9,707 research outputs found
Investigating the Effect of Stratospheric Radiation on Seed Germination and Growth
Three seed types: bean (Phaseolus vulgaris), corn (Zea mays) and radish (Raphanus sativus) were flown in a high altitude weather balloon into the mid-stratosphere to investigate the effects of high altitude radiation on germination success and seedling growth. After recovering and planting the seeds, the bean seeds showed lower germination success with exposure to high altitude radiation, and consequently stunted seedling growth. Cord and radish seeds experienced a statistically significant positive effect on germination success form radiation exposure compared to control seeds, but negative effect on seedling growth. Overall, the field experiments presented here support laboratory studies that show radiation exposure on vegetable seeds has a mixed effect on the germination success and negative effect on seedling growth on investigated seed types
Progress in Solving the 3-Dimensional Inversion Problem for Eddy Current NDE
The eddy current NDE inversion problem is to determine the parameters of a flaw from the measured eddy current sensor impedance changes. Mathematically, this requires finding the transformation which gives the sensor impedance changes in terms of the flaw parameters, and then inverting this transformation. Finding the transformation is called the forward problem, and finding the inverse of the transformation is equivalent to the inversion problem. The principal difficulty in solving the forward problem is finding solutions to Maxwell\u27s equations in the complex geometries involved. This paper describes a solution to the forward problem which is valid for ellipsoidal shaped void flaws in a non-magnetic conductor, and for flaw dimensions such that the incident field variations are at most linear over the region occupied by the flaw
ANTICIPATION EFFECT ON KNEE JOINT STABILITY DURING PLANNED AND UN-PLANNED MOVEMENT TESTS IN LABORATORY
The purpose of this study was to investigate the anticipation effect on knee stability during functional test in laboratory. Ten healthy male subjects were recruited and instructed to perform a series of planned and un-planned stop-jumping tasks. Knee joint kinematics was measured by a motion analysis system. The subjects demonstrated different abduction and rotation angles for reactive tasks. This suggested that if knee abduction or rotational stability is considered as a primary measurement in documenting knee stability, such as in the investigation of rehabilitation progress after anterior cruciate ligament reconstruction, both planned and un-planned tasks should be considered as to take the anticipation effect into account
BIOMECHANICS ANALYSIS OF ANKLE SUPINATION SPRAIN INJURY
One male athlete accidentally sprained his ankle with a supination mechanism while performing a series of cutting motion trials in a laboratory. The injury was immediately diagnosed as a grade one mild anterior talofibular ligamentous sprain, and was simultaneously recorded by three calibrated cameras and a pressure insole system at 100 Hz. For the injury trial, results showed that the foot and ankle was more internally rotated and greatly inverted at foot strike, followed by a fast plantarflexion and shift of center of pressure to forefoot. The rearfoot was lifted and swung to the lateral aspect, thus increasing the moment arm and the ankle joint torque. The ankle joint finally reached an orientation of 66 degrees dorsiflexion, 48 degrees internal rotation and 103 degrees inversion
Leptogenesis from Soft Supersymmetry Breaking (Soft Leptogenesis)
Soft leptogenesis is a scenario in which the cosmic baryon asymmetry is
produced from a lepton asymmetry generated in the decays of heavy sneutrinos
(the partners of the singlet neutrinos of the seesaw) and where the relevant
sources of CP violation are the complex phases of soft supersymmetry-breaking
terms. We explain the motivations for soft leptogenesis, and review its basic
ingredients: the different CP-violating contributions, the crucial role played
by thermal corrections, and the enhancement of the efficiency from lepton
flavour effects. We also discuss the high temperature regime GeV in
which the cosmic baryon asymmetry originates from an initial asymmetry of an
anomalous -charge, and soft leptogenesis reembodies in -genesis.Comment: References updated. Some minor corrections to match the published
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A decidable policy language for history-based transaction monitoring
Online trading invariably involves dealings between strangers, so it is
important for one party to be able to judge objectively the trustworthiness of
the other. In such a setting, the decision to trust a user may sensibly be
based on that user's past behaviour. We introduce a specification language
based on linear temporal logic for expressing a policy for categorising the
behaviour patterns of a user depending on its transaction history. We also
present an algorithm for checking whether the transaction history obeys the
stated policy. To be useful in a real setting, such a language should allow one
to express realistic policies which may involve parameter quantification and
quantitative or statistical patterns. We introduce several extensions of linear
temporal logic to cater for such needs: a restricted form of universal and
existential quantification; arbitrary computable functions and relations in the
term language; and a "counting" quantifier for counting how many times a
formula holds in the past. We then show that model checking a transaction
history against a policy, which we call the history-based transaction
monitoring problem, is PSPACE-complete in the size of the policy formula and
the length of the history. The problem becomes decidable in polynomial time
when the policies are fixed. We also consider the problem of transaction
monitoring in the case where not all the parameters of actions are observable.
We formulate two such "partial observability" monitoring problems, and show
their decidability under certain restrictions
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