bluuebunny/crossref_metadata_2025 huggingface dataset:
HEMT noise neural model based on bias conditions
Authors: Marković Vera , Marinković Zlatica
Published: March 2004

Knowledge of the microwave transistor parameters at various bias conditions is often required in computer‐aided design of complex microwave low‐noise circuit. Since the measurements of noise parameters are very complex and time‐consuming, microwave circuit designers usually use the catalogues' data or noise models. The noise data that can be found in the catalogues are often limited to a few frequencies and to one or few bias points. Further, most of the existing noise models require recalculation of elements/parameters of an equivalent circuit for every bias point. Microwave HEMT transistor noise prediction based on a multilayer perceptron neural network, proposed in this paper, enables noise prediction for all operating points over a wide frequency range. Neural networks are trained to learn noise parameters' dependence on bias conditions and frequency. After network training, noise prediction for a specified bias point requires only a network response calculation without changes in the network structure.
The Future Library Consortium in Ghana
Authors: Martey A.K.
Published: March 2004

This paper looks at the major goal and objectives set by Ghanaian academic libraries for the formation of a multipurpose consortium different from the Ghana Interlibrary Lending and Document Delivery Project (GILLDDNET). It also discusses the challenges that will be faced in achieving the stated goals and objectives and suggests what librarians can do to make a success out of the proposed consortium.
Information strategies: are we aligning the business case with enterprise planning?
Authors: Asprey Len
Published: March 2004

Focuses on the requirement for business and government enterprises to address the problems associated with managing the various types of information assets, such as electronic documents, e‐mails, sound files, digital drawings and Web content. Outlines the challenges facing executives in managing digital and physical information assets, in order to fulfil their responsibilities to customers, shareholders or the public. Suggests that information practitioners should develop a thorough understanding of the business imperatives within their organisations, and use applied methodologies to analyse critically business processes, methods and tools. This approach will mean that the various information disciplines within enterprises will have to communicate and share knowledge.
Creating a system for public information: the Swedish aid agency’s transformation to electronic administration
Authors: Granath Per , Alariksson Stefan , Axelsson Sverker
Published: March 2004

The Swedish International Development Cooperation Agency (Sida) is in the process of transition from paper‐based to electronic administration. This process includes the introduction of new methods that are based on routines and functions for electronic document management. The electronic administration is adapted to the legal requirements of the Swedish public sector and also includes the agency’s register of incoming and outgoing mail and archives. In the article the authors present the operational concept behind the major process of change being implemented by Sida and its anticipated effects together with the consequences of the change for archives work. Finally, an explanation of the Swedish principle of public access to official records and other legal aspects that affect Sida’s project for an electronic administration is provided.
Is the Freedom of Information Act driving records management in further education colleges?
Authors: Edward Sheila , McLeod Julie
Published: March 2004

This article presents key findings from a JISC‐funded research project “Developing records management in further education: responding to the requirements of the Freedom of Information Act 2000”, considering issues raised in a study of 15 colleges in northern England in 2003. It highlights difficulties of raising awareness of records management in this context; the value of the “Model action plan for achieving compliance with the Lord Chancellor’s Code of Practice on the management of records in higher and further education institutions”; and barriers to be overcome in institutions where the appointment of a professional records manager is not a possibility. It considers whether preparations for FoI have had an impact on records management in this sector, and whether this is likely to continue or increase in future, after the Act comes into force in England, Wales and Northern Ireland in January 2005.
E‐innovation: Internet impacts on small UK hospitality firms
Authors: Martin Lynn M.
Published: March 2004

Within the small firms sector, the Web is anticipated to bring unprecedented new opportunities for business development and competitive advantage. The reality in small firms, however, may be that lack of understanding of the value the Net may provide in the context of their own organisation, deters many owners from gaining such advantages. This paper looks at six cases of small hospitality firms. “E‐innovation” here represents innovative strategy enabling customers to do what best serves their purpose via information communications technology. These small hospitality firms have adopted the Web and used it; as a result they have changed business processes and personal expectations. Suggests that the current narrow focus on business growth or on technology alone seen in current initiatives may miss owners such as these who took up the Net for social and personal reasons but developed business uses alongside them. Recommends that an integrated hosting of such firms would provide better customer access, and therefore lead to benefits for such firms. Where targets are set for increases in tourism, it is also recommended that the Internet might play a part in developing such growth, if integrated and applied to the context of hospitality firms.
Selecting hotel staff: why best practice does not always work
Authors: Lockyer Cliff , Scholarios Dora
Published: March 2004

This paper considers the nature of “best practice” recruitment and selection in the hotel sector. Data from a sample of Scottish hotels indicate a reliance on informal methods, particularly in smaller hotels. In larger and chain hotels, structured procedures, including references, application forms and panel interviews, are evident, but, here too, these methods seem inadequate for dealing with recruitment and quality problems, especially in meeting temporary staffing needs. Case study evidence contrasts two alternative strategies: a successful holistic strategy based on management of social processes important for selection, and a more conventional bureaucratic strategy. Each strategy depends on a complex interrelationship between business and labour market considerations, the ownership and management structure of the hotel, and the tenure and experience of those responsible for selection. This evidence indicates that, for the hotel industry, the holistic strategy is an alternative to conventional notions
Effect of owners’ gender on venture quality evaluation
Authors: Knotts Tami L. , Jones Stephen C. , Waller LaPreze Melody
Published: March 2004

A study was undertaken to determine if there were quality differences between ventures that were forwarded on to a mass merchandiser for buyer review and those that were not. The sample ventures were manufacturers participating in an independent evaluation program for a major US midwest mass merchandiser. The quality issues were based on common management practices and on the marketability of the product being offered to the firm. Ventures that were forwarded for subsequent buyer review were found to be superior in both areas of concern. A separate analysis was run to determine if any gender‐based differences were notable in the evaluation process. With few exceptions, male‐ and female‐owned ventures were of comparable quality when forwarding status was controlled. However, using regression analysis, product quality was found to have the greatest impact on whether or not a female‐owned venture was forwarded, while the quality of the entire venture (product and management practices) was of greater significance for male‐owned ventures.
Making female first‐line nurse managers more effective: a Delphi study of occupational stress
Authors: Loo Robert , Thorpe Karran
Published: March 2004

A two‐round Delphi study was conducted with a panel of 41 Canadian female nurse managers selected from hospitals with at least 100 beds, in the province of Alberta, Canada. The Delphi study examined the changing roles of First‐line nurse managers (FLNMs) and major challenges they face with the aim of identifying major stressors and presenting recommendations for senior health care administrators to effectively support FLNMs in the future. Findings underscored the need to better prepare FLNMs for their changing and challenging roles. Organizations need to provide FLNMs with the resources to ensure quality patient care and enable them to spend more quality time executing their management responsibilities. Health care organizations should consider using a more participative management style, with mentoring, to empower and effectively use the extensive experience of their FLNMs to tackle the challenges of the future.
Are women “cooler” than men during crises? Exploring gender differences in perceiving organisational crisis preparedness proneness
Authors: Mano‐Negrin Rita , Sheaffer Zachary
Published: March 2004

The paper examines how male and female executives’ leadership orientations are reflected in crisis awareness. Drawing on management‐related gender and crisis theories, it is argued that women’s proclivity to employ participative decision making is mirrored advantageously in coping with crisis‐related scenarios. Predicated on a sample of 112 Israeli executives it is shown that perceptions of crisis preparedness/proneness are gender‐based and that women are more likely to employ a holistic approach that facilitates crisis preparedness.
GIS/RS for landslides zonation in Pos Slim‐Cameron Highlands district, Peninsula Malaysia
Authors: Syed Omar Sharifah N. , Jeber Faisal kh. M. , Mansor Shattri
Published: March 2004

Remote sensing data and GIS techniques have been used to create thematic maps for assessment and estimation of landslide hazards, in Pos Slim‐Cameron Highlands area, Peninsula Malaysia. The Landsat TM5 scene was used to extract land use parameter of the study area. The digital elevation model (DEM) was generated from digitised topographic maps to produce slope risk map, aspect risk map and height risk map. From these data, a simple algorithm is created to classify the area into different risk zones. By overlaying all hazard maps, a final hazard map is produced. The integration of GIS with remotely sensed data might greatly facilitate classifying landslide areas to three categories; low risk, medium risk and high risk.
Aviation accident aetiology: catastrophe theory perspective
Authors: Masys A.J.
Published: March 2004

Human error is often cited as a major contributing factor or cause of incidents and accidents. Incident surveys in aviation have attributed 70 per cent of incidents to crew error. Although a large proportion of the accidents can be attributed to human error, Reason proposes a view that many accidents are catalyzed by persons not present at the time of the event. In fact, it is this source of latent conditions that pose a most significant threat to the safety of complex systems. Another dimension to human error in aviation are the active errors that can precipitate the alignment or trigger the latent conditions. The risk associated with aviation is a dynamic element that is affected by both latent conditions and situational factors. This dynamic nature is presented here using the cusp model from catastrophe theory. Using Reason’s latent failure model, the descriptive and predictive nature of the cusp model works as a map to illustrate the nature of aviation accidents in terms of “instability” resulting from the alignment of latent conditions and influence of active errors. The SwissAir 111 tragedy of 2 September 1998 is used as a case study to illustrate this model.
The learning organization: towards an integrated model
Authors: Örtenblad Anders
Published: March 2004

This article presents an integrated model of the learning organization. It is based on empirical research of the learning organization literature, as well as on practitioners’ understandings of the concept where learning organizations were often described in terms of four distinct individual aspects – no more and no less. This article argues these aspects cannot be treated as separate, and that the four aspects have to be combined in order to create a true learning organization. The four aspects are: learning at work; organizational learning; developing a learning climate; and creating learning structures. The article suggests that only those organizations that have implemented all of the aspects should be called “learning organizations”, and those organizations that have implemented only one aspect should be called “partial learning organizations”.
Making brand equity a key factor in M&A decision‐making
Authors: Kumar Shailendra , Hansted Blomqvist Kristiane
Published: March 2004

Brand is a strategic asset that should be managed. This is an increasingly important issue for businesses that favor or have favored acquisition‐based growth strategies. To ensure optimal strategic value from the brands they are buying and selling, just calculating brand value does not suffice. They need a process for integrating brand and corporate finance M&A practices and for determining how to brand the acquired company and how to manage the migration of the brand to the new company. The imperative is to ensure that customers remain happy and loyal to the brand. This article offers a guide to equip acquiring companies with a framework for incorporating brand evaluation and brand strategy into the M&A transaction process. It helps non‐marketers and marketers alike better understand how to conduct marketing due diligence before the deal; think about brand strategy in the context of a portfolio; establish brand migration plans to help maximize the value of brand in the deal.
Manufacturable surface reconstruction from complex contours
Authors: Li Weishi , Xu Shuhong , Zhao Gang
Published: March 2004

To retrieve the geometric information contained in CT images, a surface reconstruction method, which is based on the similarity between the corresponding contours of adjacent sections, is presented in this paper. The correspondence of the contours of adjacent sections is determined by incorporating the topological rules and overlaps of the convex hulls of the contours. Then, the similar vertices of the corresponding contours are matched using a two‐phase strategy, consisting of overall matching followed by local matching. Dissimilar portions are extracted to construct the triangulable spatial dissimilar polygons. Finally, triangular meshes interpolating the contours are obtained by triangulating the dissimilar polygons and similar portions separately. The reconstructed surface models can be used in rapid prototyping as well as visualization. Experimental results demonstrate the validity of the method in reconstructing the surface from severe dissimilar contours.
Benchmarking for comparative evaluation of RP systems and processes
Authors: Mahesh M. , Wong Y.S. , Fuh J.Y.H. , Loh H.T.
Published: March 2004

A geometric benchmark part is proposed, designed and fabricated for the performance evaluation of rapid prototyping machines/processes. The benchmark part incorporates key shapes and features of better‐known benchmark parts. It also includes new geometric features, such as freeform surfaces, certain mechanical features and pass‐fail features that are increasingly required or expected of RP processes/systems. The part is suitable for fabrication on a typical RP machines. In this paper, the application of the benchmark part is demonstrated using relatively common RP processes. The ability of the benchmark part to determine achievable geometric features and accuracy by the aforementioned RP processes is presented and discussed.
Rapid prototyping fabricated by UV resin spray nozzles
Authors: Chang C.C.
Published: March 2004

Rapid prototyping (RP) processes produce parts layer by layer directly from 3D CAD models. Different kinds of rapid prototyping machine (RPM) have been developed with different mechanisms or materials. In this paper, a novel and economic way to build the RP by means of injection nozzles with ultra violet (UV) resins is proposed. The in‐house made RPM is constructed with two nozzles. The acrylic series is for body material and the PU series is for the supporting material. There are obvious boundaries since material properties are different. Therefore, supports can be easily removed from the main body after formation. The different diameter of nozzles can be chosen in the system, and the nozzles are also disposable. Besides, an interface system generating the direct slicing from 3D CAD models and nozzle paths for all layers is developed through PowerSOLUTION (Delcam International, Birmingham, UK) macro commands.
Performance management in the public sector: fact or fiction?
Authors: Radnor Zoe , McGuire Mary
Published: March 2004

Since New Labour came to power in the UK in 1997, there has been a drive to improve the effectiveness of public services through the use of private sector principles. From, the Modernising Government White Paper to the development of the Public Services Productivity Panel who, produced a raft of White Papers tackling health, social services, welfare and criminal justice. This paper, through the analysis of two studies, will reflect on some of the general literature on public sector performance management and the findings and recommendations of the Public Services Productivity Panel in order to attempt to answer whether performance management in the public sector is currently fact or fiction? In other words the paper will aim to develop and answer, to a certain extent, if it really possible to raise productivity and performance within public sector organisations through developing performance management systems based on private sector experience.
Molecular dynamics and free energy analysis of neuraminidase–ligand interactions
Authors: Bonnet Pascal , Bryce Richard A.
Published: March 2004

We report molecular dynamics calculations of neuraminidase in complex with an inhibitor, 4‐amino‐2‐deoxy‐2,3‐didehydro‐N‐acetylneuraminic acid (N‐DANA), with subsequent free energy analysis of binding by using a combined molecular mechanics/continuum solvent model approach. A dynamical model of the complex containing an ionized Glu119 amino acid residue is found to be consistent with experimental data. Computational analysis indicates a major van der Waals component to the inhibitor‐neuraminidase binding free energy. Based on the N‐DANA/neuraminidase molecular dynamics trajectory, a perturbation methodology was used to predict the binding affinity of related neuraminidase inhibitors by using a force field/Poisson‐Boltzmann potential. This approach, incorporating conformational search/local minimization schemes with distance‐dependent dielectric or generalized Born solvent models, correctly identifies the most potent neuraminidase inhibitor. Mutation of the key ligand four‐substituent to a hydrogen atom indicates no favorable binding free energy contribution of a hydroxyl group; conversely, cationic substituents form favorable electrostatic interactions with neuraminidase. Prospects for further development of the method as an analysis and rational design tool are discussed.
HIV‐1 protease molecular dynamics of a wild‐type and of the V82F/I84V mutant: Possible contributions to drug resistance and a potential new target site for drugs
Authors: Perryman Alexander L. , Lin Jung‐Hsin , McCammon J. Andrew
Published: March 2004

The protease from type 1 human immunodeficiency virus (HIV‐1) is a critical drug target against which many therapeutically useful inhibitors have been developed; however, the set of viral strains in the population has been shifting to become more drug‐resistant. Because indirect effects are contributing to drug resistance, an examination of the dynamic structures of a wild‐type and a mutant could be insightful. Consequently, this study examined structural properties sampled during 22 nsec, all atom molecular dynamics (MD) simulations (in explicit water) of both a wild‐type and the drug‐resistant V82F/I84V mutant of HIV‐1 protease. The V82F/I84V mutation significantly decreases the binding affinity of all HIV‐1 protease inhibitors currently used clinically. Simulations have shown that the curling of the tips of the active site flaps immediately results in flap opening. In the 22‐nsec MD simulations presented here, more frequent and more rapid curling of the mutant's active site flap tips was observed. The mutant protease's flaps also opened farther than the wild‐type's flaps did and displayed more flexibility. This suggests that the effect of the mutations on the equilibrium between the semiopen and closed conformations could be one aspect of the mechanism of drug resistance for this mutant. In addition, correlated fluctuations in the active site and periphery were noted that point to a possible binding site for allosteric inhibitors.
Substrate binding mode and reaction mechanism of undecaprenyl pyrophosphate synthase deduced from crystallographic studies
Authors: Chang Sing‐Yang , Ko Tzu‐Ping , Chen Annie P.‐C. , Wang Andrew H.‐J. , Liang Po‐Huang
Published: March 2004

Undecaprenyl pyrophosphate synthase (UPPs) catalyzes eight consecutive condensation reactions of farnesyl pyrophosphate (FPP) with isopentenyl pyrophosphate (IPP) to form a 55‐carbon long‐chain product. We previously reported the crystal structure of the apo‐enzyme from Escherichia coli and the structure of UPPs in complex with sulfate ions (resembling pyrophosphate of substrate), Mg2+, and two Triton molecules (product‐like). In the present study, FPP substrate was soaked into the UPPs crystals, and the complex structure was solved. Based on the crystal structure, the pyrophosphate head group of FPP is bound to the backbone NHs of Gly29 and Arg30 as well as the side chains of Asn28, Arg30, and Arg39 through hydrogen bonds. His43 is close to the C2 carbon of FPP and may stabilize the farnesyl cation intermediate during catalysis. The hydrocarbon moiety of FPP is bound with hydrophobic amino acids including Leu85, Leu88, and Phe89, located on the α3 helix. The binding mode of FPP in cis‐type UPPs is apparently different from that of trans‐type and many other prenyltransferases which utilize Asprich motifs for substrate binding via Mg2+. The new structure provides a plausible mechanism for the catalysis of UPPs.
Factors involved in the stability of isolated β‐sheets: Turn sequence, β‐sheet twisting, and hydrophobic surface burial
Authors: Santiveri Clara M. , Santoro Jorge , Rico Manuel , Jiménez M. Angeles
Published: March 2004

We have recently reported on the design of a 20‐residue peptide able to form a significant population of a three‐stranded up‐and‐down antiparallel β‐sheet in aqueous solution. To improve our β‐sheet model in terms of the folded population, we have modified the sequences of the two 2‐residue turns by introducing the segment DPro‐Gly, a sequence shown to lead to more rigid type II′ β‐turns. The analysis of several NMR parameters, NOE data, as well as ΔδCαH, ΔδCβ, and ΔδCβ values, demonstrates that the new peptide forms a β‐sheet structure in aqueous solution more stable than the original one, whereas the substitution of the DPro residues by LPro leads to a random coil peptide. This agrees with previous results on β‐hairpin‐forming peptides showing the essential role of the turn sequence for β‐hairpin folding. The well‐defined β‐sheet motif calculated for the new designed peptide (pair‐wise RMSD for backbone atoms is 0.5 ± 0.1 Å) displays a high degree of twist. This twist likely contributes to stability, as a more hydrophobic surface is buried in the twisted β‐sheet than in a flatter one. The twist observed in the up‐and‐down antiparallel β‐sheet motifs of most proteins is less pronounced than in our designed peptide, except for the WW domains. The additional hydrophobic surface burial provided by β‐sheet twisting relative to a “flat” β‐sheet is probably more important for structure stability in peptides and small proteins like the WW domains than in larger proteins for which there exists a significant contribution to stability arising from their extensive hydrophobic cores.
Experimentally based topology models for E. coli inner membrane proteins
Authors: Rapp Mikaela , Drew David , Daley Daniel O. , Nilsson Johan , Carvalho Tiago , Melén Karin , De Gier Jan‐Willem , Von Heijne Gunnar
Published: March 2004

Membrane protein topology predictions can be markedly improved by the inclusion of even very limited experimental information. We have recently introduced an approach for the production of reliable topology models based on a combination of experimental determination of the location (cytoplasmic or periplasmic) of a protein's C terminus and topology prediction. Here, we show that determination of the location of a protein's C terminus, rather than some internal loop, is the best strategy for large‐scale topology mapping studies. We further report experimentally based topology models for 31 Escherichia coli inner membrane proteins, using methodology suitable for genome‐scale studies.
Labor Council Outreach and Union Member Voter Turnout: A Microanalysis from the 2000 Election
Authors: Zullo Roland
Published: March 2004

A resource‐mobilization theoretical framework is used to model voter turnout as a function of contacts performed by a politically active labor council. Results indicate that the probability of voting in the 2000 national election was 27 to 17 percentage points higher for grocery workers that received a get‐out‐the‐vote telephone contact just before the election or on Election Day. Workers contacted 2 months prior to the election were associated with an 8 to 11 percentage point gain in voter turnout. The results imply that by pooling resources organized labor can serve as a positive social institution for increasing the political participation of working‐class citizens.
The Impact of Mandatory Votes on the Canada‐U.S. Union Density Gap: A Note
Authors: Johnson Susan
Published: March 2004

This article provides empirical evidence concerning the impact of mandatory votes on the Canada‐U.S. density gap. Simulation analysis reveals (1) that the increasing use of mandatory votes in Canada has narrowed the gap by about 1 percentage point and (2) that differences in recognition procedures between Canada and the United States accounted for at least 3 to 5 percentage points of the gap in 1998.
Unions and Employment Growth: The One Constant?
Authors: Addison John T. , Belfield Clive R.
Published: March 2004

Sequential analyses of the major workplace data sets available to British researchers—the cross‐sectional Workplace Industrial/Employee Relations Surveys (WIRS/WERS)—have revealed shifts in some previously well‐established associations between union presence and firm performance, so much so in fact that it has become conventional to speak of a pronounced reduction in the “disadvantages of British unionism.” One finding that seems to have persisted in cross section, however, is the negative effect of unions on employment growth. Following on a recent study in this Journal, we reexamine the issue using employment data from a panel of firms surveyed at two points in time rather than a single cross section. We report similar evidence of employment retardation in union regimes. On the other hand, the new data also suggest that some other unfavorable union effects may be longer‐standing than previously reported.
Diversity and community composition of butterflies and odonates in an ENSO‐induced fire affected habitat mosaic: a case study from East Kalimantan, Indonesia
Authors: Cleary Daniel F. R. , Mooers Arne Ø. , Eichhorn Karl A. O. , Van Tol Jan , De Jong Rienk , Menken Steph B. J.
Published: March 2004

Little is known about the diversity of tropical animal communities in recently fire‐affected environments. Here we assessed species richness, evenness, and community similarity of butterflies and odonates in landscapes located in unburned isolates and burned areas in a habitat mosaic that was severely affected by the 1997/98 ENSO (El Niño Southern Oscillation) event in east Kalimantan, Indonesian Borneo. In addition related community similarity to variation in geographic distance between sampling sites and the habitat/vegetation structure Species richness and evenness differed significantly among landscapes but there was no congruence between both taxa. The species richness of butterflies was, for example, highest in sites located in a very large unburned isolate whereas odonate species richness was highest in sites located in a small unburned isolate and once‐burned forest. We also found substantial variation in the habitat/vegetation structure among landscapes but this was mainly due to variation between unburned and burned landscapes and variation among burned landscapes.

Both distance and environment (habitat/vegetation) contributed substantially to explaining variation in the community similarity (beta diversity) of both taxa. The contribution of the environment was, however, mainly due to variation between unburned and burned landscapes, which contained very different assemblages of both taxa. Sites located in the burned forest contained assemblages that were intermediate between assemblages from sites in unburned forest and sites from a highly degraded slash‐and‐burn area indicating that the burned forest was probably recolonised by species from these disparate environments. We, furthermore, note that in contrast to species richness (alpha diversity) the patterns of community similarity (beta diversity) were highly congruent between both taxa. These results indicate that community‐wide multivariate measures of beta diversity are more consistent among taxa and more reliable indicators of disturbance, such as ENSO‐induced burning, than univariate measures.
Predator‐induced changes in population structure and individual quality of Microtus voles: a large‐scale field experiment
Authors: Norrdahl Kai , Heinilä Henrik , Klemola Tero , Korpimäki Erkki
Published: March 2004

In small mammal populations with multiannual oscillations in density, observational data have revealed cyclic changes in population structure, reproduction, and individual quality, but mechanisms inducing these changes have remained an open question. We analysed data collected during a 3‐year predator reduction experiment to find out the effects of predators on population structure, reproductive parameters, and individual quality of Microtus voles (the field vole M. agrestis and the sibling vole M. rossiaemeridionalis) in western Finland. Voles were collected by snap trapping in April, June, August, and October during 1997–1999. The yearly reduction of predators from April to October had a clear positive effect on the abundance of sibling voles but did not significantly affect the densities of field voles. Predator reduction apparently also affected the age ratio and mean body size in late summer, as well as pancreatic weights of voles. However, all observed differences between predator reduction and control areas, except those in abundance, were small and may mainly reflect a generally higher survival leading to higher densities of voles in predator reduction areas. Our results also indicated a relative lack of high quality food at population peaks but not because of reduced foraging activity in the presence of predators. We conclude that the indirect effects of vole‐eating predators on the population growth of main prey are small compared to the detrimental direct effects on prey survival. In the case of less preferred prey, indirect effects of predation through reduced interspecific competition may play a role at high densities.
Modeling the distribution and abundance of the non‐native parasite, canine heartworm, in California coyotes
Authors: N. Sacks Benjamin , B. Chomel Bruno , W. Kasten Rick
Published: March 2004

We applied a habitat‐modeling approach using logistic regression to predict the distribution and abundance of canine heartworm (Dirofilaria immitis) in coyotes (Canis latrans) throughout California. Heartworm is an arthropod‐borne parasite of considerable economic and ecological importance. In California, coyotes serve as the primary sylvatic maintenance host and represent a useful sentinel for this parasite. To develop the model, we used a large collection of coyote blood specimens and carcasses collected from spatially broad, yet nonrandom, locations in California. Survey data were useful in refining previous coarser models that predicted uniformly high prevalence of heartworm throughout the coastal and Sierra‐Nevada foothills, by indicating variability within this broadly defined plant‐climate zone. Due to the non‐random nature and large spatial scale of our data‐set, we restricted variables to those thought to be most generally important. Modeling indicated that woodlands with a relatively dense canopy, suitable breeding and host‐seeking habitat of the western treehole mosquito (Ochlerotatus sierrensis), were a good predictor of heartworm prevalence. Within this habitat, prevalence increased with precipitation, which likely affected mosquito abundance. The distribution of heartworm was limited to areas with average cumulative temperatures high enough to enable larval development of heartworms within their mosquito vectors. The prediction accuracy of our model was supported by goodness‐of‐fit tests, cross‐validation tests and external validation tests. The model provided a useful guide to the relative risk of heartworm exposure in California, although the resolution was necessarily coarse and prevalence estimates related to risk in an ordinal manner only.
What population factors influence the decision to donate blood?
Authors: Hollingsworth Bruce , Wildman John
Published: March 2004

Summary. Donations of blood in most of the developed world are by nonremunerated volunteers. As such factors, which impact upon the motivation of individuals to donate, are critical to achieving a stable supply, we analyze the factors, which influence the decision to donate. Using data on 29 762 individuals from 1999 and 2000, we investigate which factors determine the proportion of blood donors in postcode areas. Variables analyzed include blood donation status and sociodemographic characteristics in order to provide information on donation decisions. We find the proportion of donors in an area is significantly increased by higher proportions of women aged 20–29 and 40–49, and of men aged 60–69. Conversely, a higher proportion of males aged 20–29 significantly reduces proportion of donors. Also, a higher proportion of individuals born overseas significantly reduces the proportion of blood donors in an area. To increase supplies, blood collection agencies should target specific groups. Young men and men and women aged 30–49 need to be encouraged to donate. Collection agencies also need to target individuals who are born overseas to participate in the process. Using these results to aid targeting should help to maintain the blood supply.
Reducing red cell transfusion by audit, education and a new guideline in a large teaching hospital
Authors: Garrioch M. , Sandbach J. , Pirie E. , Morrison A. , Todd A. , Green R.
Published: March 2004

Summary.  Safety concerns combined with the greatly increased costs and difficulties of maintaining the blood supply are major considerations for transfusion services. Previous local surveys demonstrated that hospital blood use at our hospital could be improved. Excessive cross‐matching, unnecessary transfusion and high return rates of unused blood were commonplace.

Transfusion practice was audited over a 3‐month period. An education package with guidelines for transfusion was delivered to all clinician groups within the hospital, over the following 9 months. The audit was repeated exactly 1 year later at the same time period.

During the second audit, inpatient hospital numbers increased by 1·02% (from n = 7262 to n = 7336) but no differences in length of stay, cardiovascular morbidity or mortality were demonstrated. Twenty percent (n = 254, 2002; n = 316, 2001) fewer patients received blood, and the number of red cell packs used reduced by 19% (from n = 1093 to n = 880). Total number of patients transfused reduced from 4·4% to 3·5% which, as an absolute difference, is a reduction of 0·9% (CI 0·3–1·5, P = 0·006). The audit, guideline and education package had a major impact on red cell use within the hospital with no adverse effects.

Blood use can be improved by the implementation of a suitable education package and guideline. If it is possible to replicate the results of this education programme nationwide, the effect on blood use, with subsequent savings and enhanced patient safety could be significant.
Complement activation in prestorage leucocyte‐filtered plasma
Authors: Hyllner M. , Tylman M. , Bengtson J. P. , Rydberg L. , Bengtsson A.
Published: March 2004

Summary.  Complement activation and generation of pro‐inflammatory cytokines occur during storage of blood components. Prestorage leucocyte filtration of platelet concentrates and red cells diminishes the accumulation of leucocyte‐derived cytokines during storage, however, transfusion reactions are not eliminated. We investigated inflammatory mediator release during storage of plasma and whole blood and the effect of prestorage leucocyte filtration of plasma. Twenty‐four blood units were collected from healthy blood donors and stored for 35 days. Eight units were stored as whole blood, eight units as plasma and eight units as prestorage filtered plasma. Samples were collected weekly for analyses of potassium, leucocytes, free plasma haemoglobin, complement activation (C3a and SC5b‐9) and pro‐inflammatory cytokines [interleukin (IL)‐6, IL‐8 and tumor necrosis factor (TNF)‐α]. Elevated levels of C3a and SC5b‐9 were registered in filtered plasma, from the beginning of storage. C3a levels increased during storage. There was a higher rate of change during storage in C3a (P < 0·01) and SC5b‐9 (P < 0·05) in plasma compared with filtered plasma. Interleukin (IL)‐8 is released in whole blood. The cytokine levels generated in plasma and filtered plasma were low. Complement activation is present in whole blood, plasma and filtered plasma during storage. Prestorage filtration of plasma activates the complement cascade but does not influence cytokine generation.
On The Fundamental Theorem Of Asset Pricing: Random Constraints And Bang‐Bang No‐Arbitrage Criteria
Authors: Evstigneev Igor V. , Schürger Klaus , Taksar Michael I.
Published: March 2004

The paper generalizes and refines the Fundamental Theorem of Asset Pricing of Dalang, Morton, and Willinger (1990) in the following two respects: (a) the result is extended to a model with general portfolio constraints, and (b) versions of the no‐arbitrage criterion based on the bang‐bang principle in control theory are developed.
Patients prescribed injectable heroin or methadone —their opinions and experiences of treatment
Authors: Sell Louise , Zador Deborah
Published: March 2004

Aims  To describe the opinions and experiences of treatment of a cohort of patients prescribed injectable opiate treatment (IOT).

Design, setting, participants  Cross‐sectional survey of all patients on injectable diamorphine or methadone at a tertiary referral clinic in the northwest of England in June 2000.

Findings  A total of 104 subjects were prescribed IOT, mostly male (87.5%) and with a mean age of 36.3 years (SEM 0.66, range 20–53). The majority (75.0%) were prescribed injectable methadone with the remainder (25.0%) on injectable diamorphine. Most subjects (93.3%) used intravenously, many (58.7%) into the femoral vein. Treatment was sought most frequently in order to procure a drug supply of known dose and purity, to improve family relationships and to avoid trouble with the police. Half were satisfied with their treatment but many wanted to change to injectable diamorphine or to increase their doses. Subjects cited many advantages of injectable diamorphine over injectable methadone, although benefits of injectable methadone were acknowledged.

Conclusions  Subjects articulated a consistent desire for IOT in order to ‘stabilize’ their lives in a number of ways. This sample was recruited from one of the country's largest specialist IOT clinics. The generalizability of this study's findings to all patients in the United Kingdom currently prescribed IOT, however, was not examined. Nevertheless, these findings suggest that clinicians and policy makers should be aware of many heroin users’ perception of IOT as long‐term treatment and their clear preference for injectable diamorphine. Further investigation of differential outcomes between oral and injectable OT and between different injectable opiates is warranted.
Heroin and cocaine abusers have higher discount rates for delayed rewards than alcoholics or non‐drug‐using controls
Authors: Kirby Kris N. , Petry Nancy M.
Published: March 2004

Aims  To test a prediction of the discounting model of impulsiveness that discount rates would be positively associated with addiction. The delay‐discount rate refers to the rate of reduction in the present value of a future reward as the delay to that reward increases.

Design and measurements  We estimated participants’ discount rates on the basis of their pattern of choices between smaller immediate rewards ($11–80) and larger, delayed rewards ($25–85; at delays from 1 week to 6 months) in a questionnaire format. Participants had a one‐in‐six chance of winning a reward that they chose on one randomly selected trial.

Participants and setting  Heroin (n = 27), cocaine (n = 41) and alcohol (n = 33) abusers and non‐drug‐using controls (n = 44) were recruited from advertisements. They were tested in a drug abuse research clinic at a medical school.

Findings  On average, the cocaine and heroin groups had higher rates than controls (both P < 0.001), but alcoholics did not (P = 0.44). Abstinence was associated with lower rates for heroin abusers (P = 0.03), but not for cocaine or alcohol abusers (both P > 0.50).

Conclusions  These data suggest that discount rates vary with the preferred drug of abuse, and that high discount rates should be considered in the development of substance abuse prevention and treatment efforts.
Heroin diffusion in the mid‐Hudson region of New York State
Authors: Furst R. Terry , Herrmann Christopher , Ray Leung  , Galea John , Hunt Kirsten
Published: March 2004

Aims  Prompted by the history of heroin diffusion in the United States, press reports and building on previous research into retail heroin distribution, ethnographic research was undertaken identifying and describing retail distribution and diffusion of heroin in and into medium‐ and small‐sized towns in the mid‐Hudson region of New York State.

Methods  In conjunction with fieldwork, in‐depth tape‐recorded interviews were conducted with recent admissions (30 days) at 28 different drug treatment facilities located in the region. Interviews were also conducted with drug counselors, narcotic officers, drug treatment administrators and the county commissioners of mental hygiene.

Findings  Heroin‐dependent individuals who have access to cheaper heroin in urban areas, such as New York City, Newark, and Patterson, New Jersey, drive retail heroin distribution in the mid‐Hudson region. They travel to these cities, purchase heroin in quantity (costing $8–10 per bag), return to the region and sell premium‐priced heroin ($20‐$25 per bag) mostly to irregular users who do not have access to retail drug sellers in urban areas.

Conclusion  Price disparity contributes to a recurrent process whereby irregular users who are able to gain access to cheaper heroin in urban areas, return to the mid‐Hudson and sell premium‐priced heroin to other users who do not have access to cheaper heroin. This process contributes to the diffusion of heroin abuse.
Cannabis use and the risk of later schizophrenia: a review
Authors: Smit Filip , Bolier Linda , Cuijpers Pim
Published: March 2004

Aim  To study the role of cannabis use in the onset of symptoms and disorders in the schizophrenia spectrum.

Design  Review of five population‐based, longitudinal studies on the relationship between cannabis use and problems ranging from the experience of psychotic symptoms to hospitalization with a confirmed diagnosis of schizophrenia. Several hypotheses are examined that may explain this relationship: (1) self‐medication; (2) effects of other drugs; (3) confounding; (4) stronger effect in predisposed people, and (5) etiological hypothesis.

Findings  Hypotheses 1 and 2 can be dismissed; hypothesis 3 is still open to debate, and converging evidence is found for hypotheses 4 and 5—antecedent cannabis use appears to act as a risk factor in the onset of schizophrenia, especially in vulnerable people, but also in people without prior history.

Conclusion  There is an intrinsic message here for public health, but how that message is to be translated into action is not immediately clear.
Comparison of three models of alcohol craving in young adults: a cross‐validation
Authors: McEvoy Peter M. , Stritzke Werner G. K. , French Davina J. , Lang Alan R. , Ketterman Rita
Published: March 2004

Aims The aim of study 1 was to develop a three‐factor Approach and Avoidance of Alcohol Questionnaire (AAAQ), designed to assess mild and intense inclinations to drink, as well as inclinations to avoid drinking. The aims of study 2 were to cross‐validate the AAAQ with an independent sample and to test the goodness‐of‐fit of three models of craving for alcohol: (a) the traditional unidimensional model; (b) a two‐dimensional, approach–avoidance ambivalence model; and (c) an expanded two‐dimensional neuroanatomical model that retains avoidance, while positing a threshold that partitions approach into two distinct levels and relates all three factors involved in craving to brain pathways associated with inhibitory processes, reward and obsessive–compulsive behaviour, respectively.

Design, setting and participants The survey was administered to 589 Australian university students (69% women) in study 1 and to 523 American university students (64% women) in study 2.

Measurements Inclinations to drink and to not drink (AAAQ), drinking behaviour (quantity and frequency), drinking problems (Young Adult Alcohol Problems Screening Test; YAAPST) and readiness for change (Stages of Change Readiness and Treatment Eagerness Scale; SOCRATES).

Findings The expanded two‐dimensional neuroanatomical model provided the best fit to the data. The AAAQ explained a substantial proportion of the variance in drinking frequency (41–53%), drinking quantity (49–60%) and drinking problems (43%). AAAQ profiles differed as a function of drinking‐related risk, and the three AAAQ scales differentially predicted readiness for change.

Conclusions Approach and avoidance inclinations toward alcohol are separable constructs, and their activation may not be invariably reciprocal. Craving can be defined as the relative activation of substance‐related response inclinations along these two primary dimensions. There may be a threshold of intensity that separates mild from intense approach inclinations.