bluuebunny/crossref_metadata_2025 huggingface dataset:
Habitat Complexity Influences the Microhabitat Choices of Desert Beetles
Authors: Bartholomew Aaron , Ebeid Karim
Published: June 2012

We present a model for prey survivorship varying with average space size/prey width (Sp/Py) and total cover within an area (Ct/At), which are habitat complexity indices. The model predicts that prey survivorship is maximized at intermediate Sp/Py values, such that prey can fit through the spaces in a habitat, but their larger predators cannot. The model also predicts that prey survivorship increases with increasing cover (Ct/At), which interferes with predators' ability to detect prey. We deployed high-, medium-, and low-complexity artificial vegetation treatments with pit traps to determine if desert beetles respond to differences in habitat complexity consistent with our model's predictions for prey survivorship. We also deployed pit traps in natural vegetation and open sand to determine beetle microhabitat preference. The median number of both large and small beetles was higher in natural vegetation compared with open sand. The median number of large beetles was significantly higher in medium-complexity artificial treatments compared with both low- and high-complexity treatments.Prionotheca coronata, a common species of large beetle, was excluded from the high complexity treatments, as Sp/Py was <1 for them. This demonstrates that high-complexity habitats may exclude larger fauna, reducing community diversity. There was no difference in the mean number of small beetles captured in the different artificial complexity treatments. The results for large beetles are consistent with our model. Small beetles' distribution may be "predator-independent" since they did not respond to differences in complexity.
Links Between Childhood Physical Abuse and Intimate Partner Aggression: The Mediating Role of Anger Expression
Authors: Maneta Eleni , Cohen Shiri , Schulz Marc , Waldinger Robert J.
Published: June 2012

Research linking childhood physical abuse (CPA) and adult intimate partner aggression (IPA) has focused on individuals without sufficient attention to couple processes. In this study, 109 couples reported on histories of CPA, IPA, and anger expression. Actor–partner interdependence model (APIM) was used to examine links between CPA and revictimization and perpetration of IPA, with anger suppression as a potential mediator. Women’s CPA histories were associated with more physical aggression towards and more revictimization by partners. Men’s CPA histories were only associated at the trend level with their revictimization. Anger suppression fully mediated the link between women’s CPA and both revictimization and perpetration of IPA. Findings suggest that women with CPA histories are more prone to suppress anger, which leaves them at greater risk for revictimization and perpetration of IPA.
Application of 3-D Geosteering Capabilities in Geologically-Complex Shale
Authors: Reddy Srinivas , Pitcher Jason
Published: June 2012

On a recent well in the Middle Bakken Dolomite, Williston Basin, North Dakota, an operator struggled to effectively geosteer a horizontal well. The geology, while usually relatively simple, proved to be more complex than anticipated. While drilling, the wellbore was steered out of zone, requiring an open-hole sidetrack. After successfully sidetracking, the well was steered out of zone a second time, requiring a repeat of the sidetrack.

At this point, the operator elected to deploy a comprehensive geosteering service, which consisted of an azimuthal resistivity tool, dedicated geosteering software, and associated geosteering personnel. Once the tools were delivered to the rig site, all data was transmitted offsite to the geosteering specialists for analysis in real time.

The second side track was successfully drilled to TD with no further sidetracks. This demonstrates the ability to rapidly deploy, on short notice, a fit-for-purpose solution to assist operators in accurately positioning wells in the Middle Bakken with a substantial reduction in cost and risk.
Engineered Perforation Design Improves Fracture Placement and Productivity in Horizontal Shale Gas Wells
Authors: Walker K. , Wutherich K. , Terry J.
Published: June 2012

Perforating a horizontal well in the Marcellus shale is typically performed using bare essential technology. Simple rules-of-thumb for perforation cluster spacing and interval length are applied, most likely derived by trial and error, and rarely validated by methods such as production logging and microseismic monitoring. Conversely, a perforating method that is gaining notoriety is an engineered approach in which perforation clusters are placed in each fracture interval of rocks that have similar properties. The reasoning for this method is that it will ensure equal injection rates and volumes of the hydraulic-fracture treatment into each of the perforation clusters; maximizing reservoir contact and production from each cluster.

The completion engineer might base the perforation design on gamma ray measurements with additional support of a mud log. While these measurements add some clarity to the perforation design, there is no evidence that either of these measurements have a direct impact on the breakdown stress of the rock, which is the primary driving force that dictates flow distribution of a hydraulic fracture treatment. Current logging technology does allow us to measure compressional, fast- and slow-shear, and Stoneley slowness waves in 3D along the horizontal cased borehole. These data can then be used to calculate stress and provide a stress profile along the lateral, which can provide an accurate basis for completion design.

Fluid distribution is predicted by way of both basic orifice-flow calculations and 3D hydraulic-fracture models (using actual stress data) and then verified using observations from microseismic monitoring results.

This paper presents a field case in which production improved using the perforation design method described above vs. one using conventional geometrically spaced perforations. In this case study, the operator made the new design technique part of their standard completion program.
Barnett Shale Horizontal Restimulations: A Case Study of 13 Wells
Authors: Craig Mark , Wendte Steve , Buchwalter Jim
Published: June 2012

This case study will review performance and costs of thirteen Barnett Shale horizontal well restimulations located in the “Core” area of Wise County, Texas. This area has produced about 1 TCF gas and is considered one of the most productive areas in the Barnett Shale.

Locator Map – 13 Horizontal Well Restimulations in Wise County, Texas

Devon Energy has performed nine hundred vertical well fracture restimulations (refracs) across the entire Barnett Shale and is now beginning to focus its refrac efforts on the horizontal wells. About thirteen horizontal wells have been restimulated in this area since 2008. Initial results were mixed, but the economics have gradually been improved by developing candidate selection criteria, and modifying the stimulation design to contain costs.

This paper will address the well performance of the horizontal refracs, the costs involved, the restimulation design, and the evolution of candidate screening criteria. We will also briefly touch on some possible reasons for improved refrac well performance, based on computer simulation / history matching.
Microseismic Clouds: Modeling and Implications
Authors: Palmer Ian D. , Moschovidis Zissis A. , Schaefer Aaron
Published: June 2012

Microseismic measurements provide qualitative information about where a fracture stimulation goes. However, there is also quantitative information, which has largely been neglected. We have developed a geomechanical model to predict the extent of shear failure during fracture stimulation of a well. It is a “screening model” meaning point-by-point details of the natural fracture distribution, fluid leakoff, and failure prediction are not emphasized. By matching this to the microseismic cloud of shear failure, we obtain the injection permeability and porosity, which characterize the stimulated reservoir volume (SRV). The model identifies different types of failure, tensile and shear, which will occur on vertical planes of weakness or natural fractures.

The model can be applied to any formation in which the microseismic data demonstrates a substantial spread away from the expected main fracture plane, as occurs in many tight shales. A number of different geometries have been modeled: horizontal vs vertical wells, and transverse vs longitudinal fractures. Not all wells have microseismic data, but the first few wells usually do, and modeling of these cases can provide useful directives for future wells. For example, the injection permeability can provide information on average fracture spacing and aperture width for the induced fracture network (SRV). These can be important for choosing proppant type, size, and concentration for optimal fracture treatments in gas and oil plays in tight shales.

We find the injection permeabilities are relatively high, and these must be associated with fracture-controlled flow. From our case histories, a high injection permeability (>200 md) is required to pressure the formation and achieve failure out as far as the microseismic events extend. Low porosity (≪ 0.1%) is required for the frac fluid to leak off that far. Reports on interference with offset wells support this interpretation. As a case history, the method and results for sequential stimulation of two sister horizontal wells in the Barnett shale are described.

Most of the injection permeability is lost when a well is turned on, and ways to offset this are suggested. One of these ways is to tailor the proppant to the width and spacing of the induced fracture network, to prop more effectively the network of induced fractures. We illustrate some initial guidelines for choosing proppant type, size, and concentration which may improve fracture treatments in tight shales.
Improved Evaluation of Microseismic Data Through the Use of Cumulative Frequency Plots of Microseismic Event Source Parameters
Authors: Downie Robert
Published: June 2012

The engineering evaluation of microseismic events data acquired during hydraulic fracturing treatments can be influenced by factors that affect both the number of events detected and the quality of the waveforms used to locate the microseismic events. Variations in microseismic response that are observed during multistage stimulation treatments might be related to changes in rock properties or the stimulation treatment design or might be caused by detectability limitations related to distance, monitoring tool performance, and signal quality.

Magnitude-versus-distance plots are routinely used to determine detectability limits. Data filters based on a combination of measurement parameters of the detected waveforms can be used to reduce location uncertainty. The selections of filters to be used and the thresholds for filtering need to undertaken with care. Inadequate filtering can allow monitor well bias and microseismic events with low location confidence to adversely affect the evaluation. Aggressive filtering can introduce additional detection biases and might limit full characterization of the hydraulic fracture.

Frequency-versus-magnitude data from multiple treatments can be used to make comparative evaluations of microseismic data that have been acquired over a large range of monitoring distances during multiple stimulation treatments. The events from each treatment can be evaluated to determine a minimum event magnitude that can be used to minimize monitor well bias.

The use of cumulative-frequency-versus-magnitude data can be used to improve the engineering evaluation of microseismic events. This approach to evaluation is quantitative rather than qualitative and increases confidence that observations and analyses based on microseismic events are directly related to the stimulation procedure and properties of the reservoir.
Formation-Tester Pulse Testing in Tight Formations (Shales and Heavy Oil): Where Wellbore Storage Effects Favor the Determination of Reservoir Pressure
Authors: Hadibeik Hamid , Proett Mark , Chen Dingding , Eyuboglu Sami , Torres-Verdín Carlos , Pour Rooholah A.
Published: June 2012

Tight formation testing when mobilities are lower than 0.01 mD/cP poses significant challenges because the conventional pressure transient buildup testing becomes impractical as a result of the large buildup stabilization time. This paper introduces a new automated pulse test method for testing in tight formations that significantly reduces testing time and makes the determination of formation pressure and permeability possible. A pulse test is defined as a drawdown followed by an injection test, and the source is shut in to record the pressure transient. Based on pressure data during the shut-in period, the next drawdown or injection test is designed, such that the flow rate is a fraction of the initial pulse rate, followed by another shut-in test. This procedure continues until the difference in pressure at the beginning and at the end of the shut-in period is reduced to within a specified limit of pressure change; then, an extended transient is recorded to a stabilized shut-in pressure. The overall advantage is to reduce the pressure stabilization time by implementing an adaptive pressure feedback loop in the system. The method can be applied to a straddle packer test using conventional drillstem testing tools or formation testers, using either straddle packers or probes.

The effects of wellbore storage and fluid compressibility are found to reduce the pressure drop and positive pressure pulse in the drawdown and injection tests, respectively; they also affect the decay rate to the asymptote of the shut-in pressure response. Consequently, the combined pulse test method with the pressure feedback system and wellbore storage effect reduces the reservoir pressure testing time in tight formations.

The automated pulse-test method has been successfully validated with consideration of the effects of wellbore storage and overbalance pressure in tight gas and heavy oil formations. In addition, the effects of invasion with water- and oil-based mud filtrate were considered in the modeling. The method uses successive pressure feedbacks and automated pulses to yield a pressure to within 0.5% range of the initial reservoir pressure while decreasing the wait time by a factor of 10 for a packer type formation tester.

To account for various tool options and storage effects, the packer-type, oval probe, and standard probe-type formation testers have been simulated in various tight formation conditions. The method enables a rapid appraisal of pressure measurements in comparison to conventional testing. Simulations also indicate that the analytical spherical model can be used to analyze a pulse test, even when encountering multi-phase compositional fluid effects.
Gas Flow Tightly Coupled to Elastoplastic Geomechanics for Tight and Shale Gas Reservoirs: Material Failure and Enhanced Permeability
Authors: Kim Jihoon , Moridis George J.
Published: June 2012

We investigate coupled flow and geomechanics in gas production from extremely low permeability reservoirs such as tight and shale gas reservoirs, using coupled dynamically porosity and permeability during simulation. The intrinsic permeability is a step function of the status of material failure, and is updated every time step. We investigate the reservoirs with vertical and horizontal primary fractures, employing the single and double porosity models. We modify the multiple porosity constitutive relations for modeling double porous continua for flow and geomechanics. The numerical results indicate that production of gas causes redistribution of the effective stress fields, increasing the effective shear stress and resulting in plasticity. Shear failure occurs away from the primary fractures as well as near the fracture tips, which indicates generation of secondary fractures. These secondary fractures increase the permeability significantly, and change the flow pattern, which in turn causes a change in distribution of geomechanical variables. When the double porosity flow model is used, we observe a faster evolution of the enhanced permeability area than that obtained from the single porosity model because of the higher permeability of the fractures in the double porosity model. Additionally, we find that the complicated physics for stress sensitive reservoirs cannot properly be captured by uncoupled or decoupled methods, and thus tightly coupled flow and geomechanical models are highly recommended to accurately describe the reservoir behavior during gas production in tight and shale gas reservoirs.
Probabilistic Forecasting of Unconventional Resources Using Rate Transient Analysis: Case Studies
Authors: Anderson D. M. , Liang P. , Okouma V.
Published: June 2012

Reliable, early determination of long term production and ultimate recovery in oil and gas reservoirs is of utmost importance to E&P companies, reserves auditors and investors. In conventional reservoirs, the EUR can be reliably estimated once the drainage volume (hydrocarbon pore volume) has been established. This can be done using Rate Transient Analysis (RTA) if the presence of boundary dominated flow can be observed in the data. Unfortunately this approach is not easily applied to tight, fractured reservoirs because of the complexity of these reservoirs (which leads to non-unique reservoir characteristics) and the presence of persistent transient flow (which leads to non-unique estimations of ultimate recovery). In some instances, boundary dominated flow may not be observed until several years have elapsed during the producing life of the well.

In recent years, there have been numerous contributions to the science of well performance-based methods for estimation of ultimate recovery of unconventional resources. Wattenbarger et al. (1998) and Brown et al. (2009) propose analytical techniques while Ilk et al. (2008), Valko and Lee (2010) and Duong (2011) have each proposed new empirical decline curve equations. While each of these methods has value, they do not specifically address the problem that underpins all unconventional well analysis, uncertainty. In 2011, the authors proposed the use of probabilistic rate transient analysis to help quantify this uncertainty. This approach acknowledges the non-uniqueness inherent in the RTA model inputs and allows for the systematic investigation of an allowable parameter space based on acceptable ranges of inputs such as the conductivity, spacing, complexity, length and height of the fractures and the matrix permeability. The result is the full set of possible production forecasts (in as much as the model can be said to capture the physics of the problem) from which the "most likely" production profile can be extracted and that help define the uncertainty in long-term recovery for the play. In this paper, we will further explore probabilistic rate transient analysis by presenting a case study from the Montney play in Canada. The primary objective of this work is to illustrate that a probabilistic approach can be practical, reliable and systematic, offering a viable alternative (or complement) to the standard deterministic techniques.
Use of Drill Cuttings for Improved Design of Hydraulic Fracturing Jobs in Horizontal Wells
Authors: Ortega Camilo , Aguilera Roberto
Published: June 2012

Drill cuttings are powerful sources of information that have been used for several decades by well site petroleum geologists for qualitative evaluation of reservoir rocks. Additional cuttings work is carried subsequently in the laboratory. This includes, for example, the preparation of thin sections for petrographic work, and the evaluation of intergranular and microfracture porosity.

Drill cuttings, however, have not been used to full advantage in horizontal wells drilled through tight formation. This study proposes a method for quantitative determination of porosity, permeability and rock mechanics properties from drill cuttings collected in horizontal wells. These properties are determined through a combination of laboratory, analytical and 3D simulation work. The laboratory work includes the determination of porosity and permeability in cutting samples with sizes equal to 1 mm or larger. The results are used for determining key geomechanical properties such as Poisson's ratio and Young's modulus; and the estimation of a brittleness index. The data extracted from the previous two stages are useful in 3D hydraulic fracturing simulation for designing multi-stage hydraulic fracturing in horizontal wells.

Data extracted from drill cuttings are important as the amount of information collected in horizontal wells drilled thought tight formations, including cores and well logs, is rather limited in most instances.

It is concluded that the proposed method provides a useful tool for evaluation of direct sources of information that are available in many cases (drill cuttings) but are rarely evaluated quantitatively. The proposed method allows improved design of multi stage-hydraulic fracturing jobs in horizontal wells.
Microseismic Studies of Hydraulic Fracture Evolution at Different Pumping Rates
Authors: Chitrala Yashwanth , Sondergeld Carl , Rai Chandra
Published: June 2012

Our objective is to improve hydraulic fracturing through an understanding of the fracture evolution. We used real-time acoustic emission (AE) monitoring to study the samples subjected to varying pumping rates which are diametrically stressed at 650 psi. Velocity analysis indicates the compressional velocity variation is less than 2% throughout the sample, so they are treated as isotropic. Higher breakdown pressures were observed at rapid injection rates. Shear failures are commonly found at low to intermediate injection rates, whereas tensile fractures are observed at rapid pumping rates. Fracture initiation occurs at pressures lower than the breakdown pressure. However, the difference between the initiation and the breakdown pressure is less at slower injection rates. Secondary activity coinciding with the pump shutoff was commonly observed at intermediate and rapid injection rates. Higher pressurization rates were observed at rapid injection rates, but the relationship was not linear. The fracture width and length are observed to taper away from the borehole.
Hydraulic Fracture Design and Well Production Results in the Eagle Ford Shale: One Operator's Perspective
Authors: Bazan Lucas W. , Lattibeaudiere Michael G. , Palisch Terry T.
Published: June 2012

Multiple stage hydraulic fracturing is a key technology driving the development of unconventional resources in North America. This technique began in the Barnett shale and its application has opened the door for the successful development of nearly every shale play in the world, including the Eagle Ford shale. Given the relatively new application of this technique, and the number of fracture treatments completed, initial fracture treatment designs in a given play are often transferred from other North American shale plays to serve as baseline treatments. Given the rapid pace of development in a new play, as well as the desire to get to a standardized completion program, many operators continue to use these baseline designs and fail to evaluate current designs to develop more optimal treatments.

This paper will discuss the successful evolution of hydraulic fracture designs in the Eagle Ford shale from one operator's perspective. It will detail the development from the traditional low conductivity slick water fracture treatments used initially in the play, to the use of higher conductivity hybrid fracture designs. In addition to detailing the theory and workflow of these design changes, this paper will also evaluate production data from multiple wells and evaluate production results for the hydraulic fracture designs. Discussion of enhanced conductivity will be presented along with the economic benefit of these changes.

Those working the Eagle Ford shale can directly apply the principles presented in this paper to enhance the productivity and economics of their completions. In addition, engineers working other resource developments can use the principles from this paper to compare their current fracture design methodology and develop best practice approaches for hydraulic fracture design optimization in their respective plays.
An Evaluation of Immediate Outcomes and Fidelity of a Drug Abuse Prevention Program in Continuation High Schools: Project towards No Drug Abuse (TND)
Authors: Lisha Nadra E. , Sun Ping , Rohrbach Louise A. , Spruijt-Metz Donna , Unger Jennifer B. , Sussman Steve
Published: June 2012

The present study provides an implementation fidelity, process, and immediate outcomes evaluation of Project Towards No Drug Abuse (TND), a drug prevention program targeting continuation high school youth ( n = 1426) at risk for drug abuse. A total of 24 schools participated in three randomized conditions: TND Only, TND and motivational interviewing follow-up, and no treatment control. Fidelity was high: across program schools the curriculum was implemented as intended and was received favorably by students. Relative to controls, intervention conditions produced effects on hypothesized mediators, including greater gains in program related knowledge, greater reductions in drug use intentions, and positive changes in motivation. However, few generalizations to attitudes and intentions regarding risky sexual behavior were found. The pattern of results suggests that the experimental manipulations worked as intended.
A Review of Social Host Policies Focused on Underage Drinking Parties: Suggestions for Future Research
Authors: Wagoner Kimberly G. , Francisco Vincent T. , Sparks Michael , Wyrick David , Nichols Tracy , Wolfson Mark
Published: June 2012

Underage drinking continues to be a public health concern, partially due to the ease in which adolescents obtain alcohol and consume it in private locations. States and municipalities have implemented strategies to counteract this, including adopting public policies called social host policies, despite limited evidence of effectiveness. Traditionally, these laws have held adults accountable for furnishing alcohol to underage drinkers. However, states and communities are using another policy, also called social host, to deter underage drinking parties where easy access to alcohol and high-risk use occurs. These innovative laws hold individuals who control the property accountable for underage drinking that occurs there, regardless of alcohol source. We conducted a critical analysis of social host policies focused on hosting underage drinking parties and constructed a conceptual model to understand their targeted factors. Future research recommendations are discussed.
Islamic Death Rituals in a Small Town Context in the Netherlands: Explorations of a Common Praxis for Professionals
Authors: Venhorst Claudia
Published: June 2012

Islamic tradition tends to present death rituals in a quite univocal way, as the actual ritual practice shows to be far more diverse and flexible. This study focuses on the particular ritual of the cleansing of the deceased as it is practiced by a variety of Muslims in a small town context in the Netherlands. The presented vignettes are drawn on qualitative research data from interviews and (participant) observations. They are presented to draw attention to the different contexts that shape the religious and ritual practice of a variety of Muslims in the Netherlands. To develop an eye for this common praxis, it is important not only to be aware of the religious dimensions but also of the social dimensions. By offering insights into the actual practices it aims to offer tangible leads to professionals for a more tailor-made care for Muslim patients and their relatives.
Does Superstition Help? A Study of the Role of Superstitions and Death Beliefs on Death Anxiety Amongst Chinese Undergraduates in Hong Kong
Authors: Wong S. H.
Published: June 2012

Past research has shown that traditional Chinese death beliefs, which mostly consisted of superstitious thoughts, are related to death anxiety. However, other studies have shown that superstitions may help people cope with uncertainty and, therefore, reduce uncertainty-induced anxiety. The role of superstitions, whether related to heightened death anxiety or reduced death anxiety, is unclear. This study attempted to address the knowledge gap by examining the relationships among superstitions and Chinese death beliefs on death anxiety in the Chinese context. One hundred twenty-four undergraduates in Hong Kong completed measures of superstition (R-PBS), death anxiety (MFODS), and Chinese death beliefs scale. Superstition was found to be predictor of death anxiety, as expected. With superstitions highly prevalent in Chinese societies, the study has practical implications in end-of-life care, bereavement support, and death education in the Chinese context.
Development and Validation of the Type 1 Diabetes Nutrition Knowledge Survey
Authors: Rovner Alisha J. , Nansel Tonja R. , Mehta Sanjeev N. , Higgins Laurie A. , Haynie Denise L. , Laffel Lori M.
Published: June 2012

OBJECTIVE

The purpose of this study was to develop a survey of general and diabetes-specific nutrition knowledge for youth with type 1 diabetes and their parents and to assess the survey’s psychometric properties.

RESEARCH DESIGN AND METHODS

A multidisciplinary pediatric team developed the Nutrition Knowledge Survey (NKS) and administered it to youth with type 1 diabetes (n = 282, 49% females, 13.3 ± 2.9 years) and their parents (82% mothers). The NKS content domains included healthful eating, carbohydrate counting, blood glucose response to foods, and nutrition label reading. Higher NKS scores reflect greater nutrition knowledge (score range is 0–100%). In youths, glycemic control was assessed by A1C, and dietary quality was determined by the Healthy Eating Index-2005 (HEI-2005) derived from 3-day diet records. Validity was based on associations of NKS scores with A1C and dietary quality. Reliability was assessed using the Kuder-Richardson Formula 20 (KR-20) and correlations of domain scores to total score.

RESULTS

Mean NKS scores (23 items) were 56.9 ± 16.4% for youth and 73.4 ± 12.5% for parents. The KR-20 was 0.70 for youth and 0.59 for parents, representing acceptable internal consistency of the measure. In multivariate analysis, controlling for youth age, family income, parent education, diabetes duration, and insulin regimen, parent NKS scores were associated with corresponding youth A1C (β = −0.13, P = 0.03). Both parent (β = 0.20, P = 0.002) and youth (β = 0.25, P < 0.001) NKS scores were positively associated with youth HEI-2005 scores.

CONCLUSIONS

The NKS appears to be a useful measure of general and diabetes-specific nutrition knowledge for youth with type 1 diabetes and their parents.
Effects of Food-simulating Liquids on Surface Properties of Giomer Restoratives
Authors: Kooi TJM , Tan QZ , Yap AUJ , Guo W , Tay KJ , Soh MS
Published: June 2012

This study examined the effects of food-simulating liquid (FSL) on the hardness and roughness of giomer restoratives based on pre-reacted glass ionomer (PRG) technology. The materials investigated included a regular (Beautifil II [BT]) and a recently introduced injectable (Beautifil Flow Plus F00 [BF]) hybrid PRG composite. A direct hybrid composite (Filtek Z250 [ZT]) and an indirect hybrid composite (Ceramage [CM]) were used for comparison. The materials were placed into customized square molds (5 mm × 5 mm × 2.5 mm), covered with Mylar strips, and cured according to manufacturers' instructions. The materials were then conditioned in air (control), distilled water, 50% ethanol solution, and 0.02 N citric acid at 37°C for seven days. Specimens (n=6) were then subjected to hardness testing (Knoop) and surface profilometry. Data were analyzed using one-way analysis of variance and post hoc Scheffe test (p<0.05). Mean Knoop hardness values for the control group (air) ranged from 53.4 ± 3.4 (BF) to 89.5 ± 5.2 (ZT), while mean surface roughness values values ranged from 0.014 ± 0.002 (ZT) to 0.032 ± 0.001 (BT). All materials were significantly softened by FSL. The degree of softening by the different FSLs was material dependent. The hardness of giomers was most affected by citric acid and ethanol. The smoothest surface was generally observed with the control group. Giomer restoratives were significantly roughened by citric acid.
The gap phenomenon in the dimension study of finite type systems
Authors: Kruglikov Boris
Published: June 2012

Several examples of gaps (lacunes) between dimensions of maximal and submaximal symmetric models are considered, which include investigation of number of independent linear and quadratic integrals of metrics and counting the symmetries of geometric structures and differential equations. A general result clarifying this effect in the case when the structure is associated to a vector distribution, is proposed.
On the sum of digits of some sequences of integers
Authors: Cilleruelo Javier , Luca Florian , Rué Juanjo , Zumalacárregui Ana
Published: June 2012

Let b ≥ 2 be a fixed positive integer. We show for a wide variety of sequences {a n}n=1∞ that for almost all n the sum of digits of a n in base b is at least c b log n, where c b is a constant depending on b and on the sequence. Our approach covers several integer sequences arising from number theory and combinatorics.
De novo synthesis of protein phosphatase 1A, magnesium dependent, alpha isoform (PPM1A) during oocyte maturation
Authors: Chuderland Dana , Dvashi Zeev , Kaplan-Kraicer Ruth , Ben-Meir Daniella , Shalgi Ruth , Lavi Sara
Published: June 2012

Oocyte maturation in mammals is a multiple-stage process that generates fertilizable oocytes. Ovarian oocytes are arrested at prophase of the first meiotic division characterized by the presence of a germinal vesicle. Towards ovulation, the oocytes resume meiosis and proceed to the second metaphase in a process known as maturation; they undergo nuclear and cytoplasmic changes that are accompanied by translation and degradation of mRNA. Protein phosphatase 1A, magnesium dependent, alpha isoform (PPM1A), which belongs to the metal-dependent serine/threonine protein phosphatase family, is highly conserved during evolution. PPM1A plays a significant role in many cellular functions such as cell cycle progression, apoptosis and cellular differentiation. It works through diverse signaling pathways, including p38 MAP kinase JNK and transforming growth factor beta (TGF-β). Herein we report that PPM1A is expressed in mouse oocytes and that its mRNA level rises during oocyte maturation. Using quantitative real-time polymerase chain reaction (qPCR) and western blot analysis, we found that PPM1A mRNA is synthesized at the beginning of the maturation process and remains elevated in the mature oocytes, promoting the accumulation of PPM1A protein. Since PPM1A function is mainly affected by its level, we propose that it might have an important role in oocyte maturation.
Operational pattern and contribution of urban farming in an emerging megacity: evidence from Lagos, Nigeria
Authors: Lawal Mohamed , Aliu Ibrahim
Published: June 2012

Operational pattern and contribution of urban farming in an emerging megacity: evidence from Lagos, Nigeria

Urban farming is rapidly growing in many cities in Nigeria including a leading African megacity Lagos, although urban stakeholders have paid little attention to the trend over time. The rate of growth of urban farming and its contributions to Lagos state's food supply strategy is worthy of note. In Lagos farming activities are practiced and performed by some able bodied migrants from all parts of the country, who for many reasons could hardly have been absolved by the aggressive urban economy of the city. A close watch on the practitioners reveals a pattern of operation which requires deeper inquiry. A total of 202 urban vegetable farmers were interviewed in four areas of Lagos state to provide primary data for this study. Results from the study showed that an average farmer owns a farm plot of below 120 m by 60 m usually linear and along the expressway, the green vegetable (Celosia argientes) alone constitutes about 97% of what is grown, beds are arranged in sizes of about 1.8 m long by 0.9 m wide and 0.3 m high with furrows in between. The farmers use the simplest local tools, chemical fertilizers, and strategically located irrigation wells. It was also found that the farmers use some part of the vegetables for household consumption, sell others to the local marketers, and contribute their own quota to stem the rising prices of vegetable produce in the local markets. It is therefore imperative on the stakeholders to re-examine the relevance of urban farming in the city and provide support for its growth.
Demographic potential of the countries that have applied for the European Union membership
Authors: Sojka Elżbieta
Published: June 2012

Demographic potential of the countries that have applied for the European Union membership

The purpose of the article is to analyse the demographic potential of the countries that have applied for the European Union membership against the background of the EU member states. The study involves eight candidate states: Croatia, Iceland, Macedonia, Montenegro, and Turkey, i.e. the countries that have been approved by the European Commission as official candidates for the EU membership, as well as Albania, Bosnia and Herzegovina, Serbia, i.e. the potential candidates. Albania and Serbia applied officially for the EU membership in 2009. Favourable population age structure and relatively high fertility rate that occur in these countries determine a significant demographic potential they can bring to the EU after their accession. Decrease in infant mortality rate and extension of life expectancy illustrate positive changes that have been taking place in these countries for the last several years.
Permian volcanics in the Northern Gemericum and Bôrka Nappe system: U-Pb zircon dating and the implications for geodynamic evolution (Western Carpathians, Slovakia)
Authors: Vozárová Anna , Šmelko Miloš , Paderin Ilya , Larionov Alexander
Published: June 2012

Permian volcanics in the Northern Gemericum and Bôrka Nappe system: U-Pb zircon dating and the implications for geodynamic evolution (Western Carpathians, Slovakia)

U-Pb dating (SHRIMP) of magmatic zircon ages from the Northern Gemericum Permian volcanics (Petrová Hora Formation) yielded the Concordia age of 272.4 ± 7.3 Ma for basaltic andesite, as well as the Concordia age of 275.2 ± 4 Ma for rhyodacites. Both zircon ages correspond to the Cisuralian Epoch in the time span of the Kungurian Stage. Acquired206Pb/238U zircon age data support the nearly contemporaneous origin of the acid and basic volcanogenic members in the Northern Gemericum Permian strata. The bimodal volcanic suite proves the transtension/extension tectonic regime in the North Gemeric sedimentary basin during the Late Cisuralian. The magmatic zircon ages of rhyodacites, occurring in the lower thrust sheet of the Bôrka Nappe (Jasov Formation), gave a younger Concordia age of 266 ± 1.8 Ma proving the Guadalupian Epoch, in the time span of the Wordian/Capitanian. In comparison to the Northern Gemericum realm, this age refers to the relatively younger stage of rift-related extensional movements. In the wide Alpine-Dinarides realm the Middle Permian (Guadalupian) movements are related to the beginning of the Alpine sedimentary cycle. Thus, the Middle Permian rifting expresses the beginning of the formation of the future Meliata oceanic trough.
The resistivity image of the Muráň fault zone (Central Western Carpathians) obtained by electrical resistivity tomography
Authors: Putiška René , Dostál Ivan , Mojzeš Andrej , Gajdoš Vojtech , Rozimant Kamil , Vojtko Rastislav
Published: June 2012

The resistivity image of the Muráň fault zone (Central Western Carpathians) obtained by electrical resistivity tomography

The paper describes the application of geophysical prospecting techniques for estimation of the fault's inclination. The field survey was carried out across the Muráň fault structure in the Slovenské rudohorie Mts (central Slovakia). Three different geophysical methods were used to map the fault zone: Electrical Resistivity Tomography (ERT), induced polarization (IP) and radon emanometry. All these methods have been used to locate the fault zone area, but the principal aims of this research are to test the efficiency of the 2D ERT technique to recognize the geometrical characterization of the fault and to improve our tectonic knowledge of the investigated area. For the synthetic cases, three geometric contexts were modelled at 60, 90 and 120 degrees and computed with the l2norm inversion method, the l1norm with standard horizontal and vertical roughness filter and the l1norm with diagonal roughness filter. In the second phase this geophysical methodology was applied to fieldwork data. Our results confirm that the ERT technique is a valuable tool to image the fault zone and to characterize the general geometry, but also the importance of setting up the right inversion parameters. The main contribution of the geophysical investigations in this case was the determination of the location and confirmation of the inclination of the Muráň fault. The result of this study is the ability to make a visual estimation of the direction and dip of the fault. Pursuant to this work the dipole-dipole electrode configuration produces the best resolution, particularly for the location of vertical and dipping structures. The advantage of this array is that it shows the ability to assess the trend of the dip and therefore it can be strongly recommended. The result is also a case study of a small scale tectonic survey involving geophysical methods.
Geochemistry and electron spin resonance of hydrothermal dickite (Nowa Ruda, Lower Silesia, Poland): vanadium and chromium
Authors: Premović Pavle , Ciesielczuk Justyna , Bzowska Grażyna , Đorđević Miloš
Published: June 2012

Geochemistry and electron spin resonance of hydrothermal dickite (Nowa Ruda, Lower Silesia, Poland): vanadium and chromium

Geochemical analyses for trace V and Cr have been done on a representative sample of a typical hydrothermal dickite/kaolinite filling vein at Nowa Ruda. The mineralogy of the sample is comparatively simple, dickite being the principal component (ca. 91 % of the total sample). Geochemical fractionation and inductively coupled plasma-optical emission spectrometry (ICP-OES) indicate that most (> 90 % of total metal) of the V and Cr reside in the dickite. Electron Spin Resonance (ESR) shows that most (> 70 %) of the V in the dickite structure is in the form of vanadyl (VO2+) ions. A high concentration of Cr3+ is also detected in this structure by ESR. The combination of geochemical and spectroscopic tools applied to VO2+ and Cr3+ allow one to specify the Eh (> 0.4 V, highly oxidizing) and pH (≤4.0, highly acidic) of the solution during the formation of dickite from the Nowa Ruda Basin. Substantial proportions of the V and Cr (as well as VO2+ and Cr3+) in the dickite structure were probably contained in an original hydrothermal acid water. We suggest that hot hydrothermal waters leached the surrounding varieties of gabbroids enriched in V and Cr for the dickite-forming solution. The results of this work have shown V and Cr are potentially reliable indicators for geochemical characterization of the physicochemical conditions of their formation. The bulk-rock V/Cr ratio in hydrothermal dickites and kaolinites from Nowa Ruda, Sonoma (California, USA), Cigar Lake (Saskatchewan, Canada) and Teslić (Bosnia and Hercegovina) is also briefly explored here as a potential tracer of redox state during their formation.
Monitoring of facultative avian scavengers on large mammal carcasses in Dinaric forest of Slovenia
Authors: Krofel Miha
Published: June 2012

Monitoring of facultative avian scavengers on large mammal carcasses in Dinaric forest of Slovenia

Facultative vertebrate scavengers have an important role in forest ecosystems, however, not much is known as to their use of carrion in temperate forests. Three carcasses of Red DeerCervus elaphusand European Roe DeerCapreolus capreolusfound dead or killed by Grey WolfCanis lupuswere monitored in March and April 2010 and 2011 on Menišija Plateau in northern Dinaric Mountains (central Slovenia) using photo-trapping and video surveillance. Carcasses were monitored for 26 days, during which 708 photos and 43 video recordings of scavengers were taken. In the 91% of all visits recorded, birds were the most frequent scavengers, with Common BuzzardButeo buteoas the most frequent species present at 76% of all visits. On average, Buzzards returned to carcasses twice per day, with an average visit lasting 29 min. Common Buzzards used carcasses to a significantly higher degree on days with snow cover, which was due to the more frequent visits per day and not to longer visits. Recorded antagonistic interspecific interactions suggested that Common Buzzards were the dominant species in the observed avian scavenger guild, as they displaced RavensCorvus coraxand GoshawkAccipiter gentilisfrom the carcass. However, Ravens frequently mobbed Common Buzzards while scavenging. Once an Ural OwlStrix uralensisalso visited prey remains of Grey Wolf, but feeding could not be confirmed. Observations suggested that carcasses of large mammals could be locally and temporarily an important food source for some facultative avian scavengers in Dinaric forests, especially in times when other food is scarce. Data from the two wolf kills also confirm the importance of predation by large carnivores in providing food for scavengers. Given the small amount of meat consumed, kleptoparasitism by solitary raptors did not bring significant losses to large carnivores, whereas gregarious avian scavengers like corvids can importantly affect the consumption process and consume large amount of biomass in a relatively short time.
Phytocoenoses of Scots pine forests on the background of changes in classification of mesotrophic sites in Bolesławiec Forest
Authors: Stefańska-Krzaczek Ewa
Published: June 2012

Fitocenozy borów sosnowych na tle zmian klasyfikacji mezotroficznych siedlisk borowych na przykładzie Nadleśnictwa Bolesławiec
Possibilities of control of fir shoot moths Choristoneura murinana Hb., Zeiraphera rufimitrana H.-S. and Epinotia nigricana H.-S. in the Świętokrzyskie Mountains
Authors: Głowacka Barbara , Bystrowski Cezary
Published: June 2012

Możliwości zwalczania zwójek jodłowychChoristoneura murinanaHb.,Zeiraphera rufimitranaH.-S. iEpinotia nigricanaH.-S. w lasach Gór Świętokrzyskich
Resistance of Norway spruce to Heterobasidion root rot
Authors: Chomicz Elżbieta
Published: June 2012

Odporność świerka na hubę korzeni
Metabolomics - Useful Tool for Study of Plant Responses to Abiotic Stresses
Authors: Kráľová Katarína , Jampílek Josef , Ostrovský Ivan
Published: June 2012

Metabolomics - Useful Tool for Study of Plant Responses to Abiotic Stresses

Abiotic stresses are produced by inappropriate levels of physical components of the environment and cause plant injury through unique mechanisms that result in specific responses. Metabolomics is a relatively new approach aimed at improved understanding of metabolic networks and the subsequent biochemical composition of plants and other biological organisms. The paper is focused on the use of metabolomics, metabolic profiling and metabolic fingerprinting to study plant responses to some environmental stresses (eg elevated temperature, chilling and freezing, drought, high salinity, UV radiation, high ozone levels, nutrient deficiency, oxidative stress, herbicides and heavy metals). Attention is also devoted to the effects of some environmental factors on plants such as high or low levels of CO2 or different levels of irradiance. Alterations of plants metabolites due to multiple abiotic stresses (drought-heat, drought-salinity, elevated CO2-salinity) are analysed as well. In addition, metabolomic approach to study plant responses to some artificial abiotic stresses, mechanical stress or pulsed electric field-induced stress is discussed. The most important analytical methods applied in metabolomics are presented and perspectives of metabolomics exploitation in the future are outlined, too.