bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral characteristics of the plasma dispersionless injection during the storm recovery phase on 11 March 1998
Authors: He Z. H. , Chen T. , Liu Z. X. , Pu Z. Y. , Roth I. , Duan S. P. , Dunlop M. W.
Published: October 2012

A substorm dispersionless injection event observed during the storm recovery phase on 11 March 1998 at geosynchronous orbit is carefully studied. The event shows the notable characteristics that for energetic ions the flux enhancement ratio before and after injection increases and remains elevated with increasing energy, while for energetic electrons it tends to decrease with increasing energy. In order to explain the unique injection feature, the authors propose a possible mechanism that velocity space diffusion in common to electric acceleration adjusts the particle injection state. Spectral characteristics of four different phases (pregrowth phase, the growth phase, the substorm expansion phase, and the recovery phase) have been investigated. The differential fluxes of electrons from 50 keV to 1.5 Mev and ions from 50 keV to 1.2 MeV measured by Synchronous Orbit Plasma Analyzer (SOPA) instrument onboard LANL satellite 1991–080 are found to be best fitted with the three‐parameter kappa distribution function (f ∼ A0 · E[1 + E / (κE0)]−κ−1) by Levenberg‐Marquardt and Universal Global Optimization methods. The evolutions of the three parameters in the above kappa distribution in different substorm phases have been depicted for both electrons and ions. In each phase, E0 and κ show an approximately linear relationship κ(E0) = κ0 + ηE0. This linear relationship can be obtained by solving the velocity space diffusion equation with an initial superthermal kappa distribution. Ion and electron are found to have opposite trend of parameters κ0 and η in each phase, which indicates that the different species of particles exert different velocity space diffusion processes so that their flux enhancement ratios before and after injection are rather different. This implies that not only electric field acceleration, but also velocity space diffusion plays a very important role in the particle injection.
Mantle flow, volatiles, slab‐surface temperatures and melting dynamics in the north Tonga arc–Lau back‐arc basin
Authors: Caulfield John , Turner Simon , Arculus Richard , Dale Chris , Jenner Frances , Pearce Julian , Macpherson Colin , Handley Heather
Published: October 2012

The Fonualei Spreading Center affords an excellent opportunity to evaluate geochemical changes with increasing depth to the slab in the Lau back‐arc basin. We present H2O and CO2concentrations and Sr, Nd, Pb, Hf and U‐Th‐Ra isotope data for selected glasses as well as new Hf isotope data from boninites and seamounts to the north of the Tonga arc. The Pb and Hf isotope data are used to show that mantle flow is oriented to the southwest and that the tear in the northern end of the slab may not extend east as far as the boninite locality. Along the Fonualei Spreading Center, key geochemical parameters change smoothly with increasing distance from the arc front and increasing slab surface temperatures. The latter may range from 720 to 866°C, based on decreasing H2O/Ce ratios. Consistent with experimental data, the geochemical trends are interpreted to reflect changes in the amount and composition of wet pelite melts or super‐critical fluids and aqueous fluids derived from the slab. With one exception, all of the lavas preserve both238U excesses and 226Ra excesses. We suggest that lavas from the Fonualei Spreading Center and Valu Fa Ridge are dominated by fluid‐fluxed melting whereas those from the East and Central Lau Spreading Centers, where slab surface temperatures exceed ∼850–900°C, are largely derived through decompression. A similar observation is found for the Manus and East Scotia back‐arc basins and may reflect the expiry of a key phase such as lawsonite in the subducted basaltic crust.
Hydrate morphology: Physical properties of sands with patchy hydrate saturation
Authors: Dai S. , Santamarina J. C. , Waite W. F. , Kneafsey T. J.
Published: October 2012

The physical properties of gas hydrate‐bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate‐bearing sediments, including the coarse‐grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate‐bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore‐space hydrate saturation are embedded in hydrate‐free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate‐bearing sands and captures observed physical‐property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate‐patch size itself impacts the physical properties of hydrate‐bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate‐saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate‐saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross‐section of the specimen.
Spatial and temporal variability in phytoplankton carbon, chlorophyll, and nitrogen in the North Pacific
Authors: Xiu Peng , Chai Fei
Published: October 2012

Carbon, nitrogen, and chlorophyll are three commonly used variables to quantify phytoplankton productivity. However, owing to the complex effect of light, temperature, and nutrient, these three variables are usually decoupled from each other. By implementing a biogeochemical model that treats phytoplankton carbon, nitrogen, and chlorophyll separately in a Pacific basin‐scale circulation model, we have investigated the physical and biogeochemical controls on phytoplankton C:Chl and C:N ratios at different scales. The model reproduces the general features of phytoplankton dynamics in the Pacific basin. Model results indicate a region dependent pattern of driving mechanisms for C:Chl ratio, where C:Chl is largely controlled by light condition in high latitude, by light and nutrient levels in midlatitude, and by nutrient and temperature in the equatorial Pacific, while C:N ratio seems to be region independent and is mostly determined by nutrient and temperature. Pacific basin‐scale empirical orthogonal functions (EOF) decompositions suggest both C:Chl and C:N are regulated by the El Niño/Southern Oscillation (ENSO) events to the first‐order variability. Owing to the variation of C:Chl, the decoupling between phytoplankton carbon and chlorophyll exists, especially at seasonal and long‐term temporal scales. Climate change can affect phytoplankton pigment, biomass, and physiological state. As a consequence, using chlorophyll as a proxy for phytoplankton biomass to interpret decadal variation or long‐term trend might be with bias.
Diurnal variations of the Fe layer in the mesosphere and lower thermosphere: Four season variability and solar effects on the layer bottomside at McMurdo (77.8°S, 166.7°E), Antarctica
Authors: Yu Zhibin , Chu Xinzhao , Huang Wentao , Fong Weichun , Roberts Brendan R.
Published: October 2012

We provide one of the first reports on diurnal variations of the Fe layer in the mesosphere and lower thermosphere (MLT) using nearly 1000 h of data collected with an Fe Boltzmann lidar at McMurdo, Antarctica from December 2010 through 2011. The Fe layer undergoes significant diurnal variations on the bottomside in autumn and spring with daytime downward extension and nighttime upward contraction. Such variations are absent in winter under 24‐h darkness. Summertime Fe density perturbations exhibit downward tidal phase progression. The bottom growth/contraction of Fe layer is shown to be a solar effect that is closely correlated with the solar elevation angle. The bottom transition corresponds to the solar elevation between −9° and −1° when sunlight passes through the lower atmosphere before reaching the MLT. Once the solar elevation is above −1°, the layer bottom remains nearly flat at its daytime altitude (∼70–73 km). When the solar elevation is below −9°, the layer bottom stays at its nighttime altitude (∼78–80 km). The descending transition rate at dawn is faster than the ascending rate at dusk. The time delay between appreciable Fe density and sunrise/sunset at the MLT increases with decreasing altitude and varies with season. We describe qualitatively how both neutral Fe chemistry with H, O and O3and photolysis of Fe‐containing molecular species may play important roles in Fe diurnal variations. Accurate rate coefficients for Fe neutral and photochemical reactions are essential to quantitatively explain the solar effects in diurnal variations of the Fe layer.
Mapping gravel bed river bathymetry from space
Authors: Legleiter C. J. , Overstreet B. T.
Published: October 2012

Understanding river form and behavior requires an efficient means of measuring channel morphology. This study evaluated the potential to map the bathymetry of two clear‐flowing, shallow (<3 m deep) gravel bed rivers <60 m wide from 2 m‐pixel WorldView2 satellite images. Direct measurements of water column optical properties were used to quantify constraints on depth retrieval. The smallest detectable change in depth was 0.01–0.04 m and the maximum detectable depth was 5 m in green bands but <2 m in the near‐infrared; lower sensor radiometric resolution yields less precise estimates over a smaller range. An algorithm for calibrating a band ratioXto field measurements of depthdproved effective when applied to spectra extracted from images (R2= 0.822 and 0.594 for the larger and smaller stream, respectively) or measured in the field (R2= 0.769 and 0.452). This procedure also identified optimal wavelength combinations, but different bands were selected for each site. Accuracy assessment of bathymetric maps produced using various calibration approaches and image types indicated that: 1) a lineardvs.Xrelation provided depth estimates nearly as accurate as a quadratic formulation; 2) panchromatic and pan‐sharpened multispectral images with smaller 0.5 m pixels did not yield more reliable depth estimates than the original images; and 3) depth retrieval was less reliable in pools due to saturation of the radiance signal. This investigation thus demonstrated the feasibility, as well as the limitations, of measuring the bathymetry of clear, shallow gravel bed rivers from space.
Oceanic carbon and water masses during the Mystery Interval: A model‐data comparison study
Authors: Huiskamp W. N. , Meissner K. J.
Published: October 2012

The ‘Mystery Interval’ (17.5–14.5 ka BP) is characterized by a large decline in atmospheric Δ14C synchronous with an increase in atmospheric CO2. The most widely accepted hypothesis to explain these observed shifts involves the existence of an isolated ‘old’ ocean carbon reservoir that was subsequently ventilated. Here we use the UVic Earth System Climate Model to locate a potential carbon rich and Δ14C depleted water mass under 17.5 ka BP boundary conditions. We then investigate two mechanisms for the potential ventilation of such a reservoir, namely the weakening of the North Atlantic Meridional Overturning due to iceberg calving and latitudinal shifts in Southern Hemisphere Westerlies (SHW) due to southern hemispheric warming. We find that simulations derived from an equilibrium state forced with present‐day SHW and moderate North Atlantic Deep Water (NADW) formation are in better agreement with atmospheric and ocean Δ14C reconstructions than simulations derived from an equilibrium state forced with a northward shifted SHW belt resulting in a shut‐down of the Atlantic Meridional Overturning and formation of North Pacific Deep Water. For simulations with present‐day SHW, the oldest water masses are found in the North Pacific, although the Southern Ocean cannot be ruled out as a potential ‘Mystery Reservoir’. According to our simulations, the strength of Atlantic overturning is the dominant mechanism in increasing the ocean‐atmosphere carbon flux, while shifting SHW results in a rearrangement of deep ocean carbon largely between the Atlantic and Pacific basins. In our ‘best case’ scenario, the model can account for 58% of the atmospheric CO2 increase and 48% of the atmospheric Δ14C decline. While the rate of ventilation and the age of ventilated water masses are comparable with observations, the ventilation in the model could not be sustained long enough to account for the full excursion seen in paleodata.
Anomalous 10Be spikes during the Maunder Minimum: Possible evidence for extreme space weather in the heliosphere
Authors: Kataoka Ryuho , Miyahara Hiroko , Steinhilber Friedhelm
Published: October 2012

Extreme space weather conditions pose significant problems for standard space weather models, which are available for some limited realistic parameter ranges. As a good example, anomalous spikes of cosmic ray induced 10Be have been found during the Maunder Minimum (AD1645–1715) at the qA negative solar minima, which cannot be quantitatively explained by standard drift theories of cosmic ray transport alone. Such an extreme amplification of solar cycle modulation of cosmic rays is presumably related to the altered condition of heliospheric environment at the prolonged sunspot disappearance, providing a clue for comprehensive understandings of long‐term changes in heliospheric environment, solar cycle modulation of cosmic rays, and the maximal range of incident cosmic ray flux that is very important for our practical space activities. Model sophistication to achieve precise forecast of such extreme condition of the heliosphere and the incoming cosmic ray flux is also of urgent need as the Sun is currently showing a tendency toward lower activity. Here we show that the cosmic ray spikes found at the Maunder Minimum may be explained by the contribution from the cross‐sector transport mechanism working in the heliosheath where cosmic ray particles effectively drift across stacked magnetic sectors due to the larger cyclotron radius than the distance between the sectors. Based on the new interpretation of the 10Be record, we clarify potentially important problems for space weather modelers to help with more realistic modeling of the heliosphere during periods of extremely weak solar activity, such as the Maunder Minimum.
The inflammation theory of disease
Authors: Hunter Philip
Published: October 2012

An increasing body of evidence shows that chronic inflammation causes and advances many common diseases. This opens new possibilities for treatment and therapy by blocking the inflammatory processes.
Extra-electron induced covalent strengthening and generalization of intrinsic ductile-to-brittle criterion
Authors: Niu Haiyang , Chen Xing-Qiu , Liu Peitao , Xing Weiwei , Cheng Xiyue , Li Dianzhong , Li Yiyi
Published: October 2012

Traditional strengthening ways, such as strain, precipitation and solid-solution, come into effect by pinning the motion of dislocation. Here, through first-principles calculations we report on an extra-electron induced covalent strengthening mechanism, which alters chemical bonding upon the introduction of extra-valence electrons in the matrix of parent materials. It is responsible for the brittle and high-strength properties of Al12W-type compounds featured by the typical fivefold icosahedral cages, which are common for quasicrystals and bulk metallic glasses (BMGs). In combination with this mechanism, we generalize ductile-to-brittle criterion in a universal hyperbolic form by integrating the classical Pettifor's Cauchy pressure with Pugh's modulus ratio for a wide variety of materials with cubic lattices. This study provides compelling evidence to correlate Pugh's modulus ratio with hardness of materials and may have implication for understanding the intrinsic brittleness of quasicrystals and BMGs.
Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner
Authors: Simonin Vagner , Galina Antonio
Published: October 2012

NO (nitric oxide) is described as an inhibitor of plant and mammalian respiratory chains owing to its high affinity for COX (cytochrome c oxidase), which hinders the reduction of oxygen to water. In the present study we show that in plant mitochondria NO may interfere with other respiratory complexes as well. We analysed oxygen consumption supported by complex I and/or complex II and/or external NADH dehydrogenase in Percoll-isolated potato tuber (Solanum tuberosum) mitochondria. When mitochondrial respiration was stimulated by succinate, adding the NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine) or DETA-NONOate caused a 70% reduction in oxygen consumption rate in state 3 (stimulated with 1 mM of ADP). This inhibition was followed by a significant increase in the Km value of SDH (succinate dehydrogenase) for succinate (Km of 0.77±0.19 to 34.3±5.9 mM, in the presence of NO). When mitochondrial respiration was stimulated by external NADH dehydrogenase or complex I, NO had no effect on respiration. NO itself and DETA-NONOate had similar effects to SNAP. No significant inhibition of respiration was observed in the absence of ADP. More importantly, SNAP inhibited PTM (potato tuber mitochondria) respiration independently of oxygen tensions, indicating a different kinetic mechanism from that observed in mammalian mitochondria. We also observed, in an FAD reduction assay, that SNAP blocked the intrinsic SDH electron flow in much the same way as TTFA (thenoyltrifluoroacetone), a non-competitive SDH inhibitor. We suggest that NO inhibits SDH in its ubiquinone site or its Fe–S centres. These data indicate that SDH has an alternative site of NO action in plant mitochondria.
Comparison of Narrative and Expository Writing in Students With and Without Language-Learning Disabilities
Authors: Koutsoftas Anthony D. , Gray Shelley
Published: October 2012

Purpose

Students with language-learning disabilities (LLD) demonstrate difficulties with written language, especially in the areas of productivity, complexity, and grammar. It is not clear how these deficits affect their performance on high-stakes tests, such as those required by the No Child Left Behind Act (U.S. Department of Education, 2002). This study used writing samples to compare how students with and without LLD scored on analytic writing measures that are typically used in writing research and on a more holistic measure of writing, the six-traits writing rubric (STWR; Education Northwest, 2006), which is used in high-stakes writing assessments.

Method

Fifty-six 4th and 5th graders with typical development (TD) or LLD produced 1 narrative and 1 expository writing sample. Measures of oral language ability and handwriting accuracy–speed were also obtained. The narrative and expository samples were scored using 5–6 separate analytic measures and 6 separate traits on the STWR.

Results

On narratives, the TD group scored significantly higher than the LLD group on 5 analytic measures and all 6 traits. Similarly, for expository, the TD group outscored the LLD group on 3 analytic measures and all 6 traits. Results demonstrate that the analytic scores of productivity, sentence complexity, and lexical diversity were correlated significantly with a higher overall score on the STWR for narrative writing samples only.

Discussion

Results of this study suggest that exclusive use of analytic scores to select treatment goals and document writing progress may not translate into increased scores on writing rubrics, particularly for expository writing samples.
Metalinguistics, Stress Accuracy, and Word Reading: Does Dialect Matter?
Authors: Jarmulowicz Linda , Taran Valentina L. , Seek Jamie
Published: October 2012

Purpose

The authors examined the influence of demographic variables on nonmainstream American English (NMAE) use; the differences between NMAE speakers and mainstream American English (MAE) speakers on measures of metalinguistics, single-word reading, and a new measure of morphophonology; and the differences between the 2 groups in the relationships among the measures.

Method

Participants were typically developing 3rd graders from Memphis, TN, including 21 MAE and 21 NMAE speakers. Children received a battery of tests measuring phonological and morphological awareness (PA and MA), morphophonology (i.e., accurately produced lexical stress in derived words), decoding, and word identification (WID).

Results

Controlling for socioeconomic status, measures of PA, decoding, and WID were higher for MAE than for NMAE speakers. There was no difference in stress accuracy between the dialect groups. Only for the NMAE group were PA and MA significantly related to decoding and WID. Stress accuracy was correlated with word reading for the NMAE speakers and with all measures for the MAE speakers.

Conclusion

Stress accuracy was consistently related to reading measures, even when PA and MA were not. Morphophonology involving suprasegmental factors may be an area of convergence between language varieties because of its consistent relationship to word reading.
Oral Language Competence, Young Speakers, and the Law
Authors: Snow Pamela C. , Powell Martine B. , Sanger Dixie D.
Published: October 2012

Purpose

This paper highlights the forensic implications of language impairment in 2 key (and overlapping) groups of young people: identified victims of maltreatment (abuse and/or neglect) and young offenders.

Method

Two lines of research pertaining to oral language competence and young people’s interface with the law are considered: 1 regarding investigative interviewing with children as victims or witnesses in the context of serious allegations of sexual abuse, and the other pertaining to adolescent offenders as suspects, witnesses, or victims. The linguistic demands that forensic interviewing places on these young people are also considered. Literature concerning the impact of early maltreatment on early language acquisition is briefly reviewed, as is the role of theory of mind in relation to the requirements of investigative interviewing of children and adolescents.

Implications

High-risk young people (i.e., those who are subject to child protection orders because of suspected or confirmed maltreatment, and those who are engaged with the youth justice system) face an elevated risk for suboptimal language development but may need to draw on their language skills in high-stakes forensic interviews. Implications for early intervention policy and practice are identified, and the need for greater speech-language pathology advocacy and engagement in forensic interviewing research is emphasized.
Postschool Educational and Employment Experiences of Young People With Specific Language Impairment
Authors: Conti-Ramsden Gina , Durkin Kevin
Published: October 2012

Purpose

This study examined the postschool educational and employment experiences of young people with and without specific language impairment (SLI).

Method

Nineteen-year-olds with (
n
= 50) and without (
n
= 50) SLI were interviewed on their education and employment experiences since finishing compulsory secondary education.

Results

On average, young people with SLI were less successful than their peers without SLI, but they did attain some achievements. Young people with SLI obtained ∼2, mostly vocational qualifications in the first few years post school. Young people continuing in education at 19 years were most commonly in lower level educational placements than their typically developing (TD) peers. Performance IQ and language/literacy skills were the strongest predictors of educational experience level at this age. Young people with SLI truant less and report feeling more supported than TD peers. In terms of employment, similar proportions of young people with and without SLI had jobs. A larger proportion of young people with SLI, however, were not in education, employment, or training at 19 years of age.

Conclusion

In the immediate postschool years, young people with SLI fare less well in education and employment than their TD peers.
Developmental Communication Impairments in Adults: Outcomes and Life Experiences of Adults and Their Parents
Authors: Clegg Judy , Ansorge Lydia , Stackhouse Joy , Donlan Chris
Published: October 2012

Purpose

This study identifies the outcomes and documents the longitudinal life experiences of adults who attended a specialist residential school for children with pervasive and complex developmental communication impairments.

Method

Semistructured interviews were carried out with 26 adult ex-pupils who had attended the school and the parents of 15 of the ex-pupils.

Results

Seven key themes were identified from the data, including (a) lack of appropriate support and the impact of this in early childhood, (b) advantages and disadvantages of specialist educational provision compared to mainstream and other provision, (c) changing impact of developmental communication impairments over time, (d) challenging transition away from specialist educational provision, (e) absence of appropriate support for adults with developmental communication impairments, (f) persisting impact of developmental communication impairments on social and emotional functioning in adult life, and (g) differences in perspective between the adult ex-pupils and their parents.

Conclusion

Across the adult ex-pupils and their parents, the perceived reported benefits of early intervention, parental support, specialist educational provision, and guidance at times of transitions should inform current service provision for this vulnerable group of individuals and their families.
Longitudinal Patterns of Behavioral, Emotional, and Social Difficulties and Self-Concepts in Adolescents With a History of Specific Language Impairment
Authors: Lindsay Geoff , Dockrell Julie E.
Published: October 2012

Purpose

This study explored the prevalence and stability of behavioral difficulties and self-concepts between the ages of 8 and 17 years in a sample of children with a history of specific language impairment (SLI). We investigated whether earlier behavioral, emotional, and social difficulties (BESD); self-concepts; and language and literacy abilities predicted behavioral difficulties and self-concepts at 16/17 years.

Method

In this prospective longitudinal study, 65 students were followed up with teacher behavior ratings and individual assessments of language, literacy, and self-concepts at 8, 10, 12, 16, and 17 years.

Results

The students had consistently higher levels than norms of 5 domains of BESD, which had different trajectories over time, and poorer scholastic competence, whose trajectory also varied over time. Earlier language ability did not predict later behavioral difficulties or self-concepts, but the prediction of academic self-concept at 16 by literacy at 10 years approached significance.

Conclusions

The importance of distinguishing domains of behavioral difficulties and self-concept is demonstrated. Language, when measured at 8 or 10 years of age, was not a predictor of behavior or self-concepts at 16 years, or of self-concepts at 17 years. The study stresses the importance of practitioners addressing academic abilities and different social–behavioral domains in delivering support for adolescents with SLI.
Social, Emotional, and Behavioral Functioning of Secondary School Students With Low Academic and Language Performance: Perspectives From Students, Teachers, and Parents
Authors: Joffe Victoria L. , Black Emma
Published: October 2012

Purpose

Adolescence is a time of transition when young people with language difficulties are at increased risk of experiencing social, emotional, and behavioral difficulties (SEBD). Most studies of social, emotional, and behavioral functioning (SEBF) in individuals with language difficulties focus on children with a clinical diagnosis of language impairment. This study explores SEBF in a nonclinical group of 12-year-old students with low educational and language performance from their own perspectives and those of their parents and teachers.

Method

The Strengths and Difficulties Questionnaire (Goodman, 1997) was given to 352 mainstream secondary school students who were underperforming academically and had poor language performance. Two hundred and twenty-five of their parents and 230 of their teachers also completed the questionnaire.

Results

Students with low educational attainment and poor language showed significantly greater SEBD than a normative sample as reported by themselves, their parents, and their teachers. Significant differences were found across informants, with students identifying more overall difficulties than parents or teachers.

Conclusion

Secondary school students with low academic and language performance are more vulnerable to experiencing SEBD compared to typically developing peers. The extent of their difficulties varied depending on the informant, emphasizing the importance of gaining views from multiple perspectives.
Improving the Clinical Evidence of Bone Graft Substitute Technology in Lumbar Spine Surgery
Authors: Hsu Wellington K. , Nickoli M. S. , Wang J. C. , Lieberman J. R. , An H. S. , Yoon S. T. , Youssef J. A. , Brodke D. S. , McCullough C. M.
Published: October 2012

Bone graft substitutes have been used routinely for spine fusion for decades, yet clinical evidence establishing comparative data remains sparse. With recent scrutiny paid to the outcomes, complications, and costs associated with osteobiologics, a need to improve available data guiding efficacious use exists. We review the currently available clinical literature, studying the outcomes of various biologics in posterolateral lumbar spine fusion, and establish the need for a multicenter, independent osteobiologics registry.
Nicotine Increases Osteoblast Activity of Induced Bone Marrow Stromal Cells in a Dose-Dependent Manner: An in vitro Cell Culture Experiment
Authors: Daffner Scott D. , Waugh Stacey , Norman Timothy L. , Mukherjee Nilay , France John C.
Published: October 2012

Previous studies by our group showed that nicotine delivered via a transdermal nicotine patch significantly enhanced posterior spinal fusion rates in rabbits. Nicotine transdermal patches provide a steady serum level; there may be a dose-dependent effect of nicotine on posterior spinal fusion. In an in vitro cell culture model of rabbit bone marrow–derived osteoblast-like cells, cells were exposed to different concentrations of nicotine (0, 20, 40, 80 ng/mL and 10, 100, 250 μg/mL). Wells were stained with an alkaline phosphatase (ALP) staining kit to determine ALP enzyme activity. Cells were stained with Von Kossa for mineralization. A two-way analysis of variance (ANOVA) using dose and time as variables showed significant differences among groups; post hoc analysis showed that the 100-μg/mL dose of nicotine significantly enhanced ALP activity over controls. A one-way ANOVA using dose as the variable showed that the 100- and 250-μg/mL doses had significantly greater mineralization than controls. Dose-response analysis revealed a statistically significant effect of nicotine dose on ALP activity and Von Kossa activity. The effects of nicotine on spinal fusion may be dose-dependent and due to stimulation of osteoblastic activity. Nicotine may not be responsible for the inhibited bone healing observed in smokers.
Surgical Outcome for Foot Drop in Lumbar Degenerative Disease
Authors: Bhargava Deepti , Sinha Priyank , Odak Saurabh , Tyagi Atul , Towns Gerry , Pal Debasish
Published: October 2012

Controversy exists regarding the timing and outcome of surgery for lumbar degenerative disease (LDD) associated with foot drop. In this work, we report the results of a retrospective observational study from our center. We had a sample size of 26 patients with a minimum follow-up of 6 months. Of the 26 patients, 88% improved, with complete recovery observed in 61%. Thus, our data support the view that there is good recovery from operative management of foot drop secondary to LDD. Adjusting for preoperative strength, preoperative duration of weakness was a significant predictor of extent of recovery (odds ratio = 0.93; 95% confidence interval 0.88 to 0.98; p = 0.019). The model explained 50% of the variance in outcome in this study.
Radiation Therapy without Surgery for Spinal Metastases: Clinical Outcome and Prognostic Factors Analysis for Pain Control
Authors: Matsumura Akira , Hoshi Manabu , Takami Masatsugu , Tashiro Takahiko , Nakamura Hiroaki
Published: October 2012

The purpose of radiation therapy (RT) for patients with spinal metastases is pain relief and control of paralysis. The aim of the present study was to assess pain relief using RT and to evaluate prognostic factors for pain control. We evaluated 97 consecutive patients, of mean age 62.7 years (range 28 to 86), with spinal metastases that had been treated by RT. We evaluated the effects of RT using pain level assessed using a drug grading scale based on the World Health Organization standards. The following potential prognostic factors for pain control of RT were evaluated using multivariate logistic regression analysis: age, gender, tumor type, performance status (PS), number of spinal metastases, and a history of chemotherapy. Among the 97 patients who underwent RT for pain relief, 68 patients (70.1%) presented with pain reduction. PS (odds ratio: 1.931; 95% confidence interval: 1.244 to 2.980) was revealed by multivariate logistic regression analysis to be the most important prognostic factor for pain control using RT. In conclusion, we found that RT was more effective for patients with spinal metastases while they maintained their PS.
Screw Placement Accuracy for Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery: A Study on 3-D Neuronavigation-Guided Surgery
Authors: Torres Jorge , James Andrew R. , Alimi Marjan , Tsiouris Apostolos John , Geannette Christian , Härtl Roger
Published: October 2012

Purpose

The aim of this study was to assess the impact of 3-D navigation for pedicle screw placement accuracy in minimally invasive transverse lumbar interbody fusion (MIS-TLIF).

Methods

A retrospective review of 52 patients who had MIS-TLIF assisted with 3D navigation is presented. Clinical outcomes were assessed with the Oswestry Disability Index (ODI), Visual Analog Scales (VAS), and MacNab scores. Radiographic outcomes were assessed using X-rays and thin-slice computed tomography.

Result

The mean age was 56.5 years, and 172 screws were implanted with 16 pedicle breaches (91.0% accuracy rate). Radiographic fusion rate at a mean follow-up of 15.6 months was 87.23%. No revision surgeries were required. The mean improvement in the VAS back pain, VAS leg pain, and ODI at 11.3 months follow-up was 4.3, 4.5, and 26.8 points, respectively. At last follow-up the mean postoperative disc height gain was 4.92 mm and the mean postoperative disc angle gain was 2.79 degrees. At L5–S1 level, there was a significant correlation between a greater disc space height gain and a lower VAS leg score.

Conclusion

Our data support that application of 3-D navigation in MIS-TLIF is associated with a high level of accuracy in the pedicle screw placement.
Histomorphometric Analysis of Experimental Disc Degeneration
Authors: Vialle Emiliano Neves , Vialle Luiz Roberto Gomes , de Oliveira Arruda André
Published: October 2012

Symptomatic disc degeneration is a complex pathological condition that involves a cascade of events and is not totally understood. In this context, animal models gain an important role, allowing for better understanding of the degenerative process and therapeutic interventions. There are several models with different methods of evaluation of experimental disc degeneration (EDD), including imaging, biochemical, genetics, and histological approaches, but no real gold standard has been set. The authors aim to evaluate EDD by means of automated morphometric analysis and to determine values for differentiating normal and degenerated discs by this method. The criteria mean and total cellular area, mean and total cytoplasm area, and total nuclear area of cells in the nucleus pulposus were able to differentiate the condition of degeneration (p < 0.05). In conclusion, by applying the histomorphometric analysis of EDD, the authors could present an objective measure of EDD changes within the nucleus pulposus, reducing the evaluator bias in future studies and presenting highly sensitive and specific criteria for EDD.
ICT for Development: Solutions Seeking Problems?
Authors: Chaudhuri Anindya
Published: October 2012

This paper investigates information and communication technologies for development (ICT4D) projects from around the world. It finds that computer and Internet promotion schemes usually fail despite active support, but mobile penetration in even the poorest countries is deepening organically. It argues that mobiles have emotional appeal because talking is a universal psycho-sociological propensity while the other two are principally utilitarian technologies that have to generate returns on investment. The search for killer apps is likely to be fruitless because technological adoption is conditional upon need and absorptive capacity. The paper raises questions about the continuing support for ICT4D among proponents.
Enterprise Systems Projects: The Role of Liminal Space in Enterprise Systems Implementation
Authors: Wagner Erica L , Newell Sue , Kay William
Published: October 2012

We investigate information systems (IS) projects as a liminal space ‘betwixt and between’ the status quo and the new environment, using a case study of the implementation of an enterprise system (ES). This liminal space provides a stabilizing platform whereupon the project team can develop new and potentially transformative IS. However, after a project team has completed its initial IS design for roll-out, this liminal space must be bridged to incorporate process-generated learning and new systems back into the organizational working environment. We demonstrate how this bridging involves negotiations that attempt to reconcile divergent perspectives by adopting a conciliatory or peacemaking attitude. As such, our analysis focuses on the IS project as a multi-phased process that includes the creation of a liminal space for the project team during development and on the negotiations that ensure the ES becomes a working IS in the post-implementation environment.
Effects of biochars generated from crop residues on chemical properties of acid soils from tropical and subtropical China
Authors: Yuan Jin-Hua , Xu Ren-Kou
Published: October 2012

The chemical compositions of biochars from ten crop residues generated at 350°C and their effects on chemical properties of acid soils from tropical and subtropical China were investigated. There was greater alkalinity and contents of base cations in the biochars from legume residues than from non-legume residues. Carbonates and organic anions of carboxyl and phenolic groups were the main forms of alkalis in the biochars, and their relative contributions to biochar alkalinity varied with crop residues. Incubation experiments indicated that biochar incorporation increased soil pH and soil exchangeable base cations and decreased soil exchangeable acidity. There were greater increases in soil pH and soil exchangeable base cations, and a greater decrease in soil exchangeable acidity, for biochars from legume than from non-legume residues. The biochars did not increase the cation exchange capacity (CEC) of soils with relatively high initial CEC but did increase the CEC of soils with relatively low initial CEC at an addition level of 1%. The incorporation of biochars from crop residues not only corrected soil acidity but also increased contents of potassium, magnesium, and calcium in these acid soils from tropical and subtropical regions and thus improved soil fertility.
The chromatin insulator CTCF and the emergence of metazoan diversity
Authors: Heger Peter , Marin Birger , Bartkuhn Marek , Schierenberg Einhard , Wiehe Thomas
Published: October 2012

The great majority of metazoans belong to bilaterian phyla. They diversified during a short interval in Earth’s history known as the Cambrian explosion, ∼540 million years ago. However, the genetic basis of these events is poorly understood. Here we argue that the vertebrate genome organizer CTCF (CCCTC-binding factor) played an important role for the evolution of bilaterian animals. We provide evidence that the CTCF protein and a genome-wide abundance of CTCF-specific binding motifs are unique to bilaterian phyla, but absent in other eukaryotes. We demonstrate that CTCF-binding sites within vertebrate and
Drosophila
Hox gene clusters have been maintained for several hundred million years, suggesting an ancient origin of the previously known interaction between Hox gene regulation and CTCF. In addition, a close correlation between the presence of CTCF and Hox gene clusters throughout the animal kingdom suggests conservation of the Hox-CTCF link across the Bilateria. On the basis of these findings, we propose the existence of a Hox-CTCF kernel as principal organizer of bilaterian body plans. Such a kernel could explain (
i
) the formation of Hox clusters in Bilateria, (
ii
) the diversity of bilaterian body plans, and (
iii
) the uniqueness and time of onset of the Cambrian explosion.
Genetic and environmental vulnerabilities in children with neurodevelopmental disorders
Authors: Karmiloff-Smith Annette , D’Souza Dean , Dekker Tessa M. , Van Herwegen Jo , Xu Fei , Rodic Maja , Ansari Daniel
Published: October 2012

One might expect that children with varying genetic mutations or children raised in low socioeconomic status environments would display different deficits. Although this expectation may hold for phenotypic outcomes in older children and adults, cross-syndrome comparisons in infancy reveal many common neural and sociocognitive deficits. The challenge is to track dynamic trajectories over developmental time rather than focus on end states like in adult neuropsychological studies. We contrast the developmental and adult approaches with examples from the cognitive and social domains, and we conclude that static models of adult brain lesions cannot be used to account for the dynamics of change in genetic and environmentally induced disorders in children.
Factors underlying variable DNA methylation in a human community cohort
Authors: Lam Lucia L. , Emberly Eldon , Fraser Hunter B. , Neumann Sarah M. , Chen Edith , Miller Gregory E. , Kobor Michael S.
Published: October 2012

Epigenetics is emerging as an attractive mechanism to explain the persistent genomic embedding of early-life experiences. Tightly linked to chromatin, which packages DNA into chromosomes, epigenetic marks primarily serve to regulate the activity of genes. DNA methylation is the most accessible and characterized component of the many chromatin marks that constitute the epigenome, making it an ideal target for epigenetic studies in human populations. Here, using peripheral blood mononuclear cells collected from a community-based cohort stratified for early-life socioeconomic status, we measured DNA methylation in the promoter regions of more than 14,000 human genes. Using this approach, we broadly assessed and characterized epigenetic variation, identified some of the factors that sculpt the epigenome, and determined its functional relation to gene expression. We found that the leukocyte composition of peripheral blood covaried with patterns of DNA methylation at many sites, as did demographic factors, such as sex, age, and ethnicity. Furthermore, psychosocial factors, such as perceived stress, and cortisol output were associated with DNA methylation, as was early-life socioeconomic status. Interestingly, we determined that DNA methylation was strongly correlated to the ex vivo inflammatory response of peripheral blood mononuclear cells to stimulation with microbial products that engage Toll-like receptors. In contrast, our work found limited effects of DNA methylation marks on the expression of associated genes across individuals, suggesting a more complex relationship than anticipated.
Brain on stress: How the social environment gets under the skin
Authors: McEwen Bruce S.
Published: October 2012

Stress is a state of the mind, involving both brain and body as well as their interactions; it differs among individuals and reflects not only major life events but also the conflicts and pressures of daily life that alter physiological systems to produce a chronic stress burden that, in turn, is a factor in the expression of disease. This burden reflects the impact of not only life experiences but also genetic variations and individual health behaviors such as diet, physical activity, sleep, and substance abuse; it also reflects stable epigenetic modifications in development that set lifelong patterns of physiological reactivity and behavior through biological embedding of early environments interacting with cumulative change from experiences over the lifespan. Hormones associated with the chronic stress burden protect the body in the short run and promote adaptation (allostasis), but in the long run, the burden of chronic stress causes changes in the brain and body that can lead to disease (allostatic load and overload). Brain circuits are plastic and remodeled by stress to change the balance between anxiety, mood control, memory, and decision making. Such changes may have adaptive value in particular contexts, but their persistence and lack of reversibility can be maladaptive. However, the capacity of brain plasticity to effects of stressful experiences in adult life has only begun to be explored along with the efficacy of top-down strategies for helping the brain change itself, sometimes aided by pharmaceutical agents and other treatments.
Leveraging the biology of adversity to address the roots of disparities in health and development
Authors: Shonkoff Jack P.
Published: October 2012

Extensive evidence that personal experiences and environmental exposures are embedded biologically (for better or for worse) and the cumulative knowledge of more than four decades of intervention research provide a promising opportunity to mobilize evolving scientific insights to catalyze a new era of more effective early childhood policy and practice. Drawing on emerging hypotheses about causal mechanisms that link early adversity with lifelong impairments in learning, behavior, and health, this paper proposes an enhanced theory of change to promote better outcomes for vulnerable, young children by strengthening caregiver and community capacities to reduce or mitigate the impacts of toxic stress, rather than simply providing developmental enrichment for the children and parenting education for their mothers.