bluuebunny/crossref_metadata_2025 huggingface dataset:
Medial temporal and prefrontal contributions to working memory tasks with novel and familiar stimuli
Authors: Stern Chantal E. , Sherman Seth J. , Kirchhoff Brenda A. , Hasselmo Michael E.
Published: November 2004

Lesions of parahippocampal structures impair performance of delayed matching tasks in nonhuman primates, suggesting a role for these structures in the maintenance of items in working memory and short‐term stimulus matching. However, most human functional imaging studies have not shown medial temporal activation during working memory tasks and have primarily focused on functional magnetic resonance imaging (fMRI) signal intensity changes in the prefrontal and posterior parietal cortex. The goal of this study was to test the hypothesis that the difference between the human and nonhuman primate data results from the use of highly familiar stimuli in human working memory studies and trial‐unique stimuli in nonhuman primate studies. We used fMRI to examine prefrontal and temporal lobe activation during performance of a working memory (two‐back) task, using blocks of novel and highly familiar complex pictures. Performance of the working memory task with novel complex pictures resulted in greater signal change within medial temporal lobe structures than performance of the task with familiar complex pictures. In contrast, the working memory task with highly familiar stimuli resulted in greater prefrontal activation. These results are consistent with‐ out hypothesis that the medial temporal lobe is recruited for the short‐term maintenance of information that has no prior representation in the brain, whereas the prefrontal cortex is important for monitoring familiar stimuli that have a high degree of interference. A second set of tasks examined stimulus matching. Subjects performed a target‐matching task, during which they identified a single target presented in blocks of novel or familiar stimuli. The results provide evidence of hippocampal and parahippocampal recruitment in the target‐matching task with familiar stimuli. These results are consistent with prior animal studies and suggest that prefrontal regions may be important for the monitoring and matching of familiar stimuli which have a high potential for interference, whereas medial temporal regions may become proportionally more important for matching and maintenance of novel stimuli. Hippocampus 2001;11:337–346. © 2001 Wiley‐Liss, Inc.
MRI‐based evaluation of locus and extent of neurotoxic lesions in monkeys
Authors: Málková Ludiše , Lex Carolyn K. , Mishkin Mortimer , Saunders Richard C.
Published: November 2004

To minimize the variability in the extent of lesions made by injections of the excitotoxin ibotenic acid in rhesus monkeys, we developed and validated an MRI‐based method to determine the efficacy of the injections soon after surgery. T2‐weighted MR images were obtained 6–11 days after surgery from 17 brain hemispheres of monkeys that had received bilateral lesions of either the hippocampal formation (HF), perirhinal cortex, or parahippocampal cortex. The extent of lesion estimated from the hypersignal that appeared in and outside of the targeted area on these MR images was compared with the extent of damage assessed histologically after survival periods ranging from 120–370 days. Highly significant correlations (r values between 0.85–0.99) were found between these two measures for several regions in the medial temporal lobe. Based on this finding, lack of hypersignal in the targeted area of some Ss was followed by successful reinjection of the neurotoxin to create more complete cell loss prior to the postoperative phase of the study. We also assessed the relationship between a postoperative reduction in HF volume, measured from T1‐weighted MR images, and the extent of damage determined histologically in 14 hemispheres of monkeys with bilateral excitotoxic HF lesions. The HF volume decreases sharply after surgery until 40–50 days postoperatively, after which there is only a minor further decrease. Based on this finding, we obtained T1‐weighted MR images at least 44 days but in most cases close to 1 year after surgery. A highly significant positive correlation (r = 0.95, P < 0.001) was found between neuronal damage and volume reduction, with nearly complete neuronal damage (96–99%) corresponding to a volume reduction of 68–79%. These MRI‐based methods thus provide an accurate in vivo evaluation of the locus and extent of neurotoxic lesions. Application of these methods can ensure that each animal in the experiment is used effectively. Hippocampus 2001;11:361–370. Published 2001 Wiley‐Liss, Inc.
Evidence for a relationship between place‐cell spatial firing and spatial memory performance
Authors: Lenck‐Santini Pierre‐Pascal , Save Etienne , Poucet Bruno
Published: November 2004

The rat hippocampus contains place cells whose firing is location‐specific. Although many properties of place cells have been uncovered, little is known about their actual contribution to the animal's spatial performance. In this study, we addressed this issue by recording place cells while rats solved a continuous spatial alternation task in which they had to alternate between the two arms of a Y‐maze to get a food reward in the third (goal) arm. By manipulating the information available to the animals, we induced the cells to establish their fields in locations that were out of register relative to their standard position, thus making them inconsistent with the learned spatial task. When this happened, the rats' performance in the alternation task was markedly decreased. In addition, the nature of the behavioral errors during inconsistent field placements also changed dramatically in a way that was highly indicative of the rats' spatial disorientation. These results suggest that there is a functional relationship between the spatial firing patterns of place cells and the spatial behavior of the rat, thus strengthening the idea that these cells are part of a navigational system. Hippocampus 2001;11:377–390. © 2001 Wiley‐Liss, Inc.
Entorhinal cortex of the mouse: Cytoarchitectonical organization
Authors: van Groen Thomas
Published: November 2004

The present study describes the cytoarchitectonical and chemoarchitectonical organization of the entorhinal cortex of the mouse (C57BL/6J strain). The entorhinal cortex is medially bordered by the parasubiculum, and laterally by the perirhinal cortex; rostrally and medially it is bordered by the piriform cortex, whereas caudally and dorsally it is bordered by the postrhinal cortex. The entorhinal cortex is divided into two main areas, i.e., the lateral entorhinal area (LEA) and the medial entorhinal area (MEA). Both entorhinal areas are further divided into subfields, i.e., LEA is divided into DLE (dorsolateral entorhinal field), DIE (dorsal intermediate entorhinal field), and VIE (ventral intermediate entorhinal field), whereas MEA is divided into CE (caudal entorhinal field) and ME (medial entorhinal field). Cytoarchitectonically, the main difference between LEA and MEA is displayed by layer II neurons: while these are in a dense layer in LEA, they are more dispersed in MEA. Further, in LEA there is a relatively cell‐free zone between layers II and III; this zone is not present in MEA. Histochemically, in acetylcholinesterase (AChE)‐stained material, MEA is characterized by darker‐stained bands in the superficial layer (i.e., layer I) and in the lamina dissecans, in contrast to LEA, which is more evenly stained for AChE. Further, both the border with the perirhinal cortex and the border with the parasubiculum are characterized by dark‐stained bands of AChE. The border between the entorhinal cortex and perirhinal cortex is also easily distinguished in parvalbumin‐stained material; while the entorhinal cortex is darkly stained, the perirhinal cortex is lightly stained. In contrast, in sections stained for calretinin, the entorhinal cortex is more lightly stained than the parasubiculum, which has a darkly stained superficial layer, and a densely stained group of neurons in layer III. Hippocampus 2001;11:397–407. © 2001 Wiley‐Liss, Inc.
Circuit analysis of NMDAR hypofunction in the hippocampus, in vitro, and psychosis of schizophrenia†
Authors: Greene Robert
Published: November 2004

NMDA antagonists provide the best pharmacological model of psychosis‐related schizophrenia. Data from circuit analysis of the effects of the antagonism of NMDA receptors in the CA1 region of the hippocampus of rats in vitro suggest a hypothesis concerning cortical circuit dysfunction responsible for NMDA antagonist‐dependent psychosis, relevant to the psychosis associated with schizophrenia. The NMDA antagonists may act by causing a selective, partial, disinhibition of cortical projection cells. The effects are partially due to the partial role of NMDA‐dependent transmission in the excitatory glutamate drive of interneurons. Characterization of the selectivity is incomplete, but includes disinhibition of the recurrent inhibitory circuit and is concentration‐sensitive. It may result from differences in NMDA receptors (NMDARs) on interneurons. At higher concentrations, antagonism of all NMDA‐dependent transmission results in anesthesia. At low concentration, selective blockade of NMDA‐dependent LTP of the recurrent inhibitory circuit may disrupt particular aspects of information processing involving learning and/or memory, consistent with the generation of abnormal associations. An endogenous peptide, NAAG, is shown to antagonize NMDARs in a manner similar to known psychotogenic agents like ketamine or phencyclidine. Finally, mechanisms that could enhance NMDAR function are discussed as possible therapeutic strategies for psychosis. Hippocampus 2001;11:569–577. © 2001 Wiley‐Liss, Inc.
Clinical staging of prostate cancer: Reproducibility and clarification of issues
Authors: Campbell Timothy , Blasko John , Crawford E. David , Forman Jeffrey , Hanks Gerald , Kuban Deborah , Montie James , Moul Judd , Pollack Alan , Raghavan Derek , Ray Paul , Roach Mack , Steinberg Gary , Stone Nelson , Thompson Ian , Vogelzang Nicholas , Vijayakumar Srinivasan
Published: November 2004

The American Joint Committee on Cancer (AJCC) staging system for prostate cancer adopted in 1992 is based on tumor‐node‐metastasis (TNM) designations. It has been widely accepted for use in local and advanced disease. The purpose of this study was to assess reproducibility of staging among observers and to help clarify staging issues. Twelve prostate cancer cases were sent to 20 physicians with special expertise in prostate cancer including eight urologists, eight radiation oncologists, and four medical oncologists. Physicians were asked to assign a stage based on the 1992 AJCC clinical staging. The most frequently reported stage assigned to each case was taken to be the consensus. Agreement was the percentage of physicians who reported that particular stage. Seventy‐five percent of the physicians responded. The overall agreement for assignment of T stage was 63.9%. Differences were found by specialty for inclusion of available information in designating a T stage. The overall agreement for N stage was 73.8%. The most common designation was Nx regardless of availability of a computed tomography scan. The overall agreement for M stage was 76.6%. Without a bone scan the most common designation was Mx regardless of Gleason grade or prostate‐specific antigen (PSA). A frequent comment was that PSA was more indicative of disease extent than current clinical staging. The reproducibility of the 1992 clinical AJCC staging is poor even among experts in the field. This problem arises primarily from disagreement regarding which studies are included in assigning a stage. Some of these difficulties are addressed in the 1997 revision. However, the clinical staging does not address the true biological significance of disease in many instances. © 2001 Wiley‐Liss, Inc.
Intra‐ and intertumor heterogeneity in blood perfusion of human cervical cancer before treatment and after radiotherapy
Authors: Lyng Heidi , Vorren Ann O. , Sundfør Kolbein , Taksdal Ingeborg , Lien Hans H. , Kaalhus Olav , Rofstad Einar K.
Published: November 2004

Knowledge of the intratumor heterogeneity in blood perfusion may lead to increased understanding of tumor response to treatment. In the present work, absolute perfusion values, in units of ml/g·min, were determined in 20 tumor subregions of patients with cervical cancer before treatment (n = 12) and after 2 weeks of radiotherapy (n = 8), by using a method based on contrast‐enhanced magnetic resonance imaging. The aims were to evaluate the intratumor heterogeneity in perfusion in relation to the intertumor heterogeneity and to search for changes in the heterogeneities during the early phase of therapy. The intra‐ and intertumor heterogeneity in perfusion were estimated from components of one‐way analyses of variance. The mean perfusion differed significantly among the patients before treatment, ranging from 0.044 to 0.12 ml/g·min. Large differences in perfusion were also observed within individual tumors. The heterogeneity was largest in the best perfused tumors, perfusion values ranging, e.g., from 0.055 to 0.29 ml/g·min were observed. The intratumor heterogeneity was similar to the intertumor heterogeneity. The mean perfusion generally increased or tended to increase during radiotherapy, ranging from 0.064 ml/g·min to 0.13 ml/g·min after 2 weeks of treatment. There was a tendency of increased intratumor heterogeneity in perfusion after therapy, consistent with the higher mean value; a difference in perfusion of more than a factor of 10 was seen within some tumors. These results suggest that cervix tumors contain a significant amount of poorly perfused subregions with high treatment resistance. Moreover, the perfusion and perfusion heterogeneity may increase during the early phase of radiotherapy and influence tumor response. © 2001 Wiley‐Liss, Inc.
Role of astrocytes in trimethyltin neurotoxicity
Authors: Gunasekar Palur G. , Mickova Vera , Kotyzova Dana , Li Li , Borowitz Joseph L. , Eybl Vladislav , Isom Gary E.
Published: November 2004

Although the neurotoxicity of trimethyltin (TMT) is well known, mechanisms are still not clear. Glia have been proposed to mediate the toxic action of TMT on nerve cells. Accordingly, the effects of TMT were tested in primary neuronal cultures from rat cerebellum and compared to effects in astrocytes and mixed cultures. Neuronal damage observed following TMT exposure was less in the presence of astrocytes and astrocytes alone were resistant to TMT. Thus, astrocytes have a protective effect against TMT‐induced neurotoxicity. TMT caused an oxidative stress in granule cell cultures involving a variety of oxidative species ((O2)•−, H2O2, NO), but astrocytes were less sensitive to TMT‐induced oxidative species generation. Antioxidants, glutathione and 7‐nitroindazole attenuated neuronal cell death induced by TMT. It appears that oxidative stress mediates a large part of the destructive action of TMT in neuronal cultures. The presence of astrocytes appears to modulate TMT‐induced oxidative stress so that TMT causes only a small increase in lipid peroxidation in mouse brain after systemic administration. Thus, TMT induces a pronounced oxidative stress in cultured neurons, but when astrocytes are present, oxidative species play a lesser role in the neurotoxic action of TMT. © 2001 John Wiley & Sons, Inc. J Biochem Mol Toxicol 15:256–262, 2001
Sharp bounds for the number of 3‐independent partitions and the chromaticity of bipartite graphs
Authors: Dong F. M. , Koh K. M. , Teo K. L. , Little C. H. C. , Hendy M. D.
Published: November 2004

Given a graph G and an integer k ≥ 1, let α(G, k) denote the number of k‐independent partitions of G. Let 𝒦−s(p,q) (resp., 𝒦2−s(p,q)) denote the family of connected (resp., 2‐connected) graphs which are obtained from the complete bipartite graph Kp,q by deleting a set of s edges, where p ≥ q ≥ 2. This paper first gives a sharp upper bound for α(G,3), where G ∈ 𝒦 −s(p,q) and 0 ≤ s ≤ (p − 1)(q − 1) (resp., G ∈ 𝒦 2−s(p,q) and 0 ≤ s ≤ p + q − 4). These bounds are then used to show that if G ∈ 𝒦 −s(p,q) (resp., G ∈ 𝒦 2−s (p,q)), then the chromatic equivalence class of G is a subset of the union of the sets 𝒦−si(p+i,q−i) where max $\{-{s\over q-1},-{p-q\over 2}\}\!\le \,i \le{s\over p-1}$ and si = s − i(p−q+i) (resp., a subset of 𝒦2−s(p,q), where either 0 ≤ s ≤ q − 1, or s ≤ 2q − 3 and p ≥ q + 4). By applying these results, we show finally that any 2‐connected graph obtained from Kp,q by deleting a set of edges that forms a matching of size at most q − 1 or that induces a star is chromatically unique. © 2001 John Wiley & Sons, Inc. J Graph Theory 37: 48–77, 2001
On‐line preconcentration microliquid chromatography tandem mass spectrometric method for bradykinin analysis in plasma
Authors: Oosterkamp A. J. , Carrascal M. , Closa D. , Escolar G. , Gelpi E. , Abian J.
Published: November 2004

The practical limitations of miniaturized liquid chromatography (LC) methods for the analysis of endogenous peptides in plasma samples are studied. An automatic column switching method is used for on‐line micropreconcentration and microLC‐MS–MS (mass spectrometry) analysis of bradykinin and its metabolites in plasma. Both preconcentration (PC) and analytical columns were filled with C18 reversed phase due to the failure of anion exchange precolumns to retain bradykinins. The detection limit for bradykinin in water was 10 pmol/L (2 fmols on column) and a good linearity was found in the range 5–2000 fmols. In plasma, detection limit was 50 pmol/L (25 μL injected) with a linear response in the 100–2000 pmol/L range. Important rules for stable work were: (1) Cleaning the PC column after every run with pure acetonitrile (ACN) to eliminate organic matrix components; (2) to trap the more apolar organic matrix components on the analytical column to prevent their elution to the MS entrance; and (3) to set the electrospray needle to an off‐axis position to prevent accumulation of contaminants in the MS entrance. By using this setup, other procedures to reduce the organic load to the MS entrance such as the heart‐cutting of the peaks eluting from the LC column were not required. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 265–274, 2001
A novel extraction method for the higher order components of channel current in a GaAs MESFET
Authors: Kim Youngsik , Yi Jaehyok , Yang Youngoo , Kim Bumman
Published: November 2004

A novel extractionion method has been proposed for direct extract of the higher order Taylor coefficients of the channel current Ids (Vgs, Vds) in a GaAs MESFET. Low‐frequency (45 and 70 MHz) two‐tone signals are employed to measure the harmonic component, and the load impedance was properly designed to find the cross terms. A Volterra series analysis is used for the formulation of Taylor series coefficients of the nonlinear channel current. This proposed parameter extraction procedure is simple and straightforward. The extracted current model is utilized successfully for intermodulation analysis. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 114–117, 2001.
Gain‐clamped erbium‐doped fiber amplifier using a single fiber Bragg grating
Authors: Subramaniam T. , Mahdi M. A. , Poopalan P. , Harun S. W. , Ahmad H.
Published: November 2004

A new design of an all‐optical gain‐clamped erbium‐doped fiber amplifier is demonstrated. The amplifier is based on the conventional ring cavity, where the gain is clamped at 21.84 dB via optical feedback using a single fiber Bragg grating for an input signal power as high as −8 dBm. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 290–293, 2001.
Dual‐surface combined‐field integral equation for three‐dimensional scattering
Authors: Prakash V. V. S. , Mittra Raj
Published: November 2004

In this paper, a dual‐surface combined‐field integral equation (DS–CFIE) formulation is presented for computing electromagnetic scattering from perfectly conducting arbitrary three‐dimensional (3‐D) bodies. The formulation has the advantage that it does not suffer from the internal resonance problem associated with the closed cavity modes. Convergence is typically obtained in a few iterations, and the formulation is relatively insensitive to the location of the virtual surface. Numerical results are presented for the case of plane‐wave scattering from a conducting sphere and a cube to validate the present approach. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 293–296, 2001.
Time‐domain study of lossy nonuniform multiconductor transmission lines with complex nonlinear loads
Authors: Kabbaj Hassane , Zimmermann Jacques
Published: November 2004

This paper deals with a computational approach based upon the centered‐points finite‐difference time‐domain (FDTD) technique for evaluating voltages and currents along lossy nonuniform multiconductor transmission lines terminated with arbitrary loads. We emphasize the case of complex nonlinear loads, such as a metal semiconductor field‐effect transistor (MESFET). We illustrate and validate the FDTD technique with time‐domain reflectometer (TDR) experiments. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 296–301, 2001.
Furniture effects on the wideband indoor radio channel at microwave frequencies
Authors: Cuiñas Iñigo , Sánchez Manuel García
Published: November 2004

Typically, ray‐tracing indoor simulators take into account the structural elements of the environment, but not other objects, such as furniture. Radio‐channel characteristics in empty and furnished environments have been measured along linear paths by using a wideband swept‐technique‐based sounder in a band around 5.8 GHz. Wideband parameters, such as delay spread and coherence bandwidth, exhibit important variations when the room is furnished as opposed to the situation when it is empty. Such effects are important, so radio network designers should modify their predictions to guarantee that the performance of wideband digital communication systems will be correct. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 336–340, 2001.
A compact bandpass filter using dielectric resonators for cellular portable telephones
Authors: Chen Yao‐Chung , Huang Cheng‐Lian
Published: November 2004

The microwave dielectric properties of a Ba(2−x)Sm(4+2x/3)Ti9O26 system (BST) (0.0≤x≤0.3) and the design procedures for a microwave coaxial dielectric bandpass filter are investigated in this work. Dielectric coaxial resonators with excellent dielectric properties of εr=75–80, a Q×f value=11,000, and great temperature stability at the resonant frequency (τf=∼0 ppm/°C) were used. Microwave bandpass filters for mobile communication systems were constructed by using such λ/4 coaxial resonators. Both air‐gap coupling and direct coupling methods were applied as the coupling instruments in the transformation of electromagnetic energy. The comb‐line theory was used to adjust the response of filters. The resonant frequency of each resonator, the coupling coefficients between adjacent resonators, and the external quality factor were adjusted to achieve the target specifications. The measured responses were in excellent agreement with the expected results. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 359–362, 2001.
Design of electromagnetic crystal filters for rectangular waveguides
Authors: Mendioroz Luis , Gonzalo Ramon , del Rio Carlos
Published: November 2004

In this paper, a new implementation of rectangular waveguide filters using dielectric periodic structures called electromagnetic crystals is presented. By tuning its forbidden band with the desired rejection band of the rectangular waveguide, the filtering behavior is obtained. The dependence of the filter features as a function of the periodic structure characteristics is shown. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 81–84, 2001.
p62/p56 are cortical granule proteins that contribute to formation of the cortical granule envelope and play a role in mammalian preimplantation development
Authors: Hoodbhoy Tanya , Dandekar P. , Calarco P. , Talbot P.
Published: November 2004

The purpose of this study was to identify specific cortical granule protein(s) that form the cortical granule envelope and examine their role(s) in fertilization and preimplantation development. The polyclonal antibody A‐BL2 was used to show that the cortical granules of mice, rats, hamsters, cows, and pigs contain a pair of proteins designated p62/p56. These proteins are released from hamster cortical granules at fertilization and contribute to formation of the cortical granule envelope, an extracellular matrix present in the perivitelline space of fertilized mammalian oocytes. P62/p56 were present in the cortical granule envelope throughout preimplantation development and were found in blastomere cortices of 4‐cell to blastocyst stage embryos. Hamster oocytes fertilized in vivo in the presence of A‐BL2 were all monospermic, suggesting that p62/p56 do not function in blocking polyspermy. Likewise treatment of morula to blastocyst stage hamster embryos with A‐BL2 had no effect on the implantation of blastocysts. However, cleavage divisions were inhibited in vivo in a dose‐dependent manner when fertilized oocytes or 2‐cell embryos were treated with A‐BL2. Inhibition of cell division was more pronounced in 2‐cell embryos than in fertilized oocytes. This study identifies p62/p56 as cortical granule proteins that contribute to the formation of the cortical granule envelope and further supports the idea that after their release at fertilization, p62/p56 function in regulating preimplantation development at the level of oocyte and blastomere cleavage. Mol. Reprod. Dev. 59:78–89, 2001. © 2001 Wiley‐Liss, Inc.
Intramolecular basis set superposition errors
Authors: Senent M. L. , Wilson S.
Published: November 2004

The effects of intramolecular basis set superposition errors are less well documented than the corresponding intermolecular effects. The intramolecular basis set superposition errors are examined, using the approach of Jensen, for several basis sets developed by Pople and his co‐workers, which are widely used in studies of larger molecules. Prototype calculations are reported for the ground state of the water molecule using both the matrix Hartree–Fock method and the many‐body perturbation expansion for the correlation energy taken through second order. A similar investigation is carried out for some of the correlation consistent basis sets published by Dunning and his collaborators. Specifically, the following aspects are investigated: (i) the magnitude of the intramolecular basis set superposition error, (ii) the nonadditivity of intramolecular counterpoise corrections when applied in a pairwise fashion, and (iii) the use of multiple “ghost” centers. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 282–292, 2001
Differentiation of α‐COOH from β‐COOH in aspartic acids by N‐phosphorylation
Authors: Chen Zhong‐Zhou , Tan Bo , Li Yan‐Mei , Zhao Yu‐Fen
Published: November 2004

The biomimic reactions of N‐phosphoryl amino acids, which involved intramolecular penta‐coordinate phosphoric‐carboxylic mixed anhydrides, are very important in the study of many biochemical processes. The reactivity difference between the α‐COOH group and β‐COOH in phosphoryl amino acids was studied by experiments and theoretical calculations. It was found that the α‐COOH group, and not β‐COOH, was involved in the ester exchange on phosphorus in experiment. From MNDO calculations, the energy of the penta‐coordinate phosphoric intermediate containing five‐member ring from α‐COOH was 35 kJ/mol lower than that of the six‐member one from β‐COOH. This result was in agreement with that predicted by HF/6‐31G** and B3LYP/6‐31G** calculations. Theoretical three‐dimensional potential energy surface for the intermediates predicted that the transition states 4 and 5 involving α‐COOH or β‐COOH group had energy barriers of ΔE=175.8 kJ⋅mol−1 and 210.4 kJ⋅mol−1, respectively. So the α‐COOH could be differentiated from β‐COOH intramolecularly in aspartic acids by N‐phosphorylation. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 41–51, 2001
Near ab initio quality molecular electrostatic potential maps using hybridization displacement charges at PM3 level and effects of geometrical changes in amino groups
Authors: Singh A. K. , Kushwaha P. S. , Mishra P. C.
Published: November 2004

Charge distributions, dipole moments, and molecular electrostatic potentials (MEP) around several molecules consisting of carbon, nitrogen, oxygen, fluorine, sulfur, and chlorine atoms were studied using the PM3 semiempirical method and the results compared with those obtained using ab initio calculations at the RHF/6‐31G** level. Thus it is shown that relative MEP values near different atoms can be obtained using hybridization displacement charges (HDC) obtained by employing PM3 density matrices that usually agree quite satisfactorily with the ab initio ones. Further, positions of ab initio MEP minima are correctly located and the corresponding relative MEP values usually correctly predicted using the PM3(HDC) charges distributed continuously in three dimensions according to the forms of squares of valence s atomic orbitals. The necessary parameters for HDC calculations using the PM3 method were optimized. It is shown how within the frameworks of both PM3 and AM1 methods the π electrons or lone pairs associated with amino group nitrogen atoms and ring atoms can be satisfactorily treated in different situations. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 299–312, 2001
Mnemonic symbols in commutator perturbation method
Authors: Matamala Adelio R.
Published: November 2004

In the present article special mnemonic symbols are defined to facilitate the calculation of the commutator perturbation method (CPM) series. CPM is a Lie‐algebraic version of the perturbation theory. The connection between CPM and the well‐known Rayleigh–Schrödinger perturbation theory (RSPT) is obtained by using a particular realization of these mnemonic symbols in terms of the spectral resolution of the model Hamiltonian (discrete states). © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 263–268, 2001
Asymptotic distribution for the cost of linear probing hashing
Authors: Janson Svante
Published: November 2004

We study moments and asymptotic distributions of the construction cost, measured as the total displacement, for hash tables using linear probing. Four different methods are employed for different ranges of the parameters; together they yield a complete description. This extends earlier results by Flajolet, Poblete and Viola [On the analysis of linear probing hashing, Algorithmica 22 (1998), 490–515]. The average cost of unsuccessful searches is considered too. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 19: 438–471, 2001
An investigation of facilitator‐assisted and CONOPS‐based requirements elicitation methods using a 2 × 2 factorial experimental design
Authors: Gambhir S. Gulu
Published: November 2004

System developments are frequently unsuccessful as measured in performance, cost, and schedule dimensions. Previous research has traced many development problems to poor system requirements. A method called Facilitator‐Assisted Requirements Elicitation (FARE), which employs a technical facilitator for discussion of requirements based on a Concept of Operations (CONOPS) Matrix, is developed and tested. A 2 × 2 factorial design was used to examine the effects of two independent variables on the FARE method: (1) facilitator presence or absence and (2) CONOPS Matrix or free‐form development. Twenty‐four subjects were randomly divided into four groups. Each group was given the task of developing a set of requirements and recording both a priority and rationale for the inclusion of each requirement. The three dependent variables are Communications, measured by responses to a post‐experiment survey; Requirements Scope, measured by subjective evaluation of requirements sets by an independent panel; and Requirements Quality, also measured by the independent panel. Results indicate a significant improvement in Communications when a facilitator was present. Requirements Scope showed a significant improvement when either a facilitator or the CONOPS Matrix was used, but was degraded when both elicitation techniques were used in combination. A significant improvement in Requirements Quality was observed when the groups were facilitated versus when they were not facilitated. Overall, both the presence of the facilitator and the use of the CONOPS Matrix showed benefits. Degradation in Requirements Scope, observed when both techniques were used in combination, is believed to be the result of the time constraints imposed on the subjects. The results of the experimentation support the use of FARE as an effective approach for capturing requirements early in the development lifecycle, thereby avoiding costly requirements changes. © 2001 John Wiley & Sons, Inc. Syst Eng 4: 272–286, 2001
Self and nonself recognition of chiral catalysts: The origin of nonlinear effects in the amino‐alcohol catalyzed asymmetric addition of diorganozincs to aldehydes
Authors: Noyori Ryoji , Suga Seiji , Oka Hiromasa , Kitamura Masato
Published: November 2004

Asymmetric addition of dialkylzincs to aldehydes in the presence of (2S)‐3‐exo‐(dimethylamino)isoborneol [(S)‐DAIB] exhibits various nonclassical phenomena. The enantiomeric excess (ee) of the alkylation product, obtained with partially resolved DAIB, is much higher than that of the chiral amino alcohol, while the rate decreases considerably as the ee of DAIB is lowered. The asymmetric amplification effects reflect the relative turnover numbers of two enantiomorphic catalytic cycles, where an essential feature is the reversible homochiral and heterochiral dimerization of the coexisting enantiomeric DAIB‐based Zn catalysts. The interplay between the thermodynamics of the monomer/dimer equilibration and the kinetics of alkylation reaction strongly affect the overall profile of asymmetric catalysis. The self and nonself recognition of the chiral Zn catalysts is a general phenomenon when (S)‐DAIB is mixed with its enantiomer, diastereomer, or even an achiral β‐amino alcohol. The degree of nonlinearity is highly affected not only by the structures and purity of catalysts but also by various reaction parameters. The salient features have been clarified on the basis of molecular weight measurements, NMR and X‐ray crystallographic studies of organozinc complexes, and kinetic experiments, as well as computer‐aided quantitative analysis. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:85–100, 2001
Thailand: Opportunities and risks in a fast‐changing business environment
Authors: Wedel Paul F. , Rondinelli Dennis A.
Published: November 2004

Thailand's business environment is changing dramatically in the wake of the worst financial crisis and
economic recession in the country's recent history. Some of these changes may be ephemeral, and Thailand
will return to old business practices once the crisis eases, but many of the economic and political reforms now
being implemented can make trade and investment in Thailand easier, more transparent, and less affected by
corruption. Some of the reforms will not deliver the expected results. Others may increase uncertainty that will
be counterproductive in the short run. But some of the constitutional changes—the restructuring of family
controlled conglomerates, better regulation of the financial sector, demands for stronger corporate governance,
and new incentives for private investment—can have profound impacts on the country's business climate
and the way American companies do business in Thailand. © 2001 John Wiley & Sons, Inc.
Genetic population history relationships of the population of Bogotá, Colombia, by using the D1S80, VWA, and TH01 molecular markers
Authors: Duran Rocio , Ruiz‐García Manuel
Published: November 2004

The genetic relationships of the population of Bogotá, Colombia, was comparatively studied with regard to other populations from America, Europe, and Asia, by using the D1S80, VWA, and TH01 molecular loci. From a population history point of view, the population of Bogotá seems to be more related to a European origin, with several differential contributions coming from Amerindians rather than from African and Asian populations, when the D1S80 and TH01 markers were employed. However, the contribution was greater from African populations for the VWA marker. Several explanations are offered to resolve the genetic affiliation of this population. Am. J. Hum. Biol. 13:374–383, 2001. © 2001 Wiley‐Liss, Inc.
Mitochondrial DNA sequence analysis in Sicily
Authors: Vona G. , Ghiani M.E. , Calò C.M. , Vacca L. , Memmì M. , Varesi L.
Published: November 2004

This study reports data on the sequences of the first hypervariable segment of a sample of the Sicilian population from Alia (Palermo, Italy). The results show the presence of 32 different haplotypes in the 49 individuals examined. The average number of pairwise nucleotide differences was 4.04, i.e., 1.17% per nucleotide. The distribution of the nucleotide differences matches the theoretical distribution and indicates only one major episode of expansion that occurred between 20,732 and 59,691 years ago, between the Middle Paleolithic and Upper Paleolithic. Compared with the other populations, parameters of the Sicilian sample lie in an intermediate position between the eastern and western Mediterranean populations. This is due to numerous contacts that Sicily has had with the Mediterranean area since prehistoric times. At the same time, the singularity of some of the haplotypes present in the sample studied indicates the persistence of some characteristics caused by genetic drift and isolation that the population has endured in the course of its history. Am. J. Hum. Biol. 13:576–589, 2001. © 2001 Wiley‐Liss, Inc.
Well‐being changes in response to 30 years of regional integration in Maya populations from Yucatan, Mexico
Authors: Gurri Francisco D. , Pereira Gilberto Balam , Moran Emilio F.
Published: November 2004

Infant mortality rate (IMR), overall frequency of linear enamel hypoplasia (LEH), sexual dimorphism in LEH, age of onset of LEH, and age at menarche were used as indicators to test the hypothesis that the origin and development of the tourist industry and increased state participation on Maya subsistence agriculturists in the early 1970s had improved the well‐being of the Maya. Two historical moments where inferred from the data. The first was derived from cheap and effective immunization and sanitation campaigns that reduced IMR from 143.4/1,000 live births in the early 1960s to 97.4 in the early 1970s. State participation broke the undernutrition–disease cycle enough to reduce LEH frequencies significantly (from 71.9% in individuals born before 1971 to 51.5% in those born in 1971 or after, χ2 = 55.72; 1 df; α = 0.00001) and to eliminate the sex difference in LEH expression (from a 14.8% LEH difference between men and women before 1971 [Male/Female Odds Radio = 0.45, α significant at 0.05] to a nonsignificant 2% difference). Improvement in overall living conditions reflected in a “modern stage” infant mortality regime and an almost disappearance of LEHs, resulted from gradual improvements in living conditions that did not become apparent until the 1980s. Trends in the age at menarche are not statistically significant, probably due to methodological limitations. However, if overall living conditions continue to improve or stay as they are today, accelerations in maturation should become noticeable. Am. J. Hum. Biol. 13:590–602, 2001. © 2001 Wiley‐Liss, Inc.
Familial risk of high blood pressure in the Canadian population
Authors: Katzmarzyk Peter T. , Rankinen Tuomo , Pérusse Louis , Rao D.C. , Bouchard Claude
Published: November 2004

Familial risk ratios for high blood pressure were estimated in a representative sample of the Canadian population. The sample consisted of 14,069 participants 7–69 years of age from 5,753 families participating in the 1981 Canada Fitness Survey. Resting systolic (SBP) and diastolic (DBP) blood pressures were adjusted for the effects of body mass index using regression procedures. Varying degrees of high blood pressure were defined as the 75th, 85th, and 95th percentiles of age‐ and sex‐specific values. Age‐ and sex‐standardized risk ratios (SRRs) were calculated comparing the prevalences in the general population to those in spouses and first‐degree relatives of probands with high blood pressure. SRRs for the 95th percentile were, for SBP and DBP, respectively, 1.37 and 1.45 in spouses and 1.33 and 2.36 in first‐degree relatives of probands. SRRs decrease with decreasing percentile cut‐offs used to define high blood pressure (95th > 85th > 75th), and SRRs are generally higher in first‐degree relatives than in spouses, particularly for DBP. The results indicate significant familial risk for high blood pressure in the Canadian population, and the pattern of SRRs suggests that genetic factors may be responsible for a portion of the risk. Am. J. Hum. Biol. 13:620–625, 2001. © 2001 Wiley‐Liss, Inc.
Effect of Down syndrome on the dimensions of dental crowns and tissues
Authors: Bell Emma , Townsend Grant , Wilson David , Kieser Jules , Hughes Toby
Published: November 2004

Abnormal growth in Down syndrome (DS) is reflected by variable reduction in size and simplification in form of many physical traits. This study aimed to compare the thickness of enamel and dentine in deciduous and permanent mandibular incisor teeth between DS and non‐DS individuals and to clarify how these tissues contribute to altered tooth size in DS. Sample groups comprised 61 mandibular incisors (29 permanent and 32 deciduous) from DS individuals and 55 mandibular incisors (29 permanent and 26 deciduous) from non‐DS individuals. Maximum mesiodistal and labiolingual crown dimensions were measured initially, then the crowns were sectioned midsagittally and photographed using a stereomicroscope. Linear measurements of enamel and dentine thickness were obtained on the labial and lingual surfaces of the crowns, together with enamel and dentine–pulp areas and lengths of the dentino‐enamel junction. Reduced permanent crown size in DS was associated with a reduction in both enamel and dentine thickness. After adjustments were made for tooth size, DS permanent incisors had significantly thinner enamel than non‐DS permanent teeth. The DS permanent teeth also exhibited significant differences in shape and greater variability in dimensions than the non‐DS permanent teeth. Crown dimensions of deciduous incisors were similar in size or larger in DS compared with non‐DS deciduous teeth. Enamel and dentine thicknesses of the deciduous teeth were similar in DS and non‐DS individuals. The findings indicate that growth retardation in DS reduces both enamel and dentine deposition in the permanent incisors but not in the earlier‐forming deciduous predecessors. The results are also consistent with the concept of amplified developmental instability for dental traits in DS. Am. J. Hum. Biol. 13:690–698, 2001. © 2001 Wiley‐Liss, Inc.
Abnormal desmin protein in myofibrillar myopathies caused by desmin gene mutations
Authors: Li Mian , Dalakas Marinos C.
Published: November 2004

Muscle proteins were extracted in various sodium dodecyl sulfate buffers from 6 patients with myofibrillar myopathy (MFM) and previously identified with mutations in the desmin gene (desmin myopathy; DesM), 6 with MFM without mutations, and 14 disease controls to search for alterations in biochemistry and solubility of mutated desmin filaments. In the 1% posthigh‐speed pellet fraction, desmin was detected with immunoblots only in DesM and not the other MFM. We conclude that mutant desmin forms insoluble aggregates that are specific for the DesM and can be detected with Western blots. Ann Neurol 2001;49:533–536
Small fibers involvement in Friedreich's ataxia
Authors: Nolano Maria , Provitera Vincenzo , Crisci Claudio , Saltalamacchia Anna Maria , Wendelschafer‐Crabb Gwen , Kennedy William Robert , Filla Alessandro , Santoro Lucio , Caruso Giuseppe
Published: November 2004

Although the involvement of large myelinated sensory fibers in Friedreich's ataxia (FA) is well documented, an impairment of unmyelinated fibers has not been described. We demonstrate an involvement of cutaneous unmyelinated sensory and autonomic nerve fibers in FA patients. We performed a morphological and functional study of cutaneous nerve fibers in 14 FA patients and in a population of control subjects. We used immunohistochemical techniques and confocal microscopy applied to punch skin biopsies from thigh, distal leg, and fingertip, and compared the density of epidermal nerve fibers (ENFs) with the results of mechanical pain sensation and thermal and tactile thresholds performed on hand dorsum, thigh, distal leg, and foot dorsum. We observed in our patients a statistically significant loss of ENFs, a reduced innervation of sweat glands, arrector pilorum muscles and arterioles, and an impairment of thermal and tactile thresholds and mechanical pain detection.
Increased frequency of the tumor necrosis factor‐α‐308 a allele in adults with human immunodeficiency virus dementia
Authors: Quasney Michael W. , Zhang Qing , Sargent Susie , Mynatt Margaret , Glass Jonathan , McArthur Justin
Published: November 2004

Genetic polymorphisms in the regulatory regions of various cytokine genes influence the amount of cytokine produced in response to inflammatory stimuli. To determine whether such polymorphisms might play a role in human immunodeficiency virus (HIV) dementia, a disease process in which tumor necrosis factor (TNF)‐α is believed to play a role, we analyzed HIV‐infected adults with and without dementia and control populations for a polymorphic site located in the promoter region of the gene coding for TNF‐α. The presence of the A allele at the TNF‐α‐308 site was overrepresented among adults with HIV dementia compared to those without dementia (0.28 versus 0.07; OR 5.5; 95% CI 1.8–17.0) and a healthy control population (0.28 versus 0.11). The increased frequency of the A allele in HIV‐infected adults with dementia suggests that this locus may play a role in the pathophysiology of dementia and suggests a genetic predisposition for the development of HIV dementia.
Clinical and pathological features of a parkinsonian syndrome in a family with an Ala53Thr α‐synuclein mutation
Authors: Spira Paul J. , Sharpe David M. , Halliday Glenda , Cavanagh Julie , Nicholson Garth A.
Published: November 2004

We describe an Australian family of Greek origin with a parkinsonian syndrome and an Ala53Thr α‐synuclein gene mutation. Five of 9 siblings were affected, the average age of onset was 45 years, and the initial symptoms were variable, including resting tremor, bradykinesia, and gait disturbance, as previously described in families with the same point mutation. Affected family members responded well to levodopa, developed progressive cognitive impairment, and had a disease duration of 5 to 16 years. Pathologic features typical of idiopathic Parkinson's disease were found at autopsy. However, there were several additional features not previously reported in families with this gene mutation. These features included severe central hypoventilation, orthostatic hypotension, prominent myoclonus, and urinary incontinence. An abundance of α‐synuclein–immunoreactive Lewy neurites were found in the brainstem pigmented nuclei, hippocampus, and temporal neocortex. The Lewy neurites were associated with temporal lobe vacuolation. Subcortical basal ganglia cell loss and gliosis were seen. These additional clinical and pathological features suggest that the Ala53Thr α‐synuclein mutation can produce a more widespread disorder than found in typical idiopathic Parkinson's disease. Ann Neurol 2001;49:313–319