100 research outputs found

    Non-Sequential Double Ionization is a Completely Classical Photoelectric Effect

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    We introduce a unified and simplified theory of atomic double ionization. Our results show that at high laser intensities (I1014I \ge 10^{14} watts/cm2^2) purely classical correlation is strong enough to account for all of the main features observed in experiments to date

    Momentum Analysis in Strong-field Double Ionization

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    We provide a basis for the laser intensity dependence of the momentum distributions of electrons and ions arising from strong-field non-sequential double ionization (NSDI) at intensities in the range I=16.5×1014W/cm2I=1-6.5 \times 10^{14} W/cm^2. To do this we use a completely classical method introduced previously \cite{ho-etal05}. Our calculated results reproduce the features of experimental observations at different laser intensities and depend on just two distinct categories of electon trajectories.Comment: 5 pages, 7 figure

    Classical Effects of Laser Pulse Duration on Strong-field Double Ionization

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    We use classical electron ensembles and the aligned-electron approximation to examine the effect of laser pulse duration on the dynamics of strong-field double ionization. We cover the range of intensities 10141016W/cm210^{14}-10^{16} W/cm^2 for the laser wavelength 780 nm. The classical scenario suggests that the highest rate of recollision occurs early in the pulse and promotes double ionization production in few-cycle pulses. In addition, the purely classical ensemble calculation predicts an exponentially decreasing recollision rate with each subsequent half cycle. We confirm the exponential behavior by trajectory back-analysis

    Should a hysterosalpingogram be a first-line investigation to diagnose female tubal subfertility in the modern subfertility workup?

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    abstract: Tubal assessment is an integral part of female fertility evaluation. While diagnostic laparoscopy is gold standard, it is not suitable to be used as a screening test. Hysterosalpingogram (HSG) has been advocated as first-line investigation historically. With advances in diagnostics, more tests are available, such as hysterosalpingo contrast sonography (HyCoSy) and Chlamydia antibody titre (CAT) are available. The CAT test is much cheaper, less invasive and can be performed at any time during the cycle. The CAT test can also be used as a means of identifying which patients need further evaluation. HyCoSy has same diagnostic accuracy as HSG, without exposing women to radiation. We argue that HSG is out of date and has no place in a modern infertility evaluation. We also suggest a pathway (based on history, clinical and ultrasound evaluation) for investigations to screen for and diagnose tubal pathology

    X-ray induced electron and ion fragmentation dynamics in IBr

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    Characterization of the inner-shell decay processes in molecules containing heavy elements is key to understanding x-ray damage of molecules and materials and for medical applications with Auger-electron-emitting radionuclides. The 1s hole states of heavy atoms can be produced by absorption of tunable x-rays and the resulting vacancy decays characterized by recording emitted photons, electrons, and ions. The 1s hole states in heavy elements have large x-ray fluorescence yields that transfer the hole to intermediate electron shells that then decay by sequential Auger-electron transitions that increase the ion's charge state until the final state is reached. In molecules the charge is spread across the atomic sites, resulting in dissociation to energetic atomic ions. We have used x-ray/ion coincidence spectroscopy to measure charge states and energies of Iq+^{q+} and Brq+^{q'+} atomic ions following 1s ionization at the I and Br \textit{K}-edges of IBr. We present the charge states and kinetic energies of the two correlated fragment ions associated with core-excited states produced during the various steps of the cascades. To understand the dynamics leading to the ion data, we develop a computational model that combines Monte-Carlo/Molecular Dynamics simulations with a classical over-the-barrier model to track inner-shell cascades and redistribution of electrons in valence orbitals and nuclear motion of fragments

    Bilateral adrenocortical carcinoma in a patient with multiple endocrine neoplasia type 1 (MEN1) and a novel mutation in the MEN1 gene

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    The incidence of adrenal involvement in MEN1 syndrome has been reported between 9 and 45%, while the incidence of adrenocortical carcinoma (ACC) in MEN1 patients has been reported between 2.6 and 6%. In the literature data only unilateral development of ACCs in MEN1 patients has been reported. We report a 31 years-old female MEN1-patient, in whom hyperplasia of the parathyroid glands, prolactinoma, non functioning pancreatic endocrine carcinoma and functioning bilateral adrenal carcinomas were diagnosed. Interestingly, a not previously described in the literature data, novel germline mutation (p.E45V) in exon 2 of MEN1 gene, was detected. The association of exon 2 mutation of the MEN1 gene with bilateral adrenal carcinomas in MEN1 syndrome, should be further investigated

    Mutations in the SLC2A9 Gene Cause Hyperuricosuria and Hyperuricemia in the Dog

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    Allantoin is the end product of purine catabolism in all mammals except humans, great apes, and one breed of dog, the Dalmatian. Humans and Dalmatian dogs produce uric acid during purine degradation, which leads to elevated levels of uric acid in blood and urine and can result in significant diseases in both species. The defect in Dalmatians results from inefficient transport of uric acid in both the liver and renal proximal tubules. Hyperuricosuria and hyperuricemia (huu) is a simple autosomal recessive trait for which all Dalmatian dogs are homozygous. Therefore, in order to map the locus, an interbreed backcross was used. Linkage mapping localized the huu trait to CFA03, which excluded the obvious urate transporter 1 gene, SLC22A12. Positional cloning placed the locus in a minimal interval of 2.5 Mb with a LOD score of 17.45. A critical interval of 333 kb containing only four genes was homozygous in all Dalmatians. Sequence and expression analyses of the SLC2A9 gene indicated three possible mutations, a missense mutation (G616T;C188F) and two promoter mutations that together appear to reduce the expression levels of one of the isoforms. The missense mutation is associated with hyperuricosuria in the Dalmatian, while the promoter SNPs occur in other unaffected breeds of dog. Verification of the causative nature of these changes was obtained when hyperuricosuric dogs from several other breeds were found to possess the same combination of mutations as found in the Dalmatian. The Dalmatian dog model of hyperuricosuria and hyperuricemia underscores the importance of SLC2A9 for uric acid transport in mammals

    Association of Common Polymorphisms in GLUT9 Gene with Gout but Not with Coronary Artery Disease in a Large Case-Control Study

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    BACKGROUND: Serum uric acid (UA) levels have recently been shown to be genetically influenced by common polymorphisms in the GLUT9 gene in two genome-wide association analyses of Italian and British populations. Elevated serum UA levels are often found in conjunction with the metabolic syndrome. Hyperuricemia is the major risk factor for gout and has been associated with increased cardiovascular morbidity and mortality. The aim of the present study was to further elucidate the association of polymorphisms in GLUT9 with gout and coronary artery disease (CAD) or myocardial infarction (MI). To test our hypotheses, we performed two large case-control association analyses of individuals from the German MI Family Study. METHODS AND FINDINGS: First, 665 patients with gout and 665 healthy controls, which were carefully matched for age and gender, were genotyped for four single nucleotide polymorphisms (SNPs) within or near the GLUT9 gene. All four SNPs demonstrated highly significant association with gout. SNP rs6855911, located within intron 7 of GLUT9, showed the strongest signal with a protective effect of the minor allele with an allelic odds ratio of 0.62 (95% confidence interval 0.52-0.75; p = 3.2*10(-7)). Importantly, this finding was not influenced by adjustment for components of the metabolic syndrome or intake of diuretics. Secondly, 1,473 cases with severe CAD or MI and 1,241 healthy controls were tested for the same four GLUT9 SNPs. The analyses revealed, however, no significant association with CAD or with MI. Additional screening of genome-wide association data sets showed no signal for CAD or MI within the GLUT9 gene region. CONCLUSION: Thus, our results provide compelling evidence that common genetic variations within the GLUT9 gene strongly influence the risk for gout but are unlikely to have a major effect on CAD or MI in a German population
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