To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Through appropriate choices of elements in the underlying iterated function system, the methodology of fractal interpolation enables us to associate a family of continuous self-referential functions with a prescribed real-valued continuous function on a real compact interval. This procedure elicits what is referred to as an α-fractal operator on , the space of all real-valued continuous functions defined on a compact interval I. With an eye towards connecting fractal functions with other branches of mathematics, in this paper we continue to investigate the fractal operator in more general spaces such as the space of all bounded functions and the Lebesgue space , and in some standard spaces of smooth functions such as the space of k-times continuously differentiable functions, Hölder spaces and Sobolev spaces . Using properties of the α-fractal operator, the existence of Schauder bases consisting of self-referential functions for these function spaces is established.
The σ Orionis cluster (~3 Myr, 350 pc) is an ideal site to investigate the early evolution of substellar (brown dwarf and planetary mass) objects. To date, the cluster photometric and spectroscopic sequence of free-floaters is known for a wide mass range from 1 M⊙ down to roughly 3 MJup. The substellar domain covers spectral types that go from mid-M classes to the recently defined “methane” T-types, i.e., surface temperatures between ~3000K and 800 K. We derive a rising initial substellar mass function in the mass interval of 150–5 MJup (dN/dM ~ M-α, with α = 0.9 ± 0.4). We also find evidence for a extension of this mass function toward lower masses down to 2–3 MJup. This indicates that the population of isolated planetary mass objects with masses below the deuterium burning threshold is rather abundant in the cluster.
This article explores the properties of fractal interpolation functions with variable scaling parameters, in the context of smooth fractal functions. The first part extends the Barnsley–Harrington theorem for differentiability of fractal functions and the fractal analogue of Hermite interpolation to the present setting. The general result is applied on a special class of iterated function systems in order to develop differentiability of the so-called
-fractal functions. This leads to a bounded linear map on the space
which is exploited to prove the existence of a Schauder basis for
consisting of smooth fractal functions.
PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. The atmospheric conditions at Dome C deliver a high sensitivity, high photometric precision, wide-field, high spatial resolution, and high-cadence imaging capability to the PILOT telescope. These capabilities enable a unique scientific potential for PILOT, which is addressed in this series of papers. The current paper presents a series of projects dealing with the nearby Universe that have been identified as key science drivers for the PILOT facility. Several projects are proposed that examine stellar populations in nearby galaxies and stellar clusters in order to gain insight into the formation and evolution processes of galaxies and stars. A series of projects will investigate the molecular phase of the Galaxy and explore the ecology of star formation, and investigate the formation processes of stellar and planetary systems. Three projects in the field of exoplanet science are proposed: a search for free-floating low-mass planets and dwarfs, a program of follow-up observations of gravitational microlensing events, and a study of infrared light-curves for previously discovered exoplanets. Three projects are also proposed in the field of planetary and space science: optical and near-infrared studies aimed at characterising planetary atmospheres, a study of coronal mass ejections from the Sun, and a monitoring program searching for small-scale Low Earth Orbit satellite debris items.
PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ∼30 m height), coherence time, and isoplanatic angle are all twice as good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILOT and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e. studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e. studies of Local Group galaxies, the Milky Way, and the Solar System).
We have carried out a conceptual design study for a near-infrared
(NIR) wide-field camera and a mid-infrared (MIR) camera-spectrograph
for a 2.5 m telescope at Dome C. The main scientific drivers are the
characterisation of young embedded objects, the evolution of
crystalline silicates in circumstellar disks and the observation of
exoplanet secondary transits. Both instrument exploit the unique
features of Dome C: improved infrared transmission, reduced sky
background, superb seeing, low temperature, and increased
atmospheric stability. The NIR camera covers the wavelength range
0.8–5.5 μm and is optimized for the Kdark and L
bands. The MIR instrument is sensitive in the range 7–40 μm
with a possible extension to the sub-mm. It is optimized for the
Q window, including the Q+ extended portion (25–40 μm) only
observable from the Antarctic Plateau.
The λ Orionis star formation region (1-6 Myr, 400 pc) is a complex of star-forming clouds surrounded by a molecular ring with ~ 5° radius which was probably formed by a supernova explosion (Dolan & Mathieu 2002). For a complete picture of star formation, believed to be determined by the supernova blast, the large-scale distribution of the pre-main sequence population in λ Ori needs to be examined. We have embarked on a multi-wavelength study (XMM-Newton/X-ray, CFHT/optical, Spitzer/IR) of selected areas within this intriguing star-forming complex that enables us to identify young stars and brown dwarfs. Our study comprises various areas within the cloud complex as shown in Fig.1. This data set is among the most extended X-ray surveys carried out with XMM-Newton in a coherent star-forming environment. The XMM-Newton observations combined with optical and IR data reveal the low-mass stellar population down to ~ 0.4 M⊙. For this mass-limited sample, our preliminary analysis confirms the anomalously low disk-fraction of the central star cluster Coll 69, the Eastern extension of its low-mass population pointing towards B 35, and the concentration of young stars in front of B 35. The analysis of the ‘on-cloud field' of B 35 (white in the figure) will show if the cloud is currently forming stars. This will be crucial for determining the star-forming history in the whole λ Ori region.
A cluster of five cases of tuberculosis (TB) in persons aged 19–23 years who were not close contacts was detected in a small village in Spain in 2006. All culture isolates had the same chromosomal-DNA restriction pattern. Contact investigations of family members, friends, workmates and schoolmates were complemented with tuberculin screening offered to the resident population born between 1976 and 1995. Expanded contact tracing detected two new cases of TB, 27 tuberculin conversions and an excess of latent tuberculosis infections (LTI) in persons born between 1978 and 1990. The contacts of two cases had a significantly elevated prevalence of LTI. Two secondary cases of TB, 33·3% of those diagnosed with LTI and 47·8% of the converters were unaware of any contact with the TB cases, but had frequented some of the same bars. This study suggests that a considerable percentage of the episodes of TB transmission in young people may escape detection in conventional contact studies.
Bounds for aging properties in mixtures and their
derivatives are provided. Such bounds allow control of
the behavior of those characteristics through the aging
properties of the distributions in the mixture. We also
obtain some results for discrete mixtures involving exponential
distributions. In addition, well-known mixture-preserving
properties for several distribution classes are derived
with little algebraic complexity.
Email your librarian or administrator to recommend adding this to your organisation's collection.