Continental drainage in north america during the phanerozoic from Nd isotopes

Neodymium (Nd) isotopic data show consistent patterns in the sources of sedimentary rocks in North America at a continental scale. Between 600 and 450 million years ago (Ma), ancient continental shield sources dominated. Around 450 Ma, detritus from the Caledonian-Appalachian mountains overwhelmed sediment from all older sources, and is documented over large areas of the southern, western, and northern margins of North America. This material continued to dominate the sediment supply until about 150 Ma, probably due to cannibalistic recycling of sedimentary rocks formed earlier. Around 150 Ma, the rising western Cordillera delivered new and different detritus to the sedimentary system.     

Galileo Gravity Results and the Internal Structure of Io

Doppler data generated with the Galileo spacecraft's radio carrier wave were used to measure Io's external gravitational field. The resulting triaxial field is consistent with the assumption that Io is in tidal and rotational equilibrium. The inescapable conclusion is that it has a large metallic core. If the core is a eutectic mixture of iron and iron sulfide, it comprises 20.2 ± 7.4 percent of the satellite's total mass with a radius that is about 52 percent of Io's mean radius of 1821.3 kilometers; if the core is pure iron, it comprises 10.5 ± 3.7 percent of the total mass with a radius of about 36 percent of the mean radius.     

Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.     

Radar detection of the nucleus and coma of comet hyakutake

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.     

Differential metabolic response of barley genotypes,varying in resistance,to trichothecene‐producing and ‐nonproducing (tri5−) isolates of Fusarium graminearum

Resistance of barley to Fusarium graminearum was studied using a pair each of resistant and susceptible black and yellow barley lines. The spikelets were inoculated with a trichothecene‐producing isolate, a trichothecene‐nonproducing isolate (tri5^?), or a mock solution. Spikelets were collected 72 h after inoculation and metabolites were analysed using a LC‐hybrid MS system. Metabolite abundances were used to identify the constitutive (RRC) and induced resistance‐related metabolites (RRI). The pathogen virulence factor, DON, and its plant detoxification product, DON‐3‐O‐glucoside (D3G), were also identified and designated as resistance‐indicator (RI) metabolites. The RRC, RRI and RI metabolites were putatively identified. Jasmonic acid was significantly induced in barley following inoculation with a trichothecene‐producing isolate, but not with a tri5^? isolate. The former isolate reduced the induction of both the number and amount of RR metabolites. The metabolites cinnamic acid, sinapoyl alcohol, coniferin, catechin and naringin were identified only in response to the inoculation with a tri5^? mutant. The abundances of p‐coumaric acid, coniferaldehyde and sinapaldehyde increased more in response to the tri5^? mutant than to the trichothecene‐producing isolate. The total amount of DON synthesized and its conversion to D3G varied greatly between the resistant and susceptible black barley, but not in yellow barley. Interestingly, an increase in the amount of total DON produced was associated with a decrease in the conversion of DON to D3G. The roles of RRC, RRI and RI metabolites in plant defence and their further use as potential biomarkers in screening are discussed.     

Sexual Precocity of Nellore Bulls that are Offspring of Super Precocious,Precocious and Normal Cows in Extensive Farming Conditions

The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi‐square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls.     

管道涂敷施工前表面处理研究

通常情况下,管道涂敷商在涂敷新涂层之前,都要将管道表面处理到Sa 2.5级或者近白级,但是在施工现场却很难达到这一标准.讨论了旧涂层去除的常规方法、表面处理以及可预见的结果,并讨论了当前在表面处理方面的研究成果以及在涂层涂敷过程中二次生锈的各种影响.     

Fossil Evidence for a Late Cretaceous Origin of "Hoofed" Mammals

Seventeen of eighteen orders of living placental mammals are not known before 65 million years ago. The monophyly of each order is well established, but interrelations have been less certain. A superordinal grouping of up to seven extant orders plus a variety of extinct orders, all included within Ungulata ("hoofed" mammals), can be linked to Late Cretaceous mammals from the 85-million-year-old Bissekty Formation, Uzbekistan (and, less certainly, North America and Europe), thus pushing the origin of this major clade back by 20 million years. Ungulatomorphs are not closely related to primates, rodents, or rabbits.