JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The University of Notre Dame is collaborating with JSTOR to digitize, preserve and extend access to American Midland Naturalist.ABSTRACT: The effects of soil moisture and temperature on arthropod communities were experimentally examined in the northern Chihuahuan Desert of New Mexico. Shaded plots were established which lowered the soil temperature several degrees; some plots received artificial rainfall to increase soil moisture. Shading reduced soil temperature at 5-cm depth 7-10 C.Soil moisture at 5 cm accounted for most of the variation in surface activity of subterranean termites (r values between 0.3 and 0.7). Termites did not respond to temperature differences. When all soils were at field capacity, there was no difference in termite activity in shaded and unshaded plots. There were higher densities of microarthropods in litter bags on the shaded plots than on the unshaded plots. Numbers of microarthropods were an order of magnitude larger in litter bags on watered and shaded plots than on other plots. Lower litter temperatures apparently affect litter arthropods more than increased soil moisture. Shade had no effect on ant colonies but there were fewer colonies on the watered plots.There was between 40 to 50% mass loss from creosotebush leaf litter after 7 months on all plots. Water and soil temperature had no effect on decomposition rates.

Trypanosomatids recently isolated from the plants Euphorbia pinea, E. characias, E. hyssopifolia, Manihoi esculenta (cassava) and Lycopersicon sp. (tomato) plus the McGhee‐Postell isolate of Phytomonas davidi have been examined for the presence of enzymes of ornithine‐arginine metabolism. Arginase (EC 3.5.3.1) was not detected in the flagellates examined whereas arginine deiminase (EC 3.5.3.6) and citrullinehydrolase (EC 3.5.1.20) were present in all organisms. Phytomonas davidi and the isolate from E. hyssopifolia, besides these enzymes, also had ornithine carbamoyltransferase (EC 2.1.3.3). The enzymic constitution of these flagellates is compared from a taxonomic standpoint to that of previously studied trypanosomatids.

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1. Reproductive strategies of four species of oribatid mites were investigated in the Chihuahuan Desert from 1981 to 1984. 2. Breeding activity coincided with the summer rainfall period in three of the four cases: Passalozetes neomexicanus, P. californicus and Jornadia larreae. This pattern was not changed by the application of simulated rainfall at other times of the year. The strict seasonality of reproductive behaviour is interpreted as an outcome of strong selection pressure to recruit only when food quality and quantity and microclimate are most favourable. 3. Joshuella striata showed a more flexible pattern which was essentially bimodal. Periods of egg production occurred in winter and also during the summer rainfall period. This pattern is consistent with the known distribution of this species in winter‐ and summer‐rainfall deserts in south‐western USA.

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Trapping light in open cavities is a long sought "holy grail" of nanophotonics. Plasmonic materials may offer a unique opportunity in this context, as they may fully suppress the radiation loss and enable the observation of spatially localized light states with infinite lifetime in an open system. Here, we investigate how the spatial dispersion effects, e.g., caused by the electron-electron interactions in a metal, affect the trapped eigenstates.Heuristically, one may expect that the repulsive-type electron-electron interactions should act against light localization, and thereby that they should have a negative impact on the formation of the embedded eigenstates. Surprisingly, here we find that the nonlocality of the material response creates new degrees of freedom and relaxes the requirements for the observation of trapped light. In particular, a zero-permittivity condition is no longer mandatory and the same resonator shell can potentially suppress the radiation loss at multiple frequencies.

We investigate the potentials of open plasmonic resonators (meta‐atoms) with different shapes in the context of light trapping. Consistent with the theory of Silveirinha (2014), it is found that in some conditions complex‐shaped dielectric cavities may support discrete light states screened by volume plasmons that in the limit of vanishing material loss have an infinite lifetime. The embedded eigenstates can be efficiently pumped with a plane wave excitation when the meta‐atom core has a nonlinear response, such that the trapped light energy is precisely quantized.

Introduction: Magnetic resonance imaging is recognized as the most important diagnostic test in the diagnosis of multiple sclerosis, differential diagnosis and evaluation of progression/therapeutic response. However, to make optimal use of magnetic resonance imaging in multiple sclerosis, the use of a standard, reproducible and comparable imaging protocol is of uttermost importance. In this context, the Portuguese Society of Neuroradiology and the Group of Studies of Multiple Sclerosis, after a joint discussion, appointed a committee of experts to create recommendations adapted to the national reality on the use of magnetic resonance imaging in multiple sclerosis. This document represents the second part of the first Portuguese consensus recommendations on the use of magnetic resonance imaging in multiple sclerosis in clinical practice.Material and Methods: The Portuguese Society of Neuroradiology and the Group of Studies of Multiple Sclerosis, after discussing the topic in national meetings and after a working group meeting held in Figueira da Foz, May 2017, appointed a committee of experts that have developed several standard protocols on the use of magnetic resonance imaging on multiple sclerosis by consensus. The document obtained was based on the best scientific evidence and expert opinion. Portuguese multiple sclerosis consultants and departments of neuroradiology scrutinized and reviewed the consensus paper; comments and suggestions were considered. Standardized strategies of magnetic resonance imaging referral in clinical practice for diagnosis and follow-up of multiple sclerosis were published in the first part of this paper.Results: We provide magnetic resonance imaging acquisition protocols regarding multiple sclerosis diagnostic and monitoring and the information to be included in the report for application across Portuguese healthcare institutions.Conclusion: We hope that these first Portuguese magnetic resonance imaging guidelines will contribute to optimize multiple sclerosis management and improve patient care in Portugal.