1,441 research outputs found
QC-DMRG study of the ionic--neutral curve crossing of LiF
We have studied the ionic--neutral curve crossing between the two lowest ^1
Sigma^+ states of LiF in order to demonstrate the efficiency of the quantum
chemistry version of the density matrix renormalization group method (QC-DMRG).
We show that QC-DMRG is capable to calculate the ground and several low-lying
excited state energies within the error margin set up in advance of the
calculation, while with standard quantum chemical methods it is difficult to
obtain a good approximation to Full CI property values at the point of the
avoided crossing. We have calculated the dipole moment as a function of bond
length, which in fact provides a smooth and continuous curve even close to the
avoided crossing, in contrast to other standard numerical treatments.Comment: 10 pages, 6 figure
Spin-resolved electron-impact ionization of lithium
Electron-impact ionization of lithium is studied using the convergent
close-coupling (CCC) method at 25.4 and 54.4 eV. Particular attention is paid
to the spin-dependence of the ionization cross sections. Convergence is found
to be more rapid for the spin asymmetries, which are in good agreement with
experiment, than for the underlying cross sections. Comparison with the recent
measured and DS3C-calculated data of Streun et al (1999) is most intriguing.
Excellent agreement is found with the measured and calculated spin asymmetries,
yet the discrepancy between the CCC and DS3C cross sections is very large
Post-training load-related changes of auditory working memory: An EEG study
Working memory (WM) refers to the temporary retention and manipulation of information, and its capacity is highly susceptible to training. Yet, the neural mechanisms that allow for increased performance under demanding conditions are not fully understood. We expected that post-training efficiency in WM performance modulates neural processing during high load tasks. We tested this hypothesis, using electroencephalography (EEG) (N = 39), by comparing source space spectral power of healthy adults performing low and high load auditory WM tasks. Prior to the assessment, participants either underwent a modality-specific auditory WM training, or a modality-irrelevant tactile WM training, or were not trained (active control). After a modality-specific training participants showed higher behavioral performance, compared to the control. EEG data analysis revealed general effects of WM load, across all training groups, in the theta-, alpha-, and beta-frequency bands. With increased load theta-band power increased over frontal, and decreased over parietal areas. Centro-parietal alpha-band power and central beta-band power decreased with load. Interestingly, in the high load condition a tendency toward reduced beta-band power in the right medial temporal lobe was observed in the modality-specific WM training group compared to the modality-irrelevant and active control groups. Our finding that WM processing during the high load condition changed after modality-specific WM training, showing reduced beta-band activity in voice-selective regions, possibly indicates a more efficient maintenance of task-relevant stimuli. The general load effects suggest that WM performance at high load demands involves complementary mechanisms, combining a strengthening of task-relevant and a suppression of task-irrelevant processing
SSE Spine Tango - content, workflow, set-up: www.eurospine.org - Spine Tango
The Spine Tango registry is now accessible via the SSE webpage under www.eurospine.org - Spine Tango. Links to the Swiss/International, German and Austrian modules are provided as well as information about the philosophy, methodology and content. Following the links, the users are taken to the respective national modules for registration or log-in and data entry. The Swiss/International module, also accessible under www.spinetango.com, is used by all Swiss and international users, who do not have a separate national module. The physician administered forms for surgery, staged surgery and follow-up can be downloaded as PDFs.The officially recommended Spine Tango patient forms are also available. All forms were implemented in an online version and as scannable optical mark reader forms which can be ordered from the corresponding autho
A European spine registry
Abstract.: New joint replacement registries are being widely implemented across national and international organizations. The need for a continuous long-term post-market surveillance of implants has been recognized, and has become increasingly important to ensure the quality of prosthetic components. Registry data with large case numbers represent an acceptable alternative to controlled randomized clinical trials, which are often difficult to conduct in orthopedic surgery. The variety of implants and procedures in spinal surgery not only induces the same need for long-term monitoring of post-surgical product performance as in the joint replacement subspecialties, but also renders essential the establishment of a comprehensive spine registry for all major pathologies and interventions. In cooperation with the M.E. MĂĽller Institute for Evaluative Research in Orthopedic Surgery (MEM-CED) at the University of Berne, Switzerland, the Spine Society of Europe (SSE) has launched Spine Tango: the first modular and multilevel European online registry for spinal surgery. Within Spine Tango, the major challenge in registry design and structure is the definition of and agreement upon a core set of questions as a common European dataset. Additional questions for national or individual interest can also be dynamically added to the core dataset. An automated implant tracking system has also been setup, which allows highly precise product documentation without additional work for clinical staff member
Low Temperature Magnetic Properties of the Double Exchange Model
We study the {\it ferromagnetic} (FM) Kondo lattice model in the strong
coupling limit (double exchange (DE) model). The DE mechanism proposed by Zener
to explain ferromagnetism has unexpected properties when there is more than one
itinerant electron. We find that, in general, the many-body ground state of the
DE model is {\it not} globally FM ordered (except for special filled-shell
cases). Also, the low energy excitations of this model are distinct from spin
wave excitations in usual Heisenberg ferromagnets, which will result in unusual
dynamic magnetic properties.Comment: 5 pages, RevTeX, 5 Postscript figures include
Relationship between homoeologous regulatory and structural genes in allopolyploid genome – A case study in bread wheat
<p>Abstract</p> <p>Background</p> <p>The patterns of expression of homoeologous genes in hexaploid bread wheat have been intensively studied in recent years, but the interaction between structural genes and their homoeologous regulatory genes remained unclear. The question was as to whether, in an allopolyploid, this interaction is genome-specific, or whether regulation cuts across genomes. The aim of the present study was cloning, sequence analysis, mapping and expression analysis of <it>F3H </it>(flavanone 3-hydroxylase – one of the key enzymes in the plant flavonoid biosynthesis pathway) homoeologues in bread wheat and study of the interaction between <it>F3H </it>and their regulatory genes homoeologues – <it>Rc </it>(red coleoptiles).</p> <p>Results</p> <p>PCR-based cloning of <it>F3H </it>sequences from hexaploid bread wheat (<it>Triticum aestivum </it>L.), a wild tetraploid wheat (<it>T. timopheevii</it>) and their putative diploid progenitors was employed to localize, physically map and analyse the expression of four distinct bread wheat <it>F3H </it>copies. Three of these form a homoeologous set, mapping to the chromosomes of homoeologous group 2; they are highly similar to one another at the structural and functional levels. However, the fourth copy is less homologous, and was not expressed in anthocyanin pigmented coleoptiles. The presence of dominant alleles at the <it>Rc-1 </it>homoeologous loci, which are responsible for anthocyanin pigmentation in the coleoptile, was correlated with <it>F3H </it>expression in pigmented coleoptiles. Each dominant <it>Rc-1 </it>allele affected the expression of the three <it>F3H </it>homoeologues equally, but the level of <it>F3H </it>expression was dependent on the identity of the dominant <it>Rc-1 </it>allele present. Thus, the homoeologous <it>Rc-1 </it>genes contribute more to functional divergence than do the structural <it>F3H </it>genes.</p> <p>Conclusion</p> <p>The lack of any genome-specific relationship between <it>F3H-1 </it>and <it>Rc-1 </it>implies an integrative evolutionary process among the three diploid genomes, following the formation of hexaploid wheat. Regulatory genes probably contribute more to the functional divergence between the wheat genomes than do the structural genes themselves. This is in line with the growing consensus which suggests that although heritable morphological traits are determined by the expression of structural genes, it is the regulatory genes which are the prime determinants of allelic identity.</p
Patient characteristics differently affect early cup and stem loosening in THA: a case-control study on 7,535 patients
We postulated that certain patient characteristics have different effects on early THA component loosening. With two matched case-control studies we assessed 3,028 cups and 5,224 stems. Loosening was defined using signs of mechanical component failure on routine follow-up radiographs or revision for aseptic loosening. Women and men had similar cup-loosening odds, but women had lower odds for stem loosening (p < 0.0001). Odds for cup loosening decreased by 2.1% per additional year of age (p = 0.0004), those for stem loosening by 2.4% (p < 0.0001). Each additional kilogram of weight decreased cup loosening odds by 1.3% (p = 0.0051). Each additional unit of BMI increased stem loosening odds (p = 0.0109). Charnley classes B and C were protective factors against loosening of both components. There were no risk differences for the various main diagnoses. Certain patient characteristics differently affected early cup and stem loosening, although some characteristics had the same protective or harmful effect on component surviva
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