bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of macronutrients on gastric volume responses and gastric emptying in humans: a magnetic resonance imaging study
Authors: Goetze Oliver , Steingoetter Andreas , Menne Dieter , van der Voort Ivo R. , Kwiatek Monika A. , Boesiger Peter , Weishaupt Dominik , Thumshirn Miriam , Fried Michael , Schwizer Werner
Published: August 2006

The effects of macronutrients on gastric volume changes, emptying, and gastrointestinal symptoms are incompletely understood. Three liquid meals of 500 ml (fat emulsion, 375 kcal; protein solution, 375 kcal; glucose solution, 400 kcal) were infused into the stomach of 12 healthy volunteers on three occasions. Studies were performed in seated body position using an open-configuration magnetic resonance imaging (MRI) system. MRI imaging sequences, assessing stomach and meal volumes, were performed prior to and at times t = 0, 3, 6, 9, 12, 15, 25, 35, 45, 60, 75, and 90 min after meal administration. Areas under the curve for the early emptying phase (0–15 and 0–45 min) were calculated, and characteristics of the volume curves were analyzed by a gastric emptying model. Gastrointestinal symptoms were assessed by a self-report scale. Initial ( t = 0 min) and early postprandial gastric volumes were highest for glucose because of lower initial emptying. However, in the early emptying phase the characteristics of the volume curves for stomach and meal were uniform for all macronutrients. Perceptions of fullness and satiety were linearly associated with postprandial gastric volumes, but not with macronutrient composition. Isovolumic macronutrient meals modulate gastric volume response by initial meal emptying patterns. Macronutrient specific accommodation responses, as shown in barostat studies, are not reflected as gastric volume responses under noninvasive conditions.
Developmental changes in time course of recovery from inactivation in L-type calcium currents of rabbit ventricular myocytes
Authors: Namiki Takao , Joyner Ronald W. , Wagner Mary B.
Published: August 2006

The mechanisms of recovery from inactivation of the L-type calcium current ( ICa) are not well established, and recovery is affected by many experimental conditions. Little is known about developmental changes of recovery from inactivation of ICa. We studied developmental changes of recovery from inactivation in ICa using isolated adult and newborn (1–4 days) rabbit ventricular myocytes. We used broken-patch and perforated-patch techniques with physiological extracellular ionic concentrations of calcium and sodium and interpulse conditioning potentials of −80 or −50 mV. We also maximized ICa with forskolin. We found that recovery from inactivation did not differ between adult and newborn cells when either EGTA or BAPTA was used to buffer intracellular calcium. Maximizing ICa with forskolin slowed recovery from inactivation in newborn but not in adult cells. In contrast, when the intracellular buffering of the cell was left nearly intact (perforated patch), recovery from inactivation (half-time of recovery) in the newborn cells was significantly slower than for the adult cells when either a conditioning potential of −80 mV (140 ± 9 vs. 58 ± 4 ms, newborn vs. adult; P < 0.05) or −50 mV (641 ± 106 vs. 168 ± 15 ms, newborn vs. adult; P < 0.05) was used. Forskolin significantly increased half-time of recovery for both adult and newborn cells. Dialysis with no calcium buffer showed a slower recovery from inactivation in newborn cells. Intracellular dialysis with a calcium buffer masked differences in recovery from inactivation of ICa between newborn and adult rabbit ventricular cells.
High-volume ventilation induces pentraxin 3 expression in multiple acute lung injury models in rats
Authors: Okutani Daisuke , Han Bing , Mura Marco , Waddell Thomas K. , Keshavjee Shaf , Liu Mingyao
Published: August 2006

Pentraxin 3 (PTX3) is an acute-phase protein, which can be produced by a variety of tissue cells at the site of infection or inflammation. It plays an important role in innate immunity in the lung and in mediating acute lung injury. The aim of this study was to determine the effect of mechanical ventilation on PTX3 expression in multiple lung injury models. Male Sprague-Dawley rats were challenged with intravenous injection of lipopolysaccharide (LPS) or hemorrhage followed by resuscitation (HS). The animals were then subjected to either relatively higher (12 ml/kg) or lower (6 ml/kg, positive end-expiratory pressure of 5 cmH2O) volume ventilation for 4 h. High-volume ventilation significantly enhanced PTX3 expression in the lung, either alone or in combination with LPS or hemorrhage. A significant increase of PTX3 immunohistochemistry staining in the lung was seen in all injury groups. The PTX3 expression was highly correlated with the severity of lung injury determined by blood gas, lung elastance, and wet-to-dry ratio. To determine the effects of HS, LPS, or injurious ventilation (25 ml/kg) alone on PTX3 expression, another group of rats was studied. Injurious ventilation significantly damaged the lung and increased PTX3 expression. A local expression of PTX3 induced by high-volume ventilation, either alone or in combination with other pathological conditions, suggests that it may be an important mediator in ventilator-induced lung injury.
Null models, co-occurrence patterns, and ecological modelling of a Mediterranean community of snakes
Authors: Luiselli Luca , Filippi Ernesto
Published: August 2006

A Mediterranean community of snakes, inhabiting a hilly area in central Italy (Monterano, Tolfa Mountains) was statistically modelled to investigate whether: (i) it shows non-random structure as predicted by competition theories, (ii) there are proximate elements of the landscape that may predict the presence/absence of the various snake species at the study area, and (iii) the snakes select 'resting sites' which are relatively simple or relatively complicated in landscape structure. To investigate issue (i) we used co-occurrence pattern analyses and Monte Carlo simulations. To investigate issue (ii) we used logistic regression analysis on presence/absence data of eleven 'proximate landscape' variables around sites of presence for the snakes and around random (= absence) sites at the same study area. To investigate issue (iii), we used expected-versus-observed χ2 to test whether snake presences were associated more often than random with a combination of variables, i.e. with at least four different variables for each point of presence. The snake community was constituted by eight species, but only the five commonest species (i.e. Coluber viridiflavus, Elaphe longissima, Elaphe quatuorlineata, Natrix natrix, and Vipera aspis) were included in our models. Our modeling and simulation analyses suggested that: (i) the community structure was not competitively structured both in terms of habitat resource and in terms of 'proximate landscape' variables influencing snake presences; (ii) all five snake species were positively influenced by at least two of the eleven variables considered in the logistic regression model; (iii) four out of five species clearly selected sites with complicated structure, the only exception being Coluber viridiflavus.
Morphological changes in the female reproductive organs during mating in Colostethus stepheni and associated behaviour
Authors: Rodrigues Miguel Trefaut , Juncá Flora Acuña
Published: August 2006

Extended courtship and amplexus have been related either to readiness for spawning or to evaluation of the quality of egg-laying site. As preliminary observations revealed that a pair of C. stepheni can engage in two successive amplexi, an unusual pattern for dendrobatid frogs, we carried out experiments in the field to characterize this mating strategy. During the first hour after the first amplexus, we detect ovulation and changes in the oviduct morphology. The female could exhibit three different behavioural patterns, if disturbed after the first amplexus: remaining in the nest, leaving the nest and returning some minutes later, leaving the nest and subsequently enticed by their mate to another nearby nest. In cases where the male did not return for the second amplexus, the female sought another mate and engaged in a second amplexus.
Neuroendocrine modulation of stress response in the anuran, Rana esculenta
Authors: Mosconi Gilberto , Yamamoto Kazutoshi , Kikuyama Sakae , Carotti Marcello , Palermo Francesco , Polzonetti-Magni Alberta
Published: August 2006

In amphibians, as in other vertebrates, stress stimuli have been found to affect different functions, including development, growth, and reproduction. A wide range of responsiveness to stressors has been reported for amphibians; for instance, capture and/or captivity stress induced changes both in the hypothalamus-pituitary-interrenal and hypothalamus-pituitary-gonadal axes. However, few studies have examined the response to stress in terms of recovery and/or adaptation by applying stress paradigms for a short and long-term duration. In the present paper, the short-term captivity stress responses were evaluated in the anuran Rana esculenta by measuring peripheral corticosterone, androgens, prolactin (PRL), and growth hormone (GH) changes. Moreover, in long-term captivity and salinity stress, effects were evaluated by measuring peripheral PRL changes and those of PRL mRNA in the pituitary together with plasma corticosterone and androgens. Short-term (24 h) captivity stress induced an increase of peripheral corticosterone together with that of GH and PRL since these hormones are involved in the "alarm phase" and in energy demand of stressed animals. The opposite trend was found for peripheral androgens, in view of the negative effects exerted by stress in the reproductive axis. In long-term (1 month) captivity and salinity stress, responses were consistent with the increasing of PRL mRNA at pituitary level, through a long-loop feedback mechanism depending on the decreasing levels of peripheral PRL, whereas no changes were found in the levels of plasma corticosterone and androgens. Therefore, it seems that Rana esculenta activates different neuroendocrine mechanisms depending on the duration of stress and on the types of stressors.
The Development of an Austenitic Stainless Steel Bearing with High Corrosion Resistance and High Nonmagnetic Property
Authors: Tanaka S , Ueda K , Mitamura N , Oohori M
Published: August 2006

Apparatus of the type used in liquid crystal and semiconductor production facilities, medical inspection facilities, and linear motor cars utilize a magnetic field. When operated, either driven or rotated, they may experience a disturbance of the ambient magnetic field. This is more likely to occur if the driven or rotating portion of the apparatus is formed from a magnetic material. In recent years, bearings use in apparatus utilizing a magnetic field were made in precipitation hardening stainless steels such as Mn-Cr-V series or Mn-Cr-Ni-V series. Although these steels have excellent corrosion resistance, compared to martensitic stainless steels like AISI 440C, it is still not sufficient. In addition, the typical hardness of a precipitation hardening stainless steel used for bearings is about 446 HV. The low hardness of the steel means that the durability of the bearing is often unsatisfactory. Therefore, work was undertaken to develop a bearing steel with improved properties. In addition, to having improved corrosion resistance and durability, the steel must also have a very low magnetic permeability. This led to the development of a carburized AISI 316L austenitic stainless steel. The carburizing was carried out at 500°C to produce a surface layer with a hardness around 800∼1000 HV, while retaining the excellent corrosion resistance and low magnetic permeability associated with this type of steel. Tests carried out have shown that despite the thinness of the hardened layer and low core hardness, in certain applications bearings made in carburized AISI 316L exhibited excellent durability together with low friction characteristics.
Removal of Polychlorinated Phenols in Sequential Anaerobic–Aerobic Biofilm Reactors Packed with Tire Chips
Authors: Shin Hang‐Sik , Yoo Kyu‐Seon , Park Jae K.
Published: August 2006

Scrap vehicle tire chips were used as packing material for sequential anaerobic–aerobic biofilm reactors to remove persistent chlorinated hydrocarbons. Adsorption capacity of scrap tires was greater under acidic conditions than under basic conditions. However, it was only approximately 0.04 to 0.3% of that of activated carbon. The amount of biomass that attached to the surface of scrap tires was 3.16 and 3.72 mg volatile suspended solids/cm2 after 14 and 37 days, respectively. Two laboratory‐scale, down‐flow anaerobic–aerobic biofilm reactors packed with tire chips were operated to remove 2,4‐dichlorophenol (DCP) and 4‐chlorophenol (CP). More than 98% of DCP was dehalogenated to CP in the anaerobic reactor, 70 to 98% of which was subsequently degraded in the aerobic reactor. Scrap tires did not cause any operational problems when used as biofilter media.
Comparison of One‐Step Acidic Extraction Versus Two‐Step Basic and Acidic Extraction Procedures for Semivolatile Analysis of Wastewater
Authors: Khalil Mary S. , Kelada Nabih , Sawyer Bernard , Zenz David R. , Tata Prakasam , Lue‐Hing Cecil
Published: August 2006

The feasibility of using the U.S. Environmental Protection Agency's (U.S. EPA's) contract laboratory protocol method for analyzing semivolatile compounds in industrial wastewater pretreatment program samples was investigated because of time and labor savings involved. Various laboratory evaluation studies were conducted to determine whether this alternate one‐step acidic extraction method would give comparable results to U.S. EPA Method 625. These studies consisted of comparisons of method detection limits, spike recoveries in reagent water and actual field samples, and the precision between Method 625 and the alternate one‐step acidic extraction. More than 60 base‐neutral and acid extractables (55 target compounds and 6 surrogates) were used in the comparative study of method detection limits and spike recoveries of the two procedures. Using reagent water, one‐step acidic extraction gave consistently better recoveries than two‐step basic and acidic extraction. Similar results were obtained with representative field sample matrices. Based on results of this investigation, the Metropolitan Water Reclamation District of Greater Chicago, Illinois, submitted an application to U.S. EPA to have one‐step acidic extraction accepted as a site‐specific alternate test procedure for analyzing industrial wastewater samples. After thorough review, U.S. EPA Region V approved the use of this alternate one‐step acidic extraction method. It is recommended that other municipal analytical laboratories apply to U.S. EPA for similar approval.
Ion Exchange and Surface Charge on Montmorillonite Clay
Authors: Sperry James M. , Peirce J. Jeffrey
Published: August 2006

An ion‐exchange model originally developed for pure oxides prepared in the laboratory is extended to study of ion exchange and surface charge on a naturally occurring montmorillonite clay. The range of surface charges (−2.0 × 10−6 to 0 mol/m2) measured for montmorillonite with various electrolyte solutions and clay pretreatments is within the range of those measured for a wide variety of oxides prepared in the laboratory (−6.0 × 10−6 to 1.0 × 10−7 mol/m2), including MnO2‐IC1, MnO2‐IC12, MnO2‐IC22, titanium dioxide, ferric oxide, and aluminum oxide. In addition, fitted parameter values for lateral interaction constants and equilibrium constants for the acid sites that characterize ion exchange on montmorillonite are on the same order of magnitude as those obtained for pure oxides. Surface charge of montmorillonite in sodium nitrate solution is measured to be approximately 15 to 25% greater than that measured between a pH of 4 and 9 in calcium chloride solution. This difference is attributed to the greater charge on the calcium (2+) ion; thus, its stronger electrostatic attraction to the acid hydroxyl site. An order of magnitude change in solids concentration (Cp) can lead to a difference in measured net surface charge density of the same oxide sample of several orders of magnitude. This difference increases at higher pH, indicating the importance of reporting the corresponding Cp at which experiments are conducted.
Platinum Electrode Response in Anaerobic Sludge
Authors: Minton Monica , Molof Alan H.
Published: August 2006

Response time and stability of platinum electrodes in anaerobic environments are critical factors for determining the appropriate electrode potential in most experimental studies. In this research, several pretreatment techniques, including chemical and polarization (anodic and cathodic) methods, were investigated to find ones that reduced response time and enhanced electrode stability. Results indicated that chemical pretreatment of a dry platinum electrode with air, sludge, stannous chloride, and thioacetamide/hydrogen sulfide (H2S) and chemical pretreatment of a wet electrode by thioacetamide/H2S produced the most rapid stable response when the electrode was placed in an anaerobic sludge. Chemical pretreatment with 6 M nitric acid, water, hydrogen gas, and sludge was not effective. Pretreatment by cathodic polarization (H2 cathode in 0.05 M hydrochloric acid electrolyte) showed the best response (rapid and stable) with 94 to 97% of the 24‐hour reading in 20 minutes. These results are consistent with current understanding of the microbial processes and suggest that a rapid and stable response requires a coating of molecular hydrogen on the electrode surface.
Monitoring of the Effects of Additives on Sludge Separation Properties by Using Sensors
Authors: Vanderhasselt Alexis , Fuchs Andreas , Vanrolleghem Peter , Staudinger Gernot , Verstraete Willy
Published: August 2006

Two novel sensors, Settlometer and Sehlumosed, were used to evaluate the beneficial effect of three additives on sludge‐settling properties. Four different activated sludges were used in the study. The settling characteristics of the sludges were evaluated in automated batch settling tests by means of the start‐up time (initial lag period), initial settling velocity, stirred sludge volume, and final transparency of the supernatant. Different sludges responded in distinct ways to the dosage of additives. Talc was typically more effective than coal in terms of improving settling velocity and reducing sludge volume. Chemical polymer surpassed the two particulate additives in terms of final transparency. Furthermore, different sludge sedimentation parameters of a particular sludge were not affected to the same extent by a specific additive. This substantiates the need to describe settling properties with more than one parameter. The absolute values of the sedimentation properties were found to depend on the type of sensor used.
Splenectomy in plasma cell dyscrasias: A review of the clinical practice
Authors: Kapoor Prashant , Singh Ekta , Radhakrishnan Priya , Mehta Paulette
Published: August 2006

Plasma cell dyscrasias are a group of clinically and biochemically diverse disorders of unknown etiology, characterized by the disproportionate proliferation of one or more clones of B cells, and the presence of a structurally and electrophoretically homogeneous (monoclonal) immunoglobulin or polypeptide subunit in serum or urine. The role of splenectomy in the management of plasma cell dyscrasias has not been well defined. Using MEDLINE, the authors searched the English‐language published literature from the year 1970 through September 2005 to determine the indications for splenectomy in plasma cell dyscrasias.

A review of the literature in humans and animals supported the idea that the spleen provides a special microenvironment favorable for homing or differentiation of IgM producing B cells, and splenectomy can, at times, lead to remission in Waldenström's macroglobulinemia. The other reported reasons for splenectomy in plasma cell dyscrasias are hypersplenism‐related pancytopenia, control of splenic plasmacytomas, and management of a splenic abscess. Splenic infiltration in primary amyloidosis can be an indication for splenectomy, where removal of a large spleen can also reverse an acquired factor X deficiency. Thus, the spleen can be considered a potential target organ for management of plasma cell dyscrasias, and therapeutic success has been achieved with removal of this organ.

However, splenectomy can be a potentially morbid procedure in patients with plasma cell dyscrasias, and major postoperative complications include infection, hemorrhage, and thrombosis. Am. J. Hematol., 2006. © 2006 Wiley‐Liss, Inc.
Binding affinities/avidities of antibody–antigen interactions: Quantification and scale‐up implications
Authors: Zhang Huading , Williams P. Stephen , Zborowski Maciej , Chalmers Jeffrey J.
Published: August 2006

Bioaffinity interactions have been, and continue to be, successfully adapted from nature for use in separation and detection applications. It has been previously reported that the magnetophoretic mobility of labeled cells show a saturation type phenomenon as a function of the concentration of the free antibody–magnetic nanoparticle conjugate which is consistent with other reports of antibody–fluorophore binding. Starting with the standard antibody–antigen relationship, a model was developed which takes into consideration multi‐valence interactions, and various attributes of flow cytometry (FCM) and cell tracking velocimetry (CTV) measurements to determine both the apparent dissociation constant and the antibody‐binding capacity (ABC) of a cell. This model was then evaluated on peripheral blood lymphocytes (PBLs) labeled with anti CD3 antibodies conjugated to FITC, PE, or DM (magnetic nanoparticles). Reasonable agreements between the model and the experiments were obtained. In addition, estimates of the limitation of the number of magnetic nanoparticles that can bind to a cell as a result of steric hinderance was consistent with measured values of magnetophoretic mobility. Finally, a scale‐up model was proposed and tested which predicts the amount of antibody conjugates needed to achieve a given level of saturation as the total number of cells reaches 1010, the number of cells needed for certain clinical applications, such as T‐cell depletions for mismatched bone marrow transplants. © 2006 Wiley Periodicals, Inc.
Respirometric evaluation and modeling of glucose utilization by Escherichia coli under aerobic and mesophilic cultivation conditions
Authors: Insel G. , Celikyilmaz G. , Ucisik‐Akkaya E. , Yesiladali K. , Cakar Z.P. , Tamerler C. , Orhon D.
Published: August 2006

The study presents a mechanistic model for the evaluation of glucose utilization by Escherichia coli under aerobic and mesophilic growth conditions. In the first step, the experimental data was derived from batch respirometric experiments conducted at 37°C, using two different initial substrate to microorganism (S0/X0) ratios of 15.0 and 1.3 mgCOD/mgSS. Acetate generation, glycogen formation and oxygen uptake rate profile were monitored together with glucose uptake and biomass increase throughout the experiments. The oxygen uptake rate (OUR) exhibited a typical profile accounting for growth on glucose, acetate and glycogen. No acetate formation (overflow) was detected at low initial S0/X0 ratio. In the second step, the effect of culture history developed under long‐term growth limiting conditions on the kinetics of glucose utilization by the same culture was evaluated in a sequencing batch reactor (SBR). The system was operated at cyclic steady state with a constant mean cell residence time of 5 days. The kinetic response of E.coli culture was followed by similar measurements within a complete cycle. Model calibration for the SBR system showed that E. coli culture regulated its growth metabolism by decreasing the maximum growth rate (lower $\hat {\mu} _{\rm H}$) together with an increase of substrate affinity (lower KS) as compared to uncontrolled growth conditions. The continuous low rate operation of SBR system induced a significant biochemical substrate storage capability as glycogen in parallel to growth, which persisted throughout the operation. The acetate overflow was observed again as an important mechanism to be accounted for in the evaluation of process kinetics. Biotechnol. Bioeng. 2007;96: 94–105. © 2006 Wiley Periodicals, Inc.
Academic leadership: The pathway to and from
Authors: Strathe Marlene I. , Wilson Vicki W.
Published: August 2006

The chapter examines the characteristics of effective academic administrators and the pathways to and from an academic administrative position from the faculty member's perspective.
The rise and fall of administrative careers
Authors: Plater William M.
Published: August 2006

Managing and shaping the ascent of one's own career comes through understanding that what goes up must come down and that satisfaction in the experience is determined by recognizing the moment of balance.
Reflections on academic administration
Authors: Swain Mary Ann
Published: August 2006

Some conceptual frameworks guide the work of university administrators, informing effective hiring, planning, and budgeting.
Perspectives from the Dark Side: The career transition from faculty to administrator
Authors: Palm Risa
Published: August 2006

A number of challenges mark the transition from full‐time faculty member to academic administrator.
Transition from faculty to administrator and transition back to the faculty
Authors: Griffith Janice C.
Published: August 2006

Whereas the new administrator will seek to become comfortable and effective in a leadership role, former administrators back on the faculty will find the change of position and pace unsettling again.
Becoming “one of them” or “moving to the Dark Side”
Authors: Glick Milton D.
Published: August 2006

This recounting of the author's journey through a career as a faculty member and in various administrative positions offers lessons learned along the way.
How many lines must miss d points in a linear space
Authors: Metsch Klaus
Published: August 2006

It was remarked by P. Erdős, J. C. Fowler, V. T. Sós, and R. M. Wilson, (J Combin Theory Ser A 38, 1985, 131–142), that a non‐degenerate finite linear space on v points has the following property. For every point P the number of lines not passing through P is at least $\lfloor v-\sqrt v\rfloor$ with equality if and only if the linear space is a projective plane. We give a short proof for this result using an algebraic tool. The main purpose of the article however is to generalize this result in the direction that gives a lower bound for the number of lines not passing through a given number d of points. © 2006 Wiley Periodicals, Inc. J Combin Designs 14: 441–450, 2006
Retracts of box products with odd‐angulated factors
Authors: Che Zhongyuan , Collins Karen L.
Published: August 2006

Let G be a connected graph with odd girth 2κ+1. Then G is a (2κ+1)‐angulated graph if every two vertices of G are connected by a path such that each edge of the path is in some (2κ+1)‐cycle. We prove that if G is (2κ+1)‐angulated, and H is connected with odd girth at least 2κ+3, then any retract of the box (or Cartesian) product G□ H is S□T where S is a retract of G and T is a connected subgraph of H. A graph G is strongly (2κ+1)‐angulated if any two vertices of G are connected by a sequence of (2κ+1)‐cycles with consecutive cycles sharing at least one edge. We prove that if G is strongly (2κ+1)‐angulated, and H is connected with odd girth at least 2κ+1, then any retract of G□ H is S□T where S is a retract of G and T is a connected subgraph of H or |V(S)|=1 and T is a retract of H. These two results improve theorems on weakly and strongly triangulated graphs by Nowakowski and Rival [Disc Math 70 (1988), 169–184]. As a corollary, we get that the core of the box product of two strongly (2κ+1)‐angulated cores must be either one of the factors or the box product itself. Furthermore, if G is a strongly (2κ+1)‐angulated core, then either Gn is a core for all positive integers n, or the core of Gn is G for all positive integers n. In the latter case, G is homomorphically equivalent to a normal Cayley graph [Larose, Laviolette, Tardiff, European J Combin 19 (1998), 867–881]. In particular, let G be a strongly (2κ+1)‐angulated core such that either G is not vertex‐transitive, or G is vertex‐transitive and any two maximum independent sets have non‐empty intersection. Then Gn is a core for any positive integer n. On the other hand, let Gi be a (2κi+1)‐angulated core for 1 ≤ i≤ n where κ1 < κ2 < … < κn. If Gi has a vertex that is fixed under any automorphism for 1 ≤ i ≤ n‐1, or Gi is vertex‐transitive such that any two maximum independent sets have non‐empty intersection for 1 ≤ i ≤ n‐1, then □i=1n Gi is a core. We then apply the results to construct cores that are box products with Mycielski construction factors or with odd graph factors. We also show that K(r,2r+1) □ C2l+1 is a core for any integers l ≥ r ≥ 2. It is open whether K(r,2r+1) □ C2l+1 is a core for r > l ≥ 2. © 2006 Wiley Periodicals, Inc. J Graph Theory
Selective estrogen receptor‐α but not ‐β agonist treatment modulates brain α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptors
Authors: Le Saux Maryvonne , Estrada‐Camarena Erika , Di Paolo Thérèse
Published: August 2006

Estradiol was previously reported to decrease brain α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazoleproprionic acid (AMPA)‐receptor‐specific binding. The contributions of estrogen receptor subtypes in the estradiol modulation of AMPA receptors and its predominant subunit GluR2 are unknown. These experiments investigated whether an estrogenic receptor subtype is involved in the estradiol effect on AMPA‐receptor‐specific binding and GluR2 mRNA levels. Ovariectomized Sprague‐Dawley rats were treated 2 days after ovariectomy for 2 weeks with 17β‐estradiol, an agonist for ERα 4,4′,4′′‐(4‐propyl‐[1H]‐pyrazole‐1,3,5‐triyl)trisphenol (PPT), or an agonist for ERβ 2,3‐bis(4‐hydroxyphenyl)‐propionitrile (DPN) and compared with intact control rats. Uterus weights, used as aperipheral measure of estrogenic activity, were decreased after ovariectomy and increased by estradiol and PPT but not DPN treatments. In prefrontal and cingulate cortices, the striatum, and the nucleus accumbens, ovariectomy increased [3H]AMPA‐specific binding compared with intact controls, which was corrected by estradiol treatment. In all these brain regions, PPT, but not DPN, mimicked the estradiol decrease of AMPA‐receptor‐specific binding; in the cingulate cortex, the effect of PPT did not reach statistical significance. GluR2 mRNA levels of vehicle‐treated ovariectomized rats remained unchanged compared with intact rats in the brain regions investigated. Estradiol and PPT treatment but not DPN decreased GluR2 subunit mRNA levels in the prefrontal cortex and the striatum of ovariectomized rats, whereas no significant change was observed in the cingulate cortex or the nucleus accumbens. The present results suggest that an ERα is involved in the estradiol modulation of AMPA receptors in the cortex, striatum, and nucleus accumbens. © 2006 Wiley‐Liss, Inc.
Market risk and process uncertainty in production operations
Authors: Kamrad Bardia , Ord Keith
Published: August 2006

By adopting a real options framework we develop a production control model that jointly incorporates process and market uncertainties. In this model, process uncertainty is defined by random fluctuations in the outputs' yield and market risk through demand uncertainty for the output. In our approach, production outputs represent commodities or items for which financial contracts do not trade. Outputs are also functionally linked to the level of input inventories. To extend the model's applicability to a wide range of production industries, inputs are modeled to reflect either renewable or partially renewable or non‐renewable resources. Given this setting, techniques of stochastic control theory are employed to obtain value maximizing production policies in a constrained capacity environment. The rate of production is modeled as an adapted positive real‐valued process and analogously evaluated as a sequence of complex real options. Since optimal adjustments to the rate of production also functionally depend on the outputs' yield, we optimally establish “trigger boundaries” justifying controlled variations to the rate of production over time. In this context, we provide closed form analytic results and demonstrate their robustness with respect to the stochastic (including mean reverting) processes considered. Using these results, we also demonstrate that the value (net of holding costs) accrued to the producer from having an inventory of the output is equivalent to the producer's reservation price to operationally curb its process yield. These generalizations extend the scope of model applicability and provide a basis for applying the real options methodology in the operations arena. The model is explored numerically using a stylized example that allows for both output and demand uncertainty and achieves greater realism by incorporating an element of smoothing into the sequence of production decisions. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006
A hierarchical method for discrete structural topology design problems with local stress and displacement constraints
Authors: Stolpe Mathias , Stidsen Thomas
Published: August 2006

In this paper, we present a hierarchical optimization method for finding feasible true 0–1 solutions to finite‐element‐based topology design problems. The topology design problems are initially modelled as non‐convex mixed 0–1 programs.

The hierarchical optimization method is applied to the problem of minimizing the weight of a structure subject to displacement and local design‐dependent stress constraints. The method iteratively treats a sequence of problems of increasing size of the same type as the original problem. The problems are defined on a design mesh which is initially coarse and then successively refined as needed. At each level of design mesh refinement, a neighbourhood optimization method is used to treat the problem considered.

The non‐convex topology design problems are equivalently reformulated as convex all‐quadratic mixed 0–1 programs. This reformulation enables the use of methods from global optimization, which have only recently become available, for solving the problems in the sequence. Numerical examples of topology design problems of continuum structures with local stress and displacement constraints are presented. Copyright © 2006 John Wiley & Sons, Ltd.
Cationic, water‐soluble, fluorene‐containing poly(arylene ethynylene)s: Effects of water solubility on aggregation, photoluminescence efficiency, and amplified fluorescence quenching in aqueous solutions
Authors: Huang Yan‐Qin , Fan Qu‐Li , Lu Xiao‐Mei , Fang Chun , Liu Shu‐Juan , Yu‐Wen Li‐Hui , Wang Lian‐Hui , Huang Wei
Published: August 2006

Three novel fluorene‐containing poly(arylene ethynylene)s with amino‐functionalized side groups were synthesized through the Sonogashira reaction. They were poly{9,9‐bis[6′‐(N,N‐diethylamino)hexyl]‐2,7‐fluorenylene ethynylene}‐alt‐co‐{2,5‐bis[3′‐(N,N‐diethylamino)‐1′‐oxapropyl]‐1,4‐phenylene} (P1), poly{9,9‐bis[6′‐(N,N‐diethylamino)hexyl]‐2,7‐fluorenylene ethynylene} (P2), and poly({9,9‐bis[6′‐(N,N‐diethylamino)hexyl]‐2,7‐fluorenylene ethynylene}‐alt‐co‐(1,4‐phenylene)) (P3). Through the postquaternization treatment of P1–P3 with methyl iodide, we obtained their cationic water‐soluble conjugated polyelectrolytes (WSCPs): P1′–P3′. The water solubility was gradually improved from P3′ to P1′ with increasing contents of hydrophilic side chains. After examining the ultraviolet–visible absorption and photoluminescence (PL) spectra, fluorescence lifetimes, and dynamic light scattering data, we propose that with the reduction of the water solubility from P1′ to P3′, they exhibited a gradually increased degree of aggregation in H2O. The PL quantum yields of P1′–P3′ in H2O displayed a decreasing tendency consistent with the increased degree of aggregation, suggesting that the pronounced degree of aggregation was an important reason for the low PL quantum yields of WSCPs in H2O. Two structurally analogous water‐soluble trimers of P2′ and P3′, model compounds 2,7‐bis(9″,9″‐bis{6‴‐[(N,N‐diethyl)‐N‐methylammonium] hexyl}‐2″‐fluorenylethynyl)‐9,9‐bis{6′‐[(N,N‐diethyl)‐N‐methylammonium]hexyl}fluorene hexaiodide and 1,4‐bis(9′,9′‐bis{6″‐[(N,N‐diethyl)‐N‐methylammonium]hexyl}‐2′‐fluorenylethynyl)benzene tetraiodide, were synthesized. The amplified fluorescence quenching of these WSCPs by Fe(CN)64− in H2O was studied by comparison with a corresponding analogous trimer. The effects of aggregation on the fluorescence quenching may be two‐edged in these cases. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5778–5794, 2006
Coumarin‐containing poly(fluorenediylvinylene)s: Synthesis, photophysics, and electroluminescence
Authors: Barberis Vasilis P. , Mikroyannidis John A. , Cimrová Věra
Published: August 2006

Two new poly(fluorenediylvinylene)s (CV and CF) with coumarin side chains were synthesized via Heck coupling. The coumarin segments were attached to the C‐9 of fluorene through alkyl spacers. The polymers were soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. The photoluminescence (PL), electroluminescence (EL), and electrochemical behavior of these polymers were studied. CV and CF thin films exhibited broad‐band, bluish‐green and orange PL emissions, with maxima at 475 and 585 nm, respectively. These PL maxima were redshifted in comparison with those measured in THF solutions. Aggregate formation played an important role in the solid state. The aggregation was more pronounced in CF thin films than CV thin films. Both polymers oxidized and reduced irreversibly. Light‐emitting devices (LEDs) with indium tin oxide hole‐injecting and aluminum electron‐injecting electrodes were prepared and studied. The LEDs made of CV emitted green light, and the LEDs made of CF exhibited an orange EL emissions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5750–5762, 2006
Resonance impurity scattering in superconductivity in PrOs4Sb12
Authors: Parker D. , Haas S. , Maki K.
Published: August 2006

We study the effect of impurity scattering in the unitarity limit on the A‐ and B‐phase superconductivity in PrOs4Sb12. We take the triplet p + h‐wave superconducting order parameters and the impurity scattering is treated within the standard theory. We find the quasiparticle density of states and thermodynamics are very sensitive to the impurity scattering. The impurity scattering dependence of the superconducting transition temperature and the superconducting order parameter at T = 0 K are very similar to those in d‐wave superconductors. Some of these characteristics will provide a sensitive test of the symmetry of the underlying superconducting order parameters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic and optical properties of ZrB12 and YB6. Discussion on electron‐phonon coupling
Authors: Teyssier J. , Kuzmenko A. , van der Marel D. , Lortz R. , Junod A. , Filippov V. , Shitsevalova N.
Published: August 2006

We report the optical properties of high‐quality single crystals of low temperature superconductors zirconiumdodecaboride ZrB12 (Tc = 5.95 K) and yttrium hexaboride YB6 (Tc = 7.15 K) in the range 6 meV ‐ 4.6 eV at room temperature. The experimental optical conductivity was extracted from the analysis of the reflectivity in the infrared range and ellipsometry measurement of the dielectric function in the visible range. The electronic band structure of these compounds was calculated by the self‐consistent full‐potential LMTO method and used to compute the interband part of the optical conductivity and the plasma frequency Ωp . A good agreement was observed between the interband part of the experimental optical conductivities and the band structure calculations. Different methods combining optical spectroscopy, resistivity, specific heat measurements and results of band structure calculations are used to determine the electron‐phonon coupling constant. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of boron substitution on the crystallographic structure and superconducting properties in Y1‐xBxBa2Cu3Oy system
Authors: Mani D. K. , Zouaoui M. , Ben Azzouz F. , Annabi M. , Ben Salem M.
Published: August 2006

The changes in crystallographic and transport properties in the polycrystalline Y1‐xBxBa2Cu3Oy (YBBaCuO) compounds with x ranging from 0 to 0.55 have been investigated. Samples were synthesized using standard solid state reaction technique. The structure for all samples was characterized by X‐ray diffraction with Rietveld refinements technique. Their transport properties were measured by the standard four probe method in the temperature range from 20 to 300 K. The crystal lattice parameters are found to change due to the boron doping and YBBaCuO samples undergo to a structural phase transition from orthorhombic to tetragonal at x of more than 0.3. With the increase of x the transition temperature (Tconset) decreases. The dependence of resistivity on temperature, and the relation of the structural parameters versus the content of boron are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetoelastic effects in the YFe10V2 ferromagnetic alloy
Authors: Khandan Fadafan H. , Alinejad M. R. , Tajabor N. , Fruchart D. , Gignoux D.
Published: August 2006

Magnetoelastic effects in the YFe10V2 alloy between 5 and 300 K, and under magnetic fields up to 6 T are studied. Results show that spontaneous magnetostriction of the sample is positive in agreement with what is observed in similar iron based compounds and with the well known increase of the exchange interactions with interatomic distances. Two mechanisms of the forced magnetostriction, in polycrystalline samples, were clearly identified. The mechanism associated with the rotation of magnetization is of single ion origin and leads to a negative contribution to the volume magnetostriction. The other mechanism, mainly of two ions origin, is the same as the one responsible for the spontaneous magnetostriction. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of temperature on the electronic structure in n‐modulation‐doped AlxGa(1–x)As/GaAs heterostructure
Authors: Dakhlaoui H. , Jaziri S.
Published: August 2006

We theoretically study the subband structure of n‐modulation‐doped AlxGa(1–x)As/GaAs heterostructure using a self‐consistent procedure to solve simultaneously the Schrödinger and Poisson equations. Our results show that the sheet electron concentration can be modified by both increasing the temperature and the spacer thickness. The results also indicate that the energy levels are not prolonged linearly as the temperature increases but show step‐like behavior. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lattice dynamics and the electromechanical properties of BaTiO3 in tetragonal phase
Authors: Khalal Ali , Khatib Driss
Published: August 2006

A lattice dynamical formalism using the shell model (R. A. Cowley, Phys. Rev. 134, A981 (1964) [1]) is applied to ferroelectric crystal BaTiO3, in the tetragonal phase. This microscopic model includes the short‐range interactions of axially symmetric type and the long‐range Coulomb interactions takes into account the electronic polarizability of constituent ions. The stability conditions of crystal are used to determine several first‐derivatives potential for the crystals. Zone center phonons are used for fitting. In general, we obtained the best agreement between the calculated and observed frequencies. A calculation of the oblique phonons and electromechanical coupling are presented and compared with the available experimental data. It can be seen that, the electromechanical coupling is at a maximum when the acoustic wave is polarized parallel to the polar c‐axis, and there is zero coupling when the polarization is perpendicular to this axis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of nano‐sized manganese ferrite (MnFe2O4) via coprecipitation method
Authors: Amighian J. , Mozaffari M. , Nasr B.
Published: August 2006

Nano‐sized manganese ferrite (MnFe2O4) powder has been synthesized via coprecipitation method, using FeSO4·7H2O and MnSO4·H2O as starting materials. An aqueous solution of the starting materials, containing Fe2+ and Mn2+ in the ratio required in the ferrite, was poured into an NaOH alkaline solution. A greenish precipitate was formed, which carefully washed and dried for 6 h at 80 °C. The dried powder was then heated for 2 h at different temperatures in argon atmosphere and then rapidly cooled to room temperature, using water quenching. XRD patterns of the samples show that the sample annealed at 1050 °C is single phase. Also using Scherrer's formula a mean crystallite size of 80 nm was obtained. Magnetic measurements were performed on cold pressed pellets, using a sensitive permeameter with a maximum field of 1.2 T. The results show that a single phase MnFe2O4 nano‐sized powder can be obtained at annealing temperature of 1050 °C, which is lower than 1250 °C related to the annealing temperature of the same ferrite, prepared by the conventional ceramic technique. Saturation magnetization of the single‐phase sample was 1330 G, which is lower than 5000 G related to a bulk sample. The difference between the values is reasonable, because the magnetic measurements were performed on cold‐pressed unsintered nano sized powders. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evidence of non‐linear to linear transformation of the normal state resistivity in YBCO at constant oxygen content
Authors: Abdelhadi M. M.
Published: August 2006

We studied the origin of variation in the magnitude and temperature dependence of the normal state resistivity frequently observed in different Y Ba2Cu3O7–δ (YBCO) single crystal or thin film samples with the same T C. We investigated the temperature dependence of resistivity in YBCO thin films, which were subjected to annealing in argon at 120 – 140 °C or aging at room temperature in air. Before annealing (or aging) these films exhibited a non‐linear in‐plane resistivity ρ a b (T), with upward deviation (flattening) in ρ a b (T) from the linear high temperature behavior below 220‐230 K. For all films the annealing causes an increase of resistivity and a transformation of ρ a b (T) from a non‐linear dependence towards a more linear one (less flattening). Our proposed model provides explanation of these phenomena based on the thermally activated redistribution of residual O(5) oxygen in the chain‐layer of YBCO without any change in the overall oxygen content within the sample. The results show that a perfectly linear ρ (T) can be observed in YBCO of oxygen content 7 – δ as low as 6.8. The agreement between the our data for ρ a b (T; t) and the proposed model was very good. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Remanent magnetization of Fe1–xCox fine particles
Authors: Sebt S. A. , Zoriasatain S. , Akhavan M.
Published: August 2006

Fine Fe1–xCox grains with various values of x have been grown via the borohydride method in the presence of different magnetic fields, H0. In this method, the presence of magnetic moments at the bcc lattice sites of iron causes the formation of acicular single domain grains with a nearly 0.2 μm length. The magnetic field, H0, sets the magnetic moment of SD grains parallel to each other and forms some chains of these particles. This is equivalent to the presence of an effective internal field that increases the remanent magnetization, Mr. From the SW model point of view, the remanent magnetization of sample is determined by Boltzman distribution function at the two minimum energies. In fact, it is the thermal fluctuation that is responsible for the reduction of remanent magnetization. Therefore, in addition to the coercivity effect, the presence of an effective internal field also increases the Mr. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)