1,142 research outputs found
Van der Waals effects on grazing incidence fast atom diffraction for H/LiF(001)
We theoretically address grazing incidence fast atom diffraction (GIFAD) for
H atoms impinging on a LiF(001) surface. Our model combines a description of
the H-LiF(001) interaction obtained from Density Functional Theory calculations
with a semi-quantum treatment of the dynamics. We analyze simulated diffraction
patterns in terms of the incidence channel, the impact energy associated with
the motion normal to the surface, and the relevance of Van der Waals (VdW)
interactions. We then contrast our simulations with experimental patterns for
different incidence conditions. Our most important finding is that, for normal
energies lower than 0.5 eV and incidence along the channel, the inclusion
of Van der Waals interactions in our potential energy surface yields a greatly
improved accord between simulations and experiments. This agreement strongly
suggests a non-negligible role of Van der Waals interactions in H/LiF(001)
GIFAD in the low-to-intermediate normal energy regime
The two gap transitions in GeSn: effect of non-substitutional complex defects
The existence of non-substitutional -Sn defects in GeSn
was confirmed by emission channeling experiments [Decoster et al., Phys. Rev. B
81, 155204 (2010)], which established that although most Sn enters
substitutionally (-Sn) in the Ge lattice, a second significant fraction
corresponds to the Sn-vacancy defect complex in the split-vacancy configuration
( -Sn ), in agreement with our previous theoretical study [Ventura et
al., Phys. Rev. B 79, 155202 (2009)]. Here, we present our electronic structure
calculation for GeSn, including substitutional -Sn as
well as non-substitutional -Sn defects. To include the presence of
non-substitutional complex defects in the electronic structure calculation for
this multi-orbital alloy problem, we extended the approach for the purely
substitutional alloy by Jenkins and Dow [Jenkins and Dow, Phys. Rev. B 36, 7994
(1987)]. We employed an effective substitutional two-site cluster equivalent to
the real non-substitutional -Sn defect, which was determined by a
Green's functions calculation. We then calculated the electronic structure of
the effective alloy purely in terms of substitutional defects, embedding the
effective substitutional clusters in the lattice. Our results describe the two
transitions of the fundamental gap of GeSn as a function of the
total Sn-concentration: namely from an indirect to a direct gap, first, and the
metallization transition at higher . They also highlight the role of
-Sn in the reduction of the concentration range which corresponds to the
direct-gap phase of this alloy, of interest for optoelectronics applications.Comment: 11 pages, 9 Figure
Distal motor latency and residuallatency as sensitive markersof anti-MAG polyneuropathy
Abstract.: There is debate whether the terminal latency index (TLI) is a sensitive marker for polyneuropathy with anti-myelinassociated-glycoprotein antibodies (anti-MAGP). We examined 6 patients with an anti-MAGP and 6 patients with a chronic inflammatory demyelinating polyneuropathy (CIDP). The electroneurographic features studied were: distal compound motor action potential (CMAP), distal motor latency (DML), motor conduction velocity (MCV) elbow to wrist (distal MCV), MCV axilla to elbow (proximal MCV), MCV distal/proximal, terminal latency index (TLI), residual latency (RL), F-wave, and modified F ratio.We found significant differences between anti-MAGP and CIDP for DML and for RL.No significant differences were found for TLI and the other measures. The TLI values were not significant probably because our patients had a longer duration of disease,which supports the hypothesis of a distal to proximal progression of conduction slowing over time. We propose that a residual latency >4.0 and a distal motor latency >7.0 are strongly suggestive for an anti- MAG
Non-substitutional single-atom defects in the Ge_(1-x)Sn_x alloy
Ge_(1-x)Sn_x alloys have proved difficult to form at large x, contrary to
what happens with other group IV semiconductor combinations. However, at low x
they are typical examples of well-behaved substitutional compounds, which is
desirable for harnessing the electronic properties of narrow band
semiconductors. In this paper, we propose the appearance of another kind of
single-site defect (), consisting of a single Sn atom in the center
of a Ge divacancy, that may account for these facts. Accordingly, we examine
the electronic and structural properties of these alloys by performing
extensive numerical ab-initio calculations around local defects. The results
show that the environment of the defect relaxes towards a cubic
octahedral configuration, facilitating the nucleation of metallic white tin and
its segregation, as found in amorphous samples. Using the information stemming
from these local defect calculations, we built a simple statistical model to
investigate at which concentration these defects can be formed in
thermal equilibrium. These results agree remarkably well with experimental
findings, concerning the critical concentration above which the homogeneous
alloys cannot be formed at room temperature. Our model also predicts the
observed fact that at lower temperature the critical concentration increases.
We also performed single site effective-field calculations of the electronic
structure, which further support our hypothesis.Comment: 12 pages, 1 table, 16 figure
Peran Desentralisasi Fiskal Terhadap Kinerja Ekonomi Di Kabupaten/kota Provinsi Jawa Tengah
This research is intended to examine the influence of fiscal decentralization on economic growth, poverty, employment, and welfare at regencies/municipalities level in Central Java Province. Research population consist of 29 regencies and 6 municipalities, employing secondary data from Central Bureau of Statistic of Central Java Province and regencies/municipalities level in Central Java Province within the period of 2001 up to 2005. Data analysis is conducted by using path analysis with AMOS program software. The results of this study indicate that, first fiscal decentralization has a positive and significant effect on economic growth. Second, economic growth has a positive and significant effect on employment rate. Third, economic growth has a negative and significant effect on poverty. Forth, economic growth has a positive and significant effect on welfare. Fifth, employment rate has a negative and significant effect on welfare. Sixth, poverty has a negative and significant effect on welfare at regencies/municipalities level in Central Java Province
Transverse electrokinetic and microfluidic effects in micro-patterned channels: lubrication analysis for slab geometries
Off-diagonal (transverse) effects in micro-patterned geometries are predicted
and analyzed within the general frame of linear response theory, relating
applied presure gradient and electric field to flow and electric current. These
effects could contribute to the design of pumps, mixers or flow detectors.
Shape and charge density modulations are proposed as a means to obtain sizeable
transverse effects, as demonstrated by focusing on simple geometries and using
the lubrication approximation.Comment: 9 pages, 7 figure
Persona Obscura: A Collection of Essays on Identity and Perception
As humans, we like to think that our identities grow alongside our bodies and minds, that they are carved out gradually and imperceptibly by the slow-moving glaciers of lived experience. We regard the self as largely immutable-as a genuine, indelible, and whole entity that comes from within. But humans are social animals. Identity doesn\u27t form in a vacuum. We change selves like we change clothes-and quite often when we change clothes, hairstyles, vocabularies, intonations, and mannerisms. We assume various, sometimes conflicting personas when we interact with peers, authority figures, parents, children, mentors, lovers, and strangers. When we\u27re alone, our interior personas are ephemeral, changing with every experience we have. Even our deepest, most private identities don\u27t tell the whole story; by means of the subconscious, we obscure elements of our identities even from our own conscious minds. This collection of creative nonfiction essays explores the concept of the transient, layered self Which parts of our identities are genuine, which are manufactured, and where do they intersect? What\u27s the difference between the way we perceive ourselves and the way others perceive us? How much control do we have over how we\u27re perceived? What separates the flaws we obscure from the ones we broadcast? What happens when we\u27re forced to inhabit conflicting personas at the same time? Through the lenses of femininity, mental health, internet culture, and sex, this collection of personal narratives , cultural analyses, and graphic essays attempts to map the complex set of variables that compose human identity
Synthesis, characterization and magnetic studies of dinuclear lanthanide complexes constructed with a Schiff base ligand
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