bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological and biochemical T2 evaluation of cartilage repair tissue based on a hybrid double echo at steady state (DESS‐T2d) approach
Authors: Welsch Goetz H. , Mamisch Tallal C. , Zak Lukas , Mauerer Andreas , Apprich Sebastian , Stelzeneder David , Marlovits Stefan , Trattnig Siegfried 
Published: July 2011

AbstractPurpose:To use a new approach which provides, based on the widely used three‐dimensional double‐echo steady‐state (DESS) sequence, in addition to the morphological information, the generation of biochemical T2 maps in one hybrid sequence.Materials and Methods:In 50 consecutive MRIs at 3.0 Tesla (T) after matrix‐associated autologous chondrocyte transplantation (MACT) of the knee, by the use this new DESS‐T2d approach, the morphological Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) score, as well as biochemical T2d values were assessed. Furthermore, these results were correlated to standard morphological sequences as well as to standard multi‐echo spin‐echo T2 mapping.Results:The MOCART score correlated (Pearson:0.945; P < 0.001) significantly as assessed with standard morphological sequences (68.8 ± 13.2) and the morphological images of the DESS T2d sequence (68.7 ± 12.6). T2 and T2d relaxation times (ms) were comparable in between the control cartilage (T2: 52.5 ± 11.4; T2d: 46.6 ± 10.3) and the repair tissue (T2: 54.4 ± 11.4; T2d: 47.5 ± 13.0) (T2: P = 0.157; T2d: P = 0.589). As expected, T2d values were lower than the standard‐T2 values, however, both functional relaxation times correlated significantly (Pearson:0.429; P < 0.001).Conclusion:The presented hybrid approach provides the possibility to combine morphological and biochemical MRI in one fast 3D sequence, and thus, may attract for the clinical use of biochemical MRI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
First order correction for T2*‐relaxation in determining contrast agent concentration from spoiled gradient echo pulse sequence signal intensity
Authors: De Naeyer Dieter , Debergh Isabelle , De Deene Yves , Ceelen Wim P. , Segers Patrick , Verdonck Pascal 
Published: July 2011

AbstractPurpose:To investigate the accuracy of a method neglecting T2*‐relaxation, for the conversion of spoiled gradient echo pulse sequence signal intensity to contrast agent (CA) concentration, in dynamic contrast enhanced MRI studies. In addition a new closed form conversion expression is proposed that accounts for a first order approximation of T2*‐relaxation.Materials and Methods:The accuracy of both conversion methods is compared theoretically by means of simulations for four pulse sequences from literature. Both methods are tested in vivo against the numerical conversion method for measuring the arterial input function in mice.Results:Simulations show that the T2*‐neglecting method underestimates typical tissue CA concentrations (0 mM to 2 mM) up to 6%, while the errors for arterial concentrations (0 mM to 10 mM) range up to 43%. The results from our first order method are numerically indistinguishable from the simulation input values in tumor tissue, while for arterial concentrations the error is reduced up to a factor 10. In vivo, peak Gd‐DOTA concentration is underestimated up to 14% with the T2*‐neglecting method and up to 0.9% with our first order method.Conclusion:Our conversion method reduces the underestimation of CA concentration severely in a broad physiological concentration range and is easy to perform in any clinical setting. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Compensation of RF field and receiver coil induced inhomogeneity effects in abdominal MR images by a priori knowledge on the human adipose tissue distribution
Authors: Würslin Christian , Springer Fabian , Yang Bin , Schick Fritz 
Published: July 2011

AbstractPurpose:To reliably compensate bias field effects in abdominal areas to accurately quantify visceral adipose tissue using standard T1‐weighted sequences on MR scanners with up to 3 Tesla (T) field strength.Materials and Methods:Compensation is achieved in two steps: The bias field is first estimated by picking and fitting sampling points from the subcutaneous adipose tissue, using active contours and a thin plate fitting spline. Then, additional sampling points from visceral adipose tissue compartments are detected by thresholding and the bias field estimation is refined. It was compared with an established method using a simulated abdominal image and real 3T data.Results:At low bias field amplitudes (40–50%), the simulation study showed a good reduction of the mean coefficients of variance (CV) for both approaches (>80%). At higher amplitudes, the CV reduction was significantly higher for our approach (83.6%), compared with LEMS (54.3%). In the real data study, our approach showed reliable reduction of the inhomogeneities, while the LEMS algorithm sometimes even amplified the inhomogeneities.Conclusion:The proposed method enables accurate and reliable segmentation of abdominal adipose tissue using simple thresholding techniques, even in severely corrupted images slices, obtained when using high field strengths and/or phased‐array coils. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Resolving arterial phase and temporal enhancement characteristics in DCE MRM at high spatial resolution with TWIST acquisition
Authors: Herrmann Karl‐Heinz , Baltzer Pascal A. , Dietzel Matthias , Krumbein Ines , Geppert Christian , Kaiser Werner A. , Reichenbach Jürgen R. 
Published: July 2011

AbstractPurpose:To investigate the potential of a view‐sharing 3D fast gradient‐echo sequence using pseudo random trajectories (TWIST) to achieve very short acquisition times with high in‐plane resolution and good volume coverage and its application to dynamic contrast‐enhanced (DCE) breast magnetic resonance imaging (MRI).Materials and Methods:Two versions of a 3D fast gradient echo TWIST sequence were implemented and applied to patients: First, an ultrafast TWIST acquisition (TA = 5.7 sec) in combination with a routine DCE MRM protocol to allow the extraction of arterial input functions and to resolve the first pass of the contrast agent. Second, a dynamic full coverage TWIST DCE acquisition (TA = 10.6 sec) in a repeat examination, replacing the routine DCE MRM sequence.Results:The ultrafast acquisition enabled extraction of arterial input functions and the monitoring of the contrast agent's first pass through vessels and lesions. The dynamic full coverage TWIST acquisition captured the initial dynamic slope of the signal time curve of lesions accurately, in contrast to the routine protocol.Conclusion:TWIST acquisitions proved very robust and offer high flexibility in protocol timing. The ultrafast protocol achieved 5.7 seconds time resolution with good image quality and can be combined with any established routine protocol. The full dynamics TWIST DCE protocol offers improved time resolution of the CE dynamic time‐course and closely matches the image quality of the routine protocol. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Chemical shift sodium imaging in a mouse model of thromboembolic stroke at 9.4 T
Authors: Heiler Patrick M. , Langhauser Friederike L. , Wetterling Friedrich , Ansar Saema , Grudzenski Saskia , Konstandin Simon , Fatar Marc , Meairs Stephen , Schad Lothar R. 
Published: July 2011

AbstractPurpose:To estimate changes in the 23Na density and in the 23Na relaxation time T2* in the anatomically small murine brain after stroke.Materials and Methods:Three‐dimensional acquisition weighted chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm3 was used for sodium imaging and relaxation parameter mapping. In vivo measurements of the mouse brain (n = 4) were performed 24 hours after stroke, induced by microinjection of purified murine thrombin into the right middle cerebral artery. The measurement time was 14 minutes in one mouse and 65 minutes in the other three. An exponential fit estimation of the free induction decay was calculated for each voxel enabling the reconstruction of locally resolved relaxation parameter maps.Results:The infarcted areas showed an increase in sodium density between 160% and 250%, while the T2* relaxation time increased by 5%–72% compared to unaffected contralateral brain tissue.Conclusion:23Na chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm3 enabled sodium imaging of the anatomical small mouse brain and the acquired data allowed calculating relaxation parameter maps and hence a more exact evaluation of sodium signal changes after stroke. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Investigation of the afterglow time regime in pulsed radiofrequency glow discharge time‐of‐flight mass spectrometry
Authors: González Gago C. , Bordel N. , Pereiro R. , Sanz‐Medel A. 
Published: July 2011

AbstractThe pulsed power operation mode of a radiofrequency (rf) glow discharge time‐of‐flight mass spectrometer was investigated, for several ions, in terms of intensity profiles along each pulse period. Particular attention was paid to the plateau and transient afterglow regions. An rf pulse period of 4 ms and a duty cycle of 50% was selected to evaluate the influence of discharge parameters in the afterglow delay and shape of Ar+, Ar2+ and several analytes (Br, Cl, Cu) contained in polymeric layers. Pulse shapes of Ar+ and Ar2+ ions vary with pressure and power. At low pressures the highest intensity is observed in the plateau while at higher pressures (>600 Pa) the afterpeak is the dominant region. Although the influence of the applied power is less noticeable, a widening of the afterglow time regime occurs for Ar+ when increasing the power. Maximum intensity of the argon signal is measured in the afterglow at 30 W, while the area of such afterpeak increases with power. The maximum intensity of Ar2+ is obtained at the highest power employed (60 W) and the ratio maximum intensity/afterglow area remains approximately constant with power. Analytes with ionization potentials below (Cu) or just above (Br) the argon metastable energy show maxima intensities after argon ions decay, indicating they could be ionized by collisions with metastable Ar atoms. Chlorine signals are observed in the afterglow despite their ionization potential is well above the energy of argon metastable levels. Moreover, they follow a similar pattern to that observed for Ar2+, indicating that charge‐transfer process with Ar2+ could play a significant role. Copyright © 2011 John Wiley & Sons, Ltd.
Proteomic characterisation of hydrothermal redox damage
Authors: Grosvenor Anita J , Morton James D , Dyer Jolon M 
Published: July 2011

AbstractBACKGROUND: Peptide and protein damage contributes to the loss of quality and value in protein‐based food and textile products as well as to the degeneration of biological tissues such as hair and skin. The effects of elevated temperature on such substrates at the molecular level are, however, relatively unknown. This paper examines the response of peptides and proteins to hydrothermal damage using mass spectrometry and reports the location of molecular markers of hydrothermal damage within wool proteins.RESULTS: The hydrothermal exposure of model peptides containing the oxidatively sensitive residues tryptophan and tyrosine revealed the formation of a number of products such as hydroxytryptophan and dihydrophenylalanine. A variety of degradation products were also observed in intermediate filament proteins, including products arising from deamidation and from oxidation of histidine, tyrosine and tryptophan residues.CONCLUSION: The products observed to form during hydrothermal exposure indicated the involvement of reactive oxygen species. Molecular markers were identified within a proteinaceous system to allow the evaluation of damage type or severity. These findings have important implications for the thermal processing of foods and textiles. Copyright © 2011 Society of Chemical Industry
Potential and constraints in the development of animal industries in China
Authors: Liu Shimin , Cai Yunbo , Zhu Haiyan , Tan Zhiliang 
Published: July 2011

AbstractOver the past three decades, the growth in terrestrial livestock and aquatic animal production in China has been much faster than the annual increase of 1.92% in total grain production. It was estimated that farming animals, including aquatic animals, would require a total of 860 million tons of feed in 2008, comprising almost equal portions of concentrates, pastures, and crop straw. Grain production amounted to 528 million tons in 2008, about half of which were available for use in animal feed after satisfying demand for human consumption. This situation will not change in the near future. Pastures from the natural grasslands supply about 290 million tons of dry matter, and are also unlikely to increase. In contrast, only one third of the 890 million tons of crop straw was used as animal feeds. We conclude that the availability of grain and pasture is the major constraint to further expansion of animal production, as well as crop straw which is not fully utilised. China needs to strategically structure the industries of its herbivores and the other domestic species, and to develop sustainable faming systems based on its available feed sources. Copyright © 2011 Society of Chemical Industry
Thin‐layer chromatographic plates with monolithic layer of silica: Production, physical–chemical characteristics, separation capabilities
Authors: Frolova Anastasiya M. , Konovalova Olga Y. , Loginova Lidia P. , Bulgakova Alena V. , Boichenko Alexander P. 
Published: July 2011

AbstractThe technique for production of thin‐layer chromatographic plates with fixed monolithic layer of sorbent was developed on the basis of investigation of factors affecting sorption capacity, sorption kinetics and mechanical stability of monoliths. The optimal reaction mixture for sol–gel synthesis of monoliths consisted of tetraethoxysilane, buffer solution with pH 7.4, N,N‐dimethylformamide, ethanol, polyethyleneglycol with molecular weight 1000 and cetylpyridinium chloride in molar ratio 1.0:4.6:1.4:7.6:0.26:8×10−3. On the basis of analysis of sorption kinetics of malachite green on the monoliths it was concluded that mechanism of sorption includes chemisorption. The optimized conditions for fixing the monolithic layer on the carrier and its drying allow obtaining undisturbed monolithic layer, which was used for test mixtures separation. The increase of monolithic layer thickness in comparison with ultrathin‐layer chromatographic plates allows detecting visually at reasonable concentrations and loaded sample volumes the spots of food and synthetic dyes.
Trends in intensive management of Alaska's grizzly bears, 1980–2010
Authors: Miller Sterling D. , Schoen John W. , Faro Jim , Klein David R. 
Published: July 2011

AbstractHunting regulations for grizzly bears (Ursus arctos) in much of Alaska since 1980 increasingly were designed to reduce bear abundance in the expectation such regulations would lead to increased harvests by hunters of moose (Alces alces) and caribou (Rangifer tarandus). Regulations were liberalized during 1980–2010 primarily in the area we termed the Liberal Grizzly Bear Hunting Area (hereafter Liberal Hunt Area) which encompassed 76.2% of Alaska. By 2010, these changes resulted in longer hunting seasons (100% of Liberal Hunt Area had seasons > 100 days, 99.7% > 200 days, and 67.8% > 300 days), more liberal bag limits (99.1% of the Liberal Hunt Area with a bag limit ≥ 1/yr and 10.1% with a bag limit ≥ 2/yr), and widespread waiver of resident tag fees (waived in 95.7% of the Liberal Hunt Area). During 1995–2010, there were 124 changes that made grizzly bear hunting regulations more liberal and two making them more conservative. The 4‐year mean for grizzly bear kills by hunters increased 213% between 1976–1980 (387 grizzly bears) and 2005–2008 (823 grizzly bears). Since 2000, long‐term research studies on grizzly populations in the Liberal Hunt Area have been terminated without replacement. Management of large predators by the State of Alaska is constrained by a 1994 state statute mandating “intensive management” in areas classified as important for human consumptive use of ungulates. Current grizzly bear management in the Liberal Hunt Area is inconsistent with the recommendations of the National Research Council's 1997 report on predator management in Alaska. Current attitudes, policies and absence of science‐based management of grizzly bears in Alaska are increasingly similar to those that resulted in the near extirpation of grizzly bears south of Canada in the 19th and 20th centuries. If current trends continue, they increase risks to portions of the largest and most intact population of grizzly bears in North America. © 2011 The Wildlife Society.
Cougar survival and source‐sink structure on Greater Yellowstone's Northern Range
Authors: Ruth Toni K. , Haroldson Mark A. , Murphy Kerry M. , Buotte Polly C. , Hornocker Maurice G. , Quigley Howard B. 
Published: July 2011

AbstractWe studied survival and causes of mortality of radiocollared cougars (Puma concolor) on the Greater Yellowstone Northern Range (GYNR) prior to (1987–1994) and after wolf (Canis lupus) reintroduction (1998–2005) and evaluated temporal, spatial, and environmental factors that explain variation in adult, subadult, and kitten survival. Using Program MARK and multimodel inference, we modeled cougar survival based on demographic status, season, and landscape attributes. Our best models for adult and independent subadults indicated that females survived better than males and survival increased with age until cougars reached older ages. Lower elevations and increasing density of roads, particularly in areas open to cougar hunting north of Yellowstone National Park (YNP), increased mortality risks for cougars on the GYNR. Indices of ungulate biomass, cougar and wolf population size, winter severity, rainfall, and individual characteristics such as the presence of dependent young, age class, and use of Park or Wilderness were not important predictors of survival. Kitten survival increased with age, was lower during winter, increased with increasing minimum estimates of elk calf biomass, and increased with increasing density of adult male cougars. Using our best model, we mapped adult cougar survival on the GYNR landscape. Results of receiver operating characteristic (ROC) analysis indicated a good model fit for both female (area under the curve [AUC] = 0.81, 95%CI = 0.70–0.92, n = 35 locations) and male cougars (AUC = 0.84, 95%CI = 0.74–0.94, n = 49 locations) relative to hunter harvest locations in our study area. Using minimum estimates of survival necessary to sustain the study population, we developed a source‐sink surface and we identify several measures that resource management agencies can take to enhance cougar population management based on a source‐sink strategy. © 2011 The Wildlife Society.
High‐precision mass spectrometric analysis using stable isotopes in studies of children
Authors: Schierbeek Henk , van den Akker Chris H.P. , Fay Laurent B. , van Goudoever Johannes B. 
Published: July 2011

AbstractThe use of stable isotopes combined with mass spectrometry (MS) provides insight into metabolic processes within the body. Herein, an overview on the relevance of stable isotope methodology in pediatric research is presented. Applications for the use of stable isotopes with MS cover carbohydrate, fat, and amino acid metabolism as well as body composition, energy expenditure, and the synthesis of specific peptides and proteins, such as glutathione and albumin. The main focus of these studies is on the interactions between nutrients and the endogenous metabolism within the body and how these factors affect the health of a growing infant. Considering that the early imprinting of metabolic processes hugely impacts metabolism (and thus functional outcome) later in life, research in this area is important and is advancing rapidly. The major fluxes on a metabolic level are the synthesis and breakdown rates. They can be quantified using kinetic tracer analysis and mathematical modeling. Organic MS and isotope ratio mass spectrometry (IRMS) are the two most mature techniques for the isotopic analysis of compounds. Introduction of the samples is usually done by coupling gas chromatography (GC) to either IRMS or MS because it is the most robust technique for specific isotopic analysis of volatile compounds. In addition, liquid chromatography (LC) is now being used more often as a tool for sample introduction of both volatile and non‐volatile compounds into IRMS or MS for 13C isotopic analyses at natural abundances and for 13C‐labeled enriched compounds. The availability of samples is often limited in pediatric patients. Therefore, sample size restriction is important when developing new methods. Also, the availability of stable isotope‐labeled substrates is necessary for measurements of the kinetics and concentrations in metabolic studies, which can be a limiting factor. During the last decade, the availability of these substrates has increased. Furthermore, improvements in the accuracy, precision, and sensitivity of existing techniques (such as GC/IRMS) and the development of new techniques (such as LC/IRMS) have opened up new avenues for tackling these limitations. © 2011 Wiley Periodicals, Inc. Mass Spec Rev 31:312–330, 2012
Crack patterns in clayey soils: Experiments and modeling
Authors: Trabelsi H. , Jamei M. , Zenzri H. , Olivella S. 
Published: July 2011

SUMMARYThe paper presents an experimental and numerical study to investigate the behavior of desiccated clayey soils. The performed tests permit to evaluate the crack pattern as well as the tensile strength as a function of suction. A new model that relates the porosity evolution to the suction and to the tensile strength was developed and implemented in the finite element program CODE_BRIGHT. The proposed model captured the initiation and propagation of cracks in a thin layer of desiccated clay and predicted crack patterns in terms of the Minkowski densities (i.e. average crack length and crack intensity factor). The effect of the heterogeneity of the tested specimens, modeled by random clusters, was also quantified. Copyright © 2011 John Wiley & Sons, Ltd.