We have conducted a spectroscopic survey of over 1300 bright (V <= 17.5), hydrogen-rich white dwarfs based largely on the last published version of the McCook & Sion catalog. The complete results ...from our survey, including the spectroscopic analysis of over 1100 DA white dwarfs, are presented. High signal-to-noise ratio optical spectra were obtained for each star and were subsequently analyzed using our standard spectroscopic technique where the observed Balmer line profiles are compared to synthetic spectra computed from the latest generation of model atmospheres appropriate for these stars. First, we present the spectroscopic content of our sample, which includes many misclassifications as well as several DAB, DAZ, and magnetic white dwarfs. Next, we look at how the new Stark broadening profiles affect the determination of the atmospheric parameters. When necessary, specific models and analysis techniques are used to derive the most accurate atmospheric parameters possible. In particular, we employ M dwarf templates to obtain better estimates of the atmospheric parameters for those white dwarfs that are in DA+dM binary systems. Certain unique white dwarfs and double-degenerate binary systems are also analyzed in greater detail. We then examine the global properties of our sample including the mass distribution and their distribution as a function of temperature. We then proceed to test the accuracy and robustness of our method by comparing our results to those of other surveys such as SPY and Sloan Digital Sky Survey. Finally, we revisit the ZZ Ceti instability strip and examine how the determination of its empirical boundaries is affected by the latest line profile calculations.
Ruminant production systems are important contributors to anthropogenic methane (CH4) emissions, but there are large uncertainties in national and global livestock CH4 inventories. Sources of ...uncertainty in enteric CH4 emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH4 emission factors. There is also significant uncertainty associated with enteric CH4 measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF6) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH4 emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH4 emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH4 prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH4 emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH4 prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH4 emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.
We present high spatial resolution (750 au at 250 pc) maps of the B1 shock in the blue lobe of the L1157 outflow in four lines: CS (3-2), CH3OH (3K-2K), HC3N (16-15) and p-H2CO (202-301). The ...combined analysis of the morphology and spectral profiles has shown that the highest velocity gas is confined in a few compact ( 5 arcsec) bullets, while the lowest velocity gas traces the wall of the gas cavity excavated by the shock expansion. A large velocity gradient model applied to the CS (3-2) and (2-1) lines provides an upper limit of 106 cm−3 to the averaged gas density in B1 and a range of
cm−3 for the density of the high-velocity bullets. The origin of the bullets is still uncertain: they could be the result of local instabilities produced by the interaction of the jet with the ambient medium or could be clumps already present in the ambient medium that are excited and accelerated by the expanding outflows. The column densities of the observed species can be reproduced qualitatively by the presence in B1 of a C-type shock and only models where the gas reaches temperatures of at least 4000 K can reproduce the observed HC3N column density.
The air-water interface is ubiquitous in nature, as manifested in the form of the surfaces of oceans, lakes, and atmospheric aerosols. The aerosol interface, in particular, can play a crucial role in ...atmospheric chemistry. The adsorption of atmospheric species onto and into aerosols modifies their concentrations and chemistries. Moreover, the aerosol phase allows otherwise unlikely solution-phase chemistry to occur in the atmosphere. The effect of the air-water interface on these processes is not entirely known. This review summarizes recent theoretical investigations of the interactions of atmosphere species with the air-water interface, including reactant adsorption, photochemistry, and the spectroscopy of reactants at the water surface, with an emphasis on understanding differences between interfacial chemistries and the chemistries in both bulk solution and the gas phase. The results discussed here enable an understanding of fundamental concepts that lead to potential air-water interface effects, providing a framework to understand the effects of water surfaces on our atmosphere.
Aim
To evaluate in a laboratory setting the antibiofilm activity of several irrigating protocols including conventional irrigation, ultrasonic activation and XP‐endo Finisher, with a mixture of ...sodium hypochlorite and etidronic acid in infected isthmuses and root canals of extracted human mandibular molar teeth.
Methodology
Fifty‐six mesial roots of mandibular molars, half of them with a continuous isthmus from the cervical to the apical third between the two root canals (type 1), and the other half with a continuous isthmus from the cervical to the middle third and one canal in the apical third (type 2), were included. The root canals were contaminated for 7 days with an Enterococcus faecalis suspension. There were three experimental groups plus a control group (n = 7 per type of root canal anatomy). All the root canals, except for the control group that was not treated, were chemomechanically prepared and then assigned to one of the experimental groups according to the final adjunctive procedure: conventional irrigation, ultrasonic activation or XP‐endo Finisher activation. The irrigating solution used was a combination of 2.5% sodium hypochlorite and 9% etidronic acid, and the final protocols were applied for three cycles of 30 s with a 3 mL volume. The antibiofilm activity was evaluated at each location (root canal and isthmus) and third (cervical, middle and apical) using confocal laser scanning microscopy and the live/dead technique. Statistical analysis was performed using SPSS (descriptive statistics) and SUDAAN (P‐value calculations).
Results
Root canals had significantly lower biovolume values than the isthmuses (P < 0.05). The biovolume in the root canals was significantly reduced in all the experimental groups in all the thirds except for conventional irrigation in the apical third (P > 0.05). In the cervical and middle thirds, ultrasonic activation was associated with the lowest biovolumes (P < 0.05), followed by XP‐endo Finisher. In the isthmus, disinfection was similar in all the thirds for all the protocols. Conventional irrigation was associated with intermediate values with no significant differences from the control group or from the activated protocols (P > 0.05), although the latter were significantly different from the control group (P < 0.05). No differences were found between ultrasonic activation and XP‐endo Finisher in the middle and apical thirds (P > 0.05) in the isthmuses.
Conclusions
In this laboratory study on extracted teeth, the isthmus was more difficult to disinfect than root canals. In the root canals, ultrasonic activation and XP‐endo Finisher had a greater effectiveness than conventional irrigation. In the isthmuses, no differences were observed between the two activation techniques and conventional irrigation.
The interaction of ultrashort, high intensity laser pulses with thin foil targets leads to ion acceleration on the target rear surface. To make this ion source useful for applications, it is ...important to optimize the transfer of energy from the laser into the accelerated ions. One of the most promising ways to achieve this consists in engineering the target front by introducing periodic nanostructures. In this paper, the effect of these structures on ion acceleration is studied analytically and with multi-dimensional particle-in-cell simulations. We assessed the role of the structure shape, size, and the angle of laser incidence for obtaining the efficient energy transfer. Local control of electron trajectories is exploited to maximize the energy delivered into the target. Based on our numerical simulations, we propose a precise range of parameters for fabrication of nanostructured targets, which can increase the energy of the accelerated ions without requiring a higher laser intensity.
We report the discovery of eight new giant planets, and updated orbits for four known planets, orbiting dwarf and subgiant stars using the CORALIE, HARPS, and MIKE instruments as part of the ...Calan-Hertfordshire Extrasolar Planet Search. The planets have masses in the range 1.1-5.4 M sub( J)'s, orbital periods from 40 to 2900 d, and eccentricities from 0.0 to 0.6. They include a double-planet system orbiting the most massive star in our sample (HD147873), two eccentric giant planets (HD128356b and HD154672b), and a rare 14 Herculis analogue (HD224538b). We highlight some population correlations from the sample of radial velocity detected planets orbiting nearby stars, including the mass function exponential distribution, confirmation of the growing body of evidence that low-mass planets tend to be found orbiting more metal-poor stars than giant planets, and a possible period-metallicity correlation for planets with masses >0.1 M sub( J), based on a metallicity difference of 0.16 dex between the population of planets with orbital periods less than 100 d and those with orbital periods greater than 100 d.
Aim
To determine the free available chlorine of 2.5% sodium hypochlorite (NaOCl) alone and combined with 9% etidronic acid (HEDP) in the presence of inhibitors, organic tissue and organic tissue plus ...dentine debris; to evaluate the influence of dentine debris on the tissue‐dissolving capacity of both NaOCl solutions; and to determine the antimicrobial action of these solutions when in contact with organic tissue and organic tissue plus dentine debris.
Methodology
The available chlorine of the solutions over time in the absence and presence of the inhibitors was measured using a titration method. The organic tissue dissolution by the solutions alone and in the presence of dentine powder was evaluated by weighing bovine tissue specimens before and after exposure to the solutions for 3 and 10 min. For the antimicrobial activity, biofilms of Enterococcus faecalis were exposed to the solutions for 3 min in the absence and presence of organic tissue and organic tissue + dentine debris. The biovolume and percentage of damaged membrane cells of the biofilm were measured by means of confocal microscopy and the live/dead technique. Nonparametric tests were used to determine statistical differences (P < 0.05).
Results
Both inhibitors consumed the free available chlorine of the solutions over time. The presence of dentine debris significantly reduced the tissue dissolution capacity of the NaOCl solutions (P < 0.05). The percentages of biovolume reduction were not affected by the presence of the inhibitors in the two NaOCl solutions, whereas the percentage of damaged membrane cells was significantly reduced (P < 0.001). Overall, a similar behaviour was observed in the NaOCl and NaOCl/HEDP groups.
Conclusions
The presence of organic tissue and organic tissue + dentine debris favoured rapid consumption of the free chlorine of NaOCl and NaOCl/HEDP. This resulted in a decreased ability to dissolve organic tissue without affecting the short‐term antimicrobial activity.
Background. The benefit of the combination of serum galactomannan (GM) assay and polymerase chain reaction (PCR)–based detection of serum Aspergillus DNA for the early diagnosis and therapy of ...invasive aspergillosis (IA) in high-risk hematological patients remains unclear. Methods. We performed an open-label, controlled, parallel-group randomized trial in 13 Spanish centers. Adult patients with acute myeloid leukemia and myelodysplastic syndrome on induction therapy or allogeneic hematopoietic stem cell transplant recipients were randomized (1:1 ratio) to 1 of 2 arms: "GM-PCR group" (the results of serial serum GM and PCR assays were provided to treating physicians) and "GM group" (only the results of serum GM were informed). Positivity in either assay prompted thoracic computed tomography scan and initiation of antifungal therapy. No antimold prophylaxis was permitted. Results. Overall, 219 patients underwent randomization (105 in the GM-PCR group and 114 in the GM group). The cumulative incidence of "proven" or "probable" IA (primary study outcome) was lower in the GM-PCR group (4.2% vs 13.1%; odds ratio, 0.29 95% confidence interval, .09–.91). The median interval from the start of monitoring to the diagnosis of IA was lower in the GM-PCR group (13 vs 20 days; P = .022), as well as the use of empirical antifungal therapy (16.7% vs 29.0%; P = .038). Patients in the GM-PCR group had higher proven or probable IA–free survival (P = .027). Conclusions. A combined monitoring strategy based on serum GM and Aspergillus DNA was associated with an earlier diagnosis and a lower incidence of IA in high-risk hematological patients.
ABSTRACT
We present Very Large Telescope (VLT) UVES echelle spectrophotometry of the Orion nebula in the 3100–10 400 Å range. We have measured the intensity of 555 emission lines, many of them ...corresponding to permitted lines of different heavy‐element ions. This is the largest set of spectral emission lines ever obtained for a Galactic or extragalactic H ii region. We have derived He+, C2+, O+, O2+ and Ne2+ abundances from pure recombination lines. This is the first time that O+ and Ne2+ abundances have been obtained from these kinds of lines in the nebula. We have also derived abundances from collisionally excited lines for a large number of ions of different elements. In all cases, ionic abundances obtained from recombination lines are larger than those derived from collisionally excited lines. We have obtained remarkably consistent independent estimations of the temperature fluctuation parameter, t2, from different methods, which are also similar to other estimates from the literature. This result strongly suggests that moderate temperature fluctuations (t2 between 0.02 and 0.03) are present in the Orion nebula. We have compared the chemical composition of the nebula with those of the Sun and other representative objects. The heavy‐element abundances in the Orion nebula are only slightly higher than the solar ones, a difference that can be explained by the chemical evolution of the solar neighbourhood.
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