bluuebunny/crossref_metadata_2025 huggingface dataset:
A reappraisal of functional reconstruction of extension of the knee following quadriceps resection or loss
Authors: Lo S. J. , Yeo M. , Puhaindran M. , Hsu C. C. , Wei F. C.
Published: July 2012

The current indications for functional restoration of extension of the knee following quadriceps resection or loss require reappraisal. The contribution of pedicled and free functional muscle transfer is likely to be over-emphasised in many studies, with good functional outcomes predominantly reported only in the context of cases with residual quadriceps function. In cases with total quadriceps resection or loss, all forms of reconstruction perform poorly. Furthermore, in smaller resections with loss of two or fewer components of the quadriceps, minimal impairment of function occurs in the absence of functional reconstruction, suggesting that functional restoration may not be warranted. Thus there is a paradox in the current approach to quadriceps reconstruction, in that small resections are likely to be over-treated and large resections remain under-treated.

This review suggests a shift is required in the approach and rationale for reconstructing functional extension of the knee after quadriceps resection or loss. A classification based on current evidence is suggested that emphasises more clearly the indications and rationale for functional transfers.
Comparison of two methods of femoral tunnel preparation in single-bundle anterior cruciate ligament reconstruction: a prospective randomized study
Authors: Zhang Qiang , Zhang Shu , Li Rui , Liu Ya , Cao Xuecheng
Published: July 2012

PURPOSE: To prospectively compare therapeutic effect of femoral tunnel preparation through the tibial tunnel and the anteromedial (AM) portal in single-bundle anterior cruciate ligament (ACL) reconstruction. METHODS: Between June 2008 and October 2010, 76 patients underwent single-bundle ACL reconstruction by autogenous grafting of semitendinosus and gracilis tendon. All cases were randomly divided into two groups according to the method of femoral tunnel preparation: transtibial (TT) group (n=38) and anteromedial (AM) group (n=38). Lysholm knee score and the KT-1000 anterior laxity at 30° of pre-and post-operation were assessed for two groups. RESULTS: Sixty-five patients (TT group, 34; AM group, 31) were followed up for more than 12 months, with a follow-up rate of 86%. The Lysholm knee score and the KT-1000 anterior laxity 12 months after operation were significantly better than before reconstruction. The Lysholm knee score and the KT-1000 anterior laxity were not significantly different between the TT and AM groups after operation. CONCLUSION: Femoral tunnel preparation through tibial tunnel or the anteromedial portal in single-bundle anterior cruciate ligament reconstruction shows same therapeutic effects.
Biosynthesis of Peptide Hormones Derived from Precursor Sequences
Authors: Eggelkraut-Gottanka R. von , Beck-Sickinger A. G.
Published: July 2012

The release of hormones is subject to a complex and finely tuned regulation system. The biosynthesis plays a key role by specifically converting the prohormone precursor into its biological active product(s). A family of mammalian proteases could be identified to be responsible for the endoproteolytic processing. These subtilisin / kexin-like prohormone convertases (PC) recognize their substrates at single or pairs of basic residues with a high substrate specificity. The so far known seven members include PC1 / 3, PC2, furin / PACE, PACE4, PC4, PC5 / 6 and PC7 / SPC7 / LPC / PC8. PC1 / 3 and PC2 are the most important enzymes for the processing of prohormones, whereas furin is the only one that causes lethality in knock-out models. Tissuespecific co-localization of the prohormone and the PC as well as distinct characteristics of both, like the secondary structures, determine the possible conversion processes. Identification of such determinants implies a great potential for the development of novel drug targets. To obtain sufficient amounts for the in vitro characterization of prohormones, chemical and recombinant synthesis methods have been developed. Application of expressed protein ligation lead to the semisynthesis of the first chemically modified analogs of a full-length proneurohormone (pro-neuropeptide Y). Structural analyses mainly on peptides of the prooxytocin / neurophysin system and on prosomatostatin highlighted the importance of flexible turn or loop structures adjacent to the cleavage site for the specific substrate-enzyme active site interaction. Prohormones and their processing show multiple functions. Therapeutic application including PC inhibitors is very promising for the treatment of disorders like cancer.
Positive victimology: An innovation or “more of the same”?
Authors: Ronel Natti , Toren Ya’ara
Published: July 2012

This article discusses the theoretical and practical development of a new
perspective called Positive Victimology. A review of constructing worlds
such as Positive Criminology and Positive Psychology is examined in their
importance and contribution towards founding the preliminary yet innovative
discipline of Positive Victimology. However since this domain is an
enhancement or improvement of already existent terminology there is a need
to investigate the true theoretical and practical need for a new field while
weighing the advantages and shortcomings of producing new territory.
Damage evolution in GLARE fibre-metal laminate under repeated low-velocity impact tests
Authors: Morinière Freddy , Alderliesten René , Tooski Mehdi , Benedictus Rinze
Published: July 2012

An experimental study was performed on the repeated low-velocity impact behaviour of GLARE. Damage evolution in the material constituents was characterised with successive number of impacts. Records were correlated with visual inspection, ultrasound C-scan and chemical etching. The stiffness of the plate varied when cumulating the number of impacts. Damage accumulation was limited thanks to the synthesis of unidirectional composite and metal. The glass/epoxy plies with high elastic tensile strength could withstand several impacts before perforation despite delamination growth in the vicinity of the impacted area. The damage tolerant aluminium layers prevented the penetration of the projectile and avoided the expansion of delamination. This efficient mechanism preserved the structural integrity of GLARE until first aluminium cracking at the non-impacted side. Among the different failure modes, plate deformation absorbed most of the impact energy. The findings will support the development of a generic quasi-static analytical model and numerical methods.
Autophagy in Trypanosomatids
Authors: Brennand Ana , Rico Eva , Michels Paul A. M.
Published: July 2012

Autophagy is a ubiquitous eukaryotic process that also occurs in trypanosomatid parasites, protist organisms belonging to the supergroup Excavata, distinct from the supergroup Opistokontha that includes mammals and fungi. Half of the known yeast and mammalian AuTophaGy (ATG) proteins were detected in trypanosomatids, although with low sequence conservation. Trypanosomatids such as Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp. are responsible for serious tropical diseases in humans. The parasites are transmitted by insects and, consequently, have a complicated life cycle during which they undergo dramatic morphological and metabolic transformations to adapt to the different environments. Autophagy plays a major role during these transformations. Since inhibition of autophagy affects the transformation, survival and/or virulence of the parasites, the ATGs offer promise for development of drugs against tropical diseases. Furthermore, various trypanocidal drugs have been shown to trigger autophagy-like processes in the parasites. It is inferred that autophagy is used by the parasites in an—not always successful—attempt to cope with the stress caused by the toxic compounds.
DNA Damage and Repair in Human Cancer: Molecular Mechanisms and Contribution to Therapy-Related Leukemias
Authors: Casorelli Ida , Bossa Cecilia , Bignami Margherita
Published: July 2012

Most antitumour therapies damage tumour cell DNA either directly or indirectly. Without repair, damage can result in genetic instability and eventually cancer. The strong association between the lack of DNA damage repair, mutations and cancer is dramatically demonstrated by a number of cancer-prone human syndromes, such as xeroderma pigmentosum, ataxia-telangiectasia and Fanconi anemia. Notably, DNA damage responses, and particularly DNA repair, influence the outcome of therapy. Because DNA repair normally excises lethal DNA lesions, it is intuitive that efficient repair will contribute to intrinsic drug resistance. Unexpectedly, a paradoxical relationship between DNA mismatch repair and drug sensitivity has been revealed by model studies in cell lines. This suggests that connections between DNA repair mechanism efficiency and tumour therapy might be more complex. Here, we review the evidence for the contribution of carcinogenic properties of several drugs as well as of alterations in specific mechanisms involved in drug-induced DNA damage response and repair in the pathogenesis of therapy-related cancers.
Thermal Studies of Zn(II), Cd(II) and Hg(II) Complexes of Some N-Alkyl-N-Phenyl-Dithiocarbamates
Authors: Onwudiwe Damian C. , Ajibade Peter A.
Published: July 2012

The thermal decomposition of Zn(II), Cd(II) and Hg(II) complexes of N-ethyl-N-phenyl and N-butyl-N-phenyl dithiocarbamates have been studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The products of the decomposition, at two different temperatures, were further characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results show that while the zinc and cadmium complexes undergo decomposition to form metal sulphides, and further undergo oxidation forming metal oxides as final products, the mercury complexes gave unstable volatiles as the final product.
Preparative Isolation and Purification of Three Sesquiterpenoid Lactones from Eupatorium lindleyanum DC. by High-Speed Counter-Current Chromatography
Authors: Yan Guilong , Ji Lilian , Luo Yuming , Hu Yonghong
Published: July 2012

A high-speed counter-current chromatography (HSCCC) method was established for the preparative separation of three sesquiterpenoid lactones from Eupatorium lindleyanum DC. The two-phase solvent system composed of n-hexane–ethyl acetate–methanol–water (1:4:2:3, v/v/v/v) was selected. From 540 mg of the n-butanol fraction of Eupatorium lindleyanum DC., 10.8 mg of 3β-hydroxy-8β-[4'-hydroxy-tigloyloxy]-costunolide, 17.9 mg of eupalinolide A and 19.3 mg of eupalinolide B were obtained in a one-step HSCCC separation, with purities of 91.8%, 97.9% and 97.1%, respectively, as determined by HPLC. Their structures were further identified by ESI-MS and 1H-NMR.
On-Line Estimation of Laser-Drilled Hole Depth Using a Machine Vision Method
Authors: Ho Chao-Ching , He Jun-Jia , Liao Te-Ying
Published: July 2012

The paper presents a novel method for monitoring and estimating the depth of a laser-drilled hole using machine vision. Through on-line image acquisition and analysis in laser machining processes, we could simultaneously obtain correlations between the machining processes and analyzed images. Based on the machine vision method, the depths of laser-machined holes could be estimated in real time. Therefore, a low cost on-line inspection system is developed to increase productivity. All of the processing work was performed in air under standard atmospheric conditions and gas assist was used. A correlation between the cumulative size of the laser-induced plasma region and the depth of the hole is presented. The result indicates that the estimated depths of the laser-drilled holes were a linear function of the cumulative plasma size, with a high degree of confidence. This research provides a novel machine vision-based method for estimating the depths of laser-drilled holes in real time.
Cerebral Blood and CSF Flow Patterns in Patients Diagnosed for Cerebral Venous Thrombosis - An Observational Study
Authors: ElSankari Souraya , Czosnyka Marek , Lehmann Pierre , Meyer Marc-Etienne , Deramond Hervé , Balédent Olivier
Published: July 2012

Background and Purpose:

Recent studies of the organization of the cerebral venous system in healthy subjects using phase contrast magnetic resonance imaging (PC-MRI) show its structural complexity and inter-individual variations. Our objective was to study the venous blood and CSF flows in cerebral venous thrombosis (CVT).

Materials and Methods:

PC-MRI sequences were added to brain MRI conventional protocol in 19 patients suspected of CVT, among whom 6 patients had CVT diagnosis confirmed by MR venography. Results were compared with 18 healthy age-matched volunteers (HV).

Results:

In patients without CVT (NoCVT) confirmed by venography, we found heterogeneous individual venous flows, and variable side dominance in paired veins and sinuses, comparable to those in healthy volunteers. In CVT patients, PC-MRI detected no venous flow in the veins and/or sinuses with thrombosis. Arterial flows were preserved. CSF aqueductal and cervical stroke volumes were increased in a patient with secondary cerebral infarction, and decreased in 4 patients with extended thrombosis in the superior sagittal and transverse sinuses. These results suggest the main role of the venous system in the regulation of the dynamic intracranial equilibrium.

Conclusions:

CVT produces highly individualized pattern of disturbance in venous blood drainage. Complementary to MRI venography, PC-MRI provides non-invasive data about venous blockage consequences on CSF flow disturbances.
Assessment of data uncertainty and plausibility over the Nam Co Region, Tibet
Authors: Biskop S. , Krause P. , Helmschrot J. , Fink M. , Flügel W.-A.
Published: July 2012

Abstract. One of the major challenges for water balance studies in the remote and mostly ungauged region of the Tibetan Plateau is the lack of suitable and reliable climate data to drive hydrological models. Ground observations are rare in the high-mountainous region of the Nam Co basin and only global and regional gridded climate products are available as model input data, but these data sets need to be carefully analysed if used as driving force for hydrological modelling. In this study, various global and regional gridded data products for temperature and precipitation were compared to assess spatio-temporal deviations between several data sets. For the comparison absolute and relative differences of annual and seasonal long-term means were calculated. Climatic trends were analysed by using the non-parametric Mann-Kendall trend test. In addition, gridded climate data sets were compared to meteorological observations in order to evaluate their plausibility. The comparative statistical analysis showed significant differences in the magnitude, the seasonality, the spatial pattern and the trend behaviour of the analysed climate variables, in particular for precipitation data. The identified inconsistencies underpin the necessity to quantify the uncertainty of such climate data. Moreover, the presented study highlights the importance of further research efforts to develop regional climate data sets with finer resolutions to reduce the model's uncertainty resulting from climate input data. Such higher resolution is needed for a sufficient representation of regional topographic and orographic effects in order to simulate important hydrological processes in mountainous areas like snow accumulation and melting.
A simplified approach for generating GNSS radio occultation refractivity climatologies
Authors: Gleisner H. , Healy S. B.
Published: July 2012

Abstract. The possibility of simplifying the retrieval scheme required to produce GNSS radio occultation refractivity climatologies is investigated. In a new, simplified retrieval approach, the main statistical analysis is performed in bending angle space and an estimate of the average bending angle profile is then propagated through an Abel transform. The average is composed of means and medians of ionospheric corrected bending angles up to 80 km. Above that, the observed profile is exponentially extrapolated to infinity using a fixed a priori scale height. The new approach circumvents the need to introduce a "statistical optimization" processing step in which individual bending-angle profiles are merged with a priori data, often taken from a climatology. This processing step can be complex, difficult to interpret, and is generally recognized as a potential source of structural uncertainty. The new scheme is compared with the more conventional approach of averaging individual refractivity profiles, produced with the implementation of statistical optimization used in the EUMETSAT Radio Occultation Meteorology Satellite Application Facility (ROM SAF) operational processing. It is shown that the two GNSS radio occultation climatologies agree to within 0.1% from 5 km up to 35–40 km, for the three months January, February, and March 2011. During this time period, the new approach also produces slightly better agreement with ECMWF analyses between 40–50 km, which is encouraging. The possible limitations of the new approach caused by mean residual ionospheric errors and low observation numbers are discussed briefly, and areas for future work are suggested.
New insights on the role of organic speciation in the biogeochemical cycle of dissolved cobalt in the southeastern Atlantic and the Southern Ocean
Authors: Bown J. , Boye M. , Nelson D. M.
Published: July 2012

Abstract. The organic speciation of dissolved cobalt (DCo) was investigated in the subtropical region of the southeastern Atlantic, and in the Southern Ocean in the Antarctic Circumpolar Current (ACC) and the northern Weddell Gyre, between 34°25´ S and 57°33´ S along the Greenwich Meridian during the austral summer of 2008. The organic speciation of dissolved cobalt was determined by competing ligand exchange adsorptive cathodic stripping voltammetry (CLE-AdCSV) using nioxime as a competing ligand. The concentrations of the organic ligands (L) ranged between 26 and 73 pM, and the conditional stability constants (log K'CoL) of the organic complexes of Co between 17.9 and 20.1. Most dissolved cobalt was organically complexed in the water-column (60 to >99.9%). There were clear vertical and meridional patterns in the distribution of L and the organic speciation of DCo along the section. These patterns suggest a biological source of the organic ligands in the surface waters of the subtropical domain and northern subantarctic region, potentially driven by the cyanobacteria, and a removal of the organic Co by direct or indirect biological uptake. The highest L:DCo ratio (5.81 ± 1.07 pM pM−1) observed in these surface waters reflected the combined effects of ligand production and DCo consumption. As a result of these combined effects, the calculated concentrations of inorganic Co ([Co']) were very low in the subtropical and subantarctic surface waters, generally between 10−19 and 10−17 M. In intermediate and deep waters, the South African margins can be a source of organic ligands, as it was suggested to be for DCo (Bown et al., 2011), although a significant portion of DCo (up to 15%) can be stabilized and transported as inorganic species in those DCo-enriched water-masses. Contrastingly, the distribution of L does not suggest an intense biological production of L around the Antarctic Polar Front where a diatom bloom had recently occurred. Here [Co'] can be several orders of magnitude higher than those reported in the subtropical domain, suggesting that cobalt limitation was unlikely in the ACC domain. The almost invariant L:DCo ratio of ~1 recorded in these surface waters also reflected the conservative behaviours of both L and DCo. In deeper waters higher ligand concentrations were observed in waters previously identified as DCo sources (Bown et al., 2011). At those depths the eastward increase of DCo from the Drake Passage to the Greenwich Meridian could be associated with a large scale transport and remineralisation of DCo as organic complexes; here, the fraction stabilized as inorganic Co was also significant (up to 25%) in the low oxygenated Upper Circumpolar Deep Waters. Organic speciation may thus be a central factor in the biogeochemical cycle of DCo in those areas, playing a major role in the bioavailability and the geochemistry of Co.
Nitrous oxide emissions from crop rotations including wheat, rapeseed and dry pea
Authors: Jeuffroy M. H. , Baranger E. , Carrouée B. , de Chezelles E. , Gosme M. , Hénault C. , Schneider A. , Cellier P.
Published: July 2012

Abstract. Approximately 65% of anthropogenic emissions of N2O, a potent greenhouse gas, originate from soils at global scale, and particularly after N fertilisation of the main crops in Europe. Thanks to their capacity to fix atmospheric N2 through biological fixation, legumes allow to reduce N fertilizer use, and possibly N2O emission. Nevertheless, the decomposition of crop organic matter during the crop cycle and during the residue decomposition, and possibly the N fixation process itself, could lead to N2O emissions. The objective of this study was to quantify N2O emissions from a dry pea crop (Pisum sativum, harvested at maturity) and from the subsequent crops in comparison with N2O emissions from wheat and oilseed-rape crops, fertilized or not, in various rotations. A field experiment was conducted during 4 consecutive years, aiming at comparing the emissions during the pea crop, in comparison with those during the wheat (fertilized or not) or oilseed rape crops, and after the pea crop, in comparison with other preceding crops. N2O fluxes were measured using static chambers. In spite of low N2O fluxes, mainly linked with the site soil characteristics, fluxes during the crop were significantly lower for pea and unfertilized wheat than for fertilized wheat and oilseed rape. The effect of the preceding crop was not significant, while soil mineral N at harvest was higher after pea. These results, combined with the emission reduction allowed by the production and transport of the N fertiliser not applied on the pea crop, should be confirmed in a larger range of soil types. Nevertheless, they demonstrate the absence of N2O emission linked to the symbiotic N fixation process, and allow us to estimate the decrease of N2O emissions to 20–25% by including one pea crop in a three-year rotation. At a larger scale, this reduction of GHG emissions at field level has to be cumulated with the reduction of GHG emissions linked with the lower level of production and transport of the N fertiliser not applied on the pea crop.
OPTIMIZATION OF MIXING CONDITIONS FOR SILICA-REINFORCED NATURAL RUBBER TIRE TREAD COMPOUNDS
Authors: Kaewsakul W. , Sahakaro K. , Dierkes W. K. , Noordermeer J. W. M.
Published: July 2012

The dump temperature and mixing interval between rubber, silica, and silane coupling agent for silica-filled natural rubber (NR) tire tread compounds using bis-triethoxysilylpropyl tetrasulfide (TESPT) as silane were optimized. The dump temperature turns out to be the key parameter governing the properties of the silica-filled NR compounds. The increase in viscosity of the compounds by changing the dump temperature from 100 to 150 °C indicates that inevitably some cross-linking of NR occurs by sulfur contained in TESPT, simultaneous with the silanization reaction between silica and silane. However, the viscosity decreases again when dump temperatures above 150 °C are applied, indicating a dominant occurrence of degradation of the NR molecules. The results are in good agreement with bound rubber contents. The overall properties indicate that a dump temperature in the range of 135–150 °C and a silica–silane–rubber mixing interval of 10 min are the most appropriate mixing conditions for silica-filled NR compounds with TESPT as coupling agent.
STRAIN-INDUCED CRYSTALLIZATION AND MECHANICAL PROPERTIES OF NBR COMPOSITES WITH CARBON NANOTUBE AND CARBON BLACK
Authors: Ryu Sang-Ryeoul , Sung Jong-Whan , Lee Dong-Joo
Published: July 2012

The mechanical properties and strain-induced crystallization (SIC) of elastomeric composites were investigated as functions of the extension ratio (λ), multiwalled carbon nanotube (CNT) content, and carbon black (CB) content. The tensile strength and modulus gradually increase with increasing CNT content when compared with the matrix and the filled rubbers with same amount of CB. Both properties of rubber with CB and CNT show the magnitude of each CNT and CB component following the Pythagorean Theorem. The ratio of tensile modulus is much higher than that of tensile strength because of the CNT shape/orientation and an imperfect adhesion between CNT and rubber. The tensile strength and modulus of the composite with a CNT content of 9 phr increases up to 31% and 91%, respectively, compared with the matrix. Differential scanning calorimetry (DSC) analysis reveals that the degree of SIC increases with an increase in CNT content. Mechanical properties have a linear relation with the latent heat of crystallization (LHc), depending on the CNT content. As the extension ratio increases, the glass-transition temperature (Tg) of the composite increases for CB- and CNT-reinforced cases. However, the LHc has a maximum of λ = 1.5 for the CNT-reinforced case, which relates to a CNT shape and an imperfect adhesion with rubber. Based on these results, the reinforcing mechanisms of CNT and CB are discussed.
MONTMORILLONITE-REINFORCED NATURAL RUBBER NANOCOMPOSITES THROUGH EMULSION STABILIZATION–DESTABILIZATION METHOD
Authors: Park Jong-Min , Lee Chan-Woo , Lee Wan-Sul , Yang Kyung-Mo , Lee Jun-Ho , Nam Gi-Yong , Lee Seong-Hoon , Lee Yong Sang , Lee Youngkwan , Nam Jae-Do
Published: July 2012

A nanoplatelet of montmorillonite (MMT) was incorporated in the natural rubber (NR) matrix at a high loading content using a newly developed stabilization–destabilization process in the colloid states. Examination of the surface charge of the colloid drops by zeta potential measurement led to the identification of the stable and unstable conditions of the colloid mixture as well as each colloid system as a function of pH. The stabilized mixture of the MMT and NR colloids was subsequently destabilized by changing the pH of the mixture to achieve a well-dispersed and intercalated NR/MMT precipitate. The resulting NR/MMT nanocomposites provided an exfoliated MMT morphology up to 25 phr, and the mechanical properties and aging tolerance of the resulting nanocomposite vulcanizates were substantially enhanced by the incorporated MMT nanofillers. The developed stabilization–destabilization methodology ensured a highly loaded MMT rubber composite system, which could be used to obtain high performance NR/MMT nanocomposite systems with ease without using high-shear processing techniques.
Betacyanin accumulation and guaiacol peroxidase activity in Beta vulgaris L. leaves following copper stress
Authors: León Morales Janet M. , Rodríguez-Monroy Mario , Sepúlveda-Jiménez Gabriela
Published: July 2012

The effect of copper stress on betacyanin accumulation and guaiacol peroxidase (GPOD) activity in leaves of different age was evaluated in red beet (Beta vulgaris L. var. Crosby Egyptian) plants. In hydroponic culture, plants were treated with 0.3 μM (control), 50 μM, 100 μM, and 250 μM of CuSO4 for 6 days. Copper was taken up and accumulated in old roots but was not translocated to leaves. However in young leaves, the increase of lipid peroxidation and reduction of growth were evident from day 3 of copper exposure; whereas in old leaves, the lipid peroxidation and growth were the same from either copper-treated or control plants. In response to copper exposure, the betacyanin accumulation was evident in young leaves by day 3, and continued to increase until day 6. Betacyanin only were accumulated in old leaves until day 6, but the contents were from 4 to 5 times lower than those observed in young leaves at the same copper concentrations. GPOD activity increased 3.3- and 1.4-fold in young and old leaves from day 3 of copper treatment respectively, but only in the young leaves was sustained at the same level until day 6. Old roots shown betacyanin in the control plants, but the betacyanin level and growth were reduced with the copper exposure. In contrast, young roots emerged by copper effect also accumulated copper and showed the highest betacyanin content of all plant parts assayed. These results indicate that betacyanin accumulation and GPOD activity are defense responses to copper stress in actively growing organs.
“Toronto Has No History!” Indigeneity, Settler Colonialism, and Historical Memory in Canadas Largest City
Authors: Freeman Victoria
Published: July 2012

In 1884, during a week-long commemoration of the fiftieth anniversary of Toronto’s incorporation in 1834, tens of thousands celebrated Toronto’s history and its relation to British colonialism and imperialism. The author’s analysis of the historical tableaux in the first day’s parade and speeches by Daniel Wilson, president of University College, and Chief Samson Green of the Tyendinaga Mohawks reveals divergent approaches to commemoration as “politics by other means”: on one hand, the erasure of the area’s Indigenous past and the celebration of its European future, on the other, an idealized view of the past of Indigenous–settler partnership that ignores the role of local settlers in the dispossession of the Mississaugas. The 1884 commemoration marks the transition from the founding of the settlement in 1793 to its incorporation in 1834 as the city’s “founding moment” and marker of the assumed “indigeneity” of settler-immigrants. The deed acquired from the Mississaugas in the Toronto Purchase of 1787 is deemed irrelevant, while the 1834 Act of Incorporation becomes the symbolic deed to Toronto’s modernity.
Diasporas : ethnies sans frontières et sans politique?
Authors: Hadj-Moussa Ratiba
Published: July 2012

La littérature existante sur le thème des diasporas est aujourd’hui très abondante, et elle remet en question la manière dont cette notion était traditionnellement définie. Accompagnant le développement accéléré des mouvement migratoires qui s’opèrent conjointement avec les formes de la globalisation économique, cette littérature met désormais en cause un ensemble de définitions concernant les communautés diasporiques, en soulignant par là les difficiles questions de la formation, de la transformation et du maintien de l’identité culturelle. Elle remet également en question la place et le rôle du politique, en mettant en jeu le rapport entre territoire et ommunauté.
An ensemble-based approach to imputation of moderate-density genotypes for genomic selection with application to Angus cattle
Authors: SUN CHUANYU , WU XIAO-LIN , WEIGEL KENT A. , ROSA GUILHERME J. M. , BAUCK STEWART , WOODWARD BRENT W. , SCHNABEL ROBERT D. , TAYLOR JEREMY F. , GIANOLA DANIEL
Published: July 2012

Imputation of moderate-density genotypes from low-density panels is of increasing interest in genomic selection, because it can dramatically reduce genotyping costs. Several imputation software packages have been developed, but they vary in imputation accuracy, and imputed genotypes may be inconsistent among methods. An AdaBoost-like approach is proposed to combine imputation results from several independent software packages, i.e. Beagle(v3.3), IMPUTE(v2.0), fastPHASE(v1.4), AlphaImpute, findhap(v2) and Fimpute(v2), with each package serving as a basic classifier in an ensemble-based system. The ensemble-based method computes weights sequentially for all classifiers, and combines results from component methods via weighted majority ‘voting’ to determine unknown genotypes. The data included 3078 registered Angus cattle, each genotyped with the Illumina BovineSNP50 BeadChip. SNP genotypes on three chromosomes (BTA1, BTA16 and BTA28) were used to compare imputation accuracy among methods, and the application involved the imputation of 50K genotypes covering 29 chromosomes based on a set of 5K genotypes. Beagle and Fimpute had the greatest accuracy among the six imputation packages, which ranged from 0·8677 to 0·9858. The proposed ensemble method was better than any of these packages, but the sequence of independent classifiers in the voting scheme affected imputation accuracy. The ensemble systems yielding the best imputation accuracies were those that had Beagle as first classifier, followed by one or two methods that utilized pedigree information. A salient feature of the proposed ensemble method is that it can solve imputation inconsistencies among different imputation methods, hence leading to a more reliable system for imputing genotypes relative to independent methods.
Forskolin effect on the cryosurvival ofin vitro-produced bovine embryos in the presence or absence of fetal calf serum
Authors: Paschoal Daniela Martins , Sudano Mateus José , Guastali Midyan Daroz , Dias Maziero Rosiára Rosária , Crocomo Letícia Ferrari , Oña Magalhães Luis Carlos , da Silva Rascado Tatiana , Martins Alicio , da Cruz Landim-Alvarenga Fernanda
Published: July 2012

The objective of this study was to assess the viability and cryotolerance of zebu embryos producedin vitrowith or without the addition of fetal calf serum (FCS) and forskolin (F). Embryos producedin vivowere used as a control. Presumptive zygotes were cultured in modified synthetic oviductal fluid supplemented with amino acids (SOFaa), bovine serum albumin (BSA) and with (2.5%) or without (0%) FCS. On day 6 of growth, the embryos from each group were divided into treatments with or without 10 μM F to induce embryonic lipolysis, comprising a total of four experimental groups: 2.5% FCS, 0% FCS, 2.5% + F and 0% + F. For vitrification, embryos were exposed to vitrification solution 1 (5 M EG (ethylene glycol)) for 3 min and then transferred to vitrification solution 2 (7 M EG, 0.5 M galactose solution and 18% (w/v) Ficoll 70) before being introduced to liquid nitrogen. The presence of FCS in the culture medium resulted in the production of embryos with a similar rate of damaged cells compared within vivo-produced embryos. After vitrification, the 2.5% FCS group had a significantly higher rate of damaged cells when compared with the other groups (P< 0.05). The results of this experiment indicated that the omission of FCS and the addition of forskolin do not have deleterious effect on embryo production rates. In addition, embryos produced in the presence of FCS had greater sensitivity to cryopreservation, but this effect was reversed when forskolin was added to the medium, which improved embryo survival without affecting embryo development and quality after vitrification.
On the semiduals of local isometry groups in three-dimensional gravity
Authors: Osei Prince K. , Schroers Bernd J.
Published: July 2012

We use factorisations of the local isometry groups arising in 3D gravity for Lorentzian and Euclidean signatures and any value of the cosmological constant to construct associated bicrossproduct quantum groups via semidualisation. In this way, we obtain quantum doubles of the Lorentz and rotation groups in 3D, as well as κ-Poincaré algebras whose associated r-matrices have spacelike, timelike, and lightlike deformation parameters. We confirm and elaborate the interpretation of semiduality proposed by Majid and Schroers [“q-deformation and semi-dualisation in 3d quantum gravity,” J. Phys. A 42, 425402 (2009)]10.1088/1751-8113/42/42/425402 as the exchange of the cosmological length scale and the Planck mass in the context of 3D quantum gravity. In particular, semiduality gives a simple understanding of why the quantum double of the Lorentz group and the κ-Poincaré algebra with spacelike deformation parameter are both associated with 3D gravity with vanishing cosmological constant, while the κ-Poincaré algebra with a timelike deformation parameter can only be associated with 3D gravity if one takes the Planck mass to be imaginary.
Imaging of high-energy x-ray emission from cryogenic thermonuclear fuel implosions on the NIF
Authors: Ma T. , Izumi N. , Tommasini R. , Bradley D. K. , Bell P. , Cerjan C. J. , Dixit S. , Döppner T. , Jones O. , Kline J. L. , Kyrala G. , Landen O. L. , LePape S. , Mackinnon A. J. , Park H.-S. , Patel P. K. , Prasad R. R. , Ralph J. , Regan S. P. , Smalyuk V. A. , Springer P. T. , Suter L. , Town R. P. J. , Weber S. V. , Glenzer S. H.
Published: July 2012

Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide broadband time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered implosions. This diagnostic measures the temperature- and density-sensitive bremsstrahlung emission and provides estimates of hot spot mass, mix mass, and pressure.
Molybdenum emission from impurity-induced m = 1 snake-modes on the Alcator C-Mod tokamak
Authors: Delgado-Aparicio L. , Bitter M. , Granetz R. , Reinke M. , Beiersdorfer P. , Gates D. , Hill K. , Pablant N. , Podpaly Y. , Rice J. , Sugiyama L.
Published: July 2012

A suite of novel high-resolution spectroscopic imaging diagnostics has facilitated the identification and localization of molybdenum impurities as the main species during the formation and lifetime of m = 1 impurity-induced snake-modes on Alcator C-Mod. Such measurements made it possible to infer, for the first time, the perturbed radiated power density profiles from which the impurity density can be deduced.
Compact Kirkpatrick–Baez microscope mirrors for imaging laser-plasma x-ray emission
Authors: Marshall F. J.
Published: July 2012

Compact Kirkpatrick–Baez microscope mirror components for use in imaging laser-plasma x-ray emission have been manufactured, coated, and tested. A single mirror pair has dimensions of 14 × 7 × 9 mm and a best resolution of ∼5 μm. The mirrors are coated with Ir providing a useful energy range of 2–8 keV when operated at a grazing angle of 0.7°. The mirrors can be circularly arranged to provide 16 images of the target emission a configuration best suited for use in combination with a custom framing camera [F. J. Marshall, J. A. Oertel, and P. J. Walsh, Rev. Sci. Instrum. 75, 4045 (2004)]10.1063/1.1789258. An alternative arrangement of the mirrors would allow alignment of the images with a four-strip framing camera such as described in D. K. Bradley et al. [Rev. Sci. Instrum. 66, 716 (1995)]10.1063/1.1146268.
Long-range hydrogen-bond structure in aqueous solutions and the vapor-water interface
Authors: Irudayam Sheeba Jem , Henchman Richard H.
Published: July 2012

There is a considerable disagreement about the extent to which solutes perturb water structure. On the one hand, studies that analyse structure directly only show local structuring in a solute's first and possibly second hydration shells. On the other hand, thermodynamic and kinetic data imply indirectly that structuring occurs much further away. Here, the hydrogen-bond structure of water around halide anions, alkali cations, noble-gas solutes, and at the vapor-water interface is examined using molecular dynamics simulations. In addition to the expected perturbation in the first hydration shell, deviations from bulk behavior are observed at longer range in the rest of the simulation box. In particular, at the longer range, there is an excess of acceptors around halide anions, an excess of donors around alkali cations, weakly enhanced tetrahedrality and an oscillating excess and deficiency of donors and acceptors around noble-gas solutes, and enhanced tetrahedrality at the vapor-water interface. The structuring compensates for the short-range perturbation in water-water hydrogen bonds induced by the solute. Rather than being confined close to the solute, it is spread over as many water molecules as possible, presumably to minimize the perturbation to each water molecule.
Entangled trajectory molecular dynamics in multidimensional systems: Two-dimensional quantum tunneling through the Eckart barrier
Authors: Wang Lifei , Martens Craig C. , Zheng Yujun
Published: July 2012

In this paper, we extend the entangled trajectory molecular dynamics (ETMD) method to multidimensional systems. The integrodifferential form of the evolution equation for the Wigner function is employed, allowing general potentials not represented as a polynomial to be treated. As the example, the method is applied to a two-dimensional model of scattering from an Eckart barrier. The results of ETMD are in good agreement with quantum hydrodynamics and exact quantum simulations. By comparing the quantum and classical trajectory in phase space, the quantum tunneling phenomenon is interpreted vividly.
Influence of magnetic field strength on potential well in the ionization stage of a double stage Hall thruster
Authors: Yu Daren , Song Maojiang , Liu Hui , Zhang Xu , Li Hong
Published: July 2012

Similar to a single stage Hall thruster, the magnetic field, which controls electron trajectory and electric field distribution, is the most important factor determining the performance of a double stage Hall thruster. Especially, a potential well, which is helpful to reduce the ion loss on the thruster walls, is shaped in the ionization stage due to the existence of an annular magnetic field topology there. In this paper, the influence of magnetic field strength in the ionization stage on the potential well is researched with both experiments and particle-in-cell simulations. It is found that the depth of potential well increases with the magnetic field strength as a result of enhanced magnetic confinement and lowered electron conductivity. Consequently, the plasma density as well as the ion current entering the acceleration stage increases. However, an excessive magnetic field strength leads to an excess of ion loss on the walls of the acceleration stage. Therefore, there is an appropriate magnetic field strength in the ionization stage that results in a proper potential well and consequently an optimal performance of a double stage Hall thruster.
The effects of substrate size and temperature on the deposition of Cu clusters on a Si substrate
Authors: Gong Hengfeng , Lu Wei , Wang Lumin , Li Gongping , Zhang Shixu
Published: July 2012

The deposition of a Cu13 cluster on a Si (001) surface was studied by molecular dynamics simulations. Embedded atom method, Stillinger-Weber, and Lennar-Jones potentials were used to describe the interaction between cluster atoms, substrate atoms, and the cluster-substrate interaction. Quantitative characteristic parameters, such as kinetic energy of the cluster and the substrate, the degree of epitaxy, and the mean height of mass center of the cluster, were calculated to study the effect of substrate size and substrate temperature on cluster deposition. The substrate temperature was found to affect the degree of epitaxy at different substrate sizes. When the size ratio of the substrate and cluster is relatively small or large, the epitaxial degree was higher at 800 K than at 300 K. If the size of the substrate matches that of the cluster, the substrate temperature appeared to have minimum effect. For a given temperature, the substrate size was found to have no obvious effect on the degree of epitaxy or the mean height of mass center of the cluster. This observation indicated that simulations using even a small system can still give reliable results and qualitative description of the deposition phenomena. We also found that the cluster atoms prefer to diffuse along the [110] direction on the Si (001) surface.
Label-free monitoring of interaction between DNA and oxaliplatin in aqueous solution by terahertz spectroscopy
Authors: Wu Xiaojun , E Yiwen , Xu Xinlong , Wang Li
Published: July 2012

We demonstrated the feasibility of applying terahertz time-domain spectroscopy (THz-TDS) to monitor the molecular reactions in aqueous solutions of anticancer drug oxaliplatin with λ-DNA and macrophages DNA. The reaction time dependent refractive index and absorption coefficient were extracted and analyzed. The reaction half-decaying time of about 4.0 h for λ-DNA and 12.9 h for M-DNA was established. The results suggest that the THz-TDS detection could be an effective label-free technique to sense the molecular reaction in aqueous solutions and could be very useful in biology, medicine, and pharmacy industry.
Spectroscopic thermoacoustic imaging of water and fat composition
Authors: Bauer Daniel R. , Wang Xiong , Vollin Jeff , Xin Hao , Witte Russell S.
Published: July 2012

During clinical studies, thermoacoustic imaging (TAI) failed to reliably identify malignant breast tissue. To increase detection capability, we propose spectroscopic TAI to differentiate samples based on the slope of their dielectric absorption. Phantoms composed of different ratios of water and fat were imaged using excitation frequencies between 2.7 and 3.1 GHz. The frequency-dependent slope of the TA signal was highly correlated with that of its absorption coefficient (R2 = 0.98 and p < 0.01), indicating spectroscopic TAI can distinguish materials based on their intrinsic dielectric properties. This approach potentially enhances cancer detection due to the increased water content of many tumors.
Subpicosecond electron-hole recombination time and terahertz-bandwidth photoresponse in freestanding GaAs epitaxial mesoscopic structures
Authors: Mikulics Martin , Zhang Jie , Serafini John , Adam Roman , Grützmacher Detlev , Sobolewski Roman
Published: July 2012

We present the ultrafast (THz-bandwidth) photoresponse from GaAs single-crystal mesoscopic structures, such as freestanding whiskers and platelets fabricated by the top-down technique, transferred onto a substrate of choice, and incorporated into a coplanar strip line. We recorded electrical transients as short as ∼600 fs from an individual whisker photodetector. Analysis of the frequency spectrum of the photoresponse electrical signal showed that, intrinsically, our device was characterized by an ∼150-fs carrier lifetime and an overall 320-fs response. The corresponding 3-dB frequency bandwidth was 1.3 THz—the highest bandwidth ever reported for a GaAs-based photodetector. Simultaneously, as high-quality, epitaxially grown crystals, our GaAs structures exhibited mobility values as high as ∼7300 cm2/V·s, extremely low dark currents, and ∼7% intrinsic detection efficiency, which, together with their experimentally measured photoresponse repetition time of ∼1 ps, makes them uniquely suitable for terahertz-frequency optoelectronic applications, ranging from ultrafast photon detectors and counters to THz-bandwidth optical-to-electrical transducers and photomixers.
First principles investigation of structural, electronic, elastic and thermal properties of rare-earth-doped titanate Ln2TiO5
Authors: Niu Hui , Gou Huiyang , Ewing Rodney C. , Lian Jie
Published: July 2012

Systematic first-principles calculations based on density functional theory were performed on a wide range of Ln2TiO5 compositions (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Y) in order to investigate their structural, elastic, electronic, and thermal properties. At low temperature, these compounds crystallize in orthorhombic structures with a Pnma symmetry, and the calculated equilibrium structural parameters agree well with experimental results. A complete set of elastic parameters including elastic constants, Hill's bulk moduli, Young's moduli, shear moduli and Poisson's ratio were calculated. All Ln2TiO5 are ductile in nature. Analysis of densities of states and charge densities and electron localization functions suggests that the oxide bonds are highly ionic with some degree of covalency in the Ti-O bonds. Thermal properties including the mean sound velocity, Debye temperature, and minimum thermal conductivity were obtained from the elastic constants.