bluuebunny/crossref_metadata_2025 huggingface dataset:
Posterior hyoid space as related to excision of the thyroglossal duct cyst
Authors: Maddalozzo John , Alderfer Jeremy , Modi Vikash
Published: July 2010

Objectives/Hypothesis:

The anatomy of the anterior neck in the area of the hyoid, thyrohyoid membrane, and epiglottis is herein redescribed and compared to its classical depiction. The concept of the posterior hyoid space (PHS) is defined and substantiated through review of archived tissue and cadaver larynx dissection as well as by observation at many surgical dissections. The true anatomy of these relationships provides an insight into the effectiveness of the Sistrunk procedure. The author believes that recurrence of thyroglossal duct cysts (TGDC) occurs as a consequence of incomplete resection of: 1) microscopic suprahyoid ductules and/or 2) infra‐ and perihyoid tissue.

Study Design:

The senior author has been using the concept of the posterior hyoid space as applied to the Sistrunk procedure for more than 20 years. A retrospective study was done on cases from April 2003 to August 2008, and outcome was reviewed and compared to historical controls to determine the impact of applying this anatomic concept.

Methods:

A retrospective chart review was undertaken on 60 surgical cases performed for a 5‐year period with clinical follow‐up extended to an additional 7 months. Data collected included age at surgery, presenting symptoms, imaging characteristics, thyroid status, pathology results, and postoperative complications. All 60 were under the age of 18 who underwent a modified Sistrunk procedure and had a postoperative diagnosis of TGDC. Each patient had a minimum follow‐up period of 4 months to check for recurrences. No revision was included in this study.

Results:

Sixty patients met criteria for the study. There was one recurrence (1.67%); a complication rate of 6.67%. Complications were minor and wound related. Mean follow‐up was 17 months.

Conclusions:

The technique of applying the concept of a PHS to ensure the complete resection of the middle third of the hyoid bone and offending tissues is believed to decrease recurrence of TGDC secondary to incomplete resection in the perihyoid area. Laryngoscope, 2010
Deformation of nasal septum during nasal trauma
Authors: Lee Shu Jin , Liong Kyrin , Lee Heow Pueh
Published: July 2010

Background:

Injury to the nasal septum is commonly found in most nasal fractures. The nasal septum deforms and crumples, leading to nasal deviation and internal nasal obstruction.

Aim:

This study aims to identify the main areas of high stress concentration when a dynamic anteroposterior load is applied to the nasal tip, simulating nasal trauma. We wish to determine if the nasal septum acts as a crumpled zone, and deforms significantly during nasal trauma.

Materials and Methods:

An idealized and a patient‐specified finite element model have been generated for the present study. Several models with various combinations of narrower angle at the Vomer Ethmoidal Junction (VEJ) are also constructed from this septum model. Finite element analyses are carried out to determine the deformation and stress distribution in the nasal septum when a dynamic anteroposterior load is applied to the nasal tip.

Conclusions:

The maximum stress areas in the nasal septum are in the vicinity of the bony‐cartilaginous (BC) junction and the anterior nasal spine (ANS), which are consistent with clinical experience. A larger anteroposterior load, a longer loading duration, and a more acute VEJ angle would result in higher maximum stresses. The observations were identical in both idealized and patient‐specific models. The findings of this analysis also suggest that the septum does function as a crumpled zone, absorbing a significant amount of stress before it is transmitted to the skull. Laryngoscope, 2010
To love or to work: Must we choose?
Authors: Kofodimos Joan R.
Published: July 2010

Larry Grant was a model of competence and effectiveness, a manager whose work life at Chemco consisted of success after success. But is there enough time for him to be a husband and father as well? Is time really the issue?
Implementing strategy: Developing organizations and executives together
Authors: Kaplan Robert E.
Published: July 2010

When organizations take a new direction, key jobs can change. New requirements and different criteria for effectiveness in high‐level positions may have profound implications for the success of a new strategy.
The Narrow Band
Authors: Morrison Ann M. , White Randall P. , Van Velsor Ellen
Published: July 2010

Women are increasingly becoming a part of management. What will it take for women to become executives? What factors will move them upward? What will keep them from succeeding? These were some of the questions the authors attempted to answer during a study of executive women. What follows is an excerpt from their forthcoming book.
Brent's world
Authors: Lombardo Michael M.
Published: July 2010

Perhaps the key to understanding how executives learn from experience is to look at how a teenager learns from experience. The contexts are vastly different, but the type of experience and the process of learning are remarkably similar.
AB‐polymer Networks with Cooligoester and Poly(n‐butyl acrylate) Segments as a Multifunctional Matrix for Controlled Drug Release
Authors: Wischke Christian , Neffe Axel T. , Steuer Susi , Engelhardt Eva , Lendlein Andreas
Published: July 2010

Semi‐crystalline AB‐copolymer networks from oligo[(ε‐caprolactone)‐co‐glycolide]dimethacrylates and n‐butylacrylate have recently been shown to exhibit a shape‐memory functionality, which may be used for self‐deploying and anchoring of implants. In this study, a family of such materials differing in their molar glycolide contents χG was investigated to determine structure–property functional relationships of unloaded and drug loaded specimens. Drug loading and release were evaluated, as well as their degradation behavior in vitro and in vivo. Higher χG resulted in higher loading levels by swelling and a faster release of ethacridine lactate, lower melting temperature of polymer crystallites, and a decrease in shape fixity ratio of the programmed temporary shape. For unloaded networks, the material behavior in vivo was independent of the mechanical load associated with different implantation sites and agreed well with data from in vitro degradation studies. Thus, AB networks could be used as novel matrices for biofunctional implants, e.g., for urogenital applications, which can self‐anchor in vivo and provide mechanical support, release drugs, and finally degrade in the body to excretable fragments.

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Preparation and Properties of Novel Triphenylpyridine‐Containing Hyperbranched Polyimides Derived from 2,4,6‐Tris(4‐aminophenyl)pyridine under Microwave Irradiation
Authors: Chen W. , Yan W. , Wu S. , Xu Z. , Yeung K. W. K. , Yi C.
Published: July 2010

A novel ${\rm BB'}_{{\rm 2}} $‐type triamine was synthesized for the first time and employed to prepare a series of amine‐ and anhydride‐terminated triphenylpyridine‐containing hyperbranched polyimides under microwave irradiation. The structure of the triamine monomer and polymers were verified by FTIR and 1H NMR spectroscopy. The predominantly amorphous polyimides were soluble in m‐cresol, NMP, DMSO, DMAc and DMF at room temperature or upon heating. The polymers showed glass transition temperatures above 310 °C and a 5 and 10% weight‐loss temperature above 482 and 559 °C. Tensile strength and modulus were higher than 53.1 MPa and 1.01 GPa, respectively. AM‐HBPI‐2 and AD‐HBPI‐2 showed UV‐Vis absorptions in the region 200–400 and 200–350 nm and displayed strong purple and blue fluorescence.

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Controlling Fiber Repulsion in Multijet Electrospinning for Higher Throughput
Authors: Kumar Arun , Wei Ming , Barry Carol , Chen Julie , Mead Joey
Published: July 2010

A novel electrospinning set‐up has been developed to successfully electrospin multiple jets with controlled fiber repulsion using a plastic filter. This set‐up shows reduced fiber repulsion as compared to a multineedle set‐up, along with increased throughput. The effect of processing parameters on the fiber repulsion in a multineedle set‐up was also studied. It was found that fiber repulsion could be reduced by controlling emitter voltage and emitter/collector distance. Other important parameters studied included fiber distribution and throughput. It was found that the plastic filter set‐up produced fibers with lower mean diameters and better uniformity. This novel plastic filter design for electrospinning provides increased electrospinning rates with better fiber uniformity.

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On a Geometric Formula for the Fundamental Solution of Subelliptic Laplacians
Authors: Beals Richard , Gaveau Bernard , Greiner Peter
Published: July 2010

This paper introduces a new method for constructing fundamental solutions and parametrices for a class of second order subelliptic operators. The method is applied to obtain an explicit fundamental solution for the sublaplacian associated to the hypersurface [lm z2 = |z1|2k] ⊂ ℂ2. The fundamental solution is expressed as an integral over the characteristic variety of an expression whose denominator is a Hamiltonian action function and whose numerator solves an associated second order transport equation.
Avatars as information: Perception of consumers based on their avatars in virtual worlds
Authors: Bélisle Jean‐François , Bodur H. Onur
Published: July 2010

The presence of consumers and companies in the virtual worlds has increased in recent years. It is predicted that 80% of active Internet consumers and Fortune 500 companies will have an avatar or presence in a virtual community, including social networks, by the end of 2011 (eMarketer,2007). The increase in the number of consumers with avatars emphasizes the need for a better understanding of who these consumers behind the avatars really are in order to convert these individuals to online and real‐world customers. The objective of this paper is to investigate how avatars reflect the personality of their creators (targets) in virtual worlds. Using the Brunswik Lens Model as the theoretical framework, an investigation of real consumers in the virtual worldSecond Lifereveals that perceivers who view targets' avatar use particular thin‐slices of observations such as avatar cues (e.g., attractiveness, gender, hairstyle) to form accurate personality impressions about targets. The findings support the premise that real‐life companies that intend to expand to virtual worlds can use member avatars as a proxy for member personality and lifestyles. As a future research direction, avatars and other consumer‐generated media could be used as the basis for targeting and segmentation of online consumers. © 2010 Wiley Periodicals, Inc.
Materialism and its relationship to individual values
Authors: Kilbourne William E. , LaForge Mary C.
Published: July 2010

The nature of materialism has been of interest to scholars for many years. Of particular recent interest have been the correlates of materialism and their relationship to each other. This study examined the relationship between individual values, demographics, and materialism. Both self‐enhancement and self‐transcendence values were examined using data from a telephone survey with a random sample of 303 U.S. respondents. It was hypothesized that self‐enhancement is positively related to materialism and self‐transcendence is negatively related. The results suggest that the relationship between values and materialism is more complex than believed previously. Analysis of variance revealed several interactions that were of potential importance for both public policy and marketing strategy. Of particular interest was the interaction between self‐enhancement and self‐transcendence. © 2010 Wiley Periodicals, Inc.
Sp1 upregulates the four and half lim 2 (FHL2) expression in gastrointestinal cancers through transcription regulation
Authors: Guo Zheng , Zhang Wenjing , Xia Guosheng , Niu Lingyun , Zhang Yan , Wang Xinying , Zhang Yali , Jiang Bo , Wang Jide
Published: July 2010

In this study, our purpose is to clarify the role of specificity protein 1 (Sp1) in transcription activation of the four and half lim 2 (FHL2). pLuc595 which contained −1163nt to −568nt upstream ATG starting codon displayed the highest while pLuc382 (−950nt to −568nt) displayed lowest transcription activities in GI cancer cells. Meanwhile, suppression of Sp1 by siRNA or chemical inhibitor, mithramycin A (MIT) inhibited the promoter activity and FHL2 expression. Bioinformatics analysis showed two putative Sp1 binding elements within pLuc595 while EMSA assay demonstrated that the wild type but not the mutated probe containing the distal element bound to the cell nuclear protein specifically. Mutation of the distal Sp1 binding sequence suppressed the transcription activity of pLuc595. In vivo study showed that both Sp1 and FHL2 were highly expressed by cancer cells but not the normal GI tissues with their expressions being positive correlated. These data identified a functional Sp1 positively regulatory element (−1058nt to −1049nt) within FHL2 promoter, and the positive correlation between Sp1 and FHL2 in expressing pattern and signal mechanism strongly suggested their synergized effect in carcinogenesis and progression of GI cancers. © 2010 Wiley‐Liss, Inc.
Downregulation of programmed cell death 4 by inflammatory conditions contributes to the generation of the tumor promoting microenvironment
Authors: Yasuda Michiko , Schmid Tobias , Rübsamen Daniela , Colburn Nancy H. , Irie Kazuhiro , Murakami Akira
Published: July 2010

Ample evidence has shown key roles of inflammation in tumor promotion and carcinogenesis, and tumor‐associated macrophages are known to promote tumor growth and dissemination. Programmed cell death 4 (Pdcd4) is a novel tumor suppressor, and although various studies have revealed that the functions and expression mechanisms of Pdcd4 in tumor promotion, those in regard to inflammation remain unclear. In the present study, we examined whether inflammatory stimuli regulate Pdcd4 expression. 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) suppressed expression of pdcd4 mRNA in human monocytic cell lines (U937, THP‐1). Similarly, the bacterial endotoxin lipopolysaccharide (LPS) downregulated pdcd4 level in mouse RAW264.7 and peritoneal macrophages. Furthermore, conditioned medium from LPS‐stimulated RAW264.7 macrophages suppressed pdcd4 mRNA in RAW264.7 macrophages, and findings obtained with recombinant tumor necrosis factor‐α (TNF‐α) and TNF‐α‐specific siRNA suggested that TNF‐α partly mediates LPS‐triggered Pdcd4 downregulation via an autocrine mechanism. Specific inhibitors of phosphoinositide‐3‐kinase (PI3K) and c‐jun N‐terminus kinase (JNK) restored LPS‐abolished pdcd4 mRNA. Consistently, in MCF7 mammary carcinoma cells, conditioned medium from TPA‐differentiated/activated U937 cells suppressed pdcd4 mRNA. Additionally, knockdown of pdcd4 in RAW264.7 macrophages using siRNA significantly enhanced LPS‐induced TNF‐α protein production, and interferon‐γ, CC chemokine ligand (Ccl) 1, Ccl20, and interleukin‐10 mRNA expression. These results suggest that Pdcd4 suppresses the induction of these inflammatory mediators. Taken together, loss of Pdcd4 in macrophages may be a critical step in establishing the inflammatory environment while that in tumor cells contributes to tumor progression. © 2010 Wiley‐Liss, Inc.
Decreased expression of thrombomodulin is correlated with tumor cell invasiveness and poor prognosis in nonsmall cell lung cancer
Authors: Liu Po‐Len , Tsai Jong‐Rung , Chiu Chien‐Chih , Hwang Jhi‐Jhu , Chou Shah‐Hwa , Wang Chih‐Kuang , Wu Shu‐Jing , Chen Yuh‐Lien , Chen Wen‐Chi , Chen Yung‐Hsiang , Chong Inn‐Wen
Published: July 2010

Thrombomodulin (TM) plays a role in coagulation, inflammation, and cell adhesion. Reduction of TM expression plays an important role in the tumor metastatic process; however, insufficient information is available regarding the expression of TM in nonsmall cell lung cancer (NSCLC). Sixty NSCLC patients who underwent surgery were reviewed for TM expression and multiple variables were assessed by univariate and multivariate analyses. The expression level of TM and its metastatic ability were examined in vitro using the human NSCLC A549 cell line. TM expression in NSCLC was significantly correlated with survival; the 5‐yr survival rates of patients with high and low TM expression were 23% and 18% (P < 0.01), respectively. Distribution of TM was detected predominantly in the normal lung tissue compared with lung cancer tissue. Western blot analysis showed, on average, decreased expression levels of TM protein in the lung cancer tissues of patients with NSCLC. An in vitro study also showed that overexpression of TM can inhibit the invasiveness and migration ability of the A549 cell line, whereas silencing of TM significantly enhanced these processes. This inhibition of cellular migration by overexpression of TM was significantly prevented by the selective inhibitors of PI3K and Akt, but not by MAPK inhibitors. This study demonstrates that a decrease in TM expression may be an indicator in the prognosis of NSCLC patients and provides new insights into the molecular mechanisms of TM in the metastasis of NSCLC. © 2010 Wiley‐Liss, Inc.
Role of acidic sphingomyelinase in thymol‐mediated dendritic cell death
Authors: Xuan Nguyen Thi , Shumilina Ekaterina , Schmid Evi , Bhavsar Shefalee K. , Rexhepaj Rexhep , Götz Friedrich , Gulbins Erich , Lang Florian
Published: July 2010

Scope: Thymol is a component of several plants with antimicrobial activity. Little is known about the effects of thymol on immune cells of the host. This study addressed the effects of thymol on dendritic cells (DCs), regulators of innate and adaptive immunity.

Methods and results: Immunohistochemistry, Western blotting and fluorescence‐activated cell sorting analysis were performed in bone marrow‐derived DCs either from wild‐type mice or from mice lacking acid sphingomyelinase (ASM−/−) treated and untreated for 24 h with thymol (2–100 μg/mL). Thymol treatment resulted in activation of ASM, stimulation of ceramide formation, downregulation of anti‐apoptotic Bcl‐2 and Bcl‐xL proteins, activation of caspase 3 and caspase 8, DNA fragmentation as well as cell membrane scrambling. The effects were dependent on the presence of ASM and were lacking in ASM−/− mice or in wild‐type DCs treated with sphingomyelinase inhibitor amitriptyline.

Conclusion: Thymol triggers suicidal DC death, an effect mediated by and requiring activation of ASM.
Hydro‐ethanolic extract of cashew tree (Anacardium occidentale) nut and its principal compound, anacardic acid, stimulate glucose uptake in C2C12 muscle cells
Authors: Tedong Leonard , Madiraju Padma , Martineau Louis C. , Vallerand Diane , Arnason John T. , Desire Dzeufiet D. P. , Lavoie Louis , Kamtchouing Pierre , Haddad Pierre S.
Published: July 2010

Scope: Products of cashew tree (Anacardium occidentale) are used in traditional medicine for various ailments, including diabetes.

Methods and results: The anti‐diabetic properties of cashew plant parts were studied using differentiated C2C12 myoblasts (myotubes) and rat liver mitochondria. Hydroethanolic extract of cashew seed (CSE) and its active component, anacardic acid (AA), stimulated glucose transport into C2C12 myotubes in a concentration‐dependent manner. Extracts of other parts (leaves, bark and apple) of cashew plant were inactive. Significant synergistic effect on glucose uptake with insulin was noticed at 100 μg/mL CSE. CSE and AA caused activation of adenosine monophosphate‐activated protein kinase in C2C12 myotubes after 6 h of incubation. No significant effect was noticed on Akt and insulin receptor phosphorylation. Both CSE and AA exerted significant uncoupling of succinate‐stimulated respiration in rat liver mitochondria.

Conclusion: Activation of adenosine monophosphate‐activated protein kinase by CSE and AA likely increases plasma membrane glucose transporters, resulting in elevated glucose uptake. In addition, the dysfunction of mitochondrial oxidative phosphorylation may enhance glycolysis and contribute to increased glucose uptake. These results collectively suggest that CSE may be a potential anti‐diabetic nutraceutical.
Pterostilbene induces autophagy and apoptosis in sensitive and chemoresistant human bladder cancer cells
Authors: Chen Rong‐Jane , Ho Chi‐Tang , Wang Ying‐Jan
Published: July 2010

Scope: Bladder cancer is one of the most common malignancies in the world. The majority of bladder cancer deaths are due to unresectable lesions that are resistant to chemotherapy. Pterostilbene (PT), a naturally occurring phytoalexin, possesses a variety of pharmacologic activities, including antioxidant, cancer prevention activity and cytotoxicity to many cancers. We found that PT effectively inhibits the growth of sensitive and chemoresistant human bladder cancer cells by inducing cell cycle arrest, autophagy and apoptosis. Down‐regulations of Cyclin A, B and D1 and pRB are the results of PT‐induced cell cycle arrest.

Methods and results: Autophagy occurred at an early stage and was observed through the formation of acidic vesicular organelles (the marker for autophagy) and microtubule‐associated protein 1 light chain 3‐II production. Apoptosis occurred at a later stage and was detected by Annexin V and 4′,6‐diamidino‐2‐phenylindole staining. PT‐induced autophagy was triggered by the inhibition of active human protein kinase/the mammalian TOR/p70S6K pathway and activation of extracellular signal‐regulated kinase pathway. Inhibition of autophagy by pretreatment with 3‐methyladenine, bafilomycin A1, Beclin 1 or extracellular signal‐regulated kinase short hairpin RNA enhanced PT‐triggered apoptosis.

Conclusion: This is the first study to demonstrate that PT causes autophagy in cancer cells and suggests that PT could serve as a new and promising agent for the treatment of sensitive and chemoresistant bladder cancer cells.
Isothiocyanate sulforaphane inhibits protooncogenic ornithine decarboxylase activity in colorectal cancer cellsviainduction of the TGF‐β/Smad signaling pathway
Authors: Kaminski Bettina M. , Loitsch Stefan M. , Ochs Meike J. , Reuter Kerstin C. , Steinhilber Dieter , Stein Jürgen , Ulrich Sandra
Published: July 2010

Scope:The objective of this study was to elucidate molecular mechanisms behind the antitumor activities of the isothiocyanate sulforaphane (SFN) in colorectal cancer cells.

Methods and results:Cell growth was determined by BrdU incorporation and crystal violet staining. Protein levels were examined by Western blot analysis. Ornithine decarboxylase (ODC) activity was assayed radiometrically. Reverse transcriptase‐PCR was used for measuring mRNA expression. For reporter gene assays plasmids were transfected into cells via lipofection and luciferase activity was measured luminometrically. Acetyl‐histone H3 and H4 chromatin immunoprecipitation (ChIP) assays were performed followed by PCR with TGF‐β‐receptor II promoter specific primers. We could show that SFN‐mediated cell growth inhibition closely correlates with a dose‐dependent reduction of protein expression and enzymatic activity of ODC. This effect seems to be due to reduced protein levels and transactivation activity of transcription factor c‐myc, a direct regulator of ODC expression, as a consequence of SFN‐induced TGF‐β/Smad signaling. The coherency of these results was further confirmed by using TGF‐β receptor kinase inhibitor SB431542, which largely abolishes inhibitory effects of SFN on both, ODC activity and cell growth.

Conclusion:Since elevated ODC enzyme activity is associated with enhanced tumor development, SFN may be a dietary phytochemical with potential to prevent carcinogenesis.
Wenn ein Chemiestudium nicht das Richtige ist
Authors: van Ahn Jessica
Published: July 2010

Ein Drittel aller Chemiestudenten brechen ihr Studium ab und kehren der Universität endgültig den Rücken. Abbrecher, die zwar vom Chemiestudium überfordert sind, aber Spaß am Fach haben, können zwischen verschiedenen Berufsausbildungen wählen. Beratung bieten Universitäten und die Agentur für Arbeit an.
Akademia‐Industrie‐Austausch:ein Schuss Neugier und Offenheit
Authors: Schneider Jörg J.
Published: July 2010

Die jüngst gestartete AIA‐Initiative der GDCh und des Fonds der Chemischen Industrie soll Akademia und Industrie wieder enger miteinander verzahnen. Im Rahmen dessen hat Jörg Schneider von der TU Darmstadt im Konzeptlabor von Merck geforscht. Er berichtet über seine Erfahrungen.
Sauber ins GC/MS
Authors: Lerch Oliver
Published: July 2010

Um Pestizidrückstände in Obst und Gemüse zu analysieren, ist eine Extraktion mit anschließender GC/MS‐Analyse die Methode der Wahl. Die Rohextrakte enthalten aber meist noch schwer verdampfbare Bestandteile. Die Lösung des Problems: ein zwischengeschalteter automatisierter Reinigungsschritt.
Konkurrenz fürs Laborbuch
Authors: Domnich Alexej , Schöning Sebastian , Bottländer Dominik
Published: July 2010

Eine intelligente Pipette pipettiert und misst gleichzeitig. Sie protokolliert Messdaten automatisch und überträgt sie drahtlos an vernetzte Rechner.
Ein tiefer Blick ins Glas
Authors: Wizenmann Tobias
Published: July 2010

Ist der Dornfelder zu sauer? Enthält der Merlot zu viel Zucker? Bei der Qualitätskontrolle von Wein hilft die FT‐IR‐Spektroskopie: Sie bestimmt viele Parameter in einer Messung.
55 000 Ölproben im Jahr titrieren
Authors: Muhr Hans‐Joachim
Published: July 2010

Wägen ist genauer als Pipettieren — aber Wägen braucht mehr Zeit und ist schwer zu automatisieren. Was tun bei vielen Tausend viskosen Ölproben im Jahr? Ein System von Mettler‐Toledo pipettiert und titriert die Proben automatisch.
Three‐phase medium model for filled rock joint and interaction with stress waves
Authors: Ma G. W. , Li J. C. , Zhao J.
Published: July 2010

A three‐phase medium model is proposed in describing the dynamic property of filled rock joints and an analytical study on longitudinal wave transmission normally across a three‐phase rock joint is presented. Parameters in the three‐phase medium model were determined by a series of modified split Hopkinson pressure bar (SHPB) tests, where a sand or clay layer was used to represent an artificially filled rock joint. The effect of the unloading path on the transmitted wave was discussed by comparing the analytical and SHPB test results. The derived wave transmission coefficients across the filled joint agreed very well with those from the test results. Both the analytical and the test results showed that the wave transmission coefficients were affected by the mechanical properties of the fillings. Parametric studies with respect to the volume ratios of water and air in the three‐phase medium and the type of filling material have also been performed. Copyright © 2010 John Wiley & Sons, Ltd.
Dental chipping: Contrasting patterns of microtrauma in inuit and European populations
Authors: Scott G. Richard , Winn J. R.
Published: July 2010

While the study of dental wear has enjoyed wide popularity for over 100 years, dental chipping, or microfractures of the tooth crown, has received little attention. Observations on dental chipping in populations from the Arctic (St. Lawrence Island, Alaska) and Europe (medieval Norway and Spain) reveal patterns of microtrauma that provide insights into the dietary and tooth‐tool use behaviour of earlier populations. St. Lawrence Island Inuit, with an emphasis on consuming tough and frozen foods, in combination with extensive tooth‐tool use, exhibit a pattern of chipping that is characterised as ‘molar dominant’. The two European samples exhibit an ‘incisor‐dominant’ pattern but contrast markedly in frequencies, with medieval Norwegians showing significantly more chipping than medieval and post‐medieval Spanish. The systematic study of chipping promises to provide a new perspective on how populations used and/or abused their dentitions in earlier times. Copyright © 2010 John Wiley & Sons, Ltd.
Stochastic control of a pension fund model with first‐order Markov‐dependent parameters
Authors: Parlar Mahmut
Published: July 2010

The well known problem of the optimal control of a stochastic discrete linear system with independent parameters and with a quadratic objective functional is generalized to the case where the parameters of the system constitute a first‐order Markov chain. The solution to this more general problem is obtained by the principles of stochastic dynamic programming, and the ‘bi‐feedback’ nature of the optimal controls is explained. The results are applied to the solution of a 25‐period stochastic pension funding problem where it is assumed that the market returns constitute a first‐order Markov chain.
Application of improved optimal regulator technique to power electronics
Authors: Tsuchiya Takeshi , Osiadacz A. , Bell D. J.
Published: July 2010

A control system synthesis method for a multi‐input and multi‐output system with input dead time, input variable constraints, and state variable inequality constraints is described. A practical control algorithm which is suitable for microprocessor implementation is derived from the method and is applied to an induction motor control problem. Good simulation results are obtained, although the designed control system is suboptimal. The control system configuration designed by this method is explained clearly. It is proved that integral actions as well as proportional actions are introduced so as to guarantee good steady‐state characteristics in spite of parameter variations of the controlled object. Moreover, a kind of derivative action is introduced to compensate for input dead time effects.
State parameterization approach to the solution of optimal control problems
Authors: Sirisena H. R. , Chou F. S.
Published: July 2010

A direct method for solving optimal control problems by parameterizing state variables is developed. This state parameterization (SP) procedure is first formulated for a general class of problem. Next, a simpler and more efficient alternative version of the SP algorithm is developed for an important special class of problems, namely those involving systems that can be cast into a multivariable non‐linear phase‐variable form. The modified SP algorithm in particular avoids explicit integration of the system state and costate differential equations. The algorithm is tested on two problems which are parameterized in terms of cubic splines.
Long‐term optimization of hydro‐thermal power systems by generalized Conjugate‐Gradient Methods
Authors: Sirisena H. R. , Halliburton T. S.
Published: July 2010

The optimal management of hydro storage reservoirs is considered. The objective is to minimize thermal power station fuel costs, over a horizon of one or more years, in a mixed hydro‐thermal power system. A model of the New Zealand system is developed that is simple enough for computational purposes but nevertheless accounts for all major factors including load diversity and transmission losses. A version of Powell's generalized conjugate‐gradient algorithm with Beale restarts is used for the optimization. State and control constraints are enforced by penalty functions and transformations, respectively. Results are presented for a reduced‐order model of the New Zealand system.
Method of successive approximations for solution of optimal control problems
Authors: Chernousko F. L. , Lyubushin A. A.
Published: July 2010

The paper contains a survey of results devoted to one of the numerical methods of optimal control—the method of successive approximations. This method is based on Pontryagin's maximum principle and is known in the English literature as the min‐H method. Various modifications of the method and some theoretical results on its convergence are presented. Examples of applications of the method for the calculation of optimal trajectories are given. The method of small parameters which is close to the method of successive approximations, is also described.
Optimal control of store‐and‐forward networks
Authors: Filipiak Janusz
Published: July 2010

This paper describes a general point of view on the subject of store‐and‐forward queueing networks. A systematic approach to a store‐and‐forward network as a whole is applied. This allows network problems which involve dynamic optimization of congestion control and routing to be treated in a common framework. The dynamic model applied is non‐linear and can be handled straightforwardly by optimal control system theory. It is shown that under normal operational conditions the optimal flow pattern is given by the steady‐state solution of the costate equations. Properties of the optimal flow pattern are examined in detail. Then, schemes of the operation of the network under different operating conditions are discussed at length. It is shown that the optimal control strategies depend on the total volume of traffic forwarded to the network. Algorithms are developed for different traffic demand patterns, and a numerical example is also given.
Ellipsoidal bounds for sets of attainability and uncertainty in control problems
Authors: Chernousko F. L.
Published: July 2010

The guaranteed approach to a description of uncertainties in control problems is developed and is based on an approximation of sets to which uncertain vectors belong by means of optimal ellipsoids. Optimal and suboptimal algebraic operations with ellipsoids (sum, intersection) are presented. By means of these operations, differential equations are obtained which describe the evolution of ellipsoids which provide external and internal bounds on the attainable sets for linear controlled systems. The developed theory is generalized for non‐linear systems and is applied to obtain bounds in optimal control problems and differential games and to obtain minimax filtering in systems with incomplete information. Some examples are also given.
Stability and optimal exploitation over an infinite time horizon of interacting populations
Authors: Haurie A.
Published: July 2010

Models of optimal control of two‐species ecological systems are considered on an infinite time horizon. Conditions are obtained under which the optimal exploitation of the system is stabilizing. Thus, a stationary state toward which all optimal trajectories must converge is defined. This extends to this class of models, the co‐called turnpike property of optimal economic growth models.
A Numerical method for optimization of distributed parameter structures with displacement constraints
Authors: Haug Edward J.
Published: July 2010

Recent results in design differentiation of structural displacement are used to develop an iterative optimization method that explicitly treats bounds on the maximum displacement of structural elements. Computable design derivative expressions are employed, and a finite‐element computational algorithm is presented for obtaining design derivatives needed in structural optimization. A function‐space, gradient‐projection, optimization technique which uses these derivatives is presented. The method is applied to beam and plate optimization problems to illustrate its use and to evaluate its computational efficiency. Results obtained using this method are compared with solutions reported in the literature. The method is shown to be both generally applicable and numerically efficient.
Program CC's implementation of the wiener‐hopf lqg optimal control problem
Authors: Thompson Peter M.
Published: July 2010

The linear quadratic Gaussian (LQG) optimal control problem of single‐input‐single‐output (SISO) analogue and digital systems can be solved using Wiener‐Hopf techniques of spectral and partial factorization. A new form of the Wiener‐Hopf result is derived, followed by a description of how the solution is implemented in Program CC, a user‐friendly, command driven, computer‐aided‐control‐system‐design (CACSD) package.
Optimal expansion of the canadian tar sands industry
Authors: Dupont Serge , Fuller J. David
Published: July 2010

Our model minimizes the discounted cost of meeting projected Canadian oil demand from the currently inexpensive but limited conventional oil, more expensive tar sands and still more expensive imports. We limit the rates of increase of the three sources of supply and impose non‐negativity constraints on two of the state variables, conventional supply and imports. The optimal control is generalized bang‐bang, but the set of extreme points depends on the status of the state constraints. All possible optimal sequences of extreme point controls are determined. Implications for tar sands development policy are discussed, along with economic interpretations and additions to the theory of exhaustible resources.
Self‐tuning control of bilinear systems
Authors: Burnham K. J. , James D. J. G. , Shields D. N.
Published: July 2010

In this paper, a self‐tuning pole‐placement control algorithm is proposed for a class of single‐input‐single‐output bilinear systems. Use is made of a time‐step quasi‐linearization procedure, within an extended state‐space framework, recursively updated in order to implement a suboptimal pole‐placement control strategy.

Use of a two‐tier adaptive mechanism is proposed within the recursive estimation procedure and involves the use of variable forgetting factor reset coupled with covariance reset. Simulation studies indicate that this approach gives rise to increased alertness and adaptivity of the self‐tuner, leading to improved performance in terms of both system stability and parameter tracking ability.
Efficiency‐optimized speed control system in separately excited DC‐motor drives—performance index method
Authors: Egami Tadashi , Kanamori Yu Kihiro , Tsuchiya Tak Eshi
Published: July 2010

This paper proposes a synthesis method for an efficiency‐optimized speed control system using a performance index including loss term. Since the performance index almost includes the loss term at the steady state, suboptimal efficiency is obtained. The speed response is controlled by tuning the values of the weighting factors at the transient state. The effectiveness is shown in simulation and experimental studies, and the system is more efficient than the usual control systems with constant field excitation.
Critical control weighting for non‐minimum‐phase stochastic control systems
Authors: Lim C. C. , Hang C. C. , Leong K. Y.
Published: July 2010

Because of its capability of handling non‐minimum‐phase zeros and its simplicity in digital implementation, the generalized minimum‐variance control strategy has been used extensively in the design of stochastic digital control systems. However, the choice of a suitable control weighting factor within the performance index is not always straightforward and very often designers have to rely on a trial‐and‐error approach. This paper establishes conditions on the limits of the weighting factor for closed‐loop stability. Expressions for computing exactly the minimum stability value of control weighting for processes modelled by a dead time plus a rational transfer function of up to fourth order are derived.
Discrete‐time optimal control of an economic system using different objective functions
Authors: Sandblom C.‐L. , Eiselt H. A. , Jörnsten K. O.
Published: July 2010

In most applications of optimal control of econometric models, the objective (welfare cost) functions employed are quadratic, although some authors have suggested linear functions. One reason for choosing the quadratic objective function is that with linear system dynamics, the optimal trajectories can easily be computed by using the Riccati equation approach. With a linear objective function and with constraints on the control and/or the state variables, large‐scale linear programming techniques can be used instead of the Riccati equation to obtain optimal trajectories.

In this paper, not only piecewise quadratic but also piecewise linear minimax‐and entropy‐type objective functions are considered. As an illustration, the 35‐equation CLEAR model of Canada is optimized with various of these objective functions and the results are then compared. The relative merits of the different approaches are discussed from an economic policy point of view. Algorithmic and numerical solution aspects are also addressed.
An incentive‐compatible resource allocation problem allowing collusion
Authors: Chiu Samuel S. , Lin Qing
Published: July 2010

This paper extends recent results on an incentive‐compatible modification of the Heal algorithm for resource allocation. Previous research has shown, under some assumptions, that the participants can be induced to report the truth in their own interest so as to achieve a group optimum. Using the same modified procedure, we show that if we allow secret collusion among users, participants can be induced to report quasi‐accurate information in their own interest so as to achieve a group optimum. The instantaneous convergence rate (in terms of a Lyapunov function) is faster when we allow collusion.
Well‐posedness of a model order reduction for singularly perturbed linear stochastic systems
Authors: Gajic Zoran
Published: July 2010

An order reduction problem for the state estimation of singularly perturbed linear systems is shown to be a well‐posed problem, whereas the corresponding order reduction control problem is ill‐posed. This observation plays an important role in the concept of multimodeling and in the slow—fast decomposition control problem for singularly perturbed linear stochastic systems.
Stochastic two‐target pursuit‐evasion differential games in three dimensions
Authors: Yavin Y. , Miloh T.
Published: July 2010

Stochastic versions of a three‐dimensional two‐target ‘game of two cars’ and a three‐dimensional two‐target ‘homicidal chauffeur’ game are considered. These are used to model a dogfight, in the (x, y, z) space, between a very agile player Q and a less manoeuvrable player P. A numerical study is conducted, by numerically solving a non‐linear partial differential equation, to investigate the role of the parameters of manoeuvrability, speed and the performance of the ‘weapon systems’ in the encounter.
Sliding‐horizon optimal and certainty‐equivalent controllers for stabilizing stochastic‐parameter systems
Authors: Yaz Engin
Published: July 2010

This paper introduces novel control schemes to stabilize linear discrete stochastic‐parameter systems. It is shown that under some mild conditions, controllers that are optimal in the sense of minimizing a finite sliding‐horizon performance index subject to linear stochastic‐parameter system constraint are stabilizing for the system in both senses of almost‐sure and mean‐square asymptotic stability. Moreover, if the uncertainties of stochastic parameters are small enough, the designer can even stabilize these systems by the use of controllers that are designed on the basis of the deterministic equivalent of these systems.
On Applications of a new method for computing optimal non‐linear feedback controls
Authors: Bourdache‐Siguerdidjane Houria
Published: July 2010

A new method of computing optimal non‐linear feedbacks is used for regulating the angular momentum of spacecraft using both reaction jets and flywheels. It is shown that the optimal feedback law satisfies a system of first‐order, quasi‐linear, partial differential equations. The integration of these equations by the method of characteristics gives the non‐linear feedback control. This control reduces the angular velocities of the space vehicle to zero by minimizing the fuel consumption.

The optimal regulation, under reaction jet control alone and with the flywheels at fixed angular velocities, is considered. The special case where these velocities are zero leads readily to the known analytical solution of the feedback law, which is linear in the state although the dynamics is non‐linear.
Distributed control of layered orthotropic plates with damping
Authors: Adali S. , Sadek I. S. , Sloss J. M. , Bruch J. C.
Published: July 2010

Optimal control of a composite rectangular plate on an elastic foundation is studied with the objective of minimizing its dynamic response in a given period of time with the minimum possible expenditure of force. The plate undergoes transient vibrations starting from specified initial displacement and velocity distributions, and the control is exercised by optimally determining the transverse distributed force. The multiple objectives of the problem are taken into account by adopting a vector performance criterion comprising quadratic functional of the deflection, velocity and distributed force. The sufficiency condition of optimality is derived using control theory results which lead to an analytic solution of the problem. Numerical results are given for simply supported plates made of specially orthotropic layers of boron‐fibre‐reinforced plastic material. It is demonstrated that the effectiveness of the proposed control depends on the lamination order, foundation modulus, viscous damping, aspect ratio and terminal time as well as on the weight factors attached to various cost functionals.
Optimal transmission and jamming strategies in a communication channel
Authors: Cassandras Christos G.
Published: July 2010

A zero‐sum differential game model is presented for two players who are both transmitting information and jamming their opponent at the same time, under channel capacity constraints. The problem for each player is to find an optimal policy for allocating this capacity over the duration of the game. Given a cost function for the game, conditions are determined under which equilibrium strategies exist. These (pure) strategies are found to be of the bang‐bang variety and depend on game parameters such as the channel capacity and jamming effectiveness of the players, as well as the duration of the game.
Optimization of freeway traffic control problems
Authors: Mahmoud Maodi S. , Eid Shawki Z.
Published: July 2010

The problem of optimal freeways traffic control is described by a detailed non‐linear discrete‐time model. A four‐level hierarchical algorithm is developed to compute the optimal control strategies. Simulation results indicate the efficiency of the developed algorithm in bringing congested traffic flow back to normal operation.
A hierarchical approach to optimized control of water distribution systems: Part I decomposition
Authors: Coulbeck B. , Brdyś M. , Orr C. H. , Rance J. P.
Published: July 2010

Consideration is given to the problem of evaluating optimized control schedules for common types of water distribution systems. For these systems the major operating costs are associated with electricity charges for pumped source supplies. This paper provides a rigorous formulation for system operations. Proposals are then made for hierarchical decomposition into these levels: an upper level for dynamic optimization of reservoir storage, an intermediate level for static optimization of source extraction and a tower level for static optimization of individual sources.
Variational method for the distributed control of a vibrating beam
Authors: Sadek I. S.
Published: July 2010

The problem of damping out the oscillations of a simply supported beam subject to viscous damping is solved analytically by employing a maximum principle. The basic control problem is to minimize the deflection and the velocity of displacements in a given period of time with the minimum possible expenditure of force. The multiobjective problem is scalarized by using a linear combination of the criteria. This problem is also solved by two heuristic approaches: a direct method and an integral equation approach.
Stability analysis of adaptive systems: An Approach based on controller structure optimality
Authors: Ortega R.
Published: July 2010

In this paper we approach the problem of establishing stability conditions for adaptive controllers from a different perspective: namely, we are interested in knowing when a controller structure that minimizes a linear quadratic criterion can be adaptively implemented to ensure global stability. The main result is the proof that, for systems of relative degree zero, controller structures that solve the linear quadratic optimal control (LQOC) problem1 are globally stable when the parameters are adaptively updated. Interestingly enough, no positive realness or matchability assumption is required to establish the result.