bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification and characterization of a chemotolerant alcohol dehydrogenase applicable to coupled redox reactions
Authors: Kosjek Birgit , Stampfer Wolfgang , Pogorevc Mateja , Goessler Walter , Faber Kurt , Kroutil Wolfgang
Published: March 2004

The purification and characterization of an organic solvent tolerant, NADH‐dependent medium‐chain secondary alcohol dehydrogenase (denoted sec‐ADH “A”) from Rhodococcus ruber DSM 44541 is reported. The enzyme can withstand elevated concentrations of organic solvents, such as acetone (up to 50% v/v) and 2‐propanol (up to 80% v/v). Thus, it is ideally suited for the preparative‐scale enantioselective oxidation of sec‐alcohol and the asymmetric reduction of ketones, using acetone and 2‐propanol, respectively, as cosubstrates for cofactor‐regeneration via a coupled‐substrate approach. The homodimeric protein was found to bear tightly bound zinc and displayed a molecular mass of 38 kDa per subunit as determined by SDS gel electrophoresis. The optimal temperature ranged from 30–50°C and the half‐life at 50°C was 35 h. In addition, excellent storage stability was found. The pH optimum for reduction is pH 6.5; pH 9.0 is preferred for oxidation. The enzyme followed a sequential reaction mechanism. The substrates are medium chain sec‐alcohols or (ω‐1)‐ketones; primary alcohols or aldehydes are not accepted. © 2004 Wiley Periodicals, Inc.
Mimicking the Escherichia coli cytoplasmic environment activates long‐lived and efficient cell‐free protein synthesis
Authors: Jewett Michael C. , Swartz James R.
Published: March 2004

Cell‐free translation systems generally utilize high‐energy phosphate compounds to regenerate the adenosine triphosphate (ATP) necessary to drive protein synthesis. This hampers the widespread use and practical implementation of this technology in a batch format due to expensive reagent costs; the accumulation of inhibitory byproducts, such as phosphate; and pH change. To address these problems, a cell‐free protein synthesis system has been engineered that is capable of using pyruvate as an energy source to produce high yields of protein. The “Cytomim” system, synthesizes chloramphenicol acetyltransferase (CAT) for up to 6 h in a batch reaction to yield 700 μg/mL of protein. By more closely replicating the physiological conditions of the cytoplasm of Escherichia coli, the Cytomim system provides a stable energy supply for protein expression without phosphate accumulation, pH change, exogenous enzyme addition, or the need for expensive high‐energy phosphate compounds. © 2004 Wiley Periodicals, Inc.
Glycoforms of β‐lactoglobulin with improved thermostability and preserved structural packing
Authors: Broersen Kerensa , Voragen Alphons G. J. , Hamer Rob J. , de Jongh Harmen H. J.
Published: March 2004

In this article we show how various degrees of glycosylation can be used to control the thermal stability of proteins. The primary amines of β‐lactoglobulin were glycosylated with glucose or fructose within a range of non‐denaturing reaction parameters. The modified fractions were characterized and analyzed for structural stability and hydrophobic exposure. The modification procedure gave rise to the production of glycoproteins with a well‐defined Gaussian distribution, where glucose appeared more reactive than fructose. The integrity of the secondary, tertiary, and quaternary structures remained unaffected by the modification procedure. However, upon heating the stability of the modified fractions increased up to 6 K. Here we demonstrate the effects on the thermodynamic properties of proteins by glycosylation; this work serves as a first step in understanding and controlling the process underlying aggregation of glycosylated proteins. © 2004 Wiley Periodicals, Inc.
Haloalkane hydrolysis by Rhodococcus erythropolis cells: Comparison of conventional aqueous phase dehalogenation and nonconventional gas phase dehalogenation
Authors: Erable Benjamin , Goubet Isabelle , Lamare Sylvain , Legoy Marie Dominique , Maugard Thierry
Published: March 2004

Biofiltration of air polluted by volatile organic compounds is now recognized by the industrial and research communities as an effective and viable alternative to standard environmental technologies. Whereas many studies have focused on solid/liquid/gas biofilters, there have been fewer reports on waste air treatment using other biological processes, especially in a solid/gas biofilter. In this study, a comparison was made of the hydrolysis of halogenated compounds (such as 1‐chlorobutane) by lyophilized Rhodococcus erythropolis cells in a novel solid/gas biofilter and in the aqueous phase. We first determined the culture conditions for the production of R. erythropolis cells with a strong dehalogenase activity. Four different media were studied and the amount of 1‐chlorobutane was optimized. Next, we report the possibility to use R. erythropolis cells in a solid/gas biofilter in order to transform halogenated compounds in corresponding alcohols. The effect of experimental parameters (total flow into the biofilter, thermodynamic activity of the substrates, temperature, carbon chain length of halogenated substrates) on the activity and stability of lyophilized cells in the gas phase was determined. A critical water thermodynamic activity (aw) of 0.4 is necessary for the enzyme to become active and optimal dehalogenase activity for the lyophilized cells is obtained for an aw of 0.9. A temperature of reaction of 40°C represents the best compromise between stability and activity. Activation energy of the reaction was determined and found equal to 59.5 KJ/mol. The pH effect on the dehalogenase activity of R. erythropolis cells was also studied in the gas phase and in the aqueous phase. It was observed that pH 9.0 provided the best activity in both systems. We observed that in the aqueous phase R. erythropolis cells were less sensitive to the variation in pH than R. erythropolis cells in the gas phase. Finally, the addition of volatile Lewis base (triethylamine) in the gaseous phase and the action of the lysozyme in order to permeabilize the cells was found to be highly beneficial to the effectiveness of the biofilter. © 2004 Wiley Periodicals, Inc.
Recombinant protein purification from pea
Authors: Menkhaus Todd J. , Pate Cynthia , Krech Anthony , Glatz Charles E.
Published: March 2004

To assess the suitability of transgenic peas as a host for protein production from the perspective of ease of recovery, a strain containing recombinant β‐glucuronidase with poly(histidine) tail (GUSH6) was evaluated for solubility of the target protein in relation to native components (proteins, carbohydrates, and phenolics). Recovery of the recombinant GUSH6 from aqueous extracts by immobilized metal affinity chromatography with coupled Co2+ yielded a nearly pure product with IDA (enrichment factor (EF) = 260) or NTA (EF = 200) resin. Single‐step recoveries were also possible by isoelectric precipitation (EF = 4), polyelectrolyte precipitation (EF = 1.5), and anion‐exchange chromatography (EF = 3.1), but enrichment factors were low. © 2004 Wiley Periodicals, Inc.
Immobilization of DNAzyme as a thermostable biocatalyst
Authors: Ito Yoshihiro , Hasuda Hirokazu
Published: March 2004

Deoxyribozyme (DNAzyme) carrying peroxidase activity was immobilized on two types of particles and the enzymatic activity was measured. The DNA recognizing porphyrin were prepared according to Travascio et al. ([1998] Chem Biol 5:505–517) and the interactions with hemin were investigated by ultraviolet absorbance and circular dichroism spectroscopies. The DNA interacted with hemin and significant conformational change was induced by the interaction. Therefore, the end of this DNA was modified with a thiol group and it was immobilized on thiol‐containing polysaccharide beads or on gold particles. The DNA immobilized on the gold particle showed activity catalyzing the peroxidation reaction. No significant reduction of activity was observed even after immobilization. The immobilized DNAzyme could be repeatedly utilized without significant loss of activity. In addition, heat treatment did not reduce the activity, although a protein enzyme, horseradish peroxidase, lost its activity after the heat treatment. The repertoire of DNAzyme is still currently limited. However, in the future the utilization of DNAzyme in the field of biotechnology will be important with the increase of discoveries of new functional DNAzymes. © 2004 Wiley Periodicals, Inc.
Effect of xylan and lignin removal by batch and flowthrough pretreatment on the enzymatic digestibility of corn stover cellulose
Authors: Yang Bin , Wyman Charles E.
Published: March 2004

Compared with batch systems, flowthrough and countercurrent reactors have important potential advantages for pretreating cellulosic biomass, including higher hemicellulose sugar yields, enhanced cellulose digestibility, and reduced chemical additions. Unfortunately, they suffer from high water and energy use. To better understand these trade‐offs, comparative data are reported on xylan and lignin removal and enzymatic digestibility of cellulose for corn stover pretreated in batch and flowthrough reactors over a range of flow rates between 160° and 220°C, with water only and also with 0.1 wt% sulfuric acid. Increasing flow with just water enhanced the xylan dissolution rate, more than doubled total lignin removal, and increased cellulose digestibility. Furthermore, adding dilute sulfuric acid increased the rate of xylan removal for both batch and flowthrough systems. Interestingly, adding acid also increased the lignin removal rate with flow, but less lignin was left in solution when acid was added in batch. Although the enzymatic hydrolysis of pretreated cellulose was related to xylan removal, as others have shown, the digestibility was much better for flowthrough compared with batch systems, for the same degree of xylan removal. Cellulose digestibility for flowthrough reactors was related to lignin removal as well. These results suggest that altering lignin also affects the enzymatic digestibility of corn stover. © 2004 Wiley Periodicals, Inc.
Relation between the duration of remission and hyperglycemia during induction chemotherapy for acute lymphocytic leukemia with a hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone/methotrexate–cytarabine regimen
Authors: Weiser Mary Ann , Cabanillas Maria E. , Konopleva Marina , Thomas Deborah A. , Pierce Sherry A. , Escalante Carmen P. , Kantarjian Hagop M. , O'Brien Susan M.
Published: March 2004

BACKGROUND

Hyperglycemia, which is not uncommon during the treatment of acute lymphocytic leukemia (ALL), has been shown to be an independent predictor of adverse outcomes among hospitalized patients with undiagnosed diabetes; it also may have the potential to affect leukemic cell proliferation through altered metabolism. The purpose of the current study was to determine the prevalence of hyperglycemia during induction chemotherapy for ALL using a regimen comprised of hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (Hyper‐CVAD) and to determine its effect on survival, duration of disease remission, and treatment‐related complications.

METHODS

Two hundred seventy‐eight adult patients with previously untreated ALL who achieved a complete remission with the hyper‐CVAD regimen were evaluated. Hyperglycemia was defined as ≥ 2 glucose determinations of ≥ 200 mg/dL during the first 30 days of induction chemotherapy. Induction chemotherapy was comprised of fractionated cyclophosphamide at a dose of 300 mg/m2 twice daily on Days 1–3, doxorubicin at a dose of 50 mg/m2 on Day 4, vincristine at a dose of 2 mg on Days 4 and 11, and dexamethasone at a dose of 40 mg on Days 1–4 and Days 11–14 (hyper‐CVAD). Hyper‐CVAD, given in odd‐number courses (Courses 1, 3, 5, and 7), was alternated with methotrexate and cytarabine (MTX/Ara‐C), given in even‐number courses (Courses 2, 4, 6, and 8). MTX/Ara‐C was comprised of MTX at a dose of 200 mg/m2 over 2 hours followed by 800 mg/m2 over 22 hours on Day 1, Ara‐C at a dose of 3 g/m2 every 12 hours for 4 doses over 2 days (Days 2 and 3), and intravenous methylprednisolone given at a dose of 50 mg twice daily on Days 1–3. The complete remission duration (CRD), survival, and treatment‐related complications were determined for patients with and without hyperglycemia; differences between the two groups were assessed using standard statistical methods.

RESULTS

Hyperglycemia was found to occur in 103 patients (37%). Patients with hyperglycemia had a shorter median CRD (24 months vs. 52 months; P = 0.001) and a shorter median survival (29 months vs. 88 months; P < 0.001); they also were more likely to develop sepsis (16.5% vs. 8.0%; P = 0.03) or any complicated infection (sepsis, pneumonia, or fungal) (38.8% vs. 25.1%; P = 0.016) compared with patients without hyperglycemia.

CONCLUSIONS

Patients with hyperglycemia during induction chemotherapy for ALL with the hyper‐CVAD regimen were found to have a shorter CRD, experience a significant increase in overall mortality, and be at an increased risk for developing complicated infections. Cancer 2004. © 2004 American Cancer Society.
Effect of noisy carrier reference signal and interference on performance of MSK receiver
Authors: Stefanovic Mihajlo C. , Draca Dragan Lj. , Vidovic Aleksandra Z.
Published: March 2004

This paper considers the coherent detection of minimum shift keying signal and a degradation in error rate performance from ideal due to an interference and a phase discrepancy between the carrier of the received signal and the carrier of the receiver. The error rate is calculated for the simple receiver model with integrate‐and‐dump circuits. The reference carrier signal unsteadiness is presented by the probability density function of the first order non‐linear PLL phase error, while the uncertainty due to an interference is involved in the system model with a random phase of cosine signal that accompanied the useful signal. Copyright © 2004 John Wiley & Sons, Ltd.
Burst scheduling for differentiated services in optical burst switching WDM networks
Authors: Liu David Q. , Liu Ming T.
Published: March 2004

Optical burst switching (OBS) is one of the most important switching technologies for future optical wavelength division multiplexing (WDM) networks and the Internet. The model of differentiated services has been proposed to support quality of service (QoS) in the IP‐based Internet. It is also very important to have differentiated service support in OBS networks. When the burst scheduling in an OBS network is set up appropriately, network can support differentiated services. In this paper, we proposed a new burst scheduling scheme, calleddifferentiated scheduling with identical priority offset time(DSIPO). In DSIPO, the same priority offset time is used for all the bursts destined to the same edge node regardless of their priorities. Differentiated services in terms of burst loss probability are achieved by processing the control packets of higher priority class bursts, thus reserving resources for their data bursts, more promptly upon their arrival than those of lower priority class bursts. Each intermediate (core) node can adjust the burst loss probabilities of various burst classes by choosing its owndifferentiated processing delayvalue for each priority class or its owndifferentiated processing delay differencevalue between any pair of adjacent priority classes. We model and analyse DSIPO in terms of the burst loss probability for each priority class with simulation validation. The performance of DISPO is evaluated by simulation. Copyright © 2004 John Wiley & Sons, Ltd.
Adaptive directional‐aware location update strategy
Authors: Tung Tracy , Jamalipour Abbas
Published: March 2004

In this paper, a new tracking strategy, the directivity‐aware location updating scheme was developed to better utilize the distinct characteristics of individual users on travelling directions. In this new adaptive scheme, an optimal distance‐based update threshold is selected according to the call‐to‐mobility ratio and a transitional directivity index, introduced to give indications of the mobile's travelling patterns. It is found that as far as mobility characteristics are concerned, the actual transitional direction of roaming mobiles plays a significant role in selecting the optimal threshold in addition to the usual perception about mobility rate. Its advantage becomes even more visible when an optimal threshold is not theoretically obtainable due to certain restrictions imposed by the network during times of high system loadings. Simulation results show that the additional information made available about roaming mobile's transitional directivity is critical to ensure that the best available sub‐optimal threshold is realizable. Other advances in this paper include the simplification of existing Markovian movement model. With the improved model presentation, the number of states necessary to simulate such memoryless movements is reduced. Consequently, the computational complexity involved is also lessened. Copyright © 2004 John Wiley & Sons, Ltd.
Exploring the performance of TCP vegas in mobilead hocnetworks
Authors: Papanastasiou Stylianos , Ould‐Khaoua Mohamed
Published: March 2004

Recent research efforts in mobilead hocnetworks have concentrated on examining the behaviour of TCP Reno over variousad hocrouting protocols and have suggested a number of extensions to improve its performance. TCP Vegas, which takes a proactive approach to congestion avoidance, has not so far been examined as a viable alternative to TCP Reno in wireless environments and no effort has been made to analyse its performance over routing protocols for MANETs. This paper evaluates using extensive simulation experiments the performance behaviour of TCP Vegas over a proactive (destination sequenced distance vector) and two reactive (dynamic source routing andad hocon demand distance vector) routing protocols and compares it against that of TCP Reno. Copyright © 2004 John Wiley & Sons, Ltd.
N,N‐Dialkylcarbamato Lanthanide Complexes, a Series of Isotypical Coordination Compounds
Authors: Baisch Ulrich , Belli Dell’Amico Daniela , Calderazzo Fausto , Labella Luca , Marchetti Fabio , Merigo Alessandra
Published: March 2004

The preparations of the N,N‐dialkylcarbamato complexes with analytical formulae [Ln(O2CNR2)3] (Ln = Pr, Nd, Eu, Gd, Ho, Er, Yb, Lu, R = iPr; Ln = Nd, Eu, Gd, R = Bu; Ln = Nd, R = Et), using [LnCl3(ether)x] (ether = THF or dimethoxyethane, DME), NHR2, and CO2 are reported. X‐ray diffraction of the diisopropylcarbamato derivatives, including a reinvestigation of [Yb4(O2CNiPr2)12], showed these complexes to be tetranuclear and isotypical over a range of 12 atomic numbers. The lanthanide contraction has been evaluated based on the lengths of four different types of Ln−O bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
γ‐Linolenic acid content and fatty acid composition of Boraginaceae seed oils
Authors: Erdemoglu Nurgun , Kusmenoglu Senay , Vural Mecit
Published: March 2004

Eleven species of the Boraginaceae family collected in Turkey were analyzed with respect to the amount of γ‐linolenic acid as well as fatty acid composition. γ‐Linolenic acid was found in all species, except for Heliotropium lasiocarpum Fisch. & Mey. and Heliotropium dolosum De Not. Seed oil content ranged from 1.5% in H. lasiocarpum to 22.0% in Anchusa leptophylla ssp. leptophylla. The content of γ‐linolenic acid ranged from 1.7% of total fatty acids in Paracaryum racemosum (Schreber) Britten var. racemosum to 13.7% in A. leptophylla Roemer & Shultes ssp. leptophylla. According to data from our study, A. leptophylla ssp. leptophylla (13.7%), Anchusa azurea Miller var. azurea (11.9%) and Echium plantagineum L. (12.2%) might be considered as new sources of γ‐linolenic acid.
Controls on modern alluvial fan processes in the central Alps, northern Italy
Authors: Crosta Giovanni B. , Frattini Paolo
Published: March 2004

Alluvial fan development in Alpine areas is often affected by catastrophic sedimentary processes associated with extreme ﬂoods events, causing serious risks for people living on the fans. Hazard assessment in these areas depends on proper identiﬁcation of the dominant sedimentary processes on the fans.

Data from a set of 209 alluvial fans from the central Alps of Italy are presented in this paper and analysed with the help of various statistical techniques (linear regression, principal components analysis, cluster analysis, discriminant analysis and logistic regression). First, we used modern sedimentary facies and historical records (ﬂood events since 15th century), to distinguish between the two dominant sedimentary processes on alluvial fans: debris ﬂows and streamﬂows. Then, in order to analyse the main controls on past and present fan processes, 36 morphological, geological and land‐use variables were analysed. As with observations for arid‐environment fans, catchment morphology is the most inﬂuential factor in the study area, whereas geology and land use are minor controls. The role of climatic change and landsliding within the catchments also seems to be very important and is discussed. Statistical techniques also help in differentiating groups of alluvial fans by sets of controlling factors, including stage and type of evolution. Finally, by using discriminant analysis and logistic regression, we classiﬁed alluvial fans according to the dominant sedimentary process, with a success rate ranging between 75 and 92 per cent. Copyright © 2004 John Wiley & Sons, Ltd.
Morphometric controls and geomorphic responses on fans in the Southern Alps, New Zealand
Authors: de Scally Fes A. , Owens Ian F.
Published: March 2004

Morphometric variables associated with 41 debris‐ﬂow and 18 ﬂuvial fans and their basins in the Southern Alps of New Zealand are examined. The results show statistically signiﬁcant differences in the area, maximum elevation, relief and ruggedness (Melton's R) of the basin and the area, gradient, and apex and toe elevations of the fan between debris‐ﬂow and ﬂuvial sites. Concavity of the fan longitudinal proﬁle also differs between the two fan types, although this could not be tested statistically. Most of these morphometric differences reﬂect differences in processes and environmental controls on them. Discriminant analysis indicates that basin area and fan gradient best differentiate the two fan types by process. Moderately strong correlations exist, on both debris‐ﬂow and ﬂuvial fans, between basin area or Melton's R and fan area. Correlations between basin area or Melton's R and fan gradient are generally weaker. The results of this study also indicate that on debris‐ﬂow‐prone fans the fan gradient and basin Melton's R have lower thresholds which overlap little with upper thresholds associated with basins where only streamﬂow reaches the fan. These thresholds may therefore have value in preliminary morphometric assessments of debris‐ﬂow hazard on fans in the Southern Alps. Copyright © 2004 John Wiley & Sons, Ltd.
Use of a three‐dimensional laser scanner to digitally capture the topography of sand dunes in high spatial resolution
Authors: Nagihara Seiichi , Mulligan Kevin R. , Xiong Wei
Published: March 2004

We herein report the results of a ﬁeld study that was designed to test the feasibility of using ground‐based LIDAR to map the topography of a sand dune in high spatial resolution. A portable Cyrax 2500 three‐dimensional (3D) laser scanner was used to digitally capture the topography of a barchan, roughly 4 m tall and 50 m long, located in the White Sands National Monument, New Mexico. We performed eleven scans around the barchan and obtained the elevation relative to the inter‐dune ﬂat at roughly 1/4 million points on the dune surface. The elevation point data were then interpolated to yield a continuous surface model of the dune topography with c. 10 cm spatial resolution and c. 6 mm position accuracy. The results from this ﬁeld study clearly demonstrate the potential of ground‐based LIDAR as a mapping tool for use in aeolian research and other earth science applications. The 3D surface model of the dune can describe the morphology with hitherto unprecedented detail. Moreover, the surface of the dune is mapped with a minimum of foot trafﬁc on the dune itself. Copyright © 2004 John Wiley & Sons, Ltd.
Processes of silicate karstification associated with pan formation in the Darwin–Koolpinya area of northern Australia
Authors: Borger H. , Mcfarlane M. J. , Ringrose S.
Published: March 2004

Lyons Lagoon, one of many small pans near Darwin, Northern Australia, occurs in lateritized terrain. Formation by structurally facilitated silicate karstiﬁcation of the parent Cretaceous sandy sediments was earlier proposed. This paper presents the results of thin section microscopy and scanning electron microscopy with energy‐dispersive X‐ray study of pan sediments with a view to assessing the extent to which they reﬂect the geomorphological/hydrogeological history. Severe corrosion was found to overprint the impact features of the primary sands, attributed to aggressive leaching and consistent with formation of the depression by karstiﬁcation when the water table was low. Formation of a smectitic matrix is considered to have followed when the water table was high. Upon subsequent lowering of the water level leaching was resumed, altering smectite to kaolinite and resulting in incongruent dissolution of kaolinite to leave a siliceous residuum. At least two cycles of high followed by low water levels are recognized. Such periodic changes of levels are considered essential to pan formation within freely draining lateritic terrain. The processes of pan formation and alteration of pan sediments (essentially residual deposits) is ongoing, biocorrosion being implicated as an important mechanism. Incongruent kaolinite dissolution, to leave a silica residuum, a hitherto apparently unrecognized process, raises the possibility that silcrete may form as a relative accumulation which is synchronous with lateritic leaching in more elevated topographic positions. Copyright © 2004 John Wiley & Sons, Ltd.
An outlier robust hierarchical Bayes model for forecasting: the case of Hong Kong
Authors: Chow William W.
Published: March 2004

This paper introduces a Bayesian forecasting model that accommodates innovative outliers. The hierarchical specification of prior distributions allows an identification of observations contaminated by these outliers and endogenously determines the hyperparameters of the Minnesota prior. Estimation and prediction are performed using Markov chain Monte Carlo (MCMC) methods. The model forecasts the Hong Kong economy more accurately than the standard V AR and performs in line with other complicated BV AR models. It is also shown that the model is capable of finding most of the outliers in various simulation experiments. Copyright © 2004 John Wiley & Sons, Ltd.
Do seasonal unit roots matter for forecasting monthly industrial production?
Authors: Kawasaki Yoshinori , Franses Philip Hans
Published: March 2004

We investigate the seasonal unit root properties of monthly industrial production series for 16 OECD countries within the context of a structural time series model. A basic version of this model assumes that there are 11 such seasonal unit roots. We propose to use model selection criteria (AIC and BIC) to examine if one or more of these are in fact stationary. We generally find that when these criteria indicate that a smaller number of seasonal unit roots can be assumed and hence that some seasonal roots are stationary, the corresponding model also gives more accurate one‐step‐ahead forecasts. Copyright © 2004 John Wiley & Sons, Ltd.
Bias‐corrected bootstrap prediction regions for vector autoregression
Authors: Kim Jae H.
Published: March 2004

This paper examines small sample properties of alternative bias‐corrected bootstrap prediction regions for the vector autoregressive (VAR) model. Bias‐corrected bootstrap prediction regions are constructed by combining bias‐correction of VAR parameter estimators with the bootstrap procedure. The backward VAR model is used to bootstrap VAR forecasts conditionally on past observations. Bootstrap prediction regions based on asymptotic bias‐correction are compared with those based on bootstrap bias‐correction. Monte Carlo simulation results indicate that bootstrap prediction regions based on asymptotic bias‐correction show better small sample properties than those based on bootstrap bias‐correction for nearly all cases considered. The former provide accurate coverage properties in most cases, while the latter over‐estimate the future uncertainty. Overall, the percentile‐t bootstrap prediction region based on asymptotic bias‐correction is found to provide highly desirable small sample properties, outperforming its alternatives in nearly all cases. Copyright © 2004 John Wiley & Sons, Ltd.
Recursive penalized least squares solution for dynamical inverse problems of EEG generation
Authors: Yamashita Okito , Galka Andreas , Ozaki Tohru , Biscay Rolando , Valdes‐Sosa Pedro
Published: March 2004

In the dynamical inverse problem of electroencephalogram (EEG) generation where a specific dynamics for the electrical current distribution is assumed, we can impose general spatiotemporal constraints onto the solution by casting the problem into a state space representation and assuming a specific class of parametric models for the dynamics. The Akaike Bayesian Information Criterion (ABIC), which is based on the Type II likelihood, was used to estimate the parameters and evaluate the model. In addition, dynamic low‐resolution brain electromagnetic tomography (LORETA), a new approach for estimating the current distribution is introduced. A recursive penalized least squares (RPLS) step forms the main element of our implementation. To obtain improved inverse solutions, dynamic LORETA exploits both spatial and temporal information, whereas LORETA uses only spatial information. A considerable improvement in performance compared to LORETA was found when dynamic LORETA was applied to simulated EEG data, and the new method was applied also to clinical EEG data. Hum. Brain Mapp. 21:221–235, 2004. © 2004 Wiley‐Liss, Inc.
Don't think of a white bear: An fMRI investigation of the effects of sequential instructional sets on cortical activity in a task‐switching paradigm
Authors: Wylie Glenn R. , Javitt Daniel C. , Foxe John J.
Published: March 2004

Using functional magnetic resonance imaging (fMRI), we investigated processes involved in switching between two ongoing tasks, thought to be paradigmatic of executive control processes. Subjects were considerably slower and less accurate when switching between two tasks than when repeatedly carrying out one task, so‐called “switch costs.” Switch costs, however, generally occur only when more than one task is associated with each stimulus type. This has led to the surmise that switch costs may be due largely to ongoing interference from previously learned stimulus‐response (S‐R) associations, which are no longer relevant for the task at hand. We used a paradigm that specifically assessed this hypothesis and investigated three stages. In Stage 1, a single task was carried out with each stimulus type; in Stage 2, a second novel task was introduced for each stimulus type; and in Stage 3, subjects reverted to carrying out solely the original tasks (as in Stage 1). In Stage 1, only one task was associated with each stimulus type, whereas two tasks were associated with each stimulus type in Stages 2 and 3. We compared images obtained during Stage 3 to those obtained during Stage 1 and show that during Stage 3, there was robust activation in the network of areas associated with the Stage 2 tasks, even though these tasks were no longer relevant. Our data strongly suggest that switch costs may derive largely from continued activation of areas associated with carrying out the now‐irrelevant task(s). We posit that a large component of executive control processes involves resolution of competition between potentially relevant tasks. Our data also revealed widespread activation of a frontoparietal network of areas, and we discuss how this network might be involved in mediating this competition. Hum. Brain Mapping 21:279–297, 2004. © 2004 Wiley‐Liss, Inc.
Functional coupling of simultaneous electrical and metabolic activity in the human brain
Authors: Oakes Terrence R. , Pizzagalli Diego A. , Hendrick Andrew M. , Horras Katherine A. , Larson Christine L. , Abercrombie Heather C. , Schaefer Stacey M. , Koger John V. , Davidson Richard J.
Published: March 2004

The relationships between brain electrical and metabolic activity are being uncovered currently in animal models using invasive methods; however, in the human brain this relationship remains not well understood. In particular, the relationship between noninvasive measurements of electrical activity and metabolism remains largely undefined. To understand better these relations, cerebral activity was measured simultaneously with electroencephalography (EEG) and positron emission tomography using [18f]‐fluoro‐2‐deoxy‐D‐glucose (PET‐FDG) in 12 normal human subjects during rest. Intracerebral distributions of current density were estimated, yielding tomographic maps for seven standard EEG frequency bands. The PET and EEG data were registered to the same space and voxel dimensions, and correlational maps were created on a voxel‐by‐voxel basis across all subjects. For each band, significant positive and negative correlations were found that are generally consistent with extant understanding of EEG band power function. With increasing EEG frequency, there was an increase in the number of positively correlated voxels, whereas the lower α band (8.5–10.0 Hz) was associated with the highest number of negative correlations. This work presents a method for comparing EEG signals with other more traditionally tomographic functional imaging data on a 3‐D basis. This method will be useful in the future when it is applied to functional imaging methods with faster time resolution, such as short half‐life PET blood flow tracers and functional magnetic resonance imaging. Hum. Brain Mapping 21:257–270, 2004. © 2004 Wiley‐Liss, Inc.
Change processes and ergonomic improvements in small and medium enterprises
Authors: Karltun Johan
Published: March 2004

This article deals with the question of how change processes can create ergonomic improvements in small‐ and medium‐sized industrial enterprises. Drawing on experiences from two described and analyzed case studies in small‐ and medium‐sized enterprises (SMEs) and from ISO 9000 implementation processes previously studied, a hypothetical change framework is suggested through a theory generating approach. It separates change into action‐driven change, which is an active experiential improvement process, and into vision‐driven change, which is of a visionary design character. The ability to bring about problem solving into action was important for the success of the change processes. Furthermore, the nature of different hampering mechanisms concerning ergonomic improvements is discussed. © 2004 Wiley Periodicals, Inc. Hum Factors Man 14: 135–155, 2004.
Employee involvement: Its interaction with advanced manufacturing technologies, quality management, and inter‐firm collaboration
Authors: Bayo‐Moriones Alberto , de Cerio Javier Merino‐Díaz
Published: March 2004

The goal of this article is to assess empirically the connection between different operations management decisions and the use of practices aimed at promoting the involvement of workers in the company. More specifically, the three operations management issues considered are the use of Advanced Manufacturing Technologies, the application of Quality Management tools, and the establishment of close relationships with customers and suppliers. Information relating to an initial sample of 965 Spanish manufacturing plants with at least fifty employees was used. Information was gathered through face‐to‐face interviews with a senior manager of each plant. To achieve the objective of the study, two different analyses were taken. First, the determinants of adoption of employee involvement practices were analyzed. Second, the interactive effects of employee involvement and operation management on firm performance were examined. Results show that Advanced Manufacturing Technologies, Quality Management, and close relationships with other firms have positive effects on the number of employee involvement practices used. However, no interactive effect was detected on firm performance of the simultaneous application of participatory practices and Advanced Manufacturing Technologies, Quality Management, and the establishment of close connections with customers and suppliers. © 2004 Wiley Periodicals, Inc. Hum Factors Man 14: 117–134, 2004.
System design in normative and actual practice: A comparative study of cognitive task allocation in advanced manufacturing systems
Authors: Papantonopoulos Sotiris
Published: March 2004

The Human Factors Engineering approach to human‐machine system design is based largely on normative design methods. This article suggests that the scope of Human Factors Engineering shall be extended to the descriptive study of system design in actual practice by the application of theoretical frameworks that emphasize the role of the system‐design practitioner and organization in the design process. A comparative study of system design in normative and actual practice was conducted in the design of cognitive task allocation in a Flexible Manufacturing System (FMS) cell. The study showed that the designers' allocation decisions were influenced strongly by factors related to their own design practices, yet exogenous to the tasks to be allocated. Theoretical frameworks from Design Research were applied to illustrate differences between normative and actual practice of system design. © 2004 Wiley Periodicals, Inc. Hum Factors Man 14: 181–196, 2004.
Macroergonomics as a large work‐system transformation technology
Authors: Kleiner B.M.
Published: March 2004

Traditional ergonomics has concentrated on improving such metrics as productivity, health, safety, and quality of work life. While such local improvements are important, increasingly, there is pressure upon ergonomists to achieve global improvement. This article reviews some of the basic concepts behind large‐scale change and takes the position that the macroergonomist is postured uniquely to induce and manage positive change in industrial organizations. While ergonomists focus at the human–machine interface level, organization‐intervention consultants typically focus at the organizational level. Macroergonomists uniquely concentrate their efforts at both levels. © 2004 Wiley Periodicals, Inc. Hum Factors Man 14: 101–115, 2004.
Qualitative research to make practical sense of sustainability in primary health care projects implemented by non‐governmental organizations
Authors: Sarriot Eric G. , Winch Peter J. , Ryan Leo J. , Edison Jay , Bowie Janice , Swedberg Eric , Welch Rikki
Published: March 2004

Sustainability continues to be a serious concern for Primary Health Care (PHC) interventions targeting the death of millions of children in developing countries each year. Our work with over 30 Non‐Governmental Organizations (NGOs) implementing USAID's Child Survival and Health Grants Program (CSHGP)‐funded projects revealed the need for a study to develop a framework for sustainability assessment in these projects. We surveyed NGO informants and project managers through semi‐structured interviews and questionnaires. This paper summarizes our study findings.

The NGOs share key values about sustainability, but are skeptical about approaches perceived as disconnected from field reality. In their experience, sustainable achievements occur through the interaction of capable local stakeholders and communities. This depends strongly on enabling conditions, which NGO projects should advance. Sustainability assessment is multidimensional, value‐based and embeds health within a larger sustainable development perspective. It reduces, but does not eliminate, the unpredictability of long‐term outcomes. It should start with the consideration of the ‘local systems’ which need to develop a common purpose.

Our ability to address the complexity inherent to sustainability thinking rests with the validity of the models used to design interventions. A participant, qualitative research approach helped us make sense of sustainability in NGO field practice. Copyright © 2004 John Wiley & Sons, Ltd.
A methodological approach and framework for sustainability assessment in NGO‐implemented primary health care programs
Authors: Sarriot Eric G. , Winch Peter J. , Ryan Leo J. , Bowie Janice , Kouletio Michelle , Swedberg Eric , LeBan Karen , Edison Jay , Welch Rikki , Pacqué Michel C.
Published: March 2004

An estimated 10.8 million children under 5 continue to die each year in developing countries from causes easily treatable or preventable. Non governmental organizations (NGOs) are frontline implementers of low‐cost and effective child health interventions, but their progress toward sustainable child health gains is a challenge to evaluate. This paper presents the Child Survival Sustainability Assessment (CSSA) methodology—a framework and process—to map progress towards sustainable child health from the community level and upward. The CSSA was developed with NGOs through a participatory process of research and dialogue.

Commitment to sustainability requires a systematic and systemic consideration of human, social and organizational processes beyond a purely biomedical perspective. The CSSA is organized around three interrelated dimensions of evaluation: (1) health and health services; (2) capacity and viability of local organizations; (3) capacity of the community in its social ecological context. The CSSA uses a participatory, action‐planning process, engaging a ‘local system’ of stakeholders in the contextual definition of objectives and indicators. Improved conditions measured in the three dimensions correspond to progress toward a sustainable health situation for the population. This framework opens new opportunities for evaluation and research design and places sustainability at the center of primary health care programming. Copyright © 2004 John Wiley & Sons, Ltd.
The human perspective on health care reform: coping with diabetes in Kyrgyzstan
Authors: Hopkinson Botagoz , Balabanova Dina , McKee Martin , Kutzin Joseph
Published: March 2004

Health systems world wide are confronted by the challenge of rising levels of chronic diseases. Yet existing approaches to health system analysis often fail to capture the complexity of the responses required to address this challenge. In this paper we describe the results of a pilot study using a rapid appraisal technique to assess the performance of the health care system in Kyrgyzstan, a former Soviet central Asian republic. The study focuses on diabetes, a condition whose effective management requires a coordinated response involving many components of the health care system. The study sets out a conceptual framework in which the system is seen from the perspectives of users, health professionals and policy‐makers. It sees the effective delivery of health care as dependent on appropriate investment in human, physical, intellectual and social resources. The study reveals important weaknesses in all of these areas, although it also notes that current policies, while constrained by the legacy of the past and by limited resources, are beginning to tackle them. This pilot study indicates that rapid appraisal, using a condition such as diabetes, where those affected can be easily identified, offers a means of gaining important insights into a health care system. Copyright © 2004 John Wiley & Sons, Ltd.
NHS Direct: managing demand for primary care?
Authors: Mark Annabelle L. , Shepherd Ifan D. H.
Published: March 2004

This paper considers how NHS Direct is affecting demand for primary care in particular out‐of‐hours services from GPs. This is reviewed through a 3‐year study of NHS Direct and HARMONI, the integrated telephone health helpline based in West London. It describes the policy background and development of the services on the site, and some of the outcomes of the HARMONI commissioned research to answer the question ‘Has NHS Direct increased the workload for HARMONI doctors?’.

The research adopted both a qualitative and quantitative approach using cross‐sectional and longitudinal analysis of the data collected. The analysis of the data reveals the issues as both complex and dynamic in nature. The research shows that while there has been no significant change to the total volume of activity, changes within patient groups notably the elderly and children, and in individual GP practices may be significant. In addition, the changes in organizational arrangements may influence significant changes in referral patterns such as GP out‐of‐hours visits. This was confirmed in the interview data indicating a link between the change in nurses' role from gatekeeper to patient advocate, which happened when they ceased to be employees of the part‐time co‐op and began to work instead for the 24 hours, 7 days a week NHS Direct service.

The conclusions drawn are that behavioural and organizational changes are at least as significant as the evidence‐based computerized decision support software in changing the demand for primary care. Further evidence cited is that a different demand pattern of calls was experienced by those local GPs not integrated into out‐of‐hours provision at NHS Direct West London at the time of the study. Copyright © 2004 John Wiley & Sons, Ltd.
Costing of services of Vietnamese hospitals: identifying costs in one central, two provincial and two district hospitals using a standard methodology
Authors: Flessa Steffen , Dung Nghiem Tran
Published: March 2004

Background

The People's Republic of Vietnam is currently in a period of transition from a purely socialistic country towards a so‐called socialist market economy. Since the introduction of the Doi Moi policy in 1987, health care services have been liberalized, medical practitioners have received the right to open private hospitals and private pharmacies are booming. However, the majority of inhabitants strongly depends on governmental hospital services. These services are currently going through a financial crisis. This demands the quest for efficiency and the wise allocation of public funds.

Research question

The efficient allocation of funds depends on the quotient between costs and health outcomes, but the costs of health services in Vietnamese hospitals are unknown. Therefore the study analysed five hospitals in Vietnam and determined the average costs as well as the main cost drivers.

Methodology

The full costs of five hospitals were analysed, including depreciation and the value of donations. The costs were allocated to cost centres and cost units by a stepping‐stone method.

Major findings

As expected, the average costs per inpatient day at a central hospital are about 300% of the costs of provincial hospitals and about 600% of the costs of district hospitals. However, the costs of some laboratory procedures and operations done at district hospitals are higher than those of provincial or even central hospitals. The main reason for the high costs of some procedures at district hospitals was the low quantity of these procedures at that level. This is a strong indicator that some procedures, in particular major operations, should not be performed in Vietnamese district hospitals. Copyright © 2004 John Wiley & Sons, Ltd.