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Search Results: 1 - 10 of 114 matches for " Lowell "
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Stem cells in the genomic age
Sally Lowell
Genome Biology , 2006, DOI: 10.1186/gb-2006-7-5-315
Abstract: Stem cells span the divide between cell biology and developmental biology, and so were an especially appropriate subject for the recent joint meeting of the British Society for Developmental Biology (BSDB) and the British Society for Cell Biology (BSCB) this spring. Speakers from around the world explored this fascinating topic from a wide variety of perspectives and it was particularly interesting to see how new and emerging technologies are being used to uncover some of the mysteries of cell-fate determination.Cheryll Tickle (University of Dundee, UK) opened the meeting by telling us that the chick, which has been a model system for embryology since the time of Aristotle, is now entering the genomic age. The chicken genome sequence was published a year ago, and chick DNA microarrays are just now becoming available. Tickle exemplified the power of combining these new genetic tools with the more traditional strengths of the chick embryo in the analysis of the spontaneous mutant Talpid3. Talpid3 protein appears to be required specifically at sites of signaling by the Sonic hedgehog (Shh) protein, and experimental manipulation of Shh availability confirms a failure to respond properly to Shh in this mutant. Tickle outlined how Dave Burt and colleagues at the Roslin Institute have isolated the Talpid3 gene by positional cloning but the sequence gives no real clue as to the gene's function. The mechanism by which Talpid3 interacts with the Shh pathway is thus still under investigation.The theme of using traditional model systems in novel ways was continued by Ethan Bier (University of California at San Diego, La Jolla, USA). The fruit fly Drosophila is a powerful tool for genetic analysis that has revealed many general principles of developmental patterning. Bier convinced us that flies are also surprisingly efficient tools for understanding the genetic basis of human disease. He pointed out that of the 2,500 or so genes that have been linked to human diseases, around t
Ra?a e gênero no Brasil
Lowell, Peggy;
Lua Nova: Revista de Cultura e Política , 1995, DOI: 10.1590/S0102-64451995000100003
Abstract: using sample data from the 1960 and 1980 demografic censuses (the most recent available), this study estimates the magnitude of racial differences by gender in place of residence, education, occupational distribution, and wages. contrary to predictions that race and gender divisions in the workplace would yield to the homogenizing forces of industrialization, it is demonstrated that the modern urban labor market in brazil continues to be segregated by race and gender.
Vanessa Milberti in Boston
John Lowell
Psyche , 1907, DOI: 10.1155/1907/26353
Abstract:
Tall fescue seed extraction and partial purification of ergot alkaloids
Lowell Bush
Frontiers in Chemistry , 2014, DOI: 10.3389/fchem.2014.00110
Abstract: Many substances in the tall fescue/endophyte association (Schedonorus arundinaceus/Epichlo? coenophiala) have biological activity. Of these compounds only the ergot alkaloids are known to have significant mammalian toxicity and the predominant ergot alkaloids are ergovaline and ergovalinine. Because synthetically produced ergovaline is difficult to obtain, we developed a seed extraction and partial purification protocol for ergovaline/ergovalinine that provided a biologically active product. Tall fescue seed was ground and packed into several different sized columns for liquid extraction. Smaller particle size and increased extraction time increased efficiency of extraction. Our largest column was a 114 × 52 × 61 cm (W×L×D) stainless steel tub. Approximately 150 kg of seed could be extracted in this tub. The extraction was done with 80% ethanol. When the solvent front migrated to bottom of the column, flow was stopped and seed was allowed to steep for at least 48 h. Light was excluded from the solvent from the beginning of this step to the end of the purification process. Following elution, ethanol was removed from the eluate by evaporation at room temperature. Resulting syrup was freeze-dried. About 80% recovery of alkaloids was achieved with 18-fold increase in concentration of ergovaline. Initial purification of the dried product was accomplished by extracting with hexane/water (6:1, v/v) and the hexane fraction was discarded. The aqueous fraction was extracted with chloroform, the aqueous layer discarded, after which the chloroform was removed with a resulting 20-fold increase of ergovaline. About 65% of the ergovaline was recovered from the chloroform residue for an overall recovery of 50%. The resultant partially purified ergovaline had biological activities in in vivo and in vitro bovine bioassays that approximate that of synthetic ergovaline.
A Seifert-van Kampen Theorem for Legendrian Submanifolds and Exact Lagrangian Cobordisms
Mark Lowell
Mathematics , 2015,
Abstract: We prove a Seifert-van Kampen theorem for Legendrian submanifolds and exact Lagrangian cobordisms, and use it to calculate the change in the DGA caused by critical Legendrian ambient surgery.
Modules, comodules and cotensor products over Frobenius algebras
Lowell Abrams
Mathematics , 1998,
Abstract: We characterize noncommutative Frobenius algebras A in terms of the existence of a coproduct which is a map of left A^e-modules. We show that the category of right (left) comodules over A, relative to this coproduct, is isomorphic to the category of right (left) modules. This isomorphism enables a reformulation of the cotensor product of Eilenberg and Moore as a functor of modules rather than comodules. We prove that the cotensor product M \Box N of a right A-module M and a left A-module N is isomorphic to the vector space of homomorphisms from a particular left A^e-module D to N \otimes M, viewed as a left A^e-module. Some properties of D are described. Finally, we show that when A is a symmetric algebra, the cotensor product M \Box N and its derived functors are given by the Hochschild cohomology over A of N \otimes M.
The quantum Euler class and the quantum cohomology of the Grassmannians
Lowell Abrams
Mathematics , 1997,
Abstract: The Poincare duality of classical cohomology and the extension of this duality to quantum cohomology endows these rings with the structure of a Frobenius algebra. Any such algebra possesses a canonical ``characteristic element;'' in the classical case this is the Euler class, and in the quantum case this is a deformation of the classical Euler class which we call the ``quantum Euler class.'' We prove that the characteristic element of a Frobenius algebra A is a unit if and only if A is semisimple, and then apply this result to the cases of the quantum cohomology of the finite complex Grassmannians, and to the quantum cohomology of hypersurfaces. In addition we show that, in the case of the Grassmannians, the [quantum] Euler class equals, as [quantum] cohomology element and up to sign, the determinant of the Hessian of the [quantum] Landau-Ginzbug potential.
Sustainable, Full-Scope Nuclear Fission Energy at Planetary Scale
Robert Petroski,Lowell Wood
Sustainability , 2012, DOI: 10.3390/su4113088
Abstract: A nuclear fission-based energy system is described that is capable of supplying the energy needs of all of human civilization for a full range of human energy use scenarios, including both very high rates of energy use and strikingly-large amounts of total energy-utilized. To achieve such “planetary scale sustainability”, this nuclear energy system integrates three nascent technologies: uranium extraction from seawater, manifestly safe breeder reactors, and deep borehole disposal of nuclear waste. In addition to these technological components, it also possesses the sociopolitical quality of manifest safety, which involves engineering to a very high degree of safety in a straightforward manner, while concurrently making the safety characteristics of the resulting nuclear systems continually manifest to society as a whole. Near-term aspects of this nuclear system are outlined, and representative parameters given for a system of global scale capable of supplying energy to a planetary population of 10 billion people at a per capita level enjoyed by contemporary Americans, i.e., of a type which might be seen a half-century hence. In addition to being sustainable from a resource standpoint, the described nuclear system is also sustainable with respect to environmental and human health impacts, including those resulting from severe accidents.
The Current Evidence for Hayek’s Cultural Group Selection Theory
Brad Lowell Stone
Libertarian Papers , 2010,
Abstract: In this article I summarize Friedrich Hayek’s cultural group selection theory and describe the evidence gathered by current cultural group selection theorists within the behavioral and social sciences supporting Hayek’s main assertions. I conclude with a few comments on Hayek and libertarianism.
THE PHILIPPINE TREATY LIMITS AND TERRITORIAL WATERS CLAIM IN INTERNATIONAL LAW
Lowell B. Bautista
Social Science Diliman , 2009,
Abstract: The fundamental position of the Philippines regarding the extent of its territorial and maritime boundaries is based on two contentious premises: first, that the limits of its national territory are the boundaries laid down in the 1898 Treaty of Paris which ceded the Philippines from Spain to the UnitedStates; and second, that all the waters embraced within these imaginary lines are its territorial waters. The position of the Philippine Government is contested in the international community and runs against rules in the Law of the SeaConvention, which the Philippines signed and ratified. This situation poses two fundamental unresolved issues of conflict: first, is the issue on the breadth of its territorial sea, and second, its treatment of supposed archipelagic watersas internal waters. The twin issues of the legal status of the Philippine Treaty Limits and its extensive historic claims to territorial waters have been subject of much academic debate and serious criticisms.The delimitation of Philippine territorial and maritime boundaries in conformity with international law necessitates the reform of the existing national legal, policy and administrative framework to resolve fundamental issues ofconflict between domestic legislation and international law. This paper, proceeding from both a national and an international legal perspective, aims to clarify the legal status of the Philippine Treaty Limits and territorial watersclaim in international law.
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