30 research outputs found

    Aplicación de las calculadoras a la meteorología aeronáutica

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    Excess-noise-enhanced parametric down conversion

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    We calculate the influence of excess noise on parametric down conversion in an unstable optical parametric oscillator (OPO), using a quantum quasimode description. We find a strongly enhanced pair photon generation rate below threshold as compared to a conventional stable cavity setup of comparable gain and loss. In addition, the oscillation threshold is lowered due to the influence of the excess noise and the squeezing properties of the emitted light are significantly changed. In general, the maximal quantum-noise suppression in one quadrature component is reduced, which poses strong limitations for the practical usefulness of a geometrically unstable OPO source. The analytical results from our quasimode description are in good agreement with numerical simulations using a positive-P representation of the field in mode space and in position space

    Physiologic and molecular consequences of endothelial Bmpr2 mutation

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    <p>Abstract</p> <p>Background</p> <p>Pulmonary arterial hypertension (PAH) is thought to be driven by dysfunction of pulmonary vascular microendothelial cells (PMVEC). Most hereditary PAH is associated with BMPR2 mutations. However, the physiologic and molecular consequences of expression of BMPR2 mutations in PMVEC are unknown.</p> <p>Methods</p> <p>In vivo experiments were performed on adult mice with conditional endothelial-specific expression of the truncation mutation Bmpr2<sup>delx4+</sup>, with age-matched transactivator-only mice as controls. Phenotype was assessed by RVSP, counts of muscularized vessels and proliferating cells, and staining for thromboses, inflammatory cells, and apoptotic cells. The effects of BMPR2 knockdown in PMVEC by siRNA on rates of apoptosis were assessed. Affymetrix expression arrays were performed on PMVEC isolated and cultured from triple transgenic mice carrying the immortomouse gene, a transactivator, and either control, Bmpr2<sup>delx4+ </sup>or Bmpr2<sup>R899X </sup>mutation.</p> <p>Results</p> <p>Transgenic mice showed increased RVSP and corresponding muscularization of small vessels, with histologic alterations including thrombosis, increased inflammatory cells, increased proliferating cells, and a moderate increase in apoptotic cells. Expression arrays showed alterations in specific pathways consistent with the histologic changes. Bmpr2<sup>delx4+ </sup>and Bmpr2<sup>R899X </sup>mutations resulted in very similar alterations in proliferation, apoptosis, metabolism, and adhesion; Bmpr2<sup>delx4+ </sup>cells showed upregulation of platelet adhesion genes and cytokines not seen in Bmpr2<sup>R899X </sup>PMVEC. Bmpr2 mutation in PMVEC does not cause a loss of differentiation markers as was seen with Bmpr2 mutation in smooth muscle cells.</p> <p>Conclusions</p> <p>Bmpr2 mutation in PMVEC <it>in vivo </it>may drive PAH through multiple, potentially independent, downstream mechanisms, including proliferation, apoptosis, inflammation, and thrombosis.</p

    Usefulness of sleep EEG as a biological marker of depression. Comparison with three neuroendocrine tests

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    peer reviewedIn a sample of 12 endogenous depressive inpatients (8 primary and 4 secondary depressives), we compared the diagnostic usefulness of REM latency (recorded during at least 4 consecutive nights) with 3 neuroendocrine tests: dexamethasone suppression test and GH response after cionidine (a α-adrenergic agonist) and apomorphine (a dopaminergic agonist) challenges. Shortened REM latency (less than 50 min during at least 1 night) was present in 67% of depressives. However, REM latency presented a clear night to night intra-patient variability that makes it necessary to record at least 3 consecutive nights for the best sensitivity. Non-suppression after dexamethasone was present in 50% of depressives, blunted GH response after clonidine, in 75% and blunted response after apomorphine, in 42%. A total of 92% of patients exhibited at least one abnormal biological parameter (100% of primary and 75% of secondary depressives); 67% of patients exhibited at least two disturbed parameters and these patients constituted the whole primary depressive group (100%). These results show that these 4 potential biological markers of depression are not necessarily distributed in the same population. This suggests the potential usefulness of their concurrent use for improved accuracy of diagnosis. © 1985 Elsevier Science Publishers, Amsterdam
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