bluuebunny/crossref_metadata_2025 huggingface dataset:
Emergence of colistin resistance and characterization of antimicrobial resistance and virulence factors ofAeromonas hydrophila,Salmonellaspp., andVibrio choleraeisolated from hybrid red tilapia cage culture
Authors: Thaotumpitak Varangkana , Sripradite Jarukorn , Atwill Edward R. , Jeamsripong Saharuetai
Published: February 2023

Background

Tilapia is a primary aquaculture fish in Thailand, but little is known about the occurrence of antimicrobial resistance (AMR) inAeromonas hydrophila,Salmonellaspp., andVibrio choleraecolonizing healthy tilapia intended for human consumption and the co-occurrence of these AMR bacteria in the cultivation water.

Methods

This study determined the phenotype and genotype of AMR, extended-spectrumβ-lactamase (ESBL) production, and virulence factors ofA. hydrophila,Salmonellaspp., andV. choleraeisolated from hybrid red tilapia and cultivation water in Thailand. Standard culture methods such as USFDA’s BAM or ISO procedures were used for the original isolation, with all isolates confirmed by biochemical tests, serotyping, and species-specific gene detection based on PCR.

Results

A total of 278 isolates consisting of 15A. hydrophila, 188Salmonellaspp., and 75V. choleraeisolates were retrieved from a previous study. All isolates ofA. hydrophilaandSalmonellaisolates were resistance to at least one antimicrobial, with 26.7% and 72.3% of the isolates being multidrug resistant (MDR), respectively. AllA. hydrophilaisolates were resistant to ampicillin (100%), followed by oxytetracycline (26.7%), tetracycline (26.7%), trimethoprim (26.7%), and oxolinic acid (20.0%). The predominant resistance genes inA. hydrophilaweremcr-3(20.0%), followed by 13.3% of isolates havingfloR,qnrS,sul1,sul2, anddfrA1. Salmonellaisolates also exhibited a high prevalence of resistance to ampicillin (79.3%), oxolinic acid (75.5%), oxytetracycline (71.8%), chloramphenicol (62.8%), and florfenicol (55.3%). The most common resistance genes in theseSalmonellaisolates wereqnrS(65.4%),tetA(64.9%),blaTEM(63.8%), andfloR(55.9%). AllV. choleraeisolates were susceptible to all antimicrobials tested, while the most common resistance gene wassul1(12.0%). One isolate ofA. hydrophilawas positive forint1, while all isolates ofSalmonellaandV. choleraeisolates were negative for integrons andintSXT. None of the bacterial isolates in this study were producing ESBL. The occurrence ofmcr-3(20.0%) in these isolates from tilapia aquaculture may signify a serious occupational and consumer health risk given that colistin is a last resort antimicrobial for treatment of Gram-negative bacteria infections.

Conclusions

Findings from this study on AMR bacteria in hybrid red tilapia suggest that aquaculture as practiced in Thailand can select for ubiquitous AMR pathogens, mobile genetic elements, and an emerging reservoir ofmcrand colistin-resistant bacteria. Resistant and pathogenic bacteria, such as resistance to ampicillin and tetracycline, or MDRSalmonellacirculating in aquaculture, together highlight the public health concerns and foodborne risks of zoonotic pathogens in humans from cultured freshwater fish.
A glass you can drink from
Authors: Lewis Thomas
Published: February 2023

This paper explores a psychobiological model of psychotherapy. An emotion-centered history of the evolution of the brain is followed by a review of the basic psychobiology of emotion, attachment, and memory. Because human beings are social mammals, we regulate each orher's physiology and brain development through social contact. This process is likely to be causative not only in the generation of emotional pathology, but also in the therapeutic change that takes place in a successful psychotherapy. As neuroscience elucidates the nature of the brain, insight appears less important to emotional learning than the gradual alteration of intuition through the operation of implicit memory.
My closest friend
Authors: Alldred-Lugton Susan
Published: February 2023

This paper discusses our fundamental need to have an intimate ally, a close friend in the form of an internalised, loving and loveable object. It will explore the origins of loving feelings as they relate to the infant's first love affair with mother and how this translates into relationships in later life. It will be argued that many patients in therapy will be needing to get in touch with the preverbal. It will be suggested that training in an infant observation is useful in gaining the skills to treat the infantile aspects of such patients. Projective identification and countertransference will be discussed, as well as the process of breaking through the false self to recognise the deep suffering that the baby and the small child faced as a result of being raised by a narcissistic parent. It will be suggested that psychotherapists may unconsciously be searching for their lost maternal objects in their patients, hence the need for the therapist to have had sufficient therapy in order to be attuned, but separate.
The feminine
Authors: Roldan Felisa
Published: February 2023

This paper attempts to introduce a concept very rarely, if at all, mentioned in psychotherapy: "the feminine". It proposes that psychotherapy would benefit from better understanding masculine and feminine principles, particularly the latter one, in view of the neglect they have suffered over the years. Finally, it also suggests that psychotherapists could collude with an over-masculine culture if not careful. Awareness comes primarily from a personal encounter with the feminine. Jungian and Post-Jungian psychoanalysts add some light to this issue.
The self and Janet Frame
Authors: Griffiths Sue
Published: February 2023

The theory that psychological trauma restricts or inhibits the development of 'self', or the stream of consciousness, sparked my thinking about how these ideas link to creativity. Evidence of a flourishing stream of consciousness is apparent in many literary greats who have experienced emotional difficulties. Among them is Janet Frame, who writes poetically about the landscape of the mind. Within the framework of the psychoanalytic structure of self psychology this paper examines Frame's life, her 'self' development, and the healing function of her writing.
Silence in the conversation
Authors: Moore Anna
Published: February 2023

This paper explores the difficulties of working with clients who struggle to use words in the therapeutic context. How do we work with these difficult clients? I focus particularly on those clients whose organizing principles predispose them to using silence as a means of holding themselves together or who persist in using silence in dissociated ways, often when traumatic memory gets triggered. I present a clinical example, a "silent" client, as a way of developing the sense and feeling of silence in therapy and I explore how we can understand such "silent" clients. Concepts such as dissociation (our clients' and our own), intersubjective and interpersonal listening, and poetic and nonlinear conversation will be considered. Drawing particularly on Bromberg's and Meares' work I will then look at what the therapeutic task is with these clients.
The Investment Performance of Low-Grade Bond Funds
Authors: Cornell Bradford , Green Kevin
Published: July 2002

This study extends the literature on the pricing of low-grade bonds by examin- ing the performance of low-grade bond funds. The findings reveal that over the long run low-grade bond fund returns are approximately equal to the returns provided by an index of high-grade bonds. The relative risks of high and low-grade bonds are more difficult to assess. Because of their shorter durations, low-grade bonds are less sensitive to movements in interest rates than high-grade bonds. On the other hand, low-grade bonds are much more sensitive to changes in stock prices than high-grade bonds. When adjusted for risk using a simple two-factor model, the returns on low- grade bond funds are not statistically different from the returns on high-grade bonds. The Journal ofFinance, Vol. XLVI, No. 1 (March 1991), pp. 28-48. (Reprinted with permission of The Journal of Finance.)
Chemical synthesis and characterization of maurocalcine, a scorpion toxin that activates Ca2+ release channel/ryanodine receptors
Authors: Fajloun Z. , Kharrat R. , Chen L. , Lecomte C. , Di Luccio E. , Bichet D. , El Ayeb M. , Rochat H. , Allen P.D. , Pessah I.N. , De Waard M. , Sabatier J.M.
Published: July 2002

Maurocalcine is a novel toxin isolated from the venom of the chactid scorpion Scorpio maurus palmatus. It is a 33‐mer basic peptide cross‐linked by three disulfide bridges, which shares 82% sequence identity with imperatoxin A, a scorpion toxin from the venom of Pandinus imperator. Maurocalcine is peculiar in terms of structural properties since it does not possess any consensus motif reported so far in other scorpion toxins. Due to its low concentration in venom (0.5% of the proteins), maurocalcine was chemically synthesized by means of an optimized solid‐phase method, and purified after folding/oxidation by using both C18 reversed‐phase and ion exchange high‐pressure liquid chromatographies. The synthetic product (sMCa) was characterized. The half‐cystine pairing pattern of sMCa was identified by enzyme‐based cleavage and Edman sequencing. The pairings were Cys3‐Cys17, Cys10‐Cys21, and Cys16‐Cys32. In vivo, the sMCa was lethal to mice following intracerebroventricular inoculation (LD50, 20 μg/mouse). In vitro, electrophysiological experiments based on recordings of single channels incorporated into planar lipid bilayers showed that sMCa potently and reversibly modifies channel gating behavior of the type 1 ryanodine receptor by inducing prominent subconductance behavior.
Synthesis of Water‐Soluble Retinol Derivatives by Enzymatic Method
Authors: Maugard Thierry , Rejasse Barbara , Legoy Marie Dominique
Published: July 2002

Retinoids (vitamin A and derivatives) are of great commercial potential in cosmetics and pharmaceuticals such as skin care products. However, the clinical effectiveness of these retinoids is limited by skin irritation, water insolubility, and except for retinyl‐esters, extreme instability. In this paper, an enzymatic method for preparing water‐soluble retinol derivatives catalyzed by immobilized lipase is described. The synthesis is based on a unique strategy of two‐step enzymatic acylation. Among the different synthesized compounds, the most water‐soluble are the disaccharide derivatives such as saccharose retinyl adipate (nonionic water‐soluble retinol derivative) and the sodium salt of retinyl diacids such as retinyl succinate sodium salt (ionic water‐soluble retinol derivative).
Enzymes, Energy, and the Environment: A Strategic Perspective on the U.S. Department of Energy's Research and Development Activities for Bioethanol
Authors: Sheehan John , Himmel Michael
Published: July 2002

For well over one hundred years, researchers around the world have pursued ways to make ethanol from biomass such as wood, grasses, and waste materials. To distinguish it from ethanol made from starch and sugars in traditional agricultural crops, we refer to ethanol made from biomass as “bioethanol.” The effort to develop bioethanol technology gained significant momentum in the late 1970s as a result of the energy crises that occurred in that decade. This article briefly reviews the broader history of bioethanol technology development. With this as a background, we focus our attention on the strategic thinking behind the U.S. Department of Energy's Bioethanol Program, which envisions remarkable advances in cellulase enzyme research and as the basis for significant future process cost reductions.
An individual with a healthy phenotype in spite of a pathogenic LDL receptor mutation (C240F)
Authors: Ekström Ulf , Abrahamson Magnus , Florén Claes‐Henrik , Tollig Henrik , Wettrell Göran , Nilsson Gerd , Sun Xi‐Ming , Soutar Anne K , Nilsson‐Ehle Peter
Published: July 2002

Familial hypercholesterolemia (FH) is caused by a defect in the function of the low density lipoprotein (LDL) receptor and inherited in an autosomal, codominant way. In this study we present a 13‐year‐old girl, compound heterozygote for the LDL receptor mutations C240F and Y167X. Fibroblasts from the patient showed very low cholesterol esterification rate, LDL uptake, and degradation compared to normal fibroblasts (≪2%, 8%, and ≪2%, respectively). The C240F mutant was expressed in LDL receptor deficient CHOldlA7 cells. Analysis of cell extracts by immunoblotting demonstrated delayed processing of the mutated LDL receptor, which was accumulated as a precursor protein of normal size. A high molecular weight form of the receptor was also detectable in these cells, which probably reflects cross‐linking through the unpaired cysteine residue in the binding domain. Cells expressing the C240F mutant protein were unable to mediate uptake and degradation of LDL. The two siblings of the index case also carried the C240F mutation, but surprisingly one of them (a 17‐year‐old brother) showed no signs of hypercholesterolemia. This observation is consistent with the view that there may be cholesterol lowering mechanisms that can be activated, perhaps by mutations in known or hitherto unknown genes.
The active site of drosomycin, a small insect antifungal protein, delineated by comparison with the modeled structure of Rs‐AFP2, a plant antifungal protein
Authors: Landon C. , Vovelle F. , Sodano P. , Pajon A.
Published: July 2002

Abstract: Drosomycin is the first strictly antifungal protein isolated from an insect (Drosophila melanogaster). The solution structure of this 44‐residue protein has been reported previously. It involves a three‐stranded β‐sheet and an α‐helix, the protein global fold being maintained by four disulfide bridges. Rs‐AFP2 is a plant antifungal protein exhibiting 41% sequence similarity with drosomycin. Mutational analysis of Rs‐AFP2 showed the importance of some residues in the antifungal activity of the protein against the fungus target. In order to determine the structural features responsible for antifungal activity in both drosomycin and Rs‐AFP2, we modeled the three‐dimensional structure of Rs‐AFP2, and of other antifungal proteins, using the solution structure of drosomycin as a template. Structure analysis of drosomycin and Rs‐AFP2, and comparisons with the other modeled antifungal structures, revealed that the two proteins shared a hydrophobic cluster located at the protein surface in which a lysine residue is embedded. Based on these close structural similarities and the experimental data available for Rs‐AFP2 mutants, an antifungal active site of the insect protein is proposed.
Increased eosinophil cationic protein levels in bronchoalveolar lavage from wheezy infants
Authors: Azevedo Inês , De Blic Jacques , Vargaftig B. Boris , Bachelet Marie , Scheinmann Pierre
Published: July 2002

Although studies examining the serum suggest a role for eosinophils in wheezing episodes in infants and toddlers, the presence of a chronic eosinophilic inflammation within their airways remains to be demonstrated. In this study we investigated whether eosinophil cationic protein (ECP) levels are increased in BAL fluid (BALF) from infants and toddlers with recurrent wheezing episodes, during an asymptomatic period. The levels of ECP in BALF were quantitated by radioimmunoassay in 61 children (36 with severe recurrent episodes of wheezing and 25 who were non‐wheezy), aged 6–36 months, in whom flexible bronchoscopy was clinically indicated. BALF eosinophil counts were ≤ 1% in all patients and did not differ in wheezers, compared to non‐wheezers. In contrast, ECP levels in BALF were ≥ 2.2 µg/l in 18 of 36 (50%) wheezy infants but in only three of 25 (12%) control infants (p < 0.01). Neutrophil counts were significantly higher in the wheezer group than in the non‐wheezer group (8.1 × 103cells/ml vs. 3.0 × 103cells/ml). ECP levels in the BALF were not correlated with the absolute number of eosinophils (r = 0.03; p = 0.8) but were correlated with the absolute number of neutrophils (r = 0.54; p = 0.001). There was no association between high ECP levels in BALF and the atopic status of the wheezers. In conclusion, ECP levels are increased in BALF from young children with recurrent wheezing episodes, even during relatively quiescent periods, suggesting a chronic increased cell activation in the lower airways.
Molecular cloning and characterization of a type III glutathione S‐transferase from cell suspension cultures of opium poppy treated with a fungal elicitor
Authors: Yu Min , Facchini Peter J.
Published: July 2002

Glutathione S‐transferases (GSTs) catalyze the conjugation of electrophilic compounds to glutathione (GSH), and are involved in the detoxification of xenobiotics in plants. However, little is known about the endogenous substrates of plant GSTs, or their role in normal cellular processes. A cDNA library was constructed with poly(A)+ RNA isolated from cell suspension cultures of opium poppy (Papaver somniferum L.) treated with a fungal elicitor. A putative type III GST fragment was amplified by PCR from the cDNA library using degenerate primers designed from conserved domains found in several plant GSTs. The cDNA library was screened with the PCR product and 3 homologous clones were isolated. Deduced amino acid sequences from these clones displayed extensive homology to other plant type III GSTs, especially within the N‐terminal domain. One full‐length cDNA, designated pGST2, was expressed in Escherichia coli, and the recombinant enzyme exhibited strong GST activity in bacterial protein extracts, using 1‐chloro‐2,4‐dinitrobenzene as the substrate. Recombinant GST2 activity was inhibited by p‐coumaroyl‐ and feruloyl‐CoA esters, and p‐coumaric‐ and ferulic‐acid amides of tyramine, but not by free hydroxycinnamic acids or aromatic amines. Although type III GSTs in opium poppy appear to bind select endogenous phenolics, the in vitro conjugation of GSH to these compounds was not detected. Genomic DNA gel blot‐hybridization analysis confirmed the existence of a small family of type III GST genes in opium poppy. RNA gel blot‐hybridization analysis showed that type III GST transcripts were most abundant in the roots of mature opium poppy plants, and were induced in developing seedlings and in cell suspension cultures treated with a fungal elicitor. Relative transcript levels were generally consistent with the levels of total GST enzyme activity in each tissue.
Burkholderia cepaciacomplex: a contraindication to lung transplantation in cystic fibrosis?
Authors: LiPuma J.J.
Published: July 2002

Abstract:Previous studies have indicated that pulmonary infection withBurkholderia cepaciais associated with poor clinical outcome after lung transplantation in cystic fibrosis (CF). Many treatment centers considerB. cepaciainfection an absolute contraindication to lung transplantation. However, theB. cepaciacomplex actually consists of several closely related bacterial species. Although each of these has been isolated from CF sputum culture, certain species are much more frequently recovered than others, and it is not yet clear whether all species have the same potential for virulence in CF. Additional study is needed to better define the relative risks associated with each species of theB. cepaciacomplex.
Involvement of matrix metalloproteinases in the adipose conversion of 3T3-L1 preadipocytes
Authors: CROISSANDEAU Gilles , CHRÉTIEN Michel , MBIKAY Majambu
Published: July 2002

When mouse 3T3-L1 preadipocytes are induced to differentiate into adipocytes, they change from an extended fibroblast-like morphology to a rounded one. This change most likely occurs through extracellular matrix remodelling, a process known to be mediated in part by matrix metalloproteinases (MMPs). In this study, we have shown by semi-quantitative reverse transcriptase-PCR, zymographic and immunoblot analysis that MMP-2, MMP-9 and membrane type 1 (MT1)-MMP are regulated during adipose conversion. To assess the importance of MMPs for adipocytic differentiation we have used MMP-specific inhibitors as well as neutralizing antibodies. Treatment of 3T3-L1 preadipocytes with the broad MMP inhibitor Ilomastat or the more restricted MMP-2 Inhibitor I prevented their differentiation into adipocytes in a dose-dependent manner, as evidenced by absence of triglyceride accumulation. Inhibitor treatment prevented the fibronectin-network degradation, as well as the induction of the genes for peroxisome-proliferator-activated receptor γ and adipsin, two adipocyte phenotype markers. Inhibitor treatment was effective when applied during the early stages of adipocytic conversion, whereas inhibitor treatment during later stages had little effect. Inhibitor treatment did not inhibit clonal mitotic expansion; nor did it affect the expression pattern of the adipogenic transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) or its nuclear translocation. It did, however, markedly reduce C/EBPβ DNA-binding capacity. Taken together, these results suggest that MMPs, and notably MMP-2 and MMP-9, may be necessary mediators of adipocytic differentiation of 3T3-L1 cells.
Control of domain swapping in bovine odorant-binding protein
Authors: RAMONI Roberto , VINCENT Florence , ASHCROFT Alison E. , ACCORNERO Paolo , GROLLI Stefano , VALENCIA Christel , TEGONI Mariella , CAMBILLAU Christian
Published: July 2002

As revealed by the X-ray structure, bovine odorant-binding protein (OBPb) is a domain swapped dimer [Tegoni, Ramoni, Bignetti, Spinelli and Cambillau (1996) Nat. Struct. Biol. 3, 863–867; Bianchet, Bains, Petosi, Pevsner, Snyder, Monaco and Amzel (1996) Nat. Struct. Biol. 3, 934–939]. This contrasts with all known mammalian OBPs, which are monomers, and in particular with porcine OBP (OBPp), sharing 42.3% identity with OBPb. By the mechanism of domain swapping, monomers are proposed to evolve into dimers and oligomers, as observed in human prion. Comparison of bovine and porcine OBP sequences pointed at OBPp glycine 121, in the hinge linking the β-barrel to the α-helix. The absence of this residue in OBPb might explain why the normal lipocalin β-turn is not formed. In order to decipher the domain swapping determinants we have produced a mutant of OBPb in which a glycine residue was inserted after position 121, and a mutant of OBPp in which glycine 121 was deleted. The latter mutation did not result in dimerization, while OBPb-121Gly+ became monomeric, suggesting that domain swapping was reversed. Careful structural analysis revealed that besides the presence of a glycine in the hinge, the dimer interface formed by the C-termini and by the presence of the lipocalins conserved disulphide bridge may also control domain swapping.
Growth hormone replacement therapy in adults with growth hormone deficiency improves vascular reactivity
Authors: Christ Emanuel R. , Chowienczyk Philip J. , Sönksen Peter H. , Russel‐Jones David L.
Published: July 2002

OBJECTIVE

Patients with adult growth hormone (GH) deficiency are thought to be of increased risk of cardiovascular disease. Impaired vascular reactivity to endothelium derived nitric oxid (NO) is an early event in the development of atherosclerosis. In order to detect a possible effect of GH on vascular endothelium we examined forearm vasodilator responses in 8 patients with adult GH‐deficiency before and after 3 months GH replacement therapy.

METHODS

Forearm blood flow studies were performed using venous occlusion plethysmography. Blood flow was measured at baseline and during intra‐arterial infusions of 3 cumulative doses (7.5, 15 and 30 μg/minutes) of acetylcholine chloride and of sodium nitroprusside (1, 3 and 10 μg/minutes). Fasting blood samples were collected for measurement of lipid profile, Haemoglobin A1C (HbA1C), glucose, IGF‐I and insulin.

RESULTS

GH replacement therapy significantly increased IGF‐I concentrations and tended to increase fasting insulin concentrations (IGF‐I: 72.7 ± 12.4 vs. 130.8 ± 18.5 μg/l, P < 0.001; fasting insulin: 14.3 ± 3.4 vs. 32.9 ± 18.6, mU/l, P = 0.06). Fasting lipid profile, glucose and HbA1C did not significantly change. Blood flow responses to acetylcholine were significantly greater after GH replacement therapy (10.3 ± 1.0 vs. 17.6 ± 2.5 ml/minutes/100 ml for the highest dose, P < 0.03). There was a strong tendency to increased blood flow response to nitroprusside after GH therapy (10.7 ± 1.2 vs. 17.5 ± 1.7 ml/minutes/100 ml for the highest dose, P = 0.06).

CONCLUSION

These findings suggest that GH replacement therapy may have a beneficial effect on endothelium function which is independent of quantitative changes in fasting lipid profile.
pH and solubility of aluminium in acidic forest soils: a consequence of reactions between organic acidity and aluminium alkalinity
Authors: Skyllberg U.
Published: July 2002

Data from two Podzol O and E horizons, sampled in 1‐cm layers at 13 points within 2 m × 2 m plots, were used to test the hypothesis that the composition of hydrogen ions (H) and aluminium (Al) adsorbed to the solid‐phase soil organic matter (SOM) determines pH and Al solubility in organic‐rich acidic forest soils. Organically adsorbed Al was extracted sequentially with 0.5 mCuCl2and organically adsorbed H was determined as the difference between total acidity titrated to pH 8.2 and Al extracted in 0.5 mCuCl2. The quotient between fractions of SOM sites binding Al and H (NAl/NH) is shown to determine the variation in pH and Al solubility. It is furthermore shown that models in which pH and Al solubility are linked via a pH‐dependent solubility of an Al hydroxide and in which cation exchange between Al3+and Ca2+, rather than cation exchange between Al3+and H+, is the main pH‐buffering process cannot be used to simulate pH or Al solubility in O and E horizons. The fraction of SOM sites adsorbing Al increased by depth in the lower O and throughout the E horizon at the same magnitude as sites adsorbing H decreased. The fraction of sites binding the cations Ca2+ + Mg2+ + K+ + Na+remained constant. It is suggested that a net reaction between Al silicates (proton acceptors) and protonated functional groups in SOM (proton donors) is the long‐term chemical process determining the composition of organically adsorbed H and Al in the lower part of the O and in the E horizon of Podzols. Thus, in the long term, pH and Al solubility are determined by the interaction between organic acidity and Al alkalinity.
Repeating triplets of spikes and oscillations in the mitral cell discharges of freely breathing rats
Authors: Lestienne Rémy , Tuckwell Henry C. , Chalansonnet Monique , Chaput Michel
Published: July 2002

The olfactory bulb responses to odours display evident temporal organization, both in the form of high‐frequency oscillations and precisely replicating triplets of spikes. In this study, the frequency of replicating triplets in a sample of 118 individual responses from 45 cells was compared with that in simulations of non‐homogeneous Poisson processes, constructed from the experimental post‐stimulus time histograms (PSTHs). In a large majority of the records, replicating triplets (to a precision of 0.5 ms) are found to be more numerous in the physiological records; in some of them, they are ∼ 10 times more abundant. An excess of precisely replicating triplets is also found in records where no oscillations are apparent in the autocorrelograms. Triplet replication thus seems a more robust phenomenon than transient oscillation. Not unlike fast oscillations observed in other preparations, replicating triplets produced by a given mitral cell are generally observed only during a restricted period of time of the respiratory cycle (at least in the case of the responses under olfactory stimulation). No relation was found, however, between the nature and strength of the olfactory stimulus and the frequency of replicating patterns. In the absence of olfactory stimulation, some mitral cell discharges also contain more replicating triplets than the non‐homogeneous Poisson simulations. Thus, replicating triplets in single‐cell discharges seem to play only an indirect role in the coding of olfactory information at the mitral cell output level.
The accuracy of the frequency–volume chart: comparison of self‐reported and measured volumes
Authors: PalnÆS Hansen  , Klarskov
Published: July 2002

Objective

 To assess the accuracy of frequency–volume charts recorded by patients with voiding symptoms by comparing self‐reported voiding data with the volumes of urine collected in same period.

Patients and methods

 The study comprised 18 patients (median age 63 years, range 20–80) and lasted 3 days, during which the patients recorded their fluid intake and voided volumes, and collected 24 h urine samples.

Results

 The recorded volumes exceeded or underestimated the collected volume in 49% and 51%, respectively, of the samples, but the agreement between the accumulated daily voiding volumes on the charts and the volumes collected was acceptable. The median difference between volumes recorded on the charts and collected as samples was 100 (0–1450) mL per 24 h or 10 (0–117) mL per voiding (not significant). The median daily variation of creatinine in the urine was 1.1 (0.1–9.4) mmol (not significant), indicating that the 24 h collection periods were respected.

Conclusion

 Recordings on frequency–volume charts are valid and useful in the investigation of patients with voiding symptoms.
Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon
Authors: Uryu Yumiko , Malm Olaf , Thornton Iain , Payne Ian , Cleary David
Published: July 2002

Abstract:Since 1979 the gold rush in the Brazilian Amazon has caused serious environmental damage to one of the most complex ecosystems on Earth. Mainly due to the toxicity of mercury to humans, this problem has received wide public attention and prompted many studies. Although these studies have involved sampling of fish, the negative effect of mercury contamination to fish themselves and other wildlife has been largely ignored. To assess the present level of mercury contamination of fish, and its implication for fish and other animals, we collected and examined data on mercury concentration in fish of the Brazilian Amazon, especially for the Tapajós basin, between 1991 and 1996. We conclude that omnivores and piscivores that live nearer to gold mining areas in the Tapajós basin are already at high risk of mercury toxification, especially reproductive failure. Mercury concentrations in these fish are also high enough to have detrimental effects on animals at higher trophic levels. The same conclusion applies to other mercury‐contaminated areas in the Brazilian Amazon. Because most Amazonian rivers or their tributaries have favorable conditions for mercury contamination, we can expect the problem to persist in the Amazon for a long time, and the consequences are likely to become more significant in the future. These conclusions have important implications for all tropical rainforests where gold mining operations have caused extensive mercury pollution.
Short‐Term Boron Deprivation Induces Increased Levels of Cytoskeletal Proteins in Arabidopsis Roots
Authors: Yu Q. , Wingender R. , Schulz M. , Baluška F. , Goldbach H. E.
Published: July 2002

Abstract: Although boron is known to be an essential element for the growth of all higher plants, the links between primary responses to boron deprivation and the expression of visual symptoms are yet unknown. Western blots with anti‐actin and anti‐tubulin antibodies revealed an increase of both proteins upon 20 ‐ 40 min of boron deprivation in roots of hydroponically grown Arabidopsis thaliana. Moreover, actin depolymerizing factor and myosin VIII showed a less pronounced but similiar response to boron deficiency. In contrast, no increase in higher molecular mass ubiquitin was observed, indicating an absence of intensive protein degradation during the experimental time span. This is the first report of cytoskeletal responses of plants to short‐term boron removal. Rapid elevation of cytoskeletal proteins after boron deprivation is discussed in relation to the cell wall‐plasma membrane‐cytoskeleton continuum.
Stable Isotopes and Carbon Cycle Processes in Forests and Grasslands
Authors: Ehleringer J. R. , Bowling D. R. , Flanagan L. B. , Fessenden J. , Helliker B. , Martinelli L. A. , Ometto J. P.
Published: July 2002

Abstract:Scaling and partitioning are frequently two difficult challenges facing ecology today. With regard to ecosystem carbon balance studies, ecologists and atmospheric scientists are often interested in asking how fluxes of carbon dioxide scale across the landscape, region and continent. Yet at the same time, physiological ecologists and ecosystem ecologists are interested in dissecting the net ecosystem CO2exchange between the biosphere and the atmosphere to achieve a better understanding of the balance between photosynthesis and respiration within a forest. In both of these multiple‐scale ecological questions, stable isotope analyses of carbon dioxide can play a central role in influencing our understanding of the extent to which terrestrial ecosystems are carbon sinks. In this synthesis, we review the theory and present field evidence to address isotopic scaling of CO2fluxes. We first show that the13C isotopic signal which ecosystems impart to the atmosphere does not remain constant over time at either temporal or spatial scales. The relative balances of different biological activities and plant responses to stress result in dynamic changes in the13C isotopic exchange between the biosphere and atmosphere, with both seasonal and stand‐age factors playing major roles influencing the13C biosphere‐atmosphere exchange. We then examine how stable isotopes are used to partition net ecosystem exchange fluxes in order to calculate shifts in the balance of photosynthesis and respiration. Lastly, we explore how fundamental differences in the18O isotopic gas exchange of forest and grassland ecosystems can be used to further partition terrestrial fluxes.
Mechanism of formation of 〈110〉 oriented fivefold microcrystallites in diamond films
Authors: Narayan J. , Srivatsa A. R. , Ravi K. V.
Published: July 2002

We have investigated the formation of 〈110〉 oriented fivefold diamond microcrystallites on {001} silicon substrates using high-resolution transmission electron microscopy (HRTEM). The HRTEM micrographs clearly show that fivefold symmetry in diamond microcrystallites results from twinning in {111} planes, in agreement with electron diffraction data. The five 〈110〉 oriented microcrystallites that provide fivefold symmetry are enclosed by {111} planes. The angles between various planes in these microcrystallites can be directly measured in HRTEM micrographs. The angles between {111} planes are found to vary from 70.5° (ideal) to as much as 74° for some microcrystallites. The boundaries of microcrystallites contain coherent twins with only occasional presence of dislocations to accommodate the misfit. We propose a model for nucleation and formation of fivefold diamond microcrystallites. The proposed model, based upon the presence of a/2〈110〉{001} edge dislocations, is found to be consistent with HRTEM observations.
Organometallic vapor phase epitaxial growth and characterization of InAsBi and InAsSbBi
Authors: Ma K. Y. , Fang Z. M. , Jaw D. H. , Cohen R. M. , Stringfellow G. B. , Kosar W. P. , Brown D. W.
Published: July 2002

InAs1−xBix with x≤0.026 and InAs1−x−ySbyBix with x≤0.017 and y≤0.096 have been successfully grown on InAs (100) oriented substrates by atmospheric pressure organometallic vapor phase epitaxy using the precursors trimethylindium, trimethylbismuth, trimethylantimony, and arsine. Good surface morphologies for both InAsBi and InAsSbBi epitaxial layers were obtained at a growth temperature of 400 °C. A key growth parameter is the V/III ratio. Only a very narrow range near 4 (considering the incomplete pyrolysis of AsH3) yields smooth InAsBi epilayers. Typical growth rates were 0.02 μm/min. X-ray diffractometer scans show clearly resolved Kα1 and Kα2 peaks for the layer of InAs0.889Sb0.096Bi0.015 grown on an InAs substrate with a graded transition layer to accommodate the lattice parameter difference. The half widths of the peaks are comparable to those of the substrate. For the first time, photoluminescence (PL) at 10 K from these Bi-containing alloys has been measured. The PL peak energy is seen to decrease with increasing Bi concentration at a rate of 55 meV/at. % Bi. InAsSbBi is a potential material for infrared detectors operating in the wavelength range from 8 to 12 μm.
Modification of hydrogen-passivated silicon by a scanning tunneling microscope operating in air
Authors: Dagata J. A. , Schneir J. , Harary H. H. , Evans C. J. , Postek M. T. , Bennett J.
Published: July 2002

The chemical modification of hydrogen-passivated n-Si (111) surfaces by a scanning tunneling microscope (STM) operating in air is reported. The modified surface regions have been characterized by STM spectroscopy, scanning electron microscopy (SEM), time-of-flight secondary-ion mass spectrometry (TOF SIMS), and chemical etch/Nomarski microscopy. Comparison of STM images with SEM, TOF SIMS, and optical information indicates that the STM contrast mechanism of these features arises entirely from electronic structure effects rather than from topographical differences between the modified and unmodified substrate. No surface modification was observed in a nitrogen ambient. Direct writing of features with 100 nm resolution was demonstrated. The permanence of these features was verified by SEM imaging after three months storage in air. The results suggest that field-enhanced oxidation/diffusion occurs at the tip-substrate interface in the presence of oxygen.
Diode-pumped single-mode fluorozirconate fiber laser from the 4I11/2→4I13/2 transition in erbium
Authors: Allen R. , Esterowitz L. , Ginther R. J.
Published: July 2002

Diode-pumped cw lasing at 2.71, 2.75, and 2.78 μm from an erbium-doped ZBLAN single-mode fiber is reported for the first time. A threshold of 4 mW absorbed power at 792 nm was obtained for the 2.71 μm transition. 3% slope efficiency was obtained with an 80% reflecting output mirror. cw lasing was also observed from the fiber when a tunable pump was scanned across most of the 4I15/2→4I9/2 absorption band. cw lasing observed when pumping around 820 nm indicates that excited-state absorption of the pump from the 4I13/2 may not be necessary for cw operation. However, excited-state absorption of the pump around 810 nm from the 4I11/2 may limit performance.
Ultrashallow, high doping of boron using molecular layer doping
Authors: Nishizawa J. , Aoki K. , Akamine T.
Published: July 2002

A new doping method named molecular layer doping (MLD) is proposed. MLD is based on surface chemical adsorption of dissolvements from induced dopant gas molecules. Ultrashallow boron-doped layers are successfully achieved by MLD using B2 H6 gas. The p+ n junction formed by MLD exhibits excellent characteristics, with a reverse bias leakage current of less than 2.5×10−16 A/μm2 at 5 V. MLD is attractive in that it offers high-density, shallow-junction, damage-free, selective doping in a short time.
Microscopic and macroscopic uniformity control in plasma etching
Authors: Giapis Konstantinos P. , Scheller Geoffrey R. , Gottscho Richard A. , Hobson William S. , Lee Yong H.
Published: July 2002

By cooling substrates to low temperatures (−40 °C), plasma etching of AlGaAs/AlAs/GaAs structures is performed in an ion-activated, surface reaction limited regime. As a result, microscopic and macroscopic uniformity are vastly improved and etching is independent of gas flow patterns, plasma geometry, and reactor loading. Because the reactant is concentrated on the surface, etching rates remain large.
Enhanced and inhibited spontaneous emission in GaAs/AlGaAs vertical microcavity lasers with two kinds of quantum wells
Authors: Yamauchi T. , Arakawa Y. , Nishioka M.
Published: July 2002

We investigate enhanced and inhibited spontaneous emission effects in a vertical λ-microcavity structure having two kinds of quantum wells (QWs) with the thicknesses of 76 and 114 Å, measuring both photoluminescence intensity and carrier lifetime. The 76 and 114 Å QWs are placed at the maximum and at the nodes of the emitted standing wave in the microcavity, respectively. When the λ-microcavity mode is tuned to the quantized band-gap energy of the 76 Å QWs (enhanced condition), the PL intensity is enhanced compared with the case that the cavity mode is tuned to the quantized band-gap energy of the 114 Å QWs (inhibited condition). In addition, the increase of the carrier lifetime is also observed under the inhibited condition. These results demonstrate existence of enhanced and inhibited spontaneous emission effects in the microcavity structures.
Remotely-doped superlattices in wide parabolic GaAs/AlxGa1−xAs quantum wells
Authors: Baskey J. H. , Rimberg A. J. , Yang Scott , Westervelt R. M. , Hopkins P. F. , Gossard A. C.
Published: July 2002

Using the digital alloy technique, a series of high-mobility remotely doped GaAs/AlGaAs coupled multiple quantum well structures have been produced by the superposition of a wide parabolic quantum well and a square superlattice potential. Structures containing up to twenty superlattice periods with low temperature Hall mobilities from 23 000 to 100 000 cm2/V s have been produced. Fourier analysis of low field Shubnikov–de Haas oscillations, capacitance-voltage and Hall measurements of a 200 Å period superlattice in a 1600 Å wide parabolic well indicate the occupation of four superlattice periods with subband spacings in good agreement with theory.
Phase transitions of dense systems of charged ‘‘dust’’ grains in plasmas
Authors: Farouki R. T. , Hamaguchi S.
Published: July 2002

The behavior of ‘‘dust’’ grains (particulates) in microelectronics process plasmas has been studied using N-body simulations. Grains are assumed to be negatively charged and interact through a screened Coulomb potential Φ(r). The dimensionless parameters κ=a/λ and Γ=Φ(a)/kBT characterize the thermodynamics of the particulate system, where λ is the ion Debye length, a=(3/4πnD)1/3 is the mean intergrain distance, and nD and T are the dust density and temperature. The simulations exhibit a transition between ‘‘fluid’’ and ‘‘solid’’ phases at a critical value Γc that depends on κ and weakly on the system history (i.e., whether it ‘‘melts’’ from an ordered state or ‘‘freezes’’ from a random one).
LiNbO3 thin-film optical waveguide grown by liquid phase epitaxy using Li2O-B2O3 flux
Authors: Yamada Atsuo , Tamada Hitoshi , Saitoh Masaki
Published: July 2002

Nearly stoichiometric LiNbO3 thin-film waveguides with high crystallinity and good surface morphology were grown on a 5 mol % MgO-doped Z-plate LiNbO3 substrate by liquid phase epitaxy using Li2O-B2O3 flux. The profile of the film-substrate interface was estimated to be nearly a step and a domain inversion with a distinct boundary at the −Z surface of the substrate was observed. Waveguiding was realized for an ordinary wave, but not for an extraordinary wave. There existed no significant optical absorption to the fundamental absorption edge, resulting in a negligibly small propagation loss of less than 1 dB/cm at a wavelength of 458 nm.
Magnetic field dependence of selective pair luminescence in GaAs
Authors: Reynolds D. C. , Yu P. W. , Evans K. R. , Stutz C. E. , Loehr J.
Published: July 2002

The shift in the final state emission energy, resulting from selective pair luminescence in an applied magnetic field in GaAs, is very small. Any shift that is observed is toward lower energy. The relatively constant emission energy in the presence of an applied magnetic field is realized because the increase in band-gap energy, which would shift the emission toward higher energies, is offset by an increase in the donor binding energy which shifts the emission toward lower energies. The acceptor binding energy is essentially constant with applied field while the change in the Coulomb term, due to a change in the pair separation in a magnetic field, is quite small. As a result, the same acceptor excited states are identified in the presence of an applied magnetic field, as in zero field for the same pump energy. The results of this experiment are limited to applied fields ≤36 kG.
Epitaxial diamond thin films on (001) silicon substrates
Authors: Jiang X. , Klages C.-P. , Zachai R. , Hartweg M. , Füsser H.-J.
Published: July 2002

Epitaxial (001) diamond film were grown on mirror-polished single-crystalline (001) silicon substrates by microwave plasma chemical vapor deposition from a methane/hydrogen gas mixture. The films were characterized by means of scanning electron microscopy, Raman spectroscopy, and x-ray analysis. The results show that the diamond crystallites are oriented to the silicon substrate with both the (001) planes and the [110] directions parallel to the silicon substrate.
Multiple self-consistent solutions at zero bias and multiple conduction curves in quantum tunneling diodes incorporating N−-N+-N− spacer layers
Authors: Gullapalli K. K. , Tsao A. J. , Neikirk D. P.
Published: July 2002

We report the existence of multiple self-consistent solutions to the coupled Schrödinger and Poisson equations for diodes that combine a tunneling heterostructure with an unusual N−-N+-N− spacer layer scheme. The solutions give rise to multiple, distinct current-voltage curves that extend from zero bias. Within the single electron coherent tunneling model, we find four distinct self-consistent solutions even at zero bias in a symmetric device based on a double-barrier quantum-well tunneling structure.
Electron energy distribution function measurements in a planar inductive oxygen radio frequency glow discharge
Authors: Barnes Michael S. , Forster John C. , Keller John H.
Published: July 2002

A tuned, cylindrical Langmuir probe was used to measure current-voltage traces in a planar, inductive oxygen, radio frequency glow discharge at several pressures ranging from 0.5 to 10 mT. The plasma potentials were determined from the zero crossings of the trace second derivatives. Positive ion densities were evaluated using orbit motion limited probe theory; electron densities were estimated by integrating the area under the unnormalized distribution function. By applying the Druyvesteyn formula to the digitized probe traces, the electron energy distribution functions were obtained. The distribution functions ranged from Maxwellian at 0.5 mT to almost Druyvesteyn-like at 10 mT.
Microwave measurement of the dielectric constant of Sr0.5Ba0.5TiO3 ferroelectric thin films
Authors: Carroll K. R. , Pond J. M. , Chrisey D. B. , Horwitz J. S. , Leuchtner R. E. , Grabowski K. S.
Published: July 2002

Measurement of the relative dielectric constant of a Sr0.5Ba0.5TiO3 (SBT) thin film is presented as a function of electric field strength and temperature over a broad frequency range using a microstrip transmission line. The transmission line was fabricated from a trilayer structure where the SBT film, grown by pulsed laser deposition, was bounded by silver and platinum metallization layers. Such structures involving ferroelectric films could be useful for microwave applications because of the substantially smaller bias voltages (≊1–10 V) compared to those required for bulk material. The SBT film was found to exhibit a dielectric constant of ≊120–250 and a large electric field modulation of ≊50% at 200 kV/cm. These properties of the material as well as the Curie temperature are compared to those of bulk SBT.
Magnetic properties of LaNiO3 films and Josephson characteristics of Y1Ba2Cu3O7−y/LaNiO3/Au/Ag/Pb junctions
Authors: Sagoi Masayuki , Kinno Teruyuki , Yoshida Jiro , Mizushima Koichi
Published: July 2002

A conductive perovskite oxide, LaNiO3, has been examined for the application to the normal layer for superconductor-normal metal-superconductor junctions for the first time. LaNiO3 films showed resistivity as low as 1.5×10−4 Ω cm. Pauli paramagnetism dominated in the film. The susceptibility measured was 0.9×10−6 emu/Oe g. Boundaries between the Y1Ba2Cu3O7−y and LaNiO3 layers were found to be abrupt in a Y1Ba2Cu3O7−y/LaNiO3 multilayer by transmission electron microscopy (TEM) observation. The coherence length in LaNiO3 was estimated to be 30–70 Å from characteristics of the Y1Ba2Cu3O7−y/LaNiO3/Au/Ag/Pb junctions. The value was comparable to the dirty limit coherence length of (ℏD/2πkBT)1/2 of the conventional theory (D; the diffusion constant in LaNiO3).