Highly-silicic glass inclusions in eucrites and diogenites

Textural and chemical descriptions are reported for glass inclusions from the Dhofar 007 cumulate eucrite and the Johnstown and Tatahouine diogenites. Although previous studies described inclusions of tridymite or cristobalite, the glass inclusions found in the present samples are distributed in planar arrays transecting mineral grains, indicating a secondary origin. These glass inclusions often contain precipitated daughter minerals, such as negative crystals of chromite and troilite. Assuming each of these inclusions originally was a single phase having a homogeneous composition, EPMA and LAM-ICP-MS data suggest that the parent melts were highly silicic and sulphur-rich, and had low abundances of incompatible elements. These glass inclusions in cumulate eucrites and diogenites may be derived from silica-rich melts generated from the incongruent melting of orthopyroxene

Bazedoxifene, a selective estrogen receptor modulator, reduces cerebral aneurysm rupture in Ovariectomized rats.

BackgroundEstrogen deficiency is thought to be responsible for the higher frequency of aneurysmal subarachnoid hemorrhage in post- than premenopausal women. Estrogen replacement therapy appears to reduce this risk but is associated with significant side effects. We tested our hypothesis that bazedoxifene, a clinically used selective estrogen receptor (ER) modulator with fewer estrogenic side effects, reduces cerebral aneurysm rupture in a new model of ovariectomized rats.MethodsTen-week-old female Sprague-Dawley rats were subjected to ovariectomy, hemodynamic changes, and hypertension to induce aneurysms (ovariectomized aneurysm rats) and treated with vehicle or with 0.3 or 1.0 mg/kg/day bazedoxifene. They were compared with sham-ovariectomized rats subjected to hypertension and hemodynamic changes (HT rats). The vasoprotective effects of bazedoxifene and the mechanisms underlying its efficacy were analyzed.ResultsDuring 12 weeks of observation, the incidence of aneurysm rupture was 52% in ovariectomized rats. With no effect on the blood pressure, treatment with 0.3 or 1.0 mg/kg/day bazedoxifene lowered this rate to 11 and 17%, almost the same as in HT rats (17%). In ovariectomized rats, the mRNA level of ERα, ERβ, and the tissue inhibitor of metalloproteinase-2 was downregulated in the cerebral artery prone to rupture at 5 weeks after aneurysm induction; the mRNA level of interleukin-1β and the matrix metalloproteinase-9 was upregulated. In HT rats, bazedoxifene restored the mRNA level of ERα and ERβ and decreased the level of interleukin-1β and matrix metalloproteinase-9. These findings suggest that bazedoxifene was protective against aneurysmal rupture by alleviating the vascular inflammation and degradation exacerbated by the decrease in ERα and ERβ.ConclusionsOur observation that bazedoxifene decreased the incidence of aneurysmal rupture in ovariectomized rats warrants further studies to validate this response in humans

Hyperhomocysteinemia induced by excessive methionine intake promotes rupture of cerebral aneurysms in ovariectomized rats.

BackgroundHyperhomocysteinemia (HHcy) is associated with inflammation and a rise in the expression of matrix metalloproteinase-9 (MMP-9) in the vascular wall. However, the role of HHcy in the growth and rupture of cerebral aneurysms remains unclear.MethodsThirteen-week-old female Sprague-Dawley rats were subject to bilateral ovariectomy and ligation of the right common carotid artery and fed an 8 % high-salt diet to induce cerebral aneurysms. Two weeks later, they underwent ligation of the bilateral posterior renal arteries. They were divided into two groups and methionine (MET) was or was not added to their drinking water. In another set of experiments, the role of folic acid (FA) against cerebral aneurysms was assessed.ResultsDuring a 12-week observation period, subarachnoid hemorrhage due to aneurysm rupture was observed at the anterior communicating artery (AcomA) or the posterior half of the circle of Willis. HHcy induced by excessive MET intake significantly increased the incidence of ruptured aneurysms at 6-8 weeks. At the AcomA of rats treated with MET, we observed the promotion of aneurysmal growth and infiltration by M1 macrophages. Furthermore, the mRNA level of MMP-9, the ratio of MMP-9 to the tissue inhibitor of metalloproteinase-2, and the level of interleukin-6 were higher in these rats. Treatment with FA abolished the effect of MET, suggesting that the inflammatory response and vascular degradation at the AcomA is attributable to HHcy due to excessive MET intake.ConclusionsWe first demonstrate that in hypertensive ovariectomized rats, HHcy induced by excessive MET intake may be associated with the propensity of the aneurysm wall to rupture

Macrobenthic assemblage structure and organismal stoichiometry control faunal processing of particulate organic carbon and nitrogen in oxygen minimum zone sediments

Peer reviewedPublisher PD

In Search of a Sustainable Global Agri-Food System

The potential to meet global food demand fully exists through global development of the high-technology (HT), high-intensity type of agriculture and food processing system prevailing in developed countries. This system unfortunately is also responsible for much natural resource degradation, environmental damage and ecological imbalance. Meantime the Earth's human population continues to grow, placing ever-increasing demand on global natural resources, not only for food but also for living and recreational space. A more sustainable agri-food system must evolve. Sustainability is complex, and ought to be approached from a multidisciplinary perspective and compromise sought in resolving the obvious conflicts amongst biological, environmental, ecological, socio-economic, and other individual disciplines and competing philosophies. These form the basis for comparing three different agricultural production systems: high technology (HT); reduced input (RI), and organic (ORG). The three systems are compared empirically using primary data from farms in each group in southern Ontario, Canada. HT systems prevalent in Canada is highly productive, but its sustainability is questionable. It was concluded that the HT system should not be the model for the future. The ORG system is the least inimical to the environment, ecology, and human operators. It was concluded that the ORG system is sustainable except for its requirement for extensive use of land. The RI system causes minimal environmental and ecological damage. It is most profitable and is supportive of rural farm community viability. It was concluded that the RI system holds the best potential for meeting overall sustainability for the global agri-food system.Farm Management, Land Economics/Use,

Effect of Density Inhomogeneity on YORP: The case of Itokawa

The effect of density inhomogeneity on the YORP effect for a given shape model is investigated. A density inhomogeneity will cause an offset between the center of figure and the center of mass and a re-orientation of the principal axes away from those associated with the shape alone. Both of these effects can alter the predicted YORP rate of change in angular velocity and obliquity. We apply these corrections to the Itokawa shape model and find that its YORP angular velocity rate is sensitive to offsets between its center of mass and center of figure, with a shift on the order of 10 meters being able to change the sign of the YORP effect for that asteroid. Given the non-detection of YORP for Itokawa as of 2008, this can shed light on the density distribution within that body. The theory supports a shift of the asteroid center of mass towards Itokawa's neck region, where there is an accumulation of finer gravels. Detection of the YORP effect for Itokawa should provide some strong constraints on its density distribution. This theory could also be applied to asteroids visited by future spacecraft to constrain density inhomogeneities.Comment: 23 pages, 3 figure

The importance of diazotrophic cyanobacteria as primary producers during Cretaceous Oceanic Anoxic Event 2

In Livello Bonarelli black shale deposited during Cretaceous Oceanic Anoxic Event 2 (OAE-2, ca.&nbsp;94 Ma), nitrogen isotopic compositions of bulk sediments are mostly in a narrow range from &ndash;2.7 to &ndash;0.7&permil;. We also determined molecular distribution and nitrogen isotopic compositions of geoporphyrins extracted from the black shale. The nitrogen isotopic compositions of C₃₂ Ni deoxophylloerythroetioporphyrin (DPEP) and total Ni porphyrins are &ndash;3.5 and &ndash;3.3&permil;, respectively, leading us to the estimation that the mean nitrogen isotopic composition of photoautotrophic cells were around +1&permil; during the formation of Bonarelli black shale. This value is suggestive of N₂-fixation, a dominant process for these photoautotrophs when assimilating nitrogen. Furthermore, Ni-chelated C₃₂ DPEP, derived mainly from chlorophyll <i>a</i> had the highest concentration. Based on this evidence, we conclude that diazotrophic cyanobacteria were major primary producers during that time. Cyanobacteria may be key photoautotrophs during the formation of black shale type sediments intermittently observed throughout the later half of the Earth&apos;s history, and hence may have played a crucial role in the evolution of geochemical cycles even in the later half of the Earth&apos;s history

An importance of diazotrophic cyanobacteria as a primary producer during Cretaceous Oceanic Anoxic Event 2

International audienceIn Livello Bonarelli black shale deposited during Cretaceous Oceanic Anoxic Event 2 (OAE-2, ca. 94 Ma), nitrogen isotopic compositions of bulk sediments are in a narrow range from ?2.7 to ?0.7. We also determined molecular distribution and nitrogen isotopic compositions of geoporphyrins extracted from the black shale. The nitrogen isotopic compositions of C32 Ni deoxophylloerythroetioporphyrin (DPEP) and total Ni porphyrins are ?3.5 and ?3.3, respectively, leading us to the estimation that the mean nitrogen isotopic composition of photoautotrophic cell was around +1 during the formation of Bonarelli black shale. This value is suggestive of N2-fixation a dominant process for these photoautotrophs when assimilating nitrogen. Furthermore, Ni-chelated C32 DPEP, derived mainly from chlorophyll a was the highest concentration. Based on these evidence, we conclude that diazotrophic cyanobacteria were major primary producers during that time. The cyanobacteria may be key photoautotrophs during the formation of black shale type sediments intermittently observed throughout the later half of the Earth's history, and hence may have played a crucial role in the evolution of geochemical cycles