673 research outputs found
Immunohistochemical localization of glucagon and pancreatic polypeptide on rat endocrine pancreas: coexistence in rat islet cells
We used immunofluorescence double staining method to investigate the cellular localization of glucagon and pancreatic polypeptide (PP) in rat pancreatic islets. The results showed that both A-cells (glucagon-secreting cells) and PP-cells (PP-secreting cells) were located in the periphery of the islets. However, A-cells and PP-cells had a different regional distribution. Most of A-cells were located in the splenic lobe but a few of them were in the duodenal lobe of the pancreas. In contrast, the majority of PP-cells were found in the duodenal lobe and a few of them were in the splenic lobe of the pancreas. Furthermore, we found that 67.74% A-cells had PP immunoreactivity, 70.92% PP-cells contained glucagon immunoreactivity with immunofluorescence double staining. Our data support the concept of a common precursor stem cell for pancreatic hormone-producing cells
Mechanical Properties of Thermoplastic Variable-Angle Composite Laminations for Conical Shells
Thermoplastic composite automated fiber placement
technology, as one of the extreme manufacturing
technologies for large or extra large
composite components with complex surface
shapes, has been widely used in the field of
aerospace vehicles. This paper takes 8 lamination
groups with different initial placement angles
generated by the conical shell variable
angle placement algorithm as research objects.
Variable angle placement algorithm for conical
shell and finite element model establishment
method for thermoplastic composite laminations
of variable angle with different initial
placement angles are presented. Static, modal
and buckling analyses are conducted for each
group. The results show that stress-strain relation,
modal and buckling strength of
variable-angle laminations vary regularly with
the initial placement angle.Π’Π΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΊΠ»Π°Π΄ΠΊΠΈ ΡΠ΅ΡΠΌΠΎΠΏΠ»Π°ΡΡΠΈΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠ½ΠΎΠ³ΠΎ Π²ΠΎΠ»ΠΎΠΊΠ½Π°, ΡΠ²Π»ΡΡΡΠ°ΡΡΡ
ΠΎΠ΄Π½ΠΎΠΉ ΠΈΠ· ΡΠ°Π΄ΠΈΠΊΠ°Π»ΡΠ½ΡΡ
ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ Π±ΠΎΠ»ΡΡΠΈΡ
ΠΈΠ»ΠΈ ΠΎΡΠ΅Π½Ρ Π±ΠΎΠ»ΡΡΠΈΡ
ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠΎΠ² ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² Ρ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΡΠΌΠΈ ΡΠΎΡΠΌΠ°ΠΌΠΈ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ, ΡΠΈΡΠΎΠΊΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΡΡΡ Π² Π°Π²ΠΈΠ°ΡΠΈΠΎΠ½Π½ΠΎ-ΠΊΠΎΡΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΠΌΡΡΠ»Π΅Π½Π½ΠΎΡΡΠΈ. Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΎΠ±ΡΠ΅ΠΊΡΠΎΠ² ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»ΠΈ Π²ΠΎΡΠ΅ΠΌΡ Π³ΡΡΠΏΠΏ ΡΠ»ΠΎΠΈΡΡΡΡ
ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ² Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠΌΠΈ ΡΠ³Π»Π°ΠΌΠΈ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠ°Π·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ, ΠΊΠΎΡΠΎΡΡΠ΅ Π±ΡΠ»ΠΈ ΡΠΎΠ·Π΄Π°Π½Ρ Ρ
ΠΏΠΎΠΌΠΎΡΡΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΡΠ°Π·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠ³Π»Π° ΠΊΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΎΠ±ΠΎΠ»ΠΎΡΠΊΠΈ. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ Π°Π»Π³ΠΎΡΠΈΡΠΌ ΡΠ°Π·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠ³Π»Π° Π΄Π»Ρ ΠΊΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΎΠ±ΠΎΠ»ΠΎΡΠΊΠΈ ΠΈ ΠΌΠΎΠ΄Π΅Π»Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΌΠ΅ΡΠΎΠ΄Π°
ΠΊΠΎΠ½Π΅ΡΠ½ΡΡ
ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² Π΄Π»Ρ ΡΠ΅ΡΠΌΠΎΠΏΠ»Π°ΡΡΠΈΡΠ½ΡΡ
ΡΠ»ΠΎΠΈΡΡΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌ ΡΠ³Π»ΠΎΠΌ. ΠΠ»Ρ
ΠΊΠ°ΠΆΠ΄ΠΎΠΉ Π³ΡΡΠΏΠΏΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ² ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½Ρ ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈΠΉ Π°Π½Π°Π»ΠΈΠ·, ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΡΠ°Π·Π»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΏΠΎ ΡΠΎΠ±ΡΡΠ²Π΅Π½Π½ΡΠΌ ΡΠΎΡΠΌΠ°ΠΌ ΠΈ ΡΠ°ΡΡΠ΅Ρ ΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ
Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠ΅βΠ΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΡ, ΠΌΠΎΠ΄Π°Π»ΡΠ½Π°Ρ ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΠΈ ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΠΏΡΠΈ ΠΏΡΠΎΠ΄ΠΎΠ»ΡΠ½ΠΎΠΌ ΠΈΠ·Π³ΠΈΠ±Π΅ ΡΠ»ΠΎΠΈΡΡΡΡ
ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ² Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌ ΡΠ³Π»ΠΎΠΌ ΠΏΠ΅ΡΠΈΠΎΠ΄ΠΈΡΠ΅ΡΠΊΠΈ ΠΈΠ·ΠΌΠ΅Π½ΡΡΡΡΡ Π² Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΎΡ ΡΠ³Π»Π° ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠ°Π·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ.Π’Π΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΡΡ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠΊΠ»Π°Π΄Π°Π½Π½Ρ ΡΠ΅ΡΠΌΠΎΠΏΠ»Π°ΡΡΠΈΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠ½ΠΎΠ³ΠΎ Π²ΠΎΠ»ΠΎΠΊΠ½Π°, ΡΠΎ Ρ
ΠΎΠ΄Π½ΡΡΡ Π· ΡΠ°Π΄ΠΈΠΊΠ°Π»ΡΠ½ΠΈΡ
ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΡΠΉ ΠΎΡΡΠΈΠΌΠ°Π½Π½Ρ Π²Π΅Π»ΠΈΠΊΠΈΡ
Π°Π±ΠΎ Π΄ΡΠΆΠ΅ Π²Π΅Π»ΠΈΠΊΠΈΡ
ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΡΠ²
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΡΠ² ΡΠ· ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΈΠΌΠΈ ΡΠΎΡΠΌΠ°ΠΌΠΈ ΠΏΠΎΠ²Π΅ΡΡ
Π½Ρ, ΡΠΈΡΠΎΠΊΠΎ Π²ΠΈΠΊΠΎΡΠΈΡΡΠΎΠ²ΡΡΡΡΡΡ Π² Π°Π²ΡΠ°ΡΡΠΉΠ½ΠΎ-ΠΊΠΎΡΠΌΡΡΠ½ΡΠΉ ΠΏΡΠΎΠΌΠΈΡΠ»ΠΎΠ²ΠΎΡΡΡ. ΠΠ±βΡΠΊΡΠΎΠΌ Π΄ΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½Π½Ρ ΡΠ»ΡΠ³ΡΠ²Π°Π»ΠΈ Π²ΡΡΡΠΌ Π³ΡΡΠΏ ΡΠ°ΡΡΠ²Π°ΡΠΈΡ
ΠΌΠ°ΡΠ΅ΡΡΠ°Π»ΡΠ² ΡΠ· ΡΡΠ·Π½ΠΈΠΌΠΈ ΠΊΡΡΠ°ΠΌΠΈ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠΎΠ·ΠΌΡΡΠ΅Π½Π½Ρ, ΡΠΊΡ ΠΎΡΡΠΈΠΌΠ°Π½ΠΎ Π·Π° Π΄ΠΎΠΏΠΎΠΌΠΎΠ³ΠΎΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΡΠΎΠ·ΠΌΡΡΠ΅Π½Π½Ρ Π·ΠΌΡΠ½Π½ΠΎΠ³ΠΎ ΠΊΡΡΠ° ΠΊΠΎΠ½ΡΡΠ½ΠΎΡ ΠΎΠ±ΠΎΠ»ΠΎΠ½ΠΊΠΈ. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ΠΎ Π°Π»Π³ΠΎΡΠΈΡΠΌ
ΡΠΎΠ·ΠΌΡΡΠ΅Π½Π½Ρ Π·ΠΌΡΠ½Π½ΠΎΠ³ΠΎ ΠΊΡΡΠ° Π΄Π»Ρ ΠΊΠΎΠ½ΡΡΠ½ΠΎΡ ΠΎΠ±ΠΎΠ»ΠΎΠ½ΠΊΠΈ Ρ ΠΌΠΎΠ΄Π΅Π»Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Ρ ΠΌΠ΅ΡΠΎΠ΄Ρ ΡΠΊΡΠ½ΡΠ΅Π½Π½ΠΈΡ
Π΅Π»Π΅ΠΌΠ΅Π½ΡΡΠ² Π΄Π»Ρ ΡΠ΅ΡΠΌΠΎΠΏΠ»Π°ΡΡΠΈΡΠ½ΠΈΡ
ΡΠ°ΡΡΠ²Π°ΡΠΈΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΡΠ² Π·Ρ Π·ΠΌΡΠ½Π½ΠΈΠΌ ΠΊΡΡΠΎΠΌ. ΠΠ»Ρ
ΠΊΠΎΠΆΠ½ΠΎΡ Π³ΡΡΠΏΠΈ ΠΌΠ°ΡΠ΅ΡΡΠ°Π»ΡΠ² ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΡΡΠ°ΡΠΈΡΡΠΈΡΠ½ΠΈΠΉ Π°Π½Π°Π»ΡΠ·, Π΄ΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½Π½Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΡΠΎΠ·ΠΊΠ»Π°Π΄Π°Π½Π½Ρ Π·Π° Π²Π»Π°ΡΠ½ΠΈΠΌΠΈ ΡΠΎΡΠΌΠ°ΠΌΠΈ Ρ ΡΠΎΠ·ΡΠ°Ρ
ΡΠ½ΠΎΠΊ ΡΡΡΠΉΠΊΠΎΡΡΡ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΠΎ Π·Π°Π»Π΅ΠΆΠ½ΡΡΡΡ
Π½Π°ΠΏΡΡΠΆΠ΅Π½Π½ΡβΠ΄Π΅ΡΠΎΡΠΌΠ°ΡΡΡ, ΠΌΠΎΠ΄Π°Π»ΡΠ½Π° ΠΌΡΡΠ½ΡΡΡΡ Ρ ΠΌΡΡΠ½ΡΡΡΡ ΠΏΡΠΈ ΠΏΠΎΠ·Π΄ΠΎΠ²ΠΆΠ½ΡΠΎΠΌΡ Π·Π³ΠΈΠ½Ρ ΡΠ°ΡΡΠ²Π°ΡΠΈΡ
ΠΌΠ°ΡΠ΅ΡΡΠ°Π»ΡΠ² Π·Ρ Π·ΠΌΡΠ½Π½ΠΈΠΌ ΠΊΡΡΠΎΠΌ ΠΏΠ΅ΡΡΠΎΠ΄ΠΈΡΠ½ΠΎ Π·ΠΌΡΠ½ΡΡΡΡΡΡ Π² Π·Π°Π»Π΅ΠΆΠ½ΠΎΡΡΡ Π²ΡΠ΄ ΠΊΡΡΠ° ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠΎΠ·ΠΌΡΡΠ΅Π½Π½Ρ
Reversed Drifting Quasi-periodic Pulsating Structure in an X1.3 Solar Flare on 2005 July 30
Based on the analysis of the microwave observations at frequency of 2.60 --
3.80 GHz in a solar X1.3 flare event observed at Solar Broadband
RadioSpectrometer in Huairou (SBRS/Huairou) on 2005 July 30, an interesting
reversed drifting quasi-periodic pulsating structure (R-DPS) is confirmed. The
R-DPS is mainly composed of two drifting pulsating components: one is a
relatively slow very short-period pulsation (VSP) with period of about 130 --
170 ms, the other is a relatively fast VSP with period of about 70 -- 80 ms.
The R-DPS has a weak left-handed circular polarization. Based on the synthetic
investigations of Reuven Ramaty High Energy Solar Spectroscopic Imaging
(RHESSI) hard X-ray, Geostationary Operational Environmental Satellite (GOES)
soft X-ray observation, and magnetic field extrapolation, we suggest the R-DPS
possibly reflects flaring dynamic processes of the emission source regions
Multiple sources of infection and potential endemic characteristics of the large outbreak of dengue in Guangdong in 2014
A large outbreak of dengue, with the most documented cases, occurred in Guangdong China in 2014. Epidemiological studies and phylogenetic analysis of the isolated dengue virus (DENV) showed this outbreak was attributed to multiple sources and caused by at least two genotypes of DENV-1 (Genotypes I and III) and two genotypes of DENV-2 (Cosmopolitan and Asian I Genotypes). A retrospective review and phylogenetic analysis of DENV isolated in Guangdong showed that DENV-1 Genotype I strains were reported continuously during 2004-2014, Genotype III strains were reported during 2009-2014 ; DENV-2 Cosmopolitan and Asian I Genotype strains were reported continuously during 2012-2014. At least 45,171 cases were reported in this outbreak, with 65.9% of the patients in the 21-55-year-old group. A trend toward a decrease in the daily newly emerged cases lagged by approximately 20 days compared with the mosquito density curve. Several epidemiological characteristics of this outbreak and the stably sustained serotypes and genotypes of DENV isolated in Guangdong suggest that Guangdong has been facing a threat of transforming from a dengue epidemic area to an endemic area. The high temperature, drenching rain, rapid urbanization, and pandemic of dengue in Southeast Asia may have contributed to this large outbreak of dengue
Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and Ξ½p nucleosynthesis processes
Β© 2018 The Authors. Published by Elsevier B.V. This manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of βΌ10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low Ξ± separation energies for neutron-deficient Mo and Tc isotopes, making the formation of ZrβNb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous Ξ½p-process simulations.Peer reviewe
Hadronic B Decays to Charmed Baryons
We study exclusive B decays to final states containing a charmed baryon
within the pole model framework. Since the strong coupling for is larger than that for , the two-body charmful decay
has a rate larger than
as the former proceeds via the pole while the latter via the
pole. By the same token, the three-body decay receives less baryon-pole contribution than
. However, because the important charmed-meson
pole diagrams contribute constructively to the former and destructively to the
latter, has a rate slightly larger than
. It is found that one quarter of the rate comes from the resonant contributions. We discuss
the decays and
and stress that they are not color suppressed even though they can only proceed
via an internal W emission.Comment: 25 pages, 6 figure
High-efficiency and low-loss gallium nitride dielectric metasurfaces for nanophotonics at visible wavelengths
The dielectric nanophotonics research community is currently exploring transparent material platforms (e.g., TiO2, Si3N4, and GaP) to realize compact high efficiency optical devices at visible wavelengths. Efficient visible-light operation is key to integrating atomic quantum systems for future quantum computing. Gallium nitride (GaN), a III-V semiconductor which is highly transparent at visible wavelengths, is a promising material choice for active, nonlinear, and quantum nanophotonic applications. Here, we present the design and experimental realization of high efficiency beam deflecting and polarization beam splitting metasurfaces consisting of GaN nanostructures etched on the GaN epitaxial substrate itself. We demonstrate a polarization insensitive beam deflecting metasurface with 64% and 90% absolute and relative efficiencies. Further, a polarization beam splitter with an extinction ratio of 8.6/1 (6.2/1) and a transmission of 73% (67%) for p-polarization (s-polarization) is implemented to demonstrate the broad functionality that can be realized on this platform. The metasurfaces in our work exhibit a broadband response in the blue wavelength range of 430-470 nm. This nanophotonic platform of GaN shows the way to off- and on-chip nonlinear and quantum photonic devices working efficiently at blue emission wavelengths common to many atomic quantum emitters such as Ca+ and Sr+ ions. Β© 2017 Author(s)
Charmless Exclusive Baryonic B Decays
We present a systematical study of two-body and three-body charmless baryonic
B decays. Branching ratios for two-body modes are in general very small,
typically less than , except that \B(B^-\to p \bar\Delta^{--})\sim
1\times 10^{-6}. In general, due to
the large coupling constant for . For three-body modes we
focus on octet baryon final states. The leading three-dominated modes are with a branching ratio of
order for and
for . The penguin-dominated decays with strangeness
in the meson, e.g., and , have appreciable rates and the mass
spectrum peaks at low mass. The penguin-dominated modes containing a strange
baryon, e.g., , have
branching ratios of order . In contrast, the decay
rate of is smaller. We explain why some of
charmless three-body final states in which baryon-antibaryon pair production is
accompanied by a meson have a larger rate than their two-body counterparts:
either the pole diagrams for the former have an anti-triplet bottom baryon
intermediate state, which has a large coupling to the meson and the
nucleon, or they are dominated by the factorizable external -emission
process.Comment: 46 pages and 3 figures, to appear in Phys. Rev. D. Major changes are:
(i) Calculations of two-body baryonic B decays involving a Delta resonance
are modified, and (ii) Penguin-dominated modes B-> Sigma+N(bar)+p are
discusse
Matching the phenology of net ecosystem exchange and vegetation indices estimated with MODIS and FLUXNET in-situ observations
Shifts in ecosystem phenology play an important role in the definition of inter-annual variability of net ecosystem carbon uptake. A good estimate at the global scale of ecosystem phenology, mainly that of photosynthesis or gross primary productivity (GPP), may be provided by vegetation indices derived from MODIS satellite image data. However, the relationship between the start date of a growing (or greening) season (SGS) when derived from different vegetation indices (VI's), and the starting day of carbon uptake is not well elucidated. Additionally, the validation of existing phenology data with in-situ measurements is largely missing. We have investigated the possibility to use different VI's to predict the starting day of the growing season for 28 FLUXNET sites as well as MODIS data. This analysis included main plant functional types (PFT's). Of all VI's taken into account in this paper, the NDVI (Normalized Difference Vegetation Index) shows the highest correlation coefficient for the relationship between the starting day of the growing season as observed with MODIS and in-situ observations. However, MODIS observations elicit a 20-21 days earlier SGS date compared to in-situ observations. The prediction for the NEE start of the growing season diverges when using different VI's, and seems to depend on the amplitude for carbon and VI and on PFT. The optimal VI for estimation of a SGS date was PFT-specific - for example the WRDVI for cropland, but the MODIS NDVI performed best when applied as an estimator for Net Ecosystem Exchange and when considering all PFT's pooled
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