437 research outputs found
Pollination Studies with Native Minnesota Pyrola and Moneses Species
The closely related ericaceous ericaceous genera, Pyrola L. and Monese Salisb. ex. Gray, are common throughout the world in coniferous woods of north temperate areas. Characteristically they are small herbaceous plants with basal evergreen leaves and decorative inflorescences of green, white or pink flowers appearing in the early summer. In Minnesota there are five species of Pyrola-P. asarifolia Michx., P. elliptica Nutt., P. rotundifolia L., P. secunda L., and P. virens Schweigger. There is also the one species of Moneses, M. uniffora (L.) Gray. All these occur together in abundant quantities and bloom at approximately the same time. Consequently they are suitable as experimental material for a field problem. The aspects chosen for investigation were those of interspecific hybridization and pollination mechanisms
Fluctuations and Rheology in Active Bacterial Suspensions
We probe nonequilibrium properties of an active bacterial bath through measurements of correlations of passive tracer particles and the response function of a driven, optically trapped tracer. These measurements demonstrate violation of the fluctuation-dissipation theorem and enable us to extract the power spectrum of the active stress fluctuations. In some cases, we observe 1/âw scaling in the noise spectrum which we show can be derived from a theoretical model incorporating coupled stress, orientation, and concentration fluctuations of the bacteria
Determination of the apparent and true ileal amino acid digestibility and digestible and metabolizable energy of specialty protein sources intended for nursery pig diets
Two experiments were conducted to determine
the apparent and true-ileal amino acid
digestibility, and to determine the digestible energy and metabolizable energy values of rice protein concentrate, salmon protein hydrolysate, whey protein concentrate, and spray-dried animal plasma. The experimental ingredients were analyzed for essential and non-essential amino acids and crude protein so diets could be formulated. In Exp.1, pigs were fed each diet, and ileal digesta was collected and analyzed. Apparent and true digestibilities
were then calculated. In Exp. 2, pigs were fed each diet and feces were collected, weighed, and sampled. Lab analyses were conducted for the determination of gross energy (GE) and digestible energy (DE). Then ME values were determined by calculation from the DE and CP concentrations of experimental diets. In Exp. 1, TID lysine, methionine, and threonine values were 86.6, 69.0, and 78.9% for rice protein concentrate; 89.7, 88.7, and 80.2% for salmon protein hydrolysate; 95.7, 93.9, and
88.4% for whey protein concentrate; and 95.4,
93.5, and 92.2% for spray-dried animal plasma, respectively. In Exp. 2, DE values for rice protein concentrate, salmon protein hydrolysate, whey protein concentrate, and
spray-dried animal plasma were 2143, 1893, 2245, and 2062 kcal/lb, respectively. The ME
values that were determined for the protein
products were 1917, 1598, 1974, and 1805 kcal/lb, respectively
Effects of paylean (ractopamineâ HCl) on finishing pig growth and variation
A total of 336 pigs were used in a 21-day
trial to determine the effect of Paylean (9.0
g/ton Ractopamine·HCl) on finishing pig
growth and variation. Pigs were allotted based on weight so that all pens had the same
initial weight and degree of variation within
the pen. Pigs fed Paylean had greater ADG and better feed efficiency than control-fed
pigs (P<0.05). However, no differences in
pen coefficient of variation were observed
(P>0.70). The results suggest that adding
Paylean to the diet improves finishing pig
growth performance but does not affect
weight variation within the pen
Evaluation of hemicellÂź on growth performance of late nursery pigs
A total of 276 pigs (initially 21.9 lb) was
used to determine the effects of added HemicellÂź on growth performance. HemicellÂź is a patented fermentation product of Bacillus lentus. The active ingredient in the fermentation product is ÎČ-mannanase. However, other enzymes such as amylase, xylanase, cellulases, and α-galactosidase also are present. It is claimed that HemicellÂź degrades ÎČ-mannan in feed, thus, removing its effects as an antinutritive factor in swine diets. Dietary treatments
were arranged as a 2 x 3 factorial, with
or without 0.05% HemicellÂź, in diets with 3
levels of energy density (1,388, 1,488, 1,588
ME, kcal/lb). The 100 kcal increments were achieved by the addition of wheat bran or soy
oil to a corn-soybean meal based diet. The addition of HemicellÂź to the diets, regardless of energy level, did not lead to an improvement in growth performance in these late nursery pigs. Increasing energy density of the diet, however, resulted in an improved ADG and F/G
D-term cosmic strings from N=2 Supergravity
We describe new half-BPS cosmic string solutions in N=2, d=4 supergravity
coupled to one vector multiplet and one hypermultiplet. They are closely
related to D-term strings in N=1 supergravity. Fields of the N=2 theory that
are frozen in the solution contribute to the triplet moment map of the
quaternionic isometries and leave their trace in N=1 as a constant
Fayet-Iliopoulos term. The choice of U(1) gauging and of special geometry are
crucial. The construction gives rise to a non-minimal Kaehler potential and can
be generalized to higher dimensional quaternionic-Kaehler manifolds.Comment: 37 pages, LaTeX, v2: minor corrections, references added, version to
be published in JHE
D-instantons and Closed String Tachyons in Misner Space
We investigate closed string tachyon condensation in Misner space, a toy
model for big bang universe. In Misner space, we are able to condense tachyonic
modes of closed strings in the twisted sectors, which is supposed to remove the
big bang singularity. In order to examine this, we utilize D-instanton as a
probe. First, we study general properties of D-instanton by constructing
boundary state and effective action. Then, resorting to these, we are able to
show that tachyon condensation actually deforms the geometry such that the
singularity becomes milder.Comment: 24 pages, 1 figure, minor change
D-branes in a Big Bang/Big Crunch Universe: Nappi-Witten Gauged WZW Model
We study D-branes in the Nappi-Witten model, which is a gauged WZW model
based on (SL(2,R) x SU(2)) / (U(1) x U(1)). The model describes a four
dimensional space-time consisting of cosmological regions with big bang/big
crunch singularities and static regions with closed time-like curves. The aim
of this paper is to investigate by D-brane probes whether there are pathologies
associated with the cosmological singularities and the closed time-like curves.
We first classify D-branes in a group theoretical way, and then examine DBI
actions for effective theories on the D-branes. In particular, we show that
D-brane metric from the DBI action does not include singularities, and wave
functions on the D-branes are well behaved even in the presence of closed
time-like curves.Comment: 50 pages, 2 figures, minor change
Cornerstones of Sampling of Operator Theory
This paper reviews some results on the identifiability of classes of
operators whose Kohn-Nirenberg symbols are band-limited (called band-limited
operators), which we refer to as sampling of operators. We trace the motivation
and history of the subject back to the original work of the third-named author
in the late 1950s and early 1960s, and to the innovations in spread-spectrum
communications that preceded that work. We give a brief overview of the NOMAC
(Noise Modulation and Correlation) and Rake receivers, which were early
implementations of spread-spectrum multi-path wireless communication systems.
We examine in detail the original proof of the third-named author
characterizing identifiability of channels in terms of the maximum time and
Doppler spread of the channel, and do the same for the subsequent
generalization of that work by Bello.
The mathematical limitations inherent in the proofs of Bello and the third
author are removed by using mathematical tools unavailable at the time. We
survey more recent advances in sampling of operators and discuss the
implications of the use of periodically-weighted delta-trains as identifiers
for operator classes that satisfy Bello's criterion for identifiability,
leading to new insights into the theory of finite-dimensional Gabor systems. We
present novel results on operator sampling in higher dimensions, and review
implications and generalizations of the results to stochastic operators, MIMO
systems, and operators with unknown spreading domains
Reading Ronaldo: contingent whiteness in the football media
Ever since his introduction to the first-Â-team at Manchester United FC, Cristiano Ronaldo Dos Santos Aveiro has been recognised as one of the footballing worldâs most stand-Â-out football players. In turn, Ronaldo has drawn the attention of scholars working across a number of disciplines. While sports economists and sociologists of sport, amongst others, have contributed to a growing literature about Ronaldo and the social implications of his on and off-Â-field behaviour, few critical analyses have considered the racialised aspects of Ronaldoâs representations, or how audiences make sense of his racialised or ethnic identity. Using images of Ronaldo, which we presented to and discussed with self-Â-identified physically active white British men, we explore what it is representations and audience interpretations of Ronaldo reveal about the complexities of white male identity formation. We do this to understand better how white male identities can be read and interpreted through and in the context of football. Facilitated by our conception of contingent whiteness, we argue that white British menâs interpretations of Ronaldoâs whiteness are inextricably linked to discourses of âraceâ, masculinities and football
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