A handbook of Nebraska grasses : with illustrated keys for their identification, together with a general account of their structure and economic importance

The true grasses belong to the one family Poaceae, often called Gramineae, and constitute a very well defined natural group of plants. This family comprises upward of 3,000 species distributed among almost 300 genera. From the economic point of view the family is of supreme importance thru the fact that here belong the cereals, which supply a large part of the food of man, and the forage grasses which are so important as feed for our domesticated animals. The genera and species are for the most part separated by artificial characters—a fact which renders their study and identification extremely difficult even for the expert. The experience of the authors has convinced them that much of this difficulty is to be credited to the keys found in our common manuals. Theoretically a key is intended to assist one in properly identifying a plant, but actually many of the keys, upon close inspection. are found to contain so many vague and contradictory statements that they can be depended upon only by the expert who, on account of his working knowledge, makes slight use of the keys. It occurred to the senior author some years ago that an illustrated key might solve many of these difficulties. An accurate illustration conveys a more definite idea of any particular structure and leaves less room for doubt than any number of words. In fact, the serious and annoying inaccuracies of most keys to the grasses became more and more apparent as the work of preparing the illustrations progressed. The authors are fully convinced that illustrated keys of the type here employed will prove useful in many other groups of plants. The nomenclature here employed is largely that of the seventh edition of Gray\u27s Manual—tho our purpose has not been to insist upon any particular name but to provide means whereby the student can with some certainty attach to any given plant some one name which has been properly authorized. The present key includes most of the species known to occur in Nebraska, tho a few of minor importance and very restricted distribution have been omitted. There are provided also some data on the economic value of certain of the most important species. The illustrations for the grass keys have been drawn expressly for this publication. They are derived in part from actual authentic specimens and in part redrawn in modified form from various manuals and monographs. T he authors have made free use of the manuals, monographs. etc., included in the Bibliography and take this opportunity to commend these publications to the attention of all who wish to learn more of our common grasses. It is hoped that the keys here presented will facilitate the study of the grass flora of Nebraska by farmers and students

Field-induced paramagnons at the metamagnetic transition in Ca1.8Sr0.2RuO4

The magnetic excitations in Ca1.8Sr0.2RuO4 were studied across the metamagnetic transition and as a function of temperature using inelastic neutron scattering. At low temperature and low magnetic field the magnetic response is dominated by a complex superposition of incommensurate antiferromagnetic fluctuations. Upon increasing the magnetic field across the metamagnetic ransition, paramagnon and finally well-defined magnon scattering is induced, partially suppressing the incommensurate signals. The high-field phase in Ca1.8Sr0.2RuO4 has, therefore, to be considered as an intrinsically ferromagnetic state stabilized by the magnetic field

Rising Level of Public Exposure to Mobile Phones: Accumulation through Additivity and Reflectivity

A dramatic development occurring in our daily life is the increasing use of mobile equipment including mobile phones and wireless access to the Internet. They enable us to access several types of information more easily than in the past. Simultaneously, the density of mobile users is rapidly increasing. When hundreds of mobile phones emit radiation, their total power is found to be comparable to that of a microwave oven or a satellite broadcasting station. Thus, the question arises: what is the public exposure level in an area with many sources of electromagnetic wave emission? We show that this level can reach the reference level for general public exposure (ICNIRP Guideline) in daily life. This is caused by the fundamental properties of electromagnetic field, namely, reflection and additivity. The level of exposure is found to be much higher than that estimated by the conventional framework of analysis that assumes that the level rapidly decreases with the inverse square distance between the source and the affected person. A simple formula for the exposure level is derived by applying energetics to the electromagnetic field. The formula reveals a potential risk of intensive exposure.Comment: 5 pages, 1 fugure; to appear in J. Phys. Soc. Jpn. Vol.71 No.2 in Feb 200

Multipole tensor analysis of the resonant x-ray scattering by quadrupolar and magnetic order in DyB2C2

Resonant x-ray scattering (RXS) experiment has been performed for the (3 0 1.5) superlattice reflection in the antiferroquadrupolar and antiferromagnetic phase of DyB2C2. Azimuthal-angle dependence of the resonance enhanced intensities for both dipolar (E1) and quadrupolar (E2) resonant processes has been measured precisely with polarization analysis. Every scattering channel exhibits distinctive azimuthal dependence, differently from the symmetric reflection at (0 0 0.5) which was studied previously. We have analyzed the results using a theory developed by Lovesey et al., which directly connects atomic tensors with the cross-section of RXS. The fitting results indicate that the azimuthal dependences can be explained well by the atomic tensors up to rank 2. Rank 3 and rank 4 tensors are reflected in the data very little. In addition, The coupling scheme among the 4f quadrupolar moment, 5d ortitals, and the lattice has been determined from the interference among the Thomson scattering from the lattice distortion and the resonant scatterings of E1 and E2 processes. It has also been established from the RXS of the (3 0 1.5) reflection that the canting of the 4f quadrupolar moments exists up to T_Q. We also discuss a possible wavefunction of the ground state from the point-charge model calculation.Comment: 9 pages, 10 figure

The Extended Shapes of Galactic Satellites

We are exploring the extended stellar distributions of Galactic satellite galaxies and globular clusters. For seven objects studied thus far, the observed profile departs from a King function at large r, revealing a ``break population'' of stars. In our sample, the relative density of the ``break'' correlates to the inferred M/L of these objects. We discuss opposing hypotheses for this trend: (1) Higher M/L objects harbor more extended dark matter halos that support secondary, bound, stellar ``halos''. (2) The extended populations around dwarf spheroidals (and some clusters) consist of unbound, extratidal debris from their parent objects, which are undergoing various degrees of tidal disruption. In this scenario, higher M/L ratios reflect higher degrees of virial non-equilibrium in the parent objects, thus invalidating a precept underlying the use of core radial velocities to obtain masses.Comment: 8 pages, including 2 figures Yale Cosmology Workshop: The Shapes of Galaxies and Their Halo

Metacognition in human decision-making: confidence and error monitoring

People are capable of robust evaluations of their decisions: they are often aware of their mistakes even without explicit feedback, and report levels of confidence in their decisions that correlate with objective performance. These metacognitive abilities help people to avoid making the same mistakes twice, and to avoid overcommitting time or resources to decisions that are based on unreliable evidence. In this review, we consider progress in characterizing the neural and mechanistic basis of these related aspects of metacognition—confidence judgements and error monitoring—and identify crucial points of convergence between methods and theories in the two fields. This convergence suggests that common principles govern metacognitive judgements of confidence and accuracy; in particular, a shared reliance on post-decisional processing within the systems responsible for the initial decision. However, research in both fields has focused rather narrowly on simple, discrete decisions—reflecting the correspondingly restricted focus of current models of the decision process itself—raising doubts about the degree to which discovered principles will scale up to explain metacognitive evaluation of real-world decisions and actions that are fluid, temporally extended, and embedded in the broader context of evolving behavioural goals

Rank rigidity for CAT(0) cube complexes

We prove that any group acting essentially without a fixed point at infinity on an irreducible finite-dimensional CAT(0) cube complex contains a rank one isometry. This implies that the Rank Rigidity Conjecture holds for CAT(0) cube complexes. We derive a number of other consequences for CAT(0) cube complexes, including a purely geometric proof of the Tits Alternative, an existence result for regular elements in (possibly non-uniform) lattices acting on cube complexes, and a characterization of products of trees in terms of bounded cohomology.Comment: 39 pages, 4 figures. Revised version according to referee repor

Microscopic theory of quadrupolar ordering in TmTe

We have calculated the crystal electric field of TmTe (T>T_Q) and have obtained that the ground state of a Tm 4f hole is the $\Gamma_7$ doublet in agreement with Mossbauer experiments. We study the quadrupole interactions arising from quantum transitions of 4f holes of Tm. An effective attraction is found at the L point of the Brillouin zone, $\vec{q}_L$. Assuming that the quadrupolar condensation involves a single arm of $\vec{q}_L$ we show that there are two variants for quadrupole ordering which are described by the space groups C2/c and C2/m. The Landau free energy is derived in mean-field theory. The phase transition is of second order. The corresponding quadrupole order parameters are combinations of $T_{2g}$ and $E_g$ components. The obtained domain structure is in agreement with observations from neutron diffraction studies for TmTe. Calculated lattice distortions are found to be different for the two variants of quadrupole ordering. We suggest to measure lattice displacements in order to discriminate between those two structures.Comment: 10 pages, 2 figures, 5 tables; accepted by PR

Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER Observations of Elements 26_{26}Fe through 40_{40}Zr

We report abundances of elements from $_{26}$Fe to $_{40}$Zr in the cosmic radiation measured by the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument during 55 days of exposure on a long-duration balloon flight over Antarctica. These observations resolve elemental abundances in this charge range with single-element resolution and good statistics. These results support a model of cosmic-ray origin in which the source material consists of a mixture of 19$^{+11}_{-6}$\% material from massive stars and $\sim$81\% normal interstellar medium (ISM) material with solar system abundances. The results also show a preferential acceleration of refractory elements (found in interstellar dust grains) by a factor of $\sim$4 over volatile elements (found in interstellar gas) ordered by atomic mass (A). Both the refractory and volatile elements show a mass-dependent enhancement with similar slopes.Comment: 9 pages, 12 figures, 2 tables, accepted by Ap