bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the Inter-Relationship of Key Parameters in Unconventional Shale Reservoirs Using Analytical Solutions
Authors: Lalehrokh F. , Jayakumar R. , Lawal H.
Published: August 2013

Gas shales have become an attractive target due to their huge resource of 500 to 780 TCF. Due to the complexity of shale gas reservoirs and their ultra-low nano Darcy permeabilities, they are termed as ‘unconventional’ reservoirs. Contact to a large reservoir surface area is necessary to produce oil or gas at sustainable rates. Improvements in horizontal drilling and massive hydraulic fracturing technology have made economic extraction of these "unconventional" reservoirs feasible.

The scope of this paper is to illustrate methodology for analyzing rate-time and pressure data from horizontal wells with multiple hydraulic transverse fractures. Three distinctive scenarios are considered for a single shale gas well. The implications of multiple interpretations for the same well are discussed in detail. First scenario considers the well in internal linear transient flow with a large stimulated reservoir volume (SRV) and drainage area requirement and the implications that arise with this assumption. The second scenario considers the well is in depletion flow period but this transition has happened later in the life of the well. The third scenario considers the well has gone to an early transition period which implies high reservoir permeability (K) and small effective fracture half-length, i.e., a possibility of contribution from natural fractures in the vicinity of the wellbore. Each scenario has been analyzed in detail to demonstrate an easy step by step approach to understand the implication of multiple interpretations on the overall well performance. This approach will help us understand a common problem that is mostly overlooked which is the reservoir contribution outside the SRV - external reservoir volume (XRV).

The outcome of each of the mentioned scenarios is distinctive. Therefore choosing the right scenario for the well is very critical. In order to wisely choose the correct scenario, a combination of various parameters such as: XRV size, current well flow regime, the time that well has gone to depletion, available drainage area, presence of natural fractures and matrix permeability must be considered. In this paper, the impact of the aforementioned parameters on well performance analysis, reservoir assessment and field development is analyzed in-depth.
An Examination of Infill and Offset Drilling Patterns on Field Development for Shale Wells
Authors: Sahai Vivek , Jackson Greg , Lalehrokh Farshad , Rai Rakesh
Published: August 2013

Capital expenditures, personal and equipment resources, acreage lease restrictions, and market conditions strongly influence drilling and development plans for shale resources. Delaying the start of new wells is understood to reduce the NPV of a section but variations in the arrangement of infill wells in a section have not been thoroughly examined to date.

In this paper, the impact of timing and pattern of well placement on NPV, and recovery factor at an optimal number of wells per section is studied. The sensitivities included wells with a small amount of stimulated reservoir volume (SRV) overlap. To study the drilling/infill pattern, three limiting scenarios were evaluated, i.e. an infill scheme where future wells are drilled between existing wells, a linear scheme where future wells are immediate offsets of existing wells, and a hybrid scheme that is a combination of the infill and linear schemes. Four different start times of future wells were evaluated to determine impact of timing.

The results show EUR is relatively insensitive to the drilling schedule. The section recovery factor can be conserved as long as all the wells are drilled in a reasonable amount of time. A quantification of the NPV reduction as a result of the order and scheduling of wells is presented. These results illustrate once a threshold of total cumulative production from a section is achieved, infill wells may not be economic and thus should be carefully considered.

The results of the study are a resource to aid operators in understanding the impact of well spacing as shale plays mature from being in the appraisal phase to the field development phase. Knowledge of how development decisions impact optimal resource development will allow operators to adapt their drilling plans to maximize their return on investment.
Experimental and Numerical Studies on the Micro-fractures and its Significance Toward Production of Shales: A Case Study
Authors: Wei Chenji , Wang Yuhe , Qin Guan , Li Qianyao , Killough John
Published: August 2013

The mechanisms of shale gas storage and flow are complex. Understanding the microstructure is an important step for evaluating a new shale gas play toward accurate reserve estimation and recovery prediction. The emphasis of this paper is study on the micro-fractures observed on the research shale formation.

The approaches involved in this study include experimental study and numerical modeling. Longmaxi Shale, which is an emerging Lower Silurian marine shale gas play in China with huge potential according to preliminary explorations, is the research formation in this paper. Core samples used in the experiment are collected from the target layer of Longmaxi Shale. The pore structure is visualized in nano-scale using Scanning Electron Microscope (SEM). In order to evaluate the influence of micro-fracture, a micro-model is built to explicitly simulate the micro-factures. The effect of micro-fracture on gas drainage capacity of shale matrix is then scaled up to a well model using a triple porosity approach.

SEM images reveal well-developed micro-fractures on the Longmaxi Shale. Micro-fractures exhibit strong heterogeneity. The width, length and connectivity of the micro-fractures vary notably. This feature is believed can significantly influent the gas drainage capacity of shale matrix and as a result well performance. Sensitivity analysis is conducted by varying micro-fracture density, width, length and connectivity. Results show that micro-fracture plays an important role in production performance. This is because that the well-developed micro-fractures enhance the gas drainage capacity of shale matrix. Thus, micro-fractures observed in Longmaxi Shale have to be considered in evaluating potentials of this new shale gas play.

This study characterizes the microstructure of Longmaxi Shale and discusses the significance of micro-fractures, which provides important information to support engineers and geologist for better understanding the marine shale and optimizing production plan on the marine shale.
How Natural Fractures Could Affect Hydraulic-Fracture Geometry
Authors: Taleghani Arash Dahi , Olson Jon E.
Published: August 2013

Hydraulic fracturing is recognized as the main stimulating technique to enhance recovery in tight fissured reservoirs. These fracturing treatments are often mapped by use of hypocenters of induced microseismic events. In some cases, the microseismic mapping shows asymmetry of the induced-fracture geometry with respect to the injection well. In addition, the conventional theories predict fracture propagation along a path normal to the least compressive in-situ stresses, whereas in some cases the microseismic data suggest fracture propagation parallel to the minimum compressive stress. In this paper, we present an extended-finite-element-method (XFEM) model that can simulate asymmetric fracture-wing development as well as diversion of the fracture path along natural fractures. Simulation results demonstrate the sensitivity of the fracture-pattern geometry to differential stress and natural-fracture orientation with respect to the in-situ maximum compressive stress. We examine the properties of sealed natural fractures that are common in formations such as the Barnett shale and show that they may still serve as weak paths for hydraulic-fracture beginning and/or diversion. The presented model predicts faster fracture propagation in formations where natural fractures are favorably aligned with the tectonic stresses.
Reducing life-cycle carbon footprints in the redesign of water distribution systems
Authors: Basupi Innocent , Kapelan Zoran , Butler David
Published: August 2013

Water distribution systems (WDSs) contribute to undesirable greenhouse gas (GHG) emissions that are generated through their component fabrication, construction, operation and disposal processes. The concentration of GHGs in the atmosphere is strongly associated with global warming and climate change. In order to meet the consequent challenge of limiting GHG emissions, the problem of WDS redesign is formulated here as a multi-objective optimisation problem. The three objectives are as follows: (1) minimisation of total redesign cost, (2) maximisation of the WDS resilience, and (3) minimisation of GHG emissions. The resilience index serves as a measure of the WDS's intrinsic capability to ensure continuity of supply to users after sudden failure conditions, whilst the GHG emissions serve as a measure of environmental performance and climate change mitigation. The output from the non-dominated sorting genetic algorithm (NSGA2) optimisation process is a Pareto front containing optimal solutions traded-off in terms of the three objectives analysed. This methodology was applied on the New York Tunnels and the Anytown Network problems. The results obtained demonstrate that the redesign approach leads to cost-effective and resilient solutions that can also mitigate climate change compared with the single-objective (least cost) and other multi-objective redesigns over the long-term planning horizon.
A hydrological perspective on evaporation: historical trends and future projections in Britain
Authors: Kay A. L. , Bell V. A. , Blyth E. M. , Crooks S. M. , Davies H. N. , Reynard N. S.
Published: August 2013

Evaporation is an important component of the hydrological cycle. Potential evaporation (PE) from a vegetated surface is the amount of water that would be lost to the atmosphere were the supply unlimited; actual evaporation (AE) is a fraction of PE dependent on soil wetness. Many formulae exist for estimating PE from meteorological data. PE is usually a required input, with rainfall, for hydrological modelling, but PE accuracy is generally considered less important than rainfall accuracy for model performance. Few studies investigate historical evaporation trends in Britain, but generally indicate increases. Most studies presenting future PE projections for Britain indicate increased annual PE, but some suggest small decreases in some months. Limited consensus on the best formulae to derive PE projections from climate model data is further complicated by possible changes in plant behaviour (transpiration and growth) under higher carbon dioxide concentrations. Appropriate PE estimation could be particularly important in regions where precipitation and PE are in close balance, but PE uncertainty could be less important than climate model uncertainty for hydrological impacts. Further research is needed into which PE formulae are likely to be most reliable when applied with climate model data, and into climate change and plant feedbacks.
Climate projection ensemble as support to water management and irrigation in Nigeria
Authors: Santini M. , Valentini R. , Cervigni R.
Published: August 2013

Hydrological modeling was used for projecting average annual water availability in Nigeria in the future, comparing a baseline (1976–2005) with a 30-year future (2036–2065) period, simulated under an ensemble of ten climate projections. Simulations converged in projecting by mid-century an increase in water flows for almost half of the country. Models agreed also in projecting decrease and stability in water flows for 13% of the country, while uncertainty covers about one-third of Nigeria. Lack of agreement among different climate models on precipitation and inflow makes it difficult to project how much water will be effectively available in the future for irrigation. Reservoir size is usually designed to ensure sufficient storage providing a given yield based on past climate. The objective of this paper is evaluating what storage investments are suitable for meeting irrigation development targets under as many climate outcomes as possible. A simple methodology for more robust investment planning is suggested and the risk of over- or under-designing storage based on past climate is exemplified. This preliminary study shows that, for more than half of the country, using the historical climate as a guide to the design of future storage might lead to inappropriate investment decisions, resulting in excessive or insufficient capital outlays. The conclusions of the paper do not entail endorsement by the World Bank or its Board of Directors.
Integrated modelling of a coupled water-agricultural system using system dynamics
Authors: Sušnik Janez , Vamvakeridou-Lyroudia Lydia S. , Savić Dragan A. , Kapelan Zoran
Published: August 2013

An integrated System Dynamics Model for the water-stressed Rosetta region, Egypt, assessing water balance, and agricultural yield and revenue to 2050, is presented. The study uses 57 simulations to better understand impacts on water, food and economic security and their interactions, in order to highlight potential pathways towards a more sustainable future for the Rosetta region. Current water resource over-exploitation can be mitigated while still allowing for agricultural development. The utility of the system dynamics paradigm in modelling complex systems is highlighted, with the potential to extend the methodology to other studies. While most simulations hinted at continued over-exploitation, some suggest that improvements can be achieved by altering parameters such as per-capita domestic water demand and/or the cropping regime. Many policies should be considered in parallel to introduce redundancy into the policy framework. From initial results, it was hypothesised that by producing excess crops, international markets could be exploited, leading to further improvements in the water balance, yield and revenue. A model extension was built which suggested that improvements are possible, furthering local development. However, these improvements would probably manifest after years, have to be managed carefully, and would increase reliance on other countries.
The Effect of Audit Committee Industry Expertise on Monitoring the Financial Reporting Process
Authors: Cohen Jeffrey R. , Hoitash Udi , Krishnamoorthy Ganesh , Wright Arnold M.
Published: August 2013

Calls from practice suggest that audit committee members with industry expertise can improve audit committee effectiveness. Nevertheless, regulators and the extant literature have focused on the financial expertise of the audit committee. We posit that audit committee industry knowledge is valuable because accounting guidance, estimates, and oversight of the external auditor are often linked to a company's operations within a particular industry. Taking a holistic view, we examine two measures of financial reporting quality (financial restatements and discretionary accruals) and two measures of external auditor oversight (audit and nonaudit fees). As predicted, we find that audit committee members who are both accounting and industry experts perform better than those with only accounting expertise. We also find that in certain instances, supervisory experts who are also industry experts perform better than supervisory experts alone. Overall, these results suggest that industry expertise, when combined with accounting expertise, can improve the effectiveness of the audit committee in monitoring the financial reporting process.

Data Availability: All data are gathered from publicly available sources.
Real Activities Manipulation and Auditors' Client-Retention Decisions
Authors: Kim Yongtae , Park Myung Seok
Published: August 2013

In this study, we examine the effect of clients' real activities manipulation (RAM) on auditors' client-retention decisions. We find that, with the exception of RAM through overproduction, clients' opportunistic operating decisions are positively associated with the likelihood of auditor resignations. We also provide evidence that auditors are especially sensitive to clients' RAM to just meet or beat earnings benchmarks in their client-retention decisions. In addition, we find that clients whose auditors resign from engagements tend to hire smaller auditors and these clients engage in RAM more aggressively. Our additional analysis shows that, with the exception of RAM through overproduction, clients' abnormal operating decisions are significantly associated with litigation risk against auditors. Overall, our evidence suggests that auditors drop clients with aggressive RAM to avoid excessive risk.

Data Availability: Data used in this study are available from public sources identified in the study.
Real-Time Support of Pediatric Diabetes Self-Care by a Transport Team
Authors: Franklin Brandi E. , Crisler S. Crile , Shappley Rebekah , Armour Meri M. , McCommon Dana T. , Ferry Robert J.
Published: August 2013

OBJECTIVE

The study seeks to improve access for underserved patients via novel integration of Pedi-Flite (a critical care transport team) and to validate whether this safely enhances diabetes care and effectively expands the endocrine workforce.

RESEARCH DESIGN AND METHODS

The study retrospectively analyzed pager service use in a cohort of established diabetic patients (n = 979) after inception of Pedi-Flite support. Outcomes included incidence and severity of recurrent diabetic ketoacidosis (DKA) and cost savings generated from reduced referrals to the emergency department (ED) and on-call endocrinologist. We generated descriptive statistics to characterize the study population and ED visits for DKA and constructed logistic regression models to examine associations of pager use and likelihood of ED visitation and nonelective inpatient admission from an ED for DKA.

RESULTS

Pager users comprised 30% of the patient population. They were younger but had more established diabetes than nonusers. While pager users were 2.75 times more likely than nonusers to visit the ED for DKA (P < 0.0001), their visits were less likely to lead to inpatient admissions (odds ratio 0.58; P < 0.02). More than half (n = 587) of all calls to the pager were resolved without need for further referral. Estimates suggest that 439 ED visits and 115 admissions were avoided at a potential cost savings exceeding 760,000 USD.

CONCLUSIONS

Integration of a transport service provides a novel, cost-effective approach to reduce disparities in diabetes care. Advantages include scalability, applicability to other disease areas and settings, and low added costs. These findings enrich an emerging evidence base for telephonic care-management models supported by allied health personnel.
Measuring Maslow's Hierarchy of Needs
Authors: Lester David
Published: August 2013

Two scales have been proposed to measure Maslow's hierarchy of needs in college students, one by Lester (1990) and one by Strong and Fiebert (1987). In a sample of 51 college students, scores on the corresponding scales for the five needs did not correlate significantly and positively, except for the measures of physiological needs. Furthermore, there was limited support for Maslow's hypothesis that need deprivation would predict psychopathology (specifically, mania and depression).
Making Inferences about Intention: Perceptual Control Theory as a “Theory of Mind” for Psychologists
Authors: Marken Richard S.
Published: August 2013

Theory of Mind (ToM) assumes that humans and possibly other primates understand behavior in terms of inferences about intentions. While there is evidence that primates make such inferences, little attention has been paid to the question of their validity. In order to answer this question it is necessary to know the true intentions underlying behavior. The present paper shows that Perceptual Control Theory can provide a scientific basis for making such determinations using methods derived from control engineering. These methods—called the “Test for the Controlled Variable” (TCV)—are based on the assumption that intentional behavior is equivalent to the process of control. The TCV provides an objective approach to inferring the intentions underlying behavior in terms of the perceptual variables under control and the goal states of those variables. Thus, Perceptual Control Theory represents an empirical ToM for psychologists—one that can be used to understand behavior in terms of inferences about intention that are based on the results of active experimentation rather than passive observation.
Exploring Individual Differences in Children's Mathematical Skills: A Correlational and Dimensional Approach
Authors: Sigmundsson H. , Polman R. C. J. , Lorås H.
Published: August 2013

Individual differences in mathematical skills are typically explained by an innate capability to solve mathematical tasks. At the behavioural level, this implies a consistent level of mathematical achievement that can be captured by strong relationships between tasks, as well as by a single statistical dimension that underlies performance on all mathematical tasks. To investigate this general assumption, the present study explored interrelations and dimensions of mathematical skills. For this purpose, 68 ten-year-old children from two schools were tested using nine mathematics tasks from the Basic Knowledge in Mathematics Test. Relatively low-to-moderate correlations between the mathematics tasks indicated most tasks shared less than 25% of their variance. There were four principal components, accounting for 70% of the variance in mathematical skill across tasks and participants. The high specificity in mathematical skills was discussed in relation to the principle of task specificity of learning.
Inner Dialogue and its Relationship to Perceived Exertion during Different Running Intensities
Authors: Aitchison Callum , Turner Louise A. , Ansley Les , Thompson Kevin G. , Micklewright Dominic , Gibson Alan St Clair
Published: August 2013

This study examined the effect of low- and high-intensity running on cognitive thoughts (an individual's “inner dialogue”) and its relationship to ratings of perceived exertion (RPE). Cognitive thoughts and RPE of eight runners were collected during a 40-min. treadmill run at either a low (50% peak running speed) or a high (70% peak running speed) exercise intensity. Runners were asked to place their thoughts into one of 10 themed categories, which incorporated a broad association/dissociation classification (Schomer, 1986, 1987). At a low intensity and RPE (6–10), runners reported more dissociative thoughts, while at a high intensity and RPE (16–20) they reported more associative thoughts. Further, although the runners may report a particular RPE, the inner dialogue and description of perceived exertion and fatigue may be markedly different. These findings suggest that an athlete's “internal dialogue” is intensity dependent, and may relate to the more urgent need to self-monitor physical changes and sensations during high-intensity running.
Bender Visual-Motor Gestalt Test in Adolescents: Relationship between Visual-Motor Development and the Tanner Stages
Authors: Keppeke Lívia de Freitas , Cintra Isa de Pádua , Schoen Teresa Helena
Published: August 2013

Visual-motor skill is fundamental to human development and is an important component of psychological evaluations. The goal of the present study was to determine whether there is a correlation between visual-motor development, as measured by the Bender Visual-Motor Gestalt Test (Bender test), and sexual maturity in adolescents, based on the Tanner Stages in Adolescents. 134 adolescents from 10 to 15 years of age participated in the study. The Bender test and the Raven's Progressive Matrices Test were employed. The measures were administered individually and information on sexual maturity and the presence of developmental disorders was collected from medical charts. The results of the Bender test were not affected by gender, age, schooling, or changes stemming from puberty, but were significantly affected by having repeated a school year and by developmental disorders. An association was found with Raven's scores. The Bender test proved sensitive to developmental disorders in adolescence. No association was found between visual-motor development and sexual maturity in adolescents.
The Effect of Facial Makeup on the Frequency of Drivers Stopping for Hitchhikers
Authors: Guéguen Nicolas , Lamy Lubomir
Published: August 2013

Judgments of photographs have shown that makeup enhances ratings of women's facial attractiveness. The present study assessed whether makeup affects the stopping behavior of drivers in response to a hitchhiker's signal. Four 20- to 22-year-old female confederates wore facial makeup, or not, while pretending to be hitchhiking. Frequency of stopping was compared in 1,600 male and female drivers. Facial makeup was associated with an increase in the number of male drivers who stopped to offer a ride. Makeup did not affect frequency of stopping by female drivers.
What can we Learn from Studies Based on Small Sample Sizes? Comment on Regan, Lakhanpal, and Anguiano (2012)
Authors: Johnson David R. , Bachan Lauren K.
Published: August 2013

In a recent article, Regan, Lakhanpal, and Anguiano (2012) highlighted the lack of evidence for different relationship outcomes between arranged and love-based marriages. Yet the sample size ( n = 58) used in the study is insufficient for making such inferences. This reply discusses and demonstrates how small sample sizes reduce the utility of this research.
Similarity Facilitates Relationships on Social Networks: A Field Experiment on Facebook
Authors: Martin Angélique , Jacob Céline , Guéguen Nicolas
Published: August 2013

People interact more readily with someone with whom they think they have something in common, but the effect of an incidental similarity has never been examined on social networks. Facebook users were contacted by a stranger who also possessed a Facebook page and who asked them to become his friend. The request message contained one item of similarity, two items of similarity, or none. Compliance to the request was the dependent variable. Increased compliance to the request was found when comparing the two similarity conditions with the control no-similarity condition. However, no difference was found between the two similarity conditions. Similarity appears to foster relationships on social networks.
Reaction Time following Yoga Bellows-Type Breathing and Breath Awareness
Authors: Telles Shirley , Yadav Arti , Gupta Ram Kumar , Balkrishna Acharya
Published: August 2013

The reaction time (RT) was assessed in two groups of healthy males, yoga group ( M age = 29.0 yr.) and non-yoga or control group ( M age = 29.0 yr.), with 35 participants each. The yoga group had an average experience of 6 months, while the control group was yoga-naïve. The yoga group was assessed in two sessions, (i) bhastrika pranayama or bellows breathing and (ii) breath awareness, while the control group had a single control session. The two experimental sessions, one with each type of breathing, and the control session consisted of pre- (5 min.), during (18 min.), and post-session epochs (5 min.). Assessments were made in the pre- and post-session epochs using a Multi-Operational Apparatus for Reaction Time. Following 18 min. of bhastrika pranayama there was a statistically significant reduction in number of anticipatory responses compared to before the practice. This suggests that the immediate effect of bhastrika pranayama is to inhibit unnecessary responding to stimuli.
Creating a Framework for Experimentally Testing Early Visual Processing: A Response to Nurmoja, et al. (2012) on Trait Perception from Pixelized Faces
Authors: Carbon Claus-Christian
Published: August 2013

Nurmoja, Eamets, Härma, and Bachmann (2012) revealed that strongly pixelated pictures of faces still provide relevant cues for reliably assessing the apparent (i.e., subjectively perceived) traits of the portrayed. The present article responds to the paper by developing the outline of a framework for future research to reveal certain steps in processing complex visual stimuli. This framework combines the approach of degradation of the stimuli with the so-called microgenetic approach of percepts based on presentation time limitations. The proposed combination of a particular kind of stimulus manipulation and a specific experimental procedure allows testing targeted assumptions concerning visual processing, not only in the domain of face perception, but in all domains involving complex visual stimuli, for example, art perception.
Effects of Focus of Attention and Type of Practice on Learning and Self-Efficacy in Dart Throwing
Authors: Shafizadeh Mohsen , Platt Geoffrey K. , Bahram Abbas
Published: August 2013

The present investigation studied the effect of focus of attention and type of practice on self-efficacy and learning during a demonstration of the dart-throwing skill. 48 university students ( M = 22.5 yr., SD = 3.6) without any experience of dart throwing were divided into four groups according to the type of practice (physical and observational) and focus of attention (internal and external) and practiced a dart-throwing task. Self-efficacy in dart throwing was measured at the pre-test, acquisition, and transfer phases. The internal-focus group concentrated on their limb function, whereas the external-focus group concentrated on the darts and the target during the demonstration. Observational groups only watched during the acquisition phase, then performed the task in the retention and transfer phases. There was a main effect of focus of attention in the retention and transfer phases after controlling self-efficacy, with external focus groups showing higher performance than internal focus groups. External focus of attention could facilitate the acquisition of a motor skill during observation and may build and/or be supported by self-efficacy.
Perception of Weight-Bearing and Effort Distribution during Sit-to-Stand in Individuals Post-Stroke
Authors: Brière Anabèle , Nadeau Sylvie , Lauzière Séléna , Gravel Denis
Published: August 2013

The objectives were to assess whether individuals who are post-stroke can rate their perceived knee effort distribution during sit-to-stand tasks in various foot positions, to quantify their errors of perception and to compare these to their errors in weight-bearing perception. Weight-bearing distribution was assessed in hemiparetic participants ( N = 19) using a force platform. Electromyographic (EMG) data normalized to maximal EMG values were used to quantify knee effort distribution. The difference between participants' real weight bearing and knee effort and the perceived values rated on a visual analog scale defined their errors of weight-bearing and effort perception. The perception of effort and weight bearing, and the errors therein, were compared among the four foot positions. Participants perceived only the changes induced by the different foot positions on their weight-bearing distribution, not on their knee effort distribution, and they made greater perception errors with the knee effort distribution than with the weight-bearing distribution.
Immediate Effect of Visual Attention on Corticospinal Excitability in the Upper Trapezius Muscle
Authors: Hiraoka Koichi , Mori Nobuhiko , Horino Hiroshi
Published: August 2013

This study investigated the immediate effect of visual attention on corticospinal excitability in the upper trapezius muscle. 10 healthy males gazed at a horizontal bar. A warning tone, indicating that a line would be slightly displaced 7,400 msec. later, was delivered in the high-attention-demand condition. A different warning tone, indicating the line would not be displaced, was delivered in the low-attention-demand condition. Participants verbally declared the direction of line displacement in the high-attention-demand condition, or stated that the warning tone meant that the line would not be displaced in the low-attention-demand condition. The amplitude of the motor-evoked potential in the upper trapezius muscle increased 7,000 msec. after the warning tone in the high-attention-demand condition. Apparently, visual attention immediately increases corticospinal excitability in the upper trapezius muscle.
Coherent excitation of a nonlinear microcavity
Authors: Oden J. , Trebaol S. , Delaye P. , Dubreuil N.
Published: August 2013

Coherent excitation of a nonlinear semiconductor microcavity is theoretically reported. It intends to counterbalance the frequency drift of the cavity resonance driven by the nonlinear refractive effects, which causes a limitation in the energy coupling efficiency of an input pulse into the cavity resonance. We show that exciting such a nonlinear microcavity with tailored chirped pulses allows to maintain the benefit of light localization and to further enhance light-matter interactions, opening the way to the realization of highly efficient nonlinear devices.
The phase shift induced by a single atom in free space
Authors: Sondermann M. , Leuchs G.
Published: August 2013

In this article we theoretically study the phase shift a single atom imprints onto a coherent state light beam in free space. The calculations are performed in a semiclassical framework. The key parameters governing the interaction and thus the measurable phase shift are the solid angle from which the light is focused onto the atom and the overlap of the incident radiation with the atomic dipole radiation pattern. The analysis includes saturation effects and discusses the associated Kerr-type non-linearity of a single atom.
Self-tuning laser speckle contrast analysis based on multiple exposure times with enhanced temporal resolution
Authors: Zölei D. , Smausz T. , Hopp B. , Bari F.
Published: August 2013

Laser Speckle Contrast Analysis (LASCA) was introduced in 1981. Since then, several enhancements were applied to it. Nowadays, the technique can provide relatively high accuracy as well as high temporal and spatial resolution during the examination of ocular or cerebral tissues. However, in the case of skin, the results are highly affected by the intensive scattering on the skin surface, as the scattering on the non-moving parts of the sample lead to the detrimental decrease of the accuracy. We present a LASCA method based on the use of multiple exposure times, combined with the switching-mode control of the light intensity and a special sampling technique to achieve near to real-time measurement of the skin perfusion. The system based on our method is able to automatically handle the destructive effect of the skin surface and re-tune itself according to the changes of the sample, while it provides full-field perfusion maps with high accuracy, without the need of any precalibrations.
Continuous cerebral spinal fluid drainage associated with complications in patients admitted with subarachnoid hemorrhage
Authors: Olson DaiWai M. , Zomorodi Meg , Britz Gavin W. , Zomorodi Ali R. , Amato Anthony , Graffagnino Carmelo
Published: August 2013

Object

Cerebral artery vasospasm is a major cause of death and disability in patients recovering from subarachnoid hemorrhage (SAH). Although the exact cause of vasospasm is unknown, one body of research suggests that clearing blood products by CSF drainage is associated with a lower frequency and severity of vasospasm. There are multiple approaches to facilitating CSF drainage, but there is inadequate evidence to determine the best practice. The purpose of this study was to explore whether continuous or intermittent CSF drainage was superior for reducing vasospasm.

Methods

The authors performed a randomized clinical trial. Within 72 hours of admission for SAH, patients with an external ventricular drain (EVD) were randomized to undergo continuous CSF drainage with intermittent intracranial pressure (ICP) monitoring (open-EVD group) or continuous ICP monitoring with intermittent CSF drainage (monitor-ICP group).

Results

After 60 patients completed the study, an interim analysis was performed. The complication rate of 52.9% for the open-EVD group was significantly higher than the 23.1% complication rate for the monitor-ICP group (OR 3.75, 95% CI 1.21–11.66, p = 0.022). These results were reported to the Data Safety and Monitoring Board and enrollment was terminated. The odds ratio of vasospasm for the open-EVD versus monitor-ICP group was not significant (OR 0.44, 95% CI 0.13–1.45, p = 0.177).

Conclusions

Continuous CSF drainage with intermittent ICP monitoring is associated with a higher rate of complications than continuous ICP monitoring with intermittent CSF drainage, but there is no difference between the two types of monitoring in vasospasm. Clinical trial registration no.: NCT01169454 (clinicaltrials.gov).
The Cysteine Protease–Cysteine Protease Inhibitor System Explored in Soybean Nodule Development
Authors: Vorster Barend , Schlüter Urte , Du Plessis Magdeleen , Van Wyk Stefan , Makgopa Matome , Ncube Ignatious , Quain Marian , Kunert Karl , Foyer Christine
Published: August 2013

Almost all protease families have been associated with plant development, particularly senescence, which is the final developmental stage of every organ before cell death. Proteolysis remobilizes and recycles nitrogen from senescent organs that is required, for example, seed development. Senescence-associated expression of proteases has recently been characterized using large-scale gene expression analysis seeking to identify and characterize senescence-related genes. Increasing activities of proteolytic enzymes, particularly cysteine proteases, are observed during the senescence of legume nodules, in which a symbiotic relationship between the host plant and bacteria (Rhizobia) facilitate the fixation of atmospheric nitrogen. It is generally considered that cysteine proteases are compartmentalized to prevent uncontrolled proteolysis in nitrogen-fixing nodules. In addition, the activities of cysteine proteases are regulated by endogenous cysteine protease inhibitors called cystatins. These small proteins form reversible complexes with cysteine proteases, leading to inactivation. However, very little is currently known about how the cysteine protease-cysteine protease inhibitor (cystatin) system is regulated during nodule development. Moreover, our current understanding of the expression and functions of proteases and protease inhibitors in nodules is fragmented. To address this issue, we have summarized the current knowledge and techniques used for studying proteases and their inhibitors including the application of “omics” tools, with a particular focus on changes in the cysteine protease-cystatin system during nodule development.
Effects of Pseudomonas fluorescens on the Water Parameters of Mycorrhizal and Non-Mycorrhizal Seedlings of Pinus halepensis
Authors: Domínguez-Núñez José , Muñóz Daniel , De la Cruz Ana , Saiz de Omeñaca José
Published: August 2013

Inoculation of forest seedlings with mycorrhizal fungi and rhizobacteria can improve the morphological and physiological qualities of plants, especially those used for regeneration of arid areas. In this paper, under standard nursery conditions, Aleppo pine seedlings were inoculated with Pseudomonas fluorescens CECT 5281 rhizobacteria. Some of these seedlings were also inoculated with the ectomycorrhizal fungus Pisolithus tinctorius. Five months after the inoculations, we examined the growth, water parameters (osmotic potential at full turgor [Ψπfull], osmotic potential at zero turgor [Ψπ0], and the tissue modulus of elasticity near full turgor [Emax]), mycorrhizal colonisation, and concentration of macronutrients (N, P, K, Ca and Mg) in the seedlings. Subsequently, a trial was conducted to assess the root growth potential. P. fluorescens CECT 5281 decreased the cellular osmotic potential of P. halepensis seedlings but increased its elasticity. P. tinctorius + P. fluorescens caused osmotic adjustment at zero turgor and increased tissue elasticity, which improved tolerance to water stress. All inoculations improved the growth and nutrition of the seedlings but caused non-significant effects on root growth potential. The co-inoculation Pisolithus tinctorius + Pseudomonas fluorescens at the nursery may be a suitable technique for producing improved seedling material for restoration purposes.
Extension Agrometeorology as the Answer to Stakeholder Realities: Response Farming and the Consequences of Climate Change
Authors: Stigter Kees , Winarto Yunita , Ofori Emmanuel , Zuma-Netshiukhwi Gugulethu , Nanja Durton , Walker Sue
Published: August 2013

Extension agrometeorology is applied in agrometeorological extension work to advice and serve farmers. In agrometeorology, response farming has been developed decades ago. Climate change complicates response farming, but does not alter it. This paper reports on new operationalization of that response farming in new educational commitments in agroclimatology. It is explained how “Science Field Shops” are an example in Indonesia. This was based on a thorough analysis of what climate change means for farmers in Asia. For Africa, we report on eying the training of agrometeorological extension trainers (“product intermediaries”) in West Africa, based on a thorough analysis of what climate change means for farmers in Africa. We also compare experience with reaching farmers in South Africa and farmer communities in Zambia, as new forms of supporting response farming, all under conditions of a changing climate. The paper, for the first time, connects results from four different programs the senior author is taking part in. There is first and foremost the need for training material to make it possible for the product intermediaries to participate in training extension intermediaries. This should, particularly, bring new knowledge to farmers. With what is presently available and with new approaches, climate extension should be developed and tested with farmers in ways that improve farmer preparedness and decision making.
A Dynamic Model for the Normal Impact of Fly Ash Particle with a Planar Surface
Authors: Dong Ming , Han Jian , Li Sufen , Pu Hang
Published: August 2013

The rebound behavior of fly ash particles normally impacting a planar surface is investigated by using a dynamic model. The three forms of soft sphere physical model are obtained using static/quasi-static contact mechanics and energy dissipation theory. The influences of the particle size, the incident velocity of the particle on the damping coefficient and the impact contact time are all examined. We also predict the critical velocity for three particle sizes. It is found that the variation of the damping coefficient (η) with the normal incident velocity (vin) can be roughly divided into the three parts. In the first part, η decreases with increasing vin. In the second part, η is little changed with increasing vin. In the third part, η rapidly increases with increasing vin. For smaller impact velocities, the viscoelastic effect plays a dominant role in the impact process, while for higher incident velocities; the energy dissipation depends mainly on plastic deformation. In addition, the critical velocity shows a distinct dependence on the particle size. Finally, the contact displacement-contact time curves are examined. The work provides a solid basis for the development of a discrete-element-method approach to study ash deposition.
Homoserine Lactones Influence the Reaction of Plants to Rhizobia
Authors: Zarkani Azhar , Stein Elke , Röhrich Christian , Schikora Marek , Evguenieva-Hackenberg Elena , Degenkolb Thomas , Vilcinskas Andreas , Klug Gabriele , Kogel Karl-Heinz , Schikora Adam
Published: August 2013

Bacterial quorum sensing molecules not only grant the communication within bacterial communities, but also influence eukaryotic hosts. N-acyl-homoserine lactones (AHLs) produced by pathogenic or beneficial bacteria were shown to induce diverse reactions in animals and plants. In plants, the reaction to AHLs depends on the length of the lipid side chain. Here we investigated the impact of two bacteria on Arabidopsis thaliana, which usually enter a close symbiosis with plants from the Fabaceae (legumes) family and produce a long-chain AHL (Sinorhizobium meliloti) or a short-chain AHL (Rhizobium etli). We demonstrate that, similarly to the reaction to pure AHL molecules, the impact, which the inoculation with rhizosphere bacteria has on plants, depends on the type of the produced AHL. The inoculation with oxo-C14-HSL-producing S. meliloti strains enhanced plant resistance towards pathogenic bacteria, whereas the inoculation with an AttM lactonase-expressing S. meliloti strain did not. Inoculation with the oxo-C8-HSL-producing R. etli had no impact on the resistance, which is in agreement with our previous hypothesis. In addition, plants seem to influence the availability of AHLs in the rhizosphere. Taken together, this report provides new insights in the role of N-acyl-homoserine lactones in the inter-kingdom communication at the root surface.
Environmental Stimuli Shape Biofilm Formation and the Virulence of Periodontal Pathogens
Authors: Pöllänen Marja , Paino Annamari , Ihalin Riikka
Published: August 2013

Periodontitis is a common inflammatory disease affecting the tooth-supporting structures. It is initiated by bacteria growing as a biofilm at the gingival margin, and communication of the biofilms differs in health and disease. The bacterial composition of periodontitis-associated biofilms has been well documented and is under continual investigation. However, the roles of several host response and inflammation driven environmental stimuli on biofilm formation is not well understood. This review article addresses the effects of environmental factors such as pH, temperature, cytokines, hormones, and oxidative stress on periodontal biofilm formation and bacterial virulence.
Passivity-Based Nonlinear Excitation Control of Power Systems with Structure Matrix Reassignment
Authors: Li Jianyong , Liu Yanhong , Li Chunwen , Chu Bing
Published: August 2013

Passivity-based control is widely used in electronic circuit systems because it can utilize their internal structures to facilitate the controller design. In this paper, we first propose a dissipative Hamiltonian realization of power systems and discuss the disadvantages of the traditional passivity-based excitation controller. Then, a novel excitation controller is put forward to reassign the interconnection and dissipative matrix, and the corresponding Hamiltonian function. Simulation results verify that the proposed controller can effectively improve the transient stability of the power system.
Antianxiety-Like Effects of Chimpi (Dried Citrus Peels) in the Elevated Open-Platform Test
Authors: Ito Aya , Shin Noriyuki , Tsuchida Takashi , Okubo Toshiki , Norimoto Hisayoshi
Published: August 2013

Dried citrus peels (Chimpi) is one of the most common natural medicines with qi (energy flow) rectifying and shi (dampness) drying actions, which originates from Citrus unshiu, and/or C. reticulata according to the definition of the pharmacopoeiae of Japan and China. In this study, the pharmacological effects of their extracts and major chemical constituents hesperidin and its aglycone hesperetin on anxiety were examined with an anxiety model of elevated open-platform test using ICR male mice (6-week-old) and total duration of freezing was decreased in fluoxetine-treated mice, which is a simple and highly sensitive to the effects of serotonergic anxiolytics. Moreover, yokukansankachimpihange (YKH), a combination of yokukansan with Chimpi and Hange (Pinellia) was also examined because Chimpi is considered to play a crucial part in this formula against anxious symptoms in dementia patients. The results showed that Chimpi and YKH possess a significant anxiolytic-like effect similar to that of fluoxetine, suggesting that they might be similar to fluoxetine in their pharmacological actions through the serotonergic neurotransmission pathway. Moreover, it also suggested that the major chemical constituent, hesperidin could be an active principle attributed to the antianxiety-like effects with a direct and indirect role via its aglycone hesperetin.