Thomas O. Madsen

Early Vocabulary Development in Danish and other Languages: A CDI-Based Comparison.

The main objective of this paper is to describe the trajectory of Danish childrens early lexical development relative to other languages, by comparing a Danish study based on the Danish adaptation of The MacArthur-Bates Communicative Development Inventories (CDI) to 17 comparable CDI-studies. The second objective is to address the feasibility of cross-linguistic CDI-comparisons. The main finding is that the developmental trend of Danish childrens early lexical development is similar to trends observed in other languages, yet the vocabulary comprehension score in the Danish children is the lowest across studies from age 1 ; 0 onwards. We hypothesize that the delay is related to the nature of Danish sound structure, which presents Danish children with a harder task of segmentation. We conclude that CDI-studies are an important resource for cross-language studies, but reporting of studies needs to be standardized and the availability of published data improved in order to make comparisons more straightforward.

The Danish Communicative Developmental Inventories: validity and main developmental trends

This paper presents a large-scale cross-sectional study of Danish childrens early language acquisition based on the Danish adaptation of the MacArthur-Bates Communicative Development Inventories (CDI). Measures of validity and reliability imply that the Danish adaptation of the American CDI has been adjusted linguistically and culturally in appropriate ways which makes it suitable for tapping into Danish childrens language acquisition. The study includes 6,112 randomly selected children in the age of 0 ; 8 to 3 ; 0, and results related to the development of early gestures, comprehension and production of words as well as grammatical skills, are presented.

Dynamic Accuracy of GPS Receivers for Use in Health Research: A Novel Method to Assess GPS Accuracy in Real-World Settings.

The emergence of portable global positioning system (GPS) receivers over the last 10 years has provided researchers with a means to objectively assess spatial position in free-living conditions. However, the use of GPS in free-living conditions is not without challenges and the aim of this study was to test the dynamic accuracy of a portable GPS device under real-world environmental conditions, for four modes of transport, and using three data collection intervals. We selected four routes on different bearings, passing through a variation of environmental conditions in the City of Copenhagen, Denmark, to test the dynamic accuracy of the Qstarz BT-Q1000XT GPS device. Each route consisted of a walk, bicycle, and vehicle lane in each direction. The actual width of each walking, cycling, and vehicle lane was digitized as accurately as possible using ultra-high-resolution aerial photographs as background. For each trip, we calculated the percentage that actually fell within the lane polygon, and within the 2.5, 5, and 10 m buffers respectively, as well as the mean and median error in meters. Our results showed that 49.6% of all ≈68,000 GPS points fell within 2.5 m of the expected location, 78.7% fell within 10 m and the median error was 2.9 m. The median error during walking trips was 3.9, 2.0 m for bicycle trips, 1.5 m for bus, and 0.5 m for car. The different area types showed considerable variation in the median error: 0.7 m in open areas, 2.6 m in half-open areas, and 5.2 m in urban canyons. The dynamic spatial accuracy of the tested device is not perfect, but we feel that it is within acceptable limits for larger population studies. Longer recording periods, for a larger population are likely to reduce the potentially negative effects of measurement inaccuracy. Furthermore, special care should be taken when the environment in which the study takes place could compromise the GPS signal.

Danish children's first words: Analysing longitudinal data based on monthly CDI parental reports

Using the Danish adaptation of the MacArthur-Bates Communicative Development Inventories (CDI), first language acquisition of 183 Danish children has been studied longitudinally on a monthly basis (8—30 months). Focussing on production, we study early lexical development from the very first word until roughly 100 words are produced, dividing this period into the stages of first-1, -10, -25, -50 and -100 words. We analyse Danish childrens first words with respect to semantic-pragmatic content, sound structure, and composition of the early lexicon based on formal linguistic categories. Comparing Danish results crosslinguistically reveals both the overall typicality of Danish childrens first words as well as striking differences for some single words.

Girls talk about dolls and boys about cars?: Analyses of group and individual variation in Danish children's first words

Based on data from the Danish Longitudinal CDI study on 182 Danish children, we analyse aspects of variation in the childrens first 100 words (produced). First, we demonstrate the effect of gender and birth order (number of siblings) on acquisition times of first words by identifying single words which are significantly earlier in the productive repertoire of, for instance, girls versus boys. We also investigate the effect of the same factors on the composition of the vocabulary where the definition of categories (word classes) is based on the CDIs thematic categorization. Finally, we investigate the individuality of the lexicons composition and find time-persistent differences between children for some word classes at this early stage.

Developing Suitable Buffers to Capture Transport Cycling Behavior

The association between neighborhood built environment and cycling has received considerable attention in health literature over the last two decades, but different neighborhood definitions have been used and it is unclear which one is most appropriate. Administrative or fixed residential spatial units (e.g., home-buffer-based neighborhoods) are not necessarily representative for environmental exposure. An increased understanding of appropriate neighborhoods is needed. GPS cycling tracks from 78 participants for 7 days form the basis for the development and testing of different neighborhood buffers for transport cycling. The percentage of GPS points per square meter was used as indicator of the effectiveness of a series of different buffer types, including home-based network buffers, shortest route to city center buffers, and city center-directed ellipse-shaped buffers. The results show that GPS tracks can help us understand where people go and stay during the day, which can help us link built environment with cycling. Analysis showed that the further people live from the city center, the more elongated are their GPS tracks, and the better an ellipse-shaped directional buffer captured transport cycling behavior. In conclusion, we argue that in order to be able to link built environment factors with different forms of physical activity, we must study the most likely area people use. In this particular study, to capture transport cycling, with its relatively large radius of action, city center-directed ellipse-shaped buffers yielded better results than traditional home-based network buffer types. The ellipse-shaped buffer types could therefore be considered an alternative to more traditional buffers or administrative units in future studies of transport cycling behavior.

Changes in Maximum Muscle Strength and Rapid Muscle Force Characteristics after Long-Term Special Support and Reconnaissance Missions: A Preliminary Report

PURPOSE The purpose of the present study was to examine the impact of 8 days of immobilization during a Special Support and Reconnaissance mission (SSR) on muscle mass, contraction dynamics, maximum jump height/power, and body composition. METHODS Unilateral maximal voluntary contraction, rate of force development, and maximal jump height were tested to assess muscle strength/power along with whole-body impedance analysis before and after SSR. RESULTS Body weight, fat-free mass, and total body water decreased (4-5%) after SSR, along with impairments in maximal jump height (-8%) and knee extensor maximal voluntary contraction (-10%). Furthermore, rate of force development was severely affected (-15-30%). CONCLUSIONS Eight days of immobilization during a covert SSR mission by Special Forces soldiers led to substantial decrements in maximal muscle force and especially in rapid muscle force capacity. This may negatively influence the ability for rapid exfiltration and redeployment, respectively.

Changes in muscle strength and morphology after muscle unloading in Special Forces missions

The purpose of the present study was to determine the changes in maximal muscle strength, rapid force capacity, jumping performance and muscle morphology following a Special Forces military operation involving 8 days of muscle unloading. Nine male Special Forces soldiers were tested before (pre) and immediately after (post1) an 8‐day simulated special support and reconnaissance (SSR) mission and after 3 h of active recovery (post2). Maximal muscle strength (MVC) and rate of force development (RFD) were measured along with maximal counter movement jump height (JH). Muscle biopsies were obtained from the vastus lateralis at pre and post1. Acute reductions were found in MVC (11%), JH (10%) and RFD (17–22%) after 8 days of muscle unloading (post1) (P≤0.05). Type IIX fiber type area% increased (P≤0.05) at post1 together with a tendency toward increased type IIX fiber type % (P=0.09) and decreased type I fiber type % (P=0.06), suggesting a transition toward a less fatigue‐resistant fiber‐type profile. In conclusion, short‐term unloading during SSR missions led to marked reductions in mechanical muscle function and functional performance, which may be partly explained by the changes in muscle morphology. Future studies should identify intervention strategies to counter‐act the observed impairments.

Does sound structure affect word learning? An eye-tracking study of Danish learning toddlers

Previous research has shown that Danish-learning children lag behind in early lexical acquisition compared with children learning a number of other languages. This delay has been ascribed to the opaque phonetic structure of Danish, which appears to have fewer reliable segmentation cues than other closely related languages. In support of this hypothesis, recent work has shown that the phonetic properties of Danish negatively affect online language processing in young Danish children. In this study, we used eye-tracking to investigate whether the challenges associated with processing Danish also affect how Danish-learning children between 24 and 35 months of age establish and learn novel label-object mappings. The children were presented with a series of novel mappings, either ostensively (one novel object presented alone on the screen) or ambiguously (one novel object presented together with a familiar one), through carrier phrases with different phonetic structures (more vs less opaque). Our results showed two main trends. First, Danish-learning children performed poorly on the task of mapping novel labels onto novel objects. Second, when learning did occur, accuracy was affected by the phonetic opacity of the speech stimuli. We suggest that this finding results from the interplay of a perceptually challenging speech input and a slower onset of early vocabulary experience, which in turn may delay the onset of word learning skills in Danish-learning children.