bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Future Sustainable Power Technologies with Carbon Capture and Storage
Authors: Hadjipaschalis Ioannis , Christou Costas , Poullikkas Andreas
Published: July 2008

In this work, a technical, economic and environmental analysis concerning the use of three major power generation plant types including pulverized coal, integrated gasification combined cycle (IGCC) and natural gas combined cycle, with or without carbon dioxide (CO2) capture and storage (CCS) integration, is carried out. For the analysis, the IPP optimization software is used in which the electricity unit cost and the CO2 avoidance cost from the various candidate power generation technologies is calculated. The analysis indicates that the electricity unit cost of IGCC technology with CCS integration is the least cost option with the lowest CO2 avoidance cost of all candidate technologies with CCS integration. Further investigation concerning the effect of the loan interest rate on the economic performance of the candidate plants revealed that up to a value of loan interest of approximately 5.7%, the IGCC plant with CCS retains the lowest electricity unit cost. Above this level, the natural gas combined cycle plant with post-combustion CCS becomes more economically attractive.
Design of a New Oil Spraying Device for Hot Spot Cooling in Large Scale Electric Power Transformers
Authors: Mousavi Takami Kourosh , Mahmoudi Jafar
Published: July 2008

Hot spot temperature (HST) is the most important parameter in the operation of power transformers. The HST has to be held under a prescribed limit. HST has a considerable effect on the insulation aging. Therefore detecting, monitoring and removing the HST could be a very important and necessary action for utilities. A new design of oil spraying and its effect, along with a thermal management in a transformer cooling system has been studied in this paper. The effect of oil fluid flow on the HST problem has been considered in this paper; and the calculations and simulation have been performed by Ants algorithm. The simulation results have been validated based on a 230/63/20 kV, 250MVA transformer at the Sari substation in Iran, and the results indicate that the new design could mitigate the limitations of transformer loading due to the HST problem. The Ants algorithm have been proposed and applied for accomplishing this task and to give an improved level of accuracy.
Fundamental Analysis of the Static VAr Compensator Performance Using Individual Channel Analysis and Design
Authors: Ugalde Loo Carlos Ernesto , Acha Enrique , Liceaga-Castro Eduardo , Liceaga Castro Jesus U
Published: July 2008

In this paper the performance of a synchronous generator  SVC system is evaluated using Individual Channel Analysis and Design (ICAD), a control-oriented framework suitable for small-signal stability assessments. The SVC is already a mature piece of technology, which has become very popular for providing fast-acting reactive power support. The great benefits of ICAD in control system design tasks are elucidated. Fundamental analysis is carried out explaining the generator dynamic behavior as affected by the SVC. A multivariable control system design for the system is presented, with particular emphasis in the closed-loop performance and stability and structural robustness assessment. It is formally shown in the paper that although the addition of the SVC with no damping control loop does not improve the dynamic of the system, its inclusion is very effective in enhancing voltage stability. Moreover, ICAD analysis shows that with the use of the SVC the dynamical structure of the system is preserved and no considerable coupling or adverse dynamics are added to the plant.
Life Cycle Inventory Data Development for Greenhouse Gas Emissions of Thailand's Electricity Grid Generation Systems
Authors: Varabuntoonvit Viganda , Sadamichi Yucho , Kato Seizo , Mungcharoen Thumrongrut
Published: July 2008

LCA (Life Cycle Assessment) is a well known methodology to assess the impact on the environment over the life cycle of a product, process, or activity. This methodology is based on the LCI (Life Cycle Inventory) database, a data set of all resources (material and energy) that are consumed or emitted in order to produce 1 unit of the product. Because electricity is a basic infrastructure, a Thailand electricity grid LCI database is needed to assess the environmental impact not only for the product used in Thailand, but also for any product that is exported to other countries. A complete LCI database for the electricity grid in Thailand is not yet available, and the LCI database developed in this work applies from the fuel acquisition stage to the production stage. The analysis shows the unique characteristics of the Thailand electricity grid. An LCI database for each type of fuel and for each electricity generation system was developed. The characteristics of each type of fuel and electricity generation system are indicated in terms of Life Cycle GHG (Greenhouse Gas) emissions to reflect their global warming potential. Data on the Life Cycle GHG emission per kWh of electricity produced are also provided. The first Thailand LCI database for the fuels used in the electricity generation system was developed using data obtained from the EGAT (Electricity Generating Authority of Thailand), IPPs (Independent Power Producers), and PTT (Petroleum Authority of Thailand) during the Thai fiscal year 2005 (from October 2004 to September 2005). The database was used to analyze the current situation and the characteristics of the electricity generation system in Thailand and to compare it with the systems used in other developed countries.
A Dynamic Model of Insurgency: The Case of the War in Iraq
Authors: Blank Larry , Enomoto Carl E. , Gegax Douglas , McGuckin Thomas , Simmons Cade
Published: July 2008

This paper uses a system of differential equations to describe the insurgency in Iraq. The system has four possible outcomes or cases: (1) The U.S.-led coalition increases in size and the number of attacks by the insurgents increases. (2) The size of the U.S.-led coalition decreases and the number of attacks by insurgents decreases. (3) The size of the U.S.-led coalition increases and the number of insurgent attacks decreases. (4) The size of the U.S.-led coalition decreases and the number of insurgent attacks increases. Which case is relevant depends on the recruitment rates of the U.S.-led coalition and insurgents as well as the combat effectiveness of both sides. Policy implications are provided.
Moisture Adsorption and Desorption Isotherms of Aloe Vera (Aloe Barbadensis Miller) and Determination of Sorption Heats
Authors: Uribe Elsa , Miranda Margarita , Lemus Roberto , Vega-Gálvez Antonio
Published: July 2008

The sorption isotherms of Aloe vera were determined at 8, 30 and 45 °C, for a range of water activity (0.10-0.95). Modeling of the isotherms was done using the GAB, BET, Oswin, Halsey, Henderson, Smith, Caurie and Iglesias-Chirife equations. The fit quality of the models on experimental data was evaluated using the determination coefficient, sum squared errors and chi-square statisticals. The statistical results showed that the best fit quality was obtained by the Iglesias-Chirife model, followed by the GAB and Halsey. Monolayer moisture contents were obtained between 0.05-0.19 g water/g d.m. In addition, these parameters were temperature-dependent according to an Arrhenius-type equation. The sorption heat was calculated using the Clausius-Clapeyron equation giving 133.40 kJmol-1 (desorption) and 49.60 kJmol-1 (adsorption) at a moisture content of 0.01 g water/g d.m. The experimental heat data showed a good fit quality when these were evaluated by the Tsami equation.
Effect of High Pressure Shift Freezing Process on Microbial Inactivation in Dairy Model Food System
Authors: Choi Mi Jung , Min Sang Gi , Hong Geun Pyo
Published: July 2008

This study was carried out to investigate the microbial inactivation in dairy model system by high pressure shift freezing (HPSF). The UHT milk and broths were inoculated with Escherichia coli ATCC 25922, Staphylococcus aureus KCCM 11335 and Listeria monocytogenes HTCC 19115, respectively. The samples were pressurized to 200 MPa under different holding time at -18ºC. Inactivation effects of both E. coli ATCC 25922 and L. monocytogenes HTCC 19115 were significantly shown by the increment of pressure holding time (p<0.05) for not only in broth, but also UHT milk. The highest value of log reduction in NB media was observed as 6.1 after HPSF. However, inactivation effects of S. aureus KCCM 11335 were not significantly shown in tryptic soy broth (TSB) and UHT milk.
Physical and Mechanical Properties of Some Walnut (Juglans regia L.) Cultivars
Authors: Altuntas Ebubekir , Özkan Yakup
Published: July 2008

The physical properties of nuts and kernels of three Turkish walnut varieties (Juglans regia L.) such as dimensions, weight of nuts and kernels, sphericity, bulk density, volume, and coefficient of friction were determined. The resistance of the nut and kernel of walnut varieties to damage was determined by measuring the average rupture force, deformation and rupture energy along the X-, Y- and Z-axes at different compression speeds (30 and 60 mm/min). Both the static and dynamic coefficient of friction values were greater for the sheet iron surface than the galvanized one for all walnut varieties. The highest nut rupture force, deformation and rupture energy among the three walnut varieties occurred for Kaman loaded on the Y-axis. The results indicated that when testing the effects of compression axes the rupture force is highly dependent on walnut varieties. The lowest force needed to rupture the nut or kernel was found in walnut varieties with Sebin that were tested at a compression speed of 60 mm/min.
Modelling and Simulation Moisture Transfer in Wheat Stored in a Simulated Sealed Pit
Authors: Ismail Mohamed A. , Douglass Michael P. , Stenning Brian C.
Published: July 2008

A mathematical model, coupled to another one which was used to calculate the conductive heat transfer, was developed to predict the change of moisture distribution with time in the radial and axial directions in a simulated sealed cylindrical pit storing wheat. The finite difference method was used in the model to calculate the diffusive moisture transfer. The model predicts the grain moisture contents in the pit during the storage period using input data of initial grain temperature, initial grain moisture content, storage time and number of spatial elements in both radial and axial directions. Other input data include the finite difference spatial increment in both directions, the finite time increment, temperatures of soil surrounding the pit and the physical properties of grain, pit wall material and surrounding soil. To validate the model, predicted moisture contents were compared with measured data for wheat of Apollo variety being stored in a simulated sealed pit for a period of 70 days. The wheat was stored in a cylindrical mild steel tank with 0.6 m in both diameter and height. The initial uniform grain temperature was 15 °C and the initial uniform grain moisture content was 12.45% (w.b.). Both measured and predicted moisture contents show that the major change in wheat moisture content took place during the first week of the storage and an establishment of steady state under the storage conditions of the pit is unattainable i.e. moisture diffusion is a very slow process. At the end of the storage period, the grain moisture contents were increased by an average of 1.62% (w.b.) and the grain temperatures were decreased by an average of 2.63°C at the top layer of the pit. For the bottom layer of the pit, the grain moisture contents were decreased by an average of 0.50% (w.b.) and the grain temperatures increased by an average of 7.04°C. The diffusive moisture transfer model predicted the grain moisture contents with a standard error of estimate between measured and predicted of 0.18 -0.75% and of 0.18-0.74% (w.b.) using Chung's equation and modified Henderson's equation, respectively. There was no difference between the two sorption equations (Chung's and modified Henderson's equations) used in predicting grain moisture contents.
Nonlinear System Identification Using Laguerre Wavelet Models
Authors: Aadaleesan P. , Saha Prabirkumar
Published: July 2008

A compact and efficient model that is capable of approximating both the linear and nonlinear components of the process is in high demand. In this paper, a novel black-box modeling technique viz. Wiener type Laguerre-Wavelet model is proposed. The Laguerre-Wavelet model has the capability to approximate a function with moderate/reasonable number of data with appreciable approximation accuracy. The Laguerre filter is used to approximate the linear dynamic components of the process, whereas wavelet structure is used for the static nonlinear components. The ability of wavelets to approximate any square-integrable function to any arbitrary precision by input-output mappings is utilised for the nonlinear approximation following a modified single scaling method. The performance efficiency of the proposed Wiener type model structure, Laguerre-Wavelet model, is demonstrated using simulation case study on a continuous bioreactor.
Kinetic Studies on Sorption of Textile Dyes Using Lamina and Petiole Parts of Eichhornia crassipes
Authors: Renganathan S , Venkatakrishnan R , Gautam P , Miranda Lima Rose , Velan M
Published: July 2008

Sorption capacity of two different parts of Eichhornia crassipes such as Lamina and Petiole on a Basic dye (Basic Aurophine-O), Acidic dye (Acid Fast Red-A) and Reactive dye (Brill Red-5B) was studied in a batch system. The maximum equilibrium uptake capacity of petiole was 25.5 mg/g for Basic Aurophine-O, 23.1 mg/g for Acid Fast Red-A and 0.18 mg/g for Brill Red-5B. The equilibrium uptake capacity of petiole was found to be more in Basic Aurophine-O dye when compared to all other dyes studied. The maximum equilibrium uptake capacity of lamina was 27.0 mg/g for Basic Aurophine-O, 25.2 mg/g for Acid Fast Red-A and 4.2 mg/g for Brill Red-5B. The equilibrium uptake capacity of lamina was found to be more in Basic Aurophine-O when compared to Brill Red-5B and Acid Fast Red-A dyes studied in the present investigation. From the result, it was observed that the uptake capacity of dyes using E. crassipes part Lamina was found to be more when compared to the other E. crassipes part of Petiole used in the present study. Sorption results were found to be fitted very well with the Pseudo-second order kinetic model when compared to Pseudo-first order kinetic model. The intra particle diffusion coefficient (Ki) and diffusion coefficient (Di) obtained for the removal of dyes studied using Lamina was found to be more when compared to the other part of Petiole. The polynomial equations are developed and can be used as a ready reckoner equation to find out the percentage color removal of dyes studied in the present investigation at different period of time intervals.
Novel MILP Models for Scheduling Permutation Flowshops
Authors: Pitty Suresh S , Karimi Iftekhar A
Published: July 2008

Flowshop scheduling via mixed integer linear programming (MILP) has received considerable attention in the past four decades. However, alternate models are limited; most numerical studies have used small problem sizes. A need for good model evaluation methodology exists; and limited work exists on flowshops with no intermediate storage. This paper presents a classification of flowshops and MILP scheduling models, and addresses some of these issues. It develops a host of new MILP formulations for minimizing makespan in a permutation flowshop with no storage and with or without unit setups. It presents some useful insights into model building by employing a variety of new and old binary variables and coupling them creatively. In contrast to previous work, it evaluates a range of new and existing MILP models using many larger test problems with no or unlimited intermediate storage, and presents a reliable procedure to rank various models based on problems with varying data and sizes. It shows that the top models for the two flowshops indeed show slightly different computational performance.
Design and Optimization of a Filter Based on Artificial Neural Network Applied to a Distillation Column
Authors: Torrecilla Jose S , Fernández Adela , Garcia Julian , Rodríguez Francisco
Published: July 2008

This paper discusses the design and application of a filter based on an Artificial Neural Network (ANN) in a chemical engineering process. The design of a filter consists of adapting the algorithms that make up the filter to the process to be filtered. Taking into account that the ANN is able to model almost every type of chemical process, the design and application of a filter based on ANN was studied. In this work, every ANN used was based on Multilayer Perceptron (MLP). Bearing in mind that ANN should reproduce the process as accurately as possible, an optimisation of the ANN (training function and parameters) was carried out. A mathematical model of a reflux in the upper part of a distillation column was used to test the ANN filter. The ANN is able to filter noisy signals with a mean prediction error less than 2.510-3 %.
Modeling Catalytic and Homogenous Combustion of Hydrocarbons in Monolithic Converters
Authors: Chauhan Sanchita , Srivastava V. K.
Published: July 2008

In order to meet the strict future emission standards monolithic catalytic converters play a very important role. Although they have been extensively studied, still there are some areas that need to be further explored like the warm up period, during which the hydrocarbon emissions are relatively high. A single channel one-dimensional model can help evaluate the physicochemical processes occurring in the converter. In this study a decrease in the level of hydrocarbon emissions for propylene and propane during cold start are analysed taking into consideration the effect of both catalytic and homogenous reactions. The model proposed accounts for the combined effect of heat transfer, mass transfer and exothermic chemical reactions which are all strongly coupled.
Synchronizing Field and Control-Room Operators for Process Operating Transients
Authors: Manenti Flavio , Manca Davide
Published: July 2008

Process systems engineering is rapidly moving from steady state simulation towards operator training simulation, based on dynamic models, automated procedures, and predictive systems. Conventional operating conditions are well-known and easily controlled by field operators as well as control-room operators, whereas other situations are not yet. This is the case of more unusual circumstances, such as plant start-ups as well as planned and emergency shutdowns.The implementation of detailed dynamic mathematical models allows simulating the behavior of single process units as well as industrial plants, with the possibility to study unusual scenarios, especially for two reasons. First of all, it is necessary to train the operator and prepare him/her to face several events. Secondly, there is the need for evaluating the best automatic procedure to manage either unconventional or critical situations, without waiting for them to occur. In this sense, the safety approach is changing from reacting to predicting, thanks to the spread of tools that offer the possibility to simulate accidental events, unit and/or valve malfunctions, and significant process transients.The paper investigates and compares different procedures to control process transients, described by a sequence of actions, in order to coordinate synergistically the actions dictated by control-room operators and the operations to be accomplished manually by field operators. The main objective is to improve process start-up and shutdown reliability as well as the corresponding plant safety of an existing plant-wide control structure, without requiring any structural modification. A propane/butane splitter is adopted as a case study.
Income Insecurity and Youth Emancipation: A Theoretical Approach
Authors: Fernandes Ana , Becker Sascha O , Bentolila Samuel , Ichino Andrea
Published: July 2008

In this paper, we propose a theoretical model to study the effect of income insecurity of parents and offspring on the child's residential choice. Parents are partially altruistic toward their children and will provide financial help to an independent child when her income is low relative to the parents'. We find that children of more altruistic parents are more likely to become independent. However, first-order stochastic dominance (FOSD) shifts in the distribution of the child's future income (or her parents') have ambiguous effects on the child's residential choice. Parental altruism is the very source of ambiguity in the results. If parents are selfish or the joint income distribution of parents and child places no mass on the region where transfers are provided, a FOSD shift in the distribution of the child's (parents') future income will reduce (raise) the child's current income threshold for independence.
The Causal Effect of Studying on Academic Performance
Authors: Stinebrickner Ralph , Stinebrickner Todd R.
Published: July 2008

While a substantial amount of recent attention has been paid to understanding the determinants of educational outcomes, little is known about the causal impact of the most fundamental input in the education production function - a student's study effort. In this paper, we examine the causal effect of studying on grade performance by taking advantage of unique, new data that has been collected specifically for this purpose. Important for understanding the potential impact of a wide array of education policies, the results suggest that human capital accumulation is far from predetermined at the time of college entrance.
On the Optimal Allocation of Students and Resources in a System of Higher Education
Authors: Sallee James M , Resch Alexandra M , Courant Paul N
Published: July 2008

We model the social planner's decision to establish universities and populate them with students and resources, given a distribution of student ability and a limited pool of resources for higher education. If student ability and school resources are complements, and if there is a fixed cost to establishing a school, then the optimal allocation will involve a tiered system of higher education that sorts students by ability. In contrast to previous research, we show this tiered system is optimal even in the absence of peer effects. In considering where to locate students, the planner balances the benefit of providing students with more resources against the congestion costs of overcrowding schools. Nearly identical students who are close to the margin of entry to a higher or lower tier will experience discrete gaps in education quality. In considering how many universities to establish, the planner will balance the value of more precise tailoring against the cost of establishing additional schools. The planner's inability to perfectly tailor education quality will result in both winners and losers. Our model also makes predictions about how university systems that serve different populations should vary. Larger systems will produce more per dollar of expenditures and more education per student, due to economies of scale.
Lucky Last? Intra-Sibling Allocation of Child Labor
Authors: Chesnokova Tatyana , Vaithianathan Rhema
Published: July 2008

This paper has two objectives. First, we construct a theoretical model which explains the empirical evidence that in developing countries, first-born children are more likely to be child laborers than later-born. Second, we explore the long-run consequences of child labor regulations within our framework. In our model, credit-constrained parents use the labor income from their first-born child to fund the schooling of later-born children. In the presence of such intra-sibling effects, child labor laws which decrease work opportunities for children may backfire, increasing child labor and reducing human capital in the long run.
Entry into a Network Industry: Consumers' Expectations and Firms' Pricing Policies
Authors: Baglioni Angelo
Published: July 2008

Entry into a network industry is modeled focusing on consumers' expectations formation through higher order beliefs. Equilibrium expectations are endogenous and depend on prices, acting as a coordination device among consumers. The model is able to account for aggressive pricing policies by the incumbent and by the entrant. Both exclusion and entry are possible outcomes (depending on parameter values). The threat of entry is beneficial to consumers, even when unsuccessful.
A Duopoly Location Toolkit: Consumer Densities Which Yield Unique Spatial Duopoly Equilibria
Authors: Meagher Kieron J , Teo Ernie G.S. , Wang Wen
Published: July 2008

Anderson, Goeree and Ramer (1997) observe that although the Uniform consumer density is almost universally assumed in Hotelling style location games, it is more realistic to assume non-uniform distributions. Using Anderson et al.'s (1997) sufficient conditions for the existence of a unique pure strategy equilibrium, we extend the list of known distributions with characterised equilibria from two (Uniform and Triangular) to seven. Our extension includes the Normal and Logistic distributions which are commonly used in empirical research. We also analyse the effects of density choice on equilibrium outcomes. Holding the mean and dispersion of consumer tastes constant, we find that the Uniform distribution inflates differentiation effects.
Mechanism Design with Moderate Evidence Cost
Authors: Bull Jesse
Published: July 2008

This paper addresses how a moderate evidence disclosure cost can be incorporated into mechanism-design analysis. The paper shows that in public-action settings with transferable utility one can restrict attention to a class of three-stage dynamic mechanisms. Under complete information with two or more players, a version of this type of mechanism can be used to eliminate evidence production in equilibrium. The paper also provides conditions on the evidence environment under which the class of mechanisms studied in Bull and Watson (2004) is equivalent to those considered here.
Immigration Policy: Between Demographic Considerations and Preservation of Culture
Authors: Carmi Na'ama
Published: July 2008

Cultural rights of minority groups are recognized in international human rights law. These rights include the right of minority groups to adopt various measures to protect their cultural identity, which may include closure of the groups community from outsiders. The state in which such groups reside has a concurrent duty to respect these rights and sometimes even to take positive measures to ensure their implementation. The consideration of demographic factors, then, is regarded as legitimate when designed to protect minority groups. The rights of majority groups, on the other hand, are often ensured by the mere fact that they constitute a majority within the state and as such do not require special measures.This state of affairs is challenged, however, in face of mass immigration that could change the relation existing between majority and minority groups within the state. Under these circumstances, does a majority have the right to preserve its own culture through an immigration policy that takes into account demographic factors? I argue that the duty of states under international human rights law to protect rights of minority groups might serve as an incentive to restrict immigration endangering the character of the state. This characterthe states public cultureis the outcome of collective preferences of the majority of its citizens, which is assumed ought to be respected.
A concise quantum mechanical treatment of the forced damped harmonic oscillator
Authors: Li Ti
Published: July 2008

By selecting a right generalized coordinate X, which contains the general solutions of the classical motion equation of a forced damped harmonic oscillator, we obtain a simple Hamiltonian which does not contain time for the oscillator such that Schrödinger equation and its solutions can be directly written out in X representation. The wave functin in x representation are also given with the help of the eigenfunctions of the operator $$
\hat X
$$ in x representation. The evolution of $$
\left\langle {\hat x} \right\rangle
$$ is the same as in the classical mechanics, and the uncertainty in position is independent of an external influence; one part of energy mean is quantized and attenuated, and the other is equal to the classical energy.
The use of Cellomics to study enterocyte cytoskeletal proteins in coeliac disease patients
Authors: Mohamed Bashir , Feighery Conleth , Williams Yvonne , Davies Anthony , Kelleher Dermot , Volkov Yuri , Kelly Jacinta , Abuzakouk Mohamed
Published: July 2008

Coeliac disease is characterised by inflammation of small intestinal mucosa accompanied by abnormal villous architecture. It is now accepted that some patients with positive coeliac serology tests may have minor mucosal lesions that may not be apparent on routine histopathological analysis. The aim of the study was to perform detailed examination of enterocyte morphology and cytoskeletal structures using a high content analysis technology. Duodenal biopsies from 14 untreated and 10 treated coeliac patients and from 20 non-coeliac controls were examined. Tissue sections from six patients (study group subjects) before and after the development of gluten-sensitive enteropathy were also investigated. Immunohistochemical studies were performed on paraffin-embedded sections using an anti-α-tubulin antibody. Significant differences in enterocyte morphology and intracellular cytoskeletal structures were demonstrated in patients with proven coeliac disease and in the study group subjects. These changes were present in study group biopsies before evidence of enteropathy, as assessed by routine microscopy. This is the first study to demonstrate detailed characteristics of enterocyte morphology in coeliac patients using a high content analysis approach. The use of this technology allows a quantitative analysis of enterocyte intracellular structures from routine biopsy material and permits detection of subtle changes that precede the characteristic histological lesion.
Spinal meningiomas: Clinical and therapeutic tonsiderations
Authors: Schröder Johannes , Fischer Bernhard , Palkovic Stefan , Wassmann Hansdetlef
Published: July 2008

Meningiomas of the spinal canal are rare, in contrast to their cranial counterparts. This study reports on the dominant features of spinal meningiomas before and after treatment. We treated 30 patients (23 female) with meningiomas of the spinal canal from 1992 to 2003. The mean age was 68 (range: 43–91). Upon admission, 26 patients presented with a marked neurological deficit (11 paraparesis, 9 motor weakness, 4 myelopathic ataxia, 1 quadriplegia, and 1 cauda equina syndrome). Two patients had sensory deficits, and two had pain only. The distribution of the tumors was as follows: 8 cases were cranio-cervical, 1 case was cervical, 6 cases were at the cervico-thoracic junction, 9 cases were of the thoracic spine, 5 cases were of the thoracolumbar spine, and 1 case was of the lumbar spine. Five cases also had intracranial manifestations. The mean interval between the onset of the first symptoms and treatment was 12 months. All cases were treated via (hemi)-laminectomy for complete removal of the tumor and occasionally via duraplasty. After a mean follow-up of 3 years, symptoms had improved by 3 points (on a 5-point scale) in 3 cases, by 2 points in 7 cases, and by 1 point in 12 cases; 7 cases were unchanged, and 1 case had worsened by 1 point. We observed 3 local recurrences. One case developed manifestations at a different site. Spinal meningiomas are often diagnosed late, after they have already caused major neurological deficits. Nevertheless, owing to their benign character, the outcome is favorable when treated appropriately. The outcome depends above all on the initial neurological status. The worse the deficit is, the less probable it is that the patient will recover neurologically.
Caveat patiens — ethical dilemmas in decision -making
Authors: McKoy June , McKoy Judith
Published: July 2008

More than 99,358 men, women and children are on organ transplant lists in the United States. Pressure on family members to donate organs can therefore be intense. The medical excuse was created to address this potential coercion. It is a fabricated anatomical or physiological reason given to a donor (with or without the donor’s request) that provides an immediate shield against coercive pressure by family and friends on the potential donor. While the long-term risks and benefits of the medical excuse have not been studied, they could arguably include: 1) Reinforced perception that donation is expected; hence, declining donation is aberrant, and requires legitimization by external authority; 2) Eroded family trust of transplant physicians; 3) Eroded family trust in the individual reporting a “true” medical excuse; 4) Falsification of potential donor’s medical record; 5) Development of “toxic secrets” in the family unit; 6) Paternalism; and 7) General erosion of trust in both health care providers and the healthcare system. This author proposes a system of transparent and balanced communication where both the potential donor and the transplant team are clearly cognizant of the voluntary nature of the purported donation and where provisions for “opting-out” occur at any point along the pre-transplantation continuum.
Assessment of chemotherapy-induced anemia in children with cancer
Authors: Ruggiero Antonio , Attinà Giorgio , Haber Melina , Coccia Paola , Lazzareschi Ilaria , Riccardi Riccardo
Published: July 2008

Anemia is a common cause of co-morbidity in children with cancer. We reviewed a series of 124 children with non-metastatic cancer to assess the relationship between chemotherapy intensity, severe anemia, and frequency of transfusion. In more than 60% of children who received intensive chemotherapy, transfusions were prescribed compared to 38% and 21% of children treated with standard and mild chemotherapy, respectively. In conclusion, our data suggest that the intensity and duration of chemotherapy constitute important factors in determining the onset of anemia.
Dielectric properties of LC mixture with induced antiferroelectric phase
Authors: Wojciechowski M. , Bąk G. , Tykarska M.
Published: July 2008

Mixture of two liquid crystalline components exhibits the antiferroelectric phase in a broad temperature range at room temperatures, though the two components separately do not show an antiferroelectric phase in a temperature range applied. The dielectric spectroscopy technique combined with measurements of the selective light reflection was used for identification and characterization of the phases and subphases existing in the mixture. In the SmC*A phase, the low frequency mode characteristic of antiferroelectric phase has been detected. In the broad temperature range between SmC*A and SmA* phases, no relaxation mode has been detected. The soft mode registered near the phase transition to SmA* phase follows the Curie-Weiss law.
HUMAN FREEDOM AND TWO FRIEDMEN: MUSINGS ON THE IMPLICATIONS OF GLOBALIZATION FOR THE EFFECTIVE REGULATION OF CORPORATE BEHAVIOUR
Authors: Strine Leo E.
Published: July 2008

In this essay, which was delivered as the Torys Lecture, Vice Chancellor Strine considers the implications of globalization for the effective regulation of corporate behaviour affecting interests other than those of stockholders against the backdrop of the West's political and economic experience. He concludes that consistent with prior experience, the globalization of corporate markets will require a corresponding expansion of the polity to protect those aspects of human freedom that are affected in important ways by corporate behavior. As a practical matter, this means that if the U.S. and other Western nations wish to limit the ability of corporations to generate externalities and impair rights the West has embraced as important to individuals' ability to lead the good life, they will have to give up some of their sovereignty to international institutions in exchange for regulation that is co-extensive with the sphere in which corporations conduct their activities.
Clinical and neuroimaging outcome of cerebral arteriovenous malformations after Gamma Knife surgery: analysis of the radiation injury rate depending on the arteriovenous malformation volume
Authors: Han Jung Ho , Kim Dong Gyu , Chung Hyun-Tai , Park Chul-Kee , Paek Sun Ha , Kim Jeong Eun , Jung Hee-Won , Han Dae Hee
Published: July 2008

Object

In this paper the authors analyzed the clinical and neuroimaging outcomes of patients with cerebral arteriovenous malformations (AVMs) after Gamma Knife surgery (GKS), focusing on the analysis of the radiation injury rate depending on the AVM volume.

Methods

Between 1997 and 2004, 277 consecutive patients with cerebral AVMs were treated with GKS. Of these patients, 218 were followed up for ≥ 2 years. The mean age was 31 ± 15 years, the median AVM volume was 3.4 cm3 (range 0.17–35.2 cm3), the median marginal dose was 18.0 Gy (range 10.0–25.0 Gy), and the mean follow-up duration was 44 ± 20 months. The authors reduced the prescription dose by various amounts, depending on the AVM volume and location as prescribed in the classic guideline to avoid irreversible radiation injuries.

Results

The angiographic obliteration rate was 66.4% overall, and it was 81.7, 53.1, and 12.5% for small, medium, and large AVMs, respectively. The overall annual bleeding rate was 1.9%. The annual bleeding rate was 0.44 and 4.64% for small and large AVMs, respectively. Approximately 20% of the patients showed severe postradiosurgery imaging (PRI) changes. The rate of PRI change was 11.4, 33.3, and 9.5% for small, medium, and large AVM volume groups, respectively, and a permanent radiation injury developed in 5.1% of patients.

Conclusions

By using the reduced dose from what is usually prescribed, the authors were able to obtain outcomes in small AVMs that were comparable to the outcomes described in previous reports. However, medium AVMs appear to still be at risk for adverse radiation effects. Last, in large AVMs, the authors were able to attain a tolerable rate of radiation injury; however, the clinical outcomes were quite disappointing following administration of a reduced dose of GKS for large AVMs.
Effect of intracranial pressure on the diameter of the optic nerve sheath
Authors: Watanabe Arata , Kinouchi Hiroyuki , Horikoshi Toru , Uchida Mikito , Ishigame Keiichi
Published: July 2008

Object

The subarachnoid space around the optic nerve in the orbit can be visualized using T2-weighted MR imaging with the fat-saturation pulse sequence. The optic nerve sheath (ONS) diameter can be estimated by measuring the outer diameter of the subarachnoid space. Dilated ONS is associated with idiopathic intracranial hypertension and hydrocephalus, and is believed to reflect increased intracranial pressure (ICP). The relationship between dilated ONS and ICP is unclear because of the difficulty in obtaining noninvasive measurements of ICP. The authors investigated the relationship between subdural pressure measured at the time of surgery and ONS diameter measured on MR images in patients with chronic subdural fluid collection.

Methods

Twelve patients underwent bur-hole craniostomy with continuous drainage for chronic subdural hematoma or hygroma in 2006. Orbital thin-slice fat-saturated MR images were obtained before and after surgery, and the ONS diameters were measured just behind the optic globe. Subdural pressure was measured using a manometer before opening of the dura mater.

Results

A significant correlation was found between the ONS diameter and the subdural pressure (correlation coefficient 0.879, p = 0.0036). The ONS diameter before surgery (6.1 ± 0.7 mm) was significantly reduced after surgery (4.8 ± 0.9 mm, p = 0.003; measurements are expressed as the mean ± standard deviation).

Conclusions

Increased ONS diameter measured on coronal orbital thin-slice fat-saturated T2-weighted MR images is a strong indicator of increased ICP, and helps to differentiate between passive subdural fluid collection due to brain atrophy and subdural hygroma with increased ICP.
Aggravation of infarct formation by brain swelling in a large territorial stroke: a target for neuroprotection?
Authors: Walberer Maureen , Ritschel Nouha , Nedelmann Max , Volk Kai , Mueller Clemens , Tschernatsch Marlene , Stolz Erwin , Blaes Franz , Bachmann Georg , Gerriets Tibo
Published: July 2008

Object

In territorial stroke vasogenic edema formation leads to elevated intracranial pressure (ICP) and can cause herniation and death. Brain swelling further impairs collateral blood flow to the ischemic penumbra and causes mechanical damage to adjacent brain structures. In the present study the authors sought to quantify the impact of this space-occupying effect on ischemic lesion formation.

Methods

Wistar rats were assigned to undergo bilateral craniectomy or a sham operation and then were subjected to temporary middle cerebral artery occlusion (MCAO) for 90 minutes. A clinical evaluation and 7-T MR imaging studies were performed 5 and 24 hours after MCAO. The absolute brain water content was determined at 24 hours by using the wet/dry method.

Results

Bilateral craniectomy before MCAO led to a drastic reduction in lesion volume at both imaging time points (p < 0.0001). Ischemic lesion volume was 2.7- and 2.3-fold larger in sham-operated animals after 5 and 24 hours, respectively. Clinical scores were likewise better in rats that had undergone craniectomy (p < 0.05). After 24 hours the midline shift differed significantly between the 2 groups (p < 0.001), but not after 5 hours. The relation between brain water content and ischemic lesion volume as well as the T2 relaxation time within the infarcted area was not different between the groups (p > 0.05).

Conclusions

The data indicated that collateral damage caused by the space-occupying effect of a large MCA territory stroke contributes seriously to ischemic lesion formation. The elimination of increased ICP thus must be regarded as a highly neuroprotective measure, rather than only a life-saving procedure to prevent cerebral herniation. Further clinical trials should reveal the neuroprotective potential of surgical and pharmacological ICP-lowering therapeutic approaches.
Antimicrobial suture wound closure for cerebrospinal fluid shunt surgery: a prospective, double-blinded, randomized controlled trial
Authors: Rozzelle Curtis J. , Leonardo Jody , Li Veetai
Published: July 2008

Object

Implantation of cerebrospinal fluid (CSF) shunting devices is associated with a 5–15% risk of infection as cited in contemporary pediatric neurosurgical literature. Shunt infections typically require complete removal of the device and prolonged antibiotic treatment followed by shunt replacement. Moreover, shunt infections are commonly associated with prolonged hospital stays, potential comorbidity, and the increased risk of neurological compromise due to ventriculitis or surgical complications. The authors prospectively evaluated the incidence of CSF shunt infection following shunt procedures performed using either antimicrobial suture (AMS) or conventional suture.

Methods

In a single-center, prospective, double-blinded, randomized controlled trial, the authors enrolled 61 patients, among whom 84 CSF shunt procedures were performed over 21 months. Randomization to the study (AMS) or control (placebo) group was stratified to minimize the effect of known shunt infection risk factors on the findings. Antibacterial shunt components were not used. The primary outcome measure was the incidence of shunt infection within 6 months of surgery.

Results

The shunt infection rate in the study group was 2 (4.3%) of 46 procedures and 8 (21%) of 38 procedures in the control group (p = 0.038). There were no statistically significant differences in shunt infection risk factors between the groups (procedure type and time, age < 6 months, weight < 4 kg, recent history of shunt infection). No suture-related adverse events were reported in either group.

Conclusions

These results support the suggestion that the use of AMS for CSF shunt surgery wound closure is safe, effective, and may be associated with a reduced risk of postoperative shunt infection. A larger randomized controlled trial is needed to confirm this association.
Glossopharyngeal schwannoma in childhood
Authors: Thomas J. Alex , Bank William O. , Myseros John S.
Published: July 2008

Glossopharyngeal (that is, cranial nerve IX) schwannomas are extremely rare nerve sheath tumors that frequently mimic the more common vestibular schwannoma in their clinical as well as radiographic presentation. Although rare in adults, this tumor has not been reported in a child. The authors report the case of a 10-year-old boy who presented with several months of unilateral hearing loss. He was found to have a large right cerebellopontine angle tumor. Given the boy's primary complaint of hearing loss and the appearance of the lesion on imaging, the tumor was initially believed to be a schwannoma of the vestibular nerve. It was found intraoperatively, however, to originate from the glossopharyngeal nerve. To the authors' knowledge, this is the first reported case of a glossopharyngeal schwannoma in a child.
Thoracolumbar spine subdural hematoma as a result of nonaccidental trauma in a 4-month-old infant
Authors: Gruber Thomas J. , Rozzelle Curtis J.
Published: July 2008

The authors describe the previously unreported occurrence of thoracolumbar subdural hematoma (SDH) resulting from nonaccidental trauma and emphasize the need for a complete and thorough neurological, physical, and radiological examination in all cases of suspected nonaccidental trauma.

A 4-month-old male infant presented to the authors' Level 1 pediatric trauma center in respiratory arrest. According to the family, he had been previously healthy with a 1-day history of fussiness and irritability. While with one of the parents, the patient was noted to be apneic and had been shaken in 2 separate episodes in an attempt to stimulate respiration. Emergency services personnel intubated the child's trachea and transported him to the hospital. On arrival in the emergency department, the child was unresponsive and exhibited signs of myelopathy. A CT scan of his head demonstrated SDH and subarachnoid hemorrhage. Magnetic resonance imaging of the spine demonstrated an SDH dorsal to the spinal cord with some mass effect on the conus medullaris and descending nerve roots. The patient underwent emergency T-12 to L-3 laminotomies, evacuation of the hematoma, and laminoplasty.

The rigid nature of the rib cage provides a point of fixation around which the thoracolumbar spine can hyperflex and hyperextend when shaken, resulting in severe injury to the bony, vascular, and neural elements of the spine.
Dialysis disequilibrium syndrome: a consideration in patients with hydrocephalus
Authors: Flannery Thomas , Shoakazemi Alireza , McLaughlin Brian , Woodman Alistair , Cooke Stephen
Published: July 2008

Dialysis disequilibrium syndrome is a rare neurological manifestation of intermittent hemodialysis. Urea removal occurs more slowly across the blood–brain barrier than from the plasma, generating an osmotic gradient that promotes water movement into the brain and cerebral edema. The authors report the development of dialysis disequilibrium syndrome in a patient with spina bifida and an adequately functioning shunt.