Geochemical support for a climbing habit within the Paleozoic seed fern genus Medullosa

A long-standing problem in paleobotany is the accurate identification of the growth habits and statures of fossil plants. Tissue-specific analysis of stable carbon isotope ratios in plant fossils can provide an independent perspective on this issue. Lignin, a fundamental biopolymer providing structural support in plant tissues and the second most abundant organic material in plants, is ^(13)C depleted by several parts per thousand, averaging 4.1‰, relative to other plant constructional materials (e.g. cellulose). With this isotopic difference, the biochemical structural composition of ancient plants (and inferred stature) can be interrogated using microscale in situ isotope analysis between different tissues in fossils. We applied this technique to a well-preserved specimen of the Late Paleozoic seed plant Medullosa, an extinct genus with a variety of growth habits that includes several enigmatic yet abundant small-stemmed species widely found in calcium carbonate concretions (“coal balls”) in the Pennsylvanian coal beds of Iowa, USA. It remains unclear which of the medullosans were freestanding, and recent analysis of the medullosan vascular system has shown that this system provided little structural support to the whole plant. The leading hypothesis for small-stemmed medullosan specimens predicts that cortical tissues could have provided additional structural support, but only if they were lignified. The expected isotopic difference between lignified tissue and unlignified tissue is smaller than that expected from pure extracts, for the simple reason that even woody tissues maximally contain 40% lignin (by mass). This reduces the expected maximum difference between weakly and heavily lignified tissues by 60%, down to ~0.5‰–2‰. Analysis of the medullosan stem reveals a consistent difference in isotope ratios of 0.7‰–1.0‰ between lignified xylem and cortical tissues. This implies low abundances of lignin (between 0% and 11%) within the cortex. This inferred structural biochemistry supports hypotheses that the peripheral portions of these medullosan stems were not biomechanically reinforced to permit the plants to grow as freestanding, arborescent trees. A number of climbing or scandent medullosans have been identified in the fossil record, and this mode of growth has been suggested to be common within the group on the basis of observations from comparative biomechanics, hydraulics, and development. Finally, this mode of growth is common in several clades of stem group seed plants, including Lyginopteris and Callistophyton, along with Medullosa. This study provides further support for ideas that place a great portion of early seed plant diversity under the canopy, rather than forming it

Genetic Variation in Resistance of Scotch Pine to Zimmerman Pine Moth

(excerpt) Scotch pine (Pinus sylvestris L.), a forest tree introduced from Eurasia, is commonly planted for Christmas tree and timber use in northeastern United States. In this country it has numerous insect enemies. Among the most important are European pine shoot moth, Rhyacionia buoliana (Schiffermiieller); pine root collar weevil, Hylobius radicis Buchanan;,European pine sawfly, Neodiprion sertifer (Geoffroy); and eastern white-pine shoot borer, Eucosma gloriola Heinrich. Previous studies (Wright et al., 1967; Wright and Wilson, 1972; Steiner, 1974) have revealed large genetic differences in resistance to some of these pests. Another destructive pest is the Zimmerman pine moth, Dioryctria zimmermani (Grote). In 1968 this insect, native to the United States, was found attacking trees in a Scotch pine provenance test in southwestern Michigan. The attack rate was heavy and by 1973 it was obvious that some rams or varieties were attacked more heavily than others. This is a report on those differences

ISOTOPIC AND GEOCHEMICAL TRACERS OF GROUNDWATER FLOW IN THE SHIVWITS PLATEAU, GRAND CANYON NATIONAL PARK

As the impacts of global climate change on water resources continue to become more apparent, proper understanding and management of groundwater resources will be needed as supplies become more strained. Traditional methods of characterizing groundwater systems are time-intensive, costly, and can be difficult to complete in remote areas. Using ambient geochemical tracers from discrete sampling could aid in characterizing spring systems through determining flow paths, recharge areas, and carbon cycling. However, using discrete seasonal samples to understand the hydrogeology of complex, mixed-lithology aquifers has not been extensively examined. Here we explore using δ13C of dissolved organic carbon (DOC), δ13C of dissolved inorganic carbon (DIC) and fluorescent dissolved organic matter (fDOM), together with water isotopes, major ions, and geochemical modeling, to characterize springs of the Shivwits Plateau in Grand Canyon National Park. Values of carbon isotopes and fDOM for all springs reflect source values for regional surface vegetation and heterotrophic degradation of terrestrial DOM. Principal component analyses show that springs can be grouped into four groups by geochemical variability: 1) a shallow epikarst system, 2) a flow path through gypsiferous beds of the Toroweap Formation on the eastern side of the plateau, 3) a short, canyon slope runoff-dominated flow path through the Supai Group, and 4) a deeper complex flow system in the Redwall Limestone with characteristics of all other flow systems, which indicates mixing. Results show that the methods used can provide a simple conceptual model of a complex groundwater system, but higher–resolution spatial and temporal data are needed to fully understand changes resulting from changing climate. As appropriations from the Colorado River already exceed its annual streamflow and the regional climate is predicted to become more arid, characterizing groundwater resources for water supply will be paramount for the region as well as in other areas that will experience similar transitions

Recombinase polymerase amplification for fast, selective, DNA‐based detection of faecal indicator Escherichia coli

The bacterium Escherichia coli is commonly associated with the presence of faecal contamination in environmental samples, and is therefore subject to statutory surveillance. This is normally done using a culture‐based methodology, which can be slow and laborious. Nucleic acid amplification for the detection of E. coli DNA sequences is a significantly more rapid approach, suited for applications in the field such as a point of sample analysis, and to provide an early warning of contamination. An existing, high integrity qPCR method to detect the E. coli ybbW gene, which requires almost an hour to detect low quantities of the target, was compared with a novel, isothermal RPA method, targeting the same sequence but achieving the result within a few minutes. The RPA technique demonstrated equivalent inclusivity and selectivity, and was able to detect DNA extracted from 100% of 99 E. coli strains, and exclude 100% of 30 non‐target bacterial species. The limit of detection of the RPA assay was at least 100 target sequence copies. The high speed, and simple, isothermal amplification chemistry may indicate that RPA is a more suitable methodology for on‐site E. coli monitoring than an existing qPCR technique

Effect of Recruitment and Selection of Employees on the Performance of Small and Medium Enterprises in Kisumu Municipality, Kenya

The study investigated the effect recruitment and selection on the performance of SMEs in Kisumu Municipality, Kenya. Kenya has 1.6 million SMEs, constituting 96% of business enterprises, employing 75% of the labor force and contributing 20% to GDP. But their performance has been poor in the last decade. Hence the need to determine the suitable recruitment and selection strategies that could increase their performance. The study found that the overall average performance of SMEs in Kisumu Municipality was 60.71%. There was a significant positive correlation between recruitment and selection, and performance of SMEs at ? = .01. The average performance of SMEs with good recruitment and selection was 81.90%; with moderate was 67.94%, with poor was 53.90%. Recruitment and selection account for 40.8% of the total variance in performance of SMEs. The study concludes that recruitment and selection has a significant effect on the performance of SMEs in Kisumu Municipality. Key Words : Recruitment, selection, performance, SMEs, Kisumu, sourcing, attracting, screenin

Influence of Legal Requirements on Environmental Concern and sustainability Practices in Small and Medium-size Manufacturing Enterprises in Nairobi, Kenya.

Until recently it has been too easy to overlook Small and Medium-size Enterprises in the analysis of environmental impact of particularly the manufacturing sector (ibid 2003). SMEs continue to grow, so do their environmental impacts. SMEs are faced by such challenges as difficulty in raising capital, limited managerial skills, regulatory constraints, limited extension services and difficulty in getting access to technology The study found out that SMEs where copies of environment related laws existed and staffs were aware of the laws, respondents indicated involvement in environmental management practices. It is thus concluded that legal provisions influenced adoption of good environmental management practices by Small and Medium-size Manufacturing enterprises. Key words: Legal Requirements. Environmental Concern. Sustainability Practice

Nutrient Digestibility of Condensed Algal Residue Solubles in Beef Cattle Fishing Diets

Condensed algal residue solubles (CARS) were evaluated in finishing cattle diets. Six treatments were evaluated (2 × 3 factorial arrangement), CARS inclusion in the diet at 0, 5, or 10% of diet dry matter with 0 or 20% wet distillers grains. Th e remainder of the diets consisted of 57.5– 87.5% dry rolled corn, 7.5% sorghum silage and 5% supplement. Increasing wet distillers grains in the diet had no effect on dry matter and organic matter intake but decreased dry matter and organic matter digestibility. Increasing CARS inclusion in the diet resulted in lower dry matter and organic matter intake with no effect on dry matter and organic matter digestibility. Replacing up to 10% dry rolled corn with CARS in diets with or without wet distillers grains had little effect on digestibility of finishing beef cattle diets

Four hundred million years of silica biomineralization in land plants

Biomineralization plays a fundamental role in the global silicon cycle. Grasses are known to mobilize significant quantities of Si in the form of silica biominerals and dominate the terrestrial realm today, but they have relatively recent origins and only rose to taxonomic and ecological prominence within the Cenozoic Era. This raises questions regarding when and how the biological silica cycle evolved. To address these questions, we examined silica abundances of extant members of early-diverging land plant clades, which show that silica biomineralization is widespread across terrestrial plant linages. Particularly high silica abundances are observed in lycophytes and early-diverging ferns. However, silica biomineralization is rare within later-evolving gymnosperms, implying a complex evolutionary history within the seed plants. Electron microscopy and X-ray spectroscopy show that the most common silica-mineralized tissues include the vascular system, epidermal cells, and stomata, which is consistent with the hypothesis that biomineralization in plants is frequently coupled to transpiration. Furthermore, sequence, phylogenetic, and structural analysis of nodulin 26-like intrinsic proteins from diverse plant genomes points to a plastic and ancient capacity for silica accumulation within terrestrial plants. The integration of these two comparative biology approaches demonstrates that silica biomineralization has been an important process for land plants over the course of their >400 My evolutionary history

Synchronized Position Hold, Engage, Reorient, Experimental Satellites

Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) are bowling-ball sized spherical satellites. They will be used inside the space station to test a set of well-defined instructions for spacecraft performing autonomous rendezvous and docking maneuvers. Three free-flying spheres will fly within the cabin of the station, performing flight formations. Each satellite is self-contained with power, propulsion, computers and navigation equipment. The results are important for satellite servicing, vehicle assembly and formation flying spacecraft configurations. SPHERES is a testbed for formation flying by satellites, the theories and calculations that coordinate the motion of multiple bodies maneuvering in microgravity. To achieve this inside the ISS cabin, bowling-ball-sized spheres perform various maneuvers (or protocols), with one to three spheres operating simultaneously . The Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) experiment will test relative attitude control and station-keeping between satellites, re-targeting and image plane filling maneuvers, collision avoidance and fuel balancing algorithms, and an array of geometry estimators used in various missions. SPHERES consists of three self-contained satellites, which are 18 sided polyhedrons that are 0.2 meter in diameter and weigh 3.5 kilograms. Each satellite contains an internal propulsion system, power, avionics, software, communications, and metrology subsystems. The propulsion system uses CO2, which is expelled through the thrusters. SPHERES satellites are powered by AA batteries. The metrology subsystem provides real-time position and attitude information. To simulate ground station-keeping, a laptop will be used to transmit navigational data and formation flying algorithms. Once these data are uploaded, the satellites will perform autonomously and hold the formation until a new command is given