bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Diacylglycerol Acyltransferase Inhibitors from Rosa centifolia Petals
Authors: Kondo Hidehiko , Hashizume Kohjiro , Shibuya Yusuke , Hase Tadashi , Murase Takatoshi
Published: May 2011

Diacylglycerol acyltransferase (DGAT) catalyzes the final step of triacylglycerol (TAG) synthesis, and is considered as a potential target to control hypertriglyceridemia or other metabolic disorders. In this study, we found that the extract of rose petals suppressed TAG synthesis in cultured cells, and that the extract showed DGAT inhibitory action in a dose‐dependent manner. Fractionation of the rose extract revealed that the DGAT inhibitory substances in the extract were ellagitannins; among them rugosin B, and D, and eusupinin A inhibited DGAT activity by 96, 82, and 84% respectively, at 10 μM. These substances did not inhibit the activities of other hepatic microsomal enzymes, glucose‐6‐phosphatase and HMG‐CoA reductase, or pancreatic lipase, suggesting that ellagitannins inhibit DGAT preferentially. In an oral fat load test using mice, postprandial plasma TAG increase was suppressed by rose extract; TAG levels 2 h after the fat load were significantly lower in mice administered a fat emulsion containing rose extract than in control mice (446.3 ± 33.1 vs 345.3 ± 25.0 mg/dL, control vs rose extract group; P < 0.05). These results suggest that rose ellagitannins or rose extract could be beneficial in controlling lipid metabolism and used to improve metabolic disorders.
Glycosidic Bond Cleavage is Not Required for Phytosteryl Glycoside‐Induced Reduction of Cholesterol Absorption in Mice
Authors: Lin Xiaobo , Ma Lina , Moreau Robert A. , Ostlund Richard E.
Published: May 2011

Phytosteryl glycosides occur in natural foods but little is known about their metabolism and bioactivity. Purified acylated steryl glycosides (ASG) were compared with phytosteryl esters (PSE) in mice. Animals on a phytosterol‐free diet received ASG or PSE by gavage in purified soybean oil along with tracers cholesterol‐d7 and sitostanol‐d4. In a three‐day fecal recovery study, ASG reduced cholesterol absorption efficiency by 45 ± 6% compared with 40 ± 6% observed with PSE. Four hours after gavage, plasma and liver cholesterol‐d7 levels were reduced 86% or more when ASG was present. Liver total phytosterols were unchanged after ASG administration but were significantly increased after PSE. After ASG treatment both ASG and deacylated steryl glycosides (SG) were found in the gut mucosa and lumen. ASG was quantitatively recovered from stool samples as SG. These results demonstrate that ASG reduces cholesterol absorption in mice as efficiently as PSE while having little systemic absorption itself. Cleavage of the glycosidic linkage is not required for biological activity of ASG. Phytosteryl glycosides should be included in measurements of bioactive phytosterols.
Role of salsolinol in the regulation of pituitary prolactin and peripheral dopamine release
Authors: Oláh Márk , Bodnár Ibolya , Daniel Galit , Tóth Béla E. , Vecsernyés Miklós , Nagy György M.
Published: May 2011

(R)‐Salsolinol (SAL), a dopamine (DA)‐related tetrahydroisoquinoline, has been found in extracts of the neuro‐intermediate lobes (NIL) of pituitary glands and in the median eminence of the hypothalamus obtained from intact male rats and from ovariectomized and lactating female rats. Moreover, analysis of SAL concentrations in NIL revealed parallel increases with plasma prolactin (PRL) in lactating rats exposed to a brief (10 min) suckling stimulus after 4‐h separation. SAL is sufficiently potent in vivo to account for the massive discharge of PRL that occurs after physiological stimuli (i.e. suckling). At the same time, it was without effect on the secretion of other pituitary hormones. It has been also shown that another isoquinoline derivative, 1‐methyldihydroisoquinoline (1MeDIQ), which is a structural analogue of SAL, can dose‐dependently inhibit the in‐vivo PRL‐releasing effect of SAL. Moreover, 1MeDIQ can inhibit the elevation of plasma PRL induced by physiological stimuli, for example suckling, or in different stressful situations also. 1MeDIQ also has a psycho‐stimulant action, which is fairly similar to the effect of amphetamine, i.e. it induces an increase in plasma catecholamine concentrations. It is clear from these data that this newly discovered endogenous compound could be involved in regulation of pituitary PRL secretion. It has also been observed that SAL is present in peripheral, sympathetically innervated organs, for example the atrium, spleen, liver, ovaries, vas deferens, and salivary gland. Furthermore, SAL treatment of rats results in dose‐dependent and time‐dependent depletion of the DA content of the organs listed above without having any effect on the concentration of norepinephrine. More importantly, this effect of SAL can be completely prevented by amphetamine and by 1MeDIQ pretreatment. It is clear there is a mutual interaction between SAL, 1MeDIQ, and amphetamine or alcohol, not only on PRL release; their interaction with catecholamine “synthesis/metabolism” of sympathetic nerve terminals is also obvious.
Germany’s Polycentric Metropolitan Regions in the World City Network
Authors: Münter Angelika
Published: May 2011

On a regional scale, two types of polycentricity can be observed. The first involves polycentric metropolitan regions that have evolved in the course of post-suburban development around a previously monocentric city, whereas the second type involves neighbouring metropolises evolving into a multi-core polycentric metropolitan region due to an increase in the functional interaction between each other. The German urban system is characterised by both types of polycentricity. In this paper I examine the role of these two types of polycentricity within the context of globalisation. I address the question of whether individual metropolitan cores and metropolitan cores and their associated post-suburban areas share the global functions of a metropolitan region or whether such functions are concentrated in a single city within the metropolitan region. To this end, I analyse the locations of leading global advanced producer service firms in Germany in their role as sub-nodes of the world city network. Finally, I discuss the empirical findings in the context of modelling the world city network.
Mediators of oligodendrocyte differentiation during remyelination
Authors: Patel Jigisha R. , Klein Robyn S.
Published: May 2011

Myelin, a dielectric sheath that wraps large axons in the central and peripheral nervous systems, is essential for proper conductance of axon potentials. In multiple sclerosis (MS), autoimmune‐mediated damage to myelin within the central nervous system (CNS) leads to progressive disability primarily due to limited endogenous repair of demyelination with associated axonal pathology. While treatments are available to limit demyelination, no treatments are available to promote myelin repair. Studies examining the molecular mechanisms that promote remyelination are therefore essential for identifying therapeutic targets to promote myelin repair and thereby limit disability in MS. Here, we present our current understanding of the critical extracellular and intracellular pathways that regulate the remyelinating capabilities of oligodendrocyte precursor cells (OPCs) within the adult CNS.
Ubiquitin family modifications and template switching
Authors: Branzei Dana
Published: May 2011

Homologous recombination plays an important role in the maintenance of genome integrity. Arrested forks and DNA lesions trigger strand annealing events, called template switching, which can provide for accurate damage bypass, but can also lead to chromosome rearrangements. Advances have been made in understanding the underlying mechanisms for these events and in elucidating the factors involved. Ubiquitin‐ and SUMO‐mediated modification pathways have emerged as key players in regulating damage‐induced template switching. Here I review the biological significance of template switching at the nexus of DNA replication and recombination, and the role of ubiquitin‐like modifications in mediating and controlling this process.
Preliminary study of a traditional Chinese medicine formula in systemic lupus erythematosus patients to taper steroid dose and prevent disease flare‐up
Authors: Liao Yen‐Nung , Liu Ching‐Shen , Tsai Tong‐Rong , Hung Yu‐Chiang , Chang Shun‐Jen , Lin Hong‐Long , Chen Ying‐Chou , Lai Han‐Ming , Yu Shan‐Fu , Chen Chung‐Jen
Published: May 2011

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease. Prolonged complete remission is rare. Most patients with SLE need long‐term treatment with glucocorticoid and immunomodulators. However, side effects because of the above medications are common. We evaluated the effect of adding‐on Dan‐Chi‐Liu‐Wei combination (DCLWC) on SLE patients with conventional therapy in tapering steroid and preventing disease flare‐up. This was a double‐blind and randomized controlled trial. Sixty‐six SLE patients were recruited into this study and 53 patients who fulfilled the 1997 revised criteria for the classification of SLE with an SLE disease activity index (SLEDAI) score of 2–12 and a steroid (measured with prednisolone) daily dose of less than 20 mg/d were enrolled. The patients were randomized into either an experimental or control group. We checked the urine analysis, hemogram, liver function, renal function, C3, C4, erythrocyte sedimentation rate, and anti‐dsDNA, evaluated the SLEDAI score, and recorded the steroid dose at 0 months, 3 months, and 6 months, respectively. After 6 months of study, the C4 and blood urea nitrogen level revealed a statistically significant difference in either group. There was a tendency toward a decreased SLEDAI score in the experimental group (p = 0.083) but not in the control group (p = 0.867). The steroid dose was not statistically significant in either group. Renal function and liver function revealed no statistically significant statistics changes in either group. Adding‐on DCLWC to conventional therapy for the treatment of SLE was safe and might have a borderline effect in decreasing disease activity, but it was not possible to taper the dosage of steroid after 6 months of clinical trial. Therefore, a long‐term follow‐up and a large‐scale study are necessary to confirm the effect of DCLWC.
Analysis of antidune migration direction
Authors: Núñez‐González Francisco , Martín‐Vide Juan P.
Published: May 2011

Antidunes are bed forms characteristic of upper regime unidirectional flows. Contrary to bed forms developed in lower regime flows, antidunes not only can propagate in the downstream direction but can propagate upstream or remain stationary. In this work we analyze the stable hydraulic conditions that determine each of the three antidune movement possibilities, and a new theory is developed for distinguishing the occurrence of each of these conditions. The theory is developed from an energy balance over a symmetrical antidune; for this, the Bernoulli equation is applied between the antidune crest and antidune trough, and the pressure head is corrected to account for the centrifugal forces generated by curvilinear flow. Manipulation of the fundamental equations produces an antidune mobility dimensionless number (Fa), dependent on the Froude number, the mean water depth, and the antidune wavelength. The critical value of the antidune mobility number (Fa = 1) corresponds to the stationary condition, while values higher and lower than the critical correspond to downstream and upstream propagation, respectively. Theory predicts that for a given Froude number, downstream‐migrating antidunes are formed for higher water depth–wavelength ratios than for upstream‐migrating antidunes. Likewise, by introducing a restriction for the maximum stationary wave height above antidunes, theory predicts that downstream‐migrating antidunes could attain steeper height–wavelength ratios than upstream‐migrating antidunes. Comparison with published experimental data in literature largely showed agreement between theory and experimental observations.
Testing fluvial erosion models using the transient response of bedrock rivers to tectonic forcing in the Apennines, Italy
Authors: Attal M. , Cowie P. A. , Whittaker A. C. , Hobley D. , Tucker G. E. , Roberts G. P.
Published: May 2011

The transient response of bedrock rivers to a drop in base level can be used to discriminate between competing fluvial erosion models. However, some recent studies of bedrock erosion conclude that transient river long profiles can be approximately characterized by a transport‐limited erosion model, while other authors suggest that a detachment‐limited model best explains their field data. The difference is thought to be due to the relative volume of sediment being fluxed through the fluvial system. Using a pragmatic approach, we address this debate by testing the ability of end‐member fluvial erosion models to reproduce the well‐documented evolution of three catchments in the central Apennines (Italy) which have been perturbed to various extents by an independently constrained increase in relative uplift rate. The transport‐limited model is unable to account for the catchments' response to the increase in uplift rate, consistent with the observed low rates of sediment supply to the channels. Instead, a detachment‐limited model with a threshold corresponding to the field‐derived median grain size of the sediment plus a slope‐dependent channel width satisfactorily reproduces the overall convex long profiles along the studied rivers. Importantly, we find that the prefactor in the hydraulic scaling relationship is uplift dependent, leading to landscapes responding faster the higher the uplift rate, consistent with field observations. We conclude that a slope‐dependent channel width and an entrainment/erosion threshold are necessary ingredients when modeling landscape evolution or mapping the distribution of fluvial erosion rates in areas where the rate of sediment supply to channels is low.
Exploring preserved fossil dinoflagellate and haptophyte DNA signatures to infer ecological and environmental changes during deposition of sapropel S1 in the eastern Mediterranean
Authors: Boere Arjan C. , Rijpstra W. Irene C. , de Lange Gert J. , Malinverno Elisa , Sinninghe Damsté Jaap S. , Coolen Marco J. L.
Published: May 2011

In this study we used a comparative multiproxy survey (fossil DNA, calcareous nannofossils, and lipid biomarkers) to test whether preserved genetic signatures provide an accurate view of haptophyte and dinoflagellate populations during deposition of the eastern Mediterranean sapropel S1 and the organic carbon‐depleted oxidized marls flanking the S1 and to see if we could identify important environmental indicator species that did not fossilize and escaped previous microscopic identification. The marls above and below the S1 contained low concentrations of lipid biomarkers diagnostic for dinoflagellates and haptophytes (i.e., dinosterol and long‐chain alkenones), but 500 base pair long ribosomal DNA fragments of these protists were below the detection limit. In contrast, dinoflagellate and haptophyte DNA could be recovered from the organic carbon‐rich S1, but the most abundant sequences did not represent species that were part of the nannofossil (this study) or previously described dinocyst composition. The oldest section of S1 (9.8 to ∼8 14C kyr B.P.) revealed a predominance of dinoflagellate phylotypes, which were previously only detected in anoxic Black Sea sediments. In the same section of the core, the most abundant haptophyte sequence showed highest similarity with uncultivated haptophytes that were previously shown to grow mixotrophically as predators of picocyanobacteria, an adaptation that promotes growth in oligotrophic marine waters. Sequences with highest similarities to clones found in marine surface waters predominated in the S1 after ∼8 14C kyr B.P. We discuss whether the shifts in haptophyte and dinoflagellate populations inferred from the preserved DNA reflect known environmental changes that occurred during the formation of sapropel S1.
Accounting for interannual variability: A comparison of options for water resources climate change impact assessments
Authors: Johnson Fiona , Sharma Ashish
Published: May 2011

Empirical scaling approaches for constructing rainfall scenarios from general circulation model (GCM) simulations are commonly used in water resources climate change impact assessments. However, these approaches have a number of limitations, not the least of which is that they cannot account for changes in variability or persistence at annual and longer time scales. Bias correction of GCM rainfall projections offers an attractive alternative to scaling methods as it has similar advantages to scaling in that it is computationally simple, can consider multiple GCM outputs, and can be easily applied to different regions or climatic regimes. In addition, it also allows for interannual variability to evolve according to the GCM simulations, which provides additional scenarios for risk assessments. This paper compares two scaling and four bias correction approaches for estimating changes in future rainfall over Australia and for a case study for water supply from the Warragamba catchment, located near Sydney, Australia. A validation of the various rainfall estimation procedures is conducted on the basis of the latter half of the observational rainfall record. It was found that the method leading to the lowest prediction errors varies depending on the rainfall statistic of interest. The flexibility of bias correction approaches in matching rainfall parameters at different frequencies is demonstrated. The results also indicate that for Australia, the scaling approaches lead to smaller estimates of uncertainty associated with changes to interannual variability for the period 2070–2099 compared to the bias correction approaches. These changes are also highlighted using the case study for the Warragamba Dam catchment.
Electrical conductivity as an indicator of iron reduction rates in abiotic and biotic systems
Authors: Regberg Aaron , Singha Kamini , Tien Ming , Picardal Flynn , Zheng Quanxing , Schieber Jurgen , Roden Eric , Brantley Susan L.
Published: May 2011

Although changes in bulk electrical conductivity (σb) in aquifers have been attributed to microbial activity, σb has never been used to infer biogeochemical reaction rates quantitatively. To explore the use of electrical conductivity to measure reaction rates, we conducted iron oxide reduction experiments of increasing biological complexity. To quantify reaction rates, we propose composite reactions that incorporate the stoichiometry of five different types of reactions: redox, acid‐base, sorption, dissolution/precipitation, and biosynthesis. In batch experiments and the early stages of a column experiment, such reaction stoichiometries inferred from a few chemical measurements allowed quantification of the Fe oxide reduction rate based on changes in electrical conductivity. The relationship between electrical conductivity and fluid chemistry did not hold during the latter stages of the column experiment when σb increased while fluid chemistry remained constant. Growth of an electrically conductive biofilm could possibly explain this late stage σb increase. The measured σb increase is consistent with a model proposed by analogy from percolation theory that attributes the increased conductivity to growth of biofilms with conductivity of ∼5.5 S m−1 in at least 3% of the column pore space. This work demonstrates that measurements of σb and flow rate, combined with a few direct chemical measurements, can be used to quantify biogeochemical reaction rates in controlled laboratory situations and may be able to detect the presence of biofilms. This approach may help in designing future field experiments to interpret biogeochemical reactivity from conductivity measurements.
Playing Cards with Thomas Kuhn: A Critical Reexamination of the Bruner and Postman (1949) Experiment
Authors: Horner John M. , Tung San K.
Published: May 2011

Two experiments replicated Bruner and Postman (1949) , on which Kuhn (1962 , 1970 ) relied in his argument that humans resist experience that is incongruous with their expectations—an argument essential to Kuhn's thesis of scientific revolutions. The first experiment measured reaction times for identifying playing card stimuli in three conditions: (a) where all the stimuli were standard playing cards, (b) where stimuli had color reversed (trick), or (c) which included both regular and trick card stimuli (mixed set). Participants were equally adept at identifying regular and trick stimuli in homogenous sets but took longer to identify the same stimuli in a mixed set. The second experiment, a conceptual replication of Bruner and Postman's original experiment, obtained recognition thresholds for regular and trick stimuli while measuring participants’ frustration. Participants responded similarly to procedural difficulties for both trick and regular stimuli. An analysis of participants’ responses shows that participants used systematic trial-and-error strategy to identify any ambiguous stimulus. These findings are inconsistent with an interpretation of resistance to incongruities.
An Exploration of Listener Variability in Intelligibility Judgments
Authors: McHenry Monica
Published: May 2011

Purpose

This study was designed to assess potential contributors to listener variability in judgments of intelligibility.

Method

A total of 228 unfamiliar everyday listeners judged speech samples from 3 individuals with dysarthria. Samples were the single-word phonetic contrast test, the Sentence Intelligibility Test, an unpredictable sentence intelligibility test, and conversational speech.

Results

Across speakers, significant variability was found for all samples except the phonetic contrast test. Across tasks, significant variability was found for all speakers. There were no significant differences in age, gender, or education between the highest and lowest scoring listeners on the phonetic contrast test.

Conclusions

These findings suggest that seemingly objective intelligibility tests are subject to a number of factors that affect scores.
Parent Perceptions of the Language Development of Toddlers With Developmental Delays Before and After Participation in Parent-Coached Language Interventions
Authors: Romski MaryAnn , Sevcik Rose A. , Adamson Lauren B. , Smith Ashlyn , Cheslock Melissa , Bakeman Roger
Published: May 2011

Purpose

This study examined parent perception of early communication development before and after participation in language intervention.

Method

Fifty-three parents of toddlers with developmental delays and fewer than 10 spoken words completed the Parent Perception of Language Development, an experimental measure, before and after the children were randomly assigned to a language intervention, 2 of which focused on augmented communication with a speech-generating device, and 1 of which focused exclusively on speech.

Results

After intervention, the parents' perceptions of success became more positive. Their perceptions of the severity of the child’s language difficulties decreased for the augmented interventions but increased for the spoken intervention. Child outcome correlated positively with success and negatively with difficulty, but only the correlation between number of spoken words and difficulty was statistically significant.

Conclusions

Augmented language intervention may not only help the child communicate but also have a positive impact on parent perception of language development.
Identifying Residual Speech Sound Disorders in Bilingual Children: A Japanese-English Case Study
Authors: Preston Jonathan L. , Seki Ayumi
Published: May 2011

Purpose

To describe (a) the assessment of residual speech sound disorders (SSDs) in bilinguals by distinguishing speech patterns associated with second language acquisition from patterns associated with misarticulations and (b) how assessment of domains such as speech motor control and phonological awareness can provide a more complete understanding of SSDs in bilinguals.

Method

A review of Japanese phonology is provided to offer a context for understanding the transfer of Japanese to English productions. A case study of an 11-year-old is presented, demonstrating parallel speech assessments in English and Japanese. Speech motor and phonological awareness tasks were conducted in both languages.

Results

Several patterns were observed in the participant’s English that could be plausibly explained by the influence of Japanese phonology. However, errors indicating a residual SSD were observed in both Japanese and English. A speech motor assessment suggested possible speech motor control problems, and phonological awareness was judged to be within the typical range of performance in both languages.

Conclusion

Understanding the phonological characteristics of the native language can help clinicians recognize speech patterns in the second language associated with transfer. Once these differences are understood, patterns associated with a residual SSD can be identified. Supplementing a relational speech analysis with measures of speech motor control and phonological awareness can provide a more comprehensive understanding of a client’s strengths and needs.
Disclosure of Membership in the Lesbian, Gay, Bisexual, and Transgender Community by Individuals With Communication Impairments: A Preliminary Web-Based Survey
Authors: Kelly Rebecca J. , Robinson Gregory C.
Published: May 2011

Purpose

The purpose of this preliminary investigation was to examine potential barriers to seeking services for communication impairments perceived by lesbian, gay, bisexual, and transgender (LGBT) people. Specifically, this clinical survey investigated (a) the rate and importance of disclosure of membership in the LGBT community by people with communication impairments to their clinicians and (b) the perception of bias of audiologists and speech-language pathologists against LGBT individuals with communication impairments.

Method

A total of 192 people identifying as LGBT with a communication impairment responded to a web-based survey. The survey contained questions about the respondents' demographic information, living situation, and experiences with clinical services for communication impairments. In addition, the survey contained open-ended comment sections.

Results

There were differences in the responses of LGBT people with speech-language impairments and those with hearing impairments. The majority of respondents did not disclose their membership in the LGBT community, although they felt it was important. Most respondents reported perceiving bias toward a heterosexual orientation from their clinicians.

Conclusions

Exploration of issues important to the LGBT community contributes to the growing emphasis on diversity and cultural competency in communication sciences and disorders. Specific clinical recommendations and directions for future research are discussed.
Experimental investigation of the trigger problem in magnetic reconnection
Authors: Katz Noam , Egedal Jan , Fox Will , Le Ari , Vrublevskis Arturs , Bonde Jeff
Published: May 2011

Magnetic reconnection releases magnetic energy not only in steady state, but also in time-dependent and often explosive events. Here, we investigate the trigger mechanism for this explosive release by using a toroidal experiment in the strong guide-field regime. We observe spontaneous reconnection events with exponentially growing reconnection rates, and we characterize the full 3D dynamics of these events using multiple internal probes. The reconnection is asymmetric: it begins at one toroidal location and propagates around in both directions. The spontaneous onset is facilitated by an interaction between the x-line current channel and a global mode, which appears in the electrostatic potential. It is this mode which breaks axisymmetry and enables a localized decrease in x-line current. We apply a simple model—which relies on ion polarization currents for current continuity—to reproduce the exponential growth and compute the growth rate. The result agrees well with the experimental growth rate.
On the application of electron cyclotron emission imaging to the validation of theoretical models of magnetohydrodynamic activity
Authors: Tobias B. J. , Boivin R. L. , Boom J. E. , Classen I. G. J. , Domier C. W. , Donné A. J. H. , Heidbrink W. W. , Luhmann N. C. , Munsat T. , Muscatello C. M. , Nazikian R. , Park H. K. , Spong D. A. , Turnbull A. D. , Van Zeeland M. A. , Yun G. S. ,   DIII-D Team
Published: May 2011

Two-dimensional (2D) imaging of electron temperature perturbations provides a powerful constraint for validating theoretical models describing magnetohydrodynamic plasma behavior. In observation of Alfvén wave induced temperature fluctuations, electron cyclotron emission imaging provides unambiguous determination of the 2D eigenmode structure. This has provided support for nonperturbative eigenmode solvers which predict symmetry breaking due to poloidal flows in the fast ion population. It is shown that for Alfvén eigenmodes, and in cases where convective flows or saturated perturbations lead to nonaxisymmetric equilibria, electron plasma displacements oriented parallel to a gradient in mean temperature are well defined. Furthermore, during highly dynamic behavior, such as the sawtooth crash, highly resolved 2D temperature behaviors yield valuable insight. In particular, addressing the role of adiabatic heating on time scales much shorter than the resistive diffusion time through the additional diagnosis of local electron density allows progress to be made toward a comprehensive understanding of fast reconnection in tokamak plasmas.
Nonlinear evolution of electromagnetic ion cyclotron waves
Authors: Silin I. , Sydora R. D. , Mann I. R. , Sauer K. , Mace R. L.
Published: May 2011

Hybrid Vlasov–Fourier modeling is used to investigate the nonlinear evolution of electromagnetic ion cyclotron (EMIC) waves driven by proton temperature anisotropy in plasmas with a population of He+ ions and a cold proton background. In the pure proton–electron plasma, most of the free energy is converted into high-amplitude waves and currents. In the nonlinear stage, within a few hundred proton gyroperiods after the saturation, the wave spectrum shifts toward lower wave numbers and frequencies, from ω∼0.6Ωp to below ω∼0.25Ωp. In the presence of even a small population of He+ ions almost all of the free energy is used in He+ heating. The wave activity in the saturated state moves from the linearly unstable upper branch to the linearly stable lower one. In the presence of a background of cold protons, the waves can propagate in the frequency stop-band. Our results demonstrate that linear stability theory cannot be used to estimate the characteristics of the expected saturated wave spectra in the terrestrial magnetosphere. Significantly, our nonlinear simulations produce wave spectra which are in close agreement with the EMIC waves observed in situ by satellites as well as by ground-based magnetometers positioned at the ends of the magnetic field lines.
Resonant drive and nonlinear suppression of gradient-driven instabilities via interaction with shear Alfvén waves
Authors: Auerbach D. W. , Carter T. A. , Vincena S. , Popovich P.
Published: May 2011

The nonlinear interaction of shear Alfvén waves and gradient-driven instabilities on pressure gradients in the Large Plasma Device (LAPD) [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at UCLA is explored. Nonlinear response at the beat frequency between two shear Alfvén waves is shown to resonantly drive unstable modes as well as otherwise damped modes. Resonantly driving the damped modes is shown to suppress the originally unstable mode, leaving only the beat-driven response with an overall reduction in fluctuation amplitude. A threshold is observed in the suppression behavior, requiring that the driven damped mode power be of order 10% of the power in the saturated unstable mode. The interaction is also observed to be dependent on the parallel wavenumber of the driven beat wave; efficient coupling and suppression is only observed for co-propagating beat waves with small parallel wavenumber, consistent with the parallel wavenumber of the gradient-driven modes.
Effect of nonaxisymmetric magnetic perturbations on divertor heat and particle flux profiles in National Spherical Torus Experiment
Authors: Ahn J-W. , Maingi R. , Canik J. M. , McLean A. G. , Lore J. D. , Park J.-K. , Soukhanovskii V. A. , Gray T. K. , Roquemore A. L.
Published: May 2011

Small, nonaxisymmetric magnetic perturbations generated by external coils have been found to break the axisymmetry of heat and particle flux deposition pattern in the divertor area in the National Spherical Torus Experiment (NSTX). This breaking by the applied 3-D field causes strike point splitting that is represented as local peaks and valleys in the divertor profiles. In case of n = 3 fields application, the broken toroidal symmetry of the divertor profile shows 120° of spatial periodicity while data for n = 1 fields provide a fully nonaxisymmetric heat and particle deposition. Field line tracing showed good agreement with the measured heat and particle flux profiles. Higher toroidal mode number (n = 3) of the applied perturbation produced more and finer striations in the divertor profiles than in the lower mode number (n = 1) case. Following the previous result of the intrinsic strike point splitting by the n = 3 error fields [Nucl. Fusion 50, 045010 (2010); J. Nucl. Mater. (2011), doi:10.1016/j.jnucmat.2011.01.115], result of the connection length profile from field line tracing identifies intrinsic error field as a possible source of the intrinsic splitting. In determining the strike point splitting pattern, q95 is found to play an important role; higher q95 produces finer striations and induces higher fraction of heat flux to flow through the split strike point channels. Higher pedestal electron collisionality also made the striations in the Dα profile more pronounced in the given range of collisionality variation. The radial location of local peaks in the profiles during the triggered edge localized modes (ELMs) by the applied n = 3 fields stays similar before and after the application. This shows that the heat flux from the triggered ELMs follows the mode number of the applied perturbation. The external magnetic perturbation can reattach detached divertor plasma, but this can be overcome by detaching the plasma with additional divertor gas puffing.
Three-dimensional effects on energetic particle confinement and stability
Authors: Spong D. A.
Published: May 2011

Energetic particle populations in magnetic confinement systems are sensitive to symmetry-breaking effects due to their low collisionality and long confined path lengths. Broken symmetry is present to some extent in all toroidal devices. As such effects preclude the existence of an ignorable coordinate, a fully three-dimensional analysis is necessary, beginning with the lowest order (equilibrium) magnetic fields. Three-dimensional techniques that have been extensively developed for stellarator configurations are readily adapted to other devices such as rippled tokamaks and helical states in reversed field pinches. This paper will describe the methods and present an overview of recent examples that use these techniques for the modeling of energetic particle confinement, Alfvén mode structure and fast ion instabilities.
Amplification of ion acoustic wave in an inhomogeneous plasma through nonlinear wave-particle interaction with drift wave turbulence
Authors: Deka P. N. , Borgohain A.
Published: May 2011

A study on the amplification of ion acoustic wave in an inhomogeneous plasma has been made on the basis of a nonlinear wave-particle interaction process called plasma maser effect. The drift wave instability, which is a universal phenomenon of an inhomogeneous confined plasma system, is found to be strongly in phase relation with thermal particles and may transfer its wave energy nonlinearly through a modulated field to ion acoustic wave. Considering a Maxwellian distribution function model for inhomogeneous plasmas under the standard local approximation, we have estimated the growth rate for ion acoustic wave, which is obtained by using the nonlinear dispersion relation. It has been found that amplification of ion acoustic wave is possible at the expense of drift wave turbulent energy. This result may be particularly important for stability of various drift modes in magnetically confined plasma as well as for transport of momentum and energy in such inhomogeneous systems.
A flowing plasma model to describe drift waves in a cylindrical helicon discharge
Authors: Chang L. , Hole M. J. , Corr C. S.
Published: May 2011

A two-fluid model developed originally to describe wave oscillations in the vacuum arc centrifuge, a cylindrical, rapidly rotating, low temperature, and confined plasma column, is applied to interpret plasma oscillations in a RF generated linear magnetized plasma [WOMBAT (waves on magnetized beams and turbulence)], with similar density and field strength. Compared to typical centrifuge plasmas, WOMBAT plasmas have slower normalized rotation frequency, lower temperature, and lower axial velocity. Despite these differences, the two-fluid model provides a consistent description of the WOMBAT plasma configuration and yields qualitative agreement between measured and predicted wave oscillation frequencies with axial field strength. In addition, the radial profile of the density perturbation predicted by this model is consistent with the data. Parameter scans show that the dispersion curve is sensitive to the axial field strength and the electron temperature, and the dependence of oscillation frequency with electron temperature matches the experiment. These results consolidate earlier claims that the density and floating potential oscillations are a resistive drift mode, driven by the density gradient. To our knowledge, this is the first detailed physics model of flowing plasmas in the diffusion region away from the RF source. Possible extensions to the model, including temperature nonuniformity and magnetic field oscillations, are also discussed.
One atmospheric pressure plasma jet with two modes at a frequency of several tens kHz
Authors: Li Xuechen , Jia Pengying , Yuan Ning , Fang Tongzhen , Wang Long
Published: May 2011

This paper reports an experimental study of a plasma jet by using optical measurement and spectroscopic method. The plasma jet, composed of an inner electrode with a sharpen end and an outer water-electrode, has a cross-field configuration. A cross-field mode of the plasma jet is realized when the applied voltage is low. However, a different mechanism of plasma plume generation is involved when the applied voltage is high enough, and a linear-field mode of the plasma jet can be realized. The two different modes of the plasma jet are compared by spectroscopic method and results show that electron energy in linear-filed mode is higher than that in cross-field mode.
Study of x-ray radiant characteristics and thermal radiation redistribution in CH foam filling cylindrical cavities
Authors: Shang Wanli , Zhu Tuo , Song Tianming , Zhang Wenhai , Zhao Yang , Xiong Gang , Zhang Jiyan , Yang Jiamin
Published: May 2011

Experiments are presented, which demonstrate the properties of x-ray radiation and redistribution of radiant thermal energy in high Z cylindrical cavities filled with low Z CH foam. Time integrated spectra records were obtained by a calibrated space-resolved transmission grating spectrometer. The x-ray radiation became weaker in intensity and was changed to a softer near-Planckian radiation light after a 1500 μm long transport in the foam filling cavity. The experimental redistribution of the radiant thermal energy was plotted and compared to the numerical results of a simplified model. Good agreements have been achieved.
Precision cosmic-ray data challenge a paradigm
Authors: Schwarzschild Bertram M.
Published: May 2011

It was long thought that almost all intragalactic cosmic rays originate in supernova remnants.
Calculations clarify the role of minerals’ electron spins in Earth’s mantle
Authors: Miller Johanna L.
Published: May 2011

Laboratory measurements of the spin states are indirect and prone to ambiguities.
Atoms in a BEC engineered to have spin–orbit coupling typical of electrons in a solid
Authors: Levi Barbara Goss
Published: May 2011

By mimicking certain electromagnetic effects, researchers can use ultracold atomic gases to simulate a wide range of many-body behavior.
New fiber lasers deliver pulses at tens of gigahertz
Authors: Wilson R. Mark
Published: May 2011

Ultrafast charge-carrier dynamics and broadband tunability make carbon nanotubes and graphene appealing materials for phase-locking cavity modes.
Safety reviews, not shutdowns, are ordered in the wake of Fukushima
Authors: Kramer David
Published: May 2011

The US, China, and France each have a considerable stake in the growth of nuclear power. But public opinion may have greater sway.
For some, helium-3 supply picture is brightening
Authors: Kramer David
Published: May 2011

R&D efforts are beginning to pay off in reduced demand for the scarce neutron-detection isotope. But there is little relief for those requiring it outside the US.
US planetary sciences to focus on smaller missions, research, and technology development
Authors: Feder Toni
Published: May 2011

Heeding community advice, NASA’s planetary science division seeks to scale back its flagship missions while retaining strong international partnerships.
Bags to slags: Recycling plastics to make steel
Authors: Feder Toni
Published: May 2011

A researcher in Australia seeks ways to use alternative resources.
The origin of the Hawaiian Volcano Observatory
Authors: Dvorak John
Published: May 2011

In 1912 Thomas Jaggar left MIT to start an observatory on the remote Kilauea volcano. The move was the culmination of a tortuous chain of events.
The universe in a cup of coffee
Authors: Wettlaufer John S.
Published: May 2011

Your morning java or tea is a rotating, cooling laboratory that reflects the physics of such large-scale phenomena as stellar dynamics and energy transport in Earth’s atmosphere and oceans.
1H NMR-based metabolomic observation of a two-phased toxic mode of action in Eisenia fetida after sub-lethal phenanthrene exposure
Authors: Lankadurai Brian P. , Wolfe David M. , Simpson André J. , Simpson Myrna J.
Published: May 2011

Environmental contextPhenanthrene is a persistent soil contaminant, whose toxic mode of action in earthworms has not been fully examined. We adopt a metabolomics approach, using 1H nuclear magnetic resonance (NMR) spectroscopy, to measure the response of earthworms to sub-lethal phenanthrene exposure. The results indicate that NMR-based metabolomics may be used to monitor responses to sub-lethal levels of contaminants and to delineate their toxic mode of action. Abstract1H NMR-based metabolomics was used to examine the response of the earthworm Eisenia fetida to sub-lethal phenanthrene exposure. E. fetida were exposed via contact tests to six sub-lethal (below the measured LC50 of 1.6 mg cm–2) concentrations of phenanthrene (0.8–0.025 mg cm–2) for 48 h. Multivariate statistical analysis of the 1H NMR spectra of earthworm tissue extracts revealed a two-phased mode of action (MOA). At exposures below 1/16th of the LC50, the MOA was characterised by a linear correlation between the metabolic response and exposure concentration. At exposures ≥1/16th of the LC50, the metabolic response to phenanthrene appeared to plateau, indicating a distinct change in the MOA. Further data analysis suggested that alanine, lysine, arginine, isoleucine, maltose, ATP and betaine may be potential indicators for sub-lethal phenanthrene exposure. Metabolite variation was also found to be proportional to the exposure concentration suggesting that NMR-based earthworm metabolomics is capable of elucidating concentration-dependent relationships in addition to elucidating the MOA of sub-lethal contaminant-exposure.
UV-induced photodegradation of oseltamivir (Tamiflu) in water
Authors: Tong Alfred Y. C. , Braund Rhiannon , Tan Eng W. , Tremblay Louis A. , Stringer Tristan , Trought Katherine , Peake Barrie M.
Published: May 2011

Environmental contextOseltamivir (Tamiflu) is widely used to prevent and treat influenza but conventional wastewater processes involving sedimentation and biotic oxidation do not appear to significantly remove it from sewage, leading to its discharge into the environment. A range of advanced oxidation processes (AOPs) involving photolysis of aqueous solutions of oseltamivir with UV alone, UV/H2O2 and UV/H2O2/FeII is demonstrated to lead to photodegradation of oseltamivir to products with no ecotoxicity observed. These AOPs may therefore offer potentially environmentally friendly sewage water treatment options. AbstractAqueous solutions of the antiviral drug oseltamivir phosphate (OSP, Tamiflu, (3R,4R,5S)-ethyl 4-acetamido-5-amino-3-(pentan-3-yloxy)cyclohex-1-enecarboxylate) were degraded using advanced oxidation processes (AOPs) involving photodegradation with UV alone, UV/H2O2 and UV/H2O2/FeII (photo-Fenton reaction). The photodecay of the parent OSP in all three cases followed first-order kinetics with respective rate constants of 0.21, 1.56 and 1.75 min–1 at 20°C in pH 7 phosphate-buffered Milli-Q water. The rate of UV/H2O2 photolysis in the presence of 2-methylpropan-2-ol was significantly slower with an approximate first-order rate constant of 0.13 min–1 suggesting the involvement of •OH in the degradation process. NMR spectroscopy, mass spectrometry and high-performance liquid chromatography (HPLC) with UV diode array detection were used to identify the crude photoproduct as the hydroxylated OSP derivative (3S,4R,5S)-ethyl 4-acetamido-5-amino-2-hydroxy-3-(pentan-3-yloxy)cyclohexanecarboxylate that occurs by an unknown mechanism. OSP and this crude photoproduct demonstrated no effect on the survival of Quinquelaophonte sp. over 96 h.
Reduced sulfur accumulation in salinised sediments
Authors: Whitworth Kerry L. , Baldwin Darren S.
Published: May 2011

Environmental contextThe accumulation of reduced sulfur compounds following salinisation is an emerging risk to inland waterways. Disturbance of these materials can lead to acidification, mobilisation of heavy metals and oxygen depletion. Knowledge of the rates of reduced sulfur accumulation in salinised waterways and the speciation of the reduced sulfur products is crucial for effective management of aquatic ecosystems.
AbstractThe accumulation of reduced sulfur species in the sediments of salinised inland waterways poses a serious environmental risk to many historically freshwater environments. Here the effects of salinity (and associated sulfate concentration), organic carbon load and temperature on reduced sulfur accumulation and speciation in closed microcosms containing sediments from a wetland that had not previously been salinised are examined. At conductivities of up to 10 000 µS cm–1, extant sediment carbon was sufficient to allow reduction of the entire sulfate load. Sulfate reduction was carbon limited at higher salinities. The rate of sulfate reduction approximately tripled with an increase in temperature from 20 to 30°C. Speciation studies showed that elemental sulfur and an unidentified sulfur species – probably reduced organic sulfur – were the dominant reduced sulfur species present during the early stages of sulfate reduction. By the end of the incubation period (226 days), reactive forms of S (elemental sulfur and acid-volatile sulfide) dominated. In the low conductivity treatments (0 and 1000 µS cm–1) reduced sulfur was approximately equally distributed between the two forms; acid volatile sulfide comprised ~75% of the reduced sulfur at higher salinities. Formation of less reactive di-sulfide minerals was inconsequential over the timescale of this experiment.