778 resultados para KT-invexity


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To provide a more general method for comparing survival experience, we propose a model that independently scales both hazard and time dimensions. To test the curve shape similarity of two time-dependent hazards, h1(t) and h2(t), we apply the proposed hazard relationship, h12(tKt)/ h1(t) = Kh, to h1. This relationship doubly scales h1 by the constant hazard and time scale factors, Kh and Kt, producing a transformed hazard, h12, with the same underlying curve shape as h1. We optimize the match of h12 to h2 by adjusting Kh and Kt. The corresponding survival relationship S12(tKt) = [S1(t)]KtKh transforms S1 into a new curve S12 of the same underlying shape that can be matched to the original S2. We apply this model to the curves for regional and local breast cancer contained in the National Cancer Institute's End Results Registry (1950-1973). Scaling the original regional curves, h1 and S1 with Kt = 1.769 and Kh = 0.263 produces transformed curves h12 and S12 that display congruence with the respective local curves, h2 and S2. This similarity of curve shapes suggests the application of the more complete curve shapes for regional disease as templates to predict the long-term survival pattern for local disease. By extension, this similarity raises the possibility of scaling early data for clinical trial curves according to templates of registry or previous trial curves, projecting long-term outcomes and reducing costs. The proposed model includes as special cases the widely used proportional hazards (Kt = 1) and accelerated life (KtKh = 1) models.

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At birth, pulmonary vasodilation occurs as air-breathing life begins. The mechanism of O2-induced pulmonary vasodilation is unknown. We proposed that O2 causes fetal pulmonary vasodilation through activation of a calcium-dependent potassium channel (KCa) via a cyclic nucleotide-dependent kinase. We tested this hypothesis in hemodynamic studies in acutely prepared fetal lambs and in patch-clamp studies on resistance fetal pulmonary artery smooth muscle cells. Fetal O2 tension (PaO2) was increased by ventilating the ewe with 100% O2, causing fetal total pulmonary resistance to decrease from 1.18 +/- 0.14 to 0.41 +/- 0.03 mmHg per ml per min. Tetraethylammonium and iberiotoxin, preferential KCa-channel inhibitors, attenuated O2-induced fetal pulmonary vasodilation, while glibenclamide, an ATP-sensitive K+-channel antagonist, had no effect. Treatment with either a guanylate cyclase antagonist (LY83583) or cyclic nucleotide-dependent kinase inhibitors (H-89 and KT 5823) significantly attenuated O2-induced fetal pulmonary vasodilation. Under hypoxic conditions (PaO2 = 25 mmHg), whole-cell K+-channel currents (Ik) were small and were inhibited by 1 mM tetraethylammonium or 100 nM charybdotoxin (CTX; a specific KCa-channel blocker). Normoxia (PaO2 = 120 mmHg) increased Ik by more than 300%, and this was reversed by 100 nM CTX. Nitric oxide also increased Ik. Resting membrane potential was -37.2 +/- 1.9 mV and cells depolarized on exposure to CTX, while hyperpolarizing in normoxia. We conclude that O2 causes fetal pulmonary vasodilation by stimulating a cyclic nucleotide-dependent kinase, resulting in KCa-channel activation, membrane hyperpolarization, and vasodilation.

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We present an analysis of a series of four consecutive Chandra high-resolution transmission gratings observations, amounting to a total of 150 ks, of the Be X-ray source HD 119682 (=1WGA J1346.5–6255), a member of the new class of γ Cas analogs. The Chandra light curve shows significant brightness variations on timescales of hours. However, the spectral distribution appears rather stable within each observation and during the whole campaign. A detailed analysis is not able to detect any coherent pulsation up to a frequency of 0.05 Hz. The Chandra High Energy Transmission Gratings spectrum seems to be devoid of any strong emission line, including Fe Kα fluorescence. The continuum is well described with the addition of two collisionally ionized plasmas of temperatures kT ≈ 15 keV and 0.2 keV, respectively, by the apec model. Models using photoionized plasma components (mekal) or non-thermal components (powerlaw) give poorer fits, providing support for the pure thermal scenario. These two components are absorbed by a single column with N H = (0.20+0.15 –0.03) × 1022 cm–2 compatible with the interstellar value. We conclude that HD 119682 can be regarded as a pole-on γ Cas analog.

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We present an analysis of a pointed 141 ks Chandra high-resolution transmission gratings observation of the Be X-ray emitting star HD110432, a prominent member of the γ Cas analogs. This observation represents the first high-resolution spectrum taken for this source as well as the longest uninterrupted observation of any γ Cas analog. The Chandra light curve shows a high variability but its analysis fails to detect any coherent periodicity up to a frequency of 0.05 Hz. Hardness ratio versus intensity analyses demonstrate that the relative contributions of the [1.5-3] Å, [3-6] Å, and [6-16] Å energy bands to the total flux change rapidly in the short term. The analysis of the Chandra High Energy Transmission Grating (HETG) spectrum shows that, to correctly describe the spectrum, three model components are needed. Two of those components are optically thin thermal plasmas of different temperatures (kT ≈ 8-9 and 0.2-0.3 keV, respectively) described by the models vmekal or bvapec. The Fe abundance in each of these two components appears equal within the errors and is slightly subsolar with Z ≈ 0.75 Z ☉. The bvapec model better describes the Fe L transitions, although it cannot fit well the Na XI Lyα line at 10.02 Å, which appears to be overabundant. Two different models seem to describe well the third component. One possibility is a third hot optically thin thermal plasma at kT = 16-21 keV with an Fe abundance Z ≈ 0.3 Z ☉, definitely smaller than for the other two thermal components. Furthermore, the bvapec model describes well the Fe K shell transitions because it accounts for the turbulence broadening of the Fe XXV and Fe XXVI lines with a v turb ≈ 1200 km s–1. These two lines, contributed mainly by the hot thermal plasma, are significantly wider than the Fe Kα line whose FWHM < 5 mÅ is not resolved by Chandra. Alternatively, the third component can be described by a power law with a photon index of Γ = 1.56. In either case, the Chandra HETG spectrum establishes that each one of these components must be modified by distinct absorption columns. The analysis of a noncontemporaneous 25 ks Suzaku observation shows the presence of a hard tail extending up to at least 33 keV. The Suzaku spectrum is described with the sum of two components: an optically thin thermal plasma at kT ≈ 9 keV and Z ≈ 0.74 Z ☉, and a very hot second plasma with kT ≈ 33 keV or, alternatively, a power law with photon index of Γ = 1.58. In either case, each one of the two components must be affected by different absorption columns. Therefore, the kT = 8-9 keV component is definitely needed while the nature of the harder emission cannot be unambiguously established with the present data sets. The analysis of the Si XIII and S XV He-like triplets present in the Chandra spectrum points to a very dense (ne ~ 1013 cm–3) plasma located either close to the stellar surface (r < 3R *) of the Be star or, alternatively, very close (r ~ 1.5R WD) to the surface of a (hypothetical) white dwarf companion. We argue, however, that the available data support the first scenario.

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Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees to adverse environmental conditions. The demonstrated relationship of MR formation to ECE across this dendrochronological network in the Mediterranean basin shows the potential of MR analysis to reconstruct the history of past climatic extremes and to predict future forest dynamics in a changing climate.

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We report ground-based atmospheric measurements and emission estimates for the halons H-1211 (CBrClF₂), H-1301 (CBrF₃), and H-2402 (CBrF₂CBrF₂) from the AGAGE (Advanced Global Atmospheric Gases Experiment) and the National Oceanic and Atmospheric Administration global networks. We also include results from archived air samples in canisters and from polar firn in both hemispheres, thereby deriving an atmospheric record of nearly nine decades (1930s to present). All three halons were absent from the atmosphere until ~1970, when their atmospheric burdens started to increase rapidly. In recent years H-1211 and H-2402 mole fractions have been declining, but H-1301 has continued to grow. High-frequency observations show continuing emissions of H-1211 and H-1301 near most AGAGE sites. For H-2402 the only emissions detected were derived from the region surrounding the Sea of Japan/East Sea. Based on our observations, we derive global emissions using two different inversion approaches. Emissions for H-1211 declined from a peak of 11 kt yr⁻¹ (late 1990s) to 3.9 kt yr⁻¹ at the end of our record (mean of 2013–2015), for H-1301 from 5.4 kt yr⁻¹ (late 1980s) to 1.6 kt yr⁻¹, and for H-2402 from 1.8 kt yr⁻¹ (late 1980s) to 0.38 kt yr⁻¹. Yearly summed halon emissions have decreased substantially; nevertheless, since 2000 they have accounted for ~30% of the emissions of all major anthropogenic ozone depletion substances, when weighted by ozone depletion potentials.

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Transportation Systems Center, Cambridge, Mass.

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Mode of access: Internet.

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Molytva virnykh -- I A rmarok -- Circulus vitiosus: a. Pisni a molodosti ; b. Pisni a li u bovi ; v. Pisni a z h yti a ; h. Shkola z h yti a ; d. Shli u bna z h inka -- Sered shli a khu -- Duet -- Bodai u sni -- V antrakti -- Pered kladkoi u -- Sert s e -- Li e kt s ii pedagogii -- Pered vid'i zdom.

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T.p. also bears hijri date: 1302.

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Cf. Teerink, H. A bibliography of ... Jonathan Swift. The Hague, 1937, p. 27.

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Speeches.

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Denna studie undersöker sociala mediers påverkan på människor med fokus på mat och hälsa. Med hjälp av en kvantitativ enkätstudie har vi undersökt hur och på vilket sätt de sociala medierna spelar in i hur människor äter. Fokus ligger på vilket medie människor i åldern 18 år och uppåt väljer för att få inspiration till hälsosam mat, i vilken grad sociala medier förändrat människors medvetenhet och intresse kring hälsa och mat samt huruvida den här påverkan upplevs som positiv (inspirerande) eller negativ (stress/förvirring). Resultatet visar att de sociala medierna inte tagit över som inspirationskälla då de traditionella medierna, så som tidskrifter, TV och böcker, visade sig vara vanligast för att inspireras och skaffa sig inspiration kring mat. De sociala medierna fungerar snarare som ett komplement och har större popularitet hos den yngre generationen. Vidare visar studien att sociala medier delvis bidragit till att öka medvetenhet och intresse kring mat och hälsa. Majoriteten angav att de snarare inspireras än känner stress/förvirring till de hälsobudskap kring mat som florerar på sociala medier och studien visade ett tydligt mönster att kvinnor är både mer negativt och positivt påverkade än männen.