bluuebunny/crossref_metadata_2025 huggingface dataset:
Disclosure protection of microdata: problems and solutions
Authors: Keller W.J. , Bethlehem J.G.
Published: April 2008

National statistical offices meet an increasing demand for the dissemination of data sets containing individual data on respondents. This trend may cause problems with respect to the care taken not to disclose data about individuals. Therefore the risk of disclosure of each microdata set to be released should be assessed. If this risk is too high, measures have to be taken to protect the data set. This contribution describes the disclosure problem, and explains why it is a real problem. Using the concept of uniqueness, some theory is developed which may help to establish the risk of identification. It turns out that useful microdata sets can only be released if some of the disclosure risks are dealt with by legal arrangements, rather than by restrictions on the data to be released.
Variables control chart limits and tests for special causes
Authors: Does R.J.M.M. , Schriever B.F.
Published: April 2008

Control charts are used to detect problems in control such as outliers, shifts in levels or excess variability in subgroup means that may have a special cause. This paper addresses itself to deriving control chart limits based on past data and based on initial samples in a current control situation. We present a general setting for control charts. Furthermore, an overview is given of tests for special causes. The tests are standardized so that the asymptotic type I error does not exceed a fixed level. The distributions of the run lengths of the tests and combinations of tests are also evaluated. We propose to use a low percen‐tile of the run length distribution, instead of the average run length, to study the performance of the tests. These indicate that, in particular when tests are combined, the run length percentiles may be too small for practical purposes. It is shown that (nearly) exact control chart limits for observations from a normal distribution exist. The traditional limits differ considerably from the proposed ones and correspond to even smaller run length percentiles.
On the backfitting algorithm for additive regression models
Authors: Härdle W. , Hall P.
Published: April 2008

We analyse additive regression model fitting via the backfitting algorithm. We show that in the case of a large class of curve estimators, which includes regressograms, simple step‐by‐step formulae can be given for the back‐fitting algorithm. The result of each cycle of the algorithm may be represented succinctly in terms of a sequence of d projections in n‐dimensional space, where d is the number of design coordinates and n is sample size. It follows from our formulae that the limit of the algorithm is simply the projection of the data onto that vector space which is orthogonal to the space of all n‐vectors fixed by each of the projections. The formulae also provide the convergence rate of the algorithm, the variance of the backfitting estimator, consistency of the estimator, and the relationship of the estimator to that obtained by directly minimizing mean squared distance.
On discrete α‐unimodal distributions
Authors: Alamatsaz M. H.
Published: April 2008

Some characterizations of a‐unimodal lattice distributions, introduced in Abouammoh (1987,19881, and a‐monotone lattice distributions, introduced in Steutel (1988), are discussed. Convolution and symmetrization of a‐monotone lattice distributions are also investigated. The characterizations and convolution properties obtained by Abouammoh in this connection are corrected and improved.
Quantile‐locating functions and the distance between the mean and quantiles
Authors: Gilat D. , Hill T. P.
Published: April 2008

Given a random variable X with finite mean, for each 0 < p < 1, a new sharp bound is found on the distance between a p‐quantile of X and its mean in terms of the central absolute first moment of X. The new bounds strengthen the fact that the mean of X is within one standard deviation of any of its medians, as well as a recent quantile‐generalization of this fact by O'Cinneide.
Asymptotic consequences of neglected dynamics in individual effects models*
Authors: van den Doel I. T. , Kiviet J. F.
Published: April 2008

We assess the asymptotic consequences of estimating static models based on cross‐section or panel data, when in reality the data are generated by a dynamic relationship, involving lagged dependent and current and lagged exogenous variables as well as individual effects. If the exogenous variable follows a stationary process, then the static estimators usually underestimate its long‐run effect. This inconsistency is less severe, the higher the autocorrelation of the exogenous variable. If the exogenous variable follows a random walk with or without individual‐specific drift, then the estimators are found to be consistent for the long‐run effect.
On probability models in voting theory
Authors: Berg S. , Lepelley D.
Published: April 2008

This paper illustrates the use of probability models to study properties of voting rules. In particular, a simple occupancy distribution and its limiting Dlrichlet form are introduced, corresponding to simplifying assumptions about voters' preferences. We use as illustrations the occurrence probability of the Condorcet Paradox, a vintage problem in social choice theory, along with the related concept of Condorcet efficiency, a measure of goodness for voting rules. Further examples include properties of a lottery rule and the vulnerability of certain voting rules to strategic manipulation. Prospects for future work are indicated.
Testing the logical structure of questionnaires
Authors: Willenborg L. C. R. J.
Published: April 2008

The logical structure of a questionnaire is formally defined. This structure essentially consists of a set of constraints that should be obeyed by the joint answers to the questions in the questionnaire. The computational complexity of several test procedures for checking the consistency of the logical structure of a questionnaire is discussed.
Neglected dynamics in panel data models; consequences and detection in finite samples*
Authors: van den Doel I. T. , Kiviet J. F.
Published: April 2008

The bias of various estimators for static cross‐section and panel data models is assessed in a simulation study, where the actual data generating process is a dynamic adjustment mechanism with random individual effects. It is concluded that the consequences of incorrectly estimating a static model can be rather serious. Therefore, it is important to have an accurate technique available for the detection of dynamics. Two exact similar tests for the presence of a lagged dependent variable in panel data models are developed; in some simulation experiments these tests outperform standard asymptotic test procedures. Empirical results on Engle curves for food illustrate the above issues.
Polyhedral techniques in combinatorial optimization I: Theory
Authors: Aardal K. , van Hoesel C. P. M.
Published: April 2008

Combinatorial optimization problems appear in many disciplines ranging from management and logistics to mathematics, physics, and chemistry. These problems are usually relatively easy to formulate mathematically, but most of them are computationally hard due to the restriction that a subset of the variables have to take integral values. During the last two decades there has been a remarkable progress in techniques based on the polyhedral description of combinatorial problems, leading to a large increase in the size of several problem types that can be solved. The basic idea behind polyhedral techniques is to derive a good linear formulation of the set of solutions by identifying linear inequalities that can be proved to be necessary in the description of the convex hull of feasible solutions. Ideally we can then solve the problem as a linear programming problem, which can be done efficiently. The purpose of this manuscript is to give an overview of the developments in polyhedral theory, starting with the pioneering work by Dantzig. Fulkerson and Johnson on the traveling salesman problem, and by Gomory on integer programming. We also present some modern applications, and computational experience.
Fifty years of measurement and scaling in the Dutch social sciences
Authors: van der Heijden P. G. M. , Sijtsma K.
Published: April 2008

It is evident from recent issues of journals like Psychometrika and Applied Psychological Measurement that the Dutch contribution to the development of the area of measurement and scaling is considerable. In the first part of this paper, we try to answer the question how this could happen. In the early development De Groot in Amsterdam and Van de Geer in Leiden created an academic climate that made it possible for many researchers to develop their skills. Some other possible reasons are sketched for the flourishing of this area in the Netherlands, but it is difficult to assess which reasons were most important. In the second part of the paper, we analyze the international impact of the Dutch contribution by a citation analysis in four fields of measurement and scaling: factor analysis, test theory including item response theory, latent class analysis, and optimal scaling and multidimensional scaling. It appears that Dutch researchers not only publish a lot, but also that the impact of their publications is at the same level as publications produced world‐wide.
Random polymers
Authors: den Hollander F.
Published: April 2008

This paper is a mini‐review of some recent developments on probabilistic models for polymer chains.
Interior point methods, a decade after Karmarkar—a survey, with application to the smallest eigenvalue problem
Authors: Jansen B. , Roos C. , Terlaky T.
Published: April 2008

The introduction of Karmarkar's polynomial algorithm for linear programming (LP) in 1984 has influenced wide areas in the field of optimization. While in the 1980s emphasis was on developing and implementing efficient variants of interior point methods for LP, the 1990s have shown applicability to certain structured nonlinear programming and combinatorial problems. We will give a historical account of the developments and illustrate the typical results by analyzing a new method for computing the smallest eigenvalue of a matrix. We formulate this latter problem as a so‐called semidefinite optimization problem. Semidefinite optimization has recently gained much attention since it has a lot of applications in various fields (like control and system theory, combinatorial optimization, algebra, statistics, structural design) and semidefinite problems can be efficiently solved with interior point methods.
Measuring the costs of children: parametric and semiparametric estimators1
Authors: Melenberg B. , van Soest A. H. O.
Published: April 2008

How much additional income does a family with four children need to attain the same welfare level as a family with two children? And how much does a single person need compared to a childless couple? These questions are important in applied micro‐economics and underlie public policy on, for example, social benefits and child allowances. In microeconomics, this is known as the problem of measuring equivalence scales. We estimate these scales using two types of subjective survey information. First, we use answers to survey questions on the income required to attain a given utility level. We compare the results for the usual linear model with semiparametric estimates, in which the functional form of the relationship between required income and family size and actual income is left unspecified. Second, we use answers to the question: how satisfied are you with actual household income? We present parametric and semiparametric estimates for ordered response models explaining this discrete variable. We find that according to the second type of information, costs of children are much larger than according to the first.
On the lack of invariance of some Bayesian outlier models
Authors: Fung W. K.
Published: April 2008

The property of non‐invariance to the scale of the data for the Abraham and Box (1978) Bayesian outlier model, and the model that generalizes the Guttman, Dutter and Freeman (1978) outlier analysis is discussed. This drawback is due to the non‐informative prior taken for the parameters. Freeman (1980) expected that most posterior weight would be put on the model with the most outliers if the improper prior is used. We show that this may not be correct. An illustrative example is given.
Lichen planus and other cutaneous manifestations in chronic hepatitis C: pre‐ and post‐interferon‐based treatment prevalence vary in a cohort of patients from low hepatitis C virus endemic area
Authors: Maticic M , Poljak M , Lunder T , Rener‐Sitar K , Stojanovic L
Published: April 2008

Background  Several controversies exist regarding the relationship between hepatitis C virus (HCV) infection and some cutaneous manifestations, lichen planus (LP) in particular.

Objectives  To determine the prevalence of LP and other cutaneous manifestations in a cohort of patients infected with HCV from low HCV endemic area of Slovenia, to correlate findings with chosen biological variables and to assess the role of interferon (IFN)‐based treatment of HCV infection in cutaneous manifestations.

Methods  A total of 171 consecutive HCV‐seropositive patients and 171 HCV‐seronegative age‐ and gender‐matched controls were studied prospectively. Prevalence of cutaneous manifestations, comparison between study patients and controls and correlation of skin findings with demographic, biochemical, virological and liver histologic findings as well as IFN‐based therapy were assessed.

Results  Overall presence of LP in HCV‐seropositives was 2.3%; although LP was not found in controls, the difference was not statistically significant (P = 0.123). Significantly higher than in controls was the prevalence of pruritus (31.0%, P < 0.001), dry skin (16.4%, P < 0.001) and hair loss (9.9%, P < 0.001). In IFN‐based treatment naïves, skin findings were more frequent compared with controls, but not significantly, with no correlation to chosen biological variables. Current IFN‐based treatment was significantly connected to pruritus (P < 0.001) and dry skin (P < 0.001). Compared with treatment naïves, in post‐treated patients pruritus (odds ratio, 19.13; 95% confidence interval, 6.85–53.42; P < 0.001), dry skin (odds ratio, 4.21; 95% confidence interval, 1.44–12.31; P < 0.001) and hair loss (P < 0.001) were significantly more common.

Conclusions  LP was not significantly related to HCV infection. Prevalence of pruritus, dry skin and hair loss was significantly higher in post‐compared with pre‐treated patients. The role of IFN in post‐treatment persistence of skin manifestations needs to be assessed.
Contact allergy in patients with rosacea: a clinic‐based, prospective epidemiological study
Authors: Jappe U , Schäfer T , Schnuch A , Uter W
Published: April 2008

Background  Rosacea is a relatively common inflammatory skin disease of unknown prevalence. The proportion of contact allergy complicating rosacea and its therapy, respectively, is largely unknown.

Objective  To estimate the prevalence of specific contact allergy in rosacea patients and to compare this with the prevalence observed in the general population and in general patch test patients.

Patients/methods  In this prospective monocentre study, 78 patients with rosacea were investigated for contact sensitizations via patch testing the standard series, constituents of topical formulations, preservatives, fragrances, topically applied drugs and, if available, patient's own products.

Results  Positive reactions occurred to nickel (II) sulphate (12 of 78, 15.4%), fragrance mix I (4 of 77, 5.2%), balsam of Peru (8 of 77, 10.4%; significantly elevated prevalence compared to that observed in the population‐based KORA study), potassium dichromate (4 of 78, 5.1%) and Lyral (3 of 78, 3.8%). Regarding topical antibiotics, only 1 of 78 (1.3%) patients was positive to neomycin sulphate, and none to metronidazole; however, 6 of 75 (8%) patients were positive to gentamicin sulphate, and 4 of 76 (5.3%) patients were positive to framycetin sulphate. No allergic but irritant patch test reactions, instead, were provoked by various patients’ own products as well as by the irritant sodium lauryl sulphate (SLS) even in low concentrations.

Conclusion  Despite the limited power of the study, a strikingly high prevalence of contact allergy to gentamicin sulphate was observed, which is probably due to antibiotic treatment of rosacea‐associated eye symptoms. The reactions to the irritant SLS probably mirror the extreme skin sensitivity in rosacea.
Forming of Ceramic Laminates Comprising Thin Layers of a Few Particles
Authors: Nicolaidis Ilias , Gurauskis Jonas , Baudín Carmen , Moreno Rodrigo , Javier Sánchez‐Herencia A.
Published: April 2008

In this paper, a water‐based colloidal processing method for manufacturing multilayers with very thin zirconia layers between thick alumina‐based layers is presented. The procedure involves the dip coating of green tapes in binder‐containing slurries and further lamination and sintering. Dipping studies show that thickness increases with soaking time until a higher limit is achieved, indicating the existence of interaction between slurry and substrate. After sintering, homogeneous, dense, and continuous zirconia layers with thicknesses between 3 and 0.8 μm alternated with 350 μm layers of alumina are obtained, thus meaning that the cross section of these thin layers range from four or five to only one or two grains. Although the residual stresses are estimated to be around 2 GPa, indentation cracks do not shown any interaction when passing through the compressive layers, indicating the existence of a lower thickness limit to achieve a threshold stress.
Erythropoietin inhibits cytokine production of neonatal and adult leukocytes
Authors: Strunk Tobias , Härtel Christoph , Temming Petra , Matzke Nadja , Zimmer Janna , Schultz Christian
Published: April 2008

Background: Erythropoietin (Epo) was originally defined as a hematopoietic growth factor, but also has potent tissue‐protective properties. The cytokine‐modulating actions of Epo have received scant attention. We hypothesized that Epo significantly influences the in vitro cytokine production in both neonates and adults.

Methods: The effects of Epo were investigated using a standardized in vitro whole blood assay. Production of various cytokines was assessed by means of intracellular cytokine detection (IL‐2, ‐6, ‐8, IFN‐γ and TNF‐α) in preterm infants, term neonates and adults. Furthermore, synthesis of IL‐4, ‐5 and ‐10 in adults was investigated via cytometric bead array.

Results: Epo significantly inhibits the production of various cytokines in preterm infants, term neonates and adults. In CD3+ lymphocytes, Epo predominantly decreases the number of IL‐2‐positive cells in all age groups. Similarly, in CD14+ cells, Epo significantly diminishes the number of IL‐6‐ and TNF‐α‐producing cells. Furthermore, Epo significantly inhibits the synthesis of IL‐4, IL‐5 and IL‐10 in adults.

Conclusion: rhEpo has significant inhibitory potential on the production of various cytokines by leukocytes in preterm and term infants as well as in adults. The described effect likely contributes to the tissue protective properties of Epo.
Risk factors for early sepsis in very low birth weight neonates with respiratory distress syndrome
Authors: Shani Laliv , Weitzman Dahlia , Melamed Rimma , Zmora Ehud , Marks Kyla
Published: April 2008

Aim: To identify maternal and neonatal factors that increase suspicion of early sepsis in Very Low Birth Weight neonates with respiratory distress syndrome.

Methods: The cohort included 282 neonates born at Soroka Medical Centre 1996–2000. Definitions of ‘high’ and ‘low’‐suspicion groups for early sepsis were based on comparison between neonates with early sepsis and the remaining cohort. Univariate analysis and logistic regression were used to compare between groups.

Results: The incidence of early sepsis in the cohort was 1.8%, and 94% received antibiotics following delivery. Comparing with the remaining cohort, the five neonates with early sepsis had increased incidence of positive maternal cultures, use of antenatal antibiotics, lower 1 min Apgar scores and tendency to leucopenia. A ‘low‐suspicion’ group comprised 38% of the cohort and did not include any neonates with early sepsis. This group were more frequently treated with antenatal steroids and delivered by Caesarean section compared to the ‘high‐suspicion’ group, but otherwise there were no clinical and laboratory differences.

Conclusion: Although the incidence of early sepsis is low almost all neonates received antibiotics. A ‘low‐suspicion’ group was defined and the role of antibiotic treatment in this group needs to be determined.
Secretory products of the haptoral reservoirs and peduncular glands in two species of Bravohollisia (Monogenea: Ancyrocephalidae)
Authors: Wong Wey‐Lim , Brennan Gerard P. , Halton David W. , Maule Aaron G. , Lim Lee‐Hong Susan
Published: April 2008

Abstract. Light and electron microscopy were used to characterize the structure of secretory cells and their products involved in attachment of two monogenean parasites of fish, in order to understand their role in the attachment process. In Bravohollisia rosetta and Bravohollisia gussevi, peduncular gland cells with two nuclei, granular endoplasmic reticulum, and Golgi bodies produce dual electron‐dense (DED) secretory bodies with a homogenous electron‐dense rind and a less electron‐dense fibrillar core (oval and concave in B. rosetta and oval in B. gussevi). The DED secretory bodies are altered as they migrate from the gland cell to the haptoral reservoir, the superficial anchor grooves, and into the gill tissues. The contents of the DED secretory bodies are exocytosed into the reservoirs, fibrillar cores persisting in the matrix, some of which condense, forming highly electron‐dense spherical bodies. Small, oval, electron‐dense bodies occur in the grooves, while no inclusions are visible in the homogenous exudate within the gill tissues. The single tubular extension of the reservoir enters a bifurcate channel within the anchor via a concealed, crevice‐like opening on one side of the anchor. The channel directs secretions into the left and the right grooves via concealed apertures. The secretions, introduced into the tissues by the anchors, probably assist in attachment. The secretions are manifested externally as net‐like structures and observed in some cases to be still attached to the point of exudation, on anchors detached from the gill tissues. This suggests that despite having the anchors detached, the worms can still remain anchored to the gill tissues via these net‐like structures. Based on this, it is postulated that the net‐like secretions probably function as a safety line to anchor the worm during the onset of locomotion and in doing so reduce the risk of tearing host tissues.
The parasitic polychaete known as Asetocalamyzas laonicola (Calamyzidae) is in fact the dwarf male of the spionid Scolelepis laonicola (comb. nov.)
Authors: Vortsepneva Elena , Tzetlin Alexander , Purschke Günter , Mugue Nikolai , Haß‐Cordes Eva , Zhadan Anna
Published: April 2008

Abstract. The morphology of the obligately ectoparasitic polychaete Asetocalamyzas laonicola was studied by light and electron microscopy, and its taxonomic position was determined using molecular methods. The parasite has an extensive coelomic cavity, complete septae, and well‐developed segmental nephridia, circulatory, and digestive systems. The nervous system is rudimentary and without ganglia. The parasite's anterior region penetrates the tissues of the host, and opens into the host's body cavity. The epidermal tissues of the parasite and the host are highly integrated in the area of contact, and the parasite's cuticle is continuous with that of the host. Blood vessels of the parasite and the host may interlace in the fusion zone. The dorsal side of the parasite faces the dorsal side of the host. All parasites were males, but all hosts were females. In order to elucidate the uncertain systematic position of the parasite, molecular systematic studies were conducted. Parasite and host 18S rDNA sequences were virtually identical and revealed that both belong to the spionid cluster. These sequences differed from those of Scolelepis squamata and Scolelepis bonnieri by 2.7% and 0.9%, respectively. In addition, of seven partial sequences of the mitochondrial COI gene obtained from three parasites and four hosts, six were identical, and in one host–parasite pair, COI sequences differed by one substitution. Partial ITS2 sequences from one host–parasite pair were analyzed and also found to be similar but not identical, with two indels in a 645‐bp alignment. We conclude that the parasite is in fact a dwarf male of its conspecific spionid female host. Consequently, A. laonicola is transferred to Scolelepis (Spionidae), forming the new combination Scolelepis laonicola.
Parasitic mites influence fitness components of their host, the land snail Arianta arbustorum
Authors: Schüpbach Hans U. , Baur Bruno
Published: April 2008

Abstract. Parasites can influence the population dynamics of their hosts by affecting life‐history strategies and behavior. The hematophageous mite Riccardoella limacum lives in the lung cavity of terrestrial gastropods. We used correlational and experimental approaches to investigate the influence of parasite infection on the behavior and life‐history traits of the simultaneously hermaphroditic land snail Arianta arbustorum, a common host of R. limacum. Naturally infected individuals of A. arbustorum, collected in the wild, showed a decreased activity compared with uninfected snails. The reproductive output, expressed as the number of eggs deposited in a reproductive season, was reduced in mite‐infected hosts. However, the hatching success of the eggs laid by parasitized snails was slightly higher than that of uninfected individuals. We also examined winter survival in 361 adults of A. arbustorum collected from four natural populations. The prevalence of mite infection ranged from 44.8% to 70.1% in three populations (snails in the fourth population were not infected). Winter survival was reduced in infected snails in two out of three populations. Furthermore, experimentally infected snails from an uninfected population showed a reduced winter survival compared with control snails. Our results indicate that parasite pressure imposed by members of R. limacum may influence life history in A. arbustorum.
Pseudohypericin and Hyperforin in Hypericum perforatum from Northern Turkey: Variation among Populations, Plant Parts and Phenological Stages
Authors: Çirak Cüneyt , Radusiene Jolita , Janulis Valdimaras , Ivanauskas Liudas
Published: April 2008

Hypericum perforatum is a perennial medicinal plant known as “St. John's wort” in Western Europe and has been used in the treatment of several diseases for centuries. In the present study, morphologic, phenologic and population variability in pseudohypericin and hyperforin concentrations among H. perforatum populations from Northern Turkey was investigated for the first time. The aerial parts of H. perforatum plants representing a total of 30 individuals were collected at full flowering from 10 sites of Northern Turkey to search the regional variation in the secondary metabolite concentrations. For morphologic and phenologic sampling, plants from one site were gathered in five phenological stages: vegetative, floral budding, full flowering, fresh fruiting and mature fruiting. The plant materials were air‐dried at room temperature and subsequently assayed for chemical concentrations by high performance liquid chromatography. Secondary metabolite concentrations ranged from traces to 2.94 mg/g dry weight (DW) for pseudohypericin and traces –6.29 mg/g DW for hyperforin. The differences in the secondary metabolite concentrations among populations of H. perforatum were found to be significant. The populations varied greatly in hyperforin concentrations, whereas they produced a similar amount of pseudohypericin. Concentrations of both secondary metabolites in all tissues increased with advancing of plant development and higher accumulation levels were reached at flowering. Among different tissues, full opened flowers were found to be superior to stems, leaves and the other reproductive parts with regard to pseudohypericin and hyperforin accumulations. The present findings might be useful to optimize the processing methodology of wild‐harvested plant material and obtain increased concentrations of these secondary metabolites.
Angiotensin II and epidermal growth factor receptor cross‐talk mediated by a disintegrin and metalloprotease accelerates tumor cell proliferation of hepatocellular carcinoma cell lines
Authors: Itabashi Hidenori , Maesawa Chihaya , Oikawa Hiroki , Kotani Koji , Sakurai Eiichi , Kato Kuniyuki , Komatsu Hideaki , Nitta Hiroyuki , Kawamura Hidenobu , Wakabayashi Go , Masuda Tomoyuki
Published: April 2008

Aim:  The cross‐talk pathway between angiotensin II (AngII) and the epidermal growth factor receptor (EGFR) mediated by epidermal growth factor (EGF)‐like ligands cleaved by a disintegrin and metalloprotease (ADAM) has been elucidated in several cell types. Even though the liver is a representative angiotensinogen‐producing organ, such cross‐talk has never been elucidated in hepatocellular carcinomas (HCCs). We investigated whether AngII exerted a mitogenic effect on HCC cell lines through the AngII–EGFR cross‐talk pathway.

Methods:  We determined the expression and/or phosphorylation status of AngII receptor type 1 (AGTR1), ADAM9, ADAM17, ERK1/2, STAT3, AKT and EGFR in five HCC cell lines using Western blotting. Proliferation and invasion activities were measured by ATP and Matrigel invasion assays, respectively.

Results:  AGTR1 was expressed ubiquitously in HCC cell lines. EGFR expression in HepG2 was relatively weaker than that in the remaining HCC cell lines. The phosphorylation status of EGFR, ERK1/2, STAT3 and AKT was upregulated by AngII treatment in two EGFR‐overexpressing cell lines (Huh7 and PLC/PRF/5), but not in HepG2 (showing weak EGFR expression). AngII stimulation significantly accelerated proliferation and invasion activities in Huh7 and PLC/PRF/5, and was inhibited by pretreatment with an ADAM inhibitor. A selective AGTR1 blocker significantly repressed proliferation activity in both cell lines, but did not significantly repress the invasion activity. Both chemical agents and neutralizing antibodies against ADAMs (ADAM9 and ADAM17) and EGF‐like ligands suppressed EGFR transactivation and/or subsequent phosphorylation of ERK1/2, STAT3 and AKT.

Conclusion:  These results suggest that AngII–EGFR cross‐talk signaling mediated by ADAMs is involved in the proliferation and invasion activities of several HCC cell lines.
Microencapsule technique protects hepatocytes from cryoinjury
Authors: Kusano Tomokazu , Aoki Takeshi , Yasuda Daisuke , Matsumoto Shuichiro , Jin Zhenghao , Nishino Nobukazu , Hayashi Ken , Odaira Masanori , Yamada Kousuke , Koizumi Tomotake , Izumida Yoshihiko , Mitamura Keitaro , Enami Yuta , Niiya Takashi , Murai Noriyuki , Kato Hirohisa , Shimizu Yoshinori , Kou Keitatsu , Furukawa Yoshinori , Matsusita Michiaki , Todo Satoru , Shioda Seiji , Kusano Mitsuo
Published: April 2008

Aim:  Hepatocyte transplantation is a potential alternative to whole organ liver transplantation. To realize this procedure, a hepatocyte bank system capable of supplying large numbers of hepatocytes must be established. We previously reported an easy method for cryopreserving hepatocytes using a microencapsulation technique. Here, we investigated how cryoinjury to microencapsulated hepatocytes could be avoided during cryopreservation.

Methods:  Hepatocytes from Sprague–Dawley rats were harvested in situ using a two‐step ethylenediaminetetraacetic acid (EDTA)/collagenase digestion protocol. The cells were microencapsulated using alginate‐poly L‐lysine. The microencapsulated hepatocytes were put into vials and immediately immersed in liquid nitrogen. The growth of ice crystals in the vials containing the microencapsulated hepatocytes was observed using cryomicroscopy. The microencapsulated hepatocytes were sectioned for ultrastructural examination to investigate their intracellular conditions. Finally, total RNA was isolated from the cryopreserved microencapsulated hepatocytes and analyzed for hepatocyte nuclear factor (HNF) using reverse transcriptase polymerase chain reaction (RT–PCR) analysis.

Results:  Cryomicroscopy showed that the alginate microencapsulation technique protected the hepatocytes from physical damage caused by the growth of extracellular ice crystals. Ultrastructural examination revealed that the intracellular environment of the microencapsulated hepatocytes was maintained. The RT–PCR analysis additionally suggested that the alginate gel also maintained the HNF level.

Conclusion:  Our microencapsulation technique protects hepatocytes from cryoinjury. This novel technique could be utilized by hepatocyte banks.
Occult hepatitis B virus infection as a risk factor for hepatocellular carcinoma in patients with chronic hepatitis C in whom viral eradication fails
Authors: Miura Yukiko , Shibuya Akitaka , Adachi Shigeru , Takeuchi Atsuko , Tsuchihashi Takeshi , Nakazawa Takahide , Saigenji Katsunori
Published: April 2008

Aim:  Recent studies have suggested that an occult hepatitis B virus (HBV) infection negative for HBsAg but positive for HBV‐DNA contributes to hepatocellular carcinoma (HCC) development in patients with chronic hepatitis C. Some follow‐up studies have suggested the clinical importance of occult HBV infections in HCC development even after interferon (IFN) therapy, but a recent study denies the significance of the impact of occult HBV infection. Focusing on HCC development in patients in whom hepatitis C virus (HCV) eradication by interferon (IFN) therapy had failed, we conducted this study in order to assess the impact of occult HBV infections on HCC development in these patients.

Methods:  We enrolled 141 patients with chronic hepatitis C (histological stage F2 or F3) who were seropositive for HCV‐RNA even after IFN therapy. Serum HBV‐DNA was assayed using the real‐time polymerase chain reaction. During follow‐up, ultrasonography and/or computed tomography (CT) were performed at least every 6 months to monitor HCC development.

Results:  The cumulative incidence rates of HCC were 8.9%, 25.7% and 53.7% at 5 years, 10 years and 15 years, respectively, after IFN therapy. Multivariate analysis indicated that low platelet counts (<12 × 104/mm3), occult HBV infection, high ALT levels (≥80 IU/L) after IFN therapy and the staging of liver fibrosis were important independent factors affecting the appearance of HCC.

Conclusions:  Occult HBV was a risk factor for HCC development in patients with chronic hepatitis C in whom HCV eradication had failed. Therefore, patients with chronic hepatitis C with occult HBV should be monitored carefully for HCC after IFN therapy.
Current antiviral therapies for chronic hepatitis B
Authors: Inada Mari , Yokosuka Osamu
Published: April 2008

Among current treatment options for chronic hepatitis B, nucleoside/nucleotide analog therapy has better tolerability and most patients respond to the therapy, while interferon (IFN) therapy has rather severe side‐effects and a lower response rate. However, nucleoside/nucleotide analog therapies have problems of the emergence of drug resistance and poor sustainability of response after discontinuation. After the first nucleoside/nucleotide analog lamivudine, adefovir and entecavir are now utilized in many countries. Adefovir has efficacy for lamivudine resistant patients and current data suggests that adding adefovir to ongoing lamivudine is better than switching to adefovir in terms of viral suppression and the occurrence of resistance. Entecavir can be the first choice for naïve patients, although cross‐resistance has been known for lamivudine resistant patients and mutational screening should take place before using entecavir with such patients. Many other new nucleoside/nucleotide analogs are being developed such as telbivudine, clevudine and tenofovir; the details of each drug will be disclosed in near future.
Model Calibration of Anisotropic Rotordynamic Systems With Speed-Dependent Parameters
Authors: Younan A. A. , El-Shafei A.
Published: April 2008

In this paper, a method for calibrating rotordynamic models of speed-dependent systems with anisotropic support is presented. The method is based on the comparison between the calculated eigenvalues and those extracted from the measured synchronous frequency response functions. An eigensensitivity analysis is conducted to calculate the sensitivity of the computed eigenvalues to the selected elements to be updated. This method is suitable for field application since it requires simple coastdown tests. The method is illustrated on a test rig with fluid film bearings and is shown to be effective in the calibration of rotordynamic models at the speeds of the modes excited within the operating speed range.
Squeeze Film Damper With a Mechanical End Seal: Experimental Force Coefficients Derived From Circular Centered Orbits
Authors: Andrés Luis San , Delgado Adolfo
Published: April 2008

The paper presents parameter identification measurements conducted on a squeeze film damper (SFD) featuring a nonrotating mechanical seal that effectively eliminates lubricant side leakage. The SFD-seal arrangement generates dissipative forces due to viscous and dry-friction effects from the lubricant film and surfaces in contact, respectively. The test damper reproduces an aircraft application that must contain the lubricant for extended periods of time. The test damper journal is 2.54cm in length and 12.7cm in diameter, with a nominal clearance of 0.127mm. The damper feed end opens to a plenum filled with lubricant, and at its discharge grooved section, four orifice ports evacuate the lubricant. In earlier publications, single frequency force excitation tests were conducted, without and with lubricant in the squeeze film land, to determine the seal dry-friction force and viscous damping force coefficients. Presently, further measurements are conducted to identify the test system and SFD force coefficients using two sets of flow restrictor orifice sizes (2.8mm and 1.1mm in diameter). The flow restrictors regulate the discharge flow area and thus control the oil flow through the squeeze film. The experiments also include measurements of dynamic pressures at the squeeze film land and at the discharge groove. The magnitude of dynamic pressure in the squeeze film land is nearly identical for both sets of flow restrictors, and for small orbit radii, dynamic pressures in the discharge groove have peak values similar to those in the squeeze film land. The identified parameters include the test system damping and the individual contributions from the squeeze film, dry friction in the mechanical seal and structure remnant damping. The identified system damping coefficients are frequency and motion amplitude dependent due to the dry-friction interaction at the mechanical seal interface. Squeeze film force coefficients, damping and added mass, are in agreement with simple predictive formulas for an uncavitated lubricant condition and are similar for both flow restrictor sizes. The SFD-mechanical seal arrangement effectively prevents air ingestion and entrapment and generates predicable force coefficients for the range of frequencies tested.
Technology Options for Gas Turbine Power Generation With Reduced CO2 Emission
Authors: Griffin Timothy , Bücker Dominikus , Pfeffer Allen
Published: April 2008

ALSTOM Power R&D laboratories run various programs aimed at finding options that reduce or avoid CO2 emissions through the following: (a) high efficiency power generation equipment to utilize fossil fuels with the lowest possible emissions, and (b) technologies to remove and sequester CO2 created in power plants in an environmentally and economically favorable manner. In this paper, an overview of ongoing CO2 mitigation activities for gas turbine power generation is addressed. Energy efficiency improvements for both new and existing fossil fuel power plants are briefly reviewed. Customer requirements for future power plants with reduced CO2 emissions are discussed. Novel power generation cycles with exhaust gas recirculation for enhanced CO2 removal are introduced and evaluated. Conclusions are drawn regarding their efficiency, energy consumption, and technical feasibility.
Multidimensional Load Estimation Algorithms That Enable Performance Analysis of Industrial Gas Turbines Without A Priori Information
Authors: Yoshida Takuya , Bannai Masaaki , Yoshida Minoru , Yamada Hiroyuki , Ishikawa Masaki
Published: April 2008

Performance analysis and diagnosis for gas turbines usually assume the use of detailed design specifications or similar kinds of information for building and configuring engine models. This allows the nonlinearity of gas turbine performance characteristics to be taken into account. However, this approach tends to make it difficult for users of industrial gas turbines to analyze performance because (1) detailed design specifications are not necessarily supplied to the users, and (2) even if they were available, use of these kinds of information may often lead to complex procedures for model building and for making adjustments and configurations that all require high expertise. The purpose of this paper was to propose a direct modeling approach based only on operating data and not requiring a priori information like manufacturer-supplied specifications while preserving sufficient accuracy. The core element of this approach was the automatic identification and selection of base load operating data from various operating conditions. A set of load estimation algorithms was proposed. They were applied to 31,000h of operating data for two types of engines, which involved actual failure occurrences, and subsequent performance modeling and analysis were carried out. The following results were obtained. (1) The relative performance trends obtained revealed the quantitative extent of degradation during operation and of recovery by repair or engine change. (2) The performance trends gave a good account of actual failures. (3) The accuracy of the performance modeling measured by the 99th percentile of error was on the order of 1%. The proposed direct modeling approach offers sufficient accuracy to quantify the gradual degradation of performance and its recovery by maintenance. The performance trends obtained are useful for further fault diagnosis.
Method and Detailed Analysis of Individual Hydrocarbon Species From Diesel Combustion Modes and Diesel Oxidation Catalyst
Authors: Han Manbae , Assanis Dennis N. , Jacobs Timothy J. , Bohac Stanislav V.
Published: April 2008

An undiluted exhaust hydrocarbon (HC) speciation method, using flame ionization detector gas chromatographs, is developed to investigate HC species from conventional and low-temperature premixed charge compression ignition (PCI) combustion pre- and postdiesel oxidation catalyst (DOC) exhaust. This paper expands on previously reported work by describing in detail the method and effectiveness of undiluted diesel exhaust speciation and providing a more detailed analysis of individual HC species for conventional and PCI diesel combustion processes. The details provided regarding the effectiveness of the undiluted diesel exhaust speciation method include the use of a fuel response factor for HC species quantification and demonstration of its linearity, detection limit, accuracy, and precision. The listing of individual HC species provides not only the information needed to design surrogate exhaust mixtures used in reactor tests and modeling studies but also sheds light on PCI combustion and DOC characteristics. Significantly increased engine-out concentrations of acetylene, benzene, and toluene support the theory that net soot reduction associated with PCI combustion occurs due to the reduction of soot formation (as opposed to increased soot oxidation). DOC oxidation behavior differs depending on the combustion characteristics, which change exhaust species and temperature.
Effects of Inlet Flow Distortion on the Performance of Aircraft Gas Turbines
Authors: Kurzke Joachim
Published: April 2008

This paper describes how the fundamental effects of inlet flow distortion on the performance of gas turbines can be evaluated with any engine performance program that employs an integrated parallel compressor model. In this simulation method, both pressure and temperature distortions are quantified with coefficients, which relate the pressure (respectively temperature) in the spoiled sector to the value in the clean sector. In single spool compressor engines, the static pressure at the exit of the clean sector equals that of the distorted sector. This hypothesis does not hold true with multispool compressor engines because the short intercompressor ducts, which often contain struts or vanes, do not allow the mass flow transfer over the sector borders, which would be required for balancing the static pressures. The degree of aerodynamic coupling of compressors in series can be described in the performance simulation program by the simple coupling factor introduced in this paper. There are two fundamentally different reasons for the change in engine performance: First, there is the impact of the flow distortion on the component efficiencies and thus the thermodynamic cycle and second there are performance changes due to the actions of the control system. From the engine system simulation results, it becomes clear why inlet flow distortion has only a minor impact on the thermodynamic cycle if the comparison of the two operating conditions (with clean and distorted inlet flow) is made at the properly averaged engine inlet conditions. For each compressor, the parallel compressor theory yields two operating points in the map, one for the clean sector and one for the spoiled sector. The performance loss due to the distortion is small since the efficiency values in the two sectors are only a bit lower than the efficiency at a comparable operating point with clean inlet flow. However, the control system of the engine can react to the inlet flow distortion in such a way that the thrust delivered changes significantly. This is particularly true if a compressor bleed valve or a variable area nozzle is opened to counteract compressor stability problems. Especially, using recirculating bleed air for increasing the surge margin of a compressor affects the performance of the engine negatively. Two examples show clearly that the pros and cons of recirculating bleed can only be judged with a full system simulation; looking at the surge line improvement alone can be misleading.
Effect of Fiber Reinforcement on Dynamic Crack Growth in Brittle Matrix Composites
Authors: Shukla Arun , Khanna Sanjeev K.
Published: April 2008

An experimental investigation is conducted to study the interaction of a running crack with embedded fibers. Dynamic photoelasticity is used to evaluate the crack velocity and the instantaneous stress intensity factor, KID, as the crack propagates across the fibers. Fractography is used to explain the interaction of the dynamic crack front with the fiber. The results show that fibers significantly reduce the stress intensity factor and also the crack velocity. The effect of a weak fiber-matrix interface on crack velocity and KID is studied. A weak interface reduces KID but has no effect on the crack velocity. The crack closing forces applied by fibers bridging the crack faces have been determined for both the strong and weak interfaces and their effect on KID is explained.