bluuebunny/crossref_metadata_2025 huggingface dataset:
Cooperative Interactions and the Perception of Motion and Stationarity for Directionally Ambiguous Apparent-Motion Stimuli
Authors: Hock Howard S , Balz Gunther W , Eastman Kathleen E
Published: January 2007

Evidence is reported that stationarity rather than motion can be perceived for displaced stimuli, not because of insufficient motion energy for the stimulus to activate individual motion detectors, but because of cooperative interactions that actively suppress the perception of motion. A long row of evenly spaced dots was presented in counterphase; the dots presented during each 180 ms frame were located midway between the dots presented during the previous frame. When either a blank interval as brief as 15 ms was inserted between successive frames or the luminance polarity of the dots was reversed on successive frames, the unidirectional motion pattern perceived for small interdot distances (small displacements) was replaced by the perception of stationarity. However, when under the same conditions a single dot was displaced over the same small distances, motion rather than stationarity was perceived. The contrasting results for the long row of displaced dots and the single displaced dot indicated that when the activation of motion detectors is weakened (by nonzero interframe intervals and/or the reversal of luminance polarity), the perception of motion can be actively suppressed by the collective effects of inhibitory interactions among the large ensemble of detectors that is activated by the long row of dots.
Shadows and Depth Illusions
Authors: Morris Reg C
Published: January 2007

The visual system uses shadows to compute perceived depth of features on an uneven surface, and in doing so makes the assumption of a single light source in most circumstances.

Three illusory depth effects are described (depth reversal, accentuation, and flattening) that can be demonstrated with 3-D materials, and all of which are based on the single-source assumption. Ambiguous lighting conditions may produce moment-to-moment depth reversals and/or the subjective sensation of textural ‘strangeness’. It is suggested that these are both subjective experiences which occur when the system cannot compute depth with certainty.
The Information That Drivers Use: Is it Indeed 90% Visual?
Authors: Sivak Michael
Published: January 2007

The literature contains numerous claims that 90% of all the information used in driving is visual. This article presents a theoretical discussion, a citation search, and a review of evidence concerning such claims. The findings indicate that not only do we lack data from which to derive an accurate numerical estimate, but we lack a measurement system within which any numerical estimate would be meaningful. Consequently, although the information relevant to driving is likely to be predominantly visual, any claims about the precise percentage attributable to vision are premature. The proliferation of such claims in the absence of direct evidence is a reminder that researchers should be careful about assuring the validity of the claims they are passing on.
The Immediacy of the Moon Illusion
Authors: Reed Charles F
Published: January 2007

Exception is taken to the conclusion that the terrestrial-passage theory ignores the immediacy of the experience of the moon illusion and is therefore to be rejected. The meaning of immediacy and the definition of the illusion as a horizon enlargement are examined critically. In demonstrating that immediacy is not ignored, the passage theory is restated, with special attention to potential tests of the theory in explaining individual differences and related phenomena.
A Vector Model of Colour Contrast in a Cone-Excitation Colour Space
Authors: Shepherd Alex J
Published: January 2007

A vector model of colour contrast is examined in a colour space that is a logarithmic transformation of the MacLeod – Boynton cone-excitation diagram. Observers set matches in a haploscopic display, in which one eye viewed a standard display (a neutral target square in a coloured surround) and the other viewed a matching display (a variable square in its own surround). Contrast colours are simply represented in this colour space: the vector connecting the right-eye surround and matched chromaticities is parallel to and of the same length and direction as the vector that connects the left-eye (standard) surround and square chromaticities. This describes observers' matches to the hues induced in a neutral square for a range of inducing surround colours, a range of right-eye (match) surround colours and four different luminance contrasts.
Shading and Stereo in Early Perception of Shape and Reflectance
Authors: Sun Jennifer , Perona Pietro
Published: January 2007

Recent experiments involving shaded 2-D stimuli have shown that early-vision mechanisms are capable of interpreting 3-D shape from shading. In particular, target discrimination tasks suggest that a target ‘pops out’ when background distractors, but not the target, can be interpreted as convex and lit from above or top-left. Since the problem of extracting 3-D shape from shading is intrinsically ill-defined, early vision may need to make these twin assumptions of convexity and top-left lighting in order to constrain the problem. Would these assumptions be recognized as unnecessary and consequently discarded when 3-D shape could be unambiguously defined by some other cue, like stereo disparity?

A 2AFC stimulus onset asynchrony paradigm with masking was used in target discrimination experiments. The performance of five naive subjects on tasks where only shading cues were present was compared with that on tasks involving shading as well as stereo cues that define shape unambiguously. The results show that although stereo disparity information is incorporated by early-vision 3-D mechanisms, it is not used to overturn the default assumptions of lighting and shape. Stereo information is interpreted within the framework of top-left lighting, and a consistent preference for convexity is seen over concavity.
Banishing Illusory Contours: A New Possibility
Authors: Parks Theodore E
Published: January 2007

As an alternative to an earlier hypothesis, it may be that the harmful effect of certain modifications to a pattern which would otherwise produce an illusory figure may be due to excessive coincidences that would be present if an illusory figure were to be seen.
Spatial Scale Interactions and Visual-Tracking Performance
Authors: Hughes Howard C , Aronchick David M , Nelson Michael D
Published: January 2007

It has previously been observed that low spatial frequencies (≤ 1.0 cycles deg−1) tend to dominate high spatial frequencies (≥ 5.0 cycles deg−1) in several types of visual-information-processing tasks. This earlier work employed reaction times as the primary performance measure and the present experiments address the possibility of low-frequency dominance by evaluating visually guided performance of a completely different response system: the control of slow-pursuit eye movements. Slow-pursuit gains (eye velocity/stimulus velocity) were obtained while observers attempted to track the motion of a sine-wave grating. The drifting gratings were presented on three types of background: a uniform background, a background consisting of a stationary grating, or a flickering background. Low-frequency dominance was evident over a wide range of velocities, in that a stationary high-frequency component produced little disruption in the pursuit of a drifting low spatial frequency, but a stationary low frequency interfered substantially with the tracking of a moving high spatial frequency. Pursuit was unaffected by temporal modulation of the background, suggesting that these effects are due to the spatial characteristics of the stationary grating. Similar asymmetries were observed with respect to the stability of fixation: active fixation was less stable in the presence of a drifting low frequency than in the presence of a drifting high frequency.
Fixation Patterns Made during Brief Examination of Two-Dimensional Images
Authors: Mannan Sabira K , Ruddock Keith H , Wooding David S
Published: January 2007

Measurements were carried out of saccadic eye movements made during brief (3 s) examination of images which the observer was asked to identify. Each image was identified in three forms: low-pass filtered, high-pass filtered, and unfiltered. The analysis of the eye-movement patterns was based on the locations of fixations made during examination of the images, for which purpose a least-squares measure of similarity between two sets of locations was introduced. It is shown that there is a high degree of similarity between fixations made by the same observer to the different versions of a given image and that for a given image there is a high degree of similarity between fixations made by the eighteen observers who participated in the experiments. The similarities are greater for the initial 1.5 s than for the full viewing period of 3 s. The similarity between the locations of fixations and those of selected image features such as local contrast, high-spatial-frequency content, and edge density was also examined. It is shown that there is only weak similarity between the locations of fixations and those of any given local image feature, and the tendency of observers to fixate centrally on the image is identified as the principal reason for the low similarity values. It is shown that if the nonuniform distribution of eye movements is taken into account, significant similarities are found between the locations of fixations and those of certain image features, such as edge density.
Discrimination of Complex Patterns: Orientation Information is Integrated across Spatial Scale; Spatial-Frequency and Contrast Information are Not
Authors: Olzak Lynn A , Wickens Thomas D
Published: January 2007

Real-world objects are complex, containing information at multiple orientations and spatial scales. It is well established that at initial cortical stages of processing, local information about an image is separately represented at multiple spatial scales. However, it is not yet established how these early representations are later integrated across scale to signal useful information about complex stimulus features, such as edges and textures. In the studies reported here, we investigate the scale-integration processes involved in distinguishing among complex patterns. We use a concurrent-response paradigm in which observers simultaneously judge two components of compound gratings that differ widely in spatial frequency. In different experiments, each component takes one of two slightly different values along the dimensions of spatial frequency, contrast, or orientation. Using analyses developed within the framework of a multivariate extension of signal-detection theory, we ask how information about the frequency, contrast, or orientation of the components is or is not integrated across the two grating components. Our techniques permit us to isolate and identify interactions due to excitatory or inhibitory processes from effects due to noise, and to separately assess any attentional limitations that might occur in processing. Results indicate that orientation information is fully integrated across spatial scales within a limited orientation band and that decisions are based entirely on the summed information. Information about spatial frequency and contrast is not summed over spatial scale; cross-scale results show sensory independence. However, our results suggest that observers cannot simultaneously use information about frequency or contrast when it is presented at different spatial scales. Our results provide direct evidence for the existence of a higher-level summing circuit tailored to signal information about orientation. The properties of this mechanism differ substantially from edge-detector mechanisms proposed by Marr and others.
The Psychophysics of J-R-L Delboeuf (1831–1896)
Authors: Nicolas Serge , Murray David J , Farahmand Bahar
Published: January 2007

Delboeuf's writings on psychophysics are little known nowadays. The object of this paper is to describe the psychological contributions of this eminent Belgian psychologist of the second half of the 19th century. A true pioneer of experimental psychology, his work on psychophysics began in 1865 at the University of Gand (Ghent) but was not published until 1873 and following years. His work in this area is characterised on the one hand by the adoption of a logarithmic law relating sensation strength to stimulus strength, but which differed from that of Fechner; and on the other hand by the utilisation of a psychophysical technique based on brightness contrast (now called the ‘bisection method’). Even though Delboeuf was classified by Fechner in his later writings as an opponent of his beliefs, Delboeuf was nevertheless one of his least-virulent critics and the only psychologist of that era to have adopted a logarithmic law. Delboeuf's work is not only of historic interest; his original ideas possess sufficient interest for present-day psychophysicists to reexamine them.
The Craik—O'Brien—Cornsweet Illusion in Colour: Quantitative Characterisation and Comparison with Luminance
Authors: Wachtler Thomas , Wehrhahn Christian
Published: January 2007

The strength of the Craik–O'Brien–Cornsweet illusion was measured for different values of spatial and temporal stimulus parameters, in the traditional achromatic version, and in an isoluminant colour version. It was found that the illusion is much weaker with isoluminant colour stimuli than with achromatic luminance stimuli. The illusion depends on the spatial parameters of the stimulus in a way that yields an approximate scale invariance: The strength of the illusion is similar for different stimulus sizes, as long as the ratio of the width of the transition region around the edge, where luminance or colour change, to the total stimulus width is preserved. In both the achromatic and the chromatic case, the strength of the illusion decreases with increasing presentation time. The similarity of the differences between brightness and colour effects on one hand and the differences in sensitivity for colour and luminance changes in humans on the other suggests that a lack of gradient detection underlies the Craik–O'Brien–Cornsweet illusion.
Long-Range Twinkle Induction: An Achromatic Rebound Effect in the Magnocellular Processing System?
Authors: Tyler Christopher W , Hardage Lani
Published: January 2007

After viewing a blank region surrounded by a dynamic noise stimulus, viewers report the perception of prolonged dynamic twinkle in the unstimulated blank region. This twinkle aftereffect may be induced over long ranges in the visual field, up to 10° from the edge of the noise in central vision. Our previous studies of the properties of this aftereffect suggested mediation by the magnocellular processing system. We therefore evaluated the properties predicted by the magnocellular hypothesis by varying the coloring, the temporal and the spatial frequency of the stimulus. No aftereffect could be induced by an equiluminant color stimulus or by luminance noise below the temporal frequency of 5 Hz. The aftereffect obtained by luminance noise above 5 Hz was stronger for larger inducing elements. These results are consistent with known properties of the magnocellular processing system.
Perceptual, Oculomotor, and Neural Responses to Moving Color Plaids
Authors: Dobkins Karen R , Stoner Gene R , Albright Thomas D
Published: January 2007

Moving plaids constructed from two achromatic gratings of identical luminance contrast are known to yield a percept of coherent pattern motion, as are plaids constructed from two identical chromatic (eg isoluminant red/green) gratings. To examine the interactive influences of chromatic and luminance contrast on the integration of visual motion signals, we constructed plaids with gratings that possessed both forms of contrast. We used plaids of two basic types, which differed with respect to the phase relationship between chromatic and luminance modulations (after Kooi et al, 1992 Perception21 583–598). One plaid type (‘symmetric’) was made from component gratings that had identical chromatic/luminance phase relationships (eg both components were red-bright/green-dark modulation). The second plaid type (‘asymmetric’) was made from components that had complimentary phase relationships (ie one red-bright/green-dark grating and one green-bright/red-dark grating). Human subjects reported that the motion of symmetric plaids was perceptually coherent, while the components of asymmetric plaids failed to cohere. We also recorded eye movements elicited by both types of plaids to determine if they are similarly affected by these image cues for motion coherence. Results demonstrate that, under many conditions, eye movements elicited by perceptually coherent vs noncoherent plaids are distinguishable from one another. To reveal the neural bases of these perceptual and oculomotor phenomena, we also recorded the responses of neurons in the middle temporal visual area (area MT) of macaque visual cortex. Here we found that individual neurons exhibited differential tuning to symmetric vs asymmetric plaids. These neurophysiological results demonstrate that the neural mechanism for motion coherence is sensitive to the phase relationship between chromatic and luminance contrast, a finding which has implications for interactions between ‘color’ and ‘motion’ processing streams in the primate visual system.
W H R Rivers (1864 – 1922): The Founder of Research in Cross-Cultural Perception
Authors: Deręgowski Jan B
Published: January 2007

This paper presents a brief review of Rivers's contribution to psychology, especially to his cross-cultural studies of the basic perceptual processes of vision, and examines the lasting influence of his findings. It reports briefly on the scientific milieu in which Rivers carried out his work and traces the growth of his interest in the psychology of perception from the early days of his medical work to his appointment as a foundation lecturer of two English universities, London and Cambridge. It is argued that Rivers's contribution has been undervalued by psychologists.
The Differential Optomotor Response of the Four-Eyed Fish Anableps Anableps
Authors: Albensi Benedict C , Powell Joseph H
Published: January 2007

The perception of motion is important for the survival and reproduction of many animals, including fish. In the laboratory, support for this idea comes from the observation that many fish show a tendency to follow a series of stripes revolving around a circular aquarium. This response, known as the optomotor response (OMR), is recognized as an innate behavior in many species. The ‘four-eyed’ fishes of the genus Anableps are an unusual fish from Central and South America and actually have only two eyes. Each eye is divided into upper and lower halves internally and externally. This peculiar dual visual system allows Anableps to feed on creatures that swim or land near or on the water surface or to flee from flying predators attacking from above. It was hypothesized that Anableps should also possess the OMR. We used the OMR as a test to investigate potential differential visual processing in Anableps on normal and ‘blinded’ fish (the eyes are actually covered—not physically blinded). It was found that the OMR does exist in Anableps and that the strength of this response is dependent on the visual field being tested—a stronger OMR was seen as a result of visual stimulation from the aerial environment.
Understanding Dali's Slave Market with the Disappearing Bust of Voltaire: A Case Study in the Scale Information Driving Perception
Authors: Bonnar Lizann , Gosselin Frédéric , Schyns Philippe G
Published: January 2007

A generic problem in vision is to know which information drives the perception of a stimulus. We address this problem in a case study that involves the perceptual reversal of an ambiguous image (here, Dali's painting the Slave Market with the Disappearing Bust of Voltaire 1940). In experiment 1, we use ‘bubbles’ (Gosselin and Schyns, 2001 Vision Research41 2261–2271) to disambiguate the image and to determine the specific visual information that drives each possible perception (here, the nuns versus the bust of Voltaire). Experiment 2 validates that this information does determine the selective perception of the ambiguous image. We adapted the spatial-frequency channels of observers selectively to the information that mediates one of the two perceptions, to induce the opposite perception of the ambiguous image in a transfer phase. Together, the results suggest a method of revealing the visual information that drives perception.
Responses to the renovation of an irrigated perennial pasture in northern Victoria. 2. Botanical composition, and plant and tiller densities
Authors: Lawson A. R. , Kelly K. B.
Published: January 2007

A field experiment was established in northern Victoria in the autumn of 1999 to quantify the effects of renovating a 15-year-old, irrigated perennial pasture with a high paspalum content. The treatments were: (i) control, the existing pasture; (ii) oversown, the existing pasture grazed, topped and direct drilled; and (iii) resown, the existing pasture sprayed, cultivated and a new pasture sown. The grass species used in both renovation treatments were perennial ryegrass, Italian ryegrass and tall fescue. The treatments were grazed by dairy cows. The botanical composition, tiller density and plant frequency are reported in this paper. Oversowing with either perennial or Italian ryegrass increased the sown grass content by an average of 4–8% DM, and by up to 20% DM during winter and spring, but did not affect the average white clover, volunteer species or dead contents. Oversowing did not affect the sown grass or paspalum tiller densities but annual oversowing with either perennial or Italian ryegrass increased the ryegrass plant frequency and, in 2 of the 4 years, reduced the white clover growing point density. Resowing increased (P < 0.05) the content of sown grasses (by 12% DM for perennial ryegrass and by 20% DM for tall fescue) and white clover (by 8% DM) and decreased (P < 0.05) the content of volunteer species (by 18% DM) and, in years 1 and 2, dead material. The plant frequency of tall fescue increased over time (from 75 to 83% of quadrats), whereas that of perennial ryegrass declined (from 87 to 72% of quadrats). This resulted in the resown tall fescue having a lower (P < 0.05) white clover content and growing point density in years 3 and 4, and a tendency for a lower volunteer species content and tiller density in year 4, than the resown perennial ryegrass. Tall fescue is thus better able to resist the invasion of summer-active species and is less likely to require either oversowing or resowing than perennial ryegrass-based pastures. These results suggest that tall fescue should be considered as an alternative to perennial ryegrass when sowing pastures. The use of nitrogen did not improve the sown grass content, tiller density or plant frequency and will not therefore overcome problems resulting from a low ryegrass content.
Distortion product otoacoustic emissions measured as vibration on the eardrum of human subjects
Authors: Dalhoff E. , Turcanu D. , Zenner H.-P. , Gummer A. W.
Published: January 2007

It has previously not been possible to measure eardrum vibration of human subjects in the region of auditory threshold. It is proposed that such measurements should provide information about the status of the mechanical amplifier in the cochlea. It is this amplifier that is responsible for our extraordinary hearing sensitivity. Here, we present results from a laser Doppler vibrometer that we designed to noninvasively probe cochlear mechanics near auditory threshold. This device enables picometer-sized vibration measurements of the human eardrum
in vivo
. With this sensitivity, we found the eardrum frequency response to be linear down to at least a 20-dB sound pressure level (SPL). Nonlinear cochlear amplification was evaluated with the cubic distortion product of the otoacoustic emissions (DPOAEs) in response to sound stimulation with two tones. DPOAEs originate from mechanical nonlinearity in the cochlea. For stimulus frequencies,
f
1
and
f
2
, with
f
2
/
f
1
= 1.2 and
f
2
= 4–9.5 kHz, and intensities
L
1
and
L
2
, with
L
1
= 0.4
L
2
+ 39 dB and
L
2
= 20–65 dB SPL, the DPOAE displacement amplitudes were no more than 8 pm across subjects (
n
= 20), with hearing loss up to 16 dB. DPOAE vibration was nonlinearly dependent on vibration at
f
2
. The dependence allowed the hearing threshold to be estimated objectively with high accuracy; the standard deviation of the threshold estimate was only 8.6 dB SPL. This device promises to be a powerful tool for differentially characterizing the mechanical condition of the cochlea and middle ear with high accuracy.
The Spectrum of Doubly Ionized Titanium, Ti III
Authors: Bengt Edlén  , John W Swensson
Published: January 2007

The Ca I-like spectrum of titanium, Ti III, has been investigated by means of a pulsed hollow-cathode discharge. A total of 724 lines, covering the region from 630 to 9 300 Å, have been observed and classified, 597 of which lie above 2 000 Å. Practically all levels of the following configurations have been found: 3d4s, 5s, 6s; 4s2; 3d4p, 5p; 4s4p; 3d2; 3d4d, 5d; 3d4f, 5f; 3d5g, 6g; 3d6h. They exhibit a variety of different coupling cases and some interesting cases of configuration interaction. The series limit has been determined by applying the polarization formula to 5g, 6gand 6h, giving an ionization energy of 221 735.6±2 cm-1.
Term Analysis of Fe V
Authors: Jan Olof Ekberg
Published: January 2007

The spectrum of Fe V has been observed by using a vacuum sliding-spark discharge and the 10.7-m grazing-incidence spectrograph as well as the 10.7-m normal-incidence spectrograph at the National Bureau of Standards, Washington. Almost 1 000 lines have been identified in the region 302-1 715 Å, and all levels of 3d4and all but one level in each of the configurations 3d34sand 3d34phave been established. The estimated uncertainty of the level values is ±0.4 cm-1. From the complete set of 3d4levels the forbidden lines of Fe V from 828 to 10 000 Å are predicted, and a comparison is made with the spectrum of the star RR Telescopii.
Oscillator Strengths for the Lithium Isoelectronic Sequence from Spin-optimized SCF Wave Functions
Authors: Sten Lunell
Published: January 2007

Spin-optimized self-consistent field wave functions have been used to calculate oscillator strengths for transitions between the lowest states of Li and some of its isoelectronic ions. The results obtained are slightly better than those obtained by the ordinary Hartree-Fock method for some transitions, but differ very little from the Hartree-Fock results in the overwhelming majority of the transitions.
Spectrum and Term System of Ti XII
Authors: Jan Olof Ekberg  , Lars Åke Svensson
Published: January 2007

The spectrum of eleven times ionized titanium has been observed by using a condensed vacuum-spark discharge and a 5-m grazing-incidence spectrograph and a 3-m normal-incidence spectrograph. Fortythree lines have been identified in the region 52-960 Å. Thens- andnp-series have been extended ton= 6 and thend- andnf-series ton= 8. The derived ionization energy of Ti XII is 2 351 100±60 cm-1(291.49 eV).
Theoretical Analysis of the Hyperfine Interaction in msnl Configurations of Neutral Yb and Singly Ionized Lu
Authors: Lennarth Holmgren
Published: January 2007

Configuration with two open shells of the typemsnlfrom the spectra of Yb I and Lu II are analysed with respect to the hyperfine interaction. Radial integrals are evaluated from relativistic self-consistent-field wave-functions. Formulas are presented for the magnetic dipole and electric quadrupole interaction constants using the effective-operator formalism onLScoupled wavefunctions. The spin polarization contributions to the magnetic dipole interaction constants in a generalmsnlconfiguration are also presented. From such configurations in Yb I and Lu II, mean values of the electric quadrupole moments have been evaluated, givingQ(173Yb) = 3.6 b andQ(175Lu) = 5.3 b (uncorrected for the Sternheimer effect).
On Tornado Traps operated as Rotating Plasma Devices
Authors: B Lehnert
Published: January 2007

The possibility is being discussed of creating and heating the plasma in "Tornado" magnetic traps by means of the rotating plasma technique. On account of the particular field geometry of these traps, it is likely that the critical velocity phenomenon of rotating plasmas can be avoided.
Polymorphism in Metals I. Vibrational Free Energy
Authors: G Grimvall  , I Ebbsjö
Published: January 2007

At least 26 metals transform at ordinary pressure from a low temperature close-packed structure to a high temperature bcc phase. According to an old hypothesis of Zener, this is caused by a somewhat lower Debye temperature in a bcc lattice. This idea is investigated in detail and confirmed both by theoretical calculations and analysis of experimental data. Most polymorphic transformations occur quite close to the melting temperature but even so, anharmonicity does not cause the change in crystal structure.
Polymorphism in Metals II. Electronic and Magnetic Free Energy
Authors: G Grimvall
Published: January 2007

The paper considers the role of the electronic and magnetic free energy in stabilizing the frequently observed high temperature bcc phase in metals. For transition metals, the conduction band density of states depends on the lattice structure but yet the corresponding difference in the temperature dependence of the free energy is in general not large enough to be the main reason for the polymorphism. This is discussed in some detail for titanium and zirconium. For rare earths, neither the conduction electrons nor the localized 4fstates are effective in stabilizing a high temperature bcc structure. The form of the free energy well above the Curie temperature is compared for the localized and the itinerant models of magnetism. Although the band model gives a good description for most weakly magnetic systems, iron is an exception in this respect. Finally, it is concluded that a somewhat lower Debye temperature for the bcc lattice remains a major reason for the close-packed to bcc structural transformations of transition metals.
Levels in 115Sn
Authors: G Ch Madueme  , L Westerberg  , L O Edvardson  , M Migahed
Published: January 2007

An in-beam study of excited states in 115Sn has been made through the reactions 115In(p,n)115Sn, 112Cd(α,n)115Sn, 115In(d,2n)115Sn, and 113Cd(α,2n)115Sn. A level scheme containing 21 levels is proposed on the basis of the following measurements: γ-ray energies and intensities, excitation functions, conversion electron intensities, γ-γ- and e-γ-coincidences and angular distribution of γ-rays. The position of an odd parity state above the h11/2- single particle state is discussed.
Lifetime Measurements for Excited Levels in Cr II
Authors: B Engman  , A Gaupp  , L J Curtis  , I Martinson
Published: January 2007

Lifetimes for ten odd terms in Cr II which decay by transitions in the region 2 000-4 000 Å have been measured using the beam-foil technique. The results are compared with previous experimental data and available theoretical calculations.
Mean-life Measurements for Levels in BI-BIV
Authors: J A Kernahan  , E H Pinnington  , A E Livingston  , D J G Irwin
Published: January 2007

We have studied beam-foil spectra of boron in the wavelength range 385 Å to 5 000 Å, and measured mean lives for 35 levels in B I-B IV. Where possible, we have deduced experimental oscillator strengths for the transitions studied, and we compare our results with other work both theoretical and experimental.
Resistivity Phenomena in Plasmas with Strong Langmuir Turbulence
Authors: V N Tsytovich  , L Stenflo
Published: January 2007

We demonstrate that the collision integral for a plasma can be significantly changed by the presence of strong Langmuir turbulence. By means of a particular collision model it is shown that currents, which decay slowly in time, may exist.
Effects of cyclization on conformational dynamics and binding properties of Lys48‐linked di‐ubiquitin
Authors: Dickinson Bryan C. , Varadan Ranjani , Fushman David
Published: January 2007

In solution, Lys48‐linked di‐ubiquitin exists in dynamic equilibrium between closed and open conformations. To understand the effect of interdomain motion in polyubiquitin chains on their ability to bind ligands, we cyclized di‐ubiquitin by cross‐linking the free C terminus of the proximal ubiquitin with the side chain of residue 48 in the distal ubiquitin, using a chemical cross‐linker, 1,6‐Hexane‐bis‐vinylsulfone. Our NMR studies confirm that the cyclization affects conformational dynamics in di‐ubiquitin by restricting opening of the interface and shifting the conformational equilibrium toward closed conformations. The cyclization, however, did not rigidly lock di‐ubiquitin in a single closed conformation: The chain undergoes slow exchange between at least two closed conformations, characterized by interdomain contacts involving the same hydrophobic patch residues (Leu8‐Ile44‐Val70) as in the uncyclized di‐ubiquitin. Lowering the pH changes the relative populations of these conformations, but in contrast with the uncyclized di‐ubiquitin, does not lead to opening of the interface. This restriction of domain motions inhibits direct access of protein molecules to the hydrophobic patch residues located at the very center of the interdomain interface in di‐ubiquitin, although the residual motions are sufficient to allow access of small molecules to the interface. This renders di‐ubiquitin unable to bind protein molecules (e.g., UBA2 domain) in the normal manner, and thus could interfere with Ub2 recognition by various downstream effectors. These results emphasize the importance of the opening/closing domain motions for the recognition and function of di‐ubiquitin and possibly longer polyubiquitin chains.
Crystal structure of human μ‐crystallin complexed with NADPH
Authors: Cheng Zhongjun , Sun Lihua , He Jianhua , Gong Weimin
Published: January 2007

Human cytosolic 3,5,3′‐triiodo‐L‐thyronine‐binding protein, also called μ‐crystallin or CRYM, plays important physiological roles in transporting 3,5,3′‐triiodo‐L‐thyronine (T3) into nuclei and regulating thyroid‐hormone‐related gene expression. The crystal structure of human CRYM's bacterial homolog Pseudomonas putida ornithine cyclodeaminase and Archaeoglobus fulgidus alanine dehydrogenase have been available, but no CRYM structure has been reported. Here, we report the crystal structure of human CRYM bound with NADPH refined to 2.6 Å, and there is one dimer in the asymmetric unit. The structure contains two domains: a Rossmann fold–like NADPH‐binding domain and a dimerization domain. Different conformations of the loop Arg83–His92 have been observed in two monomers of human CRYM in the same asymmetric unit. The peptide bond of Val89–Pro90 is a trans‐configuration in one monomer but a cis‐configuration in the other. A detailed comparison of the human μ‐crystallin structure with its structurally characterized homologs including the overall comparison and superposition of active sites was conducted. Finally, a putative T3‐binding site in human CRYM is proposed based on comparison with structural homologs.
Site of deposition and absorption of an inhaled hydrophilic solute
Authors: Bondesson Eva , Bengtsson Thomas , Nilsson Lars‐Erik , Wollmer Per
Published: January 2007

Aims

To characterize the absorption kinetics and bioavailability of an inhaled hydrophilic solute deposited at various sites within the airways.

Methods

Nine healthy nonsmokers received one intravenous, one oropharyngeal and two pulmonary doses of technetium‐99 m‐labelled diethylene triamine pentaacetic acid (99mTc‐DTPA) in an open and crossover fashion. Pulmonary doses were administered as nebulized large and fine droplet‐sized aerosols by Pari and UltraVent nebulizers at fairly rapid and slow inhalation flows, respectively. Plasma concentration‐time profiles and 24 h urinary excretion of radioactivity were determined. One dose of 99mTc‐labelled Nanocoll, as a marker of mucociliary clearance (MCC), was also administered by Pari for similar lung deposition as the 99mTc‐DTPA and followed by repeated chest γ‐imaging.

Results

Intrapulmonary deposition patterns of 99mTc‐DTPA differed significantly (the mean ratio of penetration index (Pari : UltraVent) was 76% with 95% CI 63%, 91%). However, no differences in rate or extent of 99mTc‐DTPA absorption were detected. Mean absorption time was 1.8 h (mean difference (Pari–UltraVent): −0.1 h with 95% CI −0.6 h, 0.3 h) and the bioavailability was 70% (mean ratio (Pari : UltraVent): 101% with 95% CI 90%, 115%). The pulmonary elimination half‐life of 99mTc‐Nanocoll (8 h and 45 min) was significantly longer than that of 99mTc‐DTPA (less than 2 h). The oral bioavailability of 99mTc‐DTPA was estimated to be 3.1%.

Conclusions

The main elimination pathway of the inhaled hydrophilic solute 99mTc‐DTPA from the lungs is trans‐epithelial absorption. Despite different intrapulmonary radioaerosol deposition patterns, as verified by gamma scintigraphy, no differences in 99mTc‐DTPA absorption kinetics or bioavailability were detected.
Fine needle aspiration cytology of solitary fibrous tumours of the pleura
Authors: Cho E. Y. , Han J. J. , Han J. , Oh Y. L.
Published: January 2007

Objective:  To analyse fine needle aspirates from solitary fibrous tumour (SFT) of the pleura and to elucidate the cytological features unique to these tumours and differential diagnostic findings of benign and malignant SFTs.

Methods:  Fine needle aspiration (FNA) cytology slides from eight cases of SFT of the pleura, including six benign and two malignant SFTs, were reviewed. The subsequent histological slides were also examined.

Results:  Cytological diagnoses from six histologically proven cases of benign SFTs were low‐grade sarcoma (one), non‐small cell carcinoma (one), malignant tumour (1) and benign (three). Two cases of malignant SFTs were cytologically diagnosed as malignancy. The aspirates showed a varying degree of cellularity. Most smears were composed of single, scattered fusiform cells, and irregular loose aggregates of oval to spindle cells intimately admixed with dense collagenous stroma. Two malignant SFTs had a greater number of cells in clusters, and displayed mitotic activity, without significant cytological atypia.

Conclusions:  The diagnosis of SFT may be suggested by a combination of cytological and radiological findings. The precise determination of malignancy for SFT, however, is not usually straightforward on the basis of cytological features alone. The findings of highly cellular clusters and mitotic activity in the FNA cytological smear can help differentiate malignant from benign SFTs.
Climate and demography of the planktivorous Cassin's aukletPtychoramphus aleuticusoff northern California: implications for population change
Authors: LEE DEREK E. , NUR NADAV , SYDEMAN WILLIAM J.
Published: January 2007

We performed demographic analyses on Cassin's aukletPtychoramphus aleuticus, a zooplanktivorous seabird inhabiting the variable California Current System, to understand how temporal environmental variability influences population dynamics.

We used capture–recapture data from 1986 to 2002 to rank models of interannual variation in survival, breeding propensity, breeding success, and recruitment.

All demographic parameters exhibited temporal variability. Interannual variation in survival was best modelled as a nonlinear function of the winter Southern Oscillation Index (SOI). Breeding propensity was best modelled as a threshold function of local sea surface temperature. Breeding success and recruitment were best modelled with year‐dependent annual variation.

Changes in the SOI force El Niño/La Niña events, which in turn alter prey availability to seabirds in this system. Demographic responses varied during El Niños/La Niñas. Survival diminished substantially during the 1997–98 El Niño event, while breeding propensity was affected during both the 1992 and 1998 El Niños. Breeding success was reduced during the 1992, 1993, and 1998 El Niños, but was unusually high in 2002. Recruitment was higher at the beginning and end of this time‐series.

While demographic responses varied interannually, parameter values covaried in a positive fashion, a situation conducive to rapid population change. During the 11 years study period, the Farallon auklet breeding population declined at 6·05 ± 0·80% (SE) per year, a cumulative decline of 49·7%. This study demonstrates how climate variability has influenced key demographic processes for this diminished marine bird population.
Genetic diversity and mass resources promote colony size and forager densities of a social bee (Bombus pascuorum) in agricultural landscapes
Authors: HERRMANN FARINA , WESTPHAL CATRIN , MORITZ ROBIN F. A. , STEFFAN‐DEWENTER INGOLF
Published: January 2007

Although habitat fragmentation and agricultural intensification are known as threads to pollinator diversity, little is known about consequences for population size and genetic diversity. Here, we combined detailed field observations, molecular approaches and GIS‐based quantification of landscape structure (measured by proportions of seminatural habitats and proportions of mass flowering crops) to get new insights into driving forces of population dynamics of the bumblebee speciesBombus pascuorum. Comparing 13 agriculturally dominated landscape sectors, we found the proportion of mass flowering crops to positively influence bumblebee abundance whereas the proportion of seminatural habitats was of minor importance. We used microsatellites to quantify landscape‐related colony densities, inbreeding and population substructure. Detected colony densities did not correlate with landscape parameters or with local worker abundance, measured by field observations. These results indicate that increased worker abundances within landscapes are rather due to greater colony sizes than due to an increased number of nests. We found significant population substructure, measured byFSTand seven landscape sectors to bear significantly increased inbreeding values (FIS).FISwas strongly varying between sectors but did not correlate with landscape structure. Moreover,FIShad a significantly negative effect on colony size, demonstrating the importance of genetic diversity on population fitness at a landscape scale. We suggest that inbreeding levels might be related to the temporal variation of food resources and population sizes in agricultural landscapes.
Phylogeography and conservation genetics of a giant lobelia (Lobelia giberroa) in Ethiopian and Tropical East African mountains
Authors: KEBEDE MULUGETA , EHRICH DOROTHEE , TABERLET PIERRE , NEMOMISSA SILESHI , BROCHMANN CHRISTIAN
Published: January 2007

Lobelia giberroa is a giant rosette plant growing in the afro‐montane belt of the afro‐alpine environment, a unique and little‐studied ecosystem occupying the high mountains of eastern Africa. We analysed amplified fragment length polymorphisms (AFLPs) from 11 mountain systems in Ethiopia and Tropical East Africa to infer the phylogeographical history of the species. A total of 191 individuals were investigated from 25 populations. Principal coordinate analysis and population structure analyses revealed three major phylogeographical groups: the Ethiopian mountains and one group on each side of the Rift Valley in Tropical East Africa, respectively: Elgon–Cherangani and Kenya–Aberdare–Kilimanjaro–Meru. Analysis of Molecular Variance showed 55.7% variance among the three groups, suggesting an old divergence. Together with a clear geographical substructure within the main groups, this pattern indicates gradual expansion and supports the montane forest bridge hypothesis, stating that the area occupied by forest was larger and more continuous in previous interglacials and earlier in the present interglacial. Genetic diversity was lower in Ethiopia than in the other two main groups, possibly due to an ancient founder effect when Ethiopia was colonized from the south.
Dual pulse intestinal electrical stimulation normalizes intestinal dysrhythmia and improves symptoms induced by vasopressin in fed state in dogs
Authors: Qi H. , Liu S. , Chen J. D. Z.
Published: January 2007

Abstract  To assess effects of dual pulse intestinal electrical stimulation (DPIES) on intestinal dysrhythmia and motility, and symptoms induced by vasopressin in conscious dogs. The study was performed in three postprandial sessions (control; vasopressin; DPIES) in six dogs with two pairs of electrodes chronically implanted on the serosal surface of the proximal jejunum and with a chronic duodenal fistula. A manometric catheter was advanced into the small intestine via the intestinal cannula. Motility and intestinal slow waves were recorded. Symptoms were assessed. During vasopressin infusion, the percentage of normal intestinal slow wave frequency was decreased (P < 0.01), reflected as a significant increase in the percentage of both bradygastria and tachygastria; the motility index decreased (P < 0.01) and the symptom score increased (P < 0.01). In the session of DPIES, the percentage of normal slow wave frequency was recovered (P < 0.05 vs vasopressin), attributed to a reduction in both bradyarrhythmia and tachyarrhythmia; the symptom score was reduced (P < 0.05 vs vasopressin); the motility index was not significantly increased. These results suggest that vasopressin induces intestinal dysrhythmia and emetic symptoms and inhibits intestinal motility. Dual pulse intestinal electrical stimulation is capable of improving intestinal dysrhythmia and emetic symptoms but not impaired intestinal motility induced by vasopressin.
Spontaneous Uterine Leiomyosarcoma in a Golden Hamster (Mesocrietus auratus)
Authors: Kondo H. , Kimoto H. , Shibuya H. , Shirai W. , Matsuo K. , Sato T.
Published: January 2007

Uterine leiomyosarcoma occurring spontaneously in a domestic golden hamster was examined histologically and immunohistochemically. The histological findings for this tumour were similar to those for leiomyosarcomas described in other species. Immunohistochemical examination demonstrated the positivity of neoplastic cells with α‐smooth muscle actin and desmin. From the results mentioned above, the tumour of this case was revealed to be of smooth muscle origin. To our knowledge, this is the first report of a uterine leiomyosarcoma in domestic golden hamsters.
Bispectral index monitored balanced anesthesia technique for pheochromocytoma resection
Authors: MADDALI MADAN MOHAN , MATREJA PRAKASH VIRU
Published: January 2007

Balanced anesthesia under bispectral index monitoring was administered to a child undergoing a pheochromocytoma resection. By titration of anesthesia depth, the stress response during resection could be avoided as well as postresection hypotension, without resort to additional pharmacological manipulation.