244 research outputs found
Bankfull Hydraulic Geometry of Streams Draining the Southwestern Appalachians of Tennessee
The purpose of this study was to examine the bankfull recurrence interval for streams draining the Southwestern Appalachians Level III Ecoregion 68 of Tennessee, develop bankfull discharge and hydraulic geometry relationships for streams within the ecoregion and compare those relationships to the Ridge and Valley of Virginia, West Virginia, and Maryland (Keaton et al., 2005) and the Piedmont and Blue Ridge of North Carolina (Harman et al., 1999; Harman et al., 2000). For this investigation, a repeatable, systematic process was developed to locate bankfull stage within the Southwestern Appalachians during the spring and summer of 2005. The intent was to develop regional curves of empirically derived hydraulic relationships for this ecoregion, but first it was necessary to correctly identify bankfull stage in the sample streams. Bankfull discharge was defined as the effective discharge or channel-forming flow. Stream surveys were conducted on 11 study reaches (7 had USGS gages for calibration of bankfull) of various sized drainages across the ecoregion. Recurrence intervals were calculated using log Person Type III flood frequency analysis. Results demonstrated an average bankfull recurrence interval of 1.31 years for the Southwestern Appalachians, which was comparable to other nearby physiographic regions.Regional curves illustrate hydraulic and geomorphic relationships such as discharge versus watershed area, channel width versus channel cross sectional area and many more such relationships. The principal benefits from regional curves are their assistance in validating channel dimensions, pattern and profile for stream restoration designs. The marked variance in geology, climate, topography, and watershed land-uses across physiographic provinces drives the need for developing regional curves for each specific physiographic province. Stream restoration designs in Tennessee rely on curves from other nearby physiographic regions. A comparison of the Southwestern Appalachians regional curves developed in this study to the Ridge and Valley and the Piedmont and Blue Ridge reveals distinctly different relationships. In the Southwestern Appalachians, bankfull discharge and associated cross sectional area were found to be of much greater magnitude than streams in the other two regions
The Structure of Conserved Charges in Open Spin Chains
We study the local conserved charges in integrable spin chains of the XYZ
type with nontrivial boundary conditions. The general structure of these
charges consists of a bulk part, whose density is identical to that of a
periodic chain, and a boundary part. In contrast with the periodic case, only
charges corresponding to interactions of even number of spins exist for the
open chain. Hence, there are half as many charges in the open case as in the
closed case. For the open spin-1/2 XY chain, we derive the explicit expressions
of all the charges. For the open spin-1/2 XXX chain, several lowest order
charges are presented and a general method of obtaining the boundary terms is
indicated. In contrast with the closed case, the XXX charges cannot be
described in terms of a Catalan tree pattern.Comment: 22 pages, harvmac.tex (minor clarifications and reference corrections
added
Charles W. Bolen Faculty Recital Series: Faculty Brass Quintet, October 14, 2021
Center for the Performing Arts
October 14, 2021
Thursday Evening
8:00 p.m
Charles W. Bolen Faculty Recital Series: Faculty Brass Quintet, October 14, 2021
Center for the Performing Arts
October 14, 2021
Thursday Evening
8:00 p.m
Molecular modeling of an antigenic complex between a viral peptide and a class I major histocompatibility glycoprotein
Computer simulation of the
conformations of short antigenic peptides (&lo
residues) either free or bound to their receptor,
the major histocompatibility complex (MHC)-
encoded glycoprotein H-2 Ld, was employed to
explain experimentally determined differences
in the antigenic activities within a set of related
peptides. Starting for each sequence from the
most probable conformations disclosed by a
pattern-recognition technique, several energyminimized
structures were subjected to molecular
dynamics simulations (MD) either in vacuo
or solvated by water molecules. Notably, antigenic
potencies were found to correlate to the
peptides propensity to form and maintain an
overall a-helical conformation through regular
i,i + 4 hydrogen bonds. Accordingly, less active
or inactive peptides showed a strong tendency
to form i,i+3 hydrogen bonds at their Nterminal
end. Experimental data documented
that the C-terminal residue is critical for interaction
of the peptide with H-2 Ld. This finding
could be satisfactorily explained by a 3-D
Q.S.A.R. analysis postulating interactions between
ligand and receptor by hydrophobic
forces. A 3-D model is proposed for the complex
between a high-affinity nonapeptide and the H-
2 Ld receptor. First, the H-2 Ld molecule was
built from X-ray coordinates of two homologous
proteins: HLA-A2 and HLA-Aw68, energyminimized
and studied by MD simulations. With
HLA-A2 as template, the only realistic simulation
was achieved for a solvated model with minor
deviations of the MD mean structure from
the X-ray conformation. Water simulation of the
H-2 Ld protein in complex with the antigenic
nonapeptide was then achieved with the template-
derived optimal parameters. The bound
peptide retains mainly its a-helical conformation
and binds to hydrophobic residues of H-2
Ld that correspond to highly polymorphic positions
of MHC proteins. The orientation of the
nonapeptide in the binding cleft is in accordance
with the experimentally determined distribution
of its MHC receptor-binding residues
(agretope residues). Thus, computer simulation was successfully employed to explain functional
data and predicts a-helical conformation
for the bound peptid
Sound archaeology: terminology, Palaeolithic cave art and the soundscape
This article is focused on the ways that terminology describing the study of music and sound within archaeology has changed over time, and how this reflects developing methodologies, exploring the expectations and issues raised by the use of differing kinds of language to define and describe such work. It begins with a discussion of music archaeology, addressing the problems of using the term âmusicâ in an archaeological context. It continues with an examination of archaeoacoustics and acoustics, and an emphasis on sound rather than music. This leads on to a study of sound archaeology and soundscapes, pointing out that it is important to consider the complete acoustic ecology of an archaeological site, in order to identify its affordances, those possibilities offered by invariant acoustic properties. Using a case study from northern Spain, the paper suggests that all of these methodological approaches have merit, and that a project benefits from their integration
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