bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental deformation of olivine single crystals at lithospheric temperatures
Authors: Demouchy Sylvie , Schneider Stephen E. , Mackwell Stephen J. , Zimmerman Mark E. , Kohlstedt David L.
Published: February 2009

Rheological properties of mantle minerals and rocks at temperatures (T) appropriate to much of Earth's lithosphere have remained poorly constrained, even though past experimental studies on olivine single crystals and polycrystalline aggregates have quantified the high‐temperature creep mechanisms (T > 1200°C). Consequently, we have performed deformation experiments on crystals of San Carlos olivine at lower temperatures, from 900° to 1200°C, in triaxial compression along the [101]c direction. The experiments were carried out at a confining pressure of 300 MPa in a high‐resolution gas‐medium mechanical testing apparatus at differential stresses of 100 to 500 MPa. Several samples were deformed at constant displacement rate and others at constant load, in order to provide insight into possible effects of work‐hardening. Under the deformation conditions investigated, little evidence of work‐hardening was observed. The data follow a power‐law dependence on stress, as in previous high‐temperature deformation studies. The samples were, however, considerably weaker than predicted by the experimentally determined high‐temperature constitutive equation for olivine crystals of this orientation from the study of Bai et al. (1991). The mechanical behavior correlates instead with the weaker of the two mechanisms (flow laws) that contribute to the high‐temperature constitutive equation. Thus, our experiments demonstrate that published high‐temperature constitutive equations overestimate the strength of lithospheric mantle and that the transition to low‐temperature creep occurs at lower temperatures than previously inferred.
Drier Mediterranean soils due to greenhouse warming bring easterly winds over summertime central Europe
Authors: Haarsma Reindert J. , Selten Frank , Hurk Bart vd , Hazeleger Wilco , Wang Xueli
Published: February 2009

Western European summers become more continental in simulations for the 21st century. Anomalously large summer warming over the Mediterranean area in concert with drier soils and a reduced surface pressure can explain this change. The warming is enhanced due to soil moisture depletion which limits the cooling of the land surface by evaporation. A large‐scale Mediterranean heat low develops, bringing easterly winds over Central Europe. Statistical analysis for present‐day conditions indicates that the same mechanism operates on intra‐seasonal timescales; dry Mediterranean soils in June are correlated with high temperature and low surface pressure in July‐August. Idealized simulations confirm the relation between the surface warming of the Mediterranean area and the development of a heat low. The development of a heat low in response to dry soils induces a positive feedback: drier Mediterranean soils in summer bring easterly winds over Europe and increase the continental character of Western European summer climate.
Two dominant subseasonal variability modes of the eastern Pacific ITCZ
Authors: Jiang Xianan , Waliser Duane E.
Published: February 2009

Two subseasonal variability (SSV) modes over the eastern Pacific (EPAC) have been identified based on rainfall observations. The first SSV mode with a dominant period of 40 days has been documented in detail in previous studies. The second SSV mode associated with the EPAC intertropical convergence zone (ITCZ) rainfall, to the best of our knowledge, is documented for the first time, exhibiting a prevailing period of 18 days (hereafter, a 20‐d SSV mode). This 20‐d SSV mode is largely characterized by northward propagation. While its strongest signals are present over the EPAC, the impacts of this 20‐d SSV mode are also discerned over the North American Monsoon, the Gulf of Mexico, and Caribbean Sea. Analysis of the low‐frequency variability of these two SSV modes shows that they are anti‐correlated on the interannual time scales. The physics responsible for the origins of the two SSV modes over the EPAC are still elusive.
FAST observations of downward current regions: Effect of ionospheric constraints on parallel signatures
Authors: Hwang K.‐J. , Lynch K. A. , Newman D. L. , Carlson C. W.
Published: February 2009

Downward current region auroral crossings by the FAST (Fast Auroral Snapshot) spacecraft show that divergent electric fields which are perpendicular to the geomagnetic field () have two types of structures: those whose potential contours close below the spacecraft but above the ionosphere (U‐shaped), and those that are not completely closed but partially couple to the low‐altitude ionosphere (composite). Using FAST data from above 3000 km altitude, we investigate parallel signatures of particle motions in these downward current regions, focusing on the distinctions between U‐shaped and composite potential structures. We analyze probability density functions of electron velocity moments and ion energies, and power spectral density scaling laws of wave turbulence above the potential drop. Results indicate that U‐shaped potential structures show aspects of fully developed turbulence. Composite structures are often characterized by intermittent signatures, possibly because of lower ionospheric constraints. These results support a picture of an evolutionary process from composite to U‐shaped potential structures in downward current regions.
Observation of waves near lower hybrid frequency in the reconnection region with thin current sheet
Authors: Zhou M. , Deng X. H. , Li S. Y. , Pang Y. , Vaivads A. , Rème H. , Lucek E. , Fu S. , Lin X. , Yuan Z. G. , Wang J. F.
Published: February 2009

The role of waves and turbulence in the process of magnetic reconnection has been the subject of a great deal of studies and debates in the theoretical literature. Here we report the Cluster observations of electrostatic and electromagnetic waves near the lower hybrid frequency in the reconnection region with a thin current sheet. During the crossing of the separatrix with the reversal of plasma flow and Hall magnetic fields, strong electrostatic fluctuations near the lower hybrid frequency were observed, and the waves were polarized with a large angle to the ambient magnetic field. Strong electromagnetic fluctuations were observed in the center of the current sheet in the diffusion region. The dispersion properties of the electromagnetic wave are studied by using the interferometer method and are compared with the properties of lower hybrid drift instability. The role of the waves in reconnection is discussed.
Magnetic island formation between large‐scale flow vortices at an undulating postnoon magnetopause for northward interplanetary magnetic field
Authors: Eriksson S. , Hasegawa H. , Teh W.‐L. , Sonnerup B. U. Ö. , McFadden J. P. , Glassmeier K.‐H. , Le Contel O. , Angelopoulos V. , Cully C. M. , Larson D. E. , Ergun R. E. , Roux A. , Carlson C. W.
Published: February 2009

Time History of Events and Macroscale Interactions during Substorms multispacecraft observations are presented for a ∼2‐h‐long postnoon magnetopause event on 8 June 2007 that for the first time indicate that the trailing (sunward) edges of Kelvin‐Helmholtz (KH) waves are commonly related to small‐scale <0.56 RE magnetic islands or flux transfer events (FTE) during the growth phase of these surface waves. The FTEs typically show a characteristic bipolar BN structure with enhanced total pressure at their center. Most of the small‐scale FTEs are not related to any major plasma acceleration. TH‐A observations of one small FTE at a transition from the low‐latitude boundary layer (LLBL) into a magnetosheath plasma depletion layer were reconstructed using separate techniques that together confirm the presence of a magnetic island within the LLBL adjacent to the magnetopause. The island was associated with a small plasma vortex and both features appeared between two large‐scale (∼1 RE long and 2000 km wide) plasma vortices. We propose that the observed magnetic islands may have been generated from a time‐varying reconnection process in a low ion plasma beta (βi < 0.2) and low 8.3° field shear environment at the sunward edge of the growing KH waves where the local magnetopause current sheet may be compressed by the converging flow of the large‐scale plasma vortices as suggested by numerical simulations of the KH instability.
Crustal structure of the South American–Caribbean plate boundary at 67°W from controlled source seismic data
Authors: Magnani Maria Beatrice , Zelt Colin A. , Levander Alan , Schmitz Michael
Published: February 2009

We present the results of new seismic reflection and wide‐angle data across the SE Caribbean plate boundary. The 550 km long N–S profile crosses the structures involved in the active 55 Ma long continent‐arc oblique collision between the Caribbean (CAR) and the South American (SA) plate. From the north to the south these structures include the accretionary prism, the extinct volcanic arc (Leeward Antilles arc), the Tertiary Bonaire basin, the continental‐size dextral strike‐slip fault system (San Sebastián–El Pilar fault), the allochthonous exhumed terranes, and the authocthonous fold and thrust belt (Caribbean Mountain system) and foreland basin. The wide‐angle data show that these elements are characterized by different velocity structures and that they are separated by sharp lateral velocity variations. The Leeward Antilles arc exhibits a velocity structure similar to that of the Lesser Antilles active volcanic arc, indicating that the extinct arc has not been modified by the collision with the SA plate. The data show a ∼20 km change in crustal thickness across the San Sebastián fault, suggesting that the dextral strike‐slip fault is a crustal feature that likely continues in the mantle as a primary strand of the plate boundary between the South American and the Caribbean plates. South of the strike‐slip fault and beneath the exhumed eclogitic terranes, the data image a north dipping, high‐velocity (>6.5 km/s) anomaly in the upper crust (3–11 km), indicating that high‐pressure/low‐temperature rocks are the likely lithologies responsible for the high seismic velocities and suggesting that exhumation of these assemblages is enabled by the strike‐slip fault.
Validation of Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) v1.07 ozone at 9.6 μm in altitude range 15–70 km
Authors: Rong P. P. , Russell J. M. , Mlynczak M. G. , Remsberg E. E. , Marshall B. T. , Gordley L. L. , López‐Puertas M.
Published: February 2009

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument operating onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite since 2002 has provided day and nighttime measurements of ozone on a daily basis in the middle to upper atmosphere (15–100 km) using limb scanning in the 9.6‐μm band. The focus of this paper is on validation of v1.07 O3 in the stratosphere and mesosphere region below 70 km. SABER v1.07 O3 measurements have a precision of ∼1–2% in the stratosphere and ∼3–5% in the lower mesosphere. A SABER positive bias exists in all regions other than the lower stratosphere. The positive biases in the stratosphere are within ∼5–12% in most cases except in the equatorial to middle latitudes in the altitude range ∼30–50 km, where they reach ∼15–17% and exceed the combined systematic error by ∼5–6%. The comparisons in the lower mesosphere indicate that SABER O3 captures the diurnal variability very well. The best agreement of ∼5–7% occurs for daytime comparisons with solar occultation measurements in the lower mesosphere. As with most large satellite data sets, a small portion of the O3 profiles show unrealistically large values. The occurrences of these profiles were revealed using a probability approach, which enabled the identification of the time frames and spatial regions where these anomalies occur.
A model of dust in the Martian lower atmosphere
Authors: Davy Richard , Taylor Peter A. , Weng Wensong , Li P.‐Y.
Published: February 2009

A coupled boundary layer–Aeolian dust model of the Martian atmosphere is presented. This model was developed to determine how radiation (scattering, absorption, and emission) by dust affects the boundary layer and, in turn, how this affects the dust distribution in the atmosphere. This was achieved by coupling a planetary boundary layer (PBL) model with the 2007 dust model of P. A. Taylor et al. The principle motivation here is to determine whether it will be possible to use the lidar on board the Phoenix lander to detect the depth of the Martian boundary layer from the dust distribution. Runs were conducted for different dust profiles, roughness lengths, and geostrophic winds. These indicate that there should be a distinct horizon in dust concentration which will be detectable by the Phoenix lidar. The model is also applied to the 1977B dust storm optical data of Viking Lander 1, and our analysis indicates a significant improvement over previous 1‐D studies of dust storm decay.
Evaluating a hierarchy of snowmelt models at a watershed in the Canadian Prairies
Authors: Singh Purushottam Raj , Gan Thian Yew , Gobena Adam Kenea
Published: February 2009

Three semidistributed snowmelt models (SDSM) were developed and applied to the Paddle River Basin (PRB) in the Canadian Prairies: (1) A physics‐based, energy balance model (SDSM‐EBM) that considers vertical energy exchange processes in open and forested areas, and snowmelt processes that include liquid and ice phases separately; (2) a modified temperature index model (SDSM‐MTI) that uses both near surface soil temperature (Tg) and air temperature (Ta); and (3) a standard temperature index (SDSM‐TI) method using Ta only. Other than the “regulatory” effects of beaver dams that affected the validation results on simulated runoff, both SDSM‐MTI and SDSM‐EBM simulated reasonably accurate snowmelt runoff, snow water equivalent, and snow depth. For the PRB, where snowpack is shallow to moderately deep and winter is relatively severe, the advantage of using both Ta and Tg is partly attributed to Tg showing a stronger correlation with solar radiation than Ta during the spring snowmelt season and partly attributed to the onset of major snowmelt which usually happens when Tg approaches 0°C. After resetting model parameters so that SDSM‐MTI degenerated to SDSM‐TI (the effect of Tg is completely removed), the model performance worsened, even after recalibrating the melt factors using Ta alone. It seems that if reliable Tg data are available, they should be utilized to model the snowmelt processes in a prairie environment, particularly if the temperature‐index approach is adopted.
Aerosol particle dry deposition to canopy and forest floor measured by two‐layer eddy covariance system
Authors: Grönholm T. , Launiainen S. , Ahlm L. , Mårtensson E. M. , Kulmala M. , Vesala T. , Nilsson E. D.
Published: February 2009

We present, to our knowledge for the first time, results from subcanopy (forest trunk space) aerosol flux measurements with the eddy covariance (EC) technique. The measurements were performed at the SMEAR II measurement station located in a Scots pine forest in southern Finland during spring 2003 when the ground was snow covered and in situ biogenic particle formation took place almost every day. Spectral analysis showed that the EC method can be applied to estimate subcanopy aerosol fluxes and thereby ground deposition in a forest. By using the two‐layer EC measurements we were able to investigate the fraction of the total aerosol deposition taking place in the canopy and on the forest floor. We found that the ratio of subcanopy to above‐canopy flux is dependent on the strength of turbulence. When the friction velocity was low (u* < 0.25 m s−1), approximately 35% of the depositing particles penetrated the canopy and deposited on the ground. When u* increased, the fractional deposition on the forest floor decreased almost linearly, and in strongly turbulent conditions (u*>1.0 m s−1) the ground deposition contributed only around 10% to the total deposition. Thus, it seems that increased turbulence enhances the importance of the canopy for aerosol deposition and the relative importance of the forest floor to the total deposition diminishes.
Stable water isotopes in HadCM3: Isotopic signature of El Niño–Southern Oscillation and the tropical amount effect
Authors: Tindall J. C. , Valdes P. J. , Sime L. C.
Published: February 2009

Stable water isotopes have been added to the full hydrological cycle of the Hadley Centre Climate model (HadCM3) coupled atmosphere‐ocean GCM. Simulations of δ18O in precipitation and at the ocean surface compare well with observations for the present‐day climate. The model has been used to investigate the isotopic anomalies associated with ENSO; it is found that the anomalous δ18O in precipitation is correlated with the anomalous precipitation amount in accordance with the “amount effect.” The El Niño δ18O anomaly at the ocean surface is largest in coastal regions because of the mixing of ocean water and the more depleted runoff from the land surface. Coral δ18O anomalies were estimated, using an established empirical relationship, and generally reflect ocean surface δ18O anomalies in coastal regions and sea surface temperatures away from the coast. The spatial relationship between tropical precipitation and δ18O was investigated for the El Niño anomaly simulated by HadCM3. Weighting the El Niño precipitation anomaly by the precipitation amount at each grid box gave a large increase in the spatial correlation between tropical precipitation and δ18O. This improvement was most apparent over land points and between 10 and 20° of latitude.
Toward a Better Understanding of Climate of the Past Million Years: Quaternary Climate: From Pole to Pole—EPICA Open Science Conference; Venice, Italy, 10–13 November 2008
Authors: Barbante Carol , Fischer Hubertus , Masson‐Delmotte Valerie , Stocker Thomas , Waelbroeck Claire , Wolff Eric
Published: February 2009

The European Project for Ice Coring in Antarctica (EPICA) has provided unique paleoclimatic data and is now widely recognized and cited in hundreds of scientific papers. EPICA is a multinational project that has successfully drilled and analyzed two Antarctic ice cores to bedrock. The first one, at Dome C (75°06′S, 123°21′E, 3233 meters above sea level, 3259.7‐meter core length), has yielded a complete stratigraphically ordered sequence covering the past 800,000 years, almost doubling the length of previous Antarctic records (Vostok). The exceptional similarity of the Antarctic temperature and carbon dioxide (CO2) records highlights the likely role of the Southern Ocean in the carbon cycle, while other trace gas and chemical profiles show the close coupling between different aspects of the Earth system. The second EPICA core, in Dronning Maud Land (75°00′S, 00°04′E, 2892 meters above sea level, 2774.2‐meter core length), has provided a very high resolution record of a complete glacial cycle in the Atlantic sector, confirming theoretical predictions regarding the coupling of the two hemispheres during millennial‐scale climate changes. In this ice core, Antarctic counterparts were found to each of the rapid Dansgaard‐Oeschger climate change events prominent in Greenland and other Northern Hemisphere records of the glacial period; from Dome C data it appears that such events may have occurred in each previous glacial period.
Nucleolar targeting: the hub of the matter
Authors: Emmott Edward , Hiscox Julian A
Published: February 2009

The nucleolus is a dynamic structure that has roles in various processes, from ribosome biogenesis to regulation of the cell cycle and the cellular stress response. Such functions are frequently mediated by the sequestration or release of nucleolar proteins. Our understanding of protein targeting to the nucleolus is much less complete than our knowledge of membrane‐spanning translocation systems—such as those involved in nuclear targeting—and the experimental evidence reveals that few parallels exist with these better‐characterized systems. Here, we discuss the current understanding of nucleolar targeting, explore the types of sequence that control the localization of a protein to the nucleolus, and speculate that certain subsets of nucleolar proteins might act as hub proteins that are able to bind to multiple protein targets. In parallel to other subnuclear structures, such as PML bodies, the proteins that are involved in the formation and maintenance of the nucleolus are inexorably linked to nucleolar trafficking.
Control of histone methylation and genome stability by PTIP
Authors: Muñoz Ivan M , Rouse John
Published: February 2009

PTIP regulates gene transcription by controlling the methylation of histone H3, and also has important roles in cellular responses to DNA damage or to perturbed DNA replication. The available data suggest that the functions of PTIP in transcription and preserving genome stability might be independent and mediated by functionally distinct cellular pools of PTIP. Although considerable progress has been made in understanding how PTIP influences transcription, a coherent picture of how it protects cells from DNA damage at the molecular level has yet to emerge. Here, we describe recent progress made in understanding the cellular roles of PTIP and the relevance of PTIP‐interacting proteins, as well as the questions that have yet to be answered.
Representation of Sounds in Auditory Cortex of Awake Rats (Dissertation)
Authors: Hromádka Tomáš
Published: February 2009

This thesis is divided into six chapters (following Introduction). Each chapter was intended to be self-contained, so they do not have to be read in the order they are presented. Second chapter (Sec. 2) contains a detailed description of experimental techniques: surgery, recording, and training techniques we used in awake head-fixed rats. We have also included a detailed description of all sets of stimuli we used to probe neurons, analytical methods used to analyze data, and description of computational models used in other parts of the thesis.Third chapter (Sec. 3) focuses on description of single-neuron responses in primary auditory cortex of awake head-fixed rats. The primary emphasis of this part is on the sparse representation of various auditory stimuli we used to probe neurons, and the heterogeneity of responses of single neurons. To characterize population responses to sound in the auditory cortex we asked the question "What is the typical response to acoustic stimuli?" instead of what is usually asked "What is the stimulus that evokes a response?" We found that the population response was sparse, with many unresponsive neurons. In addition, the responsive neurons showed a great variety of responses. This heterogeneity of neuronal responses ("response zoo," courtesy of Anthony M. Zádor) was, however, surprisingly well characterized by lognormal distribution of firing rates. The observation that firing rates in awake auditory cortex were lognormally distributed was even more interesting given the observation of lognormal distribution of synaptic weights in the cerebral cortex.The fourth chapter (Sec. 4) focuses on mechanisms which could give rise to lognormal distribution of firing rates, as well as synaptic weights. We proposed specific types of correlations among synaptic connections, and formulated a multiplicative learning rule which led to the observed distributions. We were also able to characterize intracellular activity of neurons in awake auditory cortex. The fifth chapter (Sec. 5) contains analysis of so-called up and down states in awake auditory cortex. We show that up and down states—the "signature" subthreshold dynamics so often described in various cortical areas of anesthetized animals—were rare in the primary auditory cortex of awake rats, instead, subthreshold dynamics was consisted of brief, infrequent fluctuations of membrane potential.The experiments described and analyzed in chapters 2—-4 were conducted in naïve awake rats. As behavior or attention can influence neuronal activity even in primary sensory areas, we developed a setup for head-fixed behavior. In the sixth chapter (Sec. 6) we describe the sound discrimination task we have used to study behavior in head-fixed rats. We present a comparison of basic behavioral parameters between restrained and unrestrained rats, as well as evidence of nonauditory modulations of single neuron activity in auditory cortex.
Identification of dimer interactions required for the catalytic activity of the TRPM7 alpha-kinase domain
Authors: Crawley Scott W. , Côté Graham P.
Published: February 2009

TRPM7 (transient receptor potential melastatin) combines an ion channel domain with a C-terminal protein kinase domain that belongs to the atypical alpha-kinase family. The TRPM7 alpha-kinase domain assembles into a dimer through the exchange of an N-terminal segment that extends from residue 1551 to residue 1577 [Yamaguchi, Matsushita, Nairn and Kuriyan (2001) Mol. Cell 7, 1047–1057]. Here, we show, by analysis of truncation mutants, that residues 1553–1562 of the N-terminus are essential for kinase activity but not dimer formation. Within this ‘activation sequence’, site-directed mutagenesis identified Tyr-1553 and Arg-1558 as residues critical for activity. Examination of the TRPM7 kinase domain structure suggests that the activation sequence interacts with the other subunit to help position a catalytic loop that contains the invariant Asp-1765 residue. Residues 1563–1570 of the N-terminal segment are critical for dimer assembly. Mutation of Leu-1564, Ile-1568 or Phe-1570 to alanine abolished both kinase activity and dimer formation. The activity of a monomeric TRPM7 kinase domain lacking the entire N-terminal segment was rescued by a GST (glutathione transferase) fusion protein containing residues 1548–1576 of TRPM7, showing that all interactions essential for activity are provided by the N-terminal segment. Activity was also restored by GST fused to the N-terminal segment of TRPM6 (residues 1711–1740), demonstrating the feasibility of forming functional TRPM6–TRPM7 alpha-kinase domain heterodimers. It is proposed that covalent modifications or binding interactions that alter the conformation of the N-terminal exchanged segment may provide a means to regulate TRPM7 kinase activity.
The regulation of intestinal mucin MUC2 expression by short-chain fatty acids: implications for epithelial protection
Authors: Burger-van Paassen Nanda , Vincent Audrey , Puiman Patrycja J. , van der Sluis Maria , Bouma Janneke , Boehm Günther , van Goudoever Johannes B. , van Seuningen Isabelle , Renes Ingrid B.
Published: February 2009

SCFAs (short-chain fatty acids), fermentation products of bacteria, influence epithelial-specific gene expression. We hypothesize that SCFAs affect goblet-cell-specific mucin MUC2 expression and thereby alter epithelial protection. In the present study, our aim was to investigate the mechanisms that regulate butyrate-mediated effects on MUC2 synthesis. Human goblet cell-like LS174T cells were treated with SCFAs, after which MUC2 mRNA levels and stability, and MUC2 protein expression were analysed. SCFA-responsive regions and cis-elements within the MUC2 promoter were identified by transfection and gel-shift assays. The effects of butyrate on histone H3/H4 status at the MUC2 promoter were established by chromatin immunoprecipitation. Butyrate (at 1 mM), as well as propionate, induced an increase in MUC2 mRNA levels. MUC2 mRNA levels returned to basal levels after incubation with 5–15 mM butyrate. Interestingly, this decrease was not due to loss of RNA stability. In contrast, at concentrations of 5–15 mM propionate, MUC2 mRNA levels remained increased. Promoter-regulation studies revealed an active butyrate-responsive region at −947/−371 within the MUC2 promoter. In this region we identified an active AP1 (c-Fos/c-Jun) cis-element at −818/−808 that mediates butyrate-induced activation of the promoter. Finally, MUC2 regulation by butyrate at 10–15 mM was associated with increased acetylation of histone H3 and H4 and methylation of H3 at the MUC2 promoter. In conclusion, 1 mM butyrate and 1–15 mM propionate increase MUC2 expression. The effects of butyrate on MUC2 mRNA are mediated via AP-1 and acetylation/methylation of histones at the MUC2 promoter.
FKBP12.6 binding of ryanodine receptors carrying mutations associated with arrhythmogenic cardiac disease
Authors: Zissimopoulos Spyros , Thomas N. Lowri , Jamaluddin Wan W. , Lai F. Anthony
Published: February 2009

In the present paper we show that distinct human RyR2 (ryanodine receptor type 2) inherited mutations expressed in mammalian cells exhibit either unaltered or increased FKBP12.6 (12.6 kDa FK506-binding protein) binding compared with the wild-type. Oxidizing conditions result in decreased FKBP12.6 binding, but to the same extent as for the wild-type. Our findings suggest that FKBP12.6 regulation of RyR2 is unlikely to be the primary defect in inherited arrhythmogenic cardiac disease.
Low dose simvastatin induces compositional, structural and dynamic changes in rat skeletal extensor digitorum longus muscle tissue
Authors: Ozek Simsek Nihal , Sara Yildirim , Onur Rustu , Severcan Feride
Published: February 2009

Statins are commonly used drugs in the treatment of hypercholesterolaemia. There are many adverse effects of statins on skeletal muscle, but the underlying mechanisms remain unclear. In the present study, the effects of low dose (20 mg/kg) simvastatin, a lipophilic statin, on rat EDL muscle (extensor digitorum longus muscle) were investigated at the molecular level using FTIR (Fourier-transform infrared) spectroscopy. FTIR spectroscopy allows us rapid and sensitive determination of functional groups belonging to proteins, lipids, carbohydrates and nucleic acids simultaneously. The results revealed that simvastatin treatment induces a significant decrease in lipid, nucleic acid, protein and glycogen content. A significant increase in the lipid/protein and nucleic acid/protein ratios was also obtained with simvastatin treatment. Furthermore, an increase in lipid order and membrane fluidity was detected. A decrease in the bandwidth of the amide I band and shifting of the position of this band to higher frequency values in treated muscle indicates structural changes in proteins. Detailed secondary structure analysis of the amide I band revealed a significant increase in antiparallel and aggregated β-sheet, random coil structure and a significant decrease in β-sheet structure, which indicates protein denaturation.
The highly related LIM factors, LMO1, LMO3 and LMO4, play different roles in the regulation of the pituitary glycoprotein hormone α-subunit (αGSU) gene
Authors: Susa Takao , Ishikawa Akio , Cai Li-yi , Kato Takako , Matsumoto Kaori , Kitahara Kousuke , Kurokawa Rei , Ono Tetsuo , Kato Yukio
Published: February 2009

LMO1, LMO3 and LMO4 were cloned from the adult porcine pituitary cDNA library. Amino acid sequences of porcine LMO1, LMO3 and LMO4 were highly conserved among mammalian species. Transfection assay of the pituitary-derived cell line LβT2 was carried out using the pituitary αGSU (glycoprotein hormone α-subunit) promoter (−1059/+12 b) fused to pSEAP2-Basic vector as a reporter gene. The results demonstrated that, whereas LMO4 showed no apparent effect, αGSU promoter activity was markedly repressed by LMO1 but activated by LMO3, indicating the different roles of the three highly homologous proteins, LMO1, LMO3 and LMO4. Knockdown assay by LMO siRNAs (small interfering RNAs) confirmed the above results for LMO1 and LMO3, whereas that by LMO4 siRNA increased the expression, indicating different modes of action. RT–PCR (reverse transcription–PCR) for total RNAs of several cell lines showed that LMO1 and LMO4 mRNAs were present ubiquitously in all cell lines, except for LMO1 in L929 cells. In contrast, LMO3 mRNA was abundant only in LβT4 and GH3 cells with only small amounts in LβT2 and MtT/S cells, indicating the cell-type-specific function of this protein. Real-time analyses of porcine pituitary ontogeny revealed that the three LMO genes are expressed during the fetal period and decline immediately afterwards, followed by a remarkably low level of LMO3 and LMO4 after birth. RT–PCR of the porcine tissues examined showed ubiquitous expression of LMO4, whereas LMO1 and LMO3 are expressed tissue specifically. Thus the present study demonstrated that three highly related LIM cofactors, LMO1, LMO3 and LMO4, have different effects on αGSU gene expression in the pituitary glands.
Thermal stability of Pd/Pt/Au Ohmic contacts to InAlSb/InAs heterostructures for high electron mobility transistors
Authors: Dormaier R. , Zhang Q. , Liu B. , Chou Y. C. , Lange M. D. , Yang J. M. , Oki A. K. , Mohney S. E.
Published: February 2009

We report the thermal stability of Pd/Pt/Au Ohmic contacts to InAlSb/InAs high electron mobility transistors. An initial drop in contact resistance correlates with consumption of the InAs electron channel through reaction of both Pd and Pt with the semiconductor heterostructure during a 3 h 175 °C anneal, as determined using transmission electron microscopy. Voids form in the unreacted Pt layer after samples are aged for 1 week at 175 °C, and they grow larger when the samples are aged for 1 week at 200 °C. The contact resistance increases by more than a factor of 2 after samples are aged for 1 week at 225 °C. We discuss the degradation of the contact resistance in light of the interfacial reactions that occur during aging.
Tunable coupling in CrO2 via RuO2 layers
Authors: Sims H. , Butler W. H.
Published: February 2009

Theoretical calculations of the magnetic structure of CrO2–RuO2 interfaces and multilayer structures are presented. The antiferromagnetic coupling between Ru ions and neighboring Cr ions in such interfaces is explored both for contiguous layers of CrO2 and RuO2 and for Cr layers separated by RuO2 spacers. The Fermi surface of the RuO2 spacer is calculated and kF100 is utilized to determine the oscillatory behavior of the interlayer exchange coupling as described by Bruno [Phys. Rev. B 52, 411 (1995)]. The first-principles calculations are found to be qualitatively consistent with the Bruno theory, which suggests that CrO2–RuO2 layered structures could be designed to give the desired magnetic ordering between CrO2 layers given sufficient control over the composition and roughness of the deposited material.
Microwave generation of tilted-polarizer spin torque oscillator
Authors: Zhou Yan , Zha C. L. , Bonetti S. , Persson J. , Åkerman Johan
Published: February 2009

Microwave frequency generation in a spin torque oscillator (STO) with a tilted fixed layer magnetization is studied using numerical simulation of the Landau–Lifshitz–Gilbert–Slonczewski equation. The dependence of the STO free layer precession frequency on drive current is determined as a function of fixed layer tilt angle. We find that zero-field STO operation is possible for almost all tilt angles, which allow for great freedom in choosing the detailed layer structure of the STO.
Effects of stimulus parameters and tissue inhomogeneity on nerve excitation processes in magnetic stimulation of the brain: A simulation study
Authors: Hyodo Akira , Hayami Takehito , Tsuyama Seichi , Iramina Keiji , Ueno Shoogo
Published: February 2009

In this study, we used a computer simulation to investigate the nerve excitation processes of the nerve axon in an inhomogeneous volume conductor in magnetic stimulation. We assumed that the nerve axon was located in an inhomogeneous conducting medium with two regions having different conductivities that simulate different tissue types. The distribution of induced electric fields was calculated with the finite element method. The nerve fiber was modeled after equivalent electrical circuits having active nodes of Ranvier. We observed the excitation threshold when the coil current waveforms and direction are changed with varying the electrical properties of the tissue. The simulation results show that the threshold is lower when biphasic waveforms are used and that the optimal current direction depends on tissue conductivity. The results also suggest that the nerve is excited even when the coil current flow is perpendicular to the axon in inhomogeneous conducting media. The results in this study give useful information to explain the experimental results in magnetic stimulation of the brain.
On spectral properties of the resonances for selected potential scattering systems
Authors: Baumgärtel Hellmut , Kaldass Hani , Komy Soliman
Published: February 2009

The resonances (poles of the scattering matrix) of quantum mechanical scattering by central-symmetric potentials with compact support and zero angular momentum are spectrally characterized directly in terms of the Hamiltonian by a (generalized) eigenvalue problem distinguished by an additional condition (called boundary condition). The connection between the (generalized) eigenspace of a resonance and corresponding Gamov vectors is pointed out. A condition is presented such that a relation between special transition probabilities and infinite sums of residual terms for all complex-conjugated pairs of resonances can be proved. In the case of the square well potential the condition is satisfied.
Thermomagnetic properties of the Finland trityl radical
Authors: Cage Brant , McNeely James Halley , Russek Stephen E. , Halpern Howard J.
Published: February 2009

The Finland trityl paramagnet is characterized by magnetic susceptibility and a new form of quantitative electron paramagnetic resonance (EPR) that utilizes a superconducting quantum interference device (SQUID) as a detection method. This radical is of interest due to its use as a dynamic nuclear polarization agent as well as a potential magnetic refrigerant and quantum computing bit. The SQUID-EPR data show that the EPR linewidth of a concentrated trityl powder decreases dramatically from 4.4 to 1.4 mT as the temperature is increased from 1.8 to 10 K. The quantitative nature of SQUID-EPR is used to thermodynamically quantify the EPR energy transfer times and saturated fractions. At 95 GHz and 1.8 K, only 40% of the spins are in resonance at the onset of saturation. Conventional dc magnetic susceptibility over 1.8–150 K indicates an S=1/2 Curie–Weiss relationship with little long range interaction. Magnetization versus applied field at 1.8 and 4 K fits a Brillouin function with >80% electronic polarization at a normalized field of gμBμ0H/kT≈3. These results provide information required for theoretical modeling and engineering of the trityl radical for a wide range of applications.
The stabilizing effect of flow shear on m/n=3/2 magnetic island width in DIII-D
Authors: La Haye R. J. , Buttery R. J.
Published: February 2009

It is found that flow shear has a stabilizing effect on m/n=3/2 neoclassical tearing mode islands through a more negative classical tearing stability index Δ′ in the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak. The heating neutral beams are mixed between co- and counter-directions to vary the torque on the plasma and thus the plasma flow (rotation) and flow shear. This is done “shot to shot” in the presence of a saturated m/n=3/2 neoclassical tearing mode (NTM) while slowly raising the plasma beta up to the limit of the onset of an m/n=2/1 mode. A heuristic model for the stabilizing effect of flow shear on Δ′ is shown to explain how flow shear acts to reduce NTM island size and obviate the effect of higher beta and concomitant destabilizing helically perturbed bootstrap current.
Global solutions to one-dimensional compressible Navier–Stokes–Poisson equations with density-dependent viscosity
Authors: Ding Shijin , Wen Huanyao , Yao Lei , Zhu Changjiang
Published: February 2009

In this paper, we prove the global existence of weak solutions to one-dimensional compressible isentropic Navier–Stokes–Poisson equations with density-dependent viscosity and free boundaries. The initial density ρ0∊W1,2n is bounded below by a positive constant, and the initial velocity u0∊L2n. In contrast to Jiang et al. [“Global weak solutions to 1D compressible isentropic Navier-Stokes equations with density-dependent viscosity,” Methods Appl. Anal. 12, 239 (2005)], the Sobolev exponent n is less in this paper, and the viscosity coefficient μ=μ(ρ) is a general function of ρ including the cases μ(ρ)=c0ρθ (0<θ<1) and μ(ρ)=c0, where c0 is a positive constant.
Principle, calibration, and application of the in situ alkali chloride monitor
Authors: Forsberg Christer , Broström Markus , Backman Rainer , Edvardsson Elin , Badiei Shahriar , Berg Magnus , Kassman Håkan
Published: February 2009

The extended use of biomass for heat and power production has caused increased operational problems with fouling and high-temperature corrosion in boilers. These problems are mainly related to the presence of alkali chlorides (KCl and NaCl) at high concentrations in the flue gas. The in situ alkali chloride monitor (IACM) was developed by Vattenfall Research and Development AB for measuring the alkali chloride concentration in hot flue gases (≲650 °C). The measurement technique is based on molecular differential absorption spectroscopy in the UV range. Simultaneous measurement of SO2 concentration is also possible. The measuring range is 1–50 ppm for the sum of KCl and NaCl concentrations and 4–750 ppm for SO2. This paper describes the principle of the IACM as well as its calibration. Furthermore, an example of its application in an industrial boiler is given.
Applied digital signal processing systems for vortex flowmeter with digital signal processing
Authors: Xu Ke-Jun , Zhu Zhi-Hai , Zhou Yang , Wang Xiao-Fen , Liu San-Shan , Huang Yun-Zhi , Chen Zhi-Yuan
Published: February 2009

The spectral analysis is combined with digital filter to process the vortex sensor signal for reducing the effect of disturbance at low frequency from pipe vibrations and increasing the turndown ratio. Using digital signal processing chip, two kinds of digital signal processing systems are developed to implement these algorithms. One is an integrative system, and the other is a separated system. A limiting amplifier is designed in the input analog condition circuit to adapt large amplitude variation of sensor signal. Some technique measures are taken to improve the accuracy of the output pulse, speed up the response time of the meter, and reduce the fluctuation of the output signal. The experimental results demonstrate the validity of the digital signal processing systems.
Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma
Authors: Yatsuka Eiichi , Kinjo Kiyotake , Morikawa Junji , Ogawa Yuichi
Published: February 2009

To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45GHz, 2.5kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10W) separate frequency (1–2.1GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic.
Temporal changes in fish abundance in response to hydrological variability in a dryland floodplain river
Authors: Balcombe Stephen R. , Arthington Angela H.
Published: February 2009

Riverine fish living in unpredictable flow environments tend to be ecological generalists with traits that allow them to persist under highly variable and often harsh conditions associated with hydrological variation. Cooper Creek, an Australian dryland river, is characterised by extreme flow variability, especially in the magnitude, timing and duration of channel flows and floods, which, if they occur, do so mainly in summer. The present study examined the influence of hydrological variability on fish assemblages and abundance in four waterholes in the Windorah reach of Cooper Creek over eight occasions between 2001 and 2004. Antecedent flows had marked influences on fish species richness and assemblage structure. Following high summer flows, all waterholes supported a rich and abundant fish fauna, whereas fewer species and lower numbers were recorded following periods of zero channel flow. Recruitment of three of the four most common and abundant species was enhanced when intermittent flows inundated backwater and floodplain habitats that provide a food-rich environment. Opportunistic responses to rising channel flows and occasional large floods in Cooper Creek help to explain the prominent ‘boom’ patterns of fish production in this arid-zone river, whereas low-level recruitment during periods of low or no flow maintains populations of some species through the ‘bust’.
Seasonal variation in the long-term warming trend in water temperature off the Western Australian coast
Authors: Caputi N. , de Lestang S. , Feng M. , Pearce A.
Published: February 2009

Previous studies have demonstrated that one area of greatest increase in surface sea temperatures (SST) (0.02°C per year) in the Indian Ocean over the last 50 years occurs off the lower west coast of Australia, an area dominated by the Leeuwin Current. The present paper examines water temperature trends at several coastal sites since the early 1970s: two rock lobster puerulus monitoring sites in shallow water (<5 m); four sites from a monitoring program onboard rock lobster vessels that provide bottom water temperature (<36 m); and an environmental monitoring site at Rottnest (0–50 m depth). Two global SST datasets are also examined. These data show that there was a strong seasonal variation in the historic increases in temperature off the lower west coast of Australia, with most of the increases (0.02–0.035°C per year) only focussed on 4–6 months over the austral autumn–winter with little or no increase (<0.01°C per year) apparent in the austral spring–summer period. These increases are also apparent after taking into account the interannual variation in the strength of the Leeuwin Current. The warming trend results in a change to the seasonal temperature cycle over the decades, with a delay in the peak in the temperature cycle during autumn between the 1950s and 2000s of ~10–20 days. A delay in the timing of the minimum temperature is also apparent at Rottnest from August–September to October. This seasonal variation in water temperature increases and its effect on the annual temperature cycle should be examined in climate models because it provides the potential to better understand the specific processes through which climate change and global warming are affecting this region of the Indian Ocean. It also provides an opportunity to further test the climate models to see whether this aspect is predicted in the future projections of how increases will be manifest. Any seasonal variation in water temperature increase has important implications for fisheries and the marine ecosystem because it may affect many aspects of the annual life cycle such as timing of growth, moulting, mating, spawning and recruitment, which have to be taken into account in the stock assessment and management of fisheries.