bluuebunny/crossref_metadata_2025 huggingface dataset:
RNA transport and localized protein synthesis in neurological disorders and neural repair
Authors: Wang Wenlan , van Niekerk Erna , Willis Dianna E. , Twiss Jeffery L.
Published: May 2007

Neural cells are able to finely tune gene expression through post‐transcriptional mechanisms. Localization of mRNAs to subcellular regions has been detected in neurons, oligodendrocytes, and astrocytes providing these domains with a locally renewable source of proteins. Protein synthesis in dendrites has most frequently been associated with synaptic plasticity, while axonally synthesized proteins appear to facilitate pathfinding and injury responses. For oligodendrocytes, mRNAs encoding several proteins for myelin formation are locally generated suggesting that this mechanism assists in myelination. Astrocytic processes have not been well studied but localization of GFAP mRNA has been demonstrated. Both RNA transport and localized translation are regulated processes. RNA transport appears to be highly selective and, at least in part, the destiny of individual mRNAs is determined in the nucleus. RNA–protein and protein–protein interactions determine which mRNAs are targeted to subcellular regions. Several RNA binding proteins that drive mRNA localization have also been shown to repress translation during transport. Activity of the translational machinery is also regulated in distal neural cell processes. Clinically, disruption of mRNA localization and/or localized mRNA translation may contribute to pathophysiology of fragile X mental retardation and spinal muscular atrophy. Axonal injury has been shown to activate localized protein synthesis, providing both a means to initiate regeneration and retrogradely signal injury to the cell body. Decreased capacity to transport mRNAs and translational machinery into distal processes could jeopardize the ability to respond to injury or local stimuli within axons and dendrites. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Navigating their way to the clinic: Emerging roles for axon guidance molecules in neurological disorders and injury
Authors: Yaron Avraham , Zheng Binhai
Published: May 2007

The mechanisms underlying formation of the basic network of the nervous system are of fundamental interest in developmental neurobiology. During the wiring of the nervous system, newborn neurons send axons that travel long distances to their targets. These axons are directed by environmental cues, known as guidance cues, to their correct destinations. Through extensive studies in vertebrates and invertebrates many of the guidance cues and their receptors have been identified. Recently, guidance molecules have been suggested to have important roles in pathological conditions of the nervous system. Mutations in guidance receptors have been associated with hereditary neurological disorders, and deregulation of guidance cues might be associated with predisposition to epilepsy. In addition, it was suggested that guidance molecules play roles in the ability of the adult nervous system to recover and repair after injury. Thus, molecules that were first discovered as “developmental cues” are now emerging as important factors in neurological disease and injury in the adult. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Effects of repeated doses of caffeine on performance and alertness: new data and secondary analyses
Authors: Hewlett Paul , Smith Andrew
Published: May 2007

Rationale

The effects of caffeine on mood and performance are well established. Some authors suggest that caffeine merely reverses effects of caffeine withdrawal rather than having direct behavioural effects. It has also been suggested that withdrawal may be removed by a first dose of caffeine and further doses have little subsequent effect. These issues are examined here.

Objectives

The present study aimed to determine whether caffeine withdrawal influenced mood and performance by comparing regular consumers who had been withdrawn from caffeine overnight with non‐consumers. Following this repeated caffeine doses were administered to test the claim that repeated dosing has no extra effect on mood or performance. Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption.

Methods

One hundred and twenty volunteers participated in the study. Regular caffeine consumption was assessed by questionnaire and this showed that 36 of the volunteers did not regularly consume caffeinated beverages. Volunteers were instructed to abstain from caffeine overnight and then completed a baseline session measuring mood and a range of cognitive functions at 08.00 the next day. Following this volunteers were given 0, or 1 mg/kg caffeine in a milkshake, glucose solution or water (at 09:00), followed by a second 0 or 1 mg/kg caffeine dose (at 09:40) and the test battery repeated at 10:00.

Results

The baseline data showed no effect of overnight caffeine withdrawal on mood or performance. In contrast, caffeine challenge improved vigilance performance and prevented decreases in alertness induced by completion of the task battery. The magnitude of these effects increased as a function of the number of doses of caffeine given. Secondary analyses of data from Christopheret al. (2003) also confirmed that effects of caffeine did not depend on length of withdrawal.

Conclusions

The present findings show no effect of overnight caffeine withdrawal on mood and performance. Caffeine challenge did have the predicted effect on alertness and vigilance, with the size of the effects increasing with caffeine dose. These findings suggest that the effects of caffeine are not due to reversal of effects of withdrawal, a view confirmed by secondary analyses of data collected after a day of normal caffeine consumption. Copyright © 2007 John Wiley & Sons, Ltd.
Discriminating residual and colluvial soils using topographic analysis in a small, forested catchment in Japan
Authors: Maeda Kenji , Tanaka Takafumi , Takeshi Ohta , Hattori Shigeaki
Published: May 2007

Soil moisture plays an important role in hydrology. Understanding factors (such as topography, vegetation, and meteorological conditions) that influence spatio‐temporal variability in soil moisture, and how this influence is manifested, is important for understanding hydrological processes. A number of distributed (quasi‐)physical hydrological models have been developed to investigate this subject. Previous studies have shown that the spatial differences in the distribution of soil types (residual and colluvial soils) dominantly reflect spatio‐temporal fluctuations in soil moisture and runoff.

We present a methodology for assessing the spatial distribution of residual and colluvial soils, which differ with respect to their physical characteristics, in a 0·88 km2 forested catchment with complex topography and a complex land‐use history. Our method is based on penetration resistance profile data; in this data set, each data point represents soil physical characteristics within an area of about 25 m2. If the spatial distribution of soils under similar meteorological, geological, historical land use, and other conditions could be characterized on the basis of similarity in topographic features, then the spatial distribution of soil could be predicted based on relationships between various topographic indices (e.g. topographic index and local slope). We tested whether our model correctly assessed the reference data. The model's results were 90·5% correct for residual soils and 87·3% correct for colluvial soils. Further studies will quantify the relationships between topographic features of land covered by residual and colluvial soils and changes in spatio‐temporal variations in the catchment (e.g. vegetation and land use) as a function of geology or meteorology. Copyright © 2007 John Wiley & Sons, Ltd.
Rule reduction in fuzzy logic for better interpretability in reservoir operation
Authors: Sivapragasam C. , Vasudevan G. , Vincent P. , Sugendran P. , Marimuthu M. , Seenivasakan S.
Published: May 2007

Decision‐making in reservoir operation has become easy and understandable with the use of fuzzy logic models, which represent the knowledge in terms of interpretable linguistic rules. However, the improvement in interpretability with increase in number of fuzzy sets (‘low’, ‘high’, etc) comes with the disadvantage of increase in number of rules that are difficult to comprehend by decision makers. In this study, a clustering‐based novel approach is suggested to provide the operators with a limited number of most meaningful operating rules. A single triangular fuzzy set is adopted for different variables in each cluster, which are fine‐tuned with genetic algorithm (GA) to meet the desired objective. The results are compared with the multi fuzzy set fuzzy logic model through a case study in the Pilavakkal reservoir system in Tamilnadu State, India. The results obtained are highly encouraging with a smaller set of rules representing the actual fuzzy logic system. Copyright © 2007 John Wiley & Sons, Ltd.
Functional inactivation of the KLF6 tumor suppressor gene by loss of heterozygosity and increased alternative splicing in glioblastoma
Authors: Camacho‐Vanegas Olga , Narla Goutham , Teixeira Miriam S. , DiFeo Analisa , Misra Anjan , Singh Gobind , Chan Andrew M. , Friedman Scott L. , Feuerstein Burt G. , Martignetti John A.
Published: May 2007

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor and possesses a high incidence of 10p loss. The KLF6 (Kruppel‐like transcription factor) tumor suppressor gene on 10p15 is inactivated by loss of heterozygosity (LOH) and/or somatic mutation in a number of human cancers and forced expression of KLF6 in GBM lines inhibits their growth and transformation. In addition, increased expression of its alternatively spliced, cytoplasmic isoform KLF6‐SV1 has now been shown to play a role in cancer pathogenesis. On the basis of these findings we examined the role of KLF6 and KLF6‐SV1 in the development and progression of GBM. LOH analysis of 17 primary GBM patient samples using KLF6‐specific microsatellite markers revealed that 88.2% (15/17) had LOH of the KLF6 locus. Interestingly, no KLF6 somatic mutations were identified. RNA analysis revealed concomitant decreases in all primary GBM tumors (n = 11) by ∼80% in KLF6 expression (p < 0.001) coupled with increased KLF6‐SV1 expression (p < 0.001) when compared to normal astrocytes. To determine the biological relevance of these findings, we examined the effect of KLF6 expression and KLF6‐SV1 knockdown in A235 and CRL2020 cell lines. Reconstitution of KLF6 decreased cell proliferation by almost 50%, whereas targeted KLF6 reduction increased cell proliferation 2.5–4.5 fold. Conversely, targeted KLF6‐SV1 reduction decreased cell proliferation by 50%. Taken together, our findings demonstrate that KLF6 allelic imbalance and decreased KLF6 and increased KLF6‐SV1 expression are common findings in primary GBM tumors, and these changes have antagonistic effects on the regulation of cellular proliferation in GBM cell lines. © 2007 Wiley‐Liss, Inc.
Somatic mutations of mitochondrial genome in early stage breast cancer
Authors: Wang Cheng‐Ye , Wang Hua‐Wei , Yao Yong‐Gang , Kong Qing‐Peng , Zhang Ya‐Ping
Published: May 2007

The complete mitochondrial genomes of the primary cancerous, matched paracancerous normal and distant normal tissues from 10 early‐stage breast cancer patients were analyzed in this study, with special attempt (i) to investigate whether the reported high frequency of mitochondrial DNA (mtDNA) somatic mutations in breast cancer could be repeated under a stringent data quality control, and (ii) to characterize the spectrum of mtDNA somatic mutations in Chinese breast cancer patients and evaluate their potential significance in early cancer diagnosis. Two heteroplasmic somatic transitions (T2275C and A8601G) were identified in our samples. The transition A8601G was present in the primary cancerous and paracancerous normal tissues from patient no. 3. Transition T2275C was found in the primary cancerous tissue but not in other normal tissues from patient no. 6; this transition has been reported in the colonic crypts and is located at a highly conserved site in the 16S rRNA gene. Subsequent cloning sequencing confirmed the absence of both mutations in the distant normal tissues from the 2 patients. The overall rate of somatic mutations in our patients was much lower than those of previous studies of breast cancer. Our results gave support to the recent claim that the high frequency of mtDNA somatic mutations in cancer studies is overestimated. Based on the mtDNA mutation pattern in early stage breast cancer observed in this study, we cautioned the enthusiasms and efforts to look for somatic mutations that were of diagnostic value in cancer early detection. © 2007 Wiley‐Liss, Inc.
Quantitation of phenylalanine and its trans‐cinnamic, benzoic and hippuric acid metabolites in biological fluids in a single GC‐MS analysis
Authors: Sarkissian Christineh N. , Scriver Charles R. , Mamer Orval A.
Published: May 2007

We describe a sensitive, simple and convenient stable isotope dilution assay developed to study endogenous metabolism of administered stable isotope‐labeled phenylalanine (Phe) in phenylketonuric (PKU) mice treated experimentally with phenylalanine ammonia lyase (PAL). Mouse urine and plasma containing endogenous and administered labeled Phe together with internal standard Phe bearing a different pattern of labeling are converted by in situ diazotization to 2‐chloro‐3‐phenylpropionic acid (CPP). A single solvent extraction is then used to isolate the isotopomers of CPP along with the trans‐cinnamic acid (TCA) produced from Phe by PAL, as well as the TCA metabolites benzoic and hippuric acids. This procedure eliminates the need for a separate ion‐exchange isolation step for Phe on a second sample aliquot and separate GC‐MS analysis. Extracted CPP and the Phe metabolites are then measured by conversion to the pentafluorobenzyl esters and a single analysis by electron capture negative ion GC‐MS. The estimated lower limit of quantitation is 0.1 µM. Copyright © 2007 John Wiley & Sons, Ltd.
Comprehensive liquid chromatography–ion‐spray tandem mass spectrometry method for the identification and quantification of eight hydroxylated brominated diphenyl ethers in environmental matrices
Authors: Mas Sílvia , Jáuregui Olga , Rubio Fernando , de Juan Anna , Tauler Romà , Lacorte Sílvia
Published: May 2007

We propose an instrumental method based on liquid chromatography coupled to negative ion‐spray ionization (ISP(−)) tandem mass spectrometry (MS/MS), for the simultaneous analysis of eight hydroxylated brominated diphenyl ethers (OH‐PBDEs) in four different environmental matrices (soil, fish, sludge and particulate matter). The reversed‐phase chromatographic separation was performed on a 50 mm Xbridge C18 column, and the compounds were well resolved with a gradient consisting of a ternary mixture of 5 mMammonium acetate, methanol and acetonitrile. Detection was performed in the multiple reaction monitoring (MRM) mode using the [M − H]− ion as base peak. The fragmentation pathways of the OH‐PBDEs varied according to the hydroxyl substitution in the benzene rings and produced characteristic MRM transitions needed for resolving isomeric compounds. The method is acceptable for quantification in the high picogram per gram dry weight (dw) level for all matrices analyzed. Repeatability and reproducibility tested at 75 pg µl−1 were below 10% using internal standard quantification. The ISP (−) enhancement due to matrix effects was in the 76–132% range and the highest values corresponded to sludge samples. The use of the proposed method based on LC‐ISP(−)‐MS/MS opens a new way to directly determine OH‐PBDEs without the need of derivatization. Copyright © 2007 John Wiley & Sons, Ltd.
Technical note: Characterization of binomial semivalues through delegation games
Authors: Amer Rafael , Giménez José Miguel
Published: May 2007

Semivalues are allocation rules for cooperative games that assign to each player in a given game a weighted sum of his marginal contributions to all coalitions he belongs to, where the weighting coefficients depend only on the coalition size. Binomial semivalues are a special class of semivalues whose weighting coefficients are obtained by means of a unique parameter. In particular, the Banzhaf value is a binomial semivalue. In this article, we provide an axiomatic characterization for each binomial semivalue. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Obscure heroes
Authors: Moore Carl M.
Published: May 2007

This paper asks whether the notion of a hero is useful in helping communities. After briefly identifying the origin, evolution, and components of a hero, the paper posits that what evolved to be called heroic leadership is not desirable because it is antithetical to democracy, unrealistic for a nuclear age, and can encourage us to wait for salvation. It would be more desireable to recognize and encourage obscure heroes, who are characterized primarily by their wisdom and moral courage.
Metro areas in the 21st century: Recognizing and anticipating the forces of change
Authors: Kemp Roger L.
Published: May 2007

The significant reduction in federal resources available to local governments and the devolution of issues‐management responsibilities from federal and state to local levels of government has been accompanied by major new political, social and economic trends, both national and global. Local jurisdictions — whether municipal, county or regional — must recognize both the scope and pace of this change, and harness the civic strength of their communities to form consensual, strategic visions.
Community needs assessment: An integrated approach
Authors: Parsons Robert J. , Henderson Dee W. , Palazzo James M. , Garn Ralph , Hulterstrom Bill
Published: May 2007

Communities are required to conduct needs assessments on a regular basis to allocate limited resources to the fulfillment of human service requirements. This article presents a comprehensive methodology to ensure that data are gathered from a variety of population segments. Community perceptions and identification of unmet needs are summarized for four different segments of the community. Since perceptions differ by population segment, it is important for community needs assessments to represent a cross‐section of the community rather than just an isolated segment such as opinion leaders only.
Municipal services and economic policy priorities among Florida's smaller cities: A comparison by public officials
Authors: Mattson Gary A.
Published: May 2007

Traditional economic development activities in small, rural communities tend to follow one of two main themes: industrial recruitment and promotion of tourism. More recently, a third approach has emerged which emphasizes the development and/or enhancement of existing quality‐of‐life amenities, with the goal of attracting and retaining new residents, as well as businesses that suit the community's socio‐economic character. All three approaches require different kinds of public investment; the third requires a tax structure that will permit the community to strike a strategic balance between essential and non‐essential (amenity‐type) services.
Community consensus for economic development
Authors: Tandy Kathleen Q. , Tandy Alan
Published: May 2007

Search conferences are participatory processes in which representatives of organizations, population sub‐sectors, and interest groups affected by a particular problem are brought together to work on the development of ongoing, strategic action. The approach is particularly applicable in communities where political dynamics typically impede consensus building on controversial issues.
Education: The path to urban greatness
Authors: Schmoke Kurt L.
Published: May 2007

The success of urban centers is linked to effective public education systems incorporating innovative approaches to school structure, learning and community involvement.
Restoring competitiveness in congressional elections
Authors: Wertheimer Fred
Published: May 2007

A sensational wave of successful term‐limitation initiatives at both the state and local levels has diverted media and popular attention from the universe of other options for increasing access to public office. Alternatives to the perceived “magic bullet” of term limits include campaign finance reform, campaign spending limits, and partial public funding for candidacies.
Your vote counts: The Wichita Eagle's election project
Authors: Smith Steven A.
Published: May 2007

The Wichita Eagle has installed an innovative, ongoing program to foster greater citizen awareness of and participation in the electoral process through activist research and reporting. The project involves evaluation of what constitutes substantive campaigning relevant to pressing community issues, and what constitutes extraneous political attack.
Community‐sensible governance: The emerging political reality of the 21st century
Authors: Neu Carl H. , Ethredge Jack
Published: May 2007

A New “civil war” is raging in the United States that will redefine where the power resides to shape and realize the destinies of communities. “Community‐sensible” governance must be the means by which U.S. communities and the nation as a whole will embark upon an uncertain but exciting future.
Local government environmental advisory boards
Authors: Harless James D.
Published: May 2007

Citizens wishing to shape or change environmental policy have historically had little influence to do so, short of forcing it through direct confrontation with elected officials. This article argues for the adoption of forums and processes for broad‐based community input into environmental policy making.
An etiquette for the 1990s regional council
Authors: Atkins Patricia S. , Wilson‐Gentry Laura
Published: May 2007

The rules of the game for regional councils in the 1960s and 1970s were shaped by their central role in federal policies promoting sub‐state regionalism. When money stopped flowing from the federal tap in the 1980s, regional councils got entrepreneurial and sought ties with state government.
Regional charter making in Polk county, Iowa
Authors: Hamilton Nadean L. , Tempero Richard M.
Published: May 2007

The availability of locally developed and adopted home‐rule charters, while serving the interests of government responsiveness, can aggravate fragmentation. Counties have greater convening and coordinating potential in metropolitan regions, as evidenced by Polk County, Iowa's long‐term efforts at regional charter making.
The role of gentrification in central city revitalization
Authors: Lampe David
Published: May 2007

Is it mainly race or mainly class that has hastened the flight of central cities' more propserous residents to the outlying suburbs? Can a range of socio‐economic classes live harmoniously, side‐by‐side in central city neighborhoods, or is one of the objectives of gentrification merely to re‐homogenize the urban mix?
Saving youth from violence: Charting new paths to safety
Authors: Hechinger Fred M.
Published: May 2007

Winning the war against youth violence will require a public stance that violence is socially unacceptable and that the nation's economic and social policies should reflect a society that despises, rather than tolerates and even glorifies violence.
When a right becomes a wrong
Authors: Eikenberry Karl W.
Published: May 2007

Our public dialogue is threatened by the burgeoning practice of framing policy debates in the language of “rights” — unlimited personal entitlement.
Evolution of national civic league policies: A retrospective
Authors: Cassella William N.
Published: May 2007

A review of of the National Civic League's policies and progams over the past century reveals a remarkable continuity: The ultimate emphasis of all NCL policies is responsibility — on the part of both public officials and citizens.
Financing florida's growth management
Authors: Mattson Gary A.
Published: May 2007

For smaller, rural communities in Florida, the state's 1985 Growth Management Act constitutes a new source of fiscal stress. Who loses? Very likely small‐town Floridians on fixed incomes.
Putting “citizens first!” in orange county, florida
Authors: Chapin Linda W. , Denhardt Robert B.
Published: May 2007

Sound governance capable of stimulating community renewal is a two‐way street, placing demands on both citizens and government. Governmental organizations, however, possess significant resources for enabling citizens to define and articulate their own needs and desires.
Consensus organizing. Sharing power to gain power
Authors: Eichler Michael
Published: May 2007

The 1960s style of community organizing — relying on conflict and confrontation — has become tired and ineffective. “Consensus organizers,” who use tactics of partnership and understanding, are blazing new paths of community renewal.
The association of personality type in childhood with violence in adolescence
Authors: Atkins Robert
Published: May 2007

The relationship of personality type at age 6 years to interpersonal violence at age 12 years was investigated. Participants from the Child Sample of the National Longitudinal Survey of Youth with complete data measures for the three time periods were categorized into one of the three personality types at age 6: under‐controlled, resilient, and over‐controlled. At age 12, participants assigned to the under‐controlled personality type 6 years earlier were more likely than those assigned to the resilient or over‐controlled personality types to report that they had hurt someone seriously at least once in the past year. The association of childhood personality to interpersonal violence 6 years later was not mediated by peer rejection or associations with deviant peers. © 2007 Wiley Periodicals, Inc. Res Nurs Health 30: 308–319, 2007
Effect of method of preparation and process variables on controlled release of insoluble drug from chitosan microspheres
Authors: Kulkarni Preeti V. , Keshavayya Jathi , Kulkarni Venkatrao H.
Published: May 2007

An inexpensive and simple method was adopted for the preparation of chitosan microspheres, crosslinked with glutaraldehyde (GA), for the controlled release of an insoluble drug‐ibuprofen, which is a commonly used NSAID (non‐steroidal anti‐inflammatory drug). The chitosan microspheres were prepared by different methods and varying the process conditions such as rate of stirring, concentration of crosslinking agent, and drug:polymer ratio in order to optimize these process variables on microsphere size, size distribution, degree of swelling, drug entrapment efficiency, and release rates. The absence of any chemical interaction between drug, polymer, and the crosslinking agent was confirmed by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA) techniques. The microspheres were characterized by optical microscopy, which indicated that the particles were in the size range of 30–200 µm and scanning electron microscopy (SEM) studies revealed a smooth surface and spherical shape of microspheres. The microsphere size/size distributions were increased with the decreased stirring rates as well as GA concentration in the suspension medium. Decreasing the concentration of crosslinker increased the swelling ratio whereas extended crosslinking exhibited lowered entrapment efficiency. The in vitro drug release was controlled and extended up to 10 hr. Copyright © 2007 John Wiley & Sons, Ltd.
Acute stress in parents of children newly diagnosed with cancer
Authors: Patiño‐Fernández Anna Maria , Pai Ahna L.H. , Alderfer Melissa , Hwang Wei‐Ting , Reilly Anne , Kazak Anne E.
Published: May 2007

Objective

Acute Stress Disorder (ASD) and subclinical symptoms of acute stress (SAS) may be a useful framework for understanding the psychological reactions of mothers and fathers of children newly diagnosed with a pediatric malignancy.

Patients and Methods

Mothers (N = 129) and fathers (N = 72) of 138 children newly diagnosed with cancer completed questionnaires assessing acute distress, anxiety, and family functioning. Demographic data were also gathered. Inclusion criteria were: a confirmed diagnosis of a pediatric malignancy in a child under the age of 18 years without prior chronic or life threatening illness and fluency in English or Spanish.

Results

Descriptive statistics and multiple linear regressions were used to examine predictors of SAS. Fifty‐one percent (N = 66) of mothers and 40% (N = 29) of fathers met DSM‐IV diagnostic criteria for ASD. The majority of the sample reported experiencing at least one SAS. General anxiety, but not family functioning, was a strong predictor of SAS in both mothers and fathers even after controlling for demographic characteristics.

Conclusions

Immediately following their child's diagnosis of cancer, most mothers and fathers experience SAS, with a subsample meeting criteria for ASD. More anxious parents are at heightened risk of more intense reactions. The findings support the need for evidence‐based psychosocial support at diagnosis and throughout treatment for families who are at risk for acute distress reactions. Pediatr Blood Cancer 2008;50:289–292. © 2007 Wiley‐Liss, Inc.
Anodised TiO2 nano‐tubes: voltage ramp influence on the nano‐structured oxide and investigation of phase changes promoted by thermal treatments
Authors: Regonini D. , Bowen C. R. , Stevens R. , Allsopp D. , Jaroenworaluck A.
Published: May 2007

TiO2 nano‐tubes have been generated by anodising commercially pure (99.6%) titanium in a 1 M solution of Na2SO4 which contains a small amount of NaF (0.1–1 wt%). The use of an initial voltage ramp, prior to the application of a constant voltage to the cell, led to an increase in the thickness of the nano‐tube layer. The thermal stability of the nano‐tube layer has also been evaluated by annealing at a variety of temperatures, from 200 to 600 °C. Scanning Electron Microscopy (SEM) of the annealed nano‐tubes indicate that they are stable up to 500 °C. Raman spectroscopy was performed to monitor and evaluate the changes in the crystal structure promoted by the thermal treatments. The as‐prepared nano‐tubes are amorphous, while anatase begins to form at 300 °C and rutile is found at 550 °C, a temperature at which the nano‐tubes begin to collapse. Initial results obtained by characterising the as‐prepared nano‐tubes with Transmission Electron Microscopy (TEM) are also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FePt thin film irradiated with high energy ions
Authors: Jaafar M. , Sanz R. , Vázquez M. , Asenjo A. , Jensen J. , Hjort K. , Flohrer S. , McCord J. , Schäfer R.
Published: May 2007

The changes in structural and magnetic properties of FePt thin films due to the irradiation with high energy ions (Br7+ and Cl2+) were studied. From the hysteresis loops dominating in‐plane anisotropy is derived, however, the samples present a minor out‐of‐plane component. The structure and the magnetic properties of the films can be tuned by selecting the appropriate irradiation parameters (different ions, energies and fluencies). For the irradiation parameters used in this study an in‐plane anisotropy is favoured. Irradiation with Br7+ seems to induce minor changes in the structural ordering of the thin films, whereas the Cl2+ ions promote the amorphization of the surface of the films. In addition, a magnetic thin film patterned at the micrometer scale was obtained after irradiation through a micrometric mask. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Organo‐vermiculite structure ordering after PVAc introduction
Authors: Simha Martynková Gražyna , Valášková Marta , Šupová Monika
Published: May 2007

Natural vermiculite served as a host for intercalation with quaternary ammonium salt (QUAT) followed by in‐situ polymerization of polyvinyl acetate (PVAc). We studied the structural changes of organo‐vermiculite and its PVAc nanocomposite with the help of X‐ray diffraction analysis. The mean crystallite size of PVAc nanocomposite is double compared to that of organo‐vermiculite and its distribution of crystallite sizes presents a broader region but more uniform values than the curve calculated for organo‐vermiculite. Molecular dynamic calculation proved a monolayer arrangement of QUAT guests and a bilayer‐like system of guest organic molecules in the vermiculite gallery. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zur Theorie und Konstruktion der Geschoßflugbahn
Authors: Schweikert G.
Published: May 2007

Es wird ein neues, einfaches und doch strenges und allgemeines Verfahren zur graphischen Konstruktion der Geschoßflugbahn entwickelt. Unter Zugrundelegung einer zusätzlichen, normalen Widerstandskomponente werden strenge und allgemeine ballistische Hauptgleichungen abgeleitet und Verfahren zu ihrer rechnerischen und mechanischen Integration mittels einer neuen Integriermaschine sowie zur experimentellen Ermittlung der Widerstandsgesetze angegeben.
Zur Theorie der Integriermaschine für gewöhnliche Differentialgleichungen
Authors: Sauer R. , Pösch H.
Published: May 2007

Für die auf dem Bush‐Prinzip beruhende neue Askania‐Integriermaschine wird die Frage nach dem Wirkungsbereich durch Aufzeigung der sämtlichen mit dem Gerät lösbaren Differentialgleichungen vollständig beantwortet und eine Klassifikation der Schaltungen gegeben.
Der gegabelte Verdichtungsstoß in Luft
Authors: Kofink W. , Vollmer Th.
Published: May 2007

Eine früher abgeleitete algebraische Gleichung (§ 1) für den gegabelten Verdichtungsstoß wird auf Stöße in Luft angewandt. Neben numerischen Daten für besonders interessierende Stoßkonfigurationen, die als spezielle Punkte und Kurven im Weise‐Diagramm für Luft auftreten, werden deren Gleichungen für beliebige x aufgestellt. (§2–4). In § 5 findet man schließlich eine kurze algebraische Behandlung der Herzkurven‐methode und der Schnittzahl von Haupt‐ und Nebenherz.
Zur Berechnung von Gitterströmungen bei einigermaßen großem Schaufelabstand. Herrn R. v. Mises zum 70. Geburtstag
Authors: Betz A.
Published: May 2007

Zur Berechnung von Gitterströmungen verwendet man vielfach das durch Diagramme gegebene Feld einer Wirbelreihe, bei der ein Wirbel fehlt. Dieses Feld wird durch eine Reihenentwicklung dargestellt, von der man bei großem Schaufelabstand nur das erste Glied braucht. Weiterhin wird gezeigt, wie man aus diesem Feld einer Wirbelreihe, das Feld einer entsprechenden Reihe von Tragflügeln mit gegebener Zirkulationsverteilung ermitteln kann und wie es sich auf die Gestalt der Flügel auswirkt.
Zum Problem des ebenen Spannungszustandes im kreiszylindrischen spröden Rohr unter konstantem Innen‐ und Außendruck
Authors: Glatzel E. , Schlechtweg H.
Published: May 2007

Unter Benutzung des nichtlinearen Verformungsgesetzes spröder Stoffe wie Gußeisen, Sandstein usw. wird im ersten Kapitel die Differentialgleichung 2. Ordnung für die Radialspannung σr näherungsweise mit ungefährer Fehlerabschätzung gelöst für Fälle, in denen σ φ/σr〈 − 1 bzw σφ/σr〉 2 ist. Im zweiten Kapitel handelt es sich um eine andere Lösungsmethode, die sich einer Differentialgleichung für die Radialverschiebung bedient, zu deren Aufstellung das benutzte Verformungsgesetz näherungsweise nach dem Spannungstensor aufgelöst wird.
Über erzwungene nicht‐lineare Schwingungen hoher Erreger‐frequenz und ihre Stabilität
Authors: Stellmacher K. L.
Published: May 2007

Um Einsicht zu gewinnen in das Verhalten von nicht‐linearen Schwingern bei nicht‐linearer periodischer Erregung hoher Frequenz, werden periodische Lösungen gewisser Differentialgleichungen zweiter Ordnung konstruiert, und die Stabilität dieser periodischen Lösungen weiter untersucht. Es ergeben sich gewisse Verzweigungsstellen der periodischen Lösungen, die hier im allgemeinen gleichzeitig Stabilitätsgrenzen darstellen.
Über ein ebenes unstetiges Temperaturspannungsproblem
Authors: Hieke Max
Published: May 2007

Zur Auffindung der Wärmespannungen in einem ungleichmäßig erwärmten Körper setzte man bisher die Differenzierbarkeit der Wärmeverteilungsfunktion voraus. Diese Voraussetzung wird in der vorliegenden Arbeit fallen gelassen, und als Beispiel werden die Wärmespannungen in einem unendlich langen Zylinder bei Vorgabe einer unstetigen Temperaturverteilung ermittelt.
Die turbulente Strömung an einer angeblasenen rotierenden Scheibe
Authors: Truckenbrodt E.
Published: May 2007

Es wird die turbulente Strömung an einer rotierenden ebenen Scheibe berechnet, die gleichzeitig in Richtung der Drehachse angeströmt wird. Die Dicke der durch die Drehbewegung mitgeschleppten Schicht und damit auch das Drehmoment sind stark abhängig von dem Verhältnis der Anströmungsgeschwindigkeit zur Umfangsgeschwindigkeit der Scheibe.
Über Iterationsverfahren für Gleichungen und Gleichungssysteme. (I. Teil)
Authors: Ludwig Rudolf
Published: May 2007

Unter dem Gesichtspunkt der Ordnung eines Iterationsverfahrens (Bodewig‐Hartree) gewinnt man durch einen allgemeinen Ansatz mit willkürlichen Funktionen eine große Anzahl von Iterationsverfahren, unter denen sich bekannte wie das Newtonsche befinden; aber auch neue und solche, die noch willkürliche Funktionen zur Konvergenzverbesserung enthalten.
Zur Lösung von Potentialaufgaben mit Hilfe des Differenzenverfahrens
Authors: Schröder Johann
Published: May 2007

Bei Anwendung des gewöhnlichen Differenzenverfahrens auf Randwertaufgaben der (ebenen oder räumlichen) Potentialtheorie erhält man ein lineares Gleichungssystem für die unbekannten (Näherungs‐) Funktionswerte in den Rechenpunkten des Gitters. Es wird ein in vielen Fällen anwendbares Verfahren zur vereinfachten Ermittelung dieser Unbekannten angegeben.
Maßnahmen zur Erzielung kurzer und übersichtlicher Programme für Rechenautomaten
Authors: Samelson Klaus , Bauer Friedrich L.
Published: May 2007

Um die Programme für Rechenautomaten durch Vermeidung überflüssiger Informationen zu verkürzen und zu vereinfachen, wird deren Struktur untersucht. Es wird gezeigt, daß sich gewisse systematische Änderungsprozesse für Unterprogramme automatisch durchführen lassen. Außerdem kann der Befehlscode dadurch sehr anpassungsfähig gestaltet werden, daß man ihn in Elementarbefehle zerlegt, die direkt miteinander kombiniert werden können. Es wird ein Beispiel für einen Befehlscode angegeben, der durch derartige Elementarbefehle erzeugt wird. In einem Anhang wird die Anwendung der Methoden, die der automatischen Durchführung der Änderungsprozesse dienen, genauer diskutiert.
Der höchstmögliche Auftrieb von Tragflügeln
Authors: Nickel Karl
Published: May 2007

Es wird untersucht, um welchen Betrag der Höchstauftrieb eines Tragflügels mindestens absinkt, wenn der Flügel außer Auftrieb noch aerodynamische Momente erzeugen soll. Beispiele. Mit den entwickelten Hilfsmitteln lassen sich noch andere Aufgaben behandeln.
Über Iterationsverfahren für Gleichungen und Gleichungssysteme. (Teil II)
Authors: Ludwig Rudolf
Published: May 2007

In gleicher Weise wie in Teil I werden hier Iterationsverfahren für Gleichungssysteme unter dem Gesichtspunkt der Ordnung des Verfahrens behandelt.
Stochastische Fehlerauswertung bei numerischen Methoden
Authors: Blanc Ch. , Liniger W.
Published: May 2007

In der vorliegenden Arbeit werden verschiedene numerische Verfahren auf stochastischer Grundlage mit einander verglichen. Dabei handelt es sich um Verfahren zur angenäherten Quadratur und um lineare Annäherungs‐ und Differenzenverfahren zur Lösung von linearen Randwertaufgaben zweiter Ordnung. Aus dieser Untersuchung ergibt sich im Besonderen die Überlegenheit des Differenzenverfahrens über dasjenige der linearen Annäherung.
Theorie des elastisch=plastischen Kontinuums mit freier Oberfläche bei veränderlicher Belastung
Authors: Küssner H. G.
Published: May 2007

Ein elastisch‐plastisches Kontinuum mit freier Oberfläche, welches der Schwerkraft unterliegt, wird einer zeitlich veränderlichen Belastung unterworfen. Die kleinen Verschiebungen des Kontinuums lassen sich darstellen als Produkte von Integraloperatoren, welche die äußere Belastung wiedergeben, und von charakteristischen Funktionen, welche die übrigen Randbedingungen befriedigen. Dasselbe gilt, wenn auf der Oberfläche eine elastische Platte schwimmt, welche die Belastungen trägt.
On boundary layer thickness
Authors: Wadhwa Y. D.
Published: May 2007

Following the “Synthetic Method” due to Seth a formula is found for the thickness of the boundary layer for the motion of thin liquids past solid boundaries. This formula is more reliable than R−1/2 as obtained hy Prandtl's boundary layer theory because it depends on the vorticity allowable outside the boundary layer. Besides, the pressure distribution inside the layer is not assumed to be that immediatey outside the layer, but is, in fact found to be different.
Analytische Untersuchung des Saitenanschlages
Authors: Karas K. , Ahbe H.
Published: May 2007

Der Anschlagvorgang wird unter Benutzung eines empirischen Gesetzes über die statische Deformation des Hammerfilzes mit Hilfe der Grundgleichungen der Mechanik untersucht. Unter der Voraussetzung unverschieblicher Saitenenden zeigt sich:

Die Druckkraft zwischen Hammer und Saite kann beim Anschlag in der Saitenmitte erhebliche Schwankungen aufweisen, deren Existenz nichts mit Wanderwellen der Saite zu tun zu haben braucht.

Die Hysterese des Hammerfilzes ist für die Erzeugung des Tones von entscheidender Bedeutung.

Die Rotationsträgheit der Saitenelemente hat bei Beschränkung auf die üblichen Dimensionen der Klaviersaiten keinen wesentlichen Einfluß auf den Anschlagvorgang.
Finite Torsion of Aeolotropic and Composite Cylinders I
Authors: Ramakanth J.
Published: May 2007

The problem of the finite torsion of a long solid circular cylinder was solved by B. R. Seth for the case that the cylinder is isotropic or transversally aeolotropic. B. R. Seth's method may be applied to obtain values for the torsion of isotropic hollow cylinders and hexagonal aeolotropic cylinders. The numerical results were compared with those obtained by means of the theory of the infinitely small compulsion.
Über Stabilität bei nichtlinearen Systemen
Authors: Hahn Wolfgang
Published: May 2007

Die 2. Methode von Ljapunov wird auf physikalische Systeme mit mehreren Freiheitsgraden angewandt, die durch nichtlineare Systeme von Differentialgleichungen erster Ordnung beschrieben sind. Für die asymptotische Stabilität der Ruhelage werden hinreichende Bedingungen abgeleitet, und zwar Ungleichungen, denen die Nichtlinearitäten genügen. Die in den Ungleichungen auftretenden Konstanten können kalkülmäßig bestimmt werden.
Zur hydrodynamischen Theorie der Schmiermittelreibung
Authors: Philipzik W.
Published: May 2007

Es wird die Reynoldssche Theorie auf das halbgeschlossene zylindrische Lager endlicher Breite für konstante und veränderliche Zähigkeit des Schmiermittels angewendet. Die Lösung der partiellen Differentialgleichung erfolgt bei konstanten Randwerten mit Hilfe des Differenzenverfahrens, die der Gleichungssysteme nach der Relaxationsmethode von Gauß‐Southwell. Es wird ferner der axiale Druckverlauf untersucht und ein Minimalsatz der Lagerreibung aufgestellt.
The Engineering Radiation Problem ‐ an example of the interaction between engineering and mathematics
Authors: Oppenheim A. K.
Published: May 2007

Die Strahlung als Problem in der Technik (im Gegensatz zur Strahlung als Problem der Astrophysik z. B.) beschäftigt sich mit Interreflektionen, die durch das Vorhandensein von Wänden ‐ den wesentlichen Elementen jedes Bausystems ‐ bedingt sind. Das Thema wird dargestellt in Form eines Beispiels der charakteristischen Schwierigkeiten, die durch die komplexe Geometrie des Systems bedingt sind ‐ ein Problem von großer Wichtigkeit für die technische Praxis, dem man oft aus durchsichtigen Gründen mit Hilfe der herkömmlichen mathematischen Analysis aus dem Wege geht. Es scheint, daß zur Erzielung einer numerischen Lösung die Formulierung des Problems als Integrodifferentialgleichungen ungeeignet und auf diesem Gebiet die Netzwerk‐Methode geeigneter ist, wie schon von Mises in einer seiner letzten Arbeiten tatsächlich ausgeführt hat.
Zur angenäherten Geradführung durch symmetrische Gelenkvierecke
Authors: Wunderlich W.
Published: May 2007

Für die seinerzeit von Tschebyschew entwickelten, durch achsialsymmetrische Koppelkurven mit dreifach berührender Scheiteltangente vermittelten angenäherten Geradführungen wird eine elementaralgebraische Theorie dargelegt, die eine einfache Berechnung und übersichtliche Erfassung der vielfältigen Annahmen gestattet.
A general sphere theorem for Hydrodynamics, Heat, Magnetism, and Electrostatics
Authors: Yeh G. C. K. , Martinek J. , Ludford G. S. S.
Published: May 2007

Das Störungspotential eines harmonischen Feldes bei Anwesenheit einer sphärischen Grenze wird durch Terme des ungestörten Potentials ausgedrückt. Das Feld kann sowohl innerhalb als auch außerhalb der Grenze Singularitäten aufweisen. Die Grenzbedingungen gleichen denen der Hydrodynamik, der Wärmeleitung, des Magnetismus und der Elektrostatik.
Über eine spezielle Integralgleichung
Authors: Pöschl Klaus
Published: May 2007

Die Berechnung der Spannung in den Drähten von Spanngittern, wie sie für Elektronenröhren verwendet werden, führt auf eine Klasse linearer Integralgleichungen zweiter Art in zwei Variablen. Für ihre Lösung spielt die Abhängigkeit Fredholm scher Gleichungen vom Integrationsintervall eine Rolle. Die betrachtete Integralgleichung hat keine Eigenwerte; ihr lösender Kern, eine Funktion von vier Variablen, jedoch Singularitäten, die durch die Eigenwerte der Fredholm schen Gleichung bestimmt sind.
Näherungsformel für den Drillungswiderstand eines vielzelligen, dünnwandigen Hohlprismas
Authors: Wittmeyer H.
Published: May 2007

Der Drillungswiderstand eines vielzelligen, dünnwandigen Hohlprismas wird als größter Eigenwert eines algebraischen Eigenwertproblems dargestellt. Als solcher kann er leicht unter Benutzung des Rayleighschen Prinzipes nach unten abgeschätzt werden.
Fehlerabschätzungen bei Anfangswertaufgaben gewöhnlicher Differentialgleichungssysteme 1. Ordnung
Authors: Uhlmann Werner
Published: May 2007

Es wurden Fehlerabschätzungen abgeleitet für stetig differenzierbare Näherungslösungen von Anfangswertaufgaben (System von s gewöhnlichen Differenzialgleichungen 1. Ordnung), und zwar für jede der s Näherungslösungen einzeln. Dabei werden die Vorzeichen der Lipschitz‐Konstanten soweit wie irgend möglich berücksichtigt. Vorher wird im 1. Abschnitt gezeigt, wie man diese Abschätzungen unmittelbar für das Adamssche Interpolationsverfahren und das Verfahren der zentralen Differenzen benutzen kann.
Anwendungsmöglichkeiten der Analyse der Wahrscheinlichkeitsdichtefunktionen bei der Auswertung von Messungsergebnissen
Authors: Medgyessy P.
Published: May 2007

Von gewissen, z. B. spektroskopischen Meßergebnissen weiß man nur, daß ihre Kurve eine Überlagerung — eine „Mischung”︁ — von sogenannten stabilen, z. B. Gaußschen Wahrscheinlichkeitsdichtefunktionen darstellt, deren Parameter — die gesuchten physikalischen Größen — unbekannt sind. — Das Problem der Bestimmung solcher Parameter, die sogenannte „Analyse der Mischung”︁ wird durch wahrscheinlichkeitheoretische Mittel exakt gelöst; dann werden Näherungsverfahren — hauptsächlich im Falle einer Mischung von Gaußschen bzw. Cauchyschen Funktionen — behandelt.
Abschätzung der Lösung der ersten Platten‐Randwertaufgabe nach der Methode von Maple‐Synge
Authors: Nicolovius Rüdiger
Published: May 2007

Unter Verwendung der von Synge eingeführten Hyperkreismethode wird eine Abschätzung für die Lösung der ersten Platten‐Randwertaufgabe hergeleitet, die der von Maple für die erste Randwertaufgabe der Potential‐theorie angegebenen Abschätzung entspricht. Die Methode wird an einem Zahlenbeispiel erprobt.
Advancement of a Compressible heat conducting fluid over an infinite flat plate
Authors: Gupta A. S.
Published: May 2007

The equations of motion in the unsteady case when a compressible viscous fluid with vanishing pressure gradient flows past an infinite flat plate have been integrated in semi‐convergent expressions when the physical constants depend on temperature. Simple expressions are obtained for temperature and velocity distribution in the boundary layer, the drag coefficients and their dependence on physical constants.