Organics captured from comet 81P/Wild 2 by the Stardust spacecraft     

Sandford SA  Aléon J  Alexander CM  Araki T  Bajt S  Baratta GA  Borg J  Bradley JP  Brownlee DE  Brucato JR  Burchell MJ  Busemann H  Butterworth A  Clemett SJ  Cody G  Colangeli L  Cooper G  D'Hendecourt L  Djouadi Z  Dworkin JP  Ferrini G  Fleckenstein H  Flynn GJ  Franchi IA  Fries M  Gilles MK  Glavin DP  Gounelle M  Grossemy F  Jacobsen C  Keller LP  Kilcoyne AL  Leitner J  Matrajt G  Meibom A  Mennella V  Mostefaoui S  Nittler LR  Palumbo ME  Papanastassiou DA  Robert F  Rotundi A  Snead CJ  Spencer MK  Stadermann FJ  Steele A 《Science (New York, N.Y.)》2006,314(5806):1720-1724

Organics found in comet 81P/Wild 2 samples show a heterogeneous and unequilibrated distribution in abundance and composition. Some organics are similar, but not identical, to those in interplanetary dust particles and carbonaceous meteorites. A class of aromatic-poor organic material is also present. The organics are rich in oxygen and nitrogen compared with meteoritic organics. Aromatic compounds are present, but the samples tend to be relatively poorer in aromatics than are meteorites and interplanetary dust particles. The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage. Although the variable extent of modification of these materials by impact capture is not yet fully constrained, a diverse suite of organic compounds is present and identifiable within the returned samples.  相似文献   

Biogenic potassium salt particles as seeds for secondary organic aerosol in the Amazon     

C Pöhlker  KT Wiedemann  B Sinha  M Shiraiwa  SS Gunthe  M Smith  H Su  P Artaxo  Q Chen  Y Cheng  W Elbert  MK Gilles  AL Kilcoyne  RC Moffet  M Weigand  ST Martin  U Pöschl  MO Andreae 《Science (New York, N.Y.)》2012,337(6098):1075-1078

The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.  相似文献   

Public health. Getting HIV treatment to the most people     

S Lynch  N Ford  G van Cutsem  H Bygrave  B Janssens  T Decroo  I Andrieux-Meyer  T Roberts  S Balkan  E Casas  C Ferreyra  M Bemelmans  J Cohn  P Kahn  E Goemaere 《Science (New York, N.Y.)》2012,337(6092):298-300

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Development of a romifidine constant rate infusion with or without butorphanol for standing sedation of horses     

Ringer SK  Portier KG  Fourel I  Bettschart-Wolfensberger R 《Veterinary anaesthesia and analgesia》2012,39(1):12-20

ObjectiveTo determine constant rate infusion (CRI) protocols for romifidine (R) and romifidine combined with butorphanol (RB) resulting in constant sedation and romifidine plasma concentrations.Study designBlinded randomized crossover study.AnimalsTen adult research horses.MethodsPart I: After determining normal height of head above ground (HHAG = 100%), loading doses of romifidine (80 μg kg^?1) with butorphanol (RB: 18 μg kg^?1) or saline (R) were given intravenously (IV). Immediately afterwards, a butorphanol (RB: 25 μg kg^?1 hour^?1) or saline (R) CRI was administered for 2 hours. The HHAG was used as marker of sedation depth. Sedation was maintained for 2 hours by additional romifidine (20 μg kg^?1) whenever HHAG > 50%. The dose rate of romifidine (μg kg^?1 hour^?1) required to maintain sedation was calculated for both treatments. Part II: After loading doses, the romifidine CRIs derived from part I were administered in parallel to butorphanol (RB) or saline (R). Sedation and ataxia were evaluated periodically. Romifidine plasma concentrations were measured by HPLC-MS-MS at 0, 5, 10, 15, 30, 45, 60, 90, 105, and 120 minutes. Data were analyzed using paired t-test, Fisher's exact test, Wilcoxon signed rank test, and two-way anova for repeated measures (p < 0.05).ResultsThere was no significant difference in romifidine requirements (R: 30; RB: 29 μg kg^?1 hour^?1). CRI protocols leading to constant sedation were developed. Time to first additional romifidine bolus was significantly longer in RB (mean ± SD, R: 38.5 ± 13.6; RB: 50.5 ± 11.7 minutes). Constant plasma concentrations of romifidine were achieved during the second hour of CRI. Ataxia was greater when butorphanol was added.ConclusionRomifidine bolus, followed by CRI, provided constant sedation assessed by HHAG. Butorphanol was ineffective in reducing romifidine requirements in unstimulated horses, but prolonged the sedation caused by the initial romifidine bolus.Clinical relevanceBoth protocols need to be tested under clinical conditions.  相似文献   

Evaluation of Cut Accuracy and Cis Cortical Damage for Tibial Plateau Leveling Osteotomy Performed with and without Aid of a Novel Saw Guide: An In Vitro Study     

Neil J. Burton BVSc  Noel Fitzpatrick DUniv  MVB  Adrian M. Wallace BVSc 《Veterinary surgery : VS》2013,42(1):28-37

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Tenosynoviotomy for Sepsis of the Digital Flexor Tendon Sheath in 9 Horses     

Turlough P. Mc Nally MVB  Donnie E. Slone DVM  MS  Diplomate ACVS  Faith E. Hughes DVM  Diplomate ACVS  Timothy M. Lynch DVM  Diplomate ACVS 《Veterinary surgery : VS》2013,42(1):114-118

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Use of an ex vivo canine ventral slot model to test the efficacy of a piezoelectric cutting tool for decompressive spinal surgery     

Miguel A. Solano DVM  Noel Fitzpatrick DUniv MVB  CertSAO  CertVR  Jelena Jovanovik PGDip  BSc 《Veterinary surgery : VS》2013,42(7):832-839

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Ovarian Tumor in a Mare—Thecoma—Case Report     

Nereu Carlos Prestes  Carolina Nogueira de Moraes  Leandro Maia  Isabelle Rayanne Sousa de Oliveira  Viciany Erique Fabris  Marco Antonio Alvarenga 《Journal of Equine Veterinary Science》2013

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Perceived subject outcomes and impact on health-related quality of life associated with diet using the new Food Benefits Assessment (FBA) questionnaire: development and psychometric validation     

Guyonnet D  Chassany O  Picard C  Guillemin I  Meunier J  Seignobos E  Vigneux M  Lassel T  Trudeau E 《Public health nutrition》2008,11(11):1163-1172

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Can plantations develop understory biological and physical attributes of naturally regenerated forests?     

Isabelle Aubin  Christian Messier 《Biological conservation》2008,141(10):2461-2476

With an increasing proportion of natural forests being replaced by plantations, there is a need to determine their potential to fulfill ecological purposes other than wood production. This study evaluated the extent to which deciduous and coniferous plantations develop understory attributes comparable to those of naturally regenerated stands. A functional group approach was used to synthesise species responses in terms of their ecological traits. Multivariate analyses of ecological traits revealed 16 emergent groups that shared common traits associated with a similar life history strategy. Responses of these groups, understory structure, and understory environmental conditions to plantation types and stand stages were analyzed and compared to naturally regenerated stands. Clear associations of trait responses to stand developmental stages and plantation types emerged. Light-demanding and wind-dispersed species groups were associated with early-successional stages, while woody groups, ferns and ant-dispersed spring-flowering herbs were associated with late-successional stages. Analyses also revealed an indicator group associated with old naturally regenerated forest. The understory functional groups and environmental conditions of deciduous plantations converged toward those of old naturally regenerated forests. However, understory structure in deciduous plantations remained poorly developed and richness of the indicator group was low compared to unplanted stands. Conifer plantations, currently the most common plantation type in the northern hardwood biome, showed a completely different pathway of understory development. Modifications to current plantation management practices are proposed to help recreate or maintain natural understory biological and physical attributes.  相似文献