3,768 research outputs found
Feudalism: interpretative category or framework of life in the Medieval West?
As a  term of some utility in describing political, social and economic  institutions, 'feudalism' still has considerable currency beyond the field of  the medieval European West.l Nevertheless, its use by historians of the  medieval West suggests widespread disagreement over its essential  implications, and betrays a tendency to concentrate discussion no longer on  the term itself, or on a generalised notion of a 'feudal' society, but upon  the various discrete institutions, social practices and customs that make up  the medieval·· societies historians were once happy enough to call 'feudal'.  The present review of scholarly usage in regard to 'medieval feudalism'  contains two parts. In the first, I illustrate the various often overlapping  and competing meanings that historians since the turn of the century have  ascribed to the terms 'feudal' and 'feudalism', and in the second I offer  some comments on this diversity of opinion
Feudalism Revisited: a Tribute to S. N. Mukherjee
In  this tribute to the stimulus of Soumyen Mukherjee as a teaching colleague, I  am going to beg the reader's indulgence. Although I propose to make some  comments on the continuing utility of the concept of 'feudalism' for the  teacher of history, by way of comments on the reception and 'after-life' of  the volume Soumyen, I and Edmund Leach edited together in 1984-851, and on  the teaching venture in our department that accompanied it, I intend to be  fuller and plainer in my references to an esteemed colleague thanis, perhaps,  usual in a Festschrift. I think all who know Soumyen will realise that this  is the only appropriate way to go on this occasion
Inflation from D3-brane motion in the background of D5-branes
We study inflation arising from the motion of a BPS D3-brane in the
background of a stack of k parallel D5-branes. There are two scalar fields in
this set up-- (i) the radion field R, a real scalar field, and (ii) a complex
tachyonic scalar field chi living on the world volume of the open string
stretched between the D3 and D5 branes. We find that inflation is realized by
the potential of the radion field, which satisfies observational constraints
coming from the Cosmic Microwave Background. After the radion becomes of order
the string length scale l_s, the dynamics is governed by the potential of the
complex scalar field. Since this field has a standard kinematic term, reheating
can be successfully realized by the mechanism of tachyonic preheating with
spontaneous symmetry breaking.Comment: 10 pages, 4 figures. Minor clarifications and references added.
Version to appear in Phys. Rev.
Phosphorylation regulates human T-cell leukemia virus type 1 Rex function
Background: Human T-cell leukemia virus type 1 (HTLV-1) is a pathogenic complex
deltaretrovirus, which is the causative agent of adult T-cell leukemia/lymphoma (ATL) and HTLV-
1-associated myelopathy/tropical spastic paraparesis. In addition to the structural and enzymatic
viral gene products, HTLV-1 encodes the positive regulatory proteins Tax and Rex along with viral
accessory proteins. Tax and Rex proteins orchestrate the timely expression of viral genes
important in viral replication and cellular transformation. Rex is a nucleolar-localizing shuttling
protein that acts post-transcriptionally by binding and facilitating the export of the unspliced and
incompletely spliced viral mRNAs from the nucleus to the cytoplasm. HTLV-1 Rex (Rex-1) is a
phosphoprotein and general protein kinase inhibition correlates with reduced function. Therefore,
it has been proposed that Rex-1 function may be regulated through site-specific phosphorylation.
Results: We conducted a phosphoryl mapping of Rex-1 over-expressed in transfected 293 T cells
using a combination of affinity purification and liquid chromatography tandem mass spectrometry.
We achieved 100% physical coverage of the Rex-1 polypeptide and identified five novel
phosphorylation sites at Thr-22, Ser-36, Thr-37, Ser-97, and Ser-106. We also confirmed evidence
of two previously identified residues, Ser-70 and Thr-174, but found no evidence of
phosphorylation at Ser-177. The functional significance of these phosphorylation events was
evaluated using a Rex reporter assay and site-directed mutational analysis. Our results indicate that
phosphorylation at Ser-97 and Thr-174 is critical for Rex-1 function.
Conclusion: We have mapped completely the site-specific phosphorylation of Rex-1 identifying a
total of seven residues; Thr-22, Ser-36, Thr-37, Ser-70, Ser-97, Ser-106, and Thr-174. Overall, this
work is the first to completely map the phosphorylation sites in Rex-1 and provides important
insight into the regulation of Rex-1 function
Combined cooling and bio-treatment of beet sugar factory condenser water effluent
Submitted to Office of Water Resources Research, U.S. Department of Interior.Bibliography: pages 76-78.OWRR project no. A-008-COLO under agreement no. 14-31-0001-3006
Sequence-Specific β-Peptide Synthesis by a Rotaxane-Based Molecular Machine
We report on the synthesis and operation of a three-barrier, rotaxane-based, artificial molecular machine capable of sequence-specific β-homo (β3) peptide synthesis. The machine utilizes nonproteinogenic β3-amino acids, a class of amino acids not generally accepted by the ribosome, particularly consecutively. Successful operation of the machine via native chemical ligation (NCL) demonstrates that even challenging 15- and 19-membered ligation transition states are suitable for information translation using this artificial molecular machine. The peptide-bond-forming catalyst region can be removed from the transcribed peptide by peptidases, artificial and biomachines working in concert to generate a product that cannot be made by either machine alone
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