Identification of stuttering in bilingual Lebanese children across two presentation modes

The goals of this study were to investigate whether Lebanese speech-language pathologists (SLPs) are accurate at identifying stuttering in bilingual children, to examine whether the use of video-recordings instead of audio-recordings allows for better analyses, and to explore factors that may affect the SLPs' judgments. In phase 1, 32 SLPs listened to narrative samples in Lebanese Arabic of 6 children who do not stutter (CWNS) and 2 who stutter (CWS). They were instructed to label each child as stuttering or not, and to explain what motivated their decisions. Afterwards, they were asked to provide background information by means of a questionnaire. In phase 2, they were asked to judge the same speech samples on the basis of video-recordings, and to explain for each child which speech characteristics they relied on to make their decisions. The results showed that misidentification happens frequently, is significantly more likely to happen with CWNS than with CWS, but also varies within these categories. Moreover, the use of video-recordings does not provide more reliable analyses of speech disfluencies, and speech samples' characteristics and bilingual profile rather than SLPs' characteristics seem to influence the judgments. Qualitative analyses indicate that, in the current study, misidentification may be driven by neglecting or misinterpreting physical concomitants. In general, the findings indicate that identifying and analyzing speech fluency behaviors remain a challenging perceptual task, which underlies the need for developing consistent methods for training students and clinicians in identifying stuttering, especially in a bilingual context.

Student Athletes' Causal Attributions for Sport and School Achievement in Relation to Sport Dropout and Grade Point Average

The present study longitudinally examined stability and change in the attributional profiles of Finnish student athletes (n = 391) in upper secondary sport schools. Moreover, it examined the extent to which these profiles, and changes in them, were associated with athletes' level of sport competition and school achievements and dropouts at the end of upper secondary sport school. Using latent profile analysis, five different and highly stable attributional profiles were identified for student athletes: (a) depressive (6.9%), (b) athletic self-serving (23.0%), (c) average (16.4%), (d) learned helplessness (30.9%), and (e) responsible (22.8%). The results further showed that over the 3-year study period, the responsible attributional style, wherein individuals take responsibility for successes and failures, predicted student athletes' subsequent high grade point average and low sport dropout rates even after controlling for the impacts of their earlier grade point average, gender, and type of sport.

Stuttering Severity Judgments by Speech-Language Pathologists of Bilingual Children Who Do and Do Not Stutter

Introduction: Recent studies conducted with bilingual populations have shown that bilingual children who do not stutter (CWNS) are often less fluent than their monolingual counterparts, which seems to affect the accuracy with which speech-language pathologists (SLPs) identify stuttering in bilinguals. That is, misdiagnosis appears frequently in bilingual children, and is more likely to occur with bilingual CWNS (false positives) than bilingual CWS (false negatives). Methods: The goal of the current study was to gain insight in the extent of this misdiagnosis. Speech samples of 6 Lebanese bilingual CWNS and 2 CWS were rated by Lebanese SLPs in an audio-only and audiovisual presentation mode. SLPs had to identify each child as stuttering or not and subsequently rate on a 6-point scale the stuttering severity for each child. SLPs also provided background information by means of a questionnaire. Results: The results showed that stuttering severity ratings (1) were on average significantly higher for CWS than for CWNS, (2) were for each CWS higher than for all but one of the CWNS, (3) varied significantly among the CWNS but not the CWS, (4) were not affected by the presentation mode, and (5) correlated positively with the percentage of stuttering-like disfluencies (SLD) and the mean number of iterations, but not with the percentage of other disfluencies (OD). Conclusion: Misdiagnosed bilingual CWNS are perceived by the SLPs as having a mild stutter, primarily based on the frequency of their disfluencies, but can be occasionally rated at par with CWS. Further research differentiating the disfluent speech of bilingual children who do and do not stutter is needed to reach a more adequate diagnosis of stuttering.

Coordination of pancreatic islet rhythmic activity by delayed negative feedback

Secretion of insulin from the pancreas is pulsatile, driven by intrinsic oscillations within individual islets of Langerhans. The secretions are coordinated among the many islets distributed throughout the pancreas producing a synchronized rhythm in vivo that is essential for maintaining normal glucose levels. One hypothesized mechanism for the coordination of islet activity is negative feedback, whereby sequestration of glucose in response to elevated insulin leads to a reduction in the blood glucose level that is sensed by the islet population. This global signal of glucose then coordinates the individual islets. In this study, we tested how this coordination mechanism is affected by time delays in the negative feedback, using a microfluidic system to monitor Ca2+ levels in a small population of islets and implementing glucose control through a negative feedback system. We found that islet synchronization occurs even with time delays in the feedback of up to 7 min. We also found that a second, slower closed-loop oscillation period is produced during delayed feedback in which islet oscillations are clustered into episodes. The period of this second oscillatory mode increases with the time delay and appears to be a second stable behavior that coexists with the faster synchronized oscillation. The general conclusion is that islet coordination through negative feedback is a viable means of islet coordination that is robust to delays in the timing of the feedback, and could complement other potential coordination mechanisms such as entrainment by pancreatic ganglia.NEW & NOTEWORTHY Insulin secretion from islets of Langerhans is rhythmic, and these rhythms are coordinated to produce oscillatory plasma insulin levels. Using a combination of microfluidics and computational modeling, we demonstrate that coordination can occur through negative feedback of the type provided by the liver, even if that feedback is delayed by several minutes. We also demonstrate that a second, slower, mode of oscillations can occur when feedback is delayed where faster oscillations are grouped into episodes.

Expanding horizons of cross-linguistic research on reading: The Multilingual Eye-movement Corpus (MECO)

Scientific studies of language behavior need to grapple with a large diversity of languages in the world and, for reading, a further variability in writing systems. Yet, the ability to form meaningful theories of reading is contingent on the availability of cross-linguistic behavioral data. This paper offers new insights into aspects of reading behavior that are shared and those that vary systematically across languages through an investigation of eye-tracking data from 13 languages recorded during text reading. We begin with reporting a bibliometric analysis of eye-tracking studies showing that the current empirical base is insufficient for cross-linguistic comparisons. We respond to this empirical lacuna by presenting the Multilingual Eye-Movement Corpus (MECO), the product of an international multi-lab collaboration. We examine which behavioral indices differentiate between reading in written languages, and which measures are stable across languages. One of the findings is that readers of different languages vary considerably in their skipping rate (i.e., the likelihood of not fixating on a word even once) and that this variability is explained by cross-linguistic differences in word length distributions. In contrast, if readers do not skip a word, they tend to spend a similar average time viewing it. We outline the implications of these findings for theories of reading. We also describe prospective uses of the publicly available MECO data, and its further development plans.

Pulsatile Basal Insulin Secretion Is Driven by Glycolytic Oscillations

In fasted and fed states, blood insulin levels are oscillatory. While this phenomenon is well studied at high glucose levels, comparatively little is known about its origin under basal conditions. We propose a possible mechanism for basal insulin oscillations based on oscillations in glycolysis, demonstrated using an established mathematical model. At high glucose, this is superseded by a calcium-dependent mechanism.

Lexize: A test to quickly assess vocabulary knowledge in Finnish

Proficiency in a language is strongly related to how well and how many words one knows. Vocabulary knowledge correlates with reading comprehension and general communication ability. Due to the increasing amount of research within the field of psycholinguistics and second language acquisition in Finnish, a standardized test to objectively measure Finnish vocabulary knowledge is called for. Lexize is such a test. It was modeled after LexTALE (Lemhöfer & Broersma, Behaviour Research Methods, 44:325-343, 2012), which was developed to measure vocabulary knowledge of English as a second language using visual lexical decision (VLD). Lexize is a VLD-based online test for Finnish that consists of 102 items. By comparing performance of L1 and L2 speakers of Finnish, Lexize was validated, returning considerable differences between test scores in native and non-native speakers. For non-native speakers there was a large range of test scores, correlating strongly with exposure to Finnish and self-ratings. In native speakers, test scores correlated with self-ratings, Finnish school grades, and age. In this group, higher Lexize scores were associated with a higher education level. We conclude that Lexize is a useful tool to assess Finnish vocabulary knowledge for non-native speakers and to some extent for native speakers. Lexize is available for free use at https://psyk.abo.fi/LexizeWeb/#/.

Prevalence of spelling errors affects reading behavior across languages

This cross-linguistic study investigated the impact of spelling errors on reading behavior in five languages (Chinese, English, Finnish, Greek, and Hebrew). Learning theories predict that correct and incorrect spelling alternatives (e.g., "tomorrow" and "tommorrow") provide competing cues to the sound and meaning of a word: The closer the alternatives are to each other in their frequency of occurrence, the more uncertain the reader is regarding the spelling of that word. An information-theoretic measure of entropy was used as an index of uncertainty. Based on theories of learning, we predicted that higher entropy would lead to slower recognition of words even when they are spelled correctly. This prediction was confirmed in eye-tracking sentence-reading experiments in five languages widely variable in their writing systems' phonology and morphology. Moreover, in each language, we observed a characteristic Entropy × Frequency interaction; arguably, its functional shape varied as a function of the orthographic transparency of a given written language. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Abstracts of the Scandinavian Workshop on Applied Eye Tracking (SWAET 2018)

This document contains the abstracts for the 2018 Scandinavian Workshop on Applied Eye Tracking (SWAET 2018) which was held at Copenhagen Business School, Denmark, 23 to 24 August, 2018..

Melt growth and properties of bulk BaSnO3 single crystals

We present the first-time growth of bulk BaSnO₃ single crystals from the melt by direct solidification, their basic electrical and optical properties as well as their structural quality. Our measurement of the melting point (MP) of BaSnO₃ amounts to 1855 °C  ±  25 K. At this temperature an intensive decomposition and non-stoichiometric evaporation takes place as the partial pressure of SnO(g) is about 90 times higher than that of BaO(g). X ray powder diffraction identified only the BaSnO₃ perovskite phase, while narrow rocking curves having a full width at half maximum of 26 arcsec and etch pit densities below 10⁶ cm^-2 confirm a high degree of structural perfection of the single crystals. In this respect they surpass the structural properties of those single crystals that were reported in the literature. The electrical conductivity of nominally undoped crystals depends on the growth conditions and ranges from insulating to medium n-type conductivity. After post-growth annealing in an oxidizing atmosphere undoped crystals are generally insulating. Doping the crystals with lanthanum during growth results in a high n-type conductivity. For a La doping concentration of 0.123 wt.% we measured an electron concentration of 3.3  ×  10¹⁹ cm^-3 and an electron mobility of 219 cm² V^-1 s^-1. Based on optical absorption measurements we determined an energy of 3.17  ±  0.04 eV at 5 K and of 2.99  ±  0.04 eV at 297 K for the indirect band gap of BaSnO₃.

Ambiguous Pronoun Resolution

A visual-world eye-tracking experiment investigated the influence of order of mention and grammatical role on resolution of ambiguous pronouns in Finnish. According to the first-mention account, general cognitive structure-building processes make the first-mentioned noun phrase the preferred antecedent of an ambiguous pronoun. According to the subject-preference account, the preferred antecedent is the grammatical subject of the preceding clause or sentence. Participants listened to sentences in either subject-verb-object or object-verb-subject order; each was followed by a sentence containing an ambiguous pronoun that referred to either the subject or the object. Participants' eye movements were monitored while they looked at pictures representing the two possible antecedents of each pronoun. Analyses of the fixations on the pictures showed that listeners used both order-of-mention and grammatical-role information to resolve ambiguous pronouns.

Nanoscopic yttrium oxide fluorides: non-aqueous fluorolytic sol-gel synthesis and structural insights by 19F and 89Y MAS NMR

Nanoscopic yttrium acetate fluorides Y(CH(3)COO)(3-z)F(z) and yttrium oxide fluorides YO(3-z)/(2)F(z )were prepared with tunable Y/F molar ratios via the fluorolytic sol-gel route. All samples were characterized by X-ray diffraction, elemental analysis and thermal analysis. In addition, local structures of all samples were studied by (19)F MAS, (19)F-(89)Y CP MAS and (1)H-(89)Y CP MAS NMR spectroscopy and the respective chemical shifts are given. For both classes of compounds, only the fluorination using one equivalent of F (z = 1) leads to defined, well crystalline matrices: yttrium acetate fluoride Y(CH(3)COO)(2)F and r-YOF.

Cascaded processing in written compound word production

In this study we investigated the intricate interplay between central linguistic processing and peripheral motor processes during typewriting. Participants had to typewrite two-constituent (noun-noun) Finnish compounds in response to picture presentation while their typing behavior was registered. As dependent measures we used writing onset time to assess what processes were completed before writing and inter-key intervals to assess what processes were going on during writing. It was found that writing onset time was determined by whole word frequency rather than constituent frequencies, indicating that compound words are retrieved as whole orthographic units before writing is initiated. In addition, we found that the length of the first syllable also affects writing onset time, indicating that the first syllable is fully prepared before writing commences. The inter-key interval results showed that linguistic planning is not fully ready before writing, but cascades into the motor execution phase. More specifically, inter-key intervals were largest at syllable and morpheme boundaries, supporting the view that additional linguistic planning takes place at these boundaries. Bigram and trigram frequency also affected inter-key intervals with shorter intervals corresponding to higher frequencies. This can be explained by stronger memory traces for frequently co-occurring letter sequences in the motor memory for typewriting. These frequency effects were even larger in the second than in the first constituent, indicating that low-level motor memory starts to become more important during the course of writing compound words. We discuss our results in the light of current models of morphological processing and written word production.

Establishment of a Cre recombinase based mutagenesis protocol for markerless gene deletion in Streptococcus suis

The lack of knowledge about pathogenicity mechanisms of Streptococcus (S.) suis is, at least partially, attributed to limited methods for its genetic manipulation. Here, we established a Cre-lox based recombination system for markerless gene deletions in S. suis serotype 2 with high selective pressure and without undesired side effects.

Two neural streams, one voice: pathways for theme and variation in the songbird brain

Birdsong offers a unique model system to understand how a developing brain - once given a set of purely acoustic targets - teaches itself the vocal-tract gestures necessary to imitate those sounds. Like human infants, to juvenile male zebra finches (Taeniopygia guttata) falls the burden of initiating the vocal-motor learning of adult sounds. In both species, adult caregivers provide only a set of sounds to be imitated, with little or no information about the vocal-tract gestures used to produce the sounds. Here, we focus on the central control of birdsong and review the recent discovery that zebra finch song is under dual premotor control. Distinct forebrain pathways for structured (theme) and unstructured (variation) singing not only raise new questions about mechanisms of sensory-motor integration, but also provide a fascinating new research opportunity. A cortical locus for a motor memory of the learned song is now firmly established, meaning that anatomical, physiological, and computational approaches are poised to reveal the neural mechanisms used by the brain to compose the songs of birds.

The effect of expertise on eye movement behaviour in medical image perception

The present eye-movement study assessed the effect of expertise on eye-movement behaviour during image perception in the medical domain. To this end, radiologists, computed-tomography radiographers and psychology students were exposed to nine volumes of multi-slice, stack-view, axial computed-tomography images from the upper to the lower part of the abdomen with or without abnormality. The images were presented in succession at low, medium or high speed, while the participants had to detect enlarged lymph nodes or other visually more salient abnormalities. The radiologists outperformed both other groups in the detection of enlarged lymph nodes and their eye-movement behaviour also differed from the other groups. Their general strategy was to use saccades of shorter amplitude than the two other participant groups. In the presence of enlarged lymph nodes, they increased the number of fixations on the relevant areas and reverted to even shorter saccades. In volumes containing enlarged lymph nodes, radiologists’ fixation durations were longer in comparison to their fixation durations in volumes without enlarged lymph nodes. More salient abnormalities were detected equally well by radiologists and radiographers, with both groups outperforming psychology students. However, to accomplish this, radiologists actually needed fewer fixations on the relevant areas than the radiographers. On the basis of these results, we argue that expert behaviour is manifested in distinct eye-movement patterns of proactivity, reactivity and suppression, depending on the nature of the task and the presence of abnormalities at any given moment.

The Role of Hyphens at the Constituent Boundary in Compound Word Identification

The current eye-movement study investigated whether a salient segmentation cue like the hyphen facilitates the identification of long and short compound words. The study was conducted in Finnish, where compound words exist in great abundance. The results showed that long hyphenated compounds (musiikki-ilta) are identified faster than concatenated ones (yllätystulos), but short hyphenated compounds (ilta-asu) are identified slower than their concatenated counterparts (kesäsää). This pattern of results is explained by the visual acuity principle ( Bertram & Hyönä, 2003 ): A long compound word does not fully fit in the foveal area, where visual acuity is at its best. Therefore, its identification begins with the access of the initial constituent and this sequential processing is facilitated by the hyphen. However, a short compound word fits in the foveal area, and consequently the hyphen slows down processing by encouraging sequential processing in cases where it is possible to extract and use information of the second constituent as well.

Processing Novel and Lexicalized Finnish Compound Words

Participants read sentences in which novel and lexicalized two-constituent compound words appeared while their eye movements were measured. The frequency of the first constituent of the compounds was also varied factorially and the frequency of the lexicalized compounds was equated over the two conditions. The sentence frames prior to the target word were matched across conditions. Both lexicality and first constituent frequency had large and significant effects on gaze durations on the target word; moreover the constituent frequency effect was significantly larger for the novel words. These results indicate that first constituent frequency has an effect in two stages: in the initial encoding of the compound and in the construction of meaning for the novel compound. The difference between this pattern of results and those for English prefixed words (Pollatsek, Slattery, & Juhasz, 2008) is apparently due to differences in the construction of meaning stage. A general model of the relationship of the processing of polymorphemic words to how they are fixated is presented.

Investigating heterogeneity of intracellular calcium dynamics in anterior pituitary lactotrophs using a combined modelling/experimental approach

Cell responses are commonly heterogeneous, even within a subpopulation. In the present study, we investigate the source of heterogeneity in the Ca(2+) response of anterior pituitary lactotrophs to a Ca(2+) mobilisation agonist, thyrotrophin-releasing hormone. This response is characterised by a sharp increase of cytosolic Ca(2+) concentration as a result of mobilisation of Ca(2+) from intracellular stores, followed by a decrease to an elevated plateau level that results from Ca(2+) influx. We focus on heterogeneity of the evoked Ca(2+) spike under extracellular Ca(2+) free conditions. We introduce a method that uses the information provided by a mathematical model to characterise the source of heterogeneity. This method compares scatter plots of features of the Ca(2+) response obtained experimentally with those made from the mathematical model. The model scatter plots reflect random variation of parameters over different ranges, and matching the experimental and model scatter plots allows us to predict which parameters are most variable. We find that a large degree of variation in Ca(2+) efflux is a likely key contributor to the heterogeneity of Ca(2+) responses to thyrotrophin-releasing hormone in lactotrophs. This technique is applicable to any situation in which the heterogeneous biological response is described by a mathematical model.

A tale of two rhythms: the emerging roles of oxytocin in rhythmic prolactin release

Hormone secretion often occurs in a pulsatile manner. In this review, we discuss two rhythms of in vivo prolactin release in female rats and the ongoing research that we and others have performed aiming to understand the mechanisms underlying them. The peptide hormone oxytocin appears to play an important role in both rhythms. One rhythm occurs during the first half of pregnancy, but can also be induced in ovariectomised rats. This is characterised by a circadian pattern with two prolactin surges per day. Two methods for triggering this rhythm are discussed, each utilising a unique physiological pathway that includes oxytocin action, presumably on pituitary lactotrophs. The second rhythm occurs during the oestrous cycle and is characterised by a surge of prolactin on the afternoon of pro-oestrus. We discuss recent findings that oxytocin is more effective at stimulating prolactin release from lactotrophs taken from animals on the afternoon of pro-oestrus than from those of animals on the morning of dioestrus 1, raising the possibility that this hormone plays a physiological role in the regulation of prolactin secretion during the oestrous cycle.

Development of parafoveal processing within and across words in reading: evidence from the boundary paradigm

In this study we used the boundary paradigm to examine whether readers extract more parafoveal information within than across words. More specifically, we examined whether readers extract more parafoveal information from a compound word's second constituent than from the same word when it is the noun in an adjective-noun phrase (kummitustarina "ghost story" vs. lennokas tarina "vivid story"). We also examined whether the processing of compound word constituents is serial or parallel and how parafoveal word processing develops over the elementary school years. Participants were Finnish adults and 8-year-old second-, 10-year-old fourth-, and 12-year-old sixth-graders. The results showed that for all age groups more parafoveal information is extracted from the second constituent within compounds than from the noun in adjective-noun phrases. Moreover, for all age groups we found evidence for parallel processing of constituents within compounds, but only when the compounds were of high frequency. In sum, the present study shows that attentional allocation extends further to the right and is more simultaneous when words are linguistically and spatially unified, providing evidence that attention in text processing is flexible in nature.

Synchronization of pancreatic islet oscillations by intrapancreatic ganglia: a modeling study

Plasma insulin measurements from mice, rats, dogs, and humans indicate that insulin levels are oscillatory, reflecting pulsatile insulin secretion from individual islets. An unanswered question, however, is how the activity of a population of islets is coordinated to yield coherent oscillations in plasma insulin. Here, using mathematical modeling, we investigate the feasibility of a potential islet synchronization mechanism, cholinergic signaling. This hypothesis is based on well-established experimental evidence demonstrating intrapancreatic parasympathetic (cholinergic) ganglia and recent in vitro evidence that a brief application of a muscarinic agonist can transiently synchronize islets. We demonstrate using mathematical modeling that periodic pulses of acetylcholine released from cholinergic neurons is indeed able to coordinate the activity of a population of simulated islets, even if only a fraction of these are innervated. The role of islet-to-islet heterogeneity is also considered. The results suggest that the existence of cholinergic input to the pancreas may serve as a regulator of endogenous insulin pulsatility in vivo.

Reading polymorphemic Dutch compounds: toward a multiple route model of lexical processing

This article reports an eye-tracking experiment with 2,500 polymorphemic Dutch compounds presented in isolation for visual lexical decision while readers' eye movements were registered. The authors found evidence that both full forms of compounds (dishwasher) and their constituent morphemes (e.g., dish, washer) and morphological families of constituents (sets of compounds with a shared constituent) played a role in compound processing. They observed simultaneous effects of compound frequency, left constituent frequency, and family size early (i.e., before the whole compound has been scanned) and also observed effects of right constituent frequency and family size that emerged after the compound frequency effect. The temporal order of these and other observed effects goes against assumptions of many models of lexical processing. The authors propose specifications for a new multiple-route model of polymorphemic compound processing that is based on time-locked, parallel, and interactive use of all morphological cues as soon as they become even partly available to the visual uptake system.

Comparison of skeletal muscle strength between cardiac patients and age-matched healthy controls

The purpose of the present study was to compare muscular strength of knee extensors and arm flexor muscles of cardiac patients (n = 638) and healthy controls (n = 961) in different age groups. Isometric torques were measured in a sitting position with the elbow, hip, and knee flexed to 90(0). For statistical analysis, age groups were pooled in decades from the age of 30 to 90 years. Additionally, the influence of physical lifestyle prior to disease on muscular strength was obtained in the patients. For statistical analysis three-way ANOVA (factors age, gender, and physical activity level) was used.Both in patients and in controls a significant age-dependent decline in maximal torque could be observed for arm flexors and knee extensors. Maximal leg extensor muscle showed statistically significant differences between healthy controls and cardiac patients as well as between subgroups of patients: Physically inactive patients showed lowest torques (male: 148 +/- 18 Nm; female: 82 +/- 25 Nm) while highest values were measured in control subjects (male: 167 +/- 16 Nm; female: 93 +/- 17 Nm). In contrast, arm flexor muscles did not show any significant influence of health status or sports history.This qualitative difference between weight-bearing leg muscles and the muscle group of the upper extremity suggest that lower skeletal muscle strength in heart patients is mainly a consequence of selective disuse of leg muscles rather than any pathological skeletal muscle metabolism. Since a certain level of skeletal muscle strength is a prerequisite to cope with everyday activities, strength training is recommended as an important part of cardiac rehabilitation.

Development of the letter identity span in reading: evidence from the eye movement moving window paradigm

By means of the moving window paradigm, we examined how many letters can be identified during a single eye fixation and whether this letter identity span changes as a function of reading skill. The results revealed that 8-year-old Finnish readers identify approximately 5 characters, 10-year-old readers identify approximately 7 characters, and 12-year-old and adult readers identify approximately 9 characters to the right of fixation. Comparison with earlier studies revealed that the letter identity span is smaller than the span for identifying letter features and that it is as wide in Finnish as in English. Furthermore, the letter identity span of faster readers of each age group was larger than that of slower readers, indicating that slower readers, unlike faster readers, allocate most of their processing resources to foveally fixated words. Finally, slower second graders were largely not disrupted by smaller windows, suggesting that their word decoding skill is not yet fully automatized.

Continuity conditions and torsion angles from ssNMR orientational restraints

The backbone torsion angle pair (varphi,psi) at each amino acid of a polypeptide is a descriptor of its conformation. One can use chemical shift and dipolar coupling data from solid-state NMR PISEMA experiments to directly calculate the torsion angles for the membrane-spanning portion of a protein. However, degeneracies inherent in the data give rise to multiple potential torsion angles between two adjacent peptide planes (a diplane). The molecular backbone structure can be determined by gluing together the consecutive diplanes, as in the PIPATH algorithm [T. Asbury, J.R. Quine, S. Achuthan, J. Hu, M.S. Chapman, T.A. Cross, R. Bertram, PIPATH: an optimized alogrithm for generating alpha-helical structures from PISEMA data, J. Magn. Reson. 183 (2006) 87-95.]. The multiplicities in torsion angles translate to multiplicities in diplane orientations. In this paper, we show that adjacent diplanes can be glued together to form a permissible structure only if they satisfy continuity conditions, described quantitatively here. These restrict the number of potential torsion angle pairs. We rewrite the torsion angle formulas from [J.R. Quine, M.T. Brenneman, T.A. Cross, Protein structural analysis from solid-state NMR-drived orientational constraints, Biophys. J. 72 (1997) 2342-2348.] so that they automatically satisfy the continuity conditions. The reformulated torsion angle formulas have been applied recently in the PIPATH algorithm [T. Asbury, J.R. Quine, S. Achuthan, J. Hu, M.S. Chapman, T.A. Cross, R. Bertram, PIPATH: an optimized alogrithm for generating alpha-helical structures from PISEMA data, J. Magn. Reson. 183 (2006) 87-95.] and will be helpful in other applications in which diplane gluing is used to construct a protein backbone model.

The role of interword spacing in reading Japanese: An eye movement study

The present study investigated the role of interword spacing in a naturally unspaced language, Japanese. Eye movements were registered of native Japanese readers reading pure Hiragana (syllabic) and mixed Kanji-Hiragana (ideographic and syllabic) text in spaced and unspaced conditions. Interword spacing facilitated both word identification and eye guidance when reading syllabic script, but not when the script contained ideographic characters. We conclude that in reading Hiragana interword spacing serves as an effective segmentation cue. In contrast, spacing information in mixed Kanji-Hiragana text is redundant, since the visually salient Kanji characters serve as effective segmentation cues by themselves.

PIPATH: an optimized algorithm for generating alpha-helical structures from PISEMA data

An optimized algorithm for finding structures and assignments of solid-state NMR PISEMA data obtained from alpha-helical membrane proteins is presented. The description of this algorithm, PIPATH, is followed by an analysis of its performance on simulated PISEMA data derived from synthetic and experimental structures. pipath transforms the assignment problem into a path-finding problem for a directed graph, and then uses techniques of graph theory to efficiently find candidate assignments from a very large set of possibilities.