52 research outputs found
Seasonal forage quality of rangelands across Kansas
The K-State Research and Extension
Forage Task Force surveyed Kansas
rangelands during the course of seasonal
changes to enable producers and managers to
better estimate the feed value of their pasture
forage during particular times of the year.
Kansas’ two distinct rangeland vegetation
types, shortgrass and tallgrass prairie, were
evaluated. Forage samples were collected
monthly from two rangeland sites in each of
10 Kansas counties. Tallgrass vegetation
was lowest in acid detergent fiber (ADF) and
greatest in crude protein (CP) from May to
July, and rapidly increased in ADF and
declined in CP the rest of the season.
Shortgrass vegetation was also lower in ADF
and greater in CP from May to July, but
changed less from early summer to the
winter than did tallgrass vegetation.
Degradable intake protein (DIP) was greatest
for tallgrass vegetation in May. Otherwise
DIP was similar between tallgrass and
shortgrass except in February and March
when shortgrass had greater DIP. DIP was
greatest in May and June for both vegetation
types and gradually declined from June to
December. Undegradable intake protein
(UIP) values were greater for tallgrass
vegetation than for shortgrass vegetation
from May through July, but all other months
were similar. Seasonal forage quality is
different between and within rangeland
vegetation types, and identification of
dominant vegetation is a key determinant in
choosing appropriate animal nutritional
management strategies
Spinor-Vector Duality in Heterotic String Orbifolds
The three generation heterotic-string models in the free fermionic
formulation are among the most realistic string vacua constructed to date,
which motivated their detailed investigation. The classification of free
fermion heterotic string vacua has revealed a duality under the exchange of
spinor and vector representations of the SO(10) GUT symmetry over the space of
models. We demonstrate the existence of the spinor-vector duality using
orbifold techniques, and elaborate on the relation of these vacua to free
fermionic models.Comment: 20 pages. v2 minor corrections. Version to appear on JHEP. v3
misprints correcte
Discrete R-symmetries and Anomaly Universality in Heterotic Orbifolds
We study discrete R-symmetries, which appear in 4D low energy effective field
theory derived from hetetoric orbifold models. We derive the R-symmetries
directly from geometrical symmetries of orbifolds. In particular, we obtain the
corresponding R-charges by requiring that the couplings be invariant under
these symmetries. This allows for a more general treatment than the explicit
computations of correlation functions made previously by the authors, including
models with discrete Wilson lines, and orbifold symmetries beyond
plane-by-plane rotational invariance. Surprisingly, for the cases covered by
earlier explicit computations, the R-charges differ from the previous result.
We study the anomalies associated with these R-symmetries, and comment on the
results.Comment: 21 pages, 2 figures. Minor changes, typos corrected. Matches JHEP
published versio
A perfect match of MSSM-like orbifold and resolution models via anomalies
Compactification of the heterotic string on toroidal orbifolds is a promising
set-up for the construction of realistic unified models of particle physics.
The target space dynamics of such models, however, drives them slightly away
from the orbifold point in moduli space. This resolves curvature singularities,
but makes the string computations very difficult. On these smooth manifolds we
have to rely on an effective supergravity approximation in the large volume
limit. By comparing an orbifold example with its blow-up version, we try to
transfer the computational power of the orbifold to the smooth manifold. Using
local properties, we establish a perfect map of the the chiral spectra as well
as the (local) anomalies of these models. A key element in this discussion is
the Green-Schwarz anomaly polynomial. It allows us to identify those
redefinitions of chiral fields and localized axions in the blow-up process
which are relevant for the interactions (such as Yukawa-couplings) in the model
on the smooth space.Comment: 2+35 pages, 1 figur
Forming conjectures within a spreadsheet environment
This paper is concerned with the use of spreadsheets within mathematical investigational tasks. Considering the learning of both children and pre-service teaching students, it examines how mathematical phenomena can be seen as a function of the pedagogical media through which they are encountered. In particular, it shows how pedagogical apparatus influence patterns of social interaction, and how this interaction shapes the mathematical ideas that are engaged with. Notions of conjecture, along with the particular faculty of the spreadsheet setting, are considered with regard to the facilitation of mathematical thinking. Employing an interpretive perspective, a key focus is on how alternative pedagogical media and associated discursive networks influence the way that students form and test informal conjectures
Maternal investment, sibling competition, and offspring survival with increasing litter size and parity in pigs (Sus scrofa)
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