bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvements of Techniques to Estimate Migration Rates: An Application with Brazilian Censuses Data
Authors: Amaral Ernesto Friedrich de Lima
Published: November 2008

This paper intends to develop procedures which can be applied to different countries and databases to estimate migration rates using information on place of previous residence (last-move data) and duration of residence. For this, some modifications are proposed to previous methods, in order to improve the measurement of migration rates. Other estimations were calculated with information on place of residence at some fixed date in the past. Results suggest that estimations with improved techniques using last-move data give similar results to those ones provided by techniques based on place of residence from a specified number of years preceding the Census enumeration. As a demonstration, 1970, 1980, 1991 and 2000 Brazilian Censuses are used to estimate both sets of rates.
Human Capital Differentials across Municipalities and States in Brazil
Authors: Queiroz Bernardo L. , Golgher André B.
Published: November 2008

In this paper, we investigate the distribution of more educated and skilled people in Brazilian municipalities and states. Previous evidence shows a high concentration of college educated and high skilled workers in some areas of the country. We investigate whether the increase in the number of high skill workers is faster in municipalities with high initial levels of human capital than in municipalities with lower initial levels. We develop a theoretical model to explain the convergence/divergence of regional skill levels In Brazil. We estimate OLS models based on the theoretical model to explain empirically wage differentials in Brazil. Last, we compute standard segregation and isolation measures to show the trends in the distribution of skilled workers across states and cities in Brazil. We find that educated and qualified workers are concentrated in some areas of the country and recent decades show a higher concentration of them across states and cities.
Uniaxial Tension Tests on Cement-Stabilized Granular Materials
Authors: Kolias S , Williams RIT
Published: December 2008

This paper presents details of tests to evaluate the suitability of a double scissor friction grip system, initially developed for conventional concrete, for determining uniaxial tensile strength of cement-stabilized granular materials suitable for use in roadbase construction. The system is examined in terms of the variability of the results, the significance of fracture location, and the distribution of strain, and is judged to show promise. Test results on a cement-stabilized gravel, typical of roadbase materials used in the United Kingdom, are given, including the stress-strain characteristics in tension, the moduli of elasticity in tension and compression, and the strengths in tension, compression, and flexure.
Minding Our Manors: Lithuanian Heritage at Risk
Authors: Bucas Jurgis , Grazuleviciute-Vileniske Indre , Medisauskiene Zita , Vitkuviene Jurga
Published: December 2008

The article presents an analysis of the present state of and prospects for preserving Lithuanian manor residences. It describes the general state of historic preservation in Lithuania and surveys the history of Lithuanian manors from their initial construction until the present, revealing the impacts of political, social, and landscape changes to this heritage. The nation's turbulent history, its repeated occupations, agrarian reforms, and changes to the landscape resulted in distinctly individual Lithuanian manor residences. Because of the nation's difficult history, preservation of this heritage has been fraught with problems. However, due to a dramatic shift in country's political situation over the past sixteen years, scholars have increasingly focused on Lithuanian cultural identity, and their growing interest raises hope that this distinctive heritage will be preserved.
Systematic Identification of Gene Activities Promoting Hypoxic Death
Authors: Mabon Meghann E , Mao Xianrong , Jiao York , Scott Barbara A , Crowder C Michael
Published: December 2008

The sensitivity of an organism to hypoxic injury varies widely across species and among cell types. However, a systematic description of the determinants of metazoan hypoxic sensitivity is lacking. Toward this end, we screened a whole-genome RNAi library for genes that promote hypoxic sensitivity in Caenorhabditis elegans. RNAi knockdown of 198 genes conferred an invariant hypoxia-resistant phenotype (Hyp-r). Eighty-six per cent of these hyp genes had strong homologs in other organisms, 73 with human reciprocal orthologs. The hyp genes were distributed among multiple functional categories. Transcription factors, chromatin modifying enzymes, and intracellular signaling proteins were highly represented. RNAi knockdown of about half of the genes produced no apparent deleterious phenotypes. The hyp genes had significant overlap with previously identified life span extending genes. Testing of the RNAi's in a mutant background defective in somatic RNAi machinery showed that most genes function in somatic cells to control hypoxic sensitivity. DNA microarray analysis identified a subset of the hyp genes that may be hypoxia regulated. siRNA knockdown of human orthologs of the hyp genes conferred hypoxia resistance to transformed human cells for 40% of the genes tested, indicating extensive evolutionary conservation of the hypoxic regulatory activities. The results of the screen provide the first systematic picture of the genetic determinants of hypoxic sensitivity. The number and diversity of genes indicates a surprisingly nonredundant genetic network promoting hypoxic sensitivity.
Obesity in paleolithic era, as portrayed on sculptures
Authors: Józsa László
Published: November 2008

Száz őskőkori szobrocska közül kilencvenhét nőket ábrázol. A női idolok 57,3%-án elhízás állapítható meg. A paleolitikus figurák elemzésével a szerző megkísérli rekonstruálni a készítési módokat, a valószínűsíthető testtömeget és megállapítani a szobrocskákon látható kóros eltéréseket.
Successful epicardial ablation of a postinfarction ventricular tachycardia
Authors: Gellér László , Szilágyi Szabolcs , Zima Endre , Srej Marianna , Szűcs Gábor , Molnár Levente , Merkely Béla
Published: November 2008

Az 55 éves posztinfarktusos, öt évvel korábban gyors monomorf kamrai tachycardia miatt implantálható cardioverter defibrillátor (ICD) implantációján átesett betegnél gyakori, többször csak ICD-sokkra szűnő, 150/perc frekvenciájú monomorf kamrai tachycardia miatt endocardialis rádiófrekvenciás katéterablatiót végeztünk 2005 februárjában. Két hónapos ritmuszavar-mentesség után a korábbinál lassabb, 120/perces, de incessant kamrai tachycardia lépett fel, amelyet újabb endocardialis ablatióval nem tudtunk megszüntetni. Tartós sinusrhythmust elérni kombinált antiarrhythmiás gyógyszeres kezeléssel sem sikerült. 2005 júniusában ismételten sikertelen endocardialis ablatio után ultimum refugiumként epicardialis ablatio mellett döntöttünk. Subxyphoidealis percutan pericardialis punkciót végeztünk, majd az ablatiós katétert a pericardialis térbe vezettük fel, és a legkorábbi aktiváció helyén ablálva a másfél hónapja gyakorlatilag folyamatosan fennálló ritmuszavar 5 másodperc után megszűnt. További három ablatiót követően programozott kamrai extrastimulációval kamrai tachyarrhythmia nem volt indukálható. A hároméves utánkövetés alatt kamrai tachycardia kétszer lépett fel, az ICD mindkét ritmuszavart az első antitachycardia-ingerléssel megszüntette. A beteg NYHA II. stádiumban van. Esetismertetésünkben tudomásunk szerint hazánkban elsőként számolunk be posztinfarktusos incessant kamrai tachycardia sikeres epicardialis ablatiójáról.
Psychologists working as members of the intensive care team could reduce the length of stay
Authors: K. Szilágyi Adrienn , Diószeghy Csaba , Varga Katalin
Published: November 2008

A lélegeztetett betegek sorsának kimenetele hosszú és rövid távon is függ az intenzív osztályon és a lélegeztetőgépen töltött időtől. Az intenzív osztályos kezelést túlélt betegek egészséghez kötött életminősége bizonyítottan összefügg az intenzíves kezelés fizikai és pszichés hatásaival. Előző multicentrikus randomizált vizsgálatunkban bemutattuk az intenzíves kezeléssel egy időben adott pszichés támogatás hatását.
Célkitűzés:
A jelen post hoc analízis célja, hogy bemutassa a pszichés támogatás hatását, amikor azt folytonosan ugyanaz, a teamhez tartozó terapeuta biztosítja.
Módszer:
A post hoc analízisbe 36 beteg került: 17 a kontroll-, 19 a vizsgálati csoportba. A vizsgálati csoport naponta részesült pozitív szuggesztiókon alapuló pszichés támogatásban, amelyet a kezelés minimum 50%-ában ugyanaz a terapeuta végzett. A kontrollcsoport ugyanazt a kezelést kapta, a pszichológus bevonása nélkül. A két csoport között nem volt különbség korban, nemben, SAPSII-pontokban és az orvosi alapellátásban.
Eredmények:
Az eredmények szignifikánsan rövidebb gépi lélegeztetést (3,6 nap,
p
< 0,014) és osztályon tartózkodást (4,2 nap,
p
< 0,022) mutattak a vizsgálati csoport esetében.
Következtetések:
Ezek az eredmények igazolják az intenzív osztályos team teljes tagjaként alkalmazott pszichológus értékét és annak fontosságát, hogy gondoskodjunk a betegek pszichés támogatásáról.
Invasive endoscopy or surgery for pancreatic disorders?
Authors: Pap Ákos
Published: November 2008

Az endoszkópos kettős papillotomia már évekkel ezelőtt elfoglalta a sebészi transduodenalis papillaplasztika helyét a papilla betegségeiben és krónikus pancreatitisben. A pseudocysták endoszkópos szájaztatása is helyettesítheti a korábban egyeduralkodó sebészi módszereket még az akut pancreatitis nekrotizáló formáiban kialakuló „walled of necrosis” esetében is, akár fertőzött, akár steril folyadékgyülemről van szó. Krónikus pancreatitisben az endoterápia első beavatkozásként ajánlott a gyakran jobb késői fájdalommentességet eredményező sebészi eljárások előtt. A kőtörés, kőoldás vagy -extrakció és a többszörös pancreasstentek, lehetőleg agresszív ballonos tágítás nélkül, fokozatosan kalibrálják a domináns vezeték szűkületét berepedés, ischaemia és oldalági obstrukció nélkül. A recidívamentes periódus megnyúlik (stent nélkül is) az alkoholfogyasztás és a dohányzás teljes elhagyása esetén. Jól kontrollált, randomizált vizsgálat szükséges a többszörös pancreasstentek klinikai előnyének bizonyítására a sebészi technikákkal szemben.
Antiangiogenic therapy for gastrointestinal tumors
Authors: Lakatos Gábor , Tulassay Zsolt
Published: November 2008

Az érképződés fontos szerepet játszik számos betegség kialakulásában. A vascularis endothelnövekedési faktor központi fontosságú az élettani és a kóros érképződés folyamatában. A VEGF fokozott expressziója összefügg a daganatos érképződéssel, az áttétek kialakulásával és a tumorsejtek proliferációjával. A humán monoklonális anti-VEGF-antitest (bevacizumab) a hagyományos kemoterápia kiegészítéseként alkalmazva jó hatású lehet különböző daganatok kezelésében. Egyre több adat igazolja, hogy a bevacizumab javítja a betegek életkilátásait áttétet adó colorectalis carcinomában és előrehaladott hepatocellularis carcinomában. További vizsgálatok szükségesek az érképzést gátló kezelés hatékonyságának megítélésére egyéb tápcsatorna-daganatokban. Közleményünkben az emésztőszervi daganatok kezelésében alkalmazott, érképzést gátló készítményekkel kapcsolatos újabb eredményeket foglaljuk össze.
SWI/SNF-Brg1 Regulates Self-Renewal and Occupies Core Pluripotency-Related Genes in Embryonic Stem Cells
Authors: Kidder Benjamin L. , Palmer Stephen , Knott Jason G.
Published: December 2008

The SWI/SNF-Brg1 chromatin remodeling protein plays critical roles in cell-cycle control and differentiation through regulation of gene expression. Loss of Brg1 in mice results in early embryonic lethality, and recent studies have implicated a role for Brg1 in somatic stem cell self-renewal and differentiation. However, little is known about Brg1 function in preimplantation embryos and embryonic stem (ES) cells. Here we report that Brg1 is required for ES cell self-renewal and pluripotency. RNA interference-mediated knockdown of Brg1 in blastocysts caused aberrant expression of Oct4 and Nanog. In ES cells, knockdown of Brg1 resulted in phenotypic changes indicative of differentiation, downregulation of self-renewal and pluripotency genes (e.g., Oct4, Sox2, Sall4, Rest), and upregulation of differentiation genes. Using genome-wide promoter analysis (chromatin immunoprecipitation) we found that Brg1 occupied the promoters of key pluripotency-related genes, including Oct4, Sox2, Nanog, Sall4, Rest, and Polycomb group (PcG) proteins. Moreover, Brg1 co-occupied a subset of Oct4, Sox2, Nanog, and PcG protein target genes. These results demonstrate an important role for Brg1 in regulating self-renewal and pluripotency in ES cells.
Pluripotin Combined with Leukemia Inhibitory Factor Greatly Promotes the Derivation of Embryonic Stem Cell Lines from Refractory Strains
Authors: Yang Weifeng , Wei Wei , Shi Cheng , Zhu Jinliang , Ying Wenqin , Shen Yan , Ye Xin , Fang Lingling , Duo Shuguang , Che Jie , Shen Huan , Ding Sheng , Deng Hongkui
Published: December 2008

Most mouse embryonic stem (ES) cells are derived from a 129 or C57BL/6 background, whereas the derivation efficiency of ES cells is extremely low on certain refractory types of background for which ES cells are highly desired. Here we report an optimized, highly efficient protocol by combining pluripotin, a small molecule, and leukemia inhibitory factor (LIF) for the derivation of mouse ES cells. With this method, we successfully isolated ES cell lines from five strains of mice, with an efficiency of 57% for NOD-scid, 63% for SCID beige, 80% for CD-1, and 100% for two F1 strains from C57BL/6×CD-1. By tracking the Oct4-positive cells in the Oct4-green fluorescent protein embryos in the process of ES cell isolation, we found that pluripotin combined with LIF improved the efficiency of ES cell isolation by selectively maintaining the Oct4-positive cells in the outgrowth. To our knowledge, this is the first report of ES cells being efficiently derived from immunodeficient mice on refractory backgrounds (NOD-scid on a NOD background and SCID beige on a BALB/c background).
Cancer and Immune Response: Old and New Evidence for Future Challenges
Authors: de la Cruz-Merino Luis , Grande-Pulido Enrique , Albero-Tamarit Ana , Codes-Manuel de Villena Manuel Eduardo
Published: December 2008

Learning Objectives

After completing this course, the reader should be able to: Discuss the current scientific background of immunotherapy applied to cancer treatment.Suggest lines of future investigation in the immunotherapy field.Explain the rationale for developing and discuss the current status of new immunotherapeutic approaches in solid tumors.

CME This article is available for continuing medical education credit at http://CME.TheOncologist.com

Cancer may occur as a result of abnormal host immune system tolerance. Recent studies have confirmed the occurrence of spontaneous and induced antitumor immune responses expressed as the presence of tumor-infiltrating T cells in the tumor microenvironment in some cancer models. This finding has been recognized as a good prognostic factor in several types of tumors. Some chemotherapy agents, such as anthracyclines and gemcitabine, are effective boosters of the immune response through tumor-specific antigen overexpression after apoptotic tumor cell destruction. Other strategies, such as GM-CSF or interleukin-2, are pursued to increase immune cell availability in the tumor vicinity, and thus improve both antigen presentation and T-cell activation and proliferation. In addition, cytotoxic T lymphocyte antigen 4–blocking monoclonal antibodies enhance immune activity by prolonging T-cell activation. Strategies to stimulate the dormant immune system against tumors are varied and warrant further investigation of their applications to cancer therapy in the future.
Oral Health of Early Head Start Children: A Qualitative Study of Staff, Parents, and Pregnant Women
Authors: Mofidi Mahyar , Zeldin Leslie P. , Rozier R. Gary
Published: December 2008

Objectives.We explored the oral health knowledge, attitudes, and activities of Early Head Start (EHS) staff members, parents, and pregnant women, along with their suggestions related to future oral health educational interventions targeting EHS children.

Methods. Nine focus groups were conducted with EHS staff, parents, and pregnant women. Audiotapes of sessions were transcribed and entered into ATLAS.ti 5.0 for coding and analysis.

Results. Attitudes about the importance of children's oral health among parents and pregnant women were mixed. Staff members voiced responsibility for children's oral health but frustration in their inability to communicate effectively with parents. Parents in turn perceived staff criticism regarding how they cared for their children's oral health. Gaps were noted in the oral health activities of EHS programs. Participants expressed confusion regarding the application of Head Start oral health performance standards to EHS. The need for culturally sensitive, hands-on oral health education was highlighted.

Conclusions. Tailored, theory-based interventions are needed to improve communication between EHS staff and families. Clear policies on the application of Head Start oral health performance standards to EHS are warranted. Educational activities should address the needs and suggestions of EHS participants.
Using Community Arts Events to Enhance Collective Efficacy and Community Engagement toAddress Depression in an African American Community
Authors: Chung Bowen , Jones Loretta , Jones Andrea , Corbett Charles E. , Booker Theodore , Wells Kenneth B. , Collins Barry
Published: December 2008

Objectives. We used community-partnered participatory research (CPPR) to measure collective efficacy and its role as a precursor of community engagement to improve depression care in the African American community of South Los Angeles.

Methods. We collected survey data from participants at arts events sponsored by a CPPR workgroup. Both exploratory (photography exhibit; n = 747) and confirmatory (spoken word presentations; n = 104) structural equation models were developed to examine how knowledge and attitudes toward depression influenced community engagement.

Results. In all models, collective efficacy to improve depression care independently predicted community engagement in terms of addressing depression (B = 0.64–0.97; P < .001). Social stigma was not significantly associated with collective efficacy or community engagement. In confirmatory analyses, exposure to spoken word presentations and previous exposure to CPPR initiatives increased perceived collective efficacy to improve depression care (B = 0.19–0.24; P < .05).

Conclusions. Enhancing collective efficacy to improve depression care may be a key component of increasing community engagement to address depression. CPPR events may also increase collective efficacy. Both collective efficacy and community engagement are relevant constructs in the South Los Angeles African American community.
Violence During Pregnancy Among Women With or at Risk for HIV Infection
Authors: Koenig Linda J. , Whitaker Daniel J. , Royce Rachel A. , Wilson Tracey E. , Callahan Michelle R. , Fernandez M. Isabel
Published: December 2008

Objectives. This study estimated the prevalence of violence during pregnancy in relation to HIV infection.

Methods. Violence, current partnerships, and HIV risk behaviors were assessed among 336 HIV-seropositive and 298 HIV-seronegative at-risk pregnant women.

Results. Overall, 8.9% of women experienced recent violence; 21.5% currently had abusive partners. Violence was experienced by women in all partnership categories (range = 3.8% with nonabusive partners to 53.6% with physically abusive partners). Neither experiencing violence nor having an abusive partner differed by serostatus. Receiving an HIV diagnosis prenatally did not increase risk. Disclosure-related violence occurred, but was rare.

Conclusions. Many HIV-infected pregnant women experience violence, but it is not typically attributable to their serostatus. Prenatal services should incorporate screening and counseling for all women at risk for violence. (Am J Public Health. 2002;92:367–370)
Chronic Illness Among Poor Children Enrolled in the Temporary Assistance for Needy Families Program
Authors: Wise Paul H. , Wampler Nina S. , Chavkin Wendy , Romero Diana
Published: December 2008

Objectives. This study assessed chronic child illness among recipients of Temporary Assistance for Needy Families (TANF) benefits and poor families not receiving benefits.

Methods. Data from the 1998 National Health Interview Survey were used to examine chronic child illness, enrollment in TANF, health insurance status, and selected access indicators.

Results. One quarter of TANF-enrolled children had chronic illnesses. Unenrolled children were 3 times as likely as TANF-enrolled children to be uninsured. Among the chronically ill, 31.7% of unenrolled and 14.3% of enrolled children experienced gaps in insurance coverage that were associated with access barriers.

Conclusions. Welfare policies should consider the effects of chronic illness and gaps in insurance coverage on the health of poor children.
Mycotoxin Detection Plays “Cops and Robbers”: Cyclodextrin Chemosensors as Specialized Police?
Authors: Cozzini Pietro , Ingletto Gianluigi , Singh Ratna , Dall’Asta Chiara
Published: December 2008

As in a cops and robbers play we discover new mycotoxins and metabolites everyday and we are forced to develop new molecules quickly as chemo- or biosensors or to modify existing molecules able to recognize these new hazardous compounds. This will result in an enormous cost saving to agro-food industry through the prevention and reduction of product recalls and reduced treatment costs. Here we present a brief review of the rapid methods used to detect mycotoxins, considering usefulness and limits. Then we propose a new fast, efficient and cheap methodology, based on a combination of computer chemistry aided design and fluorescence, that can help to drive synthesis in a more efficient way.
Synthesis and characterization of monomer‐casting polyamide 6/polymethacrylic ionomer blends
Authors: Wu Tongfei , Yang Guisheng
Published: December 2008

Monomer‐casting polyamide 6 (MCPA6)/polymethacrylic ionomer blends were synthesized by the in situ anionic ring‐opening polymerization of ϵ‐caprolactam. The polymethacrylic ionomer used in this study was a copolymer of methyl methacrylate and sodium or zinc methacrylate. Because the polymethacrylic ionomer strongly interacted with polyamide 6 (PA6) chains, it influenced the alignment of the polyamide chains. The change in the degree of the order of hydrogen bonding in MCPA6 caused by the addition of the polymethacrylic ionomer was studied with Fourier transform infrared. The change in the interaction between PA6 chains was studied with rheological measurements. The influence of the polymethacrylic ionomer on the crystallization behavior of MCPA6 was also studied with differential scanning calorimetry. The isothermal crystallization and subsequent melting behavior were investigated at the designated temperature. The commonly used Avrami equation was used to fit the primary stage of the isothermal crystallization. The Avrami exponent (n) values were evaluated to be 2 < n < 3 for the neat MCPA6 and MCPA6/polymethacrylic ionomer blends. The polymethacrylic ionomer, acting as a stumbling‐block agent in the blends, decelerated the crystallization rate with the half‐time of crystallization increasing. The polymethacrylic ionomer made the molecular chains of MCPA6 more difficult to crystallize during the isothermal crystallization process. More less perfect crystals formed in the MCPA6/polymethacrylic ionomer blends because of the interaction between the MCPA6 molecular chains and polymethacrylic ionomer. The crystallinity of the blends was depressed by the addition of the polymethacrylic ionomer. The thermal stability was also studied with thermogravimetric analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Behavior of sulfonated poly(ether ether ketone) in ethanol–water systems
Authors: Roelofs Kimball S. , Kampa Andreas , Hirth Thomas , Schiestel Thomas
Published: December 2008

The behavior of sulfonated poly(ether ether ketone) (sPEEK) membranes in ethanol–water systems was studied for possible application in direct ethanol fuel cells (DEFCs). Polymer membranes with different degrees of sulfonation were tested by means of uptake, swelling, and ethanol transport with dynamic measurements (liquid–liquid and liquid–gas systems). Ethanol permeability was determined in an liquid–liquid diffusion cell. For membranes with an ion‐exchange capacity (IEC) between 1.15 and 1.75 mmol/g, the ethanol permeability varied between 5 × 10−8 and 1 × 10−6 cm2/s, being dependent on the measuring temperature. Ethanol and water transport in liquid–gas systems was tested with pervaporation as a function of IEC and temperature. Higher IEC accounted for higher fluxes and lower water/ethanol selectivity. The temperature had a large effect on the fluxes, but the selectivity remained constant. Furthermore, the membranes were characterized with proton conductivity measurements. The proton diffusion coefficient was calculated, and a transition in the proton transfer mechanism was found at a water number of 12. Membranes with high IEC (>1.6 mmol/g) exhibited larger proton diffusion coefficients in ethanol–water systems than in water systems. The membrane with the lowest IEC exhibited the best proton transport to ethanol permeability selectivity. The use of sPEEK membranes in DEFC systems depends on possible modifications to stabilize the membranes in the higher conductive region rather than on modifications to increase the proton conductivity in the stable region. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Dynamic Gravimetry in Studying The Adsorption of Proteins Onto Metal Surfaces: Analysis and Limitations
Authors: Sandu Constantine , Lund Daryl , Almas Karl , Walling David
Published: December 2008

The paper describes the physical and mathematical fundamentals of dynamic gravimetry in liquid phase. First, a relation is developed to calculate the apparent weight of a vertical thin cylinder partially immersed Into a liquid. It emphasizes the magnitude of buoyancy forces and surface‐tension forces (which act upon fine threads used to suspend a solid object completely immersed into a liquid). Next, the basic relation of dynamic gravimetry is derived to estimate the absolute mass of adsorbed material onto the surface of a submerged solid object. This relation encompasses, apart from the term related to the measured output signal of the balance, three correction terms which originate from the surface tension effects, buoyancy effect of the submerged object, and buoyancy effect due to the adsorbed material.

The following sections address adsorption at the air‐liquid interface as well as the molecular diffusion process (both being intermingled with concentration and density gradients in the system). Special attention is given to the errors connected with a series of relaxation processes in which the external menisci, the plate‐beam system, and the surface tension are involved once their equilibrium conditions are disturbed. The time constants of these relaxation processes can not be exactly predicted. The paper concludes with an experimental illustration of dynamic gravimetry, with the adsorption of β‐lactoglobulin onto stainless steel plates. The validity of predictions based upon the physico‐mathematical fundamentals is reconciled with the analytical and technical aspects and difficulties specific to dynamic gravimetry.
Modeling and Measurement of Yeast Flocculation
Authors: Davis Robert H. , Hunt Thomas P.
Published: December 2008

A sedimentation/light extinction technique has been developed to quantitatively measure the state of flocculation of a suspension of yeast cells. This experimental method is based upon sedimentation theory with a modified light extinction theory that accounts for the dependence of the extinction coefficient on the floc size distribution, and the loosely‐branched fractal structure of yeast aggregates. As demonstrated by comparisons with direct microscopic observations, this technique is capable of accurately determining the steady‐state of floc sizes as well as floc settling velocities of a variety of yeast cultures.
An Engineering Analysis of the Production of Xylose by Dilute Acid Hydrolysis of Hardwood Hemicellulose
Authors: Maloney Mark T. , Chapman Thomas W. , Baker Andrew J.
Published: December 2008

Numerical simulations of various reactors for the production of xylose from hardwood hemicellulose by dilute sulfuric acid hydrolysis have been developed to analyze the effects on reactor performance of heat and mass transfer as well as reaction kinetics. An economic objective function representing the incremental cost of producing a 10% xylose solution for fermentation to ethanol was calculated from the results of the reactor simulations to identify the operating conditions that minimize production costs for each reactor type. Lower production costs were estimated for percolation and continuous counter‐current reactors; the cost for xylose production in a continuous co‐current reactor is significantly higher. Production of ethanol from hardwood hemicellulose is not economical with any of the reactors considered, but the models developed here may be used to analyze other process alternatives for use of hemicellulose via production of xylose.
Deposition of Dairy Protein‐Containing Fluids on Heat Exchange Surfaces
Authors: Rakes P. A. , Swartzel K. R. , Jones V. A.
Published: December 2008

The deposition behavior of milk and dairy protein model systems under turbulent flow conditions (Re > 66,700) was observed in the heating sections of a tubular ultra‐high temperature processing unit. This phenomenon was monitored via thermal resistance of the deposit in four segments in each of two shell‐and‐tube heat exchangers. Model systems were comprised of mixtures of sodium caseinate, whey proteins, salts, lactose, and fat. Fouling rates varied with type of milk protein, heater wall temperature, and location in the heat exchangers. The relationship between deposition rate in the heat exchanger and protein denaturation kinetics was also examined.
Secretion of Heterologous Proteins from Saccharomyces Cerevisiae
Authors: Das Rathin C. , Shultz Janice L.
Published: December 2008

In recent years considerable progress has been achieved on the heterologous gene expression and protein secretion in the yeast Saccharomyces cerevisiae. The variety of natural yeast secretory signal sequences being utilized for heterologous protein secretion are reviewed. The usefulness of the yeast pheromone, α‐factor leader sequence on the secretion of foreign proteins is emphasized.
Intercompartmental Fluid Shifts in Hemodialysis Patients
Authors: Heineken F. G. , Evans M. C. , Keen M. L. , Gotch F. A.
Published: December 2008

Hemodialysis is a therapeutic procedure for replacing some functions of the natural kidney. As such, it is capable of allowing people with little or no residual kidney function to survive and in some cases to lead productive lives. There are, unfortunately, a number of side effects associated with this procedure (shock, muscle cramps, fatigue, etc.). In order to minimize these side effects, we have undertaken to model shifts of fluid between the intracellular and extracellular fluid spaces in hemodialysis patients. Fluid shifts are primarily a function of osmolality differences between these fluid spaces. Changes in osmolality are caused mainly by changes in urea and salt concentrations. Least squares analysis of patient data has been used to estimate the appropriate ultrafiltration and urea mass transfer coefficients for each patient. The model has then been used to find a dialysate sodium concentration profile that will minimize fluid shifts into and out of the intracellular fluid space.
Enhanced Nutrient Transport in Hollow Fiber Perfusion Bioreactors: A Theoretical Analysis
Authors: Schonberg Jeffrey A. , Belfort Georges
Published: December 2008

Entrapped cells (or enzyme) in hollow fiber perfusion reactors is an attractive method for producing concentrated biologicals. Inherent in densely packed‐cell masses are possible mass transfer limitations due to rate limiting transport processes resulting in loss of cell viability. To overcome this limitation, convective fluxes superimposed on diffusion have recently been proposed for entrapped animal cell perfusion bioreactors. We assessed whether radial fluid convection would enhance performance. In an asymptotic analysis using singular perturbation, we show that for large axial Peclet number, Pe−1/3 «« 1, it is permissible to ignore the mass transfer resistance in the lumen. Data from the literature appear to support this assumption. Radial convection of the feed in a shell and tube hollow fiber perfusion reactor is shown to be useful in increasing catalyst efficiency and production rates per unit volume. A series solution to the governing equation is presented assuming Darcy flow, first order kinetics, steady state transport, and irreversible reaction. The effect of convection is studied for many Thiele moduli, for each of two cases; catalyst activity being spatially uniform in one case and distributed in the second. Performance is essentially the same in each case.
Acid Fermentation in Water‐Organic Solvent Two‐Liquid Phase Systems
Authors: Bar Raphael , Gainer John L.
Published: December 2008

In search of an optimal system for extractive fermentation of an organic acid, fermentations of lactic, citric, and acetic acids were studied in a broth saturated with an organic solvent and in a broth‐organic solvent two‐liquid phase system. Among the 13 solvents tested, only long‐chain hydrocarbons, perfluorodecalin, and methyl oleate were found to be nontoxic to the cells of L. delbrueckii in two‐liquid phase systems. However, a distinction was made between toxicity due to dissolved solvent molecules and that due to a separate solvent phase. Thus, cells of L. delbrueckii, which were not inhibited in n‐dodecanol‐saturated broth, but inhibited in a two‐phase system, were successfully protected by immobilization in carrageenan beads. The same solvent however, partially inhibited the growth of A. niger and A. aceti when present at saturated levels in the broth. The effect of tridodecylamine on lactic acid fermentation in a two‐liquid phase system was investigated in view of enhancing the acid extraction. Since extraction of an acid is favored by low pH, an extractive fermentation of an acid is practical for microorganisms that can grow at pH < pKa, such as A. aceti and A. niger. The amine was found to be toxic to L. delbrueckii above a concentration of 222 mM, and at a level of 50%v, it was deleterious to all cell microorganisms tested, either free or gel entrapped.
A Comparative Study of Models to Predict Protein Adsorption
Authors: Graham E. Earl , Pucciani Albert , Pinto Neville G.
Published: December 2008

Two different models for preducing the adsorption of protein on packed beds of resins are examined. The models are compared by predicting the experimental breakthrough curve of Bovine Serum Albumin on two different resins at different flow rates. The first model fits the experimental breakthrough curves better, but the second one fits them reasonably well and requires no separate measurements of an effective particle diffusivity.
Correlation of Aqueous Two‐Phase Partitioning of Proteins with Changes in Free Volume
Authors: Grossman Paul D. , Gainer John L.
Published: December 2008

Phase separation and protein partitioning in polymer‐salt aqueous two‐phase systems have been correlated with changes in free volume. Both solute partitioning and phase stability are proposed to be related to those changes in liquid structure that can be described by measurements of the free volume of the mixture upon phase splitting.
Average Convective Heat Transfer Coefficients in Single Screw Extrusion of Non‐Newtonian Food Materials
Authors: Mohamed I. O. , Morgan R. G. , Ofoli R. Y.
Published: December 2008

This study deals with solving the Graetz‐Nusselt problem for single‐screw extrusion of power law fluids with viscous dissipation along the channel. The momentum and energy equations were solved numerically for the temperature and velocity profiles, which were then used for determining the Nusselt number. Results are presented in terms of the Nusselt, Brinkman, and reciprocal Graetz numbers.

The results indicate that the Nusselt number is relatively unaffected by the Brinkman number, for both heating and cooling. However, the Brinkman number significantly affects the bulk temperature. For Brinkman numbers less than ‐40, the rate of viscous heat generation is greater than the convective cooling capacity of the extruder. Increasing the screw compression ratio produced significant increase in bulk temperature and Nusselt number for the case of heating. The Nusselt number is less sensitive to the flow behavior index for the case of cooling, while somewhat sensitive for the case of heating. Data from the literature were compared to results from this analysis.
Application of Gibbs' Rule and a Simple Pathway Method to Microbial Stoichiometry
Authors: Tsai S. P. , Lee Y. H.
Published: December 2008

The power of metabolic pathway stoichiometry for applications in bioreactor monitoring and control, in terms of the degrees of freedom, the calculation of reaction rates, and the validity of pathway models, is analyzed by using Gibbs' rule of stoichiometry. The pathway stoichiometry has significant advantages over the macroscopic balance methods when the number of independent reactions is not at its maximum. When the number of reactions is at the maximum, the power of the pathway stoichiometry is very much limited, and it should be used with caution. A simple method is also proposed to derive all possible independent stoichiometric constraints from the metabolic pathways. For most practical fermentations, the proposed method is much easier to use than the existing methods in the literature.
Recovery of an Extracellular Alkaline Protease From Whole Fermentation Broth Using Reversed Micelles
Authors: Rahaman R. S. , Chee J. Y. , Cabral J. M. S. , Hatton T. A.
Published: December 2008

The liquid‐liquid extraction of an extracellular alkaline protease from its fermentation broth was carried out, using a reversed micellar organic solvent. Optimum process parameters were determined for extraction using a 250 mM AOT in isooctane micellar solution. With unequal phase volume ratios, purification factors as high as 6 have been obtained from completely untreated broth. Yields up to 56% were achieved from the same broth using a three‐stage cascade.
The Influence of Shear Stress on Cultured Vascular Endothelial Cells: The Stress Response of an Anchorage‐Dependent Mammalian Cell
Authors: Levesque M. J. , Sprague E. A. , Schwartz C. J. , Nerem R. M.
Published: December 2008

The influence of hydrodynamic forces on anchorage‐dependent mammalian cells is of interest both in biomedical research and in the development of scaled‐up mammalian cell bioreactor systems. Our own studies, reviewed here, have demonstrated that, in response to a fluid‐imposed laminar shear stress, cultured vascular endothelial cells undergo a dramatic alteration in structure and function. From these and related studies, it may be possible to obtain some insight into the general response of anchorage‐dependent mammalian cells to hydrodynamic forces. An unanswered question is: how does such a cell recognize and then transduce a fluid mechanic signal?
Bioaffinity Separations Using Reversed Micellar Extraction
Authors: Woll J. M. , Hatton T. A. , Yarmush M. L.
Published: December 2008

It is shown that significant enhancements in the efficiency of protein recovery using reversed micelle extractants are possible if an affinity ligand surfactant is incorporated in the micellar phase formulation. The partitioning of the model protein concanavalin‐A was found to increase dramatically on addition of small amounts of octyl β‐D‐glucopyranoside (2 to 10 percent of the total surfactant concentration) to the organic reversed micellar phase, while transfer of ribonuclease‐A was essentially unaffected by the addition of this biological detergent. Glucose inhibited the solubilization of concanavalin‐A owing to competition for the binding sites between glucose and the affinity ligand. The experimental results were well described in terms of a simple thermodynamic model for the affinity partitioning of the protein between the two phases. Estimated binding constants for the protein‐ligand complex in the reversed micellar phase are consistent with published aqueous‐phase results.
Response of a Mouse Hybridoma Cell Line to Heat Shock, Agitation, and Sparging
Authors: Passini Cheryl A. , Goochee Charles F.
Published: December 2008

A mouse hybridoma cell line was used as a model for studying the effect of three different environmental stresses. The heat shock response of the hybridoma cell line was examined using two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE). The relative synthesis of proteins of approximately 110‐, 95‐, 90‐, 70‐, 60‐, and 55‐kDa increased in response to a 42°C heat shock. Of particular interest was the identification of apparent isoforms of the heat shock proteins at 110‐, 60‐, and 55‐kDa. The time course of recovery for the hybridoma cell line from heat shock was consistent with previous results for other mammalian cell systems. The effect of elevated agitation rate on cell growth rate, monoclonal antibody production, and intracellular protein synthesis (using 2‐D PAGE) was then examined. Agitation conditions ranging from tissue flask culture (i.e., no agitation) to 400 RPM in a three‐liter bioreactor with a flat‐blade turbine impeller and baffles all resulted in no observed effect on cell growth rate, monoclonal antibody production, or the pattern of intracellular protein synthesis. Next, the effect of sparging was considered. In the absence of any protective agent, cells were lysed by direct sparging. The surfactant Pluronic® F‐68, at a concentration of 0.2% (w/v), provided complete protection from cell lysis due to sparging, with no effect on cell growth, monoclonal antibody synthesis, or the pattern of intracellular protein synthesis. At a Pluronic® F‐68 concentration providing only partial protection from cell lysis (0.01% (w/v)), no effect of sparging was observed on the antibody synthesis rate per viable cell, nor was there any detectable effect on the pattern of intracellular protein synthesis. Finally, the patterns of intracellular protein synthesis were compared for log and stationary phase cells. Significant declines in the basal synthesis rates of the 70‐ and 90‐kDa heat shock proteins (HSC70 and HSP90) were observed as cells entered stationary phase, while the relative synthesis rates of several other proteins increased.
Effects of radiation on the NMR relaxation effects of aqueous solutions of gadolinium contrast agents
Authors: Gultekin David H. , Raidy Thomas E. , Gore John C.
Published: December 2008

We investigate the effects of radiation on aqueous solutions of two common MRI contrast agents based on paramagnetic gadolinium chelates. Aqueous solutions of Gd–DTPA (gadolinium diethylenetriaminepentaacetic acid) and Gd–HP‐DO3A (gadoteridol), as well as Gd–DTPA in the presence of concentrations of several common metabolites (N‐acetylaspartate, Choline, Creatine and myo‐inositol) typical of conditions in vivo, were irradiated at dose levels up to 30 Gy using a 6 MV linear accelerator and imaged using a 1.5 T MRI system. In addition, the effects of radiation dose on solution relaxation rates were compared with the effects of temperature by subjecting the same samples to varying temperatures over a range of 4 K using the same experimental conditions and imaging sequences. Radiation caused small increases (1% or less at a dose of 20 Gy) in the relaxivity of solutions. The effects of radiation on relaxivities were orders of magnitude smaller than the effects of temperature over the range in this study. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis of Chlamydocin by Chelate‐Claisen Rearrangement
Authors: Quirin Christian , Kazmaier Uli
Published: December 2008

Chelate‐Claisen rearrangement of a chiral allylic ester allows the synthesis of the unusual epoxyketo amino acid Aoe found in chlamydocin, one representative of a group of peptide‐based HDAc inhibitors. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
A randomized‐response investigation of the education effect in attitudes towards foreigners
Authors: Ostapczuk Martin , Musch Jochen , Moshagen Morten
Published: December 2008

While negative correlations have often been found between a respondent's education and his attitudes towards foreigners, the reasons for this education effect are still under debate. We examined the hypothesis that the highly educated may not be genuinely less xenophobic, but simply more prone to give socially desirable, xenophile answers in attitude questionnaires. We therefore compared the attitudes of respondents who were either questioned directly or using a cheating detection extension of the randomized‐response technique (RRT). The latter is supposed to yield more honest answers to sensitive questions by experimentally offering the interviewee a higher degree of confidentiality. Under direct questioning conditions, we replicated the education effect; 75% of the highly educated expressed xenophile attitudes, as opposed to only 55% of the less educated. Under randomized‐response conditions, we obtained significantly reduced estimates of 53% for the proportion of xenophiles among the highly educated, and 24% among the less educated, indicating a strong distortion of self‐reported attitudes towards foreigners in both groups. However, a significant proportion of participants disobeyed the RRT instructions regardless of education. Because the education effect was found even after controlling for social desirability, it seems to be a genuine effect, rather than an artefact of a differential response bias. Copyright © 2008 John Wiley & Sons, Ltd.
Blending high school and college: Rethinking the transition
Authors: Hoffman Nancy , Vargas Joel , Santos Janet
Published: December 2008

For many students the first year of college begins before high school ends. This reality is requiring that educators rethink their traditional notions of the first year.
New challenges in working with traditional‐aged college students
Authors: Keup Jennifer R.
Published: December 2008

Although the transition from high school to college is a predictable rite of passage for students in their late teens and early twenties, much about the nature of these students and their environments is changing.
Spectral weighting for distributed backward propagation image reconstruction in diffraction tomography
Authors: Lee Hua
Published: December 2008

The objective of this work is to provide the formulation of the spatial‐frequency weighting of distributed filtered backward propagation in multiple‐projection diffraction tomography. This formulation provides the precise frequency‐weighting characteristics for the generalized tomographic data‐acquisition configurations. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 18, 307–309, 2008
Correcting image defects of stained glass windows
Authors: Suganthan S. , MacDonald L. W.
Published: December 2008

The main problem of photographing stained glass windows is setting the correct exposure. An overall average exposure setting frequently results in the highlight areas being overexposed, or dark area being under‐exposed, or both. It is therefore necessary to provide a suitable set of image processing tools to correct the image defects. In this work describe several algorithms to solve this problem of nonuniformity of illumination. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 18, 296–306, 2008