bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the Enablers of Organizational and Marketing Innovations in SMEs
Authors: Ajayi Oluseyi Moses , Morton Susan C.
Published: March 2015

Previous research studies on innovation tend to focus on process and product innovations. Recent theoretical opinions reveal that Organizational and Marketing Innovations (OMIs) could be the necessary prerequisites to optimally utilize and deploy such process and product innovations. It is important to note that there is a dearth of information on the enablers of OMIs capabilities among small and medium-sized enterprises (SMEs). Despite their closeness to their customers, many SMEs are finding it difficult to achieve successful and effective innovations; these are innovations that have a positive impact on the business growth and returns. This study presents findings from exploratory qualitative research conducted in South-Western Nigeria. Drawing upon information-rich evidence from 13 in-depth interviews with the owners and the managers of SMEs, this study identifies some enablers that can promote SMEs’ OMIs capabilities, effective innovations, and organizational survival.
Adherence to a Telephone-Supported Depression Self-Care Intervention for Adults With Chronic Physical Illnesses
Authors: Simco Russell , McCusker Jane , Sewitch Maida , Cole Martin G. , Yaffe Mark , Lavoie Kim L. , Sussman Tamara , Strumpf Erin , Ciampi Antonio , Belzile Eric
Published: March 2015

We assessed adherence to and predictors of two components of a telephone-supported self-care intervention for depression among primary care adults aged 40 and above with chronic physical illnesses and comorbid depressive symptoms. Participants received a “toolkit” containing six self-care tools. Trained lay self-care “coaches” negotiated a contact schedule of up to weekly contacts. Study outcomes were levels of completion of the self-care tool and the coach contacts at the 2-month follow-up. Coaches reported the number of completed contacts. In all, 57 of 63 participants completed the 2-month follow-up. Of these, 67% completed at least 1 tool; the mean number of coach contacts was 5.7 ( SD = 2.4) of a possible 9 contacts (63% adherence). Higher disease comorbidity and lower initial depression severity independently predicted better tool adherence. Findings suggest that people with chronic physical illnesses can achieve acceptable levels of adherence to a depression self-care intervention similar to those reported for other populations.
Impact of Gender Stereotype on Secondary School Students’ Self-Concept and Academic Achievement
Authors: Igbo J. N. , Onu V. C. , Obiyo N. O.
Published: March 2015

The aim of the study was to investigate the influence of gender stereotype as a predictor of secondary school students’ self-concept and academic achievement. The study was guided by four purposes, four research questions, and four hypotheses. The study adopted ex post facto design. The research sample was drawn from eight government/public senior secondary schools in Udi education zone. Nine schools were randomly selected from the 227 schools. A total of 342 senior secondary II school (SSII) students made up the sample of the study. A 20-item students’ stereotype self-concept questionnaire (SSSCQ) was adapted from Marsh’s Self Descriptive Questionnaire II (SDQII), and a 10-item students’ mathematics achievement test (SMAT) was developed by the researchers after reviewing related literature. This was done with the help of experts in the areas. The instruments were face and content validated and used for the collection of data. In analyzing the data, mean and standard deviation were used in answering the research questions while a t test was used in testing the four hypotheses. The findings of the study indicate that gender stereotype has significant influence on students’ self-concept and academic achievement in favor of the male students. On the other hand, school location has significant influence on academic achievement of students but has no significant influence on students’ self-concept.
Lessons Learned
Authors: Phelan Amanda , Davis Michaela
Published: March 2015

The public health nurses’ scope of practice explicitly includes child protection within their role, which places them in a prime position to identify child protection concerns. This role compliments that of other professions and voluntary agenices who work with children. Public health nurses are in a privileged position as they form a relationship with the child’s parent(s)/guardian(s) and are able to see the child in its own environment, which many professionals cannot. Child protection in Ireland, while influenced by other countries, has progressed through a distinct pathway that streamlined protocols and procedures. However, despite the above serious failures have occurred in the Irish system, and inquiries over the past 20 years persistently present similar contributing factors, namely, the lack of standardized and comprehensive service responses. Moreover, poor practice is compounded by the lack of recognition of the various interactional processes taking place within and between the different agencies of child protection, leading to psychological barriers in communication. This article will explore the lessons learned for public health nurses practice in safeguarding children in the Republic of Ireland.
Evaluation of the effect of ambrisentan on digital microvascular flow in patients with systemic sclerosis using laser Doppler perfusion imaging: a 12-week randomized double-blind placebo controlled trial
Authors: Bose Nilanjana , Bena James , Chatterjee Soumya
Published: March 2015

Introduction

In patients with systemic sclerosis (SSc), digital ischemia results from an occlusive microvasculopathy that may not respond adequately to conventional vasodilators. Endothelin receptor antagonists can potentially modify the fibroproliferative vascular remodeling in SSc, and hence their use may be justified in the management of digital ischemia. The objective of this clinical trial was to evaluate the effect of ambrisentan, a selective endothelin type A receptor antagonist, on microvascular blood flow in patients with limited systemic sclerosis (SSc) using laser Doppler perfusion imaging (LDPI).

Methods

In this randomized, double-blind, placebo controlled study we enrolled 20 patients with limited SSc. Fifteen patients received ambrisentan 5 mg daily for one month and then 10 mg daily for two months, and five received a placebo. There were three visits: weeks 0 (baseline), one and 12. Three patient-oriented questionnaires were completed at each visit: Scleroderma-Health Assessment Questionnaire (S-HAQ), Raynaud Condition Score (RCS), and Pain-Visual Analog Scale (P-VAS). At each visit, LDPI was used to obtain three blood flow readings involving regions of interest in second to fifth fingers of the non-dominant hand at room temperature (25°C) and after cooling (10°C) for two minutes.

Results

There were 16 females (80%); mean age was 50 years. None of the differences in blood flow (as measured by LDPI) were significant both at baseline and after cooling. However, patients in the ambrisentan group showed significant improvement in the patient-oriented outcomes: RCS (P = 0.001) and S-HAQ score (P = 0.005).

Conclusions

This pilot study did not show evidence of significant increase in digital blood flow over time; however, there was an improvement in RCS and S-HAQ score. We conclude that continuous use of ambrisentan for three months does not seem to significantly improve digital blood flow in SSc patients.

Trial registration

Clinicaltrials.gov NCT01072669. Registered 19 February 2010.
Rapid resistivity imaging for marine controlled-source electromagnetic surveys with two transmitter polarizations: An application to the North Alex mud volcano, West Nile Delta
Authors: Swidinsky Andrei , Hölz Sebastian , Jegen Marion
Published: March 2015

To image the internal resistivity structure of the North Alex mud volcano offshore Egypt, the marine electromagnetics group at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) developed and conducted a novel transient marine controlled-source electromagnetic experiment. The system, which was specifically developed to image the mud volcano, is also generally suitable for surveys of other small seafloor targets, such as gas-hydrate reservoirs, fluid-flow features, and submarine massive-sulfide deposits. An electric bipole antenna is set down by a remotely operated vehicle on the seafloor sequentially in two perpendicular polarizations at each transmission station. Two orthogonal horizontal electric field components are recorded on the seabed by an array of independently deployed nodal receivers (RXs). With two transmitter polarizations, the unique acquisition geometry of the system provides a very rich data set. However, for this geometric setup, conventional marine electromagnetic interpretation schemes (such as normalized magnitude variation with offset plots) have been difficult to implement. We have developed a simple imaging technique, which can be used for a first-step mapping of seafloor apparent resistivity with the GEOMAR system. Images can be produced in just a few minutes on a regular laptop computer, and the robustness of the approach was demonstrated using two synthetic data sets from simple seafloor models. The method was then applied to the real data acquired at the North Alex mud volcano in 2008. Results found increased apparent sediment resistivities of up to 4 Ωm near the center of the mud volcano occurring at source-RX offsets greater than 500 m, which mapped to apparent depths of greater than 150 m. This may be caused by large quantities of free gas or freshwater in the sediment pore space.
The effect of systematic diagenetic changes on the mechanical behavior of a quartz-cemented sandstone
Authors: Cook Jennie E. , Goodwin Laurel B. , Boutt David F. , Tobin Harold J.
Published: March 2015

A key goal of petrophysical studies of sandstones is to relate common field measurements, particularly seismic or sonic velocities, to parameters defining the rock’s mechanical and hydrologic characteristics. These include elastic and inelastic mechanical properties, porosity, and permeability. We explored relationships among these properties in variably quartz-cemented, mature arenites of the St. Peter Sandstone with porosities ranging from 9% to 25%. In a previous paper, we described microstructural changes accompanying progressive quartz cementation and related porosity and permeability reduction in this sample suite. Here, we report ultrasonic velocities ultrasonic velocities, dynamic and static elastic properties, confined compressive strength, and tensile strength. Analyses of these data demonstrated that factors controlling permeability also fundamentally determined the elastic and inelastic mechanical properties. We found that the number of grain contacts, or bonds, per number of grains viewed in the thin section (bond-to-grain ratio [BGR]) was a key predictive parameter of the mechanical and hydrologic properties. Although the contact length and number of contacts correlated well with the mechanical behavior, statistical analyses showed that BGR was a better predictor of strength, elastic stiffness, and fluid transport properties than was the contact length. The BGR provided a measure of the pore throat occlusion that reduced permeability and the connectivity of the grain framework that stiffened and strengthened the rock. Because porosity and BGR were typically well correlated, porosity was a more quickly and easily measured proxy for BGR in this case. However, our analysis showed that it was the microstructural changes associated with porosity loss rather than porosity loss per se that largely controlled the properties of interest. Thus, consideration of BGR as well as the relative strengths of grains and bond type (cement, pressure solution) for different compositions of sandstone and cement may constructively form the basis for comparative studies of other more complex sandstones.
Reflection waveform inversion of ground-penetrating radar data for characterizing thin and ultrathin layers of nonaqueous phase liquid contaminants in stratified media
Authors: Babcock Esther , Bradford John H.
Published: March 2015

Accurately quantifying thin-layer parameters by applying a targeted reflection waveform inversion methodology to ground-penetrating radar (GPR) reflection data may provide a useful tool for near-surface investigation and especially for contaminated site investigation where nonaqueous phase liquid (NAPL) contaminants are present. We implemented a targeted reflection waveform inversion algorithm to quantify thin-layer permittivity, thickness, and conductivity for NAPL thin ([Formula: see text] dominant wavelength [Formula: see text]) and ultrathin ([Formula: see text]) layers using GPR reflection data. The inversion used a nonlinear grid search with a Monte Carlo scheme to initialize starting values to find the global minimum. By taking a targeted approach using a time window around the peak amplitude of the reflection event of interest, our algorithm reduced the complexity in the inverse problem. We tested the inversion on three different synthetic data sets and four field data sets. In all testing, the inversion solved for NAPL-layer properties within 15% of the measured values. This algorithm provides a tool for site managers to prioritize remediation efforts based on quantitative assessments of contaminant quantity and location using GPR.
Application of 3D magnetic amplitude inversion to iron oxide-copper-gold deposits at low magnetic latitudes: A case study from Carajás Mineral Province, Brazil
Authors: Leão-Santos Marcelo , Li Yaoguo , Moraes Roberto
Published: March 2015

Strong hydrothermal alteration modifies rock physical properties in iron oxide-copper-gold deposits (IOCGs) and may result in characteristic signatures detectable in geophysical surveys. Magnetic data are commonly used in characterizing orebodies, and 3D inversions are often used to assist in interpretations. In areas with strong remanence and self-demagnetization, the total magnetization can have directions different from the inducing field direction. This deviation precludes the use of traditional inversion methods. Magnetic amplitude inversion offers one solution to this challenge because the amplitude data are weakly dependent on the magnetization direction. In addition, the low magnetic latitude also imposes difficulty in amplitude data calculation due to the instability in the component conversion in the wavenumber domain. To formulate a practical approach, we present a case study on applying the magnetic amplitude inversion to the Furnas southeast IOCG deposit at the low magnetic latitude in Carajás Mineral Province, Brazil, and demonstrate that the approach can reliably recover an interpretable distribution of effective magnetic susceptibility and identify massive magnetite from hydrothermal alterations associated with the high-grade ore.
Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection
Authors: Sun Xuekai , Sun Sam Zandong
Published: March 2015

Considering that geologic structures disturb prestack amplitude relationships, anisotropic migration is thus advocated not only for extracting azimuth-preserved common image gathers (CIGs), but also for preserving fracture-induced amplitude responses. However, most conventional anisotropic migration methods are hindered by their inefficiency in either modeling azimuthal traveltime variations at large offsets or characterizing subsurface reflections. Given that prestack time migration is widely applied for most practical purposes, we began with reformulations on a quartic traveltime formula, through which a new set of anisotropic parameters was developed. Then, an anisotropic migration method was established in the local-angle domain (LAD) for more reasonable uses of subsurface wavefield information. We also used a traveltime inversion scheme to estimate those anisotropic parameters required by anisotropic migration. Using this methodology on a physical model with a fracture medium, we derived better focused CIGs by thoroughly correcting the anisotropic effects of overburden. As a result, predicted properties of the fracture medium showed fewer interventions of geologic impacts. In a field example, a comprehensive study was performed on a deep carbonate reservoir to examine influences of different anisotropic migration algorithms on ultimate fracture prediction. Comparisons of the signal-to-noise ratio and agreements with formation microimage information reconfirmed the superiority of LAD anisotropic migration in recovering true properties of subsurface fractures, relative to routine methods (i.e., azimuth-sectored migration and anisotropic migration in the surface-offset domain).
Time-lapse monitoring of CO2 sequestration: A site investigation through integration of reservoir properties, seismic imaging, and borehole and surface gravity data
Authors: Krahenbuhl Richard A. , Martinez Cericia , Li Yaoguo , Flanagan Guy
Published: March 2015

We have developed a feasibility study on the application of time-lapse gravity as a monitoring tool for a proposed [Formula: see text] sequestration test site. The results are a component of a larger geotechnical suitability study to evaluate a specific field’s potential for [Formula: see text] storage and to evaluate viable techniques for effective monitoring there. The reservoir model for this study was constructed from detailed reservoir data available through separate reservoir characterization studies of the field. The gravity inversion used was a highly constrained binary approach that incorporated reservoir geometry from seismic data and the internal 3D distributions of density change predicted from the reservoir engineering database. Incorporating borehole data for joint surface/borehole monitoring further improved the potential of time-lapse gravity to define [Formula: see text] movement during sequestration. In this paper, we present a subset of the entire study. Our results indicate that the site likely has a favorable combination of geometry, depth, thickness, and predicted density change from [Formula: see text] movement to be effectively monitored with surface time-lapse gravity.
Time-lapse seismic performance of a sparse permanent array: Experience from the Aquistore CO2 storage site
Authors: White Don J. , Roach Lisa A. N. , Roberts Brian
Published: March 2015

A sparse areal permanent array of buried geophones was deployed at the Aquistore [Formula: see text] storage site in Saskatchewan, Canada. The purpose of this array is to facilitate 4D seismic monitoring of [Formula: see text] that is to be injected to the deep subsurface. Use of a sparse buried array is designed to improve the repeatability of time-lapse data and to economize the monitoring effort. Prior to the start of [Formula: see text] injection, two 3D dynamite seismic surveys were acquired in March 2012 and May 2013 using the permanent array. The objective of acquiring these data was to allow an assessment of the data repeatability and overall performance of the permanent array. A comparison of the raw data from these surveys and with a conventional high-resolution 3D vibroseis survey demonstrated that (1) the signal-to-noise ratio for the buried geophones was increased by 6–7 dB relative to surface-deployed geophones and by an additional 20 dB for dynamite relative to a vibroseis source, (2) the use of buried sensors and sources at this site did not appear to be significantly degraded by the effects of ghosting, (3) repeatability for the permanent array data was excellent with a mean normalized root-mean-square (nrms) value of 57% for the raw baseline-monitor difference, (4) the variance of nrms values was higher for shot gathers (18%) compared with receiver gathers (7%), and (5) the raw data repeatability was a factor of three improved over that of comparable surface-geophone data acquired at a nearby location. The use of a sparse buried permanent array at the Aquistore site has demonstrably achieved a reduction in ambient noise levels and overall enhanced data repeatability, both of which are keys to successful 4D seismic monitoring.
Transient-electromagnetic finite-difference time-domain earth modeling over steel infrastructure
Authors: Commer Michael , Hoversten G. Michael , Um Evan Schankee
Published: March 2015

Including highly conductive steel infrastructure into electromagnetic (EM) earth modeling is motivated by the fact that long metal-cased boreholes have the potential to be used as boosting antennas that enable larger source dipole moments and greater signal penetration depths. Unfortunately, geophysical algorithms designed to simulate EM responses over rather regional scales are complicated by material property contrasts and structure geometries that are more typical for EM engineering applications. Hence, the great majority of earth-modeling algorithms that consider EM responses from steel-cased boreholes use integral-equation methods. To be able to model complex casing scenarios, we revisited the finite-difference time-domain (FDTD) method to advance the modeling of transient-EM field responses from steel-cased boreholes. A time-dependent function that allows for larger FDTD time steps in the DuFort-Frankel method was developed, alleviating the generally large computational overhead. We compared our method against three different kinds of benchmark solutions to demonstrate the reliability of the FDTD field solutions. These test cases were carried out to check the feasibility of a final hydraulic fracturing study. Images of the electric current distribution in a sheetlike rock fracture were calculated for the cases with and without the presence of a connecting borehole casing, demonstrating the casing’s potential of illuminating deep target zones.
Applications of boundary-preserving seismic tomography for delineating reservoir boundaries and zones of CO2 saturation
Authors: Zhu Tieyuan , Harris Jerry M.
Published: March 2015

Delineating reservoir units is still a challenge for seismic approaches. Even high-resolution crosswell tomographic approaches that produce smooth velocity models to match traveltime data usually provide limited information about the boundaries of subsurface targets. A recent development of seismic traveltime tomography incorporated with a boundary-preserving regularization constraint promisingly helps to resolve ambiguities in reservoir boundaries, while allowing lateral variations. We applied a kind of boundary-preserving traveltime tomography to delineate boundaries of the reservoir and [Formula: see text]-saturated zones. We chose the minimum gradient support as the regularization to preserve boundaries of the geologic target by penalizing smaller model gradients and smoothing small model variations caused by noise. We evaluated several synthetic and real data applications. Synthetic examples demonstrated that the boundary-preserving algorithm produced improved recovery of the profile shape and velocity values of the blocky targets. Two real applications were for delineating the top and base of the reservoir in the King Mountain field, and for delineating a [Formula: see text]-saturated zone in the McElroy field. These inversion results suggested that the boundary-preserving inversion is able to provide better delineation of the top and base boundaries of the reservoir and boundaries of the [Formula: see text]-saturated zone than the conventional smooth-constrained inversion.
Permeability prediction based on induced polarization: Insights from measurements on sandstone and unconsolidated samples spanning a wide permeability range
Authors: Weller Andreas , Slater Lee , Binley Andrew , Nordsiek Sven , Xu Shujie
Published: March 2015

We have compared various induced polarization (IP) models for permeability prediction of the same general form that were all based on two parameters, the first being an electric substitute of effective porosity (the formation factor) and the second being an electric proxy of pore-normalized surface area (the imaginary part of electric conductivity). These models (empirically derived and based on mechanistic formulations) were applied to an extensive database acquired on sandstones and unconsolidated sandy materials. Whereas previous studies on permeability prediction mainly concentrated on either sandstone or unconsolidated sediments, we investigated a database composed of 94 samples including sandstones and unconsolidated material. Most of the samples in the database were saturated with a NaCl solution with an electric conductivity close to [Formula: see text]. Samples with a saturating fluid that deviated from this composition were corrected using recently published relationships describing the IP dependence on the pore fluid composition. In the case of the sandstone samples, the electric formation factor exerts the primary control on permeability, and the imaginary conductivity was found to be of little importance in permeability prediction. The opposite was observed for the unconsolidated samples, in which the imaginary conductivity was the most important term for permeability and the formation factor was found to be of little importance. The findings suggest that only one property (formation factor in the case of sandstone, imaginary conductivity in the case of unconsolidated samples) might be needed for the order of magnitude estimates of permeability from the popular form of the model based on the IP observations examined here. Whereas the formation factor was challenging to reliably estimate in situ, the imaginary conductivity was directly obtainable from an IP measurement. This suggests that field scale, single-frequency, IP-based estimation of permeability would be challenging, and possibly ineffective, in sandstones.
Joint Bayesian wavelet and well-path estimation in the impedance domain
Authors: Lundsgaard Astrid K. , Klemm Hanno , Cherrett Adam J.
Published: March 2015

We addressed the problem of the well-to-seismic tie as a Bayesian inversion for the wavelet and well path in the impedance domain. The result of the joint inversion is a set of wavelets for multiple angle stacks, and a corresponding well path. The wavelet optimally links the impedance data along the well to the seismic data along the optimized well path in the seismic time domain. Starting with prior distribution for wavelet and well path, the method calculates the posterior distribution of conditioning the prior distributions with the seismic and well-log data. This is done by iteratively inverting the seismic data with the current wavelet, to obtain an impedance cube around the well. In a second step, the seismic impedances are projected onto the well path. By minimizing the misfit between the inverted seismic impedances and the impedances derived from the well log, the wavelet and well path are optimized. Comparing the well and seismic data in the impedance domain enables the method to work on short and noisy well logs. Another advantage of this method is its ability to derive wavelets for multiple angle stacks and multiple well locations simultaneously. We tested the method on synthetic and real data examples. The algorithm performed well in the synthetic examples, in which we had control over the modeling wavelet, and the wavelets derived for a real data example showed consistently good seismic-to-well ties for six angle stacks and seven wells. The main algorithm we developed was aimed to linearize the problem. We compared the posterior distribution of the linearized result with a sampling-based result in a real data example and found good agreement.
Improved seismic image by Q-compensated reverse time migration: Application to crosswell field data, west Texas
Authors: Zhu Tieyuan , Harris Jerry M.
Published: March 2015

To test the effectiveness of the [Formula: see text]-compensated reverse time migration ([Formula: see text]-RTM) method, we applied it to crosswell seismic data from western Texas. This crosswell field survey was aimed at determining the boundaries and even the internal features of the reservoir. In this area, the reservoir geologic body exhibits strong attenuation that reduces high frequencies more rapidly. Thus, conventional acoustic RTM produces a dimmed image (reduced amplitude and low resolution) of the reservoir area and structures underneath. In contrast, [Formula: see text]-RTM is able to compensate for the attenuation effects during imaging. The [Formula: see text] and [Formula: see text] profiles needed for [Formula: see text]-RTM were produced by joint traveltime and frequency shift tomography. Preprocessing of the data was carried out to reduce noise, remove tube waves, and to separate up- and downgoing wavefields. Along with recovered high wavenumbers, the final [Formula: see text]-RTM image provided many details about geologic layers and structures. The lateral and vertical extent and internal structures within the reservoir unit were clearly determined. These geologic features were also correlated to the velocity profile and sonic logs. We concluded that [Formula: see text]-RTM imaging practically improved the image resolution in attenuating geologic media.
Geophysical methods used in the discovery of the Kitumba iron oxide copper gold deposit
Authors: Woolrych Thomas R. H. , Christensen Asbjorn N. , McGill Darcy L. , Whiting Tom
Published: March 2015

A range of geophysical techniques has been used at various stages of the discovery and delineation of the Kitumba deposit in Central Zambia. Early era magnetics, geologic mapping, artisanal Cu plays, and the application of an iron oxide copper gold (IOCG) exploration model led explorers to the area in the 1990s. An airborne gravity gradiometer (AGG) survey was flown in 2004, and it highlighted key regional elements considered to be prerequisite for prospective IOCG mineralization. The AGG survey accurately delineated the spatial extents of two target areas referred to as the Kitumba and Mutoya systems. Gravity, radiometric, and magnetic data sets acquired as part of the AGG survey have mapped geologic and structural information as well as the extent of the IOCG alteration system. Significant uranium anomalism in the radiometric data was identified at Kitumba upon which the discovery hole S36-001 was sited. In 2012, a 3D direct current resistivity and induced polarization survey was conducted over Kitumba. The survey results provided 3D models of induced polarization chargeability anomalism and allowed successful delineation of sulfide material within the known deposit. The survey also provided an enhanced understanding of the 3D geometry of the mineralization. This improved understanding allowed a refocusing of drilling activities to best target extensions to existing mineralization.
Introduction to this special section: Borehole geophysics and sonic logging
Authors: Smith Tad , Torres-Verdín Carlos , Cheng Arthur
Published: March 2015

Sonic logs are most frequently used to tie surface and borehole seismic amplitude measurements to P- and S-wave velocities encountered along wellbore trajectories. Other common uses of sonic logs include the estimation of dynamic elastic properties for geomechanical analysis, such as wellbore stability studies and the design and planning of hydrofracturing operations. Modern sonic logs are acquired with multiple transmitters and an array of closely spaced receivers (anywhere between eight and 13 receivers) in the form of time waveforms. Sonic transmitters can come in the form of monopole, dipole, and quadrupole actuators. By design, sonic transmitters are immersed in a fluid — the borehole mud — whereby formation shear waves can be detected and quantified only by the elastic coupling that exists between wave motion taking place in the borehole fluid and in the surrounding rock formations. Such an elastic coupling gives rise to markedly frequency-dispersive behavior of the detected waves that presents some technical challenges when one interprets their speeds.
Ultimate use of prestack seismic data: Integration of rock physics, amplitude-preserved processing, and elastic inversion
Authors: Sun Sam Zandong , Yang Pei , Liu Lifeng , Sun Xuekai , Liu Zhishui , Zhang Yuanying
Published: March 2015

Elastic information carries important data about subsurface lithology and fluid. It is highly valued by the seismic exploration industry. Compared with other methodologies (e.g., 9C VSP and 3D 3C), prestack P-wave methods are used extensively to address reservoir and fluid prediction because of their wide availability of data. However, many traditional technologies can hardly extract accurate P-wave and S-wave information from conventional prestack PP data because of lacking systematic studies on how to properly handle prestack amplitudes. A new concept, prestack elastic integration (PEI), emphasizes comprehensive interactions among rock physics, amplitude-preserved processing, and inversion algorithm. The influences of the three aspects are examined and discussed with real examples. Moreover, achievements of PEI are demonstrated through its application on a complex lithologic reservoir in eastern China, in which PEI characterizes target reservoir properties much better than traditional methods do.
The Impact of Diabetes and Diabetes Medications on Bone Health
Authors: Gilbert Matthew P. , Pratley Richard E.
Published: March 2015

Patients with type 2 diabetes mellitus (T2DM) have an increased risk of fragility fractures despite increased body weight and normal or higher bone mineral density. The mechanisms by which T2DM increases skeletal fragility are unclear. It is likely that a combination of factors, including a greater risk of falling, regional osteopenia, and impaired bone quality, contributes to the increased fracture risk. Drugs for the treatment of T2DM may also impact on the risk for fractures. For example, thiazolidinediones accelerate bone loss and increase the risk of fractures, particularly in older women. In contrast, metformin and sulfonylureas do not appear to have a negative effect on bone health and may, in fact, protect against fragility fracture. Animal models indicate a potential role for incretin hormones in bone metabolism, but there are only limited data on the impact of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 agonists on bone health in humans. Animal models also have demonstrated a role for amylin in bone metabolism, but clinical trials in patients with type 1 diabetes with an amylin analog (pramlintide) have not shown a significant impact on bone metabolism. The effects of insulin treatment on fracture risk are inconsistent with some studies showing an increased risk and others showing no effect. Finally, although there is limited information on the latest class of medications for the treatment of T2DM, the sodium-glucose co-transporter-2 inhibitors, these drugs do not seem to increase fracture risk. Because diabetes is an increasingly common chronic condition that can affect patients for many decades, further research into the effects of agents for the treatment of T2DM on bone metabolism is warranted. In this review, the physiological mechanisms and clinical impact of diabetes treatments on bone health and fracture risk in patients with T2DM are described.
Identifying the primary site of pathogenesis in amyotrophic lateral sclerosis – vulnerability of lower motor neurons to proximal excitotoxicity
Authors: Blizzard Catherine A. , Southam Katherine A. , Dawkins Edgar , Lewis Katherine E. , King Anna E. , Clark Jayden A. , Dickson Tracey C.
Published: March 2015

There is a desperate need for targeted therapeutic interventions that slow the progression of amyotrophic lateral sclerosis (ALS). ALS is a disorder with heterogeneous onset, which then leads to common final pathways involving multiple neuronal compartments that span both the central and peripheral nervous system. It is believed that excitotoxic mechanisms might play an important role in motor neuron death in ALS. However, little is known about the mechanisms by which excitotoxicity might lead to the neuromuscular junction degeneration that characterizes ALS, or about the site at which this excitotoxic cascade is initiated. Using a novel compartmentalised model of site-specific excitotoxin exposure in lower motor neurons in vitro, we found that spinal motor neurons are vulnerable to somatodendritic, but not axonal, excitotoxin exposure. Thus, we developed a model of somatodendritic excitotoxicity in vivo using osmotic mini pumps in Thy-1-YFP mice. We demonstrated that in vivo cell body excitotoxin exposure leads to significant motor neuron death and neuromuscular junction (NMJ) retraction. Using confocal real-time live imaging of the gastrocnemius muscle, we found that NMJ remodelling preceded excitotoxin-induced NMJ degeneration. These findings suggest that excitotoxicity in the spinal cord of individuals with ALS might result in a die-forward mechanism of motor neuron death from the cell body outward, leading to initial distal plasticity, followed by subsequent pathology and degeneration.
Cell cycle control of spindle pole body duplication and splitting by Sfi1 and Cdc31 in fission yeast
Authors: Bouhlel Imène B. , Ohta Midori , Mayeux Adeline , Bordes Nicole , Dingli Florent , Boulanger Jérôme , Velve Casquillas Guilhem , Loew Damarys , Tran Phong T. , Sato Masamitsu , Paoletti Anne
Published: March 2015

Spindle pole biogenesis and segregation are tightly coordinated to produce a bipolar mitotic spindle. In yeasts, the spindle pole body (SPB) half-bridge composed of Sfi1 and Cdc31 duplicates to promote biogenesis of a second SPB. Sfi1 accumulates at the half-bridge in two phases in S. pombe, from anaphase to early septation, and throughout G2 phase. We found that Sfi1/Cdc31 function in SPB duplication is accomplished before septation ends and G2 accumulation starts. Thus, Sfi1 early accumulation at mitotic exit may correspond to half-bridge duplication. We further show that Cdc31 phosphorylation on serine 15 in a CDK1 consensus is required for the dissociation of a significant pool of Sfi1 from the bridge and timely segregation of SPBs at mitotic onset. This suggests that Cdc31 N-terminus modulates the stability of Sfi1/Cdc31 arrays in fission yeast, and impacts on the timing of spindle bipolarity establishment.
Dynactin and Num1 cooperate to establish the cortical anchoring of cytoplasmic dynein inS. pombe
Authors: Fujita Ikumi , Yamashita Akira , Yamamoto Masayuki
Published: March 2015

Chromosome movement during meiosis is crucial for homologous pairing and meiotic recombination. During meiotic prophase in fission yeast, rapid nuclear migration is dependent on cytoplasmic dynein, which is anchored to the cell cortex and pulls microtubules, thereby driving nuclear migration. However, the precise mechanisms underlying dynein localization and activation remain unclear. Here, we identified three subunits of dynactin in fission yeast: Arp1, Mug5, and Jnm1/Mug1. These subunits transiently colocalized with dynein foci at the cell cortex and were essential for the cortical anchoring of dynein. Cortical factor Num1/Mcp5, which was also required for dynein anchoring, bound to dynein independently of dynactin. While Num1/Mcp5 suppressed the sliding of dynein foci along the cortex, Arp1, Mug5 and Jnm1/Mug1 were involved in the regulation of shrinkage and bundling of microtubules. From these data, we propose that dynein anchoring is established by cooperation of transient assembly of dynactin and Num1/Mcp5 at the cell cortex.
Hsp90α and Hsp90β Co-Operate a Stress-Response Mechanism to Cope With Hypoxia and Nutrient Paucity during Wound Healing
Authors: Jayaprakash Priyamvada , Dong Hangming , Zou Mengchen , Bhatia Ayesha , O'Brien Kathryn , Chen Mei , Woodley David T. , Li Wei
Published: March 2015

When tissues are injured and blood vessels clotted, the local environment becomes ischemic – lack of adequate supply of oxygen and glucose delivered to the surrounding cells. The heat shock protein-90 (Hsp90) family proteins protect tissues from various environmental insults and participate in the damaged tissue repair. Here we report discovery of a novel ischemia-responsive mechanism by which the two Hsp90 isoforms, Hsp90α and Hsp90β, work together to promote cell motility in wounded skin and accelerate wound closure. We demonstrate that Hsp90α and Hsp90β have distinct and non-exchangeable functions during wound healing. Under hypoxia and lack of serum factors, Hsp90β binds to the cytoplasmic tail of the LDL Receptor-Related Protein-1 (LRP-1) and stabilizes the receptor at the cell surface. Hsp90α, however, is secreted by the cell into extracellular space, where it binds and signals through the LRP-1 receptor to promote cell motility, leading to wound closure. In addition to skin injury, we suggest that this repair mechanism applies broadly to other non-cutaneous injured tissues.
Bat flight: aerodynamics, kinematics and flight morphology
Authors: Hedenström Anders , Johansson L. Christoffer
Published: March 2015

Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace.
Coordination between catch connective tissue and muscles through nerves in the spine joint of the sea urchin Diadema setosum
Authors: Motokawa Tatsuo , Fuchigami Yoshiro
Published: March 2015

Echinoderms have catch connective tissues that change their stiffness as a result of nervous control. The coordination between catch connective tissue and muscles was studied in the spine joint of the sea urchin Diadema setosum. Spine joints are equipped with two kinds of effector: spine muscles and a kind of catch connective tissue, which is called the catch apparatus (CA). The former is responsible for spine movements and the latter for maintenance of spine posture. Diadema show a shadow reaction in which they wave spines when a shadow falls on them, which is a reflex involving the radial nerves. Dynamic mechanical tests were performed on the CA in a joint at which the muscles were severed so as not to interfere with the mechanical measurements. The joint was on a piece of the test that contained other spines and a radial nerve. Darkening of the preparation invoked softening of the CA and spine waving (the shadow reaction). Electrical stimulation of the radial nerve invoked a similar response. These responses were abolished after the nerve pathways from the radial nerve to spines had been cut. A touch applied to the CA stiffened it and the adjacent spines inclined toward the touched CA. A touch to the base of the adjacent spine softened the CA and the spines around the touched spine inclined towards it. The softening of the CA can be interpreted as a response that reduces the resistance of the ligaments to spine movements. Our results clearly show coordination between catch connective tissue and muscles through nerves.
Comparison of Structural and Electrical Characteristics between Tetrabenzoporphyrin- and Phthalocyanine-based Charge-transfer Complexes
Authors: Nishi Miki , Matsuda Masaki , Hoshino Norihisa , Akutagawa Tomoyuki
Published: March 2015

A charge-transfer complex based on axially CN-substituted iron tetrabenzoporphyrin has been fabricated. X-ray structure analysis reveals that the differences in the distances and angles around the meso positions between tetrabenzoporphyrin and phthalocyanine are substantial between the porphin and porphyrazine frameworks. Electrical transport measurements reveal semiconducting behavior with higher activation energy due to the reduction in π–π overlapping, compared to an isostructural phthalocyanine complex.
Whole-genome mapping of 5′ RNA ends in bacteria by tagged sequencing: a comprehensive view in Enterococcus faecalis
Authors: Innocenti Nicolas , Golumbeanu Monica , Fouquier d'Hérouël Aymeric , Lacoux Caroline , Bonnin Rémy A. , Kennedy Sean P. , Wessner Françoise , Serror Pascale , Bouloc Philippe , Repoila Francis , Aurell Erik
Published: March 2015

Enterococcus faecalis is the third cause of nosocomial infections. To obtain the first snapshot of transcriptional organizations in this bacterium, we used a modified RNA-seq approach enabling to discriminate primary from processed 5′ RNA ends. We also validated our approach by confirming known features in Escherichia coli. We mapped 559 transcription start sites (TSSs) and 352 processing sites (PSSs) in E. faecalis. A blind motif search retrieved canonical features of SigA- and SigN-dependent promoters preceding transcription start sites mapped. We discovered 85 novel putative regulatory RNAs, small- and antisense RNAs, and 72 transcriptional antisense organizations. Presented data constitute a significant insight into bacterial RNA landscapes and a step toward the inference of regulatory processes at transcriptional and post-transcriptional levels in a comprehensive manner.
Analysis of MILP Techniques for the Pooling Problem
Authors: Dey Santanu S. , Gupte Akshay
Published: March 2015

The pq-relaxation for the pooling problem can be constructed by applying McCormick envelopes for each of the bilinear terms appearing in the so-called pq-formulation of the pooling problem. This relaxation can be strengthened by using piecewise-linear functions that over- and under-estimate each bilinear term. Although there is a significant amount of empirical evidence to show that such piecewise-linear relaxations, which can be written as mixed-integer linear programs (MILPs), yield good bounds for the pooling problem, to the best of our knowledge, no formal result regarding the quality of these relaxations is known. In this paper, we prove that the ratio of the upper bound obtained by solving piecewise-linear relaxations (objective function is maximization) to the optimal objective function value of the pooling problem is at most n, where n is the number of output nodes. Furthermore for any ϵ > 0 and for any piecewise-linear relaxation, there exists an instance where the ratio of the relaxation value to the optimal value is at least n − ϵ. This analysis naturally yields a polynomial-time n-approximation algorithm for the pooling problem. We also show that if there exists a polynomial-time approximation algorithm for the pooling problem with guarantee better than n1−ϵ for any ϵ > 0, then NP-complete problems have randomized polynomial-time algorithms. Finally, motivated by the approximation algorithm, we design a heuristic that involves solving an MILP-based restriction of the pooling problem. This heuristic is guaranteed to provide solutions within a factor of n. On large-scale test instances and in significantly lesser time, this heuristic provides solutions that are often orders of magnitude better than those given by commercial local and global optimization solvers.