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91.
The evolutionary history that led to Eocene-and-later primates of modern aspect (Euprimates) has been uncertain. We describe a skeleton of Paleocene plesiadapiform Carpolestes simpsoni that includes most of the skull and many postcranial bones. Phylogenetic analyses indicate that Carpolestidae are closely related to Euprimates. C. simpsoni had long fingers and an opposable hallux with a nail. It lacked orbital convergence and an ankle specialized for leaping. We infer that the ancestor of Euprimates was primitively an arboreal grasper adapted for terminal branch feeding rather than a specialized leaper or visually directed predator. 相似文献
92.
Climate reconstructions reveal unprecedented warming in the past century; however, little is known about trends in aspects such as the monsoon. We reconstructed the monsoon winds for the past 1000 years using fossil Globigerina bulloides abundance in box cores from the Arabian Sea and found that monsoon wind strength increased during the past four centuries as the Northern Hemisphere warmed. We infer that the observed link between Eurasian snow cover and the southwest monsoon persists on a centennial scale. Alternatively, the forcing implicated in the warming trend (volcanic aerosols, solar output, and greenhouse gases) may directly affect the monsoon. Either interpretation is consistent with the hypothesis that the southwest monsoon strength will increase during the coming century as greenhouse gas concentrations continue to rise and northern latitudes continue to warm. 相似文献
93.
White fat progenitor cells reside in the adipose vasculature 总被引:1,自引:0,他引:1
Tang W Zeve D Suh JM Bosnakovski D Kyba M Hammer RE Tallquist MD Graff JM 《Science (New York, N.Y.)》2008,322(5901):583-586
White adipose (fat) tissues regulate metabolism, reproduction, and life span. Adipocytes form throughout life, with the most marked expansion of the lineage occurring during the postnatal period. Adipocytes develop in coordination with the vasculature, but the identity and location of white adipocyte progenitor cells in vivo are unknown. We used genetically marked mice to isolate proliferating and renewing adipogenic progenitors. We found that most adipocytes descend from a pool of these proliferating progenitors that are already committed, either prenatally or early in postnatal life. These progenitors reside in the mural cell compartment of the adipose vasculature, but not in the vasculature of other tissues. Thus, the adipose vasculature appears to function as a progenitor niche and may provide signals for adipocyte development. 相似文献
94.
Feng JL 《Science (New York, N.Y.)》2003,302(5646):795-797
95.
Kerns JG Cohen JD MacDonald AW Cho RY Stenger VA Carter CS 《Science (New York, N.Y.)》2004,303(5660):1023-1026
Conflict monitoring by the anterior cingulate cortex (ACC) has been posited to signal a need for greater cognitive control, producing neural and behavioral adjustments. However, the very occurrence of behavioral adjustments after conflict has been questioned, along with suggestions that there is no direct evidence of ACC conflict-related activity predicting subsequent neural or behavioral adjustments in control. Using the Stroop color-naming task and controlling for repetition effects, we demonstrate that ACC conflict-related activity predicts both greater prefrontal cortex activity and adjustments in behavior, supporting a role of ACC conflict monitoring in the engagement of cognitive control. 相似文献
96.
Stebbins JF 《Science (New York, N.Y.)》2002,297(5585):1285-1287
97.
Endocannabinoid hydrolysis generates brain prostaglandins that promote neuroinflammation 总被引:2,自引:0,他引:2
Nomura DK Morrison BE Blankman JL Long JZ Kinsey SG Marcondes MC Ward AM Hahn YK Lichtman AH Conti B Cravatt BF 《Science (New York, N.Y.)》2011,334(6057):809-813
Phospholipase A(2)(PLA(2)) enzymes are considered the primary source of arachidonic acid for cyclooxygenase (COX)-mediated biosynthesis of prostaglandins. Here, we show that a distinct pathway exists in brain, where monoacylglycerol lipase (MAGL) hydrolyzes the endocannabinoid 2-arachidonoylglycerol to generate a major arachidonate precursor pool for neuroinflammatory prostaglandins. MAGL-disrupted animals show neuroprotection in a parkinsonian mouse model. These animals are spared the hemorrhaging caused by COX inhibitors in the gut, where prostaglandins are instead regulated by cytosolic PLA(2). These findings identify MAGL as a distinct metabolic node that couples endocannabinoid to prostaglandin signaling networks in the nervous system and suggest that inhibition of this enzyme may be a new and potentially safer way to suppress the proinflammatory cascades that underlie neurodegenerative disorders. 相似文献
98.
Climate data are dramatically increasing in volume and complexity, just as the users of these data in the scientific community and the public are rapidly increasing in number. A new paradigm of more open, user-friendly data access is needed to ensure that society can reduce vulnerability to climate variability and change, while at the same time exploiting opportunities that will occur. 相似文献
99.
100.
Toward inherently secure and resilient societies 总被引:3,自引:0,他引:3
Recent years have seen a number of challenges to social stability and order, ranging from terrorist attacks and natural disasters to epidemics such as AIDS and SARS. Such challenges have generated specific policy responses, such as enhanced security at transportation hubs and planned deployment of a global tsunami detection network. However, the range of challenges and the practical impossibility of adequately addressing each in turn argue for adoption of a more comprehensive systems perspective. This should be based on the principle of enhancing social and economic resiliency as well as meeting security and emergency response needs and, to the extent possible, developing and implementing dual-use technologies that offer societal benefits even if anticipated disasters never occur. 相似文献