Small Sample Areas Research Articles

Determination of ape distribution and population size using ground and aerial surveys: a case study with orang‐utans in lower Kinabatangan, Sabah, Malaysia

AbstractBecause of the difficulties encountered in detecting many large tropical forest‐dwelling species in their natural habitat, precise figures concerning the distribution, number and trends of many populations remain deficient. In tropical forests, ground surveys are generally carried out by counting objects along straight lines. These counts require a strict compliance with the line‐transect methodology before (proper design of the census), during (careful data collection) and after (accurate and correct data processing and analysis) the census itself. In addition, the major source of bias when estimating population size and/or trends comes from the extrapolation of estimates obtained in small sampling areas to the larger, and often incompletely known, distribution of the population. In the Kinabatangan floodplain (Sabah, Malaysia), helicopter surveys were useful in directly assessing the distribution of orang‐utans and were a major advantage in the precise estimation of the size of the orang‐utan population surviving in this region. Our survey showed that about 1100 orang‐utans remain in the multiple‐use forests of the Kinabatangan floodplain. These results provide new evidence on orang‐utan adaptation to habitat disturbance and indicate the potential of the Kinabatangan multiple‐use forests for orang‐utan conservation. Helicopter surveys appear to be a promising alternative to ground survey for precise distribution assessment and for monitoring population trends of apes throughout their entire range in Asia and in some parts of Africa.

Fourier Transform Infrared Synchrotron Ellipsometry for Studying the Anisotropy of Small Organic Samples

An experimental setup for polarization-dependent and spectroscopic ellipsometric measurements was developed that utilizes the brilliance of synchrotron infrared radiation at the electron storage ring at BESSY II for investigations of small samples and sample areas. During commissioning of the beamline and the experimental setup, a 1 mm2 piece of a well-characterized polyimide film was studied to show the benefits of Fourier transform infrared (FT-IR) synchrotron ellipsometry. The band shapes are interpreted with respect to the anisotropic distribution of transition dipole moments within the film. In comparison to a globar source, the signal intensity has been improved by more than one order of magnitude for this example.

Analysis of Heterogeneous Composites Based on Moving-Window Techniques

Moving-window micromechanics techniques are emerging as a useful tool for characterizing random composites, i.e., those with spatially random microstructures, in terms of local material property fields. These material property fields represent an approximate constitutive model for local material response. In this work, elastic property fields for randomly generated composite materials are estimated using a moving-window technique in combination with three micromechanical models, Mori-Tanaka, the generalized method of cells, and a brute-force finite element analysis. The first two methods make predictions of local properties based on small areas of the full sample. The brute-force finite element method performs its initial analysis on the full microstructure. Using the finite element results as the baseline solution, the fields developed from the methods are compared. Results illustrate the differences between the three methods and highlight the strong influence of window size on the analysis. Two criteria are suggested for further study of appropriate window size: A comparison of the correlation areas of the fields, which suggests an upper bound, and the analysis of a single fiber problem with known elasticity solution, which examines a potential lower bound. All of the techniques are demonstrated by application to numerically generated composite microstructures.

Automatic land cover analysis for Tenerife by supervised classification using remotely sensed data

Automatic land cover classification from satellite images is an important topic in many remote sensing applications. In this paper, we consider three different statistical approaches to tackle this problem: two of them, namely the well-known maximum likelihood classification (ML) and the support vector machine (SVM), are noncontextual methods. The third one, iterated conditional modes (ICM), exploits spatial context by using a Markov random field. We apply these methods to Landsat 5 Thematic Mapper (TM) data from Tenerife, the largest of the Canary Islands. Due to the size and the strong relief of the island, ground truth data could be collected only sparsely by examination of test areas for previously defined land cover classes. We show that after application of an unsupervised clustering method to identify subclasses, all classification algorithms give satisfactory results (with statistical overall accuracy of about 90%) if the model parameters are selected appropriately. Although being superior to ML theoretically, both SVM and ICM have to be used carefully: ICM is able to improve ML, but when applied for too many iterations, spatially small sample areas are smoothed away, leading to statistically slightly worse classification results. SVM yields better statistical results than ML, but when investigated visually, the classification result is not completely satisfying. This is due to the fact that no a priori information on the frequency of occurrence of a class was used in this context, which helps ML to limit the unlikely classes.

Examination of poly‐capillary lenses for their use in micro‐XRF spectrometers

AbstractThe availability of poly‐capillary lenses opens up a wide variety of possibilities for the analysis of small sample areas because a large part of the tube radiation can captured and focused on the sample. Propagation in the glass capillaries is achieved by external total reflection on their internal surface. At first the intensity gain of the lenses and their spot size were the most interesting parameters. However, by using these lenses in commercial instruments, other parameters became more important for characterizing their performance for spectroscopic use, e.g. the energy dependence of the spot size and of the transmission efficiency and their influence to the tube spectrum. In this paper, the examination of various lenses from different manufacturers is described. It is shown that for the main parameters spot size and intensity gain, the differences are negligible. However, other parameters can be influenced by the change in geometric parameters of the lens such as the diameter of the single capillaries and bending radius of the lenses. These changes need high perfection in lens manufacturing. It seems that at present only one of the manufacturers is able to control the process in this way. However, there is also another requirement for the implementation of lenses for commercial instruments, namely the uniformity of the outer dimensions. Only in this case can these components be used without special adaptation in a routine instrument. This also requires the complete control of the manufacturing process. Because the use of poly‐capillary lenses is in its early stages, it seems necessary to define more exactly the parameters that characterize the x‐ray optical components. Only in this case will it be possible to define the performance of the optics with high precision and compare lenses from different manufacturers. Copyright © 2003 John Wiley & Sons, Ltd.

Precipitate scanning in Ni-base γ/γ ′-superalloys

In this paper we present μSAXS and TEM investigations on the local microstructure of an experimental W-rich single crystal Ni-base γ/γ ′-superalloy. Using the ID13(ESRF) X-ray microfocus beam we scanned a small sample area and were able to distinguish between different precipitate phases (γ ′/σ). The σ phase could be unambiguously identified by comparing the data to numerical two-dimensional simulations on similar alloys, e.g. SCA, SC16. The low concentrated detrimental platelet TCP σ phase, which was not detectable in SANS on the same alloy, seems to be ordered in stacks with a preferential orientation perpendicular to the [3 2 0]-direction.

Inhomogeneous Deformation of Microcrystalline Region in Isotactic Polypropylene Film Revealed by a Simultaneous Kinetic Measurement of Microscopic Infrared Dichroism and Macroscopic Stress

The orientation behaviors of macromolecules in the microcrystalline and the amorphous regions of two isotactic polypropylene films with different degrees of inhomogeneity are studied using an instrument constructed for simultaneous kinetic measurement of microscopic IR (MicIR) dichroism and macroscopic stress at constant elongation rate. Reliability of IR data obtained by the kinetic measurement is demonstrated. The influence of the necking on the molecular orientation is revealed pursuing the time profiles of the MicIR dichroism sampled in a same small sampling area that is initially located at the center of the film but continuously moves during stretching due to the inhomogeneity of the sample. The dramatic molecular orientation in the sampling area is found to mainly occur during the process that the necking passes through this area and is almost independent of the macroscopic stress-strain relationship. The dichroism differences in different locations of the microcrystalline region next to a giant spherulite are shown to exemplify the influence of the inhomogeneity on the molecular orientation behavior.

Occupancy frequency distributions: patterns, artefacts and mechanisms.

Numerous hypotheses have been proposed to explain the shape of occupancy frequency distributions (distributions of the numbers of species occupying different numbers of areas). Artefactual effects include sampling characteristics, whereas biological mechanisms include organismal, niche-based and meta-population models. To date, there has been little testing of these models. In addition, although empirically derived occupancy distributions encompass an array of taxa and spatial scales, comparisons between them are often not possible because of differences in sampling protocol and method of construction. In this paper, the effects of sampling protocol (grain, sample number, extent, sampling coverage and intensity) on the shape of occupancy distributions are examined, and approaches for minimising artefactual effects recommended. Evidence for proposed biological determinants of the shape of occupancy distributions is then examined. Good support exists for some mechanisms (habitat and environmental heterogeneity), little for others (dispersal ability), while some hypotheses remain untested (landscape productivity, position in geographic range, range size frequency distributions), or are unlikely to be useful explanations for the shape of occupancy distributions 'species specificity and adaptation to habitat, extinction-colonization dynamics). The presence of a core (class containing species with the highest occupancy) mode in occupancy distributions is most likely to be associated with larger sample units, and small homogenous sampling areas positioned well within and towards the range centers of a sufficient proportion of the species in the assemblage. Satellite (class with species with the lowest occupancy) modes are associated with sampling large, heterogeneous areas that incorporate a large proportion of the assemblage range. However, satellite modes commonly also occur in the presence of a core mode, and rare species effects are likely to contribute to the presence of a satellite mode at most sampling scales. In most proposed hypotheses, spatial scale is an important determinant of the shape of the observed occupancy distribution. Because the attributes of the mechanisms associated with these hypotheses change with spatial scale, their predictions for the shape of occupancy distributions also change. To understand occupancy distributions and the mechanisms underlying them, a synthesis of pattern documentation and model testing across scales is thus needed. The development of null models, comparisons of occupancy distributions across spatial scales and taxa, documentation of the movement of individual species between occupancy classes with changes in spatial scale, as well as further testing of biological mechanisms are all necessary for an improved understanding of the distribution of species and assemblages within their geographic ranges.

Lysozyme diffusion adjacent to the (1 1 0) crystal surface

Measurements of lysozyme diffusion within the “depletion zone” of the (1 1 0) face of lysozyme crystals are reported. The measurements were performed using the technique of microscope light scattering , capable of measuring small sampling areas (∼2 μm 2). Measurements within such small areas allowed for the determination of intensity correlation functions at precise locations (at ∼10 μm intervals) adjacent to the (1 1 0) crystal face. From the intensity correlation functions, diffusion coefficients of lysozyme molecules adjacent to the (1 1 0) crystal face and in solution were determined. The diffusion coefficients were observed to decrease as the surface of the crystal was approached.

Non-Stoichiometry at Dislocation Cores in Perovskites and Related Materials

Z-contrast images and electron energy loss spectra (EELS) were obtained from low angle grain boundaries in SrTiO3 and YBa2Cu3O7-x (YBCO). Z-contrast images are easy to interpret and especially useful for positioning the beam to acquire EELS data from small sample areas [1], because both these techniques can be performed simultaneously.In high-temperature superconductors even a single grain boundary can reduce the critical current by up to four orders of magnitude. The band-bending model can quantitatively explain this phenomenon. YBCO is a hole-doped superconductor with about one hole per unit cell for optimum doping at x close to zero. It has a structure closely related to the perovskite structure, and Z-contrast images have shown that the dislocation cores are made up of similar structural units as in SrTiO3.[2,3] Our EELS measurements show clear evidence for band bending effects around isolated dislocation cores in an undoped 8° low angle grain boundary.

Frequency-domain fluorescence microscopy with the LED as a light source.

We describe a frequency-domain lifetime fluorometer based on a microscope and a modulated light-emitting diode (LED) excitation source (370/460 nm), which operates in the frequency range 120 Hz--250 MHz. We collected multifrequency phase and modulation fluorescence responses from cellular areas as small as 10--15 microm in diameter. We also collected fluorescence lifetime data from cells stained by a lipophilic coumarin sensitized europium fluorophore, Coum-Eu, with a millisecond lifetime, and Ru(bpy)(2)phe-C(12),with microsecond lifetime. Nanosecond lifetimes from native nuclei stained with SYTO 14 and SYTO 16 probes were measured as well. We demonstrate that a simple LED excitation source can, for many applications, successfully replace complex and expensive laser systems, which have been used for cellular frequency-domain lifetime measurements. As the LEDs are very stable with low noise, it will be possible to image even smaller sample areas using brighter LEDs. With availability of modulated LEDs emitting at several wavelengths covering almost the entire visible spectrum it is easy to assemble a system for the fluorophore of choice. The ability to select an excitation source for a given fluorophore and low price make such an excitation source even more practical.

Estimates of forest floor litter frog communities: A comparison of two methods

AbstractEstimates of forest leaf litter frog density, mass, richness and diversity given by the widely used 8 m × 8 m large plot method (LPM) were compared with estimates obtained by a newly proposed method (small 2 m × 1 m plots with leaf removal; SPLR). The study site was an undisturbed area of the Atlantic Rainforest of Ilha Grande, an island located in the south of Rio de Janeiro State, Brazil. Twenty‐four LPM (totalling 1536 m2 of forest floor) and 90 SPLR (totalling 180 m2 of forest floor) were performed. The estimates obtained by the two methods differed markedly, indicating that even using a much smaller sampling area (11.7% of that of LPM), SPLR gave frog density estimates six times higher, and frog mass estimates approximately 2.5 times higher than estimates provided by LPM. The species richness and diversity obtained by the two methods were similar, despite the fact that the total area sampled with SPLR was much smaller. These data suggest that LPM may underestimate the abundance and biomass of leaf litter frogs in a given area.

Models for description of the influence of light intensity on the parameters of the transient photo-EMF of organic photoconductors

The aim of this work is a quantitative description of the connections between the excitation laser flash intensity and the parameters of the transient photo-EMF. The models suggested in this paper were checked by experimental data obtained from layers of the organic photoconductors N,N′-dimethylperylenetetracarboxylic bisimide (MePe, n-type photoconductor) and copper(II) phthalocyanine (CuPc, p-type photoconductor) dispersed in poly(vinyl butyrale) (PVB) as binder. The models used are valid both for a neglectable and for a real dark charge carrier concentration. Nevertheless, recombination is the most important pathway of charge carrier disappearance in both photoconductors. The models may also describe the influence of laser flash intensity if the sample is illuminated by continuous white xenon light additional to the laser flash and also if the laser is focused on a very small sample area. The model valid for a real dark charge carrier concentration yields the best reproduction of the experimental data. In the case of neglectable dark charge carrier concentrations this model may be simplified. Then it permits an estimation of the mobility ratio of electrons and holes μn/μp: for example at excitation wavelength λflash = 580 nm the ratio μn/μp amounts to 1.35 for MePe and 0.73 for CuPc.

Micro-Area Residual Stress Measurement Using a Two-Dimensional Detector

Residual stress measurement by x-ray diffraction on small samples or small sampling area using a two-dimensional (2D) detector is discussed. A new approach in stress analysis using the two-dimensional diffraction data is based on a direct relationship between the stress tensor and the diffraction cone distortion. Since the whole or a part of the Debye ring is used for stress calculation, a 2D detector can measure stress with high sensitivity, high speed and high accuracy, even for micro-area. The laser-video sample alignment system can align the intended measurement spot accurately to the instrument center where the x-ray beam hits. The motorized XYZ stage can move the measurement spot precisely to the instrument center and map many sample spots automatically. The spotty, textured, or weak diffraction data can be treated by virtual oscillation.

Polycapillary X-ray optics for microdiffraction

Polycapillary optics,i.e.shaped arrays consisting of hundreds of thousands of hollow glass capillary tubes, can be used to redirect, collimate or focus X-ray beams. X-rays emitted over a large angular range from conventional laboratory-based sources can be transformed into a beam with a small angular divergence or focused onto a small sample or sample area. Convergent beams of X-rays, with convergence angles as high as 15°, have been produced using polycapillary X-ray optics. Focused-spot sizes as small as 20 µm have been achieved, with flux densities two orders of magnitude larger than that produced by pinhole collimation. This results in a comparable decrease in data collection times because of the increase in direct-beam intensity and reciprocal-space coverage. In addition, the optics can be employed to reduce background and provide more convenient alignment geometries. The inverse dependence of the critical angle for total external reflection on photon energy results in suppression of high-energy photons. This effect can be employed to allow the use of higher tube potentials to increase the characteristic line emission and has also been employed to increase significantly theKα/Kβ ratio in Cu radiation. Measurements of X-ray diffraction data and crystallographic analyses have been performed for systems ranging from elemental crystals to proteins. Data from a lysozyme protein `standard' with a slightly convergent beam, taken in 3 min per frame with 2° oscillation with a 2.8 kW source, refined to an intensity variance of 5% compared to a standard data set. High-quality data were also obtained with a 0.03 kW fixed-anode source and a 2° convergent lens in 5 min per frame.

Local current-voltage curves measured thermally (LIVT): A new technique of characterizing PV cells

Local current-voltage characteristics measured thermally (LIVT) is a non-destructive technique based on measuring the bias dependence of the local temperature of a small sample area in the ac mode. It is an important supplement to light beam induced current (LBIC), electron beam induced current (EBIC) and Dynamic Precision Contact Thermography (DPCT) techniques allowing to study the nature of the current at a given point on the cell surface. Presented experimental results comprise LIVTs of natural inhomogeneities in multicrystalline silicon solar cells, artificial defects in monocrystalline cells (mechanically damaged regions), as well as LIVTs of several test structures. LIVT data generally confirm existing theories for different current natures. A related technique for n-factor mapping is also presented.

Computer-Aided Analysis of Oriented Crystallites by Diffraction Pattern Simulation and Tilt-Stage Control in a TEM

Abstract Electron diffraction patterns taken in the transmission electron microscope (TEM) provide information about crystal structures and orientations in small sample areas. Extracting this information and manipulating local crystal orientations has become a great deal easier with the availability of desktop computer programs that allow simulation matching of experimental patterns and crystallographic control of sample tilting in the TEM. This presentation will illustrate an application of computer-aided crystallography for analyzing oriented crystallites in an experimentally complex material. The surface corrosion films that form on reactive metals such as hafnium or zirconium in hot water provided our example. Cross-sectional examinations of the corrosion films revealed a columnar microstructure of monoclinic HfO2/ZrO2 grains extending normal to the metal/corrosion-film interface.The columnar grains were only about 50 nm in width, and thus were too small to analyze individually by selected-area diffraction. Local strains in the films smeared the diffraction fine structure so there was little hope for analysis by convergent-beam diffraction methods.

ＳＩＭＳによるセラミックス中の酸素拡散の測定

One of the most interesting features of secondary ion mass spectrometry (SIMS) is its ability to detect isotope ratio in a small area of a solid state sample. It enables to study isotope diffusion properties in solids. Experimental setup and data analysis for isotope exchange/SIMS measurement are introduced focusing on its application to oxygen transport study in ceramic materials. Fast diffusion paths and preferred surface reaction sites are visualized by sector type SIMS. Oxygen vacancy diffusion coefficient and chemical diffusion coefficient of nonstoichiometric oxides are also estimated from the isotope diffusion coefficient and thermodynamic data.

Soft X-ray stimulated luminescence microscopy and spectroscopy on Gd2O2S:Pr3+ and (Y, Gd)2O3:Eu3+ ceramics

Abstract The Hamburg soft X-ray scanning microscope at HASYLAB/DESY has been equipped with detectors for luminescence in the visible and X-ray fluorescence or backscattered radiation. The microscope is operating in the region from 20–1200 eV and uses an elliptical grazing incidence mirror to focus the soft X-rays on a spot of about 1 μm. By varying the energy of the incoming radiation, excitation spectra can be taken from small sample areas (microspectroscopy). Defect structures on polished luminescent ceramics were investigated. The influence of the Gd 4d→4f giant resonance on the luminescence signal is observed in the yield spectra and compared with our calculations.

Analysis of Crystallographic Texture in Small Sample Areas

The description of texture by means of a small number of components (preferred orientations) is an exceptionally concise method. It may reveal relevant information about the texture modifying process even in those cases where the texture information, contained in the experimental pole figures, is rather limited. Some examples for texture estimates and interpretation of local textures in thin layers (SiC films synthesized by carbonization of silicon with fullerenes) and bulk materials (shear bands in brass and titanium) are presented.