11,356 research outputs found
Rare, Threatened and Endangered Vascular Plants in Oregon: An Interim Report
This report on rare, threatened and endangered vascular plants in Oregon is a basic document in the process of inventorying the state\u27s natural areas * Prerequisite to the orderly establishment of natural preserves for research and conservation in Oregon are (1) a classification of the ecological types, and (2) a listing of the special organisms, which should be represented in a comprehensive system of designated natural areas. The necessary ecological classification was published in the U.S. Forest Service Pacific Northwest Forest and Range Experiment Station document, Research Natural Area Needs in the Pacific Northwest, by Dyrness et al. (1975). This valuable reference also provided lists of vascular plants of special interest in each major physiographic province, based on early work by Chambers and Siddall. Under the direction of the Oregon Rare and Endangered Plant Species Taskforce, work has actively continued to expand and perfect the list of vascular plant species, to serve the needs of land management and natural area planning in Oregon, and of many other governmental and private activities.
Studies of rare and endangered plants in Oregon have involved a unique coalition of professional and amateur botanists, who have systematically gathered data on the distribution, abundance, habitat, and ecological requirements of some 700 native species. Coordination and leadership have come from the Oregon Rare and Endangered Plant Species Taskforce, and specifically from the Taskforce chairman, Jean L. Siddall. The Natural Area Preserves Advisory Committee has long recognized the significance of this effort and has encouraged the Taskforce\u27s goal of assembling a list of rare, threatened and endangered plant species for the State of Oregon. In August,1979, it was decided to support the publication of an interim report, summarizing the present status of all the plants under review by the Taskforce. This list will serve as a working document for the many individuals and organizations, both public and private, needing information on the rare plants in Oregon. This list will be particularly useful to the Natural Heritage Advisory Council (replacing the Natural Area Preserves Advisory Committee) as it develops the Natural Heritage Plan required by Oregon statute. Ultimately, a detailed Oregon List of Rare, Threatened and Endangered Plants will be produced. This current interim report is a timely step toward this goal
Connected and disconnected quark contributions to hadron spin
By introducing an external spin operator to the fermion action, the quark
spin fractions of hadrons are determined from the linear response of the hadron
energies using the Feynman-Hellmann (FH) theorem. At our SU(3)-flavour
symmetric point, we find that the connected quark spin fractions are
universally in the range 55-70\% for vector mesons and octet and decuplet
baryons. There is an indication that the amount of spin suppression is quite
sensitive to the strength of SU(3) breaking. We also present first preliminary
results applying the FH technique to calculations of quark-line disconnected
contributions to hadronic matrix elements of axial and tensor operators. At the
SU(3)-flavour symmetric point we find a small negative contribution to the
nucleon spin from disconnected quark diagrams, while the corresponding tensor
matrix elements are consistent with zero.Comment: 7 pages, 5 figures, 32nd International Symposium on Lattice Field
Theor
Beyond expectations: the physiological basis of sensory-enhancement of satiety
Background/Objectives: Consumption of high-energy beverages has been implicated as a risk factor for weight gain, yet why nutrients ingested as beverages fail to generate adequate satiety remains unclear. In general consumers do not expect drinks to be satiating, but drinks generate greater satiety when their sensory characteristics imply they may be filling. These findings challenge traditional bottom-up models of how gut-based satiety signals modify behavior to suggest that beliefs at the point of ingestion modify gut-based satiety signaling.
Subjects/Methods: Healthy volunteers (n = 23) consumed four different beverages, combining an overt sensory manipulation (thin, Low Sensory, LS, or thicker and more creamy, Enhanced Sensory, ES) and covert nutrient manipulation (low energy, LE, 78kcal; high energy, HE, 267 kcal) on different days. Effects on satiety were assessed through rated appetite and levels of glucose, insulin, pancreatic polypeptide (PP) and cholesystokinin (CCK) recorded periodically over 90 minutes, and through intake at an ad libitum test lunch.
Results: Intake at the test lunch and rated appetite were both altered by both the sensory and nutrient manipulations, with lowest intake and greatest suppression of hunger post-drink in the ESHE condition. Insulin increased more after HE than LE drinks, and after ES than LS drinks, while PP levels were higher after ES than LS versions. CCK levels only increased after the ESHE drink.
Conclusions: These data confirm acute sensitivity of satiety after consuming a drink both to the sensory characteristics and nutrient content of the drink, and suggest that this may be at least in part due to top-down modulation of release of satiety-related gut hormones
Applications of the Feynman-Hellmann theorem in hadron structure
The Feynman-Hellmann (FH) relation offers an alternative way of accessing
hadronic matrix elements through artificial modifications to the QCD
Lagrangian. In particular, a FH-motivated method provides a new approach to
calculations of disconnected contributions to matrix elements and high-momentum
nucleon and pion form factors. Here we present results for the total nucleon
axial charge, including a statistically significant non-negative total
disconnected quark contribution of around at an unphysically heavy pion
mass. Extending the FH relation to finite-momentum transfers, we also present
calculations of the pion and nucleon electromagnetic form factors up to
momentum transfers of around 7-8 GeV. Results for the nucleon are not able
to confirm the existence of a sign change for the ratio , but
suggest that future calculations at lighter pion masses will provide
fascinating insight into this behaviour at large momentum transfers
Disconnected contributions to the spin of the nucleon
The spin decomposition of the proton is a long-standing topic of much
interest in hadronic physics. Lattice QCD has had much success in calculating
the connected contributions to the quark spin. However, complete calculations,
which necessarily involve gluonic and strange-quark contributions, still
present some challenges. These "disconnected" contributions typically involve
small signals hidden against large statistical backgrounds and rely on
computationally intensive stochastic techniques. In this work we demonstrate
how a Feynman-Hellmann approach may be used to calculate such quantities, by
measuring shifts in the proton energy arising from artificial modifications to
the QCD action. We find a statistically significant non-zero result for the
disconnected quark spin contribution to the proton of about -5% at a pion mass
of 470 MeV
Single-Index Model-Assisted Estimation In Survey Sampling
A model-assisted semiparametric method of estimating finite population totals
is investigated to improve the precision of survey estimators by incorporating
multivariate auxiliary information. The proposed superpopulation model is a
single-index model which has proven to be a simple and efficient semiparametric
tool in multivariate regression. A class of estimators based on polynomial
spline regression is proposed. These estimators are robust against deviation
from single-index models. Under standard design conditions, the proposed
estimators are asymptotically design-unbiased, consistent and asymptotically
normal. An iterative optimization routine is provided that is sufficiently fast
for users to analyze large and complex survey data within seconds. The proposed
method has been applied to simulated datasets and MU281 dataset, which have
provided strong evidence that corroborates with the asymptotic theory.Comment: 30 page
A Feynman-Hellmann approach to the spin structure of hadrons
We perform a Nf = 2 + 1 lattice QCD simulation to determine the quark spin
fractions of hadrons using the Feynman-Hellmann theorem. By introducing an
external spin operator to the fermion action, the matrix elements relevant for
quark spin fractions are extracted from the linear response of the hadron
energies. Simulations indicate that the Feynman-Hellmann method offers
statistical precision that is comparable to the standard three-point function
approach, with the added benefit that it is less susceptible to excited state
contamination. This suggests that the Feynman-Hellmann technique offers a
promising alternative for calculations of quark line disconnected contributions
to hadronic matrix elements. At the SU(3)-flavour symmetry point, we find that
the connected quark spin fractions are universally in the range 55-70% for
vector mesons and octet and decuplet baryons. There is an indication that the
amount of spin suppression is quite sensitive to the strength of SU(3)
breaking.Comment: 13 pages, 7 figure
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