bluuebunny/crossref_metadata_2025 huggingface dataset:
Widespread Genetic Incompatibility in
C. Elegans
Maintained by Balancing Selection
Authors: Seidel Hannah S. , Rockman Matthew V. , Kruglyak Leonid
Published: January 2008

Natural selection is expected to eliminate genetic incompatibilities from interbreeding populations. We have discovered a globally distributed incompatibility in the primarily selfing species
Caenorhabditis elegans
that has been maintained despite its negative consequences for fitness. Embryos homozygous for a naturally occurring deletion of the zygotically acting gene
zeel-1
arrest if their sperm parent carries an incompatible allele of a second, paternal-effect locus,
peel-1
. The two interacting loci are tightly linked, with incompatible alleles occurring in linkage disequilibrium in two common haplotypes. These haplotypes exhibit elevated sequence divergence, and population genetic analyses of this region indicate that natural selection is preserving both haplotypes in the population. Our data suggest that long-term maintenance of a balanced polymorphism has permitted the incompatibility to persist despite gene flow across the rest of the genome.
Observation of the Spin Hall Effect of Light via Weak Measurements
Authors: Hosten Onur , Kwiat Paul
Published: January 2008

We have detected a spin-dependent displacement perpendicular to the refractive index gradient for photons passing through an air-glass interface. The effect is the photonic version of the spin Hall effect in electronic systems, indicating the universality of the effect for particles of different nature. Treating the effect as a weak measurement of the spin projection of the photons, we used a preselection and postselection technique on the spin state to enhance the original displacement by nearly four orders of magnitude, attaining sensitivity to displacements of ∼1 angstrom. The spin Hall effect can be used for manipulating photonic angular momentum states, and the measurement technique holds promise for precision metrology.
Spatiotemporal variation in activity of bat species differing in hunting tactics: effects of weather, moonlight, food abundance, and structural clutter
Authors: Ciechanowski M. , Zając T. , Biłas A. , Dunajski R.
Published: January 2008

Different foraging tactics in related animal taxa may be expected to cause species-specific differences in sensitivity to temporal and spatial variations of resources. To test this, we studied spatiotemporal dynamics of flight and foraging activity in seven insectivorous bat species in northern Poland using broadband ultrasound detection, recording of weather conditions, insect abundance, moon phase, and cover of floating vegetation. The seven species studied comprised six (genera Eptesicus Rafinesque, 1820, Pipistrellus Kaup, 1829, and Nyctalus Bowdich, 1825) that were classified as aerial hawkers and one ( Myotis daubentonii (Kuhl, 1817)) that was classified as a water-surface forager. Stepwise forward multiple regression models indicated that the prominent limiting factors for aerial hawkers were biomass of potential prey and air temperature. Analysis of the activity of the water-surface forager revealed no effect of food abundance or air temperature, but activity was negatively affected by floating vegetation (which masks echoes of prey items), fog (which absorbs echolocation calls), and moonlight (possible increased predation risk). Hence, trophic resources appear to have no significance as a limiting factor for species using microhabitats with unusually high prey abundance (e.g., water surface). Activities of such species, however, may be more affected by temporally changing detectibility of food items and vulnerability to predation pressure.
CONE CONVEX AND RELATED FUNCTIONS IN OPTIMIZATION OVER TOPOLOGICAL VECTOR SPACES
Authors: SUNEJA S. K. , BHATIA MEETU
Published: January 2008

In this paper cone convex and related functions have been studied. The concept of cone semistrictly convex functions on topological vector spaces is introduced as a generalization of semistrictly convex functions. Certain properties of these functions have been established and their interrelations with cone convex and cone subconvex functions have been explored. Assuming the functions to be cone subconvex, sufficient optimality conditions are proved for a vector valued minimization problem over topological vector spaces, involving Gâteaux derivatives. A Mond-Weir type dual is associated and weak and strong duality results are proved.
∊-STRICTLY EFFICIENT SOLUTIONS OF VECTOR OPTIMIZATION PROBLEMS WITH SET-VALUED MAPS
Authors: LI TAIYONG , XU YIHONG , ZHU CHUANXI
Published: January 2008

In this paper, the notion of ∊-strictly efficient solution for vector optimization with set-valued maps is introduced. Under the assumption of the ic-cone-convexlikeness for set-valued maps, the scalarization theorem, ∊-Lagrangian multiplier theorem, ∊-saddle point theorems and ∊-duality assertions are established for ∊-strictly efficient solution.
THE CONICAL SINGULARITY METHOD AND THE ENERGY–MOMENTUM TENSOR NEAR THE BLACK HOLE HORIZON USING THE KRUSKAL COORDINATES
Authors: ALVES M.
Published: January 2008

We apply the conical singularity method to the two-dimensional version of the Schwarzschild metric to obtain the Kruskal coordinates of the black hole in a very simple and direct way. Then we make use of this metric in an approximated version and calculate the expected value of energy–momentum tensor of a massless quantum field near the horizon, resulting in regular expressions for its components.
BROKEN UNITARY SYMMETRIES AND FERMI–DIRAC STATISTICS
Authors: CALIXTO M. , ALDAYA V.
Published: January 2008

The existence of degenerated quantum vacua (coherent states of zero modes), for N-level quantum systems, leads to a breakdown of the original unitary U (N) symmetry in the many-particle theory. The action of some spontaneously broken symmetry transformations destabilize these pseudo-vacua and make them radiate. We study the structure of this thermal radiation, which turns out to be of Fermi–Dirac type.
Suppression of carbachol-induced oscillatory Cl−secretion by forskolin in rat parotid and submandibular acinar cells
Authors: Shintani Takahide , Hirono Chikara , Sugita Makoto , Iwasa Yoshiko , Shiba Yoshiki
Published: January 2008

Sympathetic stimulation induces weak salivation compared with parasympathetic stimulation. To clarify this phenomenon in salivary glands, we investigated cAMP-induced modulation of Ca2+-activated Cl−secretion from rat parotid and submandibular acinar cells because fluid secretion from salivary glands depends on the Cl−secretion. Carbachol (Cch), a Ca2+-increasing agent, induced hyperpolarization of the cells with oscillatory depolarization in the current clamp mode of the gramicidin-perforated patch recording. In the voltage clamp mode at −80 mV, Cch induced a bumetanide-sensitive oscillatory inward current, which was larger in rat submandibular acinar cells than in parotid acinar cells. Forskolin and IBMX, cAMP-increasing agents, did not induce any marked current, but they evoked a small nonoscillatory inward current in the presence of Cch and suppressed the Cch-induced oscillatory inward current in all parotid acinar cells and half (56%) of submandibular acinar cells. In the current clamp mode, forskolin + IBMX evoked a small nonoscillatory depolarization in the presence of Cch and reduced the amplitude of Cch-induced oscillatory depolarization in both acinar cells. The oscillatory inward current estimated at the depolarized membrane potential was suppressed by forskolin + IBMX. These results indicate that cAMP suppresses Ca2+-activated oscillatory Cl−secretion of parotid and submandibular acinar cells at −80 mV and possibly at the membrane potential during Cch stimulation. The suppression may result in the weak salivation induced by sympathetic stimulation.
Neurocognitive processing of esophageal central sensitization in the insula and cingulate gyrus
Authors: Lawal Adeyemi , Kern Mark , Sanjeevi Arthi , Antonik Stephen , Mepani Rachel , Rittmann Tanya , Hussaini Syed , Hofmann Candy , Tatro Linda , Jesmanowicz Andrzej , Verber Matt , Shaker Reza
Published: January 2008

The cingulate and insular cortices are parts of the limbic system that process and modulate gastrointestinal sensory signals. We hypothesized that sensitization of these two limbic area may operate in esophageal sensitization. Thus the objective of the study was to elucidate the neurocognitive processing in the cingulate and insular cortices to mechanical stimulation of the proximal esophagus following infusion of acid or phosphate buffer solution (PBS) into the esophagus. Twenty-six studies (14 to acid and 12 to PBS infusion) were performed in 20 healthy subjects (18–35 yr) using high-resolution (2.5 × 2.5 × 2.5 mm3 voxel size) functional MRI (fMRI). Paradigm-driven, 2-min fMRI scans were performed during randomly timed 15-s intervals of proximal esophageal barostatically controlled distentions and rest, before and after 30-min of distal esophageal acid or PBS perfusion (0.1 N HCl or 0.1 M PBS at 1 ml/min). Following distal esophageal acid infusion, at subliminal and liminal levels of proximal esophageal distentions, the number of activated voxels in both cingulate and insular cortices showed a significant increase compared with before acid infusion ( P < 0.05). No statistically significant change in cortical activity was noted following PBS infusion. We conclude that 1) acid stimulation of the esophagus results in sensitization of the cingulate and insular cortices to subliminal and liminal nonpainful mechanical stimulations, and 2) these findings can have ramifications with regard to the mechanisms of some esophageal symptoms attributed to reflux disease.
Developmental changes in arginase expression and activity in the lung
Authors: Belik Jaques , Shehnaz Darakhshanda , Pan Jingyi , Grasemann Hartmut
Published: January 2008

Arginases compete with nitric oxide (NO) synthases for l-arginine as common substrate. Pulmonary vascular and airway diseases in which arginase activity is increased are associated with decreased NO production and reduced smooth muscle relaxation. The developmental patterns of arginase activity and type I and II isoforms expression in the lung have not been previously evaluated. Hypothesizing that lung arginase activity is developmentally regulated and highest in the fetus, we measured the expression of both arginase isoforms and total arginase activity in fetal, newborn, and adult rat lung, pulmonary artery, and bronchial tissue. In addition, intrapulmonary arterial muscle force generation was evaluated in the absence and presence of the arginase inhibitor Nω-hydroxy-nor-l-arginine (nor-NOHA). Arginase II content, as well as total arginase activity, was highest in fetal rat lung, bronchi, and pulmonary arterial tissue and decreased with age ( P < 0.05), and its lung cell expression was developmentally regulated. In the presence of nor-NOHA, pulmonary arterial force generation was significantly reduced in fetus and newborn ( P < 0.01). No significant change in force generation was noted in bronchial tissue following arginase inhibition. In conclusion, arginase II is regulated developmentally, and both expression and activity are maximal during fetal life. We speculate that the maintenance of a high pulmonary vascular resistance and decreased lung NO production prenatally may, in part, be dependent on increased arginase expression and/or activity.
Diagnostic Work-Up of Pleural Effusions
Authors: Froudarakis Marios E.
Published: January 2008

A wide range of diseases may be the cause of an accumulation of fluid in the pleural space. Pleural effusion is a major diagnostic problem, since the pleura is an inner cavity with no direct access. The aim of this review is to provide a practical approach to the investigation of the patient presenting with pleural effusion. This should help to accurately diagnose pleural effusion and keep time-consuming, but necessary, invasive investigations to the minimum.
Is Single-Needle Hemodialysis Still a Good Treatment in End-Stage Renal Disease?
Authors: Trakarnvanich Thananda , Chirananthavat Thanit , Maneerat Pakamas , Chabsuwan Suwanna , Areeyakulnimit Sunanta
Published: January 2008

Background: Single-needle (SN) dialysis has been accepted as one of the alternative modes of renal replacement therapy. Despite its advantages it is not widely practiced due to the belief of underdialysis by this technique. However, it is used routinely in many hemodialysis units. We therefore aimed to study the efficacy and determine parameters that reflect the dialysis efficiency. The complications and adverse events were also evaluated. The times required to achieve maximal adequacy of dialysis were compared between 4-, 4.5-and 5.0-hour dialysis sessions. Methods: Ten stable end-stage renal disease patients who regularly used the standard hemodialysis technique with double-needle (DN) dialysis were switched to SN dialysis for three consecutive dialysis session times (4, 4.5 and 5.0 h, respectively) for 3 weeks in each period. The following parameters including Kt/V, percent recirculation, calcium, phosphorus, hematocrit, and LDH level were studied at the start and end of each period. Results: After switching to the SN mode, the Kt/V did not change significantly from the baseline value. However, in the subgroup analysis, only the thrice-weekly group achieved the target Kt/V. Kt/V declined insignificantly in the twice-weekly group but did not reach the recommended level. The other parameters were not different from the DN group. The 4-hour group had a similar Kt/V to the other groups and had less recirculation. There were no major complications during the SN phase. The outcome of the fistulas was excellent. Conclusion: The thrice-weekly SN hemodialysis with 4-hour session time has the same efficacy as the conventional DN technique with no more adverse events. Therefore, the SN hemodialysis system may be suitable for routine thrice-weekly hemodialysis in the selected group of patients.
Salivary β2-Microglobulin Analysis in Chronic Kidney Disease and Hemodialyzed Patients
Authors: Michelis Regina , Sela Shifra , Ben-Zvi Ilan , Nagler Rafael M.
Published: January 2008

Background: β2-Microglobulin (β2m) is a major component in dialysis-related amyloidosis, a disabling disease affecting long-term dialysis patients. Methods: β2m and other components were analyzed in saliva and serum from 53 individuals in 4 subgroups: healthy normal controls, diabetes mellitus (DM), chronic kidney disease (CKD) and hemodialysis (HD) patients. Results: Median salivary and mean serum β2m concentrations were 78% higher in both saliva (p = 0.048) and serum (p = 0.047) in DM patients; 118% (p = 0.016) and 907% (p = 0.007) higher, respectively, in CKD patients, and 328% (p = 0.0001) and 2,710% (p = 0.001) higher, respectively, in HD patients, compared with healthy controls. The correlation analysis between salivary and serum β2m concentrations showed a low correlation rate in HD patients (r = –0.18), but was rather high in CKD patients (r = 0.50). Conclusions: Salivary analysis of β2m is a reliable method for evaluating serum β2m levels in CKD patients, and may help predict the potential for development of CKD-induced amyloidosis.
Wilms’ Tumor in Children: An Overview
Authors: Varan Ali
Published: January 2008

Wilms’ tumor is the most frequently occurring renal tumor in children and is one of the most treatment-responsive tumors. A tumor-suppressor gene and other genetic abnormalities have been implicated in its etiology. In addition, patients with several congenital anomalies, such as Beckwith-Wiedemann syndrome, WAGR syndrome, and Denys-Drash syndrome, have an increased risk of Wilms’ tumor. Previously, a three-drug chemotherapy regimen with surgery and radiotherapy was used with patients in all stages. Now, patients with early-stage Wilms’ tumor are treated with a two-drug regimen without radiotherapy, whereas those in advanced stages still receive the three-drug regimen and radiotherapy. Two large collaborative groups – the National Wilms’ Tumor Study Group (NWTS) in the United States and the International Society of Pediatric Oncology (SIOP) in Europe – are involved in Wilms’ tumor management, which differs in some aspects. Multimodality treatment has been used successfully, and in Europe preoperative strategies are used as well. As the survival rate has now reached 90%, the primary objectives of the physician are to perform nephron-sparing surgery in selected cases and to reduce the dosage and duration of chemotherapy and radiotherapy in appropriate cases. Other renal tumors occur rarely, but have also been treated successfully in the last decade.
The Toreutics of Colchis in the 5th-4th Centuries BC Local Traditions, Outside Influences, Innovations
Authors: Treister Mikhail Yu.
Published: January 2008

Two silver vessels: a silver aryballos from the mid-5th century BC burial No. 11/1969 in Vani and a silver goblet from the ritual complex No. 1 of the Ulyap barrow No. 1 in the Kuban basin, dated to the late 5th-early 4th century BC, are discussed. e similarities in details of the vessels and their decoration with those of the silver vessels found in Lydia and the vicinity of Sinope are pointed out. A group of items of toreutics from the 5th-4th centuries BC complexes in Colchis and outside it is singled out: they are decorated with incised animal or mythological images, the bodies of which are covered with vertical rows of horizontal notches. One can not exclude, that this kind of decoration goes back to the images on the Colchian bronze axes and belts of the 8th-6th centuries BC. The characteristic rosette decorating the bottoms of the vessels from Vani, Ulyap and the phiale No. 61 from the Treasure of Akhalgori is analysed; its genesis is discussed going back to the rosettes on the 6th century BC phialai from Iran, Asia Minor and the Balkans. Further the examples of Lydian metalware found in Colchis are discussed, including the phiale with the votive inscription to the temple of Apollo in Phasis found in the later Sarmatian burial in the Kuban basin. Finally, the problem of the 'international Achaemenid style' and the regional school of Achamenid-inspired toreutics is analysed. In general the author comes to the conclusion of the strong influence of toreutics of the Lydian-Ionian school and Anatolia in a broad sense of this term on the local school of toreutics, which emerged in Colchis in the 5th-4th centuries BC.
Basin-Scale Carbon Monoxide Distributions in the Parallel Ocean Program
Authors: Chu Shaoping , Elliott Scott , Erickson David
Published: January 2008

As a primary photochemical constituent in upper-ocean and tropospheric geocycling, carbon monoxide is of interest to a variety of global change research communities. Dynamic three-dimensional simulations of its marine concentration patterns, emphasizing Pacific surface waters, are presented. Calculations were driven by nitrogen/iron ecodynamics within the Parallel Ocean Program (POP) transport framework. Photoproduction was estimated following broadband transfer of ultraviolet A radiation down to and penetrating the mixed layer. Quantum efficiency, absorption, the chromophoric fraction of dissolved organics, and related microchemical parameters were all varied, in some cases collectively. Bacterial uptake was parameterized through stages of refinement ranging from a single global average time constant to the application of steady-state zooplanktonic grazing pressure. Major features of basin-spanning ship track data can be reproduced including tropical to gyre and temperate frontal ratios. Evidence for ecosystem structural influence upon the removal kinetics is reviewed and investigated. Polar waters exhibit unique processing modes and the periphery of the ocean requires specialized handling of organic and bacterial behavior. Large-scale budgets are consistent with recent independent determinations both with respect to internal turnover and flux to the atmosphere. A parsimonious mechanism involving optimized yield is recommended for early system model efforts. Areas awaiting improvement include resolution of UV and the segregation of both light-interacting carbon compounds and microbial populations as tracers.
Different Effects of SLCO1B1 Polymorphism on the Pharmacokinetics and Pharmacodynamics of Repaglinide and Nateglinide
Authors: Kalliokoski Annikka , Neuvonen Mikko , Neuvonen Pertti J. , Niemi Mikko
Published: January 2008

Thirty‐two healthy volunteers with different SLCO1B1 genotypes ingested a 0.5‐mg dose of repaglinide and 60‐mg dose of nateglinide with a washout period of 1 week. Participants with SLCO1B1 c.521CC genotype (n = 4) had a 59% (P = 0.001) or 72% (P < 0.001) greater mean area under the plasma repaglinide concentration‐time curve (AUC0‐∞) than participants with c.521TC (n = 12) or c.521TT (n = 16) genotypes. The AUC0‐∞ of repaglinide metabolites M2 and M4 were 112% (P = 0.004) and 81% (P = 0.002) larger in participants with c.521CC genotype than in those with c.521TT genotype, but no differences existed in the pharmacokinetics of M1. Maximum decrease in blood glucose concentration correlated with repaglinide AUC0‐∞ (r = 0.412, P = 0.019). SLCO1B1 polymorphism had no significant effect on the pharmacokinetics or pharmacodynamics of nateglinide or its M7 metabolite. Thus, in contrast to repaglinide, the disposition of nateglinide is unaffected by the SLCO1B1 c.521T>C polymorphism.
Mediational Inferences in Organizational Research
Authors: Mathieu John E. , DeShon Richard P. , Bergh Donald D.
Published: January 2008

This introductory article for the feature topic on mediation is designed to provide a context for the articles that follow. Specifically, the authors revisit the history of mediational inferences in social and organizational sciences and illustrate how mediational inferences have been evident for more than a century. Some of the important milestones and the evolution of thought leading to today are chronicled. Then a modern-day framework for understanding mediational inferences is outlined that serves to highlight how the articles included in this feature topic contribute to the continued evolution of the bases of mediational inferences. The article concludes with the authors' vision of what may be fruitful directions for future research.
Proteomic profile determination of autosomal aneuploidies by mass spectrometry on amniotic fluids
Authors: Mange Alain , Desmetz Caroline , Bellet Virginie , Molinari Nicolas , Maudelonde Thierry , Solassol Jerome
Published: January 2008

Background

Prenatal diagnosis of chromosomal abnormalities by cytogenetic analysis is time-consuming, expensive, and requires highly qualified technicians. Rapid diagnosis of aneuploidies followed by reassurance of women with normal results can be performed by molecular analysis of uncultured foetal cells. In the present study, we developed a proteomic fingerprinting approach coupled with a statistical classification method to improve diagnosis of aneuploidies, including trisomies 13, 18, and 21, in amniotic fluid samples.

Results

The proteomic spectra obtained from 52 pregnant women were compiled, normalized, and mass peaks with mass-to-charge ratios between 2.5 and 50 kDa identified. Peak information was combined together and analysed using univariate statistics. Among the 208 expressed protein peaks, 40 differed significantly between aneuploid and non aneuploid samples, with AUC diagnostic values ranging from 0.71 to 0.91. Hierarchical clustering, principal component analysis and support vector machine (SVM) analysis were performed. Two class predictor models were defined from the training set, which resulted in a prediction accuracy of 92.3% and 96.43%, respectively. Using an external and independent validation set, diagnostic accuracies were maintained at 87.5% and 91.67%, respectively.

Conclusion

This pilot study demonstrates the potential interest of protein expression signature in the identification of new potential biological markers that might be helpful for the rapid clinical management of high-risk pregnancies.
Heterologous influenza vRNA segments with identical non-coding sequences stimulate viral RNA replication in trans
Authors: Ng Stella SF , Li Olive TW , Cheung Timothy KW , Malik Peiris J S , Poon Leo LM
Published: January 2008

The initiation of transcription and replication of influenza A virus requires the 5' and 3' ends of vRNA. Here, the role of segment-specific non-coding sequences of influenza A virus on viral RNA synthesis was studied. Recombinant viruses, with the nonstructural protein (NS) segment-specific non-coding sequences replaced by the corresponding sequences of the neuraminidase (NA) segment, were characterized. The NS and NA vRNA levels in cells infected with these mutants were much higher than those of the wild type, whereas the NS and NA mRNA levels of the mutants were comparable to the wild-type levels. By contrast, the PB2 vRNA and mRNA levels of all the tested viruses were similar, indicating that vRNA with heterologous segment-specific non-coding sequences was not affected by the mutations. The observations suggested that, with the cooperation between the homologous 5' and 3'segment-specific sequences, the introduced mutations could specifically enhance the replication of NA and NS vRNA.
Broad network-based predictability of Saccharomyces cerevisiaegene loss-of-function phenotypes
Authors: McGary Kriston L , Lee Insuk , Marcotte Edward M
Published: January 2008

We demonstrate that loss-of-function yeast phenotypes are predictable by guilt-by-association in functional gene networks. Testing 1,102 loss-of-function phenotypes from genome-wide assays of yeast reveals predictability of diverse phenotypes, spanning cellular morphology, growth, metabolism, and quantitative cell shape features. We apply the method to extend a genome-wide screen by predicting, then verifying, genes whose disruption elongates yeast cells, and to predict human disease genes. To facilitate network-guided screens, a web server is available http://www.yeastnet.org.
Interpretation of magnetic data using tilt-angle derivatives
Authors: Salem Ahmed , Williams Simon , Fairhead Derek , Smith Richard , Ravat Dhananjay
Published: January 2008

We have developed a new method for interpretation of gridded magnetic data which, based on derivatives of the tilt angle, provides a simple linear equation, similar to the 3D Euler equation. Our method estimates both the horizontal location and the depth of magnetic bodies, but without specifying prior information about the nature of the sources (structural index). Using source-position estimates, the nature of the source can then be inferred. Theoretical simulations over simple and complex magnetic sources that give rise to noise-corrupted and noise-free data, illustrate the ability of the method to provide source locations and index values characterizing the nature of the source bodies. Our method uses second derivatives of the magnetic anomaly, which are sensitive to noise (high-wavenumber spectral content) in the data. Thus, an upward continuation of the anomaly may lead to reduce the noise effect. We demonstrate the practical utility of the method using a field example from Namibia, where the results of the proposed method show broad cor-relation with previous results using interactive forward modeling.
Acquisition and processing pitfall associated with clipping near-surface seismic reflection traces
Authors: Sloan Steven D. , Steeples Don W. , Malin Peter E.
Published: January 2008

The processing of clipped seismic traces may produce high-frequency wavelets that can be misinterpreted as reflections in filtered shot gathers and common-midpoint (CMP) stacked sections. To illustrate this effect, a near-surface CMP seismic reflection survey was conducted using two sources to compare the effects of various band-pass frequency filters on clipped traces. An event observed in the clipped data set replicated the frequency of the filter operators applied, similar to the effect of convolving a boxcar function with the filter operator. The anomaly exhibited hyperbolic moveout and imitated a reflection during the processing stages. The hyperbolic event was flattened by NMO corrections chosen for the target reflection, and it stacked in as a coherent event in the final section. Clipped data should be removed or corrected before processing to prevent misinterpreting high-frequency reflection artifacts in trace gathers and stacked sections.
Yet another Vs equation
Authors: Dvorkin Jack P.
Published: January 2008

The classical Raymer-Hunt-Gardner functional form [Formula: see text], where [Formula: see text] and [Formula: see text] denote the [Formula: see text]-wave velocity in the solid and pore-fluid phases, respectively, and [Formula: see text] is the total porosity, can also be used to relate the S-wave velocity in dry rock to porosity and mineralogy as [Formula: see text], where [Formula: see text] is the S-wave velocity in the solid phase. Assuming that the shear modulus of rock does not depend on the pore fluid, [Formula: see text] in wet rock is [Formula: see text], where [Formula: see text] and [Formula: see text] denote the bulk density of the dry and wet rock, respectively. This new functional form for [Formula: see text] prediction reiterates Nur’s critical porosity concept: The [Formula: see text] ratio in dry rock equals that in the solid phase. It accurately predicts [Formula: see text] in consolidated clastic and carbonate rock. Two motivations for using it are (1) it is simple, and (2) it predicts [Formula: see text] not from [Formula: see text] but directly from [Formula: see text] and mineralogy.
Static and dynamic Young’s moduli of chalk from the North Sea
Authors: Olsen Casper , Christensen Helle Foged , Fabricius Ida L.
Published: January 2008

We present results from a study of dynamic and static Young’s moduli of North Sea chalk based on laboratory tests on both dry and water-saturated chalk. We obtained static moduli by using both strain gauge and linear voltage displacement transducer (LVDT) measurements. We investigated the influence of pore fluid on static and dynamic Young’s moduli and evaluated the two methods for obtaining static Young’s modulus. We obtained good agreement between dynamic and static Young’s moduli from strain gauge measurements on dry chalk, but for water-saturated chalk the dynamic Young’s modulus was larger than the measured static Young’s modulus. This difference may be caused in part by the influence of the difference in frequencies of static and dynamic measurements. Another reason for the observed difference may be a practical experimental problem that causes the measured static Young’s modulus for water-saturated chalk to be lower than the true modulus. When we compared dynamic Young’s modulus for dry chalk with that for water-saturated chalk, the dry modulus was larger than the water-saturated modulus, probably owing to shear weakening of the chalk. Young’s modulus from LVDT measurements does not relate to dynamic Young’s modulus for dry or water-saturated rock because the LVDT is not able to accurately measure the small deformations of the samples during loading at relatively low stresses.
Can gas sand have a large Poisson’s ratio?
Authors: Dvorkin Jack P.
Published: January 2008

Laboratory data supported by granular-medium and inclusion theories indicate that Poisson’s ratio in gas-saturated sand lies within a range of 0–0.25, with typical values of approximately 0.15. However, some well log measurements, especially in slow gas formations, persistently produce a Poisson’s ratio as large as 0.3. If this measurement is not caused by poor-quality data, three in situ situations — patchy saturation, subresolution thin layering, and elastic anisotropy — provide a plausible explanation. In the patchy saturation situation, the well data must be corrected to produce realistic synthetic seismic traces. In the second and third cases, the effect observed in a well is likely to persist at the seismic scale.
A new sensitivity-controlled focusing regularization scheme for the inversion of induced polarization data based on the minimum gradient support
Authors: Blaschek R. , Hördt A. , Kemna A.
Published: January 2008

We present a new application of a focusing regularization scheme for the inversion of resistivity and induced polarization (IP) data that supports large resistivity magnitude and phase contrasts. Similar approaches so far have only been used for the interpretation of gravity, magnetic, or seismic data sets. Unlike methods based on smoothness constraints, the approach is able to resolve sharp boundaries of bodies and layers, and it allows slight parameter variations within them. Therefore, it can be used in hydrogeologic applications where we need focused images to resolve high-contrast aquifer boundaries. Our approach is based on the minimum gradient support, which seeks to minimize the occurrence of parameter contrasts, independent of their magnitude. We study the effects of a variable control parameter on the reweighting optimization, allowing a continuous transition from smooth to sharp images. We also take the spatially varying sensitivity into account to allow focusing even where sensitivities are small. The implemented weighting leads to increased smoothing in well-resolved areas and a decrease in regions of lower sensitivity. The opposite approach is examined as well. This gradient-dependent sensitivity weighting is basically an extension of depth-dependent sensitivity weighting. We demonstrate the effectiveness and limitations of the approach and the influence of the control parameter using different synthetic models and field data from a hydrogeophysical test site. The technique has proven particularly suitable for revealing sharp parameter contrasts.
Laboratory experiments on compressional ultrasonic wave attenuation in partially frozen brines
Authors: Matsushima Jun , Suzuki Makoto , Kato Yoshibumi , Nibe Takao , Rokugawa Shuichi
Published: January 2008

Often, the loss mechanisms responsible for seismic attenuation are unclear and controversial. We used partially frozen brine as a solid-liquid coexistence system to investigate attenuation phenomena. Ultrasonic wave-transmission measurements on an ice-brine coexisting system were conducted to examine the influence of unfrozen brine in the pore microstructure on ultrasonic waves. We observed the variations of a 150–1000 kHz wave transmitted through a liquid system to a solid-liquid coexistence system, changing its temperature from [Formula: see text] to –[Formula: see text]. We quantitatively estimated attenuation in a frequency range of [Formula: see text] by considering different distances between the source and receiver transducers. We also estimated the total amount of frozen brine at each temperature by using the pulsed nuclear magnetic resonance (NMR) technique and related those results to attenuation results. The waveform analyses indicate that ultrasonic attenuation in an ice-brine coexisting system reaches its peak at [Formula: see text], at which the ratio of the liquid phase to the total volume in an ice-brine coexisting system is maximal. Finally, we obtained a highly positive correlation between the attenuation of ultrasonic waves and the total amount of unfrozen brine. Thus, laboratory experiments demonstrate that ultrasonic waves within this frequency range are affected significantly by the existence of unfrozen brine in the pore microstructure.
Exploring Human Testicular Peritubular Cells: Identification of Secretory Products and Regulation by Tumor Necrosis Factor-α
Authors: Schell Christoph , Albrecht Martin , Mayer Christine , Schwarzer J. Ullrich , Frungieri Monica B. , Mayerhofer Artur
Published: January 2008

Testicular peritubular cells are myofibroblastic cells, which represent the major cellular components of the wall of the seminiferous tubules. In men their phenotypic characteristics, including possible secretory activity and regulation, are not well known, in neither normal nor pathologically altered testes. Especially in testes of men with impaired spermatogenesis, the cytoarchitecture of the tubular wall is frequently remodeled and presents fibrotic thickening, increased innervation, and infiltration by macrophages and mast cells. The latter are two sources of TNF-α. The purpose of our study was to explore human testicular peritubular cells and mechanisms of their regulation. To this end we primarily studied cultured human testicular peritubular cells (HTPCs), isolated from adult human testes. Having established that HTPCs express TNF-α receptors 1 and 2 and respond to recombinant human TNF-α by a rapid phosphorylation of ERK1/2, we used complementary approaches, including gene array/RT-PCR studies, Western blotting/immunocytochemistry, and ELISA techniques to study phenotypic characteristics of HTPCs and actions of TNFα. We found that HTPCs express the nerve growth factor gene and TNF-α-stimulated mRNA levels and secretion of nerve growth factor in a dose- and time-dependent manner. Similarly, monocyte chemoattractant protein-1 was identified as a product of HTPCs, which was regulated by TNF-α in a concentration- and time-dependent manner. TNF-α furthermore strongly enhanced expression and/or synthesis of other inflammatory molecules, namely IL-6 and cyclooxygenase-2. Active cyclooxygenase-2 is indicated by increased prostaglandin D2 levels. In addition, intercellular adhesion molecule-1, which was not detected at protein level in the absence of TNF-α, was induced upon TNF-α stimulation. In conclusion, these results provide novel insights into the nature of human peritubular cells, which are able to secrete potent signaling molecules and are regulated by TNF-α. These results also hint to an as-yet-unknown role of peritubular cells in normal human testis and involvement in the pathomechanisms associated with impaired spermatogenesis in men.
Clock Gene Expression in Adult Primate Suprachiasmatic Nuclei and Adrenal: Is the Adrenal a Peripheral Clock Responsive to Melatonin?
Authors: Valenzuela F. J. , Torres-Farfan C. , Richter H. G. , Mendez N. , Campino C. , Torrealba F. , Valenzuela G. J. , Serón-Ferré M.
Published: January 2008

The circadian production of glucocorticoids involves the concerted action of several factors that eventually allow an adequate adaptation to the environment. Circadian rhythms are controlled by the circadian timing system that comprises peripheral oscillators and a central rhythm generator located in the suprachiasmatic nucleus (SCN) of the hypothalamus, driven by the self-regulatory interaction of a set of proteins encoded by genes named clock genes. Here we describe the phase relationship between the SCN and adrenal gland for the expression of selected core clock transcripts (Per-2, Bmal-1) in the adult capuchin monkey, a New World, diurnal nonhuman primate. In the SCN we found a higher expression of Bmal-1 during the h of darkness (2000–0200 h) and Per-2 during daytime h (1400 h). The adrenal gland expressed clock genes in oscillatory fashion, with higher values for Bmal-1 during the day (1400–2000 h), whereas Per-2 was higher at nighttime (about 0200 h), resulting in a 9- to 12-h antiphase pattern. In the adrenal gland, the oscillation of clock genes was accompanied by rhythmic expression of a functional output, the steroidogenic enzyme 3β-hydroxysteroid dehydrogenase. Furthermore, we show that adrenal explants maintained oscillatory expression of Per-2 and Bmal-1 for at least 36 h in culture. The acrophase of both transcripts, but not its overall expression along the incubation, was blunted by 100 nm melatonin. Altogether, these results demonstrate oscillation of clock genes in the SCN and adrenal gland of a diurnal primate and support an oscillation of clock genes in the adrenal gland that may be modulated by the neurohormone melatonin.
Pathways Leading to Phosphorylation of P450c17 and to the Posttranslational Regulation of Androgen Biosynthesis
Authors: Tee Meng Kian , Dong Qing , Miller Walter L.
Published: January 2008

Cytochrome P450c17 (P450c17) is the single enzyme that catalyzes steroid 17α-hydroxylase and 17,20 lyase activities and hence is the crucial decision-making step that determines the class of steroid made in a steroidogenic cell. Although both activities are catalyzed on a single active site, the ratio of these activities is regulated by posttranslational events. Serine phosphorylation of P450c17 increases 17,20 lyase activity by increasing the enzyme’s affinity for its redox partner, P450 oxidoreductase. We searched for the relevant kinase(s) that phosphorylates P450c17 by microarray studies and by testing of kinase inhibitors. Microarrays show that 145 of the 278 known serine/threonine kinases are expressed in human adrenal NCI-H295A cells, only six of which were induced more than 2-fold by treatment with 8-Br-cAMP. Key components of the ERK1/2 and MAPK/ERK kinase (MEK)1/2 pathways, which have been implicated in the insulin resistance of PCOS, were not found in NCI-H295A cells, implying that these pathways do not participate in P450c17 phosphorylation. Treatment with various kinase inhibitors that probe the protein kinase A/phosphatidylinositol 3-kinase/Akt pathway and the calcium/calmodulin/MAPK kinase pathway had no effect on the ratio of 17,20 lyase activity to 17α-hydroxylase activity, appearing to eliminate these pathways as candidates leading to the phosphorylation of P450c17. Two inhibitors that target the Rho-associated, coiled-coil containing protein kinase (ROCK)/Rho pathway suppressed 17,20 lyase activity and P450c17 phosphorylation, both in NCI-H295A cells and in COS-1 cells transfected with a P450c17 expression vector. ROCK1 phosphorylated P450c17 in vitro, but that phosphorylation did not affect 17,20 lyase activity. We conclude that members of the ROCK/Rho pathway act upstream from the kinase that phosphorylates P450c17 in a fashion that augments 17,20 lyase activity, possibly acting to catalyze a priming phosphorylation.
Disruption of PDGFRα-initiated PI3K activation and migration of somite derivatives leads to spina bifida
Authors: Pickett Elizabeth A. , Olsen Gregory S. , Tallquist Michelle D.
Published: January 2008

Spina bifida, or failure of the vertebrae to close at the midline, is a common congenital malformation in humans that is often synonymous with neural tube defects (NTDs). However, it is likely that other etiologies exist. Genetic disruption of platelet-derived growth factor receptor (PDGFR) αresults in spina bifida, but the underlying mechanism has not been identified. To elucidate the cause of this birth defect in PDGFRα mutant embryos, we examined the developmental processes involved in vertebrae formation. Exposure of chick embryos to the PDGFR inhibitor imatinib mesylate resulted in spina bifida in the absence of NTDs. We next examined embryos with a tissue-specific deletion of the receptor. We found that loss of the receptor from chondrocytes did not recapitulate the spina bifida phenotype. By contrast, loss of the receptor from all sclerotome and dermatome derivatives or disruption of PDGFRα-driven phosphatidyl-inositol 3′ kinase (PI3K) activity resulted in spina bifida. Furthermore, we identified a migration defect in the sclerotome as the cause of the abnormal vertebral development. We found that primary cells from these mice exhibited defects in PAK1 activation and paxillin localization. Taken together, these results indicate that PDGFRα downstream effectors, especially PI3K, are essential for cell migration of a somite-derived dorsal mesenchyme and disruption of receptor signaling in these cells leads to spina bifida.
Letter: New Fragment Ion Production Method Using Super Cold Electrons in Electron Cyclotron Resonance Plasma
Authors: Kidera Masanori , Takahashi Kazuya , Enomoto Shuichi , Goto Akira , Yano Yasushige
Published: January 2008

We examined the fragmentation and ionization of molecules by low-temperature electrons generated by electron cyclotron resonance (ECR) plasma. We examined several types of metallocene compounds comprising a metal and 1,3-cyclopentadienes as ligands. We performed analyses using an ECR ion source (ECRIS) mass spectrometer. Consequently, we succeeded in ionizing fragments of an organometallic compound by adjusting the input power of the microwave introducing a super high-frequency plasma. Moreover, we succeeded in dynamically generating a significant quantity of fragment ions by continuously varying the input power. Information on the structure of a molecule may be acquired from this operation. Moreover, a molecule that could not be easily ionized thus far may now be ionizable when soft ionization is performed with this technique.
Negative Matrix-Assisted Laser Desorption/Ionization Time-of-Flight/Time-of-Flight Tandem Mass Spectrometry Fragmentation of Synthetic Analogs of the O-Specific Polysaccharide of Vibrio Cholerae O:1 in the Presence of Anionic Dopants
Authors: Chmelík Josef , Řehulka Pavel , Kováčik Vladimír , Pätoprstý Vladimír , Kováč Pavol
Published: January 2008

Oligosaccharides (tri- to hexamers) that represent terminal epitopes of O-antigens of Vibrio cholerae O:1, serotypes Ogawa and Inaba, have been studied by negative matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-ToF/ToF MS). The [M – H+]− ions are formed after expulsion of a proton from molecules studied under MALDI/MS analysis conditions in the negative mode. Several ammonium salts (chloride, nitrate, hydrogencarbonate and hydrogensulfate) were used as additives to increase the formation of negative ions from saccharides. The most efficient was the addition of ammonium hydrogencarbonate, which increased the number of [M – H+]− ions more than six times. Between three fragmentation pathways, the new conjugated transfer of electrons within the second downstream unit of oligosaccharides was discovered. Production of these ions, which has not been observed in any other kinds of measurement, distinguishes substances belonging to Ogawa and Inaba serotypes. The negative MALDI-ToF/ToF mass spectra are simpler and, at the same time, more informative, as compared with positive and negative electrospray ionization ion trap as well as with positive MALDI-ToF/ToF analysis.
Fragmentation and Gas Phase Aggregation Processes in the Laser Desorption/Ionization of Chlorodiaminotriazines
Authors: Hurtado Paola , Hortal Ana R. , Cruz-Guzmán Marta , Martínez-Haya Bruno
Published: January 2008

Fragmentation and supramolecular aggregation induced during the laser desorption/ionization (LDI) of four chlorodiaminotriazines (simazine, atrazine, terbutylazine and propazine) have been investigated. The laser wavelength employed (266 nm) lies within the first absorption band of the four triazines. The main fragmentation channel observed involves the prompt cleavage of the Cl atom, followed by partial or total fragmentation of the side alkyl chains. Breakage of the triazinic ring becomes efficient at moderate laser powers; however, the deamination of the triazine is not observed to take place. In addition, the formation of both covalent and non-covalent triazinic aggregates in the desorption plume is found to be particularly efficient. Aggregates as large as heptamers are neatly detected, with the observation that those with the most intense signal involve the dechlorinated triazinic fragment. Both aggregation and fragmentation are largely suppressed upon dilution of the triazine under matrix-assisted laser desorption/ionization conditions.