1,430 research outputs found

    Eflect of Lodging on Yield and Test Weight of Oats and Establishment of Alfalfa Seedlings

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    Lodging in small grains has been shown to reduce yield and quality of the grain in addition to the harvesting difficulties incurred. Eldredge obtained a yield reduction of 47 percent by bending over oat straws as the heads were emerging from the boot. The yield decreased with injury at succeeding weekly intervals until just before ripening when the loss was 12 percent. Pendleton found that Clinton oat yields were reduced 37 and 17 percent by complete lodging four and 20 days after heading respectively. The plots lodged at 45 degrees on the same two dates yielded 14 and three percent less, respectively, than the non-lodged plots. In barley, Sisler and Olson and Day obtained yield reductions of as much as 50 percent when barley was completely lodged. They noted greater losses in barley yields lodged at heading than at 10 or 20 days after heading. Laude and Pauli reported that winter wheat yield was reduced one third by lodging one to two weeks before and after heading. They speculated that the effect of lodging on yield and quality of wheat was associated with the capacity of the plants to recover from tissue damage and the extent to which materials were translocated to the developing kernels prior to the time of injury. All varieties of wheat tested by Schlumberger and Spahr recovered from lodging which occurred during heading

    Normal frames and the validity of the equivalence principle. I. Cases in a neighborhood and at a point

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    A treatment in a neighborhood and at a point of the equivalence principle on the basis of derivations of the tensor algebra over a manifold is given. Necessary and sufficient conditions are given for the existence of local bases, called normal frames, in which the components of derivations vanish in a neighborhood or at a point. These frames (bases), if any, are explicitly described and the problem of their holonomicity is considered. In particular, the obtained results concern symmetric as well as nonsymmetric linear connections.Comment: LaTeX2e, 9 pages, to be published in Journal of Physics A: Mathematical and Genera

    Broadband Meter-Wavelength Observations of Ionospheric Scintillation

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    Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally these observations are relatively narrow band. With Low Frequency Array (LOFAR) technology at the Kilpisj\"arvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a 3 octave bandwidth. ``Parabolic arcs'', which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broad-band observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250\,MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disappeared after transit although scintillations continued to be obvious during the entire observation. We show that this can be attributed to the structure of Cygnus-A. Initial results from modeling these scintillation arcs are consistent with simultaneous ionospheric soundings taken with other instruments, and indicate that scattering is most likely to be associated more with the topside ionosphere than the F-region peak altitude. Further modeling and possible extension to interferometric observations, using international LOFAR stations, are discussed.Comment: 11 pages, 17 figure

    Metoprolol, fentanyl and stress response to microlaryngoscopy. Effects on arterial pressure, heart rate and plasma concentrations of catecholamines, ACTH and cortisol

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    Forty patients undergoing microlaryngoscopy were anaesthetized with thiopentone and nitrous oxide. Twenty patients received metoprolol 200 mg in a slow-release tablet once daily for 4 days up to, and including, the morning of operation, and lOmgi.v. shortly before induction of anaesthesia. The other patients received placebo tablets and physiological saline i. v., instead-Both groups of 20 patients were further subdivided, half of the patients receiving fentanyl 1.0-1.5mg during anaesthesia, the effect of which was antagonized by naloxone at the end of the procedure. The other patients received saline i.v. instead of fentanyl or naloxone. Metopropolol decreased heart rate and the general level of arterial pressure during anaesthesia, but did not affect the fluctuations in pressure. Arterial plasma noradrenaline concentrations during microjaryngoscopy were >nlmnr<-H by metoprolol, in comparison with placebo, the reverse being the case for cortisol concentrations. Fentanyl decreased arterial pressure and plasma ACTH and cortisol concentrations regardless of whether the patient had received metoprolol. Plasma adrenaline and noradrenaline concentrations were decreased by fentanyl in the patients receiving metoprolol

    Flows and particles with shear-free and expansion-free velocities in (L^-_n,g)- and Weyl's spaces

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    Conditions for the existence of flows with non-null shear-free and expansion-free velocities in spaces with affine connections and metrics are found. On their basis, generalized Weyl's spaces with shear-free and expansion-free conformal Killing vectors as velocity's vectors of spinless test particles moving in a Weyl's space are considered. The necessary and sufficient conditions are found under which a free spinless test particle could move in spaces with affine connections and metrics on a curve described by means of an auto-parallel equation. In Weyl's spaces with Weyl's covector, constructed by the use of a dilaton field, the dilaton field appears as a scaling factor for the rest mass density of the test particle. PACS numbers: 02.40.Ky, 04.20.Cv, 04.50.+h, 04.90.+eComment: 20 pages, LaTeX, to appear in Classical and Quantum Gravity. arXiv admin note: substantial text overlap with arXiv:gr-qc/001104

    Electrophysiological modeling in generalized epilepsy using surface EEG and anatomical brain structures

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    Deep brain structures involve significantly in the pathology of brain diseases such as epilepsy, Alzheimer, and Parkinson. Physiological brain modeling has become an emerging approach to investigate the coupling dynamics of the brain activity ofthese diseases. We propose a method using the surface EEG signals integrated with the anatomical individual brain to build the electrophysiological model of the epileptic patient’s brain. The EEG-driven model is used to investigate the deep brain activities of 23 patients diagnosed with generalized epilepsy from CHB-MIT Scalp EEG Database. Significant changes in the electrical activities in hippocampus, accumbens, amygdala, provide us insights into the dynamics ofactive brain regions during epilepsy. All of these brain regions show the significant energy variation defined by 5 features (Mean, Max, Min, Standard deviation, Power spectral density) with the p-value < 0.05 in both pre-ictal vs ictal and ictal vs post-ictal. Such result shows the potential of using EEG as a tool to capture the deep brain activity of epilepsy and other diseases that alter deep brain structures. The proposed model may be used to enhance the sensitivity of detecting and predicting epilepsy, detect the progression of the brain lesion, and support the decision-making for a brain medical intervention

    Depressive Symptoms and Amygdala Volume in Elderly with Cerebral Small Vessel Disease: The RUN DMC Study

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    Introduction. Late onset depressive symptoms (LODSs) frequently occur in elderly with cerebral small vessel disease (SVD). SVD cannot fully explain LODS; a contributing factor could be amygdala volume. We investigated the relation between amygdala volume and LODS, independent of SVD in 503 participants with symptomatic cerebral SVD. Methods. Patients underwent FLAIR and T1 scanning. Depressive symptoms were assessed with structured questionnaires; amygdala and WML were manually segmented. The relation between amygdala volume and LODS/EODS was investigated and adjusted for age, sex, intracranial volume, and SVD. Results. Patients with LODS had a significantly lower left amygdala volume than those without (P = 0.02), independent of SVD. Each decrease of total amygdala volume (by mL) was related to an increased risk of LODS (OR = 1.77; 95% CI 1.02–3.08; P = 0.04). Conclusion. Lower left amygdala volume is associated with LODS, independent of SVD. This may suggest differential mechanisms, in which individuals with a small amygdala might be vulnerable to develop LODS

    Frames of reference in spaces with affine connections and metrics

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    A generalized definition of a frame of reference in spaces with affine connections and metrics is proposed based on the set of the following differential-geometric objects: (a) a non-null (non-isotropic) vector field, (b) the orthogonal to the vector field sub space, (c) an affine connection and the related to it covariant differential operator determining a transport along the given non-null vector filed. On the grounds of this definition other definitions related to the notions of accelerated, inertial, proper accelerated and proper inertial frames of reference are introduced and applied to some mathematical models for the space-time. The auto-parallel equation is obtained as an Euler-Lagrange's equation. Einstein's theory of gravitation appears as a theory for determination of a special frame of reference (with the gravitational force as inertial force) by means of the metrics and the characteristics of a material distribution. PACS numbers: 0490, 0450, 1210G, 0240VComment: 17 pages, LaTeX 2
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