bluuebunny/crossref_metadata_2025 huggingface dataset:
A Successful Gas Injection Pilot Test in a Mature and Complex Fractured Carbonate Reservoir, Oxiacaque Field, Southern Mexico
Authors: Arteaga M. , Molina J. , Hernández R. , Flamenco F.
Published: April 2008

This paper presents the main results of a sour gas injection pilot test performed in the Oxiacaque field, a mature and natural fractured carbonate reservoir in southern Mexico. This field is part of a complex called the Complejo Bermúdez. The Complejo is the largest oil accumulation in terms of production in the Mexican Southern Region. It was discovered in 1973, and it consists of five producing fields referred to as Samaria, Íride, Cunduacán, Platanal and Oxiacaque. The oil gravity in Oxiacaque field ranges from 29 to 31 °API and it is producing from highly fractured carbonates of Cretaceous and Jurassic ages.

Oxiacaque field is located to the east of Cunduacán and North of Íride field. As of August 31, 2007, Oxiacaque has produced 161 MMBBL of oil and 426 BCF of gas. It produced 11 MBBL of oil and 52 MMCF of gas per day, from 7 active wells during August 2007. Structurally Oxiacaque is the highest field in the Complejo Bermúdez and has had some wells shut in due to high GOR production. At the initial formation pressure of 7610 psia at 15,223 ftss and a temperature of 277°F, the oil is undersaturated with a saturation pressure of 4565 psia. After 34 years of production, a secondary gas cap has been formed. Current reservoir pressure is 2275 psia.

Prior to implementing a full field injection project, a pilot test with sour gas was performed in this field. Major objectives of this pilot were: (a) to evaluate the efficiency of immiscible gas injection in maintaining reservoir pressure, (b) to evaluate its benefit on oil production, (c) to confirm level of pressure communication in the other fields – a critical issue for expanding the project – and (d) apply a coordinated plan of gas injection monitoring and surveillance from subsurface to surface, as an aggregated value to develop field experience. All of these objectives had a strong dependency on the complexity of the fracture system, the influence of faulted blocks and the critical rate of injection. It is believed that the injection rate seriously affected a previous water injection project, with channeling and fast breakthroughs in Samaria and Cunduacán fields.

The sour gas injection pilot was initiated in the Oxiacaque field in November 2006. At the end of August 2007, a volume of 13 BCF of gas has been successfully injected through two lower and upper Cretaceous wells, at an average rate of 30 MMCFD per well.
Possible Mechanisms and Case Studies for Enhancement of Oil Recovery and Production Using In-Situ Seismic Stimulation
Authors: Kostrov Sergey , Wooden William
Published: April 2008

Beginning in the early 1980's and continuing for several decades, interest in elastic wave stimulation focused primarily on acoustic and to a lesser degree on surface vibroseis1,2,3,4. In the late 1990′s a third type of elastic wave stimulation, in-situ seismic stimulation was developed by Applied Seismic Research Corporation5,6,7 (ASR). The ASR Hydro-Imapct tool creates high-energy elastic waves identical to earthquakes but at reservoir datum (in-situ) and lower magnitudes. Theoretical and experimental research performed by many independent laboratories has supported these claims.

Extensive field studies using seismic stimulation have proven to increase oil production and oil recovery (EOR) an average of 20–40 percent in wells at distances as far as 1 mile from the tool. Some wells have shown truly remarkable increases exceeding 500 percent. In September of 2007 the Texas Railroad Commission certified seismic stimulation as the first new EOR process in several decades. EOR certification gives Texas operators using seismic stimulation a 50 percent reduction in severance tax on total production for 10 years.

This paper presents a theoretical background and stimulation results on all types of oil fields
CO2 Storage in Low Permeability Formations
Authors: Cinar Y. , Bukhteeva O. , Neal P. R. , Allinson W. G. , Paterson L.
Published: April 2008

This paper investigates ways in which CO2 storage in low-permeability formations might be made viable and how such formations might compete with more distant formations with higher permeability. Hypothetical, but realistic cases are postulated to examine the effect of reservoir engineering and economic sensitivities. The cases compare (a) a large CO2 source with nearby abundant low-permeability pore space (0.1–10md) with (b) the same source with storage in a remote high permeability (100md) site. Based on reservoir engineering and economic analyses, the paper quantifies the injectivity of the sites, assesses the number of wells required and finally estimates the costs of capturing CO2, transporting it to the storage sites and injecting it into the sub-surface.

The paper shows that for the given assumptions, Carbon Capture and Storage (CCS) in the remote high-permeability formation can be significantly cheaper than CCS in the low-permeability storage site. The cost advantage of the considerably higher permeabilities expected in the remote area by far outweighs the cost of transport over the extra distance. This is the case despite applying horizontal drilling and fracturing technologies.

The economics of both the low and high permeability formations can be improved markedly by using horizontal rather than vertical wells. However, CCS in the remote high-permeability storage site still retains its cost advantage using this technology. Fracturing increases injectivity considerably for low permeability reservoirs and for both vertical and horizontal wells. However, it does not have a significant effect on reservoirs that have high permeability. Therefore, the technology helps injection in the low-permeability storage site much more than in the remote high-permeability storage formations. However, although under some conditions the relative economics of the low-permeability formation can be improved significantly by fracturing the low-permeability formation, the improvement is not sufficient to reverse the cost disadvantage of the low-permeability storage site.
Flood Front Tracking and Pulse Test Time Lags
Authors: Orangi Abdollah , Ershaghi Iraj
Published: April 2008

Improvements in downhole sensors have opened up new opportunities to obtain continuous recordings of rate and pressure data at producing and injection wells. We have examined the progression of lag time at observation wells when injection wells are subjected to pre-scheduled or unsupervised rate changes. A monitoring of time lags and comparisons with that corresponding to the first pulse at the start of injection is correlated with the location of displacement front. Analytical solutions to calibrate numerical test cases for linear and radial flow geometries are presented. The results of these systems demonstrate the potential of monitoring repeated pulses for front tracking in immiscible fluid displacement processes.
Mechanism of the Effect of Micro-Forces on Residual Oil in Chemical Flooding
Authors: Xia H. F. , Wang D. M. , Wang G. , Ma W. G. , Liu J.
Published: April 2008

Experimental results indicate that the displacement efficiency (De) after flooding by driving fluids with and without elastic characteristics is different at the same viscosity, (i.e. at the same pressure gradient). Macro forces cannot explain the difference of the De by different driving fluids. Therefore, the changes of micro forces acting on residual oil by driving fluids with elastic properties and the increase in the De are analyzed.

In this paper, through theoretical and experimental analysis, the influence of elastic characteristics of the driving fluid on De is analyzed. The changes in the streamlines and velocity of different fluids flowing in simplified pore models are mathematically simulated, the changes in micro forces caused by the change in velocity and streamline and its effect on residual oil are analyzed. This micro force does not change the pressure gradient and mainly acts on the protruding portion of different types of residual oil, causing the protruding portion to change shape and mobilize or migrate. The results on visualization core models confirm the above calculation and analysis, the De after flooding by fluids with different elastic properties are given.

The above research results show that the streamlines and velocities in pores are different when the elasticity of the displacing fluid varies, micro forces acting on the residual oil protruding portion increase with the increase in elasticity, resulting in an increase in De for visco-elastic displacing fluids at constant pressure gradient conditions.

This method of micro force analysis and its conclusions should be useful to further understand the mechanism of displacement efficiency in porous media, should be useful in designing, screening and developing better chemical flooding products, should be useful in the further development of the mechanism of micro seepage flow through porous media.
New Developments in Production Technology for Polymer Flooding
Authors: Yan Wang , Demin Wang , Jun Wan , Jiangtao Luo , Runtao Yu , Zengyou Dong
Published: April 2008

After large scale polymer flooding in the field, due to the high elasticity and viscosity of the fluid, the efficiency and effective life-span of the producers (and injectors) decreased significantly, new technologies were developed.

After polymer is produced, severe eccentric wear on sucker rods occur. To solve the problem, on the basis of theoretical and lab studies, techniques to reduce the normal force on sucker rods and control its eccentric wear were developed. Field practice shows that this technology has increased the average life span of pumping wells by 3 times.

The effective time of conventional fracturing and acid stimulation of polymer injectors is less than 3 months. Therefore, technologies of resin-coated sand tail-in fracturing and surfactant stimulation were developed. These 2 new technologies have increased the effective time of injector stimulation by about 5 times.

The above techniques are all used in a mass scale in the field with significant results; they can and are also used on conventional wells.
Review of Practical Experience & Management by Polymer Flooding at Daqing
Authors: Dong H. Z. , Fang S. F. , Wang D. M. , Wang J. Y. , Liu Z. , Hong W. H.
Published: April 2008

This paper describes successful experiences employed during polymer flooding at Daqing that will be of considerable value to future chemical floods, both in China and elsewhere. Based on laboratory findings, new thoughts have been developed that expand conventional ideas concerning favorable conditions for mobility improvement by polymer flooding. Particular advances integrate reservoir engineering approaches and technology which is elementary for successful application of polymer flooding. These include: (1) Considering permeability differential among the oil zones and interwell continuity, optimizing the oil strata combination and well pattern design. (2) The injection procedures and injection formula are the key points when designing a polymer flood project. These points include: profile modification is needed before polymer injection and zone isolation is of value during polymer injection, higher molecular weight of the polymer used in the injected slugs, large polymer bank size, higher polymer concentrations and injection rate based on the well spacing and injection pressure. (3) Characterizing the entire polymer flooding process in five stages, with its dynamic behavior distinguished by the water cut changes. Additional techniques involved with reservoir engineering should also be considered, such as dynamic monitoring using well logging, well testing, and tracers. Effective techniques are also needed for surface mixing, injection facilities, oil production, and produced water treatment.

Continuous innovation and effective response to new challenges must be a priority during polymer flooding. New directions and opportunities at Daqing will (1) explore the feasibility of polymer flood application in poorer ("third-class") strata, (2) to identify new polymers to suit portions of the reservoir with higher temperatures and higher water salinities, and (3) continually see improvements in our approach to polymer flooding.
Current Status and Prospects of ASP Flooding in Daqing Oil Fields
Authors: Fenglan Wang , Zhenyu Yang , Junzheng Wu , Yang Li , Guangyu Chen , Shukai Peng , Ying Wang
Published: April 2008

With the development of EOR technologies, the ASP flooding technology of Daqing oilfields has become mature step by step. For years of research and practice, Daqing has established a comprehensive ASP industrial application technology, including research and manufacturing of surfactant, study of the mechanism of ultra-low interfacial tension, surface injection allocation technique and lifting techniques. At present, the large-scale industrial field tests on ASP flooding have been carried out in Daqing oilfields. ASP flooding is going to be the dominant technology in the ultrahigh water cut development phase. The development of ASP technology experienced three stages. First stage is laboratory experiments stage. Having the property of low acid number and high wax content, Daqing oil had been thought hardly to be applied with ASP technology. However, in 1988, formulas had been screened which achieved an ultra-low IFT with Daqing oil. Physical simulation experiments indicated that the final oil recovery achieved to 20% OOIP over that of water flooding.1–3 Second stage is pilot field tests stage. Daqing oilfields had completed 5 ASP flooding pilot field tests since 1994. All have gotten high displacement efficiency which according with the laboratory results. Third stage is industrial pilot tests stage. Daqing implemented the development and production of alkyl benzene sulfonate (adapt to strong base and weak base) with independent innovation. Since year 2000, several industrial ASP flooding tests have been carried out successively which have shown a satisfied effect of higher oil production and lower water cut. The field test scale is from 1 injector-4 producers to 6 injectors-12 producers. These days, large-scale industrial field application is ongoing in Daqing oilfields.4–8
The Application of Hydrocarbon-Degrading Bacteria in Daqing's Low Permeability, High Paraffin Content Oilfields
Authors: Zhaowei Hou , Peihui Han , Jianjun Le , Jianfei Chang , Xumou Dou , Menghua Guo , Xinghong Chen
Published: April 2008

To seek an effective oil recovery approach, Brevibacillus brevis and Bacillus cereus were screened and applied in a Microbial Enhanced Oil Recovery (MEOR) process to recover oil from Daqing low permeability areas. The selected bacteria were found to be highly compatible with indigenous microbes; the laboratory data shows: (1) The oil-water interfacial tensions (IFT) after microbial treatment decreased by 50%; (2) The alkanes with middle and high carbon numbers could be degraded; (3) The viscosity of treated crude oil decreased by about 40%; (4) The content of paraffin and resin decreased from 1.3% to 4.9%, and from 0.7% to 2.6%, respectively, thus improving significantly the rheology of the crude oil; and (5) The oil recovery from laboratory coreflooding achieved about 6.5% original oil in place (OOIP) over that achieved by waterflooding.

From 2002 to 2005, microbial huff ‘n’ puff trials have been conducted in 70 wells altogether in the Daqing Chaoyanggou (0.5×10−3μm2−25×10−3μm2) and Pubei areas (103×10−3μm2). Effectiveness was observed in 43 out of 60 Chaoyanggou wells, with accumulative incremental oil amounting to 9175.7 tons. Eight out of 10 Pubei wells showed effective results as well, with 1873 tons of accumulative incremental oil. The total incremental oil from the two areas amounted to 11,000 tons, with an average of about 158 tons for one individual well.

Based on the success of microbial huff ‘n’ puff trials, a microbial flooding pilot test with two injectors and 10 producers was carried out in the Chaoyanggou low permeability area (25×10−3μm2) in June 2004. The bacteria injection was followed by a pressure decrease in two injectors and an increase in the fluid injection. The daily produced fluid and oil increased from 43.6 tons to a high of 79.6 tons and from 24.7 to 40.8 tons, respectively. Water cut decreased from 45.2% to 38.6%. By the end of Dec, 2007, 7 out of 10 wells showed significant oil production response. The incremental oil is about 13,000 tons. The analysis made to the effective and non-effective wells demonstrates that MEOR plays an important role in establishing an effective driving system.
Application of Surfactants with Narrow Equivalent Weight Distribution and Desirable Structure to Daqing ASP Flooding
Authors: Wu Xiaolin , Zong Liping , Chen Jie , Wang Haifeng , Yang Yong , Shan Cunlong , Geng Jie
Published: April 2008

Alkyl benzene surfactants with narrow equivalent weight distribution (NEWD) and desirable structure were prepared by the alkylation of olefin, sulfonation and neutralization. Due to the favorable composition and molecular structure, they prove to have exceptionally high activity and oil displacement ability. The laboratory evaluation indicates: (1) ASP formulation can reduce oil-water interfacial tension (IFT) to/below 10−3 mN/m at very low surfactant concentration (0.05–0.3 wt%) and wide concentration range of alkaline (Na2CO3, 0.8–1.4 wt%). (2) The addition of Na2CO3 instead of NaOH reduces the risk of equipment corrosion and severity of produced fluid treatment. (3) Compared with conventional surfactants, this class of surfactant is much more compatible with Daqing crude oils with different properties. (4) The effect of surfactant chromatographic fractionation on ASP performance is dramatically reduced due to its narrow equivalent weight distribution. (5) Laboratory core flooding can achieved about 20 per cent original oil in place (OOIP) incremental over that for water displacement.

A 75 meter well-spacing ASP flooding field test composed of 3 injectors and 4 producers was conducted in Daqing Sabei area in October, 2004 and was completed in 2005. Effective response began to be observed for the central producing well No. 122 at the injection of 0.09 PV. Water cut decreased by 25.1 percent from 95.3 to 70.2 percent at the injection of 0.378 PV and the period of water cut below 80 percent was maintained for 0.42 PV. The daily oil production increased from 1 to 4 tons. For another producing well No. 133, water cut decreased by 71.3 percent from 99.0 to 28.7 percent at the injection of 0.575 PV. The final oil recovery amounted to 24.66 percent OOIP over water flooding.
The Methods of Improving Polymer Flooding Performance at Northwest Area of Lamadian
Authors: Shao Z. B. , Gao S. L. , Huang F. S. , Hu G. B. , Yan W.
Published: April 2008

This paper describes the main methods to improve the effect of polymer flooding with the process of project optimization and implementation in northwest area of Lamadian oil field. According to the well pattern characteristics and conditions of oil strata in this area.. Compared to the 5-spot well pattern, the connectivity factors and the sweep of the injected water by line in diagonal increased on both sides of fault. Investment was decreased and the number of inefficient wells to be reduced result from injection and production wells are completely utilized. Based on the reservoir geological features, ultra-high molecular weight polymer was one of the better option for the case design. According to the reservoir dynamic performance during polymer flooding process, integrated adjustment measures were applied to every developing stages. By means of above methods, the incremental oil recovery can be achieved to 15.3% of northwest area polymer flooding in Lamadian.
Performance and Effect Analysis of ASP Commercial Flooding in Central Xing 2 Area of Daqing Oil Field
Authors: Li Hong-Fu , Xu Dian-Ping , Jiang Jiang , Du Xiong-Wen , Hong Ji-Chun , Jiang Yang , Xu Yan-Shu
Published: April 2008

The results of five alkaline-surfactant-polymer (ASP) flood pilot tests carried out in single oil-layer and small scale showed that the incremental oil recoveries by ASP over that of the water flooding are over 20% OOIP. In order to realize the industrializing of ASP flooding, an ASP flood field test started in Central Xing2 Area of Daqing oilfield, using the surfactant produced by Daqing oilfield. Based on the great experimental achievements, the chemicals in ASP system were decreased greatly by optimizing the formulation and the injection method. Compared with the small scale site test area, the surfactant, polymer and alkaline were decreased by 1/3, 2/5 and 1/6, respectively, the chemicals can save 147 million RMB. Although the chemicals were decreased, the pilot test results show that the oil recovery was increased by 18% OOIP using the ASP flooding over that of water flooding.
No Long-Term Risk for Increased Spread of PNSP in Day-Care Centres by Permitting Carriers to Remain in the Day-Care Centre Group
Authors: Christenson B. , Henriques Normark B. , Ardung B. , Sjöström K. , Eriksson G. , Hartvig P. , Sylvan S.P.E.
Published: April 2008

In a 6-year prospective epidemiological intervention study the spread of pneumococci non-susceptible to penicillin
(PNSP) was studied among children attending day-care centres (DCCs). A primary aim was to investigate whether
there was a risk for spread of PNSP by permitting children carrying PNSP strains to remain in the DCC. Carriers were followed
until they presented negative cultures. The PNSP strains were characterised by serotyping, antibiotic susceptibility
testing and clonality. Thirteen children with PNSP, initiated sampling of 321 children, 66 DCC personnel and 149 family
members. Twenty-three (7 %) asymptomatic carriers were identified but none among the personnel. The most spread serotype
was 6B (47%), followed by 19F (17%) and 9V (14%). The PNSP isolates were resistant to three antibiotics or
more (69%). The spreading capability and duration of carriage differed between PNSP clones but no long-term risk for increased
spread of PNSP in DCCs by carriers was found.
The Impact of Supplemental Instruction on Students in Stem Courses: Results from San Francisco State University
Authors: Peterfreund Alan R. , Rath Kenneth A. , Xenos Samuel P. , Bayliss Frank
Published: April 2008

Comparisons between participants and non-participants in supplemental instruction classes at San Francisco State University over a six-year period show positive impacts in terms of increased student performance and progression through subsequent courses in a sequence, despite the lower academic indicators of the supplemental instruction participants. More females participated than were represented in the course as a whole, but the effects were greater for males. Effects were particularly striking for students from underrepresented minority groups, particularly in introductory courses.
Association of FTO With Obesity-Related Traits in the Cebu Longitudinal Health and Nutrition Survey (CLHNS) Cohort
Authors: Marvelle Amanda F. , Lange Leslie A. , Qin Li , Adair Linda S. , Mohlke Karen L.
Published: April 2008

OBJECTIVE—The underlying genetic component of obesity-related traits is not well understood, and there is limited evidence to support genetic association shared across multiple studies, populations, and environmental contexts. The present study investigated the association between candidate variants and obesity-related traits in a sample of 1,886 adult Filipino women from the Cebu Longitudinal Health and Nutrition Survey (CLHNS) cohort.

RESEARCH DESIGN AND METHODS—We selected and genotyped 19 single nucleotide polymorphisms in 10 genes (ADRB2, ADRB3, FTO, GNB3, INSIG2, LEPR, PPARG, TNF, UCP2, and UCP3) that had been previously reported to be associated with an obesity-related quantitative trait.

RESULTS—We observed evidence for association of the A allele of rs9939609 (FTO intron 1) with increased BMI (P = 0.0072 before multiple test correction), baseline BMI (P = 0.0015), longitudinal BMI based on eight surveys from 1983 to 2005 (P = 0.000029), waist circumference (P = 0.0094), and weight (P = 0.021). The increase in average BMI was ∼0.4 for each additional A allele. We also observed association of the ADRB3 Trp64Arg variant with BMI, waist circumference, percent body fat, weight, fat mass, arm fat area, and arm muscle area (P < 0.05), although the direction of effect is inconsistent with the majority of previous reports.

CONCLUSIONS—Our study confirms that FTO is a common obesity susceptibility gene in Filipinos, with an effect size similar to that seen in samples of European origin.
Blockade of α4 Integrin Signaling Ameliorates the Metabolic Consequences of High-Fat Diet–Induced Obesity
Authors: Féral Chloé C. , Neels Jaap G. , Kummer Christiane , Slepak Marina , Olefsky Jerrold M. , Ginsberg Mark H.
Published: April 2008

OBJECTIVE—Many prevalent diseases of advanced societies, such as obesity-induced type 2 diabetes, are linked to indolent mononuclear cell–dependent inflammation. We previously proposed that blockade of α4 integrin signaling can inhibit inflammation while limiting mechanism-based toxicities of loss of α4 function. Thus, we hypothesized that mice bearing an α4(Y991A) mutation, which blocks signaling, would be protected from development of high-fat diet–induced insulin resistance.

RESEARCH DESIGN AND METHODS—Six- to eight-week-old wild-type and α4(Y991A) C57Bl/6 male mice were placed on either a high-fat diet that derived 60% calories from lipids or a chow diet. Metabolic testing was performed after 16–22 weeks of diet.

RESULTS—α4(Y991A) mice were protected from development of high-fat diet–induced insulin resistance. This protection was conferred on wild-type mice by α4(Y991A) bone marrow transplantation. In the reverse experiment, wild-type bone marrow renders high-fat diet–fed α4(Y991A) acceptor animals insulin resistant. Furthermore, fat-fed α4(Y991A) mice showed a dramatic reduction of monocyte/macrophages in adipose tissue. This reduction was due to reduced monocyte/macrophage migration rather than reduced monocyte chemoattractant protein-1 production.

CONCLUSIONS—α4 integrins contribute to the development of HFD-induced insulin resistance by mediating the trafficking of monocytes into adipose tissue; hence, blockade of α4 integrin signaling can prevent the development of obesity-induced insulin resistance.
Protein Engineering Strategies for Sustained Glucagon-Like Peptide-1 Receptor–Dependent Control of Glucose Homeostasis
Authors: Picha Kristen M. , Cunningham Mark R. , Drucker Daniel J. , Mathur Ashok , Ort Tatiana , Scully Michael , Soderman Avery , Spinka-Doms Tracy , Stojanovic-Susulic Vedrana , Thomas Beth Ann , O'Neil Karyn T.
Published: April 2008

OBJECTIVE—We have developed a novel platform for display and delivery of bioactive peptides that links the biological properties of the peptide to the pharmacokinetic properties of an antibody. Peptides engineered in the MIMETIBODY platform have improved biochemical and biophysical properties that are quite distinct from those of Fc-fusion proteins. CNTO736 is a glucagon-like peptide 1 (GLP-1) receptor agonist engineered in our MIMETIBODY platform. It retains many activities of native GLP-1 yet has a significantly enhanced pharmacokinetic profile. Our goal was to develop a long-acting GLP-1 receptor agonist with sustained efficacy.

RESEARCH DESIGN AND METHODS—In vitro and in vivo activity of CNTO736 was evaluated using a variety of rodent cell lines and diabetic animal models.

RESULTS—Acute pharmacodynamic studies in diabetic rodents demonstrate that CNTO736 reduces fasting and postprandial glucose, decreases gastric emptying, and inhibits food intake in a GLP-1 receptor–specific manner. Reduction of food intake following CNTO736 dosing is coincident with detection of the molecule in the circumventricular organs of the brain and activation of c-fos in regions protected by the blood-brain barrier. Diabetic rodents dosed chronically with CNTO736 have lower fasting and postprandial glucose and reduced body weight.

CONCLUSIONS—Taken together, our data demonstrate that CNTO736 produces a spectrum of GLP-1 receptor–dependent actions while exhibiting significantly improved pharmacokinetics relative to the native GLP-1 peptide.
Spectral dependence of retinal thermal injury
Authors: Lund David J. , Edsall Peter , Stuck Bruce E.
Published: April 2008

The action spectrum for light-induced damage to the retina results from wavelength dependent transmission of the pre-retinal ocular media, wavelength dependent absorption in retinal chromophores, and chromatic aberration of the eye optics. While various light/tissue interaction mechanisms have been implicated, thermal mechanisms dominate in the visible and near-infrared spectrum for all exposure durations shorter than a few seconds and longer than 1 ns. A number of investigators have measured the transmission of the eye and the spectra of retinal absorbers, and thermal models based on these data predict the broad features of the action spectrum. This paper reports dose-response data for 100 ms duration retinal exposure in rhesus monkey to laser irradiation from a tunable Ti:Sapphire laser and from fixed-wavelength lasers over the wavelength range from 413 to 1319 nm. The wavelength dependence of these data is well predicted by the thermal action spectrum.
Super-short times laser welding of thermoplastic resins using a ring beam optics
Authors: Xu Guojian , Tsuboi Akihiko , Ogawa Takemitsu , Ikeda Takeshi , Kutsuna Muneharu
Published: April 2008

A ring beam optics was developed for a circular seam welding of the automotive parts using a 2 kW fiber laser. The characteristics of the ring beam optics were investigated by a Primes Beam Monitor. As a result, with increase of focal length of collimating lens, the outer diameter of the ring beam was hardly changed, however the inner diameter of the ring beam decreased. Therefore, the width of the ring beam was increased in the experiment. A distance (L12) between first axi-cone lens and second axi-cone lens increases, the outer diameter and inner diameter of the ring beam increases simultaneously. And the width of the ring beam was almost fixed. Moreover, it was confirmed that the intensity distribution of the ring beam becomes uniform by adjusting the coaxial performance of collimating lens, first axi-cone lens, and second axi-cone lens. After the ring beam optics connects to the fiber laser facility, a transparent thermoplastic resin and opaque thermoplastic resin with a circular seam was welded by a Through Transmission Laser Welding (TTLW). The thermoplastic resins with a circular seam were firmly welded in a super-short time.
Idling magnetic white dwarf in the synchronizing polar BY Cam. The Noah-2 project
Authors: Andronov Ivan , Antoniuk Kirill , Breus Vitalii , Chinarova Lidia , Han Wonyong , Jeon Young , Kim Yonggi , Kolesnikov Sergey , Oh Joon , Pavlenko Elena , Shakhovskoy Nikolay
Published: April 2008

A multi-color study of the variability of the magnetic cataclysmic variable BY Cam is presented. The observations were obtained at the Korean 1.8 m and Ukrainian 2.6 m, 1.2 m and 38 cm telescopes in 2003–2005, 56 observational runs cover 189 hours. The variations of the mean brightness in different colors are correlated with a slope dR/dV = 1:29(4), where the number in brackets denotes the error estimates in the last digits. For individual runs, this slope is much smaller ranging from 0.98(3) to 1.24(3), with a mean value of 1.11(1). Near the maximum, the slope becomes smaller for some nights, indicating more “blue” spectral energy distribution, whereas the night-to-night variability has an “infrared” character. For the simultaneous UBVRI photometry, the slopes increase with wavelength from dU/dR = 0:23(1) to dI/dR = 1:18(1). Such wavelength dependence is the opposite of that observed in non-magnetic cataclysmic variables, in agreement with the model of cyclotron emission. The principal component analysis shows two components of variablitity with different spectral energy distributions (with a third at the limit of detection), which possibly correspond to different regions of emission. The highest peak in the scalegram analysis corresponds to the 200 min spin variability, its quarter and to the 30 min and 8 min QPOs. The amplitudes of these components are dependent on wavelength and luminosity state. The light curves were fitted by a statistically optimal trigonometrical polynomial (up to 4th order) to take into account a 4-hump structure. The dependences of these parameters on the phase of the beat period and on mean brightness are discussed. The amplitude of spin variations increases with an increasing wavelength and with decreasing brightness. The linear ephemeris based on 46 mean minima for 2003–2005 is HJD 2453213:010(3) + 0:137123(3)E: The extensive tables of the original observations and of results of analysis are published in an electronic form. The nearby star GSC 4081–1562 was found to be an eclipsing red variable.
Comparative Study of the Effect of Different Weed Management Strategies on Disease Severity and Marketable Yield of Paprika (Capsicum Annuum L.) in the Smallholder Farming Sector of Zimbabwe
Authors: Handiseni Maxwell , Sibiya Julia , Ogunlela Vincent , Koomen Irene
Published: April 2008

Comparative Study of the Effect of Different Weed Management Strategies on Disease Severity and Marketable Yield of Paprika (Capsicum AnnuumL.) in the Smallholder Farming Sector of Zimbabwe

On-farm trials were conducted in the Chinyika Resettlement Area of Zimbabwe under dryland conditions to investigate the effects of different weed management methods on disease incidence, severity and paprika (Capsicum annuum) pod yield. The weed control treatments included hand weeding at 2 and 6 weeks after transplanting (WAT); ridge re-moulding at 3,6 and 9 WAT; application 4l/ha Lasso (alachlor) immediately after transplanting, and Ronstar (oxidiazinon) at 2l/ha tank mixed with Lasso at 2l/ha one day before transplanting. The herbicide-water solution was applied at the rate of 200l/ha using a knapsack sprayer. Major diseases identified were bacterial leaf spot (Xanthomonas campestrispv.vesicatoria), cercospora leaf spot (Cercospora unamunoi), grey leaf spot (Stemphylium solani) and powdery mildew (Leveillula taurica) in both seasons. For the 2000/2001 season hand weeding at 2 and 6 WAT and ridge re-moulding at 3, 6 and 9 WAT had the greatest reduction effect on the area under disease progress curve (AUDPC) and the highest marketable fruit yield. In the 2001/2002 season, both herbicide treatments had the same effect as hand weeding and ridge re-moulding on AUDPC and marketable fruit yield. The least weed density was obtained by ridge re-moulding at 3, 6, and 9 WAT in the 2000/2001 season. Weed density was statistically the same across all treatments except the check treatment in 2001/2002 season. Hand weeding operations were significantly (p < 0.05) effective and consequently gave the highest added profits mainly because of their effect on major weeds such asDatura stramonium.
Imaging of Ca2+ Transients in Endothelial Cells of Single Perfused Capillaries: Correlation of Peak [Ca2+]i with Sites of Macromolecule Leakage
Authors: PAGAKIS S. N. , CURRY F. E.
Published: April 2008

Objective: To investigate the mechanisms responsible for variation in the macromolecular leakage (formation of localized leaky sites) in venular microvessels with increased permeability, we examined the hypothesis that cytoplasmic calcium concentration [Ca2+]i, does not increase uniformly within microvessel endothelial cells.

Methods: We loaded the endothelial cells forming the walls of venular microvessels in frog mesentery with fura‐2, and imaged [Ca2+]i using a cooled CCD camera.

Results: Control [Ca2+]i was close to 60 nM in all regions. Control permeability was uniformly low in all microvessels. Exposure to ionomycin (5 mM) increased [Ca2+]i in a biphasic manner, but not uniformly. There was variation in both time to peak (bimodal distribution) and peak [Ca2+]i (274 ± 13 nM; mean variation above or below the peak value was 110 nM). Raising extracellular calcium from 1.1 to 5 mM increased the mean variation of [Ca2+]i about peak values. Extravascular leakage of fluorescently labeled albumin or low‐density lipoproteins was most prominent at sites where increases in [Ca2+]i were largest.

Conclusions: These data indicate that variation in [Ca2+]i within individual endothelial cells or groups of cells could account, at least in part, for the distribution of localized leakage sites for macromolecules in venular microvessels in the high‐permeability state.
Microcirculatory Homeostasis 1930–1990: Insight into Microcirculatory Readjustments Provided by Studies on the Peripheral Circulatory Insufficiency of the Shock Syndrome
Authors: ZWEIFACH BENJAMIN W.
Published: April 2008

The present overview is intended to serve several purposes. It highlights efforts over the years to resolve the difficult key issues raised by August Krogh in the 1930s and by the urgent need created in the 1940s and 1950s by World War II to come to grips with the basic problems underlying the collapse of tissue perfusion in the syndrome of circulatory shock. The complex operational issues raised by circulatory insufficiency at the systemic, as well as the local tissue level, during the shock syndrome, are used as a framework to keep in perspective the impact of advances in methodology, ultrastructure, and in recent years in molecular biology on microvascular research. In view of the current continuing need to integrate the newly emerging body of in vitro information into specific aspects of the operation of the peripheral vascular tree, emphasis is placed on the advances in dealing with data provided by in vivo microscopy of selected tissues.

This overall review has made it clear that a top priority remains the need to separate the effects of systemic and locally derived readjustments, and to identify the basis for the substantial differences in cellular behavior exhibited by the vascular and perivascular components of the various organs and tissues of the body that can serve as predisposing factors in regional pathophysiology.
Flow‐Dependent Dilation and Myogenic Constriction Interact to Establish the Resistance of Skeletal Muscle Arterioles
Authors: SUN DONG , HUANG AN , KOLLER AKOS , Kaley Gabor
Published: April 2008

Objective: To test the hypothesis that the diameter of skeletal muscle arterioles is determined by the interaction of responses elicited by intravascular pressure and flow.

Methods: Experiments were conducted on isolated, cannulated, first‐order arterioles of cremaster muscle of male Wistar rats. The diameter of arterioles was followed by videomicroscopy. Perfusion pressures and flows were controlled.

Results: In the absence of perfusate flow, increases in perfusion pressure (from 0 to 120 mm Hg), after initial dilation, elicited endothelium independent constrictions of arterioles. At 60 mm Hg of perfusion pressure, the active diameter of vessels was 84.9 ± 1.9 μm. The passive diameter of arterioles (Ca2+‐free solution) was 150.6 ± 2.4 μm. Increases in perfusate flow resulted in a significant upward shift in the pressure—diameter curves; in the presence of perfusate flows of 20, 40, and 60 μL/min, the constriction of the vessels at a pressure of 60 mm Hg was attenuated by 25.1 ± 3.9%, 35.2 ± 3.0%, and 46.8 ± 4.4%, respectively. In contrast, the corresponding diameter of arterioles at perfusate flows of 10 to 60 μL/min was significantly reduced when perfusion pressure was increased from 60 to 80 and 100 mm Hg (at a flow of 60 μL/min) by 12.0 ± 4.3% and 37.1 ± 2.8%, respectively. Hence, both flow‐ and shear stress—diameter curves were significantly shifted downward when perfusion pressure increased from 60 to 100 mm Hg.

Conclusion: These results demonstrate that an interplay between pressure and flow‐sensitive mechanisms is an important determinant of the arteriolar resistance in skeletal muscle.
A Shear Stress Component to the Modulation of Capillary Hydraulic Conductivity (Lp)
Authors: Williams Donna A.
Published: April 2008

Objective: Two major factors that determine transcapillary exchange are Starling forces and hydraulic conductivity (Lp) of capillary walls. Although chemical stimuli alter Lp, the influence of mechanical stimuli has been neglected. Therefore, we tested the hypothesis that the Lp of intact capillaries would increase with the magnitude of changes in shear stress presented to each capillary.

Methods: Capillaries (n = 26) in the mesentery of pithed frogs (n = 23) were cannulated at 30 cm H2O (average in situ pressure = 9.2) to alter shear stress. For the calculation of shear stress, velocities of both frog red blood cells (RBC) and human RBC in the pipette solution were measured in each capillary before and after cannulation, respectively. Lp was assessed 2 min after cannulation.

Results: Venular capillaries only responded to the changes in shear stress. The magnitude of the changes in shear stress correlated positively with the values for capillary Lp (Kendall's tau = 0.56; p = 0.02).

Conclusions: While Starling forces influence the movement of fluid by acting perpendicular to the long axis of capillaries, shear stress acts in a plane tangential to the capillary walls and appears to alter capillary Lp. In addition to chemical stimuli, the mechanical stimulation of capillaries can alter the barrier itself and consequently alter filtration rate.
A Review of the Microcirculation of Adipose Tissue: Anatomic, Metabolic, and Angiogenic Perspectives
Authors: Crandall David L. , Hausman Gary J. , Kral John G.
Published: April 2008

Adipose tissue microcirculation is unique within the vascular system because of a capacity for this tissue to grow throughout most of adult life. A review of the microcirculation of adipose tissue has included a historical review of the early studies, which served as a foundation for later investigations on this topic, including basic hemodynamic measurements in mammalian adipose tissue. The various methods for measuring blood flow in white and brown adipose tissue are discussed with respect to studies of transport of substrates involved in adipose tissue metabolism. The role of innervation and vascular adrenergic receptors and the effects of diet and exercise on adipose tissue blood flow are also included. An in‐depth analysis of the development of adipose tissue microvasculature indicates that angiogenesis often precedes adipogenesis. The clinical effects of hemodynamic adaptations to adipose tissue expansion are discussed in view of an epidemic increase in the prevalence of obesity and its co‐morbidities. The recent discovery of sites of nuclear regulation of adipocyte differentiation, together with the identification of growth factors in adipose tissue, is an indication of the progress that is being made in the further understanding of molecular and cellular events that affect adipose tissue growth and, ultimately, adipose tissue microcirculation.
E‐Selectin Is Upregulated in Proliferating Endothelial Cells In Vitro
Authors: Bischoff Joyce , Brasel Christopher , Kräling Birgit , Vranovska Katerina
Published: April 2008

Objective: E‐selectin is an endothelial cell‐specific membrane glycoprotein that participates in leukocyte adhesion and has also been suggested to function in angiogenesis. To gain further insights into E‐selectin, we analyzed E‐selectin polypeptide in proliferating versus quiescent bovine capillary endothelial cells and its expression as a function of the cell cycle.

Methods: E‐selectin polypeptide was analyzed by immunoadsorption from 35Scysteine—labeled endothelial cells, by enzyme‐linked immunosorbent assay, and by fluorescence‐activated cell sorting. The distribution of endothelial cells in G0/G1, S, and G2/M phases of the cell cycle was determined using propidium iodide staining of DNA.

Results: E‐selectin was upregulated in subconfluent proliferating bovine capillars endothelial cells compared to confluent quiescent cultures. The upregulation was independent of activation in that E‐selectin was further increased by treatment with tumor necrosis factor α or lipopolysaccharide. In contrast to E‐selectin, P‐selectin and platelet‐endothelial cell adhesion molecule‐1 did not appear to be regulated by the growth state of the endothelial cells. The distribution of E‐selectin‐positive cells in G0G1, S, and G2/M phases of the cell cycle differed from E‐selectin‐negative cells in that more of the E‐selectin‐positive cells were in G2 and M.

Conclusions: Increased E‐selectin expression under noninflammatory conditions is correlated with cellular proliferation and G2/M phases of the cell cycle. The expression of E‐selectin in proliferating endothelial cells in vitro is consistent with the presence of E‐selectin in proliferating endothelial cells in vivo (Kräling et al. [18]).
Polymorphonuclear Leukocytes Released from the Bone Marrow Preferentially Sequester in Lung Microvessels
Authors: Van Eeden Stephan F. , Kitagawa Yuko , Klut Maria E. , Lawrence Elizabeth , Hogg James C.
Published: April 2008

Objective: A hallmark of the systemic response to an inflammatory stimulus is the release of polymorphonuclear leukocytes (PMNs) from the bone marrow. This study was designed to measure the release of PMNs from the bone marrow and to determine their sequestration in the lung after an intravenous injection of either endotoxin (n = 5) or saline (n = 5).

Methods and Results: The thymidine analogue 5′‐bromo‐2‐deoxyuridine (BrdU) was used to pulse label dividing PMNs in the bone marrow of rabbits (n = 13), and immunohistochemistry and morphometry were used to detect the release of BrdU‐labeled PMNs into the circulation and to determine their sequestration in the lung. Endotoxin treatment caused a drop in the circulating PMN counts (3.3 ± 0.08 at baseline to 0.12 ± 0.02 × 109/L at 1 hour after endotoxin), which was followed by a neutrophilia at 8 hours (6.3 ± 1.1 × 109/L, p < 0.01), an increase in circulating band cells (0.12 ± 0.01 at baseline to 2.18 ± 0.4 × 19/L at 8 hours, p < 0.001), and an increase in the percentage of BrdU‐labeled PMNs (0.01% ± 0.004% at baseline to 26.1% ± 3.2% at 8 hours, p < 0.001). Endotoxemia caused an arteriovenous difference in BrdU‐labeled PMNs across the lung (35.9% ± 2.9% versus 26.1% ± 3.1%, mixed venous versus arterial, p < 0.02). Morphometric studies showed that endotoxin caused sequestration of PMNs in the lung (2.2 ± 0.4 versus 1.0 ± 0.2 × 1010, endotoxin versus saline, p < 0.03) with preferential retention of BrdU‐labeled PMNs (0.79 ± 0.21 versus 0.039 ± 0.016 × 1010, endotoxin versus saline, p < 0.05). The percentage of BrdU‐labeled PMNs in the alveolocapillary walls was higher than in circulating blood (64.01% ± 4.3% versus 26.1% ± 3.2%, p < 0.01) in the endotoxin group. In vitro filtration of cells through 5‐mm pore size filters showed that circulating BrdU‐labeled PMNs, 8 hours after endotoxin, were preferentially retained in the filters (p < 0.01).

Conclusions: We conclude that endotoxemia stimulates the bone marrow to release mature and immature PMNs. Compared to PMNs released from the bone marrow during normal turnover, these PMNs are less deformable and preferentially sequester in the lung microvessels.