bluuebunny/crossref_metadata_2025 huggingface dataset:
A mobile element-based evolutionary history of guenons (tribe Cercopithecini)
Authors: Xing Jinchuan , Wang Hui , Zhang Yuhua , Ray David A , Tosi Anthony J , Disotell Todd R , Batzer Mark A
Published: February 2007

Background

Guenons (tribe Cercopithecini) are a species-rich group of primates that have attracted considerable attention from both primatologists and evolutionary biologists. The complex speciation pattern has made the elucidation of their relationships a challenging task, and many questions remain unanswered. SINEs are a class of non-autonomous mobile elements and are essentially homoplasy-free characters with known ancestral states, making them useful genetic markers for phylogenetic studies.

Results

We identified 151 novel Alu insertion loci from 11 species of tribe Cercopithecini, and used these insertions and 17 previously reported loci to infer a phylogenetic tree of the tribe Cercopithecini. Our results robustly supported the following relationships: (i) Allenopithecus is the basal lineage within the tribe; (ii) Cercopithecus lhoesti (L'Hoest's monkey) forms a clade with Chlorocebus aethiops (African green monkey) and Erythrocebus patas (patas monkey), supporting a single arboreal to terrestrial transition within the tribe; (iii) all of the Cercopithecus except C. lhoesti form a monophyletic group; and (iv) contrary to the common belief that Miopithecus is one of the most basal lineages in the tribe, M. talapoin (talapoin) forms a clade with arboreal members of Cercopithecus, and the terrestrial group (C. lhoesti, Chlorocebus aethiops and E. patas) diverged from this clade after the divergence of Allenopithecus. Some incongruent loci were found among the relationships within the arboreal Cercopithecus group. Several factors, including incomplete lineage sorting, concurrent polymorphism and hybridization between species may have contributed to the incongruence.

Conclusion

This study presents one of the most robust phylogenetic hypotheses for the tribe Cercopithecini and demonstrates the advantages of SINE insertions for phylogenetic studies.
Lipids and essential fatty acids in patients presenting with self-harm
Authors: Garland Malcolm R. , Hallahan Brian , McNamara Mairead , Carney Philip A. , Grimes Helen , Hibbeln Joseph R. , Harkin Andrew , Conroy Ronan M.
Published: February 2007

Background

Low cholesterol has been reliably demonstrated in people who self-harm.

Aims

To determine whether people who self-harm also have low levels of essential fatty acids (EFAs) and to examine associations between the EFAs and serotonergic function.

Method

Depression, impulsivity and suicidal intent were measured in patients with self-harm (n=40) and matched controls, together with plasma lipids and EFAs. Platelet serotonergic studies were carried out in a subgroup (n=27).

Results

Patients with self-harm had significantly more pathology on all psychometric measures, lower mean total cholesterol levels (418 (s.d. =0.93)v.4.87 (s.d.=0.83) mmol/l,P=0.003) and lower mean total EFA levels (89. 5 (15.6)v.103.7 (17.1) μg/ml,P=0.0001) than controls after adjustment for confounding variables. Total n-3 and n-6 EFA levels were also significantly lower. Impulsivity and depression scores were significantly inversely correlated with both n-6 EFAs and n-3 EFAs, but were not associated with total or low-density lipoprotein cholesterol levels. Platelet serotonergic measures did not differ between groups, and were not related to psychobiological measures.

Conclusions

Lower plasma EFA levels combined with low cholesterol concentrations were associated with self-harm as well as impulsivity and affect. This was not related to platelet serotonergic measures.
Mental health following terrorist attacks
Authors: Whalley Matthew G. , Brewin Chris R.
Published: February 2007

We review the current literature relating to mental health following terrorist attacks. Studies assessing symptoms of stress in the general population and those assessing the mental health of direct victims are considered. Use of mental health services following an attack is reviewed and recommendations are offered.
Exception from Informed Consent Enrollment in Emergency Medical Research: Attitudes and Awareness
Authors: Triner Wayne , Jacoby Liva , Shelton Wayne , Burk Mathew , Imarenakhue Samual , Watt James , Larkin Gregory , McGee Glenn
Published: February 2007

Objectives

To explore attitudes surrounding exception from informed consent enrollment into research studies. In addition, the authors sought to determine the level of awareness of such an ongoing study among potential subjects, as defined by their presence in an emergency department (ED).

Methods

A convenience sample of urban academic ED patients and visitors was surveyed during a visit regarding their attitudes and awareness of an emergency exception from informed consent, blood‐substitute trial ongoing in the community.

Results

There was a 13% refusal rate, and 32% of those approached had characteristics that met exclusion criteria. There were 497 surveys analyzed. There was a predominance of women, Caucasians, and persons with at least some college education. Only 39 (8%) of respondents reported awareness of the ongoing blood substitute trial, and only 19 (4%) were able to list a risk or benefit of participation. Education, income, and age were not associated with reported awareness. Male gender, younger age, awareness of the existing exception from informed consent study, and being married were associated with greater acceptability for such enrollment practices.

Conclusions

The overall awareness of an ongoing exception from informed consent trial after community consultation and notification was low. A population with potential for enrollment in such a study did not demonstrate a high degree of acceptance of such practices. There were differences among certain demographic groups in the degree of acceptance. These differences may guide institutional review boards and investigators in community‐consultation strategies for future waiver of or exception from informed consent studies.
Depot-Specific Modulation of Rat Intraabdominal Adipose Tissue Lipid Metabolism by Pharmacological Inhibition of 11β-Hydroxysteroid Dehydrogenase Type 1
Authors: Berthiaume Magalie , Laplante Mathieu , Festuccia William , Gélinas Yves , Poulin Sébastien , Lalonde Josée , Joanisse Denis R. , Thieringer Rolf , Deshaies Yves
Published: February 2007

The metabolic consequences of visceral obesity have been associated with amplification of glucocorticoid action by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in adipose tissue. This study aimed to assess in a rat model of diet-induced obesity the effects of pharmacological 11β-HSD1 inhibition on the morphology and expression of key genes of lipid metabolism in intraabdominal adipose depots. Rats fed a high-sucrose, high-fat diet were treated or not with a specific 11β-HSD1 inhibitor (compound A, 3 mg/kg·d) for 3 wk. Compound A did not alter food intake or body weight gain but specifically reduced mesenteric adipose weight (−18%) and adipocyte size, without significantly affecting those of epididymal or retroperitoneal depots. In mesenteric fat, the inhibitor decreased (to 25–50% of control) mRNA levels of genes involved in lipid synthesis (FAS, SCD1, DGAT1) and fatty acid cycling (lipolysis/reesterification, ATGL and PEPCK) and increased (30%) the activity of the fatty acid oxidation-promoting enzyme carnitine palmitoyltransferase 1. In striking contrast, in the epididymal depot, 11β-HSD1 inhibition increased (1.5–5-fold) mRNA levels of those genes related to lipid synthesis/cycling and slightly decreased carnitine palmitoyltransferase 1 activity, whereas gene expression remained unaffected in the retroperitoneal depot. Compound A robustly reduced liver triacylglycerol content and plasma lipids. The study demonstrates that pharmacological inhibition of 11β-HSD1, at a dose that does not alter food intake, reduces fat accretion specifically in the mesenterical adipose depot, exerts divergent intraabdominal depot-specific effects on genes of lipid metabolism, and reduces steatosis and lipemia.
Estrogen-Induced Activation of Hypoxia-Inducible Factor-1α, Vascular Endothelial Growth Factor Expression, and Edema in the Uterus Are Mediated by the Phosphatidylinositol 3-Kinase/Akt Pathway
Authors: Kazi Armina A. , Koos Robert D.
Published: February 2007

Vascular endothelial growth factor (VEGF) plays an essential role in normal uterine physiology and function as well as endometrial cancer and other uterine disorders. Recently we showed that estrogen regulation of VEGF expression in the rat uterus involves rapid recruitment of both estrogen receptor (ER)-α and hypoxia-inducible factor (HIF)-1α to the VEGF promoter. Estrogen is known to stimulate both the MAPK and phosphatidylinositol 3-kinase (PI3K) pathways, which have been linked to the activation of both of these transcription factors. Therefore, the involvement of these pathways in estrogen-induced VEGF expression was investigated. Inhibitors of the MAPK (U0126) or PI3K pathways (wortmannin or LY294002) were administered ip to immature female rats 1 h before 17β-estradiol (E2) treatment. E2 activation of both pathways occurred and was completely inhibited by the appropriate antagonist. Only PI3K inhibitors, however, blocked E2 stimulation of VEGF mRNA expression and E2-induced uterine edema. In vivo chromatin immunoprecipitation analysis showed that this was associated with a failure of both HIF-1α and ERα to bind to the VEGF promoter. To determine whether inhibiting the PI3K pathway affected ERα induction of other estrogen target genes, the expression of creatine kinase B and progesterone receptor A/B was also examined. The expression of each was also inhibited by wortmannin, as was ERα binding to the creatine kinase B promoter. In conclusion, although estrogen activates both the MAPK and PI3K pathways in the rat uterus, activation of HIF-1α and ERα, and therefore regulation of VEGF gene expression is dependent only on the PI3K/Akt pathway. Furthermore, activation of the PI3K pathway appears to be a common requirement for the expression of estrogen-induced genes. These findings not only shed light on estrogen action in normal target tissues but also have important implications for cancer biology because excessive PI3K, HIF-1α, and VEGF activity are common in estrogen-dependent tumors.
New functions for a vertebrate Rho guanine nucleotide exchange factor in ciliated epithelia
Authors: Panizzi Jennifer R. , Jessen Jason R. , Drummond Iain A. , Solnica-Krezel Lilianna
Published: February 2007

Human ARHGEF11, a PDZ-domain-containing Rho guanine nucleotide exchange factor (RhoGEF), has been studied primarily in tissue culture, where it exhibits transforming ability, associates with and modulates the actin cytoskeleton, regulates neurite outgrowth, and mediates activation of Rho in response to stimulation by activated Gα12/13 or Plexin B1. The fruit fly homolog, RhoGEF2, interacts with heterotrimeric G protein subunits to activate Rho, associates with microtubules, and is required during gastrulation for cell shape changes that mediate epithelial folding. Here, we report functional characterization of a zebrafish homolog of ARHGEF11 that is expressed ubiquitously at blastula and gastrula stages and is enriched in neural tissues and the pronephros during later embryogenesis. Similar to its human homolog,zebrafish Arhgef11 stimulated actin stress fiber formation in cultured cells,whereas overexpression in the embryo of either the zebrafish or human protein impaired gastrulation movements. Loss-of-function experiments utilizing a chromosomal deletion that encompasses the arhgef11 locus, and antisense morpholino oligonucleotides designed to block either translation or splicing, produced embryos with ventrally-curved axes and a number of other phenotypes associated with ciliated epithelia. Arhgef11-deficient embryos often exhibited altered expression of laterality markers, enlarged brain ventricles, kidney cysts, and an excess number of otoliths in the otic vesicles. Although cilia formed and were motile in these embryos, polarized distribution of F-actin and Na+/K+-ATPase in the pronephric ducts was disturbed. Our studies in zebrafish embryos have identified new, essential roles for this RhoGEF in ciliated epithelia during vertebrate development.
Fxna, a novel gene differentially expressed in the rat ovary at the time of folliculogenesis, is required for normal ovarian histogenesis
Authors: Garcia-Rudaz Cecilia , Luna Felix , Tapia Veronica , Kerr Bredford , Colgin Lois , Galimi Francesco , Dissen Gregory A. , Rawlings Neil D. , Ojeda Sergio R.
Published: February 2007

In rodents, the formation of ovarian follicles occurs after birth. In recent years, several factors required for follicular assembly and the growth of the newly formed follicles have been identified. We now describe a novel gene, Fxna, identified by differential display in the neonatal rat ovary. Fxna encodes an mRNA of 5.4 kb, and a protein of 898 amino acids. Fxna is a transmembrane metallopeptidase from family M28, localized to the endoplasmic reticulum. In the ovary, Fxna mRNA is expressed in granulosa cells; its abundance is maximal 48 hours after birth, i.e. during the initiation of follicular assembly. Reducing Fxna mRNA levels via lentiviral-mediated delivery of short hairpin RNAs to neonatal ovaries resulted in substantial loss of primordial, primary and secondary follicles,and structural disorganization of the ovary, with many abnormal follicles containing more than one oocyte and clusters of somatic cells not associated with any oocytes. These abnormalities were not attributable to either increased apoptosis or decreased proliferation of granulosa cells. The results indicate that Fxna is required for the organization of somatic cells and oocytes into discrete follicular structures. As an endoplasmic reticulum-bound peptidase, Fxna may facilitate follicular organization by processing precursor proteins required for intraovarian cell-to-cell communication.
Extremely high-power tongue projection in plethodontid salamanders
Authors: Deban Stephen M. , O'Reilly James C. , Dicke Ursula , van Leeuwen Johan L.
Published: February 2007

Many plethodontid salamanders project their tongues ballistically at high speed and for relatively great distances. Capturing evasive prey relies on the tongue reaching the target in minimum time, therefore it is expected that power production, or the rate of energy release, is maximized during tongue launch. We examined the dynamics of tongue projection in three genera of plethodontids (Bolitoglossa, Hydromantes and Eurycea), representing three independent evolutionary transitions to ballistic tongue projection, by using a combination of high speed imaging,kinematic and inverse dynamics analyses and electromyographic recordings from the tongue projector muscle. All three taxa require high-power output of the paired tongue projector muscles to produce the observed kinematics. Required power output peaks in Bolitoglossa at values that exceed the greatest maximum instantaneous power output of vertebrate muscle that has been reported by more than an order of magnitude. The high-power requirements are likely produced through the elastic storage and recovery of muscular kinetic energy. Tongue projector muscle activity precedes the departure of the tongue from the mouth by an average of 117 ms in Bolitoglossa, sufficient time to load the collagenous aponeuroses within the projector muscle with potential energy that is subsequently released at a faster rate during tongue launch.
Adhesive recruitment by the viscous capture threads of araneoid orb-weaving spiders
Authors: Opell Brent D. , Hendricks Mary L.
Published: February 2007

The sticky prey capture threads of orb-webs are critical to web performance. By retaining insects that strike the web, these spirally arrayed threads allow a spider time to locate and subdue prey. The viscous capture threads spun by modern orb-weaving spiders of the Araneoidea clade replaced the dry, fuzzy cribellar capture threads of the Deinopoidea and feature regularly spaced moist, adhesive droplets. The stickiness of a cribellar thread is limited by its tendency to peel from a surface after the adhesion generated at the edges of contact is exceeded. In this study we test the hypothesis that viscous thread overcomes this limitation by implementing a suspension bridge mechanism (SBM) that recruits the adhesion of multiple thread droplets. We do so by using contact plates of four widths to measure the stickiness of six species' viscous threads whose profiles range from small, closely spaced droplets to large, widely spaced droplets. The increased stickiness registered by an increased number of thread droplets supports the operation of a SBM. However, the accompanying decrease in mean per droplet adhesion shows that droplets interior to the edges of thread contact contribute successively less adhesion. Models developed from these data suggest that the suspension bridge mechanism is limited to a span of approximately 12 droplets.
Pushing the limit: masticatory stress and adaptive plasticity in mammalian craniomandibular joints
Authors: Ravosa Matthew J. , Kunwar Ravinder , Stock Stuart R. , Stack M. Sharon
Published: February 2007

Excessive, repetitive and altered loading have been implicated in the initiation of a series of soft- and hard-tissue responses or `functional adaptations' of masticatory and locomotor elements. Such adaptive plasticity in tissue types appears designed to maintain a sufficient safety factor, and thus the integrity of given element or system, for a predominant loading environment(s). Employing a mammalian species for which considerable in vivo data on masticatory behaviors are available, genetically similar domestic white rabbits were raised on diets of different mechanical properties so as to develop an experimental model of joint function in a normal range of physiological loads. These integrative experiments are used to unravel the dynamic inter-relationships among mechanical loading, tissue adaptive plasticity, norms of reaction and performance in two cranial joint systems:the mandibular symphysis and temporomandibular joint (TMJ).

Here, we argue that a critical component of current and future research on adaptive plasticity in the skull, and especially cranial joints, should employ a multifaceted characterization of a functional system, one that incorporates data on myriad tissues so as to evaluate the role of altered load versus differential tissue response on the anatomical, cellular and molecular processes that contribute to the strength of such composite structures. Our study also suggests that the short-term duration of earlier analyses of cranial joint tissues may offer a limited notion of the complex process of developmental plasticity, especially as it relates to the effects of long-term variation in mechanical loads, when a joint is increasingly characterized by adaptive and degradative changes in tissue structure and composition. Indeed, it is likely that a component of the adaptive increases in rabbit TMJ and symphyseal proportions and biomineralization represent a compensatory mechanism to cartilage degradation that serves to maintain the overall functional integrity of each joint system. Therefore, while variation in cranial joint anatomy and performance among sister taxa is, in part, an epiphenomenon of interspecific differences in diet-induced masticatory stresses characterizing the individual ontogenies of the members of a species,this behavioral signal may be increasingly mitigated in over-loaded and perhaps older organisms by the interplay between adaptive and degradative tissue responses.
Oxygen in egg masses: interactive effects of temperature, age, and egg-mass morphology on oxygen supply to embryos
Authors: Moran Amy L. , Woods H. Arthur
Published: February 2007

Embryos of many marine invertebrates are encased in gelatinous masses for part or all of development. Because gel and intervening embryos retard oxygen flux, such a life-history mode profoundly affects partial pressures of metabolic gases surrounding embryos. However, little is known about relationships between egg-mass structure and the opportunities and constraints imposed on structure by metabolic gas transport. We examined the effects of four factors (temperature, embryo age, embryo density and egg-mass size) on the metabolism of egg masses using both natural egg masses of a nudibranch and artificial egg masses made from sand dollar embryos and low-melting point agarose. Both temperature and embryo age strongly affected metabolic rates of nudibranch embryos. For embryos of a given age (stage), rates of oxygen consumption roughly doubled between 12 and 21°C; from early cleavage to the veliger stage, consumption rose two- to fourfold, depending on temperature. Oxygen profiles in egg masses showed that advanced embryonic age,and to a lesser extent high temperature, both led to steeper oxygen gradients into egg masses. Egg masses containing advanced embryos at 21°C had very low central oxygen levels. Small-diameter artificial masses (2 mm diameter)had virtually no internal oxygen gradients regardless of embryo density or temperature, while medium (4 mm) and large diameter (10 mm) artificial masses had oxygen profiles that depended strongly and interactively on embryo density and temperature. Together, our data on natural and artificial egg masses suggest that (i) multiple factors have strong effects on metabolic rate; (ii)rates of oxygen transport are relatively invariant with temperature in simple,artificial systems but may vary more strongly with temperature in natural egg masses; and (iii) the four factors – temperature, embryo age, embryo density and egg-mass size – interact in important ways bearing on egg mass design.

A simple mathematical model is developed to provide a quantitative means of estimating primary and interactive effects of the different factors. We also show that in T. diomedea the gel itself is the main barrier to oxygen transport into egg masses, and that the metabolic activity of embryos increases substantially when embryos are artificially released from the capsules that contain them within the gel mass.
Automatic demisting control of automobile windscreen glass
Authors: Park Warn-Gyu , Han Myung-Chul , Jang Ki-Lyong
Published: February 2007

Mist frequently forms on automobile windscreen glass in cold humid weather. The present paper describes the development of a control device for automatically demisting windscreen glass. Automatic demisting control is initiated when the surface temperature of the glass is lower than the dew point temperature at a given relative humidity and temperature of the cabin inside. It was decided to attach the sensors measuring surface temperature and humidity on the bottom right of the glass and on the back of the rear-view mirror respectively, based on the observation of experiments. The demisting control strategy was originally designed to increase blower speed, change mode, mix hot and cold air, and turn on/off the air conditioner as the mist formed increases. The automatic device was operated with the automatic temperature controller of a heating, ventilation, and air conditioning (HVAC) system and successfully demonstrated in a vehicle test in a cold chamber by following the designed control strategy.
Simultaneous reduction of NOx and smoke from a direct-injection diesel engine with exhaust gas recirculation and diethyl ether
Authors: Anand R , Mahalakshmi N V
Published: February 2007

An experimental investigation was carried out to analyse the simultaneous reduction of oxides of nitrogen (NO x) and smoke emissions. The tests were performed on a single-cylinder direct-injection diesel engine. The engine was made to run on both pure diesel and diethyl ether (DEE)-diesel blends. The DEE-diesel blends were prepared by mixing certain proportions of DEE and diesel fuel. The amount of DEE in the diesel fuel blend was varied up to 30 vol % in steps of 10 vol % by volume. The results obtained from DEE-diesel blends were compared with those from pure diesel and it was found that the 20 vol % DEE-diesel blend resulted in the optimum performance and emission characteristics. The study was further extended by using exhaust gas recirculation (EGR) with 20 per cent DEE-diesel blend and pure diesel. At 5 vol % EGR operated with 20 vol % DEE-diesel blend, there is a simultaneous reduction of NO x and smoke emissions by 54 per cent and 20 per cent respectively. In contrast, in the case of the pure diesel mode, when the EGR rate was increased, NO x emission was reduced at the expense of smoke emissions. The alternative fuel, namely the DEE-diesel blend shows very promising results with respect to emissions, efficiency, and durability.
Development of CAD models from sketches: A case study for automotive applications
Authors: Vignesh R , Suganthan R , Prakasan K
Published: February 2007

Today products are designed not only for their functional requirements but also for aesthetics. In the automotive industries, styling has become a major part of the design process with class-A surfaces. Class-A surfaces are freeform surfaces with a continuous curvature. The process of engineering any component or system begins by generating a concept that actually describes the product in terms of its form, function, and fit. Concept sketches help the designers to arrive quickly and easily at a stage where a satisfactory design can be specified for detailed design. These concept sketches can be used for development of the digital concept design and analysis of the curves and surfaces. Software such as Alias exists and thus can be used with suitable hardware for sketching the concept of the car body on a computer screen. In this paper a systematic procedure is discussed for generating class-A surfaces from the images of concept sketches which are manually prepared on paper. These images are imported into the sketch tracer module of CATIA V5. A designer can use the image as the reference and produce a digital sketch by tracing the image using CATIA V5 software without adding any special hardware. Later, interrogation of these surfaces for improved aesthetics can be attempted. This method will be useful for the users of CATIA V5 to improve their design practices and skills.
Modelling of the selective catalytic NOx reduction in diesel exhaust including ammonia storage
Authors: Tsinoglou D , Koltsakis G
Published: February 2007

A mathematical model for the simulation of the selective catalytic reduction of NO x by ammonia in diesel exhaust is presented. The simulation of heat and mass transfer, and flow phenomena in a monolithic catalytic converter is performed by a previously published mathematical model. The chemical phenomena are described by global reactions for the oxidation of ammonia and the reduction of NO x, using Langmuir-Hinshelwood reaction rate expressions. Ammonia storage phenomena are taken into account, based on the adsorption isotherm proposed by Dubinin and Radushkevich. Both the steady state chemical reaction scheme included in the mathematical model and the ammonia adsorption and desorption model are validated against experimental data previously published in the literature. The effect of ammonia storage phenomena under an oscillating NH3/NO x ratio in the feed gas is investigated. The results indicate that for the application examined, ammonia storage plays an important role at intermediate temperatures, where conversion is controlled by reaction kinetics, provided that the ammonia adsorption capacity is sufficiently high.
Pressure-sensing pad test and computer simulation for the pressure distribution on the contact patch of a tyre
Authors: Park Sujin , Yoo Wansuk , Cho Jinrae , Kang Beomsoo
Published: February 2007

The characteristics of tyre contact with the road surface have considerable influence on various properties of the tyre. In this research, the contact pressure on the tyre was measured with a pressure-measuring device, and finite element (FE) analysis for the contact pressure was also carried out. A physical experiment device using a quarter-car uniaxial simulator and pressure pad system was set up, and the commercial FE code LS-DYNA was used for numerical calculations. FE models containing reinforcement cords and various tyre plies were generated, and the numerical results were compared with those of the physical experiment. These analyses and investigations showed reasonable results, and the reliability of the proposed FE tyre model and analysis methodology was verified.
Performance evaluation of a magnetorheological fluid variable valve
Authors: Hirani H , Manjunatha C S
Published: February 2007

The present paper describes the conceptual design, simulation, and fabrication of a magnetorheological (MR) fluid variable-valve actuation (WA) system. Two set-ups, one for testing the conceptual design and the other for application of the MR valve on a real engine, have been developed. The test set-up measures the displacement of the valve, which operates by the cam-follower mechanism. The results of valve lifts at different speeds and control currents are presented. To implement the MR fluid VVA system, a four-stroke single-cylinder Kirloskar TV1 vertical diesel engine has been selected. Inlet and exhaust manifolds have been modelled to estimate volumetric efficiency. The equations governing the unsteady air flow in the ducts have been solved using the method of characteristics. A numerical code to simulate the entire gas exchange process has been developed, and the results have been compared with the experimental results. Further, this code has been used to identify the optimal valve lift requirements of the engine at various crankshaft speeds. The quantified requirements obtained have been used for the design of an MR fluid VVA system. A prototype MR VVA system has been developed. Experimental results are reported in the form of maximum valve lift variation with speed and d.c. current.
Testing of an automobile exhaust thermoelectric generator in a light truck
Authors: Thacher E F , Helenbrook B T , Karri M A , Richter C J
Published: February 2007

Testing was conducted on a prototype automobile exhaust thermoelectric generator (AETEG) installed in a 1999 GMC Sierra pick-up truck. The system consisted of the generator, its power conditioning unit, and the interfaces to the test truck's engine coolant and exhaust systems. The objective of the test was to measure the AETEG's performance and its effect on the truck systems as well as to determine which factors are important for optimizing an AETEG design. Testing was performed in a dynamometer-equipped wind tunnel at Delphi Corporation's Harrison Thermal Systems Division in Lockport, New York. The first tests established the benchmark data set. Then the prototype AETEG was installed and three configurations of the system were tested in succession: the AETEG alone, the AETEG with portions of the exhaust pipes leading to it insulated, and the AETEG with insulated upstream exhaust pipes and with a pre-cooling heat exchanger operating to lower the inlet coolant temperature to the generator. Some of the important outcomes of the tests were: insulating the exhaust and lowering the coolant temperature had a significant positive effect on the power, parasitic losses resulting from the AETEG weight and the coolant pumping power were significant but manageable, and the increased exhaust flow resistance and the additional heat load from the AETEG were not significant effects.
Brake dynamometer model predicting brake torque variation due to disc thickness variation
Authors: Kang Jaeyoung , Choi Sungjin
Published: February 2007

In this study, the mathematical model for a brake system in a dynamometer is proposed to identify brake torque variation (BTV), and correlations between the dynamo test and simulation are determined. The interaction between the pads and the disc on the contact patch is simply modelled as a point-contact element and the transient response analysis in the time domain is introduced. The model indicates that the amount of BTV is linearly proportional to the pad stiffness, the friction coefficient, the disc thickness variation, and the effective radius of the brake pads. To verify the analytical model, a brake dynamometer is used and additional material tests are carried out. The dynamo test shows that the suggested model has reasonable accuracy in predicting the BTV of a brake system.
Comparison of black-, white-, and grey-box models to predict ultimate tensile strength of high-strength hot rolled coils at the Port Talbot hot strip mill
Authors: Jones D M , Watton J , Brown K J
Published: February 2007

In the manufacture of rolled steel from a hot strip mill (HSM), the final mechanical properties, such as ultimate tensile strength, are important requirements specified by the customer. Traditional, physically based models are now being challenged by the development of black-box techniques such as artificial neural networks. In this present paper, an existing white-box physical equation for predicting ultimate tensile strength in high-strength steels is compared to an optimized black-box neural network model using the same model inputs. The predictive accuracy of both models is compared through the use of previously unseen data from a validation coil where the ultimate tensile strength throughout its length is known. In addition, a combination of the white-box equation and a black-box neural network connected in parallel, whose role is to predict the white-box approximation error, provides a grey-box solution for ultimate tensile strength prediction for high-strength coils at the Port Talbot HSM. It was found that this grey-box solution outperformed the stand-alone white-and black-box models in terms of predictive accuracy.
Study of the selective laser sintering of polycarbonate and postprocess for parts reinforcement
Authors: Shi Y , Chen J , Wang Y , Li Z , Huang S
Published: February 2007

Polycarbonate (PC) powder, a common and low-cost amorphous polymer, can be moulded easily by the process of selective laser sintering (SLS). However, the sintered parts cannot be used as functional parts because of their poor mechanical properties. In this article, epoxy resin was applied to improve the mechanical properties of PC SLS parts. Specimens for testing dimensional accuracy, tensibility, flexibility, and impact strength were made by SLS with 75-100 μ PC powder. Some of the specimens were posttreated with two types of epoxy resins. Dimensional accuracy and mechanical properties of the specimens were measured. Microstructures of tensile fracture were observed by scanning electron microscopy. The result shows that the mechanical properties of the specimens are reinforced greatly after the epoxy resin has been infiltrated. Extent of the reinforcement depends on curing agents of epoxy resins. For example, with curing agent W, it is increased to 13.82, 8.00, and 3.69 times, respectively, in tensile, flexural, and impact strength and with curing agent Y, it is increased to 19.87, 7.43, and 1.55 times, respectively, in the same properties. The reinforcement in mechanical properties of PC SLS parts can be improved a step further by means of optimizing the epoxy resin system. Therefore, the PC SLS parts reinforced by epoxy resin can be used as functional parts, if the requirement on mechanical properties is not very high.
A Dual-Self Model of Impulse Control
Authors: Fudenberg Drew , Levine David K
Published: February 2007

We propose that a simple “dual-self” model gives a unified explanation for several empirical regularities, including the apparent time inconsistency that has motivated models of quasi-hyperbolic discounting and Rabin's paradox of risk aversion in the large and small. The model also implies that self-control costs imply excess delay, as in the O'Donoghue and Rabin models of quasi-hyperbolic utility, and it explains experimental evidence that increased cognitive load makes temptations harder to resist. The base version of our model is consistent with the Gul-Pesendorfer axioms, but we argue that these axioms must be relaxed to account for the effect of cognitive load.
Inherited Control and Firm Performance
Authors: Pérez-González Francisco
Published: February 2007

I use data from chief executive officer (CEO) successions to examine the impact of inherited control on firms' performance. I find that firms where incoming CEOs are related to the departing CEO, to a founder, or to a large shareholder by either blood or marriage underperform in terms of operating profitability and market-to-book ratios, relative to firms that promote unrelated CEOs. Consistent with wasteful nepotism, lower performance is prominent in firms that appoint family CEOs who did not attend “selective” undergraduate institutions. Overall, the evidence indicates that nepotism hurts performance by limiting the scope of labor market competition.
The Hidden Costs of Control
Authors: Falk Armin , Kosfeld Michael
Published: February 2007

We analyze the consequences of control on motivation in an experimental principal-agent game, where the principal can control the agent by implementing a minimum performance requirement before the agent chooses a productive activity. Our results show that control entails hidden costs since most agents reduce their performance as a response to the principal's controlling decision. Overall, the effect of control on the principal's payoff is nonmonotonic. When asked for their emotional perception of control, most agents who react negatively say that they perceive the controlling decision as a signal of distrust and a limitation of their choice autonomy.
Globalization and Emerging Markets: With or Without Crash?
Authors: Martin Philippe , Rey Hélène
Published: February 2007

We analyze the effects of financial and trade globalization on the likelihood of financial crashes in emerging markets. While trade globalization always makes crashes less likely, financial globalization may make them more likely, especially when trade costs are high. Pessimistic expectations can be self-fulfilling and lead to a collapse in demand for goods and assets. Such a crash comes with a current account reversal and drops in income and investment. Lower-income countries are more prone to such demand-based financial crises. A quantitative evaluation shows our model is consistent with the main stylized facts of financial crashes in emerging markets.
Cognition and Behavior in Two-Person Guessing Games: An Experimental Study
Authors: Costa-Gomes Miguel A , Crawford Vincent P
Published: February 2007

This paper reports an experiment that elicits subjects' initial responses to 16 dominance-solvable two-person guessing games. The structure is publicly announced except for varying payoff parameters, to which subjects are given free access. Varying the parameters allows very strong separation of the behavior implied by leading decision rules. Subjects' decisions and searches show that most subjects understood the games and sought to maximize payoffs, but many had simplified models of others' decisions that led to systematic deviations from equilibrium. The predictable component of their deviations is well explained by a structural nonequilibrium model of initial responses based on level-k thinking.
The Japanese Saving Rate
Authors: Chen Kaiji , İmrohoroğlu Ayşe , İmrohoroğlu Selahattin
Published: February 2007

Despite much work, economists have not been able to quantitatively account for the differences in the Japanese and U.S. saving rates after World War II. In this paper, we show that the use of actual Japanese total factor productivity growth rates in a standard growth model generates saving rates that are reasonably similar to the Japanese data between 1956 and 2000.
How Big a Problem is Too Big to Fail? A Review of Gary Stern and Ron Feldman's Too Big to Fail: The Hazards of Bank Bailouts
Authors: Mishkin Frederic S
Published: February 2007

This review essay examines whether too-big-to-fail is as serious a problem as Gary Stern and Ron Feldman contend. This essay argues that Stern and Feldman overstate the importance of the too-big-to-fail problem and do not give enough credit to the FDICIA legislation of 1991 for improving bank regulation and supervision. However, this criticism of the Stern and Feldman book does not detract from many of its messages. The policy recommendations in their book have merit even if the too-big-to-fail problem is currently not that serious because these policies make it less likely that a banking crisis will occur even if driven by other factors.
Avoiding Invalid Instruments and Coping with Weak Instruments
Authors: Murray Michael P
Published: February 2007

Archimedes said, “Give me the place to stand, and a lever long enough, and I will move the Earth.” Economists have their own powerful lever: the instrumental variable estimator. The instrumental variable estimator can avoid the bias that ordinary least squares suffers when an explanatory variable in a regression is correlated with the regression's disturbance term. But, like Archimedes' lever, instrumental variable estimation requires both a valid instrument on which to stand and an instrument that isn't too short (or “too weak”). This paper briefly reviews instrumental variable estimation, discusses classic strategies for avoiding invalid instruments (instruments themselves correlated with the regression's disturbances), and describes recently developed strategies for coping with weak instruments (instruments only weakly correlated with the offending explanator).
What Has Mattered to Economics Since 1970
Authors: Kim E. Han , Morse Adair , Zingales Luigi
Published: February 2007

Citations are one way that past research echoes through time. In this paper, we compile a list of articles published in major refereed economics journals in the last 35 years that have received more than 500 citations as of June 2006. We then use this list to examine various trends: what fields of economics are most in vogue; what types of articles generate the most interest; and which institutions host the production of these articles and train their authors.
Markets: The U.S. Lodging Industry
Authors: Kalnins Arturs
Published: February 2007

The U.S. lodging industry appears highly competitive. Ownership concentration appears to be low. Fixed costs are high relative to variable costs and unused rooms cannot be stored for future sale, so price-cutting should be attractive. However, this paper argues that, unexpectedly, oligopolistic market structures in many local lodging markets, combined with behavioral norms of cooperation, sustain profits in what might otherwise be an industry of cutthroat competition. I describe the patterns of competition and cooperation in the U.S. lodging industry, summarizing theoretical arguments, empirical research, descriptive statistics from industry and government sources, and anecdotal evidence from the trade press and from interviews conducted with managers of over 200 properties nationwide.
Policy Watch: Examining the Justification for Residential Recycling
Authors: Kinnaman Thomas C
Published: February 2007

There are 8,875 municipalities in the United States that have initiated curbside recycling programs over the past two decades to help reduce residential solid waste. Four thousand of these municipalities encourage recycling by requiring households to pay a fee for each unit of garbage presented at the curb for collection. How beneficial have the various recycling policies been in practice? This article examines the empirical lessons gained from twenty years of solid waste policy in the United States and argues for the replacement of several state recycling mandates with a moderate landfill tax.
Modern Macroeconomics in Practice: How Theory Is Shaping Policy
Authors: Chari V. V , Kehoe Patrick J
Published: February 2007

Over the last three decades, macroeconomic theory and the practice of macroeconomics by economists have changed significantly—for the better. Macroeconomics is now firmly grounded in the principles of economic theory. We focus on the role of economic theory in shaping policy. Over the last several decades, the United States and other countries have undertaken a variety of policy changes that are precisely what macroeconomic theory of the last 30 years suggests. The evidence that theoretical advances have had a significant effect on the practice of policy is often hard to see for policymakers and advisers involved in the hurly-burly of day-to-day policymaking, but easy to see if one steps back and takes a longer-term perspective. Examples of the effects of theory on the practice of policy include increased central bank independence; adoption of inflation targeting and other rules to guide monetary policy; increased reliance on consumption and labor taxes instead of capital income taxes; and increased awareness of the costs of policies that distort labor markets.
Enantioenriched cyanohydrin O-phosphates: Synthesis and applications as chiral building blocks
Authors: Baeza Alejandro , Sansano José M. , Saá José M. , Nájera Carmen
Published: February 2007

Aluminum complexes of the chiral (R)- or (S)-3,3'-bis(diethylaminomethyl)-1,1'-bi-2,2'-naphthol (BINOLAM) ligand behave as efficient catalysts for the enantioselective cyanation-O-functionalization of aldehydes, thereby leading to enantiomerically enriched O-silyl, O-methoxycarbonyl, or O-phosphate derivatives of cyanohydrins. The enantioenriched cyanohydrin-O-phosphates are useful for the synthesis of several enantioenriched compounds such as α-hydroxy esters, β-amino alcohols, and γ-substituted α,β-unsaturated nitriles. Natural products such as (-)-aegeline and (-)-tembamide have been prepared in this manner.
Asymmetric catalysis in aqueous media
Authors: Kobayashi Shū
Published: February 2007

Lewis acid catalysis has attracted much attention in organic synthesis because of unique reactivity and selectivity attained under mild conditions. Although various kinds of Lewis acids have been developed and applied in industry, these Lewis acids must be generally used under strictly anhydrous conditions. The presence of even a small amount of water handles the reactions owing to preferential reactions of the Lewis acids with water rather than the substrates. In contrast, rare earth and other metal complexes have been found to be water-compatible. Several catalytic asymmetric reactions in aqueous media, including hydroxymethylation of silicon enolates with an aqueous solution of formaldehyde in the presence of Sc(OTf)3-chiral bipyridine ligand or Bi(OTf)3-chiral bipyridine ligand, Sc- or Bi-catalyzed asymmetricmeso-epoxide ring-opening reactions with amines, and asymmetric Mannich-type reactions of silicon enolates withN-acylhydrazones in the presence of a chiral Zn catalyst have been developed. Water plays key roles in these asymmetric reactions.