bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk Management Failures: What Are They and When Do They Happen?
Authors: Stulz René M.
Published: December 2008

The difficulties of the past year have convinced many observers that current risk management practices are deeply flawed, and that such flaws have contributed greatly to the current financial crisis. In this paper, the author challenges this view by showing the need to distinguish between flawed assessments by risk managers and corporate risk‐taking decisions that, although resulting in losses, were reasonable at the time they were made.

In making this distinction, the paper also identifies a number of different ways that risk management can fail. In addition to choosing the wrong risk metrics and misidentifying or mismeasuring risks, risk managers can fail to communicate their risk assessments and provide effective guidance to top management and boards. And once top management has used that information to help determine the firm's risk appetite and strategy, the risk management function can also fail to monitor risks appropriately and maintain the firm's targeted risk positions.

But if risk management has been mistakenly identified as the culprit in many cases, current risk management practice can be improved by taking into account the lessons from financial crises past and present. In particular, such crises have occurred with enough frequency that crisis conditions can be modeled, at least to some extent. And when models reach their limits of usefulness, companies should consider using scenario planning that aims to reveal the implications of crises for their financial health and survival. Instead of relying on past data, scenario planning must use forward‐looking economic analysis to evaluate the expected impact of sudden illiquidity and the associated feedback effects that are common in financial crises.
La question d'une tradition sociologique en Acadie : un aperçu1
Authors: MASSICOTTE JULIEN
Published: December 2008

La présente étude examine la question d'une tradition sociologique en Acadie. L'auteur passe en revue trois grandes périodes de la présence sociologique en Acadie. Une première période, allant de la toute fin des années 1930 aux années 1960, marque l'échafaudage institutionnel d'une première sociologie en Acadie. Une seconde période, allant des années 1960 aux années 1980, constitue pour la sociologie en Acadie une période de crise, de contestation et de redéfinition. Finalement, la troisième grande période, du début des années 1980 à aujourd'hui, marque l'éclatement de la discipline. On termine le texte en se demandant, à la lumière de ces trois périodes marquantes, s'il existe vraiment, en Acadie, une tradition sociologique distincte.

The present study examines the question of a sociological tradition in Acadie. The author focuses on three large periods of sociological presence in Acadie. In the first phase, between the end of the thirties to the first years of the sixties, sociology became institutionally rooted in Acadie. A second period took place between the early sixties and the early eighties, when sociology experienced a period of crisis, contestation and redefinition. Finally, the third and final period, from the early eighties to the present, marks the fragmentation of the discipline. The present study ends by asking the following question: does a sociological tradition truly exist in Acadie?
Natural Convective Flow in a Three Enclosure System Involving Two High Aspect Ratio Side Enclosures Joined to a Large Square Enclosure With Interfacial Heat Generation
Authors: Oosthuizen Patrick H.
Published: December 2008

A numerical study of free convective flow in a vertical joined three enclosure arrangement has been undertaken. In this arrangement, a vertical heated wall kept at a uniform high temperature is contained in a high aspect ratio rectangular side enclosure. This enclosure is joined to a second high aspect ratio rectangular side enclosure which has the same height as the first side enclosure, the two enclosures being separated by a vertical impermeable dividing wall which offers no resistance to heat transfer. The second side enclosure is joined to a larger square enclosure, the vertical dividing wall between these two enclosures also being impermeable and offering no resistance to heat transfer. The vertical wall of the square main flow enclosure opposite to the dividing wall is maintained at a uniform lower temperature. There is a uniform rate of heat generation in the dividing wall between the inner side enclosure and the main enclosure. The situation considered is an approximate model of a double-paned window exposed to a hot outside environment and covered by a plane blind which in turn is exposed to cooled room. In some such cases there can be significant heat generation in the blind due to the absorbtion of solar energy, this being modeled by the heat generation in the one dividing wall. The flow has been assumed to be laminar and two-dimensional and results have been obtained for a Prandtl number of 0.7. The effects of Rayleigh number, dimensionless width of the side enclosures and dimensionless heat generation rate in the blind on the Nusselt number have been investigated. The results show that for a fixed Rayleigh number and for a given dimensionless first (i.e., outer) side enclosure width, there is a minimum in the Nusselt number variation with the dimensionless width of the second side enclosure. An approximate solution for the Nusselt number variation with the dimensionless width of the second side enclosure for small values of this dimensionless width has also been derived.
An Experimental Study of Pin Fin Heat Sinks and Determination of End Wall Heat Transfer
Authors: Rizzi Massimiliano , Catton Ivan
Published: December 2008

An experimental study of a pin fin heat sink was carried out in support of the development of heat sink optimization methods requiring more detailed measurements be made. Measurements of heat flux and temperature are used to separately determine heat transfer coefficients for the pins and the base region between the pins. Three pitch to diameter ratios (distance from pin center to pin center measured diagonally) were studied: P/d = 3/1, 9/4, 3/2. Heat generation was accomplished using cartridge heaters inserted into a copper block. The high thermal conductivity of the copper ensured that the surface beneath the heat sink would be at a constant temperature. The cooling fluid was air and the experiments were conducted with a Reynolds numbers based on a porous media type hydraulic diameter ranging from 500 to 25000. The channel had a shroud that touches the fin tips, eliminating any flow bypass. The pin surface heat transfer coefficients match the values reported by Kays and London and by Zukauskas. The base region heat transfer coefficients were, surprisngly, larger than the pin values.
Radiation Effects on Natural Convection in Air in a Divergent Channel With Uniformly Heated Plates
Authors: Bianco Nicola , Manca Oronzio , Nardini Sergio , Naso Vincenzo
Published: December 2008

Nowadays trends in natural convection heat transfer are oriented toward either the seeking of new configurations to enhance the heat transfer parameters or the optimization of standard configurations. An experimental investigation on air natural convection in divergent channels with uniform heat flux at both the principal walls is presented in this paper to analyze the effect of radiative heat transfer. Results in terms of wall temperature profiles as a function of the walls diverging angle, the interwall spacing, the heat flux are given for two value of the wall emissivity. Flow visualization is carried out in order to show the peculiar pattern of the flow between the plates in several configurations. Nusselt numbers are then evaluated and correlated to the Rayleigh number. The investigated Rayleigh number ranges from 7.0 × 102 to 4.5 × 108. The maximum wall temperature decreases at increasing divergence angles. This effect is more evident when the minimum channel spacing decrease. A significant decrease in the maximum wall temperature occurs passing from ε = 0.10 to ε = 0.90, except in the inlet region. Flow visualization shows a separation of the fluid flow for bmin = 40 mm and θ = 10°. Correlations between Nusselt and Rayleigh numbers show that data are better correlated when the maximum channel spacing is chosen as the characteristic length.
Experimental Investigation of Single-Phase Micro Jets Impingement Cooling for Electronic Applications
Authors: Fabbri Matteo , Jiang Shanjuan , Dhir Vijay K.
Published: December 2008

Impinging jets for cooling of electronic equipment have been used by many researchers. Only few studies using arrays composed of a small number of jets are available in the literature. When very small jet diameters are used, the jet Reynolds number becomes quite small and no data are available for Reynolds number values below 500. In this work attention has been focused on circular arrays of free surface micro jets. Experiments were conducted by employing three jet pitches, 1, 2 and 3 mm and four jet diameters 50, 100, 150 and 250 μm and two different fluids, DI water and FC 40. The jet Reynolds number range was varied between 90 and 2000 while the Prandtl number varied from 6 to 84. Heat fluxes as high as 250 W/cm2 could be removed when water was utilized. Experimental data have been correlated within ±20%.
Numerical Study of Lateral Merger of Vapor Bubbles During Nucleate Pool Boiling
Authors: Mukherjee Abhijit , Dhir Vijay K.
Published: December 2008

Nucleate boiling is one of the most efficient modes of heat transfer. At the start of nucleate boiling, isolated bubbles appear on the heating surface, the regime known as partial nucleate boiling. Transition from isolated bubbles to fully developed nucleate boiling occurs with increase in wall superheat, when bubbles begin to merge in vertical and lateral directions. The laterally merged bubbles form vapor mushrooms, which stay attached to the heater surface via numerous vapor stems. The present study is performed to numerically analyze the bubble dynamics and heat transfer associated with lateral bubble merger during transition from partial to fully developed nucleate boiling. The complete Navier-Stokes equations in three dimensions along with the continuity and energy equations are solved using the SIMPLE method. The liquid vapor interface is captured using the Level-Set technique. Calculations are carried out for multiple bubble-merger in a line and also in a plane and the bubble dynamics and wall heat transfer are compared to that for a single bubble. The results show that the merger process significantly increases the overall wall heat transfer. It is also found that the orientation of the bubbles strongly influences different heat transfer mechanisms.
On the Group Front and Group Velocity in a Dispersive Medium Upon Refraction From a Nondispersive Medium
Authors: Zhang Z. M. , Park Keunhan
Published: December 2008

Conventional definitions of the velocities associated with the propagation of the modulated wave are both confusing and insufficient to describe the behavior of the wave packet clearly in a multi-dimensional dispersive medium. There exist infinite solutions to the general equation of wave-front movement, suggesting that there are infinite phase velocities. Therefore, the introduction of “normal phase velocity” becomes necessary to unambiguously define the phase velocity in the direction perpendicular to the wave front. Similarly, there exist infinite solutions to the equation describing the group-front movement in the case of a wave packet, resulting in infinite “group-front velocities.” The “normal group-front velocity” is defined as the smallest speed at which the group-front travels and is in the direction perpendicular to the group front. We show that the group velocity (i.e., the velocity of energy flow) is one of the group-front velocities and, in general, is not the same as the normal group-front velocity. Hence, the direction in which the wave packet travels is not necessarily normal to the group front. Examples are used to demonstrate the behavior of a wave packet that is refracted from vacuum to a positive index medium (PIM) or a negative index medium (NIM).
An Investigation of Copper Dissolution and the Formation of Intermetallic Compounds in Molten Tin and Tin-Silver Solders
Authors: Faizan M. , McCoy R. A. , Lin D. C. , Srivatsan T. S. , Wang G.-X.
Published: December 2008

This paper presents an experimental study of copper dissolution in molten tin and tin-silver (Sn-Ag) solders and the formation and presence of the Cu-Sn intermetallic compound at solder/copper interfaces. During the experiments, copper (99.9% pure) samples, coated with a RMA flux, were dipped vertically in a molten solder for different time periods ranging from 5 seconds to 10 minutes. The molten solder was maintained at temperatures of 232°C, 250°C and 300°C for pure tin and 221°C, 250°C, and 300°C for Sn-3.5%Ag respectively. The samples were then cut, cleaned and cold mounted in epoxy at ambient temperature. Mechanical grinding, finish polishing, etching, and optical metallographic procedures were utilized for examining the microstructures of the polished and etched samples. The average thickness of the intermetallic compound and the amount of copper dissolved was determined. Experimental results indicate the temperature of molten solder to control the rate of dissolution of copper and the formation and presence of intermetallic compounds at the interfaces. At a given temperature of the solder temperature, the rate of dissolution of copper in the solder revealed a rising trend with an increase in dwell time of copper in the solder. For short contact time periods, the dissolution rate is low and the thickness of the intermetallic compound is small. With an increase in dwell time, the dissolution rate of copper rapidly increases and eventually reaches a plateau. Initiation of dissolution of copper causes a layer of the Sn-Cu intermetallic compound to form around the copper substrate. This in turn prevents direct contact of the copper substrate with the molten solder. The rate of formation of the layer of intermetallic compound reveals a similar trend. Based on experimental results, the kinetic parameters involved in governing the growth of the intermetallic were determined for the two solders. The parameters can be used to estimate the kinetics of copper dissolution and intermetallic compound formation during soldering.
Numerical Study of the Effect of Magnetic Fields on Melt-Crystal Interface-Deflection in Czochralski Crystal Growth
Authors: Liu Lijun , Kakimoto Koichi
Published: December 2008

In order to control the impurity distribution and remove defects in a crystal grown in Czochralski growth for high quality crystals of silicon, it is necessary to study and control the melt-crystal interface shape, which plays an important role in control of the crystal quality. The melt-crystal interface interacts with and is determined by the convective thermal flow of the melt in the crucible. Application of magnetic field in the Czochralski system is an effective tool to control the convective thermal flow in the crucible. Therefore, the shape of the melt-crystal interface can be modified accordingly. Numerical study is performed in this paper to understand the effect of magnetic field on the interface deflection in Czochralski system. Comparisons have been carried out by computations for four arrangements of the magnetic field: without magnetic field, a vertical magnetic field and two types of cusp-shaped magnetic field. The velocity, pressure, thermal and electromagnetic fields are solved with adaptation of the mesh to the iteratively modified interface shape. The multi-block technique is applied to discretize the melt field in the crucible and the solid field of silicon crystal. The unknown shape of the melt-crystal interface is achieved by an iterative procedure. The computation results show that the magnetic fields have obvious effects on both the pattern and strength of the convective flow and the interface shape. Applying magnetic field in the Czochralski system, therefore, is an effective tool to control the quality of bulk crystal in Czochralski growth process.
Heat and Mass Transfer in Parallel Flow Mist Cooling
Authors: Baxi C. B. , Gutierrez O. , Schleicher R. , Kendall C. M.
Published: December 2008

The lasing gain media (LGM) of the solid-state heat capacity laser (SSHCL) need to be cooled in a short time in between laser operations to increase the duty cycle. Parallel flow mist cooling is an attractive option to accomplish this. However, no general correlations exist to predict parallel flow mist cooling heat transfer for various fluids. In order to obtain such a correlation this study was undertaken. Drop size distribution from different nozzles was characterized by laser Doppler anemometer. A parallel flow mist cooling experimental set-up was designed and fabricated. Data from over 300 experiments with air, air-water mist, air-denatured ethanol mist and air-pure ethanol mist was obtained. The parameter ranges were: flow velocity between 5 and 50 m/s, drop diameters between 18 and 75 μm, mist concentrations as high as 0.2 kg/m3, heat fluxes up to 170000 W/m2 and hydraulic diameters between 0.003 and 0.008 m. An enhancement of up to a factor of six relative to the heat flux removed by air was obtained. The experiments indicated that there are four regimes in parallel flow mist cooling. These are: 1) Mass transfer, 2) Forced convection 3), Critical Heat Flux and 4) Film boiling. Two general correlations for parallel flow mist cooling are proposed for the first two of these regimes.
Reconstructing Cylinder Pressure of a Spark-Ignition Engine for Heat Transfer and Heat Release Analyses
Authors: Zeng Pin , Prucka Robert G. , Filipi Zoran S. , Assanis Dennis N.
Published: December 2008

This paper proposes a technique for reconstructing the cylinder pressure traces of a spark-ignition engine based on three inputs: spark-timing, speed and load. This method is an extension of previous work for reconstructing cylinder pressure in a heavy-duty diesel engine [1]. The previous study utilized only two inputs for cylinder pressure reconstruction, e.g. engine speed and load, hence implying optimal combustion phasing. The new method adds one more input to allow reconstruction of pressure traces from cycles with combustion phasing altered based on emissions or knock constraints. The method was applied to a 4-cylinder, 2.4-liter DaimlerChrysler gasoline engine. Comparisons between measured and reconstructed cylinder pressure traces demonstrate that the method is applicable over the majority of the gasoline engine operating range. Reconstructed cylinder pressure traces have also been used to carry out engine heat transfer and heat release analyses. Problems associated with the application of this method to gasoline engine are also discussed.
A New Predictive ID Model for Advanced High Speed Direct Injection Diesel Engines
Authors: Zhong Lurun , Henein Naeim A. , Bryzik Walter
Published: December 2008

Advance high speed direct injection diesel engines apply high injection pressures, exhaust gas recirculation (EGR), injection timing and swirl ratios to control the combustion process in order to meet the strict emission standards. All these parameters affect, in different ways, the ignition delay (ID) which has an impact on premixed, mixing controlled and diffusion controlled combustion fractions and the resulting engine-out emissions. In this study, the authors derive a new correlation to predict the ID under the different operating conditions in advanced diesel engines. The model results are validated by experimental data in a single-cylinder, direct injection diesel engine equipped with a common rail injection system at different speeds, loads, EGR ratios and swirl ratios. Also, the model is used to predict the performance of two other diesel engines under cold starting conditions.
Analysis of an Extended Ionization Equilibrium in the Post-Flame Gases for Spark Ignited Combustion
Authors: Ahmedi A. , Mauss F. , Sunde´n B.
Published: December 2008

Constant volume combustion is studied, using a zero-dimensional model, which is a wide-ranging chemical kinetic simulation that allows a closed system of gases to be described on the basis of a set of initial conditions. The model provides an engine- or reactor-like environment in which the engine simulations allow for a variable system volume and heat transfer both to and from the system. The combustion chamber is divided into two zones as burned and unburned ones, which are separated by a thin adiabatic flame front in the combustion model used in this work. A detailed chemical mechanism is applied in each zone to calculate the temperature and pressure history. Equilibrium assumptions have been adopted for the modeling of the thermal ionization, in which Saha’s equation was derived for singly ionized molecules. The investigation is focused on the thermal ionization and electron attachment of 13 chemical species by solving a set of 6 chemical reactions dynamically, the equilibrium calculation using Saha’s equation is performed in a post process, using the temperature and pressure history from the previous model. The experiments that were used for the validation of this model were performed in constant-volume bomb. The outputs generated by the model are temperature profiles, species concentration profiles, ionization degree and an electron density for each zone. The model also predicts the pressure cycle and the ion current. The results from the simulation show good agreement with the experimental measurements and literature data.
S.I. Engine Operation on H2, CO, CH4 and Their Mixtures
Authors: Li Hailin , Karim Ghazi A. , Sohrabi A.
Published: December 2008

Experimental data are presented of the knock and combustion characteristics of a wide range of fuel mixtures of CO, H2 and CH4 while using a variable compression ratio engine. A predictive model was employed for predicting such characteristics where the oxidation reactions of mixtures of H2, CO, and CH4 were simulated using detailed chemical kinetics. Predicted results were validated against those determined experimentally and showed good agreement for a wide range of fuel compositions and operating conditions. However, it was noted that the predicted knock limited equivalence ratios for dry CO-air operation, in comparison to the other fuel applications, tended to display deviation from the experimentally established values. The reasons for this tendency are discussed and measures to permit the prediction of such a behavior are presented.
Steam Jet Air Ejector Performance Evaluation for Nuclear Plants
Authors: Sunder Raj Komandur S.
Published: December 2008

Improper design, operation and maintenance of the steam jet air ejector (SJAE) system result in elevated condenser pressures with attendant loss in plant capacity. Conversely, problems associated with the condenser and circulating water system may be incorrectly attributed to the SJAE system. This paper provides an overview of SJAE systems for nuclear plants. It discusses sizing of venting equipment, examines the interface of the SJAE system with the condenser, explores performance issues encountered with the SJAE system and shows how to evaluate its performance. The Heat Exchange Institute Standards for Surface Condensers and Steam Jet Vacuum Systems are also discussed. The paper provides conclusions and recommendations for troubleshooting and monitoring the performance of the SJAE system and for ensuring optimum performance.
Ship’s Engine Room Fire Modelling
Authors: Petelin Stojan , Perkovic Marko , Vidmar Peter , Petelin Katja
Published: December 2008

When traffic accidents occur, transport systems can result in irreparable negative impacts on people as well as the environment. In maritime transport unexpected fire in the ship’s engine room represents a grave risk. Because such accidents are very often difficult to prevent, modelling of fire propagation bears a vital significance for setting up preventive measures and safety systems, whose task is the suppression of fire danger. The paper describes the CFAST computer model (Building and Fire Research Laboratory - National Institute of Standards and Technology), whose purpose is to solve the problem of fire propagation in a complex multi-compartment environment. In our example it was used in a concrete ship’s engine room, with a fire starting in the ship’s main propulsion engine. The application includes all elements that can be damaged in case of fire at different ventilation conditions of the ship’s engine room. By means of simulation, the analysis and presentation of physical parameters working upon exposed engine components was made.
Four Years of Operation of the Amonix High Concentration Photovoltaic System at Arizona Public Service Utility
Authors: Stone Kenneth W. , Garboushian Vahan , Dutra David , Hayden Herb
Published: December 2008

This paper describes the operation of 570 kW of installed Amonix High Concentration PV systems at various Arizona Public Service (APS) site locations over the last four years. The physical characteristics of the different units in the field are described, including the operating characteristics that make this system applicable for large grid connected, distributed, and off-grid/remote operation. Data is presented showing that the monthly generated energy and annual generated energy over this period of time increased as the technology matured. Discussion and data are also presented on the effects of field shadowing and lens soiling. The latest status of the largest concentrating PV plant in the world is also discussed.
Optimizing Boiler Generating Bank Tube Reliability Through the Use of IRIS Non Destructive Testing
Authors: Marra Dominic
Published: December 2008

The boilers’ generating bank (convective) section began suffering repeated random failures at the Miami-Dade County Resources Recovery Facility. The plant embarked on an optimization program to better identify and target the failures using non destructive ultrasonic Internal Rotary Inspection Services (IRIS) testing. Through the use of the IRIS nondestructive testing method, the plant was able to identify 3 major contributors to tube failures by mapping out the locations of the tube wastage across all 4 boilers at the facility. The testing allowed optimizing the use of resources allocated to this area of the boiler and resulted in a considerable drop of unscheduled downtime and increase in generating bank tube reliability. The IRIS testing method involves an ultrasonic probe that is lowered down the inside of the tubes. The tubes are flooded with water in order to get a full 360-degree thickness survey of the tubes from top to bottom, (steam drum to mud drum). The data for over 4.7 miles (7.5 Km) of linear tube per boiler is recorded digitally and presented on a CD. By pinpointing the location and severity of tube wastage across the entire generating bank section, the root cause of the failures could be identified. An integrated solution was developed involving a combination of tube replacements, shielding, tube plugging, and soot blower optimization. This paper summarizes the results of the testing and optimization program.
The “First Physics First” Movement, 1880–1920
Authors: Sheppard Keith , Robbins Dennis M.
Published: December 2008

The issue of the grade placement of the sciences in high school is a much-discussed topic and “Physics First” strands have become regular features at physics teacher conferences. The American Association of Physics Teachers has issued a position statement and published an informational guide concerning the movement.2 There is a “Physics First” website, a list-serv that provides a forum for discussion, and at least six doctoral dissertations have been completed on the topic, with more in preparation.3 The topic is not confined to the physics education community; the American Chemical Society opened a forum on “Physics First” and recently called for a conference session about the grade placement of chemistry.4 Biologists also recently held a symposium on “Capstone Biology” and published their proceedings.5
Reliability measures for pile foundations based on cone penetration test data
Authors: Haldar Sumanta , Babu G. L. Sivakumar
Published: December 2008

The in situ behaviour of pile foundations is considerably influenced by variability in soil properties. Cone penetration (CPT) data are often used to determine the pile ultimate capacity. A wider range of values of the ultimate capacity are predicted when different CPT-based methods are used, as compared to using pile load test results. The present study considers inherent soil variability, measurement, and transformation variability. The undrained shear strength obtained from CPT data is considered to be a random variable. An approach to obtain load–settlement curves and the associated statistics from CPT data is suggested. Component reliability indices, based on ultimate limit state (ULS) and serviceability limit state (SLS) criteria, and system reliability indices combining ULS and SLS are evaluated. The variability in the pile–soil interface parameters and pile ultimate capacity is quantified in a Monte Carlo framework using the measured data. The effects of variability, scale of fluctuation, and limiting serviceability settlement on the reliability of pile foundations are also examined. A geotechnical database from the Konaseema site in India is utilized as an example. It is shown that the reliability based design of pile foundations considering spatial variability of soil, along with the variables associated with pile–soil interface properties, enables a rational choice of design loads.
Modelling the combined effect of strain rate and temperature on one-dimensional compression of soils
Authors: Laloui L. , Leroueil S. , Chalindar S.
Published: December 2008

Strain rate and temperature have important effects on the behaviour of soils. The present paper enhances the thermoviscoplastic modelling of soils by taking advantage of the most recent understanding of the effects of temperature and strain rate on soils. In particular, modelling of the evolution of the vertical yield stress at any void ratio is made possible with the use of an advanced model for the dependence of vertical yield stress on temperature, as well as the use of the unique effective stress–strain – strain rate concept. The first part of the paper presents an overview of the experimental and constitutive theoretical works performed on the effects of strain rate and temperature. The second part describes a strain rate and temperature coupled model, and the third part deals with the numerical validation of the proposed model.
PPARs Mediate Lipid Signaling in Inflammation and Cancer
Authors: Michalik Liliane , Wahli Walter
Published: December 2008

Lipid mediators can trigger physiological responses by activating nuclear hormone receptors, such as the peroxisome proliferator‐activated receptors (PPARs). PPARs, in turn, control the expression of networks of genes encoding proteins involved in all aspects of lipid metabolism. In addition, PPARs are tumor growth modifiers, via the regulation of cancer cell apoptosis, proliferation, and differentiation, and through their action on the tumor cell environment, namely, angiogenesis, inflammation, and immune cell functions. Epidemiological studies have established that tumor progression may be exacerbated by chronic inflammation. Here, we describe the production of the lipids that act as activators of PPARs, and we review the roles of these receptors in inflammation and cancer. Finally, we consider emerging strategies for therapeutic intervention.
A Robust Low‐Voltage On‐Chip LDO Voltage Regulator in 180 nm
Authors: Patri Sreehari Rao , Krishna Prasad K. S. R.
Published: December 2008

This paper proposes a capacitor‐less LDO with improved steady‐state response and reduced transient overshoots and undershoots. The novelty in this approach is that the regulation is improved to a greater extent by the improved error amplifier in addition to improved transient response against five vital process corners. Also entire quiescent current required is kept below 100 μA. This LDO voltage regulator provides a constant 1.2 V output voltage against all load currents from zero to 50 mA with a maximum voltage drop of 200 mV. It is designed and tested using Spectre, targeted to be fabricated on UMC 180 nm.
Breast Cancer Biology: The Multifaceted Roles of Mesenchymal Stem Cells
Authors: Patel Shyam A. , Heinrich Andrew C. , Reddy Bobby Y. , Srinivas Balaji , Heidaran Nicole , Rameshwar Pranela
Published: December 2008

Recent upsurge in the interest of breast cancer metastasis is partly attributed to the discovery of novel, yet unclear, mechanisms of breast cancer interaction with sites of distant metastasis such as the bone marrow microenvironment. In this review, we discuss the significance of the interactions between breast cancer cells and cells of the bone marrow. This is a subject of intense research studies aim to provide new methods of treatments and perhaps the identification of new drug targets. This review also discusses the role of inflammation and the bimodal function of the transforming growth factor- signaling pathway in the process of tumorigenesis. We bring attention to future prospects in breast cancer research, including the role of microRNAs in cancer quiescence in the bone marrow and the application of microRNAs to basic science discoveries in oncology. Finally, we discuss the cancer stem cell hypothesis, which is not a new idea, but has resurged with investigative questions.
Clear Cell Adenocarcinoma Arising from Abdominal Wall Endometriosis
Authors: Achach Thouraya , Rammeh Soumaya , Trabelsi Amel , Ltaief Rached , Ben Abdelkrim Soumaya , Mokni Moncef , Korbi Sadok
Published: December 2008

Endometriosis is a frequent benign disorder. Malignancy arising in extraovarian endometriosis is a rare event. A 49-year-old woman is presented with a large painful abdominal wall mass. She underwent a myomectomy, 20 years before, for uterus leiomyoma. Computed tomography suggested that this was a desmoid tumor and she underwent surgery. Histological examination showed a clear cell adenocarcinoma associated with endometriosis foci. Pelvic ultrasound, computed tomography, and endometrial curettage did not show any malignancy or endometriosis in the uterus and ovaries. Adjuvant chemotherapy was recommended, but the patient was lost to follow up. Six months later, she returned with a recurrence of the abdominal wall mass. She was given chemotherapy and then she was reoperated.
Mechanical and Thermal Properties of Polymethyl Methacrylate‐BN Nanotube Composites
Authors: Zhi C. Y. , Bando Yoshio , Wang Wenlong L. , Tang Chengchun C. , Kuwahara Hiroaki , Golberg Dmitri
Published: December 2008

Polymethyl methacrylate (PMMA)‐BN nanotube (BNNT) composites were fabricated and their mechanical and thermal properties were analyzed. Using a 1 wt.% BNNTs fraction in a polymer, the elastic modulus of PMMA was increased up to 19%. In addition, thermal stability and glass transition temperature of PMMA were also positively affected. The thermal conductivity of PMMA with BNNT additions increased three times. The resultant BNNT‐PMMA composites possess the high electrical breakover voltages. Thus our studies clearly indicate that BNNTs are promising nanofillers for improvement of mechanical and thermal conductivity of dielectric polymers under preservation of their electrical insulation.
Affine Anosov Diffeomorphims of Affine Manifolds
Authors: Tsemo Aristide
Published: December 2008

We show that a compact affine manifold endowed with an affine Anosov transformation is finitely covered by a complete affine nilmanifold. This is a partial answer of a conjecture of Franks for affine manifolds.
The Extended Likeability Framework: A Theoretical Framework for and a Practical Case of Designing Likeable Media Applications for Preschoolers
Authors: vanden Abeele Vero , Zaman Bieke
Published: December 2008

A theoretical framework and practical case for designing likeable interactive media applications for preschoolers in the home environment are introduced. First, we elaborate on the theoretical framework. We introduce the uses and gratifications paradigm (U&G). We argue that U&G is a good approach to researching likeability of media applications. Next, we complete the U&G framework with expectancy-value (EV) theory. EV theory helps us move from theoretical insights to concrete design guidelines. Together, the U&G framework and the EV model form the foundation of our extended likeability framework for the design and evaluation of interactive media applications, for preschoolers in the home environment. Finally, we demonstrate a practical case of our extended likeability framework via the research project CuTI. The CuTI project aims at revealing those particular user gratifications and design attributes that are important to support playful behaviour and fun activities of preschoolers in the home environment.
A New Method of Synthesizing Black Birnessite Nanoparticles: From Brown to Black Birnessite with Nanostructures
Authors: Cheney Marcos A. , Bhowmik Pradip K. , Qian Shizhi , Joo Sang W. , Hou Wensheng , Okoh Joseph M.
Published: December 2008

A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet‐aging at 7∘C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X‐ray diffraction (XRD), transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET) techniques. Wet‐aging and lyophilization times are shown to affect the architecture of the product. XRD patterns show a single phase corresponding to a semicrystalline birnessite‐based manganese oxide. TEM studies suggest its fibrous and petal‐like structures. The HRTEM images at 5 and 10 nm length scales reveal the fibrils in folding sheets and also show filamentary breaks. The BET surface area of this nanomaterial was found to be 10.6 m2/g. The TGA measurement demonstrated that it possessed an excellent thermal stability up to 400∘C. Layer‐structured black birnessite nanomaterial containing sheets, spirals, and filamentary breaks can be produced at low temperature (−49∘C) from brown birnessite without the use of cross‐linking reagents.
SVD‐Based Evaluation of Multiplexing in Multipinhole SPECT Systems
Authors: Jorgensen Aaron K. , Zeng Gengsheng L.
Published: December 2008

Multipinhole SPECT system design is largely a trial‐and‐error process. General principles can give system designers a general idea of how a system with certain characteristics will perform. However, the specific performance of any particular system is unknown before the system is tested. The development of an objective evaluation method that is not based on experimentation would facilitate the optimization of multipinhole systems. We derive a figure of merit for prediction of SPECT system performance based on the entire singular value spectrum of the system. This figure of merit contains significantly more information than the condition number of the system, and is therefore more revealing of system performance. This figure is then compared with simulated results of several SPECT systems and is shown to correlate well to the results of the simulations. The proposed figure of merit is useful for predicting system performance, but additional steps could be taken to improve its accuracy and applicability. The limits of the proposed method are discussed, and possible improvements to it are proposed.
Peripheral Mononuclear Cell Resistin mRNA Expression Is Increased in Type 2 Diabetic Women
Authors: Tsiotra Panayoula C. , Tsigos Constantine , Anastasiou Eleni , Yfanti Eleni , Boutati Eleni , Souvatzoglou Emmanouil , Kyrou Ioannis , Raptis Sotirios A.
Published: December 2008

Resistin has been shown to cause insulin resistance and to impair glucose tolerance in rodents, but in humans its physiological role still remains elusive. The aim of this study was to examine whether resistin mRNA expression in human peripheral mononuclear cells (PBMCs) and its corresponding plasma levels are altered in type 2 diabetes. Resistin mRNA levels were easily detectable in human PBMC, and found to be higher in DM2 compared to healthy women (P = .05). Similarly, mononuclear mRNA levels of the proinflammatory cytokines IL‐1β, TNF‐α, and IL‐6 were all significantly higher in DM2 compared to control women (P < .001). The corresponding plasma resistin levels were slightly, but not significantly, increased in DM2 women (P = .051), and overall, they correlated significantly with BMI (r = 0.406, P = .010) and waist circumference (r = 0.516, P = .003), but not with fasting insulin levels or HOMA‐IR. Resistin mRNA expression is increased in PBMC from DM2 women, together with increased expression of the inflammatory cytokines IL‐1β, TNF‐α, and IL‐6, independent of obesity. These results suggest that resistin and cytokines might contribute to the low‐grade inflammation and the increased atherogenic risk observed in these patients.
Superconductivity, Electron Paramagnetic Resonance, and Raman Scattering Studies of Heterofullerides with Cs and Mg
Authors: Kulbachinskii V. A. , Bulychev B. M. , Kytin V. G. , Krechetov A. V. , Konstantinova E. A. , Lunin R. A.
Published: December 2008

In the present study, the results of investigation of physical properties of heterofulleridesA3−xMxC60(A=K, Rb, Cs, M=Be, Mg, Ca, Al, Fe, Tl,x=1,2); as well asRbCsTlC60,KCsTlC60, andKMg2C60are described. All of the fullerides were synthesized by the exchange reactions of alkaline fullerides with anhydrous metal halides. Superconductivity was found inRbCsTlC60andKCsTlC60.
BPH Procedural Treatment: The Case for Value-Based Pay for Performance
Authors: Stovsky Mark , Jaeger Irina
Published: December 2008

The concept of “pay for performance” (P4P) applied to the practice of medicine has become a major foundation in current public and private payer reimbursement strategies for both institutional and individual physician providers. “Pay for performance” programs represent a substantial shift from traditional service-based reimbursement to a system of performance-based provider payment using financial incentives to drive improvements in the quality of care. P4P strategies currently embody rudimentarystructureandprocess(as opposed tooutcomes) metrics which set relatively low-performance thresholds. P4P strategies that align reimbursement allocation with “free market” type shifts in cognitive and procedural care using evidence-based data and positive reinforcement are more likely to produce large-scale improvements in quality and cost efficiency with respect to clinical urologic care. This paper reviews current paradigms and, using BPH procedural therapy outcomes, cost, and reimbursement data, makes the case for a fundamental change in perspective tovalue-based pay for performanceas a reimbursement system with the potential to align the interests of patients, physicians, and payers and to improve global clinical outcomes while preserving free choice of clinically efficacious treatments.
Differences in the Nature of Stroke in a Multiethnic Urban South African Population
Authors: Connor Myles D. , Modi Girish , Warlow Charles P.
Published: December 2008

Background and Purpose—

The burden of stroke is increasing in Sub-Saharan Africa (SSA) as the population undergoes epidemiological and demographic transition. Little is known about the nature (risk factors, stroke type and subtype, and causes) of stroke in SSA and whether it differs from stroke in high-income populations. We aimed to compare the nature of stroke between black and white populations in South Africa.

Methods—

We used overlapping sources to ascertain consecutive first-ever-in-a-lifetime stroke patients admitted to Johannesburg Hospital over 23 months. We assessed each patient’s demographic details, risk factors, CT confirmed pathological stroke type, ischemic stroke subtype and stroke severity, and compared the nature of stroke between black and white stroke patients.

Results—

524 patients with presumed stroke were referred. Of these, 432 were first-ever strokes; 308 patients were black and 76 white. Black patients were significantly younger (mean age 51) than white patients (61). Stroke severity was similar (median NIH stroke score 10; 95% CI 8 to 11). More black than white patients had cerebral hemorrhage (27% versus 15%), lacunar stroke (28% versus 22%) and total anterior circulation infarcts (28% versus 22%). Large vessel atherosclerosis (none detected) and ischemic heart disease were very uncommon (1%) as a cause of stroke in black patients. Hypertension (70% versus 68%) and diabetes (14 versus 15%) were as common in black and white stroke patients, but mean cholesterol levels were lower (4.6 mmol/L; 95% CI 4.3 to 4.9 versus 5.3 mmol/L; 4.8 to 5.7) and cigarette smoking less frequent in black patients (23 versus 54%).

Conclusions—

Although this was a hospital-based study, the difference in the nature of stroke between black and white stroke patients likely reflects the profile of stroke risk factors. There is an opportunity to prevent an otherwise inevitable increase in atherosclerotic stroke (and IHD) by targeting dietary and smoking habits in the black South African population.
Prolactin Treatment Improves Engraftment and Function of Transplanted Pancreatic Islets
Authors: Johansson Magnus , Olerud Johan , Jansson Leif , Carlsson Per-Ola
Published: December 2008

Transplantation of pancreatic islets is clinically used to treat type 1 diabetes but requires multiple donors. Previous experimental studies demonstrated that transplanted islets have a low blood vessel density, which leads to a hypoxic microenvironment. The present study tested the hypothesis that experimental prolactin pretreatment, a substance that seems to stimulate angiogenesis in endogenous islets, would increase graft blood vessel density, thereby improving transplantation outcome. Pancreatic islets from C57BL/6 mice were incubated with prolactin (500 ng/ml) or vehicle during the last 24 h of culture before syngeneic transplantation beneath the renal capsule, or recipients were injected with prolactin or vehicle for the first 7 d after transplantation. One month after transplantation, graft vascular density, blood flow, oxygen tension, endocrine volume, and function were evaluated. Also, human islets were incubated with prolactin or vehicle before experimental transplantation and investigated for vascular engraftment. Vascular engraftment of syngeneically transplanted mouse islets was improved by both in vivo and in vitro prolactin pretreatment. Moreover, prolactin pretreatment in vitro of islets used for transplantation improved recovery from diabetes in a minimal islet mass model. Interestingly, also human islets subjected to prolactin treatment before experimental transplantation demonstrated improved revascularization, blood perfusion, and oxygen tension when evaluated 1 month after transplantation. We conclude that prolactin may improve engraftment of transplanted pancreatic islets. The protocol with pretreatment of islets ex vivo could minimize the risk of side effects when used in the clinical setting.