2,807 research outputs found
Recommended from our members
Self-selection and risk sharing in a modern world of life-long annuities
Communicating a pension product well is as important as optimising the financial value. In a recent study, we showed that up to 80% of the value of a pension lump sum could be lost if customer communication failed. In this paper, we extend the simple customer interaction of the earlier contribution to the more challenging lifetime annuity case. Using a simple mobile phone device, the pension customer can select the life-long optimal investment strategy within minutes. The financial risk trade-off is presented as a trade-off between the pension paid and the number of years the life-long annuity is guaranteed. The pension payment decreases when investment security increases. The necessary underlying mathematical financial hedging theory is included in the stud
Historic rammed earth structures in Spain : construction techniques and a preliminary classification.
Conservation and repair of historic rammed earth sites should only be undertaken if there is a good understanding of the consequences of any intervention technique. Until recently there has been little interest in the characterisation of historic rammed earth construction, yet it is only with this understanding that successful conservation strategies can be adopted.
A survey of around 60 historic rammed earth sites in Spain constructed between 967AD and 1837AD has recently been undertaken. While all the sites are built primarily in rammed earth, the construction techniques and state of repair vary greatly. The high density of historic rammed earth structures in the Iberian peninsula is likely due to the Muslim presence there from the 8th century onwards. Initial expansion, a period of civil war and eventual defeat by Christians led to the construction of a large number of fortifications, many constructed in rammed earth. A famous example is the Alhambra at Granada, but there are hundreds of smaller sites throughout Spain. By the end of the 15th century Christians had replaced Muslims through most of Spain, but rammed earth continued to be used in both vernacular and monumental architecture.
Examples of historic construction techniques are presented and common features of historic rammed earth construction are identified. A classification is outlined and a clear development of the rammed earth technique is observed
Observational properties of a kink unstable coronal loop
Aims. Previous work on the dynamics of the kink instability has concentrated on the evolution of the magnetic field and associated current sheets. Here we aim to determine the observational consequences of the kink instability in short coronal loops, particularly what images TRACE would record of such an instability. This paper concentrates on the internal m = 1 mode where the kink structure
of the instability may not be apparent from the global field shape. This is most relevant to the observation of active region brightenings and coronal bright points.
Methods. An existing fluid code was modified to include the TRACE temperature response function in order to calculate temporally and spatially averaged, line of sight images in the 171, 195 and 284 Å band passes for straight, kink unstable flux tubes.
Results. Two new fluid effects of the kink instability are discovered: the circular enhancement of the density at the foot points and the appearance of a low density band running across the flux tube. The second of these effects is shown to be imagable by TRACE and hence would be a good candidate observational signature for an internal m = 1 kink unstable loop
Recommended from our members
Self-selection and risk sharing in a modern world of lifelong annuities - Abstract of the London Discussion
This abstract relates to the following paper: Gerrard, R., Hiabu, M., Kyriakou, I. and Nielsen, J. P. (2018) Self-selection and risk sharing in a modern world of lifelong annuities ‐ Abstract of the London Discussion. British Actuarial Journal. Cambridge University Press, 23. doi: 10.1017/S135732171800020X
Reducing the number of miscreant tasks executions in a multi-use cluster.
Exploiting computational resources within an organisation
for more than their primary task offers great
benefits – making better use of capital expenditure and provides
a pool of computational power. This can be achieved through
the deployment of a cycle stealing distributed system, where
tasks execute during the idle time on computers. However,
if a task has not completed when a computer returns to its
primary function the task will be preempted, wasting time
(and energy), and is often reallocated to a new resource in
an attempt to complete. This becomes exacerbated when tasks
are incapable of completing due to excessive execution time or
faulty hardware / software, leading to a situation where tasks
are perpetually reallocated between computers – wasting time
and energy. In this work we investigate techniques to increase
the chance of ‘good’ tasks completing whilst curtailing the
execution of ‘bad’ tasks. We demonstrate, through simulation,
that we could have reduce the energy consumption of our cycle
stealing system by approximately 50%
Transverse Shifts in Paraxial Spinoptics
The paraxial approximation of a classical spinning photon is shown to yield
an "exotic particle" in the plane transverse to the propagation. The previously
proposed and observed position shift between media with different refractive
indices is modified when the interface is curved, and there also appears a
novel, momentum [direction] shift. The laws of thin lenses are modified
accordingly.Comment: 3 pages, no figures. One detail clarified, some misprints corrected
and references adde
Simulations of a lattice model of two-headed linear amphiphiles: influence of amphiphile asymmetry
Using a 2D lattice model, we conduct Monte Carlo simulations of micellar
aggregation of linear-chain amphiphiles having two solvophilic head groups. In
the context of this simple model, we quantify how the amphiphile architecture
influences the critical micelle concentration (CMC), with a particular focus on
the role of the asymmetry of the amphiphile structure. Accordingly, we study
all possible arrangements of the head groups along amphiphile chains of fixed
length and 16 molecular units. This set of idealized amphiphile
architectures approximates many cases of symmetric and asymmetric gemini
surfactants, double-headed surfactants and boloform surfactants. Consistent
with earlier results, we find that the number of spacer units separating
the heads has a significant influence on the CMC, with the CMC increasing with
for . In comparison, the influence of the asymmetry of the chain
architecture on the CMC is much weaker, as is also found experimentally.Comment: 30 pages, 17 fgure
Recommended from our members
Long-run savings and investment strategy optimization
We focus on automatic strategies to optimize life cycle savings and investment. Classical optimal savings theory establishes that, given the level of risk aversion, a saver would keep the same relative amount invested in risky assets at any given time. We show that, when optimizing lifecycle investment, performance and risk assessment have to take into account the investor's risk aversion and the maximum amount the investor could lose, simultaneously. When risk aversion and maximum possible loss are considered jointly, an optimal savings strategy is obtained, which follows from constant rather than relative absolute risk aversion. This result is fundamental to prove that if risk aversion and the maximum possible loss are both high, then holding a constant amount invested in the risky asset is optimal for a standard lifetime saving/pension process and outperforms some other simple strategies. Performance comparisons are based on downside risk-adjusted equivalence that is used in our illustration
Simulations of a lattice model of two-headed linear amphiphiles: influence of amphiphile asymmetry
Using a 2D lattice model, we conduct Monte Carlo simulations of micellar
aggregation of linear-chain amphiphiles having two solvophilic head groups. In
the context of this simple model, we quantify how the amphiphile architecture
influences the critical micelle concentration (CMC), with a particular focus on
the role of the asymmetry of the amphiphile structure. Accordingly, we study
all possible arrangements of the head groups along amphiphile chains of fixed
length and 16 molecular units. This set of idealized amphiphile
architectures approximates many cases of symmetric and asymmetric gemini
surfactants, double-headed surfactants and boloform surfactants. Consistent
with earlier results, we find that the number of spacer units separating
the heads has a significant influence on the CMC, with the CMC increasing with
for . In comparison, the influence of the asymmetry of the chain
architecture on the CMC is much weaker, as is also found experimentally.Comment: 30 pages, 17 fgure
Numerical simulations of kink instability in line-tied coronal loops
The results from numerical simulations carried out using a new shock-capturing, Lagrangian-remap, 3D MHD code, Lare3d are presented. We study the evolution of the m=1 kink mode instability in a photospherically line-tied coronal loop that has no net axial current. During the non-linear evolution of the kink instability, large current concentrations develop in the neighbourhood of the infinite length mode rational surface. We investigate whether this strong current saturates at a finite value or whether scaling indicates current sheet formation. In particular, we consider the effect of the shear, defined by where is the fieldline twist of the loop, on the current concentration. We also include a non-uniform resistivity in the simulations and observe the amount of free magnetic energy released by magnetic reconnection
- …
