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Mitochondrial disease associated with complex I (NADH-CoQ oxidoreductase) deficiency.
Mitochondrial diseases due to a reduced capacity for oxidative phosphorylation were first identified more than 20Â years ago, and their incidence is now recognized to be quite significant. In a large proportion of cases the problem can be traced to a complex I (NADH-CoQ oxidoreductase) deficiency (Phenotype MIM #252010). Because the complex consists of 44 subunits, there are many potential targets for pathogenic mutations, both on the nuclear and mitochondrial genomes. Surprisingly, however, almost half of the complex I deficiencies are due to defects in as yet unidentified genes that encode proteins other than the structural proteins of the complex. This review attempts to summarize what we know about the molecular basis of complex I deficiencies: mutations in the known structural genes, and mutations in an increasing number of genes encoding "assembly factors", that is, proteins required for the biogenesis of a functional complex I that are not found in the final complex I. More such genes must be identified before definitive genetic counselling can be applied in all cases of affected families
The Equilibrium Shape of Quantum Dots
The formation of dislocation-free three-dimensional islands during the
heteroepitaxial growth of lattice-mismatched materials has been observed
experimentally for several material systems. The equilibrium shape of the
islands is governed by the competition between the surface energy and the
elastic relaxation energy of the islands as compared to the uniform strained
film. As an exemplification we consider the experimentally intensively
investigated growth of InAs quantum dots on a GaAs(001) substrate, deriving the
equilibrium shape as a function of island volume. For this purpose InAs surface
energies have been calculated within density-functional theory, and a continuum
approach has been applied to compute the elastic relaxation energies.Comment: 10 pages, 4 figures. Submitted to Nuovo Cimento (November 27, 1996)
First-principles studies of kinetics in epitaxial growth of III-V semiconductors
We demonstrate how first-principles calculations using density-functional
theory (DFT) can be applied to gain insight into the molecular processes that
rule the physics of materials processing. Specifically, we study the molecular
beam epitaxy (MBE) of arsenic compound semiconductors. For homoepitaxy of GaAs
on GaAs(001), a growth model is presented that builds on results of DFT
calculations for molecular processes on the beta2-reconstructed GaAs(001)
surface, including adsorption, desorption, surface diffusion and nucleation.
Kinetic Monte Carlo simulations on the basis of the calculated energetics
enable us to model MBE growth of GaAs from beams of Ga and As_2 in atomistic
detail. The simulations show that island nucleation is controlled by the
reaction of As_2 molecules with Ga adatoms on the surface. The analysis reveals
that the scaling laws of standard nucleation theory for the island density as a
function of growth temperature are not applicable to GaAs epitaxy. We also
discuss heteroepitaxy of InAs on GaAs(001), and report first-principles DFT
calculations for In diffusion on the strained GaAs substrate. In particular we
address the effect of heteroepitaxial strain on the growth kinetics of
coherently strained InAs islands. The strain field around an island is found to
cause a slowing-down of material transport from the substrate towards the
island and thus helps to achieve more homogeneous island sizes.Comment: 12 pages, 7 figures, REVTeX, Final version to appear in Appl. Phys. A
(2002). Other related publications can be found at
http://www.fhi-berlin.mpg.de/th/paper.htm
Effect of the cluster size in modeling the H_2 desorption and dissociative adsorption on Si(001)
Three different clusters, Si_9H_12, Si_15H_16, and Si_21H_20, are used in
density-functional theory calculations in conjunction with ab initio
pseudopotentials to study how the energetics of H_2 dissociativ e adsorption on
and associative desorption from Si(001) depends on the cluster size. The
results are compared to five-layer slab calculations using the same
pseudopotentials and high qu ality plane-wave basis set. Several
exchange-correlation functionals are employed. Our analysis suggests that the
smaller clusters generally overestimate the activation barriers and reaction
energy. The Si_21H_20 cluster, however, is found to predict reaction
energetics, with E_{a}^{des}=56 +- 3 kcal/mol (2.4 +- 0.1 eV), reasonably close
(though still different) to that obtained from the slab calculations.
Differences in the calculated activation energies are discussed in relation to
the efficiency of clusters to describe the properties of the clean Si(001)-2x1
surface.Comment: 10 pages, 6 figures, submitted to J. Chem. Phy
(The Markan and Matthean) Jesus’ appropriation and criticism of the Torah: The question of divorce
According to the Gospel of Matthew, Jesus functions as a Moses figure who, in the Sermon on the Mount, gave the new law of the kingdom of God. In this article it is argued that Jesus drew his ethic from his Jewish tradition, as manifested particularly in the Pentateuch. However, although being an inspiring source, to Jesus the Pentateuch (or scripture) was not an authority that could not be challenged or criticised. This is illustrated by focusing on the question of divorce (Mk 10:2–12; Mt 5:27–32; 19:3–12). It is argued that Jesus’ use of the Pentateuch was guided by an ethic of compassion. In view of Jesus’ stance, an uncritical use of the Bible (as manifested for example in many Christian circles) ironically contradicts the Bible’s own message and nature
Renormalized Second-order Perturbation Theory for The Electron Correlation Energy: Concept, Implementation, and Benchmarks
We present a renormalized second-order perturbation theory (rPT2), based on a
Kohn-Sham (KS) reference state, for the electron correlation energy that
includes the random-phase approximation (RPA), second-order screened exchange
(SOSEX), and renormalized single excitations (rSE). These three terms all
involve a summation of certain types of diagrams to infinite order, and can be
viewed as "renormalization" of the 2nd-order direct, exchange, and single
excitation (SE) terms of Rayleigh-Schr\"odinger perturbation theory based on an
KS reference. In this work we establish the concept of rPT2 and present the
numerical details of our SOSEX and rSE implementations. A preliminary version
of rPT2, in which the renormalized SE (rSE) contribution was treated
approximately, has already been benchmarked for molecular atomization energies
and chemical reaction barrier heights and shows a well balanced performance
[Paier et al, New J. Phys. 14, 043002 (2012)]. In this work, we present a
refined version of rPT2, in which we evaluate the rSE series of diagrams
rigorously. We then extend the benchmark studies to non-covalent interactions,
including the rare-gas dimers, and the S22 and S66 test sets. Despite some
remaining shortcomings, we conclude that rPT2 gives an overall satisfactory
performance across different chemical environments, and is a promising step
towards a generally applicable electronic structure approach.Comment: 16 pages, 11 figure
Assembling Complex I with ACAD9
Acyl-Co dehydrogenase 9 (ACAD9) was thought to play a role in fatty acid oxidation. Nouws et al. (2010) reveal a novel and essential role for this enzyme in mitochondrial complex I assembly. A mutation in ACAD9 causes an isolated complex I deficiency in a subset of patients with mitochondrial disease
Novel Reconstruction mechanisms: A comparison between group-III-nitrides and "traditional" III-V-semiconductors
We have studied the driving forces governing reconstructions on polar GaN
surfaces employing first-principles total-energy calculations. Our results
reveal properties not observed for other semiconductors, as for example a
strong tendency to stabilize Ga-rich surfaces. This mechanism is shown to have
important consequences on various surface properties: Novel and hitherto
unexpected structures are stable, surfaces may become metallic although GaN is
a wide-bandgap semiconductor, and the surface energy is significantly higher
than for other semiconductors. We explain these features in terms of the small
lattice constant of GaN and the unique bond strength of nitrogen molecules.Comment: 13 pages, 5 figure
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