bluuebunny/crossref_metadata_2025 huggingface dataset:
Determinants of participation and nonparticipation in job‐related education and training in Shenzhen, China
Authors: Xiao Jin , Tsang Mun C.
Published: December 2004

In the fast‐growing market‐oriented economy of Shenzhen, China, most employees have continued to participate in job‐related education and training. We argue that as firms have acquired autonomy in their operations and individuals have gained the right to pursue their personal occupational aspirations, non–state‐sponsored education and training systems for the working population have developed to respond to the demands from firms, as well as individuals. With survey data from 3,475 employees in seventy‐six firms from Shenzhen, this study uses a multinomial model to examine patterns in employee participation in job‐related education and training. There are basically four options open to employees: taking part in education and training provided by a firm to its own employees, enrolling in education and training offered by institutions outside the firm, availing themselves of both options simultaneously, or not participating. Our findings suggest that these four groups of employees vary in terms of their cultural and symbolic attributes, their individual socioeconomic attributes in relation to their workplace, and the economic attributes of their firm.
Evaluating wetland flow regulating functions using discharge time‐series
Authors: Smakhtin V. U. , Batchelor A. L.
Published: December 2004

This paper describes a parsimonious approach for the evaluation of wetland hydrological functions, based on continuous observed streamflow records and flow duration curves. The functions evaluated are baseflow maintenance and flood attenuation, jointly referred to as ‘flow regulation’. The first step in this evaluation is to establish a reference hydrological condition. This condition is defined in terms of mean daily and instantaneous daily maximum flow time‐series and their corresponding duration curves, assuming that there is no wetland in the catchment. Further steps include calculating the changes of various flow percentiles, caused by the presence of a wetland, detailed hydrograph analysis, baseflow analysis and analysis of changes in characteristics of continuous flow events above and below specified threshold discharges. The method is illustrated using the observed streamflow data in the catchment of the Rustenburg wetland in South Africa. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling stream flow for use in ecological studies in a large, arid zone river, central Australia
Authors: Costelloe Justin F. , Grayson Rodger B. , McMahon Thomas A.
Published: December 2004

Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time‐step, grid‐based, conceptual rainfall–runoff model was developed for the previously uninstrumented Neales River in the arid zone of northern South Australia. Hourly, logged stage data provided a record of stream‐flow events in the river system. In conjunction with opportunistic gaugings of stream‐flow events, these data were used in the calibration of the model. The poorly constrained spatial variability of rainfall distribution and catchment characteristics (e.g. storage depths) limited the accuracy of the model in replicating the absolute magnitudes and volumes of stream‐flow events. In particular, small but ecologically important flow events were poorly modelled. Model performance was improved by the application of catchment‐wide processes replicating quick runoff from high intensity rainfall and improving the area inundated versus discharge relationship in the channel sections of the model. Representing areas of high and low soil moisture storage depths in the hillslope areas of the catchment also improved the model performance. The need for some explicit representation of the spatial variability of catchment characteristics (e.g. channel/floodplain, low storage hillslope and high storage hillslope) to effectively model the range of stream‐flow events makes the development of relatively complex rainfall–runoff models necessary for multisite ecological studies in large, ungauged arid zone catchments. Grid‐based conceptual models provide a good balance between providing the capacity to easily define land types with differing rainfall–runoff responses, flexibility in defining data output points and a parsimonious water‐balance–routing model. Copyright © 2004 John Wiley & Sons, Ltd.
Effects of commercial timber harvesting on streamflow regimes in the Plynlimon catchments, mid‐Wales
Authors: Robinson M. , Dupeyrat A.
Published: December 2004

This paper presents the first large‐scale British study of the impacts of commercial forest cutting on stream‐flow regimes. The 70% forested headwaters of the River Severn are part of the intensively instrumented long‐term Plynlimon catchment study into the impact of land use on stream flow. The forest area, comprising predominantly Sitka spruce (Picea sitchensis), was planted mainly in the 1930s and 1940s. Harvesting commenced in the mid‐1980s and over the study period about half the forest has been felled. Changes in annual water yield and extreme flows were studied in four nested catchments ranging in area from about 1 to 10 km2 and compared with an adjacent benchmark grassland catchment. As expected from earlier process studies the cutting of the forest increased total annual flows. Less expected was the clear evidence that the felling augmented low flows. This informs a long‐standing debate whether upland forestry increases or reduces baseflows. A particularly notable result was the lack of impact of the harvesting on storm peak flows. This may result from the application of forest management guidelines designed to reduce soil damage and erosion during the harvesting, and indicates that the forest itself has a limited impact on flooding. These findings are timely because British forest expansion peaked in the 30 years following the Second World War, and large areas of these woodlands are now approaching economic maturity and will be harvested in the next two decades. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling flow resistance in vegetated streams: review and development of new theory
Authors: Green Julian C.
Published: December 2004

Aquatic macrophytes are often the dominant factor influencing flow conditions within the channels they occupy. Existing knowledge of how stream plants affect the flow is outlined, and the different scales at which vegetation resistance operates are proposed. Resistance is shown to be a function of the size of the plants, their structural properties, location in the channel, and the local flow conditions. Current models to calculate this composite resistance effect are assessed in the light of theoretical considerations of the nature of vegetation resistance. New theory is also presented, which demonstrates the non‐linear relationship between channel resistance and the proportion of the channel occupied by vegetation. Copyright © 2004 John Wiley & Sons, Ltd.
Multivariate statistical analysis to identify the major factors governing groundwater quality in the coastal area of Kimje, South Korea
Authors: Kim Ji‐Hoon , Kim Rak‐Hyeon , Lee Jeongho , Cheong Tae‐Jin , Yum Byoung‐Woo , Chang Ho‐Wan
Published: December 2004

The main purpose of this study is to identify the major factors affecting groundwater quality by means of multivariate statistical analysis of the physico‐chemical compositions. Cluster analysis results show that the groundwater in the study area is classified into four groups (A, B, C and D), and factor analysis indicates that groundwater composition, 81·9% of the total variance of 17 variables, is mainly affected by three factors: seawater intrusion, microbial activity and chemical fertilizers. These results might be related to the geographical characteristics of the study area. The main influence on groundwater in groups B, C and D, which are close to the Yellow Sea and contain reclaimed areas, is the seawater intrusion by the present seawater, the trapped seawater, and microbial activity. Group A, however, has been used for agriculture for a long time, and thus groundwater in this group has been largely affected by chemical fertilizers. As groundwater flows from group A to group D according to its path, the governing factor of the groundwater quality gradually changes from chemical fertilizers to microbial activity and seawater intrusion. Copyright © 2004 John Wiley & Sons, Ltd.
How to construct recursive digital filters for baseflow separation
Authors: Eckhardt K.
Published: December 2004

Recursive digital filtering of hydrographs is a baseflow separation method that can easily be automated and has been recommended for providing reproducible results. In the past, different formulations of the most simple filter type, the so‐called one‐parameter filter, have been proposed. In this paper, a theoretical framework is developed for filter algorithms that were constructed under the assumption that the outflow from an aquifer is linearly proportional to its storage. It is shown that these one‐parameter filters describing an exponential baseflow recession are all special cases of a two‐parameter filter whose equation is specified. Its parameters are the recession constant—which can be objectively determined by a recession analysis—and BFImax, the maximum value of the baseflow index that can be modelled by the algorithm. This introduces a subjective element into the baseflow calculation, since BFImax is not measurable. A preliminary analysis based on the results of conventional separation techniques shows that it might be possible to find typical BFImax values for classes of catchments that can be unequivocally distinguished by their hydrological and hydrogeological characteristics. Copyright © 2004 John Wiley & Sons, Ltd.
Parametric pricing of higher order moments in S&P500 options
Authors: Lim G. C. , Martin G. M. , Martin V. L.
Published: December 2004

A general parametric framework based on the generalized Student t‐distribution is developed for pricing S&P500 options. Higher order moments in stock returns as well as time‐varying volatility are priced. An important computational advantage of the proposed framework over Monte Carlo‐based pricing methods is that options can be priced using one‐dimensional quadrature integration. The empirical application is based on S&P500 options traded on select days in April 1995, a total sample of over 100,000 observations. A range of performance criteria are used to evaluate the proposed model, as well as a number of alternative models. The empirical results show that pricing higher order moments and time‐varying volatility yields improvements in the pricing of options, as well as correcting the volatility skew associated with the Black–Scholes model. Copyright © 2004 John Wiley & Sons, Ltd.
Extraction and pertraction of phenol through bulk liquid membranes
Authors: Cichy Wojciech , Schlosser Štefan , Szymanowski Jan
Published: December 2004

The extraction and pertraction of phenol through a bulk liquid membrane (BLM) with Cyanex® 923, Amberlite® LA‐2 and trioctylamine (TOA) as carriers were studied. Cyanex® 923 was selected as the best carrier for pertraction. The distribution coefficient of phenol for solvents with carrier and pure n‐alkanes, the individual mass‐transfer coefficient at the extraction interface and the initial flux of phenol through the extraction interface (JFo) decreased in the order: Cyanex® 923 > Amberlite® LA‐2 > TOA ≫ pure n‐alkanes. The opposite order was observed for the value of the mass‐transfer coefficient in BLM and the maximum flux of phenol through the stripping interface (JRmax). At constant driving forces the maximum fluxes through the extraction and stripping interfaces were similar when amine carriers were used. However, JRmax was lower than JFo for Cyanex® 923. Although the kinetics of stripping was the rate‐determining step, the flux of phenol was significantly higher than in pertraction with amine carriers. The adsorption of the carrier at aqueous phase/membrane interfaces was probably responsible for the rapid and slow transfer of phenol through the extraction and stripping interface, respectively. Copyright © 2004 Society of Chemical Industry
Simultaneous purification and immobilization of bitter gourd (Momordica charantia) peroxidases on bioaffinity support
Authors: Akhtar Suhail , Ali Khan Amjad , Husain Qayyum
Published: December 2004

This paper demonstrates the construction of an inexpensive bioaffinity adsorbent by simply incubating Sephadex G 50 matrix with jack bean meal extract at room temperature. Sephadex G 50 adsorbed 17 mg Con A (concanavalin A) per g of the matrix. Con A‐adsorbed Sephadex was employed for the immobilization of glycoenzymes directly from ammonium sulfate‐fractionated proteins of bitter gourd. The obtained bioaffinity support was very efficient for high yield immobilization of peroxidases from bitter gourd and it bound nearly 425 enzyme units per g of the matrix. Bitter gourd peroxidase immobilized on lectin–Sephadex support showed a very high effectiveness factor, ‘η,’ of 1.25. Immobilized BGP preparation was quite stable against the denaturation induced by pH, heat, urea, Triton X 100, Tween 20, SDS, Surf Excel and water‐miscible organic solvents: dimethyl sulfoxide and dimethyl formamide. Low concentration of detergents like SDS, Tween 20, and Triton X 100 enhanced the activity of soluble and immobilized bitter gourd peroxidase. Peroxidase bound to the bioaffinity support exhibited very high resistance to proteolysis caused by the trypsin treatment. Con A–Sephadex‐bound bitter gourd peroxidase retained 85% of its initial activity after treatment with 2.5 mg trypsin per cm3 of incubation mixture for 1 h at 37 °C while the soluble enzyme lost nearly 40% of the initial activity under similar incubation conditions. Immobilized bitter gourd peroxidase preparation appeared to be more rigid to proteolysis mediated by trypsin compared with soluble bitter gourd peroxidase. Copyright © 2004 Society of Chemical Industry
Effects of supplementation of succinic acid on the production and molecular weight distribution of exopolysaccharides by Antrodia camphorata in batch cultures
Authors: Shu Chin‐Hang , Lung Ming‐Yeou , Xu Chun‐Jun
Published: December 2004

The effects of organic acid supplementation on both yields and molecular weight distributions of exopolysaccharide (EPS) of Antrodia camphorata were investigated in shaker flasks and air‐lift bioreactors. In the shaker flask study, five out of six organic acid‐supplemented cultures showed negative effects on cell growth, the exception being pyruvic acid‐supplemented culture; lower number average molecular weights (Mn) of EPS were obtained in all the supplemented cultures. EPS production was enhanced by 31% due to the addition of succinic acid. Optimum product yield was obtained between 2.0 and 3.0 g dm−3 succinic acid; however, the specific production of EPS increased monotonically as succinic acid concentration was increased from 0 to 5 g dm−3. Enhancement of EPS yield by 28% and a higher Mn of EPS (around 310 kDa) due to the addition of succinic acid were also demonstrated in an air‐lift bioreactor. In addition, a novel fermentation process resistant to EPS degradation is proposed, based on the inhibition of β‐glucanase activity by the supplementation with succinic acid. Copyright © 2004 Society of Chemical Industry
Effects of anions on the photocatalytic and photoelectrocatalytic degradation of reactive dye in a packed‐bed reactor
Authors: Zhang Wenbing , An Taicheng , Cui Mingchao , Sheng Guoying , Fu Jiamo
Published: December 2004

The effects of various anions, Cl−, ClO4−, SO42−, NO3−, HCO3−, H2PO4− and C2O42−, on the photocatalytic and photoelectrocatalytic degradation of reactive Brilliant Orange K‐R have been investigated in a packed‐bed photoelectrocatalytic reactor. It was found that the nature and concentrations of these inorganic anions significantly affected the photocatalytic and photoelectrocatalytic degradation performance of the reactive dye. The results indicated that the external electric field was successfully applied to improve the photocatalytic efficiency of reactive Brilliant Orange K‐R in the presence of Cl−, especially at higher concentrations, while other inorganic anions displayed more or less negative effects on the degradation of the dye. The strongest inhibition effect on photocatalytic and photoelectrocatalytic degradation of the dye was observed in the presence of HCO3− ions. Copyright © 2004 Society of Chemical Industry
An hp‐adaptive finite element method for scattering problems in computational electromagnetics
Authors: Rachowicz W. , Zdunek A.
Published: December 2004

An hp‐adaptive finite element (FE) approach is presented for a reliable, efficient and accurate solution of 3D electromagnetic scattering problems. The radiation condition in the far field is satisfied automatically by approximation with infinite elements (IE). Near optimal discretizations that can effectively resolve local rapid variations in the scattered field are sought adaptively by mesh refinements blended with graded polynomial enrichments. The p‐enrichments need not be spatially isotropic. The discretization error can be controlled by a self‐adaptive process, which is driven by implicit or explicit a posteriori error estimates. The error may be estimated in the energy norm or in a quantity of interest. A radar cross section (RCS) related linear functional is used in the latter case. Adaptively constructed solutions are compared to pure uniform p approximations. Numerical, highly accurate, and fairly converged solutions for a number of generic problems are given and compared to previously published results. Copyright © 2004 John Wiley & Sons, Ltd.
Multiscale enrichment based on partition of unity
Authors: Fish Jacob , Yuan Zheng
Published: December 2004

A new multiscale enrichment method based on the partition of unity (MEPU) method is presented. It is a synthesis of mathematical homogenization theory and the partition of unity method. Its primary objective is to extend the range of applicability of mathematical homogenization theory to problems where scale separation may not be possible. MEPU is perfectly suited for enriching the coarse scale continuum descriptions (PDEs) with fine scale features and the quasi‐continuum formulations with relevant atomistic data. Numerical results show that it provides a considerable improvement over classical mathematical homogenization theory and quasi‐continuum formulations. Copyright © 2005 John Wiley & Sons, Ltd.
Acremonium pyomyositis in a pediatric patient with acute leukemia
Authors: Chang Yu‐Hsiang , Huang Li‐Min , Hsueh Po‐Ren , Hsiao Cheng‐Hsiang , Peng Shinn‐Forng , Yang Rong‐Sen , Lin Kai‐Hsin
Published: December 2004

Invasive Acremonium infection in humans is rare. We report a patient with leukemia who developed pyomyositis due to Acremonium species. Painful cutaneous nodules and severe myalgia were the first clinical manifestations during the neutropenic stage after chemotherapy. Magnetic resonance image (MRI) revealed multiple nodular lesions scattered along the intramuscular regions of the lower legs. Culture of an aspiration grew Acremonium species. Surgical drainage was performed. Although all antifungal agents tested showed no in vitro inhibitory activity, we successfully treated this patient with amphotericin B, granulocyte colony‐stimulating factor (G‐CSF), and surgical drainage. © 2004 Wiley‐Liss, Inc.
Rheology and gelation kinetics in laponite dispersions containing poly(ethylene oxide)
Authors: Baghdadi Hossein A. , Sardinha Heidi , Bhatia Surita R.
Published: December 2004

We report results on the rheology of a model polymer/clay system, laponite clay particles with added poly(ethylene oxide) (PEO), focusing on the kinetics of gel formation and on molecular weight effects. We examined solutions at both pH = 7, where interparticle attractions are present and a networked gel is formed; and at pH = 10, where repulsive forces dominate and laponite forms a colloidal glass. We found that PEO of low to moderate molecular weight significantly slows down gelation and decreases the complex viscosity and elastic modulus of the dispersion by several orders of magnitude for both pH = 7 and 10. In the former case, adsorbed PEO likely forms a steric barrier to the formation of an attractive gel. In the latter case, we propose that free PEO chains in solution induce a depletion attraction between particles, preventing or slowing the formation of a colloidal glass. At higher molecular weights, PEO chains are long enough to bridge between particles and form an associative network, enhancing the viscosity and elastic modulus for both pH = 7 and 10. Finally, we have shown the critical molecular weight for transitioning between these two types of behavior scales with the interparticle distance. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 233–240, 2005
Theoretical and experimental studies on the Raman spectra of electrosynthesized polynaphthalene
Authors: Zhang Jiaxin , Liu Chen , Shi Gaoquan , Zhao Yufen
Published: December 2004

Polynaphthalene (Pnap) was electrosynthesized through the direct oxidation of naphthalene in boron trifluoride diethyl etherate and was characterized with IR and Raman spectroscopy, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy, and thermogravimetric analysis. Raman spectra of oligonaphthalene were calculated with Gaussian 98 at the B3LYP/6‐31G* level. Combining the computational and experimental results, we assigned the Raman bands of pristine Pnap. The Raman bands related to the chain‐stretching vibrations of Pnap around 1600 cm−1 shifted to higher wave numbers as the polymerization degree increased. This phenomenon was in contrast to that of other conducting polymers bearing simple aromatic rings, such as polythiophene and polyfuran. The reason was that the condensed ring of Pnap and the steric repulsion of the interring hydrogen atoms prevented the elongation of conjugation sequences with the polymer chain length. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 241–251, 2005
Impact of congenital heart disease on cerebrovascular blood flow dynamics in the fetus
Authors: Kaltman J. R. , Di H. , Tian Z. , Rychik J.
Published: December 2004

Objectives

Neurological abnormalities are present in some children after repair of congenital heart disease (CHD). Recently, structural brain abnormalities have been identified in infants prior to cardiac surgery. By altering in utero blood flow patterns, the type of CHD may impact upon cerebrovascular flow dynamics prior to birth. We sought to determine whether left‐ and right‐sided obstructive congenital heart lesions modify cerebrovascular flow dynamics in the fetus.

Methods

Pulsed Doppler was used to measure blood flow velocities in the umbilical (UA) and middle cerebral (MCA) arteries in 172 fetuses from 20 to 39 weeks' gestational age referred for fetal echocardiography. Pulsatility index (PI), an indicator of downstream vascular resistance, was determined by (peak systolic velocity—end‐diastolic velocity)/mean velocity.

Results

Fetuses with hypoplastic left heart syndrome (HLHS; n = 28) had decreased MCA‐PI (P = 0.009) compared to normal fetuses (n = 114). Fetuses with right‐sided obstructive lesions (RSOL; n = 17) had increased MCA‐PI (P = 0.001) when compared to fetuses with HLHS. The UA‐PI was elevated in fetuses with RSOLs (P = 0.045).

Conclusions

Cerebrovascular resistance is lower than normal in fetuses with HLHS, a condition in which cerebral perfusion occurs retrograde via the ductus arteriosus. Fetuses with RSOL had significantly higher cerebrovascular resistance compared to fetuses with HLHS. The type of CHD impacts upon fetal cerebrovascular blood flow distribution and this may have implications for later development of neurological sequelae. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Differential diagnosis in fetuses with absent septum pellucidum
Authors: Malinger G. , Lev D. , Kidron D. , Heredia F. , Hershkovitz R. , Lerman‐Sagie T.
Published: December 2004

Objective

To elucidate the characteristic morphological features that may help in the prenatal differential diagnosis of absent septum pellucidum as demonstrated by ultrasound.

Methods

Twenty‐six fetuses were referred to the fetal neurology clinic due to mild to severe ventriculomegaly and a connection between the lateral ventricles. The following ultrasonographic features were evaluated: place and extent of the ventricular communication, non‐cleavage of the hemispheres and deep gray nuclei, callosal anomalies, position of the choroid plexus, and other central nervous system and facial or body anomalies. A flowchart was created in order to facilitate the final diagnosis.

Results

The presence of non‐cleavage and/or characteristic facial anomalies prompted the diagnosis of holoprosencephaly (HPE) in 14 fetuses, including two fetuses with the middle interhemispheric variant. Ten fetuses were diagnosed as having hydrocephalus based on the lack of the same features and the observation that the communication between the lateral ventricles was at the level of the third ventricle with almost normal anterior and posterior segments. In two fetuses the diagnosis of septo‐optic dysplasia vs. isolated agenesis of the cavum septi pellucidi was contemplated.

Conclusions

The use of the proposed flowchart enabled differentiation between hydrocephalus and HPE. The communication between the ventricles in hydrocephalic fetuses may be due to a disruption of the septum pellucidum or to a pathological enlargement of the foramen of Monro. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Inhibitory properties of nucleic acid‐binding ligands on protein synthesis
Authors: Malina Abba , Khan Shakila , Carlson Coby B. , Svitkin Yuri , Harvey Isabelle , Sonenberg Nahum , Beal Peter A. , Pelletier Jerry
Published: December 2004

The use of small molecule inhibitors in the study of cellular processes is a powerful approach to understanding gene function. During the course of a high throughput screen for novel inhibitors of eukaryotic translation, we identified a number of nucleic acid binding ligands that showed activity in our assay. When tested on a panel of mRNA transcripts displaying different modes of translation initiation, these ligands showed a range of biological activities – with some inhibiting both cap‐dependent and internal initiation and others preferentially blocking internal initiation. We used this information to identify a novel threading intercalator that inhibits Hepatitis C virus internal initiation.
From peptide‐bond formation to cotranslational folding: dynamic, regulatory and evolutionary aspects
Authors: Baram David , Yonath Ada
Published: December 2004

Ribosomes are ribozymes exerting substrate positioning and promoting substrate‐mediated catalysis. Peptide‐bonds are formed within a symmetrical region, thus suggesting that ribosomes evolved by gene‐fusion. Remote interactions dominate substrate positioning at stereochemistry suitable for peptide‐bond formation and elaborate architectural‐design guides the processivity of the reaction by rotatory motion. Nascent proteins are directed into the exit tunnel at extended conformation, complying with the tunnel's narrow entrance. Tunnel dynamics facilitate its interactive participation in elongation, discrimination, cellular signaling and nascent‐protein trafficking into the chaperon‐aided folding site. Conformational alterations, induced by ribosomal‐recycling factor, facilitate subunit dissociation. Remarkably, although antibiotics discrimination is determined by the identity of a single nucleotide, involved also in resistance, additional nucleotides dictate antibiotics effectiveness.
Stage‐specific expression of microRNAs during Xenopus development
Authors: Watanabe Toshiaki , Takeda Atsushi , Mise Kazuyuki , Okuno Tetsuro , Suzuki Toru , Minami Naojiro , Imai Hiroshi
Published: December 2004

MicroRNAs (miRNAs) repress target genes at the post‐transcriptional level and play important roles in development and cell lineage decision. However, in vertebrates, both the targets of miRNAs and their expression profile during development are poorly understood. Here, we report the detailed expression profiles of miRNAs from oocyte stage to tadpole stage in Xenopus laevis. As development proceeds, a variety of miRNAs start to be expressed. Most miRNAs emerged at a specific stage and were continuously expressed until the tadpole stage. In addition, we identified a novel miRNA that was expressed only at specific stages of development and that is likely to have roles in midblastula transition.
Short and highly efficient synthetic promoters for melanoma‐specific gene expression
Authors: Martinelli Rosanna , De Simone Vincenzo
Published: December 2004

Here, we report the construction and functional analysis of synthetic promoters designed for gene therapy applications requiring strong and specific gene expression in melanoma cell lines. We have analysed the transcriptional activity of different combinations of two transcriptional regulatory modules, a melanocyte‐specific element from the human tyrosinase promoter and a cell‐cycle‐specific element from the human α‐fetoprotein promoter. Transient expression assays in different cell lines show that several of these composite synthetic promoters can drive a strong and selective expression of a reporter gene in melanoma cell, providing us with a new powerful tool for gene therapy of melanomas.
Cytokine mediated suppression of TF‐1 apoptosis requires PI3K activation and inhibition of Bim expression
Authors: Rosas Marcela , Birkenkamp Kim U. , Lammers Jan-Willem J. , Koenderman Leo , Coffer Paul J.
Published: December 2004

Phosphatidylinositol 3‐kinase (PI3K) and its effector protein kinase B (PKB/c‐akt) have been implicated as critical mediators of cytokine‐induced survival signals. In this study, we have utilized an IL‐5 dependent hematopoietic cell line (TF‐1) to investigate the signaling events involved in cytokine‐dependent erythroblast survival. We demonstrate that IL‐5 rescues TF‐1 cells from apoptosis through a PI3K/PKB‐dependent signaling pathway. Cytokine‐withdrawal leads to activation of the Forkhead transcription factor FOXO3a and subsequent expression of the pro‐apoptotic Bcl‐2 family member Bim. Bim is itself sufficient to induce apoptosis in these cells. Importantly, activation of an inducible active FOXO3a mutant is alone sufficient for upregulation of Bim expression and induction of apoptosis. These data define a mechanism by which survival factors inhibit the default apoptotic pathway and can regulate TF‐1 erythroblast survival.
Presence of syntaxin 1A in secretory granules of chromaffin cells and interaction with chromogranins A and B
Authors: Yoo Seung Hyun , You Soon Hee , Huh Yang Hoon
Published: December 2004

Syntaxin 1A and synaptotagmin I are key participants of fusion complex formation during exocytotic processes, and syntaxin 1A is known to be present in the plasma membrane. Here, we show the presence of not only synaptotagmin I but also syntaxin 1A in secretory granules of bovine adrenal chromaffin cells by immunogold electron microscopy, and further demonstrate the interaction of these proteins with chromogranins A and B (CGA and CGB), two major proteins of secretory granules. Interaction between chromogranins and the components of fusion complex also suggests active participation of CGA and CGB in fusion complex formation and subsequent exocytosis.
The effect of synthetic glucocorticoid, dexamethasone on CYP1A1 inducibility in adult rat and human hepatocytes
Authors: Monostory Katalin , Kőhalmy Krisztina , Prough Russell A. , Kóbori László , Vereczkey László
Published: December 2004

Glucocorticoids act synergistically with polycyclic aromatic hydrocarbons in increasing mRNA and protein levels of CYP1A1 in rat liver. The action of dexamethasone to modify CYP1A1 expression has been investigated in adult human hepatocytes. The effect of dexamethasone on the induction of CYP1A1 by 3‐methylcholanthrene is different in rat and human liver cells. Dexamethasone potentiates the induction of CYP1A1 about 3‐ to 4‐fold in rat cells. In human hepatocytes, it reduces CYP1A1 induction by 50–60% at enzyme protein level, while it does not have an effect on CYP1A1 mRNA amount.
Men, Women and the Dynamics of Presidential Approval
Authors: CLARKE HAROLD D. , STEWART MARIANNE C. , AULT MIKE , ELLIOTT EUEL
Published: December 2004

Although commentary on the ‘gender gap’ is a staple of political discourse in the United States, most analyses of the dynamics of presidential approval have ignored possible gender differences in the forces driving approval ratings of US presidents. This article analyses gender differences in the impact of economic evaluations and political interventions on the dynamics of presidential approval between 1978 and 1997. The analyses are made possible by disaggregating 240 monthly Survey of Consumers datasets gathered over this period. These data show that women's economic evaluations are consistently more pessimistic than men's, regardless of who occupied the Oval Office. Analyses of rival presidential approval models reveal that a national prospective economic evaluation model performs best for women, but a personal prospective model works best for men. Parameter estimates indicate that economic evaluations accounted for substantial proportions of gender differences in presidential approval in the post-Carter era. Men and women also reacted differently to presidential transitions, with approval increasing more among men when Reagan replaced Carter, and more among women when Clinton replaced Bush. The hypothesis that men are more susceptible than women to rally effects induced by domestic and international crises and wars does not receive consistent support.
Social Movements and Deliberative Democratic Theory
Authors: MEDEARIS JOHN
Published: December 2004

Deliberative democrats are committed both to inclusion and to barring coercion in public discourse. Their commitment to democratic inclusion should make them sympathetic to the challenges faced by social movements. An adequate sociology of contentious public discourse, however, shows that social movements must often act coercively in order to be included. For example, they must often alter the terrain of conflict, create a crisis, pressure interlocutors to argue consistently, or compel other parties to enter social arenas of contention that they have avoided. Democratic theorists who are committed to inclusion should approve of such coercion. Under the actual circumstances movements face, there is a tension between non-coercion and democratic inclusion. This tension demonstrates the need for a democratic standard and a mode of democratic social analysis beyond those that deliberative theory offers.
Electoral Reforms, Membership Stability and the Existence of Committee Property Rights in American State Legislatures
Authors: SQUIRE PEVERILL , HAMM KEITH E. , HEDLUND RONALD D. , MONCRIEF GARY F.
Published: December 2004

One of the most creative theories advanced about legislative organization in recent years is Katz and Sala's linkage of the development of committee property rights in the US House of Representatives to the introduction of the Australian ballot. Katz and Sala argue that the Australian ballot – a government-printed ballot cast in secret that replaced a party-produced ballot that was cast in public – gave members of the House an incentive to pursue personal constituency votes. This, in turn, led to the rise of committee property rights as members sought to keep their committee assignments from term to term because of the potential electoral benefits they derived from them.

In this Note we use the state legislative committee membership dataset collected by Hamm and Hedlund and their colleagues to test whether committee property rights appeared in American state legislatures at roughly the same time as Katz and Sala find they emerged in the US House. State legislatures were, of course, exposed to the same electoral innovation at the same time. But, while in some ways state legislatures were much like Congress as organizations, in other ways they were very different. Our cross-sectional data and the variance in important institutional variables they provide allow us to test a critical proposition about the importance of membership stability rates in mediating the rise of committee property rights. We also go beyond Katz and Sala's analysis by testing to see if differences in Australian ballot design (office column and party bloc) across the states influenced the behaviour of legislators in the way their theory suggests.
MALE CIRCUMCISION AND SEXUALLY TRANSMITTED INFECTIONS IN BOTSWANA
Authors: LANGENI TABITHA
Published: December 2004

This study set out to investigate the influence of male circumcision and other factors on sexually transmitted infections in Botswana. A syndromic approach, which diagnoses a sexually transmitted infection based on the presence of urethral discharge or genital ulcers rather than on laboratory tests, was used. The data were from the 2001 Botswana AIDS Impact Survey where a nationally representative, randomly selected sample of men and women aged 10–64 years were interviewed in both urban and rural areas. The sample selected for this study consisted of 216,480 men aged 15–64 years who had ever had sexual intercourse. The logistic regression technique was executed to examine the association between male circumcision and self-reported urethral discharge or genital ulcers, while controlling for all other independent variables in the analysis. The main finding of this study was that among men who are circumcised, the odds for self-reported urethral discharge or genital ulcers are significantly lower than for those men who are not circumcised in both urban and rural Botswana. The analysis also showed that the odds in favour of self-reported urethral discharge or genital ulcers, for men who drink alcohol, are twice as large as those for men who do not drink alcohol, controlling for all other independent variables in the analysis. Religion and ethnicity also came through as factors exerting a protective influence against self-reported symptoms of sexually transmitted infections. The conclusion is that while male circumcision appears to be significantly associated with the risk for self-reported urethral discharge or genital ulcers, it is man’s behaviour, irrespective of ethnicity or religious dictates, that continues to play a vital role in protection against self-reported symptoms of sexually transmitted infections in Botswana.
MEASURING THE CHILDBEARING MOTIVATION OF COUPLES REFERRED TO THE SHIRAZ HEALTH CENTER FOR PREMARITAL EXAMINATIONS
Authors: PEZESHKI MOHAMMAD Z. , ZEIGHAMI BAHRAM , MILLER WARREN B.
Published: December 2004

Millions of children who were born during the first decade after the Islamic revolution in Iran are now reaching the age of marriage and childbearing. Short spacing between marriage and the birth of the first child has the potential to cause an excessive and costly increase in the growth of population in Iran. Research into the motivations for the birth of first child among newly married couples can create a knowledge base that will enable health centres to help these couples make better decisions about the timing of their first pregnancy. Using a consecutive sampling technique and administering Miller’s Childbearing Questionnaire, data were gathered regarding the childbearing motivations and desires of 300 couples who had been referred to the Shiraz Health Center for premarital counselling. The Childbearing Questionnaire, with some minor modifications, was found to be a valid and reliable instrument for measuring the childbearing motivations of newly married couples of Shiraz County, Fars Province, Iran. The utility of these findings for counselling in health centres is discussed. Based on the results, a longitudinal study is being designed that will allow the development of models for predicting the time of first pregnancy after marriage.
Cobalt ions inhibit negative feedback in the outer retina by
blocking hemichannels on horizontal cells
Authors: FAHRENFORT I. , SJOERDSMA T. , RIPPS H. , KAMERMANS M.
Published: December 2004

In goldfish, negative feedback from horizontal cells to cones shifts
the activation function of the Ca2+ current of the cones to
more negative potentials. This shift increases the amount of
Ca2+ flowing into the cones, resulting in an increase in
glutamate release. The increased glutamate release forms the basis of
the feedback-mediated responses in second-order neurons, such as the
surround-induced responses of bipolar cells and the spectral coding of
horizontal cells. Low concentrations of Co2+ block these
feedback-mediated responses in turtle retina. The mechanism by which
this is accomplished is unknown. We studied the effects of
Co2+ on the cone/horizontal network of goldfish retina
and found that Co2+ greatly reduced the feedback-mediated
responses in both cones and horizontal cells in a GABA-independent way.
The reduction of the feedback-mediated responses is accompanied by a
small shift of the Ca2+ current of the cones to positive
potentials. We have previously shown that hemichannels on the tips of
the horizontal cell dendrites are involved in the modulation of the
Ca2+ current in cones. Both the absence of this
Co2+-induced shift of the Ca2+ current in the
absence of a hemichannel conductance and the sensitivity of Cx26
hemichannels to low concentrations of Co2+ are consistent
with a role for hemichannels in negative feedback from horizontal cells
to cones.
Visual sensitivity across the menstrual cycle
Authors: EISNER ALVIN , BURKE SARA N. , TOOMEY MAUREEN D.
Published: December 2004

This study was designed to evaluate the hypothesis that hormonal
change can affect lower level light-adaptation processes, which are
likely to be retinally based. Foveal visual sensitivities were measured
across several menstrual cycles of four women not using hormonally
acting medication and across several menstrual cycles of three women
using a triphasic oral contraceptive. One woman, diagnosed with
premenstrual syndrome (PMS), was a subject for both groups.
Sensitivities were measured for a series of test wavelengths for 580-nm
backgrounds of 2.0 and 4.0 log td. Of the six individuals tested, one
had clear evidence of visual-adaptation changes occurring in phase with
the menstrual cycle. Prior to using the oral contraceptive, this
individual (the PMS subject) experienced changes of
short-wavelength-sensitive (SWS)-cone-mediated sensitivities of up to
about 1.4 log unit on the 4.0 log td background. Her SWS-cone-mediated
sensitivities tended to be highest near ovulation and lowest
premenstrually. Threshold-versus-illuminance (TVI) curves confirmed
that the rate of sensitivity decrease with increasing background
illuminance (i.e. the TVI slope) was greater premenstrually. The degree
of background-induced desensitization within her
middle-wavelength-sensitive (MWS)/long-wavelength-sensitive (LWS)
cone pathways also appeared to vary cyclically, but the magnitude of
the variation was smaller and the time course appeared to be different.
When this subject began oral contraceptive use, the patterns of
sensitivity change were all altered. None of the other five subjects
experienced changes of SWS-cone-mediated vision that were cyclic and
significantly adaptation-state dependent. However, there was evidence
for a limited degree of cyclic adaptation change within the MWS/LWS
cone pathways of at least one additional subject. We conclude that
hormonal change can—for some unknown proportion of women—be
linked to alterations of retinal function. However, the alterations are
not the same for all visual pathways, and there are pronounced
individual differences. The data also demonstrate that
individuals' visual adaptation capabilities can vary substantially
over periods of weeks.
Origins of the electroretinogram oscillatory potentials in the
rabbit retina
Authors: DONG CUN-JIAN , AGEY PETER , HARE WILLIAM A.
Published: December 2004

The electroretinogram (ERG) oscillatory potential (OP) is a
high-frequency, low-amplitude potential that is superimposed on the
rising phase of the b-wave. It provides noninvasive evaluation
of inner retina function in vivo and is a useful tool in basic
research as well as in the clinic. While the OP is widely believed to
be generated mainly by activity of the inner retina, the exact
underlying neural mechanisms are not well understood. We have
investigated the retinal mechanisms that underlie OP generation in
Dutch-belted rabbits. The OP was isolated by band-filtering
(100–1000 Hz) ERG signals. We used pharmacological agents that
block specific transmitter receptors or voltage-gated channels in order
to examine contributions of various retinal mechanisms to OP
generation. Our results show that the OP elicited by a bright brief
flash can be classified into early, intermediate, and
late subgroups that are likely generated mainly by
photoreceptors, action-potential-independent, and
action-potential-dependent mechanisms in the ON pathway of the inner
retina, respectively. ON bipolar cells themselves make only a small
direct contribution to OP generation, as do horizontal cells
and neurons in the OFF pathway.
The computational basis of an identified neuronal circuit for elementary motion detection in dipterous insects
Authors: HIGGINS CHARLES M. , DOUGLASS JOHN K. , STRAUSFELD NICHOLAS J.
Published: December 2004

Based on comparative anatomical studies and electrophysiological experiments, we have identified a conserved subset of neurons in the lamina, medulla, and lobula of dipterous insects that are involved in retinotopic visual motion direction selectivity. Working from the photoreceptors inward, this neuronal subset includes lamina amacrine (α) cells, lamina monopolar (L2) cells, the basket T-cell (T1 or β), the transmedullary cell Tm1, and the T5 bushy T-cell. Two GABA-immunoreactive neurons, the transmedullary cell Tm9 and a local interneuron at the level of T5 dendrites, are also implicated in the motion computation. We suggest that these neurons comprise the small-field elementary motion detector circuits the outputs of which are integrated by wide-field lobula plate tangential cells. We show that a computational model based on the available data about these neurons is consistent with existing models of biological elementary motion detection, and present a comparable version of the Hassenstein-Reichardt (HR) correlation model. Further, by using the model to synthesize a generic tangential cell, we show that it can account for the responses of lobula plate tangential cells to a wide range of transient stimuli, including responses which cannot be predicted using the HR model. This computational model of elementary motion detection is the first which derives specifically from the functional organization of a subset of retinotopic neurons supplying the lobula plate. A key prediction of this model is that elementary motion detector circuits respond quite differently to small-field transient stimulation than do spatially integrated motion processing neurons as observed in the lobula plate. In addition, this model suggests that the retinotopic motion information provided to wide-field motion-sensitive cells in the lobula is derived from a less refined stage of processing than motion inputs to the lobula plate.