bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of aerosol containment on the elite flow cytometer
Authors: Ferbas John , Chadwick Karen R. , Logar Alison , Patterson Anne E. , Gilpin Richard W. , Margolick Joseph B.
Published: June 2005

Biohazardous aerosols generated during cell sorting have been of increased concern recently because of interest in sorting specimens containing human immunodeficiency virus type 1 (HIV‐1). Current flow cytometers have features designed to contain such aerosols within the sorting chamber, but the efficacy of these features has not been established. Therefore, we tested aerosol containment by two ELITE flow cytometers (Coulter Cytometry, Inc., Hialeah, FL) during sorting of specimens containing high titers of bacteriophage. Agar plates confluent with susceptible Escherichia coli were used to detect infectious units released from the sorting chamber. Under recommended operating conditions very few infectious units were released from the sorting chambers. Release increased when the center stream was not optimally collected in a vacuum‐exhausted tube or the chamber door was not completely closed. Failure of the negative pressure and high efficiency particle air (HEPA) filtration features had less of an effect. The data indicate that these standard safety features provide a rational expectation of safety for the flow cytometry operator. © 1995 Wiley‐Liss, Inc.
Comparison of monoclonal antibodies for flow cytometric analysis of HLA‐B27 antigen
Authors: Ward Anne M. , Nikaein Afzal
Published: June 2005

HLA‐B27 is an antigen associated with the disease ankylosing spondylitis. Ninety percent of Caucasians with ankylosing spondylitis possess the HLA‐B27 antigen. However, only 20% of Caucasians with the HLA‐B27 antigen will develop the disease. Defining the presence or absence of the HLA‐B27 antigen can be helpful in differentiating ankylosing spondylitis from juvenile rheumatoid arthritis. In this study, we evaluated the application of two monoclonal antibodies (MoAbs), using flow cytometric analysis for the detection of HLA‐B27 antigen. After an initial comparison of HLA‐B27 analysis by flow cytometry to the standard microlymphocytotoxicity assay, cutoffs were established to differentiate HLA‐B27 positive from HLA‐B27 negative. One MoAb showed very reliable results with >99% accuracy in discriminating HLA‐B27 positive from HLA‐B27 negative samples. Various parameters were investigated to obtain the optimum results and showed that incubation time, reagent lot, and the flow cytometric instrument can affect the results. We concluded that a reliable MoAb and flow cytometry are valuable for the rapid and inexpensive determination of HLA‐B27 typing in the clinical setting. However, testing conditions can affect the accuracy of results; therefore, adequate parallel testing in various conditions must be performed in order to establish the proper standards. © 1995 Wiley‐Liss, Inc.
Reproducibility in DNA flow cytometric analysis of breast cancer: Comparison of 12 laboratories' results for 67 sample homogenates
Authors: Baldetorp Bo , Bendahl Pär‐Ola , Fernö Mårten , Alanen Kalle , Delle Ulla , Falkmer Ursula , Hansson‐Aggesjö Britt , Höckenström Thomas , Lindgren Anders , Mossberg Lotta , Nordling Stig , Sigurdsson Helgi , Stål Olle , Visakorpi Tapio
Published: June 2005

Flow cytometric (FCM) DNA analysis yields information on ploidy status and the S‐phase fraction (SPF), variables of prognostic importance in breast cancer. The clinical value of the SPF is currently being evaluated in prospective randomized trials. The widespread use of FCM DNA analysis emphasizes the importance of reproducibility (both intra‐ and interlaboratory). In this study, 67 nuclear suspensions of breast cancer samples were analyzed by 12 laboratories routinely performing FCM DNA analysis in breast cancer. No general guidelines were imposed; each laboratory used its own standard protocols. For DNA ploidy status (diploid vs. non‐diploid), agreement was complete for 79% (53/67) of the samples, compared with 64% (43/67) of samples when tetraploidy was considered [i.e., euploid (diploid + tetraploid) vs. aneuploid (the remaining non‐diploid)]. For the SPF, pairwise comparison of the results of all 12 laboratories yielded a mean Spearman's rank correlation of 0.78 (range: 0.54–0.93). For those 39 samples being categorized in low or high SPF by all laboratories, all agreed in 14 samples (36%). Similar patterns were obtained with kappa measures, agreement being good for ploidy status (diploid vs. non‐diploid; overall K = 0.87 and 0.74 for euploid vs. aneuploid), but moderate for the SPF [overall k = 0.47 (for low SPF vs. high SPF vs. “no SPF reported”)]. Discrepancies were chiefly attributable to differences in the categorization of the S‐phase values, rather than in FCM procedures, other critical differences being in the detection and interpretation of near‐diploid and small non‐diploid cell populations, the definition of tetraploidy, and the choice and execution of the method used for S‐phase estimation. Based on the observations of this study, detailed guidelines for FCM analysis and interpretation of data are proposed in the Appendix. Some issues remain, however, e.g., to standardize a method for S‐phase calculation and tetraploid definition.© 1995 Wiley‐Liss, Inc.
Measurement of apoptotic cells in peripheral blood
Authors: Carbonari Maurizio , Cibati Marina , Fiorilli Massimo
Published: June 2005

The measurement of apoptosis in peripheral blood might represent a useful tool in acquired immunodeficiency syndrome (AIDS) and cancer research. Among the many assays that are currently used to identify apoptotic leukocytes, flow cytometric methods are the most valuable in terms of rapidity, simplicity, and level of analytical detail. Some flow cytometric assays may also offer the additional advantage of detecting the earliest phases of apoptosis, which is of paramount importance for measuring apoptotic cells in vivo before they are destroyed by phagocytes. © 1995 Wiley‐Liss, Inc.
DNA analysis of in situ ductal carcinoma of the breast via flow cytometry
Authors: Ottesen Gyda Lolk , Christensen Ib Jarle , Larsen Jørgen K. , Christiansen Jette , Hansen Bodil , Andersen Johan A.
Published: June 2005

Flow cytometric (FCM) DNA analysis of 41 clinical cases of ductal carcinoma in situ (DCIS) of the breast was performed on fine‐needle aspirates of unfixed, frozen tissue. Based on analysis of a single tissue sample, abnormal DNA content was found in 35 (85%) of the cases, and 15 (37%) disclosed heterogeneity. If five or more samples were analyzed, then heterogeneity was found in eight of ten cases. No conclusive correlation could be found between DNA index (DI) and histopathology. Our results on DCIS demonstrate a very high concordance with invasive breast cancer with respect to the frequency of DNA nondiploid cases, distribution of DI, occurrence of multiple clones, and S‐phase fraction. This indicates that major genetic alterations and DNA heterogeneity are early events in carcinogenesis that are already established at the preinvasive stage. © 1995 Wiley‐Liss, Inc.
Instrument‐Dependent fluorochrome sensitivity in flow cytometric analyses
Authors: Chance John T. , Larsen Sandra A. , Pope Victoria , Measel John W. , Cox David L.
Published: June 2005

Flow cytometry has become the preferred technique by which critical clinical evaluations are made such as CD4 counts and aneuploid analyses. Mounting concern has arisen over the numerous techniques, reagents, and different flow cytometers employed to determine these data. Several studies have documented significant differences in results when different flow cytometers are utilized to analyze the same sample. Fluorochrome‐dependent instrument sensitivity also has been reported by numerous investigators. As more and more procedures are performed by cytometric analysis, light scatter and fluorescence limitations, which appear to be instrument dependent, demonstrate that not all flow cytometers have the same capabilities. Attempts were made to calculate molecules of equivalent soluble fluorochrome (MESF) values on nine different flow cytometers using fluorescein isothiocyanate (FITC) and R‐phycoerythrin (R‐PE) labeled microsphere reference standards produced by Flow Cytometry Standards Corporation (FCSC). Dramatic differences were observed in the ability of some cytometers to resolve these microspheres. The diminished resolution appeared to be instrument model and fluorochrome dependent. We propose that diminished fluorescence resolution in certain flow cytometers could be responsible for significant variability in clinical values reported from laboratories utilizing different flow cytometers. © Wiley‐Liss, Inc.
Amplification and detection of a Y‐chromosome DNA sequence by fluorescence in situ polymerase chain reaction and flow cytometry using cells in suspension
Authors: Timm Earl A. , Podniesinski Ed , Stewart Carleton C. , Duckett Larry , Cardott John
Published: June 2005

A procedure for amplifying and detecting nucleic acid sequences in situ using cells in suspension and flow cytometry has been developed. The process involves the use of the polymerase chain reaction (PCR) and a fluorescent in situ hybridization (FISH) protocol developed in our laboratory to detect the amplified PCR product. For these studies, a Y‐chromosome specific repeat DNA sequence was amplified. Daudi cells, a B‐cell lymphoma culture line established from a male, was used as a positive control and HL‐60, a promyelocytic leukemia culture line established from a female, was used as a negative control. During the in situ PCR process cellular autofluorescence (noise) increases causing markedly reduced detection sensitivity of the probe (signal) bound to the amplified product within the positive cells. An autofluorescence reduction circuit was applied which was integrated into a standard bench top flow cytometer to reduce this noise, thereby producing a 10‐fold increase in detection sensitivity of the signal. Without the application of the autofluorescence reduction circuit, the positive control histogram distribution was virtually indistinguishable from the negative control sample distributions. After autofluorescence reduction, the data showed that the Y‐chromosome DNA was only amplified in the Daudi cells subjected to the complete in situ PCR protocol. This increased sensitivity also provided direct detection of the Y‐chromosome repeat sequence, albeit exhibiting less signal compared to the amplified target after the in situ PCR. © 1995 Wiley‐Liss, Inc.
Aneuploidy in breast cancer: A fluorescence in situ hybridization study
Authors: Shackney Stanley E. , Singh Sarita G. , Yakulis Robert , Smith Charles A. , Pollice Agnese A. , Petruolo Susan , Waggoner Alan , Hartsock Robert J.
Published: June 2005

Although ploidy is associated with the development and progression of most breast cancers, the value of flow cytometric ploidy as a clinical prognostic factor remains controversial. The technique of fluorescence in situ hybridization (FISH) can be used not only to determine overall ploidy, but also to assess the over‐representation or under‐representation of specific chromosomes in interphase cells. This information may be of prognostic value. We studied 84 primary breast cancers and 20 metastatic tumors by FISH, using chromosome‐specific fluorescent centromeric probes. Of these, 100 cases were also studied by DNA flow cytometry. The FISH studies were concordant with DNA flow cytometry with regard to distinguishing aneuploid from diploid tumors in 78% of cases. The FISH data suggested that aneuploidy arises by a process of chromosome complement doubling with subsequent chromosome loss. In tumors that exhibited evidence of more than one round of chromosome complement doubling, the selective accumulation of multiple copies of specific chromosomes or chromosome segments was common. Multiple copies of chromosomes centromeres 1, 3, and 17 were accumulated selectively in the cells of individual tumors more frequently than chromosomes centromeres 7, 11, and 16. Multiple copies of chromosomes centromeres 10 and 20 were selectively accumulated only rarely, if at all. Aneuploidy in breast cancer can be divided into distinct stages using fluorescence in situ hybridization techniques. The stages of aneuploidy provide potential landmarks in the genetic evolution of this disease with possible links to chromosome‐specific evolutionary changes. © 1995 Wiley‐Liss, Inc.
Spectroscopy and Redox Behaviour of Dicopper(II) and Dinickel(II) Complexes of Bis(cyclen) and Bis(cyclam) Ligands
Authors: El Ghachtouli Sanae , Cadiou Cyril , Déchamps‐Olivier Isabelle , Chuburu Françoise , Aplincourt Michel , Turcry Véronique , Le Baccon Michel , Handel Henri
Published: June 2005

The dinuclear CuII and NiII complexes of meta‐xylyl and pyridyl biscyclen and biscyclam have been prepared and characterised in solution by means of UV/Visible spectra, electrochemical and EPR studies. X‐ray structures of copper biscyclen complexes have been obtained. The comparison of all the data shows that the potentially coordinating N(py) pyridyl atom promotes the interaction between the two metal centers, whether it is spontaneously coordinated (biscyclen complexes) or not (biscyclam ones). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Pyridone Dipeptides – Synthesis of a Novel Peptide Chromophore
Authors: Tremmel Peter , Geyer Armin
Published: June 2005

Sequential elimination of two water molecules transfers the diols 2 and 3 into the pyridone dipeptide 1. Both dehydration steps become part of the peptide synthesis under appropriate reaction conditions. A straightforward strategy for the incorporation of 1 in oligopeptide sequences is presented here. As part of the oligopeptide backbone, 1 has a local rigidifying effect which was studied in the cyclic octapeptides 16 and 25. Both cyclopeptides exhibit conformational averaging although a fixed conformation was identified for the 1‐Phe tripeptide fragment of octapeptide 25. The pyridone dipeptide 1 serves also as a fluorescence label and the UV/Vis‐spectroscopic properties of tetrapeptide 13 are investigated here. The peptide backbones of the two cyclic octapeptides 16 and 25 arrange a pair of chromophores 1 in close vicinity of each other. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The state‐of‐the‐art in pyrolysis modelling of lignocellulosic solid fuels
Authors: Moghtaderi Behdad
Published: June 2005

Recent advances in mathematical modelling and numerical analysis of the pyrolysis of char forming solid fuels have shed new light on the pyrolytic behaviour of these materials under fire conditions. A review of the pyrolysis models of lignocellulosic (wood‐based) charring solid fuels developed over the past 60 years is presented in order of increasing complexity. The review, however, is limited to pyrolysis models developed for high temperature and high heating rate conditions and does not encompass the pyrolysis of wood‐based materials under conditions pertinent to ‘steam pipe’ type problems encountered typically at low temperatures, low heating rates and relatively long residence times. The models can be broadly categorized into thermal and comprehensive type models. While thermal models predict the conversion of the virgin fuel into products based on a critical pyrolysis criterion and the energy balance, the comprehensive models describe the degradation of the fuel by a chemical kinetic scheme coupled with the conservation equations for the transport of heat and/or mass. A variety of kinetic schemes have been reported in the literature ranging from simple one‐step global reactions to semi‐global and multi‐step reaction mechanisms. There has been much less uniformity in the description of the transport phenomena (i.e. heat and mass) in comprehensive models and different levels of approximation have been used. It is shown that the accuracy of pyrolysis models largely depends on the model parameters. Copyright © 2005 John Wiley & Sons, Ltd.
The combination of intermediate doses of thalidomide and dexamethasone reduces bone marrow micro‐vessel density but not serum levels of angiogenic cytokines in patients with refractory/relapsed multiple myeloma
Authors: Hatjiharissi E. , Terpos E. , Papaioannou M. , Hatjileontis C. , Kaloutsi V. , Galaktidou G. , Gerotziafas G. , Christakis J. , Zervas K.
Published: July 2005

The aim of the study was the evaluation of anti‐angiogenic activity of the combination of intermediate doses of thalidomide and dexamethasone in patients with refractory/relapsed myeloma. Twenty‐five patients were included in the study. Microvessel density (MVD) was evaluated in marrow biopsies before and after treatment. Serum levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (b‐FGF), tumor necrosis factor‐alpha (TNF‐α), which have angiogenic potential and interleukin‐6 (IL‐6), IL‐1β, soluble IL‐6 receptor (sIL‐6R), and transforming growth factor‐beta (TGF‐β) which are involved in the disease biology, were measured before treatment and then every 2 weeks for 8 weeks. Pretreatment levels of MVD, VEGF, b‐FGF, IL‐6, sIL‐6R were increased in the patients compared to controls. The overall response rate to therapy was 72%. The administration of the combined regimen produced a significant reduction in MVD in responders. However, an increase in serum levels of VEGF, b‐FGF, IL‐6, sIL‐6R was observed post‐treatment in responders. In contrast, serum levels of TNF‐α, TGF‐β, IL‐1β did not differ between patients and controls and remained unchanged during the study. These results suggest that the combination of thalidomide plus dexamethasone is an effective treatment for myeloma reducing MVD marrow levels but not serum levels of angiogenic cytokines or cytokines implicated in myeloma biology. Copyright © 2005 John Wiley & Sons, Ltd.
Voltage‐dependent K+ channel acts as sex steroid sensor in endocrine cells of the human ovary
Authors: Kunz Lars , Rämsch Romi , Krieger Annette , Young Kelly A. , Dissen Gregory A. , Stouffer Richard L. , Ojeda Sergio R. , Mayerhofer Artur
Published: June 2005

Molecular targets of rapid non‐genomic steroid actions are not well known compared to those of the classical transcription pathway, but ion channels have recently been identified to be steroid‐sensitive. Especially, in the ovary, the very organ producing high amounts of sex steroids, their rapid actions are not well examined. We now identified a yet unknown target for sex steroids, a voltage‐dependent K+ channel (Kv4.2) that contributes to a transient outward K+ current (IA) in human granulosa cells (GCs). Sex steroid hormones at concentrations typical for the ovary (1 µM) blocked Kv4.2 thereby attenuating IA by about 25% within seconds. We also found both Kv4.2 (KCND2) mRNA and protein in endocrine cells of the human and rhesus macaque ovary, emphasizing the physiological relevance of this channel. Therefore, we propose a role as fast‐responding steroid sensor for the Kv4.2 channel. The direct regulation of K+ channel activity by sex steroids might represent a yet unknown mechanism of rapid steroid action in close proximity to the site of steroid production in the primate ovary. Our data might also be important for Kv4 channels in the brain and the cardiovascular system where rapid steroid effects are discussed in the context of prevention of cell death. © 2005 Wiley‐Liss, Inc.
PLGA‐(L‐Asp‐alt‐diol)x‐PLGAs with Different Contents of Pendant Amino Groups: Synthesis and Characterization
Authors: Zhao Jie , Quan Daping , Liao Kairong , Wu Qing
Published: June 2005

Summary: A series of novel biodegradable multi‐block copolymers PLGA‐(L‐Asp‐alt‐diol)x‐PLGA with pendant amino groups was synthesized by ring‐opening polymerization of D,L‐lactide/glycolide(D,L‐LA/GA) (75/25) using poly(N‐Cbz‐L‐Asp‐alt‐diol)s as macroinitiator and stannous octoate as catalyst, in which the N‐Cbz‐L‐Asp represents N‐carbobenzyloxy‐L‐aspartic acid and diols are ethylene glycol, triethylene glycol, PEG200, and PEG600, respectively. Their structures and properties were characterized by FTIR, 1H NMR, DSC, GPC, and elemental analysis (EA). The contents of the L‐Asp unit in the copolymers were increased from 12.9 to 79.3 mmol · g−1 with decreasing the chain length of the diol, while the glass transition temperatures of the copolymers were decreased from 27.1 to 11.7 °C with increasing the chain length of the diol. Thus, the results in this study provide a way to prepare biomaterials with different L‐Asp unit densities or different number of bioactive sites as well as different properties through adjusting the chain length of the diol.

Synthesis of PLGA‐(N‐Cbz‐L‐Asp‐alt‐diol)x‐PLGA copolymers.

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Synthesis of PLGA‐(N‐Cbz‐L‐Asp‐alt‐diol)x‐PLGA copolymers.
Configuring and managing a large‐scale monitoring network: solving real world challenges for ultra‐low‐powered and long‐range wireless mesh networks
Authors: Dugas Christophe
Published: July 2005

In creating wireless networking solutions suitable for deployment in harsh, unpredictable and widespread environments, we were confronted with a series of problems as yet unsolved by commercially available technologies. The purpose of this article is to describe how we addressed mission‐critical customer requirements by developing a wireless technology explicitly for devices in ultra‐low‐power (ULP) and long‐range wireless mesh networks. The key end‐points in our target implementation are battery‐operated devices located in hard‐to‐reach places, but which are nonetheless expected to offer a lifespan of several years without human intervention. We provide an overview of the technical requirements for building ULP networks, with a focus on configuration and management (including patent pending self‐configuration and dynamic‐routing features). This is followed by a case study of an existing 25,000‐node wireless network deployed for an automatic meter reading (AMR) solution, and examples of provisioning individual nodes in complex real‐world networks. Copyright © 2005 John Wiley & Sons, Ltd.
Anionic polymerization of n‐hexyl isocyanate with monofuctional initiators. Synthesis of well‐defined diblock copolymers with styrene and isoprene
Authors: Zorba Georgia , Vazaios Aggelos , Pitsikalis Marinos , Hadjichristidis Nikos
Published: July 2005

Several monofunctional initiators, such as s‐BuLi, 1,1‐diphenyl‐4‐methylpentyl lithium (DPMPL), benzyl potassium (BzK), triphenylmethyl sodium (trityl sodium, TrNa) and benzyl sodium (BzNa) were tested and evaluated for the polymerization of n‐hexyl isocyanate (HIC) in THF at −98 °C. The polymerizations were conducted either without or with additives, such as LiBPh4, NaBPh4, and crown ether 18C6. The products were characterized by size exclusion chromatography (SEC), membrane osmometry (MO), and 1H NMR spectroscopy. The best results regarding polymerization yield, molecular weight distribution, and agreement between the stoichiometric and the experimentally observed molecular weight were obtained by the initiating system BzNa/NaBPh4 in a molar ratio 1/10. By using BzNa/NaBPh4 system, well‐defined block copolymers of HIC with styrene or isoprene were synthesized for the first time. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3533–3542, 2005
The fuzzball proposal for black holes: an elementary review
Authors: Mathur S.D.
Published: June 2005

We give an elementary review of black holes in string theory. We discuss BPS holes, the microscopic computation of entropy and the 'fuzzball' picture of the black hole interior suggested by microstates of the 2‐charge system.
Progress on holographic three‐point functions
Authors: Mück W.
Published: June 2005

The recently developed gauge‐invariant formalism for the treatment of fluctuations in holographic renormalization group (RG) flows overcomes most of the previously encountered technical difficulties. I summarize the formalism and present its application to the GPPZ flow, where scattering amplitudes between glueball states have been calculated and a set of selection rules been found.
String and supergravity motivated cosmology
Authors: Kallosh R.
Published: June 2005

In this pedagogical lecture we explain some basic part of the standard cosmological model which is most relevant for the fundamental theoretical physics. We stress the common features and differences between early universe inflation and late‐time acceleration. We than proceed with some recent attempts to address the issues of cosmology in string theory and higher dimensional supergravity with the emphasis on successes and still unsolved problems.
On the high‐temperature phase transitions of NH4HSO4
Authors: Diosa J. E. , Fernández M. E. , Vargas R. A. , Torijano E. , Mellander B.‐E.
Published: June 2005

Modulated differential scanning calorimetry (MDSC), thermogravimetric analysis (TGA) and X‐ray diffraction (XRD) were used to study the phase behaviour of NH4HSO4 (AHS) above room temperature. For powder AHS measured during successive thermal cycles, the MDSC curves show an endothermic peak at 147 °C on heating scans and an exothermic peak at about 115 °C on subsequent cooling runs. However, after the second thermal cycle, a second endothermic peak starts to appear at about 135 °C on heating runs whose intensity increases on subsequent cycles. The thermogravimetric measurements on powder AHS show weight loss above 135 °C. X‐ray powder diffraction data for AHS heated to 140 °C during 24 hours, show the diffraction pattern for (NH4)2S2O7. We discuss the endothermic effect at 135 °C in terms of a partial dehydration setting in at reaction sites distributed on the surface of the crystals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of the electrical properties of the new conductor Pr0.5Bi0.05Li0.35TiO3 prepared by sol–gel and ceramic methods
Authors: García‐Sánchez M.‐F. , Fernández Nestor , Martínez‐Sarrión María‐Luisa , Mestres Lourdes , Herraiz Marta , Escribano Purificación , Cordoncillo Eloisa , Beltrán Hector
Published: July 2005

Lithium ion conducting perovskite, Pr0.5Bi0.05Li0.35TiO3, has been synthesized by ceramic and sol–gel methods. The influence of the synthesis method on the crystal structure, morphology and ionic conductivity has been studied. Crystal structure of the material prepared by the sol–gel method is identical to that of the material prepared by the solid state reaction, although the synthesis temperature in the former case is lower. AC impedance measurements show two contributions to the ionic conductivity, which can be ascribed to grain and grain boundary effects. The bulk conductivity is similar for samples obtained by each methods. The grain boundary conductivity, and therefore the total conductivity, is higher for samples prepared by the sol–gel method. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preface: phys. stat. sol. (b) 242/9
Authors: Sánchez Maria
Published: July 2005

The XVII Latin American Symposium on Solid State Physics took place in the conference rooms of the Convent San Francisco de Asis, in the heart of the Old Havana. The sixteen previous editions were organized in eight different countries; the last two were in Colombia (Cartagena, 1999) and Venezuela (Merida, 2002). After eighteen years the meeting came back to Havana in 2004.

The program topics included: Surfaces and interfaces analysis; Spintronics; Magnetism; Materials and energy; Ab‐initio methods, simulations and modeling in solids; Nanophysics, nanomaterials and nanotechnology; New materials, properties and applications; Preparation of materials, thin films and characterization; High temperature superconductivity; Techniques of structural analysis in solids. The program included 6 plenary talks, 13 invited talks, 58 oral presentations (in eight sessions) and 200 poster contributions (in four poster sessions).

The meeting attracted more than 200 participants from 14 countries. The physica status solidi Young Researcher Award sponsored by Wiley‐VCH was conferred at the meeting. This prize was divided between two participants: Clara Calderón (“Study of electrical transport properties of ZnO thin films used as front contact of solar cells”) from Colombia and Aimé Pelaiz Barranco (“AC behavior in lanthanum modified PZT ferroelectric ceramics”) from Cuba. Special Mentions went to Valérie Halté (“Femtosec‐ond dynamics of transmission of gold arrays of sub‐wavelength holes”) from France, Erick Larramendi Cancio (“Cd desorption induced by Zn exposure during atomic layer epitaxy of CdxZn1−xTe”) and Julio Cesar Rimada Herrera (“Quantum and conversion efficiency calculation of AlGaAs/GaAs multiple quantum well solar cells”) from Cuba.

Nanostructures and in general low dimensional physics related to different systems was a very hot topic during the meeting. Some talks and presentations were devoted to optoelectronic materials and devices. Characterization of solids by different structural and optical techniques together with modeling and simulations were also important subjects of the symposium.

The XVIII Symposium will be held in Mexico in 2006.

The editors wish to thank all the participants who contributed to the success of the meeting and hope that it helped to develop close links between researchers and institutions of Latin America. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reactive oxygen species (ROS) and aging: Do we need them — can we measure them — should we block them?
Authors: Simm Andreas , Brömme Hans‐Jürgen
Published: June 2005

Reactive oxygen species (ROS) are derivatives of oxygen which arise during life in an oxygenated environment. Whereas there is a long discussion within the scientific community about the causes of aging, there is an impressive amount of data indicating that ROS are indeed a major cause for aging. An increase in radical production or a decrease in the defense against ROS appears to be associated with the decrease of the life span of an organism. On the other hand, in the last 15 years, it was shown that radicals are needed for cellular function. Therefore this review concentrates on the arguments for the link between ROS and aging, the hazardous nature of individual radicals, the possibility to analyze ROS and a short view on the impact of ROS on cellular functions.
Structure and properties of the fundamental elastic plate matrix
Authors: Cheng Zhen‐Qiang , Reddy J.N.
Published: June 2005

This work presents further development of the octet formalism established by the authors for the classical Kirchhoff anisotropic plate theory. The structure of the fundamental elastic plate matrix is fully explored and the explicit expression is provided. The matrices N2 and N3 are proved to be positive semi‐definite. Thus, H and L are positive definite. Further studies are concerned with a rotated coordinate system. The transform relation between the eigenvectors in the original and the rotated coordinate system is given. The fundamental elastic plate matrix associated with the eigenrelation referring to the dual coordinate systems, NΘ, is studied. The major properties that hold in the Stroh sextic formalism for generalized plane strain problems are also valid in the octet formalism for thin plate bending problems. In particular, we generalize a property in Stroh's formalism for any non‐semisimple matrix NΘ. We show a new property in the octet formalism. The non‐semisimple cases of NΘ are discussed. Finally, we make it transparent that the mixed/hybrid formalism of others is precisely one of sixteen permuted forms of the octet formalism.
Oscillation of perturbed nonlinear dynamic equations on time scales
Authors: Sun H.‐R. , Li W.‐R.
Published: June 2005

In this paper we consider the oscillatory and asymptotic behavior of bounded solutions of second‐order nonlinear perturbed dynamic equation (α(t)(xΔ(t))r)Δ+ F(t,xσ (t)) = G(t, xσ (t), xΔ (t)), t ∈𝕋 , (0.1) where r = k/l with k even and l odd positive integer. Some new sufficient conditions are obtained for all bounded solutions of (0.1) to be oscillatory. Several examples that dwell upon the importance of our results are also included. In particular, our criteria extend some earlier results.
Studies on abnormal metabolic function in Reye's syndrome
Authors: Tracey B. M. , Chalmers R. A. , Mehta A. , English N. , Purkiss P. , Valman H. B. , Stacey T. E.
Published: June 2005

Conclusions

(1) The presence of medium chain dicarboxylic acylcarnitines and 3‐hydroxydicarboxylic acids in the urine of a patient with Reye's syndrome suggests that β‐oxidation of dicarboxylic acids to succinyl CoA is occurring but also being inhibited at several stages. The cellular organelle responsible for this oxidation is not apparent.

(2) Administration of carnitine in Reye's syndrome appears to increase the production of acetylcarnitine. This would seem to indicate stimulation of β‐oxidation of fatty acids to acetyl CoA by the large amount of carnitine present.
Centrifugal trapping in the magnetotail
Authors: Delcourt D. C. , Martin R. F. , Sauvaud J. A. , Moore T. E.
Published: July 2005

Abstract. Particles leaving the neutral sheet in the distant magnetotail at times display adiabatic trajectory sequences characterized by an inflection toward the equator and subsequent mirroring in its vicinity. We demonstrate that this low-latitude mirroring results primarily from a centrifugal deceleration due to the fast direction-changing E×B drift. This effect which we refer to as "centrifugal trapping" appears both in guiding centre and full particle treatments. It thus does not directly relate to nonadiabatic motion. However, pitch angle scattering due to nonadiabatic neutral sheet interaction does play a role in reducing the parallel speed of the particles. We show that centrifugal trapping is an important mechanism for the confinement of the slowest (typically below the equatorial E×B drift speed) plasma sheet populations to the midplane vicinity.
Nighttime enhancements in ionospheric electron content: seasonal and solar cycle variation
Authors: Jain S. , Vijay S. K. , Gwal A. K. , Huang Y. N.
Published: July 2005

Abstract. Various characteristics of anomalous nighttime enhancement in ionospheric electron content (IEC) at Lunping (14.08°N geomagnetic), a station near the crest of the equatorial anomaly, have been presented by considering the IEC data for the 21st solar cycle. Out of a total of 1053 enhancements, 354 occur in pre-midnight and 699 occur in post-midnight hours, which indicates an overall dominance of post-midnight events at Lunping. The occurrence is more frequent during summer, less during the equinox and least during winter months. All the characteristics of the enhancements have seasonal dependencies and they reach their maximum values during summer months. The occurrence of the pre-midnight events show positive and post-midnight events show negative correlation with solar activity. The results have been discussed and compared with those at low-latitude stations in India and Hawaii and at the mid-latitude station, Tokyo.
Spatial transport and spectral transfer of solar wind turbulence composed of Alfvén waves and convective structures I: The theoretical model
Authors: Schmidt J. M. , Marsch E.
Published: July 2005

Abstract. In this paper we give a survey of detailed algebraic developments of a solar wind turbulence model. The numerical solution of the coupled system of spectral transfer equations for turbulence composed of Alfvén waves and convective structures or two-dimensional turbulence is prepared. The underlying theory of spectral transfer equations was established by several authors in the early 1990s. The related numerical turbulence model which is elaborated in detail in this paper is based on a rotationally symmetric solar wind model for the background magnetic and flow velocity fields with the full geometry of Parker's spiral which has to be inserted into the transfer equations. Various sources and sinks for turbulent energy are included and appropriately modelled analytically. Spherical expansion terms related to radial gradients of the background velocity fields are considered as far as possible within a rotational symmetric solar wind model, which excludes vorticity effects. Furthermore, nonlinear interaction terms are considered, justified by phenomenological arguments and evaluated by dimensional analysis. Moreover, parametric conversion terms for Alfvén waves and wave-structure interactions are modelled and a generalized spectral flux function for the residual energy eR is introduced. In addition, we compensate the spectra for WKB trends and f -5/3-slopes in order to prepare a convenient form of the equations for numerical treatment. The modelling of source and sink terms includes a special analytical treatment for correlation tensors. This first part presents a summary of the main ideas and the special approximations used for all these terms, together with details on the basic steps of the algebraic calculations. The description of the numerical scheme and a survey of the numerical results of our model, as well as a discussion of the main physical results are contained in a companion paper.
An analysis of geomagnetic field variations (3 min-2 h) at a low-latitude observatory (L=1.6)
Authors: Francia P. , Villante U. , Meloni A.
Published: July 2005

Abstract. An analysis of the geomagnetic field variations between 3 min and 2 h at L'Aquila (L=1.6) shows that the power level in the low-frequency range (i.e. for periods longer than approximately 10 min) at solar maximum (1989/90) is much higher than at solar minimum (1985/86). Conversely, at solar minimum, it emerges that there is a greater relative importance of fluctuations with periods smaller than 10 min which might be related to the greater percentage of solar wind speeds greater than approximately 540 km s–1. Diurnal, seasonal and solar cycle variations of both the high- and the low-frequency power are also discussed. We found that several aspects of these variations might be correlated with ionospheric features such as the ionisation of the F2 layer and the location and the intensity of the S current system.
Daytime F2-layer positive storm effect at middle and lower latitudes
Authors: Mikhailov A. V. , Skoblin M. G. , Förster M.
Published: July 2005

Abstract. Daytime F2-layer positive storm effects at middle and lower latitudes in the winter thermosphere are analyzed using AE-C, ESRO-4 neutral gas composition data, ground-based ionosonde observations and model calculations. Different longitudinal sectors marked by the storm onset as 'night-time' and 'daytime' demonstrate different F2-layer positive storm mechanisms. Neutral composition changes in the 'night-time' sector with increased [O] and [N2] absolute concentrations, while (N2/O)storm/(N2/O)quiet\\approx1 at F2-layer heights, are shown to contribute largely to the background NmF2 increase at lower latitudes lasting during daytime hours. Storm-induced surges of the equatorward wind give rise to an additional NmF2 increase above this background level. The mid-latitude F2-layer positive storm effect in the 'daytime' sector is due to the vertical plasma drift increase, resulting from the interaction of background (poleward) and storm-induced (equatorward) thermospheric winds, but not to changes of [O] and [N2] concentrations.
An optimised method for calculating the O+-O collision parameter from aeronomical measurements
Authors: Davis C. J. , Farmer A. D. , Aruliah A.
Published: July 2005

Abstract. A study has been made of the interaction between the thermosphere and the ionosphere at high latitudes, with particular regard to the value of the O+-O collision parameter. The European incoherent scatter radar (EISCAT) was used to make tristatic measurements of plasma parameters at F-region altitudes while simultaneous measurements of the neutral wind were made by a Fabry-Perot interferometer (FPI). The radar data were used to derive the meridional neutral winds in a way similar to that used by previous authors. The accuracy of this technique at high latitudes is reduced by the dynamic nature of the auroral ionosphere and the presence of significant vertical winds. The derived winds were compared with the meridional winds measured by the FPI. For each night, the value of the O+-O collision parameter which produced the best agreement between the two data sets was found. The precision of the collision frequency found in this way depends on the accuracy of the data. The statistical method was critically examined in an attempt to account for the variability in the data sets. This study revealed that systematic errors in the data, if unaccounted for by the analysis, have a tendency to increase the value of the derived collision frequency. Previous analyses did not weight each data set in order to account for the quality of the data; an improved method of analysis is suggested.
Diffusion spreading of middle-latitude ionospheric plasma irregularities
Authors: Blaunstein N.
Published: July 2005

Abstract. In contrast to the way that the spreading of irregularities in a plasma is usually considered, the diffusion spreading of irregularities stretched along the geomagnetic field B is examined using a three-dimensional rigorous numerical model of quasi-neutral diffusion in the presence of a magnetic field, in conjunction with the actual height variations of the diffusion and conductivity tensors in the ionosphere. A comparison with the earlier constructed approximate model of unipolar diffusion was made. As in the previous case, the same peculiarities of irregularity spreading in the inhomogeneous background ionospheric plasma were observed. The accuracy of the approximate model for describing the process of spreading of anisotropic ionospheric irregularities is established. Time relaxation effects of real heating-induced ionospheric irregularities on their scale transverse to B are presented using the approximate analytical model for the case of a quasi-homogeneous ionospheric plasma. The calculated results have a vivid physical meaning and can be directly compared with experimental data on the radiophysical observations of artificial heating-induced irregularities created by powerful radio waves in the ionosphere.
On the occurrence and characteristics of intense low-altitude electric fields observed by Freja
Authors: Marklund G. , Blomberg L. , Fälthammar C.-G. , Lindqvist P.-A. , Eliasson L.
Published: July 2005

Abstract. High-resolution measurements by the double probe electric field instrument on the Freja satellite are presented. The observations show that extremely intense (up to 1 V m–1) and fine-structured (<1 km) electric fields exist at auroral latitudes within the altitude regime explored by Freja (up to 1700 km). The intense field events typically occur within the early morning sector of the auroral oval (01–07 MLT) during times of geomagnetic activity. In contrast to the observations within the auroral acceleration region characterized by intense converging electric fields associated with electron precipitation, upward ion beams and upward field-aligned currents, the intense electric fields observed by Freja are often found to be diverging and located within regions of downward field-aligned currents outside the electron aurora. Moreover, the intense fields are observed in conjunction with precipitating and transversely energized ions of energies 0.5–1 keV and may play an important role in the ion heating. The observations suggest that the intense electric field events are associated with small-scale low-conductivity ionospheric regions void of auroral emissions such as east-west aligned dark filaments or vortex streets of black auroral curls located between or adjacent to auroral arcs within the morningside diffuse auroral region. We suggest that these intense fields also exist at ionospheric altitudes although no such observations have yet been made. This is possible since the height-integrated conductivity associated with the dark filaments may be as low as 0.1 S or less. In addition, Freja electric field data collected outside the auroral region are discussed with particular emphasis on subauroral electric fields which are observed within the 19–01 MLT sector between the equatorward edge of the auroral oval and the inner edge of the ring current.
Space physics coordinate transformations: the role of precession
Authors: Hapgood M. A.
Published: July 2005

Abstract. Raw data on spacecraft orbits and attitude are usually supplied in "inertial" coordinates. The normal geocentric inertial coordinate system changes slowly in time owing to the effects of astronomical precession and the nutation of the Earth's rotation axis. However, only precession produces a change that is significant compared with the errors in determining spacecraft position. We show that the transformations specified by Russell (1971) and Hapgood (1992) are strictly correct only if the epoch-of-date inertial system is used. We provide a simple formula for estimating the error in the calculated position if the inertial system for some other epoch is used. We also provide a formula for correcting inertial coordinates to the epoch-of-date from the standard fixed epoch of J2000.0.
Variations of solar EUV, UV and ionospheric foF2 related to the solar rotation period
Authors: Kane R. P. , de Paula E. R. , Trivedi N. B.
Published: July 2005

Abstract. Spectral analysis of daily values of various solar indices viz. sunspot number, 10.7-cm flux, H Lyman-α and -β, specific He, Fe and Mg lines and solar X-rays was carried out for two selected intervals. During interval A (May-August 1978, 123 days) the solar indices showed a prominent periodicity near 27 days, while during interval B (January-May 1979, 151 days) the solar indices showed a prominent periodicity near 13 days. For the same intervals, foF2 (max) and foF2 (average) during 1000-1500 LT were similarly analysed for the locations Cachoeira Paulista, SP, Brazil (23°S, 45°W), and Okinawa (26°N, 128°E) and Kokubunji (36°N, 139°E) in Japan. The 27-day and 13-day periodicities in solar indices were reflected in the foF2 series, but in different relative proportions at the three locations, probably due to the interference of local aerodynamical effects. Some other periodicities were common to solar indices and foF2, while some others were present in the solar indices but not in foF2, or vice versa
Air mass exchange across the polar vortex edge during a simulated major stratospheric warming
Authors: Günther G. , Dameris M.
Published: July 2005

Abstract. The dynamics of the polar vortex in winter and spring play an important role in explaining observed low ozone values. A quantification of physical and chemical processes is necessary to obtain information about natural and anthropogenic causes of fluctuations of ozone. This paper aims to contribute to answering the question of how permeable the polar vortex is. The transport into and out of the vortex ("degree of isolation") remains the subject of considerable debate. Based on the results of a three-dimensional mechanistic model of the middle atmosphere, the possibility of exchange of air masses across the polar vortex edge is investigated. Additionally the horizontal and vertical structure of the polar vortex is examined. The model simulation used for this study is related to the major stratospheric warming observed in February 1989. The model results show fair agreement with observed features of the major warming of 1989. Complex structures of the simulated polar vortex are illustrated by horizontal and vertical cross sections of potential vorticity and inert tracer. A three-dimensional view of the polar vortex enables a description of the vortex as a whole. During the simulation two vortices and an anticyclone, grouped together in a very stable tripolar structure, and a weaker, more amorphous anticyclone are formed. This leads to the generation of small-scale features. The results also indicate that the permeability of the vortex edges is low because the interior of the vortices remain isolated during the simulation.