bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine Learning Methods to Speed up Compositional Reservoir Simulation
Authors: Gaganis Vassilis , Varotsis Nikos
Published: June 2012

Compositional reservoir simulation is the most powerful tool available to the reservoir engineer upon which, nowadays, most reservoir development decisions rely on. According to the number of components used to describe the fluids, there is a very high demand for computational power due to the complexity and to the iterative nature of the phase behavior problem solution process. Phase stability and phase split computations often consume more than 50% of the simulation's total CPU time as both problems need to be solved repeatedly for each discretization block at each iteration of the non-linear solver. Therefore, the speeding up of these calculations is a challenge of great interest.

In this work, machine learning methods are proposed for the solving of the phase equilibrium problem. It is shown that by using proper transformations, the unknown closed-form solution of the Equation-of-State based formulation can be emulated by proxy models. The phase stability problem is treated by classifiers which label the fluid's state in each block as either stable or unstable. For the phase-split problem, regression models provide the prevailing equilibrium coefficients values given the feed composition, pressure and temperature. The development of both models is performed rapidly and offline in an automated way, by utilizing the fluid's tuned-EoS model, prior to running the reservoir simulator. During the simulation run, the proxy models are called to provide direct answers of the phase equilibrium problem at a very small CPU charge instead of solving iteratively the phase behavior problem.

The proposed approach is presented in two-phase equilibria formulation but it can be extended to multi-phase equilibria applications. Examples demonstrate the accuracy of the calculations and the very significant CPU time reduction achieved with respect to currently used methods.
A New Comprehensive Approach for Predicting Injectivity Decline during Waterflooding
Authors: Yuan H. , Nielsen S. M. , Shapiro A. A. , Bedrikovetsky P.
Published: June 2012

Injectivity decline during sea waterflooding or produced water re-injection is widely observed in North Sea, Gulf of Mexico and Campos Basin fields. The formation damage occurs mainly due to the deposition of suspended solids around injectors and the build-up the external filter cakes in the well bores. The ability to predict injectivity decline accurately is of great importance for project designs and water management. A comprehensive model that incorporates a variety of factors influencing the process is desirable for the prediction. In this paper, a new comprehensive approach for predicting injectivity decline during water flooding is proposed. The deep bed filtration is described by novel stochastic random walk equations. The injectivity decline model takes into account the reservoir heterogeneity and the distribution of solid particles by sizes. It also accounts for the later formation of the external filter cake and its erosion. A piece of software SNY is developed with the proposed model. The model is able to capture the behaviors of the injectors in the field: the initial slow injectivity decline due to the deep bed filtration of suspended particles, the later faster decline due to the build-up of the external cake, and the temporary steady state due to the cake erosion. Stronger normal dispersion or median heterogeneity close to the injector leads to farther penetration of the particles and slower impedance increase. Neglecting the particle population heterogeneity may lead to the underestimation of formation damage and predicts late transition to external cake formation. The impedance at the steady state and the starting time are highly influenced by the cake properties. The impedance and the external cake thickness at the steady state are likely to be higher in horizontal wells than those in vertical wells.
New Insights Into CO2 Injection and Storage in Saline Aquifers
Authors: Sohrabi Mehran , Riazi Masoud , Bernstone Christian , Jamiolahmady Mahmoud , Christensen Niels-Peter
Published: June 2012

Worldwide, significant efforts and resources are being directed at evaluating potentials of CCS (carbon capture and storage) for the long term storage of large quantities of CO2 that would otherwise be released in the atmosphere. Despite many years of experience with CO2 injection in oil reservoirs, our current understanding of brine/CO2 interactions that occur during CO2 injection in aquifers (brine-bearing rocks) remains very limited. This is a source of uncertainty and concern not just for the governments and companies interested in investment in CCS but also for the public in relation to the safety of long term injection and storage of CO2 in geologic formations.

In this paper we report new insights into the pore-scale interactions between super-critical CO2 and brine obtained from the results of a series of CO2 injection visualisation experiments carried out in novel high-pressure transparent porous media. In these experiments, we have physically simulated and visually investigated the micro-scale behaviour of CO2 in brine-bearing porous media. In particular, through vivid images of fluids distribution taken during the experiments, we highlight a new mechanism in which CO2 evolution follows CO2 dissolution in brine. In parts of the porous medium in which CO2 injection was taking place, it was observed that a free CO2 phase nucleated and came out of solution and gradually expanded. The phenomenon accelerated when the brine salinity increased or when the CO2 injection rate increased.

The observed mechanism is expected to affect many important aspects of CO2 flow and retention in porous media. It may increase CO2 storage capacity by displacing more brine. On the other hand, it can adversely affect the ability of rock to safely contain the stored CO2.
Experimental and Theoretical Investigation of Gas/Oil Relative Permeability Hysteresis under Low Oil/Gas IFT and Mixed-Wet Conditions
Authors: Fatemi S. Mobeen , Sohrabi Mehran , Jamiolahmady Mahmoud , Ireland Shaun
Published: June 2012

Accurate determination of relative permeability values and their hysteresis is crucial for obtaining a reliable prediction of the performance of water-alternating-gas (WAG) injection in oil reservoirs. In this paper we report two series of gas/oil relative permeability curves obtained from coreflood experiments carried out in a mixed-wet core under a very low oil/gas interfacial tension (IFT) of 0.04mN.m−1. The first set of the corefloods began by oil injection (imbibition) in the core saturated with gas and immobile water (Swi). This was followed by a period of gas injection (drainage) and this sequential injection of oil and gas continued and in total, three imbibition and two drainage periods were carried out. In the second series of experiments, the core was initially saturated with oil and immobile water and the experiment started with a gas injection followed by cycles of drainage and imbibitions.

The measured pressure drop and production data were history matched through simulation analysis to obtain krg and kro values for each of the imbibition and drainage cycles. The results show that both the oil and the gas relative permeability curves show cycle-dependent hysteresis despite the very low gas/oil IFT. Therefore, the current assumption in existing models (such as Land, Carlson and Killough) that the drainage scanning kr curves follow the preceding imbibition curve is not supported by our coreflood experiments.

When compared to our measured data, Carlson model predictions for krg in imbibition direction are poor. Killough model predictions underestimate krg and overestimate kro especially near trapped gas saturation regions. Beattie et al. hysteresis model is able to capture the krg and kro behavior that we observed in our experiments qualitatively, but it is still unable to predict the value of the observed hysteresis. The results suggest that for mixed-wet systems, it is necessary to consider irreversible hysteresis loops for both the wetting and non-wetting phases. Such capability currently does not exist in reservoir simulators due to lack of appropriate predictive tools.
Depth of Investigation and Depletion Behavior in Unconventional Reservoirs Using Fast Marching Methods
Authors: Xie Jiang , Gupta Neha , King Michael J. , Datta-Gupta Akhil
Published: June 2012

The concept of depth of investigation is fundamental to well test analysis. Much of the current well test analysis relies on solutions based on homogeneous or layered reservoirs. Well test analysis in spatially heterogeneous reservoirs is complicated by the fact that Green’s function for heterogeneous reservoirs is difficult to obtain analytically (Deng and Horne 1993). In this paper, we introduce a novel approach for computing the depth of investigation and pressure response in spatially heterogeneous and fractured reservoirs.

In our approach, we first present an asymptotic solution of the diffusion equation in heterogeneous reservoirs. Considering terms of highest frequencies in the solution, we obtain two equations: the Eikonal equation that governs the propagation of a pressure ‘front’ and the transport equation that describes the pressure amplitude as a function of space and time. The Eikonal equation generalizes the depth of investigation for heterogeneous reservoirs and provides a convenient way to calculate drainage volume. From drainage volume calculations, we estimate a generalized pressure solution based on a geometric approximation of the drainage volume. A major advantage of our approach is that the Eikonal equation can be solved very efficiently using a class of front tracking methods called the Fast Marching Methods (FMM). Thus, transient pressure response can be obtained in multimillion cell geologic models in seconds without resorting to reservoir simulators.

We first visualize depth of investigation and pressure solution for a homogeneous reservoir with multi-stage transverse fractures and identify flow regimes from pressure diagnostic plot. And then, we apply the technique to a heterogeneous reservoir to predict depth of investigation and pressure behavior. The computation is orders of magnitude faster than conventional numerical simulation and provides a foundation for future work in reservoir characterization and field development optimization.
Evaluation of the CO2 Storage Capacity of the Captain Sandstone Formation
Authors: Jin Min , Mackay Eric , Quinn Martyn , Hitchen Ken , Akhurst Maxine
Published: June 2012

The volume of CO2 that can be stored in the Captain Sandstone saline aquifer in the North Sea was investigated by building a geological model and performing numerical simulations. These simulations were also used to calculate the best position for the injection wells, and the migration and ultimate fate of the CO2.

The overall migration of CO2 and the pressure response over the entire saline aquifer was studied by the calculated injection of 15 million tonnes CO2 per year. The injection rate was restricted to a maximum of 2.5 million tonnes CO2 per year for each of a possible 12 wells considered. An important objective was to predict how to avoid flow of the injected CO2 toward potential leakage points, such as the sandstone boundaries and faults. The migration of injected CO2 towards existing oil and gas fields was also a determining factor.

The summary conclusions are: The Captain Sandstone saline aquifer has significant potential CO2 storage capacity. Even with all boundaries closed to flow, the probable storage capacity is calculated to be about 358 million tonnes, giving a storage efficiency of 0.6% of pore volume, with an expected operating life-span of 15-25 years.The possible storage capacity of the formation may be at least four times greater if the aquifer boundaries are open. This increase would be a result of displacement of salt water, and not CO2.The storage capacity if the sandstone is closed to flow may be increase from 358 to 1668 million tonnes of CO2 by significant additional investment in 15 to 20 water production wells.Injection of up to 2.5 million tonnes CO2 per year in one well has an impact on the pressure throughout the entire formation, and thus interference between different injection locations must be considered.
xzsEffect of Drilling Fluid (Water-Based vs Oil-Based) on Phase Trap Damage in Tight Sand Gas Reservoirs
Authors: Mitchel Tsar , Hassan Bahrami , Reza Rezaee , Geeno Murickan , Sultan Mehmood , Mohsen Ghasemi , Abolfazl Ameri , Mahna Mehdizadeh
Published: June 2012

Tight gas reservoirs are mainly characterized by low matrix permeability and significant damage. During drilling and fracturing of tight formations, wellbore liquid invades into tight formation and increases water saturation around wellbore and eventually reduces permeability near wellbore or adjacent to fracture wings. The damage to permeability caused by invasion of liquid into tight formation is controlled by capillary pressure and relative permeability curves.

The phase trap damage is one of the main concerns in use of water based drilling or fracturing fluid, since due to high critical water saturation, strong capillary pressure, and sensitivity of tight sand to water. Therefore, use of oil based mud may be preferred in drilling or fracturing of tight formation. However invasion of oil filtrate into tight formation may result in a three-phase relative permeability curves in invaded zone in presence of reservoir gas and initial water, which may differently affect damage and productivity of tight gas reservoirs.

This study evaluates phase trap damage in water-based in comparison with oil-based drilled or fractured tight gas reservoir. Reservoir simulation is used to study the effect of relative permeability curves on phase trap damage and well productivity, based on reservoir and core data from a West Australian tight gas reservoir. The results highlights benefits of using oil-based fluids in drilling and fracturing of tight gas reservoirs in term of improving well productivity.
Development Of An Integrated Evaluation Methodology On Scale Management Pre- and Post-Production: An Engineer’s Perspective
Authors: Akuanyionwu Obinna , Wahid Fazrie
Published: June 2012

Scale formation can have a detrimental impact on production if left unchecked. Similarly, scale management can be costly without proper evaluation and planning. Developing a cost-effective scale management strategy during field development planning phase is imperative to assist decision making. Furthermore the strategy must address the procedures to explicitly assess the well and field performance during production, to optimize the production over the field life.

In the past, the assessment of potential for scale formation was performed based on static scaling risk assessment method, which relied solely on the output from static thermodynamic scale prediction models. In this document, we introduce a systematic methodology to assess the scale formation risk as time dependent by coupling dynamic modeling with static scaling risk assessments; where streamline simulation technique has been used to predict scale precipitation in the reservoir and the consequent in-situ stripping of scaling ions. Extending the use of the dynamic simulation tools to assess the scaling risks in reservoir and near wellbore will assist in field development planning, development, as well as production operation, monitoring and optimization.

Workflows developed on a North Sea field development (pre- and post-production) are described, including results from analog/synthetic datasets as examples. Our work indicates that both in-situ ion stripping and drainage patterns significantly influence chemical requirements and treatment frequencies for squeeze treatments following in-situ scale deposition. It also shows from a historical perspective how scale has impacted production in analogue wells and more importantly to characterize the location of the precipating scale. Finally, we highlight limitations in current industry tools and workflows, and what can be done to reduce uncertainties during the development of a scale management strategy.
Different modulatory effects of ammonium ions on angiotensin vascular actions in isolated rat aortic and renal arteries
Authors: Popescu Raducu , Bild W. , Ciobica A. , Bild Veronica
Published: June 2012

In the present study, we were interested in the vascular effects of
angiotensin II on perfused rings of the rat thoracic aorta and renal artery.
Our results demonstrated different modulator alterations of these
preparations induced by ammonium ions. Unlike the aortic rings, which
exhibited only a reduction of angiotensin-induced contractility by NH4Cl,
the renal artery preparations showed both activation of vasoconstriction and
inhibition of vasorelaxation in the ring precontracted with phenylephrine or
noradrenalin. These results are interpreted as a modulation by the ammonium
ions of vascular reactions induced by the stimulation of the vasoconstrictor
AT1 receptor on the one side and AT2 vasodilator receptors on the other. The
potentiation of renal vasoconstriction accompanied by the reduction of
angiotensin vasodilation by NH4Cl suggests the possibility of involvement
from the blood flow and renal vascular tonus disturbances induced by
ammonium ions during hyperammonemia of various causes.
The role of Omi/HtrA2 protease in neonatal postasphyxial serum-induced apoptosis in human kidney proximal tubule cells
Authors: Zhang Yong , Dong Wen-Bin , Qing-Ping Li , Deng Chun-Liang , Xiong Tao , Lei Xiao-Ping , Guo Lin
Published: June 2012

Omi/HtrA2, a proapoptotic mitochondrial serine protease, is involved in both
caspase-dependent and caspaseindependent apoptosis. A growing body of
evidence indicates that Omi/HtrA2 plays an important role in the pathogenesis
of a variety of ischemia-reperfusion (I/R) injuries. However, the role of
Omi/HtrA2 in renal injuries that occur in neonates with asphyxia remains
unknown. The present study was designed to investigate whether Omi/HtrA2
plays an important role in the types of renal injuries that are induced by
neonatal postasphyxial serum. Human renal proximal tubular cell line (HK-2)
cells were used as targets. A 20% serum taken from neonates one day after
asphyxia was applied to target cells as an attacking factor. We initially
included control and postasphyxial serum-attacked groups and later included a
ucf-101 group in the study. In the postasphyxial serum-treated group,
cytosolic Omi/HtrA2 and caspase-3 expression in HK-2 cells was significantly
higher than in the control group. Moreover, the concentration of cytosolic
caspase-3 was found to be markedly decreased in HK-2 cells in the ucf-101
group. Our results suggest both that postasphyxial serum has a potent
apoptosis-inducing effect on HK-2 cells and that this effect can be partially
blocked by ucf-101. Taken together, our results demonstrate for the first
time that postasphyxial serum from neonates results in Omi/HtrA2
translocation from the mitochondria to the cytosol, where it promotes HK-2
cell apoptosis via a protease activity-dependent, caspase-mediated pathway.
Antibacterial and antioxidant activities of Licania tomentosa (Benth.) fritsch (crhysobalanaceae)
Authors: Silva J.B.N.F. , Menezes I.R.A. , Coutinho H.D.M. , Rodrigues F.F.G. , Costa J.G.M. , Felipe C.F.B.
Published: June 2012

This work describes the chemical composition, and evaluates the antimicrobial
and antioxidant activities of a hydroalcoholic extract from the leaves of the
Licania tomentosa. Gram positive and negative bacterial strains were used in
this work. Examination of the phytochemical composition of L. tomentosa
revealed the presence of secondary metabolites such as tannins, flavonoids,
saponins, alkaloids, steroids and triterpenoids. An antibacterial assay
pointed out that the extract had a lower minimal inhibitory concentration
(MIC - 32 ?g/mL) towards Staphylococcus aureus (ATCC12692). The extract also
presented antibacterial activity against other assayed bacteria, with the MIC
varying between 64 and 512 ?g/ mL. Our findings reveal that the extract
presented an antioxidative capacity lower than that of BHT at the same
concentration, used as positive control. Our results suggest that the levels
and combinations between the secondary metabolites of this plant should be
investigated to explain the demonstrated antibacterial activity.
Phytochemical screening and synergistic interactions between aminoglycosides, selected antibiotics and extracts from the bryophyte Octoblepharum albidum Hedw (Calymperaceae)
Authors: Vidal C.A.S. , Sousa E.O. , Rodrigues Fabíola , Campos Adriana , Lacerda S.R. , Costa J.G.M.
Published: June 2012

This work is the first to describe the modulation of antibiotic activity of
the bryophyte Octoblepharum albidum Hedw extract. The antibacterial activity
of ethanolic extract of O. albidum (EEOa), alone and in association with
aminoglycosides, was determined against six bacterial strains by a
microdilution test. The results showed a similar inhibitory activity of EEOa
against Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 33018
(MICs 512 ?g/mL). The synergistic effect of the extracts and aminoglycosides
was also verified. The most pronounced effects were obtained with EEOa +
gentamicin against E. coli and EEOa + kanamycin against K. pneumoniae with
MICs reduction (128 to 32 ?g/mL). The data from this study are indicative of
the antibacterial activity of the bryophyte O. albidum extracts and its
potential in modifying the resistance of aminoglycosides analyzed.
Fatty acid composition and Ω3/Ω6 ratios of the muscle lipids of six fish species in Sugla Lake, Turkey
Authors: Cakmak Selim , Zengin Gokhan , Guler Ozmen , Aktumsek Abdurrahman , Ozparlak Haluk
Published: June 2012

Fatty acid composition of the muscle lipids of Carassius gibelio,
Pseudophoxinus anatolicus, Sander lucioperca, Tinca tinca, Vimba vimba
tenella and Capoeta capoeta in Sugla Lake were determined. In all species,
palmitic acid (13.25- 18.54% of total fatty acids) and oleic acid
(11.93-34.23% of total fatty acids) were identified as major saturated fatty
acid (SFA) and monounsaturated fatty acid (MUFA), respectively.
Docosahexaenoic acid (DHA) was found to be the major polyunsaturated fatty
acid (PUFA) in T. tinca, C. capoeta, C. gibelio, P. anatolicus and S.
lucioperca while the predominant PUFA of V. vimba tenella was
eicosapentaenoic acid (EPA). S. lucioperca contained more ?3 fatty acids than
the other fish species. The percentages of total ?3 fatty acids were higher
than those of total ?6 fatty acids in all species. Since P. anatolicus is
endemic and endangered, this species should be protected and produced for
future marketing.
Evaluation of the combined effect of temperature and salinity on the filtration, clearance rate and assimilation efficiency of the mangrove oyster Crassostrea corteziensis (Hertlein, 1951)
Authors: Enríquez-Ocaña L.F. , Nieves-Soto M. , Piña-Valdez P. , Martinez-Cordova L.R. , Medina-Jasso María
Published: June 2012

An experimental trial was conducted to evaluate the effect of the combination
of four temperatures (23?, 26?, 29? and 32?C) and four salinities (25, 30,
35 and 40 PSU), on clearance (FR) and filtration (CR) rates, as well as on
the assimilation efficiency (AE) of the mangrove oyster Crassostrea
corteziensis. The interaction temperature-salinity had a significant effect
on the feeding physiology of the oyster; optimum results were observed in
the combination of 32?C and 35 PSU with a FR of 38.08 L?h-1?g-1, and a CR of
1.61 mg?h-1?g-1. The AE was higher in the combination of 29?C and 35 PSUs
with a value of 65.1%. Results suggest that C. corteziensis maintains its
feeding physiology in the gradient of temperature and salinity evaluated,
which characterizes the bivalve as an eurythermal and euryhaline organism,
with a better performance at moderate temperatures (29-32?C) and salinities
(~35 PSU).
Non-specific biological markers as a screening test for diagnostic of extrapulmonary tuberculosis
Authors: Stevanovic G. , Pelemis M. , Pelemis S. , Pavlovic M.
Published: June 2012

Serum concentrations of adenosine deaminase were determined in 223 febrile
patients. In 62, we discovered extrapulmonary tuberculosis. Serum levels of
immunoglobulin G were monitored in 287 febrile patients, and 68 had
extra-pulmonary tuberculosis. Serum concentrations of adenosine deaminase
were significantly higher in patients with tuberculosis compared to other
patients with fever of unknown origin. Serum concentrations declined during
antituberculosis therapy. A correlation with the localization of infection
was not found. Levels of immunoglobulin G were higher in patients with
tuberculosis. Both tests had high sensitivity and specificity and could
therefore be used for screening extrapulmonary tuberculosis; however, they
can only be interpreted adequately following a full clinical investigation.
Effect of cytokinins on shoot apical meristem in Nicotiana tabacum
Authors: Uzelac Branka , Janosevic Dusica , Stojicic Dragana , Budimir Snezana
Published: June 2012

Cytokinins are involved in plant cell proliferation leading to plant growth
and morphogenesis. The size, activity and maintenance of the shoot apical
meristem (SAM) are defined by a balanced rate of mitotic cell divisions and
functional cell differentiation that are controlled by cytokinins. In order
to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical
changes in the shoot apices of tobacco treated with benzyladenine (BA) were
compared to those of untreated control plants.
Plant regeneration from pulse-treated longitudinally sliced half cotyledon node explants of Turkish ochrus chickling [Lathyrus ochrus (L.) D.C.]
Authors: Saglam S.
Published: June 2012

The forage legume ochrus chickling [Lathyrus ochrus (L.) D.C.] which is
distributed in the Mediterranean region, is gaining importance in terms of
economy and agriculture in Turkey. However, the full potential of the legume
has yet to be realized due to the presence of neurotoxin, ?-N-oxalyl-L-a,
?-diaminopropionic acid (ODAP) causing lathyrism. This study aimed to develop
an efficient micropropagation system using longitudinally sliced cotyledon
node explants for use in Agrobacterium-mediated genetic transformation in the
future. The results show that the maximum number of shoots per explant was
achieved on MS medium solidified with 8 g/l isubgol gelled medium containing
0.30 mg/l BA-0.2 mg/l NAA. Well-developed shoots were rooted by pulse
treatment with 50 mg/l IBA and culturing on an 8 g/l isubgol gel solidified
MS medium. The results showed 60% rooting in the treated shoots. The rooted
plantlets were transferred to pots containing sand and organic matter and
acclimatized.
Does overhead irrigation with salt affect growth, yield, and phenolic content of lentil plants?
Authors: Giannakoula Anastasia , Ilias I.F. , Dragisic-Maksimovic Jelena , Maksimovic V.M. , Zivanovic Branka
Published: June 2012

Overhead irrigation of lentil plants with salt (100 mM NaCl) did not have any
significant impact on plant growth, while chlorophyll content and
chlorophyll fluorescence parameter Fv/Fm were affected. Under such poor
irrigation water quality, the malondialdehyde content in leaves was
increased due to the lipid peroxidation of membranes. In seeds, the total
phenolic content (TPC) was correlated to their total antioxidant capacity
(TAC). High performance liquid chromatography-mass spectrometry (HPLC-MS)
detection showed that flavonoids (catechin, epicatechin, rutin, p-coumaric
acid, quercetin, kaempferol, gallic acid and resveratrol) appear to be the
compounds with the greatest influence on the TAC values. Catechin is the
most abundant phenolic compound in lentil seeds. Overhead irrigation with
salt reduced the concentration of almost all phenolic compounds analyzed
from lentil seed extracts.
Contributions from population genetics to ecotoxicology and stress ecology in light of transformation to the population genomic era
Authors: Pertoldi C. , Bach L.A. , Svenning J.C. , Damgaard C. , Bayley M.
Published: June 2012

With the advent of the genomic era, which has partly been driven by advances
in stress ecology, there is enormous growth in molecular and computer
simulation techniques. Here we propose combining some of these techniques to
give more elaborate risk assessments that include the effects of population
variation in genotypes, phenotypes, and the way they link to aspects of life
history and adaptive potential. We focused on ways to ascertain whether
phenotypic plasticity or evolutionary responses constitute the basis for
observed stress responses, as well as on the extrapolation problem, i.e. how
do responses under controlled conditions correspond to those observed in
natural ecological populations or in evolutionary end-points of interest?
Additionally, we discuss the ways to integrate environmental variability into
risk analysis and pest control predictions that include gene-environment
interactions, focusing also on the importance of erosion of genetic diversity
by toxic stressors to the risk of population extinction.
Karyotype analysis of some Onobrychis (sainfoin) species in Turkey
Authors: Akçelik Somay , Avci S. , Uzun S. , Sancak C.
Published: June 2012

In this study, karyotype analysis of the species of Onobrychis sp. was
undertaken using the squash method. The results showed that the chromosome
number of Onobrychis tournefortii (Willd.) Desv., O. gracilis Besser, O.
hypargyrea Boiss. is 2n = 14 and O. argyrea Boiss. subsp. argyrea Boiss., 2n
= 16. The karyotype formula of O. tournefortii (Willd.) Desv. is 4m+3sm, of
O. hypargyrea Boiss. and O. gracilis Besser 3m+4sm, and of O. argyrea Boiss.
subsp. argyrea Boiss. 2m+ 5sm+1 st.
Genetic variability of bottle gourd Lagenaria siceraria (Mol.) Standley and its morphological characterization by multivariate analysis
Authors: Mladenovic Emina , Berenji J. , Ognjanov V. , Ljubojevic Mirjana , Cukanovic Jelena
Published: June 2012

A wide range of bottle gourd Lagenaria siceraria (Mol.) Standley germplasm
was collected from different parts of the world. Genetic resource
preservation and determination of genetic variability was carried out as a
foundation for future breeding work. The germplasm diversity collected in
Serbia is a result of its adaptation to diverse ecological conditions and
farmers? selection in accordance with their preference and ethnobotanical
utilization. The broad intraspecific variation of the plant, fruit and seed
morphology is a direct result of the research carried out. Principal
component analysis (PCA) of L. siceraria with 13 quantitative traits showed
continuous variation among accessions, primarily due to fruit and seed size
and shape. The evident reduction in trait variation is a direct result of the
preference for ornamental use that favored certain shapes and sizes of the
fruit, which has not significantly changed over the centuries.
Spatial and temporal distribution of phytoplankton in Lake Skadar
Authors: Rakocevic Jelena
Published: June 2012

Phytoplankton seasonal succession and spatial heterogeneity were studied in
Lake Skadar from February to December 2004. A total of 167 taxa from 6 algal
divisions were observed, with Bacillariophyta being best represented (52.8%).
The general pattern of phytoplankton seasonal succession in Lake Skadar was:
Bacillariophyta in the spring, Chlorophyta in early summer, Cyanobacteria and
Chlorophyta in late summer and Bacillariophyta and Chlorophyta in autumn and
winter. Distinct spatial heterogeneity was observed. The central, open part
of the lake (pelagic zone) was characterized by dominant euplanktonic
species, mostly diatoms, whereas the western and northwestern parts (more
isolated and shallower) had higher abundance of greens and blue-greens and a
higher percentage of resuspended benthic-epiphytic forms in the phytoplankton
community. Comparison with former phytoplankton data showed distinct
differences in terms of the qualitative and quantitative composition of the
phytoplankton community of Lake Skadar, which indicates lake deterioration.
Crown structure of Picea omorika trees in the plantation
Authors: Krstic M. , Stavretovic N. , Isajev V. , Bjelanovic I.
Published: June 2012

The study was carried out in Serbian spruce (Picea omorika Panc/Purkyn?)
plantations in the western Serbia. The paper presents results of the analysis
of crown development. The following elements were analyzed: total tree
height, height of the crown base, absolute and relative crown length, maximal
crown diameter, coefficient of crown spreading and degree of crown girth. We
discuss approaches to the modeling of tree crown growth and development,
growing under favorable environmental and stand conditions, without anomalies
in development. In order to establish the relationship between analyzed
factors, regression analyses were applied. Data fitting was by the analytic
method, by the implementation of Prodan?s functions of growth, linear and
parabolic function. Received models can be used for the simulation of various
growth and developing processes in forest.
Contributions to the biology of molting and growth of the Longarm river prawn Macrobrachium tenellum (Decapoda: Paleamonidae) in Mexico
Authors: Yamasaki-Granados S. , Ruíz-Fregozo M. , Vega-Villasante F. , Espinosa-Chaurand L.D. , Cortés-Jacinto E. , García-Guerrero M.
Published: June 2012

Studies on the molting cycle of Macrobrachium tenellum are not available,
which limits the scope of studies of growth and reproduction. The duration of
the molt cycle was determined under controlled experimental conditions. The
prawns were divided into four groups according to weight: Group 1 (1.0-1.9
g), Group 2 (2.0-2.9 g), Group 3 (3.0-3.9 g), and Group 4 (4.0-9.0 g). The
increase in total weight was higher in groups 2 (23.4%) and 3 (20.3%) than in
group 1 (~18%) and 4 (~18%). The increase in size after molting among all
groups was statistically different: in group 1 it increased 6.1% (highest)
and in group 2 it increased 2.2% (lowest). The duration of a complete cycle
was 8.9, 9.4, 10.4, and 15.1 days for groups 1, 2, 3, and 4, respectively.
The lengths of the molting cycles were not significantly different between
groups 1 and 2, but group 4 was different from group 1.
The first record of the species Lacinius erinaceus Staręga, 1966 (Opiliones, Phalangiidae) in Turkey with some SEM studies on its morphology
Authors: Kurt K. , Erman Ö.K.
Published: June 2012

The harvestman species of Lacinius erinaceus Star?ga 1966, recorded for the
first time in Turkey, is presented in this paper. The characteristic
features of this species are described and illustrated and data regarding
collecting sites and distribution all over the world are given. Scanning
electron microscopy (SEM) studies on the dorsal integument, dorsal habitus,
chelicerae, pedipalpus, trident, the ocularium and legs of the specimens are
also presented. Localities of the collecting sites are plotted on a map.
A new epigean false scorpion: Roncus sumadijae n.sp. (Neobisiidae, Pseudoscorpiones) from the Balkan Peninsula (Western Serbia)
Authors: Curcic B.P.M. , Dimitrijevic R.N. , Tomic V.T. , Pecelj M. , Ilic B.S. , Makarov S.E. , Curcic Nina , Pesic Snezana
Published: June 2012

A new endemic epigean species from the village of Adzina Livada, nr.
Kragujevac, Mts. Gledicke Planine, western Serbia, is erected, described and
thoroughly illustrated. Its main morphometric characters and important
diagnostic features are analyzed and compared to the two closest congeners,
Roncus ivanjicae B. Curcic, and R. golijae B. Curcic from western Serbia,
respectively.
New data on the distribution of Ranunculus polyphyllus Waldst. & Kit. ex Willd. in Serbia
Authors: Panjkovic Biljana , Peric R. , Stojsic Vida , Batanjski Vera
Published: June 2012

During our field studies of saline meadows, salt marshes and swampy flora
carried out near the Backi Monostor and Melenci villages (Vojvodina, Serbia)
several specimens of the genus Ranunculus L. (Ranunculaceae) were found and
identified as Ranunculus polyphyllus Waldst. & Kit. ex Willd. Apart from two
records from the beginning of the last century, the appearance of this rare
species has been uncertain in the flora of Serbia. We confirmed its presence
at one known and two new localities in salt marsh and aquatic floating
communities. Also, this is the first herbarium evidence of the presence of
this species in Serbia.
Does the diurnal activity pattern of carabid beetles depend on season, ground temperature and habitat?
Authors: Tuf I.H. , Dedek P. , Veselý M.
Published: June 2012

The influence of season, ground temperature and habitat on diurnal epigeic
activity of ground beetles (Coleoptera: Carabidae) in floodplain forest and
neighboring clear-cut area was studied in late spring and early autumn by
pitfall trapping. Among the material collected were 35 species of ground
beetles. We recorded a significant influence of daytime factors on epigeic
activity in 16 species. The epigeic activity of 13 species was co-affected by
the temperature of the soil surface. The activity of some species differed,
depending on season and locality.
The “widow maker” warning sign or Wellens’ syndrome: A case report
Authors: Karadzic Mirjana , Vuckovic-Filipovic Jelena , Davidovic G. , Iric-Cupic Violeta , Tasic M. , Kovacevic Z.
Published: June 2012

Wellens? syndrome, also known as LAD (left anterior descending) coronary
T-wave syndrome, ?widow maker? or warning sign, is a potentially unrecognized
critical proximal LAD stenosis with possible fatal consequences. It can be
associated with extensive acute anterior wall myocardial infarction, with
left ventricular dysfunction and a lethal outcome within a few days after the
onset of symptoms. It usually consists of a typical ECG finding in the
precordial leads that represents a significant proximal LAD stenosis in
patients with unstable angina pectoris. Although this syndrome is not
indicated for PCI (the patient is usually pain-free at the time of
electrocardiography registration), it is necessary to recognize the
characteristic pattern and perform an emergency coronary angiography and
percutaneous or surgical revascularisation of the affected blood vessel. Here
we present the case report of a 47 year-old woman without previous anamnesis
of coronary disease. On admission to the Coronary Care Unit she was chest
pain-free and had all the indicators of Wellens? syndrome.
Summer aspect of phytoplankton communities in some Montenegrin lakes: Are there changes after more than two decades?
Authors: Rakocevic Jelena
Published: June 2012

Qualitative and quantitative phytoplankton compositions of 10 Montenegrin
lakes were investigated in the summer of 2007. The obtained results were
compared with a previous study-period that was undertaken two decades ago. In
the first period, diatoms numerically dominated the phytoplankton community
in all studied lakes, while in the second period, the same was observed only
in three of the ten lakes; in other studied lakes the relative contributions
of green algae, dinoflagellates and/or cyanobacteria increased, while the
contribution of diatoms decreased. The shift observed in phytoplankton
composition and diversity in some of the studied lakes indicates an increase
in the trophic level over the two decades. The sustainable management plan of
the aquatic ecosystems in Montenegro should include the establishment of an
environmental monitoring system in order to record any alterations that may
take place in water quality.
Influence of nutrient substrates on the expression of cellulases in Cerambyx cerdo L. (Coleoptera: Cerambycidae) larvae
Authors: Pavlovic R. , Grujic Marica , Dojnov Biljana , Vujcic Miroslava , Nenadovic Vera , Ivanovic Jelisaveta , Vujcic Z.
Published: June 2012

The expression and distribution of digestive cellulases along the midgut of
Cerambyx cerdo larvae were analyzed for the first time and are presented in
this article. Four groups of larvae were examined: larvae developed in the
wild; larvae taken from the wild and successively reared on an artificial
diet based on polenta; and larvae hatched in the laboratory and reared on two
different artificial diets. Seven endocellulase and seven ?-D-glucosidase
isoforms were detected in all midgut extracts of C. cerdo with a zymogram
after native PAGE. We observed that C. cerdo larvae are capable of producing
cellulase isoforms with different PAGE mobilities depending on the nutrient
substrate. From our findings it can be assumed that, depending on the
distribution of endocellulase and ?-D-glucosidase, cellulose molecules are
first fragmented in the anterior and middle midgut by endo-?-1,4-glucanase;
subsequently, the obtained fragments are broken down by ?-D-glucosidase
mostly in middle midgut.
Quantitative analysis of the dystrophin gene by real-time PCR
Authors: Maksimovic Nela , Andjelkovic Ana , Milic-Rasic Vedrana , Rakocevic-Stojanovic Vidosava , Kastratovic-Kotlica Biljana , Brankovic S. , Damnjanovic Tatjana , Jekic Biljana , Bunjevacki Vera , Lukovic Ljiljana , Perovic Dijana , Cvjeticanin Suzana , Novakovic Ivana
Published: June 2012

Duchenne and Becker muscular dystrophy (DMD/BMD) are severe X-linked
neuromuscular disorders caused by mutations in the dystrophin gene. Our aim
was to optimize a quantitative real-time PCR method based on SYBR? Green I
chemistry for routine diagnostics of DMD/BMD deletion carriers. Twenty female
relatives of DMD/BMD patients with previously detected partial gene deletions
were studied. The relative quantity of the target exons was calculated by a
comparative threshold cycle method (??Ct). The carrier status of all subjects
was successfully determined. The gene dosage ratio for non-carriers was
1.07?0.20, and for carriers 0.56?0.11. This assay proved to be simple, rapid,
reliable and cost-effective.
Genetic diversity revealed by AFLP markers in Albanian goat breeds
Authors: Hoda Anila , Sena Lumturi , Hykaj Gentian
Published: June 2012

The amplified fragment length polymorphism (AFLP) technique with three
EcoRI/TaqI primer combinations was used in 185 unrelated individuals,
representative of 6 local goat breeds of Albania, and 107 markers were
generated. The mean Nei?s expected heterozygosity value for the whole
population was 0.199 and the mean Shannon index was 0.249, indicating a high
level of within-breed diversity. Wright?s FST index, Nei?s unbiased genetic
distance and Reynolds? genetic distance were calculated. Pairwise Fst values
among the populations ranged from 0.019 to 0.047. A highly significant
average FST of 0.031 was estimated, showing a low level of breed subdivision.
Most of the variation is accounted for by differences among individuals.
Cluster analysis based on Reynolds? genetic distance between breeds and PCA
were performed. An individual UPGMA tree based on Jaccard?s similarity index
showed clusters with individuals from all goat breeds. Analysis of population
structure points to a high level of admixture among breeds.
Ontology-based home service model
Authors: Wei Moji , Xu Jianliang , Yun Hongyan , Xu Linlin
Published: June 2012

This paper researches Home Service retrieval and invocation for smart home.
We represent ontology-based Home Service Model to retrieve and invoke
services according to user?s needs automatically. Firstly by analyzing the
context of home service, we differentiate key concepts in the field and
analyze the relations among them, and as a result, an upper ontology as a
fixed viewpoint for further more detailed conceptualization is achieved. Then
by reifying the concepts of the upper ontology, we construct two domain
ontologies which are Function Concept Ontology and Context Concept Ontology
to annotate the semantic of Home Service from different facets. The Function
Concept Ontology is constructed with the guidance of Maslow's Hierarchy of
Needs to annotate the goal of service for automating service retrieval. For
service invocation, the Context Concept Ontology is constructed by analyzing
the contents that services operate. Finally two scenarios for different types
of services are given to demonstrate the usage of the model.
Recommending collaboratively generated knowledge
Authors: Chen Weiqin , Persen Richard
Published: June 2012

With the development and adoption of information technologies in education,
learners become active producer of knowledge. There is an increasing amount
of content generated by learners in their learning process. These emerging
learning objects (ELOs) could potentially be valuable as learning resources
as well as for assessment purpose. However, the potentials also give rise to
new challenges for indexing, sharing, retrieval and recommendation of such
learning objects. In this research we have developed a recommender system for
emerging learning objects generated in a collaborative knowledge building
process and studied the implications and added values of the recommendations.
We conducted two evaluations with learners to assess and improve the system?s
design and study the quality and effects of the recommendations. From the
evaluations, we received generally positive feedback and the results confirm
the added values of the recommendations for the knowledge building process.
Landscape visualisation of the Roman site Margum
Authors: Blagojevic Ivana
Published: June 2012

There are numerous traces around the world that testify on the duration and
significance of the Roman Empire. There are many more Roman traces in Serbia,
than it could be seen in the field. Many traces have been lost or forgotten
forever. Roman Margum is one of them. On the base of outline maps and
historical facts, this work aims to revive the Roman era on the site Margum,
in an innovative way, by using natural vegetation and installation. The
approach to work has a multidisciplinary character. By analyzing the current
situation and by using a check list, it was found that partly carried out
archaeological excavations were not visible, and that their invisibility was
more enhanced with invasive vegetation that occupied the space. The
revitalization of the site Margum will not only contribute to the cultural
heritage of Serbia, but also to a tourist activation of the space and its
surroundings and to raising the attractiveness of the site as well.
Influence of nitrogen form on growth of invasive species Acer negundo L. and Ailanthus altissima (Mill.) swingle
Authors: Djukic Matilda , Djunisijevic-Bojovic Danijela , Grbic Mihailo , Skocajic Dragana , Obratov-Petkovic Dragica , Bjedov Ivana
Published: June 2012

Relative amounts of nutrients, especially nitrogen, the most abundant
macro-element, and also the distribution of ammonium ions in relation to
nitrate ions, in the soils of different ecosystems, are determined by many
factors. The most important are: temperature, pH of substrate, accumulation
of organic matter, presence of allelopathic compounds, degree of oxygenation,
etc. The ability of plants to adapt to these variations influences their
production of bio-mass, the rate of expansion in different habitats, and the
impact on ecosystem and biodiversity. This paper analyzes the impact of
different forms of nitrogen (NO3 - and NH4 +) on the growth of seedlings of
invasive species Acer negundo L. and Ailanthus altissima (Mill.) Swingle. The
results show that nitrogen nutrition only in the form of NH4 + ions
significantly affects the reduction in shoot dry weight. Compared to the
nutrition with both forms of nitrogen together, aerial parts of Ailanthus
altissima were reduced by 62.5%, and leaf area by 66.7%, while Acer negundo
seedlings had reduction in dry mass of aboveground part by 89.5%, root by
81.2% and leaf area by 85.8%. Nutrition with nitrate form of nitrogen led to
a proportionally small, but statistically significant decrease in dry mass of
aboveground parts and roots as well as leaf area of Acer negundo, while in
Ailanthus altissima seedlings, it was only the mass reduction of aboveground
parts that was significantly influenced, so it can be assumed that this
species is more resistant to the lack of both forms of nitrogen. The fact
that both species produced significantly more biomass when nitrogen was
present in both forms may be important in controlling the spread of alien
species, or in their potential use in phytoremediation.