The influence of leaf characteristics on epiphyllic cover : a test of hypotheses with artificial leaves

Studies of epiphyll ecology have been hindered by the biochemical and morphological variability of the leaf substrate. The use of artificial (plastic ribbon tape) leaves solved that problem in a study done at the Braulio Carrillo National Park, Costa Rica. It showed that after nine months of field exposure, relative epiphyll cover was similar in five leaf shapes and two sizes. Driptips do not affect epiphyll cover, which was four times higher under a clearing than in the shaded understory, for all leaf shapes and sizes

The two-phase model for calculating thermodynamic properties of liquids from molecular dynamics: Validation for the phase diagram of Lennard-Jones fluids

We propose a general approach for determining the entropy and free energy of complex systems as a function of temperature and pressure. In this method the Fourier transform of the velocity autocorrelation function, obtained from a short (20 ps) molecular dynamics trajectory is used to obtain the vibrational density of states (DoS) which is then used to calculate the thermodynamic properties by applying quantum statistics assuming each mode is a harmonic oscillator. This approach is quite accurate for solids, but leads to significant errors for liquids where the DoS at zero frequency, S(0), remains finite. We show that this problem can be resolved for liquids by using a two phase model consisting of a solid phase for which the DoS goes to zero smoothly at zero frequency, as in a Debye solid; and a gas phase (highly fluidic), described as a gas of hard spheres. The gas phase component has a DoS that decreases monotonically from S(0) and can be characterized with two parameters: S(0) and 3Ng, the total number of gas phase modes [3Ng0 for a solid and 3Ng3(N–1) for temperatures and pressures for which the system is a gas]. To validate this two phase model for the thermodynamics of liquids, we applied it to pure Lennard-Jones systems for a range of reduced temperatures from 0.9 to 1.8 and reduced densities from 0.05 to 1.10. These conditions cover the gas, liquid, crystal, metastable, and unstable states in the phase diagram. Our results compare quite well with accurate Monte Carlo calculations of the phase diagram for classical Lennard-Jones particles throughout the entire phase diagram. Thus the two-phase thermodynamics approach provides an efficient means for extracting thermodynamic properties of liquids (and gases and solids)

Durability of building envelope materials

This thesis is part of a series of documents that presents some research on different topics that are being conducted at The Durability Lab of The University of Texas consisting of groundbreaking research focused on the durability of building envelope materials used in construction. Behavior of stucco was analyzed when different construction joint configurations were used, Strict and Compromise cases (accepted by the ASTM standard) and Usual case (often used in construction). These cases were used, in a wall constructed at the exposure site at The University of Texas Pickle Research Campus to compare the joint opening widths due to temperature and weather conditions by installing gage points on both sides of the construction joints. Water-resistive barrier testing is ongoing as well as nail sealability testing, observations on the performance of products exposed on mockups are being made and the new implementation of the ASTM D7349, Standard Test Method for Determining the Capability of Roofing and Waterproofing Materials to Seal around Fasteners, regarding nail sealability is presented. Building sealants are crucial when avoiding water to get inside buildings through the perimeters of doors and windows principally. Long-term testing is being done based on ASTM C1589, Standard Practice for Outdoor Weathering of Construction Seals and Sealants Procedure C, and important trends are presented after observation and data analysis of the gathered information. Important takeaways from water-repellent testing are listed considering the behavior and performance of water-repellents based on the effects of UV radiation and weather conditions, as well as the active component and the type of water-repellent. Construction tapes and flashings are vital in many water-resistive barrier systems, since they seal around all penetrations to provide a complete waterproofing system. Test of construction tapes and flashings has been performed mainly based on ASTM D3654, Standard Test Methods for Shear Adhesion of Pressure-Sensitive Tapes, considering different types of tapes and different substrates. Lastly, the effect of surfactants on the performance of building paper were observed, two different conditions were evaluated: the presence of surfactants on stucco mixes and admixtures, and the presence of surfactants on detergents and soaps used to clean the outer part of buildings. Some other, but no less important research topics, are ongoing, including properties of plaster mixtures, pedestrian membranes, and elastomeric wall coatings.Civil, Architectural, and Environmental Engineerin

Notes on the natural history of Cyclopogon obliquus (Orchidaceae: Spiranthinae) in Costa Rica

University of Miami/[]//Estados UnidosAndrew W. Mellon Foundation/[]//Estados UnidosOrganization for Tropical Studies/[]/OTS/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

High voltage and high specific capacity dual intercalating electrode Li-ion batteries

The present invention provides high capacity and high voltage Li-ion batteries that have a carbonaceous cathode and a nonaqueous electrolyte solution comprising LiF salt and an anion receptor that binds the fluoride ion. The batteries can comprise dual intercalating electrode Li ion batteries. Methods of the present invention use a cathode and electrode pair, wherein each of the electrodes reversibly intercalate ions provided by a LiF salt to make a high voltage and high specific capacity dual intercalating electrode Li-ion battery. The present methods and systems provide high-capacity batteries particularly useful in powering devices where minimizing battery mass is important

A new species of Stellilabium section Taeniorhachis (Orchidaceae) from Costa Rica

The new species Stellilabium smaragdinum is described and illustrated from the montane oak forests of the Cordillera de Talamanca, Costa Rica. Among the species of Sect. Taeniorhachis, S. smaragdinum may be recognized for the inflorescence bearing 1-3 (4) simultaneous flowers, the oblong to ovoid, rounded basal lobules of the lip, the non-ciliate margins of the lip midlobe and the peculiar colour of the column setae, cream banded with purple.Se describe e ilustra Stellilabium smaragdinum de los bosques montanos de encino de la Cordillera de Talamanca. S. smaragdinum se distingue de otras especies de la sección Taeniorhachis por su inflorescencia con 1 a 3 (4) flores simultáneas, los lóbulos basales del labelo oblongos a ovoides y redondeados en el ápice y la peculiar coloración de la setas en los lóbulos laterales de la columna, marfil con bandas púrpura.Organization for Tropical Studies/[]/OTS/Estados UnidosAndrew W. Mellon Foundation/[]//Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

The rise and development of parenthetical needless to say: An assumed evidential strategy

The article traces the diachronic development of the assumed evidential needless to say. This parenthetical expression allows the speaker to make certain assertions regarding the obviousness of what s/he is about to say, thus serving as an evidential strategy that marks the information conveyed as being based on inference and/or assumed or general knowledge. Parenthetical needless to say has its roots in the Early Modern English needless to-INF construction (meaning ‘it is unnecessary to do something’), which originally licensed a wide range of infinitives. Over the course of time, however, it became restricted to uses with utterance verbs, eventually giving rise to the grammaticalized evidential expression needless to say. In fact, it is only in Late Modern English that the evidential pragmatic inferences become conventionalized and that the first parenthetical uses of the construction are attested. In Present-day English, parenthetical needless to say occurs primarily at the left periphery with forward scopeS

Elucidation of the dynamics for hot-spot initiation at nonuniform interfaces of highly shocked materials

The fundamental processes in shock-induced instabilities of materials remain obscure, particularly for detonation of energetic materials. We simulated these processes at the atomic scale on a realistic model of a polymer-bonded explosive (3,695,375 atoms/cell) and observed that a hot spot forms at the nonuniform interface, arising from shear relaxation that results in shear along the interface that leads to a large temperature increase that persists long after the shock front has passed the interface. For energetic materials this temperature increase is coupled to chemical reactions that lead to detonation. We show that decreasing the density of the binder eliminates the hot spot