bluuebunny/crossref_metadata_2025 huggingface dataset:
The Norm Dependence of Singular Vectors
Authors: Kuang Zhiming
Published: December 2004

For a linearized system such as ∂ψ/∂t = 𝗠ψ, singular vector analysis can be used to find patterns that give the largest or smallest ratios between the sizes of 𝗠ψ and ψ. Such analyses have applications to a wide range of atmosphere–ocean problems. The resulting singular vectors, however, depend on the norm used to measure the sizes of 𝗠ψ and ψ, as noted in various applications. This causes complications because the choices of norm are generally nonunique. Based on perturbation theory, a derivation of how singular vectors change with norms typically used in the atmosphere–ocean literature is provided, and it is shown that the norm dependences observed in previous studies can be understood as general properties of singular vectors. This will hopefully clarify the interpretation of these observed norm dependencies, and provide guidance to new studies on how singular vectors would vary for different norms. It is further argued, based on these results, that there may not be as much norm-related ambiguity in problems, such as designing targeted observations or ensemble forecasts, as is often assigned to them.
Assessing a Cloud Optical Depth Retrieval Algorithm with Model-Generated Data and the Frozen Turbulence Assumption
Authors: Barker H. W. , Pavloski C. F. , Ovtchinnikov M. , Clothiaux E. E.
Published: December 2004

A cloud optical depth retrieval algorithm that utilizes time series of solar irradiance and zenith downwelling radiance data collected at a fixed surface site is assessed using model-generated cloud fields and simulated radiation measurements. To date, the retrieval algorithm has only been assessed using instantaneous cloud fields in which time series were mimicked via the frozen turbulence assumption. In this study, time series of radiation data are generated for use by the algorithm from a series of snapshots of an evolving and advecting cloud field, with values of optical depth retrieved for clouds occurring at the midpoint of the time series. This approach resembles conditions encountered in the field much better than those arising from the convenient frozen turbulence assumption. Values of optical depth are also retrieved for the same cloud field by employing the frozen turbulence approach. For the field of broken, shallow cumulus considered here, differences between the two sets of retrievals are small. This suggests that the encouraging results obtained thus far for this retrieval algorithm have not been secured falsely by the frozen turbulence assumption.
Effects of Noise on Thorpe Scales and Run Lengths
Authors: Johnson Helen L. , Garrett Chris
Published: December 2004

Estimating the diapycnal mixing rate from standard CTD data by identifying overturning regions in the water column (the Thorpe-scale approach) provides good spatial and temporal coverage but is sometimes limited by instrument noise. This noise leads to spurious density inversions that are difficult to distinguish from real turbulent overturns. Previous efforts to eliminate noise may have overcorrected and hence underestimated the level of mixing. Here idealized density profiles are used to identify the magnitude and characteristics of overturning regions arising entirely from instrument noise, in order to establish a standard against which CTD data can be compared. The key nondimensional parameters are 1) the amplitude of the noise scaled by the density change over the section of profile considered, and 2) the number of data points in the section of profile. In some cases the product of these, which is equal to the amplitude of the noise scaled by the average density difference between consecutive measurements, is more useful than the second parameter. The probability distribution of “run length,” a useful diagnostic, varies significantly across this parameter space. Reasons for this are discussed, and it is shown that CTD data very rarely lie in a region of parameter space where comparison with the probability density function (PDF) of run lengths for a random uncorrelated series, or its rms value 6, is appropriate. The distribution of Thorpe displacements arising entirely from instrument noise, as well as the Thorpe scale and the statistics of density inversions, is also discussed. Analysis of CTD data from the interfaces of the thermohaline staircase in the deep Canada Basin illustrates how the results can be applied in practice to help to distinguish between signal and noise in marginal regimes. Density inversions seen in these data are shown to be no different from those that would result from instrument noise.
The Importance of Nonlinear Cross-Shelf Momentum Flux during Wind-Driven Coastal Upwelling*
Authors: Lentz Steven J. , Chapman David C.
Published: December 2004

A simple theory is proposed for steady, two-dimensional, wind-driven coastal upwelling that relates the dynamics and the structure of the cross-shelf circulation to the stratification, bathymetry, and wind stress. The new element is an estimate of the nonlinear cross-shelf momentum flux divergence due to the wind-driven cross-shelf circulation acting on the vertically sheared geostrophic alongshelf flow. The theory predicts that the magnitude of the cross-shelf momentum flux divergence relative to the wind stress depends on the Burger number S = αN/f, where α is the bottom slope, N is the buoyancy frequency, and f is the Coriolis parameter. For S ≪ 1 (weak stratification), the cross-shelf momentum flux divergence is small, the bottom stress balances the wind stress, and the onshore return flow is primarily in the bottom boundary layer. For S ≈ 1 or larger (strong stratification), the cross-shelf momentum flux divergence balances the wind stress, the bottom stress is small, and the onshore return flow is in the interior. Estimates of the cross-shelf momentum flux divergence using moored observations from four coastal upwelling regions (0.2 ≤ S ≤ 1.5) are substantial relative to the wind stress when S ≈ 1 and exhibit a dependence on S that is consistent with the theory. Two-dimensional numerical model results indicate that the cross-shelf momentum flux divergence can be substantial for the time-dependent response and that the onshore return flow shifts from the bottom boundary layer for small S to just below the surface boundary layer for S ≈ 1.5–2.
Coastline Direction, Interannual Flow, and the Strong El Niño Currents along Australia's Nearly Zonal Southern Coast
Authors: Li Jianke , Clarke Allan J.
Published: December 2004

The western equatorial Pacific Ocean El Niño signal leaks through the gappy western equatorial Pacific Ocean boundary to the western and southern coasts of Australia. Ocean Topography Experiment (TOPEX)/Poseidon sea level data and coastal tide gauge measurements show that off the northwest coast the low-frequency signal propagates westward as large-scale Rossby waves. However, along the nearly zonal southern coast, particle displacements are nearly zonal near the coast and experience no planetary vorticity change. As a consequence, the Rossby wave mechanism fails, and theory suggests that the signal should decay from the shelf edge with baroclinic Rossby radius-of-deformation scale. High-resolution along-track TOPEX/Poseidon sea level heights show that the interannual height signal does decay rapidly seaward of the shelf edge with this scale. The sharp fall in sea level and geostrophic balance imply strong (∼10 cm s−1) low-frequency currents seaward of the shelf edge. On the shelf, interannual flow is in the same direction as the shelf-edge flow but is much weaker. The anomalous flows tend to be eastward during La Niña, when the western equatorial Pacific and Australian coastal sea levels are unusually high, and westward during El Niño when coastal sea levels tend to be anomalously low. The anomalous low-frequency flows can transport larvae large distances, enhancing the recruitment of Australian salmon to nursery grounds in the eastern part of the southern coast when the coastal sea level is higher than normal and decreasing recruitment when it is lower than normal.
Psychologists’ Search for the Good Life
Authors: Kernes Jerry L. , Kinnier Richard T.
Published: December 2004

Psychologists working in three settings (academia, university counseling centers, and community mental health) completed three measures of the “good life” as part of a study examining psychologists’ personal and professional values and beliefs. Psychologists generally endorsed accepting something from allways of life, appreciating and preserving the best of humanity, showing sympathetic concern for others, and enjoying the easily obtainable pleasures as preferred ways to live. They also supported feeling or expressing love, having or being part of a family, having good physical and/or mental health, and having significant friendships as the most desired characteristics of life. Psychologists were generally divided into moral absolutists and moral situationists with regard to their views about the moral dimensions of the good life.
Existential Psychotherapy with Adult Survivors of Sexual Abuse
Authors: Fisher Grace
Published: December 2004

This article explores existential psychotherapy as an effective approach to working with survivors of childhood sexual abuse. Focused on being in the world, the existential approach addresses the very issue that torments many survivors: To be seen and exposed in the world invites not only danger but possible annihilation. The article touches on the broad range of symptoms or manifestations of childhood sexual abuse as they may surface in the adult’s life, specifically how it compromises one’s relations with oneself and others. It examines three critical elements that arise in the therapeutic relationship: trust and betrayal, protective internal structures, and dissociative patterns. The article then discusses existential therapy, emphasizing the unifying themes of presence, authenticity, and awareness, and referencing specific tools like awaring, focusing, and bracketing to explore how this approach helps clients engage in their processes and assists the therapist to skillfully manage transference and countertransference issues unique to this population.
Pretherapy from a Developmental Perspective
Authors: Peters Hans
Published: December 2004

The starting-point of this article was one published earlier in the Dutch Journal of Client-Centered Psychotherapytitled “Some Comments on Imitation and Intersubjectivity in Neonates and Infants in Relation to Some Forms of Psychotherapy” (Peters, 2003). In that article, I demonstrated the importance of imitation in early life for well-developed intersubjectivity and for a well-established functional development in general. The intention of this article is a more thorough investigation into the possible relationship between imitation, intersubjectivity, and pretherapy. Although I published an extended article on pretherapy in this journal (Peters, 1999) I first give a summarized version of the principles of pretherapy. In the second part, I expand on some relevant research on early childhood imitation and intersubjectivity, whereas the third part deals with the relation between imitation, intersubjectivity, and pretherapeutic reflections, which places pretherapy in a developmental psychological frame of reference.
“We’re Blocking Youth’s Path to Crime”
Authors: Appier Janis
Published: December 2004

Everywhere Americans turned in the early 1930s, they heard alarming reports about the “crime wave” sweeping the country. Much of the blame for the crisis fell on teenage boys. In response, civic leaders in hundreds of U.S. cities formed crime prevention groups that sought to slash the rate of juvenile delinquency. The Los Angeles Coordinating Councils (LACC), the largest and best-known of these groups, pioneered the community approach to crime control, which entailed extensive experiments in social engineering. Because it championed social work and environmental explanations of criminal behavior, the community approach differed sharply from the contemporaneous federal “war on crime.” During the 1940s, the LACC suffered a series of blows, including a significant loss of funding. Nevertheless, the LACC and the community approach represent a cohesive attempt by middle-class urban Americans during the Great Depression to create a safe and meaningful civic life.
Estimating Johnson Curve Population Distributions in MULTILOG
Authors: van den Oord Edwin J. C. G.
Published: December 2004

The shape of the latent trait distribution can be of considerable theoretical and methodological importance. A simulation study was performed to examine the distribution of the likelihood ratio statistic that was used to test for normality via Johnson curves, the power to detect deviations from normality, and the estimation properties of the item and latent trait distribution parameters. Except in conditions in which all items had high-difficulty parameters or were dichotomous, the distribution of the statistic used to test for normality could be approximated with a chi-square distributed with 2 degrees of freedom. In a variety of situations, the power was good enough to detect even small deviations from normality. Compared to assuming a normal distribution, allowing for Johnson curve latent trait distributions increased the standard errors of the marginal maximum likelihood item parameter estimates but reduced their bias in situations in which the latent trait was nonnormal.
The α and the ω of Congeneric Test Theory: An Extension of Reliability and Internal Consistency to Heterogeneous Tests
Authors: Lucke Joseph F.
Published: December 2004

Psychometric theory focuses primarily on tests that are homogeneous, measuring only one attribute of a psychosocial entity. However, the complexity of psychosocial behavior often requires tests that are heterogeneous, measuring more than one attribute. In this presentation, reliability and internal consistency are extended to heterogeneous tests under the rubric of congeneric test theory. The extensions show that reliability and internal consistency have very similar properties. Reliability and internal consistency are shown to be unique up to a linear transformation. Whereas internal consistency is a lower bound to reliability in the homogeneous case, it is a strict lower bound in the heterogeneous case. Reliability equals internal consistency if and only if the test is homogeneous and true-score equivalent. An analytic argument shows that neither reliability nor internal consistency can detect whether a test is homogeneous or heterogeneous. The reliability (internal consistency) of a heterogeneous test is the sum of the sub-tests’ reliabilities (internal consistencies) plus the sum of reliabilities (internal consistencies) involving the correlations among the sub-tests. Higher-order tests are tests in which items measure first-order attributes, first-order attributes reflect second-order attributes, and so on. Reliability (internal consistency) can be partitioned into the sums of direct reliability (direct internal consistency) for the first-order attributes and indirect reliabilities (indirect internal consistencies) for the second- and higher-order attributes. Simple examples demonstrate that internal consistency may be a poor approximator to the reliability of congeneric tests. Given that reliability for congeneric tests can now be estimated by modern statistical software, the need for internal consistency is diminished. However, internal consistency may be useful in bounding or approximating reliability in general linear latent variable models.
Fair Highway Networks
Authors: De Corla-Souza Patrick
Published: December 2004

The House reauthorization bill, H.R. 3550, eliminates current opportunities available to States to use variable pricing to reduce congestion under the existing Value Pricing Pilot Program. This article presents an innovative road-pricing strategy that could make great strides in achieving national, state, and local transportation goals. Known as FAIR (fast and intertwined regular) highway networks, the strategy converts the existing metropolitan freeway network during peak periods only into a premium-service, free-flowing freeway network that provides new fast, frequent, and inexpensive bus service, free premium service for carpools, and premium service for single-occupant vehicles paying a toll that varies to manage demand and keep the freeway congestion free. A FAIR highway network will be self-financing and economically efficient. Surpluses may also be available to address new transportation capacity needs in growing areas. The concept can gain support from transportation stakeholders if its benefits are carefully explained and demonstrated through a pilot project.
A Web-Supported National Bridge Inventory Management Tool
Authors: Karlaftis Matthew , Kepaptsoglou Konstantinos , Lambropoulos Sergios
Published: December 2004

The U.S. National Bridge Inventory (NBI) contains approximately 600,000 bridges. Its size, numerous items, and electronic format make management and analysis of its data difficult. The objective of this study is to develop a tool that will provide a user-friendly environment as well as advanced services for accessing and analyzing NBI data sets. The tool can import text- or spreadsheet-based NBI data sets, provide tools for managing and analyzing them, and use Web services for pinpointing bridge positions. It is considered useful for managing the NBI data sets and for further examining and analyzing the characteristics and condition of the NBI.
Estimating Differential Responses to Local Fiscal Conditions: A Mixture Model Analysis
Authors: Sjoquist David L. , Walker Mary Beth , Wallace Sally
Published: December 2004

Alternative hypotheses exist regarding the impact of local sales and income taxes on local governments’ taxing and spending decisions. One hypothesis is that local governments use sales and income taxes to pay for spending increases and leave property tax collections unchanged, while an equally plausible alternative is that local governments use sales and income taxes to reduce property taxes. Traditional models that restrict the impact of these local taxes to be the same across all local governments are not able to capture both types of behavior. The methodological difficulty lies in allowing for differences in behavior with no a priori information on which cities belong in which category. In this article, the authors use panel data to estimate a mixture model of spending and property tax response to the existence of local taxes. These empirical results provide evidence to support both hypotheses. These differences are both substantive and statistically significant.
Testing a Computational Model of the Goal-Level Effect: An Example of a Neglected Methodology
Authors: Vancouver Jeffrey B. , Putka Dan J. , Scherbaum Charles A.
Published: December 2004

To encourage the use of computational modeling in organizational behavior research, an example computational model is developed and rigorous tests of it presented. Specifically, a computational model based on control theory was created to test the theory’s explanation of the goal-level effect (e.g., higher goals lead to higher performance). Data from simulations of the model were compared with the behavior of 32 undergraduate students performing a scheduling task under various within-subject manipulations and across time. Correlational analyses indicated that the model accounted for most of the participants’data, with coefficients between the model and each participant’s behavior mostly in the high 90s.
Validity of the Structural Properties of Text-Based Causal Maps: An Empirical Assessment
Authors: Nadkarni Sucheta , Narayanan V. K.
Published: December 2004

Recently, text-based causal maps (TBCMs) have generated enthusiasm as a methodological tool because they provide a way of accessing large, untapped sources of data generated by organizations. Although TBCMs have been used extensively in organizational behavior and strategic management research, studies assessing the psychometric properties of TBCM measures are virtually nonexistent. With the intention of facilitating large-sample substantive research using TBCMs, the authors examine the construct validity of two most frequently employed structural properties of TBCMs: complexity and centrality. In assessing construct validity, they examine the internal consistency, dimensionality, and predictive validity of the structural properties. The results suggest that complexity is not a general cognitive attribute. Rather, it is indicative of domain knowledge. On the other hand, centrality, which reflects the degree of hierarchy characterizing the TBCM, is related to cognitive ability and may reflect general information processing. Moreover, complexity and centrality, but not cognitive ability, predicted student performance.
How Do We Justify Knowledge Produced Within Interpretive Approaches?
Authors: Sandberg Jörgen
Published: December 2004

The use of interpretive approaches within management and organizational sciences has increased substantially. However, appropriate criteria for justifying research results from interpretive approaches have not developed so rapidly alongside their adaptation. This article examines the potential of common criteria for justifying knowledge produced within interpretive approaches. Based on this investigation, appropriate criteria are identified and a strategy for achieving them is proposed. Finally, an interpretive study of competence in organizations is used to demonstrate how the proposed criteria and strategy can be applied to justify knowledge produced within interpretive approaches.
Immunostimulatory oligodeoxynucleotides induce apoptosis of B cell chronic lymphocytic leukemia cells
Authors: Jahrsdörfer Bernd , Wooldridge James E , Blackwell Sue E , Taylor Christiana M , Griffith Thomas S , Link Brian K , Weiner George J
Published: December 2004

Immunostimulatory oligodeoxynucleotides (IS ODN) can mediate a number of immunologic effects. We previously demonstrated that treatment of B cell chronic lymphocytic leukemia (B-CLL) cells with one class of IS ODN, CpG ODN, alters their phenotype and increases their immunogenicity. Here, we demonstrate that in contrast to the classic understanding of CpG ODN as inhibitors of B cell apoptosis, IS ODN including CpG ODN induce apoptosis in B-CLL cells. It is important that these changes are seen not only with CpG ODN but with ODN that lack the classical CpG motif. B-CLL cells from 20 subjects were treated in vitro with IS ODN for up to 7 days. IS ODN treatment resulted in increased numbers of apoptotic cells in 13 out of 20 B-CLL samples. IS ODN enhanced apoptosis in samples with 13q deletion as a single aberration and had a heterogeneous effect on apoptosis in samples with other aberrations including 17p deletion, 11q deletion, or trisomy 12. Induction of apoptosis did not correlate with expression of the CpG ODN receptor Toll-like receptor 9. Apoptosis was dependent on the activation of caspases and was accompanied by up-regulation of CD95/Fas and its ligand. We conclude that IS ODN including CpG ODN can induce apoptosis of most B-CLL samples. The ability of IS ODN to induce apoptosis differs based on cytogenetic status. Up-regulation of CD95/Fas may play a role in IS ODN-induced apoptosis of B-CLL.
Neutrophils and keratinocytes in innate immunity—cooperative actions to provide antimicrobial defense at the right time and place
Authors: Borregaard Niels , Theilgaard-Mönch Kim , Cowland Jack B , Ståhle Mona , Sørensen Ole E
Published: December 2004

The human neutrophil is a professional phagocyte of fundamental importance for defense against microorganisms, as witnessed by the life-threatening infections occurring in patients with neutropenia or with defects that result in decreased microbicidal activity of the neutrophil [1, 2]. Likewise, the skin and mucosal surfaces provide important barriers against infections. Traditionally, these major defense systems, the epithelial cells and the neutrophils, have been viewed as limited in their armory: The epithelial cells provide defense by constituting a physical barrier, and the neutrophils provide instant delivery of preformed antimicrobial substances or on-the-spot assembly of the multicomponent reduced nicotinamide adenine dinucleotide phosphate oxidase from stored components for the generation of reactive oxygen metabolites. Recent research has shown that epithelial cells are highly dynamic and able to generate antimicrobial peptides in response not only to microbial infection itself [3–6] but more importantly, to the growth factors that are called into play when the physical barrier is broken, and the risk of microbial infection is imminent [7]. Likewise, the neutrophil changes its profile of actively transcribed genes when it diapedeses into wounded skin [8]. This results in generation of signaling molecules, some of which support the growth and antimicrobial potential of keratinocytes and epithelial cells. This paper will highlight some recent advances in this field.
Why are European Countries Diverging in their Unemployment Experience?
Authors: Saint-Paul Gilles
Published: December 2004

During the nineties, unemployment fell in a number of European countries while it remained high in others. This Paper discusses potential causes for that evolution in light of recent economic research, emphasizing obstacles to reform due to political constraints, the prevalence of ideology, and agency issues within those bureaucracies concerned with the unemployment problem. Some speculative thoughts are offered as to why those factors might be more stringent in countries where unemployment remained high.
On the (Ir)Relevance of Distribution and Labor Supply Distortion to Government Policy
Authors: Kaplow Louis
Published: December 2004

Should the assessment of government policies, such as the provision of public goods and the control of externalities, deviate from first-best principles to account for distributive effects and the distortionary cost of labor income taxation? For example, is the optimal extent of public goods provision smaller than indicated by the Samuelson rule because finance is distortionary? Or should environmental regulations fail to internalize externalities fully if the incidence of the regulations is regressive? It is suggested that these questions are best addressed by considering distribution-neutral implementation, in which budget balance is achieved by choosing an adjustment to the income tax that offsets the distributive impact of the policy in question. In basic cases, both distribution and labor supply distortion are moot because the target policy and the tax adjustment produce offsetting effects on each. Thus, traditional first-best principles provide good benchmarks for policy analysis after all. Moreover, even when actual implementation will not be distribution neutral in aggregate, distribution-neutral policy analysis has many conceptual and practical virtues that render it quite useful to investigators.
Recommendations for Further Reading
Authors: Saffran Bernard
Published: December 2004

This section will list readings that may be especially useful to teachers of undergraduate economics, as well as other articles that are of broader cultural interest. In general, the articles chosen will be expository or integrative and not focus on original research. If you write or read an appropriate article, please send a copy of the article (and possibly a few sentences describing it) to Bernard Saffran, c/o Journal of Economic Perspectives, Department of Economics, Swarthmore College, Swarthmore, PA 19081.
Specific Chemical Effects on Surface-Enhanced Raman Spectroscopy for Ultra-Sensitive Detection of Biological Molecules
Authors: Koo Tae-Woong , Chan Selena , Sun Lei , Su Xing , Zhang Jingwu , Berlin Andrew A.
Published: December 2004

Achieving high signal amplification in surface-enhanced Raman scattering (SERS) is important for reaching single molecule level sensitivity and has been the focus of intense research efforts. We introduce a novel chemical enhancer, lithium chloride, that provides an additional order of magnitude increase in SERS relative to previously reported enhancement results. We have duplicated single molecule detection of the DNA base adenine that has previously been reported, thereby providing independent validation of this important result. Building upon this work, we show that the chemical enhancer LiCl produces strong SERS signal under a wide range of experimental conditions, including multiple laser excitation wavelengths and target molecule concentrations, for nucleotides, nucleosides, bases, and dye molecules. This is significant because while selection of anions used in chemical enhancement is well known to affect the degree of amplification attained, cation selection has previously been reported to have no major effect on the magnitude of SERS enhancement. Our findings indicate that cation selection is quite important in ultra-sensitive SERS detection, opening the door to further discussion and theory development involving the role of cations in SERS.
Evaluation of Visible and Near-Infrared Spectroscopy as a Tool for Assessing Fiber Fineness during Mechanical Preparation of Dew-Retted Flax
Authors: Sharma H. S. S. , Reinard N.
Published: December 2004

Flax fiber must be mechanically prepared to improve fineness and homogeneity of the sliver before chemical processing and wet-spinning. The changes in fiber characteristics are monitored by an airflow method, which is labor intensive and requires 90 minutes to process one sample. This investigation was carried out to develop robust visible and near-infrared calibrations that can be used as a rapid tool for quality assessment of input fibers and changes in fineness at the doubling (blending), first, second, third, and fourth drawing frames, and at the roving stage. The partial least squares (PLS) and principal component regression (PCR) methods were employed to generate models from different segments of the spectra (400–1100, 1100–1700, 1100–2498, 1700–2498, and 400–2498 nm) and a calibration set consisting of 462 samples obtained from the six processing stages. The calibrations were successfully validated with an independent set of 97 samples, and standard errors of prediction of 2.32 and 2.62 dtex were achieved with the best PLS (400–2498 nm) and PCR (1100–2498 nm) models, respectively. An optimized PLS model of the visible–near-infrared (vis-NIR) spectra explained 97% of the variation ( R2 = 0.97) in the sample set with a standard error of calibration (SEC) of 2.45 dtex and a standard error of cross-validation (SECV) of 2.51 dtex ( R2 = 0.96). The mean error of the reference airflow method was 1.56 dtex, which is more accurate than the NIR calibration. The improvement in fiber fineness of the validation set obtained from the six production lines was predicted with an error range of −6.47 to +7.19 dtex for input fibers, −1.44 to +5.77 dtex for blended fibers at the doubling, and −4.72 to +3.59 dtex at the drawing frame stages. This level of precision is adequate for wet-spinners to monitor fiber fineness of input fibers and during the preparation of fibers. The advantage of vis-NIR spectroscopy is the potential capability of the technique to assess fineness and other important quality characteristics of a fiber sample simultaneously in less than 30 minutes; the disadvantages are the expensive instrumentation and the expertise required for operating the instrument compared to the reference method. These factors need to be considered by the industry before installing an off-line NIR system for predicting quality parameters of input materials and changes in fiber characteristics during mechanical processing.
Intensities of Calcium Dipicolinate and Bacillus Subtilis Spore Raman Spectra Excited with 244 nm Light
Authors: Nelson W. H. , Dasari R. , Feld M. , Sperry J. F.
Published: December 2004

Ultraviolet (UV) resonance Raman spectra of Bacillus subtilis endospores have been excited at 244 nm. Spectra can be interpreted in terms of contributions from calcium dipicolinate and nucleic acid components. Differences between spectra of spores and vegetative cells are very large and are due to the dominance of the dipicolinate features in the spore spectra. Because the DNA and RNA composition of B. subtilis spores is known and because the cross-sections of Raman bands belonging to DNA and RNA bases are known, it is possible to calculate resonance Raman spectral cross-sections for the spore Raman peaks associated with the nucleic acids. The cross-sections of peaks associated with calcium dipicolinate have been measured from aqueous solutions. Cross-section values of the dominant 1017 cm−1 calcium dipicolinate peak measured from the Bacillus spores have been shown to be consistent with a calcium dipicolinate composition of ten percent or less by weight in the spores. It is suggested that spectral cross-sections of endospores excited at 244 nm can be estimated to be the sum of the cross-sections of the calcium dipicolinate, DNA, and RNA components of the spore. It appears that the peaks due to DNA and RNA can be used as an internal standard in the calculation of spore Raman peak cross-sections, and potentially the amount of calcium dipicolinate in spores. It is estimated on the basis of known nucleic acid base cross-sections that the most intense Raman band of the Bacillus subtilis spore spectra has a cross-section of no more than 4 × 10−18 cm2/mol-sr.
Modeling of Complex Viscosity Changes in the Curing of Epoxy Resins from Near-Infrared Spectroscopy and Multivariate Regression Analysis
Authors: Garrido M. , Larrechi M. S. , Rius F. X.
Published: December 2004

The present study investigates the relationship between the changes in complex viscosity and near-infrared spectra. Principal component regression analysis is applied to a near-infrared data set obtained from the in situ monitoring of the curing of diglycidyl ether of bisphenol A with the diamine 4,4′-diaminodiphenylmethane. The values of complex viscosity obtained by dynamic mechanical analysis during the cure process were used as a reference. The near-infrared spectra recorded throughout the reaction, unlike the univariate data analysis at some wavelengths of the spectra, contain a sufficient amount of information to estimate the complex viscosity. The relationship found was high and the results demonstrate the quality of the fitted model. Also, a simple user-friendly procedure for applying the model, focused on the user, is shown.
Fourier Transform Near-Infrared Spectrometer Using a Corner-Cube Integrated Prism Scanning Interferometer
Authors: Kiyokura Takanori , Ito Takahiro , Sawada Renshi
Published: December 2004

This paper describes a Fourier transform (FT) near-infrared spectrometer that uses an integrated prism scanning interferometer whose optical paths are stabilized by corner cubes. A combination of corner cubes and a retroreflection mirror, which is sometimes used in the conventional interferometer for FT spectrometers, is adopted and adapted to the integrated prism scanning interferometer through a special design. Without any degradation of spectroscopic properties, the optical path in the interferometer is highly stabilized and the moving distance of the stage is halved. These advantages provide a robust and portable FT spectrometer for field use.
C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution
Authors: Olson Lydia G. , Uibel Rory H. , Harris Joel M.
Published: December 2004

Metal colloids immobilized on a glass support substrate are modified with a self-assembled alkylsilane (C18) layer to promote adsorption of polycyclic aromatic hydrocarbons from aqueous solutions. Detection of these compounds from low concentration solutions is accomplished by using surface-enhanced Raman scattering (SERS). SERS spectra of pyrene adsorbed to C18-modified immobilized silver colloids are dominated by Raman bands that are not consistent with pyrene and indicate that pyrene undergoes a chemical reaction at the surface. The origins of this surface product are investigated, and it is determined that silver and oxygen are required to form the product, whose Raman spectrum is consistent with oxidation to a quinone. When a C18-modified gold-colloid substrate is used, Raman scattering consistent with unreacted pyrene is observed. The adsorption and detection of pyrene adsorbed from low (2 ppb) concentration aqueous solutions onto C18-modified gold-colloid substrates is reported; naphthalene and phenanthrene are detected at ∼5 ppb. Adsorption kinetics are rapid (<5 min), and the concentration-dependent SERS response is consistent with a Langmuir isotherm.
Prediction of Interlaminar Shear Strength of a Thermally Aged Carbon/Epoxy Composite Material by Fourier Transform Infrared Photoacoustic Spectroscopy
Authors: Sweterlitsch Jeffrey J. , Jones Roger W. , Hsu David K. , McClelland John F.
Published: December 2004

Photoacoustic spectroscopy was used to predict the interlaminar shear strength of a carbon/epoxy composite. Samples were artificially aged by exposing the samples to elevated temperatures in an air environment. Short-beam shear tests were performed to determine mechanically the interlaminar shear strength of the samples. Photoacoustic spectra of the samples were also collected and compared to mechanical data. Chemometrics were performed on the spectral and mechanical data, and a good correlation was found between the near surface chemistry of the composite and overall mechanical integrity.
Laser-Excited Time-Resolved Shpol'skii Spectroscopy for the Direct Analysis of Dibenzopyrene Isomers in Liquid Chromatography Fractions
Authors: Yu Shenjiang , Campiglia Andres D.
Published: December 2004

We present a unique method for the unambiguous determination of dibenzo[ a,l]pyrene, dibenzo[ a,e]pyrene, dibenzo[ a,h]pyrene, dibenzo[ a,i]pyrene, and dibenzo[ e,l]pyrene in high-performance liquid chromatography (HPLC) fractions. Chemical analysis is performed via laser-excited time-resolved Shpol'skii spectroscopy with the aid of a cryogenic fiber-optic probe, pulsed tunable dye laser, spectrograph, and intensified charge-coupled device. Unambiguous identification is accomplished via wavelength time matrix formats, which give simultaneous access to spectral and lifetime information. Prior to spectroscopic analysis, HPLC fractions are pre-treated with liquid–liquid extraction or solid–liquid extraction at the tip of the fiber-optic probe. Solid–liquid extraction gives the best limits of detection, which vary from 40 pg mL−1 (dibenzo[ a,l]pyrene) to 0.2 ng mL−1 (dibenzo[ e,l]pyrene).
Mechanisms of action of peptide inhibitors of mammalian ribonucleotide reductase targeting quaternary structure
Authors: Gao Ying , Kashlan Ossama B. , Kaur Jaskiran , Tan Chiheng , Cooperman Barry S.
Published: December 2004

Mammalian ribonucleotide reductase (mRR) is a chemotherapeutic target. The enzyme is composed of 2 subunits (mR1 and mR2) and is inhibited by Ac‐FTLDADF (denoted P7), corresponding to the C‐terminus of mR2, which competes with mR2 for binding to mR1. mRR has 2 physiologically important active forms, mR12mR22 and mR16(mR22)j (j = 1–3). Here we report on the mechanism of action of recently identified peptide derivatives having higher activities than P7 toward inhibition of one or both active forms. A significant feature of both P7 and these new inhibitors is that they are more potent vs. mR12mR22 than mR16(mR22)j. For some of these peptides, this is due in part to their preferential binding to the mR1 monomer. The possible application of these peptide derivatives in cancer chemotherapy is discussed. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2005
Newly developed basis sets for density functional calculations
Authors: Chiodo S. , Russo N. , Sicilia E.
Published: December 2004

Optimized contracted Gaussian basis sets of double‐zeta valence polarized (DZVP) quality for first‐row transition metals are presented. The DZVP functions were optimized using the PWP86 generalized gradient approximation (GGA) functional and the B3LYP hybrid functional. For a careful analysis of the basis sets performance the transition metal atoms and cations excitation energies were calculated and compared with the experimental ones. The calculated values were also compared with those obtained using the previously available DZVP basis sets developed at the local‐density functional level. Because the new basis sets work better than the previous ones, possible reasons of this behavior are analyzed. The newly developed basis sets also provide a good estimation of other atomic properties such as ionization energies. © 2004 Wiley Periodicals, Inc. J Comput Chem 26: 175–183, 2005
Urea: An ab initio and force field study of the gas and solid phases
Authors: Sun H. , Kung P. W.‐C.
Published: December 2004

We have studied the gaseous and solid phases of urea using both quantum mechanics calculation and force field simulation methods. Our ab initio calculations confirmed experimental observations that urea structure is planar in the crystal, but nonplanar in the gas phase. Based on electron structure analysis, we suggest that the significant difference between these two structures in different environments can be qualitatively explained by two resonance structures. The planar structure is more polarized than the nonplanar one, and the former is stabilized in the solid phases due to strong electrostatic interactions. We found classical force field method is incapable to represent such strong polarization effect. Using molecular dynamics simulations with a force field optimized for condensed phases, we calculated the crystalline structures of urea in the temperature range of 12 to 293 K. The densities as well as cell parameters are within 2% deviation from the experimental data in the temperature range. © 2004 Wiley Periodicals, Inc. J Comput Chem 26: 169–174, 2005
Electrospray ionization mass spectrometry of organic–inorganic materials: identification and gas‐phase reactivity of functionalized octahedral rhenium(III) clusters
Authors: Rondeau David , Perruchas Sandrine , Avarvari Narcis , Batail Patrick , Vékey Karoly
Published: December 2004

Electrospray ionization mass spectrometry was used for the analysis of functionalized rhenium clusters such as [Re6Se8(o‐Me2TTFPPh2)6]2+ (1), {Re6Se8[(o‐Me2TTF)2PPh]6}2+ (2) and [Re6Se8(MePPh2)6]2+ (3). The high‐resolution mass spectra of the intact clusters, performed in dichloromethane, confirm the identification of the compounds by comparison with the theoretical isotopic distributions. Low‐resolution full‐scan mass spectra recorded at increasing desolvation cone voltage values allow the study of the intrinsic reactivity of ionic species. The survival yield curves illustrating the bimolecular reactivity of 1 and 2 suggest that a bisdimethyltetrathiafulvalene(phenyl)phosphine ligand increases the stability of the functionalized ML62+ cluster 2. In the case of the 3, instead of loss of a neutral ligand, ligand exchange is observed either with traces of water present in dichloromethane or with acetonitrile used as solvent. Copyright © 2004 John Wiley & Sons, Ltd.
Electrospray ionization mass spectrometric analysis of chemical reactions of dissolution of selenium in strongly basic amines
Authors: Arakawa Ryuichi , Sasao Ai , Sonoda Noboru
Published: December 2004

When elemental selenium was added to a strongly basic amine, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) or 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN), the selenium started to dissolve and the solution turned dark brown. We investigated the chemical reaction of this selenium dissolution process by electrospray ionization mass spectrometry (ESI‐MS). The study reveals for the first time that cleavage of SeSe bonds by the amine initiates the reaction to form molecular Se2, which then abstracts hydrogen from the amine molecule. ESI‐MS with the use of a nanospray technique was shown to be a useful tool for studying the dissolution of elements in strongly basic or acidic solvents. Copyright © 2004 John Wiley & Sons, Ltd.
Poly(propylene terephthalate) Modified with 2,2‐Bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) Units: Thermal Behaviour, Crystallisation Kinetics and Morphology
Authors: Berti Corrado , Colonna Martino , Finelli Lara , Lorenzetti Cesare , Lotti Nadia , Vannini Micaela
Published: December 2004

Summary: The thermal behaviour of poly(propylene terephthalate) modified with 2,2‐bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) units (PPT/BHEEBT copolymers) was investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and hot‐stage optical microscopy (MO). Good thermal stability was found for each sample. The thermal analysis carried out using the DSC technique showed that the Tm of the copolymers decreased with the increment in BHEEBT unit content. This was different from the Tg which, on the contrary, increased. Wide‐angle X‐ray diffraction measurements allowed the identification of the PPT crystalline structure in each semicrystalline sample. Multiple endotherms were shown in the PPT/BHEEBT samples, due to melting and recrystallisation processes, similarly to PPT. The $T_{\rm m}^ \circ $ of the copolymers was derived from the application of the Hoffman‐Weeks' method. The isothermal crystallisation kinetics were analysed according to Avrami's treatment. The introduction of BHEEBT units was found to decrease the crystallisation rate compared to pure PPT. Values of the Avrami's exponent n close to 3 were obtained for PPT/BHEEBT6 and PPT/BHEEBT12, regardless of Tc, in agreement with a crystallisation process originating from pre‐determined nuclei and characterised by three‐dimensional spherulitic growth. As a matter of fact, for these two copolymers, space‐filling spherulites were observed through optical microscopy at all Tcs. The heat of fusion (ΔHm) was correlated to the specific heat increment (Δcp) for samples with different degrees of crystallinity, and the results were interpreted on the basis of the existence of an interphase, whose amount was found to depend mainly on composition, despite the thermal treatment applied to the polymer also playing an important role.

Calorimetric curves of PPT, PBHEEBT homopolymers and their random copolymers after melt quenching.

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Calorimetric curves of PPT, PBHEEBT homopolymers and their random copolymers after melt quenching.
Morphology and Rheological Behaviors of Polycarbonate/High Density Polyethylene in situ Microfibrillar Blends
Authors: Xu Hong‐Sheng , Li Zhong‐Ming , Pan Ji‐Lin , Yang Ming‐Bo , Huang Rui
Published: December 2004

Summary: Polycarbonate (PC)/high density polyethylene (HDPE) in situ microfibrillar blends were fabricated by a slit die extrusion, hot stretching, and quenching process. Despite PC and HDPE having a high viscosity ratio, which is usually disadvantageous to fibrillation, the morphological observation indicated that the blends had well‐defined PC microfibrils. The size and amount of the PC fibrils were nonuniform through the thickness of the extrudate, and were also affected by the PC concentration and hot stretch ratio. There were coarse and dense fibrils in the core zone, while these fibrils became finer and reduced in number toward the surface. The melt flow rate (MFR) of the PC/HDPE microfibrillar blend decreased with the increase of PC concentration, but increased with the larger hot stretching rate (or hot stretching ratio, HSR). Besides, it was found that the fibrillar blend had better flowability than the common blend with spherical particles at the same PC concentration. Temperature was also an important factor influencing the MFR due to the temperature dependence of PC and HDPE viscosity, and the PC phase morphology. The PC microfibrils could not be preserved beyond 230 °C and transformed into spherical particles. The rheological behaviors at various shear rates were studied by capillary rheometer. The orientation of PC fibrils and HDPE molecules with higher shear rate led to a decrease in the viscosity of microfibrillar blend. The data obtained in this study can help construct the technical foundation for recycling and utilization of PC and HDPE waste by manufacture of microfibrillar blends in future work.

SEM micrograph of the PC/HDPE microfibrillar blend.

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SEM micrograph of the PC/HDPE microfibrillar blend.