bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in Bacterioplankton Composition under Different Phytoplankton Regimens
Authors: Pinhassi Jarone , Sala Maria Montserrat , Havskum Harry , Peters Francesc , Guadayol Òscar , Malits Andrea , Marrasé Cèlia
Published: November 2004

The results of empirical studies have revealed links between phytoplankton and bacterioplankton, such as the frequent correlation between chlorophyll
a
and bulk bacterial abundance and production. Nevertheless, little is known about possible links at the level of specific taxonomic groups. To investigate this issue, seawater microcosm experiments were performed in the northwestern Mediterranean Sea. Turbulence was used as a noninvasive means to induce phytoplankton blooms dominated by different algae. Microcosms exposed to turbulence became dominated by diatoms, while small phytoflagellates gained importance under still conditions. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments showed that changes in phytoplankton community composition were followed by shifts in bacterioplankton community composition, both as changes in the presence or absence of distinct bacterial phylotypes and as differences in the relative abundance of ubiquitous phylotypes. Sequencing of DGGE bands showed that four
Roseobacter
phylotypes were present in all microcosms. The microcosms with a higher proportion of phytoflagellates were characterized by four phylotypes of the
Bacteroidetes
phylum: two affiliated with the family
Cryomorphaceae
and two with the family
Flavobacteriaceae
. Two other
Flavobacteriaceae
phylotypes were characteristic of the diatom-dominated microcosms, together with one
Alphaproteobacteria
phylotype (
Roseobacter
) and one
Gammaproteobacteria
phylotype (
Methylophaga
). Phylogenetic analyses of published
Bacteroidetes
16S rRNA gene sequences confirmed that members of the
Flavobacteriaceae
are remarkably responsive to phytoplankton blooms, indicating these bacteria could be particularly important in the processing of organic matter during such events. Our data suggest that quantitative and qualitative differences in phytoplankton species composition may lead to pronounced differences in bacterioplankton species composition.
Intracellular Proliferation of
Legionella pneumophila
in
Hartmannella vermiformis
in Aquatic Biofilms Grown on Plasticized Polyvinyl Chloride
Authors: Kuiper Melanie W. , Wullings Bart A. , Akkermans Antoon D. L. , Beumer Rijkelt R. , van der Kooij Dick
Published: November 2004

The need for protozoa for the proliferation of
Legionella pneumophila
in aquatic habitats is still not fully understood and is even questioned by some investigators. This study shows the in vivo growth of
L. pneumophila
in protozoa in aquatic biofilms developing at high concentrations on plasticized polyvinyl chloride in a batch system with autoclaved tap water. The inoculum, a mixed microbial community including indigenous
L. pneumophila
originating from a tap water system, was added in an unfiltered as well as filtered (cellulose nitrate, 3.0-μm pore size) state. Both the attached and suspended biomasses were examined for their total amounts of ATP, for culturable
L. pneumophila
, and for their concentrations of protozoa.
L. pneumophila
grew to high numbers (6.3 log CFU/cm
2
) only in flasks with an unfiltered inoculum. Filtration obviously removed the growth-supporting factor, but it did not affect biofilm formation, as determined by measuring ATP. Cultivation, direct counting, and 18S ribosomal DNA-targeted PCR with subsequent sequencing revealed the presence of
Hartmannella vermiformis
in all flasks in which
L. pneumophila
multiplied and also when cycloheximide had been added. Fluorescent in situ hybridization clearly demonstrated the intracellular growth of
L. pneumophila
in trophozoites of
H. vermiformis
, with 25.9% ± 10.5% of the trophozoites containing
L. pneumophila
on day 10 and >90% containing
L. pneumophila
on day 14. Calculations confirmed that intracellular growth was most likely the only way for
L. pneumophila
to proliferate within the biofilm. Higher biofilm concentrations, measured as amounts of ATP, gave higher
L. pneumophila
concentrations, and therefore the growth of
L. pneumophila
within engineered water systems can be limited by controlling biofilm formation.
Influence of an Oyster Reef on Development of the Microbial Heterotrophic Community of an Estuarine Biofilm
Authors: Nocker Andreas , Lepo Joe E. , Snyder Richard A.
Published: November 2004

We characterized microbial biofilm communities developed over two very closely located but distinct benthic habitats in the Pensacola Bay estuary using two complementary cultivation-independent molecular techniques. Biofilms were grown for 7 days on glass slides held in racks 10 to 15 cm over an oyster reef and an adjacent muddy sand bottom. Total biomass and optical densities of dried biofilms showed dramatic differences for oyster reef versus non-oyster reef biofilms. This study assessed whether the observed spatial variation was reflected in the heterotrophic prokaryotic species composition. Genomic biofilm DNA from both locations was isolated and served as a template to amplify 16S rRNA genes with universal eubacterial primers. Fluorescently labeled PCR products were analyzed by terminal restriction fragment length polymorphism, creating a genetic fingerprint of the composition of the microbial communities. Unlabeled PCR products were cloned in order to construct a clone library of 16S rRNA genes. Amplified ribosomal DNA restriction analysis was used to screen and define ribotypes. Partial sequences from unique ribotypes were compared with existing database entries to identify species and to construct phylogenetic trees representative of community structures. A pronounced difference in species richness and evenness was observed at the two sites. The biofilm community structure from the oyster reef setting had greater evenness and species richness than the one from the muddy sand bottom. The vast majority of the bacteria in the oyster reef biofilm were related to members of the γ- and δ-subdivisions of
Proteobacteria
, the
Cytophaga-Flavobacterium -Bacteroides
cluster, and the phyla
Planctomyces
and
Holophaga-Acidobacterium
. The same groups were also present in the biofilm harvested at the muddy sand bottom, with the difference that nearly half of the community consisted of representatives of the
Planctomyces
phylum. Total species richness was estimated to be 417 for the oyster reef and 60 for the muddy sand bottom, with 10.5% of the total unique species identified being shared between habitats. The results suggest dramatic differences in habitat-specific microbial diversity that have implications for overall microbial diversity within estuaries.
Adhesion of
Enterococcus faecalis
in the Nonculturable State to Plankton Is the Main Mechanism Responsible for Persistence of This Bacterium in both Lake and Seawater
Authors: Signoretto Caterina , Burlacchini Gloria , Lleò Maria del Mar , Pruzzo Carla , Zampini Massimiliano , Pane Luigi , Franzini Giorgio , Canepari Pietro
Published: November 2004

The presence of enterococci in lake and seawater in an 18-month survey comparing molecular (PCR and quantitative PCR) and culture methods was evaluated, as well as the possibility that zooplankton could act as reservoirs for enterococci. Samples of both water and zooplankton were collected monthly from a Lake Garda site and an Adriatic Sea site. In lake water, the positive samples numbered 13 of 54 (24%) by culture and 32 of 54 (59%) when PCR was applied. In seawater, they numbered 0 of 51 by culture and 18 of 51 (35%) by PCR. Enterococci were found either totally bound to plankton or totally in water, depending on the presence or absence of plankton, respectively. These results clearly indicate that the PCR assay is a powerful tool for detecting fecal indicators and pathogens in the environment, thus providing a much more sensitive method than culture.
Use of Transposon-Transposase Complexes To Create Stable Insertion Mutant Strains of
Francisella tularensis
LVS
Authors: Kawula Thomas H. , Hall Joshua D. , Fuller James R. , Craven Robin R.
Published: November 2004

Francisella tularensis
is a highly virulent zoonotic bacterial pathogen capable of infecting numerous different mammalian species, including humans. Elucidation of the pathogenic mechanisms of
F. tularensis
has been hampered by a lack of tools to genetically manipulate this organism. Herein we describe the use of transposome complexes to create insertion mutations in the chromosome of the
F. tularensis
live vaccine strain (LVS). A Tn
5
-derived transposon encoding kanamycin resistance and lacking a transposase gene was complexed with transposase enzyme and transformed directly into
F. tularensis
LVS by electroporation. An insertion frequency of 2.6 × 10
−8
± 0.87 × 10
−8
per cell was consistently achieved using this method. There are 178 described Tn
5
consensus target sites distributed throughout the
F. tularensis
genome. Twenty-two of 26 transposon insertions analyzed were within known or predicted open reading frames, but none of these insertions was associated with the Tn
5
target site. Analysis of the insertions of sequentially passed strains indicated that the transposons were maintained stably at the initial insertion site after more than 270 generations. Therefore, transformation by electroporation of Tn
5
-based transposon-transposase complexes provided an efficient mechanism for generating random, stable chromosomal insertion mutations in
F. tularensis
.
In Vitro Laser Ablation of Natural Marine Biofilms
Authors: Nandakumar Kanavillil , Obika Hideki , Utsumi Akihiro , Ooie Toshihiko , Yano Tetsuo
Published: November 2004

We studied the efficiency of pulsed low-power laser irradiation of 532 nm from an Nd:YAG (neodymium-doped yttrium-aluminum-garnet) laser to remove marine biofilm developed on titanium and glass coupons. Natural biofilms with thicknesses of 79.4 ± 27.8 μm (titanium) and 107.4 ± 28.5 μm (glass) were completely disrupted by 30 s of laser irradiation (fluence, 0.1 J/cm
2
). Laser irradiation significantly reduced the number of diatoms and bacteria in the biofilm (paired
t
test;
P
< 0.05). The removal was better on titanium than on glass coupons.
Combined Phospholipid Biomarker-16S rRNA Gene Denaturing Gradient Gel Electrophoresis Analysis of Bacterial Diversity and Physiological Status in an Intertidal Microbial Mat
Authors: Villanueva Laura , Navarrete Antoni , Urmeneta Jordi , White David C. , Guerrero Ricardo
Published: November 2004

A combined lipid biomarker-16S rRNA gene denaturing gradient gel electrophoresis analysis was used to monitor changes in the physiological status, biomass, and microbial composition of a microbial mat. In the morning hours, an increase in the biomass of layers containing a high density of phototrophs and a decrease in the growth rate in the deep layers were observed. The combined approach also revealed differences in major groups of microorganisms, including green nonsulfur, gram-positive, and heterotrophic bacteria.
Diversity of Toxic Shock Syndrome Toxin 1-Positive
Staphylococcus aureus
Isolates
Authors: Warner John E. , Onderdonk Andrew B.
Published: November 2004

Staphylococcus aureus
isolates from women with nasal, anal, or vaginal colonization were evaluated for population diversity by pulsed-field gel electrophoresis. Cluster analysis of restriction patterns revealed diversity indices of 0.89 and 0.99 for toxic shock syndrome toxin 1-positive and -negative isolates, respectively. Toxin-producing strains were isolated more frequently from the nares than from other sites.
Selection of Single-Chain Antibodies against the VP8* Subunit of Rotavirus VP4 Outer Capsid Protein and Their Expression inLactobacillus casei
Authors: Monedero Vicente , Rodríguez-Díaz Jesús , Viana Rosa , Buesa Javier , Pérez-Martínez Gaspar
Published: November 2004

Single-chain antibodies (scFv) recognizing the VP8* fraction of rotavirus outer capsid and blocking rotavirus infection in vitro were isolated by phage display. Vectors for the extracellular expression inLactobacillus caseiof one of the scFv were constructed.L. caseiwas able to secrete active scFv to the growth medium, showing the potential of probiotic bacteria to be engineered to express molecules suitable for in vivo antirotavirus therapies.
BIO-PIXE: PRESENT STATUS AND FUTURE PROSPECTS
Authors: MALMQVIST K.G.
Published: November 2004

The status of the field of analysis of biological material using PIXE and complementary ion beam techniques are discussed. The development of PIXE with relevance to biology and the future prospects of Bio-PIXE are described.
Design of Absorbers for Metal-rich Samples in PIXE Analysis (Application of PIXE to various research fields at NMCC)
Authors: SERA K. , FUTATSUGAWA S.
Published: November 2004

About 40 subjects of PIXE have been studied in various research fields at Nishina Memorial Cyclotron Center (NMCC), and many satisfactory results have been obtained and reported. As the results, samples to be analyzed are highly diversified both in form and in elemental composition. Among them, samples most hard to be dealt with by PIXE are ones which contain a great quantity of specific elements. In order to solve this problem, we have developed and tried various absorbers which are specially designed for each kind of sample and are capable of decreasing some distinguished x-ray peak and making x-ray spectra gentle-sloping. It is found that not only the measuring time is fairly shortened but also highly sensitive and highly accurate analysis can be performed for each sample only by selecting absorbers.
TRACE ELEMENT ANALYSIS IN AN OPTIMIZED SET-UP FOR TOTAL REFLECTION PIXE (TPIXE)
Authors: VAN KAN J.A. , VIS R.D.
Published: November 2004

A newly constructed chamber for measuring with MeV proton beams at small incidence angles (0 to 35 mrad) is used to analyse trace elements on flat surfaces such as Si wafers, quartz substrates and perspex. This set-up is constructed in such a way that the X-ray detector can reach very large solid angles, larger than 1 sr. Using these large solid angles in combination with the reduction of bremsstrahlungs background, lower limits of detection (LOD) using TPIXE can be obtained as compared with PIXE in the conventional geometry. Standard solutions are used to determine the LODs obtainable with TPIXE in the optimized setup. These solutions contain traces of As and Sr with concentrations down to 20 ppb in an insulin solution. The limits of detection found are compared with earlier ones obtained with TPIXE in a non optimized setup and with TXRF results.
SYSTEM OF PATTERN ANALYSIS IN PIXE SPECTRA
Authors: MUROZONO K. , IWASAKI S. , INOUE J. , ISHII K. , KITAMURA M. , SERA K. , FUTATSUGAWA S.
Published: November 2004

We have developed a software system based on the pattern analysis method in order to realize the automatic and quick PIXE spectra analysis. The software system was applied to some PIXE spectra to test the present method. Through the tests, important knowledge was obtained and some notions were adopted to the system.
Application of micro beam PIXE in biomedical implant research
Authors: EKTESSABI A.M.
Published: November 2004

The material composition and surface structure of dental and orthopaedic implants influence the integration in bone, and, at the same time, the release of the constituent elements of the implants into the surrounding tissues. Titanium, titanium alloys (Ti-6Al-4V) and other materials which are considered to be biocompatible materials, release metal ions into the surrounding tissues. This may affect the appropriate biological response of the tissues to the implanted materials. The toxicity of some of the constituent elements of these implants, e.g. vanadium, is a matter of serious concern. In this paper, the experimental data on application of PIXE to biomedical-implant research are presented. Two groups of samples were prepared for PIXE analysis. The first group consisted of the specimens that were retrieved from the tissues around implants in 28 rats. The second group consisted of specimens that were sliced and polished to a thickness of a few 10 µm, while keeping the interface between the implant, cortical bone, bone marrow, and soft tissues intact. The implants of the second group, 10 specimens with between 6 and 20 measurement points on each specimen, were used for specifically obtaining the distribution of the released elements with reference to the implant tissue interface, using ion micro beam. The implantation time ranged from 12 weeks to 52 weeks.
MICROPROBE PIXE ANALYSIS AND EDX ANALYSIS ON THE BRAIN OF PATIENTS WITH ALZHEIMER’S DISEASE
Authors: YUMOTO S. , HORINO Y. , MOKUNO Y , FUJII K. , KAKIMI S. , MIZUTANI T. , MATSUSHIMA H. , ISHIKAWA A.
Published: November 2004

To investigate the cause of Alzheimer’s disease (senile dementia of Alzheimer’s disease type), we examined aluminium (Al) in the brain (hippocampus) of patients with Alzheimer’s disease using heavy ion (5 MeV Si 3+) microprobe particle-induced X-ray emission (PIXE) analysis. Heavy ion microprobes (3 MeV Si 2+) have several times higher sensitivity for Al detection than 2 MeV proton microprobes. We also examined Al in the brain of these patients by energy dispersive X-ray spectroscopy (EDX). (1) Al was detected in the cell nuclei isolated from the brain of patients with Alzheimer’s disease using 5 MeV Si 3+ microprobe PIXE analysis, and EDX analysis. (2) EDX analysis demonstrated high levels of Al in the nucleolus of nerve cells in frozen sections prepared from the brain of these patients. Our results support the theory that Alzheimer’s disease is caused by accumulation of Al in the nuclei of brain cells.
DETERMINATION OF TRACE ELEMENTS IN HUMAN SALIVA BY PIXE TECHNIQUE
Authors: HATAMI P. , PEYROVAN H. , AFARIDEH H. , SHOJAEI S.
Published: November 2004

Mineral trace element concentration of human saliva from healthy volunteers, were investigated by Proton-Induced X-ray Emission (PIXE) analysis. The specimens were bombarded with Proton beams of 2 MeV from a Van de Graaff accelerator at NRC . The object of this measurement was to find a normal range of trace element concentration for Iranian people.
PIXE ANALYSIS ON DESORPTION OF ELEMENTS FROM BOG MUD (II)
Authors: MATSUDA Y. , NISHIYAMA F. , YAMAMOTO K. , KASAHARA M. , ISHIYAMA T.
Published: November 2004

To obtain background information to formulate strategy to keep lakes, marshes and bogs free from pollution. soil and peat were sampled and analyzed continually. Sample preparation, size segregation and chemical extraction with ultra-pure water. 0.2 M ( NH 4)2 C 2 O 4. 1 M CH 3 COONH 4, 0.01M EDTA·2Na, 1N HCl and 6N HCl were undertaken prior to the normal PIXE target preparation. It was found that with present improved PIXE plus correct chemical extraction procedure. chemical informations about a variety of mud components are easily brought through the element concentrations especially Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Br. The tendency that irreversible absorption components are more abundant than EDTA·2Na extraction components was common for Mn, Ni, Cu, Zn and Fe, The ratios of Ni. Cu and Zn to Fe in a irreversible absorption component were the same in an EDTA·2Na extraction component. On the other hand, Mn/Fe ratios were deviated to an EDTA·2Na extraction component side.
PIXE ANALYSIS OF THE SERUM OF MICE ACQUIRED RADIO-RESISTIBILITY BY LOW DOSE X-RAYS
Authors: MATSUDA Y. , YONEZAWA M. , NISHIYAMA F.
Published: November 2004

It is not only important for maintenance and improvement of health, but also indispensable for diagnosis and remedy of diseases to make inquiries into the biological defence mechanisms. Yonezawa et al. came across an induction of yet unknown defence mechanism(s) in mice which acquired radioresistance two weeks after low dose X-irradiation with 0.5 Gy. The 30-day survival rate after midlethal X-irradiation of the mice significantly increased by the pre-irradiation, but contrary to the common knowledge on radiation protection, recovery of the blood cell counts of thrombocytes, leukocytes and erythrocytes were not stimulated by the pre-irradiation. This study was planned to find some keys to elucidate the mechanism for the acquired radioresistance. Metal ions are well known to be important for enzyme activities as well as for metabolisms. Eleven elements, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se and Br were analysed in mice sera by PIXE.
PRELIMINARY STUDY ON THE CHARACTERISTICS OF AEROSOLS OVER THE WESTERN PACIFIC OCEAN
Authors: HU ZHAOHUI , LIU PINGSHENG , LIU SHIJIE , YAO YING , FENG GUOHUA
Published: November 2004

Marine aerosol from the western Pacific were collected by two types of samplers during a cruise from Nanhai of China through the west of Philippines to the equatorial and to the north-eastern of Solomon Archipelago. Collected samples were analyzed by PIXE. The data gave aerosol characteristics over the western Pacific, including concentrations, enrichmens and mass size distributions of detected elements, and possible sources of these elements were specially researched. The result indicates that Al, Si and Fe were associated with soil particles; Cl, Br, K, Ca and S showed characteristics of the sea-salt origin; and Cu, Zn and Pb were due to pollution from long-range transport of continental aerosol. We have also made comparison with data obtained in earlier studies over other regions of the Pacific.
ANALYSIS OF CONTAMINATING ELEMENTS IN TREE RINGS IN SANTIAGO, CHILE
Authors: ROMO-KRÖGER C.M. , AVILA M.J. , EATON L.C. , LÓPEZ L.A.
Published: November 2004

Using the 22” isochronous cyclotron at the University of Chile, we have performed PIXE analyses on a group of samples collected from trees of metropolitan parks in Santiago. Dendrochronology was performed on each sample, which was then sectioned for the PIXE and other analyses, neutron activation and electro-chemistry. Available samples are trunk sections or cores obtained by the use of a 4.0 mm stainless steel incremental corer. We took three cores from each tree with permission of the municipalities. For the PIXE we use infinitely thick targets, as wood slabs taken along the trunk radius, and thin targets obtained by acid digestion of wood pieces and deposition on Kapton foils. Self supporting thick targets were placed directly in the PIXE chamber in a position so as to allow the irradiation of a specific annual ring. Potassium and Calcium appear as the most abundant elements in wood Other elements such as S, Cu, Zn, As, Br and Pb were detected in amounts above the natural background in wood, and can be attributed to environmental contamination. The K/Ca ratios appear to be different for each species of tree, and seem to be related to the physico-chemical properties of wood. Preliminary results show important amounts of As and Cu (supposedly from mining origin) with increasing presence in the recent years. Pb and Zn (supposedly from vehicle origin) are also higher in recent years.
PIXE AND RECEPTOR MODEL APPLIED TO ATMOSPHERIC AEROSOL SOURCE APPORTIONMENT
Authors: Zhu Guang-hua
Published: November 2004

Atmospheric aerosol samples were collected using an 8-stage cascade impactor or an automatic time sequence step sampler at Mount Qomolangma and Beijing. Element concentrations were analyzed by particle induced x-ray emission (PIXE) technique. Then the data were analyzed by the absolute principal factor analysis (APFA) to evaluate the principal components and the percent variance explained by them. As a result, it shows that the PIXE analysis combing with statistical method can effectively resolve the aerosol components in urban area and distinguish between local and remote area aerosol components in the area far from the pollution sources.
SOME CHARACTERISTICS OF THE AEROSOL IN BEIJING
Authors: WANG XINFU , ZHU GUANGHUA
Published: November 2004

Aerosol samples were collected by using a 8 or 10-stage cascade impactor and a streaker sampler in Beijing area during the period from 1986 to 1991. Elemental analysis of each particle size fraction of the samples collected was carried out by particle induced X-ray emission (PIXE) at a 2×1.7 MV tandem accelerator. From the measured results of the concentrations for the 18 elements we obain the average value of the mass concentrations (total sum of these elemental concentrations) of the aerosol to be 42 mg/m 3 in urban districts of Beijing and some characteristics of the aerosol in Beijing are also discussed.
APPLICATION OF PIXE TECHNIQUE TO DETERMINATION OF TRACE ELEMENTS IN DIET AND COMPARISON WITH NAA AND ICP-AES
Authors: Yukawa Masae , Watanabe Yoshito , Nishimura Yoshikazu , Kimura Mieko
Published: November 2004

PIXE technique was applied to measurement of trace elements in total diet samples collected in Japan for estimation of their daily dietary intake. Results of PIXE analysis were compared with INAA Concentration of Cl, K, Mn and Zn by PIXE analysis well agreed with the results from NAA, while Ca, Fe and Cu showed different results between these two techniques. Preliminary data of elemental concentrations in Mate-cha, a kind of tea popular in South America, determined by ICP-AES indicated a little higher concentration of Cu than that by PIXE and much lower value than that by INAA For Zn. concentrations by PIXE and ICP well agreed to each other, while INAA gave much lower value. Japanese internal radiation doses by 137 Cs and 90 Sr were estimated to be 2.30µSv/year and 1.27µSv/year respectively as the effective dose equivalents using the daily intake data obtained for K and Ca.
QUANTITATIVE ANALYSIS OF BIOLOGICAL SAMPLES USING SYNCHROTRON RADIATION MICROPROBE
Authors: XU QING , SHAO HANRU , QIAN QINFONG , LIU PENG , LIU NIANQING
Published: November 2004

A quantitative analysis method of the trace elements in biological specimens using the synchrotron radiation microprobe is described. The synchrotron radiation X-ray fluorescence microprobe system is calibrated by the standard sample specially prepared for the microprobe analysis. The mass thickness of each measured point is determined by measuring Compton scattering intensity in 17–20 keV from the sample. In this way, concentration of the trace elements in samples can be measured correctly. The measured values of the biological standard reference material NBS-SRM-1577a are in good agreement with the certified values. The longitudinal concentration variations of some trace element in a single hair of pregnant women have been measured by this method
A NEW METHOD OF MULTI-ELEMENT ANALYSIS WITH POSITION SENSITIVE SPECTROMETER FOR RARE-EARTH-ELEMENT SAMPLE
Authors: LIU PENG , XU QING , SHAO HANRU
Published: November 2004

By using position-sensitive spectrometer the rare-earth-element sample could be analyzed conveniently. This method of measurement was described and some of its features were discussed in this paper.
AN OPEN EXPERIMENT OF PIXE ANALYSIS
Authors: MATSUYAMA S. , ISHII K. , YAMAZAKI H. , IWASAKI S. , MUROZONO K. , INOUE J. , TANAKA M. , ORIHARA H.
Published: November 2004

PIXE analysis opened to public was conducted as an event of an open school of the Atomic Energy Society of Japan, which is semiannually held in order to arouse public interest in the science of radiation and nuclear power. The experiment was performed using a vertical in air (Via) PIXE system at Tohoku university. Forty-seven people participated and enjoyed this open experiment.
PIXE ANALYSIS OF HEAD BONE
Authors: FUTATSUGAWA S. , HATAKEYAMA S. , SAITOU Y. , SERA K. , ADACHI A.
Published: November 2004

An unknown bone was analyzed by PIXE at the Nishina Memorial Cyclotron Center. The head bone had a normal area, a rotted area and the green colored area on its surface. An extremely small amount of powder was cut from each area. Each powder sample was fixed on a backing film with a small amount of collodion liquid. The concentrations of sodium and chlorine are relatively high compared with that of other elements in all powder samples. The concentrations of copper and zinc in the colored area are higher than that in the other areas. The analytical results by PIXE agreed with other investigated results. We describe one of the applications of PIXE to archaeology field.
FUNDAMENTAL INVESTIGATION ON TRACE ELEMENT ANALYSIS IN WOOD SAMPLES USING THE PIXE METHOD
Authors: AOKI TORU , KATAYAMA YUKIO , YOSHIDA KOHJI
Published: November 2004

A fundamental investigation of the PIXE method applied to the measurement of trace elements in wood samples, is described in this work. Yields of the elements added to a sugi (Cryptomeria japonica D. Don) specimen, were almost constant after they were bombarded with radiation up to 600µC. Yields of certain elements in the early wood and the late wood in the same annual ring of the sugi were compared. The yields of Ca, Cu, Zn, Rb and Sr in the late wood were the same or slightly higher than those in the early wood, but Fe and Mn yields in the late wood were higher than those in the early wood. The concentration profiles of Ca, Mn, Fe, Zn and Sr along a radial direction in the stem of the sugi were also determined.
PIXE ANALYSIS OF TRACE ELEMENTS IN SQUID STATOLITHS: COMPARISON BETWEEN OMMASTREPHIDAE AND LOLIGINIDAE
Authors: IKEDA Y. , ARAI N. , SAKAMOTO W. , NATEEWATHANA A. , MURAYAMA T. , YATSU A. , YOSHIDA K.
Published: November 2004

Trace elements in the squid statoliths were analyzed by PIXE for following seven species distributing at offshore and inshore waters: Family Ommastrephidae, Ommastrephes bartrami, Todarodes pacificus; family Loliginidae, Loligo bleekeri, L. duvaucelii, L. chinensis, L. edulis and Sepioteuthis lessoniana. Statoliths of all seven species contained manganese, iron, capper, zinc and relatively high amount of strontium. Statoliths Sr concentration, an possible index for thermal history of the animal’s habitat, were the highest in O. bartrami that spends their entire life time at pelagic water, and secondly highest in T. pacificus living at the pelagic as well as the coastal waters. On the other hand, statoliths Sr concentration was relatively low in the five species of Loliginidae living at coastal waters, with following order: L. edulis >S. lessoniana >L. duvaucelii >L. bleekeri >L. chinensis. These observations may indicate that quantity of the statoliths trace elements are species specific in squids, thus would be a possible “key” to reconsidering about taxonomy and distribution in squid.
MICRO-PIXE RECONNAISSANCE OF ALLANITE AS A PRASEODYMIUM SOURCE
Authors: MURAO SATOSHI , NAKASHIMA KAZUO , H SIE SOEY
Published: November 2004

Praseodymium is one of the most important pigment materials for high-quality china and ceramics but its source minerals are not well known to geologists. Allanite, one of the REE-bearing minerals in nature, has a large coordination polyhedra for cations and favors the larger LREE ions such as praseodymium than other REE-bearing minerals that favor the smaller HREE. We have tested some allanite crystals by CSIRO’s micro-PIXE to examine its possibility as a praseodymium source. Our result showed that allanite incorporates praseodymium at the order of 4000 to 5000 ppm and thus it is one of the good host of this element. We conclude that micro-PIXE is a viable quantitative tool for determining REE in allanite and other conventional REE sources in spite of the relatively poor minimum detection limit compared to that for other elements.
PLANAR TILINGS AS FRACTAL CONFIGURATIONS
Authors: PIACQUADIO LOSADA M.
Published: November 2004

Let Ω be a bounded planar domain, its boundary ∂Ω a closed curve of fractal dimension df ∈ (1, 2). In Piacquadio [1992] we approximated such ∂Ω by closed ∂Ωp curves, p ∈ ℕ, p → ∞. In this paper we deal with the pathological case df = 2 — i.e. the so-called "plane filling" ∂Ω. Such ∂Ω are both frequent and important in physics. We study a variety of planar tilings, corresponding to crystalline and quasicrystalline configurations, by means of approximating curves ∂Ωp to different plane filling ∂Ω. We give some applications to elliptic partial differential equations (P.D.E.) and to the study of crystalline and quasicrystalline matter structure.
ON A CLASS OF FRACTIONAL ITERATES
Authors: NARAYANINSAMY TONY
Published: November 2004

We construct solutions g of the functional equation gm-1 (g(x)) = f(x), m ∈ N*, m > 1, f is a given map. The set of definition of f is strictly included in the set of definitions of these solutions.
GENERATION OF COLLECTIVE-ACTIVITY STRUCTURES IN A HOMOGENEOUS NEURON-LIKE MEDIUM I: BIFURCATION ANALYSIS OF STATIC STRUCTURES
Authors: PELINOVSKY DMITRY E. , YAKHNO VLADIMIR G.
Published: November 2004

A general model of the neuron-like medium with a selfconsistent excitation threshold is considered. The necessary and sufficient conditions of stability of static collective-activity structures in this model are found. The structure bifurcations which are possible by additional inertial inhibition introduced by a local excitation threshold are analyzed using a linear approach.
HOW TO DETERMINE THE REDUNDANCY OF NOISY CHAOTIC TIME SERIES
Authors: WIENHOLT WILLFRIED , SENDHOFF BERNHARD
Published: November 2004

The mutual information and the redundancy are used in the time series analysis as tools to determine the best possible time-lag for successful phase space reconstruction. The known methods exhibit difficulties and inaccuracy when applied to noisy and small data sets. In this paper, we will introduce two methods to make a more reliable determination of the redundancy possible. Firstly, we will modify the Θ-function used in the correlation intergrals and, secondly, we will use the "Neural Gas" algorithm to calculate reference vectors and local radii, which enter the redundancy calculations. A clear differentiation between the redundancy and the mutual information on information theoretical background provides the path along which the new methods can be introduced and applied to the Mackey–Glass and Lorenz systems.
ON LOCAL CONTROL OF CHAOS: THE NEIGHBOURHOOD SIZE
Authors: PASKOTA MIRKO
Published: November 2004

In this paper, conditions for effective local control of nonlinear, chaotic dynamical systems are analyzed. The aim is to determine the size of a neighbourhood of a fixed point in which the system remains stable when subjected to a linear control law. The stability margins are obtained using ideas from functional analysis, and ways of implementing the obtained results in practice are proposed. An implementation of obtained conditions is illustrated on a real application.
SOFTENING THE NONLINEARITY IN CHUA'S CIRCUIT
Authors: LIPTON J. M. , DABKE K. P.
Published: November 2004

The effects of both hard and soft nonlinearities are examined in the frequency domain. Softening the hard nonlinearity in Chua's diode has a similar effect to low pass filtering or reducing the level of high frequency noise components.
CHAOS IN THE NETWORKS: SIMULATION OF A BIOLOGICAL LEARNING PROCESS BY TIME EVOLUTION IN AN UNSUPERVISED NEURAL NETWORK
Authors: PANDIN MARIO , DIDONÉ GIUSEPPE
Published: November 2004

This paper shows an abstract computational system with interesting properties concerning the emulation of a learning process by time evolution, using an unsupervised neural net, called "Autoreflexive Monoconnected Neural Net". We show how this particular unsupervised neural network can be used to simulate chaotic activities related to learning processes, which have been observed in many physiological experiments. We demonstrate how this chaos activity is distributed inside the net system, leading to the generation of synchronous oscillations with different amplitudes and frequencies, consistent with the coherent and rhythmic activity of large numbers of neurons in the brain. These findings suggest that such local oscillations are important for information processing. The results suggest that the learning process is composed of different phases, which are characterized by interspersed chaotic and periodic behaviors. Small perturbations by changing net parameters can be used to control chaotic activity, and to stabilize unstable periodic orbits, offering a new approach for the learning process control.
MONOTONE SYNCHRONIZATION OF CHAOS
Authors: KAPITANIAK TOMASZ , SEKIETA MAREK , OGORZALEK MACIEJ
Published: November 2004

In this letter we show that the monotone synchronization is possible for chaotic systems and can be easily obtained using the method of continuous chaos control. We also discuss possible applications of this type of synchronization for secure communications.
CHARACTERIZATION OF THE MEMBRANE THEORY OF A CLAMPED SHELL: THE HYPERBOLIC CASE
Authors: PIILA JYRKI
Published: November 2004

We study the membrane-dominated deformation state of a thin shell, the midsurface of which is located on a hyperbolic surface of revolution whose boundary is a curvilinear polygon. The shell is loaded by a surface tractions on both faces, and clamped all along the edge. Proceeding from the classical shell model of Koiter–Sanders–Novozhilov, an asymptotic membrane theory model is constructed to describe the limit behavior of the shell as the thickness tends to zero. The mathematical properties of the membrane theory are analyzed and the convergence rate estimate between the two models is proven.
CONTROL OF MANUFACTURING SYSTEMS WITH RE-ENTRANT LINES
Authors: NIKITIN S.
Published: November 2004

In this paper a mathematical framework of the control theory of manufacturing systems is proposed. All possible plant structures are classified. A mathematical dynamical model which describes the dynamics of a plant is developed. With the help of this model it is shown how the real time control policy which guarantees the stable work of the plant with the quasi-maximal production rate can be designed.
FAST OSCILLATING MIGRATIONS IN A PREDATOR-PREY MODEL
Authors: POGGIALE JEAN-CHRISTOPHE , AUGER PIERRE
Published: November 2004

The aim of this paper is to give a method which permits us to describe how individual properties can emerge at the population level, in population dynamics. We consider interacting populations. In order to take into account the spatial or behavioral heterogeneity, we subdivide each population into subpopulations. A given subpopulation corresponds to those individuals having the same behavior and who are in a homogeneous environment. Furthermore, we assume that the migration process is faster than the growth and interaction processes. Therefore, we must study models with many variables coupled together into large scaled differential systems. Firstly, our method permits us to reduce these complex systems into simpler ones, which will be called reduced systems. Secondly, these reduced systems give the population dynamics and contains informations about individuals' behavior, that is we can explain how individual dynamics emerge in the population dynamics. We already investigated the case where the fast dynamics reach an equilibrium in previous works. In this paper, we are interested in those models where the fast dynamics oscillates because it is ecologically relevant.
MATHEMATICAL MODELS OF CHEMICALLY REACTING GASES
Authors: RONDONI L.
Published: November 2004

Modeling and analysis of models of complex chemical reactions constitute wide branches of research in chemistry, physics and mathematics. Here a model is proposed which is amenable to rigorous mathematical study, which makes clear the dynamics of the systems described by such a model. In particular, only combinations of chemical reactions which preserve the number of particles, and which have equal forward and backward reaction rates are allowed. Reactions which do not satisfy such requirements can be considered, provided they are suitably modified. Also, it is required that the densities of the chemicals in the reactions be low, so that the applicability of the theory is restricted to mixtures of gases.
TRANSMISSION LOSS IN THE FAR FIELD OVER A SEABED WITH RIGID SUBSTRATE ASSUMING THE BIOT SEDIMENT MODEL
Authors: BUCHANAN JAMES L. , GILBERT ROBERT P.
Published: November 2004

A system of differential equations is derived from Biot's constitutive and motion equations for a poroelastic material. The seabed is modeled as a poroelastic layer over a rigid substrate. A residue expansion for pressure in the far field is found in the case of constant parameters. The model's prediction for transmission loss is examined for five different types of sediments.
A METHOD FOR THE TREATMENT OF A SLOPING SEA BOTTOM IN THE PARABOLIC APPROXIMATION
Authors: PAPADAKIS J. S. , PELLONI B.
Published: November 2004

The impedance boundary condition for the parabolic approximation is derived in the case of a sea bottom profile sloping at a constant angle, as a non-local boundary condition imposed exactly at the interface. This condition is integrated into the IFD code for the numerical computation of the pressure field and implemented to test its accuracy in some benchmark cases, for which the backscattered field is negligible.

It is shown that by avoiding the sloping interface, the results obtained are closer to the benchmark results given by normal mode codes solving the full Helmholtz equation, such as the 2-way COUPLE code, than those of the standard IFD or other 1-way codes, at least for problems that do not have significant backscattering effects.
Ionic mechanism for contractile response to hyposmotic challenge in canine basilar arteries
Authors: Yano Shunsuke , Ishikawa Tomohisa , Tsuda Hidetaka , Obara Kazuo , Nakayama Koichi
Published: November 2004

A hyposmotic challenge elicited contraction of isolated canine basilar arteries. The contractile response was nearly abolished by the removal of extracellular Ca2+ and by the voltage-dependent Ca2+ channel (VDCC) blocker nicardipine, but it was unaffected by thapsigargin, which depletes intracellular Ca2+ stores. The contraction was also inhibited by Gd3+ and ruthenium red, cation channel blockers, and Cl− channel blockers DIDS and niflumic acid. The reduction of extracellular Cl− concentrations enhanced the hypotonically induced contraction. Patch-clamp analysis showed that a hyposmotic challenge activated outwardly rectifying whole cell currents in isolated canine basilar artery myocytes. The reversal potential of the current was shifted toward negative potentials by reductions in intracellular Cl− concentration, indicating that the currents were carried by Cl−. Moreover, the currents were abolished by 10 mM BAPTA in the pipette solution and by the removal of extracellular Ca2+. Taken together, these results suggest that a hyposmotic challenge activates cation channels, which presumably cause Ca2+ influx, thereby activating Ca2+-activated Cl− channels. The subsequent membrane depolarization is likely to increase Ca2+ influx through VDCC and elicit contraction.
Linked mechanical and biological aspects of remodeling in mouse pulmonary arteries with hypoxia-induced hypertension
Authors: Kobs Ryan W. , Muvarak Nidal E. , Eickhoff Jens C. , Chesler Naomi C.
Published: November 2004

Right heart failure due to pulmonary hypertension causes significant morbidity and mortality. To study the linked vascular mechanical and biological changes that are induced by pulmonary hypertension, we mechanically tested isolated left main pulmonary arteries from mice exposed to chronic hypobaric hypoxia and performed histological assays on contralateral vessels. In isolated vessel tests, hypoxic vessels stretched less in response to pressure than controls at all pressure levels. Given the short length and large diameter of the pulmonary artery, the tangent Young's modulus could not be measured; instead, an effective elastic modulus was calculated that increased significantly with hypoxia [(280 kPa (SD 53) and 296 kPa (SD 50) for 10 and 15 days, respectively, vs. 222 kPa (SD 35) for control; P < 0.02)]. Hypoxic vessels also had higher damping coefficients [(0.063 (SD 0.017) and 0.054 (SD 0.014) for 10 and 15 days, respectively, vs. 0.033 (SD 0.016) for control; P < 0.002)], indicating increased energy dissipation. The increased stiffness with hypoxia correlated with an increase in collagen thickness (percent collagen multiplied by wall thickness) as well as the sum of elastin and collagen thicknesses measured histologically in the artery wall. These results highlight the mechanobiological changes in the pulmonary vasculature that occur in response to hypoxia-induced pulmonary hypertension. Furthermore, they demonstrate significant vascular mechanical and biological changes that would increase pulmonary vascular impedance, leading to right heart failure.
Neuroendocrinology of nutritional infertility
Authors: Wade George N. , Jones Juli E.
Published: November 2004

Natural selection has linked the physiological controls of energy balance and fertility such that reproduction is deferred during lean times, particularly in female mammals. In this way, an energetically costly process is confined to periods when sufficient food is available to support pregnancy and lactation. Even in the face of abundance, nutritional infertility ensues if energy intake fails to keep pace with expenditure. A working hypothesis is proposed in which any activity or condition that limits the availability of oxidizable fuels (e.g., undereating, excessive energy expenditure, diabetes mellitus) can inhibit both gonadotropin-releasing hormone (GnRH)/luteinizing hormone secretion and female copulatory behaviors. Decreases in metabolic fuel availability appear to be detected by cells in the caudal hindbrain. Hindbrain neurons producing neuropeptide Y (NPY) and catecholamines (CA) then project to the forebrain where they contact GnRH neurons both directly and also indirectly via corticotropin-releasing hormone (CRH) neurons to inhibit GnRH secretion. In the case of estrous behavior, the best available evidence suggests that the inhibitory NPY/CA system acts primarily via CRH or urocortin projections to various forebrain loci that control sexual receptivity. Disruption of these signaling processes allows normal reproduction to proceed in the face of energetic deficits, indicating that the circuitry responds to energy deficits and that no signal is necessary to indicate that there is an adequate energy supply. While there is a large body of evidence to support this hypothesis, the data do not exclude nutritional inhibition of reproduction by other pathways and processes, and the full story will undoubtedly be more complex than this.
Intramuscular pressure-induced inhibition of cardiac contraction: implications for cardiac-locomotor synchronization
Authors: Niizeki Kyuichi
Published: November 2004

The synchronization of cardiac and locomotor rhythms has been suggested to enhance the efficiency of arterial delivery to active muscles during rhythmic exercise, but direct evidence showing such a functional role has not been provided. In this study, we tested the hypothesis that the heartbeat is coupled with intramuscular pressure (IMP) changes so as to time the delivery of blood through peripheral tissues when the IMP is lower. To this end, we developed a computer-controlled, dynamic, thigh cuff occlusion device that enables bilateral thigh cuffs to repeatedly inflate and deflate, one side after the other, to simulate rhythmic IMP changes during bipedal locomotion. Nine healthy subjects were examined, and three different occlusion pressures (50, 80, and 120 mmHg) were applied separately to the thigh cuffs of normal subjects while they were sitting. Alternate occlusions of the bilateral thigh cuffs administered at the frequency of the mean heart rate produced significant phase synchronization between the cardiac and cuff-occlusion rhythms when 120 mmHg pressure was applied. However, synchronization was not observed when the occlusion pressure was 50 or 80 mmHg. During synchronization, heartbeats were most likely to occur in phases that did not include overlap between the peak arterial flow velocity in the thigh and elevated cuff pressure. We believe that phase synchronization occurs so that the cardiac cycle is timed to deliver blood through the lower legs when IMP is not maximal. If this can be extrapolated to natural locomotion, synchronization between cardiac and locomotor activities may be associated with the improved perfusion of exercising muscles.