Evolution. Is the "Big Bang" in animal evolution real?     

Jermiin LS  Poladian L  Charleston MA 《Science (New York, N.Y.)》2005,310(5756):1910-1911

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Ecology: The Convention on Biological Diversity's 2010 target     

Balmford A  Bennun L  Brink BT  Cooper D  Côte IM  Crane P  Dobson A  Dudley N  Dutton I  Green RE  Gregory RD  Harrison J  Kennedy ET  Kremen C  Leader-Williams N  Lovejoy TE  Mace G  May R  Mayaux P  Morling P  Phillips J  Redford K  Ricketts TH  Rodríguez JP  Sanjayan M  Schei PJ  van Jaarsveld AS  Walther BA 《Science (New York, N.Y.)》2005,307(5707):212-213

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Gender, land, and water: From reform to counter-reform in Latin America     

Carmen Diana Deere  Magdalena Leon 《Agriculture and Human Values》1998,15(4):375-386

Rural women did not fare very well inthe land reforms carried out during the Latin Americanreformist period of the 1960s and 1970s, with womenbeing under-represented among the beneficiaries. It isargued that women have been excluded from access toand control over water for similar reasons that theywere excluded from access to land during thesereforms. The paper also investigates the extent towhich women have gained or lost access to land duringthe counter-reforms of the 1980s and 1990s. Underthe neo-liberal agenda, production cooperatives aswell as communal access to land have largely beenundermined in favor of privatization and theindividual parcelization of collectives. Significantland titling efforts are also being carried outthroughout the region to promote the development of avigorous land market. This latter period has also beencharacterized by the growth of the feminist movementthroughout Latin America and a growing commitment bystates to gender equity. The paper reviews the extentto which rural womens access to land and, thus, waterhas potentially been enhanced by recent changes inagrarian and legal codes.  相似文献   

Protein digestive dynamics of meat and bone meals in broiler chickens     

Shemil P. Macelline  Leon R. McQuade  Bernie V. Mclnerney  Amy F. Moss  Peter H. Selle  Sonia Y. Liu 《动物营养（英文）》2020,6(4):521-528

This study determined the variations in protein digestibilities and digestion rates in broiler chickens offered diets containing 7 different meat and bone meals (MBM). A total of 252 male Ross 308 broiler chickens were offered 7 atypical diets largely based on maize and MBM from 24 to 28 d post-hatch. Each experimental diet was offered to 6 replicates with 6 birds per replicate cage. Excreta were collected in their entirety from 25 to 27 d post-hatch and on 28 d post-hatch. Digesta samples were collected from the proximal jejunum, distal jejunum, proximal ileum and distal ileum. Apparent digestibilities of protein were determined in each segment and apparent digestibilities of amino acids were measured in the distal ileum. There were significant differences in apparent protein digestibility coefficients in the proximal jejunum (P = 0.006), where broiler chickens offered the high ash beef meal (diet 7) generated the lowest protein digestibility in the proximal jejunum (0.318). Similarly, there were significant differences in apparent digestibility coefficients in the distal jejunum (P < 0.001) and distal ileum (P < 0.001) but not in the proximal ileum. More pronounced differences were found in the disappearance rate of protein and there were significant differences in all 4 segments of the small intestine (P < 0.001). Broiler chickens offered the high ash beef meal had the lowest protein disappearance rate (P < 0.001). No difference was observed in the predicted protein digestion rate (P = 0.486) but chickens offered the high ash beef meal had the lowest potential digestible protein (0.662, P = 0.034) whereas the highest potential digestible protein (0.739) was detected in diet 5 (containing a beef meal). This study contributed to the establishment of a preliminary database to include digestion rates of starch and protein into practical diet formulation.  相似文献   

Tools to study trends in community structure: application to fish and livestock trading networks     

Green DM  Werkman M  Munro LA  Kao RR  Kiss IZ  Danon L 《Preventive veterinary medicine》2011,99(2-4):225-228

Partitioning of contact networks into communities allows groupings of epidemiologically related nodes to be derived, that could inform the design of disease surveillance and control strategies, e.g. contact tracing or design of 'firebreaks' for disease spread. However, these are only of merit if they persist longer than the timescale of interventions. Here, we apply different methods to identify concordance between network partitions across time for two animal trading networks, those of salmon in Scotland (2002-2004) and livestock in Great Britain (2003-2004). Both trading networks are similar in that they moderately agree over time in terms of their community structures, but this concordance is higher--and therefore community structure is more consistent--when only the 'core' network of nodes involved in trading over the whole time series is considered. In neither case was higher agreement found between partitions close together in time. These measures differ in their absolute values unless appropriate standardisation is applied. Once standardised, the measures gave similar values for both network types.  相似文献   

Images of asteroid 21 Lutetia: a remnant planetesimal from the early Solar System     

Sierks H  Lamy P  Barbieri C  Koschny D  Rickman H  Rodrigo R  A'Hearn MF  Angrilli F  Barucci MA  Bertaux JL  Bertini I  Besse S  Carry B  Cremonese G  Da Deppo V  Davidsson B  Debei S  De Cecco M  De Leon J  Ferri F  Fornasier S  Fulle M  Hviid SF  Gaskell RW  Groussin O  Gutierrez P  Ip W  Jorda L  Kaasalainen M  Keller HU  Knollenberg J  Kramm R  Kührt E  Küppers M  Lara L  Lazzarin M  Leyrat C  Lopez Moreno JJ  Magrin S  Marchi S  Marzari F  Massironi M  Michalik H  Moissl R  Naletto G  Preusker F  Sabau L  Sabolo W  Scholten F 《Science (New York, N.Y.)》2011,334(6055):487-490

Images obtained by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras onboard the Rosetta spacecraft reveal that asteroid 21 Lutetia has a complex geology and one of the highest asteroid densities measured so far, 3.4 ± 0.3 grams per cubic centimeter. The north pole region is covered by a thick layer of regolith, which is seen to flow in major landslides associated with albedo variation. Its geologically complex surface, ancient surface age, and high density suggest that Lutetia is most likely a primordial planetesimal. This contrasts with smaller asteroids visited by previous spacecraft, which are probably shattered bodies, fragments of larger parents, or reaccumulated rubble piles.  相似文献   

The Use of Herbs in Pastures: An Interview Survey Among Bio-Dynamic and Organic Farmers with Dairy Cattle     

Naja?W.?Smidt  Leon?BrimerEmail author 《Agriculture and Human Values》2005,22(3):355-363

Lack of knowledge about the effects of herbs in pastures and the frequency of their use by today's organic farmers has limited the development of new methods to improve animal health compatible with organic farming principles. Understanding farmers' agricultural practices is an early step in a participatory research process. With this in mind, we conducted a two-tiered, semi-structured survey of Danish organic farmers with dairy cattle to begin documenting their practices. Out of 350 farmers, 255 completed a mailed questionnaire – a response rate of 73%. Of these participating farmers, 66 (26%) confirmed their use of herbs in pastures. Caraway was sown at an average rate of 500 g of seed per hectare by 60 (91%). Of these, 32 used solely caraway, while 7 used it in combination with parsley. Twenty-one used caraway together with herbs other than parsley. Six used one or more herbs, not including caraway, such as chicory, chervil, dill, fenugreek, great burnet, and salad burnet. Further details concerning cultivation, convictions, observed effects, and information sources were obtained through telephone interviews. The results of this study would indicate that more research in this field is called for. Naja W. Smidt is a M.Sc. student in agricultural sciences at the Royal Veterinary and Agricultural University, Denmark. Leon Brimer is an Associate Professor of chemical food safety at the Royal Veterinary and Agricultural University, Denmark. His research focuses on the interface between chemistry and biology with special emphasis on aspects of cultivation, processing, and use of plants with physiologically active components (toxins).  相似文献   

Localization of a stable neural correlate of associative memory     

Reijmers LG  Perkins BL  Matsuo N  Mayford M 《Science (New York, N.Y.)》2007,317(5842):1230-1233

Do learning and retrieval of a memory activate the same neurons? Does the number of reactivated neurons correlate with memory strength? We developed a transgenic mouse that enables the long-lasting genetic tagging of c-fos-active neurons. We found neurons in the basolateral amygdala that are activated during Pavlovian fear conditioning and are reactivated during memory retrieval. The number of reactivated neurons correlated positively with the behavioral expression of the fear memory, indicating a stable neural correlate of associative memory. The ability to manipulate these neurons genetically should allow a more precise dissection of the molecular mechanisms of memory encoding within a distributed neuronal network.  相似文献   

Colossal ionic conductivity at interfaces of epitaxial ZrO2:Y2O3/SrTiO3 heterostructures     

Garcia-Barriocanal J  Rivera-Calzada A  Varela M  Sefrioui Z  Iborra E  Leon C  Pennycook SJ  Santamaria J 《Science (New York, N.Y.)》2008,321(5889):676-680

The search for electrolyte materials with high oxygen conductivities is a key step toward reducing the operation temperature of fuel cells, which is currently above 700 degrees C. We report a high lateral ionic conductivity, showing up to eight orders of magnitude enhancement near room temperature, in yttria-stabilized zirconia (YSZ)/strontium titanate epitaxial heterostructures. The enhancement of the conductivity is observed, along with a YSZ layer thickness-independent conductance, showing that it is an interface process. We propose that the atomic reconstruction at the interface between highly dissimilar structures (such as fluorite and perovskite) provides both a large number of carriers and a high-mobility plane, yielding colossal values of the ionic conductivity.  相似文献   

Muscle fiber types in Crioulo horses     

Inês N. de Castro PhD  Nadja L. Pinheiro PhD  Flvio De La Corte PhD  Carlos Eduardo Nogueira PhD  Igncio Leon DVM 《Journal of Equine Veterinary Science》2004,24(5):204-209

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