381 research outputs found
New Measurements of Venus Winds with Ground-Based Doppler Velocimetry at CFHT
operations with observations from the ground using various techniques and spectral domains (Lellouch and Witasse, 2008). We present an analysis of Venus Doppler winds at cloud tops based on observations made at the Canada France Hawaii 3.6-m telescope (CFHT) with the ESPaDOnS visible spectrograph. These observations consisted of high-resolution spectra of Fraunhofer lines in the visible range (0.37-1.05 μm) to measure the winds at cloud tops using the Doppler shift of solar radiation scattered by cloud top particles in the observer's direction (Widemann et al., 2007, 2008). The observations were made during 19-20 February 2011 and were coordinated with Visual Monitoring Camera (VMC) observations by Venus Express. The complete optical spectrum was collected over 40 spectral orders at each point with 2-5 seconds exposures, at a resolution of about 80000. The observations included various points of the dayside hemisphere at a phase angle of 67°, between +10° and -60° latitude, in steps of 10° , and from +70° to -12° longitude relative to sub-Earth meridian in steps of 12°. The Doppler shift measured in scattered solar light on Venus dayside results from two instantaneous motions: (1) a motion between the Sun and Venus upper cloud particles; (2) a motion between the observer and Venus clouds. The measured Doppler shift, which results from these two terms combined, varies with the planetocentric longitude and latitude and is minimum at meridian ΦN = ΦSun - ΦEarth where the two components subtract to each other for a pure zonal regime. Due to the need for maintaining a stable velocity reference during the course of acquisition using high resolution spectroscopy, we measure relative Doppler shifts to ΦN. The main purpose of our work is to provide variable wind measurements with respect to the background atmosphere, complementary to simultaneous measurements made with the VMC camera onboard the Venus Express. We will present first results from this work, comparing with previous results by the CFHT/ESPaDOnS and VLT-UVES spectrographs (Machado et al., 2012), with Galileo fly-by measurements and with VEx nominal mission observations (Peralta et al., 2007, Luz et al., 2011). Acknowledgements: The authors acknowledge support from FCT through projects PTDC/CTE-AST/110702/2009 and PEst-OE/FIS/UI2751/2011. PM and TW also acknowledge support from the Observatoire de Paris. Lellouch, E., and Witasse, O., A coordinated campaign of Venus ground-based observations and Venus Express measurements, Planetary and Space Science 56 (2008) 1317-1319. Luz, D., et al., Venus's polar vortex reveals precessing circulation, Science 332 (2011) 577-580. Machado, P., Luz, D. Widemann, T., Lellouch, E., Witasse, O, Characterizing the atmospheric dynamics of Venus from ground-based Doppler velocimetry, Icarus, submitted. Peralta J., R. Hueso, A. Sánchez-Lavega, A reanalysis of Venus winds at two cloud levels from Galileo SSI images, Icarus 190 (2007) 469-477. Widemann, T., Lellouch, E., Donati, J.-F., 2008, Venus Doppler winds at Cloud Tops Observed with ESPaDOnS at CFHT, Planetary and Space Science, 56, 1320-1334
Retrograde Free Venous Flaps for Extremity Reconstruction: A Roadmap
Background and Objectives: Retrograde free venous flaps represent a separate entity among free venous flaps: their physiology is still unclear, but they provide an immediate visible refill after reconnection, with a similar behaviour to conventional flaps. Therefore, the dimensions and the indications of these flaps can be extended beyond what was previously believed, and they can be easily customized, including with respect to tendons and nerves. Nevertheless, they are still debated and regarded as unsafe. Materials and Methods: From 2012 to 2019, we performed 31 retrograde free venous flaps on 31 patients to reconstruct hands, digits, and in one case the heel. All the flaps were arterialized in a retrograde manner; the donor site was the forearm in 28 cases, the foot in 2 cases, and the calf in 1 case. We recorded the size, vein architecture, donor site, donor artery, donor morbidity, function for composite and non-composite flaps, immediate complications, late complications, survival rate, and the number of revisions. We recorded the hand function when appropriate. A total of 10 flaps were also intraoperatively studied with indocyanine green to monitor their hemodynamical behaviour. Results: All the patients were followed for an average of 8 months (6-15). The flap dimensions ranged from 6 cm to 136 cm. All the flaps, except two that had complete necrosis, survived. Two flaps had partial necrosis. There was no correlation between necrosis and the size of the flap, with one case of necrosis and one of partial necrosis in the small flaps (<10 cm). None of the cases with partial necrosis needed a new flap. Two flaps developed a late arterio-venous shunt that was ligated. Conclusions: The retrograde free venous flaps proved to be a useful tool for complex reconstructions of the hand and extremities. They can provide a large island of pliable skin and composite tissue with tendons and nerves, but surgeons must be aware of some caveats
DISCOVERY OF 13CCC in SgrB2(M)
Small carbon chain molecules like linear C are thought to play a crucial role in the formation of larger, complex molecules, including pre-biotic species. The formation pathways of organic molecules with carbon chains as backbones is by far not well understood. Studies of isotope fractionation have proven to be a useful tool of tracing chemical reaction pathways and to elucidate formation and destruction processes of interstellar molecules. Recent velocity-resolved observations in the far-infrared have resulted in the detection of C ro-vibrational transitions in the warm envelopes of star-forming hot cores W31C, W49N and DR21(OH). Multiple far-infrared transitions of C have also been detected towards the Galactic center molecular clouds SgrB2(M) and Sgr B2(N). Since C is involved in an important step of the formation route of the C molecule, it is likely that effects of isotopic fractionation of C will manifest itself in the C/CCC and C/CCC ratios as well._x000d_
Based on high resolution THz- laboratory measurements of C and its C-isotopologues conducted at the Kassel laboratories, we used the GREAT-receiver onboard SOFIA for a first ever detection of CCC towards SgrB2(M). In this talk we present results and possible implications of the observation. _x000d
INFRARED SPECTROSCOPY OF DISILICON-CARBIDE, Si2C
Small silicon and carbon containing molecules are thought to be important building blocks of interstellar grains. Some of them have been detected in circumstellar environments of late-type stars by means of rotational spectroscopy e.g., SiC, SiC, SiC, c-SiC, SiC, while centro-symmetric species, e.g., C, C, C, SiC, SiC, can only be detected by vibrational transitions, mainly in the infrared. _x000d_
In view of a new generation of high resolution infrared telescope instruments, e.g., EXES (Echelon-Cross-Echelle Spectrograph) onboard SOFIA (Observatory for Infrared Astronomy) and TEXES (Texas Echelon Cross Echelle Spectrograph) at the Gemini-North observatory, accurate laboratory data of small silicon-carbides in the infrared region are of high demand. In this talk we present first laboratory data of the SiC asymmetric stretching mode at 1200 cm. A pulsed Nd:YAG-laser is used to vaporize a solid target of silicon exposed to a dilute sample of methane in helium buffer gas. SiC is formed in an adiabatic expansion of a supersonic jet and radiation of a quantum cascade laser is used to record rotationally resolved spectra. To date, 160 ro-vibrational lines and have been assigned to the asymmetric stretching vibration of SiC, and derived molecular parameters are in excellent agreement with ab initio calculations. In our global fit analysis recently published microwave laboratory data (McCarthy {it et al.} 2015)footnote{McCarthy M.C., Baraban J.H., Changala P.B., Stanton J.F., Martin-Drumel M.A, Thorwirth S., et al., {it J. Chem. Phys. Lett.} {bf6}, 2107–2111 (2015).} and astronomical data (Cernicharo {it et al.} 2015)footnote{Cernicharo J., McCarthy M.C., Gottlieb C.A., Agundez M., Velilla Prieto L., Baraban J.H., et al. {it Astrophys. J. Lett.} {bf 806},L3 (2015).} were taken into account. Our new results allow for the identification of SiC by means of high resolution infrared astronomy towards the warm background of carbon-rich stars._x000d_
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GPs views on transfer of information about terminally ill patients to the out-of-hours co-operative
<p>Abstract</p> <p>Background</p> <p>In the Netherlands, the increase in of out-of-hours care that is provided by GP co-operatives is challenging the continuity of care for the terminally ill in general practice. Aim of this study is to investigate the views of general practitioners (GPs) on the transfer of information about terminally ill patients to the GP co-operatives. GPs were asked to give their view from two different perspectives: as a GP in their daily practice and as a locum in the GP co-operative.</p> <p>Methods</p> <p>Retrospective web based questionnaire sent to all 424 GPs in the Amsterdam region.</p> <p>Results</p> <p>With a response rate of 42%, 177 physicians completed the questionnaire. Transfer of information to the GP co-operative about most of their terminally ill patients was reported by 82% of the GPs and 5% did not do so for any of their patients. A faster than foreseen deterioration of the patient's situation was the most frequently reported reason for not transferring information.</p> <p>Of those who transferred information to the GP co-operative, more than 95% reported that they provided information about the diagnosis and terminally ill status of the patient. Information about medication, patient wishes regarding treatment, and prognosis was reported by respectively 90%, 87%, and 74% of the GPs. Less than 50% of the GPs reported that they transferred information about the patient's awareness of both the diagnosis and the prognosis, about the psychosocial context, and intolerances.</p> <p>In their role as locum, over 90% of the GPs wanted to receive information about the diagnosis, the terminally ill status of the patient, the medication and the patient's wishes regarding treatment.</p> <p>Conclusions</p> <p>Although most GPs reported that they transferred information about their terminally ill patients to the GP co-operative, the content of this information varies considerably. Only 21% of the GPs, working out of hours as a locum, were satisfied with the quality of the information transferred.</p
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Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape
Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare.
Consequently, long-term effects of fire on soils are often hypothesized from
short-term effects. In a chronosequence study, I studied 24 western Cascades
(Oregon) forest stands thought to have been initiated in fire. Twelve of those
burned about 150 years ago (“young” sites), and the other 12 burned an
average of 550 years ago (“old” sites). I hypothesized that young stands would
have less carbon (C) and nitrogen (N) in forest floor and in 0 -10 cm mineral
soil than old stands. I found that forest floor N pools of old sites (average =
1,823 kg/ha ± s.e. = 132 kg/ha) were significantly greater than young sites
(1,450 ± 98 kg/ha). Similarly, forest floor C pools of old sites (62,980 ± 5,403
kg/ha) were significantly greater than young sites (49,032 ± 2,965 kg/ha).
Greater N and C pools in forest floor of old sites resulted from greater forest
floor mass in old sites; concentrations of both N and C, and C:N ratios, did not
differ significantly by forest age class. In mineral soil, neither concentrations
nor pools of N and C differed between young and old sites. Despite overall
similarity of C:N ratios in young versus old sites, potential N mineralization
rates were twice as high in forest floor of old sites (average = 60 ± 7.3 mg N /
g soil) than young sites (26 ± 3.5 mg N / g soil), . Nitrate accounted for only
2% or less of total N mineralized in forest floor samples. In mineral soil,
potential net N mineralization did not differ by forest age class. The pattern of
high net N mineralization and low nitrification in old forests is consistent with
other studies of fire-prone forests, yet contrasts with many studies of forests
that lack fire, and suggests that ammonium is not the sole control over
nitrification in fire-prone ecosystems. Overall, fire appears to impart a longterm
legacy of reduced forest floor N and C pools in this western Oregon
Cascades landscape, which suggests that current fire-suppression activities in
the region may increase forest floor N and C storage over historical conditions
within several centuries. The differences in forest floor and soil N cycling
processes that I observed by forest age class raise the further possibility that
fire exclusion in these forests may change the relative abundance of soil
inorganic N forms to favor ammonium over nitrate. Such changes may have
unknown consequences for relative competitive abilities of plant and microbial
species that rely preferentially on different N-forms to meet N nutrition
requirements.
While forest floor N and C pools increase from young to old stands, forest floor
and soil N and C pools are not different, or decline, between 450 year old
stands and the oldest stands at 800+ years, That, and other, anomalous
changes in values from ~450 to 800+ years, suggest possible changes in
ecosystem functions, and may indicate that this landscape could be a fruitful
study area for examinations of a mature, steady-state ecosystemKeywords: succession, nitrification, biogeochemistry, soils, nitrogen, N mineralization, carbon, forest fire, old-growt
Time-course of balance training-related changes on static and dynamic balance performance in healthy children
Objective: In healthy children, there is evidence of improvements in static and dynamic balance performance following balance training. However, the time-course of balance training-related changes is unknown. Thus, we determined the effects of balance training after one, three, and six weeks of exercise on measures of static and dynamic balance in healthy children (N = 44, 20 females, mean age: 9.6 ± 0.5 years, age range: 9–11 years). Results: Participants in the intervention group (2 × 25 min balance exercises per week) compared to those in the control group (2 × 25 min track and field exercises and soccer practice per week) significantly improved their static (i.e., by measuring stance time in the One-Legged Stance test) and dynamic (i.e., by counting step number in the 3-m Beam Walking Backward test) balance performance. Late effects (after 6 weeks) occurred most frequently followed by mid-term effects (after 3 weeks) and then early effects (after 1 week). These findings imply that balance training is effective to improve static and dynamic measures of balance in healthy children, whereby the effectiveness increases with increasing training period. Trial registration: Current Controlled Trials ISRCTN16518737 (retrospectively registered at 24th August, 2023)
Rotational spectroscopy of rare iron monoxide isotopologues: A mass-independent analysis
We present pure rotational transitions of the rare iron monoxide isotopologues.,andin their lowest spin states. For, the rotational spectrum reveals hyperfine splitting due to the nuclear spin of. We use Dunham-like parameters to analyse the new laboratory data together with data from the literature. In particular, we are able to derive the Born-Oppenheimer breakdown parametersandand the corresponding equilibrium bond length of. With these new accurate molecular parameters line positions on a sub-MHz accuracy level can be calculated, including those of the radioactive isotopologue. The new data allow for an astronomical search for the rareisotopologues using sensitive radio telescopes, like the Atacama Large Millimetre/submillimetre Array
E-Type Delayed Fluorescence of a Phosphine-Supported Cu_2(μ-NAr_2)_2 Diamond Core: Harvesting Singlet and Triplet Excitons in OLEDs
A highly emissive bis(phosphine)diarylamido dinuclear copper(I) complex (quantum yield = 57%) was shown to exhibit E-type delayed fluorescence by variable temperature emission spectroscopy and photoluminescence decay measurement of doped vapor-deposited films. The lowest energy singlet and triplet excited states were assigned as charge transfer states on the basis of theoretical calculations and the small observed S_1−T_1 energy gap. Vapor-deposited OLEDs doped with the complex in the emissive layer gave a maximum external quantum efficiency of 16.1%, demonstrating that triplet excitons can be harvested very efficiently through the delayed fluorescence channel. The function of the emissive dopant in OLEDs was further probed by several physical methods, including electrically detected EPR, cyclic voltammetry, and photoluminescence in the presence of applied current
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