bluuebunny/crossref_metadata_2025 huggingface dataset:
FT-IR, XPS, and AES Studies on Surface Films of W-S-Cu Cluster Compounds on Copper
Authors: Xiangrong Ye , Xinquan Xin , Hammer C. F.
Published: May 2005

Conversion films of W-S-Cu cluster compounds with a metallic luster of various shades and colors have been applied to a copper surface by the interface reaction between WS2–4 and the Cu2O layer due to the formation of W-S-Cu bonds; their colors have been changed by heating treatment. FT-IR, XPS, and AES determinations were carried out, and the results show that W-S-Cu, terminal W-S, and terminal W-O bonds exist in the cluster films. The films are composed of the elements W, S, Cu, and O, the valences of those elements being +6, −2, +1, and −2, respectively. The films are all multimolecular layers and can be described as an overlapping double-layer structure. The outer (upper) layer has been oxidized to some extent. WS2 clusters remain in the inner (lower) layer. As for the heated films, they are also composed of W, S, Cu, and O, but the content, distribution, and valence state of each element and the structure of the films change. The first layer of the heated films is largely composed of CuO. The second is a mixture of CuO and Cu2O. The third is an intermediate layer. The fourth is composed of W, S, Cu, and O; the valence of W remains ambiguous, while the other three are −2, +1, and −2, respectively. WS2 units survive the heating in this layer. There is still another intermediate layer between the whole film and the copper surface confirming the penetration of tungsten and sulfur. The colors of the unheated and the heated films are probably caused by W-S-Cu bonds and a statistical distribution and overlapping of various molecular layers since the films are complicated multicomponent and multilayer systems. The disparity of colors before and after heating treatment is caused by the change of composition and structure of the films.
FT-IR Solution Spectra of Propyl Sulfide, Propyl Sulfoxide, and Propyl Sulfone
Authors: Staggs R. Louis , Lyon William G.
Published: May 2005

FT-IR spectra were obtained of 0.5% volumetric solutions of propyl sulfide, propyl sulfoxide, and propyl sulfone in hexane, CCl4, CS2, and CHCl3 to assist in the assignment of FT-IR-PAS spectra of propyl sulfoxide sorbed within the structure of several peats and onto cellulose. The C-H stretching bands of all three compounds showed a 10-fold larger solvent sensitivity than did analogous aliphatic bands in a comparable series of n-alkanes in solution. The S=O stretching bands of alkyl sulfoxides are known to be quite sensitive to solvent environments because of donor-acceptor interactions involving the oxygen of the sulfoxide group and the slightly acidic protons of generalized organic acids; the expected decreases in frequency were seen with propyl sulfoxide and acidic solvents like chloroform. The frequencies of asymmetric and symmetric stretching vibrations of the -SO2 group of propyl sulfone both exhibit smaller decreases in Old, than does the sulfoxide S=O stretching vibration.
Characterization of Matrix-Assisted Laser Desorption Based on Absorption and Acoustic Monitoring
Authors: Preisler Jan , Yeung Edward S.
Published: May 2005

Conventional methods for studying matrix-assisted desorption-ionization rely on mass spectroscopy. In this study, a 488-nm argon-ion laser beam is deflected by two acoustooptic deflectors to image plumes desorbed at atmospheric pressure via absorption. All species, including neutral molecules, are monitored. Interesting features, e.g., differences between the initial plume and subsequent plumes desorbed from the same spot, or the formation of two plumes from one laser shot, are observed. Total plume absorbance can be correlated with the acoustic signal generated by the desorption event. A model equation for the plume velocity as a function of time is proposed. Optical probing also enables accurate determination of plume velocities at reduced pressures. These results define the optimal conditions for desorbing analytes from matrices, as opposed to achieving a compromise between efficient desorption and efficient ionization as is practiced in mass spectrometry.
Zeolite Slurry Analysis Using Freon-Assisted Graphite Furnace Vaporization for Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Alary Jean-François , Hernandez Genaro , Salin Eric D.
Published: May 2005

Halogen-assisted electrothermal vaporization (ETV) was used as a sample introduction mechanism for inductively coupled plasma atomic emission spectrometry. Freon-12™ was used as a gas-phase halogenation reagent in the ETV graphite furnace to enhance vaporization of carbide-forming elements by converting them into metal halides. With Freon ETV, detection levels for Zn, Pb, Cd, Mn, V, Cu, Ti, and Ca were lower than those obtained with conventional nebulization of liquid standards. A zeolite sample was analyzed for the refractory elements chromium and vanadium. Without Freon, the signals for these elements were very low; however, with Freon, the signals were dramatically improved. Detection limits of 1.4 μg/g and 0.3 μg/g, respectively, were obtained for these elements. A sheathing and cooling gas flow was introduced to reduce analyte vapor condensation on tubing walls and to promote aggregate formation. This additional flow enhanced the quality of signal with the zeolite but proved to be detrimental for the determination of refractory elements in liquid standards with or without halogenation. The precision of determination for the zeolite sample varied from 3% for cadmium, to 6% for lead.
Assignment of N=N Vibrational Frequencies and Tautomeric Effects in the Vibrational Spectra of 1-Aryl-3-alkyl-3-hydroxy-triazenes and Their Platinum Complexes
Authors: Scholz A. , Wokaun A.
Published: May 2005

The vibrational frequencies of the N=N stretching mode of 1-aryl-3-alkyl-3-hydroxy-triazenes and their platinum complexes (PtL4; L = triazene) were investigated by FT-IR and FT-Raman spectroscopy. The influence of electron-donating or -withdrawing substituents on the phenyl ring and of different alkyl substituents at the N3 atom on these frequencies was considered. The N=N vibrational frequency is significantly lowered (as a result of the delocalization of the N=N bond over three nitrogen atoms) compared to related compounds. The Pt complexes show a reduced intensity and an increased linewidth in the vibrational spectra. Additionally, the NMR spectra of the 1-aryl-3-alkyl-3-hydroxy-triazenes were recorded in order to show the tautomeric structure of these substances. The hydroxy triazenes preferentially exist in the N1H form. As a consequence, the N=N stretching frequencies of the hydroxy triazenes appear to be influenced by the superposition of two counteracting effects, the delocalization of the N=N bond and tautomerism.
Determination of Petroleum Properties by Fiber-Optic Fourier Transform Raman Spectrometry and Partial Least-Squares Analysis
Authors: de Bakker Christopher J. , Fredericks Peter M.
Published: May 2005

The petroleum products unleaded gasoline and reformate have been analyzed by Fourier transform (FT) Raman spectrometry with the use of a fiber optic cable that allows a measurement to be carried out remotely from the spectrometer. Samples were contained in glass cuvettes, and collection of high-quality spectra was simple. Fuel properties such as research octane number (RON), motor octane number (MON), density, benzene content, and flexible volatility index (FVI) were determined by application of the partial least-squares multivariate statistical approach. Analytically useful calibrations ( R2 > 0.97) were obtained for all of the significant fuel properties studied. Cross-validation results were, as expected, worse than the calibration results but still indicated the usefulness of the method. Standard errors of prediction with the use of cross validation for models that contained 14–28 samples include: MON = 0.12, RON = 0.16, benzene % = 0.09, and density = 0.0018. These results demonstrate that it is feasible to undertake on-line analyses of petroleum fuels by fiber-optic FT-Raman spectrometry.
Evaluation of External-Cavity Diode Lasers for Raman Spectroscopy
Authors: Cooney Thomas F. , Skinner H. Trey , Angel S. M.
Published: May 2005

We have evaluated the suitability of two commercial external-cavity, tunable diode lasers (tuning range approximately 770–800 nm) for use as Raman excitation sources. The tests consisted of relatively long-term (up to 14 h) measurements of wavelength and power stability as well as measurements of reproducibility of emission wavelength during repeated on/off cycling. We find that, for both tested lasers, the external cavity configuration either eliminates or dampens “mode-hopping” and wavelength drift to a level suitable for obtaining good-quality Raman spectra in most routine experiments. Over the course of several hours, wavelength change from both mode-hopping and drift is less than approximately 0.05 nm for the New-Focus laser and 0.07 nm for the SDL laser. Reproducibility over several on/off cycles is of the same order of magnitude. In all cases, resolution measurements were limited by the spectrographs.
Determination and Use of Secondary Infrared Intensity Standards
Authors: Bertie John E. , Zhang Shuliang L. , Jones R. Norman , Apelblat Yoram , Keefe C. Dale
Published: May 2005

The presentation of absorption intensities in infrared spectra is usually limited to relative intensities instead of absolute intensities. The measurement of absolute intensities can be facilitated by the use of secondary intensity standards. Such standards have been accepted by the Commission on Molecular Structure and Spectroscopy and the Physical Chemistry Division of the International Union of Pure and Applied Chemistry and were published recently. The secondary standards are based on the complex refractive index and molar absorption coefficient spectra of benzene, chlorobenzene, toluene, and dichloromethane. They have been used in this laboratory to calibrate the effective pathlength of a transmission cell and the effective number of reflections in a Circle® multiple attenuated total reflection cell. A computer program, IRYTRUE, has been developed to standardize the routine use of these intensity standards to calibrate the effective pathlength of a transmission cell. The program has been used to calibrate three transmission cells. The agreement between the calibrated values of the effective pathlength obtained from the use of different standard band groups was determined. The calibrated cell pathlength agrees with that calculated from the interference fringe pattern of the empty cell within 3% for very thin cells and within 1% for cells thicker than 100 μm. We propose that the effective pathlength evaluated in this manner be called the cell constant, and that this cell constant be used in place of the pathlength in quantitative infrared analysis. The calibration of multiple attenuated total reflection measurements in the Circle cell has been achieved in two ways: by the use of peak heights and by the use of areas. Programs PCCALC and CIRCLCAL and its associated program RSCALC are described for this purpose. The intensity standards allow one to measure absolute infrared absorption intensities of liquids with confidence to an estimated accuracy of 2–3% by either transmission or calibrated ATR methods.
Pulse-Induced Thermal Lensing in Kerr Media
Authors: Kozich Valery P. , Hernández Florencio E. , Aristides Marcano O.
Published: May 2005

The thermal lens effect induced by nanosecond laser pulses in a media having large Kerr nonlinearity is studied. It is shown that thermal lensing is affected by pump-beam self-focusing due to the Kerr nonlinearity, which increases the sensitivity of the thermal lens technique to detect small linear or nonlinear absorption.
Silicon Substrate Microelectrode Array for Surface-Enhanced Raman Spectroscopy
Authors: Zhelyaskov Valentin R. , Milne Elizabeth T. , Hetke Jamille F. , Morris Michael D.
Published: May 2005

Electrode sites of a photolithographically fabricated microelectrode array have been demonstrated to function as surface-enhanced Raman Spectroscopy (SERS) microelectrodes. The 5 × 15 μm iridium electrodes on the substrate are electroplated with silver and activated by standard procedures. Working and counter-electrode functions are integrated onto the same assembly. The electrode is shown to yield adenosine and pyridine spectra at low concentrations and submilliwatt laser power.
Studies of Chiral Modifiers on γ-Cyclodextrin-Pyrene Complexes Using Fluorescence Lifetime Measurements
Authors: Will A. Yvette , Schuette-Parsons Jodi M. , Agbaria Rezik A. , Warner Isiah M.
Published: May 2005

This work focuses on the inclusion complexes of γ-cyclodextrin and pyrene as indicated by fluorescence lifetime analyses and the influences of chiral alcohols and diols on these complexes. The 2-butanol participates in the γ-cyclodextrin-pyrene complexation and produces a longer lifetime of complexed pyrene than the value determined for the complex in pure water. The enantiomeric 1,3-butanediol also produces a longer lifetime of complexed pyrene. However, a decrease in this lifetime is observed in the presence of racemic 1,3-butanediol. This study also involves an estimation of formation constants for γ-cyclodextrin-pyrene complexes by use of the fluorescence lifetime measurements.
Wavelength Calibration Method for a CCD Detector and Multichannel Fiber-Optic Probes
Authors: Cho Junghwan , Gemperline Paul J. , Walker Dwight
Published: May 2005

A wavelength calibration method for a charge-coupled device (CCD) array detector and seven-channel fiber-optic spectrograph is described. The method was developed for the extraction of wavelength-calibrated spectra for in situ dissolution testing of tablets. The method includes automatic recognition of the positions of the seven fiber channels and recognition of mercury line positions in pixel numbers. A wavelength calibration model with two trigonometric terms was used for least-squares fitting of horizontal pixel numbers to the known wavelengths of five lines from a low-pressure mercury discharge lamp. Four other models were used for comparison. The standard error of estimate (SEE) was minimum for the model with two trigonometric terms. Each fiber channel was calibrated separately. After least-squares fitting, linear interpolation was used to obtain the wavelength-calibrated spectra in the range of 190–450 nm at 1-nm intervals. With this method, spectra from seven fiber-optic probes can be acquired simultaneously and rapidly for in situ dissolution testing. The wavelength calibration procedure is good enough to permit solution spectra acquired on one channel to be used for multivariate calibration of the other channels under appropriate circumstances.
Application of a Poly(Hexafluoropropyl-Co-Tetrafluoroethylene) Thin-Film Architecture for Aqueous O2 Quantification
Authors: Li Ming , Pacholski Michaeleen L. , Bright Frank V.
Published: May 2005

Compared to electrochemical methodologies, detection and quantification of O2 with optical means has been regarded as more advantageous. Among the optical approaches that have been exploited, fluorescence quenching schemes have attracted significant attention. More recently, several authors have used time-resolved fluorescence in concert with quenching schemes to sense O2. We report a new quenching-based architecture to detect dissolved O2 in water. The system is composed of a fluoropolymer film, namely) (FEP), that has been subjected to a radio-frequency glow discharge plasma to introduce -OH groups, modified further with aminopropyl-triethoxysilane (APS) to produce an aminated surface, and subsequently reacted with an activated pyrene (Py) residue to form FEP-APS-Py. In a sample cell configuration this system exhibits a sensitivity to aqueous O2 as high as 863 ± 28 M−1 and a detection limit on the order of 10 μM O2. If β-cyclodextrin is added to the aqueous solution, the sensitivity to O2 is enhanced further. Slow time-dependent reconfiguration of the FEP-APS-Py surface is the major drawback of this system.
Methylated Purines in Urinary Stones
Authors: Safranow Krzysztof , Machoy Zygmunt
Published: May 2005

Background: The aim of the study was to measure the content of methylated purines that appear as admixtures in uric acid stones.

Methods: We analyzed urinary calculi from 48 residents of Western Pomerania who underwent surgery at the urology ward in Szczecin. Stone samples were dissolved in 0.1 mol/L NaOH. Extracts were diluted in 50 mmol/L KH2PO4 and analyzed by reversed-phase HPLC with ultraviolet detection and use of a gradient of methanol concentration and pH.

Results: Uric acid was the main component of 9 stones. All 9 showed admixtures of 9 other purine derivatives: endogenous purine breakdown products (xanthine, hypoxanthine, and 2,8-dihydroxyadenine) and exogenous methyl derivatives of uric acid and xanthine (1-, 3-, and 7-methyluric acid; 1,3-dimethyluric acid; and 3- and 7-methylxanthine). Amounts of these purine derivatives ranged from the limit of detection to 12 mg/g of stone weight and showed a strong positive correlation (Spearman rank correlation coefficients, 0.63–0.94) with the uric acid content of the samples. The main methylated purine in the stones was 1-methyluric acid.

Conclusions: Urinary purines at concentrations below their saturation limits may coprecipitate in samples supersaturated with uric acid and appear as admixtures in urinary stones. The amount of each purine depends on its average urinary excretion, similarity to the chemical structure of uric acid, and concentration of the latter in the stone. These findings suggest that purines in stones represent a substitutional solid solution with uric acid as solvent. Methylxanthines, which are ubiquitous components of the diet, drugs, and uric acid calculi, may be involved in the pathogenesis of urolithiasis.
Die selbstverteilende virtuelle Maschine SDVM (Self Distributing Virtual Machine (SDVM))
Authors: Haase Jan , Eschmann Frank , Waldschmidt Klaus
Published: May 2005

Die Self Distributing Virtual Machine (SDVM) ist eine Middleware, die beliebige Standard-Rechner zu einem parallelen Rechnercluster verbindet. Die an der SDVM teilnehmenden Rechner können verschieden leistungsfähig sein und unter verschiedenen Betriebssystemen laufen. Ebenso kann die Netzwerktopologie beliebig gewählt werden und sich auch während der Laufzeit ändern. Die SDVM unterstützt dynamisches An- und Abmelden von Sites, sodass sich der Cluster während der Laufzeit vergrößern oder verkleinern kann. Außer dem SDVM-Daemon benötigen Rechner keine weiteren Voraussetzungen und können sich direkt in den SDVM-Cluster einfügen. Die SDVM besitzt eine automatische Verteilung von Daten und Instruktionsblöcken auf die teilnehmenden Sites, sowie einen dezentralen Scheduler. Aufgrund des Ausführungsparadigmas der SDVM können Applikationen ohne Änderungen auf beliebigen Cluster-Konfigurationen genutzt werden. Das Konzept der SDVM ist ebenfalls besonders für eng gekoppelte Systeme wie beispielsweise Multi-Prozessor-Systeme oder Systems-on-Chip (SoC) geeignet, kann aber auch für den Bereich des Grid Computing erweitert werden. Dieser Artikel beschreibt die Eigenschaften und die Struktur der SDVM.
Strukturierte Lehr- und Lernmodelle für die Ausbildung im Fachgebiet Technische Informatik (Structured Educational Models for Computer Engineering)
Authors: Lucke Ulrike , Nölting Kristin , Tavangarian Djamshid
Published: May 2005

Bewährte Entwurfsmechanismen für Rechentechnik weisen einen hohen Strukturierungsgrad auf. Zentrale, bleibende Anteile werden als fest verdrahtete Hardware realisiert, während dynamische Anteile rekonfigurierbar gestaltet werden. Modularität und Interoperabilität der Komponenten spielen dabei eine wichtige Rolle. Der Entwurfsprozess setzt Technologie-unabhängig auf einem hohen Abstraktionsniveau an. Der Artikel zeigt an aktuellen eLearning-Angeboten, wie diese Erfahrungen auf die Lehre übertragen werden können.
Transregional Collaborative Research Center SFB/TR 8 Spatial Cognition: Reasoning, Action, Interaction (Sonderforschungsbereich/Transregio SFB/TR 8 Raumkognition: Schließen, Handeln, Interagieren)
Authors: Barkowsky Thomas , Bateman John , Freksa Christian , Burgard Wolfram , Knauff Markus
Published: May 2005

Summury

The Transregional Collaborative Research Center SFB/TR 8 Spatial Cognition was established by the German Science Foundation (DFG) at the Universities of Bremen and Freiburg in January 2003. 13 Research projects pursue interdisciplinary research on intelligent spatial information processing. This article introduces the research field of spatial cognition and reports on aspects from cognitive psychology, cognitive robotics, linguistics, and artificial intelligence.
Effects of dietary vitamin A intake on acrosin- and plasminogen-activator activity of ram spermatozoa
Authors: Zervos I A , Tsantarliotou M P , Vatzias G , Goulas P , Kokolis N A , Taitzoglou I A
Published: May 2005

Acrosin and plasminogen activators are proteolytic enzymes of ram spermatozoa that play an essential role in the induction of the acrosome reaction, as well as the binding of spermatozoa to the oocyte and their penetration through the layers that surround the oocyte. Since vitamin A can alter gene expression in various tissues, testis included, this study was undertaken to evaluate the possible effect of vitamin A intake on acrosin- and plasminogen-activator activity. During a 20-week experiment, 15 rams of the Greek breed Karagouniki, divided to three groups, received different amounts of vitamin Aper osin retinyl acetate capsules (group A, controls, 12 500 iu/animal per day; group B, 50 000 iu/animal per day; group C, 0 iu/animal per day up to the 13th week, then 150 000 iu/animal per day until the end of the experiment). Acrosin- and plasminogen-activator activity were determined by spectrophotometric methods. Vitamin A was determined in blood plasma by HPLC. No statistical differences were detected regarding the body weight of the rams or the qualitative and quantitative parameters of their ejaculate throughout the whole experiment. No statistically significant alterations of enzyme activity were detected in group B. In group C, both enzyme activities started declining in week 9. Compared with controls, maximum reduction for acrosin was 49% on week 11 and for plasminogen activators 51% in week 14. Activities returned to normal rates after vitamin A resupplementation. To date, the main result of vitamin A deficiency was known to be arrest of spermatogenesis and testicular degeneration. A new role for vitamin A may be suggested, since it can influence factors related to male reproductive ability before spermatogenesis is affected.
Effect of cryopreservation on the cellular integrity of equine embryos
Authors: Tharasanit T , Colenbrander B , Stout T A E
Published: May 2005

Horse embryos are rarely cryopreserved in practice because expanded blastocysts tolerate freezing poorly, and the embryo begins expanding very soon after entering the uterine cavity. This study examined the effects of freezing on cytoskeleton integrity, and investigated whether cell damage could be reduced using trypsin to thin the blastocyst capsule or cytochalasin-B (cyto-B) to stabilise the cytoskeleton. Sixty-nine embryos were recovered 7 days after ovulation and equilibrated in 10% glycerol, with or without pretreatment with 0.2% trypsin or 7.5 μg/ml cyto-B. Forty-two of the embryos were frozen; the rest were used to determine whether pre-freezing treatment alone caused cell damage. Subsequently, embryos were stained with 4′,6-diamidino-2-phenylindole dihydrochloride, to identify dead cells, and fluorescently labelled phalloidin, to assess cytoskeleton quality. Without freezing, none of the treatments affected cell viability. And although Cyto-B altered actin distribution, the cytoskeleton returned to normal during a 4-h culture. Following cryopreservation, the percentage of dead cells (11.1 ± 1.3%) did not differ between treatments (P > 0.05), but significantly fewer cells died in small (≤300 μm) than in large embryos when neither pretreatment was used (P > 0.05); the effect of embryo size was, however, not significant after pretreatment with trypsin or cyto-B, and trypsin improved the likelihood of an intact cytoskeleton post thaw. However, trypsin treatment also resulted in a ‘sticky’ capsule that complicated embryo handling, and cyto-B-induced actin-depolymerisation was not reversed during a 6-h post-thaw incubation. Thus, while trypsin pretreatment improved cytoskeleton preservation and both trypsin and cyto-B may reduce cell death during cryopreservation of large embryos, both treatments induced other changes likely to compromise embryo survival.
An Overview on the Generation of BAC Transgenic Mice for Neuroscience Research
Authors: Yang X. William , Gong Shiaoching
Published: May 2005

This unit provides a comprehensive overview on the generation of transgenic mice using bacterial artificial chromosomes (BACs), and the application of BAC transgenic mice in neuroscience research. In the first section, advantages of the BAC transgenic approach compared to the conventional transgenic approach are summarized. In the second section, important considerations in designing BAC transgenic constructs are outlined. Four commonly used BAC transgenic construct designs are also outlined. Concepts of modifying BACs by homologous recombination in E. coli to introduce a variety of mutations into BACs, and important steps to characterize a modified BAC prior to the generation of transgenic mice are also presented. In the final section, some of the important applications of BAC transgenic mice in neuroscience research, including studying gene expression, gene function, mapping neuronal circuitry, and modeling human diseases, are described.
Modification of Bacterial Artificial Chromosomes (BACs) and Preparation of Intact BACDNA for Generation of Transgenic Mice
Authors: Gong Shiaoching , Yang X. William
Published: May 2005

BAC transgenesis is a powerful tool for the study of gene expression and gene function in the mouse in vivo. In this unit, detailed protocols are provided for modification (i.e., marker gene insertion, deletion, or point mutation) of BACs by homologous recombination in E. coli. This method utilizes a shuttle vector that allows transient expression of the E. coli RecA gene to support homologous recombination in the BAC host bacteria. In addition, two protocols are provided for purification of BAC DNA for microinjection to generate transgenic mice. Since BAC DNA is prone to degradation, which may introduce positional effects in transgenic mice, two methods are given for purification of intact BAC DNA for subsequent microinjection.
Rule Out (R/O) Vasculitis
Authors: Thibodeau Steven , Grant Ellen , Schaefer Pamela W.
Published: May 2005

When imaging patients for vasculitis, the goals are: (1) to determine if there is evidence of acute or subacute cerebral injury and (2) to assess the contour of the major intracranial arteries. An additional but still experimental goal is (3) to determine if there are areas of altered perfusion that suggest active small vessel disease. Standard MR images and diffusion‐weighted imaging are used to detect and determine the age of parenchymal lesions. The 3‐D TOF MRA helps evaluate the large and medium vessels. Perfusion‐weighted imaging may detect regions of altered relative blood flow and blood volume. This unit contains a basic protocol for the evaluation of stable patients as well as an alternative protocol for unstable patients.
Rule Out (R/O) Migraine
Authors: Thibodeau Steven , Grant Ellen
Published: May 2005

When imaging patients with headaches, the goals are: (1) to rule out a more ominous etiology for their headaches and (2) to assess the degree of hemodynamic and parenchymal involvement when atypical or complicated migraine is suspected. The standard images allow other etiologies, such as mass lesions, to be excluded and an MR venogram can rule out venous sinus thrombosis. Contrast may be helpful in differentiating multiple small metastases, demylinating lesions with inflammatory components, and subcortical infarcts from the nonspecific foci of increased T2 associated with migraines that do not enhance. Perfusion‐weighted imaging allows detection assessment of hemodynamic compromise. Diffusion‐weighted imaging, in combination with the standard MR images, allows assessment of parenchymal involvement. This unit contains a basic protocol which can be used for the evaluation of patients as well as an alternative protocol for the assessment of cerebral perfusion in patients with visual auras.
Signal Detection
Authors: Cheng Yu‐Chung Norman , Haacke E. Mark
Published: May 2005

The bulk magnetization represents the equilibrium value of the magnetization when all spins have aligned themselves parallel to the main field. When this magnetization is tipped into the transverse plane, it precesses about the main field. This precession generates a changing flux through the face of an appropriately placed coil inducing an electromotive force (emf) in the coil. The measured signal is proportional to the induced emf. This unit discusses the basic physics behind detecting MR signal. The process of calculating induced emf based on Faradays law of induction is explained.
Phase Dependence on Motion
Authors: Cheng Yu‐Chung Norman , Haacke E. Mark
Published: May 2005

This unit introduces the sources of variable phase in the presence of motion. The sources of these phase changes can come from the read gradient, from the slice select gradient and from the phase encoding gradient. Motion during the gradient moves the spin from one location to another and, therefore, changes the effective field it sees. This field change leads to a frequency change in time during either the dephasing or rephasing gradient or both. As a result, the spins do not refocus at the expected time.
Recombineering: Genetic Engineering in Bacteria Using Homologous Recombination
Authors: Thomason Lynn , Court Donald L. , Bubunenko Mikail , Costantino Nina , Wilson Helen , Datta Simanti , Oppenheim Amos
Published: May 2005

The bacterial chromosome and plasmids can be engineered in vivo by homologous recombination using PCR products and synthetic oligonucleotides as substrates. This is possible because bacteriophage‐encoded recombination functions efficiently recombine sequences with homologies as short as 35 to 40 bases. This recombineering allows DNA sequences to be inserted or deleted without regard to location of restriction sites. This unit first describes preparation of electrocompetent cells expressing the recombineering functions and their transformation with double‐stranded DNA (dsDNA) or single‐stranded DNA (ssDNA). Support protocols describe a two‐step method of making genetic alterations without leaving any unwanted changes, and a method for retrieving a genetic marker (cloning) from the E. coli chromosome or a coelectroporated DNA fragment and moving it onto a plasmid. A method is also given to screen for unselected mutations. Additional protocols describe removal of defective prophage, methods for recombineering.
Basic Protein Sequence Analysis
Authors: Krishnamurthy Nandini , Sjölander Kimmen V.
Published: May 2005

Prediction of molecular function of proteins has become an important task in the genomics era. A wide variety of sequence analysis tools are available to biologists for this task. We have selected one or two primary protocols for tasks such as domain detection, subcellular localization, and motif detection. We also present a strategy for integration of results from different protocols. All the resources needed for these protocols are accessible via publicly available Web servers and databases and require little or no computational expertise.
Analysis of Protein Co‐Occupancy by Quantitative Sequential Chromatin Immunoprecipitation
Authors: Geisberg Joseph V. , Struhl Kevin
Published: May 2005

Sequential Chromatin Immunoprecipitation (SeqChIP) is a powerful technique for analyzing the simultaneous association of two different proteins with genomic DNA sequences in vivo. Cellular Protein‐DNA complexes are cross‐linked with formaldehyde (UNIT ), and are purified via two successive immunoprecipitations, with each immunoprecipitation targeting a different protein. Protein‐DNA cross‐links are then reversed and DNA sequences of interest are analyzed by quantitative PCR. At each genomic region, calculated SeqChIP co‐occupancy values are compared to occupancy values of singly immunoprecipitated samples. The extent of enrichment brought about by the second immunoprecipitation relative to the singly immunoprecipitated sample is directly correlated with the degree of co‐occupancy between the two proteins at the genomic location assayed. In principle, the technique is not limited to Saccharomyces cerevisiae. Cells from a wide variety of organisms can be used.
Measurement of Cytokine Production Using Whole Blood
Authors: Thurm Cary W. , Halsey John F.
Published: May 2005

Whole blood (WB) ex vivo stimulation assays are useful for measuring cytokine responses due to the easy access of samples from healthy donors and patients and the minimal processing of the sample required. Because the assay mimics the natural environment, WB culture may be the best milieu in which to study cell activation and cytokine production in vitro. Whole blood stimulation has been used to investigate the cellular responsiveness to a variety of stimuli, including bacterial endotoxin (LPS), antigens, allergens, and antibiotics. Various clinical uses of whole blood stimulation assays have been suggested, including the assessment of autoimmune diseases, the monitoring of drug and vaccine efficacy, and immunotoxicity. Thus, whole blood cell culture may be useful in studying the biological effects of potential allergenic and/or antigenic substances or drugs on immune cell activation and cytokine secretion.
Sources and Methods for Obtaining Stem and Progenitor Cells
Authors: Donahue Robert E. , Kuramoto Ken , Dunbar Cynthia E.
Published: May 2005

Extrapolation of an understanding regarding hematopoiesis and, in particular, hematopoietic stem cells (HSCs) from rodent models or in vitro human cell models to applications in humans has proven very difficult. This is not surprising, given the differences between rodent and human hematopoietic physiology and the lack of true in vitro assays for HSCs. Therefore, translational preclinical development of genetic and cellular therapies is dependent on the utilization of practical and well‐defined large animal models. This chapter will introduce the most commonly used model species, including macaques, baboons, dogs, cats, and sheep, and explain the particular advantages and limitations of each. Specific protocols for the support of macaques through ablative cell and gene therapy procedures will be included to introduce investigators to the types of resources and support required to maintain a large animal facility dedicated to high‐intensity experimentation, and also to introduce investigators to the types of procedures that are possible.
Isolation of Prolymphocytes from Bone Marrow and Fetal Liver
Authors: Kouro Taku , Yokota Takafumi , Welner Robert , Kincade Paul W.
Published: May 2005

Isolation of the lymphoid progenitors in their earliest stage of development is indispensable for understanding when and how hematopoietic cell lineages are committed. Recently developed immunofluorescent labeling and sorting has made it possible to identify and isolate rare progenitors of lymphocytes. In this unit, protocols for isolating lymphoid progenitors from three different sources are provided. These protocols are based on stepwise purification consisting of magnetic and fluorescence‐activated cell sorting techniques, optimized according to the nature of progenitors in each organ. Isolated progenitors may be analyzed in the lymphocyte differentiation cultures described in the following units and are useful for in vivo transfer experiments or microarray assays for gene expression.
In Vitro Differentiation and Measurement of B Cell Progenitor Activity in Culture
Authors: Kouro Taku , Yokota Takafumi , Welner Robert , Kincade Paul W.
Published: May 2005

As well as other blood cells, B lymphocytes originate from hematopoietic stem cells. However, it is not fully understood how their production is controlled. In the serum‐free, stromal‐cell‐free B cell differentiation culture described here, early steps of the B lineage differentiation process are reproduced under defined conditions. This assay is useful for examining the direct effects of various soluble factors on B cell progenitors because it does not contain stromal cells or unknown factors. Additionally, this assay yields sufficient cloning to measure B cell progenitors from single cell cultures. Stromal cell coculture assays are also described that cover a wider category of precursors such as human B cell progenitors.
Measurement of Natural Killer Cell Progenitor Activity in Culture
Authors: Kouro Taku , Yokota Takafumi , Welner Robert , Kincade Paul W.
Published: May 2005

Natural killer cells are morphologically related to and have progenitors in common with B and T lymphocytes. In this unit, protocols describe how to induce natural killer cell differentiation from prolymphocytes. Since NK cell differentiation cultures also support B cell differentiation, this protocol is extremely useful for seeking the B and NK cell branch point in their differentiation pathway.
Responses of plant functional types to an environmental gradient on the Northeast China Transect
Authors: Wang Guo‐Hong , Ni Jian
Published: May 2005

The hypothesis that some plant traits such as life form are robust surrogates for plant functional type (PFT) has provoked an ongoing debate. Based on a dataset from the Northeast China Transect (NECT), we attempted to test the hypothesis by comparing an objective PFT identification framework in which large datasets of plant traits were considered with two subjective PFT frameworks in which only a few plant traits were involved. Additionally, we addressed the relations between the relative abundance of PFTs and the environmental gradient represented by actual evapotranspiration (AET) along the NECT. We also discuss the changes in ecosystem functioning associated with the PFT turnover along the environmental gradient. Based on an objective PFT classification, eight PFTs were identified: deciduous trees, shrubs, perennial forbs with lower net photosynthesis, perennial forbs with higher net photosynthesis, perennial bulb‐grasses, perennial tiller‐grasses, annual C4 herbs and evergreen trees. Our results indicated that some plant traits, such as life form and photosynthesis pathway, are robust surrogates for PFTs, implying that subjective approaches to PFT classification are useful. Nonetheless, caution should be used during the classification of PFTs. The framework adopted for PFT classification should depend on the specific scientific issues being dealt with. It is therefore meaningless to pursue a general framework for the identification of PFTs even within given plant communities. On the other hand, our quantitative classification of PFTs confirmed recurrent patterns with respect to PFT turnover along an environmental gradient. Furthermore, with the turnover in PFT along the NECT from the west to the east, ecosystem properties such as productivity and carbon storage are predicted to decrease, while photosynthesis is predicted to increase, suggesting that PFT turnover would inevitably lead to changes in ecosystem functioning.
ON SOME NORMING PROPERTIES OF SUBFACTORS
Authors: Pop Florin
Published: May 2005

We investigate the role of projections in norming a $C^*$-algebra by a type II1 subfactor. Applications are given for factors with property $\varGamma$ and for free-product factors.
SOME DUALITY CONJECTURES FOR FINITE GRAPHS AND THEIR GROUP THEORETIC CONSEQUENCES
Authors: Gersten S. M. , Riley T. R.
Published: May 2005

We pose some graph theoretic conjectures about duality and the diameter of maximal trees in planar graphs, and we give innovations in the following two topics in geometric group theory, where the conjectures have applications.

Central extensions. We describe an electrostatic model concerning how van Kampen diagrams change when one takes a central extension of a group. Modulo the conjectures, this leads to a new proof that finitely generated class $c$ nilpotent groups admit degree $c+1$ polynomial isoperimetric functions.

Filling functions. We collate and extend results about interrelationships between filling functions for finite presentations of groups. We use the electrostatic model in proving that the gallery length filling function, which measures the diameter of the duals of diagrams, is qualitatively the same as a filling function DlogA, concerning the sum of the diameter with the logarithm of the area of a diagram. We show that the conjectures imply that the space-complexity filling function filling length essentially equates to gallery length. We give linear upper bounds on these functions for a number of classes of groups including fundamental groups of compact geometrizable 3-manifolds, certain graphs of groups, and almost convex groups. Also we define restricted filling functions which concern diagrams with uniformly bounded vertex valence, and we show that, assuming the conjectures, they reduce to just two filling functions—the analogues of non-deterministic space and time.
THREE POSITIVE SOLUTIONS FOR A CLASS OF ELLIPTIC SYSTEMS IN ANNULAR DOMAINS
Authors: Marcos do Ó João , Lorca Sebastián , Ubilla Pedro
Published: May 2005

In this paper we study the existence and multiplicity of positive radial solutions for a class of semilinear elliptic systems in bounded annular domains with non-homogeneous boundary conditions by the use of a fixed-point theorem of cone expansion/compression type.
ON THE BEHAVIOUR OF THE OSCILLATORY SOLUTIONS OF SECOND-ORDER LINEAR UNSTABLE TYPE DELAY DIFFERENTIAL EQUATIONS
Authors: Philos Ch. G. , Purnaras I. K. , Sficas Y. G.
Published: May 2005

Second-order linear (non-autonomous as well as autonomous) delay differential equations of unstable type are considered. In the non-autonomous case, sufficient conditions are given in order that all oscillatory solutions are bounded or all oscillatory solutions tend to zero at $\infty$. In the case where the equations are autonomous, necessary and sufficient conditions are established for all oscillatory solutions to be bounded or all oscillatory solutions to tend to zero at $\infty$.
MULTIVARIATE SAMPLING THEOREMS ASSOCIATED WITH MULTIPARAMETER DIFFERENTIAL OPERATORS
Authors: Annaby M. H.
Published: May 2005

We investigate the multivariate sampling theory associated with multiparameter eigenvalue problems. A several-variable counterpart of the classical sampling theorem of Whittaker, Kotel’nikov and Shannon is given. It arose when the multiparameter system has order one. Two-dimensional sampling theorems associated with two-parameter systems of second-order differential operators will be established. The sampling formulae are of multivariate non-uniform Lagrange interpolation type. Unlike many of the known formulae, the interpolating functions are not necessarily products of single variable functions.
CLASSIFICATION OF LAGRANGIAN SURFACES OF CONSTANT CURVATURE IN THE COMPLEX EUCLIDEAN PLANE
Authors: Chen Bang-Yen
Published: May 2005

One of the most fundamental problems in the study of Lagrangian submanifolds from a Riemannian geometric point of view is the classification of Lagrangian immersions of real-space forms into complex-space forms. In this article, we solve this problem for the most basic case; namely, we classify Lagrangian surfaces of constant curvature in the complex Euclidean plane $\mathbb{C}^2$. Our main result states that there exist 19 families of Lagrangian surfaces of constant curvature in $\mathbb{C}^2$. Twelve of the 19 families are obtained via Legendre curves. Conversely, Lagrangian surfaces of constant curvature in $\mathbb{C}^2$ can be obtained locally from the 19 families.
INVARIANT SUBSPACES AND HANKEL-TYPE OPERATORS ON A BERGMAN SPACE
Authors: Nakazi Takahiko , Osawa Tomoko
Published: May 2005

Let $L^{2}=L^{2}(D,rdrd\theta/\pi)$ be the Lebesgue space on the open unit disc $D$ and let $L_{a}^2=L^{2}\cap\mathrm{Hol}(D)$ be a Bergman space on $D$. In this paper, we are interested in a closed subspace $\mathcal{M}$ of $L^{2}$ which is invariant under the multiplication by the coordinate function $z$, and a Hankel-type operator from $L_{a}^2$ to $\mathcal{M}^\bot$. In particular, we study an invariant subspace $\mathcal{M}$ such that there does not exist a finite-rank Hankel-type operator except a zero operator.
HOMOGENEOUS RIEMANNIAN STRUCTURES ON BERGER 3-SPHERES
Authors: Gadea P. M. , Oubiña J. A.
Published: May 2005

The homogeneous Riemannian structures on the three-dimensional Berger spheres, their corresponding reductive decompositions and the associated groups of isometries are obtained. The Berger 3-spheres are also considered as homogeneous almost contact metric manifolds.
A GENERAL FRAMEWORK FOR HOLOMORPHIC FUNCTIONAL CALCULI
Authors: Haase Markus
Published: May 2005

We present an abstract approach to the construction of holomorphic functional calculi for unbounded operators and apply it to the special case of sectorial operators. In effect, we obtain a calculus for a much larger class of functions than was known before, including certain meromorphic functions. We discuss the role of topology. Then we prove in detail a composition rule $(f\circ g)(A)=f(g(A))$ which is the main result of the paper. This is done in such a way that the proof can easily be transferred to functional calculi for other classes of operators.
ZEROS OF DIFFERENTIAL POLYNOMIALS IN REAL MEROMORPHIC FUNCTIONS
Authors: Bergweiler Walter , Eremenko Alex , Langley Jim K.
Published: May 2005

We investigate whether differential polynomials in real transcendental meromorphic functions have non-real zeros. For example, we show that if $g$ is a real transcendental meromorphic function, $c\in\mathbb{R}\setminus\{0\}$ and $n\geq3$ is an integer, then $g'g^n-c$ has infinitely many non-real zeros. If $g$ has only finitely many poles, then this holds for $n\geq2$. Related results for rational functions $g$ are also considered.
Thought and Action: A Tribute to Stuart Hampshire
Authors: Hacker P. M. S.
Published: May 2005

The paper is a tribute to the late Stuart Hampshire's investigations of the ramifying role of intention in our conceptual scheme. It surveys the central argument of Thought and Action and the third chapter of Freedom of the Individual. Emphasis is placed upon Hampshire's constructive account of human agency and consequent description of the manner in which perception and action are interwoven. His analysis of the character of intentional action, self-knowledge and autonomy is described. Various lacunae in Hampshire's account are identified and an attempt is made to fill them in in a manner consistent with Hampshire's insights.
Minority Rights and the Preservation of Languages
Authors: Ellis Anthony
Published: May 2005

Do minority groups have a right to the preservation of their language? I argue that the rights of groups are always reducible to the rights of individuals. In that case, the question whether minorities have a right to the preservation of their language is a question of whether individuals have a right to it. I argue that, in the only relevant sense of ‘right’, they do not. They may have an interest in the preservation of their language, but, if so, that interest must be weighed against the costs of satisfying it, and, normally at least, we should expect that the costs will be quite out of proportion to the weight of the interests involved.
A Contextualized Approach to Biological Explanation
Authors: Boniolo Giovanni
Published: May 2005

In the paper, starting from a slightly modified version of van Fraassen's pragmatic approach to explanation, I will propose a pragmatical meta-model for the different biological explanatory models. That is, I will offer a pragmatic point of view to rule different explanatory models in function of the biological context from which the given biologist explains.