.Comment: 17 pages, Latex, the contribution of fermions with opposite chirality
is added,the parameterisation of fermion determinant by two parameters is
confirmed,it is shown that dynamical dimensions of fermion fields calculated
from different correlation functions can be made equal.This allows to remove
the dependence on the ultra-violet cut-off by the renormalization of the wave
function of Thirring fermion fields onl
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