3,110 research outputs found
Improving competitive ability of chickpea with sowthistle
An experiment was conducted to examine the extent of root and canopy interference of chickpea (Cicer arietinum L.) with sowthistle (Sonchus oleraceus L.). Sowthistle was surrounded with either two or eight chickpea plants. There were different types of competition: no competition, shoot competition, root competition and full competition (root and shoot). The performance of sowthistle grown in full competition with two chickpea plants was the same as that grown with root competition only. Also, there were no significant differences between sowthistle grown with chickpea canopy shade and the control, where there was no competition. On the other hand sowthistle grown with eight neighbours was significantly suppressed in full, canopy or root competition
The Eclipsing Scuti Star EPIC 245932119
We present the physical properties of EPIC 245932119 ( = 9.82)
exhibiting both eclipses and pulsations from the {\it K{\rm 2}} photometry. The
binary modeling indicates that the eclipsing system is in detached or
semi-detached configurations with a mass ratio of 0.283 or 0.245, respectively,
and that its light-curve parameters are almost unaffected by pulsations.
Multiple frequency analyses were performed for the light residuals in the
outside-primary eclipsing phase after subtracting the binarity effects from the
observed data. We detected 35 frequencies with signal to noise amplitude ratios
larger than 4.0 in two regions of 0.626.28 day and 19.3624.07
day. Among these, it is possible that some high signals close to the
Nyquist limit may be reflections of real pulsation frequencies
(2). All frequencies (, , , ,
, ) in the lower frequency region are orbital harmonics, and
three high frequencies (, , ) appear to be sidelobes
split from the main frequency of = 22.77503 day. Most of them are
thought to be alias effects caused by the orbital frequency. For the 26 other
frequencies, the pulsation periods and pulsation constants are in the ranges of
0.0410.052 days and 0.0130.016 days, respectively. These values and the
position in the Hertzsprung-Russell diagram reveal that the primary component
is a Sct pulsator. The observational properties of EPIC 245932119 are
in good agreement with those for eclipsing binaries with Sct-type
pulsating components.Comment: 17 pages, including 5 figures and 3 tables, accepted for publication
in A
"Et problembarn?" : når politiet kommer på banen! : en teoretisk oppgave
Bachelor i politiutdannin
On a tropicalization of planar polynomial ODEs with finitely many structurally stable phase portraits
Recently, concepts from the emerging field of tropical geometry have been
used to identify different scaling regimes in chemical reaction networks where
dimension reduction may take place. In this paper, we try to formalize these
ideas further in the context of planar polynomial ODEs. In particular, we
develop a theory of a tropical dynamical system, based upon a differential
inclusion, that has a set of discontinuities on a subset of the associated
tropical curve. The development is inspired by an approach of Peter Szmolyan
that uses the connection of tropical geometry with logarithmic paper. In this
paper, we define a phaseportrait, a notion of equivalence and characterize
structural stability. Furthermore, we demonstrate the results on several
examples, including a(n) (generalized) autocatalator model. Our main result is
that there are finitely many equivalence classes of structurally stable phase
portraits and we enumerate these ( in total) in the context of the
generalized autocatalator model. We believe that the property of finitely many
structurally stable phase portraits underlines the potential of the tropical
approach, also in higher dimension, as a method to obtain and identify skeleton
models in chemical reaction networks in extreme parameter regimes
Theory and applications of supercycled symmetry-based recoupling sequences in solid-state NMR
We present the theoretical principles of supercycled symmetry-based recoupling sequences in solid-state magic-angle-spinning NMR. We discuss the construction procedure of the SR26 pulse sequence, which is a particularly robust sequence for double-quantum homonuclear dipole-dipole recoupling. The supercycle removes destructive higher-order average Hamiltonian terms and renders the sequence robust over long time intervals. We demonstrate applications of the SR26 sequence to double-quantum spectroscopy, homonuclear spin counting, and determination of the relative orientations of chemical shift anisotropy tensors
Seasonal variation in population dynamics of Calanus finmarchicus in the south western Norwegian Sea
Burnout and Its Antecedents:Considering Both Work and Household Time Claims, and Flexibility in Relation to Burnout
This study contributes to the previous literature by examining how flexible work arrangements interact with work and family time claims to affect burnout. It does so by providing a theoretical framework and empirical test of the interaction of flexibility with the effect of work and family time claims on burnout. Hypotheses and predictions based on previous literature are tested by Ordinary Least Squared regression models using data from the Time Competition Survey, constituting a sample of 1,058 employees of 89 function groups within 30 organizations. We found no main effects of work and family time claims or flexible work arrangements on burnout. However, the results do show an interaction of flexible working hours with the effect of work and family time claims on burnout. Specifically, the higher an individual's work and family time claims, the more this person benefits from having flexible working hours. In general, the results support the proposition that the relationship between work and family time claims and burnout differs for individuals with different levels of flexible work arrangements.</p
Thermal and electrical modelling of polymer cored BGA interconnects
Polymer cored BGA/CSP balls have been proposed as
a more reliable alternative to solid solder balls for
demanding application environments. Their potential
advantages are dependant on their increased compliance
compared with a solid solder ball, thereby reducing the
level of stress imposed on the solder joints during
exposure to cyclic thermal loads and impacts. The latter is
of particular importance for hand held products
assembled using lead free solders, which are much more
brittle than traditional tin-lead alloys, but this may also be
important for harsh environment applications where tinlead
solders are still being used, such as in aerospace and
defence electronics applications. The increased
compliance of a polymer cored ball may reduce the
requirement for underfilling of components in hand held
products, and allow adoption of BGA/CSP for safety
critical applications in harsh environments. Such polymer
cored interconnects are however likely to provide a
reduced thermal and electrical conductivity and it is
important to ensure any such effects do not impact upon
the thermal and electrical performance of the product.
This paper utilises analytical and computational
modelling techniques to achieve an understanding of the
effect of conductor particle geometry and properties on
thermal and electrical performance. Such models offer a
route to appropriate materials selection for the polymer
spheres and their conductive coatings, and for
establishing optimum design parameters such as ball
diameter, conductive coating thickness, solder pad
diameter, and solder volumes.
The results confirm that the introduction of polymer
cored BGA balls will result in some increases in thermal
and electrical resistance, but that these changes will have
minor impacts on the overall performance of products
- …