bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF PREVIOUS CONCUSSION OR INJURY ON SPORT-SPECIFIC SKILLS IN ELITE YOUTH ICE HOCKEY: A PILOT STUDY
Authors: Eliason P , McKay C , Meeuwisse W , Emery CA
Published: March 2014

Background

Concussions can lead to cognitive or neuromotor impairments which may influence skill performance. No published research has investigated the effect of previous concussions on sport-specific skill performance. Skill performance may be an important component of injury prevention strategy development in youth ice hockey.

Objective

To investigate the effect of previous concussion or injury on sport-specific skill performance in elite youth ice hockey.

Design

Cross Sectional pilot study.

Setting

Winsport arena in Calgary, Alberta, Canada.

Participants:

A sample of ten teams (n=131, 84 males and 47 females, ages 13-17) representing the most elite 20% of players by division of play (“AA, AAA”).

Risk factor assessment

Players completed a preseason baseline questionnaire including history of previous concussion and/or injury in the past year.

Main outcome measurements

On-ice skills testing was based on the Hockey Canada Skills Test (HCST) battery which included forward agility weave, forward and backward speed skate, forward to backward transition agility, and a 6-repeat endurance test.

Results

Comparing players with a history of concussion and those without, there were no differences in HCST component scores. There were also no differences in HCST scores between those reporting a previous injury within 1 year and those without. Males were faster than females on all HCST timed skill components, except for forward agility weave without the puck. Midget players were faster than Bantam players for transition agility with and without the puck, forward speed with the puck, and backward speed with and without the puck.

Conclusion

There were no apparent associations between history of concussion and/or injury and sport-specific skill performance. Our results provide reference values for HCST component scores that can allow assessment of risk and provide a foundation for prevention studies.
THE EFFECT OF PROTECTIVE TAEKWONDO FOOTPADS ON ATTENUATING IMPACTS OF AN INSTRUMENTED HEAD-FORM
Authors: Fife G , O'Sullivan D , Pieter W , Lee S
Published: March 2014

Background

A recent regulation in boxing, of removing headgear, proposes the question as to whether a similar rule should be adopted in taekwondo.

Objective

To assess the effect of protective taekwondo footpads on attenuating impacts of an instrumented head-form. It is hypothesised that footpads with greater thickness would mitigate impacts better than thinner ones.

Design

Between groups.

Setting

Impact biomechanics laboratory.

Participants

World Taekwondo Federation approved protective footpads.

Risk factor assessment

A standardized (ASTM F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III head and neck complex. All impacts were imparted with a terminal striking velocity of 5.0 m/s (min-max: 4.75–5.15 m/s). Six different striking conditions were employed (no footpad (control), KDS, Adidas, Mooto, Mooto MTX, old style footpad [i.e., thick]). Each footpad condition was tested for a total of 3 impacts. The level of significance was set to an effect size of 0.2.

Main outcome measurements

Resultant linear acceleration (RLA).

Results

Significant differences were found between all footpads (eta2=0.86). The most effective impact attenuation was provided by the old style footpad (102g), followed by the Adidas (124g), KDS (140g), Mooto (140g), MTX (149g), and non-footpad condition (211g). The greatest difference in RLA was observed between the thick footpad and the non-padded condition (102 g v 211 g, d=2.08, 95% CI=-0.19–3.51).

Conclusions

The footpads when compared with the control condition did decrease the RLA but not to an ASTM standard of 50g. These results do not support the removal of protective taekwondo headgear. Future studies may investigate the use of better designed footpads if a similar regulation were to be adopted.
DEVELOPMENT OF AN OBSERVATIONAL TOOL TO ASSESS QUALITY OF EXERCISE PERFORMANCE BY PARTICIPANTS IN A NEUROMUSCULAR INJURY PREVENTION PROGRAM
Authors: Fortington L , Finch CF , Donaldson A , Lathlean T , Cook J , Gabbe B , Lloyd D , Young W
Published: March 2014

Background

In determining the effectiveness of sports injury prevention programs (IPP), an assessment of program fidelity is needed. This includes considering whether the intervention was delivered and adhered to as it was intended. Evaluation of program fidelity prevents incorrect conclusions being made about the effects of an IPP and can provide information on why it was successful, or not. Program fidelity for IPPs in sport has generally been limited to self-reported measures around frequency of participation. However, for exercise-based IPPs, performing the exercises as they were originally prescribed is important to maximise injury prevention benefits. Therefore, observing the actual exercise performance could give important insight when evaluating overall IPP fidelity.

Objective

The aim of this study was to develop an observational tool for exercise-based IPPs and assess its inter-rater reliability. This was trialled in the context of FootyFirst, an IPP in Australian Football.

Design

The essential performance criteria of each FootyFirst exercise were described in terms of their technique, volume and intensity, in line with exercise prescription guidelines. The expert FootyFirst development team were consulted until consensus was reached on details of each exercise. Each criterion was evaluated by observing player performance and responding with a yes/no answer.

Setting

Community Australian football clubs.

Participants

Players participating in FootyFirst as part of regular training; two independent raters.

Main outcome measurements

Inter-rater reliability of tool and correct performance of FootyFirst exercises.

Results

The observational tool was trialled at eight clubs for 70 observations. The raters agreed on 61 observations (K=0.718, P<.001; substantial agreement), of which 41(67%) scored yes for all performance criteria (technique, volume and intensity), indicating the exercise was performed as prescribed.

Conclusions

The FootyFirst Observational Tool has high inter-rater reliability. This can be used to monitor the quality of exercise performance when assessing overall program fidelity.
NORMATIVE DATA FOR THE FUNCTIONAL MOVEMENT SCREEN™ IN MALE GAELIC FIELD SPORTS
Authors: Fox D , O'Malley E , Blake C
Published: March 2014

Background

Hurling and Gaelic Football are amateur team field sports which are native to Ireland. Due to the speed, player to player contact and multidirectional nature of the sports, injury to players is inevitable.

Objective

Determine normative values for the Functional Movement Screen™ (FMS) in Elite and Sub-Elite male Gaelic Football and Hurling players.

Design

A cross sectional study of functional movement in Gaelic games. Players were video recorded completing the FMS™ and scored post-test.

Setting

Testing of Elite and Sub-Elite Gaelic players in a gym and university biomechanics laboratory.

Participants

A total of 62 players (injury-free) were included. This consisted of 41 Hurling, and 21 Gaelic Football players. 30 of these participants were deemed Elite and 32 were deemed Sub-Elite. The mean age of the sample was 22.15±3.02 years.

Risk factor assessment

The FMS™ is a screening method which is proposed to identify potential injury causing deficits in the human body. There are 7 specific components to the test (Deep Squat, Hurdle Step, In-line Lunge, Shoulder Mobility, Active Straight Leg Raise, Trunk Stability Push Up, Rotary Stability), accompanied by 3 clearing tests (Spinal flexion, Spinal extension, Shoulder internal rotation with flexion). Each is scored out of 3 for a maximum of 21. The clearing tests are not scored.

Main outcome measurement

Functional Movement Screen™ (FMS).

Results

The FMS mean score for the sample was 15.56±1.456. The Elite group (15.8±1.58) scored higher than the Sub-Elite group (15.34±1.31), but there was no significant difference between groups.

Conclusions

This study provides normative reference values for Gaelic Players. Elite Gaelic Players perform no better than a young, active population in the FMS indicating a potential problem with the FMS as a measure. The ability of the FMS to detect injury risk is not well supported and clinicians should be cautious using it as such.
PRIMARY AND SECONDARY HARM PREVENTION–EATING DISORDERS IN BRITISH ATHLETICS
Authors: Fylan J , Currie A , Lightfoot L
Published: March 2014

Background

Eating disorders are prevalent in athletics and impact on health and performance. Knowledge of how the sports environment contributes to risk can be translated into effective prevention and harm reduction.

Objectives

To ensure that the workforce (including volunteers) of British Athletics can: 1) Practice in a manner that minimizes the eating disorder risk, 2) Recognise the early warning signs of disordered eating, 3) Support and direct athletes to appropriate help.

Design

The Welfare Department of British Athletics consulted with eating disorders experts to develop an education package and describe a referral pathway.

Setting

British Athletics–the organisation responsible for the sport's governance, funding and development throughout the United Kingdom.

Participants

50 leaders in medical, coaching and support staff with a cascade mechanism for dissemination to all staff and athletes.

Interventions

A seminar for all key personnel (covering the extent of the problem, prevention, early detection and access to treatment), supplemented by educational articles in athletics press, training videos uploaded to coach education website (ucoach.com) and resource pack for all staff.

Main outcome measurements

50 key personnel attended the seminar including the Chief Medical Officer (CMO). Referral pathways are now clear and managed by British Athletics. The CMO can direct immediate further action for funded athletes. All other athletes are signposted to appropriate help by the Welfare Department.

Results

There was a 100% approval rating for the resource pack. 96% reported improved understanding of the problem, 92% were confident with the referral pathways and 93% reported increased awareness of sources of support. 800 resource packs distributed and 1500 visits to ucoach.com.

Conclusions

Preventive measures for eating disorders are important and can be widely disseminated within national sports organisations. Prompt action minimises harm but requires clear pathways to assessment and further treatment.
The IOC consensus statement: beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S)
Authors: Mountjoy Margo , Sundgot-Borgen Jorunn , Burke Louise , Carter Susan , Constantini Naama , Lebrun Constance , Meyer Nanna , Sherman Roberta , Steffen Kathrin , Budgett Richard , Ljungqvist Arne
Published: March 2014

Protecting the health of the athlete is a goal of the International Olympic Committee (IOC). The IOC convened an expert panel to update the 2005 IOC Consensus Statement on the Female Athlete Triad. This Consensus Statement replaces the previous and provides guidelines to guide risk assessment, treatment and return-to-play decisions. The IOC expert working group introduces a broader, more comprehensive term for the condition previously known as ‘Female Athlete Triad’. The term ‘Relative Energy Deficiency in Sport’ (RED-S), points to the complexity involved and the fact that male athletes are also affected. The syndrome of RED-S refers to impaired physiological function including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis, cardiovascular health caused by relative energy deficiency. The cause of this syndrome is energy deficiency relative to the balance between dietary energy intake and energy expenditure required for health and activities of daily living, growth and sporting activities. Psychological consequences can either precede RED-S or be the result of RED-S. The clinical phenomenon is not a ‘triad’ of the three entities of energy availability, menstrual function and bone health, but rather a syndrome that affects many aspects of physiological function, health and athletic performance. This Consensus Statement also recommends practical clinical models for the management of affected athletes. The ‘Sport Risk Assessment and Return to Play Model’ categorises the syndrome into three groups and translates these classifications into clinical recommendations.
Maternal alcohol intake prior to and during pregnancy and risk of adverse birth outcomes: evidence from a British cohort
Authors: Nykjaer Camilla , Alwan Nisreen A , Greenwood Darren C , Simpson Nigel A B , Hay Alastair W M , White Kay L M , Cade Janet E
Published: March 2014

Background

Evidence is conflicting regarding the relationship between low maternal alcohol consumption and birth outcomes. This paper aimed to investigate the association between alcohol intake before and during pregnancy with birth weight and gestational age and to examine the effect of timing of exposure.

Methods

A prospective cohort in Leeds, UK, of 1303 pregnant women aged 18–45 years. Questionnaires assessed alcohol consumption before pregnancy and for the three trimesters separately. Categories of alcohol consumption were divided into ≤2 units/week and >2 units/week with a non-drinking category as referent. This was related to size at birth and preterm delivery, adjusting for confounders including salivary cotinine as a biomarker of smoking status.

Results

Nearly two-thirds of women before pregnancy and over half in the first trimester reported alcohol intakes above the Department of Health (UK) guidelines of ≤2 units/week. Associations with birth outcomes were strongest for intakes >2 units/week before pregnancy and in trimesters 1 and 2 compared to non-drinkers. Even women adhering to the guidelines in the first trimester were at significantly higher risk of having babies with lower birth weight, lower birth centile and preterm birth compared to non-drinkers, after adjusting for confounders (p<0.05).

Conclusions

We found the first trimester to be the period most sensitive to the effect of alcohol on the developing fetus. Women adhering to guidelines in this period were still at increased risk of adverse birth outcomes. Our findings suggest that women should be advised to abstain from alcohol when planning to conceive and throughout pregnancy.
A plasticity model for spudcan foundations in soft clay
Authors: Zhang Youhu , Cassidy Mark J. , Bienen Britta
Published: March 2014

A plasticity model for predicting the load displacement behaviour of a typical spudcan foundation for offshore jack-up platforms under combined vertical, horizontal, and moment loading in soft clay is presented. Results from geotechnical centrifuge experiments of a spudcan embedded vertically to 0.7, 1.0, and 1.45 footing diameters are described. Augmented with finite element results, these centrifuge experiments are used to evaluate the plasticity model components. As a result of soil backflow on top of the spudcan, enhanced combined bearing capacity was measured and this is reflected in increased yield surface size. A tensile vertical load capacity is also incorporated. The excellent predictive capabilities of the model are demonstrated by retrospectively simulating a selection of centrifuge tests.
Reaction products of diorganotin(IV) oxides, R2SnO, with nitric acid. Part 2 – R = n-butyl and t-butyl
Authors: Reuter Hans , Reichelt Martin
Published: March 2014

The reaction of diorganotin(IV) oxides, R2SnO with R = n-butyl and t-butyl, with nitric acid in different stoichiometric ratios resulted in the formation of different products depending on the organic groups attached to the tin atom: the diorganotin(IV) dinitrate dihydrates, n-Bu2Sn(NO3)2·2H2O (2d) and t-Bu2Sn(NO3)2·2H2O (2e), the mixed diorganotin(IV) nitrate methoxide oxide n-Bu2Sn(NO3)(n-Bu2SnOMe)O (6), and the diorganotin(IV) nitrate hydroxide hydrate t-Bu2Sn(NO3)(OH)·H2O = [t-Bu2Sn(OH)(H2O)][NO3] (7). On examination of the solubility of the primary reaction products in different solvents, the three additional compounds t-Bu2Sn(NO3)(OH)·DMSO (8), t-Bu2Sn(NO3)(OH)·THF, and 2-t-Bu2Sn(NO3)(OH)·DMF = [t-Bu2Sn(OH)dmf]2[NO3]2·[t-Bu2Sn(NO3)OH]2 (9) could be isolated. All compounds have been structurally characterized by single crystal X-ray diffraction (primary results for 7) with special attention paid to dimensionality (2d and 2c = monomeric, hydrogen bonded molecules; 6 = dimeric molecules of ladder-type structure; 7 = dimeric cation; 8 = dimeric molecule with hydrogen bonded solvent molecules; 9 = both components dimeric), tin coordination (6, 7, 8, and 9 = trigonal bipyramidal; 2d and 2e = eightfold), and nitrate bonding modes (7 and 9 = isolated, hydrogen bonded; 6, 8, and 9 (component 2) = monodentate; 2d and 2e = symmetrical bidentate), the latter one being analyzed using both Sn–O and N–O distances.
Comparison of wind tunnel measurements with NBCC 2010 wind-induced torsion provisions for low- and medium-rise buildings
Authors: Elsharawy Mohamed , Galal Khaled , Stathopoulos Ted
Published: March 2014

The aim of this study is to assess wind-induced torsional loads on low- and medium-rise buildings determined in accordance with the National Building Code of Canada (NBCC 2010). Two building models with the same horizontal dimensions but different gabled-roof angles (0° and 45°) were tested at different full-scale equivalent eave heights (6, 12, 20, 30, 40, 50, and 60 m) in open terrain exposure for several wind directions (every 15°). Wind-induced measured pressures were numerically integrated over all building surfaces and results were obtained for along-wind force, across-wind force, and torsional moment. Torsion load case (i.e., maximum torsion and corresponding shear) and shear load case (i.e., maximum shear and corresponding torsion) were evaluated to reflect the maximum actual wind load effects in the two horizontal directions (i.e., transverse and longitudinal). The evaluated torsion and shear load cases were also compared with the current torsion- and shear-related provisions in the NBCC 2010. The results demonstrated significant discrepancies between NBCC 2010 and the wind tunnel measurements regarding the evaluation of torsional wind loads on low- and medium-rise buildings. Finally, shear and torsion load cases were suggested for evaluating wind loads in the design of low- and medium-rise rectangular buildings.
Molecular systematic relationships and evidence for a recent origin of the thermal spring endemic snailsPhysella johnsoniandPhysella wrighti(Pulmonata: Physidae)
Authors: Remigio Elpidio A , Lepitzki Dwayne AW , Lee Jacqueline S , Hebert Paul DN
Published: March 2014

The evolutionary origins of Physella johnsoni and Physella wrighti, freshwater snails endemic to thermal springs in Alberta and British Columbia, were examined by sequence comparisons of mitochondrial genes coding for segments of the large subunit ribosomal RNA (16S) and cytochrome c oxidase I (COI) with those in the closely allied species Physella gyrina. Phylogenetic reconstructions based on combined and separate analyses of the datasets identified P. wrighti as the sister taxon to a P. johnsoni + P. gyrina clade. For both gene regions there was little or no sequence variation among conspecific individuals, but a number of diagnostic differences existed between each of the species pairs. Tree topologies and estimates of sequence divergence indicate that the divergence events which separated the three species occurred rather recently and at relatively brief intervals, and it is likely that P. wrighti is the source of the ancestral population from which P. johnsoni and P. gyrina were derived. Our findings support the recognition of P. johnsoni and P. wrighti as endemic species. The populations of P. johnsoni probably separated from P. gyrina about 10 000 years ago, when glaciers retreated from the Banff area and prehistoric lake levels dropped. The limited molecular divergence between P. johnsoni and P. gyrina argues against their current placement in different subgenera within the genus Physella.
The demographic response of bank-dwelling beavers to flow regulation: a comparison on the Green and Yampa rivers
Authors: Breck Stewart W , Wilson Kenneth R , Andersen Douglas C
Published: March 2014

We assessed the effects of flow regulation on the demography of beavers (Castor canadensis) by comparing the density, home-range size, and body size of bank-dwelling beavers on two sixth-order alluvial river systems, the flow-regulated Green River and the free-flowing Yampa River, from 1997 to 2000. Flow regulation on the Green River has altered fluvial geomorphic processes, influencing the availability of willow and cottonwood, which, in turn, has influenced the demography of beavers. Beaver density was higher on the Green River (0.50.6 colonies per kilometre of river) than on the Yampa River (0.35 colonies per kilometre of river). Adult and subadult beavers on the Green River were in better condition, as indicated by larger body mass and tail size. There was no detectable difference in home-range size, though there were areas on the Yampa River that no beavers used. We attribute the improved habitat quality on the Green River to a greater availability of willow. We suggest that the sandy flats and sandbars that form during base flows and the ice cover that forms over winter on the Yampa River increase the energy expended by the beavers to obtain food and increase predation risk and thus lowers the availability of woody forage.
On a class of Einstein Finsler metrics
Authors: Shen Zhongmin , Yu Changtao
Published: March 2014

In this paper, we study Finsler metrics expressed in terms of a Riemannian metric, an 1-form, and its norm. We find equations which are sufficient conditions for such Finsler metrics to have constant Ricci curvature. Using certain transformations, we successfully solve these equations and hence construct a large class of Einstein metrics.
Lattice kinetic scheme for generalized coordinates and curved spaces
Authors: Mendoza M. , Debus J.-D. , Succi S. , Herrmann H. J.
Published: March 2014

We present a new lattice kinetic method to simulate fluid dynamics in curvilinear geometries and curved spaces. A suitable discrete Boltzmann equation is solved in contravariant coordinates, and the equilibrium distribution function is obtained by a Hermite polynomials expansion of the Maxwell–Boltzmann distribution, expressed in terms of the contravariant coordinates and the metric tensor. To validate the model, we calculate the critical Reynolds number for the onset of the Taylor–Couette instability between two concentric cylinders, obtaining excellent agreement with the theory. In order to extend this study to more general geometries, we also calculate the critical Reynolds number for the case of two concentric spheres, finding good agreement with experimental data, and the case of two concentric tori, where we have found that it is around 10% larger than the respective values for the two concentric cylinders.
Optimal control analysis of hepatitis C virus with acute and chronic stages in the presence of treatment and infected immigrants
Authors: Okosun Kazeem Oare , Makinde Oluwole Daniel
Published: March 2014

In this paper, we consider a deterministic hepatitis C virus (HCV) model and study the impact of optimal control on the screening of immigrants and treatment of HCV on the transmission dynamics of the disease in a homogeneous population with constant immigration of susceptibles. First, we derived the condition in which disease-free equilibrium is locally asymptotically stable and established that a stable disease-free equilibrium can only be achieved in the absence of infective immigrants. Second, we investigated the impact of each control mechanism individually and the combinations of these strategies in the control of HCV. The costs associated with each of these strategies are also investigated by formulating the costs function problem as an optimal control problem, and we then use the Pontryagin's Maximum Principle to solve the optimal control problems. From the numerical simulations we found that the optimal combination of treatment of acute-infected and chronic-infected individuals control strategy produced the same results as the combination of the three strategies (combination of screening of immigrants, treatment of acute-infected and chronic-infected individuals). By our model and these results, we suggest the treatment of acute-infected and chronic-infected individuals control strategy should be optimized where resources are scarce, because the implementation of the three strategies (combination of screening of immigrants, treatment of acute-infected and chronic-infected individuals) would imply additional cost.
Influences of nodular chert rhythmites on natural fracture networks in carbonates: an outcrop and two-dimensional discrete element modelling study
Authors: Spence Guy H. , Finch Emma
Published: March 2014

Natural fractures control primary fluid flow in low-matrix-permeability carbonate hydrocarbon reservoirs, making it important to understand the factors that affect natural fracture distributions and networks. Away from the influence of folds and faults, stratigraphic controls are accepted to be the major control on fracture networks. The influence of carbonate nodular chert rhythmite successions on natural fracture networks is investigated here using a Discrete Element Modelling (DEM) technique that draws on outcrop observations of naturally fractured carbonates in the Eocene Thebes Formation, exposed in the west central Sinai of Egypt, that also form reservoir rocks in the subsurface. Stratally-bound chert nodules below bedding surfaces create lateral heterogeneities that vary over short distances. The resulting distribution of physical properties (differing stiffnesses) caused by chert rhythmites is shown to generate extra complexity in natural fracture networks in addition to that caused by bed thickness and lithological physical properties. Chert rhythmite successions need to be considered as a distinct type of carbonate fractured reservoir. Stratigraphic rules for predicting the distribution, lengths and spacing of natural fractures, and quantitative fracture indices (
P
11
,
P
21
,
P
22
and fractal dimension) are generated from the DEM outcomes. In a less-stiff carbonate medium, the presence of chert nodules reduces fracture intensity at chert horizons, and fractures per unit area are higher in chert-free vertical corridors. In a stiff carbonate medium, chert has little influence on fracture development. In a peritidal cyclic succession with constant layer thicknesses, the presence of chert in less-stiff carbonate horizons results in a reduction in fracture intensity. When chert is introduced in a subtidal cyclic sequence with constant layer thicknesses, it has little effect on fracture distribution. The study has widespread significance for characterizing naturally fractured reservoirs containing carbonate nodular chert rhythmites.
Gas injection test in the Callovo-Oxfordian claystone: data analysis and numerical modelling
Authors: De La Vaissière Rémi , Gerard Pierre , Radu Jean-Pol , Charlier Robert , Collin Frédéric , Granet Sylvie , Talandier Jean , Piedevache Médéric , Helmlinger Benjamin
Published: March 2014

This paper describes a field-scale experiment on gas transport mechanisms performed at Andra's Underground Research Laboratory (URL) in a clay rock. The experimental layout consists of two parallel boreholes that are equipped with multiple packer completions isolating three intervals each, which have been continuously monitoring the pore pressure evolution of the clay rock. Nitrogen gas was injected in the middle test interval of one of the boreholes at increasing rates. The entire gas test comprised six periods of controlled gas injections, each followed by a shut-in pressure recovery phase. The experimental data are presented along with their interpretation by means of numerical modelling of two-phase flow of gas and water using different numerical codes and different geometrical approaches that include axisymmetric, half-space and full 3D models. An iterative modelling process was used to show step-by-step how an accurate description of each component of the experiment system produced a satisfactory reproduction of the experimental data and an improved understanding of the relevant phenomena. For instance, the initial volume of remaining water in the test interval, and the presence of a damaged zone around the boreholes, was important for the models to obtain good agreement with the field data.
Dynamics and Timekeeping in Biological Systems
Authors: Dobson Christopher M.
Published: March 2014

This article introduces three reviews on the theme of circadian rhythms.
Understanding Nucleic Acid–Ion Interactions
Authors: Lipfert Jan , Doniach Sebastian , Das Rhiju , Herschlag Daniel
Published: March 2014

Ions surround nucleic acids in what is referred to as an ion atmosphere. As a result, the folding and dynamics of RNA and DNA and their complexes with proteins and with each other cannot be understood without a reasonably sophisticated appreciation of these ions' electrostatic interactions. However, the underlying behavior of the ion atmosphere follows physical rules that are distinct from the rules of site binding that biochemists are most familiar and comfortable with. The main goal of this review is to familiarize nucleic acid experimentalists with the physical concepts that underlie nucleic acid–ion interactions. Throughout, we provide practical strategies for interpreting and analyzing nucleic acid experiments that avoid pitfalls from oversimplified or incorrect models. We briefly review the status of theories that predict or simulate nucleic acid–ion interactions and experiments that test these theories. Finally, we describe opportunities for going beyond phenomenological fits to a next-generation, truly predictive understanding of nucleic acid–ion interactions.
Lipidomics: Analysis of the Lipid Composition of Cells and Subcellular Organelles by Electrospray Ionization Mass Spectrometry
Authors: Brügger Britta
Published: March 2014

Lipidomics aims to quantitatively define lipid classes, including their molecular species, in biological systems. Lipidomics has experienced rapid progress, mainly because of continuous technical advances in instrumentation that are now enabling quantitative lipid analyses with an unprecedented level of sensitivity and precision. The still-growing category of lipids includes a broad diversity of chemical structures with a wide range of physicochemical properties. Reflecting this diversity, different methods and strategies are being applied to the quantification of lipids. Here, I review state-of-the-art electrospray ionization tandem mass spectrometric approaches and direct infusion to quantitatively assess lipid compositions of cells and subcellular fractions. Finally, I discuss a few examples of the power of mass spectrometry–based lipidomics in addressing cell biological questions.
Metabolic and Nontranscriptional Circadian Clocks: Eukaryotes
Authors: Reddy Akhilesh B. , Rey Guillaume
Published: March 2014

Circadian clocks are cellular timekeeping mechanisms that coordinate behavior and physiology around the 24-h day in most living organisms. Misalignment of an organism's clock with its environment is associated with long-term adverse fitness consequences, as exemplified by the link between circadian disruption and various age-related diseases in humans. Current eukaryotic models of the circadian oscillator rely on transcription/translation feedback loop mechanisms, supplemented with accessory cytosolic loops that connect them to cellular physiology. However, mounting evidence is questioning the absolute necessity of transcription-based oscillators for circadian rhythmicity, supported by the recent discovery of oxidation-reduction cycles of peroxiredoxin proteins, which persist even in the absence of transcription. A more fundamental mechanism based on metabolic cycles could thus underlie circadian transcriptional and cytosolic rhythms, thereby promoting circadian oscillations to integral properties of cellular metabolism.
Growth and the Smart State
Authors: Aghion Philippe , Roulet Alexandra
Published: March 2014

As countries develop, the main driver of economic growth shifts from imitation to innovation. These two sources of growth require different policies and institutions. In particular, in this article we argue that the transition from an imitation-based to an innovation-based economy calls the old welfare state model into question. It is not so much the size of the state that is at stake but rather its governance. What we need to foster economic growth in developed economies is not a reduced state but a strategic state, which acts as a catalyst using selective and properly governed support to the market-driven innovation process. This idea of a strategic state that targets its investments to maximize growth in the face of hard budget constraints departs both from the Keynesian view of a state sustaining growth through demand-driven policies and from the neoliberal view of a minimal state confined to its regalian functions.
Who Is the Global Fuel Cell Leader Today? What the United States Needs to Do to Get Back in the Lead
Authors: Behling Noriko
Published: March 2014

Three government entities have vigorously competed for leadership in the fuel cell field—the EU (the European Union in combination with individual European state government), Japan, and the United States. For many years, Japan had no significant fuel cell accomplishments, nor had it successfully brought to market fuel cell products. Yet today Japan is leading the world in fuel cell market share. How did they do it? The story is simple. It worked out a long term plan and stuck with it. Key laws were enacted to address the inferior science and technology competence in Japan and promote originality, inventiveness, and entrepreneurship. Second, the government ensured that the laws were implemented by all the relevant ministries. Third, policy initiatives were developed to promote fuel cell technology, which were supported by the entire government, including the Prime Minister’s office. Fourth, the government published ambitious fuel cell roadmaps and demonstrated consistent and strong leadership to ensure that industry joined forces with the government. Finally, the government provided a robust and stable fuel cell budget. As a result, Japan now leads the world in fuel cell patents and has the largest market for fuel cell products in the world. Comparisons with the EU and US programs suggest that Japan could remain the leader for some time to come, unless the US adopts a new strategy for fuel cell development. This strategy will require building a political consensus between government and industry as well as undertaking substantial changes to R&D programs and management.
A microstructural model of reentry arising from focal breakthrough at sites of source-load mismatch in a central region of slow conduction
Authors: Hubbard Marjorie Letitia , Henriquez Craig S.
Published: March 2014

Regions of cardiac tissue that have a combination of focal activity and poor, heterogeneous gap junction coupling are often considered to be arrhythmogenic; however, the relationship between the properties of the cardiac microstructure and patterns of abnormal propagation is not well understood. The objective of this study was to investigate the effect of microstructure on the initiation of reentry from focal stimulation inside a poorly coupled region embedded in more well-coupled tissue. Two-dimensional discrete computer models of ventricular monolayers (1 × 1 cm) were randomly generated to represent heterogeneity in the cardiac microstructure. A small, central poorly coupled patch (0.40 × 0.40 cm) was introduced to represent the site of focal activity. Simulated unipolar electrogram recordings were computed at various points in the tissue. As the gap conductance of the patch decreased, conduction slowed and became increasingly complex, marked by fractionated electrograms with reduced amplitude. Near the limit of conduction block, isolated breakthrough sites occurred at single cells along the patch boundary and were marked by long cell-to-cell delays and negative deflections on electrogram recordings. The strongest determinant of the site of wavefront breakthrough was the connectivity of the brick wall architecture, which enabled current flow through small regions of overlapping cells to drive propagation into the well-coupled zone. In conclusion, breakthroughs at the size scale of a single cell can occur at the boundary of source-load mismatch allowing focal activations from slow conducting regions to produce reentry. These breakthrough regions, identifiable by distinct asymmetric, reduced amplitude electrograms, are sensitive to tissue architecture and may be targets for ablation.
Absence of c-Jun NH2-terminal kinase 1 protects against house dust mite-induced pulmonary remodeling but not airway hyperresponsiveness and inflammation
Authors: van der Velden Jos L. J. , Hoffman Sidra M. , Alcorn John F. , Tully Jane E. , Chapman David G. , Lahue Karolyn G. , Guala Amy S. , Lundblad Lennart K. A. , Aliyeva Minara , Daphtary Nirav , Irvin Charles G. , Janssen-Heininger Yvonne M. W.
Published: March 2014

Chronic allergic asthma leads to airway remodeling and subepithelial fibrosis via mechanisms not fully understood. Airway remodeling is amplified by profibrotic mediators, such as transforming growth factor-β1 (TGF-β1), which plays a cardinal role in various models of fibrosis. We recently have identified a critical role for c-Jun-NH2-terminal-kinase (JNK) 1 in augmenting the profibrotic effects of TGF-β1, linked to epithelial-to-mesenchymal transition of airway epithelial cells. To examine the role of JNK1 in house dust mite (HDM)-induced airway remodeling, we induced allergic airway inflammation in wild-type (WT) and JNK1−/− mice by intranasal administration of HDM extract. WT and JNK1−/− mice were sensitized with intranasal aspirations of HDM extract for 15 days over 3 wk. HDM caused similar increases in airway hyperresponsiveness, mucus metaplasia, and airway inflammation in WT and JNK1−/− mice. In addition, the profibrotic cytokine TGF-β1 and phosphorylation of Smad3 were equally increased in WT and JNK1−/− mice. In contrast, increases in collagen content in lung tissue induced by HDM were significantly attenuated in JNK1−/− mice compared with WT controls. Furthermore HDM-induced increases of α-smooth muscle actin (α-SMA) protein and mRNA expression as well as the mesenchymal markers high-mobility group AT-hook 2 and collagen1A1 in WT mice were attenuated in JNK1−/− mice. The let-7 family of microRNAs has previously been linked to fibrosis. HDM exposure in WT mice and primary lung epithelial cells resulted in striking decreases in let-7g miRNA that were not observed in mice or primary lung epithelial cells lacking JNK1−/− mice. Overexpression of let-7g in lung epithelial cells reversed the HDM-induced increases in α-SMA. Collectively, these findings demonstrate an important requirement for JNK1 in promoting HDM-induced fibrotic airway remodeling.
Motile cilia harbor serum response factor as a mechanism of environment sensing and injury response in the airway
Authors: Nordgren Tara M. , Wyatt Todd A. , Sweeter Jenea , Bailey Kristina L. , Poole Jill A. , Heires Art J. , Sisson Joseph H. , Romberger Debra J.
Published: March 2014

Nonmotile primary cilia are recognized as important sensory organelles during development and normal biological functioning. For example, recent work demonstrates that transcriptional regulators of the sonic hedgehog signaling pathway localize to primary cilia and participate in sensing and transducing signals regarding the cellular environment. In contrast, motile cilia are traditionally viewed as mechanical machinery, vital for the movement of solutes and clearance of bacteria and debris, but not participants in cellular sensing and signaling mechanisms. Recently, motile cilia were found to harbor receptors responsible for sensing and responding to environmental stimuli. However, no transcription factors are known to be regulated by cilia localization as a sensing mechanism in vertebrates. Using a mouse model of organic dust-induced airway inflammation, we found that the transcription factor serum response factor (SRF) localizes to motile cilia of airway epithelial cells and alters its localization in response to inflammatory stimuli. Furthermore, inhibition of SRF signaling using the small molecule CCG-1423 reduces organic dust-induced IL-8 release from bronchial epithelial cells and stimulates cilia beat frequency in ciliated mouse tracheal epithelial cells. Immunohistochemical analyses reveal that SRF localizes to the cilia of mouse brain ependymal and ovarian epithelial cells as well. These data reveal a novel mechanism by which a transcription factor localizes to motile cilia and modulates cell activities including cilia motility and inflammation response. These data challenge current dogma regarding motile cilia functioning and may lead to significant contributions in understanding motile ciliary signaling dynamics, as well as mechanisms involving SRF-mediated responses to inflammation and injury.
Effect of acute hypoxia on regional cerebral blood flow: effect of sympathetic nerve activity
Authors: Lewis Nia C. S. , Messinger Laura , Monteleone Brad , Ainslie Philip N.
Published: March 2014

We examined 1) whether global cerebral blood flow (CBF) would increase across a 6-h bout of normobaric poikilocapnic hypoxia and be mediated by a larger increase in blood flow in the vertebral artery (VA) than in the internal carotid artery (ICA); and 2) whether additional increases in global CBF would be evident following an α1-adrenergic blockade via further dilation of the ICA and VA. In 11 young normotensive individuals, ultrasound measures of ICA and VA flow were obtained in normoxia (baseline) and following 60, 210, and 330 min of hypoxia (FiO2 = 0.11). Ninety minutes prior to final assessment, participants received an α1-adrenoreceptor blocker (prazosin, 1 mg/20 kg body mass) or placebo. Compared with baseline, following 60, 220, and 330 min of hypoxia, global CBF [(ICAFlow + VAFlow) ∗ 2] increased by 160 ± 52 ml/min (+28%; P = 0.05), 134 ± 23 ml/min (+23%; P = 0.02), and 113 ± 51 (+19%; P = 0.27), respectively. Compared with baseline, ICAFlow increased by 23% following 60 min of hypoxia ( P = 0.06), after which it progressively declined. The percentage increase in VA flow was consistently larger than ICA flow during hypoxia by ∼20% ( P = 0.002). Compared with baseline, ICA and VA diameters increased during hypoxia by ∼9% and ∼12%, respectively ( P ≤ 0.05), and were correlated with reductions in SaO2. Flow and diameters were unaltered following α1 blockade ( P ≥ 0.10). In conclusion, elevations in global CBF during acute hypoxia are partly mediated via greater increases in VA flow compared with ICA flow; this regional difference was unaltered following α1 blockade, indicating that a heightened sympathetic nerve activity with hypoxia does not constrain further dilation of larger extracranial blood vessels.
Essential role of hemoglobin beta-93-cysteine in posthypoxia facilitation of breathing in conscious mice
Authors: Gaston Benjamin , May Walter J. , Sullivan Spencer , Yemen Sean , Marozkina Nadzeya V. , Palmer Lisa A. , Bates James N. , Lewis Stephen J.
Published: March 2014

When erythrocyte hemoglobin (Hb) is fully saturated with O2, nitric oxide (NO) covalently binds to the cysteine 93 residue of the Hb β-chain (B93-CYS), forming S-nitrosohemoglobin. Binding of NO is allosterically coupled to the O2 saturation of Hb. As saturation falls, the NO group on B93-CYS is transferred to thiols in the erythrocyte, and in the plasma, forming circulating S-nitrosothiols. Here, we studied whether the changes in ventilation during and following exposure to a hypoxic challenge were dependent on erythrocytic B93-CYS. Studies were performed in conscious mice in which native murine Hb was replaced with human Hb (hB93-CYS mice) and in mice in which murine Hb was replaced with human Hb containing an alanine rather than cysteine at position 93 on the Bchain (hB93-ALA). Both strains expressed human γ-chain Hb, likely allowing a residual element of S-nitrosothiol-dependent signaling. While resting parameters and initial hypoxic (10% O2, 90% N2) ventilatory responses were similar in hB93-CYS mice and hB93-ALA mice, the excitatory ventilatory responses (short-term potentiation) that occurred once the mice were returned to room air were markedly diminished in hB93-ALA mice. Further, short-term potentiation responses were virtually absent in mice with bilateral transection of the carotid sinus nerves. These data demonstrate that hB93-CYS plays an essential role in mediating carotid sinus nerve-dependent short-term potentiation, an important mechanism for recovery from acute hypoxia.
Solution of an Integral-Differential Equation Arising in Oscillating Magnetic Fields Using Local Polynomial Regression
Authors: Li Fenglan , Yan Tianshun , Su Liyun
Published: March 2014

An integrodifferential equation which describes the charged particle motion for certain configurations of oscillating magnetic fields is considered. The local polynomial regression method (LPR) is used to solve this equation. The reliability of this method and the reduction in the size of computational domain give this method a wider applicability. Several representative examples are given to reconfirm the efficiency of these algorithms. The results of applying this theory to the integro-differential equation with time-periodic coefficients reveal that LPR method possesses very high accuracy, adaptability, and efficiency.
Studies on the Antidiabetic Activities ofCordyceps militarisExtract in Diet-Streptozotocin-Induced Diabetic Sprague-Dawley Rats
Authors: Dong Yuan , Jing Tianjiao , Meng Qingfan , Liu Chungang , Hu Shuang , Ma Yihang , Liu Yan , Lu Jiahui , Cheng Yingkun , Wang Di , Teng Lirong
Published: March 2014

Due to substantial morbidity and high complications, diabetes mellitus is considered as the third “killer” in the world. A search for alternative antidiabetic drugs from herbs or fungi is highly demanded. Our present study aims to investigate the antidiabetic activities ofCordyceps militarison diet-streptozotocin-induced type 2 diabetes mellitus in rats. Diabetic rats were orally administered with water extract or alcohol extract at 0.05 g/kg and 2 g/kg for 3 weeks, and then, the factors levels related to blood glucose, lipid, free radicals, and even nephropathy were determined. Pathological alterations on liver and kidney were examined. Data showed that, similar to metformin,Cordyceps militarisextracts displayed a significant reduction in blood glucose levels by promoting glucose metabolism and strongly suppressed total cholesterol and triglycerides concentration in serum.Cordyceps militarisextracts exhibit antioxidative effects indicated by normalized superoxide dismutase and glutathione peroxidase levels. The inhibitory effects on blood urea nitrogen, creatinine, uric acid, and protein revealed the protection ofCordyceps militarisextracts against diabetic nephropathy, which was confirmed by pathological morphology reversion. Collectively,Cordyceps militarisextract, a safe pharmaceutical agent, presents excellent antidiabetic and antinephropathic activities and thus has great potential as a new source for diabetes treatment.