747 research outputs found
BD-22 3467, a DAO-type star exciting the nebula Abell 35
Spectral analyses of hot, compact stars with NLTE (non-local thermodynamical
equilibrium) model-atmosphere techniques allow the precise determination of
photospheric parameters. The derived photospheric metal abundances are crucial
constraints for stellar evolutionary theory.
Previous spectral analyses of the exciting star of the nebula A 35, BD-22
3467, were based on He+C+N+O+Si+Fe models only. For our analysis, we use
state-of-the-art fully metal-line blanketed NLTE model atmospheres that
consider opacities of 23 elements from hydrogen to nickel. For the analysis of
high-resolution and high-S/N (signal-to-noise) FUV (far ultraviolet, FUSE) and
UV (HST/STIS) observations, we combined stellar-atmosphere models and
interstellar line-absorption models to fully reproduce the entire observed UV
spectrum.
The best agreement with the UV observation of BD-22 3467 is achieved at Teff
= 80 +/- 10 kK and log g =7.2 +/- 0.3. While Teff of previous analyses is
verified, log g is significantly lower. We re-analyzed lines of silicon and
iron (1/100 and about solar abundances, respectively) and for the first time in
this star identified argon, chromium, manganese, cobalt, and nickel and
determined abundances of 12, 70, 35, 150, and 5 times solar, respectively. Our
results partially agree with predictions of diffusion models for DA-type white
dwarfs. A combination of photospheric and interstellar line-absorption models
reproduces more than 90 % of the observed absorption features. The stellar mass
is M ~ 0.48 Msun.
BD-22 3467 may not have been massive enough to ascend the asymptotic giant
branch and may have evolved directly from the extended horizontal branch to the
white dwarf state. This would explain why it is not surrounded by a planetary
nebula. However, the star, ionizes the ambient interstellar matter, mimicking a
planetary nebula.Comment: 13 pages, 17 figure
Selective Deletion of the A1 Adenosine Receptor Abolishes Heart-Rate Slowing Effects of Intravascular Adenosine In Vivo
OBJECTIVE:Intravenous adenosine induces temporary bradycardia. This is due to the activation of extracellular adenosine receptors (ARs). While adenosine can signal through any of four ARs (A1AR, A2AAR, A2BAR, A3AR), previous ex vivo studies implicated the A1AR in the heart-rate slowing effects. Here, we used comparative genetic in vivo studies to address the contribution of individual ARs to the heart-rate slowing effects of intravascular adenosine. METHODS AND RESULTS:We studied gene-targeted mice for individual ARs to define their in vivo contribution to the heart-rate slowing effects of adenosine. Anesthetized mice were treated with a bolus of intravascular adenosine, followed by measurements of heart-rate and blood pressure via a carotid artery catheter. These studies demonstrated dose-dependent slowing of the heart rate with adenosine treatment in wild-type, A2AAR(-/-), A2BAR(-/-), or A3AR(-/-) mice. In contrast, adenosine-dependent slowing of the heart-rate was completely abolished in A1AR(-/-) mice. Moreover, pre-treatment with a specific A1AR antagonist (DPCPX) attenuated the heart-rate slowing effects of adenosine in wild-type, A2AAR(-/-), or A2BAR(-/-) mice, but did not alter hemodynamic responses of A1AR(-/-) mice. CONCLUSIONS:The present studies combine pharmacological and genetic in vivo evidence for a selective role of the A1AR in slowing the heart rate during adenosine bolus injection
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The Relationship between Client Social Character and Counselor Orientation as a Variable in Individual Counseling
The purpose of this study was to investigate the relationship between two counseling approaches (cognitive and affective) and two types of client social character (inner-directed and other-directed) and to measure the effect of congruence between the two from the client's frame of reference
Pressure Controlled Ventilation to Induce Acute Lung Injury in Mice
Murine models are extensively used to investigate acute injuries of different organs systems (1-34). Acute lung injury (ALI), which occurs with prolonged mechanical ventilation, contributes to morbidity and mortality of critical illness, and studies on novel genetic or pharmacological targets are areas of intense investigation (1-3, 5, 8, 26, 30, 33-36). ALI is defined by the acute onset of the disease, which leads to non-cardiac pulmonary edema and subsequent impairment of pulmonary gas exchange (36). We have developed a murine model of ALI by using a pressure-controlled ventilation to induce ventilator-induced lung injury (2). For this purpose, C57BL/6 mice are anesthetized and a tracheotomy is performed followed by induction of ALI via mechanical ventilation. Mice are ventilated in a pressure-controlled setting with an inspiratory peak pressure of 45 mbar over 1 - 3 hours. As outcome parameters, pulmonary edema (wet-to-dry ratio), bronchoalveolar fluid albumin content, bronchoalveolar fluid and pulmonary tissue myeloperoxidase content and pulmonary gas exchange are assessed (2). Using this technique we could show that it sufficiently induces acute lung inflammation and can distinguish between different treatment groups or genotypes (1-3, 5). Therefore this technique may be helpful for researchers who pursue molecular mechanisms involved in ALI using a genetic approach in mice with gene-targeted deletion
Normalisierung des T3/T4-Quotienten im Serum bei Struma-Patienten unter Kaliumjodid
Bei 16 Patienten mit blander Struma kam es bereits nach 4-wöchentlicher Behandlung mit täglich nur 200 µg Kaliumjodid zu einer Normalisierung des zuvor erhöhten T3/T4-Quotienten. Die TSH-Spiegel zeigten unter dieser Kaliumjodidbehandlung dagegen keine meßbaren Veränderungen. Die Schilddrüse besitzt demnach offensichtlich auch beim Menschen die Fähigkeit, die Synthese und Sekretion der beiden Schilddrüsenhormone T3 und T4 unabhängig vom TSH der jeweiligen Jodzufuhr anzupassen (sog. Autoregulation der jeweiligen Jodzufuhr anzupassen (sog. Autoregulation der Schilddrüse)
Myeloid Hypoxia-Inducible Factor HIF1A Provides Cardio-Protection During Ischemia and Reperfusion
The transcription factor hypoxia-inducible factor HIF1A induces cardioprotection from ischemia and reperfusion injury. Here, we investigate tissue-specific pathways that are critical for HIF1A-elicited tissue protection. Initial studies showed that mice with induced global Hif1a deletion (Hif1aloxP/loxP UbiquitinCre+) have exaggerated myocardial injury during in situ ischemia and reperfusion. Surprisingly, this phenotype was mirrored only in mice with myeloid-specific Hif1a deletion (Hif1aloxP/loxP LysM Cre+). In contrast, mice with myocardial specific (Hif1aloxP/loxP Myosin Cre+), or vascular Hif1a deletion (Hif1aloxP/loxP VEcadherin Cre+) experienced similar levels of injury as controls. Subsequent studies using adoptive transfer of Hif1a-deficient polymorphonuclear neutrophils (PMNs) prior to myocardial injury demonstrated increased reperfusion injury. On the contrary, the adoptive transfer of PMNs treated ex vivo with the hypoxia inducible factor (HIF) stabilizer dimethyloxalylglycine (DMOG) was associated with attenuated myocardial injury. Furthermore, DMOG-mediated cardioprotection was abolished in Hif1aloxP/loxP LysM Cre+ mice, but not in Hif2aloxP/loxP LysM Cre+ mice. Finally, studies of PMN-dependent HIF1A target genes implicated the neuronal guidance molecule netrin-1 in mediating the cardioprotective effects of myeloid HIF1A. Taken together, the present studies identified a functional role for myeloid-expressed HIF1A in providing cardioprotection during ischemia and reperfusion injury, which is mediated, at least in part, by the induction of the netrin-1 neuronal guidance molecule in neutrophils
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Determination of Background Uranium Concentration in the Snake River Plain Aquifer under the Idaho National Engineering and Environmental Laboratory's Radioactive Waste Management Complex
Uranium occurs naturally in the environment and is also a contaminant that is disposed of at the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering and Environmental Laboratory. To determine whether uranium concentrations in the Snake River Plain Aquifer, which underlies the laboratory, are elevated as a result of migration of anthropogenic uranium from the Subsurface Disposal Area in the RWMC, uranium background concentrations are necessary. Guideline values are calculated for total uranium, 234U, 235U, and 238U from analytical results from up to five datasets. Three of the datasets include results of samples analyzed using isotope dilution thermal ionization mass spectrometry (ID-TIMS) and two of the datasets include results obtained using alpha spectrometry. All samples included in the statistical testing were collected from aquifer monitoring wells located within 10 miles of the RWMC. Results from ID-TIMS and alpha spectrometry are combined when the data are not statistically different. Guideline values for total uranium were calculated using four of the datasets, while guideline values for 234U were calculated using only the alpha spectrometry results (2 datasets). Data from all five datasets were used to calculate 238U guideline values. No limit is calculated for 235U because the ID-TIMS results are not useful for comparison with routine monitoring data, and the alpha spectrometry results are too close to the detection limit to be deemed accurate or reliable for calculating a 235U guideline value. All guideline values presented represent the upper 95% coverage 95% confidence tolerance limits for background concentration. If a future monitoring result is above this guideline, then the exceedance will be noted in the quarterly monitoring report and assessed with respect to other aquifer information. The guidelines (tolerance limits) for total U, 234U, and 238U are 2.75 pCi/L, 1.92 pCi/L, and 0.90 pCi/L, respectively
Detrended fluctuation analysis as a statistical tool to monitor the climate
Detrended fluctuation analysis is used to investigate power law relationship
between the monthly averages of the maximum daily temperatures for different
locations in the western US. On the map created by the power law exponents, we
can distinguish different geographical regions with different power law
exponents. When the power law exponents obtained from the detrended fluctuation
analysis are plotted versus the standard deviation of the temperature
fluctuations, we observe different data points belonging to the different
climates, hence indicating that by observing the long-time trends in the
fluctuations of temperature we can distinguish between different climates.Comment: 8 pages, 4 figures, submitted to JSTA
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