bluuebunny/crossref_metadata_2025 huggingface dataset:
The occurrence of species flocks in the nematode genus Cloacina (Strongyloidea : Cloacininae), parasitic in the stomachs of kangaroos and wallabies
Authors: Beveridge I. , Chilton N. B. , Spratt D. M.
Published: March 2003

The occurrence of species flocks within the nematode genus Cloacina was examined using the criteria of host specificity, co-occurrence and monophyly. Species of Cloacina generally exhibited a high degree of host specificity, with most species occurring either in a single host species or in two closely related host species. The frequency distribution of numbers of component species of Cloacina per host species indicated that most host species harboured 2–4 species of nematodes, with an approximately exponential decline in the number of species of parasites to a maximum of 20 species of nematode per host species. Host species harbouring eight or more species of Cloacina were found within a single recent macropodid clade, but there was no correlation between evolutionary age of the host and the number of parasite species harboured. Sampling effort was significantly correlated with the number of nematode species found and, in partial regression analysis, subsumed the effects of host body size and geographic range, which were found to be significant correlates with the number of nematode species present in preliminary analyses. Analysis of co-occurrences of nematode species indicated significant variation between host species, with some hosts (e.g. Macropus agilis) most commonly harbouring a single species of Cloacina, while closely related host species (e.g. M. dorsalis) most commonly harboured numerous species. Parsimony analysis of species of Cloacina based on morphological data suggested that while small series of related nematode species could be identified within a single host species, the species flock in each host species is polyphyletic in origin. Species flocks contributed significantly to community richness in some host species.
Chlamydia trachomatis-induced death of human spermatozoa is caused primarily by lipopolysaccharide
Authors: Hosseinzadeh S. , Pacey A.A. , Eley A.
Published: March 2003

Elementary bodies (EBs) of Chlamydia trachomatis serovar E are more toxic to sperm than those from serovar LGV. In this study, lipopolysaccharide (LPS) was prepared from the EBs of both serovars and incubated with human spermatozoa at concentrations that matched the LPS concentration of EBs. The effects of EBs and LPS on sperm motility, viability and acrosomal status were then determined. Sperm motility was measured by computer-assisted sperm analysis and the hypo-osmotic swelling test was used to determine the proportion of dead cells. Acrosomal status was examined using a standard mAb assay. Over a 6 h incubation, LPS from both serovars resulted in a marked reduction in sperm motility (and a concomitant increase in the proportion of dead spermatozoa) in a manner similar to that seen in response to EBs of serovar E. In addition, when sperm were incubated with a range of doses of EBs and LPS, probit analysis revealed that the greater spermicidal effects of EBs from serovar E (when compared with serovar LGV) were not observed when sperm were incubated with LPS from the two serovars. This suggests that the more potent effect of EBs of serovar E cannot be explained entirely by differences in the composition of LPS. Interestingly, Escherichia coli LPS was required in doses 500 times more concentrated than chlamydial LPS in order to kill a similar proportion of sperm, suggesting that bacterial LPSs may differ in their spermicidal properties. However, that chlamydial LPS was spermicidal was demonstrated by the use of polymyxin B (a polycationic antibiotic known to neutralize LPS effects), confirming that the effects observed were primarily a result of LPS activity.
Antimicrobial susceptibility patterns and genomic diversity in strains of Streptococcus pyogenes isolated in 1978–1997 in different Brazilian cities
Authors: Nunes De Melo Maria Celeste , Figueiredo Agnes Marie Sá , Ferreira-Carvalho Bernadete Teixeira
Published: March 2003

Penicillin has been the antimicrobial of choice for the treatment ofStreptococcus pyogenesinfections for almost six decades. Although penicillin-resistant isolates have not been described to date, clinical failures have been reported after treatment with β-lactams. In this study, we analysed the antimicrobial susceptibility and genetic diversity ofS. pyogenesisolates obtained from healthy carriers or patients in different cities in the south and south east of Brazil. The MICs were determined for penicillin and seven other antimicrobials. Penicillin tolerance was also investigated. Genetic diversity was analysed by PFGE afterSmaI fragmentation of the genomic DNA. All 211 isolates tested were susceptible to penicillin (MIC 0.0025–0.02 mg l−1). Four isolates were moderately penicillin-tolerant (MBC/MIC = 16 mg l−1). Most of the other drugs tested were very active against the strains examined, except for tetracycline, to which 50 % of strains were resistant. We also found extensive genetic diversity, in that 60 different patterns were recognized in the 96 strains studied. Indeed, we found no correlation between tetracycline resistance and clonality. Despite this diversity, some PFGE patterns persisted for up to 18 years and specific clone types were spread over different geographical locations
Protein kinase antagonists inhibit invasion of mammalian cells by Fonsecaea pedrosoi
Authors: Limongi Cristiana L. , De Souza Wanderley , Rozental Sonia
Published: March 2003

The phosphorylation process is an important mechanism of cell signalling and regulation. It has been implicated recently in defence strategies against a variety of pathogens that alter host signalling pathways in order to facilitate their invasion and survival within host cells. In this study, the involvement of protein kinases (PKs) has been investigated in attachment and invasion by the pathogenic fungusFonsecaea pedrosoiwithin epithelial cells and macrophages. The use of the PK inhibitors staurosporine, genistein and calphostin C prior to infection provided significant information about the role played by PKs in theF. pedrosoi–host cell interaction. All three PK inhibitors could reduce cell invasion byF. pedrosoisignificantly. Pre-treatment of macrophages, epithelial cells or conidia with PK inhibitors decreased fungus invasion, and this effect could be overcome by okadaic acid, a phosphatase inhibitor. Immunofluorescence assays showed that tyrosine residues were phosphorylated in the first step of the interaction, while serine residues were phosphorylated in the subsequent step of entry of the parasite into the host cell. These results suggest that both host-cell and conidium PK activities are important in the interaction process, playing a significant role in cell invasion.
Identification of immunodominant Helicobacter pylori proteins with reactivity to H. pylori-specific egg-yolk immunoglobulin
Authors: Shin Ji-Hyun , Nam Seung-Woo , Kim Jung-Taik , Yoon Jong-Bok , Bang Won-Gi , Roe Im-Hwan
Published: March 2003

The importance of hens eggs as a source of specific antibodies (IgY) is well recognized. The protective effect of IgY obtained from hens immunized withHelicobacter pyloriwhole-cell lysate has been reported for the control ofH. pyloriinfection. However, IgY produced by whole-cell lysates presents the possibility of cross-reactivity with other bacteria, including the normal human flora, and this could decrease the efficiency of IgY. In the present study, the immunodominant proteins ofH. pyloriwith reactivity toH. pylori-specific IgY (IgY-Hp) were identified. IgY obtained from hens immunized with various fractions ofH. pyloriproteins was isolated and purified, titres of IgY-HpagainstH. pyloriwere determined and cross-reactivity between IgY-Hpand normal human bacteria was examined by Western blot analysis. Finally, immunodominantH. pyloriproteins were identified by LC/MS analysis. IgY obtained 2 months after immunization withH. pyloriwhole-cell lysate showed the highest antibody titre. Five immunodominant proteins were identified that were strongly reactive to IgY-Hp: urease β-subunit (62 kDa), heat-shock protein 60 (60 kDa), urease α-subunit (26 kDa), probable peroxiredoxin (22 kDa) and probable thiol peroxidase (18 kDa). Immunization of hens with the immunodominant proteins identified would produce a more specific IgY againstH. pylori.
Chlamydia pneumoniae infection in adult patients with persistent cough
Authors: Miyashita Naoyuki , Fukano Hiroshi , Yoshida Koichiro , Niki Yoshihito , Matsushima Toshiharu
Published: March 2003

Chlamydia pneumoniae is a frequent causative agent of acute respiratory disease. To assess whether C. pneumoniae plays a role in persistent cough, the prevalence of C. pneumoniae infection in adult patients with persistent cough was investigated. Nasopharyngeal swabs and serology samples from 366 adult patients with a persistent cough lasting in excess of 2 weeks and 106 control subjects were analysed for bacterial isolation and by PCR. C. pneumoniae was isolated from two patients and from none of the controls and was detected by PCR in 20 patients and one control. Serological evidence of acute C. pneumoniae infection was present in 24 patients but in none of the controls. Of these 20 patients who were positive by culture and/or PCR, three were still positive by PCR after 2 weeks of treatment with clarithromycin and symptoms either continued or relapsed. However, when patients were treated with clarithromycin for 5–6 weeks, their symptoms disappeared completely and the results of their cultures and/or PCR for C. pneumoniae became negative. These data suggest that C. pneumoniae infection may cause persistent cough in adults. Furthermore, these data also indicate that it may be necessary to eradicate the organism when C. pneumoniae is detected by culture and/or PCR in patients with persistent cough.
Enhancement of DNA vaccine potency against herpes simplex virus 1 by co-administration of an interleukin-18 expression plasmid as a genetic adjuvant
Authors: Zhu Mingzhao , Xu Xuemei , Liu Hongwei , Liu Xiaojuan , Wang Sheng , Dong Fangtian , Yang Baoling , Song Guoxing
Published: March 2003

In this study, the immune-modulatory and vaccine effects of using an interleukin (IL)-18 expression plasmid as a genetic adjuvant to enhance DNA vaccine-induced immune responses were investigated in a mouse herpes simplex virus 1 (HSV-1) challenge model. BALB/c mice were immunized by three intramuscular inoculations of HSV-1 glycoprotein D (gD) DNA vaccine alone or in combination with a plasmid expressing mature IL-18 peptide. Both the serum IgG2a/IgG1 ratio and T helper 1-type (Th1) cytokines [IL-2 and interferon (IFN)-γ] were increased significantly by the co-injection of the IL-18 plasmid compared with the injection of gD DNA alone. However, the production of IL-10 was inhibited by IL-18 plasmid co-injection. Furthermore, IL-18 plasmid co-injection efficiently enhanced antigen-specific lymphocyte proliferation and the delayed-type hypersensitivity response. When mice were challenged with HSV-1 at the cornea, co-injection of IL-18 plasmid with gD DNA vaccine showed significantly better protection, manifested as lower corneal lesion scores and faster recovery. These experiments indicate that co-injection of an IL-18 plasmid with gD DNA vaccine efficiently induces Th1-dominant immune responses and improves the protective effect against HSV-1 infection.
Changes in sensitivity patterns to selected antibiotics in Clostridium difficile in geriatric in-patients over an 18-month period
Authors: Drummond Lisa J. , McCoubrey Jodie , Smith David G. E. , Starr John M. , Poxton Ian R.
Published: March 2003

Clostridium difficile-associated disease continues to be a major problem in hospitals and long-term care facilities throughout the developed world. Administration of certain antibiotics such as amoxycillin, oral cephalosporins and clindamycin is associated with the greatest risk of developing C. difficile disease. The two antibiotics used for treatment of C. difficile disease are vancomycin and metronidazole, to which there is currently very little resistance. Randomly selected isolates (186) from 90 patients being investigated during an 18-month epidemiological study into the disease were tested for their susceptibility to vancomycin, metronidazole, amoxycillin, clindamycin, cefoxitin and ceftriaxone by the NCCLS agar dilution method. There was a narrow range of MIC for the two treatment agents (vancomycin and metronidazole), from 0.5 to 4 μg ml−1, with no evidence of resistance. All strains were resistant to cefoxitin (MIC 64–256 μg ml−1), the antibiotic used in most selective media. All strains were of similar sensitivity to amoxycillin (MIC90= 4 μg ml−1). Most strains were resistant to ceftriaxone (MIC ≥ 64 μg ml−1) or of intermediate resistance (MIC ≥ 32 μg ml−1), with only two sensitive strains (MIC 16 μg ml−1). Clindamycin resistance was common, with 67 % of strains resistant (MIC ≥ 8 μg ml−1), 25 % with intermediate resistance (MIC ≥ 4 μg ml−1) and only 8 % sensitive (MIC ≤ 2 μg ml−1). Twelve isolates from six different patients had very high resistance to clindamycin (MIC ≥ 128 μg ml−1). Multiple isolates from the same patient, taken at different times, showed changes in susceptibility patterns over time. The only major change in susceptibility over the time-period was in clindamycin resistance; some strains appeared to become more resistant while others became less resistant. No differences were seen in the MIC50 and MIC90 of the different S-types of C. difficile identified, although some S-types were present in very small numbers. There was no correlation between the antibiotics prescribed and susceptibility.
Characterization of rifampicin-resistant Mycobacterium tuberculosis in Taiwan
Authors: Hwang Hsing-Yu , Chang Chung-Yu , Chang Lin-Li , Chang Shui-Feng , Chang Ya-Hui , Chen Yi-Jing
Published: March 2003

Sixty-three rifampicin-resistant (Rifr) isolates of Mycobacterium tuberculosis from Kaohsiung, Taiwan, were analysed for mutations in the core region (69 bp, codons 511–533) of the rpoB gene. Some 84.1 % (53/63) of the resistant isolates showed mutations in this region, especially in codons 531 (41.5 %), 526 (18.9 %), 516 (15.1 %) and 533 (7.5 %). Five novel alleles of a total of 16 different types of mutations were identified in Rifr isolates. Ten Rifr isolates (15.9 %) exhibited no mutations in the core region of rpoB. Also, they did not show mutations in another 365 bp fragment (codons 99–220) of rpoB. The agar proportion method was used to determine the relationship between the degree of rifampicin resistance and alterations in the core region of rpoB. The results revealed that the mean MIC was 92.38 μg ml−1 for the 53 isolates with a mutation in the core region, whereas the mean MIC of the other 10 isolates without mutations was only 24.8 μg ml−1. This indicates that the isolates with mutations in the core region had higher levels of resistance than those without mutations in this region. IS6110 restriction fragment length polymorphism (RFLP) was used for typing of 55 Rifr
M. tuberculosis isolates. Isolates contained two to 19 copies of IS6110, with sizes ranging from 600 to 16 000 bp. The majority (85 %) contained six to 16 copies. No strains lacking IS6110 were found. A total of 54 of 55 RFLP types were defined at the 90 % similarity level. The observation of varied IS6110-associated banding patterns indicates that an outbreak of drug-resistant tuberculosis did not occur in this area.
Effect of antimycotic agents on the activity of aspartyl proteinases secreted by Candida albicans
Authors: Schaller Martin , Krnjaic Nikola , Niewerth Markus , Hamm Gerald , Hube Bernhard , Korting Hans C.
Published: March 2003

The inhibitory effect of human immunodeficiency virus (HIV) proteinase inhibitors amprenavir and saquinavir and antifungal agents terbinafine, ketoconazole, amphotericin B and ciclopiroxolamine on aspartyl proteinases (Saps) secreted by Candida albicans was tested in an in vitro spectophotometric assay. As expected, both HIV proteinase inhibitors showed a significant inhibitory effect on Sap activity, which was comparable to that of the classical aspartyl proteinase inhibitor pepstatin A (P < 0.001). Antifungal drugs such as ketoconazole, terbinafine and amphotericin B had no, or only minor, inhibitory effects on proteolytic activity. In contrast, a significant reduction in Sap activity could be demonstrated during treatment with the antifungal agent ciclopiroxolamine (P < 0.001). These results point to a multiple effect of this antimycotic agent and might explain the reduced adherence of C. albicans to human epithelial cells at subinhibitory doses.
Detection of seven Candida species using the Light-Cycler system
Authors: White P. Lewis , Shetty Anjali , Barnes Rosemary A.
Published: March 2003

Due to the limitations of classical methods for the detection of systemic fungal infections and the high mortality rates associated with these infections, it has become essential to develop a quick, sensitive and specific detection assay. By using the Idaho Technologies Light-Cycler system, a qualitative real-time PCR system has been developed for the detection of the leading causes of systemic infection within the genus Candida. The sensitivity of the assay was comparable to previously described PCR methods (1–5 c.f.u. ml−1) and, by the use of a single Candida probe, it was able to detect, but not differentiate between, seven species of Candida (Candida albicans, Candida dubliniensis, Candida glabrata, Candida kefyr, Candida krusei, Candida parapsilosis and Candida tropicalis). Single-round amplification on the Light-Cycler allowed rapid turn-around of clinical samples (within one working day) and it was shown to be more sensitive than classical procedures, exposing 39 possible systemic infections that were not detected by blood culture.
Medium pH-dependent redistribution of the urease of Helicobacter pylori
Authors: Hong Wu , Sano Kouichi , Morimatsu Shinichi , Scott David R. , Weeks David L. , Sachs George , Goto Toshiyuki , Mohan Sharad , Harada Fumiue , Nakajima Norihito , Nakano Takashi
Published: March 2003

Helicobacter pylori is an aetiological agent of gastric disease. Although the role of urease in gastric colonization of H. pylori has been shown, it remains unclear as to where urease is located in this bacterial cell. The purpose of this study was to define the urease-associated apparatus in the H. pylori cytoplasm. H. pylori was incubated at both a neutral and an acidic pH in the presence or absence of urea and examined by double indirect immunoelectron microscopy. The density of gold particles for UreA was greatest in the inner portion of the wild-type H. pylori cytoplasm at neutral pH but was greatest in the outer portion at acidic pH. This difference was independent of the presence of urea and was not observed in the ureI-deletion mutant. Also, the eccentric shift of urease in acidic pH was not observed in UreI. After a 2 day incubation period at acidic pH, it was observed that the urease gold particles in H. pylori assembled and were associated with UreI gold particles. Urease immunoreactivity shifted from the inner to the outer portion of H. pylori as a result of an extracellular decrease in pH. This shift was urea-independent and UreI-dependent, suggesting an additional role of UreI in urease-dependent acid resistance. This is the first report of the intracellular transport of molecules in bacteria in response to changes in the extracellular environment.
Disseminated cryptococcosis in an AIDS patient caused by a canavanine-resistant strain of Cryptococcus neoformans var. grubii
Authors: Khan Z.U. , Al-Anezi A.A. , Chandy R. , Xu J.
Published: March 2003

A case of disseminated cryptococcosis caused by Cryptococcus neoformans var. grubii is presented in a male diabetic who had AIDS. The diagnosis was based upon the isolation and identification of the aetiological agent from a lymph-node biopsy, cerebrospinal fluid and sputum. The isolate formed spherical, encapsulated yeast cells, produced cherry-brown colonies on niger-seed agar, grew on canavanine-glycine-bromothymol blue (CGB) medium, changing its colour from greenish yellow to blue, and hydrolysed urea weakly in the presence of 100 μM EDTA. The strain was unable to assimilate d-proline and, serologically, it was untypable. The identity of the isolate as C. neoformans var. grubii, serotype A, possessing a mating-type allele Aα, was confirmed by crossing with standard laboratory test strains and by performing PCR with the mating-type α allele-specific primer of the STE12 gene and with serotype (A and D)- and mating type (a and α)-specific primers of the STE20 gene. To the best of our knowledge, this is the first report of disseminated cryptococcosis in an AIDS patient caused by a canavanine-resistant strain of C. neoformans var. grubii, serotype A, possessing mating type allele Aα; the strain is probably a hybrid. The report suggests that, in the absence of a clear-cut serotyping result, a positive CGB reaction alone is not sufficient for intervarietal discrimination and additional confirmatory evidence is required.
Let’s have some capatence here
Authors: Berman Brown Reva , McCartney Sean
Published: March 2003

Defines two competitive ideas – competence and capability – and argues that neither deals adequately with the central issue of the present. Provides a model, to place these ideas in conceptual space – the vertical axis of which is bounded by the extremes of narrow and broad focus, and the horizontal axis by the past and the future. Suggests that competence is on an outer edge, being narrowly focused on the performance of pre‐defined tasks, and based on the past in that it can be demonstrated in the present only if it has already been developed. Capability is on the opposite outer edge, being broadly focused on the performance of non‐defined tasks, and cannot be demonstrated in the present, because it exists as potential/future possibility or capacity. To illuminate the centre, suggests a tentative solution called “capatence” – the necessary symbiosis between competence and capability that will allow for flexibility of focus and a grounding in the present.
Entering work in the 1960s: reflections and expectations
Authors: Goodwin John , O’Connor Henrietta
Published: March 2003

The transition from school to work is a crucial component in a young person’s transition to adulthood. Recently data have emerged from one of the very first projects on school to work transitions. This research was undertaken in the early 1960s by researchers at the University of Leicester, and led by Norbert Elias. Nearly 900 interview schedules from the project “Adjustment of Young Workers to Work Situations and Adult Roles” have been discovered, which provide a significant insight into the school to work transitions of the 1960s. This paper aims to present some of this data for the first time. In particular the discussion will focus on the respondents’ reflections on education, their expectations of paid employment and their perceptions of a “good job”. The paper concludes by reflecting on the value of using such historical data and considers its implications for current debates on transitions and the expectations of school leavers.
Mentoring: the contextualisation of learning – mentor, protégé and organisational gain in higher education
Authors: Dutton Chris
Published: March 2003

This article considers the benefits for students, industry mentors and organisations of a trial mentoring project completed by the School of Service Management at the University of Brighton. The Savoy Educational Trust Mentorship Programme, a concept developed through discussions between academic staff and the School’s industry advisors, effectively matched students (protégés) with professionals from industry (mentors) for a period of one academic year. Once matched, the relationship between the student protégé and their mentor was allowed to develop and follow its own natural course. The research concludes that such a relationship can offer significant rewards for the student through the contextualisation of their learning and also through personal development. Mentors also gained significant personal satisfaction, with their employer organisations gaining access to vocationally aware graduates.
Internship and the Nova Scotia Government experience
Authors: Dodge R. Bruce , McKeough Mary
Published: March 2003

This paper explores student and graduate internships. The roles and motivation of the intern and the academic, employer and professional associations that sponsor internships are considered. An examination of the “Career Starts” Program created by the Public Service Commission of the Province of Nova Scotia, in Canada serves as a case study to consider the application of internships, practical issues and objectives associated with such a program, and the experience of individual interns. This case is interesting, as a “collective agreement” element currently limits intern access to full time employment within the government. The impact of this limitation is contrasted with conventional programs established as a “recruitment pool”. Internships are seen as a critical component of individual development and for succession planning for professional and management staff, as well as development of specialized skills. Internships are seen as providing a bridge between academic preparation, and full participation in work or a professional association that provides benefits to the intern, the academic institutions and employers or professional bodies.
Currency attacks, information externalities and search
Authors: Allsopp Louise
Published: March 2003

The currency crisis literature now comprises three main schools of thought; first‐generation models consider the depletion of foreign exchange reserves as a consequence of incompatible exchange rate and monetary policies. Second‐generation models are based on speculative theories whereby the belief of investors that monetary policy will be modified as a result of an attack makes the attack possible. Third‐generation models have been designed in an attempt to explain the nature of the Asian crises of 1997/1998. Each school of thought considers the nature of a speculative attack. However, this model uses a search framework to explain the timing of an attack in terms of an information externality in the foreign exchange market. It then assesses the efficacy of a Tobin tax in delaying and thereby possibly preventing such a crisis.
An experiment with two‐way offers into court: restoring the balance in pre‐trial negotiation
Authors: Main Brian G.M. , Park Andrew
Published: March 2003

Defendant offers into court is common procedural device aimed at increasing the probability that pre‐trial negotiations will lead to out of court settlement. Both in the UK following the Woolf Report and the Cullen Report and in the USA, the idea of extending the arrangement to plaintiff offers into court has been suggested. This paper presents an extension of the theoretical work by Chung on defendant offers into court under the US rule to cover the English rule and to extend to two‐way offers into court. It also reports on experiments conducted to measure the effect of moving to two‐way offers into court. The results suggest no impact on the propensity to settle and a statistically significant but empirically modest movement of settlement in favour of the plaintiff.
What type of economist are you: r‐strategist or K‐strategist?
Authors: Ricardo Faria João
Published: March 2003

This paper proposes a simple model to classify economists according to their preferences towards quality and/or quantity of their publications. When more emphasis is placed on quantity they are defined as r‐strategists. When they put more effort in the quality of their papers targeting top journals, they are defined as K‐strategists. It is shown that prestigious departments tend to select K‐strategists. By analyzing which strategy maximizes the influence of an economist in the profession, the paper shows that neither r‐, nor K‐strategists are the winners. The paper conjectures that the economists more likely to be successful in the profession follow the Samuelson‐strategy, which is characterized by a balance between quality and quantity.
External debt and worsening business cycles in less developed countries
Authors: Leung H.M.
Published: March 2003

Less developed countries (LDCs) have seen considerable business cycles in recent decades. At the same time they have significantly increased their external‐debt‐to‐GDP ratios. It seems natural to suspect that increased indebtedness and the amplified cycles are linked. The paper presents a simple macroeconomic model to formalize this connection. External debt is the novelty of this model. The paper's main contribution is to calibrate the dynamic parameter using the World Development Indicator. It is found that the LDC dynamic behavior is generally non‐oscillatory. Alarmingly though, the dynamic convergent system in the 1970s has been replaced by one of divergence.
Cost efficiency in ARL academic libraries
Authors: Stewart Saunders E.
Published: March 2003

Examines 88 academic member libraries of the Association of Research Libraries (ARL) to determine their relative cost efficiency, using stochastic frontier regression and data envelopment analysis (DEA) methods. Both methods give average ARL cost efficiencies of around 80 percent. This places academic ARL libraries in the same range of efficiency as other institutions, including for‐profit and non‐profit institutions. Many libraries are above 80 percent efficiency. For those below, some speculation is given for the lower efficiency. The lack of an output measure for the use of electronic sources may contribute to lower efficiency for a few libraries. Large staff size and a large number of serial subscriptions do predict lower efficiency, but this is not a necessary consequence. The DEA model allows us to determine increasing, constant, or declining returns to scale for research libraries. From this, it appears research libraries with expenditures between $10,000,000 and $20,000,000 are operating at the most efficient scale. Since the methods used are outside the repertoire of most LIS research, a conceptual explanation is provided.
How to market yourself and your library organization: a solo librarian’s guide
Authors: Adeloye Anthony
Published: March 2003

This article explores how information professionals and librarians, particularly those referred to as “one‐man bands”, can ensure a vibrant use of the library and information center (unit) in their organizations. The author notes that more often than not, lone information professionals and librarians believe the argument that because they have not been trained to “sell”, there is no point for them to market their units. But, as the author argues, lone librarians, and indeed all involved in the profession, should embrace marketing as an ally and use it to promote their work in a structured way both within and without the organization. A number of practical ideas are presented to ensure that information and library units justify their existence within an organization.
Attitudes of university library users towards overdue fines in Nigeria
Authors: Adomi Esharenana E.
Published: March 2003

This article surveys university library users’ attitudes towards overdue fines. Users of the libraries of the University of Benin, Benin City, and Delta State University, Abraka, both in Nigeria, were used as subjects for the study. A total of 143 users who responded to a questionnaire participated in the study. Frequency counts, percentages and t‐test statistic were used to analyze data. Findings revealed the users’ opinions and feelings about overdue fines. No significant difference was found between either university library with respect to their users’ attitude toward overdue fines. Neither was any discovered in attitude between genders. This paper makes recommendations that can help libraries boost the collection of overdue fines.
A weighted decision matrix for outsourcing library services
Authors: Ball David
Published: March 2003

A study, funded by Resource: The Council for Museums, Archives and Libraries, was undertaken in 2000‐2001 to give an up‐to‐date view of the current experience of outsourcing and externalization in libraries, museums and archives. Case studies of purchasers recognized as pioneers in the field, and of providers, were undertaken. As a result, this weighted decision matrix was developed as a tool for judging the suitability of library services for outsourcing. Illustrations of potential uses are given.
On the propagation of a normal shock wave through a layer of incompressible porous material
Authors: Torrens R. , Wrobel L.C.
Published: March 2003

A novel numerical formulation of the two‐phase macroscopic balance equations governing the flow field in incompressible porous media is presented. The numerical model makes use of the weighted average flux method and total variation diminishing flux limiting techniques, and results in a second‐order accurate scheme. A shock tube study was carried out to examine the interaction of a normal shock wave with a thin layer of porous, incompressible cellular ceramic foam. Particular attention was paid to the transmitted and reflected flow fields. The numerical model was used to simulate the experimental test cases, and their results compared with a view to validate the numerical model. A phenomenological model is proposed to explain the behaviour of the transmitted flow field.
The Soret effect on convection in a horizontal porous domain under cross temperature and concentration gradients
Authors: Bennacer R. , Mahidjiba A. , Vasseur P. , Beji H. , Duval R.
Published: March 2003

Natural convection with Soret effect in a binary fluid saturating a shallow horizontal porous layer is studied both numerically and analytically. The vertical walls of the enclosure are heated and cooled by uniform heat fluxes and a solutal gradient is imposed vertically. In the formulation of the problem, we use the Darcy model and the density variation is taken into account by the Boussinesq approximation. The governing parameters of the problem are the aspect ratio, A, the thermal Rayleigh number, RT, the buoyancy ratio, N, the Lewis number, Le and the Soret coefficient, NS. The analytical solution, based on the parallel flow approximation, is found to be in good agreement with a numerical solution of the full governing equations. In the presence of a vertical destabilizing concentration gradient, the existence of both natural and antinatural flows is demonstrated. When the vertical concentration gradient is stabilizing, multiple steady state solutions are possible in a range of buoyancy ratio, N, that depends strongly on the Soret coefficient, NS.
Application of the CE/SE method to two‐dimensional flow in fluid film bearings
Authors: Cioc Sorin , Keith Theo G.
Published: March 2003

A numerical scheme that has been successfully used to solve a wide variety of compressible flow problems, entitled the space‐time conservation element and solution element (CE/SE) method, is extended to predict the effects of gaseous cavitation in moderate to heavily loaded bearings. The formulation of the two‐dimensional, finite length, bearing problem is presented. The numerical results obtained are compared with other numerical solutions to demonstrate the superior ability of the method to solve such problems.
Motion of miscible magnetic fluids in a dynamic magnetic field
Authors: Chen Ching‐Yao , Liao Chi‐Yuan
Published: March 2003

Displacements of a miscible magnetic layer in a capillary tube under a moving ring‐shaped magnet are studied numerically. The magnet is adjusted dynamically to maintain a constant distance from the front mixing interface on the centerline. Control parameters, such as magnetic strength, effective viscosity variation due to magnetization, diffusion and the position of the magnet, are analyzed systematically. Motion of the magnetic layer is evaluated by two quantitative measurements, i.e. movement of center of gravity and spread of layer width. In general, the moving speed of the center of gravity depends only slightly on the magnetic strength, and is found slower at a higher viscosity ratio and a closer placement to the front interface as well if the magnet is placed amid the layer. A weaker spread occurs in situations of stronger magnetic strength, lower viscosity parameters and also placements near the rear interface. A multi‐front finger results if the magnet is positioned ahead of the front interface.
Dosimetric characteristics of a linear array of γ or β‐emitting seeds in intravascular irradiation: Monte Carlo studies for the AAPM TG‐43/60 formalism
Authors: Ye Sung‐Joon , Parsai E. Ishmael , Feldmeier John J.
Published: March 2003

In principle, the AAPM TG‐43/60 formalism for intravascular brachytherapy (IVBT) dosimetry of catheter‐based sources is fully valid with a single seed of cylindrical symmetry and in the region comparable to or larger than the mean‐free path of emitting radiation. However, for the geometry of a linear array of seeds within the few millimeter range of interest in IVBT, the suitability of the AAPM TG‐43/60 formalism has not been fully addressed yet. We have meticulously investigated the dosimetric characteristics of catheter‐basedandsources using Monte Carlo methods before applying the AAPM TG‐43/60 formalism. The dosimetric perturbation due to radiation interactions with neighboring seeds is at most 2% over the entire region of interest for thesource, while it increases to about 5% for thesource. As the transaxial distanceincreases beyond 3 mm, the sum of the dose contributions from neighboring seeds exceeds the dose contribution from the center seed for both sources. However, it continues to increase with the increasingyforbut is saturated beyondforEven within a few millimeters from the seeds, the dose from the low‐energy betas ofis still less than 1% of the total dose. The radial dose and anisotropy functions are reformulated in reduced cylindrical coordinate with the reference point atThe dose rate constant ofand the dose rate ofat the reference point showed a fairly good agreementwith earlier studies and the NIST‐traceable value, respectively. We conclude that the dosimetric perturbation caused by close proximity of neighboring seeds is nearly negligible so that the AAPM TG‐43/60 formalism can be applied to a linear array of seeds.
Three‐dimensional electron dose calculation using an improved hybrid pencil beam model
Authors: Chengjun Gou , Zhangwen Wu , Zhengming Luo , Jette David
Published: March 2003

An improved hybrid‐pencil beam model (HPBM) for electron‐beam three‐dimensional dose calculation has been studied. The model is based on the fact that away from the edges of a large field, the electron distribution function exactly equals that for an infinitely wide electron beam. In the present model, we use the bipartition model to calculate the longitudinal part of the pencil‐beam distribution function, and Fermi–Eyges multiple‐scattering theory to calculate its transverse part. In order to describe the electron beam characteristics accurately, we introduce a new parameter, which is extracted from measured profile data near the surface of a water phantom, to correct the transverse distribution determined by the Fermi–Eyges theory. Furthermore, we introduce an effective energy spectrum to describe the effect on the collimated electron beam of the accelerator head. The dose distributions calculated with the improved HPBM were compared with the experimental data, and the agreement was within 1% in most of cases. This preliminary study has demonstrated the potential for use of the model in the clinical therapy.
A volumetric method for estimation of breast density on digitized screen‐film mammograms
Authors: Pawluczyk Olga , Augustine Bindu J. , Yaffe Martin J. , Rico Dan , Yang Jiwei , Mawdsley Gordon E. , Boyd Norman F.
Published: March 2003

A method is described for the quantitative volumetric analysis of the mammographic density (VBD) from digitized screen‐film mammograms. The method is based on initial calibration of the imaging system with a tissue‐equivalent plastic device and the subsequent correction for variations in exposure factors and film processing characteristics through images of an aluminum step wedge placed adjacent to the breast during imaging. From information about the compressed breast thickness and technique factors used for taking the mammogram as well as the information from the calibration device, VBD is calculated. First, optical sensitometry is used to convert images to Log relative exposure. Second, the images are corrected for x‐ray field inhomogeneity using a spherical section PMMA phantom image. The effectiveness of using the aluminum step wedge in tracking down the variations in exposure factors and film processing was tested by taking test images of the calibration device, aluminum step wedge and known density phantoms at various exposure conditions and also at different times over one year. Results obtained on known density phantoms show that VBD can be estimated to within 5% accuracy from the actual value. A first order thickness correction is employed to correct for inaccuracy in the compression thickness indicator of the mammography units. Clinical studies are ongoing to evaluate whether VBD can be a better indicator for breast cancer risk.
Inclusion of organ deformation in dose calculations
Authors: Brock K. K. , McShan D. L. , Ten Haken R. K. , Hollister S. J. , Dawson L. A. , Balter J. M.
Published: March 2003

A previously described system for modeling organ deformation using finite element analysis has been extended to permit dose calculation. Using this tool, the calculated dose to the liver during radiotherapy can be compared using a traditional static model (STATIC), a model including rigid body motion (RB), and finally a model that incorporates rigid body motion and deformation (RBD). A model of the liver, consisting of approximately 6000 tetrahedral finite elements distributed throughout the contoured volume, is created from the CT data obtained at exhale. A deformation map is then created to relate the liver in the exhale CT data to the liver in the inhale CT data. Six intermediate phase positions of each element are then calculated from their trajectories. The coordinates of the centroid of each element at each phase are used to determine the dose received. These intermediate dose values are then time weighted according to a population‐modeled breathing pattern to determine the total dose to each element during treatment. This method has been tested on four patient datasets. The change in prescribed dose for each patient's actual tumor as well as a simulated tumor of the same size, located in the superior, intermediate, and inferior regions of the liver, was determined using a normal tissue complication model, maintaining a predicted probability of complications of 15%. The average change in prescribed dose from RBD to STATIC for simulated tumors in the superior, intermediate, and inferior regions are 4.0 (range 2.1 to 5.3), −3.6 (range −5.0 to −2.2), and −14.5 (range −27.0 to −10.0) Gy, respectively. The average change in prescribed dose for the patient's actual tumor was −0.4 Gy (range −4.1 to 1.7 Gy). The average change in prescribed dose from RBD to RB for simulated tumors in the superior, intermediate, and inferior regions are −0.04 (range −2.4 to 2.2), 0.2 (range −1.5 to 1.9), and 3.9 (range 0.8 to 7.3) Gy, respectively. The average change in the prescribed dose for the patient's actual tumor was 0.7 Gy (range 0.2 to 1.1 Gy). This patient sampling indicates the potential importance of including deformation in dose calculations.
A Monte Carlo study of IMRT beamlets in inhomogeneous media
Authors: Jones Andrew O. , Das Indra J. , Jones Frederick L.
Published: March 2003

Intensity Modulated Radiation Therapy (IMRT) has trended toward smaller multiple radiation fields thereby increasing the resolution of the intensity map. Vendors have introduced multileaf collimators with beam apertures of 0.5 cm and less. The beam characteristics of these smaller fields have not been adequately assessed, especially in the presence of inhomogeneities. Most dosimetric devices have significant limitations due to finite size, dose rate, and energy dependence. We studied the effect of inhomogeneities on small beamlets. The 6, 15, and 24 MV beams were modeled using the EGSnrc Monte Carlo code. Point source beams of circular field sizes 0.5, 1.0, 3.0, 5.0, and 10 cm were simulated in a water phantom at 100 SSD. A 3 cm inhomogeneity of lung tissue was incorporated between 3 and 6 cm in the phantom. The depth dose curves and profiles were compared by beam size and density of the inhomogeneity. The Monte Carlo simulations show that for small fields a marked dose decrease in the presence of low‐density media due to the lack of lateral electronic equilibrium is observed. As the density and field size increase, the dose reduction is less pronounced and for the 10 cm field there is an increased dose as expected due to lack of attenuation. This data suggests that current TPS may dramatically over‐ or underestimate the dose in inhomogeneous media for small field sizes that are used for IMRT.
Optimized treatment planning using intensity and energy modulated proton and very high energy electron beams
Authors: Yeboah Collins
Published: March 2003

Intensity and energy modulated radiotherapy dose planning with protons and very‐high energy (50–250 MeV) electron beams has been investigated. A general‐purpose inverse treatment planning (ITP) system that can be applied to any combination of proton, electron and photon radiation modalities in therapy has been developed. The new ITP program uses a very fast proton dose calculation engine and employs one of the most efficient optimization algorithms currently available. First, the ITP program was employed to investigate intensity‐modulated proton therapy (IMPT) dose optimization for prostate cancer. The second application was to evaluate the potential of intensity‐modulated very‐high energy electron therapy (VHEET) for dose conformation. For an active proton beam delivery system the required energy resolution to reasonably implement energy modulation was found to be a function of the incident beams' energy spread and became coarser with increasing energy spread. For passive proton beam delivery systems the selection of the required depth resolution for inverse planning may not be critical as long as the depth resolution chosen is at least equal to FWHM/2 of the primary beam Bragg peak. In the study of the number of beam ports selected for IMPT treatment of the prostate, it was found that a maximum of three to four beams is required. Using proton beams for inverse planning of the prostate instead of photon beams gave the same or better target coverage while reducing the sensitive structure dose and normal tissue integral dose by up to 30% and 28% of the prescribed target dose, respectively. In evaluating the potential of VHEET beams for dose conformation, it was found that electron energies greater than 100 MeV are preferable for VHEET treatment of the prostate and that implementation of energy modulation in addition to intensity modulation has only a modest effect on the final dose distribution. VHEET treatment employing approximately nine beams was sufficient to give good dose conformation. Compared to intensity‐modulated x‐ray therapy (IMXT) of the prostate, VHEET provided comparable target coverage but significantly greater sparing of the sensitive structures (10%) and normal tissues (12% of the prescribed target dose).