1,765 research outputs found
Effect of leaf temperature on estimating physiological traits of wheat leaves from hyperspectral reflectance
A growing number of leaf traits can be predicted from hyperspectral reflectance data. These include structural and compositional traits, such as leaf mass per area, nitrogen and chlorophyll content, but also physiological traits such a Rubisco carboxylation activity, electron transport rate and respiration rate. Since physiological traits vary with leaf temperature, how does this impact on predictions made from reflectance measurements? We investigated this with two wheat varieties, by repeatedly measuring each leaf through a sequence of temperatures imposed by varying the air temperature in a growth room. The function predicting Rubisco capacity normalised to 25 °C predicted the same value, regardless of leaf temperatures ranging from 20 to 35°C. Leaf temperature affected none of the predicted traits: Vcmax25, J, chlorophyll content, LMA, N content per unit leaf area or Vcmax25/N. However, as others have derived models to predict Rubisco activity that includes variation associated with leaf temperature, we discuss whether these functions may include a temperature signal within the reflectance spectra
MATHEMATICAL MODELLING FOR MAGNETITE (CRUDE) REMOVAL FROM PRIMARY HEAT TRANSFER LOOP BY ION-EXCHANGE RESINS
The present research focuses to develop mathematical model for the removal of iron (magnetite) by ion-exchange resin from primary heat transfer loop of process industries. This mathematical model is based on operating capacities (that's provide more effective design as compared to loading capacity) from static laboratory tests. Results showed non-steady state distribution of external Fe2+ and limitations imposed on operating conditions, these conditions includes; loading and elution cycle time, flow rate, concentration of both loading and removal, volume of resin required. Number of generalized assumptions was made under shortcut modeling techniques to overcome the gap of theoretical and actual process design.
KEY WORDS: Magnetite, Mathematical modeling, Ion-exchange resin, Operating capacity, Loading capacity
Bull. Chem. Soc. Ethiop. 2009, 23(1), 129-133
Probing the isovector transition strength of the low-lying nuclear excitations induced by inverse kinematics proton scattering
A compact approach based on the folding model is suggested for the
determination of the isoscalar and isovector transition strengths of the
low-lying () excitations induced by inelastic proton
scattering measured with exotic beams. Our analysis of the recently measured
inelastic O+p scattering data at and 43 MeV/nucleon
has given for the first time an accurate estimate of the isoscalar
and isovector deformation parameters (which cannot be determined from
the (p,p') data alone by standard methods) for 2 and excited
states in O. Quite strong isovector mixing was found in the 2
inelastic O+p scattering channel, where the strength of the isovector
form factor (prototype of the Lane potential) corresponds to a
value almost 3 times larger than and a ratio of nuclear transition
matrix elements .Comment: 5 pages, 3 figure
Vertical transport and electroluminescence in InAs/GaSb/InAs structures: GaSb thickness and hydrostatic pressure studies
We have measured the current-voltage (I-V) of type II InAs/GaSb/InAs double
heterojunctions (DHETs) with 'GaAs like' interface bonding and GaSb thickness
between 0-1200 \AA. A negative differential resistance (NDR) is observed for
all DHETs with GaSb thickness 60 \AA below which a dramatic change in the
shape of the I-V and a marked hysteresis is observed. The temperature
dependence of the I-V is found to be very strong below this critical GaSb
thickness. The I-V characteristics of selected DHETs are also presented under
hydrostatic pressures up to 11 kbar. Finally, a mid infra-red
electroluminescence is observed at 1 bar with a threshold at the NDR valley
bias. The band profile calculations presented in the analysis are markedly
different to those given in the literature, and arise due to the positive
charge that it is argued will build up in the GaSb layer under bias. We
conclude that the dominant conduction mechanism in DHETs is most likely to
arise out of an inelastic electron-heavy-hole interaction similar to that
observed in single heterojunctions (SHETs) with 'GaAs like' interface bonding,
and not out of resonant electron-light-hole tunnelling as proposed by Yu et al.
A Zener tunnelling mechanism is shown to contribute to the background current
beyond NDR.Comment: 8 pages 12 fig
Gravitational Collapse: Expanding and Collapsing Regions
We investigate the expanding and collapsing regions by taking two well-known
spherically symmetric spacetimes. For this purpose, the general formalism is
developed by using Israel junction conditions for arbitrary spacetimes. This
has been used to obtain the surface energy density and the tangential pressure.
The minimal pressure provides the gateway to explore the expanding and
collapsing regions. We take Minkowski and Kantowski-Sachs spacetimes and use
the general formulation to investigate the expanding and collapsing regions of
the shell.Comment: 12 pages, 4 figures, accepted for publication in Gen. Relativ. Gra
Nucleon Structure from Lattice QCD Using a Nearly Physical Pion Mass
We report the first Lattice QCD calculation using the almost physical pion
mass mpi=149 MeV that agrees with experiment for four fundamental isovector
observables characterizing the gross structure of the nucleon: the Dirac and
Pauli radii, the magnetic moment, and the quark momentum fraction. The key to
this success is the combination of using a nearly physical pion mass and
excluding the contributions of excited states. An analogous calculation of the
nucleon axial charge governing beta decay has inconsistencies indicating a
source of bias at low pion masses not present for the other observables and
yields a result that disagrees with experiment.Comment: journal version; 15 pages, 6 figure
A toy model of fractal glioma development under RF electric field treatment
A toy model for glioma treatment by a radio frequency electric field is
suggested. This low-intensity, intermediate-frequency alternating electric
field is known as the tumor-treating-field (TTF). In the framework of this
model the efficiency of this TTF is estimated, and the interplay between the
TTF and the migration-proliferation dichotomy of cancer cells is considered.
The model is based on a modification of a comb model for cancer cells, where
the migration-proliferation dichotomy becomes naturally apparent. Considering
glioma cancer as a fractal dielectric composite of cancer cells and normal
tissue cells, a new effective mechanism of glioma treatment is suggested in the
form of a giant enhancement of the TTF. This leads to the irreversible
electroporation that may be an effective non-invasive method of treating brain
cancer.Comment: Submitted for publication in European Physical Journal
Experimental study of heat transfer and pressure drop in micro-channel based heat sinks with tip clearance
This article presents an experimental study on the optimisation of micro-heat sink configurations when both thermal effects and pressure drop are accounted for. The interest of the latter is that the practical engineering viability of some of these systems also depends on the required pumping power. The working fluid was water and, according to typical power dissipation and system size requirements, the considered fluid regime was either laminar or transitional, and not fully developed from the hydrodynamics point of view. Five configurations were considered: a reference geometry (selected for comparison purposes) made up of square section micro-channels, and four alternative configurations that involved the presence of a variable tip clearance in the design. The performance of the different configurations was compared with regard to both cooling efficiency and pressure drop. Finally, we also provide some practical guidelines for the engineering design of these types of systems
A formal characterization of SI-based ROWA replication protocols
Snapshot isolation (SI) is commonly used in some commercial DBMSs with a multiversion
concurrency control mechanism since it never blocks read-only transactions. Recent database
replication protocols have been designed using SI replicas where transactions are firstly
executed in a delegate replica and their updates (if any) are propagated to the rest of the
replicas at commit time; i.e. they follow the Read One Write All (ROWA) approach. This paper
provides a formalization that shows the correctness of abstract protocols which cover these
replication proposals. These abstract protocols differ in the properties demanded for achieving
a global SI level and those needed for its generalized SI (GSI) variant ¿ allowing reads from old
snapshots. Additionally, we propose two more relaxed properties that also ensure a global GSI
level. Thus, some applications can further optimize their performance in a replicated system
while obtaining GSI.
© 2010 Elsevier B.V. All rights reserved.The authors wish to thank the reviewers for their valuable comments that helped us to greatly improve the quality and readability of this paper. This work has been supported by the Spanish Government under research grant TIN2009-14460-C03. Besides, the authors wish to thank the reviewers for their valuable comments that helped us to greatly improve the quality and readability of this paper.Armendáriz-Iñigo, J.; Juárez-Rodríguez, J.; González De Mendívil, J.; Garitagoitia, J.; Irún Briz, L.; Muñoz Escoí, FD. (2011). A formal characterization of SI-based ROWA replication protocols. Data and Knowledge Engineering. 70(1):21-34. doi:10.1016/j.datak.2010.07.012S213470
Hadron Structure on the Lattice
A few chosen nucleon properties are described from a lattice QCD perspective:
the nucleon sigma term and the scalar strangeness in the nucleon; the vector
form factors in the nucleon, including the vector strangeness contribution, as
well as parity breaking effects like the anapole and electric dipole moment;
and finally the axial and tensor charges of the nucleon. The status of the
lattice calculations is presented and their potential impact on phenomenology
is discussed.Comment: 17 pages, 9 figures; proceedings of the Conclusive Symposium of the
Collaborative Research Center 443 "Many-body structure of strongly
interacting systems", Mainz, February 23-25, 201
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