bluuebunny/crossref_metadata_2025 huggingface dataset:
Distributed Population Mechanism for the 3-D Oculomotor Reference Frame Transformation
Authors: Smith Michael A. , Crawford J. Douglas
Published: November 2004

Human saccades require a nonlinear, eye orientation–dependent reference frame transformation to transform visual codes to the motor commands for eye muscles. Primate neurophysiology suggests that this transformation is performed between the superior colliculus and brain stem burst neurons, but provides little clues as to how this is done. To understand how the brain might accomplish this, we trained a 3-layer neural net to generate accurate commands for kinematically correct 3-D saccades. The inputs to the network were a 2-D, eye-centered, topographic map of Gaussian visual receptive fields and an efference copy of eye position in 6-dimensional, push–pull “neural integrator” coordinates. The output was an eye orientation displacement command in similar coordinates appropriate to drive brain stem burst neurons. The network learned to generate accurate, kinematically correct saccades, including the eye orientation–dependent tilts in saccade motor error commands required to match saccade trajectories to their visual input. Our analysis showed that the hidden units developed complex, eye-centered visual receptive fields, widely distributed fixed-vector motor commands, and “gain field”–like eye position sensitivities. The latter evoked subtle adjustments in the relative motor contributions of each hidden unit, thereby rotating the population motor vector into the correct correspondence with the visual target input for each eye orientation: a distributed population mechanism for the visuomotor reference frame transformation. These findings were robust; there was little variation across networks with between 9 and 49 hidden units. Because essentially the same observations have been reported in the visuomotor transformations of the real oculomotor system, as well as other visuomotor systems (although interpreted elsewhere in terms of other models) we suggest that the mechanism for visuomotor reference frame transformations identified here is the same solution used in the real brain.
New Type of Synaptically Mediated Epileptiform Activity Independent of Known Glutamate and GABA Receptors
Authors: Skov Jane , Nedergaard Steen , Andreasen Mogens
Published: November 2004

It is well known that excitatory synaptic transmission at the hippocampal CA3–CA1 synapse depends on the binding of released glutamate to ionotropic receptors. Here we report that during long-term application of Cs+ (5 mM), stimulation of the Schaffer collateral-commisural pathway evokes an epileptic field potential (Cs-FP) in area CA1 of the rat hippocampal slice, which is resistant to antagonists of ionotropic glutamate and GABAA receptors. The Cs-FP was blocked by N-type but not L-type Ca2+ channel antagonists and was attenuated by adenosine (0.5 mM), as expected for a synaptically mediated response. These properties make the Cs-FP fundamentally different from other types of Cs+-induced epileptiform activity. Replacement of Cs+ with antagonists of the hyperpolarization-activated nonselective cation current Ih and inwardly rectifying potassium channels (KIR) or partial inhibition of the Na+/K+ pump did not cause Cs-FP–like potentials, which indicates that such actions of Cs+ were not responsible for the Cs-FP. The effect of Cs+ was partly mimicked by 4-aminopyridine (4-AP; 2 mM), suggesting that an increase in transmitter release is involved. The group I metabotropic glutamate receptor (mGluR) agonist ( RS)-3,5-dihydroxyphenylglycine (DHPG) attenuated the Cs-FP. This effect was not, however, antagonized by group I mGluR antagonists. Selective and nonselective mGluR antagonists did not attenuate the Cs-FP. We conclude that long-term exposure to Cs+ induces a state where excitatory synaptic transmission can exist between area CA3 and CA1 in the hippocampus, independent of ionotropic and metabotropic glutamate receptors and GABAA receptors.
Dopamine Modulates Excitability of Basolateral Amygdala Neurons In Vitro
Authors: Kröner Sven , Rosenkranz J. Amiel , Grace Anthony A. , Barrionuevo German
Published: November 2004

The amygdala plays a role in affective behaviors, which are modulated by the dopamine (DA) innervation of the basolateral amygdala complex (BLA). Although in vivo studies indicate that activation of DA receptors alters BLA neuronal activity, it is unclear whether DA exerts direct effects on BLA neurons or whether it acts via indirect effects on BLA afferents. Using whole cell patch-clamp recordings in rat brain slices, we investigated the site and mechanisms through which DA regulates the excitability of BLA neurons. Dopamine enhanced the excitability of BLA projection neurons in response to somatic current injections via a postsynaptic effect. Dopamine D1 receptor activation increased excitability and evoked firing, whereas D2 receptor activation increased input resistance. Current- and voltage-clamp experiments in projection neurons showed that D1 receptor activation enhanced excitability by modulating a 4-aminopyridine- and α-dendrotoxin-sensitive, slowly inactivating K+current. Furthermore, DA and D1 receptor activation increased evoked firing in fast-spiking BLA interneurons. Consistent with a postsynaptic modulation of interneuron excitability, DA also increased the frequency of spontaneous inhibitory postsynaptic currents recorded in projection neurons without changing release of GABA. These data demonstrate that DA exerts direct effects on BLA projection neurons and indirect actions via modulation of interneurons that may work in concert to enhance the neuronal response to large, suprathreshold inputs, while suppressing weaker inputs.
Dynamic Properties of Antennal Responses to Pheromone in Two Moth Species
Authors: Justus Kristine A. , Cardé Ring T. , French Andrew S.
Published: November 2004

Dynamic properties of pheromone plumes are behaviorally important in some moths for inducing upwind flight, but little is known about the time-dependent properties of odor transduction or the mechanisms that limit receptor dynamic sensitivity. We stimulated male antennae of two moth species, Cadra cautella and Spodoptera exigua, with pheromone plumes in a wind tunnel while recording electroantennograms (EAG) and concentration of a surrogate plume (propylene, which mimics a pheromone plume) using a photoionization detector (PID). Turbulent plumes were produced by mechanical baffles, creating broad frequency range dynamic concentration changes at the antennae. Frequency response functions and coherence functions between PID and EAG signals were used to measure the dynamic responses of the two species to pheromone blends and individual components. A single time constant filter fitted the responses of both species, but S. exigua was about three times faster than C. cautella. Responses to individual pheromone components were significantly different in S. exigua but not in C. cautella. We also fitted the data with a simple block-structured nonlinear cascade. This supported the simple filter model but also suggested that the response saturates at an early stage of chemotransduction.
Existence of triple positive periodic solutions of a functional differential equation depending on a parameter
Authors: Liu Xi-lan , Zhang Guang , Cheng Sui Sun
Published: November 2004

We establish the existence of three positive periodic solutions
for a class of delay functional differential equations depending
on a parameter by the Leggett‐Williams fixed point theorem.
Staging Disaster: Reporting Live (sort of) from Seattle
Authors: Dent Michelle
Published: November 2004

When it comes to “homeland security”, ordinary people, the press, government, theatre practitioners, and academics are struggling to effectively stage catastrophe and rehearse preparedness
Metal Performance Humanizing Robots, Returning to Nature, and Camping About
Authors: Dixon Steve
Published: November 2004

Robots and cyborgs perform the humanization of machines and the dehumanization of humans. Paradoxically, these “metal performances” also dramatize a return to nature and the animal
Managing the Flow of Construction Minerals in the North West Region of England
Authors: McEvoy Darryn , Ravetz Joe , Handley John
Published: November 2004

This article, focusing on the flow of bulk construction minerals, establishes a mass balance framework for the North West of England, a region that imports more aggregate material than any other in the United Kingdom. The problems associated with construction minerals are of a different nature than most other resource flow issues: Depletion of resources and contamination are not considered major problems; rather it is the environmental impact resulting from life‐cycle stages from extraction, transport, processing, through to final disposal that is most important. A mass balance framework can promote a better understanding of the regional flow of materials, and the impact of human activity on surrounding ecosystems, and hence underpin informed decision making. This is of particular relevance at the current time because increasing political emphasis is placed on sustainable resource management and resource productivity at the United Kingdom and European Union levels. Using a mass balance framework to analyze the sustainability impacts of construction and mineral flows in the North West of England, this study finds that flows resulting from construction activity account for 34,075 terajoules (TJ) of energy resulting in 2,701 gigagrams (Gg) of carbon dioxide emissions related to energy use, and 387 Gg of carbon dioxide emissions related to the transportation of the minerals. Against these impacts, the flow of bulk construction mineral salso supports 147,000 jobs within the region.
Students' Academic Performance: An Interaction of Inputs from the Students, Schools, and Voters
Authors: Koshal Rajindar , Koshal Manjulika , Gupta Ashok
Published: November 2004

This study proposes and tests a model affecting students' academic performance. We postulate that students' academic performance depends on the interaction of key factors associated with students, the schools, and the voters. The model incorporates variables such as the attendance rate, social and economic background of parents of the students, marital status of parents, expenditure per pupil that voters are willing to invest, proportion of school expenditure from local sources, and quality of teachers. Academic performance of students is measured by the percentage of total number of students passing all four parts of the proficiency test. The simultaneous-equations model is estimated by using data for 576 Ohio school districts. Our analysis suggests that an increased expenditure on education would improve the academic performance of the students. However, money alone is not sufficient. Our study implies that, along with the increased investment in education, a number of other socioeconomic variables need to be paid attention to. For example, an increase in the attendance rate of students can bring a substantial improvement in the academic performance of students. An improvement in attendance rate requires reduction in poverty and an increase in the percentage of families having two parents.
Mission As Service to Life: Reflections From an African Worldview
Authors: Ssettuuma Benedict
Published: November 2004

This article discusses mission as service to life. The author developing from the African worldview whose centrality is life, argues that the question of life permeates the history of salvation and is at the heart of the Christian mission as Jesus Christ the Perfect Revealer of God indicates ( John 10:10). The author concludes that life thus unites both the African worldview and the Christian mission; consequently mission becomes God's lifegiving activities directed to the world and the church's mandate of service to life under His guiding power. Such understanding gives new meaning to church activity in Africa and unites all her undertakings for this one purpose that all may come to get life to the full. It suggests that all that is anti-life is to be fought and rejected while all that is pro-life and leads all to acquire life in its fullness must be promoted and cultivated.
The Correlates of Nuclear Proliferation
Authors: Singh Sonali , Way Christopher R.
Published: November 2004

Fears of rogue states, withdrawal of cold war-era security guarantees, a falling technological threshold, and availability to terrorist organizations ensure that nuclear weapons proliferation remains a central security issue and that developing an adequate theory of proliferation ranks high on the agenda. A data set on nuclear proliferation is constructed that identifies three different stages on the path to the weaponization of nuclear weapons technology. Hazard models and multinomial logit are used to test theories of nuclear proliferation. Results suggest that nuclear weapons proliferation is strongly associated with the level of economic development, the external threat environment, lack of great-power security guarantees, and a low level of integration in the world economy.
Medical Malpractice in Correctional Facilities: State Tort Remedies for Inappropriate and Inadequate Health Care Administered to Prisoners
Authors: Vaughn Michael S. , Collins Sue Carter
Published: November 2004

This article reviews state tort remedies assessed against correctional personnel for inappropriate and/or inadequate health care administered to prisoners. It reviews medical malpractice and negligence law generally and then applies these legal precepts to jail and prison health care legal actions. Through an inductive process, the cases from various state courts are divided into four categories: administration of inadequate or inappropriate medication, performance of inappropriate medical procedures, inappropriate diagnosis of serious medical conditions, and undertreatment of serious medical problems. The article concludes by calling for more research on health care within correctional settings.
Nursing Care and Context in Theresienstadt
Authors: Brush Barbara L.
Published: November 2004

Over the past 5 years, nurses’roles as caregivers in ghettos and concentration camps during the Third Reich increasingly have become the subject of interest. Historians have focused particularly on the ethical dilemmas of caregiving practices that often deviated from normal care standards and situations. This article examines nurses and their work in one concentration camp, Theresienstadt, to demonstrate that even under the unique and horrible conditions of camp existence, contextual differences between camps provided nurses with different difficulties and opportunities. Although an extreme example, this article demonstrates the critical link between care and context as nurses practice across various settings and situations.
Effect of Environment and Research Participant Characteristics on Data Quality
Authors: Drew Barbara L. , Mion Lorraine C. , Meldon Stephen W. , Khalil Mazen Y. , Beaver Andrew , Ghazal-Haddad Lisa
Published: November 2004

The purpose of this study, a component of a randomized clinical trial, was to assess the influence of the emergency department environment and participant characteristics on the accuracy of self-reported health care utilization. Interviews of 612 seniors aged 65 to 93 were conducted in two emergency departments. The research assistant, upon completion of each interview, rated characteristics of the emergency department and compared participants’ self-reports of emergency department use and hospitalization during the previous 4 weeks with data from hospital records: 3.6% overreported and 2.2% underreported visits to the emergency department. Regarding hospitalizations, 2.6% overreported and 1.2% underreported. Discrepancies were associated with male gender, cognitive deficits, and risk status. Inconsistencies were not related to any of the environmental variables. These findings suggest that seniors without cognitive decline report reliable data even in a potentially challenging environment.
The Relationship Between Malingerers’ Intelligence and MMPI-2 Knowledge and Their Ability to Avoid Detection
Authors: Pelfrey William V.
Published: November 2004

One of the most frequently administered psychometrics is the Minnesota Multiphasic Personality Inventory-2 (MMPI-2). Occasionally, those participants taking the MMPI-2 will malinger or exaggerate their symptoms. Several malingering detection devices are available, and a significant body of literature exists concerning their efficacy. However, little research is available considering those factors that facilitate successfully evading detection as a malingerer. Some of these studies have identified general intelligence and knowledge of the MMPI-2 as key variables in the likelihood of escaping detection as a malingerer. The extant research considered the utility of general intelligence and knowledge of the MMPI-2 as predictors in avoiding detection as a malingerer. To detect malingering, the two traditional detection devices were employed: the F-Scale and the F - K Index. Results indicate that intelligence and MMPI-2 knowledge contribute significantly to the likelihood of successfully escaping detection as a malingerer.
Experiential learning: Introducing faculty and staff to a university leadership development program
Authors: Hornyak Martin J. , Page Diana
Published: November 2004

This description explores a form of experiential learning using specific outdoor learning activities in a higher education setting to introduce participants to each other and to build a team in a leadership program. Participants in the Leadership Enhancement and Development Program(LEAD) created at the University of West Florida (UWF) include both faculty and staff members.
Clarity Across the Disciplines
Authors: Hartley James , Sotto Eric , Fox Claire
Published: November 2004

Computer-based readability measures were used to examine the clarity of texts written in the sciences, the social sciences, and the arts and humanities. Five studies examined texts that were written in these different disciplines for different audiences, moving from fellow researchers to students and the general public. Readability increased across these genres until it reached an asymptote. In several cases, the scientific texts used shorter sentences and were easier to read than were their parallel texts in the other disciplines.
Inhibition of Wnt/Axin/β-catenin pathway activity promotes ventral CNS midline tissue to adopt hypothalamic rather than floorplate identity
Authors: Kapsimali Marika , Caneparo Luca , Houart Corinne , Wilson Stephen W.
Published: November 2004

Ventral midline cells in the neural tube form floorplate throughout most of the central nervous system (CNS) but in the anterior forebrain, they differentiate with hypothalamic identity. The signalling pathways responsible for subdivision of midline neural tissue into hypothalamic and floorplate domains are uncertain, and in this study, we have explored the role of the Wnt/Axin/β-catenin pathway in this process. This pathway has been implicated in anteroposterior regionalisation of the dorsal neural tube but its role in patterning ventral midline tissue has not been rigorously assessed.

We find that masterblind zebrafish embryos that carry a mutation in Axin1, an intracellular negative regulator of Wnt pathway activity, show an expansion of prospective floorplate coupled with a reduction of prospective hypothalamic tissue. Complementing this observation, transplantation of cells overexpressing axin1 into the prospective floorplate leads to induction of hypothalamic gene expression and suppression of floorplate marker gene expression. Axin1 is more efficient at inducing hypothalamic markers than several other Wnt pathway antagonists, and we present data suggesting that this may be due to an ability to promote Nodal signalling in addition to suppressing Wnt activity. Indeed, extracellular Wnt antagonists can promote hypothalamic gene expression when co-expressed with a modified form of Madh2 that activates Nodal signalling. These results suggest that Nodal signalling promotes the ability of cells to incorporate into ventral midline tissue, and within this tissue, antagonism of Wnt signalling promotes the acquisition of hypothalamic identity. Wnt signalling also affects patterning within the hypothalamus, suggesting that this pathway is involved in both the initial anteroposterior subdivision of ventral CNS midline fates and in the subsequent regionalisation of the hypothalamus. We suggest that by regulating the response of midline cells to signals that induce ventral fates, Axin1 and other modulators of Wnt pathway activity provide a mechanism by which cells can integrate dorsoventral and anteroposterior patterning information.
Coupling segmentation to axis formation
Authors: Dubrulle Julien , Pourquié Olivier
Published: November 2004

A characteristic feature of the vertebrate body is its segmentation along the anteroposterior axis, as illustrated by the repetition of vertebrae that form the vertebral column. The vertebrae and their associated muscles derive from metameric structures of mesodermal origin, the somites. The segmentation of the body is established by somitogenesis, during which somites form sequentially in a rhythmic fashion from the presomitic mesoderm. This review highlights recent findings that show how dynamic gradients of morphogens and retinoic acid, coupled to a molecular oscillator, drive the formation of somites and link somitogenesis to the elongation of the anteroposterior axis.
Segment-specific prevention of pioneer neuron apoptosis by cell-autonomous, postmitotic Hox gene activity
Authors: Miguel-Aliaga Irene , Thor Stefan
Published: November 2004

In vertebrates, neurons often undergo apoptosis after differentiating and extending their axons. By contrast, in the developing nervous system of invertebrate embryos apoptosis typically occurs soon after cells are generated. Here, we show that the Drosophila dMP2 and MP1 pioneer neurons undergo segment-specific apoptosis at late embryonic stages, long after they have extended their axons and have performed their pioneering role in guiding follower axons. This segmental specificity is achieved by differential expression of the Hox gene Abdominal B, which in posterior segments prevents pioneer neuron death postmitotically and cell-autonomously by repressing the RHG-motif cell death activators reaper and grim. Our results identify the first clear case of a cell-autonomous and anti-apoptotic role for a Hox gene in vivo. In addition, they provide a novel mechanism linking Hox positional information to differences in neuronal architecture along the anteroposterior axis by the selective elimination of mature neurons.
The Drosophila MBD2/3 protein mediates interactions between the MI-2 chromatin complex and CpT/A-methylated DNA
Authors: Marhold Joachim , Kramer Katja , Kremmer Elisabeth , Lyko Frank
Published: November 2004

Methyl-DNA binding proteins play an important role in epigenetic gene regulation. The Drosophila genome encodes a single protein (MBD2/3)with extended homologies to the vertebrate methyl-DNA binding proteins MBD2 and MBD3. However, very little is known about its functional properties. We have now characterized an MBD2/3 null mutant allele that is viable and fertile. This mutation caused a strong dominant suppression of position-effect variegation and also resulted in a high rate of chromosome segregation defects during early embryogenesis. Confocal analysis of mutant embryos showed local displacement of MI-2 from DNA and indicated that MBD2/3 is associated with only a subset of MI-2 complexes. In addition, band shift experiments demonstrated a specific binding of MBD2/3 to CpT/A-methylated DNA, which reflects the endogenous DNA methylation pattern of Drosophila.Consistently, the localization of MBD2/3 was disrupted in embryos with reduced levels of DNA methylation. Our data provide novel insights into the function of MBD2/3 proteins and strongly suggest the existence of methylation-dependent chromatin structures in Drosophila.
Observation of Coherent Recurrence Motion of Excitons in Anthracene Dimers
Authors: Yamazaki Iwao , Akimoto Seiji , Aratani Naoki , Osuka Atsuhiro
Published: November 2004

Intramolecular electronic excitation transfer in anthracene dimers in solution at room temperature has been investigated by probing the fluorescence anisotropy decay with a femtosecond up-conversion method. Two types of anthracene dimers were used: anthracenophane (DTA) in which two anthracene rings are stacked parallel, but with nearly orthogonal orientation, and two dianthrylbenzenes (m- and o-DAB) in which two anthracene rings are linked to a benzene ring at meta- and ortho-positions. There appeared damped oscillations of apparent periods of 0.6–1.0 ps and damping time constants of 0.7–1.2 ps. The ordinary fluorescence decay (excited-state population decay) obtained with the magic angle excitation exhibits no oscillation in all the cases. It has been found from a theoretical analysis that the oscillatory behaviors on fluorescence anisotropy are consistent with the coherent recurrence motion of an exciton between two anthracene moieties. The magnitudes of the dipole–dipole energy transfer interaction are estimated to be 10–80 cm−1, which are considerably smaller than the experimental value (30–100 cm−1) deduced from the angular frequencies of oscillation. This means that some interchromophore interaction other than the dipole–dipole resonance interaction is involved in the energy transfer interaction in strongly coupled dimers. The longer dephasing time can be explained as a consequence of rigid dimeric conformations in anthracene dimers.
Reaction Rate Spectroscopy for a Catalyzed Reaction of Gases
Authors: Yasuda Yusuke , Matsumoto Akira , Oda Ryo
Published: November 2004

A “reaction rate spectroscopy” available for a catalyzed reaction of gases is proposed on the basis of a frequency response method by which the flow of Gibbs free energy along a reaction coordinate τ, J(τ) (≡[−dG/dt]τ), can be determined. The validity was confirmed by actual data obtained in a reaction of CO(g) + (1/2)O2(g) → CO2(g) (I) on Pt/Al2O3, Ru/Al2O3, and Cu pellets at 623 K under partial pressures of ca. 100 Pa. The Gibbs free energy drop in the reaction (I), −ΔgT (> 0), was found to be divided into two parts, x(−ΔgT) and y(−ΔgT) (x + y = 1), concerning the parallel transformations of the two reactants, (i) CO(g) → CO2(g) and (ii) (1/2)O2(g) → CO2(g), respectively: y = 0.158 (on Pt), 0.124 (Ru), and 0.021 (Cu). Both transformations were assumed to occur via three elementary steps accompanied by two intermediates, A and B, represented by (i) CO(X) ↔ CO(AX) ↔ CO(BX) → CO2(ZX) and (ii) (1/2)O2(Y) ↔ (1/2)O2(AY) ↔ O(BY) → CO2(ZY). Changes in J(τ) in the course of (i) and (ii), δJX(τn) (≡JX(τn) − JX(τn−1)) and δJY(τn), respectively, were determined along the reaction coordinate τn (n = 1–5; n corresponds to the three steps and two intermediates). Although both δJX(τn) and δJY(τn) were either negative or positive, the sum of δJX(τn) + δJY(τn) was negative throughout the reaction, in agreement with the second law of thermodynamics.
Adsorption Equilibria of Novel Phthalocyaninatomagnesium(II) Derivatives with Thioethers at the Toluene/Water Interface
Authors: Adachi Kenta , Watarai Hitoshi
Published: November 2004

Three novel phthalocyaninatomagnesium(II) derivatives with eight peripheral thioethers (MgPc(SR)8) such as (2,3,9,10,16,17,23,24-octakis-ethylthiophthalocyaninato)magnesium(II) (MgPc(SEt)8), (2,3,9,10,16,17,23,24-octakis-benzylthiophthalocyaninato)magnesium(II) (MgPc(SBz)8), and (2,3,9,10,16,17,23,24-octakis-benzhydrylthiophthalocyaninato)magnesium(II) (MgPc(SBh)8) were synthesized. The interfacial adsorption and aggregation behavior of the three derivatives in a toluene/water system were examined by means of a high-speed stirring (HSS) method and a centrifugal liquid membrane (CLM) method. The interfacial adsorption constant of each MgPc(SR)8 derivative at the toluene/water interface was determined by the HSS measurement. Only in the case of MgPc(SEt)8, the formation of the trimer was observed at the interface. Moreover, the CLM measurements showed that the interfacial aggregate of MgPc(SEt)8 had a new broad band (613 nm) at the blue flank of the Q band (702 nm) of MgPc(SEt)8 monomer, which might be ascribed to H-aggregate. Extended double-dipole (EDD) model calculations suggested a cofacially stacked arrangement of MgPc(SEt)8 molecules in the trimer. The interfacial spectral change indicated that the aggregation of MgPc(SEt)8 at the toluene/water interface proceeded in a two-step, three-stage (monomer → dimer → trimer) formation.
Potentiometric Study on Interaction of Dodecyltrimethylammonium Bromide with α-Amylase
Authors: Bordbar Abdol-Khalegh , Hosseinzadeh Reza , Omidiyan Khodayar
Published: November 2004

The binding of dodecyltrimethylammonium bromide (DTAB) with α-amylase was investigated under various experimental conditions, such as pH, ionic strength, urea and protein concentration at 25 °C using surfactant membrane-selective electrodes as a fast and accurate method. The obtained binding isotherms have been analyzed and interpreted using the Wyman binding potential concept. The results represent: a) the self aggregation of protein that occurs at enzyme concentrations of more than 1 mg/mL (this observation was also confirmed by light-scattering measurements), b) the binding affinity at 10−3 M NaBr is more than other salt concentrations, and c) in the concentration range of 3 to 5 M of urea a predominant unfolding of protein occurs.
Absolute Stereochemisty and Chiroptical Properties of 3,3′-Bis(methoxycarbonyl)-9,9′-bianthryl
Authors: Toyota Shinji , Shimasaki Toshiaki , Ueda Takashi , Tanifuji Naoki , Wakamatsu Kan
Published: November 2004

The axially chiral title compound was enantiomerically resolved by the diastereomer method via the camphorsultamamide of the corresponding dicarboxylic acid. The absolute stereochemistry of the (+)- and (−)-forms ([α]D +32 and −33) was determined by X-ray analysis of one of the diastereomers of the sultamamide to be P and M, respectively, for the helicity about the C9–C9′ bond. The observed CD and UV spectra were reasonably reproduced by the theoretical calculation based on the time-dependent density functional theory (TDDFT). The CD spectrum of the (M)-(−) form features a split curve around 270 nm assignable to the exciton coupling of the β transition and a broad p band peak around 380 nm.
Preparation of Polystyrene-Bound Dichlorotitanium Dialkoxide and Its Application as a Polymer-Supported Lewis Acid Catalyst in Organic Syntheses
Authors: Fujita Ken-ichi , Muraki Takahito , Hashimoto Shigeru , Oishi Akihiro , Taguchi Yoichi
Published: November 2004

Polymer-supported dichlorotitanium dialkoxide was readily prepared from polystyrene-bound α-glycol and dichlorotitanium diisopropoxide. When we employed it as an immobilized Lewis acid catalyst, several fundamental and important Lewis acid-catalyzed reactions proceeded smoothly with fair chemical yields.
The Synthesis and Phosphate Adsorptive Properties of Mg(II)–Mn(III) Layered Double Hydroxides and Their Heat-Treated Materials
Authors: Tezuka Satoko , Chitrakar Ramesh , Sakane Kohji , Sonoda Akinari , Ooi Kenta , Tomida Tahei
Published: November 2004

Hydrotalcite-like layered double hydroxides (LDHs) of Mg(II) and Mn(III) were prepared by a co-precipitation/air oxidation method using MgCl2 and MnCl2 as starting materials. Syntheses were studied at different precipitation temperatures and variable starting Mg/Mn ratios. MgMn-LDH were obtained at a preparation temperature below 333 K. Samples prepared at a Mg/Mn ratio of 3 showed a crystalline LDH phase having a basal spacing of 7.85 Å. The LDH prepared at lower Mg/Mn ratios had slightly less crystalline phase, with lower basal spacing. Calcination of MgMn-LDH at 573 K for 4 h in air resulted in a transformation from a layered to an amorphous phase, accompanied by a loss of interlayer water and a partial loss of carbonate ions. Chemical analysis and IR studies showed that oxidation from Mn(III) to Mn(IV) progressed during the calcinations, and that HCO3− was formed in the calcined solid. Equilibrium distribution coefficients (Kd) of different kinds of anions were measured for the uncalcined and calcined samples. The selectivity sequences were Cl− < NO3− < SO42− < HPO42− and Cl−, NO3−, SO42− << HPO42− for the uncalcined and calcined ones, respectively. The latter had specific selectivity for phosphate ions. The calcined sample showed a maximum phosphate uptake of 1.1 mmol-P/g at a pH around of 8. The pH titration study of the supernatant solution suggested that the phosphate adsorption progresses mainly through the HCO3−/HPO42− ion exchange reaction.
The Role of Volition in Organizational Learning: The Case of Automotive Product Recalls
Authors: Haunschild Pamela R. , Rhee Mooweon
Published: November 2004

What is the role of volition in organizational learning? Do firms learn better in response to internal procedures or external mandates? Existing literature provides conflicting answers to this question, with some theories suggesting that volition is important for learning because autonomy increases commitment and problem analyses, whereas external mandates tend to produce defensive reactions that are not coupled to the organization in any useful way. Yet, other theories suggest that mandate is important for learning because external pressures act as jolts that help overcome organizational inertia, resulting in deep exploration of problems to prevent future surprises. We investigate this issue in the context of automakers learning from voluntary versus involuntary product recalls. Using data on all recalls experienced by automakers that sold passenger cars in the United States during the 1966–1999 period, we follow the learning-curve tradition in investigating the effects of voluntary and involuntary recalls on subsequent recall rates. We find that voluntary recalls result in more learning than mandated recalls when learning is measured as a reduction in subsequent involuntary recalls. This effect is at least partly because of shallower learning processes that result from involuntary recalls. The effect of volition, however, is different for generalist and specialist automakers. The results of this study suggest an important, yet understudied, determinant of the rate and effectiveness of learning—volition. The results also add to our knowledge of the different learning processes of generalist and specialist organizations.
Managing Knowledge-Based Resource Capabilities Under Uncertainty
Authors: Carrillo Janice E. , Gaimon Cheryl
Published: November 2004

A firm's ability to manage its knowledge-based resource capabilities has become increasingly important as a result of performance threats triggered by technology change and intense competition. At the manufacturing plant level, we focus on three repositories of knowledge that drive performance. First, the physical production or information systems represent knowledge embedded in the plant's technical systems. Second, the plant's workforce has knowledge, including diverse scientific information and skills, to effectively operate the technical systems. Third, the firm's managerial systems embody knowledge in the form of goals, reward systems, and control and coordination systems. Taken together, we consider the technical systems, workforce knowledge, and the managerial systems as the plant's knowledge-based resource capability.

Two normative models are introduced offering insight on how plant performance is impacted by investments in workforce knowledge (training) or the technical systems (process change). The models explicitly recognize that the outcome of investments in knowledge-based change is uncertain due to factors including technical problems, worker resistance, and limited financial resources. Also, we recognize that workforce knowledge may be deployed to mitigate the outcome uncertainty encountered with process change.

Investments in knowledge-based change cannot be fully understood in isolation of the managerial systems. In one model, the plant manager is motivated by an incentive system that rewards the realization of a threshold goal, whereas in the other model the incentive system emphasizes the realization of meeting a particular target goal. We also investigate the impact of the manager's view of uncertainty (her willingness to absorb risk), which is influenced by the managerial systems. Results show that different characterizations of the managerial systems have a profound effect on managerial behavior and plant-level performance.
Arbitrage in a Discrete Version of the Wick-Fractional Black-Scholes Market
Authors: Bender Christian , Elliott Robert J.
Published: November 2004

We consider binary market models based on the discrete Wick product instead of the pathwise product and provide a sufficient criterion for the existence of an arbitrage. This arbitrage is explicitly constructed in the class of self-financing one-step buy-and-hold strategies, (i.e., the investor holds shares of the stock only at one time step). Using coefficients obtained from an approximation of a fractional Brownian motion with Hurst parameter ½ < H < 1 the result is applied to a discrete version of the (Wick-)fractional Black-Scholes market.
Existence and Properties of Optimal Production and Inventory Policies
Authors: Sun Daning
Published: November 2004

It is an important and fundamental question whether an optimal inventory policy exists for a general deterministic multi-item, multistage (GDMM) production and inventory model. We show that an inventory model with a nonsubadditive ordering cost function could have no optimal policy over a finite horizon. However, when the ordering cost is a subadditive function an optimal policy exists for a GDMM production and inventory model over both a finite horizon and an infinite horizon. Properties of optimal inventory policies are crucial to investigating an inventory problem. We present four properties of optimal policies: (1) nonpositive inventory ordering, (2) last-minute ordering, (3) extended last-minute ordering, and (4) nonnegative filling properties. They have been explicitly or implicitly used in analyzing many different inventory models. The last two properties have been used but not proved before.
Asymptotic Values of Vector Measure Games
Authors: Neyman Abraham , Smorodinsky Rann
Published: November 2004

In honor of L. S. Shapley's eightieth birthday

The asymptotic value, introduced by Kannai in 1966, is an asymptotic approach to the notion of the Shapley value for games with infinitely many players. A vector measure game is a game v where the worth v(S) of a coalition S is a function f of μ(S) where μ is a vector measure. Special classes of vector measure games are the weighted majority games and the two-house weighted majority games, where a two-house weighted majority game is a game in which a coalition is winning if and only if it is winning in two given weighted majority games. All weighted majority games have an asymptotic value. However, not all two-house weighted majority games have an asymptotic value. In this paper, we prove that the existence of infinitely many atoms with sufficient variety suffice for the existence of the asymptotic value in a general class of nonsmooth vector measure games that includes in particular two-house weighted majority games.
Patient Choice in Kidney Allocation: The Role of the Queueing Discipline
Authors: Su Xuanming , Zenios Stefanos
Published: November 2004

This paper develops and analyzes a queueing model to examine the role of patient choice on the high rate of organ refusals in the kidney transplant waiting system. The model is an M/M/1 queue with homogeneous patients and exponential reneging. Patients join the waiting system and organ transplants are reflected by the service process. In addition, unlike the standard M/M/1 model, each service instance is associated with a variable reward that reflects the quality of the transplant organ, and patients have the option to refuse an organ (service) offer if they expect future offers to be better. Under an assumption of perfect and complete information, it is demonstrated that the queueing discipline is a potent instrument that can be used to maximize social welfare. In particular, first-come-first-serve (FCFS) amplifies patients' desire to refuse offers of marginal quality, and generates excessive organ wastage. By contrast, last-come-first-serve (LCFS) contains the inefficiencies engendered by patient choice and achieves optimal organ utilization. A numerical example calibrated using data from the U.S. transplantation system demonstrates that the welfare improvements possible from a better control of patient choice are equivalent to a 25% increase in the supply of organs.
In This Issue
Authors: van Ryzin Garrett J.
Published: November 2004

A regular feature of Manufacturing & Service Operations Management, “In This Issue” briefly describes each issue's articles and highlights their contributions.
Effects of Processing and Storage Conditions on Amyloid β (1–42) and Tau Concentrations in Cerebrospinal Fluid: Implications for Use in Clinical Practice
Authors: Schoonenboom Niki SM , Mulder Cees , Vanderstichele Hugo , Van Elk Evert-Jan , Kok Astrid , Van Kamp Gerard J , Scheltens Philip , Blankenstein Marinus A
Published: November 2004

Background: Reported concentrations of amyloid β (1–42) (Aβ42) and tau in cerebrospinal fluid (CSF) differ among reports. We investigated the effects of storage temperature, repeated freeze/thaw cycles, and centrifugation on the concentrations of Aβ42 and tau in CSF.

Methods: Stability of samples stored at −80 °C was determined by use of an accelerated stability testing protocol according to the Arrhenius equation. Aβ42 and tau concentrations were measured in CSF samples stored at 4, 18, 37, and −80 °C. Relative CSF concentrations (%) of the biomarkers after one freeze/thaw cycle were compared with those after two, three, four, five, and six freeze/thaw cycles. In addition, relative Aβ42 and tau concentrations in samples not centrifuged were compared with samples centrifuged after 1, 4, 48, and 72 h.

Results: Aβ42 and tau concentrations were stable in CSF when stored for a long period at −80 °C. CSF Aβ42 decreased by 20% during the first 2 days at 4, 18, and 37 °C compared with −80 °C. CSF tau decreased after storage for 12 days at 37 °C. After three freeze/thaw cycles, CSF Aβ42 decreased 20%. CSF tau was stable during six freeze/thaw cycles. Centrifugation did not influence the biomarker concentrations.

Conclusions: Repeated freeze/thaw cycles and storage at 4, 18, and 37 °C influence the quantitative result of the Aβ42 test. Preferably, samples should be stored at −80 °C immediately after collection.
Piecewise-smooth surfaces as the union of geodesic disks
Authors: Goodman-Strauss C.
Published: November 2004

We consider a question of G. Fejes Tóth, whether the boundary of a convex body can be the union of three geodesic disks with disjoint interior.
Sensitivity of Phage Lambda upon Variations of the Gibbs Free Energy
Authors: Bakk Audun , Metzler Ralf , Sneppen Kim
Published: November 2004

We investigate the sensitivity of production rates (activities) of the regulatory proteins CI (repressor) and Cro at the right operator (OR) of bacteriophage lambda. The DNA binding energies of CI, Cro, and RNA polymerase are perturbed to check the uncertainty of the activity, due to the experimental error, by means of a computational scattering method according to which the binding energies are simultaneously chosen at random around the literature values, with a width corresponding to the experimental error. In a grand canonical ensemble, with the randomly drawn protein‐DNA binding energies as input, we calculate the corresponding activities of the promoters PRM and PR. By repeating this procedure we obtain a mean value of the activity that roughly corresponds to wild‐type (unperturbed) activity. The standard deviation emerging from this scheme, a measure of the sensitivity due to experimental error, is significant (typically >20% relative to wild‐type activity), but still the promoter activities are sufficiently separated to make the switch feasible. We also suggest a new, compact way of presenting repressor and Cro data.
Temperature‐Dependent Solvent Polarity Effects on Adiabatic Proton Transfer Rate Constants and Kinetic Isotope Effects
Authors: Kiefer Philip M. , Hynes James T.
Published: November 2004

Temperature‐dependent solvent polarity effects are presented for proton transfer (PT) reactions in a polar environment in the proton adiabatic regime, in which proton motion is quantum mechanical, but is not tunneling. In this adiabatic perspective, the reaction activation free energy barrier ΔG‡ is in the solvent coordinate, with contributions due to proton and hydrogen bond vibration zero point energy, and is strongly dependent on the polarity of the solvent. In particular, the consequences of the feature that solvent polarity decreases with increasing temperature is explored within this nontraditional PT picture, via a continuum dielectric solvent model. For an acid ionization PT reaction, the activation free energy barrier increases with increasing temperature due to the solvent polarity's temperature dependence (although the so‐called intrinsic barrier and reorganization energy for the thermodynamically symmetric reaction varies in the opposite direction). The resulting PT rate constant k has a reduced effective activation energy in an Arrhenius plot due to the temperature‐dependent solvent polarity effect; this differs from the activation free energy via an activation entropy effect. The Arrhenius behavior of the kinetic isotope effect kH/kD is, however, largely unchanged by the solvent polarity's temperature dependence due to a cancellation of effects between isotopes. Some further consequences of the solvent polarity's temperature dependence for adiabatic PT systems are discussed.
Laser Infrared Multiphoton Noncoherent Control of Intermolecular (Isotope) Selectivity for Polyatomic Molecules on a Practical Scale
Authors: Letokhov Vladilen S. , Ryabov Evgeny A.
Published: November 2004

This paper discusses methods for noncoherent laser control of molecules, based on intermolecular selectivity of their excitation and dissociation by laser radiation, describes the technology developed for laser separation of carbon isotopes, based on the IR multiphoton dissociation of Freon‐22 molecules by CO2 laser radiation, and presents the results of developing a two‐stage laser process for the production of highly enriched (⩾ 99%) carbon‐13.
Effect of Hydrogen Bonding on Barrier‐Free Proton Transfer in Anionic Complexes of Uracil with Weak Acids: (U…HCN)− versus (U…H2S)−
Authors: Harańczyk Maciej , Rak Janusz , Gutowski Maciej , Radisic Dunja , Stokes Sarah T. , Bowen Kit H.
Published: November 2004

A photoelectron spectrum is reported for an anionic complex of uracil (U) with HCN. The effects of electron attachment to a complex of U with HA (A = CN, NC) have been studied at the density functional theory level with 6–31++G** basis sets and the B3LYP and MPW1K exchange correlation functionals. Critical anionic structures have been reexamined at the MP2/6–31++G** level. The B3LYP gas‐phase deprotonation enthalpies are equal to 14.56, 15.13, and 15.12 eV for HNC, HCN, and H2S, respectively. The experimental deprotonation enthalpies are 15.217 ± 0.009 and 15.212 ± 0.126 eV for HCN and H2S, respectively. Hence, HCN and H2S have very indeed similar deprotonation enthalpies. The photoelectron spectra of anionic complexes of uracil with HCN and H2S are, however, very different. The (UHCN)− spectrum reveals a broad feature with a maximum between 1.2–1.4 eV, whereas the main feature of the (UH2S)− spectrum has a maximum between 1.7 and 2.1 eV. We suggest that barrier‐free proton transfer (BFPT) occurs in the (UH2S)−complex, but not in (UHCN)−. Critical factors for the occurrence of BFPT have been analyzed. The difference between the (UHCN)− and (UH2S)− complexes is attributed to differences in hydrogen bonds formed by HCN and H2S with uracil.