1,227 research outputs found
Pionic Content of Rho-N-N and Rho-N-Delta Vertex Functions
The dynamical content of rho-N-N and rho-N-Delta vertex functions is studied
with a mesonic model. A set of coupled integral equations satisfied by these
vertex functions were solved self-consistently. These soulutions indicate that
the dominant mesonic content arises from di-pion dynamics. With the
experimentally determined pion-baryon-baryon coupling constants and ranges as
input, the model predicts a g_{\rho NN} that agrees with the
meson-exchange-potential results. On the other hand, it predicts a smaller
f_{\rho N\Delta} and much softer form factors. Implications of the findings on
the use of phenomenological coupling constants in nuclear reaction studies are
discussed.Comment: 9 pages, 2 figures will be furnished upon request; LA-UR-94-126
Truth Table Invariant Cylindrical Algebraic Decomposition by Regular Chains
A new algorithm to compute cylindrical algebraic decompositions (CADs) is
presented, building on two recent advances. Firstly, the output is truth table
invariant (a TTICAD) meaning given formulae have constant truth value on each
cell of the decomposition. Secondly, the computation uses regular chains theory
to first build a cylindrical decomposition of complex space (CCD) incrementally
by polynomial. Significant modification of the regular chains technology was
used to achieve the more sophisticated invariance criteria. Experimental
results on an implementation in the RegularChains Library for Maple verify that
combining these advances gives an algorithm superior to its individual
components and competitive with the state of the art
Relationship Between Tissue Zinc Levels and Maturity Period of Field Beans
Most bean varieties (Phaseolus vulgaris) are susceptible
to zinc deficiency and, if grown where
zinc deficiency occurs, are invariably listed among
those crops with the greatest need for zinc fertilization
(1, 2, 3, 4). Bean plants with mild to moderate zinc deficiency
symptoms early in the growing season may
recover and produce essentially a normal yield. However,
as several individuals have observed (1, 2, 3)
this early-season zinc deficiency invariably results in
delayed maturity. This is a critical factor in geographical
areas where beans may be damaged by fall
rains or early frost.
The research reported here establishes quantitative
relationships between the zinc level in bean tissues
and the number of days required for maturation. The
results support previous observations of delayed maturity
when bean plants have inadequate zinc during
early growth
Randomized trial in postprandial functional dyspepsia: reassurance and diagnostic explanation with or without traditional dietary advice
Background
Almost 80% of individuals with functional dyspepsia experience meal-related symptoms and are diagnosed with postprandial distress syndrome (PDS). However, studies evaluating dietary modifications in PDS are sparse. We performed a single-center randomized trial comparing reassurance and diagnostic explanation (RADE) with or without traditional dietary advice (TDA) in PDS.
Methods
Following a normal upper gastrointestinal endoscopy, individuals with PDS were randomized to a leaflet providing RADE ± TDA; the latter recommending small, regular meals and reducing the intake of caffeine/alcohol/fizzy drinks and high-fat/processed/spicy foods. Questionnaires were completed over 4 weeks, including self-reported adequate relief of dyspeptic symptoms, and the validated Leuven Postprandial Distress Scale (LPDS), Gastrointestinal Symptom Rating Scale, and Nepean Dyspepsia Index for quality of life. The primary endpoint(s) to define clinical response were (i) ≥50% adequate relief of dyspeptic symptoms and (ii) >0.5-point reduction in the PDS subscale of the LPDS (calculated as the mean scores for early satiety, postprandial fullness, and upper abdominal bloating).
Key Results
Of the 53 patients with PDS, 27 were assigned RADE-alone and 26 to additional TDA. Baseline characteristics were similar between groups, with a mean age of 39 years, 70% female, 83% white British, and coexistent irritable bowel syndrome in 66%. The primary endpoints of (i) adequate relief of dyspeptic symptoms were met by 33% (n = 9) assigned RADE-alone versus 39% (n = 10) with TDA; p-value = 0.70, while (ii) a reduction of >0.5 points in the PDS subscale was met by 37% (n = 10) assigned RADE-alone versus 27% (n = 7) with TDA; p-value = 0.43. Response rates did not differ according to irritable bowel syndrome status. There were no significant between-group changes in the gastrointestinal symptom rating scale and dyspepsia quality of life.
Conclusions & Inferences
This study of predominantly white British patients with PDS found the addition of TDA did not lead to significantly greater symptom reduction compared with RADE alone. Alternate dietary strategies should be explored in this cohort
Scanning electron microscopy image representativeness: morphological data on nanoparticles.
A sample of a nanomaterial contains a distribution of nanoparticles of various shapes and/or sizes. A scanning electron microscopy image of such a sample often captures only a fragment of the morphological variety present in the sample. In order to quantitatively analyse the sample using scanning electron microscope digital images, and, in particular, to derive numerical representations of the sample morphology, image content has to be assessed. In this work, we present a framework for extracting morphological information contained in scanning electron microscopy images using computer vision algorithms, and for converting them into numerical particle descriptors. We explore the concept of image representativeness and provide a set of protocols for selecting optimal scanning electron microscopy images as well as determining the smallest representative image set for each of the morphological features. We demonstrate the practical aspects of our methodology by investigating tricalcium phosphate, Ca3 (PO4 )2 , and calcium hydroxyphosphate, Ca5 (PO4 )3 (OH), both naturally occurring minerals with a wide range of biomedical applications
Kinematically Complete Measurements of p+p → p+n+(pi+) Near Threshold
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Tensor Polarized Deuteron Capture by the Hydrogen Isotopes
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
- …