bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of Geomechanics in Naturally Fractured Reservoirs
Authors: Bagheri M. , Settari A. 
Published: February 2008

Summary
Conventional modeling of fractured reservoirs treats fracture-system permeability and porosity as static (or pressure-dependent) data. Recent attempts at coupling geomechanics focused on the permeability but used crude empirical relations and treated the fluid flow as single porosity. This study takes advantage of the joint-mechanics theory to develop general, rigorous coupling between the fluid-flow equation and deformation of fractured media. Both porosity and permeability coupling are considered.
The geomechanical part uses the equivalent-continuum approach, considering both rock- and fracture-deformation properties. Multiple sets of fractures with any dip and strike angle can be defined. The stiffness of fractures varies with the effective stress according to a law typical for joints.
The main novelty of this work is that the geomechanics solution is decomposed into matrix and fracture parts and used to compute their dynamic porosity and permeability separately. This approach rigorously captures the effect of fractured-media deformation on the dual-porosity-flow part of the coupled system and allows the permeability and porosity variations to be based on measurable joint properties. Generally, fracture deformations produce changes of the permeability tensor in both magnitude and orientation, which in turn influences reservoir flow and compaction behavior.
The main issue studied was the variation in the permeability of the fracture system. The examples show that fracture deformation has a significant effect on productivity or injectivity and that anisotropy of the permeability tensor develops from deformation. The results provide an initiative for implementing the case of full-tensor permeability.
Sweep-Improvement Options for the Daqing Oil Field
Authors: Wang Dongmei , Han Peihui , Shao Zhenbo , Hou Weihong , Seright R. S. 
Published: February 2008

SummaryThis paper investigates the potential of various approaches for improving sweep in parts of the Daqing oil field that have been enhanced-oil-recovery (EOR) targets. Our studies indicated that the polymer flood should have provided excellent sweep throughout the vast majority of the patterns under consideration. However, because alkaline/surfactant/polymer (ASP) flooding is being considered to increase recovery efficiency from the Daqing oil field, mobility control and sweep improvement will be especially important and challenging during implementation of any future ASP process.Fractures were present in a number of Daqing wells (both injectors and producers). Because the fractures were narrow and far from the wellbore, severe channeling did not occur. On the contrary, fractures near the wellbore aided reservoir sweep. Nearwellbore fractures increased the injectivity index substantially during the injection of polymer solutions and increased oil-productivity index in the production wells. These observations may be valuable during implementation of future floods where very-low-mobility chemical (i.e., ASP) banks must be injected to maintain mobility control.Several modes of polymer degradation were considered, with mechanical (shear) degradation being of greatest concern. Appropriate use of near-wellbore fractures may mitigate mechanical degradation effectively, as well as improving injectivity.Several new polymers show potential for cost-effective improvements at Daqing. Increased polymer concentration was also considered. A number of other approaches are (or have been) under investigation, including colloidal dispersion gels, foams, ASP foams, steam, microbes, and polymer solutions prepared with reduced salinity.
Malonyl CoenzymeA Decarboxylase Regulates Lipid and Glucose Metabolism in Human Skeletal Muscle
Authors: Bouzakri Karim , Austin Reginald , Rune Anna , Lassman Michael E. , Garcia-Roves Pablo M. , Berger Joel P. , Krook Anna , Chibalin Alexander V. , Zhang Bei B. , Zierath Juleen R. 
Published: February 2008

OBJECTIVE—Malonyl coenzyme A (CoA) decarboxylase (MCD) is a key enzyme responsible for malonyl-CoA turnover and functions in the control of the balance between lipid and glucose metabolism. We utilized RNA interference (siRNA)-based gene silencing to determine the direct role of MCD on metabolic responses in primary human skeletal muscle.
RESEARCH DESIGN AND METHODS—We used siRNA to silence MCD gene expression in cultured human myotubes from healthy volunteers (seven male and seven female) with no known metabolic disorders. Thereafter, we determined lipid and glucose metabolism and signal transduction under basal and insulin-stimulated conditions.
RESULTS—RNA interference–based silencing of MCD expression (75% reduction) increased malonyl-CoA levels twofold and shifted substrate utilization from lipid to glucose oxidation. RNA interference–based depletion of MCD reduced basal palmitate oxidation. In parallel with this reduction, palmitate uptake was decreased under basal (40%) and insulin-stimulated (49%) conditions compared with myotubes transfected with a scrambled sequence. MCD silencing increased basal and insulin-mediated glucose oxidation 1.4- and 2.6-fold, respectively, compared with myotubes transfected with a scrambled sequence. In addition, glucose transport and cell-surface GLUT4 content was increased. In contrast, insulin action on IRS-1 tyrosine phosphorylation, tyrosine-associated phosphatidylinositol (PI) 3-kinase activity, Akt, and glycogen synthase kinase (GSK) phosphorylation was unaltered between myotubes transfected with siRNA against MCD versus a scrambled sequence.
CONCLUSIONS—These results provide evidence that MCD silencing suppresses lipid uptake and enhances glucose uptake in primary human myotubes. In conclusion, MCD expression plays a key reciprocal role in the balance between lipid and glucose metabolism.
Interaction of Oral Antidiabetic Drugs With Hepatic Uptake Transporters
Authors: Bachmakov Iouri , Glaeser Hartmut , Fromm Martin F. , König Jörg 
Published: February 2008

OBJECTIVE—The uptake of drugs into hepatocytes is a key determinant for hepatic metabolism, intrahepatic action, their subsequent systemic plasma concentrations, and extrahepatic actions. In vitro and in vivo studies indicate that many drugs used for treatment of cardiovascular diseases (e.g., oral antidiabetic drugs, statins) are taken up into hepatocytes by distinct organic anion transporters (organic anion transporting polypeptides [OATPs]; gene symbol SLCO/SLC21) or organic cation transporters (OCTs; gene symbol SLC22). Because most patients with type 2 diabetes receive more than one drug and inhibition of drug transporters has been recognized as a new mechanism underlying drug-drug interactions, we tested the hypothesis of whether oral antidiabetic drugs can inhibit the transport mediated by hepatic uptake transporters.RESEARCH DESIGN AND METHODS—Using stably transfected cell systems recombinantly expressing the uptake transporters OATP1B1, OATP1B3, OATP2B1, or OCT1, we analyzed whether the antidiabetic drugs repaglinide, rosiglitazone, or metformin influence the transport of substrates and drugs (for OATPs, sulfobromophthalein [BSP] and pravastatin; for OCT1, 1-methyl-4-phenylpyridinium [MPP+] and metformin).RESULTS—Metformin did not inhibit the uptake of OATP and OCT1 substrates. However, OATP-mediated BSP and pravastatin uptake and OCT1-mediated MPP+ and metformin uptake were significantly inhibited by repaglinide (half-maximal inhibitory concentration [IC50] 1.6–5.6 μmol/l) and rosiglitazone (IC50 5.2–30.4 μmol/l).CONCLUSIONS—These in vitro results demonstrate that alterations of uptake transporter function by oral antidiabetic drugs have to be considered as potential mechanisms underlying drug-drug interactions.
Validation and Reliability of Visual Assessment with a Shade Guide for Tooth-Color Classification
Authors: Meireles S. S. , Demarco F. F. , Santos I. S. , Dumith S. C. , Bona A. Della 
Published: February 2008

Clinical Relevance
The results of this study showed that the visual assessment of tooth color using the Vitapan Classical shade guide is a valid method for distinguishing between light and dark tooth colors.
Effect of Two In-office Whitening Agents on the Enamel Surface In Vivo: A Morphological and Non-contact Profilometric Study
Authors: Cadenaro M. , Breschi L. , Nucci C. , Antoniolli F. , Visintini E. , Prati C. , Matis B. A. , Di Lenarda R. 
Published: February 2008

Clinical Relevance
This in vivo study supports the hypothesis that the use of in-office bleaching agents is a safe and reliable procedure, inducing no structural damage to the enamel surface, even after prolonged and repeated applications.
Are low‐productive plant communities responsive to nutrient addition? Evidence from sand pioneer grassland
Authors: Storm Christian , Suss Karin 
Published: February 2008

AbstractQuestion:What is the effect of nutrient addition on primary production, phytodiversity and succession of a very unproductive plant community (ca. 100 g.m‐2.a‐1)?Location:A nutrient‐poor, calcareous inland sand ecosystem in the northern upper Rhine valley, Germany.Methods:Within a five‐fold replicated randomized block design, 10‐m2plots were given six single or combined applications of nitrogen, phosphorus, potassium and other essential nutrients for four years. An organic carbon treatment was included as a measure to immobilize soil nitrogen. Data were analysed by mixed linear models.Results:Productivity of above‐ground vascular plant species doubled after nitrogen addition. Additional nutrient elements did not increase productivity further. The cover of ten species and the height of 15 (out of 19 examined) species were significantly enhanced by nutrient addition.Centaurea stoebeis nitrogen‐limited and exhibits a decisive impact on total above‐ground vascular species productivity. Nutrients did not affect phytodiversity. Low‐dosage nitrogen addition (25 kg .ha‐1a‐1) and organic carbon treatment had no significant impact. However, long‐term effects cannot be excluded.Conclusions:The productivity of the examined plant community is responsive to nutrient addition. Although the response is actually more pronounced than in plant communities with higher initial productivity, productivity remained at a low level. Nutrient limitation (mostly phosphorus + nitrogen co‐limitation) of many individual species across all life forms is shown. Total above‐ground vascular plant productivity is nitrogen‐limited. No species were suppressed completely, nor has there yet been an encroachment of new species. However, high‐dosage nitrogen addition resulted in accelerated succession.
Long-term outcome following radical temporal bone resection for lateral skull base malignancies: a neurosurgical perspective
Authors: Kawahara Nobutaka , Sasaki Tomio , Asakage Takahiro , Nakao Kazunari , Sugasawa Masashi , Asato Hirotaka , Koshima Isao , Saito Nobuhito 
Published: February 2008

Object
Primary temporal bone malignancy is a rare form of tumor for which the therapeutic strategy remains controversial. In this study, the authors reviewed their experience with radical temporal bone resection (TBR) of such lesions and analyzed the long-term results to provide treatment recommendations.

Methods
Between 1994 and 2006, 17 patients (10 men and 7 women) underwent total or subtotal TBR for primary temporal bone malignancies. Tumors were graded according to the University of Pittsburgh system. The effects of surgical margins and tumor extensions on patient survival were analyzed using the Kaplan–Meier method.

Results
All tumors, except 1, were graded T4 (most advanced). Subtotal TBR was performed in 14 patients, and total TBR was performed in 3. The surgical margin was tumor negative in 10 patients and tumor positive in 7. For large tumors extending into the infratemporal fossa or encroaching on the jugular foramen, orbitozygomatic (3 patients) and posterior transjugular (4 patients) approaches were combined with the standard approach, and en bloc resection with a negative margin was achieved in all cases but 1. The follow-up time ranged from 0.3–11.6 years (mean 3.3 years). The 5-year recurrence-free and disease-specific survival rates were 67.5 and 60.1%, respectively. When a negative surgical margin was achieved, the survival rates improved to 100 and 89%, respectively.

Conclusions
The neurosurgical skull base technique could improve the probability of en bloc resection with a tumor-free margin for extensive temporal bone malignancies, which would cure a subset of patients. The active participation of neurosurgeons would improve patient care in this field.
Prediction of prognosis in children with medulloblastoma by using immunohistochemical analysis and tissue microarray
Authors: Shim Kyu-Won , Joo Sun-Young , Kim Se-Hoon , Choi Joong-Uhn , Kim Dong-Seok 
Published: February 2008

Object
Medulloblastoma is the most common malignant neuroepithelial tumor found in children. Several reports have described efforts to identify the prognostic significance of various patterns of pathological and immunohistochemical features in medulloblastoma, but the published data appear to be controversial. The authors therefore attempted to demonstrate these prognostic factors convincingly in a retrospective study performed in patients with medulloblastoma.

Methods
The data used were obtained in 58 patients with medulloblastoma who were > 3 years of age and in whom > 1 year of follow-up was available after the maximal resection, craniospinal irradiation, and chemotherapy treatments. These assessments were performed to compare the immunohistochemical features to cellular differentiation, the proliferation index (PI), the apoptotic index (AI), and oncogenesis revealed by TrkC and c-erbB-3. In addition, the authors tried to determine the prognostic utility of these results in this tumor category.

Results
There was no statistically significant correlation between the prognosis and the degree of cell differentiation, but a positive correlation was noted between the PI and the AI in a tumor mass. The number of cases with a PI > 10% was significantly greater in the group of tumors in patients with recurrent medulloblastoma. A close association between the PI as a continuous variable and the progression-free and overall survival was also found. Most importantly, the PI is the only significant prognostic factor for the overall survival of patients with medulloblastoma.

Conclusions
Therefore, the authors suggest that the PI is directly linked to the prognostic factor for medulloblastoma and that immunohistochemical staining is a potentially powerful tool for predicting the prognosis of patients with medulloblastoma.
Surgical strategies and seizure control in pediatric patients with dysembryoplastic neuroepithelial tumors: a single-institution experience
Authors: Minkin Krasimir , Klein Olivier , Mancini Josette , Lena Gabriel 
Published: February 2008

Object
Dysembryoplastic neuroepithelial tumors (DNTs) are commonly associated with medically resistant epilepsy that usually starts in childhood. Presurgical workup and surgical strategies remain controversial. The authors present a study of long-term seizure outcome after noninvasive presurgical investigations and different surgical strategies were used in a series of pediatric patients.

Methods
Twenty-four children who underwent operations at a single center between 1986 and 2006 were eligible for this retrospective study. The authors reviewed medical records including sex, age at seizure onset, age at surgery, seizure type and pharmacoresistance, lesion location, extent and complications of resection, histopathological findings, prescription of seizure and antiepileptic drugs, outcome, and tumor recurrence.

Results
At the last follow-up examination (range 1–16 years after initial treatment, mean 6.7 years) 20 children (83.3%) were seizure free. The authors did not find the rundown phenomenon in any of the patients. Complete antiepileptic drug withdrawal was achieved in 12 children (50%). In 4 of 15 children with temporal DNTs, the lesionectomy alone failed to control seizures. These results could be explained by the wider epileptogenic zone. The only significant predictor for favorable seizure outcome was an absence of preoperative generalized seizures.

Conclusions
In children with extratemporal DNTs the results suggest that complete lesionectomy alone without invasive presurgical investigations are effective for long-term seizure control. For children with temporal DNTs not invading the amygdalohippocampal complex, extensive presurgical evaluations seem indicated. The absence of preoperative generalized seizures was associated with a better seizure outcome.
Management of complicated shunt infections: a clinical report
Authors: James Hector E. , Bradley John S. 
Published: February 2008

Object
The authors present their experience with a protocol for the treatment of patients with complicated shunt infections.

Methods
Complicated shunt infections are defined for the purpose of this protocol as multiple compartment hydrocephalus, multiple organism shunt infection, severe peritonitis, or infections in other sites of the body. The initial treatment protocol for these patients was 3 weeks of intravenous antibiotic therapy and 2 weeks of twice daily intraventricular/intrashunt antibiotic therapy. Cerebrospinal fluid (CSF) cultures were monitored during therapy and obtained again 48 hours after completion. The shunt was completely replaced. Additionally, follow-up cultures were obtained in all patients 3–6 months after therapy was completed.

Results
A cure of the infection was achieved in all patients as defined by negative cultures obtained at completion of antibiotic therapy and in follow-up studies. The follow-up period was 2–11 years (mean 4.4 ± 2.5 years). The treatment protocol was modified in the patients treated after 1991, and 18 patients were treated with this modified treatment regime. In these patients, intraventricular antibiotics were administered only once daily for 14 days, and the CSF was cultured 24 hours after antibiotic therapy had been stopped instead of after 48 hours. The results were similar to those obtained with the initial protocol.

Conclusions
Based on their prospective nonrandomized series, the authors believe that patients with complicated shunt infections can be successfully treated with 2 weeks of intraventricular antibiotic therapy administered once daily, concurrent with 3 weeks of intravenous antibiotic therapy. This protocol reduces length of treatment and hospital stay, and avoids recurrence of infection.
Accuracy of pedicle screw insertion in the cervical spine for internal fixation using frameless stereotactic guidance
Authors: Rath Stefan A. , Moszko Slawomir , Schäffner Petra M. , Cantone Giuseppe , Braun Veit , Richter Hans-Peter , Antoniadis Gregor 
Published: February 2008

Object
Although transpedicular fixation is a biomechanically superior technique, it is not routinely used in the cervical spine. The risk of neurovascular injury in this region is considered high because the diameter of cervical pedicles is very small and their angle of insertion into the vertebral body varies. This study was conducted to analyze the clinical accuracy of stereotactically guided transpedicular screw insertion into the cervical spine.

Methods
Twenty-seven patients underwent posterior stabilization of the cervical spine for degenerative instability resulting from myelopathy, fracture/dislocation, tumor, rheumatoid arthritis, and pyogenic spondylitis. Fixation included 1–6 motion segments (mean 2.2 segments). Transpedicular screws (3.5-mm diameter) were placed using 1 of 2 computer-assisted guidance systems and lateral fluoroscopic control. The intraoperative mean deviation of frameless stereotaxy was < 1.9 mm for all procedures.

Results
No neurovascular complications resulted from screw insertion. Postoperative computed tomography (CT) scans revealed satisfactory positioning in 104 (90%) of 116 cervical pedicles and in all 12 thoracic pedicles. A noncritical lateral or inferior cortical breach was seen with 7 screws (6%). Critical malplacement (4%) was always lateral: 5 screws encroached into the vertebral artery foramen by 40–60% of its diameter; Doppler sonographic controls revealed no vascular compromise. Screw malplacement was mostly due to a small pedicle diameter that required a steep trajectory angle, which could not be achieved because of anatomical limitation in the exposure of the surgical field.

Conclusions
Despite the use of frameless stereotaxy, there remains some risk of critical transpedicular screw malpositioning in the subaxial cervical spine. Results may be improved by the use of intraoperative CT scanning and navigated percutaneous screw insertion, which allow optimization of the transpedicular trajectory.
Controlled Integration of Nanocrystals in Inverted Hexagonal Nano‐Pits at the Surface of Light‐Emitting Heterostructures (Adv. Mater. 5/2008)
Authors: de Sousa Pereira S. M. , Martins M. A. , Trindade T. , Watson I. M. , Zhu D. , Humphreys C. J. 
Published: February 2008

AbstractHexagonal inverted nanopyramids on gallium‐nitride‐based multiple quantum wells are exploited to confine gold nanocrystals (NCs) at the surface of such light‐emitting heterostructures. The number of NCs incorporated in each pit can be controlled by nanoengineering either the NCs' size or the pit size. Capillarity effects can be used to drive the formation of well‐defined assemblies of Au NCs within each pit, as reported by Sérgio Pereira and co‐workers on p. 1038.
Thermodynamic properties of THF + CO2 hydrates in relation with refrigeration applications
Authors: Martínez M. C. , Dalmazzone D. , Fürst W. , Delahaye A. , Fournaison L. 
Published: February 2008

AbstractClathrate hydrate slurries are promising systems in the field of cold distribution. In this work, the Lw‐H‐V equilibrium conditions, the dissociation enthalpy, and the CO2 hydration number of a clathrate hydrate formed from THF/CO2/water mixtures were studied, using a DSC method. For equilibrium condition determination, THF concentration was varied from 1.0 to 16.0 wt % and CO2 partial pressure range was 0.2 to 2.0 MPa. For enthalpy measurements, THF concentration was fixed at 19 wt % and CO2 partial pressure investigated from 0.2 to 2.0 MPa. Experimental equilibrium temperatures and enthalpy values were in good agreement with the results of a model combining the van der Waals and Platteeuw approach with the RKS equation of state associated to a MHV2 mixing rule and UNIFAC model. Equilibrium conditions and dissociation enthalpy show that THF + CO2 hydrate slurries are promising mixtures for refrigeration application. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Correlation of mechanical behaviors with crystalline phase and related cavitation in isotactic polypropylene
Authors: Lv Ruihua , Xu Wenfei , Na Bing , Yan Junzhang 
Published: February 2008

AbstractThe β→α phase transformation during annealing of β‐nucleated isotactic polypropylene (iPP) at 160°C for 1 h has been confirmed by differential scanning calorimetry and X‐ray diffraction measurements. The α‐crystals and related crystallinity in the annealed samples result in higher yield stress and volume dilatation, indicated by the true stress–strain and volume strain analysis, respectively. Meanwhile, higher volume dilatation can find its origin in the lower network modulus in the annealed samples. The increasing yield stress and volume strain, related to the crystalline phase (including crystal form and crystallinity), furthermore, should be responsible for the significant deterioration of the fracture toughness in the annealed samples determined by the essential work of fracture tests. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008