The issue "Do trivalent cations conduct in crystalline solids or not?" appears in the basic research of solid-state chemistry and deals with the characteristics and properties of a multivalent cationic current transport through a solid material. Cations in an oxidation state higher than two are not unanimously accepted as mobile species. Due to the high charge density and the resulting strong Coulombic interactions with the rigid anionic host lattice, they are expected to be rather fixed within their crystallographic sites and thus not available for the current transport. Nevertheless, some compounds are already mentioned in the literature to conduct multivalent cations. But it appears that the comprehensive demonstration and the direct verification of this phenomenon is a demanding challenge which is not completed for many of these reported multivalent conductors. On the other hand, observations and experimental data are available which unambiguously identify cations in a trivalent oxidation state as mobile charge carrying species. Such a doubtless and reliable demonstration of the migrating species in an electrochemical potential gradient can be achieved, for example, by a mutual connection of dc electrolysis experiments, electromotive force, and polarization measurements. After a careful evaluation of the literature data, it turns out that the above-mentioned question concerning the possibility of mobile multivalent cationic charge carriers in solid materials must be answered in the affirmative, even in the case of trivalent cations.
Recently, neural sequence-to-sequence (Seq2Seq) models have been applied to the problem of grapheme-to-phoneme (G2P) conversion. These models offer a straightforward way of modeling the conversion by jointly learning the alignment and translation of input to output tokens in an end-to-end fashion. However, until now this approach did not show improved error rates on its own compared to traditional joint-sequence based n-gram models for G2P. In this paper, we investigate how multitask learning can improve the performance of Seq2Seq G2P models. A single Seq2Seq model is trained on multiple phoneme lexicon datasets containing multiple languages and phonetic alphabets. Although multi-language learning does not show improved error rates, combining standard datasets and crawled data with different phonetic alphabets of the same language shows promising error reductions on English and German Seq2Seq G2P conversion. Finally, combining Seq2seq G2P models with standard n-grams based models yields significant improvements over using either model alone.
Sequence labeling systems should perform reliably not only under ideal conditions but also with corrupted inputs-as these systems often process user-generated text or follow an errorprone upstream component. To this end, we formulate the noisy sequence labeling problem, where the input may undergo an unknown noising process and propose two Noise-Aware Training (NAT) objectives that improve robustness of sequence labeling performed on perturbed input: Our data augmentation method trains a neural model using a mixture of clean and noisy samples, whereas our stability training algorithm encourages the model to create a noise-invariant latent representation. We employ a vanilla noise model at training time. For evaluation, we use both the original data and its variants perturbed with real OCR errors and misspellings. Extensive experiments on English and German named entity recognition benchmarks confirmed that NAT consistently improved robustness of popular sequence labeling models, preserving accuracy on the original input. We make our code and data publicly available for the research community.
SUMMARY The effect of hypothyroidism on left ventricular function at rest and during exercise was studied in nine patients without demonstrable cardiovascular disease who had had total thyroidectomy and ablative radioiodine treatment for thyroid cancer. Radionuclide ventriculography and simultaneous right heart catheterisation were performed while the patients were hypothyroid two weeks after stopping triiodothyronine treatment (to permit routine screening for metastases) and while they were euthyroid on thyroxine replacement treatment. When the patients were hypothyroid, cardiac output, stroke volume, and end diastolic volume at rest were all lower and peripheral resistance was higher than when they were euthyroid. Pulmonary capillary wedge pressure, right atrial pressure, heart rate, left ventricular ejection fraction, and the systolic pressure:volume relation of the left ventricle, which was used as an estimate of the contractile state, were not significantly different when the patients were hypothyroid or euthyroid. During exercise, heart rate, cardiac output, end diastolic volume, and stroke volume were higher when the patients were euthyroid than when they were hypothyroid. Again, pulmonary capillary wedge pressure, ejection fraction, and the systolic pressure:volume relation were similar in both thyroid states.The data suggest that the alterations in cardiac performance seen in short term hypothyroidism are primarily related to changes in loading conditions and exercise heart rate; they do not suggest that acute thyroid hormone deficiency has a major effect on the contractile properties of the myocardium.Thyroid hormone deficiency is known to affect the heart.`13 Although exercise intolerance is a classic feature of hypothyroidism, most studies have focused on the contractile function of the heart at rest' and little attention has been paid to the performance of the left ventricle during exercise.Some radionuclide studies assessed the response of the ejection fraction to stress in hypothyroid patients.7' The ejection fraction is widely accepted as a useful measure of ventricular performance'0 but it has limitations. Because it is the ratio of two physiological variables the size of the left ventricular chamber can change considerably without causing a significant change in ejection fraction. So the Requests for reprints to Dr Siegfried Wieshammer, Cardiology Section, Department of Internal Medicine, University of Ulm, Steinhovelstraf3e 9, D-7900 Ulm, Federal Republic of Germany.Accepted for publication 9 November 1987 haemodynamic consequences of hypothyroidism are only incompletely evaluated by the response of the ejection fraction to stress, and for a more comprehensive assessment left ventricular volumes and pressures must be measured. More importantly, the ejection fraction is dependent not only on the intrinsic contractile state of the heart but also on the preload and afterload." Changes in loading conditions seem to be especially important when thyroid function is abnormal'2 and, therefore, it is u...
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