bluuebunny/crossref_metadata_2025 huggingface dataset:
Fuel Cell Vehicle Simulation – Part 1: Benchmarking Available Fuel Cell Vehicle Simulation Tools
Authors: Hauer K.H. , Moore R.M.
Published: December 2003

Fuel cell vehicle simulation is one method for systematic and fast investigation of the different vehicle options (fuel choice, hybridization, reformer technologies). However, a sufficient modeling program, capable of modeling the different design options, is not available today. Modern simulation programs should be capable of serving as tools for analysis as well as development. Shortfalls of the existing programs, initially developed for internal combustion engine hybrid vehicles, are: (i)Insufficient modeling of transient characteristics; (ii) Insufficient modeling of the fuel cells system; (iii) Insufficient modeling of advanced hybrid systems; (iv) Employment of a non‐causal (backwards looking) structure; (v) Significant shortcomings in the area of controls.

In the area of analysis, a modeling tool for fuel cell vehicles needs to address the transient dynamic interaction between the electric drive train and the fuel cell system. Especially for vehicles with slow responding on‐board fuel processor, this interaction is very different from the interaction between a battery (as power source) and an electric drive train in an electric vehicle design. Non‐transient modeling leads to inaccurate predictions of vehicle performance and fuel consumption. When applied in the area of development, the existing programs do not support the employment of newer techniques, such as rapid prototyping. This is because the program structure merges control algorithms and component models, or different control algorithms (from different components) are lumped together in one single control block and not assigned to individual components as they are in real vehicles. In both cases, the transfer of control algorithms from the model into existing hardware is not possible. This paper is the first part of a three part series and benchmarks the “state of the art” of existing programs. The second paper introduces a new simulation program, which tries to overcome existing barriers. Specifically it explicitly recognizes the dynamic interaction between fuel cell system, drive train and optional additional energy storage.
Hydrogen Automobile Heads Toward Series Production HydroGen3 Puts Fuel Cells on the Road
Authors: Winter U. , Herrmann M.
Published: December 2003

General Motor's concept vehicle HydroGen3, based on the Opel Zafira production model, represents the third generation of fuel cell concept vehicles. Groundbreaking new technical and engineering improvements have been reached, e.g. the integration of the latest generation of fuel cell stacks. The fleet demonstrations will start this year. Given the current stage of development at GM/Opel, hydrogen‐powered automobiles could be mass‐produced in about eight years. An efficient fuel cell technology suitable for everyday use is the essential pre‐condition for the development of an alternative propulsion system, which would replace the classic crude oil‐based fuels for the vehicles of the future. However, this technology alone is not sufficient to establish fuel cell automobiles as viable substitutes for conventional vehicles with gasoline and diesel engines. Factors such as purchase price, safety, engine performance and driving dynamics also play a decisive role for the customer. General Motors (GM) has therefore invested more than one billion dollars to develop an automobile incorporating state‐of‐the‐art fuel cell technology with vehicle characteristics suited to the marketplace. The hydrogen concept vehicle HydroGen3 (Figure 1) marks the newest and most comprehensive advance made by GM/Opel on the road to fuel cell vehicle market readiness. Test drives conducted by an international group of expert journalists at the Grand‐Prix course in Monte Carlo in December 2002 confirmed that the HydroGen3 has brought mass production of hydrogen‐fuelled automobiles within reach.
Hydrogen for the Mobility of the Future Results of GM/Opel's Well‐to‐Wheel Studies in North America and Europe
Authors: Winter U. , Weidner H.
Published: December 2003

General Motors conducted two well‐to‐wheel studies for fundamental clarification on the question of which is the cleanest and most environmentally sustainable source of energy for the mobility of the future. In both studies the complete energy chains were analyzed from fuel production using primary energy to the actual consumption of the fuel in the car, i.e. from the well up to the wheels of the vehicle (well to wheel). The aim of the studies was to evaluate total energy consumption on the one hand and, on the other, the total greenhouse gas emissions arising between the production of a fuel and its final use to power an automobile. The results of the studies clearly show that fuel cell vehicles can greatly reduce greenhouse gas emissions from passenger cars or, if they run on hydrogen from renewable energy sources, they can eliminate them entirely. Regenerative fuels, however, will be more expensive than current products. With the fuel cell, because of its superior efficiency (35 – 45% less energy consumption well to wheel), it will be possible to keep individual mobility affordable in the future.
Fuel Cell Vehicle Simulation – Part 3: Modeling of Individual Components and Integration into the Overall Vehicle Model
Authors: Hauer K.H. , Moore R.M.
Published: December 2003

This is the third paper of a three part series on fuel cell vehicle (FCV) simulation. In Part 1 of this series, the existing publicly available models for FCV analysis and simulation were evaluated and the strengths and weaknesses of these models were identified. In Part 2, a new FCV simulation framework (and the methodology behind it) was introduced which focused on overcoming the weaknesses of the benchmarked models. In this third paper, the model framework developed in Part 2 is filled with component models. Specifically, models for the electric drive train, the transmission, a battery system, a dc‐dc‐converter and a fuel cell system with the associated control units are developed and described. An indirect‐methanol fuel cell system, with all of its subsystems, is illustrated in this paper, as an example of the process and implementation of a fuel cell system model. This example fuel cell system is characterised in both steady‐state and dynamic terms by numerical simulation, and is also used to illustrate the system integration required for a complete FCV simulation model.
Development of an Auxiliary Power Unit with Solid Oxide Fuel Cells for Automotive Applications
Authors: Lamp P. , Tachtler J. , Finkenwirth O. , Mukerjee S. , Shaffer S.
Published: December 2003

Delphi Corporation and the BMW Group are developing Solid Oxide Fuel Cell (SOFC) technology for application in the automotive industry as an on‐board Auxiliary Power Unit (APU). Delphi is part of the US‐DOE SECA initiative and is working with Battelle to develop SOFC for multiple applications including the automotive market. BMW is a leading customer in the development and is a key player in the introduction of new technologies to the market.

The APU provides significant customer benefits with regard to the availability of electrical functions, in particular engine‐independent functions such as auxiliary air conditioning. In addition, it has the potential to save fuel due to the high efficiency of producing electricity.

The focus of this development is to apply the APU to the present car generation, i.e. using gasoline as fuel. This makes SOFC the most suitable fuel cell technology for this application, being able to utilize the high CO containing reformate expected from higher hydrocarbons without further gas purification steps. However, key challenges exist in using the SOFC technology to meet the particular needs for this automotive application. These challenges include rapid start‐up, large number of thermal cycles, compact system, low cost and others. In this paper, the status of the Delphi/BMW APU and recent progress in the SOFC development will be reviewed.
Cooling Modules for Vehicles with a Fuel Cell Drive
Authors: Rogg S. , Höglinger M. , Zwittig E. , Pfender C. , Kaiser W. , Heckenberger T.
Published: December 2003

In spite of the high efficiency of fuel cell drives for vehicles, cooling is a key problem. The present article reveals the reasons for cooling limits and their physical causes. This leads to deductions about what kind of actions can be taken to increase cooling performance. The implementation of these measures is demonstrated by means of examples of cooling modules for vehicles with a fuel cell drive.
Hydrogen Supplied ICEs and Fuel Cells for Commercial Vehicles
Authors: Hipp E. , Kerschl S. , Pflanz T. , Gruber C.
Published: December 2003

In view of the limited availability of fossil fuels and the necessity to reduce the output of emissions of greenhouse gases in the long term, the transport sector needs efficient, environmentally compatible drive solutions. Hydrogen, as a clean and sustainable fuel, offers a high implementation potential and can be used both in internal combustion engines and in fuel cells. In urban deployment the fuel cell drive has specific advantages and is suitable for use in city buses. Integration of high‐power energy storage systems improves fuel consumption and can reduce the costs of the drive system. In May 2000 MAN presented its first fuel cell bus, which was successfully deployed in passenger transport in various cities. The next FC‐bus, using hybrid fuel cell propulsion, is planned under the framework of the Bavarian hydrogen project at Munich Airport and will be tested from spring 2004 on. The first deployment of pre‐series bus fleets with fuel cells using hydrogen as fuel can be expected from the end of this decade onwards.
Simulation Code for Gasoline Driven Fuel Cell Cars
Authors: Braun B. , Fischer K. , Rzepka M. , Stimming U. , Biermann J.W. , Johannaber M. , Wallentowitz H.
Published: December 2003

A simulation model of a car driven by a gasoline based fuel cell system was generated with Matlab/SIMULINK. The model of the vehicle represents a common compact class passenger car equipped with an electric power train, fuel cell system and with and without an additional battery. For the fuel cell system two variants have been implemented, a PEMFC and a high temperature SOFC system. Both models consist of an on‐board gasoline reformer, stack and auxiliary components such as evaporator, catalytic burner, fuel pump, fans and control unit with additional FC‐type specific components such as air preheater or CO‐shifter. The simulation model allows the comparison of the two FC systems in different automotive traction concepts (fuel cell vehicle, hybrid car) varying all important parameters such as driving cycle or fuel cell nominal power. In this paper the simulation model is described and first simulation results are given.
APOE is associated with age‐of‐onset, but not cognitive functioning, in late‐life depression
Authors: Butters Meryl A. , Sweet Robert A. , Mulsant Benoit H. , Ilyas Kamboh M. , Pollock Bruce G. , Begley Amy E. , Reynolds, Charles F. , DeKosky Steven T.
Published: December 2003

Objective

There is a recognized but poorly understood relationship between late‐life depression (LLD) and progressive dementia. Both cognitive impairment co‐occurring with LLD and a late age‐of‐onset of first lifetime depressive episode appear to be associated with subsequent progressive dementia. A history of major depression, especially when the first onset occurs in late‐life, has been identified as a risk factor for Alzheimer's disease (AD). The major genetic risk factor for sporadic AD is carrying one or more apolipoprotein E4 (APOE4) alleles. We hypothesized that the association between LLD and dementia risk would be mediated by APOE4, specifically that APOE4 allele frequency would be associated with cognitive impairment and later age‐of‐depression‐onset. We also predicted that APOE4 allele frequency would be increased among subjects with LLD.

Methods

We compared the distribution of APOE2, APOE3, and APOE4 alleles in groups of LLD (n=160), AD (n=568) and elderly control (EC; n=156) subjects.

Results

The allele distribution of the cognitively impaired LLD subgroup was not different from either the cognitively normal subgroup or the EC group but was different from the AD group. However, mean age‐of‐onset of depression in APOE4 carriers (51.4±20.7) was significantly lower than non‐carriers (58.8±16.8). The allele distribution in LLD overall was significantly different from the AD but not the EC group.

Conclusions

The finding that neither LLD, accompanying cognitive impairment, nor late age‐of‐onset was associated with an increased APOE4 allele frequency suggests that LLD acts as a risk factor for developing AD as well as non‐AD dementia through mechanisms independent of APOE4. The unexpected finding that age‐of‐onset of LLD was significantly reduced in APOE4 carriers is similar to the association between APOE4 and age‐of‐onset in AD. Replication of the association of APOE4 with earlier age‐of‐depression‐onset is indicated. Copyright © 2003 John Wiley & Sons, Ltd.
Gender in elderly suicide: analysis of coroners inquests of 200 cases of elderly suicide in Cheshire 1989–2001
Authors: Salib Emad , Green Laura
Published: December 2003

Objectives

The aim of this study is to review gender differences in elderly suicide in relation to specific social aspects of the suicidal process and health care contact before death. Such information may have practical value in identifying and targeting vulnerable elderly in whom suicide may be potentially preventable.

Methods

Data were extracted from the records of coroner's inquests into all reported suicide of persons aged 60 and over, in Cheshire over a period of 13 years 1989–2001. The Coroner's office covers the whole county of Cheshire (population 1 000 000).

Results

Men were less likely to have been known to psychiatric services (Odds Ratio [OR] 0.4 95% 0.2–0.6) and with less frequently reported history of previous attempted suicide compared to women (OR 0.5 95% Confidence Intervals [CI] 0.2–1). All deceased from ethnic minorities were men, none of whom had been known to psychiatric services. There was no significant difference between women and men in relation to, physical or psychiatric morbidity, GP contact prior to suicide, intimation of intent or living alone. Of suicide victims not known to services a surprisingly high proportion of 38% and 16% were found to have psychiatric morbidity in men and women respectively.

Conclusion

Suicide is an important problem in the elderly with gender playing an important part in their social behaviour but a high proportion of the deceased were not known to local services. Primary Care professionals have an important role to play in reducing elderly suicide as most contact with the health service in elderly suicide seem to be with GPs. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of reminiscence and life review on late‐life depression: a meta‐analysis
Authors: Bohlmeijer Ernst , Smit Filip , Cuijpers Pim
Published: December 2003

Aim

To assess the effectiveness of reminiscence and life review on late‐life depression across different target groups and treatment modalities.

Method

Twenty controlled outcome studies were retrieved from Psychlit, Medline and Dissertation Abstracts. For each study a standardised effect size, d, was calculated and a random‐effects meta‐analysis was conducted.

Results

An overall effect size of 0.84 (95% Confidence Intervals (CI)=0.31–1.37) was found, indicating a statistically and clinically significant effect of reminiscence and life review on depressive symptomatology in elderly people. This effect is comparable to the effects commonly found for pharmacotherapy and psychological treatments. The effect was larger in subjects with elevated depressive symptomatology (d=1.23) as compared to other subjects (d=0.37). Other characteristics of the subjects or interventions were not found to be related to increased or decreased effect sizes.

Discussion

Reminiscence and life review are potentially effective treatments for depressive symptoms in the elderly and may thus offer a valuable alternative to psychotherapy or pharmacotherapy. Especially in non‐institutionalised elderly people—who often have untreated depression—it may prove to be an effective, safe and acceptable form of treatment. Randomized trials with sufficient statistical power are necessary to confirm the results of this study. Copyright © 2003 John Wiley & Sons, Ltd.
Nursing home suicides—a psychological autopsy study
Authors: Suominen Kirsi , Henriksson Markus , Isometsä Erkki , Conwell Yeates , Heilä Hannele , Lönnqvist Jouko
Published: December 2003

Objective

Older adults comprise a fifth of all suicides. Elders are the fastest growing part of the population, thus the number of persons needing nursing home care will increase dramatically in the near future. Little information has been available about suicides in nursing homes. The present study described all suicides among older adults in nursing homes in Finland during a 12‐month period emphasizing the factors that have been found to be associated with suicide in the general elderly population.

Methods

Drawing on data from a psychological autopsy study of all suicides (n=1397) in Finland during one year, all suicides committed by patients in nursing homes were identified. Retrospective DSM‐IV consensus diagnoses were assigned.

Results

Twelve elderly (aged 60 years or more) nursing home residents who died by suicide, 0.9% of all suicides, were identified. The primary finding of the present study was that nursing home residents who died by suicide had suffered from highly comorbid somatopsychiatric disorders. One or more diagnoses on Axis I were made for all who died by suicide in nursing home. Depressive syndrome was diagnosed in three‐quarters of subjects. Only a third of these were identified to have suffered from depressive symptoms before their death.

Conclusions

Early recognition and adequate treatment of both somatic diseases and mental disorders, particularly depression, as well as early recognition of suicide risk among nursing home residents, are needed in order to prevent suicide. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling late‐life depression
Authors: Parker Gordon , Snowdon John , Parker Kay
Published: December 2003

Objective

To determine if we could find support for a three‐class depression sub‐typing model (and identify differentiating constituent clinical features) in a sample of elderly depressed patients.

Background

Depression is currently modelled dimensionally, with little concession to descriptive psychopathology and distinction of meaningful clinical depressive sub‐types. We have proposed a three‐class hierarchical specificity model for sub‐typing the depressive disorders (comprising psychotic, melancholic and non‐melancholic depression), with specificity referring to two clinical features (psychotic symptoms and psychomotor disturbance or PMD) separating the first two classes from a residual non‐melancholic class.

Method

Subjects were aged 65 years or more, non‐demented and being treated for depression. Extensive clinical assessment was undertaken, while several standardised measures were administered. ‘Bottom up’ analyses were data driven, while ‘top down’ analyses respected DSM‐III‐R decision rules. Dimensional and categorical multivariate analyses sought to identify features differentiating psychotic depression (PD), melancholic depression (MEL) and a residual non‐melancholic (NON‐MEL) class.

Results

Of the 123 referred patients (having a mean age of 75.6 years), 46 had DSM‐defined PD, 46 had MEL and 31 were assigned as NON‐MEL. Mean total CORE scores (measuring PMD) more clearly distinguished the groups than scores on two depression severity measures. Psychotic depression was best distinguished from melancholic depression by psychotic features, as well as more severe PMD and anhedonia. Melancholic depression was best distinguished from non‐melancholic depression by PMD, terminal insomnia and pathological guilt.

Conclusion

The specificity of PMD to the definition of the psychotic and melancholic depression was confirmed in our elderly depressed sample. Clinical features identified as distinguishing psychotic, melancholic and non‐melancholic depression were broadly consistent with findings from our previous studies involving younger subjects and with our three‐class hierarchical model. Copyright © 2003 John Wiley & Sons, Ltd.
Alzheimer’s disease: usefulness of the Family Strain Questionnaire and the Screen for Caregiver Burden in the study of caregiving‐related problems
Authors: Ferrario Silvia Rossi , Vitaliano Peter , Zotti Anna Maria , Galante Emanuela , Fornara Roberta
Published: December 2003

Objectives

The economic and psychosocial impacts of Alzheimer's disease (AD) on caregivers are so well documented that they have stimulated socioeconomic regulations that are international in scope. In Italy caregivers have the right to receive economic and psychosocial aid. However, to distribute such aid the needs of caregivers, must be properly assessed. Here we have attempted to integrate two measures, the Family Strain Questionnaire (FSQ) and the Screen for Caregiver Burden (SCB), in order to evaluate caregiver needs that are both general and specific to AD.

Material and Methods

The SCB and FSQ were administered to 91 primary caregivers of home‐based patients with AD. Caregivers also were asked to rate the activities of daily living of their care recipients, the latter of which were administered the Mini‐Mental State Examination.

Results

The SCB and FSQ provide different, but complementary assessments of the needs of AD caregivers. The SCB identifies situations that are potentially stressful to AD caregivers and the FSQ identifies the needs of specific caregivers (e.g. men vs women, spouses vs children, unemployed vs employed).

Conclusion

Together these measures may help government agencies to assess caregiver needs beyond those assessed by each individual measure. Copyright © 2003 John Wiley & Sons, Ltd.
A systematic review of cognitive decline in the general elderly population
Authors: Park Helen L. , O'Connell Janice E. , Thomson Richard G.
Published: December 2003

Background

The public health impact of cognitive decline and dementia is increasing as the population ages. Studies exploring therapies or risk factors for cognitive impairment require understanding of expected age‐related decline.

Objective

To establish the rate of age‐related cognitive decline in the general elderly population.

Design

Systematic review of studies of cognitive decline in the general elderly population. Medline, Embase and PsycINFO databases were searched using an adapted version of McMaster's aetiology, causation and harm strategies and the Cochrane Dementia and Cognitive Impairment Group strategy. Grey literature was explored and experts contacted. A second observer was involved at all stages and quality appraisal of included studies was performed. Included studies were representative, community‐based, cohort studies of people aged over 60, incorporating individuals with dementia.

Results

Identification of 5990 abstracts and retrieval of 163 full texts led to inclusion of 19 papers. Heterogeneity made narrative review the appropriate method of data synthesis. Some degree of cognitive impairment with increasing age was found in all studies, although the extent varied. The prevalence of cognitive impairment and the rate of decline increased with age. Studies were of variable quality.

Conclusions

Cognitive decline is almost universal in the general elderly population and increases with age. Improved communication between researchers and between clinicians to identify a core minimum data set of neuropsychological tests that could be used in different populations would support consistent study design and meta‐analysis, helping to quantify the true rate of cognitive decline in the elderly and assisting diagnosis in clinical practice. Copyright © 2003 John Wiley & Sons, Ltd.
The association of psychosocial factors and depression with hypertension among older adults
Authors: Bosworth Hayden B. , Bartash Rachel M. , Olsen Maren K. , Steffens David C.
Published: December 2003

Objective

To examine the relationship between depression and hypertension in an elderly population and how psychosocial variables influence this relationship.

Methods

The study included 293 subjects, who met DSM‐IV criteria for unipolar depression, and 151 subjects with no psychiatric disorder. All subjects were over the age of 58. Participants were administered the Duke Depression Evaluation Schedule at baseline and at yearly intervals for 3 years.

Results

Cross‐sectional analyses of baseline data showed that hypertensive patients were more likely to be depressed and of non‐white race. Bivariate analyses provided evidence that hypertension was associated with higher amounts of total stressors and lower social support. No differences in the prevalence of hypertension were found between men and women. In addition, there was no evidence of change in hypertension status over time.

Conclusion

Patients, especially minorities, who experience depression, stress, or a lack of social support, are at an increased likelihood of having hypertension and clinicians should consider this risk when treating this population. Copyright © 2003 John Wiley & Sons, Ltd.
An infinite class of fibres in CURDs with block sizes two and three
Authors: Keranen Melissa S. , Rees Rolf S. , Ling Alan C.H.
Published: December 2003

Class‐uniformly resolvable designs (CURDs) are introduced by Lamken et al. Discrete Math 92 (1991) 197–209. In Wevrick and Vanstone, J Combin Designs 4 (1996) 177–202, a classification scheme is developed based on the ratio a:b of pairs to triples. Asymptotic existence results are obtained when (a,b) = (1,2n), n ≥ 1 and when (a,b) = (9,2). The authors also obtain partial results on the existence of CURDs when (a,b) = (1,2n), 1 ≤ n ≤ 5, (a,b) = (3, 6u − 2), u ≥ 1 and when (a,b) ∈ {(1,1), (3,1), (7,2), (3,4), (9,2)}. In Danziger and Stevens, J Combin Designs 9 (2001), 79–99, the necessary and sufficient conditions for CURDs when (a,b) = (3,1) are completely settled. In this article, we obtain a necessary and sufficient condition when (a,b) = (3m, 1) for all m > 1. © 2003 Wiley Periodicals, Inc.
Super‐simple resolvable balanced incomplete block designs with block size 4 and index 3
Authors: Ge Gennian , Lam C. W. H.
Published: December 2003

The necessary conditions for the existence of a super‐simple resolvable balanced incomplete block design on v points with k = 4 and λ = 3, are that v ≥ 8 and v ≡ 0 mod 4. These conditions are shown to be sufficient except for v = 12. © 2003 Wiley Periodicals, Inc.
Atomic Latin squares of order eleven
Authors: Maenhaut Barbara M. , Wanless Ian M.
Published: December 2003

A Latin square is pan‐Hamiltonian if the permutation which defines row i relative to row j consists of a single cycle for every i ≠ j. A Latin square is atomic if all of its conjugates are pan‐Hamiltonian. We give a complete enumeration of atomic squares for order 11, the smallest order for which there are examples distinct from the cyclic group. We find that there are seven main classes, including the three that were previously known. A perfect 1‐factorization of a graph is a decomposition of that graph into matchings such that the union of any two matchings is a Hamiltonian cycle. Each pan‐Hamiltonian Latin square of order n describes a perfect 1‐factorization of Kn,n, and vice versa. Perfect 1‐factorizations of Kn,n can be constructed from a perfect 1‐factorization of Kn+1. Six of the seven main classes of atomic squares of order 11 can be obtained in this way. For each atomic square of order 11, we find the largest set of Mutually Orthogonal Latin Squares (MOLS) involving that square. We discuss algorithms for counting orthogonal mates, and discover the number of orthogonal mates possessed by the cyclic squares of orders up to 11 and by Parker's famous turn‐square. We find that the number of atomic orthogonal mates possessed by a Latin square is not a main class invariant. We also define a new sort of Latin square, called a pairing square, which is mapped to its transpose by an involution acting on the symbols. We show that pairing squares are often orthogonal mates for symmetric Latin squares. Finally, we discover connections between our atomic squares and Franklin's diagonally cyclic self‐orthogonal squares, and we correct a theorem of Longyear which uses tactical representations to identify self‐orthogonal Latin squares in the same main class as a given Latin square. © 2003 Wiley Periodicals, Inc.
Unitals in the code of the Hughes plane
Authors: Baker R. D. , Wantz K. L.
Published: December 2003

A coding‐theoretic characterization of a unital in the Hughes plane is provided, based on and extending the work of Blokhuis, Brouwer, and Wilbrink in PG(2,q2). It is shown that a Frobenius‐invariant unital is contained in the p‐code of the Hughes plane if and only if that unital is projectively equivalent to the Rosati unital. © 2003 Wiley Periodicals, Inc.
Symmetric Hamilton cycle decompositions of the complete graph
Authors: Akiyama Jin , Kobayashi Midori , Nakamura Gisaku
Published: December 2003

We construct a new symmetric Hamilton cycle decomposition of the complete graph Kn for odd n > 7. © 2003 Wiley Periodicals, Inc.
On perfect deletion‐correcting codes
Authors: Klein Andreas
Published: December 2003

In this article, we present constructions for perfect deletion‐correcting codes. The first construction uses perfect deletion‐correcting codes without repetition of letters to construct other perfect deletion‐correcting codes. This is a generalization of the construction shown in 1. In the third section, we investigate several constructions of perfect deletion‐correcting codes using designs. In the last section, we investigate perfect deletion‐correcting codes containing few codewords. © 2003 Wiley Periodicals, Inc.
Distance measurement by circular scanning of the excitation beam in the two‐photon microscope
Authors: Kis‐Petikova Katarina , Gratton Enrico
Published: December 2003

We developed a method to measure relative distances with nanometer accuracy of fluorescent particles of different color in a two‐photon scanning fluorescence microscope, with two‐channel photon counting detection. The method can be used in the 10–500 nm range, for distances below the resolution limit of standard far field microscopy. The proposed technique is more efficient than the methods using raster scanning. To achieve maximum sensitivity in the radial direction, the excitation beam is moved periodically in a circular orbit with a radius of the size of the point spread function. The phase and the modulation of the periodic fluorescence signal, calculated by fast Fourier transform, gives the phase and the radial distance of the particle from the center of scanning. The coordinates of particles are recovered simultaneously in the two channels and the relative distance is calculated in real time. Particles can be tracked by moving the center of scanning to the recovered position, while measuring the distance from the second particle. Intensity data are saved and fitted later by a model accounting for light leakage between the channels. The total number of detected photons limited the accuracy of the position and distance measurement. Experiments demonstrating the advantages of the method were performed on fluorescent spheres and single dye molecules immobilized on quartz surface. Microsc. Res. Tech. 63:34–49, 2004. © 2003 Wiley‐Liss, Inc.
Antecedents of two‐photon excitation laser scanning microscopy
Authors: Masters Barry R. , So Peter T.C.
Published: December 2003

In 1931, Maria Göppert‐Mayer published her doctoral dissertation on the theory of two‐photon quantum transitions (two‐photon absorption and emission) in atoms. This report describes and analyzes the theoretical and experimental work on nonlinear optics, in particular two‐photon excitation processes, that occurred between 1931 and the experimental implementation of two‐photon excitation microscopy by the group of Webb in 1990. In addition to Maria Göppert‐Mayer's theoretical work, the invention of the laser has a key role in the development of two‐photon microscopy. Nonlinear effects were previously observed in different frequency domains (low‐frequency electric and magnetic fields and magnetization), but the high electric field strength afforded by lasers was necessary to demonstrate many nonlinear effects in the optical frequency range. In 1978, the first high‐resolution nonlinear microscope with depth resolution was described by the Oxford group. Sheppard and Kompfner published a study in Applied Optics describing microscopic imaging based on second‐harmonic generation. In their report, they further proposed that other nonlinear optical effects, such as two‐photon fluorescence, could also be applied. However, the developments in the field of nonlinear optical stalled due to a lack of a suitable laser source. This obstacle was removed with the advent of femtosecond lasers in the 1980s. In 1990, the seminal study of Denk, Strickler, and Webb on two‐photon laser scanning fluorescence microscopy was published in Science. Their paper clearly demonstrated the capability of two‐photon excitation microscopy for biology, and it served to convince a wide audience of scientists of the potential capability of the technique. Microsc. Res. Tech. 63:3–11, 2004. © 2003 Wiley‐Liss, Inc.
Novel diode‐pumped infrared tunable laser system for multi‐photon microscopy
Authors: Deguil Nelly , Mottay Eric , Salin Francois , Legros Philippe , Choquet Daniel
Published: December 2003

We report on a novel laser source, emitting high energy (20 nanoJoule) femtosecond pulses, in a broad spectrum (250 nm). This source is easily tuned from 950 to 1200 nm, without any laser adjustment, and delivers sub‐300 femtosecond pulses with a 10‐nm spectral width. Microsc. Res. Tech. 63:23–26, 2004. © 2003 Wiley‐Liss, Inc.
Ultracompact autocorrelator for multiphoton microscopy
Authors: Quercioli F. , Ghirelli A. , Tiribilli B. , Vassalli M.
Published: December 2003

Pulse temporal characterization is a fundamental task when operating a Ti:Sapphire ultrafast laser system for multiphoton microscopy applications. In the present report, an ultracompact autocorrelator setup and a simple procedure is reported to perform pulse width measurements at the focal plane of the microscope objective without the need of any further instrumentation, aside from a few optical elements, since the confocal microscope, detection, data acquisition, processing, and displaying capabilities are used. Microsc. Res. Tech. 63:27–33, 2004. © 2003 Wiley‐Liss, Inc.
Fluorescence lifetime imaging by time‐correlated single‐photon counting
Authors: Becker W. , Bergmann A. , Hink M.A. , König K. , Benndorf K. , Biskup C.
Published: December 2003

We present a time‐correlated single photon counting (TCPSC) technique that allows time‐resolved multi‐wavelength imaging in conjunction with a laser scanning microscope and a pulsed excitation source. The technique is based on a four‐dimensional histogramming process that records the photon density over the time of the fluorescence decay, the x‐y coordinates of the scanning area, and the wavelength. The histogramming process avoids any time gating or wavelength scanning and, therefore, yields a near‐perfect counting efficiency. The time resolution is limited only by the transit time spread of the detector. The technique can be used with almost any confocal or two‐photon laser scanning microscope and works at any scanning rate. We demonstrate the application to samples stained with several dyes and to CFP‐YFP FRET. Microsc. Res. Tech. 63:58–66, 2004. © 2003 Wiley‐Liss, Inc.
Probing microscopic diffusion by 2‐photon flash photolysis: Measurement of isotropic and anisotropic diffusion in lens fiber cells
Authors: Cannell M.B. , Jacobs M.D. , Donaldson P.J. , Soeller C.
Published: December 2003

Two‐photon excited flash photolysis (TPEFP) was used to photorelease caged fluorescein in test solutions and inside fiber cells of the eye lens. Accurate alignment between the focus of the IR beam and the probe beam from the confocal microscope was achieved with an accessory focussing lens and computer models of diffusion were fit to experimental data to extract apparent diffusion coefficients. Inside a fiber cell, the diffusion coefficient for fluorescein was 4 × 10−7 cm2/s at 21°C, a value an order of magnitude lower than observed in free solution. Fluorescence also diffused between fiber cells via gap junctions. In the periphery, diffusion between cells occurred mainly in a radial direction while deep in the lens the diffusion between cells appeared more isotropic. Diffusion between cells was slower than inside cells and corresponded to less than ∼1% of the area between cells being available for diffusion. This value is in good agreement with that expected from measurements of gap junction structure and packing density if a 1–1.5‐nm aqueous gap junction pore is nearly always open. Microsc. Res. Tech. 63:50–57, 2004. © 2003 Wiley‐Liss, Inc.
Practical limits of resolution in confocal and non‐linear microscopy
Authors: Cox Guy , Sheppard Colin J.R.
Published: December 2003

Calculated and measured resolution figures are presented for confocal microscopes with different pinhole sizes and for nonlinear (2‐photon and second harmonic) microscopes. A modest degree of super‐resolution is predicted for a confocal microscope but in practice this is not achievable and confocal fluorescence gives little resolution improvement over widefield. However, practical non‐linear microscopes do approach their theoretical resolution and therefore show no resolution disadvantage relative to confocal microscopes in spite of the longer excitation wavelength. Microsc. Res. Tech. 63:18–22, 2004. © 2003 Wiley‐Liss, Inc.
Notes on theory and experimental conditions behind two‐photon excitation microscopy
Authors: Esposito Alessandro , Federici Federico , Usai Cesare , Cannone Fabio , Chirico Giuseppe , Collini Maddalena , Diaspro Alberto
Published: December 2003

This report deals with the fundamental quantum physics behind two‐photon excitation also providing a link to the experimental consequences exploited in microscopy. The optical sectioning effect is demonstrated as well as the distribution of excitation and of fluorescence emission. Microsc. Res. Tech. 63:12–17, 2004. © 2003 Wiley‐Liss, Inc.
Live cell ultraviolet microscopy: A comparison between two‐ and three‐photon excitation
Authors: Balaji J. , Desai R. , Maiti S.
Published: December 2003

We compare conventional infrared laser based three‐photon excitation with a visible laser based two‐photon excitation scheme for imaging the ultraviolet fluorophore serotonin in solution and in live cells. To obtain a signal level of 1,000 photons per second per mM serotonin solution, we need a back aperture power of 5 mW at 550 nm (for two‐photon excitation) and 33 mW at 740 nm (for three‐photon excitation). The detectivity of serotonin (defined as the concentration of serotonin that yields a signal equivalent to three times the standard deviation of the signal obtained from the buffer alone) is 12 μM for two‐photon, and 220 μM for three‐photon excitation. Surprisingly, for live cell imaging of vesicular serotonin in serotonergic cells, three‐photon excitation appears to provide better image contrast than two‐photon excitation. The origin of this is traced to the concentration‐dependent shift of the serotonin emission spectrum. Microsc. Res. Tech. 63:67–71, 2004. © 2003 Wiley‐Liss, Inc.
Manganese availability and microbial populations in the rhizosphere of wheat genotypes differing in tolerance to Mn deficiency
Authors: Marschner Petra , Fu Qinglin , Rengel Zed
Published: December 2003

Plant genotypes differ in their capacity to grow in soils with low manganese (Mn) availability. The physiological mechanisms underlying differential tolerance to Mn deficiency are poorly understood. To study the relationship between Mn content in soil, plant genotypes, and rhizosphere microorganisms in differential Mn efficiency, two wheat (Triticum aestivum L.) cultivars, RAC891 (tolerant to Mn deficiency) and Yanac (sensitive), were grown in a Mn‐deficient soil to which 5, 10, 20 or 40 mg Mn kg–1 were added. The shoot dry matter of both cultivars increased with increasing Mn addition to the soil. At all soil Mn fertilizer levels, the tolerant RAC891 had a greater shoot dry matter and a higher total shoot Mn uptake than the sensitive Yanac. The concentration of DTPA‐extractable Mn in the rhizosphere soil of RAC891 at Mn20 and Mn40 was slightly lower than in the rhizosphere of Yanac. The population density of culturable microorganisms in the rhizosphere soil was low (log 6.8–6.9 cfu (g soil)–1) in both cultivars and neither Mn oxidation nor reduction were observed in vitro. To assess the non‐culturable fraction of the soil microbial community, the ribosomal intergenetic spacer region of the bacterial DNA in the rhizosphere soil was amplified (RISA) and separated in agarose gels. The RISA banding patterns of the bacterial rhizosphere communities changed markedly with increasing soil Mn level, but there were no differences between the wheat cultivars. The bacterial community structure in the rhizosphere was significantly correlated with the concentration of DPTA‐extractable Mn in the rhizosphere, fertilizer Mn level, shoot dry matter, and total shoot Mn uptake. The results obtained by RISA indicate that differential tolerance to Mn deficiency in wheat may not be related to changes in the composition of the bacterial community in the rhizosphere.
Effect of nitrogen supply on leaf traits related to photosynthesis during grain filling in two maize genotypes with different N efficiency
Authors: Paponov Iwan A. , Engels Christof
Published: December 2003

In the present study, plant traits related to the photosynthetic capacity at the whole plant level were compared during grain filling in two maize genotypes with different nitrogen (N) efficiency. The plants were grown in a greenhouse in large root containers and supplied either with suboptimal or optimal rates of N fertilizer. Suboptimal N supply reduced total plant biomass at maturity (47 days (d) after flowering) by 29 % for the efficient genotype and by 36 % for the inefficient genotype. Suboptimal N supply reduced leaf growth of both genotypes. The reduction of leaf area was less severe in the N‐efficient genotype, despite of lower N content in the leaves. This indicates lower sensitivity of leaf growth towards internal N limitation in the efficient genotype. At low N supply, the green leaf area per plant gradually decreased after flowering in both genotypes, because of loss of chlorophyll during leaf senescence. The rate of net photosynthesis per unit leaf area (A) was reduced at low in comparison with high N supply. The ratio of A/leaf N content or leaf chlorophyll content was higher in the efficient genotype, indicating more efficient utilization of internal N for photosynthesis. At the end of grain filling, low N supply led to enhanced intercelluar CO2 concentrations (Ci) in the leaves, indicating limitation of CO2 assimilation by carboxylation rather than by stomatal resistance. The N deficiency‐induced increase of Ci was less pronounced in the efficient genotype. Furthermore, higher photosynthetic rate of the efficient genotype at suboptimal N supply was associated with lower contents of reducing sugars and sucrose in the leaves, whereas starch content was higher than in the inefficient genotype. The ability to avoid excessive sugar accumulation in the leaves under N deficiency might be related to higher photosynthetic N efficiency.
Relative Agronomic Effectiveness of phosphate rocks and P adsorption characteristics of an Oxic Rhodustalf in Eastern India
Authors: Ghosal Prabir K. , Chakraborty Trishit , Bhattacharya Buddhadeb , Bagchi Dipak K.
Published: December 2003

The Relative Agronomic Effectiveness (RAE) of rock phosphates as compared to water soluble Triple Super Phosphate was measured on direct, residual, and cumulative application of the P fertilizers in a field experiment with rice on an Oxic‐Rhodustalf in the eastern plateau region of India. The fertilizers were Morocco Rock Phosphate (MORP), Mussoorie Rock Phosphate (MRP), Partially Acidulated Rock Phosphate (PARP), and Triple Super Phosphate (TSP). The RAE of the rock phosphates were lower for direct application (54–80 %) and cumulative application (70–93 %) of P but roughly equal or larger for the residual effect (92–142 %) as compared to TSP. The P adsorption characteristic of the experimental soil conformed to the linear relationship of both Freundlich and Langmuir isotherm equation. The adsorption data when plotted according to Langmuir equation deviated from a single linear relationship at higher concentration (10 μg ml–1), thereby giving two adsorption maximum values ( 68.49 μg g–1 and 256.41 μg g–1) and binding energies ( 2.86 ml μg–1 and 0.089 ml μg–1) for the soil. Two populations of P adsorption site with widely different affinity for P probably existed in the soil.
Effects of parent material and land use on soil erodibility
Authors: Özdemir Nutullah , Aşkin Tayfun
Published: December 2003

The objective of the present investigation was to find out the effect of different parent materials and land use on soil erodibility. Four types of parent materials such as andesite, basalt, alluvial, and gypsum, and three land use types such as grass, clover, and maize, all wide spread in Erzurum Province in Turkey, were tested. Aggregate stability and soil erodibility factors were determined. The susceptibility of soils against erosion decreased in the order of parent materials basalt > andesite > alluvial > gypsum. Likewise, the susceptibility of land use can be sorted as follows: grass > clover > maize.
Field efficiency of biofertilizers on the growth of okra (Abelmoschus esculentus [(L.) Moench])
Authors: Nuruzzaman M. , Ashrafuzzaman M. , Zahurul Islam M. , Rafiqul Islam M.
Published: December 2003

An experiment was carried out at the Farm of the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh from March to July, 2001 to investigate the effect of biofertilizers on morpho‐physiological characters of okra. The experiment was laid out in a randomized complete block design with four replications. There were nine treatments such as T0 (control), T1 (Azotobacter biofertilizer), T2 (Azospirillum. biofertilizer), T3 (Azotobacter + Azospirillum. biofertilizers), T4 (Azotobacter + Cowdung 5 t ha–1), T5 (Azospirillum + 5 t ha–1 cowdung), T6 (Azotobacter + Azospirillum + 5 t ha–1 cowdung), T7 (5 t ha–1 cowdung), and T8 (60 % N). The experimental results revealed significant variations among the treatments in respect of morphological characters, e.g. plant height, number of leaves per plant, stem base diameter, tap root length, and physiological characters like root dry weight, leaf area index, and crop growth rate. Number of leaves per plant, stem base diameter, root length, root dry weight, leaf area index, and crop growth rate were larger in T4, T5, T6, and T8 than the others. In all the parameters, T8 gave the similar result with biofertilizers in combination with cowdung treatments, and T7 was identical with T0 (control). These experimental results revealed that morpho‐physiological characters of okra could be modified by the application of biofertilizer + cowdung. However, biofertilizers + cowdung treatments were comparable to T8 (60 % N) in this study. This suggests that T4 or T6 or T5 were more benificial in environmentally friendly okra cultivation and may be used as an alternative of inorganic N by saving cost of production and sustaining productivity.