3,269 research outputs found

    Mutations of the ret protooncogene in German multiple endocrine neoplasia families: Relation between genotype and phenotype.

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    It has been suggested that not only the position but also the nature of the mutations of the ret protooncogene strongly correlate with the clinical manifestation of the multiple endocrine neoplasm type 2 (MEN 2) syndrome. In particular, individuals with a Cys634-Arg substitution should have a greater risk of developing parathyroid disease. We, therefore, analyzed 94 unrelated families from Germany with inherited medullary thyroid carcinoma (MTC) for mutation of the ret protooncogene. In all but 1 of 59 families with MEN 2A, germline mutations in the extracellular domain of the ret protein were found. Some 81% of the MEN 2A mutations affected codon 634. Phenotype-genotype correlations suggested that the prevalence of pheochromocytoma and hyperparathyroidism is significantly higher in families with codon 634 mutations, but there was no correlation with the nature of the mutation. In all but 1 of 27 familial MTC (FMTC) families, mutations were detected in 1 of 4 cysteines in the extracellular domain of the ret protooncogene. Half of the FMTC mutations affected codon 634. Mutations outside of codon 634 occurred more often in FMTC families than in MEN 2A families. In all but 1 of 8 MEN 2B patients, de novo mutations in codon 918 were found. These data confirm the preferential localization of MEN 2-associated mutations and the correlation between disease phenotype and the position of the ret mutation, but there was no correlation between the occurrence of hyperparathyroidism or pheochromocytoma and the nature of the mutation

    NMR Imaging of the honeybee brain

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    NMR microscopy provides non-invasively distinct soft-tissue contrast in small biological samples. We were able to visualize the three-dimensional structure of the honeybee brain in its natural shape in the intact head capsule. Thus, in addition to acquiring detailed information about the shapes and volumes of the different brain compartments, we were able to show their relative orientations toward each other within the head capsule. Since the brain was lightly fixed but not dehydrated, and stayed attached to the head capsule and its internal structures, the NMR experiments exhibited larger volumes and a more natural stereo geometry of the various brain structures compared to confocal laser microscopy experiments on dissected, dehydrated and cleared brains. Abbreviation: / CLM: confocal laser microscopy NMR: nuclear magnetic resonanc

    The complexity of coverability in ν-Petri nets

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    We show that the coverability problem in ν-Petri nets is complete for ‘double Ackermann’ time, thus closing an open complexity gap between an Ackermann lower bound and a hyper-Ackermann upper bound. The coverability problem captures the verification of safety properties in this nominal extension of Petri nets with name management and fresh name creation. Our completeness result establishes ν-Petri nets as a model of intermediate power among the formalisms of nets enriched with data, and relies on new algorithmic insights brought by the use of well-quasi-order ideals

    Interpretation of Nuclear Quadrupole Resonance Spectra in Doped La2_2CuO4_4

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    The nuclear quadrupole resonance (NQR) spectrum of strontium doped La2_2CuO4_4 surprisingly resembles the NQR spectrum of La2_2CuO4_4 doped with excess oxygen, both spectra being dominated by a main peak and one principal satellite peak at similar frequencies. Using first-principles cluster calculations this is investigated here by calculating the electric field gradient (EFG) at the central copper site of the cluster after replacing a lanthanum atom in the cluster with a strontium atom or adding an interstitial oxygen to the cluster. In each case the EFG was increased by approximately 10 % leading unexpectedly to the explanation that the NQR spectra are only accidentally similar and the origins are quite different. Additionally the widths of the peaks in the NQR spectra are explained by the different EFG of copper centres remote from the impurity. A model, based on holes moving rapidly across the planar oxygen atoms, is proposed to explain the observed increase in frequency of both the main and satellite peaks in the NQR spectrum as the doping concentration is increased

    Thermodynamics of Coupled Identical Oscillators within the Path Integral Formalism

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    A generalization of symmetrized density matrices in combination with the technique of generating functions allows to calculate the partition function of identical particles in a parabolic confining well. Harmonic two-body interactions (repulsive or attractive) are taken into account. Also the influence of a homogeneous magnetic field, introducing anisotropy in the model, is examined. Although the theory is developed for fermions and bosons, special attention is payed to the thermodynamic properties of bosons and their condensation.Comment: 13 REVTEX pages + 9 postscript figure

    Early predictors of career development: A 10-year follow-up study

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    This paper presents empirical findings from a 10-year longitudinal study of the educational and occupational socialization of 445 participants who were about 7 years old when first tested, and about 17 years old at the fourth time of measurement. In addition to collecting psychological measurements from the participants, behavioral reports were collected from significant others, specifically parents and teachers. Findings demonstrated that the life/career evolution of the participants can be understood only when taking into account the dynamic interaction between the unique personal characteristics of individuality of each person and the psychosocial theatre within which the person's development takes place. Using the life-span, life-space framework of Super, and the Developmental-Contextual model from Vondracek, different emerging early predictors with unique impact on the process of educational and occupational socialization were identified, especially with respect to the probability of dropping out of school. Results in terms of gender, parental influences, psychological characteristics, and social context are discussed with regard to their potential implications for psychological interventions in schools, families, and occupational settings, as well as with regard to personal counseling in what concerns the management of life circumstances and behavioral ecosystems.http://www.sciencedirect.com/science/article/B6WMN-4K4WMXS-1/1/81776838ae5ea3c58ff98cf864f1d43

    A reduced subduction graph and higher multiplicity in S_n transformation coefficients

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    Transformation coefficients between {\it standard} bases for irreducible representations of the symmetric group SnS_n and {\it split} bases adapted to the Sn1×Sn2SnS_{n_1} \times S_{n_2} \subset S_n subgroup (n1+n2=nn_1 +n_2 = n) are considered. We first provide a \emph{selection rule} and an \emph{identity rule} for the subduction coefficients which allow to decrease the number of unknowns and equations arising from the linear method by Pan and Chen. Then, using the {\it reduced subduction graph} approach, we may look at higher multiplicity instances. As a significant example, an orthonormalized solution for the first multiplicity-three case, which occurs in the decomposition of the irreducible representation [4,3,2,1][4,3,2,1] of S10S_{10} into [3,2,1][3,1][3,2,1] \otimes [3,1] of S6×S4S_6 \times S_4, is presented and discussed.Comment: 12 pages, 1 figure, iopart class, Revisited version (several typographical errors have been corrected). Accepted for publication in J. Phys. A: Math. Ge

    Discrete model for laser driven etching and microstructuring of metallic surfaces

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    We present a unidimensional discrete solid-on-solid model evolving in time using a kinetic Monte Carlo method to simulate micro-structuring of kerfs on metallic surfaces by means of laser-induced jet-chemical etching. The precise control of the passivation layer achieved by this technique is responsible for the high resolution of the structures. However, within a certain range of experimental parameters, the microstructuring of kerfs on stainless steel surfaces with a solution of H3PO4\mathrm{H}_3\mathrm{PO}_4 shows periodic ripples, which are considered to originate from an intrinsic dynamics. The model mimics a few of the various physical and chemical processes involved and within certain parameter ranges reproduces some morphological aspects of the structures, in particular ripple regimes. We analyze the range of values of laser beam power for the appearance of ripples in both experimental and simulated kerfs. The discrete model is an extension of one that has been used previously in the context of ion sputtering and is related to a noisy version of the Kuramoto-Sivashinsky equation used extensively in the field of pattern formation.Comment: Revised version. Etching probability distribution and new simulations adde

    Versatile Atomic Magnetometry Assisted by Bayesian Inference

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    Quantum sensors typically translate external fields into a periodic response whose frequency is then determined by analyses performed in Fourier space. This allows for a linear inference of the parameters that characterize external signals. In practice, however, quantum sensors are able to detect fields only in a narrow range of amplitudes and frequencies. A departure from this range, as well as the presence of significant noise sources and short detection times, lead to a loss of the linear relationship between the response of the sensor and the target field, thus limiting the working regime of the sensor. Here we address these challenges by means of a Bayesian inference approach that is tolerant to strong deviations from desired periodic responses of the sensor and is able to provide reliable estimates even with a very limited number of measurements. We demonstrate our method for an 171^{171}Yb+^{+} trapped-ion quantum sensor but stress the general applicability of this approach to different systems.Comment: 5+14 pages, 3+9 figures. Comments are welcome

    A variational approach to strongly damped wave equations

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    We discuss a Hilbert space method that allows to prove analytical well-posedness of a class of linear strongly damped wave equations. The main technical tool is a perturbation lemma for sesquilinear forms, which seems to be new. In most common linear cases we can furthermore apply a recent result due to Crouzeix--Haase, thus extending several known results and obtaining optimal analyticity angle.Comment: This is an extended version of an article appeared in \emph{Functional Analysis and Evolution Equations -- The G\"unter Lumer Volume}, edited by H. Amann et al., Birkh\"auser, Basel, 2008. In the latest submission to arXiv only some typos have been fixe
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