1,720 research outputs found
Leaf Size and Leaf Area Index in Fagus sylvatica Forests: Competing Effects of Precipitation, Temperature, and Nitrogen Availability
Plants across diverse biomes tend to produce smaller leaves and a reduced total leaf area when exposed to drought. For mature trees of a single species, however, the leaf area-water supply relationship is not well understood. We tested the paradigm of leaf area reduction upon drought by a transect study with 14 mature Fagus sylvatica forests along a steep precipitation gradient (970-520 mm y(-1)) by applying two independent methods of leaf size determination. Contrary to expectation, average leaf size in dry stands (520-550 mm y(-1)) was about 40% larger and SLA was higher than in moist stands (910-970 mm y(-1)). As a result of increased leaf sizes, leaf area index significantly increased from the high- to the low-precipitation stands. Multiple regression analyses suggested that average leaf size was primarily controlled by temperature, whereas the influence of soil moisture and soil C/N ratio was low. Summer rainfall of the preceding year was the most significant predictor of total leaf number. We assume that leaf expansion of beech was independent of water supply, because it takes place in May with ample soil water reserves along the entire transect. In contrast, bud formation, which determines total leaf number, occurs in mid-summer, when droughts are severest. We conclude that leaf expansion and stand leaf area of beech along this precipitation gradient are not a simple function of water availability, but are controlled by several abiotic factors including spring temperature and possibly also nitrogen supply, which both tend to increase toward drier sites, thus overlaying any negative effect of water shortage on leaf development.Deutsche Bundesstiftung Umwel
Neutron Drops and Skyrme Energy-Density Functionals
The J=0 ground state of a drop of 8 neutrons and the lowest
1/2 and 3/2 states of 7-neutron drops, all in an external well, are
computed accurately with variational and Green's function Monte Carlo methods
for a Hamiltonian containing the Argonne two-nucleon and Urbana IX
three-nucleon potentials. These states are also calculated using Skyrme-type
energy-density functionals. Commonly used functionals overestimate the central
density of these drops and the spin-orbit splitting of 7-neutron drops.
Improvements in the functionals are suggested
Many-body effects in 16O(e,e'p)
Effects of nucleon-nucleon correlations on exclusive reactions on
closed-shell nuclei leading to single-hole states are studied using
( MeV, ) as an example. The quasi-hole wave
function, calculated from the overlap of translationally invariant many-body
variational wave functions containing realistic spatial, spin and isospin
correlations, seems to describe the initial state of the struck proton
accurately inside the nucleus, however it is too large at the surface. The
effect of short-range correlations on the final state is found to be largely
cancelled by the increase in the transparency for the struck proton. It is
estimated that the values of the spectroscopic factors obtained with the DWIA
may increase by a few percent due to correlation effects in the final state.Comment: 21 Pages, PHY-7849-TH-9
Systematic study of Coulomb distortion effects in exclusive (e,e'p) reactions
A technique to deal with Coulomb electron distortions in the analysis of
(e,e'p) reactions is presented. Thereby, no approximations are made. The
suggested technique relies on a partial-wave expansion of the electron wave
functions and a multipole decomposition of the electron and nuclear current in
momentum space. In that way, we succeed in keeping the computational times
within reasonable limits. This theoretical framework is used to calculate the
quasielastic (e,e'p) reduced cross sections for proton knockout from the
valence shells in O, Ca, Zr and Pb. The
final-state interaction of the ejected proton with the residual nucleus is
treated within an optical potential model. The role of electron distortion on
the extracted spectroscopic factors is discussed.Comment: 45 pages, 10 encapsulated postscript figures, Revtex, uses epsfig.sty
and fancybox.sty, to be published in Physical Review
Screening of Dementia in Portuguese Primary Care: Methodology, Assessment Tools, and Main Results
The objectives of this article are as follows: (1) to describe the assessment protocol used to outline people with probable dementia in Primary Health Care; (2) to show the methodological design and procedure to obtain a representative sample of patients with probable dementia; and (3) to report the main characteristics of the sample collected in the context of the study “Characteristics and needs of people with probable dementia.” The study protocol was based on the “Community Assessment of Risk and Treatment Strategies (CARTS) Program” and is composed by a set of instruments that allow the assessment of older adults with probable dementia in several areas (health, psychological, functionality, and other). Descriptive analysis was used to characterize the final sample (n = 436). The study protocol as well as the methodological procedure to obtain the referral of research participants and data collection on the condition of people with probable dementia in Primary Health Care proved to be a valuable tool to obtain a sample of patients distributed by the full range of probable dementia in a large geographical area. Results may allocate the design of care pathways for old people with cognitive disorders to prevent, delay impairment, and/or optimize quality of life of patients
Ground state correlations and mean-field in O
We use the coupled cluster expansion ( method) to generate the
complete ground state correlations due to the NN interaction. Part of this
procedure is the calculation of the two-body G matrix inside the nucleus in
which it is being used. This formalism is being applied to in a
configuration space of 50 . The resulting ground state wave
function is used to calculate the binding energy and one- and two-body
densities for the ground state of .Comment: 9 pages, 9 figures, LaTe
Avaliação da satisfação e importância atribuída aos serviços prestados na área da saúde mental
Com o objectivo de avaliar o grau de satisfação e importância atribuída aos serviços prestados
na consulta na área da saúde mental e identificar as relações entre as variáveis demográficas e o
grau de satisfação do utente foi realizado um estudo descritivo transversal, numa amostra de
305 utentes.
Com a aplicação do questionário verificamos que a satisfação conjugada com a importância
fornece-nos informação valiosa permitindo identificar pontos fortes, oportunidades ou
necessidades de melhoria dos serviços. Neste estudo verificamos que os utentes encontram-se
satisfeitos com os serviços prestados e consideram-nos importantes.
Na análise bivariada, encontramos relação entre a satisfação e escolaridade.In order to evaluate the degree of satisfaction and importance attached to services provided in
the consultation on mental health and identify relationships between demographic variables
and the degree of user satisfaction was conducted a cross-sectional survey in a sample of 305
users. With the application of the questionnaire we found that satisfaction coupled with the
importance provides us with valuable information allowing identifying strengths, opportunities
or needs for improved services. In this study we found that users are satisfied with the services
provided and consider them important.
In bivariate analysis, we found the relationship between satisfaction and education level
Kandungan, Resorpsi N dan P Serta Specifi C Leaf Area Daun Kakao (Theobroma Cacao L.) pada Cekaman Kekeringan
Plant nutrient absorptions depend on their environment and plants' stage of development. Beside from soil, nutrient absorption also proceed through resorption in leaves. The resorption efficiency varies based on types of habitat. Drought stress also influences the efficiency of nutrient resorption, growth rate, and plant development. The purpose of this research was to study the change of nitrogen (N) and phosphorus (P) content and leaf resorption value of N and P, and specific leaf area of 6-years old cacao grown under drought stress. Research was carried out in a cacao plantation with 7-years old Gliricidia sepium Jacq. as shading trees. The results showed that drought stress with Troughfall Displacement Experiment (TDE) system did not affect the content and resorption level of N and P of cacao leaves. However, N resorption of cacao leaves tended to increase while P resorption decreased. Cacao plants experienced drought stress have the ability to resorp leaf N for 46.64-50.63%, leaf P for 47.98-58.40%, whereas, the control plants had the leaf N resorption of 45.05-52.97%, and leaf P resorption of 36.64-44.10%. Drought stress for 13 months on 6-years old cacao did not affect specifi c leaf area
Wavelet Based Fractal Analysis of Airborne Pollen
The most abundant biological particles in the atmosphere are pollen grains
and spores. Self protection of pollen allergy is possible through the
information of future pollen contents in the air. In spite of the importance of
airborne pol len concentration forecasting, it has not been possible to predict
the pollen concentrations with great accuracy, and about 25% of the daily
pollen forecasts have resulted in failures. Previous analysis of the dynamic
characteristics of atmospheric pollen time series indicate that the system can
be described by a low dimensional chaotic map. We apply the wavelet transform
to study the multifractal characteristics of an a irborne pollen time series.
We find the persistence behaviour associated to low pollen concentration values
and to the most rare events of highest pollen co ncentration values. The
information and the correlation dimensions correspond to a chaotic system
showing loss of information with time evolution.Comment: 11 pages, 7 figure
A Current Mode Detector Array for Gamma-Ray Asymmetry Measurements
We have built a CsI(Tl) gamma-ray detector array for the NPDGamma experiment
to search for a small parity-violating directional asymmetry in the angular
distribution of 2.2 MeV gamma-rays from the capture of polarized cold neutrons
by protons with a sensitivity of several ppb. The weak pion-nucleon coupling
constant can be determined from this asymmetry. The small size of the asymmetry
requires a high cold neutron flux, control of systematic errors at the ppb
level, and the use of current mode gamma-ray detection with vacuum photo diodes
and low-noise solid-state preamplifiers. The average detector photoelectron
yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in
the measurement is therefore dominated by the fluctuations in the number of
gamma rays absorbed in the detector (counting statistics) rather than the
intrinsic detector noise. The detectors were tested for noise performance,
sensitivity to magnetic fields, pedestal stability and cosmic background. False
asymmetries due to gain changes and electronic pickup in the detector system
were measured to be consistent with zero to an accuracy of in a few
hours. We report on the design, operating criteria, and the results of
measurements performed to test the detector array.Comment: 33 pages, 20 figures, 2 table
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