276 research outputs found
EFFECT OF NITROGEN ON SAFFLOWER PHYSIOLOGY AND PRODUCTIVITY
Safflower ( Carthamus tinctorius ) L. is an oil-crop suitable for
semi-arid agriculture, but its physiological re- sponse to agronomic
inputs has yet to be fully evaluated. The effect of fertiliser on the
physiology and produc- tion of Safflower grown in pots filled with
standard grade perlite inside a semi-controlled glass house was
studied. Plants were initially irrigated with 20-100 ml standard
hydroponic solution and then one month after germination plants were
irrigated using 50-200 ml complete Hoagland\u2019s solution,
supplemented with one of eight levels of nitrogen (0, 25, 50, 75, 100,
125, 150, 175 kg N ha-1) in the form of ammonium nitrate. Elevating
nitrogen to 100 kg N ha-1 significantly increased the assimilation rate
by about 42 %, transpiration rate by 32%, stomatal conductance by 52%
and LAI by 42% compared with the control. The above ground dry weight,
seed yield and Water Use Efficiency (WUE) increased incrementally with
increases in nitrogen rate. Above ground dry weight increased by an
average of 42%, seed yield by 76% and WUE by 41% at harvest compared
with the control. This study clearly demonstrates how nitrogen
fertilisation can affect physiology of Safflower leading to im-
provement in seed yield.Le carthame ( Carthamus tinctorius ) L.) est une culture
ol\ue9agineuse appropri\ue9e \ue0 l\u2019agriculture semi aride,
mais sa r\ue9ponse physiologique aux intrants agronomiques reste
\ue0 \ue9valuer. L\u2019effet de fertilisants sur la physiologie
et la production du carthame cultiv\ue9 en pots rempli de perlites de
niveau standard \ue0 l\u2019int\ue9rieur d\u2019une serre semi
contr\uf4l\ue9e \ue9tait \ue9tudi\ue9. Les plants
\ue9taient initialement irrigu\ue9s avec 20-100 ml de solution
hydroponique standard et, ensuite, un mois apr\ue8s la germination
des plants \ue9taient irrigu\ue9s avec 50-200 ml de solution de
Hoagland compl\ue8te et un suppl\ue9ment de huit niveau
d\u2019azote (0, 25, 50, 75, 100, 125, 150, 175 kg N ha-1) sous forme
du nitrate d\u2019ammonium. L\u2019utilisation de la dose de 100 kg N
ha-1 a significativement accru le taux d\u2019assimilation
d\u2019environ 42 %, le taux de transpiration de 32 %, la conductance
stomatale de 52 % et l\u2019index de la surface foliaire de 42 % en
comparaison avec le t\ue9moin. Le poids sec de la biomasse
a\ue9rienne, le rendement en grain et le Water Use Efficieny (WUE)
avait augment\ue9 avec la dose d\u2019azote. Le poids sec de la
biomasse a\ue9rienne a en moyenne augment\ue9 de 42% pendant que le
rendement en grains et le WAE ont augment\ue9 \ue0 la r\ue9colte
de 76% et 41% , respectivement, en comparaison avec le t\ue9moin.
Cette \ue9tude d\ue9montre clairement comment la fertilisation
azot\ue9e peut affecter la physiologie du carthame conduisant \ue0
l\u2019am\ue9lioration du rendement en grains
Flexible modeling of dependence in volatility processes
This paper proposes a novel stochastic volatility model that draws from the exist- ing literature on autoregressive stochastic volatility models, aggregation of autoregres- sive processes, and Bayesian nonparametric modelling to create a stochastic volatility model that can capture long range dependence. The volatility process is assumed to be the aggregate of autoregressive processes where the distribution of the autoregressive coefficients is modelled using a flexible Bayesian approach. The model provides insight into the dynamic properties of the volatility. An efficient algorithm is defined which uses recently proposed adaptive Monte Carlo methods. The proposed model is applied to the daily returns of stocks
Exact Solutions for Matter-Enhanced Neutrino Oscillations
The analogy between supersymmetric quantum mechanics and matter-enhanced
neutrino oscillations is exploited to obtain exact solutions for a class of
electron density profiles. This integrability condition is analogous to the
shape-invariance in supersymmetric quantum mechanics. This method seems to be
the most direct way to obtain the exact survival probabilities for a number of
density profiles of interest, such as linear and exponential density profiles.
The resulting neutrino amplitudes can also be utilized as comparison amplitudes
for the uniform semiclassical treatment of neutrino propagation in arbitrary
electron density profiles.Comment: Submitted to Physical Review D. Latex file, 8 pages. This paper is
also available at http://nucth.physics.wisc.edu/preprints
Making things happen : a model of proactive motivation
Being proactive is about making things happen, anticipating and preventing problems, and seizing opportunities. It involves self-initiated efforts to bring about change in the work environment and/or oneself to achieve a different future. The authors develop existing perspectives on this topic by identifying proactivity as a goal-driven process involving both the setting of a proactive goal (proactive goal generation) and striving to achieve that proactive goal (proactive goal striving). The authors identify a range of proactive goals that individuals can pursue in organizations. These vary on two dimensions: the future they aim to bring about (achieving a better personal fit within one’s work environment, improving the organization’s internal functioning, or enhancing the organization’s strategic fit with its environment) and whether the self or situation is being changed. The authors then identify “can do,” “reason to,” and “energized to” motivational states that prompt proactive goal generation and sustain goal striving. Can do motivation arises from perceptions of self-efficacy, control, and (low) cost. Reason to motivation relates to why someone is proactive, including reasons flowing from intrinsic, integrated, and identified motivation. Energized to motivation refers to activated positive affective states that prompt proactive goal processes. The authors suggest more distal antecedents, including individual differences (e.g., personality, values, knowledge and ability) as well as contextual variations in leadership, work design, and interpersonal climate, that influence the proactive motivational states and thereby boost or inhibit proactive goal processes. Finally, the authors summarize priorities for future researc
On the two-dimensional solution of both adhesive and non-adhesive contact problems involving functionally graded materials
This paper presents a semi-analytical algorithm for the determination of the contact half width and surface pressure which results from both adhesive and non-adhesive contact problems involving functionally graded materials (FGM). The inhomogeneously elastic solid comprises a graded elastic coating whose shear modulus depends exponentially on the vertical coordinate and a homogeneously elastic substrate. The solid is assumed to be in a state of plane strain and thus a two-dimensional analysis is performed within this work.
Using the work of Chidlow et al. (2011a) as a starting point, we derive a pair of integral equations which may be used to determine approximations to the contact pressure when either the surface deflection or the deflection gradient is known over the contact region. As these integral equations are non-singular, we use Galerkin's method to approximate the contact pressure and it is found that relatively small trial spaces allow accurate computation of the pressure. Information about the prescribed load is then used to formulate an iterative algorithm to determine the contact half width.
A selection of numerical results are presented using this method and it is found that the solutions computed here compare favourably with those of other authors. A further investigation is then conducted into the solution of adhesive contact problems using the assumptions of Maugis (1992) and Johnson and Greenwood (2008) to inform the nature of the adhesive stresses outside of the contact. It is found that both JKR-like and DMT-like behaviour can be observed in contact problems involving FGMs
Energy radiation of moving cracks
The energy radiated by moving cracks in a discrete background is analyzed.
The energy flow through a given surface is expressed in terms of a generalized
Poynting vector. The velocity of the crack is determined by the radiation by
the crack tip. The radiation becomes more isotropic as the crack velocity
approaches the instability threshold.Comment: 7 pages, embedded figure
Pulsar kicks from a dark-matter sterile neutrino
We show that a sterile neutrino with mass in the 1-20 keV range and a small
mixing with the electron neutrino can simultaneously explain the origin of the
pulsar motions and the dark matter in the universe. An asymmetric neutrino
emission from a hot nascent neutron star can be the explanation of the observed
pulsar velocities. In addition to the pulsar kick mechanism based on resonant
neutrino transitions, we point out a new possibility: an asymmetric
off-resonant emission of sterile neutrinos. The two cases correspond to
different values of the masses and mixing angles. In both cases we identify the
ranges of parameters consistent with the pulsar kick, as well as cosmological
constraints.Comment: 5 pages, 2 figures; final version; discussion and references adde
The Concussion Recognition Tool 5th Edition (CRT5): Background and rationale
The Concussion Recognition Tool 5 (CRT5) is the most recent revision of the Pocket Sport Concussion Assessment Tool 2 that was initially introduced by the Concussion in Sport Group in 2005. The CRT5 is designed to assist non-medically trained individuals to recognise the signs and symptoms of possible sport-related concussion and provides guidance for removing an athlete from play/sport and to seek medical attention. This paper presents the development of the CRT5 and highlights the differences between the CRT5 and prior versions of the instrument
In Silico and Structural Analyses Demonstrate That Intrinsic Protein Motions Guide T Cell Receptor Complementarity Determining Region Loop Flexibility.
T-cell immunity is controlled by T cell receptor (TCR) binding to peptide major histocompatibility complexes (pMHCs). The nature of the interaction between these two proteins has been the subject of many investigations because of its central role in immunity against pathogens, cancer, in autoimmunity, and during organ transplant rejection. Crystal structures comparing unbound and pMHC-bound TCRs have revealed flexibility at the interaction interface, particularly from the perspective of the TCR. However, crystal structures represent only a snapshot of protein conformation that could be influenced through biologically irrelevant crystal lattice contacts and other factors. Here, we solved the structures of three unbound TCRs from multiple crystals. Superposition of identical TCR structures from different crystals revealed some conformation differences of up to 5 Å in individual complementarity determining region (CDR) loops that are similar to those that have previously been attributed to antigen engagement. We then used a combination of rigidity analysis and simulations of protein motion to reveal the theoretical potential of TCR CDR loop flexibility in unbound state. These simulations of protein motion support the notion that crystal structures may only offer an artifactual indication of TCR flexibility, influenced by crystallization conditions and crystal packing that is inconsistent with the theoretical potential of intrinsic TCR motions
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