Search results for "Sunset"
showing 10 items of 12 documents
Diurnal timing of nonmigratory movement by birds: the importance of foraging spatial scales
2020
Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of timing of movement activity among species using six temporal variables: start of activity relative to sunrise, end of activity relative to sunset, relative speed at midday, number of movement bouts, bout duration and proportion of active daytime hours. We test for the influence of flight mode and foraging habitat on the timing of movement activit…
Experienced Migratory Bats Integrate the Sun's Position at Dusk for Navigation at Night.
2019
Summary From bats to whales, millions of mammals migrate every year. However, their navigation capacity for accomplishing long-distance movements remains remarkably understudied and lags behind by five decades compared to other animals [ 1 , 2 ]—partly because, unlike for other taxa, such as birds and sea turtles, no small-scale orientation assay has so far been developed. Yet recently, bats became a model to investigate which cues mammals use for long-range navigation, and, surprisingly for nocturnal animals, sunset cues, and particularly polarized-light cues, appear to be crucial for calibration of the magnetic-compass system in non-migratory bats [ 3 , 4 , 5 ]. This does not appear to ho…
Night, day, sunrise, sunset: do fish under snow and ice recognize the difference?
2008
1. Although boreal lakes are ice-covered for several months annually, little is known about the behaviour of fish under ice. To consider the reasons for diel vertical migrations (DVM) it is important to compare periods under ice as opposed to under open water. Echosounding provides a tool for non-intrusive continuous monitoring of fish, even in winter. 2. Changes in the vertical distribution of fish through six 48-h periods were monitored using a stationary, mounted echosounder that beamed vertically either from the bottom up or from the surface down from February to April, 2003. The up-beaming and down-beaming transducers were run alternately for 24 h each over the 48-h period. Standard ec…
Uncertain sunset lives: British migrants facing Brexit in Spain
2020
One of the most concerned groups potentially impacted by the approval of Brexit in 2016 is that of the so-called “Brexpats”. This group of people is composed by at least 784,900 British citizens who are living in the European Union (EU), among which those settling in Spain are the most prominent. Spanish Brexpats are the largest British population outside the borders of the UK, except for in the Commonwealth territories. They have some peculiar characteristics, such as an advanced average age compared to other EU destinations; a large number of people living off the radar; geographical concentration within coastal areas; and a certain social isolation. In this context, the succession of new…
Threshold expansion of the sunset diagram
1999
By use of the threshold expansion we develop an algorithm for analytical evaluation, within dimensional regularization, of arbitrary terms in the expansion of the (two-loop) sunset diagram with general masses m_1, m_2 and m_3 near its threshold, i.e. in any given order in the difference between the external momentum squared and its threshold value, (m_1+m_2+m_3)^2. In particular, this algorithm includes an explicit recurrence procedure to analytically calculate sunset diagrams with arbitrary integer powers of propagators at the threshold.
A walk on sunset boulevard
2016
A walk on sunset boulevard can teach us about transcendental functions associated to Feynman diagrams. On this guided tour we will see multiple polylogarithms, differential equations and elliptic curves. A highlight of the tour will be the generalisation of the polylogarithms to the elliptic setting and the all-order solution for the sunset integral in the equal mass case.
Experimental Verification of the Determination of Atmospheric Turbidity from Sunshine Recorders
1984
Abstract The feasibility of determining atmospheric turbidity from the burned traces of Campbell-Stokes sunshine recorders during cloudless sunsets and sunrises is examined experimentally. Results show that atmospheric turbidity can be determined in this way and can provide data for climatological research over the period of existing sunshine records. However, the measurements show a substantial uncertainty in the results if the properties of the used record cards are unknown. For networks of recorders, the method remains useful despite these limitations.
A dispersion relation for the pion-mass dependence of hadron properties
2010
We present a dispersion relation in the pion-mass squared, which static quantities (nucleon mass, magnetic moment, etc.) obey under the assumption of analyticity in the entire complex $m_\pi^2$ plane modulo a cut at negative $m_\pi^2$ associated with pion production. The relation is verified here in a number of examples of nucleon and $\Delta$-isobar properties computed in chiral perturbation theory up to order $p^3$. We outline a method to obtain relations for other mass-dependencies, and illustrate it on a two-loop example.
On the evaluation of sunset-type Feynman diagrams
1999
We introduce an efficient configuration space technique which allows one to compute a class of Feynman diagrams which generalize the scalar sunset topology to any number of massive internal lines. General tensor vertex structures and modifications of the propagators due to particle emission with vanishing momenta can be included with only a little change of the basic technique described for the scalar case. We discuss applications to the computation of $n$-body phase space in $D$-dimensional space-time. Substantial simplifications occur for odd space-time dimensions where the final results can be expressed in closed form through rational functions. We present explicit analytical formulas fo…
Most-Favoured-Nation Treatment, Survival Clauses and Reform of International Investment Law
2016
In the last decade, international investment law has been on a trajectory of rapid evolution with reform high on agenda priorities. Reform requires a reconciliation of competing interests, which is generally so difficult to achieve that it is often unclear whether an option constitutes ‘reform’ or unwanted change. Two specific treaty provisions, the most-favoured-nation (MFN) treatment and survival clauses, can interfere with the reform process and become an impediment to changing the rules of the game. This is particularly true when political will is present. The MFN treatment, a guarantee of non-discrimination present in the quasi-totality of investment treaties, can have far-reaching ram…