Recent spectroscopic findings concerning clay/water interactions at low humidity: Possible applications to models of Martian surface reactivity

A feasibility study assessing the utility of the adaptation of near infrared correlation spectroscopy to quantifying iron and adsorbed water in some clay-based Mars soil analog materials (MarSAM's). The work was intended to constitute Phase 1 of an approach to identifying optical analytical wavelength regions, not only for important mineral classes, but for chemically active centers within them. Many of these centers are common to unrelated mineral classes and of disproportionate influence relative to the mineral structure as a whole in determining the surface reactivity of mineral surfaces. We previously reported linearity between reflectance and total iron and total moisture over a large range of both key variables. We also discovered interesting relationships between the intensity of iron bands and the relative humidity of the systems. These relationships were confirmed. We also show that, in the low humidity range, reflectance is linearly dependent on a different kind of water from that best representing the full humidity range (the kind of water associated, in clays, with surface acidity). These relationships and the sensitivity and capability of quantitation of near infrared data indicate high promise with the production of reactive surface intermediates of products of surface reactions

A SEQUENTIAL CHOICE MODEL OF RECREATION BEHAVIOR

The travel cost model is the standard model used in the recreation demand literature. This model assumes that the decision on the number of trips to a particular site in a given period (a season, for example) is determined at the beginning of the period. For certain types of recreation activity, this decision may be more appropriately modeled as a sequential process, in which the decision of whether or not to take each additional trip is made after previous trips have occurred. This decision is dependent on the realization of random variables on previous trips as well as travel costs. A model is developed in which the choice of a discrete number of sequentially chosen trips to a given site is specified as function of site-specific variables and variables realized on previous trips. This models advantage over the traditional travel cost model is that it specifies discrete, nonnegative integer values for the number of trips and allows intraseasonal effects to determine the probability of taking each additional trip.Resource /Energy Economics and Policy,

Kaolinite-catalyzed air oxidation of hydrazine: Consideration of several compositional, structural and energetic factors in surface activation

Clay minerals have been shown to have numerous, curious, energetic properties by virtue of ultra-violet light release which can be triggered by gentle environmental changes such as wetting and dewetting by a variety of liquids, unique among them water and hydrazine. Since both water and hydrazine play multiple key roles in the air-oxidation of hydrazine on kaolinite surfaces, this reaction would seem to have prime potential for studying interrelationships of energy storage, release and chemical reactivity of clay surfaces, capacities basic to either the Bernal or Cairns-Smith roles of minerals in the origin of life. Establishment of the capacity for stored electronic energy to significantly alter surface chemistry is important, regardless of the reaction chosen to demonstrate it. Hydrazine air oxidation is overawingly complex, given the possibilities for step-wise control and monitoring of parameters. In the light of recently extended characterization of the kaolinite and model sheet catalysts we used to study hydrazine oxidation and gamma-irradiated silica, previous studies of hydrazine air-oxidation on aluminosilicate surfaces have been reevaluated. Our former conclusion remains intact that, whereas trace structural and surface contaminants do play some role in the catalysis of oxidation, they are not the only, nor even the dominant, catalytic centers. Initial intermediates in the oxidation can now be proposed which are consistent with production via O(-)-centers as well as ferric iron centers. The greater than square dependence of the initial reaction rate on the weight of the clay is discussed in the light of these various mechanistic possibilities

Spectroscopic analyses of Fe and water in clays: A Martian surface weathering study

Martian surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the Martian surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic studies of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification

Mental Workload as a Function of Traffic Density: Comparison of Physiological, Behavioral, and Subjective Indices

High traffic density can be expected to increase the attentional processing requirements of driving. Establishing methods of assessing the differential demands placed on drivers by environmental variables has been the focus of a recent series of investigations. Results of an initial examination of the impact of traffic density on mental workload are reported here. The current investigation utilizes an array of methodological assessment techniques and compares the sensitivity of each to changes in attentional processing requirements as a function of driving task demand. Analogous versions of a visual and auditory sensory detection task were developed and used in a dual task paradigm involving simulated driving. P300 amplitude, though in the predicted direction, failed to distinguish between increased task demands resulting from increases in traffic density. Response time and accuracy to the detection task in both visual and auditory modalities demonstrated significant processing decrements as a function of increased traffic density. Subjective workload ratings obtained from the NASA TLX did not distinguish between driving task difficulty, but indicated that performing the visual detection task in combination with driving was perceived as more difficult than performing the concurrent auditory task. Implications of these results for modeling differential aspects of mental workload and for establishing workload assessment techniques for surface transportation environments are discussed

SURVIVAL MECHANISMS OF PHYTOPATHOGENIC BACTERIA

Natural habitats usually do not provide bacteria the continuity of agricultural crops. With continuous culture. perpetuation of pathogen is no problem. Although agricul­ tural practices provide some discontinuity between crops. it is less than that in nature. Uniformity of crop germ plasm also favors inoculum buildup and perhaps perpetuation of the pathogens

Has Their Son Been Vaccinated? Beliefs About Other Parents Matter for Human Papillomavirus Vaccine

A quadrivalent vaccine against human papillomavirus (HPV; i.e., HPV4) was approved for use in males in 2009 for the prevention of genital warts (Centers for Disease Control & Prevention, 2010). Subsequently, in 2010, the Food and Drug Administration approved HPV4 vaccine for the prevention of anal cancer in both males and females (Food and Drug Administration, 2011). Although the Advisory Committee on Immunization Practices issued a recommendation that HPV4 vaccine should be routinely given to males aged 11–12 years in 2011 (Centers for Disease Control & Prevention, 2011), vaccination rates in young males have been slow to improve (Stokley et al., 2014). As of 2013, only about 35% of males ages 13–17 years had received at least one dose, and only 14% had completed the three-dose vaccine series (Stokley et al.)

Dissociable Aspects of Mental Workload: Examinations of the P300 ERP Component and Performance Assessments

Advanced technologies have enabled the choice of either visual or auditory formats for avionics and surface transportation displays. Methods of assessing the mental workload imposed by displays of different formats are critical to their successful implementation. Towards this end a series of investigations were conducted with the following aims: 1) developing analogous auditory and visual versions of a secondary task that could be used to compare display modalities; and 2) to compare the sensitivity of neurophysiological, behavioral and subjective indices of workload. Experiments 1 and 2 confirmed that analogous auditory and visual secondary oddball discrimination tasks were of equivalent difficulty as indicated by P300 amplitude, RT, accuracy and subjective ratings of workload. Experiments 1-3 revealed that RT and accuracy for target detections were generally more sensitive to changes in primary task difficulty than P300 responses and subjective ratings. However, Experiment 3 indicated that P300 amplitude was sensitive to increased perceptual demands (resulting from driving in heavy fog versus clear visibility) not revealed by changes in either behavioral or subjective indices. Together the results of the current investigations indicate that a battery of assessment techniques will provide the most sensitive assessment of workload in complex environments

Morphological and molecular characterisation of Scutellonema species from yam (Dioscorea spp.) and a key to the species of the genus

The yam nematode, Scutellonema bradys, is a major threat to yam (Dioscorea spp.) production across yam-growing regions. In West Africa, this species cohabits with many morphologically similar congeners and, consequently, its accurate diagnosis is essential for control and for monitoring its movement. In the present study, 46 Scutellonema populations collected from yam rhizosphere and yam tubers in different agro-ecological zones in Ghana and Nigeria were characterised by their morphological features and by sequencing of the D2-D3 region of the 28S rDNA gene and the mitochondrial COI genes. Molecular phylogeny, molecular species delimitation and morphology revealed S. bradys, S. cavenessi, S. clathricaudatum and three undescribed species from yam rhizosphere. Only S. bradys was identified from yam tuber tissue, however. For barcoding and identifying Scutellonema spp., the most suitable marker used was the COI gene. Additionally, 99 new Scutellonema sequences were generated using populations obtained also from banana, carrot, maize and tomato, including the first for S. paralabiatum and S. clathricaudatum, enabling the development of a dichotomous key for identification of Scutellonema spp. The implications of these results are discussed