bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alignment of the cell nucleus from labeled proteins only for 4D in vivo imaging
Authors: Rieger B. , Molenaar C. , Dirks R.W. , Van Vliet L.J. 
Published: August 2004

AbstractStudies of protein dynamics by 4D (3D + time) confocal microscopy in vivo are hampered by global cell motion. The time between the acquisitions of the 3D images is in the order of minutes. Therefore, it is not to be expected that the cell as a whole remains fixed in the water basin on the stage. This superimposes a motion on the protein dynamics that has to be removed. We present a robust registration technique to align the cell images that does not require the a priori establishment of point‐to‐point correspondences. Instead, it uses the distribution of the labeled proteins. After correction for the translation, the 3D rotation of the cell is estimated. A robust intrinsic body coordinate system is constructed via the inertia tensor from the intensity distribution. By combining basis transformation to this intrinsic coordinate system, we can calculated the rotation matrix in a conceptual and computational straightforward manner. We have evaluated the performance of this approach in three experiments with human osteaosarcoma cells (U‐2 OS), where the nuclear proteins Histon H4 and PML were visualized. The PML is concentrated in several dozen nuclear spots. Expression of Histon H4 results in a total nuclear staining. The registration results for both channels computed independently are very similar. Practically, this means that only the labeled material needs to be observed and still registration of the cell as a whole can be achieved. Microsc. Res. Tech. 64:142–150, 2004. © 2004 Wiley‐Liss, Inc.
3D restoration with multiple images acquired by a modified conventional microscope
Authors: Vermolen B.J. , Garini Y. , Young I.T. 
Published: August 2004

AbstractA problem in high magnification microscopy is the blurring in the imaging of an object. In this article, we demonstrate a restoration technique that simultaneously makes use of the confocal image and the wide‐field image. These images can be acquired by a modified conventional microscope. In front of the light‐source, there is an array of pinholes. There are no pinholes at the detection plane. Instead, one or more pixels from the CCD camera are used, where the pinholes would have been. Using all pixels gives the wide‐field image, but using a selected subset can give a confocal image. The array is used to speed up the process of acquiring the image. Note that the speed of acquisition is proportional to the number of pinholes. We show that the restoration from the two images can lead to a better result than using only one of the images. If this is the case, we show that a distance of 5 times the diameter of the pinholes can give the same results as a distance of 20 times after deconvolution. This offers an increase in acquisition time of a factor 16. Microsc. Res. Tech. 64:113–125, 2004. © 2004 Wiley‐Liss, Inc.
Optical‐sectioning improvement in two‐color excitation scanning microscopy
Authors: Ibáñez‐López Cristina , Escobar Isabel , Saavedra Genaro , Martínez‐Corral Manuel 
Published: August 2004

AbstractWe present a new beam‐shaping technique for two‐color excitation fluorescence microscopy. We show that by simply inserting a properly designed shaded‐ring filter in the illumination beam of smaller wavelength, it is possible to improve the effective optical sectioning capacity of such microscopes by 23%. Such an improvement is obtained at the expense of only a very small increasing of the overall energy in the point‐spread‐function sidelobes. The performance of this technique is illustrated by a numerical imaging simulation. Microsc. Res. Tech. 64:96–102, 2004. © 2004 Wiley‐Liss, Inc.
Applying spectral fingerprinting to the analysis of FRET images
Authors: Neher Richard A. , Neher Erwin 
Published: August 2004

AbstractFörster resonance energy transfer (FRET) allows one to study interactions between two fluorescently labeled molecules (donors and acceptors) at distances on the order of 5 nm. Many studies have described methods of how to measure the efficiency of FRET. However, few have addressed the question of how fluorescence from unpaired donors and acceptors can be determined in addition to that from FRET‐pairs and how the signal‐to‐noise ratio (SNR) of such estimates depends on the presence of the partner species. Such knowledge, however, is essential for many biological applications, in which—after initial characterization of the spectral properties of a well‐defined donor‐acceptor complex—the in vivo affinity and stoichiometry of the complex is of interest. Here, we provide a theoretical analysis on how spectral fingerprinting can be applied to separate fluorescence of FRET pairs from that originating from unpaired donors and acceptors and how to select imaging parameters to optimize the SNR of the estimates. Thereby, we uncover a fundamental problem in this application and discuss ways to evade its adverse consequences. We compare the expected resolution of traditional FRET measures with that of optimized spectral fingerprinting and analyze the resolution of a method for FRET measurements that combines spectral with fluorescence lifetime information. Microsc. Res. Tech. 64:185–195, 2004. © 2004 Wiley‐Liss, Inc.
Optimization of the extraction of paclitaxel from Taxus baccata L. by the use of microwave energy
Authors: Talebi Mohammad , Ghassempour Alireza , Talebpour Zahra , Rassouli Ali , Dolatyari Lila 
Published: August 2004

AbstractA simple and rapid microwave‐assisted extraction (MAE) procedure was developed and optimized for the extraction of paclitaxel (Taxol®) from the needles of yew trees Taxus baccata L. grown in Iranian habitats. The samples, immersed in a methanol‐water mixture, were irradiated with microwaves in a closed‐vessel system. The method was evaluated using a factorial design approach based on parameters such as extraction time, temperature, methanol concentration in water (v/v), and the ratio of grams of sample to 10 mL of solvent. Statistical treatment of the results revealed that the selected parameters were all significant except the extraction time. Optimum conditions would be 1.5 g samples in 10 mL solvent (90% methanol), an extraction temperature of 95°C, and an extraction time of 7 min. The extracts has been analyzed by reverse‐phase high‐performance liquid chromatography with UV detection (LC/UV) at 227 nm for quantification. Liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) was used for confirmation. The main advantage of the proposed MAE method versus conventional solvent extraction (CSE) are the considerable reductions in time (7 min versus 16 h) and in solvent consumption (20 mL versus 150 mL). The MAE procedure yielded extracts that could be analyzed directly without any preliminary clean‐up or solvent exchange steps. Both extraction methods show RSDs lower than 10% and lead to comparable recoveries of paclitaxel (87–92%).
Association Behavior between End‐Functionalized Block Copolymers PEO‐PPO‐PEO and Poly(acrylic acid)
Authors: Wang Ying , Goethals Eric J. , Du Prez Filip E. 
Published: August 2004

AbstractSummary: The end groups of ABA‐triblock copolymers HO–PEO–PPO–PEO–OH, (PEO – poly(ethylene oxide), PPO – poly(propylene oxide)), have been modified with ammonia, ethylene diamine and linear polyethylenimine (LPEI) by substitution of the α,ω‐ditosyl ester of the triblock copolymer (TsO–PEO–PPO–PEO–OTs) with amines, or by the hydrolysis of the corresponding poly(2‐methyl‐2‐oxazoline) (PMeOx) containing ABCBA block copolymers. The latter block copolymer structures have been obtained by the polymerization of MeOx using TsO–PEO–PPO–PEO–OTs as a macro‐initiator. Adding poly(acrylic acid) (PAA) to these (poly)amine terminated block copolymers leads to the formation of networks through a combination of PAA–PEO hydrogen bonding and PAA–(poly)amine acid‐base reaction. Depending on the number of amino groups at both chain ends of the block copolymer, the corresponding complexes behave as liquids, gels or precipitates. Introduction of as little as 1–5 wt.‐% block copolymers H2N–PEO–PPO–PEO–NH2 or H2NCH2CH2NH–PEO–PPO–PEO–NHCH2CH2NH2 to the system of HO–PEO–PPO–PEO–OH/PAA leads to viscous liquids with strong shear‐thickening behavior.Reversible gel formation via the ternary PAA/HO–PEO–PPO–PEO–OH/H2N–PEO–PPO–PEO–NH2 system under shear conditions.magnified imageReversible gel formation via the ternary PAA/HO–PEO–PPO–PEO–OH/H2N–PEO–PPO–PEO–NH2 system under shear conditions.
High‐Molecular‐Weight Isobutene–Isoprene Copolymers Containing Unusually High Isoprene Content
Authors: McInenly Paula J. , Drewitt Mark J. , Baird Michael C. 
Published: August 2004

AbstractSummary: The 1:2 adduct of the highly electrophilic borane B(C6F5)3 with n‐decanoic (stearic) acid, [n‐C17H35CO2H][B(C6F5)3]2 exhibits sufficiently enhanced acidity that it is an excellent initiator for the carbocationic copolymerization of isobutene with isoprene in methylene chloride and methyl chloride. High conversions to gel free, high‐molecular‐weight copolymers containing up to 15 wt.‐% isoprene are readily obtained, consistent with the anion [n‐C17H35CO2{BC6F5)3}2]− being very weakly coordinating. Thus chain transfer following IP incorporation into the growing polymeric chain, which normally results in low average molecular weights, is much less of a factor here.The acidic 1:2 adduct of B(C6F5)3 with n‐decanoic acid, [n‐C17H35CO2H][B(C6F5)3]2, as an initiator for the carbocationic copolymerization of isobutene with isoprene.magnified imageThe acidic 1:2 adduct of B(C6F5)3 with n‐decanoic acid, [n‐C17H35CO2H][B(C6F5)3]2, as an initiator for the carbocationic copolymerization of isobutene with isoprene.
Index sets for computable differential equations
Authors: Cenzer Douglas , Remmel Jeffrey B. 
Published: August 2004

AbstractIndex sets are used to measure the complexity of properties associated with the differentiability of real functions and the existence of solutions to certain classic differential equations. The new notion of a locally computable real function is introduced and provides several examples of Σ04 complete sets. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two constructive embedding‐extension theorems with applications to continuity principles and to Banach‐Mazur computability
Authors: Bauer Andrej , Simpson Alex 
Published: August 2004

AbstractWe prove two embedding and extension theorems in the context of the constructive theory of metric spaces. The first states that Cantor space embeds in any inhabited complete separable metric space (CSM) without isolated points, X, in such a way that every sequentially continuous function from Cantor space to ℤ extends to a sequentially continuous function from X to ℝ. The second asserts an analogous property for Baire space relative to any inhabited locally non‐compact CSM. Both results rely on having careful constructive formulations of the concepts involved.As a first application, we derive new relationships between “continuity principles” asserting that all functions between specified metric spaces are pointwise continuous. In particular, we give conditions that imply the failure of the continuity principle “all functions from X to ℝ are continuous”, when X is an inhabited CSM without isolated points, and when X is an inhabited locally non‐compact CSM. One situation in which the latter case applies is in models based on “domain realizability”, in which the failure of the continuity principle for any inhabited locally non‐compact CSM, X, generalizes a result previously obtained by Escardó and Streicher in the special case X = C[0, 1].As a second application, we show that, when the notion of inhabited complete separable metric space without isolated points is interpreted in a recursion‐theoretic setting, then, for any such space X, there exists a Banach‐Mazur computable function from X to the computable real numbers that is not Markov computable. This generalizes a result obtained by Hertling in the special case that X is the space of computable real numbers. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximation representations for reals and their wtt‐degrees
Authors: Barmpalias George 
Published: August 2004

AbstractWe study the approximation properties of computably enumerable reals. We deal with a natural notion of approximation representation and study their wtt‐degrees. Also, we show that a single representation may correspond to a quite diverse variety of reals. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Density and Baire category in recursive topology
Authors: Kalantari Iraj , Welch Larry 
Published: August 2004

AbstractWe develop the concepts of recursively nowhere dense sets and sets that are recursively of first category and study closed sets of points in light of Baire's Category Theorem. Our theorems are primarily concerned with exdomains (i. e. complements of domains) of recursive quantum functions and hence with avoidable points (i. e. points that can be forced into exdomains of recursive quantum functions). An avoidance function is a recursive function which can be used to expel avoidable points from domains of recursive quantum functions. We define an avoidable set of points to be an arbitrary subset of the avoidable points of a single avoidance function, and we study an effective union of such sets which we call a piecemeal avoidable set. We note that each of ‘the set of recursive points’ and ‘the set of avoidable points’ is of first category but not recursively of first category. We show an exdomain exists which is recursively nowhere dense, as well as one that is nowhere dense but not recursively nowhere dense. After establishing that every exdomain is recursively of first category, we prove that given any fixed exdomain, there is another exdomain, which while dense in the underlying space, is disjoint from the fixed exdomain. Finally, we show how to build a recursive sequence of recursive quantum functions that have mutually disjoint, dense exdomains. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computable operators on regular sets
Authors: Ziegler Martin 
Published: August 2004

AbstractFor regular sets in Euclidean space, previous work has identified twelve ‘basic’ computability notions to (pairs of) which many previous notions considered in literature were shown to be equivalent. With respect to those basic notions we now investigate on the computability of natural operations on regular sets: union, intersection, complement, convex hull, image, and pre‐image under suitable classes of functions. It turns out that only few of these notions are suitable in the sense of rendering all those operations uniformly computable. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterizations of the class Δta2 over Euclidean spaces
Authors: Hemmerling Armin 
Published: August 2004

AbstractWe present some characterizations of the members of Δta2, that class of the topological arithmetical hierarchy which is just large enough to include several fundamental types of sets of points in Euclidean spaces ℝk. The limit characterization serves as a basic tool in further investigations. The characterization by effective difference chains of effectively exhaustible sets yields only a hierarchy within a subfield of Δta2. Effective difference chains of transfinite (but constructive) order types, consisting of complements of effectively exhaustible sets, as well as another closely related concept, yield a rich hierarchy within the whole class Δta2. The presentation always first reports analogies between Hausdorff's difference hierarchy within the Borel class ΔB2 and Ershov's hierarchy within the class Δ02 of the arithmetical hierarchy; after that the counterparts for Δta2 are developed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Type‐2 computability on spaces of integrable functions
Authors: Kunkle Daren 
Published: August 2004

AbstractUsing Type‐2 theory of effectivity, we define computability notions on the spaces of Lebesgue‐integrable functions on the real line that are based on two natural approaches to integrability from measure theory. We show that Fourier transform and convolution on these spaces are computable operators with respect to these representations. By means of the orthonormal basis of Hermite functions in L2, we show the existence of a linear complexity bound for the Fourier transform. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Baire category and nowhere differentiability for feasible real functions
Authors: Breutzmann Josef M. , Juedes David W. , Lutz Jack H. 
Published: August 2004

AbstractA notion of resource‐bounded Baire category is developed for the classPC[0,1]of all polynomial‐time computable real‐valued functions on the unit interval. The meager subsets ofPC[0,1]are characterized in terms of resource‐bounded Banach‐Mazur games. This characterization is used to prove that, in the sense of Baire category, almost every function inPC[0,1]is nowhere differentiable. This is a complexity‐theoretic extension of the analogous classical result that Banach proved for the classC[0, 1] in 1931. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computability and continuity in metric partial algebras equipped with computability structures
Authors: Dahlgren Fredrik 
Published: August 2004

AbstractIn this paper we give an axiomatisation of the concept of a computability structure with partial sequences on a many‐sorted metric partial algebra, thus extending the axiomatisation given by Pour‐El and Richards in [9] for Banach spaces. We show that every Banach‐Mazur computable partial function from an effectively separable computable metric partial Σ‐algebraAto a computable metric partial Σ‐algebraBmust be continuous, and conversely, that every effectively continuous partial function with semidecidable domain and which preserves the computability of a computably enumerable dense set must be computable. Finally, as an application of these results we give an alternative proof of the first main theorem for Banach spaces first proved by Pour‐El and Richards. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First steps in constructive game theory
Authors: Bridges Douglas S. 
Published: August 2004

AbstractThe minimax theorem of matrix game theory is examined from a constructive point of view. It is then shown that the existence of solutions for matrix games cannot be proved constructively, but that a 2‐by‐2 game with at most one solution has a constructible solution. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fast quantum algorithms for handling probabilistic and interval uncertainty
Authors: Kreinovich Vladik , Longpré Luc 
Published: August 2004

AbstractIn many real‐life situations, we are interested in the value of a physical quantity y that is difficult or impossible to measure directly. To estimate y, we find some easier‐to‐measure quantities x1, … , xn which are related to y by a known relation y = f(x1, … , xn). Measurements are never 100% accurate; hence, the measured values $ \tilde {x} _{i} $ are different from xi, and the resulting estimate $ \tilde {y} = f( \tilde {x} _{1} \ldots , \tilde {x} _{n}) $ is different from the desired value y = f(x1, … , xn). How different can it be? Traditional engineering approach to error estimation in data processing assumes that we know the probabilities of different measurement errors $ \Delta x_i {\mathop {=} \limits ^{\rm def}} \tilde x _i - x_i $. In many practical situations, we only know the upper bound Δi for this error; hence, after the measurement, the only information that we have about xi is that it belongs to the interval $ {\bf x}_i {\mathop {=} \limits ^{\rm def}} [ \tilde x _i - \Delta _i, \tilde x_i + \Delta _i] $. In this case, it is important to find the range y of all possible values of y = f(x1, … , xn) when xi ∈ xi. We start the paper with a brief overview of the computational complexity of the corresponding interval computation problems: Most of the related problems turn out to be, in general, at least NP‐hard. In this paper, we show how the use of quantum computing can speed up some computations related to interval and probabilistic uncertainty. We end the paper with speculations on whether (and how) “hypothetic” physical devices can compute NP‐hard problems faster than in exponential time. Most of the paper's results were first presented at NAFIPS'2003 [30]. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Global non‐existence of solutions of a class of wave equations with non‐linear damping and source terms
Authors: Messaoudi Salim A. , Houari Belkacem Said 
Published: August 2004

AbstractIn this paper we consider the non‐linear wave equation

a,b>0, associated with initial and Dirichlet boundary conditions. We prove, under suitable conditions on α,β,m,p and for negative initial energy, a global non‐existence theorem. This improves a result by Yang (Math. Meth. Appl. Sci. 2002; 25:825–833), who requires that the initial energy be sufficiently negative and relates the global non‐existence of solutions to the size of Ω. Copyright © 2004 John Wiley & Sons, Ltd.
Use of recombinant factor VIIa (rFVIIa) to control intraoperative bleeding in pediatric brain tumor patients
Authors: Heisel M. , Nagib M. , Madsen L. , Alshiekh M. , Bendel A. 
Published: August 2004

AbstractSurgical bleeding during the resection of brain tumors in children may be related to tumor vascularity, pathology, and location. Despite improvements in neurosurgical technique, neuroanesthesia, and blood product replacement, bleeding can be life‐threatening in these surgeries. We report eight pediatric patients in whom recombinant factor VIIa (rFVIIa) was used to control intraoperative bleeding during surgical resection of pediatric brain tumors. rFVIIa should be considered as a method to control intraoperative bleeding that is unresponsive to conventional interventions. Additional studies are needed to determine optimal patient selection and drug dosing, efficacy and safety. © 2004 Wiley‐Liss, Inc.
Attention and information processing in survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only
Authors: Mennes Maarten , Stiers Peter , Vandenbussche Erik , Vercruysse Gertrui , Uyttebroeck Anne , Meyer Geert De , Van Gool Stefaan W. 
Published: August 2004

AbstractBackgroundOmitting radiotherapy for central nervous system (CNS) prophylaxis has improved the overall quality of life for long‐term survivors of childhood acute lymphoblastic leukemia (ALL). However, recent reports suggest minor cognitive impairment in survivors who received chemotherapy only.ProcedureThis study focused on attentional functioning and speed of information processing in 23 children previously treated for ALL according to EORTC 58881 and EORTC 58951 protocol. Patients received intrathecal methotrexate combined with high doses intravenous methotrexate as CNS prophylaxis. Cognitive functioning was assessed with the Amsterdam Neuropsychological Tasks, a computerized attention assessment program. Variables of both speed and accuracy of the patients were compared with those obtained from 23 age‐ and sex‐matched control children.ResultsPatients were equal to control children concerning baseline speed, sustained attention, response inhibition, and response organization. However, they were significantly slower than controls in three tasks: encoding, memory search letters, and focused attention 4‐letters. Interactions with the difficulty of the task were found. There were no differences in number or type of errors between groups on all tasks.ConclusionsALL survivors treated with chemotherapy have specific information processing difficulties. They process information slower than control children, especially when more information has to be processed or when attention has to be focused precisely. In spite of being slower, patients are equally accurate compared to control children. © 2004 Wiley‐Liss, Inc.