142Nd evidence for early (>4.53 Ga) global differentiation of the silicate Earth

New high-precision samarium-neodymium isotopic data for chondritic meteorites show that their 142Nd/144Nd ratio is 20 parts per million lower than that of most terrestrial rocks. This difference indicates that most (70 to 95%) of Earth's mantle is compositionally similar to the incompatible element-depleted source of mid-ocean ridge basalts, possibly as a result of a global differentiation 4.53 billion years ago (Ga), within 30 million years of Earth's formation. The complementary enriched reservoir has never been sampled and is probably located at the base of the mantle. These data influence models of Earth's compositional structure and require revision of the timing of global differentiation on Earth's Moon and Mars.     

Mechanisms of Porphyroblast Crystallization: Results from High-Resolution Computed X-ray Tomography

Quantitative three-dimensional analysis of rock textures is now possible with the use of high-resolution computed x-ray tomography. When applied to metamorphic rocks, this technique provides data on the sizes and positions of minerals that allow mechanisms of porphyroblast crystallization to be identified. Statistical analysis of the sizes and spatial disposition of thousands of garnet crystals in three regionally metamorphosed rocks with diverse mineralogies, in conjunction with simple numerical models for crystallization, reveals in all cases the dominance of crystallization mechanisms whose kinetics are governed by rates of intergranular diffusion of nutrients.     

Predicting human brain activity associated with the meanings of nouns

The question of how the human brain represents conceptual knowledge has been debated in many scientific fields. Brain imaging studies have shown that different spatial patterns of neural activation are associated with thinking about different semantic categories of pictures and words (for example, tools, buildings, and animals). We present a computational model that predicts the functional magnetic resonance imaging (fMRI) neural activation associated with words for which fMRI data are not yet available. This model is trained with a combination of data from a trillion-word text corpus and observed fMRI data associated with viewing several dozen concrete nouns. Once trained, the model predicts fMRI activation for thousands of other concrete nouns in the text corpus, with highly significant accuracies over the 60 nouns for which we currently have fMRI data.     

A partial pelvis of Australopithecus sediba

The fossil record of the hominin pelvis reflects important evolutionary changes in locomotion and parturition. The partial pelves of two individuals of Australopithecus sediba were reconstructed from previously reported finds and new material. These remains share some features with australopiths, such as large biacetabular diameter, small sacral and coxal joints, and long pubic rami. The specimens also share derived features with Homo, including more vertically oriented and sigmoid-shaped iliac blades, greater robusticity of the iliac body, sinusoidal anterior iliac borders, shortened ischia, and more superiorly oriented pubic rami. These derived features appear in a species with a small adult brain size, suggesting that the birthing of larger-brained babies was not driving the evolution of the pelvis at this time.     

Effects of dietary selenium supply and timing of nutrient restriction during gestation on maternal growth and body composition of pregnant adolescent ewes

The objectives were to examine effects of dietary Se supplementation and nutrient restriction during defined periods of gestation on maternal adaptations to pregnancy in primigravid sheep. Sixty-four pregnant Western Whiteface ewe lambs were assigned to treatments in a 2 x 4 factorial design. Treatments were dietary Se [adequate Se (ASe; 3.05 microg/kg of BW) vs. high Se (HSe; 70.4 microg/kg of BW)] fed as Se-enriched yeast, and plane of nutrition [control (C; 100% of NRC requirements) vs. restricted (R; 60% of NRC requirements]. Selenium treatments were fed throughout gestation. Plane of nutrition treatments were applied during mid (d 50 to 90) and late gestation (d 90 to 130), which resulted in 4 distinct plane of nutrition treatments [treatment: CC (control from d 50 to 130), RC (restricted from d 50 to 90, and control d 90 to 130), CR (control from d 50 to 90, and restricted from d 90 to 130), and RR (restricted from d 50 to 130)]. All of the pregnant ewes were necropsied on d 132 +/- 0.9 of gestation (length of gestation approximately 145 d). Nutrient restriction treatments decreased ewe ADG and G:F, as a result, RC and CR ewes had similar BW and maternal BW (MBW) at necropsy, whereas RR ewes were lighter than RC and CR ewes. From d 90 to 130, the HSe-CC ewes had greater ADG (Se x nutrition; P = 0.05) than did ASe-CC ewes, whereas ADG and G:F (Se x nutrition; P = 0.08) were less for HSe-RR ewes compared with ASe-RR ewes. The CR and RR treatments decreased total gravid uterus weight (P = 0.01) as well as fetal weight (P = 0.02) compared with RC and CC. High Se decreased total (g; P = 0.09) and relative heart mass (g/kg of MBW; P = 0.10), but increased total and relative mass of liver (P < or = 0.05) and perirenal fat (P < or = 0.06) compared with ASe. Total stomach complex mass was decreased (P < 0.01) by all the nutrient restriction treatments, but was reduced to a greater extent in CR and RR compared with RC. Total small intestine mass was similar between RC and CC ewes, but was markedly reduced (P < 0.01) in CR and RR ewes. The mass of the stomach complex and the small and large intestine relative to MBW was greater (P = 0.01) for RC than for CR ewes. Increased Se decreased jejunal DNA concentration (P = 0.07), total jejunal cell number (P = 0.03), and total proliferating jejunal cell number (P = 0.05) compared with ASe. These data indicate that increased dietary Se affected whole-body and organ growth of pregnant ewes, but the results differed depending on the plane of nutrition. In addition, the timing and duration of nutrient restriction relative to stage of pregnancy affected visceral organ mass in a markedly different fashion.     

Agricultural injuries among operation household members: RRIS-II 1999

The purpose of this study was to determine the magnitude and consequences of agricultural injuries, and to reveal potential risk factors among agricultural household members. The Regional Rural Injury Study (RRIS-II) collected injury and exposure data on agricultural households of 16,538 people in Minnesota, Wisconsin, North Dakota, South Dakota, and Nebraska for each six-month period of 1999. Adjusted injury rates, consequences, and potential risk factors were identified through analyses. Selection of variables for multivariate analyses was based on a causal model. Injuries reported here occurred while the individuals were involved in activities associated with their own farm or ranch, unless otherwise stated. Estimates of injury rates and the effects of various exposures were derived by Poisson and logistic regression. These models accounted for correlation within both subject and household, and were adjusted for non-response. The rate of agricultural injury to household members on their own operation was 74.5 injuries per 1,000 persons per year. Differences in rates due to age and gender diminished when rates were calculated according to hours worked. Although only 5% of injured persons required in-patient hospitalization, 28% required emergency department treatment, and 84% required some type of professional health care. Moreover, 47% of all injuries required time off from agricultural work, and 7% required time off from non-agricultural work. In multivariate analyses, decreased risks were associated with Minnesota, and increased risks were identified for those with prior injuries and for males.This study provides a basis for further research on agricultural injuries and their prevention.     

Zinc is involved in regulation of secretion from intestinal epithelium in weaned piglets

The objective was to study the effect of serosal zinc (Zn) on intestinal chloride (Cl⁻) secretion in vitro by the Ussing chamber technique. The secretagogues used to stimulate Cl⁻ secretion were serotonin (5-HT), vasoactive intestinal polypeptide (VIP) and forskolin (FSK). In addition correlations between organ and plasma Zn levels vs. the responses to 5-HT were studied. The results revealed an attenuating effect of serosal Zn on the secretory response to 5-HT, VIP and FSK. Furthermore, negative correlations between secretory responses to 5-HT vs. ADG and plasma Zn concentrations were found, whereas the responses to 5-HT did not correlate to the Zn concentration in liver or intestinal mucosa. It is suggested, that dietary Zn reduces diarrhoea directly through a regulatory role of serosal Zn on Cl⁻ secretion and indirectly by improving the nutritional status, which may stabilize the function of the intestinal epithelium.