4,713 research outputs found
Frequentist statistics as a theory of inductive inference
After some general remarks about the interrelation between philosophical and
statistical thinking, the discussion centres largely on significance tests.
These are defined as the calculation of -values rather than as formal
procedures for ``acceptance'' and ``rejection.'' A number of types of null
hypothesis are described and a principle for evidential interpretation set out
governing the implications of -values in the specific circumstances of each
application, as contrasted with a long-run interpretation. A variety of more
complicated situations are discussed in which modification of the simple
-value may be essential.Comment: Published at http://dx.doi.org/10.1214/074921706000000400 in the IMS
Lecture Notes--Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
Designing protein β-sheet surfaces by Z-score optimization
Studies of lattice models of proteins have suggested that the appropriate energy expression for protein design may include nonthermodynamic terms to accommodate negative design concerns. One method, developed in lattice model studies, maximizes a quantity known as the "Z-score," which compares the lowest energy sequence whose ground state structure is the target structure to an ensemble of random sequences. Here we show that, in certain circumstances, the technique can be applied to real proteins. The resulting energy expression is used to design the β-sheet surfaces of two real proteins. We find experimentally that the designed proteins are stable and well folded, and in one case is even more thermostable than the wild type
Black hole polarization and new entropy bounds
Zaslavskii has suggested how to tighten Bekenstein's bound on entropy when
the object is electrically charged. Recently Hod has provided a second tighter
version of the bound applicable when the object is rotating. Here we derive
Zaslavskii's optimized bound by considering the accretion of an ordinary
charged object by a black hole. The force originating from the polarization of
the black hole by a nearby charge is central to the derivation of the bound
from the generalized second law. We also conjecture an entropy bound for
charged rotating objects, a synthesis of Zaslavskii's and Hod's. On the basis
of the no hair principle for black holes, we show that this last bound cannot
be tightened further in a generic way by knowledge of ``global'' conserved
charges, e.g., baryon number, which may be borne by the object.Comment: 21 pages, RevTex, Regularization of potential made clearer. Error in
energy of the particle corrected with no consequence for final conclusions.
New references adde
Oxidation and formation of deposit precursors in hydrocarbon fuels
The oxidation of two jet turbine fuels and some pure hydrocarbons was studied at 130 C with and without the presence of small amounts of N-methyl pyrrole (NMP) or indene. Tendency to form solid-deposit precursors was studied by measuring soluble gum formation as well as dimer and trimer formation using field ionization mass spectrometry. Pure n-dodecane oxidized fastest and gave the smallest amount of procursors. An unstable fuel oil oxidized much slower but formed large amounts of precursors. Stable Jet A fuel oxidized slowest and gave little precursors. Indene either retarded or accelerated the oxidation of n-dodecane, depending on its concentration, but always caused more gum formation. The NMP greatly retarded n-dodecane oxidation but accelerated Jet A oxidation and greatly increased the latter's gum formation. In general, the additive reacted faster and formed most of the gum. Results are interpreted in terms of classical cooxidation theory. The effect of oxygen pressure on gum formation is also reported
No Scalar Hair Theorem for a Charged Spherical Black Hole
This paper consolidates noscalar hair theorem for a charged spherically
symmetric black hole in four dimension in general relativity as well as in all
scalar tensor theories, both minimally and nonminimally coupled, when the
effective Newtonian constant of gravity is positive. However, there is an
exception when the matter field itself is coupled to the scalar field, such as
in dilaton gravity.Comment: 13 pages, Latex format, some minor corrections are made, accepted for
publication in Physical Review
Entropy bounds for charged and rotating systems
It was shown in a previous work that, for systems in which the entropy is an
extensive function of the energy and volume, the Bekenstein and the holographic
entropy bounds predict new results. In this paper, we go further and derive
improved upper bounds to the entropy of {\it extensive} charged and rotating
systems. Furthermore, it is shown that for charged and rotating systems
(including non-extensive ones), the total energy that appear in both the
Bekenstein entropy bound (BEB) and the causal entropy bound (CEB) can be
replaced by the {\it internal} energy of the system. In addition, we propose
possible corrections to the BEB and the CEB.Comment: 12 pages, revte
Nanocrystalline Zr3Al Made through Amorphization by Repeated Cold Rolling and Followed by Crystallization
The intermetallic compound Zr3Al is severely deformed by the method of
repeated cold rolling. By X-ray diffraction it is shown that this leads to
amorphization. TEM investigations reveal that a homogeneously distributed
debris of very small nanocrystals is present in the amorphous matrix that is
not resolved by X-ray diffraction. After heating to 773 K, the crystallization
of the amorphous structure leads to a fully nanocrystalline structure of small
grains (10 - 20 nm in diameter) of the non-equilibrium Zr2Al phase. It is
concluded that the debris retained in the amorphous phase acts as nuclei. After
heating to 973 K the grains grow to about 100 nm in diameter and the compound
Zr3Al starts to form, that is corresponding to the alloy composition
Lifelong learning and schools as community learning centres : key aspects of a national curriculum draft policy framework for Malta
The island of Malta has been engaged in policy document formulations for curriculum renewal in the country’s educational system (4-16 years of age) since 1988 when the first National Minimum Curriculum (henceforth NMC) was launched (Wain, 1991; Borg et al, 1995). In 1999 a revamped NMC (Ministry of Education, 1999) was developed following a long process of consultation involving various stages and stakeholders. It was a compromise document (Borg & Mayo, 2006) which emerged as a result of reactions to a more radical and coherent draft document produced in 1988.
Both curricular documents were subject to debates and critiques (Wain, 1991; Darmanin, 1993; Borg et al, 1995; Giordmaina, 2000; Borg and Mayo, 2006). More recently a series of volumes providing guidelines, key principles and aims for a national curriculum framework (henceforth NCF) have been produced (MEEF, 2011a,b,c,d) and are currently the target of debate and the focus of reactions by various stakeholders in education including teachers who were asked to read the volumes and provide reactions in the form of answers to a set questionnaire. In this paper, I will focus on one aspect of the documents, the first of its three aims: ‘Learners who are capable of successfully developing their full potential as lifelong learners.’ It is that aspect of the framework documents that falls within the purview of the title for this special issue. The use of this notion attests to the influence of the EU’s policy communications on member states, Malta having joined the Union in 2004 (Mayo, 2007).peer-reviewe
Static black hole solutions with axial symmetry
We construct a new class of asymptotically flat black hole solutions in
Einstein-Yang-Mills and Einstein-Yang-Mills-dilaton theory. These black hole
solutions are static, and they have a regular event horizon. However, they
possess only axial symmetry. Like their regular counterparts, the black hole
solutions are characterized by two integers, the winding number and the
node number of the gauge field functions.Comment: 14 pages, including 4 postscript figures, LaTe
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