bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Hermann Grid Illusion: A Tool for Studying Human Perceptive Field Organization
Authors: Spillmann Lothar 
Published: January 2007

Psychophysical research on the Hermann grid illusion is reviewed and possible neurophysiological mechanisms are discussed. The illusion is most plausibly explained by lateral inhibition within the concentric receptive fields of retinal and/or geniculate ganglion cells, with contributions by the binocular orientation-specific cortical cells. Results may be summarized as follows: (a) For a strong Hermann grid illusion to be seen bar width must be matched to the mean size of receptive-field centers at any given retinal eccentricity. (b) With the use of this rationale, the diameter of foveal perceptive-field centers (the psychophysical correlate of receptive-field centers) has been found to be in the order of 4–5 min arc and that of total fields (centers plus surrounds) 18 min arc. These small diameters explain why the illusion tends to be absent in foveal vision. (c) With increasing distance from the fovea, perceptive-field centers increase to 1.7 deg at 15 deg eccentricity and then to 3.4 deg at 60 deg eccentricity. This doubling in diameter agrees with the change in size of retinal receptive-field centers in the monkey. (d) The Hermann grid illusion is diminished with dark adaptation. This finding is consistent with the reduction of the center—surround antagonism in retinal receptive fields. (e) The illusion is also weakened when the grid is presented diagonally, which suggests a contribution by the orientation-sensitive cells in the lateral geniculate nucleus and visual cortex. (f) Strong induction effects, similar to the bright and dark spots in the Hermann grid illusion, may be elicited by grids made of various shades of grey; and by grids varying only in chroma or hue. Not accounted for are: the illusory spots occurring in an outline grid ie with hollow squares, and the absence of an illusion when extra bars are added to the grid. Alternative explanations are discussed for the spurious lines connecting the illusory spots along the diagonals and the fuzzy dark bands traversing the rhombi in modified Hermann grids.
Structural Description Theories: Is RBC/JIM a General-Purpose Theory of Human Entry-Level Object Recognition?
Authors: Kurbat Matthew A 
Published: January 2007

A long-standing problem in structural description theories of object recognition has been the lack of concrete proposals for parts, methods of dividing objects into parts, and relations between parts. Biederman's RBC theory and Hummel and Biederman's JIM model are seminal works because they present one of the first concrete solutions to this very difficult problem: RBC/JIM in turn played a major role in turning object recognition into a burgeoning research area. Here, a review of RBC/JIM as the state-of-the-art structural description theory of recognition is presented. A main conclusion is that there are strong limitations on the scope of objects which RBC/JIM can represent, and hence recognize, because mechanisms for dividing objects into parts and representing parts are not general purpose. Nevertheless, RBC/JIM has promise as a model of geometric object recognition, and there are other directions that may be pursued in the interest of developing a more general-purpose theory.
Mental Rotation of a Tactile Layout by Young Visually Impaired Children
Authors: Ungar Simon , Blades Mark , Spencer Christopher 
Published: January 2007

Mental rotation tasks have been used to probe the mental imagery both of sighted and of visually impaired people. People who have been blind since birth display a response pattern which is qualitatively similar to that of sighted people but tend to respond more slowly or with a higher error rate. It has been suggested that visually impaired people code the stimulus and its (or their own) motion in a different way from sighted people—in particular, congenitally blind people may ignore the external reference framework provided by the stimulus and surrounding objects, and instead use body-centred or movement-based coding systems. What has not been considered before is the relationship between different strategies for tactually exploring the stimulus and the response pattern of congenitally blind participants. Congenitally blind and partially sighted children were tested for their ability to learn and recall a layout of tactile symbols. Children explored layouts of one, three, or five shapes which they then attempted to reproduce. On half the trials there was a short pause between exploring and reproducing the layouts. In an aligned condition children reproduced the array from the same position at which they had explored it; in a rotated condition children were asked to move 90° round the table between exploring and reproducing the layout. Both congenitally blind and partially sighted children were less accurate in the rotated condition than in the aligned condition. Five distinct strategies used by the children in learning the layout were identified. These strategies interacted with both visual status and age. We suggest that the use of strategies, rather than visual status or chronological age, accounts for differences in performance between children.
The Perception of Surface Folding in Static and Animated Displays
Authors: Massironi Manfredo , Bruno Nicola 
Published: January 2007

How do we interpret outline drawings of surfaces? Although pictorial depictions are projectively ambiguous, observers demonstrate definite preferences of interpretation. Additionally, they commit typical errors. A study is reported of one specific arrangement of surfaces as it is represented in outline drawings, namely the arrangement that results when two arbitrary surfaces are joined at a common edge to form an angle in 3-D (‘phenomenic folding’). With some of these arrangements, observers report that the angle formed by the two surfaces is zero (complete folding). With others, they report that the angles are greater than zero (incomplete folding). Both interpretations are actually valid. Several investigators have proposed that observer preferences such as these are due to a tendency to prefer a 3-D interpretation that will make the depicted 3-D shape regular. Three experiments were performed to test this regularisation hypothesis. In the first, observers were shown pairs of four-sided polygons joined at one equal side. Their task was to imagine how the smaller polygon could be folded completely towards the larger, and, subsequently, to report on its position after the folding (‘mental folding’). Reported positions were consistent with 3-D interpretations that caused figural regularisations. In the second and third experiments, observers were shown drawings of diamonds and parallelograms folded along a number of differently positioned and oriented segments (‘folding edge’). Their task was to estimate verbally the extent of the dihedral angle formed by the two surfaces. Results indicated that the perception of incomplete folding is determined by 3-D interpretation of the orientation of the drawing with respect to the picture plane. In a fourth experiment, observers were asked whether projective equivalences might be disambiguated by animating two kinds of displays that yield the ‘incomplete folding’ effect but that should be distinguishable on the basis of the trajectories of the vertexes of the folding parts. Results demonstrated that even in these conditions observers are unable to interpret the foldings correctly. These results might be taken to indicate that projective, static information leading to a simpler and more regular interpretation of the display can prevail over explicit motion information that should force the system to achieve a nonregular solution.
Large Scale Differences between Haptic and Visual Judgments of Curvature
Authors: Kappers Astrid M L , Koenderink Jan J , Oudenaarden Gerlene 
Published: January 2007

Large systematic scale differences show up when subjects are asked to match the curvature of a haptically presented surface with a visually presented cross section. Scaling factors ranging from 0.3 to 3.0 were found. Most often (for five out of six subjects) haptically estimated curvature was overestimated relative to visual curvature. We conclude that mutually inconsistent representations of surface curvature coexist in a single observer in the haptic and visual modalities. Another conclusion can be drawn with certainty, namely that at least one of the two modalities does not provide the observer with veridical information. The results for the left and the right hand of a subject were very similar, though for two subjects there existed a small significant difference in scaling. It seems likely that the curvature representations of the two hands are not independent of one another, but our data do not permit us to be conclusive.
Hyperfine Interaction, Zeeman and Stark Effects for Excited States in Potassium
Authors: G Belin  , L Holmgren  , I Lindgren  , S Svanberg  
Published: January 2007

Using the optical double resonance and level crossing methods, properties of several excitedS,P, andDstates in39K were studied. TheSandDstates were populated using stepwise excitation with the firstPstate as an intermediate level. An rf lamp and a CW dye laser were used in the first and second excitation steps, respectively. The studiedPstates were populated in the cascade decay of states, excited with the laser. The following results for the magnetic depole interaction constant a, the LandégJfactor, and the tensor polarizability α2were obtained for the studied states:72S1/2: a = 10.78(5) MHz,gJ= 2.0020(10);82S1/2: a = 5.99(8) MHz,gJ= 2.0028(12);62P1/2: a = 4.05(7) MHz,gJ= 0.6663(4);62P3/2: a = 0.89(5) MHz,gJ= 1.3337(8);72P1/2: a = 2.18(5) MHz,gJ= 0.6659(6);72P3/2: a = 0.49(4) MHz,gJ= 1.3336(8);52D3/2: |a| = 0.44(10) MHz,gJ= 0.7997(7), |α2| = 9.64(45) MHz/(kV)/cm)2;52D5/2: |a| = 0.24(7) MHz,gJ= 1.2004(10), |α2| = 13.4(7) MHz/(kV)/cm)2;62D3/2: |a| = 0.2(2) MHz,gJ= 0.7997(14), |α2| = 33.8(1.7) MHz/(kV)/cm)2;62D5/2: |a| = 0.1(1) MHz,gJ= 1.2013(20), |α2| = 47.6(2.4) MHz/(kV)/cm)2.Theoretical values for the magnetic dipole interaction constant have been obtained using a limited many-body perturbation expansion. The Polarization effect, which is due to single excitations from the restricted Hartree-Fock model, is included to all orders, while the true correlation effect is omitted. The results are compared with the experimental values, and the agreement is found to be quite good. For theSandPstates the polarization effect is of the order of 10-20%, and it is responsible for roughly half of the deviation of the Hartree-Fock values from experiment. For theDstates, on the other hand, the effects are much more drastic. The sign of theafactors has not been measured. The perturbative calculation yields positive values for all2D3/2states and negative values for all2D5/2 states. The theoretical magnitudes are in agreement with the observed ones.
Design of a functionally equivalent nonglycosylated analog of the glycopeptide antibiotic formaecin I
Authors: Kaur Kanwal J. , Pandey Shashank , Salunke Dinakar M. 
Published: January 2007

AbstractVarious nonglycosylated analogs were designed in order to explore the role of glycosylation in formaecin I, an antibacterial glycopeptide of insect origin. The functional behavior of a designed nonglycosylated analog (P7,endo P8a,ΔT11)formaecin I was found to be similar to that of native glycosylated peptide. Both the peptides showed similar antibacterial activities against Escherichia coli and Salmonella strains. The designed nonglycosylated analog (P7,endo P8a,ΔT11)formaecin I has low binding affinity to LPS identical to that of native glycopeptide, formaecin I. Both the peptides have similar killing kinetics and are nontoxic to erythrocytes. Formaecin I and designed nonglycosylated (P7,endo P8a,ΔT11)formaecin I have no definite conformational features associated with them. The glycosylated residue of threonine in formaecin I and proline residues in designed peptide [(P7,endo P8a,ΔT11)formaecin I], possibly help in stabilizing the correct conformation that facilitates presentation of the peptide to its receptor. It is evident that a functionally equivalent nonglycosylated analog of native glycosylated antibacterial peptide can be designed by strategically modifying the sequence.
Diagnosis of Parietaria judaica pollen allergy using natural and recombinant Par j 1 and Par j 2 allergens
Authors: González‐Rioja R. , Ferrer A. , Arilla M.C. , Ibarrola I. , Viguera A.R. , Andreu C. , Martínez A. , Asturias J.A. 
Published: January 2007

SummaryBackground
Parietaria judaica pollen is one of the main causes of allergic diseases in the Mediterranean area and contains two major allergens, called Par j 1 and Par j 2.Objective
To evaluate the diagnostic potential of natural and recombinant forms of Par j 1 and Par j 2 in comparison with standardized P. judaica pollen extract.Methods
Thirty patients allergic to P. judaica pollen and 15 control patients were investigated. Skin prick tests and determination of specific IgE levels were performed with commercial P. judaica extract, natural Par j 1 and Par j 2, and recombinant forms of both allergens expressed in P. pastoris.Results
The whole group of patients with allergy to P. judaica had a positive skin test reaction to purified nPar j 1–Par j 2 and rPar j 2 at 5 μg/mL, and no false‐positive reactions were detected. Natural and recombinant Par j 1 and Par j 2 showed no significantly different responses in skin tests compared with P. judaica extract. A high correlation was found between the serum‐specific IgE levels to P. judaica extract vs. natural (R=0.996; P<0.001) and recombinant allergens (R=0.887 and 0.982 for rPar j 1 and rPar j 2, respectively; P<0.001). rPar j 2 displayed a 100% sensitivity and specificity among P. judaica‐allergic patients.Conclusions
In vivo and in vitro diagnosis of P. judaica pollen allergy could be simplified using rPar j 2. This protein showed comparable IgE response and skin prick reactivity with those produced by P. judaica pollen extract.
Skin prick‐test reactivity to aeroallergens and allergic symptoms in an urban population of central Italy: a longitudinal study
Authors: Dottorini M. L. , Bruni B. , Peccini F. , Bottini P. , Pini L. , Donato F. , Casucci G. , Tantucci C. 
Published: January 2007

SummaryBackground
Cross‐sectional studies report an increasing prevalence of allergic diseases, such as rhinitis and asthma. Not thoroughly known, instead, is the natural history of allergic sensitization and the progress of the allergic disease‐related symptoms.Aim
The purpose of this study was to evaluate longitudinally the skin reactivity for the most common aeroallergens and the allergic symptoms in an urban population living in Perugia, a town of central Italy with a low‐level of air pollution exposure.Methods
In the 1998–1999 period 788 subjects were tested for skin reactivity to a panel of aeroallergens and underwent the administration of a questionnaire. These same subjects were part of a cohort of 1200 subjects who participated in a previous epidemiological study performed in 1984–1985 using the same tools. Subjects were aged between 14 and 64 years at the time of the first survey.Results
In the present survey 196 subjects (24.9%) had skin reactivity to at least one aeroallergen, while in the previous survey 143 subjects (18.1%) had skin prick‐test reactivity. The increase of the skin reactivity between the two observations was highly significant (P<0.001) and was mainly observed in subjects <40‐years old. The greatest increment in skin reactivity was seen to Dermatophagoides pteronyssinus (house dust mite) allergen. Data obtained from questionnaires showed that subjects who declared allergic symptoms increased from 341 (43.3%) to 380 (48.2%). However, the increase was significant (P<0.01) only in subjects who had a positive association between allergic symptoms and prick‐test reactivity and was greater for rhino‐conjunctivitis than for asthma‐related symptoms.Conclusions
In a cohort of urban population of the centre of Italy, exposed to a low and stable level of air pollution, the sensitization to common aeroallergens increased with time, mostly in people <40‐years of age. The greatest increment was found for indoor allergens such as Dermatophagoides pteronysimus. A significant increase in allergic symptoms, mainly related to rhino‐conjunctivitis, was observed only in the presence of positive prick test.
Smear cytology in the intra‐operative assessment of periodontoid pseudotumour of the craniocervical junction
Authors: Galloway M. , Amin A. , Casey A. , Crockard A. , Revesz T. 
Published: January 2007

Objective:  Periodontoid pseudotumours are lesions of presumed degenerative aetiology which typically occur in elderly patients with cervical myelopathy. The clinical and radiological differential diagnosis includes neoplastic and inflammatory lesions, and the exclusion of such lesions may be of value in the intra‐operative management of the patient. This audit aimed to examine the value of intra‐operative smear cytology in the management of this condition.Methods:  The intra‐operative smear cytological features of four cases of periodontoid pseudotumour were reviewed.Results:  In each case the intra‐operative cytological interpretation was in keeping with a non‐neoplastic and non‐inflammatory process.Conclusion:  These results suggest that intra‐operative smear cytology can provide information on the value in the intra‐operative management of patients with this lesion.
Opportunism at work: habitat predictability affects reproductive readiness in free‐living zebra finches
Authors: PERFITO NICOLE , ZANN RICHARD A. , BENTLEY GEORGE E. , HAU MICHAELA 
Published: January 2007

SummaryOpportunistic breeding (i.e. breeding whenever favourable conditions occur, regardless of interval or periodicity) is a strategy often adopted by animals breeding in habitats where food resources important for offspring survival are unpredictable.One putative adaptation for this breeding strategy is the maintenance of a partially activated reproductive system year‐round. Breeding readiness is assumed to be the default state and reproduction is therefore suppressed only when environmental conditions become inhibitory.We tested this assumption in an opportunistic archetype, the Australian zebra finchTaeniopygia guttata, by comparing reproductive activation and suppression in free‐living zebra finches in two climatically different habitats: (1) an unpredictable habitat of arid central Australia, where breeding is closely tied to aperiodic rainfall and can occur during any month of the year, and (2) a more predictably seasonal habitat in southern Australia, where breeding occurs during approximately the same months each year. We quantified reproductive activation by measuring gonad size and circulating gonadotrophin concentration during the breeding and nonbreeding seasons in the predictable habitat and within a nonbreeding period during drought in the unpredictable habitat.We found reproductive readiness changed consistently between the breeding and nonbreeding state in the predictable habitat, but more nonbreeding birds in the unpredictable habitat maintained an activated reproductive system even though they had poorer body condition. We found no evidence for suppression of reproductive activity by stress hormones (i.e. elevated glucocorticoids). Furthermore, birds were able to activate the reproductive axis quickly when removed from inhibitory field conditions and responded equally well to various stimulatory cues.
Spatial analysis of nuclear and cytoplasmic DNA diversity in wild sea beet (Beta vulgarisssp.maritima) populations: do marine currents shape the genetic structure?
Authors: FIEVET VIRGIL , TOUZET PASCAL , ARNAUD JEAN‐FRANÇOIS , CUGUEN JOËL 
Published: January 2007

AbstractPatterns of seed dispersal in the wild sea beet (Beta vulgarisssp.maritima) are predicted to be influenced by marine currents because populations are widely distributed along the European Atlantic coast. We investigated the potential influence of marine currents on the pattern of spatial genetic structuring in natural populations of sea beet. Populations were located along the French coasts of the Anglo‐Norman gulf that features peculiar marine currents in the Channel.Thirty‐three populations were sampled, among which 23 were continental and 10 were insular populations located in Jersey, Guernsey and Chausey, for a total of 1224 plants genotyped. To validate the coastal topography influence and the possibility of marine current orientated gene flow on the genetic features of sea beet populations, we assessed patterns of genetic structuring of cytoplasmic and nuclear diversity by: (i) searching for an isolation‐by‐distance (IBD) pattern using spatial autocorrelation tools; (ii) using the Monmonier algorithm to identify genetic boundaries in the area studied; and (iii) performing assignment tests that are based on multilocus genotype information to ascertain population membership of individuals. Our results showed a highly contrasted cytoplasmic and nuclear genetic differentiation and highlighted the peculiar situation of island populations. Beyond a classical isolation‐by‐distance due to short‐range dispersal, genetic barriers fitting the orientation of marine currents were clearly identified. This suggests the occurrence of long‐distance seed dispersal events and an asymmetrical gene flow separating the eastern and western part of the Anglo‐Norman gulf.
Natural variation in the genetic architecture of a host–parasite interaction in the bumblebee Bombus terrestris
Authors: WILFERT L. , GADAU J. , BAER B. , SCHMID‐HEMPEL P. 
Published: January 2007

AbstractThe genetic architecture of fitness‐relevant traits in natural populations is a topic that has remained almost untouched by quantitative genetics. Given the importance of parasitism for the host's fitness, we used QTL mapping to study the genetic architecture of traits relevant for host–parasite interactions in the trypanosome parasite, Crithidia bombi and its host, Bombus terrestris. The three traits analysed were the parasite's infection intensity, the strength of the general immune response (measured as the encapsulation of a novel antigen) and body size. The genetic architecture of these traits was examined in three natural, unmanipulated mapping populations of B. terrestris. Our results indicate that the intracolonial phenotypic variation of all three traits is based on a network of QTLs and epistatic interactions. While these networks are similar between mapping populations in complexity and number of QTLs, as well as in their epistatic interactions, the variability in the position of QTL and the interacting loci was high. Only one QTL for body size was plausibly found in at least two populations. QTLs for encapsulation and Crithidia infection intensity were located on the same linkage groups.