bluuebunny/crossref_metadata_2025 huggingface dataset:
Document provision and supply in less developed countries,
with particular reference to the potential of regional systems
Authors: Line Maurice B
Published: May 2006

Argues that the availability of documents in less developed
countries (LDCs) is very poor given seriously deficient library stocks
and the cost of access to external resources. Claims that the solution
commonly proposed, the sharing of resources between LDCs within regions,
is unlikely to be effective since there are no adequate resources to
share. Asserts that it is necessary to plan national availability
systems, to improve general availability generally, and meanwhile to
make heavy use of resources in developed countries.
Moving the library: the INIST experience
Authors: Wiegandt‐Sakoun Caroline , Gunet Catherine
Published: May 2006

Describes how in 1989 the Institut de l′Information Scientifique et
Technique of the French Centre Nationale de Recherche moved its
scientific and technical activities from Paris to Nancy. Discusses how
the library staff prepared a large collection of periodicals,
dissertations, research reports and congress proceedings located on
three different sites for moving to a single site; how they came up with
a theoretical model which led to a moving schedule. Finally, tells of
the actual move.
XREF: A Subject Thesaurus Generated with WordPerfect 5.0
Authors: Sprunger Kent
Published: May 2006

Presents the XREF macro which demonstrates the use of programming
variables with advanced WordPerfect macros to generate a
cross‐referencing subject thesaurus. Considers the XREF macro procedure,
structure, input file format and output file, including an example to
show how re‐running the macro generates an updated subject thesaurus.
OCLC MARC Tape Processing Using dBASE III+
Authors: Traxel Ellen , Aroksaar Richard
Published: May 2006

Explains how the Pacific Northwest Regional Library converted
catalog records from the OCLC MARC Tape Service into a working database
by loading the tapes onto a minicomputer and then downloading the data
onto diskettes. Tackles the problems that were encountered as a result
of this when the database was set up.
Education, Communication, and Cooperation: OCLC’s Preservation Program
Authors: Clareson Thomas F. R.
Published: May 2006

Reflects on the initiatives being taken by OCLC to educate
librarians about preservation of library collections. Describes the
techniques whereby libraries can create bibliographic records containing
preservation data. Reviews the research being carried out in the field
by OCLC. Examines the issues of co‐operation and training.
OCLC’s Cataloging Micro Enhancer in Decentralization
Authors: Fairchild Patricia
Published: May 2006

Describes the decentralzation of a fine arts library into a
university branch library, using CAT ME. Considers the particular
problems of fine arts cataloguing: awkwardness of handling, security,
and specialised knowledge. Surmises that rather than tying libraries to
one location, computer systems free cataloguers to work in more than one
location.
OCLC Users Council
Authors: Bierman Kenneth J.
Published: May 2006

Discusses the OCLC Users Council debate on electronic information
delivery and electronic journals. Considers the decline of paper
journals, the current thirst for information, the speed of electronic
networks, and the growing gap between costs and available resources.
Surmises that many changes wil occur in the next five years, the
electronic journal coming of age when it is recognised in academic
appointments.
A guarantee of success
Authors: Logan Marc , Oliver Jim
Published: May 2006

Offers two examples of organizations′ high achievement in training
and human resource development (HRD) together with suggestions for
maintaining organizational competitiveness. Discusses the HRD approaches
adopted by the British Multinational Manufacturing Company, and that
followed by a county council. Shows that a very simple process underlies
both successful approaches, despite the very different natures of each
organization.
The top‐flight initiative at British Airways – Part 1
Authors: O′Neill Brian
Published: May 2006

Focuses on the assessment and identification of potential at the
senior manager level. Develops a profile of leadership competence and
describes the assessment and selection process for participation on the
in‐company MBA programme. Discusses the need for a framework for
competence profiling and the principle of competence compensation.
Concludes that future‐oriented Leadership Profiles will be increasingly
important to progressive organisations.
An award‐winning training programme at R S Clare
Authors: Mackenzie Pat , Meadows Ian
Published: May 2006

Describes the two‐phase implementation of a programme to revitalise
a small manufacturing company. Explains how senior managers clearly
identified the company′s mission, goals and objectives. Notes the highly
participative workshops to assist employees to better understand
communications within the company and provide them with an awareness of
the business plan. Concludes that the success of the programme has been
the full involvement of managers in the programme of changes.
Economic Problems of Reunification in Germany
Authors: Porstmann Reiner
Published: May 2006

The situation of East and West Germany before reunification is
analysed with special emphasis on macro – and microeconomic
questions: GNP, exchange rates, productivity, consumer behaviour.
Patterns of growth in the early life history of the round herring Etrumeus teres
Authors: Plaza G. , Honda H. , Sakaji H. , Nashida K.
Published: May 2006

Early life history traits of young‐of‐the‐year (YOY) round herring Etrumeus teres, caught in Tosa Bay (south‐western Japan), were studied using otolith microstructure analysis for the 2000–2003 year classes. Hatch dates ranged from October to March, and were restricted to either autumn or winter within each year class. YOY ranged from 50 to 123 mm total length (LT) and from 57 to 192 days in age. The relationship of LT to otolith radius was linear. Individual growth rates (GI) were backcalculated between the 70th and 150th days (the size range of most YOY caught) using the biological intercept method. GI ranged from 0·3 to 1·4 mm day−1 and decreased in most cases as season progressed irrespective of year class, although GI in winter cohorts were significantly higher than in autumn cohorts. Otolith growth rates (GO) ranged from 2·13 to 12·25 μm day−1 for autumn spawned YOY and from 3·12 to 12·41 μm day−1 for YOY spawned in winter. The GO trajectories followed three consistent patterns: (1) an increase in increment widths after first feeding through the second week of larval life, then (2) a plateau in increment spacing before increment widths increased again until reaching the maximum growth rate, followed by (3) a gradual decrease in increment widths until the end of the fifth month. The three stages occurred irrespective of spawning season, although YOY spawned in October and December had higher GO during stages (1) and (2) than YOY spawned in February and March, whereas higher GO was observed for late‐winter cohorts in stage (3). Otolith growth from YOY spawned in December and January showed an intermediate pattern between YOY hatched in the early autumn (October to December) and late winter (February to March). The GO trajectories were cross‐matched to the calendar date to estimate time series of otolith growth rates (GOTS) for each year. A parabolic trend was found with maximum GOTS in autumn and spring and minimum values in winter. This trend was significantly correlated to daily sea surface temperature variations. The differences in otolith growth trajectories suggest that the otolith microstructure of E. teres may be used as a natural tag for identifying autumn and winter spawned cohorts.
Leishmania histone H1 overexpression delays parasite cell‐cycle progression, parasite differentiation and reduces Leishmania infectivity in vivo
Authors: Smirlis Despina , Bisti Sylvia N. , Xingi Evangelia , Konidou Georgia , Thiakaki Maria , Soteriadou Ketty P.
Published: May 2006

Episomal expression of Leishmania histone H1 sense mRNAs in Leishmania major promasigotes was found previously to result in overexpression of this molecule and to reduce parasite infectivity in vitro. Herein, we evaluated the in vivo infectivity of these transfectants, in BALB/c mice, and showed that it is dramatically reduced. No lesions were observed in this group of mice and this was associated with an extremely low number of parasites both in the footpad and in the draining lymph nodes. Interestingly, the transfectants‐reduced infectivity was associated with a delay in their cell‐cycle progression and differentiation to axenic amastigotes, assessed in vitro. Therefore, the dramatic reduction in their infectivity may be attributed to the above‐mentioned phenotypic modifications. As the metazoan linker histone H10 homologue is known to delay cell‐cycle progression in mammalian cells we investigated whether its Leishmania counterpart, which possesses homology to its C‐terminal region, when expressed in mammalian cells may also affect their cell‐cycle progression. It was thus shown that Leishmania histone H1 expressed in COS7 and NIH 3T3 cells, delays cell‐cycle progression in these cells too. The latter strengthens the phenotype observed in Leishmania and provides evidence that critical functions of histone H1 molecules are conserved throughout evolution.
Modelling spatial and environmental effects at the edge of the distribution: the red‐backed shrikeLanius collurioin Northern Portugal
Authors: Reino Luís , Beja Pedro , Heitor António C.
Published: May 2006

This study examined the interplay of spatial and environmental effects shaping the range margin of the red‐backed shrike (Lanius collurio) in northern Portugal. The occurrence of shrikes in 10 × 10 km UTM squares was related to three sets of explanatory variables, reflecting environmental effects (climate and habitat), large‐scale spatial trends, and neighbourhood influences (considering an autologistic term); spatial variables were used as surrogates for historical and demographic factors. Multiple logistic regression models were built for each set, and then variation partitioning based on partial regressions isolated the unique and shared components of explained variation. The environmental model revealed a dominant influence of climate effects, with the occurrence of shrikes increasing with frost and thermal amplitude, declining with insolation, and responding unimodally to rainfall. There was a weaker influence of habitat conditions, though shrikes were more likely with increasing cover by annual crops and pastures, and decreasing forest cover. Only a relatively small proportion of explained variation was due to a ‘pure’ environmental component (10.4%), as most variation explained by environmental factors appeared spatially structured (51.9%). The unique contributions of spatial variables to the overall model were also small, though the neighbourhood effects appeared relatively stronger than large‐scale trends. Taken together, results suggested that the south‐western range margin of the red‐backed shrike was largely determined by spatially structured environmental factors. Nevertheless, there were also ‘pure’ environmental factors determining some isolate occurrences irrespective of any spatial structure, and ‘pure’ spatial factors that appeared to favour the occupation of squares surrounding the core distribution areas irrespective of environmental conditions. These results add to the growing evidence that both environmental and spatial factors need to be considered in predictive modelling of species range margins.
Tacrolimus immunosuppression – An association with asymptomatic eosinophilia and elevated total and specific IgE levels
Authors: Granot E. , Yakobovich E. , Bardenstein R.
Published: May 2006

Abstract:  De novo development of food allergy is an infrequent but potentially serious complication of transplantation. An increased prevalence of food allergy noted specifically in children receiving tacrolimus immunosuppression supports the hypothesis that selective suppression of Th1 lymphocytes by the IL‐2 inhibitor immunosuppressants CsA, and the more potent drug, tacrolimus , promotes Th2 lymphocytes and an allergic immune response. This study was undertaken to characterize the IgE‐mediated immune response, in CsA and tacrolimus‐treated, post‐OLT children. Thirty children and adolescents aged 1.9–21 yr, mean: 10.6 yr, (6.4 yr post‐tx.) were studied. Immunosuppression‐CsA: 10 patients, tacrolimus; 20 patients. Blood eosinophils, total IgE levels and specific IgE antibodies (Immulite 2000 Allergy; Diagnostic Products Corp., Los Angeles, CA, USA) to a panel of food and inhaled allergens were measured and correlated with clinical symptoms of allergy. Eosinophilia (>500/mm3) range: 599–3125, mean: 1294, was present in 10/20 of patients treated with tacrolimus and 1/10 treated with CsA. IgE levels were elevated in eight of these 10 tacrolimus‐treated patients and in two CsA patients ; five were <3 yr of age and IgE levels ranged from 54 to 111 IU/mL (mean: 83), normal for age <45 IU/mL and five were ≥9 yr and IgE levels ranged from 134 to 1606 IU/mL (mean: 557), normal for age <87 IU/mL. Specific IgE levels to a wide panel of food allergens were positive in five tacrolimus‐treated patients and to both food and inhaled allergens in three patients (two tacrolimus‐treated, one CsA). Four children (tacrolimus‐treated) had symptoms of food allergy . None had a family history of allergy. Eosinophilia is present in up to 50% of children and adolescents receiving tacrolimus immunosuppression. The majority of these patients also have elevated levels of total and specific (mainly to food allergens) IgE antibodies. Most patients are asymptomatic and do not manifest food allergy or asthma.
Polyoma virus in pediatric renal transplantation
Authors: Acott Philip D.
Published: May 2006

Abstract:  Renal transplantation is the treatment of choice for children with end‐stage renal disease. Patient survival and allograft survival have improved with better immunosuppressant regimes to reduce acute allograft rejection but post‐transplant infections have been exacerbated. An emerging problematic virus in the past decade is the polyoma virus BKV. The features of BKV including the clinical features in the general and immune compromised population are reviewed and correlated with pediatric studies in the post‐transplant population. These features are placed in context with lessons learned about BKV in relevant adult studies.
Incidence of positive pelvic lymph nodes in patients with prostate cancer, a prostate‐specific antigen (PSA) level of ≤10 ng/mL and biopsy Gleason score of ≤6, and their influence on PSA progression‐free survival after radical prostatectomy
Authors: WECKERMANN DOROTHEA , GOPPELT MARCUS , DORN ROBERT , WAWROSCHEK FRIEDHELM , HARZMANN ROLF
Published: May 2006

OBJECTIVE

To investigate how many men with low‐risk prostate cancer had positive lymph nodes detected by radio‐guided surgery and whether they had a higher biochemical relapse rate after radical prostatectomy, because in such patients most urologists dispense with operative lymph node staging, as nomograms indicate only a low percentage of lymph node metastases.

PATIENTS AND METHODS

The study included 474 men with a prostate‐specific antigen (PSA) level of ≤ 10 ng/mL, biopsy Gleason score of ≤ 6 and positive biopsies in one (group 1, 315 men) or both lobes (group 2, 159 men); follow‐up data were available in 357 men. Men with adjuvant radiation or hormone therapy before the occurrence of biochemical relapse were excluded.

RESULTS

Positive lymph nodes were detected in 17 men in group 1, and in 18 in group 2. In more than half of the patients (19/35) these nodes were found outside the region of standard lymphadenectomy. Men with node‐positive disease had a higher biochemical relapse rate (P < 0.001). When the tumour was organ‐confined and well differentiated in node‐positive disease (Gleason score ≤ 6) the biochemical relapse rate was lower than in men with higher tumour stage and grade.

CONCLUSIONS

When dissecting pelvic lymph nodes, extended or sentinel lymphadenectomy should be preferred. Removing the diseased nodes could improve the PSA progression‐free survival, especially in well differentiated organ‐confined disease.
Infants' Attention to Patterned Stimuli: Developmental Change From 3 to 12 Months of Age
Authors: Courage Mary L. , Reynolds Greg D. , Richards John E.
Published: May 2006

To examine the development of look duration as a function of age and stimulus type, 14‐ to 52‐week‐old infants were shown static and dynamic versions of faces, Sesame Street material, and achromatic patterns for 20 s of accumulated looking. Heart rate was recorded during looking and parsed into stimulus orienting, sustained attention, and attention termination phases. Infants' peak look durations indicated that prior to 26 weeks there was a linear decrease with age for all stimuli. Older infants' look durations continued to decline for patterns but increased for Sesame Street and faces. Measures of heart rate change during sustained attention and the proportion of time spent in each phase of attention confirmed infants' greater engagement with the more complex stimuli.
Restrictions on Provider Access in Health Plans and Socioeconomic Status
Authors: Deb Partha , Trivedi Pravin K.
Published: May 2006

Objective. To model the socioeconomic determinants of restrictions on provider access and choices in health plans.

Data Sources. Data from the 1996–97 Community Tracking Study are used. Publicly available enrollee data including enrollee reports of health care plan characteristics are linked with restricted use data with insurer reports of health plan characteristics.

Study Design. This is an observational study. A mixed multinomial logit model is used to model the enrollees' choice between health plans, each plan being treated as a bundle of attributes formed from restrictions on provider access.

Principal Findings. There are important differences between the enrollee responses and the insurer reports, which may be due to poor information dissemination on the part of health plans and/or lack of attention on the part of enrollees. There is no evidence of selection into plans with restrictive attributes on the basis of observed health status but there is evidence of selection on the basis of race, ethnicity, gender and other socioeconomic characteristics. Determinants of plan supply, i.e., employment characteristics, are the most important determinants of plan attribute choices.

Conclusion. The finding suggests that plan designs optimized using “objective” knowledge and with the best intentions may not receive favorable reviews from enrollees because enrollees have different perceptions of these plans.
Reviews: Diagnosis and Management of Sleep Apnea Syndrome and Restless Legs Syndrome in Dialysis Patients
Authors: Novak Marta , Mendelssohn David , Shapiro Colin M. , Mucsi Istvan
Published: May 2006

Sleep complaints are very common in patients with end‐stage renal disease (ESRD) and contribute to their impaired quality of life. Both obstructive and central sleep apnea syndromes are reported more often in patients on dialysis than in the general population. Impaired daytime functioning, sleepiness, and fatigue, as well as cognitive problems, are well known in patients with sleep apnea. Increasing evidence supports the pathophysiological role of sleep apnea in cardiovascular disorders, which are the leading cause of death in ESRD patients. Uremic factors may be involved in the pathogenesis of sleep apnea in this patient population and optimal dialysis may reduce disease severity. Furthermore, treatment with continuous positive airway pressure may improve quality of life and may help to manage hypertension in these patients. Secondary restless legs syndrome is highly prevalent in patients on maintenance dialysis. The pathophysiology of the disorder may also involve uremia‐related factors, iron deficiency, and anemia, but genetic and lifestyle factors might also play a role. The treatment of restless legs syndrome involves various pharmacologic approaches and might be challenging in severe cases. In this article we review the diagnosis and treatment of sleep apnea and restless legs syndrome, with a focus on dialysis patients. We also briefly review current data regarding sleep problems after transplantation, since these studies may indirectly shed light on the possible pathophysiological role of uremia or dialysis in the etiology of sleep disorders. Considering the importance of sleep disorders, more awareness among professionals involved in the care of patients on dialysis is necessary. Appropriate management of sleep disorders could improve the quality of life and possibly even impact upon survival of renal patients.
Burden of Clostridium Difficile‐Associated Diarrhea in a Long‐Term Care Facility
Authors: Laffan Alison M. , Bellantoni Michelle F. , Greenough William B. , Zenilman Jonathan M.
Published: May 2006

OBJECTIVES: To describe the incidence and prevalence of Clostridium difficile–associated diarrhea (CDAD) in a long‐term care facility (LTCF).

DESIGN: Retrospective review of CDAD cases between July 2001 and December 2003.

SETTING: Two hundred two–bed LTCF affiliated with an academic medical center in Baltimore, Maryland.

PARTICIPANTS: All residents of the facility during July 2001 to December 2003.

MEASUREMENTS: Clinical and laboratory‐confirmed cases of CDAD.

RESULTS: Incidence of CDAD ranged from 0 to 2.62 cases per 1,000 resident days. The highest rates were observed in residents of subacute units, whereas incidence was much lower on traditional nursing home units. Prevalence of CDAD at admission was greater on units (subacute and rehabilitative) where the majority of patients were admitted from hospital settings than on those where the majority of patients were admitted from the community (nursing home units). Recurrent disease occurred in 21.7% of patients with CDAD.

CONCLUSION: CDAD remains a problem in the long‐term care setting, and importation from the acute care setting accounts for a large proportion of the C. difficile seen LTCFs. As the population continues to age, issues of disease and infection in long‐term care are expected to increase. New prevention and control strategies are needed to control the spread of CDAD in LTCFs.
Consumer‐Phase Salmonella enterica serovar Enteritidis Risk Assessment for Egg‐Containing Food Products
Authors: Mokhtari Amirhossein , Moore Christina M. , Yang Hong , Jaykus Lee‐Ann , Morales Roberta , Cates Sheryl C. , Cowen Peter
Published: May 2006

We describe a one‐dimensional probabilistic model of the role of domestic food handling behaviors on salmonellosis risk associated with the consumption of eggs and egg‐containing foods. Six categories of egg‐containing foods were defined based on the amount of egg contained in the food, whether eggs are pooled, and the degree of cooking practiced by consumers. We used bootstrap simulation to quantify uncertainty in risk estimates due to sampling error, and sensitivity analysis to identify key sources of variability and uncertainty in the model. Because of typical model characteristics such as nonlinearity, interaction between inputs, thresholds, and saturation points, Sobol's method, a novel sensitivity analysis approach, was used to identify key sources of variability. Based on the mean probability of illness, examples of foods from the food categories ranked from most to least risk of illness were: (1) home‐made salad dressings/ice cream; (2) fried eggs/boiled eggs; (3) omelettes; and (4) baked foods/breads. For food categories that may include uncooked eggs (e.g., home‐made salad dressings/ice cream), consumer handling conditions such as storage time and temperature after food preparation were the key sources of variability. In contrast, for food categories associated with undercooked eggs (e.g., fried/soft‐boiled eggs), the initial level of Salmonella contamination and the log10 reduction due to cooking were the key sources of variability. Important sources of uncertainty varied with both the risk percentile and the food category under consideration. This work adds to previous risk assessments focused on egg production and storage practices, and provides a science‐based approach to inform consumer risk communications regarding safe egg handling practices.
A Note on the Inoperability Input‐Output Model
Authors: Percoco Marco
Published: May 2006

In this note, we propose some comments and some extensions of the inoperability input‐output model (IIOM), as recently proposed by Santos and Haimes (2004). In particular, we propose the use of some analytic tools capable of providing information on the reaction of sectors subsequent to a terrorist attack on infrastructure service sectors. These tools, namely, the field of influence and the multiplier product matrix, provide information on the way sectors react to a shock on the aggregate demand and/or to a (temporary or permanent) change of production function coefficients. Finally, using the 2003 65 sectors input‐output matrix for the U.S. economy, a simple empirical example is presented.
The effect of β‐aminobutyric acid on the growth of herbivorous insects feeding on Brassicaceae
Authors: Hodge S. , Pope T.W. , Holaschke M. , Powell G.
Published: May 2006

dl‐β‐Aminobutyric acid (BABA) is a nonprotein amino acid that can enhance defences in a variety of plants against a wide range of pathogens. BABA can also reduce infestation by phytopathogenic nematodes and has recently been shown to suppress the growth of aphids feeding on legumes. This investigation examined the effect of applying BABA as a root drench to a range of Brassicaceae, including Arabidopsis thaliana, on the performance of two species of aphid (Myzus persicae and Brevicoryne brassicae) and the larvae of two species of Lepidoptera (Trichoplusia ni and Plutella xylostella). Application of BABA reduced the performance of all four insect species, and inhibition of insects occurred on all the plants tested. The results illustrate that BABA‐induced resistance (BABA‐IR) can affect generalist and specialist insect herbivores and inhibit insects feeding with mandibulate as well as sap‐feeding mouthparts. The BABA‐induced suppression of B. brassicae and P. xylostella feeding on A. thaliana provides a means to further examine the mechanisms of BABA‐IR to insects using this model plant.
Experimental Investigation of the Machinability of Polycarbonate Reinforced With Multiwalled Carbon Nanotubes
Authors: Samuel J. , DeVor R. E. , Kapoor S. G. , Hsia K. J.
Published: May 2006

The machinability of a polycarbonate nanocomposite containing multiwalled carbon nanotubes is investigated and contrasted with its base polymer and with a conventional carbon fiber composite. The material microstructures are characterized using transmission electron and scanning electron microscopy methods. Micro-endmilling experiments are conducted on the three materials. Chip morphology, machined surface characteristics, and the nature of the cutting forces are employed as machinability measures for comparative purposes. Polycarbonate chips are seen to transition from being discontinuous to continuous as the feed-per-tooth (FPT) increases, while, at all FPT values the nanocomposite is seen to form comparatively thicker continuous chips. The nanocomposite and the carbon fiber composite are seen to have the lowest and the highest magnitudes, respectively, for both the surface roughness and cutting forces. Shearing along the nanotube-polymer interface and better thermal conductivity are speculated to be the mechanisms responsible for the observations seen in the nanocomposite.
A New Method for Measuring Straightness and Yawing Motion Errors of a Linear Slide
Authors: Fung Eric H. K.
Published: May 2006

In this paper, an on-machine Fourier five-sensor (F5S) measurement method is developed using Fourier series and sensor integration techniques to determine the straightness and yawing motion errors of a linear slide. The profile of the slide is also determined in this error separation technique. The method is an extension of the previous Fourier three-sensor (F3S) method (Fung, E. H. K., and Yang, S. M., 2000, “An Error Separation Technique for Measuring Straightness Motion Error of a Linear Slide,” Meas. Sci. Technol., 11, pp. 1515–1521; Yang, S. M., Fung, E. H. K., and Chiu, W. M., 2002, “Uncertainty Analysis of On-Machine Motion and Profile Measurement With Sensor Reading Errors,” Meas. Sci. Technol., 13, pp. 1937–1945) by including the effects of yawing error in the straightness motion error and profile measurements. The principles and operation of the F5S measurement method are described. The uncertainty analysis of the method in the presence of a sensor reading error is studied both in the frequency domain and the spatial domain. The spatial domain parameter is first optimized to yield the 12 possible sensor configurations and the final configuration is chosen based on the frequency domain parameter values. The method is evaluated by computer simulation where the simulated sensor outputs are derived from the predefined profile, straightness, and yawing motion errors. By comparing the calculated results with the input data, the F5S method is found to be superior to the F3S method as far as accuracy is concerned. The results reported in this simulation study not only confirm the feasibility of the F5S method but also encourage the author to perform an experimental study in the near future.
Time resolved electroluminescence measurements on GaAs and GaN devices
Authors: Hulse J. E. , Sarault K. , Rowell N. L. , Simard-Normandin M. , Bardwell J. A.
Published: May 2006

Time correlated single photon electroluminescence maps have been recorded on operating semiconductor devices with a spatial resolution approaching 1μm and a time resolution of 50 ps. The technique is noninvasive and observes signal wave forms optically, directly at the device. Spectral measurements in the near infrared and visible were also performed. Two examples of the application of this technique to semiconductor devices are presented. An AlGaAs∕GaAs heterojunction bipolar transistor typical of high speed bipolar devices used in rf circuitry, and an AlGaN∕GaN heterostructure field-effect transistor as an example of the application of optical techniques in characterizing the emerging technology.
Organic monolayers detected by single reflection attenuated total reflection infrared spectroscopy
Authors: Rowell N. L. , Tay L. , Lockwood D. J. , Baribeau J.-M. , Bardwell J. A. , Boukherroub R.
Published: May 2006

A single-reflection attenuated total reflection (ATR) technique has been used to study low index monolayers with a high index ATR hemisphere in an optical contact with the sample surface. A model calculation predicts a field enhancement with the present method substantially larger than that of conventional ATR. For the present method, a discontinuity of the field normal to the film is responsible for the field enhancement in the lower index thin film. We show theoretically and experimentally that the angle of incidence has a strong influence on the ATR signal strength. We demonstrate the present method by examining the infrared reflectance spectra of a undecylenic acid self-assembled on Si (111) and with the adsorption of a bovine serum albumin monolayer. We also apply the method to examine the oxidation and surface contamination of the functionalized Si samples stored in ambient conditions.
Fabrication of out-of-plane micromirrors in silicon-on-insulator planar waveguides
Authors: Lamontagne B. , Cheben P. , Post E. , Janz S. , Xu D.-X. , Delâge A.
Published: May 2006

Emerging optical waveguide spectrometers, sensors, and biochips require the simultaneous acquisition of numerous optical signals. Aligning many tens or hundreds of optical fibers to waveguides is a formidable and costly exercise in packaging. We propose a data acquisition scheme using arrays of micromirrors to redirect light propagating in each waveguide out of the device surface, where all the beams can be collected by a single imaging array. Micromirrors, which are the key elements in this data acquisition scheme, were fabricated in 2μm thick silicon-on-insulator waveguides. Chemically assisted ion beam etching (CAIBE) was used to obtain inclined mirror facets, benefiting from the unique capability of CAIBE to tilt the sample relative to the ion beam. Finite difference time domain (FDTD) simulations of an ideal micromirror oriented at 45° to the propagation direction predict a >96% out-coupling efficiency (loss of 0.14dB) and a negligible polarization dependent loss (PDL). The measured total insertion loss for the fabricated waveguide and mirror was −5dB, including fiber-to-waveguide coupling loss, waveguide propagation loss, and mirror loss due to fabrication errors and diffraction, with a PDL of 0.7dB. The dependence of micromirror performance on facet angle and etch depth was studied by FDTD simulations. The influence of CAIBE etching chemistry and selectivity in obtaining optimum mirror parameters is discussed.
Characterization and modeling of AlGaN∕GaN heterostructure field effect transistors for low noise amplifiers
Authors: Knox S. H. , Rogers J. W. M. , Chyurlia P. N. A. , Tarr N. G. , Bardwell J. A. , Tang H. , Haffouz S.
Published: May 2006

A simple equivalent circuit model including noise sources for the GaN heterostructure field effect transistor is presented and analyzed. The model is used to determine optimum source impedance for low noise amplifier applications. A good agreement between the model and measured NFmin of experimental devices is shown. Prototype transistors with a 0.75μm gate length and 80μm width delivered a power-added efficiency of 45.6% and a minimum noise figure of 2.1dB at 2.4GHz when operated from a 48V supply. Gate leakage current was found to be an important noise source.
Microelectromechanical system based variable optical attenuator by vertically bending waveguides
Authors: Zhang Guhong , Jessop Paul E.
Published: May 2006

A variable optical attenuator based on electrostatic bending of a silicon-on-insulator rib waveguide was designed and fabricated. Microelectromechanical system fabrication techniques were used to remove the underlying silica layer in a section of a silicon-on-insulator waveguide, creating a deformable beam structure. The observed dependence of the optical attenuation on applied voltage agreed well with numerical modeling, which indicates that the attenuation is due to conversion to lossy higher order modes at the waveguide bends rather than radiation into the air cover or the substrate. Electrostatic zipping actuation was shown to be more effective in achieving sufficient curvature than direct bending of a fixed-fixed beam before pull in. A typical 1mm long device showed a maximum voltage tunable attenuation of up to 14dB.
Temperature effects in complementary metal-oxide semiconductor microwave distributed amplifiers
Authors: Ranuárez J. C. , Deen M. J. , Chen C. H.
Published: May 2006

Broadband amplifiers implemented in complementary metal-oxide semiconductor technology offer a low-cost solution as gain elements for wideband communication systems. These components must maintain an acceptable target performance for a wide range of temperatures. We present experimental results for the gain, reflection coefficients, and group delay of a broadband amplifier operating from 2to14GHz in the temperature range of 25–125°C. The high-frequency power gain drops by approximately 0.37dB every 10°C of temperature increase, the maximum input and output refection coefficients change by less than 0.1dB∕10°C, and the change in the input-to-output group delay is negligible over the measured temperature range. The amplifier was simulated using temperature-dependent measurement-based models for the transistors, capacitors, and resistors and a single-temperature electromagnetic-simulation-based model for the inductors and interconnections. Simulated gain degradation is 0.22dB∕10°C, which suggests that the temperature effects on the inductors and interconnections lines are very important; however, temperature-dependent simulation is not a standard feature of electromagnetic (EM) simulators. It is thus important to include temperature effects when developing models based on EM simulations. Our results suggest that the key element to be considered is the conductor’s resistivity increase with temperature.
Rhodium(I) acetylacetonato complexes containing phosphinoalkynes as catalysts for the hydroboration of vinylarenes
Authors: Vogels Christopher M , Decken Andreas , Westcott Stephen A
Published: May 2006

Three novel rhodium(I) acetylacetonato (acac) complexes bearing phosphinoalkynes (Ph2PC≡C-t-Bu, Ph2PC≡CPPh2, and Ph2PC≡CC≡CPPh2) have been prepared and characterized fully. Addition of B2cat3 (cat = 1,2-O2C6H4) to Rh(acac)(Ph2PC≡C-t-Bu)2 (1a) led to zwitterionic Rh(η6-catBcat)(Ph2PC≡C-t-Bu)2 (2a), the first example of this type of compound to contain monodentate phosphine ligands. All new rhodium complexes have been investigated for their ability to catalyse the hydroboration of vinylarenes.Key words: catalysis, hydroboration, phosphinoalkynes, regioselectivity, rhodium.
Thermodynamic investigations of zeolites NaX and NaY
Authors: Qiu Liyan , Laws Patricia A , Zhan Bi-Zeng , White Mary Anne
Published: May 2006

Understanding of the thermodynamic stability of zeolites is important in the prediction of thermodynamic equilibrium. Therefore, we have undertaken an investigation of the thermodynamic stability of the zeolites NaX and NaY through heat capacity measurements from ca. 30 to 300 K. No phase transitions were observed, and zeolite NaX does not show a significant particle size effect when the particle size is reduced to ca. 30 nm. The results show that the specific heat capacity increases with the Al content in the zeolite. Both NaX and NaY are found to be thermodynamically stable with respect to their elements because of enthalpic stabilization and with slight entropic destabilization. These data are used along with literature data for many other zeolitic materials to show that the thermodynamic stability of zeolites is enhanced with increasing aluminum content. Key words: zeolite, heat capacity, thermodynamic stability, nano effects.
Systematic sequences of well-balanced Gaussian basis sets
Authors: Klobukowski Mariusz
Published: May 2006

Systematic sequences of Gaussian basis sets with controlled energy errors for the studies of convergence of the basis set effects on the computed results of molecular calculations are presented. The basis sets were prepared for atoms H–Ne and Al–Ar and may be used in systematic ab initio ad limitem studies of molecular structure and properties.
Surface and interfacial tensions of aqueous dispersions of charged colloidal (clay) particles
Authors: Schramm Laurier L. , Hepler Loren G.
Published: May 2006

We have measured (du Nouy ring and maximum bubble pressure methods) suspension–air surface tensions of aqueous suspensions of montmorillonite and have observed that these surface tensions are larger than those of pure water at the same temperatures. Further measurements have shown that dispersed montmorillonite also increases the suspension–toluene interfacial tension compared with that of pure water–toluene. Similar measurements on aqueous suspensions of kaolinite have yielded suspension–air interfacial tensions with uncertainties as large as the observed (small) effect, and also shown that the suspension–toluene interfacial tension is decreased (opposite to the effect of montmorillonite) by amounts larger than the experimental uncertainties. Measurements of maximum bubble pressures at different flow rates have provided information about the effect of surface age on observed surface tensions.
Weiss's endo- and exo-tetracyclo[5.5.1.0.2,6 010,13]tridecane-4,8,12-trione: analysis of 1H NMR couplings in a system of fused 5-membered rings
Authors: Bertz Steven H. , Zhang Weijiang , Cook James M. , Bruch Martha D. , Jelinski Lynn W.
Published: May 2006

The configurational isomers of the title compounds consist of four fused five-membered rings. They contain tightly coupled 1H NMR spin systems, which provide excellent models for establishing the relationships between coupling constants and conformation. Complete chemical shift assignments and spin–spin coupling constants are reported for the title compounds by using high-field (500 MHz) 1H NMR techniques (e.g., 2D homonuclear and heteronuclear experiments, difference NOE enhancements, and computational spin simulations). In addition to the more familiar two- and three-bond couplings, the spectra of 1 and 2 also contain a number of long-range (four- and five- bond) couplings, which provide a stringent test of Barfield's theoretical treatment of four-bond couplings.
Excited state acid catalysis of the 2 + 2 photocycloaddition of methyl 2-naphthoate and acetylacetone; the interaction of a nonfluorescent exciplex with H2SO4
Authors: Chow Yuan L. , Johansson Carl I.
Published: May 2006

In this paper, the striking acid catalysis of the photocycloaddition of methyl 2-naphthoate (2MN) to acetylacetone (AA) to give 1 and 2 was traced to the enhanced conversion of the nonemissive *(2MN–AA) exciplex to 1 and 2 by H2SO4. The partial reversibility of the exciplex in CH3CN and CH3OH was established by extended fluorescence-quenching analysis using oxygen to perturb the system, whereas time-resolved fluorescence kinetics failed to reveal the presence of this exciplex. A similar analytical method demonstrated the interaction of the nonfluorescent *(2MN–AA) exciplex and H2SO4 with the rate constants of kap = (2 ± 1) × 109 M−1 s−1 in CH3CN and (4 ± 1) × 109 M−1 s−1 in CH3OH. The quantum yield of photocycloadducts was significantly enhanced at high 2MN conversions owing to the retardation of the competing excimer *(2MN)2 formation. In the range of low conversion (< 15%) and [H2SO4] ≤ 1 mM, the quantum yield was shown to be proportional to H2SO4 concentration; the slope from such plots was analyzed to give kap values similar to those obtained from the extended fluorescence-quenching analysis. This agreement, along with the elimination of other potential acid catalytic routes, unambiguously proves that the acid catalysis originates from the interaction of the *(2MN–AA) exciplex with H2SO4.
Spruce budworm (Choristoneura fumiferana) antifeedants 4. Synthesis of specionin and biological studies
Authors: Mohammad-Ali Anmar K. , Chan T.H. , Thomas A.W. , Jewett B. , Strunz G.M.
Published: May 2006

Specionin (1) was synthesized in seven steps from aucubin (2), an abundant iridoid form aucuba japonica. In a "no-choice" bioassay, specionin and several of its derivatives showed only modest antifeedant activity against the spruce budworm, while other derivatives were devoid of activity.
A comparison of nickel boride and Raney nickel electrode activity in the electrocatalytic Hydrogenation of Phenanthrene
Authors: Mahdavi Behzad , Los Przemyslaw , Lessard Marie Josée , Lessard. Jean
Published: May 2006

The electrocatalytic activity of nickel boride in the electrocatalytic hydrogenation (ECH) of phenanthrene in ethylene glycol–water at 80 °C has been compared to that of Raney nickel and fractal nickel. The intrinsic activity of the electrode material (real electrode activity) is the same for nickel boride and Raney nickel electrodes and is lower for fractal nickel electrodes. The apparent electrode activity of nickel boride pressed powder electrodes (Ni2B electrodes) is less than that of codeposited Raney nickel (RaNi) electrodes and pressed powder fractal nickel/Raney nickel (Ni/RaNi = 50/50 to 0/100) electrodes. The apparent activity of Ni2B electrodes is improved by adding sodium chloride to the powder and dissolving it after pressing (Ni2B–NaCl electrodes). The Ni2B–NaCl electrodes have the same apparent activity as codeposited RaNi and pressed powder Ni/RaNi (20/80 to 0/100) electrodes. The apparent and real electrode activity of Ni/RaNi electrodes increases with the RaNi content up to a 20/80 ratio. The Tafel and alternating current (ac) impedance parameters were determined for the hydrogen evolution reaction (HER) in 1 M aqueous sodium hydroxide at 25 °C at nickel boride and at codeposited RaNi electrodes. The intrinsic electrocatalytic activity for HER, expressed by the ratio of the exchange current density over the roughness factor (I0/R), is similar for Ni2B, Ni2–NaCl, and codeposited RaNi electrodes. Surface characterization of Ni2B and Ni2B–NaCl electrodes was carried out by BET, ac impedance, scanning electron microscopy, and mercury porosimetry. No direct relation between the apparent electrode activity in ECH and the surface measured by BET and ac impedance was found. The ac impedance measurements were also carried out in the presence of sodium trans-cinnamate.
Silver nitrate in aqueous solution and as molten salt: A molecular dynamics simulation and NMR relaxation study
Authors: Laaksonen Aatto , Kovacs Helena
Published: May 2006

Using molecular dynamics simulations, the motion and intermolecular interactions of the ions of silver nitrate are studied in aqueous solution and compared to the results obtained from simulations of molten AgNO3. The particularly interesting and experimentally frequently studied modes of reorientational motion (in-plane and end-over-end) of the planar nitrate ion have been determined from the simulation results. In accordance with earlier experimental results, the correlation times for the end-over-end rotation in aqueous solution are longer than those for the in-plane rotation, while the opposite is found to hold in the melt. In addition, the rotational motion of the nitrate ion in aqueous solution is experimentally studied using 14N relaxation measurements. Good agreement is found between the reorientational correlation times obtained from MD simulations and from NMR relaxation measurements.
Influence of oxidative treatment of copper grid electrodes on the efficiency of conversion to aniline in the electroreduction of nitrobenzene and azobenzene in basic aqueous methanol
Authors: Martel Anna , Cheong Amoy Kam , Lessard Jean , Brossard Louis
Published: May 2006

The influence of preoxidizing the surface of polycrystalline copper electrodes on the efficiency of the controlled potential electrochemical reduction of nitrobenzene and azobenzene to aniline in basic aqueous methanol has been investigated. Electrodes electrochemically preoxidized to Cu(OH)2 or to Cu2O gave high yields of aniline (90–100%) with high current efficiencies (88–99%) for the electrohydrogenation of nitrobenzene compared to electrodes preoxidized by air (7–29% of aniline, 64–74% current efficiency). For the electrohydrogenation of azobenzene, copper electrodes preoxidized to Cu2O were found to be more active (average yield of aniline of 28%, average current efficiency of 55%) than electrodes preoxidized to Cu(OH)2 (3–11% of aniline, 42–53% current efficiency), and electrodes preoxidized by air were inactive (the electrohydrogenation stopped at hydrazobenzene). The improvement of activity induced by preoxidation of the copper surface is linked to the increase of the surface area.
General analytical solution for a reversible i/t response to a double potential step at spherical electrodes in the absence/presence of amalgamation effects
Authors: Molina A. , Serna C. , Chicón R. , Camacho L. , Ruiz J. J.
Published: May 2006

The general rigorous theory corresponding to double potential step chronoamperometry for a reversible charge transfer reaction in a spherical electrode whose area increases with tz, where z ≥ 0, is presented. The static mercury drop electrode (z = 0) and the dropping mercury electrode (z = 2/3) are addressed specifically. The explicit equations for the current versus time response assuming unequal diffusion coefficients for the oxidized and reduced species are valid when the product is soluble in both the electrolytic solution and the electrode. Comparisons with previous general treatments in the literature are made. The theory is applied to the detection of amalgamation in RP and DNP techniques.Moreover, in this work we show the origin of errors appearing in some general treatments in the literature, these errors lead to physically meaningless results when amalgamation takes place.