396 research outputs found
HHSMT Observations of the Venusian Mesospheric Temperature, Winds, and CO abundance around the MESSENGER Flyby
We present submillimeter observations of 12CO J=3-2 and J=2-1, and 13CO J =
2-1 lines of the Venusian mesosphere and lower thermosphere with the Heinrich
Hertz Submillimeter Telescope (HHSMT) taken around the second MESSENGER flyby
of Venus on 5 June 2007. The observations cover a range of Venus solar
elongations with different fractional disk illuminations. Preliminary results
like temperature and CO abundance profiles are presented.These data are part of
a coordinated observational campaign in support of the ESA Venus Express
mission. Furthermore, this study attempts to contribute to cross-calibrate
space- and ground-based observations, to constrain radiative transfer and
retrieval algorithms for planetary atmospheres, and to a more thorough
understanding of the global patters of circulation of the Venusian atmosphere.Comment: 12 pages, 8 figures. Latex, uses elsart.cls (included). Higher
resolution figures in original article. Planetary and Space Science, in pres
Submillimetric spectroscopic observations of volatiles in comet C/2004 Q2 (Machholz)
We aim to determine the production rates of several parent and product
volatiles and the 12C/13C isotopic carbon ratio in the long-period comet C/2004
Q2 (Machholz), which is likely to originate from the Oort Cloud. The line
emission from several molecules in the coma was measured with high
signal-to-noise ratio in January 2005 at heliocentric distance of 1.2 AU by
means of high-resolution spectroscopic observations using the Submillimeter
Telescope (SMT). We have obtained production rates of several volatiles (CH3OH,
HCN, H13CN, HNC, H2CO, CO and CS) by comparing the observed and simulated
line-integrated intensities. Furthermore, multiline observations of the CH3OH
(7-6) series allow us to estimate the rotational temperature using the rotation
diagram technique. We find that the CH3OH population distribution of the levels
sampled by these lines can be described by a rotational temperature of 40 \pm 3
K. Derived mixing ratios relative to hydrogen cyanide are
CO/CH3OH/H2CO/CS/HNC/H13CN/HCN = 30.9/24.6/4.8/0.57/0.031/0.013/1 assuming a
pointing offset of 8" due to the uncertain ephemeris at the time of the
observations and the telescope pointing error. The measured relative molecular
abundances in C/2004 Q2 (Machholz) are between low- to typical values of those
obtained in Oort Cloud comets, suggesting that it has visited the inner solar
system previously and undergone thermal processing. The HNC/HCN abundance ratio
of ~3.1% is comparable to that found in other comets, accounting for the
dependence on the heliocentric distance, and could possibly be explained by
ion-molecule chemical processes in the low-temperature atmosphere. From a
tentative H13CN detection, the measured value of 97 \pm 30 for the H12CN/H13CN
isotopologue pair is consistent with a telluric value.Comment: 14 pages with 11 figures, abridged abstrac
A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths
The line emission in the coma was measured in the comets C/2001 Q4 (NEAT) and
C/2002 T7 (LINEAR), that were observed on five consecutive nights, 7-11 May
2004, at heliocentric distances of 1.0 and 0.7 AU, respectively, by means of
high-resolution spectroscopy using the 10-m Submillimeter Telescope (SMT). We
present a search for six parent- and product-volatile species (HCN, H2CO, CO,
CS, CH3OH, and HNC) in both comets. Multiline observations of the CH3OH J = 5-4
series allow us to estimate the rotational temperature using the rotation
diagram technique. We derive rotational temperatures of 54(9) K for C/2001 Q4
(NEAT) and 119(34) K for C/2002 T7 (LINEAR) that are roughly consistent with
observations of other comets at similar distances from the Sun. The gas
production rates of material are computed using a spherically symmetric
molecular excitation code that includes collisions between neutrals and
electrons. We find an HCN production rate of 2.96(5)e26 molec.s-1 for comet
C/2001 Q4 (NEAT), corresponding to a mixing ratio with respect to H2O of
1.12(2)e-3. The mean HCN production rate during the observing period is
4.54(10)e26 molec.s-1 for comet C/2002 T7 (LINEAR), which gives a Q_HCN/Q_H2O
mixing ratio of 1.51(3)e-3. With systematically lower mixing ratios in comet
C/2001 Q4 (NEAT), production rate ratios of the observed species with respect
to H2O lie within the typical ranges of dynamically new comets in both objects.
We find a relative low abundance of CO in C/2001 Q4 (NEAT) compared to the
observed range in other comets based on millimeter/submillimeter observations,
and a significant upper limit on the CO production in C/2002 T7 (LINEAR) is
derived. Depletion of CO suggests partial evaporation from the surface layers
during previous visits to the outer Solar System and agrees with previous
measurements of dynamically new comets.Comment: 20 pages, 18 figures. Minor changes to match the published versio
Comparison of Cellulosic Ethanol Yields from Midwestern Maize and Reconstructed Tallgrass Prairie Systems Managed for Bioenergy
Maize- and prairie-based systems were investigated as cellulosic feedstocks by conducting a 9 ha side-by-side comparison on fertile soils in the Midwestern United States. Maize was grown continuously with adequate fertilization over years both with and without a winter rye cover crop, and the 31-species reconstructed prairie was grown with and without spring nitrogen fertilization. Both maize stover and prairie biomass were harvested in the fall. We compared amounts of cellulosic biomass produced and harvested, carbohydrate contents as measured by both dietary and detergent methods, and estimated cellulosic ethanol yields per hectare. From 2009–2013, the cropping system with the largest non-grain biomass yield was fertilized prairie, averaging 10.4 Mg ha−1 year−1 aboveground biomass with average harvest removals of 7.8 Mg ha−1 year−1. The unfertilized prairie produced 7.4 Mg ha−1 year−1 aboveground biomass, with average harvests of 5.3 Mg ha−1 year−1. Lowest cellulosic (non-grain) biomass harvests were obtained from continuous maize systems, averaging 3.5 Mg ha−1 year−1 when grown with, and 3.7 Mg ha−1 year−1 when grown without a winter rye cover crop, respectively. Unfertilized prairie biomass and maize stover had equivalent dietary-determined potential biomass ethanol yields at 330 g ethanol kg−1 dry biomass, but fertilized prairie was lower at 315. The detergent method did not accurately capture these differences. Over the five-year period of the experiment, unfertilized and fertilized prairie systems averaged 810 and 1,790 L potential cellulosic ethanol ha−1 year−1 more than the maize systems, respectively. Differences in harvested biomass accounted for \u3e90 % of ethanol yield variation
Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with the Herschel space observatory
HCl and HF are expected to be the main reservoirs of fluorine and chlorine
wherever hydrogen is predominantly molecular. They are found to be strongly
depleted in dense molecular clouds, suggesting freeze-out onto grains in such
cold environments. We can then expect that HCl and HF were also the major
carriers of Cl and F in the gas and icy phases of the outer solar nebula, and
were incorporated into comets. We aimed to measure the HCl and HF abundances in
cometary ices as they can provide insights on the halogen chemistry in the
early solar nebula. We searched for the J(1-0) lines of HCl and HF at 626 and
1232 GHz, respectively, using the HIFI instrument on board the Herschel Space
Observatory. HCl was searched for in comets 103P/Hartley 2 and C/2009 P1
(Garradd), whereas observations of HF were conducted in comet C/2009 P1. In
addition, observations of HO and HO lines were performed in C/2009
P1 to measure the HO production rate. Three lines of CHOH were
serendipitously observed in the HCl receiver setting. HCl is not detected,
whereas a marginal (3.6-) detection of HF is obtained. The upper limits
for the HCl abundance relative to water are 0.011% and 0.022%, for 103P and
C/2009 P1, respectively, showing that HCl is depleted with respect to the solar
Cl/O abundance by a factor more than 6 in 103P, where the error is
related to the uncertainty in the chlorine solar abundance. The marginal HF
detection obtained in C/2009 P1 corresponds to an HF abundance relative to
water of (1.80.5) 10, which is approximately consistent
with a solar photospheric F/O abundance. The observed depletion of HCl suggests
that HCl was not the main reservoir of chlorine in the regions of the solar
nebula where these comets formed. HF was possibly the main fluorine compound in
the gas phase of the outer solar nebula.Comment: Accepted for publication in Astronomy & Astrophysic
Safety and Efficacy of Expanded Polytetrafluoroethylene Implants in the Surgical Management of Traumatic Nasal Deformity
IMPORTANCE: The ideal alloplastic implant for correction of traumatic nasal deformity has not been adequately examined.
OBJECTIVE: To evaluate the safety profile and postoperative results of expanded polytetrafluoroethylene (ePTFE) implants used in functional nasal surgery (FNS) in the setting of traumatic nasal deformity.
DESIGN, SETTING, AND PARTICIPANTS: We conducted a 13-year retrospective medical chart review for patients treated at a tertiary academic facial plastic and reconstructive surgery practice between July 1999 and July 2012. A total of 404 FNS procedures were performed by a single surgeon during this period, 255 to repair traumatic deformities, 35 of these involving ePTFE implants. Patient demographics, medical comorbidities, operative and technical considerations, functional and aesthetic results, complications, and postoperative course findings were collected from patient records. In addition, preoperative and postoperative photographic documents were examined.
EXPOSURES: Functional nasal surgery.
MAIN OUTCOMES AND MEASURES: Postoperative complications or presentations necessitating revision.
RESULTS: A total of 404 patients (197 male, 207 female) underwent FNS. Of those, 255 procedures were to treat traumatic deformities. Forty patients altogether required the use of an ePTFE implant, 35 of those 40 deformities being associated with a traumatic injury. One of the 35 patients in the ePTFE-repaired traumatic deformities group experienced postoperative infection. This patient ultimately developed exposure after the infection failed to resolve with oral antibiotics, and the implant was removed. An additional patient in the ePTFE group required revision of the implant owing to contour irregularity and aesthetic concerns. No infections or other complications occurred among the 220 patients with traumatic deformity treated with autologous grafts. Analysis of other variables including sex, tobacco use, diabetes, immunosuppression, implant thickness, suture material, and prior septorhinoplasty were not associated with increased rate of infection (P > .05 for all).
CONCLUSIONS AND RELEVANCE: In the setting of traumatic nasal deformities requiring FNS, ePTFE implants can be used at the level of the nasal dorsum, where soft tissue coverage is often adequate, with a low risk of complications
Practice Patterns in the Perioperative Treatment of Patients Undergoing Septorhinoplasty: A Survey of Facial Plastic Surgeons
IMPORTANCE The common practices used in the perioperative care of patients undergoing septorhinoplasty are diverse and controversial. A consensus statement on the preferred clinical pathway in the perioperative treatment of patients undergoing septorhinoplasty has yet to be approached formally. OBJECTIVES To investigate the perioperative treatment of patients undergoing septorhinoplasty and to identify common practice patterns based on the preferences of leading facial plastic surgeons. DESIGN, SETTING, AND PARTICIPANTS We distributed an online survey to members of the American Academy of Facial Plastic and Reconstructive Surgery. Specifically, fellowship directors and academic contact members were anonymously polled and stratified by the number of septorhinoplasties performed annually. MAIN OUTCOME AND MEASURE A cohesive clinical guide to perioperative treatment after rhinoplasty. RESULTS Of the 92 members surveyed, 67 (73%) successfully completed the survey. The distribution of respondents included 43 academicians (64%) and 24 physicians in private practice (36%). Twenty-eight surgeons (42%) performed fewer than 50 rhinoplasties a year and 39 (58%), more than 50, representing 3510 to 4549 septorhinoplasties in total among respondents. Forty-four surgeons (66%) refrained from using any packing, and 41 (61%) used intranasal splints, with polymeric silicone splints the most popular of these (n = 24 [59%]). Sixty-six surgeons (99%) used external nasal splints, including 49 (74%) who used a thermoplastic splint and 49 (74%) who left the external nasal splint in place for 7 days or longer. The most common postoperative interventions to reduce edema and ecchymosis were elevation of the head of bed by 62 (93%), ice packs by 50 (75%), and Arnica montana by 33 (49%). Only 12 surgeons (18%) used postoperative corticosteroids to reduce edema. Fifty-six respondents (84%) prohibited participation in contact sports until at least 6 weeks after surgery. CONCLUSIONS AND RELEVANCE Perioperative care and practices after nasal surgery vary among the most highly trained and leading rhinoplasty surgeons. No published communication or consensus on perioperative practices has been disseminated in this setting. Given the results from those surgeons performing the most rhinoplasties in our field, some surgeons may choose to vary their practices to coincide with those of experienced surgeons. These guidelines could facilitate future studies of patient outcomes
An upper limit for the water outgassing rate of the main-belt comet 176P/LINEAR observed with Herschel/HIFI
176P/LINEAR is a member of the new cometary class known as main-belt comets
(MBCs). It displayed cometary activity shortly during its 2005 perihelion
passage that may be driven by the sublimation of sub-surface ices. We have
therefore searched for emission of the H2O 110-101 ground state rotational line
at 557 GHz toward 176P/LINEAR with the Heterodyne Instrument for the Far
Infrared (HIFI) on board the Herschel Space Observatory on UT 8.78 August 2011,
about 40 days after its most recent perihelion passage, when the object was at
a heliocentric distance of 2.58 AU. No H2O line emission was detected in our
observations, from which we derive sensitive 3-sigma upper limits for the water
production rate and column density of < 4e25 molec/s and of < 3e10 cm^{-2},
respectively. From the peak brightness measured during the object's active
period in 2005, this upper limit is lower than predicted by the relation
between production rates and visual magnitudes observed for a sample of comets
by Jorda et al. (2008) at this heliocentric distance. Thus, 176P/LINEAR was
likely less active at the time of our observation than during its previous
perihelion passage. The retrieved upper limit is lower than most values derived
for the H2O production rate from the spectroscopic search for CN emission in
MBCs.Comment: 5 pages, 2 figures. Minor changes to match published versio
Cotauberian Operators on L1(0, 1) Obtained by Lifting
ABSTRACT:We show that the set Td(L1(0, 1)) of cotauberian operators acting on L1(0, 1) is not open, and T ? Td(L1(0, 1)) does not imply T** cotauberian. As a consequence, we derive that the set T(L8(0, 1)) of tauberian operators acting on L8(0, 1) is not open, and that T ? T(L8(0,1)) does not imply T** tauberian
HIFI observations of warm gas in DR21: Shock versus radiative heating
The molecular gas in the DR21 massive star formation region is known to be
affected by the strong UV field from the central star cluster and by a fast
outflow creating a bright shock. The relative contribution of both heating
mechanisms is the matter of a long debate. By better sampling the excitation
ladder of various tracers we provide a quantitative distinction between the
different heating mechanisms. HIFI observations of mid-J transitions of CO and
HCO+ isotopes allow us to bridge the gap in excitation energies between
observations from the ground, characterizing the cooler gas, and existing ISO
LWS spectra, constraining the properties of the hot gas. Comparing the detailed
line profiles allows to identify the physical structure of the different
components. In spite of the known shock-excitation of H2 and the clearly
visible strong outflow, we find that the emission of all lines up to > 2 THz
can be explained by purely radiative heating of the material. However, the new
Herschel/HIFI observations reveal two types of excitation conditions. We find
hot and dense clumps close to the central cluster, probably dynamically
affected by the outflow, and a more widespread distribution of cooler, but
nevertheless dense, molecular clumps.Comment: Accepted for publication by A&
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