Intercept Data Research Articles

Haptic processing of the location of a known property: does knowing what you've touched tell you where it is?

The relationship between knowing where a haptic property is located and knowing what it is was investigated using a haptic-search paradigm. Across trials, from one to six stimuli were presented simultaneously to varying combinations of the middle three fingertips of both hands. Participants reported the presence/absence of a target or its location for four perceptual dimensions: rough/smooth, edge/no edge, relative position (right/left), and relative orientation (right/left). Reaction time data were plotted as a function of set size. The slope data indicated no difference in processing load for location as compared to identity processing. However, the intercept data did reveal a cost associated with processing location information. Location information was not obtained for "free" when identity was processed. The data also supported a critical distinction between material and edge dimensions versus geometric dimensions, as the size of the cost associated with processing location was larger for spatial than for intensive stimuli.

More efficient estimation of plant biomass

Abstract Question: The optimal use of the point intercept method (PIM) for efficient estimation of plant biomass has not been addressed although PIM is a commonly used method in vegetation analysis. In this study we compare results achieved using PIM at a range of efforts, we assess a method for calculating these results that are new with PIM and we provide a formula for planning the optimal use of PIM. Location: Northern Norway. Methods: We collected intercept data at a range of efforts, i.e. from one to 100 pins per 0.25 m2 plots, on three plant growth forms in a mountain meadow. After collection of intercept data we clipped and weighed the plant biomass. The relationship between intercept frequency and weighed biomass (b) was estimated using both a weighted linear regression model (WLR) and an ordinary linear regression model (OLR). The accuracy of the estimate of biomass achieved by PIM at different efforts was assessed by running computer simulations at different pin densities. Results: The relations...

Fungal colonization of shrub willow roots at the forefront of a receding glacier.

Shrub willows ( Salix spp.) form associations with arbuscular mycorrhizal (AM), ectomycorrhizal (EM) and dark septate endophytic (DSE) fungi. Willow root colonization by these three types of fungi was studied on a deglaciated forefront of Lyman Glacier, Washington, USA. Root colonization was low; less than 1% of the root length was colonized by AM and 25.6% by DSE. EM colonized 25% of the root tips and 19.4% of the root length. AM and DSE colonization were not related to distance from the present glacier terminus or to canopy cover. EM colonization increased with distance from the glacier terminus based on gridline intercept data but not on root tip frequency data. Availability of propagules in the substrate was low, but numbers of propagules increased with distance from the glacier terminus. The EM communities were dominated by three ascomycetes showing affinity to Sordariaceae in BLAST analyses. Other frequent taxa on the glacier forefront included species of Cortinariaceae, Pezizaceae, Russulaceae, Thelephoraceae and Tricholomataceae. When occurrence of individual taxa was used as a response variable to canopy cover, distance from the glacier terminus, and their interaction, four different fungal guilds were identified: 1) fungi that did not respond to these environmental variables; 2) fungi that occurred mainly in intercanopy areas and decreased with distance from the glacier terminus; 3) fungi that were insensitive to canopy cover but increased with distance from the glacier terminus; 4) fungi that occurred mainly under willow canopies and increased with distance from the glacier terminus. We suggest that fungal colonization is mainly limited by fungal propagule availability. Environmental conditions may also limit successful establishment of plant-fungus associations. We propose that the four EM guilds partly explain successional dynamics. The initial EM community comprises fungi that tolerate low organic matter and nitrogen environment (first and second guilds above). During later community development, these fungi are replaced by those that benefit from an increased organic matter and nitrogen environment (third and fourth guilds above).

Mimicking Cox-Regression

A class of objective functions, related to the Cox partial likelihood, that generates unbiased estimating equations is proposed. These equations allow for estimation of interest parameters when nuisance parameters are proportional to expectations. Examples of the objective functions are applied to binary data with a log-link in three situations: independent observations, independent groups of observations with common random intercept and discrete survival data. It is pointed out that the Peto–Breslow approximation to the partial likelihood with discrete failure times fits a conditional model with a log-link.

Lay beliefs about high blood pressure in a low- to middle-income urban African-American community: an opportunity for improving hypertension control

PurposeLay beliefs about illness are a potential barrier to improving the control of hypertension. We investigated the extent to which lay beliefs about hypertension diverge from current medical understanding. MethodsWe conducted street intercept interviews and focus group discussions in six predominantly African-American census tracts in the southern sector of Dallas County, Texas. Sixty subjects, aged 18 to 67 years, were stopped along popular thoroughfares and administered a brief survey. Additionally, 107 participants were interviewed in 12 homogeneous focus groups, balanced by sex and age (18 to 74 years). Participants were asked about the meaning, causes, consequences, and treatment of high blood pressure. ResultsThe street intercept data indicated that 35% (n = 21) of respondents related high blood pressure to eating pork or other foods that makes the blood travel too fast to the head, and only 15% (n = 9) related hypertension to an elevated pressure in blood vessels. The focus group data indicated that hypertension was causally linked to eating pork in 8 of the 12 groups; was perceived as a symptomatic illness in all 12 groups; and was considered treatable with vitamins, garlic, and other herbs in 11 groups, with prescription medications in 10 groups and with lifestyle modifications such as weight loss in 8 groups. Hypertension was mentioned as a leading cause of death among African Americans in none of the 4 focus groups of 18-year-old to 29-year-old participants, in 2 of the 4 focus groups of 30-year-old to 49-year-old participants, and in 3 of the 4 focus groups of 50-year-old to 74-year-old participants. ConclusionsIn a low- to middle-income urban African-American community, the predominant beliefs about hypertension diverged sharply from current medical understanding. Lack of appreciation of these lay beliefs by providers may contribute to noncompliance and poor rates of hypertension control.

AVO and elastic impedance

A mplitude-variation-with-offset (AVO) has been used extensively in hydrocarbon exploration over the past two decades. Traditional AVO analysis involves computation of the AVO intercept and gradient from a linear fit of P-wave reflection amplitude to the sine square of the angle-of-incidence. This linear fit is based on the approximate P-wave reflection coefficient formulation in intercept-gradient form, given by Bortfeld (1961) and Shuey (1985) among others. Under the assumption of a background P-S velocity ratio of two, the AVO intercept and gradient values can also be combined to obtain additional AVO attributes such as pseudo S-wave data and Poisson's ratio contrast. AVO intercept and pseudo S-wave data are also used in conjunction with prestack waveform inversion by Mallick et al. (2000) in a hybrid inversion scheme.

Zircon ages constrain the timing of deformation events in the the Granites‐Tanami region, northwest Australia*

Dating of extensive granitoids in the The Granites‐Tanami Block of northern Australia has enabled time limitations on deformational events, including five Palaeoproterozoic events (D1‐D5) and one older, almost Neoarchaean event. D1 is present in the basal Tanami Group, D2 to D5 help define other stratigraphic groups in the region. The intrusive rocks have been dated by traditional zircon and stepwise lead evaporation techniques. A post‐D2/pre‐D3 foliated and boudinaged leucocratic tonalite gave 1870 ± 3 Ma. A syn‐D3 foliated and boudinaged tonalite 1858 ± 3 Ma and a post‐D3/pre‐D4 foliated tonalite 1840 ± 11 Ma. Two unmetamorphosed and post‐D5 granitoids gave 1797 ± 1 Ma and 1787 ± 3 Ma, respectively. Some deformation events are separated by as little as 10 to 20 million years. These times of intrusive igneous activity exactly replicate other igneous events, many of which are volcanic, in the Halls Creek Province 400 km to the northwest, which strengthens proposed geological relationships between the two regions. A granitic gneiss in a basement inlier gives 2487 ± 3 Ma, a Neoarchaean age. Tectonic uplift in the Carboniferous is deduced from concordia lower intercept data that is similar to the eastern Arunta Block. Further age definition of D1 D2 and D5 is under current investigation.

Length-Biased Sampling in Mall Intercept Surveys

The authors address length-biased sampling that occurs when sampling is done at central locations in a shopping center. Correction techniques are presented for two situations: when the total length of stay is known or estimated and when only the recurrence time is known accurately. The techniques are illustrated with mall intercept data.

Toward a Model of the In-Store Purchase Decision Process: Consumer Use of Criteria for Evaluating Women's Apparel

To identify criteria considered by consumers while making garment purchase decisions, free response interviews of 80 female customers were conducted at point of purchase in two specialty apparel stores. Subjects described the criteria they used to evaluate a garment they had tried on. The most important criteria for apparel assessment were related to aesthetics. Comparison of responses of customers who purchased and customers who did not purchase their garments revealed that different criteria had primary effects in two stages of the purchase process. During the Interest phase, color/pattern, styling, and fabric were most critical in influencing selection of garments from the display racks. Fit, styling, and appearance on the body were more important in determining rejection or adoption of the garments during the Trial phase in the dressing rooms. The research begins to fulfill a need for store intercept data collection, study of free responses minimally shaped by the researcher, and development of theoretical models of the apparel purchase process.

A numerical method for extending ray trace calculations of radio fields into strong focusing regions

This paper presents a practical method for computing radio fields in regions of strong focusing, using ray intercept data provided by a standard ray‐tracing program. The procedure extends the usefulness of the ray trace by allowing fields to be computed near caustics and cusps where ray density calculations fail. Using a plane wave decomposition of the field components, phase integrals are computed by curve‐fitting intercepts of rays traced through ionospheric or tropospheric media whose refractive indices vary arbitrarily with altitude. A numerical algorithm is described for performing the plane wave angular spectral integrations. This procedure avoids the complications associated with higher‐order asymptotic techniques, allowing a broad range of refractive‐index profiles to be analyzed by a single method. It is applied to two sample profiles, and the results agree very closely with higher‐order stationary‐phase estimates in caustic regions. Moreover, the computer code runs efficiently, despite the presence of highly oscillatory integrands. The method is capable of including the effects of weak collisions, the spherical earth, and azimuthally dependent transmitter configurations.

Grain size statistics

A method for the computation of spatial grain size distributions from intercept data based on a tetrakaidecahedron grain model is developed. The necessary inverse matrix is presented. The method is applied to a range of metallic and ceramic specimens. The derived distributions are analysed to show that they are not necessarily log-normal. Statistical techniques are applied to determine the minimum sample sizes and these are shown to increase as the distributions become more dispersed. The constant relating the average grain size to the average intercept length is also shown to be sensitive to the grain size distribution.

Vaporization reactions in the ytterbium–fluorine system

The vaporization and sublimation reactions for the ytterbium fluoride system have been investigated by mass loss, x-ray powder diffraction, elemental analysis, and mass spectrometry. When YbF2.00 is heated in vacuum, it decomposes to give a metal rich vapor and a metal deficient residue until the composition YbF2.40(4) is reached. The following equilibrium reactions were established: YbF2.40(s,l) = (0.60)YbF2(g) + (0.40)YbF3(g), Reaction (a); and YbF3.00(s,l) = (0.05)YbF2.40(s,l) + (0.95)YbF3(g) + (0.03) F (g), Reaction (b). % A target collection Knudsen effusion method was used to determine vapor pressures for the above reactions. From the slope–intercept data the following enthalpy and entropy changes with associated standard deviations were derived at the median temperatures: For Reaction (a), ΔH°1597 = (96.9±1.1) kcal mol−1 and ΔS°1597 = (36.83±0.67 %cal mol−1⋅K−1; for Reaction (b), ΔH°1568 = (91.19±0.41) kcal mol−1 and ΔS°1568 = (37.28±0.26) cal mole−1⋅K−1. Estimated and reported thermodynamic functions were employed to reduce the thermodynamic values to 298 K. The reduced values are as follows: For reaction (a), ΔH°298 = (110.7±2.3) kcal mol−1 and ΔS°298 = (50.8±2.2) cal mol−1⋅K−1; for Reaction (b), ΔH°298 = (111.1±1.3) kcal mol−1 and ΔS°298 = (56.2±1.5) cal mol−1⋅K−1. By use of the third-law procedure, the following ΔH°298 values were derived: for (a), (109.8±2.4) kcal mol−1; for (b), (107.0±3.0) kcal mol−1. The enthalpies and entropies for the hypothetical congruent sublimation reactions of YbF2(s) and YbF3(s) are derived and compared with those of the alkaline earth difluorides and other selected lanthanide fluoride systems.

A Procedure for Rapid Collection, Processing, and Analysis of Line Intercept Data

A Procedure for Rapid Collection, Processing, and Analysis of Line Intercept Data