Large Dissimilarity Research Articles

Sucessão florestal secundária no município de São Pedro de Alcântara, litoral de Santa Catarina: estrutura e diversidade.

O processo de sucessão florestal secundária no Litoral de Santa Catarina é caracterizado por estádios sucessionais bem-definidos. Este trabalho foi realizado com o objetivo de caracterizar esses estádios em relação à riqueza de espécies, índice de diversidade (Shannon-Weaver), grupos de densidades, classes diamétricas, e área basal. O estudo foi realizado em uma área situada no município de São Pedro de Alcântara, localizado a 50 km de Florianópolis, com vegetação característica de Floresta Ombrófila Densa. Foram amostradas seis parcelas de 10x10 m em cada estádio sucessional, Myrsinietum3, Miconietum e Mata Secundária. Foram medidos todos indivíduos de espécies arbóreas e arbustivas com altura superior a 1 metro. O estádio de Myrsinietum, com grande dominância de Myrsine coriacea, se caracterizou pela baixa diversidade de espécies (H =2,09 nats), com muitos indivíduos de cada espécie nas classes de menor diâmetro (<10cm), refletindo em uma baixa área basal (6,99 m2/ha). No estádio de Miconietum, com dominância de Miconia cinnamomifolia, existe um grande número de indivíduos nas classes de até 20 cm de DAP, não passando de 35 cm, resultando em uma área basal de 33,67 m2/ha. Nesse estádio, verificou-se um grande número de espécies, com alta diversidade (H = 3,55 nats), das quais a maior parte é de ocorrência muito esparsa. No estádio de Mata Secundária, existe um grande número de indivíduos nas classes até 15 cm de DAP, mas com indivíduos até 52 cm, resultando em uma área basal de 39,11 m2. Nesse estádio, 50% das espécies é de ocorrência muito esparsa com um índice de diversidade (H) de 3,48 nats. Os resultados obtidos neste trabalho não permitiram o enquadramento dos estádios sucessionais de Myrsinietum, Miconietum e Mata Secundária nos estádios de regeneração definidos pela Resolução n. 04/1994 do CONAMA. As características de cada estádio sucessional demonstram a grande dessemelhança existente entre o estádio Myrsinietum e os estádios Miconietum e Mata Secundária, tanto do ponto de vista estrutural como ecológico. Essas diferenças podem subsidiar estratégias, visando ao uso e à conservação dos recursos florestais.

Spin-dependent neutrino-induced nucleon knockout

We study neutrino-induced nucleon knockout off atomic nuclei and examine the polarization properties of the ejectile. A detailed study of the spin dependence of the outgoing nucleon is presented. The numerical results are derived within a nonrelativistic plane-wave impulse-approximation approach. Our calculations reveal large polarization asymmetries and clear dissimilarities between neutrino- and antineutrino-induced reactions. They reflect the fact that neutrino-induced nucleon knockout is dominated by the transverse axial current and gains its major contributions from forward nucleon emission and backward lepton scattering.

Vesicle membrane interactions of penetratin analogues.

Reports on serious artifacts associated with the use of cell fixation in studies of the cellular uptake of cell-penetrating peptides, also denoted protein transduction domains, have demonstrated the need for a reevaluation of the current understanding of peptide-mediated cellular delivery of large, hydrophilic molecules. In a recent study on the internalization in unfixed cells of penetratin and its analogues in which tryptophans are substituted for phenylalanines (Pen2W2F), lysines for arginines (PenArg), and arginines for lysines (PenLys), we revealed large dissimilarities in cell interactions among the peptides [Thorén et al. (2003) Biochem. Biophys. Res. Commun. 307, 100-107]. We here investigated possible correlations with their respective affinities for the lipid membranes of large unilamellar vesicles. The variations found in membrane affinity correlated qualitatively with differences in hydrophobicity among the peptides but were by far too small to account for the striking differences in cell membrane binding. Interestingly, we found that the inclusion of a small fraction of lipids conjugated to poly(ethylene glycol) (PEG) in the vesicles both stabilized the vesicle dispersion against peptide-induced aggregation and, furthermore, enhanced the binding of the peptides to the membrane. By use of PEG-conjugated lipids, it could be shown that vesicle aggregation drives an alpha-helix to beta-sheet conformational transition for these peptides. A similar transition was discovered at submicellar concentrations of sodium dodecyl sulfate in aqueous solution for all peptides except PenLys. Finally, significant changes of the contributions to CD spectra from aromatic residues due to their insertion into the membrane were observed.

Spatial characteristics of snow accumulation in Dronning Maud Land, Antarctica

An accurate knowledge of spatial variations in snow accumulation on ice sheets is vital for numerical reconstructions and future projections of ice sheet dynamics, with implications for changes in global climate and sea level. This study considers net snow accumulation in Dronning Maud Land, East Antarctica. Ground-penetrating radar (GPR) soundings were carried out along two ground traverses, 800 and 1000 km long, extending from the ice shelves to the high plateau in order to map snow accumulation rates continuously along the route. Comparisons between the net accumulation rates obtained by GPR and those obtained by stake-line measurements exhibited a close correlation. Large dissimilarities in the accumulation distribution were observed between the two traverses. The ice sheet surface topography and the regional distribution of air pressure systems and cyclone tracks can explain these differences to a large extent. Spatial trends in snow accumulation rate were determined for characteristic traverse sections. The spatial variability was calculated as the standard deviation in snow accumulation rate over 5 km, expressed as percentages of the average accumulation within the 5-km section. On ice shelves, the spatial variability was less than 10%. In grounded coastal areas, it ranged between 20% and 40%, and on the high plateau, it ranged up to 20%. In areas of intense wind erosion, the spatial variability often exceeded 50%. The generally high spatial variability demonstrates that the spatial representativeness of individual point measurements is of vital importance in Antarctic snow accumulation studies. This is a problem that is presently not properly attributed.

Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system

We report measurements of seasonal variability in the C‐N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh) to determine whether C‐N isotopes can be used as biomarkers for tracing the origins of organic matter in this river‐marsh‐estuary complex. Variability of δ13C and δ15N was high (~5–10‰) within each plant group, and we identified three modes of variability: (1) between species and their microhabitats, (2) over annual cycles of plant growth and senescence, and (3) between living and decomposing biomass. These modes of within‐group variability obscure any source specific isotopic signatures, confounding the application of C‐N isotopes for identifying the origins of organic matter. A second confounding factor was large dissimilarity between the δ13C‐δ15N of primary producers and the organic matter pools in the seston and sediments. Both confounding factors impede the application of C‐N isotopes to reveal the food supply to primary consumers in ecosystems supporting diverse autotrophs and where the isotopic composition of organic matter has been transformed and become distinct from that of its parent plant sources. Our results support the advice of others: variability of C‐N stable isotopes within all organic‐matter pools is high and must be considered in applications of these isotopes to trace trophic linkages from primary producers to primary consumers. Isotope‐based approaches are perhaps most powerful when used to complement other tools, such as molecular biomarkers, bioassays, direct measures of production, and compilations of organic‐matter budgets.

Coarse-to-fine planar object identification using invariant curve features and B-spline modeling

This paper presents a hybrid algorithm for coarse-to-fine matching of affine-invariant object features and B-spline object curves, and simultaneous estimation of transformation parameters. For coarse-matching, two dissimilar measures are exploited by using the significant corners of object boundaries to remove candidate objects with large dissimilarity to a target object. For fine-matching, a robust point interpolation approach and a simple gradient-based algorithm are applied to B-spline object curves under MMSE criterion. The combination of coarse and fine-matching steps reduces the computational cost without degrading the matching accuracy. The proposed algorithm is evaluated using affine transformed objects.

Thermodynamic analysis of Ga xB 1− xN grown by MOVPE

A thermodynamic model was applied to predict the GaBN MOVPE growth such as the equilibrium partial pressures, vapor–solid distribution relation, and growth efficiency. The delta-lattice-parameter (DLP) method was employed to determine the activities of the binary compounds. The large structural dissimilarity between BN and GaN results in a high interaction parameter of 70 730 cal/mol, indicating that GaBN deviates greatly from an ideal solid solution. A V/III ratio>100 is required for the growth of GaBN at 1000°C to avoid Ga droplets on the growth front. The growth of GaBN is controlled by the much higher Ga partial pressure than that of B over the alloy. The unstable regions in which inhomogeneous compositions are formed exist in the GaBN alloy based on the vapor–solid distribution relation. The predicted growth behavior of GaBN agrees well with the experimental data.

An experimental investigation of atmospheric electricity and lightning activity to be performed during the descent of the Huygens Probe onto Titan

No terrestrial-like electrical activity was observed during the Voyager 1 flyby of Titan on 12 November 1980, in spite of a predicted global lightning energy dissipation rate of 4 × 10 −6 Wm −2. This lack of evidence does not, however, rule out the existence of electrical discharges with magnitudes, rates of occurrence and spectral characteristics drastically different from those known on Earth, owing to large dissimilarities between the temperatures, chemical compositions and, especially, electrical conductivities of the two atmospheres. Towards the end of the year 2004, the ESA probe Huygens will be jettisoned from the NASA Saturn orbiter, Cassini. This probe will descend onto Titan and perform in situ measurements during a period of 3 h, from an altitude of 170 km down to the satellite surface where the atmospheric pressure reaches 1.6 × 10 5 Pa. The Huygens scientific payload will include a set of instruments entirely dedicated to the detection of lightning and to the characterization of the electrical properties of the atmosphere and surface. An electric antenna will search for natural emissions in the frequency range 0–10 kHz, at altitudes lower than those of ionized layers opaque to electromagnetic waves, and measure the magnitude of static electric fields due to charge separation. The conductivity of the atmosphere and the existence of free electrons will be checked during the whole descent with a combination of quadrupolar and relaxation probes; a microphone will also record acoustic phenomena associated with electrical discharges and atmospheric processes. The impedance of the surface will be evaluated from the measurements collected with a radar during the descent and a quadrupolar array after touch down.

Phenology of the Larval Chironomidae of a Large Temperate Nearctic River

ABSTRACT I used rock-basket and multiplate samplers to collect chironomid larvae on ten sampling dates throughout 1979 from the Ohio River, a large river with a wide yearly temperature range (ΔT = 29°C in 1979). Winter and early spring collections of chironomids were heavily dominated by species of the subfamily Orthocladiinae such as Eukiefferiella brevicalcar gr., Hydrobaenus pilipes, Orthocladius obumbratus, Orthocladius oliveri, Orthocladius sp., and Parakiefferiella sp. Although these six species dominated cold-weather collections, no individuals of any of these species were present in the samples in the warm months of July and August. Such species probably aestivate in the summer as eggs or early larval instars. The summer fauna was dominated, instead, by species of the subfamily Chironominae, such as Rheotanytarsus sp., Stenochironomus sp., and Polypedilum convictum. This Study shows that the pattern of changing dominance (Orthocladiinae/Chironominae) can apply not only latitudinally and altitudinally, as shown by other investigators, but also seasonally in a single temperate location. The utilization of the Ohio River's wide annual temperature range by the Chironomidae, with each species selecting the appropriate season and temperature for its development, results in a diverse community when viewed over the entire year, and in large dissimilarities in composition between the summer and winter faunas.

UV Resonance Raman Spectra of Bacillus Spores

UV resonance Raman spectra of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis endospores have been excited at 222.7,230.7,242.5, and 251.1 nm, and spectra have been compared with those of vegetative cells. The resonance Raman spectra of aqueous solutions of dipicolinic acid and calcium dipicolinate have been measured at the same wavelengths. Spectra of endospores and their corresponding germinated spores show only modest differences when excited at 222, 231, and 251 nm. However, very substantial differences appear when excitation occurs at 242 nm. Difference spectra obtained at 242 nm by subtracting spectra of germinated spores of Bacillus cereus from spectra of their corresponding endospores are attributed almost entirely to dipicolinate. Vegetative cells and endospores show large spectral dissimilarities at all exciting wavelengths. These spectral differences, which vary strongly with exciting wavelength, appear to be the result of large differences in the amounts and composition of proteins and nucleic acids, especially ribosomal RNA. The very substantial resonance enhancement of Raman spectra has been obtained from aqueous solutions of pure dipicolinic acid and of sodium and calcium dipicolinate salts, as well as spores at the various exciting wavelengths. The strong enhancement of dipicolinate spectra in spores, however, was noted only with 242-nm excitation. Consequently, only with 242-nm light was it possible to selectively and sensitively excite and study calcium dipicolinate in spores. Resonance enhancement of the dipicolinate spectra with 242-nm excitation appears due primarily to resonance interactions with n-π* electronic transitions associated with the pyridine ring and/or the carboxylate group.

On the compatibility of nested logit models with utility maximization

The paper examines the relationship between the nested multinomial logit (NMNL) model and rational consumer behavior. We show that the Daly-Zachary-McFadden (DZM) condition of the validity of stochastic utility maximization in NMNL models is unnecessarily strong and leads too often to rejection of NMNL models with large dissimilarity parameters. In many cases, the distribution of the stochastic utility components in the NMNL model can be modified in a way that preserves the NMNL choice probabilities on a subset of R I , where I is the number of alternatives in the choice set. On this subset, the DZM condition can be violated without violating the restrictions of stochastic utility maximization.

Intraregional Income Distribution and Poverty: Some Investigations for the Netherlands, 1960–81

"This paper is addressed to intraregional income inequalities in the Netherlands. Various concepts are used to measure the degree of regional poverty. In addition, dissimilarity between intraregional income distributions is studied. At the provincial level, relatively small and decreasing dissimilarities are observed. However, at lower spatial levels (especially within metropolitan areas) much larger dissimilarities in mean income and income distribution occur. In the Netherlands, urban poverty has become a more intense and widespread phenomenon than rural poverty."

Back-side diffraction by relief gratings

A comparison is made between the efficiency of bare and aluminum coated dielectric diffraction gratings supporting only two propagating orders utilizing substrate side light incidence. A large dissimilarity between the two types of gratings is observed and a possibility to achieve a 100% value of the absolute diffraction efficiency in Littrow mount is discussed. An almost constant value of 80% of efficiency is preserved for the aluminum grating nearly in the entire visible region.

Two-photon Ã←X̃ spectra of benzonitrile and styrene vapors: Tests of perturbation rules

The two-photon vapor Ã←X̃ spectra of benzonitrile and styrene have been studied by fluorescence excitation at room temperature. Because of low frequency internal torsional vibrations, the styrene spectrum was also obtained using multiphoton ionization in a supersonic jet. Despite the totally symmetric symmetry of the excited state, the polarization properties of the styrene Franck–Condon spectrum show that the two-photon electronic intensity mechanism predominantly involves the symmetric tensor and not the scalar tensor. Comparison with the corresponding 1B2←1A1 spectrum of phenylacetylene shows that the cross section for the two-photon spectra of the three molecules are roughly equal (∼102 gm) despite a large dissimilarity in the one-photon spectra. The near equality of the three cross sections in molecules without special symmetry properties confirms both the pseudoparity (±) basis of the Callis–Scott–Albrecht inductive perturbation selection rule, and the rule that orbitally allowed -↔- transitions should be very strong for alternant aromatic hydrocarbon two-photon spectra.

The scattering of high-energy electrons. II. Quantitative validity domains of the single-scattering approximations for organic crystals

Two approximations that are commonly used to describe the scattering of high-energy electrons are the first Born approximation (kinematic approximation) and the closely related 'weak phase-object' approximation. The quantitative domains of validity for the use of these two scattering approximations for structural analysis of organic crystals are evaluated numerically in terms of resolution, crystal thickness and incident electron energy. The resulting calculations show how progressively important dynamical scattering effects lead to an increasingly large contribution to the R value in a structure factor analysis. Alternatively, the results show that an increasing dissimilarity is produced between the structure inferred from electron microscope images and the correct structure. The results also show that the actual images (and the structure inferred from the images) remain qualitatively similar to the projected Coulomb potential, even though dynamical scattering effects may lead to a large quantitative dissimilarity relative to the correct structure.

Partial molar excess free enthalpies of n‐alkenes in apiezon M and alkanes in squalane and polydimethylsiloxane, and the solution theories of prigogine and flory: An investigation by gas chromatography

AbstractPartial molar excess free enthalpies (or excess chemical potentials) at infinite dilution were obtained over a large temperature range by gas chromatography. Data on n‐alkenes in Apiezon M are interpreted by the Prigogine–Patterson theory; data on normal and branched alkanes in squalane and polydimethylsiloxane (PDMS) are discussed in terms of the Prigogine–Patterson theory and the solution theory of Flory, Orwoll, and Vrij. For the alkane–PDMS systems heats of dilution and partial excess heat capacity data are given.The aim of this work is to get some insight in the applicability of these solution theories to mixtures of fluids, the properties of which may slightly violate the basic assumptions of these theories. It is shown that orientational order in and a large cross‐sectional chain diameter of the polymer solvent do not affect their applicability to the partical molar excess free enthalpies of apolar mixtures, whereas large dissimilarities between the force fields around the segments of the mixture components and/or dissimilar chain flexibilities detract from the applicability of these theories (alkanes in PDMS).Special attention has been paid to the effects of dissimilar size and shape of the segments of the mixture compounds on the magnitude of the interchange interaction parameter. It is shown that the multiple‐connected segment model after Lichtenthaler et al. does not warrant a reliable combinatorial contribution. Comparison of the interaction parameters obtained for n‐alkanes in n‐alkanes, Apiezon, squalane, and polyisobutylene and for branched alkanes in squalane reveals that the magnitude of this parameter is affected by small end‐effects due to the relative weakness of methyl‐methylene interactions.

Low molecular weight proteins of pike ( Esox lucius) white muscles—II. Chemical and physical properties

1. 1. The amino acid compositions of the two low molecular weight proteins extracted from pike muscles are typical of this protein's family. The molecular weights are 11,525 and 11,740 respectively for components II and III. Their tryptic peptide maps show large dissimilarities. 2. 2. The N-terminal groups are acetylated and alanine is the C-terminal residue in both proteins. 3. 3. For the two proteins 58 per cent helicity was calculated from O.R.D. data. These results are compared with similar measurements on four low molecular weight proteins extracted from carp.

The secretory rate of the human submandibular glands in response to parasympathicomimetic and gustatory stimulation

The relationship between the rate of secretion of the submandibular gland and a number of somatic variables has been examined for stimulation with citric acid and intravenously administered acetyl-beta-methylcholineiodide (Betacholyl®). The results show that functional tests performed with this agent do not give results comparable with those of a gustatory test, and that it should not be used for a clinical examination of the secretory capacity of salivary glands. The difference may be ascribed to large individual dissimilarities in the reaction to the general stimulating agent.