bluuebunny/crossref_metadata_2025 huggingface dataset:
A CROSS-SECTIONAL STUDY OF THE BIOPSYCHOSOCIAL CHARACTERISTICS OF ELITE ADULT IRISH DANCERS AND THEIR ASSOCIATION WITH MUSCULOSKELETAL PAIN AND INJURY
Authors: Cahalan R , O'Sullivan K , Purtill H , O'Sullivan P
Published: March 2014

Background

Irish dancing (ID) is a technically demanding art form practised by growing numbers internationally. However, research into musculoskeletal pain and injury in elite adult Irish dancers is scant.

Objective

To establish the biopsychosocial characteristics of elite adult Irish dancers. To investigate any relationship between these characteristics and musculoskeletal pain and injury.

Design

104 elite adult Irish dancers completed a questionnaire providing data on dance and activity levels, physical and psychological health, pain and injury history. 84 of these subjects underwent a physical screen examining lower limb flexibility, balance and endurance, a number of functional tests, anthropometric and biomechanical/anatomical assessments.

Setting

Testing was completed at a number of sites in Ireland using standardised portable equipment.

Participants

The study cohort comprised professional Irish dancers (34.6%), elite competitive Irish dancers (26.9%), and dancers in full time education studying ID (38.5%). All participants were 18 years of age or older. Elite dancers from eleven different countries were tested.

Main outcome measurements

Subjects were dichotomised into “significantly injured (SI)” and “not significantly injured (NSI)” categories based on reported levels of pain and injury. Specific injury data from the previous five years were also recorded.

Results

33 (31.7%) subjects were classified as SI, with the remaining 71 (68.3%) subjects classified as NSI. Factors significantly associated being SI were female gender (P=.036), higher number of subjective general health (P=.001) and psychological (P=.036) complaints, low mood (P=.01), higher catastrophising (P=.047) and failure to always warm-up (P=.006). The mean number of injuries sustained to all body parts over the previous five years was 1.49 with a mean of 126.1 days lost to injury. Foot and ankle injuries were most prevalent.

Conclusions

A complex combination of biopsychosocial factors appears to be associated with a significant level of pain and injury in elite adult Irish dancers.
DOES A MODIFIED RUGBY SCRUM ENGAGEMENT PROCESS IMPROVE THE STABILITY OF THE SCRUM AND MINIMISE THE LIKELIHOOD OF SCRUM COLLAPSE?
Authors: Cazzola D , Preatoni E , Stokes KA , England M , Trewartha G
Published: March 2014

Background

Rugby Union scrums which collapse possess a higher injury risk than completed scrums. A mechanically stable scrum should limit the motions which generate uncontrolled and hazardous (non-axial) loading on front row players and minimise the risk of scrum collapse.

Objective

To compare scrum stability during live contested rugby scrums using two different scrum engagement processes.

Design

A cross-sectional design, where teams from different playing levels performed live scrums under two engagement processes: CTS (Crouch-Touch-Set, 2012–2013); and PreBind (Crouch-Bind-Set, 2013–2014), with measurements made via video analysis.

Setting

Outdoors, natural turf rugby pitches.

Participants

27 Rugby teams (i.e. 54 forward packs, n=432 players) from five playing levels – International, Elite, Community, Women and University.

Risk factor assessment

Scrum engagement process. PreBind differs from CTS for a legal bind that is taken at the “Bind” call and is maintained through the “Set” action.

Main outcome measurements

Vertical motion of the (i) shoulder and (ii) centre of mass (COM), and (iii) COM variability in the sagittal plane of prop forwards during initial engagement.

Results

The extent of props' vertical shoulder motion were reduced (P<.05, Cohen's d=0.3–0.5) during engagement in the PreBind process compared with the CTS process. The COM vertical motion tended to be reduced in PreBind process (Cohen's d=0.45).There were also reductions in the variability (P<.05, Cohen's d=0.5–1.0) of the props' COM vertical motion, meaning vertical movements were more controlled during PreBind engagement. The International level had reduced vertical motion characteristics with respect to the Community level.

Conclusions

Scrum stability improved (moderate effects) in the PreBind engagement process, with props making less extreme postural adjustments during initial engagement. Combined with attenuated peak forces during the engagement process, the PreBind improves the stability of the scrum and should minimise the risk of scrum collapse and subsequent injury.
CHANGING HAND POSITIONS ALTERS LOWER EXTREMITY BIOMECHANICS DURING LANDING
Authors: Ambegaonkar J , Oladipo E , Caswell SV , Shimokochi Y , Cortes N
Published: March 2014

Background

During gameplay, athletes frequently change their trunk and hand placement positions (e.g. ball handling). Changing trunk positions alters lower extremity (LE) biomechanics and subsequent injury risk during sport. However, whether changing hand positions also alters LE biomechanics during landing (a high LE injury-risk activity) is unclear.

Objective

To examine if changing hand positions during landing affects LE biomechanics.

Design

Repeated measures.

Setting

Laboratory.

Participants

30 healthy participants (23.4±4.3 years, 170.7±7.7 cm, 70.2±18.9 kg).

Interventions

Participants performed 5 landings from a 45cm box in 4 different hand placement (HP) conditions: 1) Holding a basketball at chest level (CH), 2) Holding a basketball at chest with arms straight in front (FR), 3) Holding a basketball straight up over head (UP), and 4) Placing hands on hips (HIP).

Main outcome measurements

Sagittal hip, knee, ankle angles (°) from initial touchdown to lowest point of the vertical Center of Mass (COM min) displacement were assessed using 3-D motion analyses. Repeated measures ANOVAs and Bonferroni pairwise comparisons examined differences across HP conditions.

Results

At touchdown, participants had differing hip (P<.001), but not knee (P=.09), or ankle (P=.22) flexion angles across conditions. At COMmin, participants had differing hip (P=.01), knee (P=<.001), and ankle (P<.001)angles across conditions, resulting in differing hip (P=.01)and knee (P<.001) but similar ankle (P=.06) flexion excursions across conditions. Specifically, participants had lower hip excursions in UP than in FR (P=.03) and HIP (P=.009), and lower knee excursions in CH than in FR (P=.02), UP (P=.003), and UP (P<.001).

Conclusions

Overall, when landing with hands up or across the chest, participants landed in an extended posture and with decreased range of motion. Conversely, when landing with hands in front, participants had increased joint flexion angles associated with an increased range of motion. Changing hand placements during landing may alter LE biomechanics, and influence subsequent injury risk during landing. Clinicians should incorporate exercises that include hand position changes when designing injury prevention programs to decrease LE injury risk.
LOWER EXTREMITY MUSCLE ONSET TIMES DURING THE TRANSITION FROM DOUBLE-LEG STANCE TO SINGLE-LEG STANCE IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTED SUBJECTS
Authors: Dingenen B , Janssens L , Claes S , Bellemans J , Staes F
Published: March 2014

Background

Deficits in neuromuscular control are believed to increase re-injury risk after anterior cruciate ligament reconstruction (ACLR). Previous studies mainly focused on muscles at the operated knee, less on muscles around other joints of the operated and non-operated leg.

Objective

To evaluate lower extremity muscle onset times during the transition from double-leg stance to single-leg stance in ACLR and non-injured control subjects.

Design

Cross-sectional (retrospective).

Setting

Controlled laboratory study.

Participants

20 ACLR subjects (15 females, 5 males), 23.1±13.9 months after ACLR and fully returned to their pre-injury sport, and 20 non-injured control subjects (15 females, 5 males) participated in the study. Both groups were matched for age, gender, weight, height and activity level. All ACL injuries were caused by a non-contact injury mechanism.

Risk factor assessment

A transition task from double-leg stance to single-leg stance with eyes closed was performed, using a single force plate and surface electromyography. Movement speed was standardized. Both legs of each subject were tested.

Main outcome measurements

Onset times of 10 lower extremity muscles were compared between groups and between legs within the same group. Significance was set at P<.05.

Results

TheACLR group showed significant delayed muscle onset times for gastrocnemius (P=0.40), peroneus longus (P=.022), vastus medialis (P=.007), gluteus medius (P=.035) and gluteus maximus (P=.001). No significant different muscle onset times were found between legs in the ACLR group (P>.05).

Conclusions

Despite the full return to sport, ACLR subjects showed delayed muscle onset times during the transitional movement, not only around the knee, but also around the hip and ankle of both legs. Whether these deficits are a result or a pre-existing risk factor of the initial ACL injury remains unclear. Secondary prevention strategies should focus on the whole lower kinetic chain of both legs to improve neuromuscular control after ACLR.
ARE TWO-DIMENSIONAL MEASURED SAGITTAL PLANE KINEMATICS RELATED TO THREE-DIMENSIONAL JOINT LOADING DURING THE DROP VERTICAL JUMP TEST?
Authors: Dingenen B , Malfait B , Vanrenterghem J , Robinson M , Verschueren S , Staes F
Published: March 2014

Background

Acute and overuse knee injuries are common in sports involving jump-landing movements, especially in female athletes. More erect sagittal plane movement patterns are believed to increase injury risk. Whilst three-dimensional (3D) measurements are considered to be the gold standard, they are complex and two-dimensional (2D) video analysis may be a valuable alternative to screen athletes in clinical practice.

Objective

The purpose of the present study was to investigate the relationship between 2D sagittal plane kinematics and 3D joint loading during the drop vertical jump (DVJ) test.

Design

Cross-sectional.

Setting

Controlled laboratory study.

Participants

Fifty injury-free elite female athletes were tested.

Risk factor assessment

Two-dimensional sagittal plane video analysis and 3D motion analysis were used during the DVJ test.

Main outcome measurements

Hip flexion, knee flexion and ankle dorsiflexion angles were measured at the deepest landing position (2D analysis). External hip flexion moments (HFM), knee flexion moments (KFM) and knee abduction moments (KAM) were measured across the entire support phase (3D analysis). One-dimensional statistical parametric mapping was used to examine the temporal relationship between 2D angles at the deepest landing position and 3D moments across the entire support phase. Significance was set at P<.0055.

Results

The amount of hip flexion was significantly related to HFM, KFM and KAM during the time frames corresponding with highest 3D moments, while the amount of knee flexion was only significantly related to HFM during these time frames. No significant results were found for ankle dorsiflexion.

Conclusions

These results indicate that 2D measured sagittal plane hip and knee flexion angles at the deepest landing position are associated with sagittal plane peak joint loading during a DVJ. Furthermore, the significant association of hip flexion with frontal plane knee loading provides evidence that assessment of knee joint injury risk could benefit from measuring maximal hip flexion.
BALANCE FAILURE IN SINGLE LIMB STANCE DUE TO ANKLE SPRAIN INJURY: AN ANALYSIS OF CENTRE OF PRESSURE USING THE FRACTAL DIMENSION METHOD
Authors: Doherty C , Delahunt E , Bleakley C , Hertel J , Ryan J , Caulfield B
Published: March 2014

Background

Dynamic stability is ubiquitous to fulfilling daily living activities. Instrumented postural control analysis plays an important role in evaluating the effects of injury on dynamic stability during balance tasks, and is often characterized with measures based on the displacement of the centre of pressure (COP) assessed with a force platform. However, the desired outcome of the task is frequently characterized by a loss of dynamic stability, secondary to injury. Typically, failed trials of balance tasks are discarded during research investigations.

Objective

To compare the COP characteristics of failed trials in participants with acute lateral ankle sprain (LAS) to successful trial data in another group with the same injury, and a non-injured control group during a single limb stance (SLS) task.

Design

Cross-sectional.

Setting

University biomechanics laboratory.

Participants

29 participants with acute LAS attempted and succeeded a task of eyes closed SLS on their non-injured limb (successful injured group). A separate group of 28 participants with acute LAS attempted and failed the task on their injured limb (failed injured group). Finally a non-injured control group of 16 participants successfully completed the task on their non-dominant limb (successful non-injured group).

Main outcome measure

Fractal dimension (FD) of the COP path during the SLS task.

Results

There was a statistically significant difference at the level of P<.05 in FD scores for the three groups: F (2, 70)=11.61, P<.05 (successful injured group=1.26±0.15=failed injured group: 1.17±0.14;successful non-injured group=1.38±0.11) with a large effect size.

Conclusion

Successful eyes-closed SLS is characterized by a larger FD of the COP path trajectory when compared to failed trials, indicating greater utilisation of the available base of support.
PRE-PARTICIPATION HEALTH QUESTIONNAIRE IN MAJOR ATHLETIC CHAMPIONSHIPS: FEASIBILITY AND INTEREST TO DETERMINE INJURY AND ILLNESS RISK FACTORS
Authors: Edouard P , Branco P , Jacobsson J , Timpka T , Kowalski J , Nilsson S , Karlsson D , Depiesse F , Alonso JM
Published: March 2014

Background

The current injury and illness (I&I) surveillance system in association to athletics championships have to be improved by collecting pre-participation data for risk factors analyses.

Objectives

To evaluate a pre-participation health questionnaire (PHQ) for collecting health status data from athletes for risk factors analyses and to describe incidence and characteristics of I&I occurred during a major indoor Athletics championships.

Design

Cohort study using retrospective athlete self-report data on health status for the 4 weeks prior to the championship and prospective recording of in-championship injuries and illnesses.

Setting

32stEuropean Athletics Indoor Championships 2013 in Göteborg, Sweden.

Participants

A sub-cohort of athletes (n=127) for PHQ study and 577 registered athletes for I&I study.

Risk factor assessment

Age, gender, pre-competition pain, pre-competition injury, pre-competition illness, pre-competition training load and fatigue.

Main outcome measures

Newly incurred injury and illness at the championships.

Results

In the I&I study, 60 injuries (104.6/1000 registered athletes) were recorded. The most common injury cause was “field play conditions” (31%), followed by overuse (29%). 29 illnesses were reported (12.6 illnesses per 1000 athlete days), with upper respiratory tract infection and gastro-enteritis/diarrhoea as the most common diagnoses. 74 athletes submitted a complete PHQ (58.3%). An univariate statistical analysis showed that athletes having trained more than 12 hours per week were at increased risk for suffering a new injury (Relative risk (RR)=4.9 (95% Confidence interval (95% CI):1.2–20.7)), and athletes who presented a pre-participation health problem were more likely to suffer a new illness (RR=2.7; (95% CI:1.1–6.7)).

Conclusions

An athlete self-report PHQ was feasible and allowed for pre-participation screening of individuals at risk. Injury risk during indoor championships seems slightly lower than during outdoor championships with specific injury types that can be attributed to the indoor track conditions.
EVALUATION OF A BODY CHECKING POLICY CHANGE AS AN INJURY PREVENTION STRATEGY FOR NON-ELITE YOUTH ICE HOCKEY PLAYERS
Authors: Emery CA , Black A , Macpherson A , Kang J , Hagel B , Romiti M , Meeuwisse W
Published: March 2014

Background

In Pee Wee (ages 11–12) ice hockey, body checking is associated with an increased risk of injury and concussion. In 2011, research informed some provincial policy change, disallowing body checking in non-elite Pee Wee leagues.

Objective

To determine if the risk of injury and concussion differ for non-elite Pee Wee ice hockey players in leagues where body checking is permitted (Alberta, Canada) compared to leagues where prospective policy change disallows body checking (Ontario, Canada).

Design

Cohort study.

Setting

Ice hockey rinks (2011/12 season).

Participants

Non-elite (lower 70%) Pee Wee ice hockey players from Alberta (n=590) and Ontario (n=281).

Risk factor assessment

Exposure to a Pee Wee league where policy permits body checking. Other risk factors included previous concussion/injury, year of play, level of play, position and attitudes toward body checking.

Main outcome Measurement

Suspected concussions were identified by a team designate and referred to a sport medicine physician. Hockey injuries included those requiring medical attention or time loss.

Results

There were 101 game injuries (incidence rate [IR]=4.19/1000 game hours [95% CI; 3.38–5.18]), and 67 game concussions ([IR]=2.78/1000 game hours [95% CI; 2.19–3.52]) in Alberta and 14 game injuries (IR=1.60/1000 game hours [95% CI; 0.87–2.94]) and 8 concussions (IR=0.91/1000 game hours [95% CI; 0.41–2.06]) in Ontario. Based on multivariate poisson regression (adjusted for cluster, exposure hours and other risk factors), incidence rate ratio associated with policy allowing body checking was 2.97 (95% CI; 1.33–6.61) for game injury and 2.83 (95% CI; 1.09–7.31) for concussion.

Conclusions

The risk of injury and concussion was 3-fold greater in non-elite Pee Wee hockey players in leagues where body checking is permitted. This is similar to previous findings examining retrospective policy change. Policy change disallowing body checking is effective in preventing injury and concussion in non-elite youth ice hockey.
SHOULDER INJURIES IN HIGHLY TRAINED COMPETITIVE SWIMMERS
Authors: Folland J , Archer G
Published: March 2014

Background

The shoulder is the most commonly injured joint among competitive swimmers, and there are suggestions that sex, swimming stroke and level or training/competition are risk factors, but previous studies are inconclusive and have used small cohorts and/or relatively low level competitors.

Objectiv

To document the incidence, nature, severity and location of shoulder injuries in competitive highly trained swimmers, and whether these factors were influenced by sex, swimming stroke and level of competition.

Design

Retrospective study.

Setting

Swimming competitions and clubs.

Participants

132 young competitive adult swimmers (61 females, 71 males; age, 21±2 yrs; body mass: 73±11kg; current training volume, 16±4 hrs/wk; competitive history 9±3 years).

Risk factor assessment

Participants completed a retrospective questionnaire concerning their age, sex, competitive standard, primary stroke, recent training volume.

Main outcome measurements

They also recorded their experience of shoulder injury incidence (new injury, recurrence), time loss severity (mild, moderate, severe), nature of injury onset (acute/chronic) and location (left, right, both).

Results

99 swimmers (74%) had experienced shoulder injury, collectively reporting 124 unique injuries, and >50% of these injuries had recurred at least once. 22% of swimmers were currently experiencing shoulder pain, and 10% were currently receiving treatment for shoulder injury. Injury incidence was not influenced by sex (P=.223) or competitive standard (P=.415). There were more chronic than acute injuries (86 vs 38; P=.001). There were tendencies for more injuries to the right than left shoulder (65 vs 43, P=.066), and for a higher incidence of severe injuries than expected (P=.053). Shoulder injury was 50% lower for breaststroke swimmers, but this difference was not significant P=.245).

Conclusions

Injury incidence was not influenced by sex or level of competition, but was 50% lower for breaststroke swimmers. Despite the symmetrical nature of swimming the right shoulder seems to be at greater risk of injury.
Cytogenetics of the Holarctic black fly Simulium noelleri (Diptera: Simuliidae)
Authors: Adler Peter H , Kachvorian Eugenie A
Published: March 2014

The polytene chromosomes of Simulium noelleri from 16 sites in Armenia, Canada, England, Germany, Russia, and Sweden were analyzed. A standard map is proposed for the S. noelleri species-group that is 11 fixed inversions removed from the original standard map of the subgenus Simulium. Based on one shared subterminal inversion in the IIIL arm, the S. noelleri species-group is in a trichotomy with the S. bezzi and S. ornatum species-groups. Reproductive isolation of S. noelleri and S. decorum is demonstrated chromosomally at sites where both occur together. All analyzed populations of S. noelleri are considered conservatively to represent a single species, although at least three cytotypes are recognized, based primarily on different sex-chromosome systems. Cytotype A, representing the type species of S. noelleri, occurs in Germany, England, and western Russia. Cytotype B occupies Sweden and western Canada, emphasizing the intimate connection between the northern Nearctic and Palearctic simuliid faunas. Cytotype C is known only from Armenia.
Parasitism, movement, and distribution of the snail Diloma subrostrata (Trochidae) in a soft-sediment intertidal zone
Authors: Miller Aroha A , Poulin Robert
Published: March 2014

Despite reports of their effects on host reproduction, growth, survival, and habitat use, the role of parasites in determining community structure is still poorly understood. Trematode infections in snails are a ubiquitous feature of intertidal systems worldwide. In this study, the influence of a trematode parasite on the movement and dispersal of the trochid snail Diloma subrostrata on a soft-sediment shore is examined using markrecapture experiments. The natural densities and shell widths of the snail peak between the upper and lower portions of the intertidal zone; marked snails were released within this area. Parasitized snails tended to have larger shells than nonparasitized conspecifics, and larger snails tended to move a greater linear distance than smaller snails in the 24 h following their marking and release. After shell width was corrected for, parasitized snails were found to move a significantly shorter distance than nonparasitized snails. In addition, the mean direction chosen by parasitized snails was almost parallel to the water's edge, whereas that taken by nonparasitized snails was almost directly toward the upper portion of the intertidal zone. Although the mean directions taken by the two types of snails were statistically different, the considerable scatter in the distributions of directions taken by individual snails casts a doubt over the biological significance of the result. Without detailed knowledge of the parasite's full life cycle it is difficult to determine whether this small bias in the direction of dispersal is an adaptive manipulation of snail behaviour by the parasitic trematode. Nevertheless, these results show that the trematode limits the range of movement, and possibly the direction of movement, of parasitized D. subrostrata, and can therefore contribute to the spatial structuring of the snail population.
Killing technique of North American badgers preying on Richardson's ground squirrels
Authors: Michener Gail R , Iwaniuk Andrew N
Published: March 2014

Carcasses of 13 Richardson's ground squirrels (Spermophilus richardsonii) cached during autumn by North American badgers (Taxidea taxus) in southern Alberta, Canada, were inspected to determine the capture and killing technique. Regardless of prey size (251651 g) or torpor status (normothermic or torpid), badgers killed ground squirrels with a single grasping bite directed dorsally or laterally to the thorax. The canines and third upper incisors of badgers generally bruised the skin without puncturing it, but caused extensive hematomas on the thoracic musculature and penetrated between the ribs, with associated breakage of ribs and hemorrhaging in the thoracic cavity. Internal organs and bones other than ribs were usually not damaged. Thoracic bites, rather than nape or throat bites, are used by several mustelids, including North American badgers, when capturing small prey (<10% of the predator's mass).
Reproduction and postnatal growth of the Cabrera vole, Microtus cabrerae, in captivity
Authors: Fernández-Salvador Rosa , García-Perea Rosa , Ventura Jacint
Published: March 2014

Three pairs of the endangered Cabrera vole, Microtus cabrerae, which is endemic to the Iberian Peninsula, were captured in the wild and reared in captivity. They did not breed under standard laboratory conditions, and bred only under conditions similar to those found in wild colonies. Six litters were obtained and a total of 24 pups were monitored. Five external variables were measured and timing of 11 developmental events was recorded for each pup until it was 80 days old. Litter size was 4.0 ± 0.89 (mean ± SE; range = 35) pups per female, falling within the range reported for other Microtus species. Litter size of M. cabrerae was lower in the laboratory than in the field. Female body mass was correlated with litter mass at birth. Newborns were heavy (3.5 g, on average) compared with those of other Microtus species because of the relatively large size of adult M. cabrerae. Timing of the main developmental events followed a similar pattern to that observed for other species of the genus. Juvenile M. cabrerae grew fast in length during lactation, rapidly increasing their body mass during postweaning. Observations on parental behaviour in rearing pups support the previously published hypothesis that the species is monogamous. A global assessment of our results suggests that M. cabrerae should be included among the species that use the K strategy of reproduction.
Reproductive changes in a cyclic population of snowshoe hares
Authors: Stefan Carol I , Krebs Charles J
Published: March 2014

Reproductive output was estimated for a cyclic population of snowshoe hares (Lepus americanus) in the Kluane Lake region of the southwest Yukon Territory. Data collected by five researchers were collated over 8 years (19891996). Pregnant hares were captured and held in cages until they gave birth so that reproductive characteristics could be measured. Pregnancy rate, litter size, and neonate size fluctuated significantly throughout the cycle, changes occurring about 2 years before corresponding changes in density. Pregnancy rates were nearly 100% early in the breeding season, but declined up to 20% in the last gestation periods of the year. The number of litters produced in a breeding season varied between two (decline phase) and four (low, early increase phase). Litter size varied among years as well as among litters within a year, larger litters being born later in the breeding season. The body mass and size of newborn hares varied by 533% among years. The combined changes in pregnancy rate and litter size resulted in a cyclic change in total reproductive output ranging from a low of 6.9 young per female during the decline phase to a maximum of 18.9 during the second year of the low and early increase phases.
Site fidelity and the costs of movement among territories: an example from colonial web-building spiders
Authors: Jakob Elizabeth M , Porter Adam H , Uetz George W
Published: March 2014

Species differ in whether they exhibit strong site fidelity or move readily among sites. To understand the adaptive significance of site fidelity it is necessary to measure the cost of relocating to new sites, but this is very difficult with most species because it entails following individuals during the entire course of their transition. We studied the colonial web-building spider Metepeira incrassata (Araneae: Araneidae), which defends individual orb webs within a large, shared frame web. Colonies are heterogeneous habitats, with more prey but also more predators at the periphery of the colony relative to the central core. We measured relocation costs in this species by breaking them into the following components, (i) searching costs, (ii) establishment costs, and (iii) lost-opportunities costs, or the potential benefits of alternative behaviors that an animal might engage in if it were not relocating. We observed spiders that were in the process of establishing their orb webs at the start of the foraging day and conducted experiments to examine the costs of relocation by transferring spiders between locations within the colony. Transferred spiders had more fights with conspecifics than non-transferred spiders did, and the number of fights was positively correlated with the distance moved. However, searching and establishment costs seem unimportant, as individuals moving within their territories were as active as individuals moving to new sites. Transferred spiders faced greater lost-opportunities costs in the form of time spent on prey-capture orbs, as they significantly delayed orb construction. Lost-opportunities costs seem to be the most important component of relocation costs in this species and are likely to be generally important among species. This study is one of the few to document movement costs through direct observation.
Directed harmonic currents for laminations on certain compact complex surfaces
Authors: Pérez-Garrandés Carlos
Published: March 2014

Let ℒ be a Lipschitz lamination by Riemann surfaces embedded in M. If M is a complex torus, ℂℙ1 × ℂℙ1 or 𝕋1 × ℂℙ1 and there is no directed closed current then there exists a unique directed harmonic current of mass one. Moreover, if ℒ is embedded in M = ℂℙ1 × ℂℙ1 and has no compact leaves, then there is no directed closed current. If ℒ is not Lipschitz, then slightly weaker results are obtained.
Generalized Killing spinors on Einstein manifolds
Authors: Moroianu Andrei , Semmelmann Uwe
Published: March 2014

We study generalized Killing spinors on compact Einstein manifolds with positive scalar curvature. This problem is related to the existence of compact Einstein hypersurfaces in manifolds with parallel spinors, or equivalently, in Riemannian products of flat spaces, Calabi–Yau, hyperkähler, G2 and Spin(7) manifolds.
Index conditions and cup-product maps on Abelian varieties
Authors: Grieve Nathan
Published: March 2014

We study questions surrounding cup-product maps which arise from pairs of non-degenerate line bundles on an abelian variety. Important to our work is Mumford's index theorem which we use to prove that non-degenerate line bundles exhibit positivity analogous to that of ample line bundles. As an application we determine the asymptotic behavior of families of cup-product maps and prove that vector bundles associated to these families are asymptotically globally generated. To illustrate our results we provide several examples. For instance, we construct families of cup-product problems which result in a zero map on a one-dimensional locus. We also prove that the hypothesis of our results can be satisfied, in all possible instances, by a particular class of simple abelian varieties. Finally, we discuss the extent to which Mumford's theta groups are applicable in our more general setting.
Lattice Boltzmann kinetic modeling and simulation of thermal liquid–vapor system
Authors: Gan Yanbiao , Xu Aiguo , Zhang Guangcai , Wang Junqi , Yu Xijun , Yang Yang
Published: March 2014

We present a highly efficient lattice Boltzmann (LB) kinetic model for thermal liquid–vapor system. Three key components are as below: (i) a discrete velocity model (DVM) by Kataoka et al. [Phys. Rev. E69, 035701(R) (2004)]; (ii) a forcing term Iiaiming to describe the interfacial stress and recover the van der Waals (VDW) equation of state (EOS) by Gonnella et al. [Phys. Rev. E76, 036703 (2007)] and (iii) a Windowed Fast Fourier Transform (WFFT) scheme and its inverse by our group [Phys. Rev. E84, 046715 (2011)] for solving the spatial derivatives, together with a second-order Runge–Kutta (RK) finite difference scheme for solving the temporal derivative in the LB equation. The model is verified and validated by well-known benchmark tests. The results recovered from the present model are well consistent with previous ones [Phys. Rev. E84, 046715 (2011)] or theoretical analysis. The usage of less discrete velocities, high-order RK algorithm and WFFT scheme with 16th-order in precision makes the model more efficient by about 10 times and more accurate than the original one.
Dynamics of opinion formation with strengthen selection probability
Authors: Zhang Haifeng , Jin Zhen , Wang Binghong
Published: March 2014

The local majority rule is extensively accepted as a paradigmatic model to reflect the formation of opinion. In this paper, we study a model of opinion formation where opinion update rule is not based on the majority rule or linear selection probability but on a strengthen selection probability controlled by an adjustable parameter β. In particular, our proposed probability function can proximately fit the two extreme cases–linear probability function and majority rule or in between the two cases under different values of β. By studying such model on different kinds of networks, including different regular networks and complex networks, we find that there exists an optimal value of β giving the most efficient convergence to consensus regardless of the topology of networks. This work reveals that, compared with the majority rule and linear selection probability, the strengthen selection probability might be a more proper model in understanding the formation of opinions in society.
1.55-μm wavelength ultrafast fiber oscillators and amplifiers
Authors: Wang Hongjie , Gaponov Dmitry , Cabasse Amélie , Martel Gilles , Hideur Ammar , Oudar Jean-Louis , Kotov Leonid , Likhachev Mikhail , Lipatov Denis , Février Sébastien
Published: March 2014

In this paper, we review our recent developments on ultrafast pulse generation in erbium-doped fiber laser systems operating in the 1550 nm wavelength range. This work concerns the generation of ultrafast pulses from dissipative soliton fiber lasers featuring resonant saturable absorber mirrors, as well as their amplification in highly efficient erbium-doped large-mode-area fibers. Different amplification schemes featuring all-fiber components are studied leading to the achievement of record pulse energy from a high repetition rate laser system.
Nonlinear pulse shaping and polarization dynamics in mode-locked fiber lasers
Authors: Boscolo Sonia , Sergeyev Sergey V. , Mou Chengbo , Tsatourian Veronika , Turitsyn Sergei , Finot Christophe , Mikhailov Vitaly , Rabin Bryan , Westbrook Paul S.
Published: March 2014

We review our recent progress on the study of new nonlinear mechanisms of pulse shaping in passively mode-locked fiber lasers. These include a mode-locking regime featuring pulses with a triangular distribution of the intensity, and spectral compression arising from nonlinear pulse propagation. We also report on our recent experimental studies unveiling new types of vector solitons with processing states of polarization for multi-pulse and tightly bound-state soliton (soliton molecule) operations in a carbon nanotube (CNT) mode-locked fiber laser with anomalous dispersion cavity.
Single-walled carbon nanotubes as high pressure nanocontainer
Authors: Chen Na , Xu Qing , Ye Xiang
Published: March 2014

The single-walled carbon nanotubes (SWCNTs) under high internal pressure are studied by the constant-pressure molecular dynamics method. The results show that SWCNTs are suitable candidates for high pressure nanocontainer, and they can resist 30 GPa to 110 GPa internal pressure. We find that the ultimate internal pressure that nanotubes can sustain is mainly determined by the radius of the tube, and it is not sensitive to the tube chirality. The breaking of the nanotube induced by high internal pressure is mainly due to bond stretching rather than bond angle changing. An elastic model is used to explain the size-dependent ultimate internal pressure behavior for SWCNTs.
Realizing various approximate quantum cloning with XY-type exchange interactions of flux qubits
Authors: Li Na , Ye Liu
Published: March 2014

In this paper, we realize all kinds of 1 → 2 approximate quantum cloning, including optimal 1 → 2 symmetric (or asymmetric) universal quantum cloning (UQC) and phase-covariant cloning (PCC), symmetric economical phase-covariant cloning (EPCC) and real state quantum cloning, with the XY-type exchange interactions of the flux qubits which are coupled by dc superconducting quantum interference devices (SQUIDs). It is shown that our schemes can be realized with the current experimental technology.
On the scientific work of Kunyang Wang
Authors: Dai Feng
Published: March 2014

This paper surveys some of the scientific work on positive polynomial sums, Fourier analysis and spherical approximation on the sphere that Kunyang Wang did in the past 20 years.
On the widths of Sobolev's classes
Authors: Huang Hongwei , Wang Kunyang
Published: March 2014

Optimal estimates of Kolmogorov's n-widths, linear n-widths and Gelfand's n-widths of the weighted Sobolev classes on the unit sphere 𝕊d are established. Similar results are also established on the unit ball Bd and on the simplex Td.
The Physics of Vision
Authors: Miller David R.
Published: March 2014

The perception of an image in one's mind filled with vibrant colors comes so naturally for humans that the complexity of the human visual system is often overlooked. This paper follows the journey of light through the human eye and its interpretation in the brain. The wave properties of light are explored as light propagates through the eye while the particle properties of light are examined when light is absorbed by the retina. The computations involved in the perception of color are discussed as well as birefringent properties of the eye.
Effects of first-order chemical reactions on the dispersion coefficient associated with laminar flow through the lungs
Authors: Saini Anju , Katiyar V. K. , Pratibha
Published: March 2014

This paper aims to look into the determination of effective area-average concentration and dispersion coefficient associated with unsteady flow through a small-diameter tube where a solute undergoes first-order chemical reaction both within the fluid and at the boundary. The reaction consists of a reversible component due to phase exchange between the flowing fluid and the wall layer, and an irreversible component due to absorption into the wall. To understand the dispersion, the governing equations along with the reactive boundary conditions are solved numerically using the Finite Difference Method. The resultant equation shows how the dispersion coefficient is influenced by the first-order chemical reaction. The effects of various dimensionless parameters e.g. Da (the Damkohler number), α (phase partitioning number) and Γ (dimensionless absorption number) on dispersion are discussed. One of the results exposes that the dispersion coefficient may approach its steady-state limit in a short time at a high value of Damkohler number (say Da ≥ 10) and a small but nonzero value of absorption rate (say Γ ≤ 0.5).
Universality of local eigenvalue statistics in random matrices with external source
Authors: O'Rourke Sean , Vu Van
Published: March 2014

Consider a random matrix of the form [Formula: see text], where Mn is a Wigner matrix and Dn is a real deterministic diagonal matrix (Dn is commonly referred to as an external source in the mathematical physics literature). We study the universality of the local eigenvalue statistics of Wn for a general class of Wigner matrices Mn and diagonal matrices Dn. Unlike the setting of many recent results concerning universality, the global semicircle law fails for this model. However, we can still obtain the universal sine kernel formula for the correlation functions. This demonstrates the remarkable phenomenon that local laws are more resilient than global ones. The universality of the correlation functions follows from a four moment theorem, which we prove using a variant of the approach used earlier by Tao and Vu.
Enhancing situational awareness of indoor orientation for the visually impaired
Authors: Alkhanifer Abdulrhman A.
Published: March 2014

This research is to design a user interface dedicated for visually impaired users to assist them when orienting themselves to unfamiliar indoor environments. Current orientation and navigation systems research focuses on providing feasible solutions to assist users, however less focus is given to the user interface level and how it enhances user's understanding of the surrounding environment. Our proposal is to apply the Situation Awareness Oriented design approach to enhance the user interface of the current indoor navigation systems for the visually impaired.
Exergames for children with motor skills problems
Authors: Caro Karina
Published: March 2014

Physical therapy helps children with Developmental Coordination Disorder (DCD) generalize motor functions executing different physical exercises through practice, repetition, and guidance. Children find task-repetition boring and guidance could not be provided outside the therapy-room in real life situations. Exergames are good in supporting motor therapeutic interventions as children find them engaging, but little has been said if the practicing of motor skills through exergaming enables skills generalization. The goal of this project is to investigate the impact of using exergames to help children with motor skills problems improve motor coordination and achieve motor skills generalization in real life situations. To date I have completed a contextual study to uncover the type of exercises children with DCD conduct during physical therapy, and inform the design of Froggy Bobby --an exergame supporting the motor skills generalization of children with DCD.
Automatic assessment of problem behaviour in developmental disabilities
Authors: Kirkham Reuben
Published: March 2014

Many with developmental disabilities, especially severe Autism, exhibit what is clinically known as 'problem behaviour', which includes persistent episodes of self-injury, aggression and disruption. Current treatments rely upon manually counting the individual episodes over a period of several weeks, which presents challenges in respect of accuracy, feasibility, and scalability. Situated in the domain of Human Activity Recognition, the goal of this PhD Project is to develop a system that automatically recognizes different types and degrees of problem behaviour on the basis of accelerometer sensor data. The proposed approach is detailed and justified, including how the field of Human Activity Recognition itself can be advanced, together with a clear plan of how the project is to be conducted.
Getting Smart About Content
Authors: Quinn Clark
Published: March 2014

eLearning is behind the industry when it comes to dealing with content systematically. The Intelligent Content Conference presents a chance to understand what leading organizations are recommending and doing with content. The practices observed include design, engineering, and management of content in ways enlightened by new standards and tools that provide a multi-layer approach to customizing the user experience.
Progress Towards Commercialization of Electrochemical Membrane Technology for CO2 Capture and Power Generation
Authors: Ghezel-Ayagh Hossein , Jolly Stephen , DiNitto Mathew , Hunt Jennifer , Patel Dilip , Steen William A , Richardson Carl F , Marina Olga A , Pederson Larry
Published: March 2014

To address the concerns about climate change resulting from emission of CO2 by coal-fueled power plants, FuelCell Energy, Inc. has developed Combined Electric Power and Carbon-dioxide Separation (CEPACS) system concept, as a novel solution for greenhouse gas emission reduction. The CEPACS system utilizes Electrochemical Membrane (ECM) technology derived from the Company’s well established Direct FuelCell® products. The system concept works as two devices in one: it separates the CO2 from the exhaust of other plants and simultaneously, using a supplementary fuel, produces electric power at high efficiency. FCE is currently evaluating the use of ECM to cost effectively separate CO2 from the flue gas of coal fired power plants under a U.S. Department of Energy contract. The overarching objective of the project is to verify that the ECM can achieve at least 90% CO2 capture from flue gas of a PC plant with no more than 35% increase in the cost of electricity. The specific objectives and related activities presently ongoing for the project include: 1) conduct bench scale tests of ECM and 2) evaluate the effects of impurities present in the coal plant flue gas by laboratory scale performance tests of the membrane.
Fuel Cells and Flow Batteries: A Comparative Process and Design Analysis
Authors: Winkler Wolfgang , Williams Mark C.
Published: March 2014

The energy industry needs an increase of efficiency of energy conversion and inexpensive energy storage. Electrochemical flow processes, such as fuel cells, flow batteries and electrolysers, could become key technologies in our energy future. The increasing amount of fluctuating renewable electric power generation needs the installation of electric storage. Hydrogen economy might be one solution involving fuel cells and electrolyzer, but classic secondary batteries as batch processes have size and cost limitations. The development of flow batteries changed the process of classic design of electrochemical batch process for storing electricity to a flow process like a fuel cell. For further development and a future research strategy it is important to understand their similarities and synergies to fuel cells and electrolyzer. A process and design analysis allows identifying similarities and differences between fuel cells and flow batteries. Electrolyzer also can be discussed. A thermodynamic consideration shows that the reaction coordinate (fuel utilization or state of charge (SoC)) of fuel cells and flow batteries is a function of space. SoC of secondary batteries is a function of time because they are batch processes. Flow processes generally allow high energy storage by its reaction products that can be stored independently from their stack design. A comparison of the major design criteria, as kind of process, BoP needs, ionic transport in membranes, substance transport, operation conditions, transformation of electrodes, reaction progress, comparison open system and closed system etc. shows a number of similarities between fuel cells and flow batteries. Only the energy storage by ionic substances in flow batteries differs clearly from energy storage by reaction enthalpy of electrical neutral substances in fuel cells. The storage of sufficient electric work in a certain volume or mass still remains a problem. This may be the use of high pressure with the necessary pressure vessels or heavy metallic hydrates for storing hydrogen or the use of strongly diluting supporting electrolytes for flow batteries. For that reason it is important to identify the quality of energy storage in an early state of design. A new method allows a very early and simple evaluation of the future technical feasibility of electrochemical processes as fuel cells or flow batteries for electricity storage.