bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract: Beam energy transfer and propagation in a fully ionized magnetized plasma
Authors: Ekdahl C. , Greenspan M. , Sethian J. , Wharton C. B. 
Published: July 2002

The interaction of a relativistic electron beam (300–500 kV, 5–40 kA, ν/2&lt;2) with a fully ionized magnetic mirror-confined plasma column (1012 cm−3&lt;ne&lt;5×1013 cm−3; 0.01&lt;nb/ne&lt;0.3) has been experimentally investigated. Beam density profiles have been obtained using a small Faraday cup with a thin foil-covered aperture, and by measuring the intensity of x rays generated in small targets. Spatially resolved current profiles have been measured with small magnetic flux loops. Beam energy has been determined by varying the foil thickness covering the Faraday-cup aperature and by graded-foil-absorber energy analysis of the target x-ray emission. The energy transfer to the plasma column has been measured with diamagnetic loops, and the ion energy distribution has been determined with a multichannel analyzer.
Results indicate up to 8% transfer of the diode energy to heating of the plasma column with the energy per electron–ion pair increasing linearly with the beam to plasma density ratio nb/ne. Ion energy distribution with high energy tails is observed. Following beam injection, oscillations are observed on the plasma column which propagate with the Alven velocity. 80%–98% current neutralization is observed. From the decay of currents which persist after the passage of the beam, a plasma resistivity can be inferred for the plasma column which is three to four orders of magnitude greater than the Spitzer resistivity calculated for the plasma column.
Strain dependence of the valence-band offset in arsenide compound heterojunctions determined by photoelectron spectroscopy
Authors: Ohler C. , Moers J. , Förster A. , Lüth H. 
Published: July 2002

We have used ultraviolet and x-ray photoelectron spectroscopy to study the strain dependence of the valence-band offset (VBO) in situ for binary arsenide compound semiconductor heterojunctions grown by molecular beam epitaxy; i.e., we have measured the VBO of InAs/GaAs, InAs/AlAs, and AlAs/GaAs(100) heterojunctions as it changes when these heterojunctions are pseudomorphically strained to lattice constants ranging from 5.653 Å (GaAs) to 6.058 Å (InAs). Intermediate lattice constants have been realized by using fully relaxed InxGa1−xAs buffer layers as virtual substrates. The spectrum of two distinct core-levels, one from either side of the coherently strained junction, monitors the energetic alignment across the junction. To establish the band offset, one has to know in addition the binding-energy separation of the core-level to the respective valence-band maximum (VBM) for each of the junction’s two components and corresponding to their correct bulk strain state. Here, we have recorded valence-band and core-level spectra of strained ‘‘bulk’’ samples to determine this energy difference experimentally. We have accounted for the true shape of the density of states near the VBM by using results of k⋅p theory, thus avoiding a full pseudopotential calculation. GaAs/InAs and AlAs/InAs heterojunction VBOs are heavily strain dependent.
For example, one can alter the GaAs/InAs VBO by 480 meV on going from the GaAs to the InAs lattice constant, the InAs VBM being 0.04±0.10 eV lower than the GaAs VBM when InAs is strained to the GaAs lattice constant and 0.52±0.10 eV lower when the strain is vice versa. The AlAs/InAs heterojunction VBO changes from +0.29±0.11 eV (type-I), when InAs is strained to AlAs, to −0.10±0.17 eV (type-II) for the opposite case. The AlAs/GaAs heterojunction VBO is independent of strain within our limits of accuracy. The results are compared with recent theoretical data, both ‘‘model’’ theories and self-consistent calculations, shedding some light on the features that are important for the band alignment at polar heterojunctions. The results can be interpolated in a straightforward manner to estimate the VBO for the more realistic case of heterojunctions built up of any two ternary arsenide compounds strained to any reasonable lattice constant.
Use of maximum entropy deconvolution for the study of silicon delta layers in GaAs
Authors: Cooke G. A. , Dowsett M. G. , Allen P. N. , Collins R. , Miethe K. 
Published: July 2002

Semiconductor layer structures with sharply changing concentration, and more especially delta-doped (single atomic plane) structures, provide an ideal environment for the study of the more subtle mass transport phenomena such as concentration-dependent diffusion and localized mixing caused by ion bombardment. However, to be able to extract meaningful parameters from such experiments, accurate depth profiles must be obtained with extremely high depth resolution and good sensitivity. Secondary ion mass spectrometry (SIMS) provides one of the most sensitive methods for acquiring such profiles. To obtain high depth resolution, a number of criteria must be satisfied, not the least of which is the reduction of redistribution by the probe; thus it is essential to employ a low energy primary beam. It is also vital that the crater floor recedes parallel to the original surface of the specimen. This necessitates accurate scanning of a stable ion beam, so as to ensure a constant flux across the entire sampled area.
If this is not the case, depth resolution will degrade as a function of depth, and important information will be lost. However, even if probes of the order of 1–2 keV are used, together with a precision scan system, beam-induced redistribution is still a significant limit to the sharpness of the recorded profiles. To further improve upon the data, the effects of the analysis must be removed from the profile. In this article we demonstrate the use of the maximum entropy deconvolution technique, applying it to a SIMS depth profile of a multilayer silicon in gallium arsenide structure containing alternating layers of high and low areal density. The important issue of data validity is discussed and the deconvolved results are used to calculate a diffusion constant for the denser layers, the less dense layers show no diffusion at the growth temperature of 450 °C.
Efficacy of Voriconazole in a Guinea Pig Model of Disseminated Invasive Aspergillosis
Authors: Kirkpatrick William R. , McAtee Robert K. , Fothergill Annette W. , Rinaldi Michael G. , Patterson Thomas F. 
Published: July 2002

ABSTRACT

Voriconazole (VRC) was evaluated in an immunosuppressed-guinea pig model of invasive aspergillosis. VRC was more effective than amphotericin B or similar doses of itraconazole in the clearance of
Aspergillus
from tissues. VRC treatment regimens improved survival and significantly reduced tissue colony counts compared with those of controls.
Fluoroquinolone Resistance Associated with Target Mutations and Active Efflux in Oropharyngeal Colonizing Isolates of Viridans Group Streptococci
Authors: Guerin François , Varon Emmanuelle , Hoï Annie Buu , Gutmann Laurent , Podglajen Isabelle 
Published: July 2002

ABSTRACT

Oropharyngeal samples from 60 hospitalized patients (30 fluoroquinolone [FQ]-treated and 30 non-FQ-treated patients) and 30 untreated nonhospitalized healthy control subjects yielded 20 isolates of viridans group streptococci with reduced susceptibility to FQ, mostly from the hospitalized patients. An efflux phenotype was commonly encountered, expressed either alone or with topoisomerase mutations. Interspecies transfer of the efflux phenotype was demonstrated via transformation of
Streptococcus pneumoniae
R6 with DNA from
S. mitis
and
S. oralis
.
Clinical Isolate of Vancomycin-Heterointermediate
Staphylococcus aureus
Susceptible to Methicillin and In Vitro Selection of a Vancomycin-Resistant Derivative
Authors: Bobin-Dubreux Sophie , Reverdy Marie-Elisabeth , Nervi Chantal , Rougier Martine , Bolmström Anne , Vandenesch François , Etienne Jerome 
Published: July 2002

ABSTRACT

A
Staphylococcus aureus
strain with low-level heteroresistance to vancomycin (designated MER) but susceptible to methicillin was isolated from an outpatient with conjunctivitis who did not receive any glycopeptide antibiotics. Incubation of the parent strain, MER, with increasing concentrations of vancomycin led to rapid selection of a stable progeny homogeneously resistant to vancomycin. Electron micrographs of strain MER showed enhanced cell wall thickness and abnormal septations typically seen with methicillin-resistant
S. aureus
having intermediate susceptibility to vancomycin.
Systematic Analysis of a Conserved Region of the Aminoglycoside 6′-
N
-Acetyltransferase Type Ib
Authors: Shmara Ali , Weinsetel Natalia , Dery Ken J. , Chavideh Ramona , Tolmasky Marcelo E. 
Published: July 2002

ABSTRACT

Alanine-scanning mutagenesis was applied to the aminoglycoside 6′-
N
-acetyltransferase type Ib conserved motif B, and the effects of the substitutions were analyzed by measuring the MICs of kanamycin (KAN) and its semisynthetic derivative, amikacin (AMK). Several substitutions resulted in no major change in MICs. E167A and F171A resulted in derivatives that lost the ability to confer resistance to KAN and AMK. P155A, P157A, N159A, L160A, I163A, K168A, and G170A conferred intermediate levels of resistance. Y166A resulted in an enzyme derivative with a modified specificity; it conferred a high level of resistance to KAN but lost the ability to confer resistance to AMK. Although not as pronounced, the resistance profiles conferred by substitutions N159A and G170A were related to that conferred by Y166A. These phenotypes, taken together with previous results indicating that mutant F171L could not catalyze acetylation of AMK when the assays were carried out at 42°C (D. Panaite and M. Tolmasky, Plasmid 39:123–133, 1998), suggest that some motif B amino acids play a direct or indirect role in acceptor substrate specificity. MICs of AMK and KAN for cells harboring the substitution C165A were high, suggesting that the active form of the enzyme may not be a dimer formed through a disulfide bond. Furthermore, this result indicated that the acetylation reaction occurs through a direct mechanism rather than a ping-pong mechanism that includes a transient transfer of the acetyl group to a cysteine residue. Deletion of fragments at the C terminus demonstrated that up to 10 amino acids could be deleted without a loss of activity.
Outbreak of Cefozopran (Penicillin, Oral Cephems, and Aztreonam)-Resistant
Neisseria gonorrhoeae
in Japan
Authors: Muratani Tetsuro , Akasaka Soichiro , Kobayashi Tomoko , Yamada Yoji , Inatomi Hisato , Takahashi Koichi , Matsumoto Tetsuro 
Published: July 2002

ABSTRACT

We have previously reported that the
Neisseria gonorrhoeae
isolates from clinical failure cases treated with cefdinir and aztreonam, β-lactams exhibited high MICs. These resistant isolates were clearly separated from the isolates exhibiting a low level of resistance to β-lactams as shown by the MIC distribution of cefozopran. Restriction fragment length polymorphism DNA typing revealed that the outbreak of cefozopran-resistant isolates in Kitakyushu, Japan, occurred as a result of clonal spread.
In Vitro Antibacterial Activities of AF 3013, the Active Metabolite of Prulifloxacin, against Nosocomial and Community Italian Isolates
Authors: Montanari Maria Pia , Mingoia Marina , Varaldo Pietro Emanuele 
Published: July 2002

ABSTRACT
AF 3013, the active metabolite of prulifloxacin, was tested to determine its inhibitory and bactericidal activities against 396 nosocomial and 258 community Italian isolates. Compared with that of ciprofloxacin, its activity (assessed in MIC and minimal bactericidal concentration tests) was generally similar or greater against gram-positive bacteria and greater against gram-negative bacteria. In time-kill assays using selected isolates, its bactericidal activity was comparable to that of ciprofloxacin.
Pharmacokinetics and Safety of a 7-Day Administration of Intravenous Itraconazole followed by a 14-Day Administration of Itraconazole Oral Solution in Patients with Hematologic Malignancy
Authors: Boogaerts Marc A. , Maertens Johan , Van Der Geest Ronald , Bosly Andre , Michaux Jean-Louis , Van Hoof Achiel , Cleeren Myriam , Wostenborghs Robert , De Beule Karel 
Published: July 2002

ABSTRACTThe pharmacokinetics and safety of an intravenous hydroxypropyl-β-cyclodextrin solution of itraconazole administered for 7 days followed by itraconazole oral solution administered at 200 mg once or twice daily for 14 days were assessed in 17 patients with hematologic malignancies. Steady-state plasma itraconazole concentrations were reached by 48 h after the start of intravenous treatment. The mean trough plasma itraconazole concentration at the end of the intravenous treatment was 0.54 ± 0.20 μg/ml. This concentration was not maintained during once-daily oral treatment but increased further in the twice-daily treatment group, with a trough itraconazole concentration of 1.12 ± 0.73 μg/ml at the end of oral treatment. As expected in the patient population studied, all patients experienced some adverse events (mainly gastrointestinal). Biochemical and hematologic abnormalities were frequent, but no consistent changes occurred. In conclusion, 7 days of intravenous treatment followed by 14 days of twice-daily oral treatment with itraconazole solution enables plasma itraconazole concentrations of at least 0.5 μg/ml to be reached rapidly and to be maintained. The regimen is well tolerated and has a good safety profile.
Domestic Cat Model for Predicting Human Nucleoside Analogue Pharmacokinetics in Blood and Seminal Plasma
Authors: Jordan Holly L. , Pereira Arlene S. , Cohen Myron S. , Kashuba Angela D. M. 
Published: July 2002

ABSTRACT
To establish whether a feline model can predict nucleoside analogue behavior in human semen, zidovudine (ZDV) and lamivudine (3TC) pharmacokinetic parameters (PKs) were determined in the blood and seminal plasma of healthy cats. Our results show considerable similarity in ZDV and 3TC PKs between cats and humans. As in humans, ZDV and 3TC tend to accumulate in feline seminal plasma. Area under the blood plasma concentration-time curve was predictive of seminal plasma excretion. The felid model offers a unique in vivo experimental alternative for investigating the pharmacokinetics of nucleoside analogues in the male genital tract.
Pathovars of
Pseudomonas syringae
Causing Bacterial Brown Spot and Halo Blight in
Phaseolus vulgaris
L. Are Distinguishable by Ribotyping
Authors: González Ana J. , Landeras Elena , Mendoza M. Carmen 
Published: July 2002

ABSTRACT

Ribotyping was evaluated as a method to differentiate between
Pseudomonas syringae
pv. phaseolicola and pv. syringae strains causing bacterial brown spot and halo blight diseases in
Phaseolus vulgaris
L. Ribotyping, with restriction enzymes
Bgl
I and
Sal
I and using the
Escherichia coli rrnB
operon as the probe, differentiated 11 and 14 ribotypes, respectively, and a combination of data from both procedures yielded 19 combined ribotypes. Cluster analysis of the combined ribotypes differentiated the pathovars phaseolicola and syringae, as well as different clonal lineages within these pathovars. The potential of ribotyping to screen for correlations between lineages and factors such as geographical region and/or bean varieties is also reported.
Development of a Nonantibiotic Dominant Marker for Positively Selecting Expression Plasmids in Multivalent
Salmonella
Vaccines
Authors: McNeill Hesta V. , Sinha Katharine A. , Hormaeche Carlos E. , Lee Jeong Jin , Khan C. M. Anjam 
Published: July 2002

ABSTRACT

We report the novel application of a herbicide-resistance-based dominant marker for the positive selection of expression plasmids in
Salmonella
serovar vaccines. The β-lactamase gene of the plasmid pTETnir15, which expresses fragment C of tetanus toxin (TetC), has been replaced with the
bar
gene marker. The new plasmid pBAT1 can be positively selected in vitro within
Salmonella
serovars in the presence of the herbicide
dl
-phosphinothricin. The expression of TetC remains unaltered, and the
Salmonella enterica
serovar Typhimurium vaccine strain is stable and immunogenic in vivo.
Development of a Fluorogenic Probe-Based PCR Assay for Detection of
Bacillus cereus
in Nonfat Dry Milk
Authors: Kim Young-Rok , Czajka John , Batt Carl A. 
Published: July 2002

ABSTRACT

A fluorogenic probe-based PCR assay was developed and evaluated for its utility in detecting
Bacillus cereus
in nonfat dry milk. Regions of the hemolysin and cereolysin AB genes from an initial group of two
B. cereus
isolates and two
Bacillus thuringiensis
isolates were cloned and sequenced. Three single-base differences in two
B. cereus
strains were identified in the cereolysin AB gene at nucleotides 866, 875, and 1287, while there were no species-consistent differences found in the hemolysin gene. A fluorogenic probe-based PCR assay was developed which utilizes the 5′-to-3′ exonuclease of
Taq
polymerase, and two fluorogenic probes were evaluated. One fluorogenic probe (cerTAQ-1) was designed to be specific for the nucleotide differences at bases 866 and 875 found in
B. cereus
. A total of 51 out of 72
B. cereus
strains tested positive with the cerTAQ-1 probe, while only 1 out of 5
B. thuringiensis
strains tested positive. Sequence analysis of the negative
B. cereus
strains revealed additional polymorphism found in the cereolysin probe target. A second probe (cerTAQ-2) was designed to account for additional polymorphic sequences found in the cerTAQ-1-negative
B. cereus
strains. A total of 35 out of 39
B. cereus
strains tested positive (including 10 of 14 previously negative strains) with cerTAQ-2, although the assay readout was uniformly lower with this probe than with cerTAQ-1. A PCR assay using cerTAQ-1 was able to detect approximately 58
B. cereus
CFU in 1 g of artificially contaminated nonfat dry milk. Forty-three nonfat dry milk samples were tested for the presence of
B. cereus
with the most-probable-number technique and the fluorogenic PCR assay. Twelve of the 43 samples were contaminated with
B. cereus
at levels greater than or equal to 43 CFU/g, and all 12 of these samples tested positive with the fluorogenic PCR assay. Of the remaining 31 samples, 12 were
B. cereus
negative and 19 were contaminated with
B. cereus
at levels ranging from 3 to 9 CFU/g. All 31 of these samples were negative in the fluorogenic PCR assay. Although not totally inclusive, the PCR-based assay with cerTAQ-1 is able to specifically detect
B. cereus
in nonfat dry milk.
Lipopolysaccharides of
Rhizobium etli
Strain G12 Act in Potato Roots as an Inducing Agent of Systemic Resistance to Infection by the Cyst Nematode
Globodera pallida
Authors: Reitz M. , Rudolph K. , Schröder I. , Hoffmann-Hergarten S. , Hallmann J. , Sikora R. A. 
Published: July 2002

ABSTRACT

Recent studies have shown that living and heat-killed cells of the rhizobacterium
Rhizobium etli
strain G12 induce in potato roots systemic resistance to infection by the potato cyst nematode
Globodera pallida
. To better understand the mechanisms of induced resistance, we focused on identifying the inducing agent. Since heat-stable bacterial surface carbohydrates such as exopolysaccharides (EPS) and lipopolysaccharides (LPS) are essential for recognition in the symbiotic interaction between
Rhizobium
and legumes, their role in the
R. etli
-potato interaction was studied. EPS and LPS were extracted from bacterial cultures, applied to potato roots, and tested for activity as an inducer of plant resistance to the plant-parasitic nematode. Whereas EPS did not affect
G. pallida
infection, LPS reduced nematode infection significantly in concentrations as low as 1 and 0.1 mg ml
−1
. Split-root experiments, guaranteeing a spatial separation of inducing agent and challenging pathogen, showed that soil treatments of one half of the root system with LPS resulted in a highly significant (up to 37%) systemic induced reduction of
G. pallida
infection of potato roots in the other half. The results clearly showed that LPS of
R. etli
G12 act as the inducing agent of systemic resistance in potato roots.
Expression of a Tetraheme Protein,
Desulfovibrio vulgaris
Miyazaki F Cytochrome
c
3
, in
Shewanella oneidensis
MR-1
Authors: Ozawa Kiyoshi , Tsapin Alexandre I. , Nealson Kenneth H. , Cusanovich Michael A. , Akutsu Hideo 
Published: July 2002

ABSTRACT

Cytochrome
c
3
from
Desulfovibrio vulgaris
Miyazaki F was successfully expressed in the facultative aerobe
Shewanella oneidensis
MR-1 under anaerobic, microaerophilic, and aerobic conditions, with yields of 0.3 to 0.5 mg of cytochrome/g of cells. A derivative of the broad-host-range plasmid pRK415 containing the cytochrome
c
3
gene from
D. vulgaris
Miyazaki F was used for transformation of
S. oneidensis
MR-1, resulting in the production of protein product that was indistinguishable from that produced by
D. vulgaris
Miyazaki F, except for the presence of one extra alanine residue at the N terminus.
Monitoring of
Ralstonia eutropha
KT1 in Groundwater in an Experimental Bioaugmentation Field by In Situ PCR
Authors: Tani Katsuji , Muneta Masahiro , Nakamura Kanji , Shibuya Katsutoshi , Nasu Masao 
Published: July 2002

ABSTRACT

Ralstonia eutropha
KT1, which degrades trichloroethylene, was injected into the aquifer after activation with toluene, and then the number of bacteria was monitored by in situ PCR targeting the phenol hydroxylase gene and by fluorescent in situ hybridization (FISH) targeting 16S rRNA. Before injection of the bacterial suspension, the total concentration of bacteria in the groundwater was approximately 3 × 10
5
cells/ml and the amount of
Ralstonia
and bacteria carrying the phenol hydroxylase gene as a percentage of total bacterial cells was less than 0.1%. The concentration of bacteria carrying the phenol hydroxylase gene detected by in situ PCR was approximately 3 × 10
7
cells/ml 1 h after injection, and the concentration of
Ralstonia
detected by FISH was similar. The number of bacteria detected by in situ PCR was similar to that detected by FISH 4 days after the start of the extraction of groundwater. On and after day 7, however, the number of bacterial cells detected by FISH was less than that detected by in situ PCR.