bluuebunny/crossref_metadata_2025_split huggingface dataset:
A metabolomic analysis of the toxicity of Aconitum sp. alkaloids in rats using gas chromatography/mass spectrometry
Authors: Sun Bo , Wu Shengming , Li Ling , Li Haijing , Zhang Qi , Chen Hebing , Li Famei , Dong Fangting , Yan Xianzhong 
Published: March 2009

AbstractA metabolomic investigation of intoxication with Aconitum sp. alkaloids was carried out. Plasma obtained from Wistar rats administered these alkaloids was analyzed using gas chromatography/time‐of‐flight mass spectrometry. Samples were analyzed following protein precipitation, liquid‐liquid extraction, and derivatization. Thirty‐six metabolites were identified among the detected compounds. Subsequent data analysis using the t test and principal component analysis revealed metabolic differences between the control rats and treated groups as well as between the groups of rats administered different alkaloids. Twenty‐seven metabolites were significantly different between plasma samples from the controls and treated groups. The significant decreased plasma levels of glutamine and creatinine in all treated groups suggested impaired heart and muscle function caused by alkaloids. The plasma levels of 22 metabolites in the hypaconitine group were significantly decreased. In contrast, only 8 and 13 metabolites were observed with significantly decreased levels in the aconitine and mesaconitine groups, respectively.These results indicated that Aconitum sp. alkaloids can cause metabolic disorders in rats. The toxicity and corresponding mechanism of hypaconitine was different from those of aconitine and mesaconitine, based on the differences of perturbed metabolic patterns between groups. Copyright © 2009 John Wiley & Sons, Ltd.
The use of limited dependent variable techniques in strategy research: issues and methods
Authors: Wiersema Margarethe F. , Bowen Harry P. 
Published: March 2009

AbstractStrategy researchers are increasingly turning their attention from examining the impact of strategic choices on firm performance to examining the factors that determine strategic choices at the firm level. This shift of research orientation has meant that researchers are increasingly faced with a limited dependent variable (LDV) that takes a limited number of usually discrete values, for which LDV methods such as logit or probit are required. Despite their growing popularity, there appears to be widespread problems in the use of LDV methods. This research note complements recent studies that offer general guidelines by presenting and illustrating the practical steps needed to implement the methods essential for analyzing and interpreting the results from LDV models. Copyright © 2009 John Wiley & Sons, Ltd.
Value appropriation as an organizational capability: the case of IP protection through patents
Authors: Reitzig Markus , Puranam Phanish 
Published: March 2009

AbstractWe develop and test a theoretical framework that describes the organizational antecedents of value appropriation capabilities in the context of obtaining patent protection. We argue that intermediate levels of cross‐functional involvement across intellectual property (IP) generation, protection, and utilization activities outperform very high or very low levels of functional specialization in terms of obtaining rapid patent protection; while these activities are distinct enough to generate gains from specialization, there are also significant gains to be generated by coordinating across them, which cross‐functional involvement achieves. Using a unique dataset that combines survey and patent (application) data, and multiple estimation techniques, we test and find support for our arguments. Copyright © 2009 John Wiley & Sons, Ltd.
Thermal Deposition of Intact Tetrairon(III) Single‐Molecule Magnets in High‐Vacuum Conditions
Authors: Margheriti Ludovica , Mannini Matteo , Sorace Lorenzo , Gorini Lapo , Gatteschi Dante , Caneschi Andrea , Chiappe Daniele , Moroni Riccardo , de Mongeot Francesco Buatier , Cornia Andrea , Piras Federica M. , Magnani Agnese , Sessoli Roberta 
Published: March 2009

AbstractA tetrairon(III) single‐molecule magnet is deposited using a thermal evaporation technique in high vacuum. The chemical integrity is demonstrated by time‐of‐flight secondary ion mass spectrometry on a film deposited on Al foil, while superconducting quantum interference device magnetometry and alternating current susceptometry of a film deposited on a kapton substrate show magnetic properties identical to the pristine powder. High‐frequency electron paramagnetic resonance spectra confirm the characteristic behavior for a system with S = 5 and a large Ising‐type magnetic anisotropy. All these results indicate that the molecules are not damaged during the deposition procedure keeping intact the single‐molecule magnet behavior.
Alternative Translation of OCT4 by an Internal Ribosome Entry Site and its Novel Function in Stress Response
Authors: Wang Xia , Zhao Yannan , Xiao Zhifeng , Chen Bing , Wei Zhanliang , Wang Bin , Zhang Jing , Han Jin , Gao Yuan , Li Lingsong , Zhao Hongxi , Zhao Wenxue , Lin Hang , Dai Jianwu 
Published: March 2009

Abstract
OCT4 is a pivotal transcription factor in maintaining the pluripotency and self-renewal capacities of embryonic stem (ES) cells. Human OCT4 can generate two isoforms by alternative splicing, termed OCT4A and OCT4B. OCT4A confers the stemness properties of ES cells, whereas the function of OCT4B is unknown. We present here the diverse protein products and a novel function of OCT4 gene. A single OCT4B mRNA can encode three isoforms by alternative translation initiation at AUG and CUG start codons, respectively. A putative internal ribosome entry site (IRES) has been identified in OCT4B mRNA accounting for the translation mechanism. The OCT4B-190 is upregulated under stress conditions and it may protect cell against apoptosis under stress. This work evokes the significance to distinguish the biological function of the protein products of OCT4. The OCT4 gene, by the regulation of alternative splicing and alternative translation initiation, may carry out more crucial roles in many biological events.
Disclosure of potential conflicts of interest is found at the end of this article.
The importance of surgical education in the accuracy of implant placement during hip fracture fixation
Authors: Parmar Vinay , Kumar A. J. Shyam 
Published: March 2009

Abstract

Background
Studies have found that tip apex distance (TAD) is the strongest independent predictor of lag screw cut-out following hip fracture fixation. The objective of this study was to understand the importance of introducing the concept of TAD to surgeons. The null hypothesis was that there were no differences between fractures fixed before awareness of TAD compared with fractures fixed after awareness of TAD.

Materials and Methods
This study involved assessing 75 consecutive radiographs retrospectively (before introduction of “tip apex distance” to surgeons) and 83 consecutive radiographs prospectively (after introduction of “tip apex distance” to surgeons). Radiographs were measured using a radiograph digitizer and software.

Results
Average TAD in radiographs measured retrospectively was 22.6 mm compared with 9.7 mm in radiographs analysed prospectively (P ≤ 0.001). The power of this study was 97%.

Conclusion
This study demonstrates that introducing the concept of “TAD” to surgeons, will improve the accuracy of lag screw placement during fixation of an extracapsular fracture. The improvements in lag screw placement will undoubted reduce cut-out of the implant post-surgery.
Immediate continuous passive motion after internal fixation of an ankle fracture
Authors: Farsetti Pasquale , Caterini Roberto , Potenza Vito , De Luna Vincenzo , De Maio Fernando , Ippolito Ernesto 
Published: March 2009

AbstractBackgroundSurgical treatment is usually mandatory in displaced bimalleolar and trimalleolar fractures. Some authors have recommended early mobilization of the ankle joint after surgical treatment of these lesions. In this study, we evaluate the effect of immediate postoperative continuous passive motion in the management of displaced bimalleolar and trimalleolar fractures treated surgically.Materials and methodsTwo series of 22 patients each, who had had a Weber type A, B or C ankle fracture treated surgically, were followed up at least 10 years after the injury. In the first series, immediately after surgery, a continuous passive motion machine was applied to the operated ankle for 3 weeks, whereas in the second series, after surgery a plaster splint or a plaster cast was applied for 3 weeks.ResultsAt follow-up, all patients were evaluated clinically and radiographically using the AOFAS Ankle Hindfoot Score System (Kitaoka, Foot Ankle 15:349–353, 1994). The average final score for the first series of patients was 95.7 points (range 87–100 points, standard deviation 3.42 points). Of this series, at radiographic examination, in two patients we observed minor signs of osteoarthritis of the ankle joint. The average final score for the second series was 88 points (range 68–100 points, standard deviation 10.60 points). At radiographic examination, in six patients we observed minor signs of osteoarthritis of the ankle joint, whereas in another one the osteoarthritis was severe.ConclusionsContinuous passive motion started immediately after surgery seems to be an effective method both for allowing complete and quick recovery of the range of motion of the ankle and for reducing the risk of early degenerative joint disease. Immediate passive ankle motion can be applied only after adequate reduction and stable internal fixation.
Electron-Spin Precession in Dependence of the Orientation of the External Magnetic Field
Authors: Miah M Idrish 
Published: March 2009

Abstract
Electron-spin dynamics in semiconductor-based heterostructures has been investigated in oblique magnetic fields. Spins are generated optically by a circularly polarized light, and the dynamics of spins in dependence of the orientation (θ) of the magnetic field are studied. The electron-spin precession frequency, polarization amplitude, and decay rate as a function ofθ are obtained and the reasons for their dependences are discussed. From the measured data, the values of the longitudinal and transverse components of the electrong-factor are estimated and are found to be in good agreement with those obtained in earlier investigations. The possible mechanisms responsible for the observed effects are also discussed.
Finite blocking property versus pure periodicity
Authors: MONTEIL THIERRY 
Published: March 2009

AbstractA translation surface 𝒮 is said to have the finite blocking property if for every pair (O,A) of points in 𝒮 there exists a finite number of ‘blocking’ points B1,…,Bn such that every geodesic from O to A meets one of the Bis. 𝒮 is said to be purely periodic if the directional flow is periodic in each direction whose directional flow contains a periodic trajectory (this implies that 𝒮 admits a cylinder decomposition in such directions). We will prove that the finite blocking property implies pure periodicity. We will also classify the surfaces that have the finite blocking property in genus two: such surfaces are exactly the torus branched coverings. Moreover, we prove that in every stratum such surfaces form a set of null measure. In Appendix A, we prove that completely periodic translation surfaces form a set of null measure in every stratum.
A family of 2-graphs arising from two-dimensional subshifts
Authors: PASK DAVID , RAEBURN IAIN , WEAVER NATASHA A. 
Published: March 2009

AbstractHigher-rank graphs (ork-graphs) were introduced by Kumjian and Pask to provide combinatorial models for the higher-rank Cuntz–KriegerC*-algebras of Robertson and Steger. Here we consider a family of finite 2-graphs whose path spaces are dynamical systems of algebraic origin, as studied by Schmidt and others. We analyse theC*-algebras of these 2-graphs, find criteria under which they are simple and purely infinite, and compute theirK-theory. We find examples whoseC*-algebras satisfy the hypotheses of the classification theorem of Kirchberg and Phillips, but are not isomorphic to theC*-algebras of ordinary directed graphs.
Unitary representations of wavelet groups and encoding of iterated function systems in solenoids
Authors: DUTKAY DORIN ERVIN , JORGENSEN PALLE E. T. , PICIOROAGA GABRIEL 
Published: March 2009

AbstractFor points indreal dimensions, we introduce a geometry for general digit sets. We introduce a positional number system where the basis for our representation is a fixedd by dmatrix over ℤ. Our starting point is a given pair (A,𝒟) with the matrixAassumed expansive, and 𝒟 a chosen complete digit set, i.e., in bijective correspondence with the points in ℤd/ATℤd. We give an explicit geometric representation and encoding with infinite words in letters from 𝒟. We show that the attractorX(AT,𝒟) for an affine Iterated Function System (IFS) based on (A,𝒟) is a set of fractions for our digital representation of points in ℝd. Moreover our positional ‘number representation’ is spelled out in the form of an explicit IFS-encoding of a compact solenoid 𝒮Aassociated with the pair (A,𝒟). The intricate part (Theorem 6.15) is played by the cycles in ℤdfor the initial (A,𝒟)-IFS. Using these cycles we are able to write down formulas for the two maps which do the encoding as well as the decoding in our positional 𝒟-representation. We show how some wavelet representations can be realized on the solenoid, and on symbolic spaces.
Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions
Authors: Dromey B. , Bellei C. , Carroll D.C. , Clarke R.J. , Green J.S. , Kar S. , Kneip S. , Markey K. , Nagel S.R. , Willingale L. , McKenna P. , Neely D. , Najmudin Z. , Krushelnick K. , Norreys P.A. , Zepf M. 
Published: March 2009

AbstractAs the state of the art for high power laser systems increases from terawatt to petawatt level and beyond, a crucial parameter for routinely monitoring high intensity performance is laser spot size on a solid target during an intense interaction in the tight focus regime (<10 µm). Here we present a novel, simple technique for characterizing the spatial profile of such a laser focal spot by imaging the interaction region in third harmonic order (3ωlaser). Nearly linear intensity dependence of 3ωlaser generation for interactions >1019 Wcm−2 is demonstrated experimentally and shown to provide the basis for an effective focus diagnostic. Importantly, this technique is also shown to allow in-situ diagnosis of focal spot quality achieved after reflection from a double plasma mirror setup for very intense high contrast interactions (>1020 Wcm−2) an important application for the field of high laser contrast interaction science.
Error Mechanisms in Indoor Positioning Systems without Support from GNSS
Authors: Michalson William R. , Navalekar Abhijit , Parikh Hemish K. 
Published: March 2009

A version of this paper was first presented at the Royal Institute of Navigation NAV 08 Conference held at Church House, Westminster, London in October 2008.There exist various applications for indoor positioning, amongst which indoor positioning and tracking in urban environments has gained significant attention. Some user communities, like fire fighters, ideally require indoor accuracy of less than one metre, with accuracies of less than six metres acceptable by some other user communities. Achieving this level of accuracy requires a detailed profiling of error sources so that they can be better understood so that, in turn, indoor positioning accuracy in the presence of these errors can be further improved. Some well known error sources like multipath, NLOS (non line of sight), oscillator drift, dilution of precision and others have been studied and can be found in the literature. A less well known error source that can substantially affect indoor positioning accuracy are the effects of the dielectric properties of building materials on propagation delay.Various RF and non-RF based prototypes that claim to be suitable for indoor positioning can be found in the literature. Most of the existing literature discusses algorithms and summarizes the positioning results that were achieved during field tests using a prototype system or, more commonly, simulations. Little of this existing literature provides a breakdown of the total navigation system errors observed with the objective of analyzing the contribution of each error source independently.The paper will first provide a brief overview of the precision personnel locator system developed at the Worcester Polytechnic Institute. The field tests and observed indoor positioning results using this RF prototype will then be summarized and used to provide a baseline to establish a system error budget. The total observed error will be broken down and a detailed analysis of each of the error sources will be presented based on actual measured data in a variety of indoor environments. This leads to a better understanding of how each error source affects indoor positioning accuracy. Each of the error sources can then be independently optimized to minimize the observed errors. Specifically, the interplay between the dielectric properties and multipath profiles will be highlighted. This paper will conclude by presenting an error budget which can be used as a practical lower bound when designing precise indoor positioning systems.
GPS Jamming and the Impact on Maritime Navigation
Authors: Grant Alan , Williams Paul , Ward Nick , Basker Sally 
Published: March 2009

Versions of this paper were first presented at the Royal Institute of Navigation GNSS Vulnerabilities and Solutions Conference held at Baska, Croatia in September 2008 and the Royal Institute of Navigation NAV 08 Conference held at Church House, Westminster, London in October 2008.The US Global Positioning System (GPS) is currently the primary source of Position, Navigation and Timing (PNT) information in maritime applications, whether stand-alone or augmented with additional systems. This situation will continue in the future with GPS, possibly together with other Global Navigation Satellite Systems (GNSS) e.g. Galileo, being the core PNT technology for e-Navigation – the future digital maritime architecture. GPS signals, measured at the surface on the Earth, are very weak. As such, the system is vulnerable to unintentional interference and jamming, resulting in possible denial of service over large geographical areas. The result of such interference could be the complete failure of the mariner's GPS receiver or, possibly worse, the presentation to the mariner of hazardously misleading information (HMI) for navigation and situational awareness, depending on how the GPS receiver reacts to the jamming incident. Recognising this, the General Lighthouse Authorities of the United Kingdom and Ireland (GLA), in collaboration with the UK Ministry of Defence (MOD) Defence Science and Technology Laboratory (DSTL), have conducted a series of sea-trials with the aim of identifying the full effects of GPS jamming on safe navigation at sea.This paper presents the key findings of these trials and provides important information on the effect of GPS denial. The GLA are playing a pivotal role in the establishment of eLoran as an independent source of PNT, taking advantage of eLoran's complementary nature, having dissimilar failure modes to GPS and the future GNSS. This paper provides information on the performance of an eLoran receiver in an area of GPS service denial. The paper presents the rationale for the work, details the system architecture employed, the data gathering efforts and finally the data analysis procedures, results and conclusions.
Virtual evolution for visual search in natural images results in behavioral receptive fields with inhibitory surrounds
Authors: ZHANG SHENG , ABBEY CRAIG K. , ECKSTEIN MIGUEL P. 
Published: March 2009

AbstractThe neural mechanisms driving perception and saccades during search use information about the target but are also based on an inhibitory surround not present in the target luminance profile (e.g., Eckstein et al., 2007). Here, we ask whether these inhibitory surrounds might reflect a strategy that the brain has adapted to optimize the search for targets in natural scenes. To test this hypothesis, we sought to estimate the best linear template (behavioral receptive field), built from linear combinations of Gabor channels representing V1 simple cells in search for an additive Gaussian target embedded in natural images. Statistically nonstationary and non-Gaussian properties of natural scenes preclude calculation of the best linear template from analytic expressions and require an iterative optimization method such as a virtual evolution via a genetic algorithm. Evolved linear receptive fields built from linear combinations of Gabor functions include substantial inhibitory surround, larger than those found in humans performing target search in white noise. The inhibitory surrounds were robust to changes in the contrast of the signal, generalized to a larger calibrated natural image data set, and tasks in which the signal occluded other objects in the image. We show that channel nonlinearities can have strong effects on the observed linear behavioral receptive field but preserve the inhibitory surrounds. Together, the results suggest that the apparent suboptimality of inhibitory surrounds in human behavioral receptive fields when searching for a target in white noise might reflect a strategy to optimize detection of signals in natural scenes. Finally, we contend that optimized linear detection of spatially compact signals in natural images might be a new possible hypothesis, distinct from decorrelation of visual input and sparse representations (e.g., Graham et al., 2006), to explain the evolution of center–surround organization of receptive fields in early vision.
Distribution, ecology and conservation of an endangered Andean hummingbird: the Violet-throated Metaltail (Metallura baroni)
Authors: TINOCO BORIS A. , ASTUDILLO PEDRO X. , LATTA STEVEN C. , GRAHAM CATHERINE H. 
Published: March 2009

SummaryThe Violet-throated MetaltailMetallura baroniis a high altitude hummingbird endemic to south-central Ecuador currently considered globally ‘Endangered’. Here we present the first detailed assessment of its distribution, ecology and conservation. We first used a maximum entropy model (Maxent model) to create a predicted distribution for this species based on very limited species occurrence data. We used this model to guide field surveys for the species between April and October 2006. We found a positive relationship between model values and species presence, indicating that the model was a useful tool to predict species occurrence and guide exploration. In the sites where the metaltail was found we gathered data on its habitat requirements, food resources and behaviour. Our results indicate that Violet-throated Metaltail is restricted to the Western Cordillera of the Andes Mountains in Azuay and Cañar provinces of Ecuador, with an area of extent of less than 2,000 km2. Deep river canyons to the north and south, lack of suitable habitat, and potential interspecific competition in the east may limit the bird's distribution. The species occurred in three distinct habitats, includingPolylepiswoodland, the upper edge of the montane forest, and in shrubby paramo, but we found no difference in relative abundance among these habitats. The metaltail seems to tolerate moderate human intervention in its habitats as long as some native brushy cover is maintained. We found thatBrachyotumsp.,Berberissp., andBarnadesiasp. were important nectar resources. The ‘Endangered’ status of this species is supported due to its restricted distribution in fragmented habitats which are under increasing human pressures.