bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of the Uncertainty in the Determination of the Equilibrium Moisture Content of Pumpkin Seed Flour
Authors: da Silva Wilton P. S. , Precker Jürgen W. , Silva Cleide M. D. P. S. , Silva Cleiton D. P. S. , Silva Diogo D. P. S. , de Lima A. G. B.
Published: March 2007

Empiric equations for the determination of the equilibrium moisture content as a function of temperature and relative humidity of air are normally obtained from experimental data by curve fitting. Once the fitting parameters of a function for a given product are determined, the value of that function for specific values of temperature and humidity of air is obtained by substituting these values into the function, which represents an indirect measurement. Generally, the results of these modelings are stated without the uncertainties inherent in the measurement. This article proposes a method for the determination of these uncertainties. For that, a computer code was developed which calculates the error propagation in first order approximation from the obtained fitting parameters and their covariances. The code was used for the determination of the uncertainties of the equilibrium moisture content of pumpkin seed flour, both for adsorption and desorption. This procedure allows a report of the measurement in agreement with the rules established by international standardization organizations.
Separation and Concentration of Health Compounds by Membrane Filtration
Authors: Saleh Zaid S , Stanley Roger , Wibisono Reginald
Published: March 2007

The performance of nano-filtration (NF) for separating phenolic compounds from sugar in apple juice was studied using 1 and 0.25 kDa molecular weight cut-off (MWCO) spiral wound membranes. If these phenolic compounds could be recovered, they could stabilize the juice from haze formation or be added as antioxidants to foods and beverages in order to increase their health properties. Batch experiments were conducted on a pilot scale rig using a diluted clear apple juice concentrate. For the 1 kDa MWCO membrane, the research determined the effect of operating conditions on process efficiency and membrane fouling. The concentration of polyphenolics on the retentate side increased by a factor of up to 4 and the sugar concentration increased by 1.5 times under optimum conditions of lower temperature (30oC), acidic pH (2), lower trans-membrane pressure (5 Bar) and higher initial sugar concentration (20 oBrix). Despite the increase in polyphenolics in the retentate, there was little difference in the phenolic composition between retentate and permeate solutions. As the molecular mass of the rejected phenolics was smaller than the membrane cut-off, this indicated that the rejection was related to the formation of a secondary membrane formed as a result of fouling. A mass balance of polyphenolics in the final retentate and permeate compared with the initial feed solution indicated that up to 4.3 gm of polyphenolics were bound per m2 of membrane. The permeate solutions collected from the 1 kDa MWCO membrane were then filtered using a 0.25 kDa MWCO membrane. Most phenolic compounds were retained by the membrane and the concentration increased by a factor of up to 2. Catechin, rutin, phloridzin and quercetin derivatives were concentrated on the retentate side. However, around 20 - 40% of chlorogenic acid and epicatechin was observed on the permeate side. It is concluded that membrane separation represents a potentially efficient and cost-effective technology to separate the phenolic fraction of fruit juice in a form suitable for use as a functional ingredient.
Conjugated Linoleic Acid Production by Fermentation
Authors: Dong Ming , Qi Shuting
Published: March 2007

Lactobacillus acidophilus 1.1854 was used for CLA production in whole milk and alfalfa seed oil was used as substrate. Alfalfa seed oil contained linoleic acid about 40%. Results showed that alfalfa seed oil addition to the culture improved CLA production, indicating the presence of linoleic acid isomerase activity in the culture. The concentration of lactic acid bacteria, the incubation time, the substrate concentration, the pH, incubation temperature, the pre-incubation time and the substrate amount of pre-incubation were studied in our research and they are optimized at 2.5%(v/v), 21h, 0.05%(v/v), pH 6.4, 37°C, 11h and 10µL which brought the optimal conversion ratio at about 50%.
Crystallization of Powders of Spray-Dried Lactose, Skim Milk and Lactose-Salt Mixtures
Authors: Langrish Tim , Wang Eric 'Hao-Liang'
Published: March 2007

Crystallization of spray-dried amorphous skim milk, lactose and lactose-salt mixtures at different relative humidities and storage times was studied by moisture sorption and X-ray diffraction tests. The results from the moisture sorption tests indicated that the time for 95% crystallization of skim milk powders at 75% and 89% relative humidities are 155 and 80 hours, respectively. For lactose, the 95% crystallization times at 51% and 75% relative humidities are 55 and 7 hours, respectively. A significant result is that salt delayed lactose crystallization, with lactose-salt mixtures (5:1 by weight) at 51% and 75% relative humidities having 95% crystallization times of 70 and 20 hours, respectively. Crystallization was also observed from increasing peak intensities in X-ray diffraction patterns. The rate of crystallization increased with increasing moisture content.
Estimation of Alanine and Glycine in Cane Juice Using Near Infrared Spectroscopy
Authors: Puri Aamarpali Ratna
Published: March 2007

The ICUMSA or AOAC (Association of Official Agricultural Chemists) traditional test methods for testing individual constituents, pol and brix, are time consuming, operator dependent and involve the use of hazardous chemicals. The increased awareness of environmental and health topics makes it desirable to avoid the clarification of cane juice with basic lead acetate. Widely used in the food and agricultural industries, Near Infrared Spectroscopy NIR has now made considerable inroads into the more lengthy and wet chemistry procedures. Near Infrared is the region of combination bands and overtones due to interatomic forces. Hydrogenic atoms being the lightest vibrate within the near infrared region due to N-H, O-H and C-H groups. These are common atoms present within most food products. As near infrared wavelengths are specific, individual components can be identified so it can be used for quantitative analysis of phosphates, silicates and amino acids in cane juice. Amino acids are important as they, along with other nitrogenous bodies, react with reducing sugars to form colored compounds. Analyzing amino acids in a sample can help solve color problem in sugar. Alanine and glycine are commonly found amino acids in sugarcane. In the present research the online estimation of alanine and glycine is done in cane juice using Near-Infrared spectroscopy. Near Infrared Spectrophotometer of Elico (India) range (600-2500nm) has been used in its transmittance mode in conjunction with two multivariate calibration procedures, i.e., Partial Least Square Regression analysis (PLSR) and Stepwise Multivariate Linear Regression analysis (SMLR) for the analysis of alanine and glycine in cane juice. Multi linear regression analysis was also carried out to find out the most correlating wavelengths along with the standard deviation.
GIT Physicochemical Modeling - A Critical Review
Authors: Yoo 'Michelle' Ji Yeon , Chen Xiao Dong
Published: March 2007

Many attempts to model the human gastrointestinal tract (GIT) were made since the beginning of the last decade. The main purpose was either to simulate an in vivo testing of drugs on animals or to investigate the viability of the probiotic intake. Two well-known physio-chemical models regarding the viability of the probiotics have been produced. In 1993, Molly et al. developed a simulator of the human intestinal microbial ecosystem (SHIME). Six reactors simulating the conditions of human stomach, duodenum/jejunum, ileum, caecum/ascending colon, transverse colon and descending colon were artificially developed. In 1995, Minekus et al. created a TNO gastro-intestinal model (TIM) with four computer-controlled chambers simulating the conditions of stomach, duodenum, jejunum and ileum. The simulated parameters included the body temperature, pH, salivary, gastric and intestinal mixing with peristaltic movements, secretions and absorption of water and small molecules. Despite the use of pharmacological, physiological and biochemical knowledge of the human and animal GIT and associated secretions, conflicting results such as the extremely low viability of probiotics were obtained. The failure of the above two models indicates the necessity of devising a suitable in vitro model that would be capable of simulating the digestion process as an exact replica of the actual in vivo model. In this paper, the key aspects of the above have been summarized and discussed.
Influences of Microemulsion Cross-linking Reaction and Ball-milling on Particle Size Characteristics of Potato and Maize Starches
Authors: Zhou Yu-guang , Li Dong , Wang Li-jun , Özkan Necati , Chen Xiao Dong , Mao Zhi-huai
Published: March 2007

In this study, microemulsion cross-linking treatment was used on food grade potato and maize starches for preparing micro starch particles. Laser diffraction technique was introduced to measure the particle size characteristics, including the median particle diameter (d 50), surface area mean diameter D [3, 2], volume mean diameter D [4, 3] and specific surface area of micro potato and maize starch particles. The volume distributions and number distributions were also analyzed using Mastersizer 2000 Software. The d 50, D [3, 2], D [4, 3] of the potato starch granules were reduced significantly (p < 0.05) after the microemulsion cross-linking reaction and ball-milling treatment. However, the microemulsion cross-linking treatment did not produce significant changes in the particle size characteristics of the maize starch samples.
The Business Case for Diabetes Disease Management for Managed Care Organizations
Authors: Beaulieu Nancy , Cutler David M , Ho Katherine , Isham George , Lindquist Tammie , Nelson Andrew , O'Connor Patrick
Published: March 2007

Diabetes is a common and very costly chronic disease. There is broad-based agreement on how to manage diabetes, yet less than 40% of adults with diabetes achieve guideline-recommended levels of medical care. We investigate the reasons for this phenomenon by examining the business case for improved diabetes care from the perspective of a single health plan (HealthPartners of Minnesota). The potential benefits accruing to a health plan from diabetes disease management include medical care cost savings and higher premiums. The potential costs to the health plan derive from disease management program costs and adverse selection. We find that the implementation of diabetes disease management coincided with large health improvements. For a defined population of diabetes patients, medical care cost savings over several years were small in the closed panel medical group but moderate for the health plan overall. We find evidence that adverse selection and the timing of cost and benefits worsen the health plan business case. In addition, the payment systems, from purchaser to health plan and health plan to provider, are very weakly connected to the quality of diabetes care, further weakening the business case. Finally, overlapping provider networks create a public goods externality that limits the health plans ability to privately capture the benefits from its investments. Nonetheless, it is clear that improved diabetes care affords economic benefits to health plans as well as valuable quality of life benefits to adults with diabetes.
Using Imagery to Predict Self-Confidence and Anxiety in Young Elite Athletes
Authors: Strachan Leisha , Munroe-Chandler Krista
Published: March 2007

As elite sport participation by children increases, it is important to study the psychological development of these athletes, specifically the management of self-confidence and anxiety. Imagery is one strategy that may be used by young athletes in controlling cognitions in competition (Weiss, 1991). Although research has been conducted examining imagery use by adult athletes (Hall, 2001), there have been fewer studies investigating how imagery is related to self-confidence and anxiety in young elite athletes (c.f., Vadocz et al., 1997) hence the purpose of the current study. Female participants were recruited from baton twirling competitions in Canada and the USA. Seventy-six athletes were divided into two age cohorts: 7-11 and 12-15 years. A modified version of the Sport Imagery Questionnaire (SIQ; Hall et al., 1998) and the Competitive State Anxiety Inventory 2 for Children (CSAI-2C; Stadulis et al., 2002) were given to each participant. Results indicated that developmental differences might exist between the two age cohorts in imagery use, self-confidence, and anxiety.
Steady-State Simulation of Hybrid Nickel Leaching Circuit Using Syscad
Authors: Razavimanesh Abbas , Tade Moses , Rumball John , Pareek Vishnu
Published: March 2007

There is an increasing focus on the hydrometallurgical processing of nickel-rich laterite ore due to declining global reserves of nickel sulphides. The development of new technology called hybrid nickel leaching circuit that encompasses pressure acid leaching (PAL) and atmospheric leaching (AL) processes has made processing of low-grade ores (with nickel content as low as 0.5%) a possibility. However, significant challenges exist in lowering the operating costs for this new process including the reduction of sulphuric acid and the energy required to heat the pulp to the desired temperature (250oC). To address above challenges, a detailed understanding of the process chemistry together with interactions between unit operations feeding into and out of the system is required. To accomplish this, a software package with powerful convergence algorithms, control loops, background chemical equilibrium, aqueous thermodynamics and extensive databases containing information on the physical properties of desired components is needed. Using such a process simulator, it is possible to produce numerically rigorous mass/energy balances for as many variations of the model as desired. This allows enhanced analysis of the flowsheet, better process design, and ultimately, better business decisions. Although there have been several studies on hybrid circuit, most of these studies have only dealt with the effects of process variable such as temperature, acidity, pulp density. Thus far, no complete study has been published on the modelling of different proposed scenarios. The present work constitutes an effort towards bridging this gap. A number of possible flowsheeting combinations were simulated using a commercial software packages SysCAD, and some optimal configurations were identified.
Optimal Solution of MINLP Problems Using Modified Genetic Algorithm
Authors: Danish Mohd. , Kumar Surendra , Qamareen Arees , Kumar Shashi
Published: March 2007

Many engineering and industrial constrained optimization problems can be modeled as mixed integer nonlinear programming (MINLP) problems e.g. heat and mass exchange networks, reactor-separator networks, batch plant design and scheduling, flow sheeting etc. The global optima in such problems are ill-conditioned due to the involvement of continuous and discrete variables, nonlinearities and non-convexities.This research work concerns the development of a modified GA and to apply it to find the solutions of several difficult MINLP problems. The modified GA utilizes tournament selection, SBX cross-over, polynomial mutation and variable elitism operators, along with distance based dynamic penalty with anti-distortion. The algorithm has been programmed in MATLAB. Six MINLP problems, which emerged from the optimal design of sequential multi-product batch plants, and considered as difficult ones in literature, were successfully solved. The solutions thus obtained are either comparable or better than those available in literature. The above combination of various schemes in modified GA helps in achieving faster convergence to global optimum with comparatively less violation of constraints; population size required is also less. The effect of various parameters on the convergence to global optimum has also been studied along with setting of various parameters. In future, efforts may be devoted to search proper merging strategy of quality operators for the design of a general purpose and robust GA so as to use it for a variety of engineering, specifically process engineering problems, more effectively.
Modeling of Grinding in a Laboratory Continuous Ball Mill for Dynamic Studies
Authors: Ramasamy M.
Published: March 2007

Comminution, in general, and grinding, in particular, is extremely energy intensive and it is imperative that size reduction equipment is operated at optimum operating conditions. Reasonably accurate mathematical models are required to understand their dynamic characteristics to enable optimisation and control of such unit operations. This paper deals with the development of a phenomenological mathematical model for describing size reduction operation in a laboratory-size continuous ball mill. Breakage rate function parameters and a correlation relating the power drawn to the operating conditions such as the mill throughput and percent solids in the mill were determined using the data collected from the ball mill operation. Using this correlation and the estimated breakage model parameters, simulations were carried out to compare the experimental data with the simulated results. It is observed that the model is adequately accurate in predicting the product size distributions with a maximum error of about 5% in the prediction of particles finer than 104 micron in the mill product.
Process Simulation - From Large Computers and Small Solutions to Small Computers and Large Solutions
Authors: Svrcek William Y , Satyro Marco A
Published: March 2007

This paper reviews the evolution of process simulation in conjunction with the evolution of computer hardware and software technologies from a chemical engineering perspective. A brief history of this hardware evolution is presented and points to exponential growth of computing power. The current personal computers or full function workstations have at least 1GB of memory, 100GB hard drive and run at 4 GHz. We as chemical engineers can only benefit from this continued hardware evolution, as the personal computer has become our full function slide rule.Concurrent with this hardware evolution there has been a proliferation of operating systems and applications software. Some of the applications software has migrated from mainframes and minicomputers and some has been specifically written to take advantage of the user-friendly features available on today's personal computers. A review of this software is presented with particular emphasis on process simulation software. The currently available fifth generation, non-sequential interactive process simulator does make process modeling and design a truly rewarding experience. This software has been designed to allow the personal computer and the engineer to do what each does best, namely the personal computer performing the systematic number crunching and the engineer the intuitive aspect of process simulation and design. The paper will conclude with a look into the future development of process simulation and its interaction with chemical engineering practice.
Learning to Control pH Processes at Multiple Time Scales: Performance Assessment in a Laboratory Plant
Authors: Syafiie S. , Tadeo F. , Martinez E.
Published: March 2007

This article presents a solution to pH control based on model-free learning control (MFLC). The MFLC technique is proposed because the algorithm gives a general solution for acid-base systems, yet is simple enough for implementation in existing control hardware. MFLC is based on reinforcement learning (RL), which is learning by direct interaction with the environment. The MFLC algorithm is model free and satisfying incremental control, input and output constraints. A novel solution of MFLC using multi-step actions (MSA) is presented: actions on multiple time scales consist of several identical primitive actions. This solves the problem of determining a suitable fixed time scale to select control actions so as to trade off accuracy in control against learning complexity. An application of MFLC to a pH process at laboratory scale is presented, showing that the proposed MFLC learns to control adequately the neutralization process, and maintain the process in the goal band. Also, the MFLC controller smoothly manipulates the control signal.
CFD Diagnosis of the Cyclotol Manufacturing Plant: Product Quality and Process Operation
Authors: Lea Jimmy , Adesina Adesoji A
Published: March 2007

The production of cyclotol, a military high explosive used in manufacture of aerial bombs, involves the multiphase mixing of molten TNT, RDX solid particles and water. Textural homogeneity of the final cyclotol mixture and near-zero water composition are critical requirements to minimize bomb-rejection rate and hence improved plant profitability. Although current data reveal significant statistical variation in product quality, detailed investigation of the complex mixing operation does not lend itself to physical experimentation due to the explosive nature of the process. This forestalls opportunities for improved process operation or re-design. To circumvent this constraint, a computational fluid dynamics (CFD) simulation of the industrial-scale process was carried out to understand how current mixing protocols impact on key in-tank profiles such as water draw-down, RDX particles suspension, turbulence kinetic energy, velocity magnitude, vector direction and water-entrainment. The analysis revealed that while the maximum impeller speed allowable to avoid water draw-down is 20 rpm, the minimum speed necessary to suspend the RDX particles for homogeneous mixing is 40 rpm. These opposing requirements are neither accommodated by the present mixing protocols nor achievable with the existing tank design. Even so, the 'mystery' of irrational cyclotol quality has been uncovered by a judicious use of CFD modeling and opened up the possibility of a revised tank design and optimal process operation for superior plant economics.
A Generalized Kinetic Model for Hydrometallurgical Processes
Authors: Habashi Fathi
Published: March 2007

In electrochemical leaching processes the solid must be an electric conductor, e.g., a metal, or a semiconductor, e.g., certain metal sulfides or oxides. Reaction takes place by the transfer of electrons at the solid surface and involves oxidationreduction processes that take place simultaneously at two different locations not far from each other. At one location, electrons are picked up by a depolarizer, D, in solution, e.g., O2, H+, etc. (the cathodic zone) and at another location metal ions are released in solution (the anodic zone) where they react with reagent C. A single kinetic law derived theoretically is obeyed: Rate = k1k2A[D][C] / (k1[D] + k2[C]) where k1 and k2 are constants, and A is the total surface area of the dissolving solid.
How Standards Drive Taxes: The Political Economy of Tailpipe Pollution
Authors: Gulati Sumeet , Roy Devesh
Published: March 2007

To control tailpipe pollution, governments often use environmental product standards and consumption taxes in conjunction (for example, the use of fuel economy standards and gasoline taxes to restrict automobile pollution in the US). Further, the choice of standards and consumption taxes is often independently influenced by special interests. For example, domestic producers have the incentive to influence environmental product standards, and likewise, domestic consumers have the incentive to influence the choice of the consumption tax. In this paper we explore the political link between environmental standards and consumption taxes in the presence of independent special interests. We find that despite the independence of special interests, the political outcome is inextricably linked. This political link is different from the welfare maximizing second-best link usually expected between two related policies, and is crucial in correctly anticipating policy outcomes. Specifically, we find that the government's choice of an environmental standard influences political incentives in the choice of the consumption tax. As the environmental standard falls, a higher demand for the environmentally damaging product develops. This higher demand increases the incentives for consumers to lobby for lower consumption tax. Under certain conditions, this political link is large enough to result in a complementary relationship between the two policies in equilibrium. The complementary relationship implies that a lower standard results in a lower consumption tax and vice versa when the standard is higher.
The Timing of Prenatal WIC Participation
Authors: Swann Christopher A
Published: March 2007

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides food vouchers, nutritional counseling, and health care referrals to low-income pregnant and breastfeeding women and their young children. This paper uses duration models to study the factors that influence the timing of prenatal WIC participation among pregnant women. The estimates show that Hispanic women, women with low levels of education, women who have no private insurance, and women who are overweight participate in WIC earlier than others. WIC program rules such as allowing applicants to self-declare income and linking WIC eligibility to Medicaid eligibility are related to earlier participation for women experiencing their first pregnancies. Extending the analysis to women pregnant for the second time shows a strong relationship between WIC participation during the first pregnancy and the timing, and likelihood, of participation during the second pregnancy.
The Role of Distance in Gravity Regressions: Is There Really a Missing Globalisation Puzzle?
Authors: Márquez-Ramos Laura , Martínez-Zarzoso Inmaculada , Suárez-Burguet Celestino
Published: March 2007

The main aim of this paper is to investigate the role of distance in gravity regressions in relation to the missing globalisation puzzle cited by Coe et al. (2002). These authors claimed that the fact that distance coefficients do not fall over time is another puzzle that should have been added in Obsfeld and Rogoff's (2000) paper, in which six major puzzles in international macroeconomics were cited. In order to do so, a linear and a non-linear gravity model are estimated for a cross-section of 65 countries over the period 1980-1999. Non-linear specifications of the gravity model have been recently used in the literature to address the issue of non-declining transport costs over time (Coe et al., 2002 and Croce et al., 2004). However, we claim that there is no missing globalisation puzzle once the linear specification results are correctly interpreted. The main findings are that distance has a different effect for developed and developing countries and that the grounds for using a non-linear specification are not clear since the linear specification, in general terms, shows better performance than the non-linear one.
Resource Allocation with Spatial Externalities: Experiments on Land Consolidation
Authors: Tanaka Tomomi
Published: March 2007

This paper compares the performance of a two-sided combinatorial call market, direct negotiation, and double auction for consolidating fragmented land. Experimental results suggest direct negotiation produces higher efficiencies than other mechanisms. The combinatorial call market tends to alleviate the exposure problem, and performs well when 1) swapping is easily agreeable, and 2) the number of subjects and commodities are increased and the initial endowments are unchallenging. The two-sided combinatorial call market, however, suffers from the holdout problem when the number of subjects and commodities is small.
Regional Integration, Subsidy Competition and the Relocation Choice of MNCs
Authors: Albornoz Facundo , Corcos Gregory
Published: March 2007

Regional integration makes relocation a more attractive option for Multinational Corporations (MNC), influencing in turn the provision of investment incentives by member countries. We examine in this context the effects of subsidy competition. To do so, we model the strategic interaction between two governments offering subsidies to a MNC facing different location alternatives, which involve relocation and plant closure. Our welfare analysis shows that the combination of regional integration and subsidy competition may lead to suboptimally high levels of subsidization. We also discuss how the desirability of harmonizing subsidies (by banning them), and the net gains from integration crucially depend on technological differences, ownership, and on corporate tax rates. For instance, a simple agreement on avoiding subsidies generally raises welfare if the MNC belongs to an extra-regional country. This is not the case for a regional MNC. Lastly, we find that the gain from regional subsidy coordination increases with integration.
The Optimal Consumption and the Quitting of Harmful Addictive Goods
Authors: Wang Ruqu
Published: March 2007

In this paper we study a model of rational consumption and quitting in the context of harmful addictive goods. We assume that a person has imperfect information about his ability to resist and terminate the addiction. We first characterize the optimal consumption path of a non-addicted person, along which his stock of the addictive substance is either always increasing (and thus addiction occurs stochastically), always decreasing, or always unchanged. We then characterize the optimal consumption path of an addicted person, along which he may attempt to quit the addiction for a period of time, and then resume his consumption if the attempt is unsuccessful. Finally, we remark on the issues of regret, multiple attempts to quit, and quitting programs.
Effective Scrappage Subsidies
Authors: Esteban Susanna
Published: March 2007

It is a common practice for governments to offer scrappage subsidies in order to stimulate the early removal of used cars and modify the distribution of vehicle holdings. In this paper, we analyze the market implications of such subsidies when producers have market power and face competition from a secondary used car market. One key result is that, with market power, a subsidy can induce scrappage even if it pays less than the price of a used car in the absence of the subsidy. We provide a full characterization of the effects of scrappage subsidies on primary and secondary markets for the case of a monopoly, and show that the subsidy that maximizes aggregate welfare lowers prices in the used car market. Our results contrast with the predictions derived from a model with perfect competition.
A Decentralized Market for a Perishable Good
Authors: Anwar Ahmed W , Sákovics József
Published: March 2007

We characterize the steady state of a market with random matching and bargaining, where the sellers' goods can perish overnight. Generically, the quantity traded is suboptimal, prices are dispersed and there is a dead-weight loss caused by excess supply or demand. In the limit as the cost of staying in the market tends to zero, only the amount of trade tends to the efficient level, the other two non-competitive characteristics remain. We discuss the implications of these findings on the foundations of competitive equilibrium and on the robustness of the results in the literature on durable-good markets.
Relating Network Structure to Diffusion Properties through Stochastic Dominance
Authors: Jackson Matthew O. , Rogers Brian W.
Published: March 2007

We examine the spread of a disease or behavior through a social network. In particular, we analyze how infection rates depend on the distribution of degrees (numbers of links) among the nodes in the network. We introduce new techniques using first- and second order stochastic dominance relationships of the degree distribution in order to compare infection rates across different social networks.
Intestinal alkaline phosphatase activity as a molecular marker of enterotoxicity induced by single dose of 5-fluorouracil and protective role of orally administered glutamine
Authors: Bajin-Katic Katica , Stankov Karmen , Djolai Matilda , Kovacevic Zoran
Published: March 2007

Background. One of the critical limitations for the administration of the chemotherapy is the toxicity affecting normal tissue. The main target organs for 5-fluorouracil (5-FU) toxicity in humans and experimental animals are the gastrointestinal tract, bone marrow, and skin. The cytotoxic effects of antimetabolite chemotherapy are based on their role as substrates for the same transport processes and enzymes involved in anabolism and catabolism as the natural substrates. The main goal of our study was to analyze the dose-dependent antiproliferative effects of 5-FU on intestinal mucosa, enterotoxic potential of 5-FU in experimental animals and to test possible protective role of glutamine. Methods. In our study, we used Sprague Dawley rats. The control group of rats included 50 animals, while the groups where either 5-fluorouracil (5-FU) alone or 5-FU and glutamine were administered included 200 animals. All experimental animals were further stratified according to the experimental model (25 animals in each of 8 experimental subgroups of animals). The 5-FU was administered by intraperitoneal application in single dose of 0, 100, 200, 300, and 400 mg of 5-FU per kg of body weight. Water solution of 1% glutamine was prepared daily and administered orally, in volume of 200 ml, for 7 days continuously, after the 7th day of 5-FU administration. Experimental animals were sacrificed 7 days after the administration of 5-FU. The isolation of enterocytes was performed according to the method of Kralovansky et al. In cell homogenate obtained by described method, we determined the protein content using the Biuret method and the DNA content using the Burton reagent. The activities of enzymes alkaline phosphatase (ALP), glutathione S-transferase (GST), glutathione reductase (GR), and glutathione peroxidase (GPX) were determined by kinetic method. All paraffin samples of the small intestine were stained by haematoxiline and eosine(HE method). All the experiments were done in duplicate and analyzed by standard statistical methods. All the experiments were done in duplicate and analyzed by standard statistical methods. Results: Our results of enterotoxicity induced by intraperitonealy administered 5-FU showed statistically significant decrease of DNA content in small intestine samples of experimental animals, decrease in activity of intestinal alkaline phosphatase enzyme and the increase in glutathione-dependent enzymes. The glutamine supplementation reduced 5-FU intestinal toxicity. Conclusion: Intestinal alkaline phosphatase is a good marker of the dose-dependent enterotoxicity induced by 5-fluorouracil.
Prognostic role of epidermal growth factor receptor in localized breast cancer: 15 Years of follow-up
Authors: Neskovic-Konstantinovic Zora , Kanjer Ksenija , Borojevic Nenad , Jezdic Svetlana , Gavrilovic Dusica , Nikolic-Vukosavljevic Dragica
Published: March 2007

Background: The expression of epidermal growth factor receptor (EGF-R) in breast cancer (BC) is generally considered as an unfavorable event during tumor progression. Its predictive role has been fairly well defined: EGF-R expression predicts tamoxifen unresponsiveness. EGF-R role in autocrine growth regulation was confirmed. However, reported results on its prognostic role in BC patients were conflicting. The prognostic role of EGF-R after 15 years of follow-up is analyzed in a group of 70 localized BC patients, presented at diagnosis in clinical stages I-III. Methods: BC patients newly diagnosed from December 1990 until March 1991, treated in accordance to the National Protocol, were selected for EGF-R analysis. Steroid receptors and EGF-R were determined at diagnosis in same frozen tissue samples, using biochemical methods. Except 6 patients who were lost from follow-up in the interval shorter than 60 months, the remaining patients were followed-up from 60-188 months. The total number of events was 32 relapses (46%), and 27 deaths (38.5%). Results: EGF-R expression was found in 28/70 patients (40%), and the EGF-R content higher than 26 fmol - in 15/70 patients (21%). Neither the expression, nor the high content of EGF-R showed any influence on disease-free or overall survival. Levels of EGF-R were similar in relapsing and relapse-free patients. Nodal status had the strongest infuence on prognosis. Conclusion: Our results suggest that the controversial findings, regarding the EGF-R prognostic role, might be the consequence of a genuine weak influence of EGF-R expression on disease outcome. .
Comparison of ultrasound controlled aspiration puncture to clinical examination in detection of breast cancer recurrence
Authors: Gojkovic Zdenka , Jovanovic Darjana , Gajanin Radoslav , Jakovljevic Branislava , Cvijetic Zeljka , Rakita Ivanka , Jungic Sasa
Published: March 2007

Background: Breast carcinoma recurrence appears in 5%-30% of cases, after the completion of breast cancer treatment. Recurrence appears on thoracic wall (chest wall), on the skin, on the breast tissue remaining after the surgery, equal sided axillary lymph nodes, supraclavicular lymph nodes or on the internal mammary lymph nodes. Recurrence often stays undetected by clinical examination, while it can be detected by ultrasound and punctured under ultrasound control. Cytological confirmation of malignant cells represents a signal to commence a specific recurrence treatment. Methods: Aspiration puncture under ultrasound control has been performed within 128 patients. Only 38 patients, out of 128, did not have distant metastasis at the moment of recurrence detection, so the recurrence was surgically removed and was subjected to the histopathological analysis. The results of definite histopathological analysis were compared to the clinical results and cytological results, which had been obtained preoperatively. Results: 31 patients, out of above mentioned 38 patients, have had breast carcinoma recurrence, while 7 patients have had benign tumor lesion. Clinical diagnoses were correct in 47.4% of cases, and incorrect for 52.6%. False positive finding result happened in 7.89% cases and false negative finding result happened in 39.47% cases. Ultrasound diagnoses were correct for 86.84% of patients and incorrect for 13.16% of patients. Cytological analysis of material obtained by aspiration puncture under ultrasound control produced correct diagnoses for 86.84% of patients. 13.16% of patients had inconsistent cytological and histopathological findings result. Cytological analysis has detected malignant cells for 5.26%, but the recurrence was not histopathologically confirmed, which points that the results were falsely positive. Falsely negative results were confirmed for 7.89%. Conclusion: Clinical examination was reliable for 52.6% of patients examined. Cytological analysis of material obtained by ultrasound-controlled puncture was reliable for 86.84% of patients examined. Aspiration puncture followed by cytological analysis gave falsely negative result for 7.89% of patients examined, while clinical examination gave falsely negative result for 39.47% of patients examined. Aspiration puncture gave falsely positive result for 5.26%, and clinical examination gave falsely positive result for 7.89%. Aspiration puncture is simple, easy to perform, without damaging effect for the patient or the medical personnel, it is not expensive and it is significantly more reliable than clinical examination itself for detection of breast carcinoma recurrence. .
Role of transforming growth factor-β1 in breast carcinogenesis
Authors: Ivanovic Vesna , Krtolica Koviljka , Krajnovic Milena , Dimitrijevic Bogomir
Published: March 2007

The main objective of this presentation is to review current knowledge regarding molecular mechanisms of Transforming Growth Factor-?1(TGF-?1) action in breast carcinogenesis. In addition, our recent results will be presented on TGF-?1 gene polymorphism and its relationship to TGF-?1 secretion in breast cancer (BC) patients. Special focus will be made on potential clinical applicability of TGF-?1 as a putative diagnostic, prognostic or predictive tool in BC detection and treatment. TGF-?1 has a complex multifunctional profile, with tumor suppressive effects in early stages of breast carcinogenesis, but progressive dominance of tumor promoting effects with transition to more advanced malignant states. Clarification of molecular mechanisms that control parallel processing of these opposing TGF-?1 activities might suggest new approaches for shifting the balance in favor of net tumor suppression. Now, a major challenge remains in more precisely defining TGF-?1 signaling pathways and their cancer-related alterations. Current dogma views human tumorigenesis as a molecular disruption of normal physiology through genetic, epigenetic, or somatic alterations. The genetic model offers biological plausibility to epidemiological studies that link the TGF-?1 gene polymorphism, at codon 10 due to Leu10Pro substitution in the signal peptide, with the risk of developing BC. The somatic mutations approach, provides an explanation for the TGF-?1 overexpression in advanced BC through mutations acquired in the components of Smad-mediated TGF-?1 signaling pathway. The available results indicate decreased T?RII (TGF-?1 receptor-type II) expression, rare T?RII gene mutations, but no mutations in Smad2 and Smad4 genes, in advanced BC patients. .
Angiogenesis: bFGF and VEGF in breast carcinoma
Authors: Vujasinovic Tijana , Buta Marko , Markicevic Milan , Nikolic-Vukosavljevic Dragica
Published: March 2007

Angiogenesis, or neovascularization, is a complex process leading to formation of new blood vessels from the pre-existing vascular network of the tissue. Angiogenesis plays a central role in various physiological and pathological conditions, including embryonic development, reproduction, inflammation and wound healing, infertility, heart diseases, ulcers, rheumatoid arthritis, diabetic blindness and cancer. It is a multistep process involving EC activation, basement membrane and extracellular matrix (ECM) degradation, EC proliferation, migration and differentiation, synthesis of new basement membrane and maturation of new blood vessels. Tumor vasculature is considered to be of an "immature" nature with series of structural abnormalities. There are reciprocal paracrine interactions between ECs, tumor cells, stroma and ECM. Angiogenesis plays a key role in transformation of normal to malignant cell, tumor progression and metastasis. It is similar to the metastatic process in that it requires EC attachment, proteolysis, and locomotion to proceed. A close relationship exists between the tumor and ECs invasiveness of the tissue. The switch to the angiogenic phenotype involves a change in the local equilibrium between positive and negative regulators of the growth of microvessels. Basic fibroblast growth factor (bFGF) and vas?cular endothelial growth factor (VEGF) are positive regulators of angiogenesis. Intimate cross-talk exists among bFGF and the different members of the VEGF family during angiogenesis, lymphangiogenesis, and vasculogenesis. A substantial body of experimental evidence supports the hypothesis that angiogenesis and angiogenic factors may be strong prognostic and predictive factors in breast carcinoma. This article reviews the current knowledge on angiogenesis and its positive regulators: bFGF and VEGF. .
In vivo model for research of breast cancer biomarkers
Authors: Kanjer Ksenija , Neskovic-Konstantinovic Zora , Nikolic-Vukosavljevic Dragica
Published: March 2007

The preoperative (neoadjuvant) setting of breast cancer treatment is an optimal in vivo model by which to allow the characterization of biomarker expression pattern with the tumor remaining in situ throughout treatment as an in vivo measure of response to particular therapy. Elucidating surrogate molecular or cellular markers of tumor response to therapy, may provide biological insight into both, the mechanism of tumor growth dynamics and drug sensitivity/resistance. Owing to the knowledge that many drugs are effective on actively proliferating cells and more intriguingly, that many anticancer agents with differing modes of action achieve cytotoxic effects by inducing apoptosis, has lead to a reappraisal of traditional views of tumor response/resistance to cytotoxic drugs in vivo. Accordingly, this review article will focus on discussing apoptosis phenomena and the p53 and bcl-2 protein as its regulators of principal impor?tance; a cell proliferation determined by the Ki-67 expression, as the major counterbalancing process to apoptosis is also considered. This paper reviews the rationale for the use of these proteins as indices of tumor response to therapy, as well as the published literature regarding their clinical relevance. So far, no firm conclusions can be made concerning their predictive utility. .
Estrogen-regulated proteins cathepsin D and pS2 in breast carcinoma
Authors: Markicevic Milan , Vujasinovic Tijana , Neskovic-Konstantinovic Zora , Nikolic-Vukosavljevic Dragica
Published: March 2007

In addition to classical prognostic/predictive factors, significant biological markers have been identified to provide potentially relevant information regarding natural or clinical course of breast cancer. Steroid receptor status of the primary breast cancer have been proven to be a predictor of response to endocrine therapy since up to 80 % of patients with steroid receptor-positive tumors respond to endocrine treatment. In order to improve the predictive value of steroid receptor status, attention has been paid to estrogen-regulated proteins, including pS2 and cathepsin D among others that may be indicators of a functional signal transduction pathway through which tumor cells respond to estrogen stimulation. It has been shown that pS2 protein may be constitutive product as well as estrogen-regulated product in breast carcinoma. pS2 appears to be positively correlated with ER, associated with a good prognosis and a predictor of response to endocrine treatment of primary and metastatic breast cancer. The expression cathepsin D may be both constitutive and overexpressed as a result of estrogen-induced transcription. It was believed that the main role of cathepsin D was to degrade protein, but many other biological functions of cathepsin D were recognized. Cathepsin D level in primary breast cancer has been demonstrated as an independent marker of poor prognosis associated with increased risk for metastasis and shorter survival times. Our recent results show direct correlation of cathepsin D positivity with pS2 expression. Additionally, we found that cathepsin D is statistically significantly associated with pS2 both in node-negative and node-positive patients bearing tumors smaller than 2 cm. .