bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstructing Diplomacy
Authors: Hoffman John
Published: October 2003

Conventional views on diplomacy emphasise the centrality of the state. This article will argue that the state is incoherent, and that this incoherence necessarily extends itself to statist diplomacy. Traditional concepts of diplomacy note the tension between negotiation and violence, so that if we are to make use of the conciliatory potential of diplomatic practice, we have to look to rework radically the concept of diplomacy. A rigorous distinction between violence and coercion (and constraint), and the state and government, enables us to reconstruct diplomacy so that it acquires a consistency which its association with the state makes impossible.
The Trajectory of Post‐communist Welfare State Development: The Cases of Bulgaria and Romania
Authors: Sotiropoulos Dimitri A. , Neamtu Ileana , Stoyanova Maya
Published: October 2003

Governments of countries undergoing a post‐communist transition face the dilemma of balancing conflicting demands for greater economic efficiency (to achieve a successful transition to a market system) with demands for enhanced social protection (to legitimize regime change through a visible improvement in living standards which includes vulnerable groups). This paper analyses the transition in Bulgaria and Romania. Unlike other European countries, these countries did not embark on retrenchment policies until the mid‐ to late 1990s, so convergence with policies of spending constraint elsewhere in Europe was belated and partial. The social problems created by strict economic policies, exacerbated by a determination to reorganize the post‐communist welfare states along the lines promoted by international organizations, are now being recognized. Post‐communist governments in South‐eastern Europe have belatedly started to address the social aspects of transition to democracy and the market. This probably reflects the process of regime change in Bulgaria and Romania, which has been characterized as a “two‐step transition to democracy”, with liberal governments only succeeding transformed communist elites in power after a protracted transition.
The Association of the Dopamine D4 Receptor Gene (DRD4) and the Serotonin Transporter Promoter Gene (5‐HTTLPR) with Temperament in 12‐month‐old Infants
Authors: Auerbach Judith G. , Faroy Michal , Ebstein Richard , Kahana Merav , Levine Joseph
Published: October 2003

This study examined the association between two common polymorphisms, the dopamine D4 receptor (DRD4) gene and the serotonin transporter promoter (5‐HTTLPR) gene and temperament in 61 infants aged 12 months. Twenty‐two infants had a least one copy of the 6–8 repeat DRD4 alleles (L‐DRD4) and 39 had two copies of the 2–5 repeat allele (S‐DRD4). Twenty infants were homozygous for the short form (s/s) of 5‐HTTLPR while 41 were either heterozygous for the short and the long form (l/s) or were homozygous for the long form (l/l). The infants were observed in a series of standard temperament episodes that elicited fear, anger, pleasure, interest, and activity. L‐DRD4 infants showed less interest in a structured block play situation and more activity in a free play situation. They also displayed less anger in an episode of mild physical restraint. Infants with s/s 5‐HTTLPR showed less fearful distress to stranger approach and less pleasure in a structured play situation than infants with l/l or l/s 5‐HTTLPR. Duration of looking during block play was affected by a significant interaction between DRD4 and 5‐HTTLPR. Shortest duration of looking was associated with the L‐DRD4 and s/s 5‐HTTLPR genotypes. The implications and limitations of these findings are discussed.
Well Sibling Psychological Adjustment to Chronic Physical Disorder in a Sibling: How Important is Maternal Awareness of Their Illness Attitudes and Perceptions?
Authors: Taylor Victoria , Fuggle Peter , Charman Tony
Published: October 2003

The psychological adjustment of healthy siblings was investigated in relation to their attitudes and perceptions about their brother's or sister's chronic physical disorder, to their mothers’ awareness of these attitudes and perceptions, and to three other maternal factors (maternal distress, maternal social support, and amount of care demanded by the physical disorder). Sixty‐two well siblings and mothers of children with a range of chronic physical disorders completed standardised questionnaires. The majority of siblings did not appear to have adjustment problems, although the sample had slightly increased rates of emotional symptoms compared to the general population. Mothers rated well siblings as having more negative attitudes and perceptions about the physical disorder than reported by siblings themselves. A multiple regression analysis indicated that better sibling adjustment was associated with higher maternal awareness of their attitudes and perceptions. These findings support Varni and Wallander's (1998) model that emphasises the role of relationship and attitude variables in child adjustment to chronic physical disorder. The implications of these findings for clinical practice are discussed.
Familiality of heart rate and cardiac‐related autonomic activity in five‐month‐old twins: The Québec newborn twins study
Authors: Dubreuil Etienne , Ditto Blaine , Dionne Ginette , Pihl Robert O. , Tremblay Richard E. , Boivin Michel , Pérusse Daniel
Published: October 2003

The familiality of infant sleeping heart rate (HR) and cardiac‐related autonomic activity, as indexed by spectral analysis of HR variability (HRV) and response to postural change, was investigated in 322 5‐month‐old twin pairs. The postural change elicited only minor changes in cardiovascular activity. As a result, analyses focused on supine cardiovascular activity. Multivariate genetic modeling indicated that individual differences in sleeping HR and high frequency (HF) HRV were determined by unique environmental and distinct additive genetic factors. These variables, along with low frequency (LF) HRV, were also affected by overlapping familial environmental influences. Familial influences in HF HRV were more pronounced for baby girls than boys. Estimates of relative LF and HF HRV were determined by common (familial) and unique environmental factors; familial influences on these estimates did not overlap with familial influences on sleeping HR.
Picture–word matching: Flexibility in conceptual memory and pupillary responses
Authors: Van Der Meer Elke , Friedrich Manuela , Nuthmann Antje , Stelzel Christine , Kuchinke Lars
Published: October 2003

The influence of levels of abstraction in picture–word matching was examined. The items each consisted of one picture and three successively presented words. Hierarchies with words for superordinate, basic, and subordinate level concepts were used (e.g., plant, flower, rose). The picture–word condition (congruent, incongruent), the word position (first, second, third), and the level of categorization (subordinate, basic, superordinate) were manipulated. Reaction times, error rates, and pupillary responses were recorded. Pupillary responses coincided with behavioral data. In general, there was an advantage for subordinate and basic level processing compared to superordinate level processing. However, switches to words for superordinate concepts were most facilitated. These findings support a two‐step account of picture–word matching. First, the picture is categorized according to its concrete features. Second, amodal features are processed.
Short‐term mobilization of processing resources is revealed in the event‐related potential
Authors: Falkenstein Michael , Hoormann Jörg , Hohnsbein Joachim , Kleinsorge Thomas
Published: October 2003

This study investigates whether an occasional effortful improvement of performance, as asked for by a precue, is reflected in event‐related potential (ERP) changes. To estimate the limits of possible effort‐induced behavioral and ERP changes, we manipulated the time between precue and imperative stimulus (IS; precue interval, PCI). The subjects could, in fact, improve their performance in the effort trials, with all but the shortest PCI. The postcue ERP revealed a fronto‐central contingent negative variation (CNV), which was preceded by a frontal positive/occipital negative wave (P2/N2). Both the P2/N2 and the CNV were larger for effort than for standard trials for all PCIs. For the shortest PCI (300 ms), the CNV increase was seen after the IS. The CNV increase for PCIs 600 and 300 began at about 400 ms postcue. The results suggest that effortful performance improvement is associated with prior increase of a frontocentral CNV and a preceding P2/N2. The CNV increase is thought to reflect the activity of a frontal executive process by which additional processing resources can be mobilized on a trial‐to‐trial basis within less than 500 ms.
Startle reflex modulation, affective ratings and autonomic reactivity in incarcerated Spanish psychopaths
Authors: Carmen Pastor M. , Moltó Javier , Vila Jaime , Lang Peter J.
Published: October 2003

Startle probe modulation during affective picture viewing was assessed in a Spanish prison population. As for North American inmates, psychopaths failed to display normal blink potentiation during unpleasant slides even though their evaluative judgments and autonomic reaction to affective stimuli paralleled those of other inmate and noninmate participants. The results suggest that diminished defense activation characterizes psychopaths despite cultural differences.
Coupling of theta activity and glucose metabolism in the human rostral anterior cingulate cortex: An EEG/PET study of normal and depressed subjects
Authors: Pizzagalli Diego A. , Oakes Terrence R. , Davidson Richard J.
Published: October 2003

In rodents, theta rhythm has been linked to the hippocampal formation, as well as other regions, including the anterior cingulate cortex (ACC). To test the role of the ACC in theta rhythm, concurrent measurements of brain electrical activity (EEG) and glucose metabolism (PET) were performed in 29 subjects at baseline. EEG data were analyzed with a source localization technique that enabled voxelwise correlations of EEG and PET data. For theta, but not other bands, the rostral ACC (Brodmann areas 24/32) was the largest cluster with positive correlations between current density and glucose metabolism. Positive correlations were also found in right fronto‐temporal regions. In control but not depressed subjects, theta within ACC and prefrontal/orbitofrontal regions was positively correlated. The results reveal a link between theta and cerebral metabolism in the ACC as well as disruption of functional connectivity within frontocingulate pathways in depression.
The CNV peak: An index of decision making and temporal memory
Authors: Macar Françoise , Vidal Franck
Published: October 2003

A slow brain potential change, the contingent negative variation (CNV), was recorded in a temporal generalization schedule. The task was to judge the duration of a signal (1.250 to 3.125 s) as being equal or not to that of a 2‐s target that had been previously memorized. Two signal modalities, visual and tactile, were contrasted in distinct trial blocks, in order to explore possible localization differences. Significant results were found at CPz, irrespective of signal modality. The CNV that developed during signal presentation peaked around 2 s and then declined when the current signal was longer than the 2‐s target, instead of peaking at signal extinction as was the case for shorter signals. Thus, for signals longer than the target, the CNV peak and the following slope change provide a memory trace of the encoded target duration, leading to decision making.
Differentiating amodal familiarity from modality‐specific memory processes: An ERP study
Authors: Curran Tim , Dien Joseph
Published: October 2003

Distinct event‐related potential effects have been related to familiarity and recollection processes underlying recognition memory. Familiarity has been conceptualized as similar either to perceptual priming mechanisms supporting implicit memory or to amodal global‐matching processes that should show little sensitivity to perceptual variables. The present experiment manipulated the study modality of words (auditory, visual) that were visually tested for recognition memory. The mid‐frontal (300–500 ms) old/new effect often attributed to familiarity was not affected by study modality, so it appears related to an amodal familiarity process. An earlier (176–260 ms) fronto‐polar old/new effect was perceptually specific in that it was observed only following visual study. The parietal old/new effect (400–800 ms), often attributed to recollection, was similar following both visual and auditory study. Temporal‐spatial PCA clarified the separability of these effects.
BIS–BAS sensitivity and cardiac autonomic stress profiles
Authors: Heponiemi Tarja , Keltikangas‐Järvinen Liisa , Kettunen Joni , Puttonen Sampsa , Ravaja Niklas
Published: October 2003

This study examined the relationship of sensitivities of Gray's behavioral inhibition system (BIS) and behavioral approach system (BAS) to cardiac autonomic stress responses during laboratory tasks among 65 healthy men (n=34) and women (n=31) aged 22–37 years. Carver and White's BIS–BAS scales were used to measure BIS and BAS sensitivities. We measured heart rate (HR), respiratory sinus arrhythmia, and preejection period during mental arithmetic, a reaction time task, and a speech task. Results revealed that BAS sensitivity was related to HR reactivity and parasympathetic withdrawal during the tasks, but was unrelated to baseline levels. BIS sensitivity was unrelated to both reactivity and baseline levels of all measures. Overall, our results suggest that the relationship of the BAS with cardiac reactivity seems to be mediated by the parasympathetic nervous system.
Comparing arithmetic and semantic fact retrieval: Effects of problem size and sentence constraint on event‐related brain potentials
Authors: Jost Kerstin , Hennighausen Erwin , Rösler Frank
Published: October 2003

Event‐related potentials were recorded with 61 electrodes from 16 students who verified either the correctness of single‐digit multiplication problems or the semantic congruency of sentences. Multiplication problems varied in size and sentence fragments in constraint. Both semantic and arithmetic incongruencies evoked a typical N400 with a clear parieto‐central maximum. In addition, numerically larger problems (8×7), in comparison to smaller problems (3×2), evoked a negativity starting at about 360 ms whose maximum was located over the right temporal‐parietal scalp. These results indicate that the arithmetic incongruency and the problem‐size effect are functionally distinct. It is suggested that the arithmetic and the semantic incongruency effects are both functionally related to a context‐dependent spread of activation in specialized associative networks, whereas the arithmetic problem‐size effect is due to rechecking routines that go beyond basic fact retrieval.
Profit Warnings and Timing
Authors: Jackson Dave , Madura Jeff
Published: October 2003

We find that profit‐warning announcements elicit a strong negative market response that is not sensitive to timing the warning in advance of the earnings announcement. Share prices begin to adjust about five days before a profit warning, and the market response is not complete until about five days after the warning. The accumulated response over the 11‐day period ending five days after the announcement is −21.7%. The profit warning effect over the two‐day announcement period is 32 times the valuation effect upon subsequent release of the actual earnings. There is no evidence of a reversal after this period, and therefore no sign that the market response is excessive.
Functional genomics in rodent models of hypertension
Authors: McBride Martin W. , Charchar Fadi J. , Graham Delyth , Miller William H. , Strahorn Pamela , Carr Fiona J. , Dominiczak Anna F.
Published: October 2003

Inbred strains of rodents have been used to study mammalian physiology and pathophysiology in an attempt to understand the contribution of genes in the pathogenesis of the disease process. In this review we focus on experimental animal models to identify quantitative trait loci (QTL) and possible strategies for identifying underlying genetic determinants responsible for hypertension. Confirmation of the existence of the QTL and dissection of the implicated region can be undertaken by production of either recombinant inbred, consomic or congenic strains. Despite complex interactions and the relatively few confirmed causative genes underlying QTL, recent developments in rat genome resources and advancement in statistical and bioinformatic methods will facilitate the identification of major gene(s) responsible for complex, polygenic traits.
Properties of Pacemaker Potentials Recorded from Myenteric Interstitial Cells of Cajal Distributed in the Mouse Small Intestine
Authors: Kito Yoshihiko , Suzuki Hikaru
Published: October 2003

Recording of electrical responses from isolated small intestine of mice using conventional microelectrodes revealed two types of potential, a pacemaker potential and a slow wave, both with rapid rising primary components and following plateau components. The rate of rise and peak amplitude were greater for pacemaker potentials than for slow waves, and the plateau component was smaller in slow waves than in pacemaker potentials. Both potentials oscillated at a similar frequency (20–30 min−1). Unitary potentials often discharged during the interval between pacemaker potentials. Infusion of Lucifer Yellow allowed visualization of the recorded cells; pacemaker potentials were recorded from myenteric interstitial cells of Cajal (ICC‐MY) while slow waves were recorded from circular smooth muscle cells. Pacemaker potentials were characterized as follows: the primary component was inhibited by Ni2+, Ca2+‐free solution or depolarization with high‐K+ solution, the plateau component was inhibited by 4,4′‐diisothiocyanostilbene‐2,2′‐disulphonic acid (DIDS), an inhibitor of Ca2+‐activated Cl− channels, low [Cl−]o solution or Ca2+‐free solution, and the generation of potentials was abolished by co‐application of Ni2+and DIDS or by chelating intracellular Ca2+ with 1,2‐bis(2‐aminophenoxy)ethane‐N,N,N’,N’‐tetraacetic acid acetoxymethyl ester (BAPTA‐AM). These results indicate that in the mouse small intestine ICC‐MY generate pacemaker potentials with two components in situ; the primary and plateau components may be generated by activation of voltage‐dependent Ca2+‐permeable channels and Ca2+‐activated Cl− channels, respectively. Slow waves are generated in circular smooth muscles via electrotonic spread of pacemaker potentials. These properties of intestinal pacemaker potentials are considered essentially similar to those of gastric pacemaker potentials.
Alternative splicing of N‐ and C‐termini of a C. elegans ClC channel alters gating and sensitivity to external Cl− and H+
Authors: Denton Jerod , Nehrke Keith , Rutledge Eric , Morrison Rebecca , Strange Kevin
Published: October 2003

CLH‐3 is a meiotic cell cycle‐regulated ClC Cl− channel that is functionally expressed in oocytes of the nematode Caenorhabditis elegans. CLH‐3a and CLH‐3b are alternatively spliced variants that have identical intramembrane regions, but which exhibit striking differences in their N‐ and C‐termini. Structural and functional studies indicate that N‐ and C‐terminal domains modulate ClC channel activity. We therefore postulated that alternative splicing of CLH‐3 would alter channel gating and physiological functions. To begin testing this hypothesis, we characterized the biophysical properties of CLH‐3a and CLH‐3b expressed heterologously in HEK293 cells. CLH‐3a activates more slowly and requires stronger hyperpolarization for activation than CLH‐3b. Depolarizing conditioning voltages dramatically increase CLH‐3a current amplitude and induce a slow inactivation process at hyperpolarized voltages, but have no significant effect on CLH‐3b activity. CLH‐3a also differs significantly in its extracellular Cl− and pH sensitivity compared to CLH‐3b. Immunofluorescence microscopy demonstrated that CLH‐3b is translationally expressed during all stages of oocyte development, and furthermore, the biophysical properties of the native oocyte Cl− current are indistinguishable from those of heterologously expressed CLH‐3b. We conclude that CLH‐3b carries the oocyte Cl− current and that the channel probably functions in nonexcitable cells to depolarize membrane potential and/or mediate net Cl− transport. The unique voltage‐dependent properties of CLH‐3a suggest that the channel may function in muscle cells and neurones to regulate membrane excitability. We suggest that alternative splicing of CLH‐3 N‐ and C‐termini modifies the functional properties of the channel by altering the accessibility and/or function of pore‐associated ion‐binding sites.
Exercise Increases Ca2+–Calmodulin‐Dependent Protein Kinase II Activity in Human Skeletal Muscle
Authors: Rose Adam J. , Hargreaves Mark
Published: October 2003

There is evidence in rodents that Ca2+‐calmodulin‐dependent protein kinase II (CaMKII) activity is higher in contracting skeletal muscle, and this kinase may regulate skeletal muscle function and metabolism during exercise. To investigate the effect of exercise on CaMKII in human skeletal muscle, healthy men (n= 8) performed cycle ergometer exercise for 40 min at 76 ± 1 % peak pulmonary O2 uptake (V̇O2peak), with skeletal muscle samples taken at rest and after 5 and 40 min of exercise. CaMKII expression and activities were examined by immunoblotting and in vitro kinase assays, respectively. There were no differences in maximal (+ Ca2+, CaM) CaMKII activity during exercise compared with rest. Autonomous (‐ Ca2+, CaM) CaMKII activity was 9 ± 1 % of maximal at rest, remained unchanged at 5 min, and increased to 17 ± 1 % (P < 0.01) at 40 min. CaMKII autophosphorylation at Thr287 was 50‐70 % higher during exercise, with no differences in CaMKII expression. The effect of maximal aerobic exercise on CaMKII was also examined (n= 9), with 0.7‐ to 1.5‐fold increases in autonomous CaMKII activity, but no change in maximal CaMKII activity. CaMKIV was not detected in human skeletal muscle. In summary, exercise increases the activity of CaMKII in skeletal muscle, suggesting that it may have a role in regulating skeletal muscle function and metabolism during exercise in humans.
Evidence of porcine and human endothelium activation by cancer‐associated carbohydrates expressed on glycoproteins and tumour cells
Authors: Glinskii Olga V. , Turk James R. , Pienta Kenneth J. , Huxley Virginia H. , Glinsky Vladislav V.
Published: October 2003

It is well established that after metastatic cancer cells escape the primary tumour and enter the circulation, their interactions with microvascular endothelium of a target organ constitute an essential rate‐limiting step in haematogenous cancer metastasis. However, the physiological and biochemical processes supporting neoplastic cell arrest and retention in the microcirculation are still poorly understood. In this study, we present experimental evidence that microvascular endothelium of metastasis‐prone tissues undergoes activation in response to desialylated cancer‐associated carbohydrate structures such as Thomsen–Friedenreich (TF) antigen (Galβ1–3GalNAc) expressed on circulating glycoproteins and neoplastic cells. The metastasis‐associated endothelium activation, manifested by marked increase in endothelial cell surface galectin‐3 expression, causes gradual decrease in cancer cell velocities (from 72 × 102± 33 × 102μm s−1 to 7.6 × 102± 1.9 × 102μm s−1, mean ±s.d.) accompanied by a corresponding increase in the percentage of rolling cells (from 3.3%± 1.2% to 24.3%± 3.6%, mean ±s.d.), and results in human breast and prostate carcinoma cell arrest and retention in the microvasculature. This process, which could be of high importance in haematogenous cancer metastasis, was inhibited efficiently by an anti‐TF antigen function‐blocking antibody. Carbohydrate‐mediated endothelial activation could be a process of physiological significance as it probably occurs in the interactions between a variety of circulating constituents and the vessel wall.
Platelet‐Activating Factor: A Previously Unrecognized Mediator of Fever
Authors: Ivanov Andrei I. , Patel Shreya , Kulchitsky Vladimir A. , Romanovsky Andrej A.
Published: October 2003

Lipopolysaccharide (LPS)‐induced systemic inflammation is accompanied by either hypothermia (prevails when the ambient temperature (Ta) is subneutral) or fever (prevails when Ta is neutral or higher). Because platelet‐activating factor (PAF) is a proximal mediator of LPS inflammation, it should mediate both thermoregulatory responses to LPS. That PAF possesses hypothermic activity and mediates LPS‐induced hypothermia is known. We asked whether PAF possesses pyrogenic activity (Expt 1) and mediates LPS fever (Expt 2). The study was conducted in Long‐Evans rats implanted with jugular catheters. A complex with bovine serum albumin (BSA) was infused as a physiologically relevant form of PAF; free (aggregated) PAF was used as a control. In Expt 1, either form of PAF caused hypothermia when infused (83 pmol kg‐1 min‐1, 60 min, i.v.) at a subneutral Ta of 20 °C, but the response to the PAF‐BSA complex (−4.5 ± 0.5 °C, nadir) was ~4 times larger than that to free PAF. At a neutral Ta of 30 °C, both forms caused fever preceded by tail skin vasoconstriction, but the febrile response to PAF‐BSA (1.0 ± 0.1 °C, peak) was > 2 times higher than that to free PAF. Both the hypothermic (at 20 °C) and febrile (at 30 °C) responses to PAF‐BSA started when the total amount of PAF infused was extremely small, < 830 pmol kg‐1. In Expt 2 (conducted at 30 °C), the PAF receptor antagonist BN 52021 (29 µmol kg‐1, i.v.) had no thermal effect of itself. However, it strongly (~2 times) attenuated the febrile response to PAF (5 nmol kg‐1, i.v.), implying that this response involves the PAF receptor and is not due to a detergent‐like effect of PAF on cell membranes. BN 52021 (but not its vehicle) was similarly effective in attenuating LPS (10 µg kg‐1, i.v.) fever. It is concluded that PAF is a highly potent endogenous pyrogenic substance and a mediator of LPS fever.
Mixing and Entrainment Characteristics of Circular and Noncircular Confined Jets
Authors: Singh Ghanshyam , Sundararajan T. , Bhaskaran K. A.
Published: October 2003

The present work deals with the experimental investigation of entrainment characteristics of confined/semiconfined circular and noncircular jets. The jet fluid, after issuing out of a nozzle of circular or noncircular cross section, enters a circular mixing tube of larger area, and during this process it entrains some ambient fluid into the mixing tube. The flow is incompressible and isothermal at a jet Reynolds number of 7200. The experimental results obtained in the study are first validated with the approximate theoretical analysis of Pritchard et al. (1997) and also with the similarity solution proposed by Becker et al. (1963) for circular nozzles. It is observed that the similarity solution is applicable for circular as well as noncircular jets in the region close to the jet axis and away from the nozzle exit plane. The entrainment ratio increases to a maximum value as the jet location is shifted away from the tube inlet; for the configurations studied, enhancement up to 30% has been observed in the entrainment ratio with shift in jet location. For a smaller mixing tube diameter and jet located at the inlet of the mixing tube, the circular jet entrains more than noncircular jets. For a larger mixing tube or shifted jet locations, the noncircular jets entrain more of ambient fluid, in general. Among the different noncircular geometries considered, the jet having the cross section of an isosceles triangle causes maximum entrainment.
Linear Multi-Degree-of-Freedom System Stochastic Response by Using the Harmonic Wavelet Transform
Authors: Tratskas P. , Spanos P. D.
Published: October 2003

The wavelet transform is used to capture localized features in either the time domain or the frequency domain of the response of a multi-degree-of-freedom linear system subject to a nonstationary stochastic excitation. The family of the harmonic wavelets is used due to the convenient spectral characteristics of its basis functions. A wavelet-based system representation is derived by converting the system frequency response matrix into a time-frequency wavelet “tensor.” Excitation-response relationships are obtained for the wavelet-based representation which involve linear system theory, spectral representation of the excitation and of the response vectors, and the wavelet transfer tensor of the system. Numerical results demonstrate the usefulness of the developed analytical procedure.
An Expermentally Validated Model for Two-Phase Pressure Drop in the Intermittent Flow Regime for Noncircular Microchannels
Authors: Garimella Srinivas , Killion Jesse D. , Coleman John W.
Published: October 2003

This paper reports the development of an experimentally validated model for pressure drop during intermittent flow of condensing refrigerant R134a in horizontal, noncircular microchannels. Two-phase pressure drops were measured in six noncircular channels ranging in hydraulic diameter from 0.42 mm to 0.84 mm. The tube shapes included square, rectangular, triangular, barrel-shaped, and others. For each tube under consideration, pressure drop measurements were taken over the entire range of qualities from vapor to liquid at five different refrigerant mass fluxes between 150 kg/m2s and 750 kg/m2s. Results from previous work by the authors were used to select the data that correspond to the intermittent flow regime; generally, these points had qualities less than 25%. The pressure drop model previously developed by the authors for circular microchannels was used as the basis for the model presented in this paper. Using the observed slug/bubble flow pattern for these conditions, the model includes the contributions of the liquid slug, the vapor bubble, and the transitions between the bubble and slugs. A simple correlation for nondimensional unit-cell length was used to estimate the slug frequency. The model successfully predicts the experimentally measured pressure drops for the noncircular tube shapes under consideration with 90% of the predictions within ±28% of the measurements (average error 16.5%), which is shown to be much better than the predictions of other models in the literature. The effects of tube shape on condensation pressure drop are also illustrated in the paper.
Usage of the Lund Rotordynamic Programs in the Analysis of Centrifugal Compressors
Authors: Memmott Edmund A.
Published: October 2003

This paper is intended to be a history of the usage of the Jørgen Lund rotordynamic programs in the analysis of centrifugal compressors from the perspective of the author’s experience in that industry. Application of the Lund tilt pad bearing, rotor response, and stability programs will be described. They will be seen to be the basis for an industry wide acceptance criterion for the rotor dynamics of centrifugal compressors. They are used in the required audit reports for new compressors, and in trouble shooting investigations on the rotordynamics of centrifugal compressors.
The Scientific Work of Jørgen Lund and a Personal Assessment of Its Significance
Authors: Rieger Neville F.
Published: October 2003

A selection of the more important works of Jørgen Lund are described. The industrial features of the periods in which specific developments in rotordynamics took place are discussed, together with these developments themselves and the investigators who made them. Lund’s contributions are included within the latter part of this framework. The comparative value of Lund’s work is considered in terms of several criteria, which are judged to apply to the work of investigators generally. These criteria are used to examine the characteristics of three important pioneers of vibration technology, to demonstrate the validity of these criteria. Lund’s contributions are shown to be of high caliber when judged by the same criteria.
Inhomogeneous Cartilage Properties Enhance Superficial Interstitial Fluid Support and Frictional Properties, But Do Not Provide a Homogeneous State of Stress
Authors: Krishnan Ramaswamy , Park Seonghun , Eckstein Felix , Ateshian Gerard A.
Published: October 2003

It has been well established that articular cartilage is compositionally and mechanically inhomogeneous through its depth. To what extent this structural inhomogeneity is a prerequisite for appropriate cartilage function and integrity is not well understood. The first hypothesis to be tested in this study was that the depth-dependent inhomogeneity of the cartilage acts to maximize the interstitial fluid load support at the articular surface, to provide efficient frictional and wear properties. The second hypothesis was that the inhomogeneity produces a more homogeneous state of elastic stress in the matrix than would be achieved with uniform properties. We have, for the first time, simultaneously determined depth-dependent tensile and compressive properties of human patellofemoral cartilage from unconfined compression stress relaxation tests. The results show that the tensile modulus increases significantly from 4.1±1.9MPa in the deep zone to 8.3±3.7MPa at the superficial zone, while the compressive modulus decreases from 0.73±0.26MPa to 0.28±0.16MPa. The experimental measurements were then implemented with the finite-element method to compute the response of an inhomogeneous and homogeneous cartilage layer to loading. The finite-element models demonstrate that structural inhomogeneity acts to increase the interstitial fluid load support at the articular surface. However, the state of stress, strain, or strain energy density in the solid matrix remained inhomogeneous through the depth of the articular layer, whether or not inhomogeneous material properties were employed. We suggest that increased fluid load support at the articular surface enhances the frictional and wear properties of articular cartilage, but that the tissue is not functionally adapted to produce homogeneous stress, strain, or strain energy density distributions. Interstitial fluid pressurization, but not a homogeneous elastic stress distribution, appears thus to be a prerequisite for the functional and morphological integrity of the cartilage.
Methods for Quasi-Linear Viscoelastic Modeling of Soft Tissue: Application to Incremental Stress-Relaxation Experiments
Authors: Sarver Joseph J. , Robinson Paul S. , Elliott Dawn M.
Published: October 2003

The quasi-linear viscoelastic (QLV) model was applied to incremental stress-relaxation tests and an expression for the stress was derived for each step. This expression was used to compare two methods for normalizing stress data prior to estimating QLV parameters. The first and commonly used normalization method was shown to be strain-dependent. Thus, a second normalization method was proposed and shown to be strain-independent and more sensitive to QLV time constants. These analytical results agreed with representative tendon data. Therefore, this method for normalizing stress data was proposed for future studies of incremental stress-relaxation, or whenever comparing stress-relaxation at different strains.
Heat capacity in bits
Authors: Fraundorf P.
Published: October 2003

The temperature T may be expressed as the rate of energy increase per unit increase in the state uncertainty under no-work conditions. The consequences of such a choice for heat capacities are explored. I show that the ratio of the total thermal energy E to kT is the multiplicity exponent (log–log derivative of the multiplicity) with respect to energy, as well as the number of base-b units of mutual information that is lost about the state of the system per b-fold increase in the thermal energy. Similarly, the no-work heat capacity CV is the multiplicity exponent for temperature, making CV independent of the choice of the intensive parameter associated with energy (for example, kT vs 1/kT) to within a constant, and explaining why its usefulness may go beyond the detection of thermodynamic phase changes and quadratic modes.
Controlled and Living Polymerizations Induced with Rhodium Catalysts. A Review
Authors: Sedláček Jan , Vohlídal Jiří
Published: October 2003

In the last fifteen years, a large variety of specialty polymers of diverse chemical structure and functionality have been synthesized with the rhodium-based catalysts. The high tolerance to the reaction medium and functional groups of monomers, as well as ability to control various structure features of the polymer formed are typical properties of these catalysts. In addition, some rhodium catalysts can be anchored to inorganic or organic supports or dissolved in ionic liquids to form heterophase polymerization systems, which opens the way to pure, well-defined polymers free of the catalyst residues, as well as to recycling rhodium catalysts. This review provides a survey on the polymerization reactions induced with rhodium-based catalysts, in which one or more structure attributes of the polymer formed are subject to control. The structure attributes considered are (i) sequential arrangement of monomeric units along polymer chains; (ii) head-tail isomerism of polymer molecules; (iii) configurational structure of polymer molecules; (iv) conformation of polymer molecules; and (v) molecular weight and molecular-weight distribution of the polymer formed. A review with 188 references.
Carbon Monoxide Chemisorption and Disproportionation on Thin Palladium Layers, Supported by Niobium and Niobium Pentoxide
Authors: Plšek Jan , Nikolajenko Vladimír , Thiam Michel Malick , Knor Zlatko
Published: October 2003

Thermally programmed desorption technique has been applied to the investigation of "virgin" and repeated adsorption of carbon monoxide on Pd/Nb and Pd/Nb2O5/Nb systems. The desorbed products of the CO interaction with these surfaces, CO and CO2, were monitored with a quadrupole mass spectrometer. On the basis of presented results some of the observed differences between the metal- and oxide-supported active metal (Pd) have been ascribed to the morphological rather than to chemical (electronic) effects in these systems. The different excess kinetic energy dissipation of Pd atoms colliding with metallic or oxidic surface is considered to influence the initial growth of the Pd layer, resulting afterwards in a different morphology of the final Pd layers.
Linear Dimerization of Terminal Alkynes by Bis(tetramethylphenylcyclopentadienyl)titanium-Magnesium Hydride and Acetylide Complexes
Authors: Mach Karel , Gyepes Róbert , Horáček Michal , Petrusová Lidmila , Kubišta Jiří
Published: October 2003

New tetramethylphenylcyclopentadienyl trinuclear titanocene hydride-magnesium hydride complexes [{Ti(η5-C5Me4R)2(μ-H)2}2Mg], where R = Ph (1) or 4-fluorophenyl (FPh; 2), the dinuclear [Ti(η5-C5Me4Ph)[η5:η1{Ti:Mg}-C5Me4(o-C6H4)](μ-H)2Mg(THF)2] (3) and [Ti(η5-C5Me4Ph)2(μ-H)2MgC(Me)=CHMe] (4) complexes, and the [{Ti(η5-C5Me4Ph)2(η1-C≡CSiMe3)2}-{MgCl(THF)}+] (5) tweezer complex initiated the dimerization of (trimethylsilyl)ethyne (TMSE) or 1-hexyne (HXYN) to exclusively head-to-tail (HTT) dimers at 60 °C with the turnover number ranging from 300 to 500 mol alkyne per mol of the Ti complex. In contrast, all of them were inactive in the dimerization of tert-butylethyne (TBUE). Monitoring of reactions of the 1-5 complexes with the alkynes by electron spin resonance (ESR) method revealed a decay of the initial complexes 1-5 in the dimerizing systems with TMSE and HXYN or a conversion of complexes 3, 4, and 5 into the Ti(III) acetylide [Ti(η5-C5Me4Ph)2(η1-C≡CCMe3)] (6) in systems with TBUE. The acetylide 6 also initiated the dimerization of TMSE and HXYN to HTT dimers only. This fact together with the absence of ESR signals of tweezer complexes and acetylides in the reacting hydride systems allow us to assume that the rate of conversion of complexes 1-4 to tweezer complexes is slower than the rate of dissociation of the tweezer complexes to give the acetylides which are apparently the ultimate catalytic species. Most of the evidence on the catalytic complexes has been obtained from ESR spectra which are reliably characteristic of each type of the complexes. Crystal structures of 4 and 6 were determined.
Transition Metal Complex Catalysis in Fine Organic Synthesis. A Personal Account
Authors: Beletskaya Irina P. , Cheprakov Andrei V.
Published: October 2003

The development of catalytic systems for palladium catalyzed C-C and C-heteroatom bond formation is overviewed. Attention is focused on the issues relevant for environmental and technological safety of the processes: high catalytic efficiency, reactions in the absence of expensive non-recoverable phosphine ligands, the use of water and aqueous media, atom efficient transformations, etc.
Transmission Electron Microscopy Study of the Porous Structure of Aluminas Synthesized by Non-Ionic Surfactant Templating Route
Authors: Díaz Isabel , González-Peña Verónica , Márquez-Alvarez Carlos , Pérez-Pariente Joaquín
Published: October 2003

Organized mesoporous and microporous aluminas have been synthesized by a sol-gel route in non-aqueous media using poly(oxyethylene) block polymers as directing agents. Gel compositions adjusted to obtain direct micelles (in 1,4-dioxane solution) and reverse micelles (in cyclohexane solution) were tested. The influence of synthesis conditions, such as temperature, solvent, use of additives or chemical modification of the precursor, on the alumina porous structure has been analysed by transmission electron microscopy (TEM). Mesoporous aluminas with a pore structure originated by the cross-linking of corrugated oxide-hydroxide platelets of nanometric size were obtained using aluminum sec-butoxide as precursor. The addition of ammonium fluoride or amines to the synthesis gel, as well as higher calcination temperatures, caused a decrease in the surface area due to the condensation of the crystallites into a dense porous structure composed of small polycrystalline agglomerates. Microporous aluminas with higher density and a disordered but isotropic porous structure were obtained by chemical modification of the alkoxide precursor with chelating agents such as ethyl acetoacetate or triethanolamine.
Alkylation of Phenol and m-Cresol Over Zeolites
Authors: O'Connor Cyril T. , Moon Gillian , Böhringer Walter , Fletcher Jack C. Q.
Published: October 2003

The alkylation of phenols and phenol derivatives such as m-cresol are important reactions in a sequence of syntheses for the production of many important fine chemicals. Specifically it is of great importance to develop catalysts and processes, which are able to selectively produce one or other particular isomer or derivative. This paper presents results of an investigation into the alkylation of phenol and m-cresol, respectively, using methanol in the former case and propene in the latter. The catalysts of choice were H-ZSM-5 and H-MCM-22. In the case of phenol methylation it was found that controlling diffusivity by increasing crystal size was most conducive to the formation of p-cresol. H-MCM-22 showed a high selectivity to p-cresol. In the case of m-cresol propylation the selectivity over H-ZSM-5 to thymol was greater than 90% at conversions of around 50%, and 80% at conversions of around 85%. This high selectivity to thymol was considerably greater than reported in previous papers. In both systems mild reaction temperature and pressure conditions were desirable so as to minimize the formation of oligomeric products of methanol (via dimethyl ether) and propene, which could cause deactivation of the zeolite.
Hydrogenation and Hydrogenolysis of Acetophenone
Authors: Bejblová Martina , Zámostný Petr , Červený Libor , Čejka Jiří
Published: October 2003

Catalytic hydrogenation and hydrogenolysis of acetophenone was investigated on supported palladium catalysts in liquid phase at temperatures 30-130 °C and pressures 1-10 MPa. A number of supports like active carbon, alumina and zeolites Beta and ZSM-5 were employed. The effects of solvent and support on the reaction mechanism of acetophenone transformation were studied. Catalysts with acid zeolite support showed a very high activity in transformation of acetophenone to ethylbenzene. Based on a kinetic model, the reaction rates of acetophenone transformation to ethylbenzene on Pd/C and Pd/Al2O3 catalysts were discussed. The kinetic model confirmed that the transformation of acetophenone to ethylbenzene proceeds primarily via a hydrogenation-dehydration mechanism and the effect of the direct hydrogenolysis of the C=O bond of acetophenone is insignificant.
The Forest Watershed and Riparian Disturbance study: a multi-discipline initiative to evaluate and manage watershed disturbance on the Boreal Plain of Canada
Authors: Smith Daniel W , Prepas E E , Putz G , Burke J M , Meyer W L , Whitson I
Published: October 2003

The Forest Watershed and Riparian Disturbance (FORWARD) initiative integrates aquatic and soil science, hydrology, and forestry into models that link water quality, water quantity, and disturbance indicators with management of watersheds on the Boreal Plain of western Canada. The impacts of varying patterns and intensities of fire and logging are being evaluated for 16 streams in the Swan Hills, Alberta, with the intention to extend the approach to the eastern portion of the Boreal Plain and into the Boreal Shield. The study uses two comparative approaches: treatment versus reference stream and before versus after disturbance. Models generated will be applied to designated multi-user watersheds in selected forest areas. In addition to yielding transferable technology for forest product industries, the FORWARD study tests hypotheses related to effects of watershed disturbance on soils, hydrology, and water quality on the phosphorus-rich and fire-prone Boreal Forest in western Canada. Key words: watershed disturbance, surface waters, soils, hydrology, modelling, forest management.
Hydraulic properties of Orthic Gray Luvisolic soils and impact of winter logging
Authors: Whitson I R , Chanasyk D S , Prepas E E
Published: October 2003

Runoff as overland flow and interflow from hillslopes on the Boreal Plain Ecozone of North America is likely to depend on near-surface hydraulic properties. Hydraulic properties were examined in Orthic Gray Luvisolic soil profiles in Alberta, Canada, over several years following clear-cut winter logging and contrasted to those in adjacent forested areas. Infiltration characteristics were determined with double ring infiltrometers at both logged and forested sites. Saturated hydraulic conductivity (Ksat) of Ae and Bt horizons was measured in logged areas with undisturbed Uhland core samples. Infiltration parameters derived by the Kostiakov equation suggest that initial infiltration rates are higher at forested sites than logged. Steady-state infiltration was greater under forest. Vertical Ksat of the Ae was less than the Bt horizon, and horizontal Ksat of the Ae horizon exceeded vertical, indicating anisotropy. Compaction and soil swelling resulting from increased soil water content after logging probably reduced macro-porosity and lowered infiltration capacity. Similarity of Ksat between Ae and Bt horizons in logged areas may have reflected compaction. Logging then may temporarily increase the potential for overland flow but may reduce interflow through Ae horizons until time restores soil hydraulic characteristics to that of an older forest. Key words: infiltration, hydraulic conductivity, Gray Luvisolic.