bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid flow consideration in fin-tube heat exchanger optimization
Authors: Wais Piotr
Published: December 2010

Fluid flow consideration in fin-tube heat exchanger optimization

The optimization of finned tube heat exchanger is presented focusing on different fluid velocities and the consideration of aerodynamic configuration of the fin. It is reasonable to expect an influence of fin profile on the fluid streamline direction. In the cross-flow heat exchanger, the air streams are not heated and cooled evenly. The fin and tube geometry affects the flow direction and influences temperature changes. The heat transfer conditions are modified by changing the distribution of fluid mass flow. The fin profile impact also depends on the air velocity value. Three-dimensional models are developed to find heat transfer characteristics between a finned tube and the air for different air velocities and fin shapes. Mass flow weighted average temperatures of air volume flow rate are calculated in the outlet section and compared for different fin/tube shapes in order to optimize heat transfer between the fin material and air during the air flow in the cross flow heat exchanger.
The influence of external cooling system on the performance of supercritical steam turbine cycles
Authors: Kosman Wojciech
Published: December 2010

The influence of external cooling system on the performance of supercritical steam turbine cycles

The problem presented in this paper refers to the concepts applied to the design of supercritical steam turbines. The issue under the investigation is the presence of a cooling system. Cooling systems aim to protect the main components of the turbines against overheating. However the cooling flows mix with the main flow and modify the expansion line in the steam path. This affects the expansion process in the turbine and changes the performance when compared to the uncooled turbine. The analysis described here investigates the range of the influence of the cooling system on the turbine cycle. This influence is measured mainly through the change of the power generation efficiency. The paper explains the approach towards the assessment of the cooling effects and presents results of the modeling for three supercritical steam cycles.
Thermodynamic analysis of a new conception of supplementary firing in a combined cycle
Authors: Kotowicz Janusz , Bartela Łukasz , Balicki Adrian
Published: December 2010

Thermodynamic analysis of a new conception of supplementary firing in a combined cycle

The paper analyzes a new concept of integration of combined cycle with the installation of supplementary firing. The whole system was enclosed by thermodynamic analysis, which consists of a gas-steam unit with triple-pressure heat recovery steam generator. The system uses a determined model of the gas turbine and the assumptions relating to the construction features of steam-water part were made. The proposed conception involves building of supplementary firing installation only on part of the exhaust stream leaving the gas turbine. In the proposed solution superheater was divided into two sections, one of which was located on the exhaust gases leaving the installation of supplementary firing. The paper presents the results of the analyses of which the main aim was to demonstrate the superiority of the new thermodynamic concept of the supplementary firing over the classical one. For this purpose a model of a system was built, in which it was possible to carry out simulations of the gradual transition from a classically understood supplementary firing to the supplementary firing completely modified. For building of a model the GateCycle™ software was used.
Heating system with vapour compressor heat pump and vertical U-tube ground heat exchanger
Authors: Hanuszkiewicz-Drapała Małgorzata , Składzień Jan
Published: December 2010

Heating system with vapour compressor heat pump and vertical U-tube ground heat exchanger

In the paper a heating system with a vapour compressor heat pump and vertical U-tube ground heat exchanger for small residential house is considered. A mathematical model of the system: heated object - vapour compressor heat pump - ground heat exchanger is presented shortly. The system investigated is equipped, apart from the heat pump, with the additional conventional source of heat. The processes taking place in the analyzed system are of unsteady character. The model consists of three elements; the first containing the calculation model of the space to be heated, the second - the vertical U-tube ground heat exchanger with the adjoining area of the ground. The equations for the elements of vapour compressor heat pump form the third element of the general model. The period of one heating season is taken into consideration. The results of calculations for two variants of the ground heat exchanger are presented and compared. These results concern variable in time parameters at particular points of the system and energy consumption during the heating season. This paper presents the mutual influence of the ground heat exchanger subsystem, elements of vapour compressor heat pump and heated space.
On Noise Analysis of Oscillators Based on Statistical Mechanics
Authors: Thiessen Tina , Mathis Wolfgang
Published: December 2010

On Noise Analysis of Oscillators Based on Statistical Mechanics

In this paper a new approach of thermal noise analysis of electronic oscillators is presented. Although nonlinear electronic oscillators are one of the most essential subcircuits in electronic systems typical design concepts for these oscillators are based on ideas of linear circuits. Because the functionality of oscillators depends on nonlinearities, advanced design methods are developed where nonlinearities are an integral part. Since low voltage oscillator concepts have to be developed in modern IC technologies there is a need to include at least thermal noise aspects into the design flow. For this reason we developed new physical descriptions of thermal noise in electronic oscillators where we use ideas from nonequilibrium statistical mechanics as well as the Langevin approach. We illustrate our concepts by some examples.
64 Channel ASIC for Neurobiology Experiments
Authors: Gryboś Paweł , Kmon Piotr , Szczygieł Robert , Żołądź Mirosław
Published: December 2010

64 Channel ASIC for Neurobiology Experiments

This paper presents the design and measurements of 64 channel Application Specific Integrated Circuits (ASIC) for recording signals in neurobiology experiments. The ASIC is designed in 180 nm technology and operates with ± 0.9 V supply voltage. Single readout channel is built of AC coupling circuit at the input and two amplifier stages. In order to reduce the number of output lines, the 64 analogue signals from readout channels are multiplexed to a single output by an analogue multiplexer. The gain of the single channel can be set either to 350 V/V or 700 V/V. The low and the high cut-off frequencies can be tuned in 9 ÷ 90 Hz and in the 1.6 ÷ 24 kHz range respectively. The input referred noise is 7 μV rms in the bandwidth 90 Hz - 1.6 kHz and 9 μV rms in the bandwidth 9 Hz - 24 kHz. The single channel consumes 200 μW of power and this together with other parameters make the chip suitable for recording neurobiology signals.
Fast Low Voltage Analog Four-Quadrant Multipliers Based on CMOS Inverters
Authors: Machowski Witold , Kuta Stanisław , Jasielski Jacek , Kołodziejski Wojciech
Published: December 2010

Fast Low Voltage Analog Four-Quadrant Multipliers Based on CMOS Inverters

The paper presents quarter-square analog four-quadrant multipliers, based on proprietary architecture using four CMOS inverters. The most important upgrade on already published own circuit implementation is the use of the same inverter "core" of the circuit with completely redesigned auxiliary and steering blocks. Two variants of new driving peripherals are considered: one with differential pair, the second with CMOS inverters. The proposed circuit solutions are suitable for RF applications in communication systems due to simple architecture comprising building blocks with RF CMOS transistors having sufficiently large biasing currents. Postlayout simulation results done on the basis of 180nm CMOS UMC Foundry Design Kit are also presented.
A Study and Review of Self Managed Vehicular Networks
Authors: Agbinya Johnson , Navarrette Gina , Al-Ja'afreh Hanan
Published: December 2010

A Study and Review of Self Managed Vehicular Networks

An Intelligent transportation system (ITS) focuses on application of smart vehicles. The vehicles are equipped with significant computing, communicating and sensing capabilities to provide services to travelers or the goal of providing safety massages in emergency situations. Vehicular network may also be used for Internet access, inter-passengers communications and entertainment. To understand the behavior of such networks as well as to provide good services to the travelers many issues have to be managed, some of them are: call handover between vehicles in vehicular network, speed Vs capacity, security of call, network topology, and network fragmentation. In this paper we study such vehicular networks and explain these issues and the related work. Detailed study of practical node mobility models based on mobility states and the quality of practical links based on received signal strengths are used as inputs for system capacity studies. Experiments were run in Sydney based on drive tests with mobile terminals deployed on them. Then some new ideas for managing the vehicular networks are proposed.
Hysteresis Modeling Using a Preisach Operator
Authors: Bilski Adrian , Twardy Maciej
Published: December 2010

Hysteresis Modeling Using a Preisach Operator

The aim of this paper is to present the analysis and modeling of the hysteresis phenomenon using a Preisach operator. The fundamentals of parameterized hysteresis modeling are introduced, by utilizing three probability density functions. Then, the Preisach operator and its characteristics are defined. Subsequently, results of simulations obtained by means of the aforementioned functions are presented and compared to the ones obtained by other authors.
Advanced Photonic and Electronic Systems WILGA 2010
Authors: Romaniuk Ryszard
Published: December 2010

Advanced Photonic and Electronic Systems WILGA 2010

SPIE - PSP WILGA Symposium gathers two times a year in January and in May new adepts of advanced photonic and electronic systems. The event is oriented on components and applications. WILGA Symposium on Photonics and Web Engineering is well known on the web for its devotion to "young research" promotion under the eminent sponsorship of international engineering associations like SPIE and IEEE. WILGA is supported by the most important national organizations like KEiT PAN and PSP-Photonics Society of Poland. The Symposium is organized since 1998 twice a year. It has gathered over 4000 young researchers and published over 2000 papers mainly internationally, including more than 1000 in 10 published so far volumes of Proc. SPIE. This paper is a digest of WILGA Symposium Series and WILGA 2010 summary.
Measuring the Strength of Teachers' Unions
Authors: Strunk Katharine O. , Reardon Sean F.
Published: December 2010

The literature on teachers' unions is relatively silent about the role of union strength in affecting important outcomes, due in large part to the difficulty in measuring union strength. In this article, we illustrate a method for obtaining valid, reliable, and replicable measures of union strength through the use of a Partial Independence Item Response (PIIR) model. This method uses the individual regulations found within collective bargaining agreements (CBAs) and models their existence as a function of a contract-specific latent level of restrictiveness. This allows for the estimation of (a) a measure of the latent level of relative union strength and associated standard errors of measurement; (b) the reliability of the measure; (c) item severities for each item addressed in the contract, allowing for assessment of item restrictiveness; and (d) contract and item information.
Bayesian Estimation of the Logistic Positive Exponent IRT Model
Authors: Bolfarine Heleno , Bazan Jorge Luis
Published: December 2010

A Bayesian inference approach using Markov Chain Monte Carlo (MCMC) is developed for the logistic positive exponent (LPE) model proposed by Samejima and for a new skewed Logistic Item Response Theory (IRT) model, named Reflection LPE model. Both models lead to asymmetric item characteristic curves (ICC) and can be appropriate because a symmetric ICC treats both correct and incorrect answers symmetrically, which results in a logical contradiction in ordering examinees on the ability scale. A data set corresponding to a mathematical test applied in Peruvian public schools is analyzed, where comparisons with other parametric IRT models also are conducted. Several model comparison criteria are discussed and implemented. The main conclusion is that the LPE and RLPE IRT models are easy to implement and seem to provide the best fit to the data set considered.
A Comparison of Strategies for Estimating Conditional DIF
Authors: Moses Tim , Miao Jing , Dorans Neil J.
Published: December 2010

In this study, the accuracies of four strategies were compared for estimating conditional differential item functioning (DIF), including raw data, logistic regression, log-linear models, and kernel smoothing. Real data simulations were used to evaluate the estimation strategies across six items, DIF and No DIF situations, and four sample size combinations for the reference and focal group data. Results showed that logistic regression was the most recommended strategy in terms of the bias and variability of its estimates. The log-linear models strategy had flexibility advantages, but these advantages only offset the greater variability of its estimates when sample sizes were large. Kernel smoothing was the least accurate of the considered strategies due to estimation problems when the reference and focal groups differed in overall ability.
Experimental Study of Free Energy of Activation of Flow and Grunberg-Nissan Parameters in Binary Liquid Mixtures
Authors: Jha IS , Koirala RP , Adhikari D
Published: December 2010

The binary mixtures of cabontetrachloride with isobutylmethylketone and benzaldehyde were studied at 308.15 by measuring viscosities and densities. The derived and excess viscosities, activation energy of flow and Grunberg-Nissan parameters have been calculated. It was found that these parameters are satisfactorily used to predict the strength and nature of molecular interactions. It was found that the strength of interactions in the systems studied is in the following order: CCl4 + IBMK>CCl4 + BDKeywords: Binary liquid; benzaldehyde; carbontetrachlorideDOI: 10.3126/bibechana.v6i0.3932BIBECHANA Vol. 6, March 2010 pp.9-14
Food Additives
Authors: Chaudhary Narendra Kumar
Published: December 2010

Different types of food additives have been discussed. I have discussed the role of food additives to preserve nutritional values and to maintain desired consistency of the product. The antioxidants and antimicrobials food preservatives have also been studied. Keywords: food additives; preservatives; colorants; sweetenersDOI: 10.3126/bibechana.v6i0.3935BIBECHANA Vol. 6, March 2010 pp.22-26
Dark Matter in the Universe
Authors: Adhikari Devendra , Adhikari Krishna Raj
Published: December 2010

Different physical phenomena, techniques, and evidences which give the proof for the existence of dark matter have been discussed. Keywords: Baryonic matter; dark matter; Chandra x-ray ObservatoryDOI: 10.3126/bibechana.v6i0.3936BIBECHANA Vol. 6, March 2010 pp.27-30
Effect of Sewage and industrial effluents on flowering behavior and yield of pea (Pisum sativum L. var. arkel)
Authors: Shrestha Mohan Kumar
Published: December 2010

Municipality Sewage and effluents from Shah Udyog and Dairy Farming were taken to assess the flowering behavior and yield of pea. The effluents from Dairy Farming initiated flowering earlier than the other effluents while effluents of Shah Udyog retarded comparatively. The same trend was followed for anthesis, withering and pod appearance. Duration of anthesis was found increasing in the order: Dairy Farming, Municipality Sewage, Control and Shah Udyog respectively. On the other hand, number of seed per plant and dry weight per seed was found in decreasing order from Dairy Farming to Shah Udyog through Municipality Sewage. Key words: Effluents; Flowering; Yield; Inhibition and promotion DOI: 10.3126/bibechana.v7i0.4049BIBECHANA 7 (2011) 70-75
Riemann integral and its relation with Lebesgue integral
Authors: Bhattrai Mani Raj
Published: December 2010

This review explains the limitations of the Riemann integral and focuses on the more general concept. It has been suggested that a better route is to abandon the Riemann integral for Lebesgue integral and explained the importance of Lebesgue integral in real analysis and other fields of mathematical science. Keywords: Riemann integral; Lebesgue integral; Fourier series DOI: 10.3126/bibechana.v7i0.4051BIBECHANA 7 (2011) 83-86
Exorcistes américains : la Heritage Foundation, la guerre culturelle et la sauvegarde du mariage et des valeurs familiales traditionnelles
Authors: Gagnon Frédérick , Goulet-Cloutier Catherine
Published: December 2010

Abstract:

During the Republican Party's national convention in 1992, Pat Buchanan claimed that a “culture war” was raging in the United States. While Buchanan described this “war” as a “struggle for the soul of America,” we use the culture-war concept to refer to the efforts of various conservative political and social actors trying to protect US traditional values and to “exorcise” the liberal and secular “demons” of the United States. Accordingly, this paper focuses on one of these actors: the Heritage Foundation, a conservative think tank located in Washington, DC. Performing a postructuralist discursive analysis of various “texts” produced by three scholars from the Heritage about marriage, family values, and sexuality, the paper shows how these scholars strategically rely on certain words and expressions in their research in order to reach two political goals: (1) marginalize liberal views on the issues just mentioned; and (2) discipline Americans by leading them to embrace a traditional/conservative interpretation of US national identity.
Surgical Ventricular Restoration (SVR) - Hope for Heart Failure Patients or is it a Dilemma?
Authors: Ahmed F , Sharifuzzaman M , Chanda PK
Published: December 2010

DOI: 10.3329/cardio.v2i2.6626Cardiovasc. j. 2010; 2(2) : 118-120
Comparison of Recovery and Postoperative Analgesia between Thoracic Epidural Anaesthesia (TEA) plus General Anaesthesia and General Anaesthesia alone, in Patients Undergoing Off-Pump Coronary Artery Bypass (OPCAB) Surgery
Authors: Ferdous S , Hossain S , Haque N , Chowdhury AYFE
Published: December 2010

Background: In recent years, high thoracic anaesthesia (HTEA) combined with general anaesthesia has been extensively studied in patients undergoing coronary artery bypass graft surgery with or without cardiopulmonary bypass. Off-pump coronary artery bypass grafting was implemented to reduce trauma of surgical coronary revascularization by avoiding extracorporeal circulation. TEA in combination with GA further reduces intraoperative stress resulting in more rapid extubation and significantly better pain relief in patients undergoing off-pump coronary artery bypass grafting (OPCAB). In addition, common postoperative complications are also decreased. Methodology: 40 male patients aged between 40-65 years with CAD undergoing OPCAB surgery at NICVD from April 2006 to October 2008 were randomly divided in two groups. Group A received epidural analgesic drugs through an indwelling catheter introduced before induction of anesthesia while group B patients received standard general anesthesia (GA) alone. Group A patients received continuous epidural analgesia delivered through the indwelling catheter with a mixture of Lignocaine (2%) 20 ml + Bupivacaine (0.5%) 20 ml + Fentanyl 50 gm 1 ml + normal saline q.v. 50 ml at the rate of 1-2 ml/hour by a syringe pump for up to 72 hours. Group B patients received conventional intermittent narcotics (Morphine)/NSAIDS (Ketorolac/Diclofen) for up to 72 hours. Results: Haemodynamic parameters of all patients in both the groups were within acceptable range throughout operations. Incidence of cardiac dysrhythmias was less in patients of group A. Group A patients showed faster recovery and better analgesia compared to Group B patients. There was also decreased incidence of nausea, vomiting, arrhythmia, O2 desaturation, confusional states, renal failure and requirement of iontropic support in ICU in Group A patients. TEA for postoperative analgesia was safe and well accepted by the patients. There was no complication related to epidural anesthesia in any patient. Conclusion: TEA in general anesthesia provides faster recovery and effective analgesia. Nonetheless, the actual and potential risks of TEA during cardiac surgery should not be underestimated. Keywords: Thoracic epidural anaesthesia; OPCAB; Postoperative analgesia DOI: 10.3329/cardio.v2i2.6632Cardiovasc. j. 2010; 2(2) : 156-162
Coronary Angiographic Characteristics of Patients with First Myocardial Infarction Admitted in a Tertiary Care Cardiac Hospital in Bangladesh
Authors: Kabiruzzaman M , Ali MA , Islam MN
Published: December 2010

Background: Coronary artery lesion characteristics of patients with First myocardial infarction (First MI) of Indian subcontinent origin in UK, is different from indigenous white population. The present study was aimed to observe coronary angiographic profile of first MI patients, hospitalized in a tertiary care hospital, in Bangladesh and to compare the results with published data of study done home and abroad. Methods: This is a prospective observational study. A total of 100 cases of First MI patients were included in this study. Clinical history, physical examination, major risk factors, relevant investigations including ECG & Echocardiogram and coronary angiogram of all patients were recorded. Results: The coronary angiographic features of 100 patients revealed that 88% of the study population had significant coronary artery lesion (stenosis e”70%). Normal coronary arteriogram was found in 5 patients (5%); although they had myocardial infarction previously. Insignificant lesion (stenosis < 70%) was detected in 7 patients (7%). Left anterior descending (LAD) arteries were affected in most of the patients (78%), followed by right coronary artery (62%) and left circumflex artery (55%). Single vessel disease (33%) and triple vessel diseases were equally prevalent among the study population. Conclusion: Present study observed that triple vessel disease, diffuse pattern of lesions and combined type of lesions were more prevalent among the first MI patients. Increase in the number of risk factors was associated with progressive increase in severity of disease as defined by number of significant stenosis. Comparison of results of present study population with that of study done abroad shows that single vessel disease was more prevalent among European white patients who had first MI but triple vessel disease was more prevalent among our patients. Keywords: First MI; Coronary angiogram. DOI: 10.3329/cardio.v2i2.6640Cardiovasc. j. 2010; 2(2) : 204-211
Non-invasive Diagnosis in Clinically Suspected ASD Secundum
Authors: Jahan WA , Azam A , Rahman M , Meah N , Meah AY , Sabur SAMA A , Khan JH
Published: December 2010

Background: The non-invasive tests like X-ray, ECG and Echocardiography are viewed as an extension of clinical art in cardiology and have become an integral part of history taking, physical examination and other diagnostic method. Atrial Septal Defect (ASD) of secundum type is defined as a through and through communication at atrial level. Previously the diagnosis and decision of surgery for ASD, mandatorily advocate cardiac catherization. Now cardiologist and cardiac surgeon very hardly asked for cardiac catheterization. Non-invasive diagnosis with the help of ECG, X-ray and Echo is sufficient for its diagnosis and treatment for surgery. In Bangladesh there is no study upon it. Considering this ground the study is perform on Bangladeshi patients.Methods: Forty six consecutive patients with clinical (auscultatory and electrocardiographic) signs of uncomplicated atrial septal defect of secundum type were examined by chest x-ray, ECG and echocardiography, before right heart catheterisation.Result: Thirty four (74%) had ASD, four patients (9%) had insignificant pulmonary stenosis, and eight subjects (17%) were normal. No false positive diagnosis of atrial septal defect was made by chest x-ray examination, whereas increased vascular markings were incorrectly interpreted as pulmonary congestion in one case. Eight patients had x-ray films showing questionable signs of left-to-right shunt. Twelve of 30 patients with a large left-to-right shunt were correctly selected for surgery based on radiological findings. Conclusion: Analysis of non invasive diagnosis and management of ASD secundum conform the usually described pattern in western literature. Keywords: Atrial Septal Defect; Cardiac Imaging DOI: 10.3329/cardio.v2i2.6645Cardiovasc. j. 2010; 2(2) : 223-226
Infective Endocarditis by Pseudomonas Species Following Percutaneous Transluminal Mitral Commissurotomy
Authors: Rahman MT , Mannan MA , Ullah M , Rahman Z , Khair A , Hossain A , Sayami LA , Ahmed MU , Roy SS , Masud AA , Das M , Majumder AAS
Published: December 2010

Infective mitral valve endocarditis developed in a 35-year-old male patient after a percutaneous transvenous mitral commissurotomy (PTMC). The echocardiogram demonstrated vegetation in the anterior leaflet of the mitral valve and blood culture showed growth of Pseudomonas species which was sensitive to Ceftazidime, Ciprofloxacin, Cotrimoxazole and Imipenem and resistant to Amikacin, Ceftriaxone, Gentamycin and Nitilmycin. The patient underwent treatment with intravenous ceftazidime and ciprofloxacin for six weeks and patient improved significantly and got cure of the disease. Infective mitral valve endocarditis should be recognized as a potentially lethal complication after PTMC. The important measures to prevent bacteremia during PTMC and the appropriate role of antibiotics and operation are discussed. Keywords: PTMC; Infective endocarditis. DOI: 10.3329/cardio.v2i2.6649Cardiovasc. j. 2010; 2(2) : 252-255
Cervical Epidural Anesthesia for Carotid Endarterectomy
Authors: Alauddin M , Choudhury BMM , Beg AK , Alam SAN , Chowdhury AYFE
Published: December 2010

The successful anaesthetic management using a cervical epidural technique is reported in patients undergoing carotid artery surgery. Adequate analgesia is obtained and the adequacy of cerebral blood flow is easily judged by the patient’s state of consciousness. Cervical epidural anaesthesia could be a safe and reasonable technique for the management of patients who need carotid artery surgery.A 54 years old man of A.S.A (American Society of Anesthesiologists) grade- II underwent carotid endarterectomy under Cervical Epidural Anaesthesia (CEA) at C7 – T1 level using a mixture of 0.5% Lidocaine, 0.25% Bupivacaine and Fentanyl citrate. Standard peroperative monitoring including invasive arterial blood pressure and arterial blood gas analysis was done. Keywords: Cervical epidural Anaesthesia; Carotid Endarterectomy; Monitoring of cerebral function DOI: 10.3329/cardio.v2i2.6650Cardiovasc. j. 2010; 2(2) : 256-257
Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry
Authors: Zaima Nobuhiro , Hayasaka Takahiro , Goto-Inoue Naoko , Setou Mitsutoshi
Published: December 2010

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful tool that enables the simultaneous detection and identification of biomolecules in analytes. MALDI-imaging mass spectrometry (MALDI-IMS) is a two-dimensional MALDI-mass spectrometric technique used to visualize the spatial distribution of biomolecules without extraction, purification, separation, or labeling of biological samples. MALDI-IMS has revealed the characteristic distribution of several biomolecules, including proteins, peptides, amino acids, lipids, carbohydrates, and nucleotides, in various tissues. The versatility of MALDI-IMS has opened a new frontier in several fields such as medicine, agriculture, biology, pharmacology, and pathology. MALDI-IMS has a great potential for discovery of unknown biomarkers. In this review, we describe the methodology and applications of MALDI-IMS for biological samples.
Temporal and Spatial Aspects of Snow Distribution in the Nam Co Basin on the Tibetan Plateau from MODIS Data
Authors: Kropacek Jan , Feng Chen , Alle Markus , Kang Shichang , Hochschild Volker
Published: December 2010

Large areas of the Tibetan plateau are only covered by a sparse network of ground snow sampling stations, while the snow cover is highly heterogeneously distributed due to wind, topography etc. Nevertheless, the snow accumulation and spatial patterns play an important role in the hydrological cycle. It releases moisture during the dry spring period before the onset of the monsoon season. Widely used MODIS snow cover products have been available globally since 2002. The understanding of the temporal and spatial distribution of snow cover in a given region calls for a comprehensive data representation method. In this paper a method to visualize both spatial and temporal aspects of snow cover distribution from MODIS 8-day composite data is presented. It is based on RGB display of the snow cover data which is grouped according to season. The RGB syntheses of snow cover distribution (RSD) were generated for the Nam Co Basin in the central part of the Tibetan Plateau during the years of 2002–2009. An alternating pattern of monsoon and autumn snow cover was identified in the western part of the basin which corresponds to the biennial character of the variations of the Indian monsoon. Monsoon snow cover was found in RSD images for the years 2002, 2004 and 2008 whereas in years 2003 and 2009 the autumn snow cover is dominant. The eastern part of the basin does not follow this general pattern since it is affected by the so called “lake effect”, which is a snow fall induced by the passing of dry and cold westerlies over the lake surface during the winter months. The years 2002, 2006 and 2007 were identified as years with a particularly strong lake effect from the RSD images. Areas with permanent snow cover and areas that were snow free were both found to be relatively stable. Comparison of the lake effect at Nam Co with nearby Siling Co, where the lake effect is smaller or absent, suggests that the presence of an effective barrier on the opposite side of the lake is a prerequisite for the occurrence of the strong lake effect.
Man-Machine Interface System for Neuromuscular Training and Evaluation Based on EMG and MMG Signals
Authors: De la Rosa Ramon , Alonso Alonso , Carrera Albano , Durán Ramon , Fernández Patricia
Published: December 2010

This paper presents the UVa-NTS (University of Valladolid Neuromuscular Training System), a multifunction and portable Neuromuscular Training System. The UVa-NTS is designed to analyze the voluntary control of severe neuromotor handicapped patients, their interactive response, and their adaptation to neuromuscular interface systems, such as neural prostheses or domotic applications. Thus, it is an excellent tool to evaluate the residual muscle capabilities in the handicapped. The UVa-NTS is composed of a custom signal conditioning front-end and a computer. The front-end electronics is described thoroughly as well as the overall features of the custom software implementation. The software system is composed of a set of graphical training tools and a processing core. The UVa-NTS works with two classes of neuromuscular signals: the classic myoelectric signals (MES) and, as a novelty, the myomechanic signals (MMS). In order to evaluate the performance of the processing core, a complete analysis has been done to classify its efficiency and to check that it fulfils with the real-time constraints. Tests were performed both with healthy and selected impaired subjects. The adaptation was achieved rapidly, applying a predefined protocol for the UVa-NTS set of training tools. Fine voluntary control was demonstrated to be reached with the myoelectric signals. And the UVa-NTS demonstrated to provide a satisfactory voluntary control when applying the myomechanic signals.
Cardiac Cell Generation from Encapsulated Embryonic Stem Cells in Static and Scalable Culture Systems
Authors: Jing Donghui , Parikh Abhirath , Tzanakakis Emmanuel S.
Published: December 2010

Heart diseases are major causes of morbidity and mortality linked to extensive loss of cardiac cells. Embryonic stem cells (ESCs) give rise to cardiomyocyte-like cells, which may be used in heart cell replacement therapies. Most cardiogenic differentiation protocols involve the culture of ESCs as embryoid bodies (EBs). Stirred-suspension bioreactor cultures of ESC aggregates may be employed for scaling up the production of cardiomyocyte progeny but the wide range of EB sizes and the unknown effects of the hydrodynamic environment on differentiating EBs are some of the major challenges in tightly controlling the differentiation outcome. Here, we explored the cardiogenic potential of mouse ESCs (mESCs) and human ESCs (hESCs) encapsulated in poly-l-lysine (pLL)-coated alginate capsules. Liquefaction of the capsule core led to the formation of single ESC aggregates within each bead and their average size depended on the concentration of seeded ESCs. Encapsulated mESCs were directed along cardiomyogenic lineages in dishes under serum-free conditions with the addition of bone morphogenetic protein 4 (BMP4). Human ESCs in pLL-layered liquid core (LC) alginate beads were also differentiated towards heart cells in serum-containing media. Besides the robust cell proliferation, higher fractions of cells expressing cardiac markers were detected in ESCs encapsulated in LC than in solid beads. Furthermore, we demonstrated for the first time that ESCs encapsulated in pLL-layered LC alginate beads can be coaxed towards heart cells in stirred-suspension bioreactors. Encapsulated ESCs yielded higher fractions of Nkx2.5- and GATA4-positive cells in the bioreactor compared to dish cultures. Differentiated cells formed beating foci that responded to chronotropic agents in an organotypic manner. Our findings warrant further development and implementation of microencapsulation technologies in conjunction with bioreactor cultivation to enable the production of stem cell-derived cardiac cells appropriate for clinical therapies and applications.
Liposomal Formulations of Thrombomodulin Increase Engraftment after Intraportal Islet Transplantation
Authors: Cui Wanxing , Angsana Julianty , Wen Jing , Chaikof Elliot L.
Published: December 2010

Early destruction of donor islet grafts due to an instant blood-mediated inflammatory reaction (IBMIR) remains a major obstacle in islet transplantation. Thrombomodulin plays an important role in limiting coagulation and inflammatory events through a variety of effects. In this study, we investigated the ability of thrombomodulin (TM), when reconstituted as a liposomal formulation, to enhance early syngeneic islet engraftment by minimizing or abrogating the IBMIR. Administration of TM significantly improved early engraftment of syngeneic islets after intraportal transplantation in diabetic mice. In the absence of treatment, conversion to euglycemia was observed among 46.6% (7/15) of recipients. In contrast, administration of TM led to euglycemia in 93.3% (14/15) of recipients ( p = 0.0142). Recipients that received TM exhibited a lower incidence of primary nonfunction and better glucose control over a 30-day period after transplantation. Fibrin deposition ( p < 0.05), neutrophil infiltration ( p < 0.05), expression of TNF-α and IL-β mRNA ( p < 0.05), as well as NF-κB activity ( p < 0.05) were significantly reduced in the liver of islet recipients having been treated with liposomal TM. These data demonstrate that TM significantly improves early syngeneic islet engraftment through effects that target both coagulation and inflammatory pathways.
Evaluation of 28 Human Embryonic Stem Cell Lines for Use as Unrelated Donors in Stem Cell Therapy: Implications of HLA and ABO Genotypes
Authors: Lee Jeoung Eun , Kang Myung Seo , Park Myoung Hee , Shim Sung Han , Yoon Tae Ki , Chung Hyung Min , Lee Dong Ryul
Published: December 2010

For human embryonic stem cells (hESCs) to be used clinically, it is imperative that immune responses evoked by hESCs and their derivates after transplantation should be prevented. Human leukocyte antigens (HLA) and ABO blood group antigens are important histocompatibility factors in graft rejection. HLA matching between recipient and unrelated donors, in particular, is important in improving outcomes in hematopoietic cell transplantation (HCT). We have established and successfully maintained 29 hESC lines and analyzed the HLA and ABO genotypes of these lines. HLA-A, -B, -C and -DR (DRB1) genotyping was performed by polymerase chain reaction (PCR) sequence-based typing and ABO genotyping was carried out by PCR restriction fragment length polymorphism methods. To determine what proportion of the Korean population would be covered by these cell lines in organ transplantation, 27 cell lines with HLA-A, -B, and -DR data were evaluated for HCT (cord blood) donors and 28 cell lines with HLA-DR and ABO data were evaluated for solid organ (kidney) transplantation donors, and then compared the data with those from 6,740 donated cord bloods. When 2 HLA mismatches are allowed for HCT, as currently accepted for cord blood transplantation, it was estimated that about 16% and 25% of the possible recipients can find one or more donor cell lines with ≤2 mismatches at A, B, DRB1 allele level and at A, B antigen/DRB1 allele level, respectively. When HLA-DR antigen level matching and ABO compatibility was considered for solid organ (kidney) transplantation, it was estimated that about 29% and 96% of the possible recipients can find one or more ABO-compatible donor cell lines with 0 and 1 DR mismatches, respectively. We provided the first report on the HLA and ABO genotypes of hESC lines, and estimated the degree of HLA and ABO matching in organ transplantation for the Korean population.
Evaluation of Alginate Microspheres for Mesenchymal Stem Cell Engraftment on Solid Organ
Authors: Trouche E. , Fullana S. Girod , Mias C. , Ceccaldi C. , Tortosa F. , Seguelas M. H. , Calise D. , Parini A. , Cussac D. , Sallerin B.
Published: December 2010

Mesenchymal stem cells (MSCs) may be used as a cell source for cell therapy of solid organs due to their differentiation potential and paracrine effect. Nevertheless, optimization of MSC-based therapy needs to develop alternative strategies to improve cell administration and efficiency. One option is the use of alginate microencapsulation, which presents an excellent biocompatibility and an in vivo stability. As MSCs are hypoimmunogenic, it was conceivable to produce microparticles with [alginate-poly-l-lysine-alginate (APA) microcapsules] or without (alginate microspheres) a surrounding protective membrane. Therefore, the aim of this study was to determine the most suitable microparticles to encapsulate MSCs for engraftment on solid organ. First, we compared the two types of microparticles with 4 × 106 MSCs/ml of alginate. Results showed that each microparticle has distinct morphology and mechanical resistance but both remained stable over time. However, as MSCs exhibited a better viability in microspheres than in microcapsules, the study was pursued with microspheres. We demonstrated that viable MSCs were still able to produce the paracrine factor bFGF and did not present any chondrogenic or osteogenic differentiation, processes sometimes reported with the use of polymers. We then proved that microspheres could be implanted under the renal capsule without degradation with time or inducing impairment of renal function. In conclusion, these microspheres behave as an implantable scaffold whose biological and functional properties could be adapted to fit with clinical applications.
N-Acetylcysteine Improves the Viability of Human Hepatocytes Isolated from Severely Steatotic Donor Liver Tissue
Authors: Sagias Filippos G. , Mitry Ragai R. , Hughes Robin D. , Lehec Sharon C. , Patel Ameet G. , Rela Mohamed , Mieli-Vergani Giorgina , Heaton Nigel D. , Dhawan Anil
Published: December 2010

Hepatocyte transplantation is dependent on the availability of good quality human hepatocytes isolated from donor liver tissue. Hepatocytes obtained from livers rejected for transplantation on the grounds of steatosis are often of low viability and not suitable for clinical use. The aim of this study was to evaluate the effects of the antioxidant N-acetylcysteine (NAC) on the function of hepatocytes isolated from steatotic donor livers. Human hepatocytes were isolated from 10 severely steatotic (>60%) donor livers rejected for transplantation. The left lateral segment of the donor liver was dissected into two equal size pieces and randomized to NAC or control. NAC (5 mM) was added to the first perfusion buffer of the standard collagenase digestion technique. Cells from tissues perfused with NAC had a significantly higher mean viability (81.1 ± 1.7% vs. 66.0 ± 4.7%; p = 0.003) and cell attachment (1.08 ± 0.26 vs. 0.67 ± 0.18 OD units; p = 0.012). Addition of NAC during isolation of human hepatocytes from steatotic donor liver tissue significantly improved the outcome of cell isolation. Further studies are needed to investigate the mechanism(s) of this effect. Incorporation of NAC in the hepatocyte isolation protocol could increase the availability of hepatocytes for transplantation.
Antiproinflammatory Effects of Iodixanol (OptiPrep)-Based Density Gradient Purification on Human Islet Preparations
Authors: Mita A. , Ricordi C. , Messinger S. , Miki A. , Misawa R. , Barker S. , Molano R. D. , Haertter R. , Khan A. , Miyagawa S. , Pileggi A. , Inverardi L. , Alejandro R. , Hering B. J. , Ichii H.
Published: December 2010

Islet isolation and purification using a continuous density gradient may reduce the volume of tissue necessary for implantation into patients, therefore minimizing the risks associated with intraportal infusion in islet transplantation. On the other hand, the purification procedure might result in a decreased number of islets recovered due to various stresses such as exposure to cytokine/chemokine. While a Ficoll-based density gradient has been widely used in purification for clinical trials, purification with iodixanol (OptiPrep) has been recently reported in islet transplant series with successful clinical outcomes. The aim of the current study was to compare the effects of the purification method using OptiPrep-based and Ficoll-based density gradients. Human islet isolations were performed using a modified automated method. After the digestion phase, prepurification digests were divided into two groups and purified using a semiautomated cell processor with either a continuous Ficoll- or OptiPrep-based density gradient. The quantity, purity, viability, and cellular composition of islet preparations from each group were assessed. Cytokine/chemokine and tissue factor production from islet preparations after 48-h culture were also measured. Although islet purity, postpurification IEQ, islet recovery rate, FDA/PI, and fractional β-cell viability were comparable, β-cell mass after 48-h culture significantly improved in the OptiPrep group when compared to the Ficoll group. The production of cytokine/chemokine including IL-1β, TNF-α, IFN-γ, IL-6, IL-8, MIP-1β, MCP-1, and RANTES but not tissue factor from the OptiPrep group was significantly lower during 48-h culture after isolation. Each preparation contained the similar number of ductal cells and macrophages. Endotoxin level in both gradient medium was also comparable. The purification method using OptiPrep gradient media significantly reduced cytokine/chemokine production but not tissue factor from human islet preparations and improved β-cell survival during pretransplant culture. Our results suggest that the purification method using OptiPrep gradient media may be of assistance in increasing successful islet transplantation.
Delivery of a Therapeutic Protein by Immune-Privileged Sertoli Cells
Authors: Halley Katelyn , Dyson Emily L. , Kaur Gurvinder , Mital Payal , Uong Peter M. , Dass Brinda , Crowell Sherry N. , Dufour Jannette M.
Published: December 2010

Immune-privileged Sertoli cells survive long term after allogeneic or xenogeneic transplantation without the use of immunosuppressive drugs, suggesting they could be used as a vehicle to deliver therapeutic proteins. As a model to test this, we engineered Sertoli cells to transiently produce basal levels of insulin and then examined their ability to lower blood glucose levels after transplantation into diabetic SCID mice. Mouse and porcine Sertoli cells transduced with a recombinant adenoviral vector containing furin-modified human proinsulin cDNA expressed insulin mRNA and secreted insulin protein. Transplantation of 5–20 million insulin-expressing porcine Sertoli cells into diabetic SCID mice significantly decreased blood glucose levels in a dose-dependent manner, with 20 million Sertoli cells decreasing blood glucose levels to 9.8 ± 2.7 mM. Similar results were obtained when 20 million insulin-positive, BALB/c mouse Sertoli cells were transplanted; blood glucose levels dropped to 6.3 ± 2.4 mM and remained significantly lower for 5 days. To our knowledge, this is the first study to demonstrate Sertoli cells can be engineered to produce and secrete a clinically relevant factor that has a therapeutic effect, thus supporting the concept of using immune-privileged Sertoli cells as a potential vehicle for gene therapy.
Human Cord Blood-Derived Endothelial Progenitor Cells and Their Conditioned Media Exhibit Therapeutic Equivalence for Diabetic Wound Healing
Authors: Kim Ji Yeon , Song Sun-Hwa , Kim Koung Li , Ko Jeong-Jae , Im Ji-Eun , Yie Se Won , Ahn Young Keun , Kim Duk-Kyung , Suh Wonhee
Published: December 2010

Transplantation of human cord blood-derived endothelial progenitor cells (EPCs) is reported to contribute to neovascularization in various ischemic diseases. However, the possible beneficial role and underlying mechanisms in diabetes-impaired wound healing have been less well characterized. In this study, EPC transplantation stimulated keratinocyte and fibroblast proliferation substantially as early as 3 days after injury, leading to significantly accelerated wound closure in streptozotocin-induced diabetic nude mice, compared to PBS control. RT-PCR analysis showed that EPCs secreted various wound healing-related growth factors. Among them, keratinocyte growth factor and platelet-derived growth factor were highly expressed in the EPCs and were present at substantial levels in the EPC-injected dermal tissue. Using EPC-conditioned medium (CM), we found that paracrine factors from EPCs directly exerted mitogenic and chemotactic effects on keratinocytes and fibroblasts. Moreover, injection of EPC-CM alone into the same diabetic wound mice promoted wound healing and increased neovascularization to a similar extent as achieved with EPC transplantation. These results indicate that the beneficial effect of EPC transplantation on diabetic wounds was mainly achieved by their direct paracrine action on keratinocytes, fibroblasts, and endothelial cells, rather than through their physical engraftment into host tissues (vasculogenesis). In addition, EPC-CM was shown to be therapeutically equivalent to EPCs, at least for the treatment of diabetic dermal wounds, suggesting that conditioned medium may serve as a novel therapeutic option that is free from allograft-associated immune rejection concern.