Multiepoch Radial Velocity Observations of L Dwarfs

We report on the development of a technique for precise radial-velocity measurements of cool stars and brown dwarfs in the near infrared. Our technique is analogous to the Iodine (I2) absorption cell method that has proven so successful in the optical regime. We rely on telluric CH4 absorption features to serve as a wavelength reference, relative to which we measure Doppler shifts of the CO and H2O features in the spectra of our targets. We apply this technique to high-resolution (R~50,000) spectra near 2.3 micron of nine L dwarfs taken with the Phoenix instrument on Gemini-South and demonstrate a typical precision of 300 m/s. We conduct simulations to estimate our expected precision and show our performance is currently limited by the signal-to-noise of our data. We present estimates of the rotational velocities and systemic velocities of our targets. With our current data, we are sensitive to companions with M sin i > 2MJ in orbits with periods less than three days. We identify no companions in our current data set. Future observations with improved signal-to-noise should result in radial-velocity precision of 100 m/s for L dwarfs.Comment: Accepted for publication in ApJ, 24 pages, 7 figure

Relationship of morpho-sedimentological variations to the fate of Hg- and Zn-polluted sediments in the contaminated site of Porto Marghera, Lagoon of Venice, Italy.

New data collected from twenty-six sites during 2008 in the contaminated Site of National Interest (SIN) of Porto Mar- ghera within the Lagoon of Venice (Italy), which has been affected by the presence of an industrial zone for the last 80 years, were compared with data from a campaign performed in the same site 30 years before (1976-1978). The SIN was found to be heavily polluted in the earlier study, and several tons of Hg and Zn are still stored in soils and industrial channel sediments, potentially affecting the lagoon part of the SIN. Bathymetric variations, grain-size, Hg and Zn con- tent in sediments were analysed. The severe contamination of the late 1970s (Hg 1.7 µg/g; Zn 754 µg/g) had fallen by the late 2000s (Hg 0.9 µg/g; Zn 225 µg/g). The fall in Hg and Zn contamination over the 30-year period was mainly linked to the patterns of geomorphological change inside the SIN that affected two distinct sub-areas: 1) a stable-depo- sitional (SD) area in the Northern part, which exerted a “dilution” effect on contaminants, with significant deposition (~11%) of coarse-grained sediments (63 - 8 µm), and 2) an area characterised by moderate-to-severe-erosion (MSE) to the South, which saw the loss (~13%) of pollutant-bearing fine-grained sediments (<8 µm). A budget calculation in the MSE sub-area showed a loss of ~2.5 tons for Hg and ~700 tons for Zn over three decades, most of which was exported to other parts of the LV or at the open sea. A similar amount is still stored in the SD area, which will be subject to ero- sion if hydrodynamic conditions change in the future. This study provides useful support to decision-making systems by helping to select hot-spots for remediation measures

Accommodation and vergence response gains to different near cues characterize specific esotropias

Aim. To describe preliminary findings of how the profile of the use of blur, disparity and proximal cues varies between non-strabismic groups and those with different types of esotropia. Design. Case control study Methodology. A remote haploscopic photorefractor measured simultaneous convergence and accommodation to a range of targets containing all combinations of binocular disparity, blur and proximal (looming) cues. 13 constant esotropes, 16 fully accommodative esotropes, and 8 convergence excess esotropes were compared with age and refractive error matched controls, and 27 young adult emmetropic controls. All wore full refractive correction if not emmetropic. Response AC/A and CA/C ratios were also assessed. Results. Cue use differed between the groups. Even esotropes with constant suppression and no binocular vision (BV) responded to disparity in cues. The constant esotropes with weak BV showed trends for more stable responses and better vergence and accommodation than those without any BV. The accommodative esotropes made less use of disparity cues to drive accommodation (p=0.04) and more use of blur to drive vergence (p=0.008) than controls. All esotropic groups failed to show the strong bias for better responses to disparity cues found in the controls, with convergence excess esotropes favoring blur cues. AC/A and CA/C ratios existed in an inverse relationship in the different groups. Accommodative lag of >1.0D at 33cm was common (46%) in the pooled esotropia groups compared with 11% in typical children (p=0.05). Conclusion. Esotropic children use near cues differently from matched non-esotropic children in ways characteristic to their deviations. Relatively higher weighting for blur cues was found in accommodative esotropia compared to matched controls

Should wheat, barley, rye, and/or gluten be avoided in a 6-food elimination diet?

Eosinophilic esophagitis (EoE), a food antigen-mediated disease, is effectively treated with the dietary elimination of six foods commonly associated with food allergies (milk, wheat, egg, soy, tree nuts/peanuts and fish/shellfish). Because wheat shares homologous proteins (including gluten) with barley and rye and may also be processed with these grains, some clinicians have suggested barley and rye may also trigger EoE as a result of cross-reaction and/or cross-contamination with wheat. In this opinion paper, we discuss the theoretical risks of cross-reactivity and cross-contamination among wheat, barley, and rye proteins (including gluten), assess common practices at EoE treatment centers, and provide recommendations for dietary treatment and future studies of EoE

Response of the photosynthetic apparatus to a flowering-inductive period by water stress in Citrus

The photosynthetic responses to a flowering-inductive water-stress period and recovery were studied and compared in two Citrus species. Under greenhouse conditions, Fino lemon and Owari satsuma trees were subjected to moderate (-2 MPa at predawn) and severe (-3 MPa) water stress levels and were re-watered after 60 days. Vegetative growth was inhibited during the stress assays, and strong defoliation levels were reported, especially in Fino lemon. In both species, bud sprouting was induced after re-watering. Flowers and vegetative shoots developed in Owari satsuma after a drought period, and the development was independent of the stress level. In Fino lemon, vegetative shoots and flowers were primarily formed after moderate and severe stress, respectively. The photosynthetic rate and stomatal conductance were reduced by water stress, and a marked increase in water-use efficiency at the moderate water deficit level was observed. Nevertheless, the photosynthetic apparatus was not damaged, since the maximum quantum yield, photosynthetic pigment concentrations and Rubisco level and activity did not change. Furthermore, the measured malonyldialdehyde (MDA) and peroxidase activity indicated that oxidative stress was not specifically triggered by water stress in our study. Therefore, the gas exchange, fluorescence and biochemical parameters suggested that diffusional limitations to photosynthesis predominated in both of the studied Citrus species, and explained the rapid recovery of the photosynthetic parameters after rehydration. The net CO 2 fixation rate and stomatal conductance were recovered within 24 h in Fino lemon, whereas 3 days were required in Owari satsuma. This suggests the presence of some metabolic limitations in the latter species. 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Pulmonary hemodynamic responses to in utero ventilation in very immature fetal sheep

<p>Abstract</p> <p>Background</p> <p>The onset of ventilation at birth decreases pulmonary vascular resistance (PVR) resulting in a large increase in pulmonary blood flow (PBF). As the large cross sectional area of the pulmonary vascular bed develops late in gestation, we have investigated whether the ventilation-induced increase in PBF is reduced in immature lungs.</p> <p>Methods</p> <p>Surgery was performed in fetal sheep at 105 d GA (n = 7; term ~147 d) to insert an endotracheal tube, which was connected to a neonatal ventilation circuit, and a transonic flow probe was placed around the left pulmonary artery. At 110 d GA, fetuses (n = 7) were ventilated <it>in utero </it>(IUV) for 12 hrs while continuous measurements of PBF were made, fetuses were allowed to develop <it>in utero </it>for a further 7 days following ventilation.</p> <p>Results</p> <p>PBF changes were highly variable between animals, increasing from 12.2 ± 6.6 mL/min to a maximum of 78.1 ± 23.1 mL/min in four fetuses after 10 minutes of ventilation. In the remaining three fetuses, little change in PBF was measured in response to IUV. The increases in PBF measured in responding fetuses were not sustained throughout the ventilation period and by 2 hrs of IUV had returned to pre-IUV control values.</p> <p>Discussion and conclusion</p> <p>Ventilation of very immature fetal sheep <it>in utero </it>increased PBF in 57% of fetuses but this increase was not sustained for more than 2 hrs, despite continuing ventilation. Immature lungs can increase PBF during ventilation, however, the present studies show these changes are transient and highly variable.</p