bluuebunny/crossref_metadata_2025 huggingface dataset:
Formate binding to ferric wild type and mutant myoglobins thermodynamic and X‐ray crystallographic study
Authors: Leci Edlira , Brancaccio Andrea , Cutruzzolà Francesca , Allocatelli Carlo Travaglini , Tarricone Cataldo , Bolognesi Martino , Desideri Alessandro , Ascenzi Paolo
Published: July 2002

The X‐ray crystal structure of the formate derivative of ferric loggerhead sea turtle (Caretta caretta) Mb has been determined at 2.0 Å resolution (R = 0.164) by difference Fourier techniques. Formate, sitting in the central part of the heme distal site, is coordinated to the heme iron as unidentate ligand, through the O1 oxygen atom, and is hydrogen bonded to the distal His64(E7) NE2 atom through O2. Thermodynamics for formate binding to ferric loggerhead sea turtle Mb, sperm whale Mb, Aplysia limacina Mb, as well as to the VR and VRS mutants of sperm whale Mb were obtained between pH 4.5 and 8.5, at 20.0°C. These results, representing the first structure of a ferric hemoprotein:formate complex solved by X‐ray crystallography, outline the role of amino acid residues at positions E7, F8 and E10 in modulating ligand binding properties of oxygen carrying proteins.
Characterization of a null mutation in ace‐1, the gene encoding class A acetylcholinesterase in the nematode Caenorhabditis elegans
Authors: Talesa Vincenzo , Culetto Emmanuel , Schirru Nathalie , Bernardi Henri , Fedon Yann , Toutant Jean-Pierre , Arpagaus Martine
Published: July 2002

Two genes (ace‐1 and ace‐2) encode two major classes (A and B) of acetylcholinesterase (AChE) in the nematode Caenorhabditis elegans. A null mutation in ace‐1 (allele p1000) suppresses all acetylcholinesterase activity of class A. We have identified an opal mutation TG (W99)→TG (Stop) as the only alteration in the mutated gene. This leads to a truncated protein (98 instead of 620 amino acids) with no enzymatic activity. The mutation also reduces the level of ace‐1 transcripts to only 10% of that in wild‐type animals. This most likely results from a destabilization of mRNA containing the nonsense message. In contrast, compensation of class B by class A AChE in the null mutant strain ace‐2 takes place with unchanged ace‐1 mRNA level and enzymatic activity similar to class A AChE.
Autoprocessing of HSV‐1 protease: effect of deletions on autoproteolysis
Authors: Godefroy Sylvie , Guenet Chantal
Published: July 2002

HSV‐1 protease is involved in virus maturation. It is autoproteolytic and processed from a larger precursor. We have analysed the autoproteolysis of UL26 ORF and shown by in vitro‐coupled transcription and translation that the UL26 encoded protein is processed, leading to the accumulation of its N‐terminal domain. The deletion of the residues 245–248 in UL26 ORF abolishes the N‐terminal cleavage but not the C‐terminal processing. Deletion of the 3′ end of UL26 prevents production of the mature protease. These results strongly suggest that autoproteolysis is achieved in a defined order.
Temperature‐induced micellar‐lamellar transformation in binary mixtures of saturated phosphatidylcholines with sodium cholate
Authors: Polozova Alla I. , Dubachev Gennady E. , Simonova Tatyana N. , Barsukov Leonid I.
Published: July 2002

The transition states of binary mixtures of dipalmitoyl‐ and dimyristoylphosphatidylcholines with sodium cholate at the reversible temperature‐induced micellar‐lamellar transformation were characterized by turbidimetry, electron microscopy, 31P NMR and differential scanning calorimetry. This transformation is triggered by the phospholipidacyl chain melting, and appears to include two structural pathways: (i) from discoidal mixed micelles to network‐like structures composed of long interlaced rod‐like micelles, then to multilayer membrane structures, and finally to multilamellar vesicles; and (ii) from discoidal micelles to membrane fragments and finally to unilamellar vesicles.
Secondary structure in solution of two anti‐HIV‐1 hammerhead ribozymes as investigated by two‐dimensional 1H 500 MHz NMR spectroscopy in water
Authors: Sarma Ramswamy H. , Sarma Mukti H. , Rein Robert , Shibata Masayuki , Setlik Robert S. , Ornstein Rick L. , Latif Kazim A. , Cairo Alfred , Tomasi Thomas B.
Published: July 2002

Two hammerhead chimeric RNA/DNA ribozymes (HRz) were synthesized in pure form. Both were 30 nucleotides long, and the sequences were such that they could be targeted to cleave the HIV‐1 gag RNA. Named HRz‐W and HRz‐M, the former had its invariable core region conserved, the latter had a uridine in the invariable region replaced by a guanine. Their secondary structures were determined by 2D NOESY 1H 500 MHz NMR spectroscopy in 90% water and 10% D20, following the imino protons. The data show that both HRz‐M and HRz‐W form identical secondary structures with stem regions consisting of continuous stacks of AT and GT pairs. An energy mimimized computer model of this stem region is provided. The results suggest that the loss of catalytic activity that is known to result when an invariant core residue is replaced is not related to the secondary structure of the ribozymes in the absence of substrate.
The expression of esterase S gene of Drosophila virilis in Drosophila melanogaster
Authors: Sergeev Pavel V. , Panin Vladislav M. , Pavlova Galina V. , Kopantseva Marina R. , Shostak Natalia G. , Bashkirov Victor N. , Georgiev Georgii P. , Korochkin Leonid I.
Published: July 2002

Drosophila melanogaster was transformed with the esterase S gene from Drosophila virilis. This gene is strongly activated in ejaculatory bulbs of mature males of Drosophila virilis. The closely related gene from Drosophila melanogaster is activated in ejaculatory ducts. The tissue‐ and stage‐specific expression of incomplete genomic copy of the esterase S gene integrated into the Drosophila melanogaster genome is the same as in Drosophila virilis. These data show that tissue and stage specificity is determined by relatively small 5′ regulatory region of the esterase S gene. The comparison between deduced amino‐acid sequences of the esterase S of Drosophila virilis and esterase 6 of Drosophila melanogaster was performed. These sequences revealed 50% homology.
Native like structure and stability of apo AI in a n‐propanol/water solution as determined by 13C NMR
Authors: Leroy Arnaud , Lippens Guy , Wieruszeski Jean-Michel , Parra Henri-Joseph , Fruchart Jean-Charles
Published: July 2002

To elucidate the molecular details of the conformation of apolipoprotein AI (apo AI), we have developed an approach related to the solubilization of this protein in 30% n‐propanol. We have previously reported the promotion of a native‐like structure for apo AI solubilized in n‐propanol, as depicted by circular dichroism, fluorescence, and limited proteolytic digestion as compared to the lipid associated form of apo AI. In the present study, we labeled the Lys residues of apo AI with 13C by reductive methylation and used 13C NMR to confirm the formation of a native‐like structure of apo AI in this environment. Furthermore, by the above criteria (circular dichroism and 13C NMR) and by using urea and temperature as denaturing agents, we show that the denaturation of the native‐like structure of apo AI in n‐propanol is a biphasic process. These studies show that in 30% n‐propanol, apo AI contains two independently folded structural domains, of markedly different stabilities that might correspond to the amino‐terminal and the carboxy‐terminal halves of the molecule.
Human prothymosin α inhibits division of yeast Saccharomyces cerevisiae cells, while its mutant lacking nuclear localization signal does not
Authors: Pavlov Nickolay , Evstafieva Alexandra , Rubtsov Yury , Vartapetian Andrey
Published: July 2002

Effect of human prothymosin α and its mutant over‐produced in S. cerevisiae on yeast cell division was studied. Wild‐type prothymosin α appeared to block division of yeast cells. Its inhibitory action could be abolished by deletion of the last nine carboxy‐terminal amino acids of prothymosin α containing nuclear localization signal, thus pointing to the nucleus as a compartment, where prothymosin α performs its action.
Retinoic acid induces gene expression of fibroblast growth factor‐9 during induction of neuronal differentiation of mouse embryonal carcinoma P19 cells
Authors: Misuzu Seo  , Kiyoshi Noguchi
Published: July 2002

We have found that the gene expression of the ninth member of the fibroblast growth factor (FGF) family, FGF9 was induced during retinoic acid(RA)‐induced neuronal differentiation of murine embryonal carcinoma P19 cells. We have reported here the nucleotide sequence of the mouse FGF9 cDNA. The murine cDNA showed 92.4% nucleotide sequence homology to the human FGF9 cDNA and 98.2% homology to that of rats. This mouse FGF9 cDNA encoded a polypeptide consisting of 208 amino acids with amino acid sequence identical to that of rats. Only one amino acid was replaced compared to the human homolog. The highly conserved sequence homology of FGF9 suggests its functional importance. FGF9 was originally isolated from a culture medium of a human glioma cell line as a growth‐promoting factor for glial cells [5]. Upon induction of neuronal differentiation by forming cell aggregates with 10−6 M RA, the gene expression of FGF9 was increased biphasically during the first 96 hours when cells were aggregating and from 168 hours to 192 hours followed by plating onto a tissue culture dish as glia‐like cells proliferated. Neither undifferentiated P19 cells nor the cells aggregated without RA remaining undifferentiated expressed FGF9. This indicates that RA regulates the gene expression of FGF9 that may play an important role in neuronal differentiation in both early and late developmental process.
Import of sterols into mitochondria of the yeast Saccharomyces cerevisiae
Authors: Tuller Gabriele , Daum Günther
Published: July 2002

An in vitro assay was designed to study the import of radiolabeled ergosterol and cholesterol from unilamellar vesicles into isolated mitochondria of the yeast Saccharomyces cerevisiae. Supply of ergosterol to the mitochondrial surface was enhanced by a cytosolic fraction containing a lipid transfer protein, whereas no such additive to the assay was required for cholesterol transport. Both sterols reached the inner mitochondrial membrane. During import, they were detected in contact sites between the outer and the inner mitochondrial membrane supporting the idea, that these zones are sites of intramitochondrial lipid translocation. Transport of ergosterol between the outer and the inner mitochondrial membrane was not affected by addition of ATP, depletion of ATP caused by treatment of mitochondria with apyrase and oligomycin, and incubation with the uncoupler CCCP, indicating that this process is energy‐independent.
Crystallisation and preliminary X‐ray analysis of the receptor‐binding domain of human and bovine α2‐macroglobulin
Authors: Dolmer Klavs , Jenner Lasse B , Jacobsen Linda , Andersen Gregers R , Koch Trine J , Thirup Søren , Sottrup-Jensen Lars , Nyborg Jens
Published: July 2002

The receptor‐binding domains (RBDs) of human and bovine α
2‐macroglobulin (α
2M) have been isolated after limited proteolysis of methylamine‐treated α
2M with papain. Single crystals of the RBDs have been grown by vapour diffusion. Crystals of human RBD are very thin plates unsuited for data collection. However, crystals of RBD from bovine α
2M give diffraction patterns suitable for X‐ray analysis, and a complete dataset with a maximum resolution of 2.3 Å has been collected with synchrotron radiation at cryogenic temperature. The crystals belong to spacegroup P3121 or P3221 with cell parameters , .
The dimer contact area of sorghum NADP‐malate dehydrogenase: role of aspartate 101 in dimer stability and catalytic activity
Authors: Schepens Isabelle , Decottignies Paulette , Ruelland Eric , Johansson Kenth , Miginiac-Maslow Myroslawa
Published: July 2002

During thioredoxin‐mediated activation of chloroplastic NADP‐malate dehydrogenase, a homodimeric enzyme, the interaction between subunits is known to be loosened but maintained. A modeling of the 3D structure of the protein identified Asp‐101 as being potentially involved in the association between subunits through an electrostatic interaction. Indeed, upon site‐directed substitution of Asp‐101 by an asparagine, the mutated enzyme behaved mainly as a monomer. The mutation strongly affected the catalytical efficiency of the enzyme. The now available 3D structure of the enzyme shows that Asp‐101 is protruding at the dimer interface, interacting with Arg‐268 of the neighbouring subunit.
Multiprotein complexes present at the MIF motifs flanking the promoter of the human c‐myc gene
Authors: Itkes Alexander , Allegra Carmen J , Zajac-Kaye Maria
Published: July 2002

The activated c‐myc allele in Burkitt's lymphoma is associated with a clustering of somatic mutations within a discrete domain of intron I that define protein recognition sequences, designated as myc intron factors (MIF‐1, MIF‐2 and MIF‐3). We have previously shown that MIF‐1 binding activity consists of two polypeptides, myc intron binding polypeptide (MIBP1) and RFX1. In the present study we identified two polypeptides, p105 and p115, and showed that these proteins give rise to a DNA–protein complex at the MIF‐2 as well as the adjacent MIF‐1 site. In addition, we demonstrated that all four proteins interact with a novel MIF‐1 like motif upstream from the c‐myc promoter region, designated 5′MIF. These data suggest a model, where the interactions of MIBP1/RFX1 and p105/p115 with the MIF‐like sites may play a role in the promoter topology of the c‐myc gene.
Varying effects of temperature, Ca2+ and cytochalasin on fusion activity mediated by human immunodeficiency virus type 1 and type 2 glycoproteins
Authors: Jernigan Kristine M , Blumenthal Robert , Puri Anu
Published: July 2002

We examined fusion mediated by the human immunodeficiency virus type 1 (HIV‐1) and type 2 (HIV‐2) envelope glycoproteins under various experimental conditions. Incubation of HeLa cells expressing HIV‐2ROD and HIV‐2SBL/ISY envelope glycoproteins with HeLa‐CD4 target cells resulted in fusion at temperatures ≥25°C whereas fusion with cells expressing HIV‐1Lai occurred only at ≥31°C. HIV‐2 envelope glycoprotein‐mediated fusion proceeded in the absence of Ca2+ in the culture medium, whereas HIV‐1 fusion required Ca2+ ions for fusion. In contrast to HIV‐2 envelope glycoprotein fusion, incubations in the presence of the 0.5 μM cytochalasin B completely inhibited HIV‐1 envelope glycoprotein‐mediated fusion. Our results suggest that in contrast to HIV‐2, HIV‐1 fusion is dependent on dynamic processes in the target membrane.
Spontaneous lipid vesicle fusion with electropermeabilized cells
Authors: Ramos Corinne , Bonato David , Winterhalter Mathias , Stegmann Toon , Teissié Justin
Published: July 2002

Fusion is obtained between electropermeabilized mammalian cells and intact large unilamellar lipid vesicles. This is monitored by a fluorescence assay. Prepulse contact is obtained by Ca2+ when negatively charged lipids are present in the liposomes. The mixing of the liposome content in the cell cytoplasm is observed under conditions preserving cell viability. Electric conditions are such that free liposomes are not affected by the external field. Therefore destabilization of only one of the two membranes of the partners is sufficient for fusion. The comparison between the efficiency of dye delivery for different liposome preparations (multilamellar vesicles, large unilamellar vesicles, small unilamellar vesicles) is indicative that more metastable liposomes are more fusable with electropulsated cells. This observation is discussed within the framework of the recent hypothesis that occurrence of a contact induced electrostatic destabilization of the plasma membrane is a key step in the exocytosis process.
Telephone contact with patients in the year after a suicide attempt: does it affect treatment attendance and outcome? A randomised controlled study
Authors: Cedereke M. , Monti K. , Öjehagen A.
Published: July 2002

Ambivalence to treatment and repeated suicidal behaviour are well-known problems in suicide attempters. A randomised controlled study was performed to investigate the influence of repeated telephone contacts on treatment attendance, repetition of suicidal behaviour and mental health the year after a suicide attempt.

Subjects and methods

One month after their suicide attempt 216 patients were randomised to either two telephone interventions in addition to treatment as usual, or no such intervention during the subsequent year. The interventions included motivational support to attend and/or to stay in treatment. At 1 month and again after 12 months the following measurements were used: GSI (SCL-90), GAF and SSI.

Results

At follow-up treatment attendance was high and did not differ between the randomised groups. Among those with an initial treatment contact other than psychiatric, more patients in the intervention group had such contact at follow-up. The randomised groups did not differ in repetition of suicide attempts during follow-up or in improvement in GSI (SCL-90), GAF and SSI. In individuals with no initial treatment the intervention group improved more in certain psychological symptom dimensions (SCL-90).

Conclusions

Telephone interventions seem to have an effect on patients who at their suicide attempt had other treatment than psychiatric and in those with no treatment.
Green Fluorescent Protein as a Real Time Quantitative Reporter of Heterologous Protein Production
Authors: Albano C. Renee , Randers‐Eichhorn Lisa , Bentley William E. , Rao Govind
Published: July 2002

Since its cloning and commercial availability, applications of green fluorescent protein (GFP) as a reporter gene have become prevalent in many aspects of science. The attributes of GFP could also be applied to the area of heterologous protein production. The work described here represents the first experiments to use GFP as a generic tool to monitor protein production in bioprocess development. We have constructed a plasmid containing an operon fusion of the two reporter genes GFP and chloramphenicol acetyl transferase (CAT) . CAT served as a “model” recombinant protein product to demonstrate the in situ quantifiable reporting mechanism of GFP. Our results indicate there is a direct correlation between the fluorescence intensity of GFP and the functional activity of the downstream CAT protein. In addition, there is a quantitative relationship between the level of CAT protein concentration and GFP fluorescence. These experiments provide the groundwork for using GFP as an in situ reporter gene for scale‐up and process optimization of recombinant protein production.
Two‐step test: the combined use of fetal fibronectin and sonographic examination of the uterine cervix for prediction of preterm delivery in symptomatic patients
Authors: HINCZ PIOTR , WILCZYNSKI JAN , KOZARZEWSKI MAREK , SZAFLIK KRZYSZTOF
Published: July 2002

Purpose. Our purpose was to assess the possibility of combined use of fetal fibronectin testing and sonographic examination of the uterine cervix for prediction of preterm deliveries.

Methods. We prospectively evaluated 82 patients with preterm labor. In each case fibronectin testing and sonographic examination of the cervix were performed. The primary outcome measure was preterm delivery within 28 days.

Results. Seventeen point one percent of the examined women delivered within 28 days. Among the analyzed sonographic parameters of the cervix only the functional canal length was significantly correlated with delivery (21.6±7.0 mm vs. 30.1±6.5 mm, p<0.001). Positive fetal fibronectin was found in 71.4% of patients delivered within 28 days and in 7.4% delivered after 28 days (p<0.001). In multiple logistic regression analysis only positive fibronectin testing (OR 11.25, p=0.005) and functional canal length ≤20 mm (OR 8.18, p=0.027) were independently associated with preterm delivery. We propose two‐step testing: begin with the sonographic assessment of the cervix with functional canal length ≤20 mm as a positive result and >31 mm as a negative one. The fibronectin testing should be performed only in patients with length 21–31 mm. Two step testing had overall sensitivity of 86%, specificity of 90%, positive predictive value of 63% and negative of 97% for predicting delivery within 28 days.

Conclusions. The proposed combined use of the cervical sonography and fetal fibronectin testing is a practical diagnostic tool for predicting preterm delivery with higher sensitivity and negative predictive value than any of these methods alone.
Evaluation of topically applied enilconazole for the treatment of dermatophytosis in a Persian cattery
Authors: Hnilica Keith A. , Medleau Linda
Published: July 2002

Many Persian catteries have long‐standing dermatophyte infections and are particularly difficult to treat. Enilconazole is a topical antifungal agent that has demonstrated good efficacy in recent studies. Twenty‐two Persian cats naturally infected withMicrosporum canisin a breeding cattery were treated with topical 0.2% enilconazole and monitored for 180 days. The treatments were repeated every 3 days for a total of eight applications. All the cats improved clinically and became culture negative by day 28. By day 180, four cats had developed clinical dermatophytosis and all cats had positive fungal cultures. In this study, topical 0.2% enilconazole was generally well tolerated but may have caused hypersalivation, idiopathic muscle weakness and slightly elevated serum alanine aminotransferase (ALT) concentrations. This study suggests that enilconazole may be used safely with little risk to the young, aged and gravid animals.
Lack of menstrual cycle effects on hypothalamic‐ pituitary‐adrenal axis response to insulin‐induced hypoglycaemia
Authors: Long Teresa D. , Ellingrod Vicki L. , Kathol Roger G. , Christensen Laura E. , Resch David S. , Perry Paul J.
Published: July 2002

OBJECTIVE

Limited data are available on the effects of the menstrual cycle on the hypothalamic‐pituitary‐adrenal axis (HPA) function. This study evaluates HPA axis reactivity to insulin‐induced hypoglycaemia over the menstrual cycle.

PATIENTS

Twelve normal women were randomized to placebo and evaluated during three successive menstrual cycles. Menstrual phase was documented by menstrual diary and by oestradiol and progesterone levels at the time of each insulin tolerance test (ITT). Six normal men were included as a comparison in the statistical analysis.

MEASUREMENTS

Afternoon ITTs were performed initially on the second or third day of menses in women, then seven more ITTs followed at one or two week intervals during the next 10 weeks. Serum measurements of glucose, adrenocorticotrophin (ACTH) and cortisol were obtained.

RESULTS

The glucose and ACTH responses to the ITTs were similar between men and women. Cortisol levels at baseline and during the test were higher in men than in women, although the amount of change was similar. Glucose, ACTH and cortisol response to insulin‐induced hypoglycaemia did not vary over the menstrual cycle or during repeat testing in men or women.

CONCLUSIONS

These data show that it is unnecessary to control for menstrual cycle during insulin tolerance tests performed at 1600 hours. It is, however, necessary to control for the effect of sex on cortisol levels. Repeat testing more than one week apart does not appear to influence the glucose, ACTH or cortisol response to insulin stress.
Neural substrates of the tilt illusion
Authors: Wenderoth Peter , Smith Stuart
Published: July 2002

Purpose: It has been suggested that direct and indirect tilt illusions and after‐effects have different mechanisms, namely that the direct effects arise in V1 and are sensitive to differences in spatial and temporal parameters between test and inducing stimuli, whereas indirect effects arise in extra‐striate cortex and are insensitive to such parameters. When Wolfe (Vision Research 1984; 24: 1959–64) reported that large direct tilt after‐effects occurred with short test flashes, he postulated that either there are distinct mechanisms which process brief and longer duration stimuli or that there are distinct mechanisms that are not primarily concerned with duration but are differentially responsive to temporal parameters amongst several others.

Results: In three experiments we demonstrate that large direct tilt illusions can be induced when parameters other than duration are manipulated, including contrast and spatial frequency, and that such large effects can occur when stimulus parameters are chosen to favour preferentially either the transient (magnocellular‐like) system or the sustained (parvocellular‐like) system.

Conclusions: These results are thus consistent with Wolfe’s second hypothesis. None of these stimulus manipulations had any effect on indirect tilt illusions, consistent with previous findings and hypotheses about the different mechanisms of the direct and indirect effects.
Predicting the dynamics of antiviral cytotoxic T‐cell memory in response to different stimuli: Cell population structure and protective function
Authors: Bocharov G , Klenerman P , Ehl S
Published: July 2002

This paper examines the numerical and functional consequences of various stimuli on antiviral CD8+ T‐cell memory using a mathematical model. The model is based upon biological evidence from the murine model of infection with lymphocytic choriomeningitis virus (LCMV) that the phenotype of immunological memory represents low‐level responses driven by various stimuli, and the memory CTL population is partitioned between resting, cycling and effector cells. These subpopulations differ in their lifespan, their potential to mediate antiviral protection and in the stimuli needed for their maintenance. Three types of maintenance stimuli are examined: non‐antigen‐specific (bystander) stimulation, persisting antigen stimulation and reinfection‐mediated stimulation. The modelling predicts that: (i) stable persistence of CTL memory requires the presence of either bystander or antigen‐specific stimulation above a certain threshold depending on the sensitivity of memory CTL to stimulation and their life‐span; (ii) a relatively low level of stimuli (approximately 104 fold less on a per CTL basis compared to acute infection) is needed to stabilize the expanded memory CTL population; (iii) the presence of CTL subsets in the memory pool of different activation states and lifespans ensures the robustness of memory persistence in the face of temporal variation in the low‐level stimuli and; (iv) an ‘optimal’ population structure of the memory CTL pool, in terms of immediate protection, requires the presence of both activated cycling and effector CTL. For this, persisting antigen alone or synergistically with bystander signals provide the appropriate stimulation, so that the stimuli equivalent to approximately 30 p.f.u. of LCMV in the spleen are sufficient to maintain approximately 105–106 specific CTL in the memory pool. These observations are relevant both to our understanding of natural protective immunity and to vaccine design.
Accuracy of ultrasonic detection of the uterus in normal newborn infants: implications for infants with ambiguous genitalia
Authors: Kutteh W. H. , Santos‐Ramos R. , Ermel L. D.
Published: July 2002

Every year approximately one in 5000 babies is born with ambiguous genitalia, a condition that requires immediate sex assignment if possible. We investigated whether transabdominal ultrasonography with the use of a linear array high‐resolution 7.5‐MHz transducer would enhance the accuracy of detecting the uterus in the newborn.

One hundred mothers who delivered normal, term infants (> 36 weeks and > 2500 g) gave their informed consent for the investigation. Each infant was placed in an unmarked bassinet, external genitalia were covered, and ultrasound examinations were performed by the same examiner (R. S.) who was blinded to the sex of the infant.

The neonatal uterus was identified in 47 of 50 female infants (94% sensitivity) and the absence of a uterus was correctly predicted in 49 of 50 male infants (specificity 98%). The average length of the neonatal uteri 1 day after birth was 3.2 ± 0.5 cm and the total volume was 3.5 ± 0.9 cm³. An endometrial strip could be identified in 98% of neonatal uteri.

We conclude that the use of the high‐resolution 7.5‐MHz transducer available in commercial ultrasound equipment is an accurate method for the detection of the neonatal uterus. Infants born with ambiguous genitalia who have a uterus will almost always be assigned the female sex. Infants with ambiguous genitalia but without a uterus will have male pseudohermaphroditism. Copyright © 1995 International Society of Ultrasound in Obstetrics and Gynecology
Observation of quantum size effect in the resistivity of thin, gray tin epilayers
Authors: Tu Li-Wei , Wong George K. , Ketterson John B.
Published: July 2002

Thin, gray tin films, with thicknesses from 50 to 375 Å, have been grown on (001) CdTe wafers by the molecular beam epitaxy technique. Resistivity measurements in the intrinsic region show a thickness-dependent band gap. Quantum size effect theory using a square well potential has been used to interpret the experimental data.
Terahertz beam generation by femtosecond optical pulses in electro-optic materials
Authors: Xu L. , Zhang X.-C. , Auston D. H.
Published: July 2002

We have observed subpicosecond pulses having terahertz bandwidths generated from electro-optic materials by using femtosecond optical pulses. The time-resolved radiation signal clearly indicates that the terahertz radiation comes from the regions within the coherence length near the surfaces of electro-optic materials under the phase-mismatched condition. When the high-energy femtosecond laser pulses are used, this method provides a new way to generate large amplitude broad bandwidth terahertz radiation efficiently.
Nuclear reaction analysis profiling as direct evidence for lithium ion mass transport in thin film ‘‘rocking-chair’’ structures
Authors: Goldner R. B. , Haas T. E. , Arntz F. O. , Slaven S. , Wong K. K. , Wilkens B. , Shepard C. , Lanford W.
Published: July 2002

A nuclear reaction analysis technique using the p,γ reaction, 7Li(p,γ)8Be, occurring at approximately 440 keV, (half-width≊12 keV), has been utilized to determine the lithium concentration profiles in multilayer electrochromic window (‘‘smart window’’)/rechargeable battery cells when in their ‘‘colored’’/charged and ‘‘bleached’’/discharged states. The lithium profiles have been observed to shift according to the cells’ states, thereby providing direct experimental evidence for the so-called rocking-chair model for such structures.
Epitaxial growth of iridium and platinum films on sapphire by metalorganic chemical vapor deposition
Authors: Vargas Roberto , Goto Takashi , Zhang Wei , Hirai Toshio
Published: July 2002

Ir and Pt epitaxial films were grown on (0001), (112̄0), and (011̄2) sapphire by metalorganic chemical vapor deposition using Ir- or Pt-acetylacetonate precursors. The epitaxial growth was achieved at deposition temperatures between 500 and 600 °C with the addition of oxygen to the source vapor. The film orientation and epitaxial relationships between films and substrates were determined by x-ray diffraction, x-ray pole figures, and reflection high energy electron diffraction. Ir films on (112̄0) sapphire grow in [100] orientation. Ir or Pt films on (011̄2) and (0001) sapphire grow in [111] orientation. Ir films on (0001) sapphire contain two in-plane orientations related by a 180° rotation, while Pt films containing only one in-plane orientation can be obtained on (011̄2) and (0001) sapphire.
Multidipole confinement of argon and potassium plasmas
Authors: Bosch Robert A. , Merlino Robert L.
Published: July 2002

Multidipole confinement of an argon discharge plasma and a potassium plasma produced by surface ionization was investigated. In both cases, a large volume of uniform density quiescent plasma was produced in the central region of low magnetic field strength. Measurements of electron and ion densities and space potentials suggest that self-consistent electrostatic fields resulted in crossfield (to B) ion confinement and that the cusp leak widths were determined by a noncollisional mechanism (e.g., Bohm diffusion). A comparison of the nondischarge potassium plasmas produced with and without multidipole confinement indicates that the ion confinement time was improved by a factor of ∼15 by the multidipole magnetic field.
Voltage-controlled acousto-optic phase shifter
Authors: Ehrlich Michael J. , Phillips Louis C. , Wagner James W.
Published: July 2002

A novel solid-state technique for effecting a phase shift in a light beam has been developed utilizing a voltage-controlled rf phase shifter and two acousto-optic modulators. The acousto-optic phase-shifting technique provides a simple and accurate method of phase stepping, and is a solid-state alternative to conventional mechanical piezoelectric pusher techniques. Accuracy and repeatability of the prototype system were better than 1°. The technique lends itself quite well to situations where both heterodyne and quasi-heterodyne techniques are used for interferometric analysis.
Variable-heating-rate wire-mesh pyrolysis apparatus
Authors: Gibbins J. R. , King R. A. V. , Wood R. J. , Kandiyoti R.
Published: July 2002

An electrically heated wire-mesh apparatus for pyrolysis studies has been developed which uses computer-driven feedback control for the heating system and thus can apply virtually any time-temperature history to the sample. Internal components are water cooled to prevent heat buildup during long runs. Using this system, coal pyrolysis has been studied at heating rates from 0.1 to about 5000 K/s and temperatures up to 1000 °C. Alternating current is used for heating; this allows the thermocouples to be attached directly to the sample holder and also makes power regulation relatively simple. For atmospheric-pressure experiments, a gas sweep can be forced through the sample holder to remove products from the heated zone and also to concentrate them in a trap which can be removed from the apparatus and weighed to establish tar yields directly. Although the design is optimized for atmospheric-pressure operation, relatively simple modifications allow operation under vacuum or at pressures of up to 160 bars in inert gas or hydrogen. The apparatus has been used to investigate a number of phenomena in coal pyrolysis and, most significantly, has demonstrated the existence of a heating-rate effect which is independent of reactor geometry.
A metrological electron microscope system for microfeatures of very large scale integrated circuits
Authors: Hatsuzawa Takeshi , Toyoda Kouji , Tanimura Yoshihisa
Published: July 2002

An absolute linewidth measuring system, based on a scanning electron microscope (SEM), is developed to measure critical dimension (CD) of VLSIs (very large scale integrated circuits). The system employs two laser interferometers for the absolute scales of the X and Y axes, while the electron beam is used to detect microfeatures on the silicon chips. The resolutions of the interferometers are 0.8 nm for X and 20 nm for Y. An LaB6 filament is used for the electron gun and the system is operated under low acceleration voltages of around 1 kV for noncharging measurements. In this article, the principle of the measurements, the electron beam system, the scanning mechanism, and the laser interferometer are described including basic experimental results.
Lifetime-selective fluorescence imaging using an rf phase-sensitive camera
Authors: Lakowicz Joseph R. , Berndt Klaus W.
Published: July 2002

We report the creation of two-dimensional fluorescence lifetime images, based on a sinusoidally modulated image intensifier that is operated as a radio-frequency phase-sensitive camera, synchronized to a mode-locked and cavity dumped picosecond dye laser. By combining the image intensifier with a CCD camera and applying digital image processing, lifetime-selective signal suppression can be realized even for fluorophores with comparable lifetimes. This phase-sensitive technique can be used to create fluorescence lifetime images, that is, images in which the contrast is based upon the fluorescence lifetimes rather than upon local probe concentration and/or intensity. Because the lifetimes of many dyes are sensitive to the chemical environments surrounding the fluorophore, fluorescence lifetime imaging (FLIM) can reveal the local chemical composition and properties of the molecular environment that surrounds the fluorophore. As an example we created images of rhodamine 6G (4 ns) and rhodamine B (1.5 ns) solutions in which the difference in lifetimes results in 100% contrast, whereas the total fluorescence intensity is similar. In order to estimate the time resolution obtainable with our phase-sensitive imaging setup, we also performed measurements using distance-selective suppression of optical signals backscattered from laser-illuminated targets. In these studies, we have created distance-selective images with a resolution of 3.75 cm, which corresponds to a lifetime resolution of 0.25 ns for fast-decaying fluorophores. Since we observed nearly 100% contrast for this 0.25 ns difference, still smaller distances and/or lifetime differences could be observed, which seems to imply some advantages of phase fluorometric lifetime imaging. Using these same intensifiers in the pulse-gating mode one expects a typical 5 ns gating time, which result in a distance resolution of only 75 cm. The distance-selective imaging principle has the potential for manifold applications related to robotics, construction, and even to spacecraft maneuvering. Fluorescence lifetime imaging, in combination with fluorescence microscopy, can have numerous applications to biochemistry, biophysics, and cell physiology.
Design and operation of the multipulse Thomson scattering diagnostic on DIII-D (invited)
Authors: Carlstrom T. N. , Campbell G. L. , DeBoo J. C. , Evanko R. , Evans J. , Greenfield C. M. , Haskovec J. , Hsieh C. L. , McKee E. , Snider R. T. , Stockdale R. , Trost P. K. , Thomas M. P.
Published: July 2002

This paper describes the design and operation of a 40 spatial channel Thomson scattering system that uses multiple 20-Hz Nd:YAG lasers to measure the electron temperature and density profiles periodically throughout an entire plasma discharge. As many as eight lasers may be fired alternately for an average measurement frequency of 160 Hz, or they may be fired in rapid succession (<10 kHz), producing a burst of pulses for measuring transient events. The high spatial resolution (1.3 cm) and wide dynamic range (10 eV–20 keV) enable this system to resolve large electron density and temperature gradients formed at the plasma edge and in the scrape-off layer during H-mode operation. These features provide a formidable tool for studying L–H transitions, edge localized modes (ELMs), beta limits, transport, and disruptions in an efficient manner suitable for large tokamak operation where shot-to-shot scans are impractical. The scattered light is dispersed by interference filter polychromators and detected by silicon avalanche photodiodes. Laser control and data acquisition are performed in real time by a VME-based microcomputer. Data analysis is performed by a MicroVAX 3400. Additional features of this system include real-time analysis capability, full statistical treatment of error bars based on the measured background light, and laser beam quality and alignment monitoring during plasma operation. Results of component testing, calibration, plasma operation, and error analysis are presented.
Satellite borne energetic ion mass spectrometer for three-dimensional measurement of velocity distribution
Authors: Hirahara M. , Mukai T.
Published: July 2002

For research of the magnetospheric plasma, we have developed a new type of energetic ion energy-mass spectrometer on board a spinning spacecraft, which is capable of measuring three-dimensional velocity distributions of different ion species simultaneously with a wide angular coverage and high time resolution. It can cover the energy-mass range of 5–400 amu keV/e, while lower-energy ions can also be measured by using preacceleration. The fan-shaped field of view is 130°×10°, with the longer dimension being divided into five sectors. The instrument consists of three major elements with axially symmetric configuration in order to cover the wide angular acceptance. The first stage is a tandem energy analyzer which consists of a spherical analyzer and a saddle-type poloidal analyzer. The second is an orange-type mass spectrometer with multiple sector fields. The third is an array of microchannel plate detectors with one-dimensional position sensitive anodes for snapshot measurement of mass distributions in different incident angles. Nearly optimum design parameters of each element are determined by means of a numerical ray-tracing simulation of ions trajectories. The instrumental characteristics are also investigated experimentally by using a calibration facility. The experimental results are generally in good agreement with those obtained by the numerical method. The present instrument can resolve the dominant ion species (H+,He2+,He+,O2+,O+) in the Earth’s magnetosphere, which play a crucial role as tracers to study the origin of plasmas. Finally, future possible improvements are also discussed.
Tunable photoemission with harmonics of subpicosecond lasers
Authors: Haight R. , Peale D. R.
Published: July 2002

Soft x-ray photons, generated by the interaction of intense 610 nm subpicosecond laser pulses with rare gases, are used to carry out tunable angle-resolved photoemission on a number of systems. When the intensity at the focus of the input radiation exceeds ∼1014 W/cm2 significant quantities of harmonic photons at odd multiples of the input 610 nm (2.04 eV) light are produced. To date, harmonics from the 5th (10.2 eV) to the 25th (51 eV) have been generated with fluxes sufficient for generating photoemission spectra. The experimental apparatus for harmonic generation and several experiments demonstrating the applications of this light are described.
New type of embedded laser Doppler velocimeter for measurement of rotary wings boundary layer
Authors: Favier D. , Maresca C. , Nsi Mba M. , Berton E. , Agnes A.
Published: July 2002

An experimental method has been developed to determine the velocity profiles across the boundary layer of rotary wings. The measurement, based on laser Doppler velocimetry, has been tested on a helicopter rotor blade in hover. The main components of the prototype are embedded in an untwisted blade. The beams converging at the measurement volume, which can be moved along perpendicular to the surface, and the signals backscattered by flow particles, are collected through rotating fiber optic cables to a transmitter insuring the connection with fixed components (laser source, photomultipliers, burst spectrum analyzer, computer, etc.). Measurements, performed in a frame linked to the rotating blade for one radial distance from the rotation axis and at a chord abscissa x/c=0.25, have involved the tangential velocity component (chordwise) and the crossflow component (spanwise). The boundary layer has been explored at different rotating speeds of the blade. The accuracy of velocity components measurements has been evaluated in the region very close to the wall and far from the wall. The velocity profiles obtained in different hovering test conditions have shown the efficiency of the present embedded laser Doppler velocimeter method, which can also be applied to rotors in forward flight, wind turbines, etc. Undoubtly, the new database obtained on the rotating boundary layer will constitute an essential support for the physical models and computational works.
A laser-locked cavity ring-down spectrometer employing an analog detection scheme
Authors: Spence T. G. , Harb C. C. , Paldus B. A. , Zare R. N. , Willke B. , Byer R. L.
Published: July 2002

A system is described that employs a diode-pumped Nd:YAG continuous-wave laser source servolocked to a three-mirror optical cavity and an analog detection circuit that extracts the ring-down rate from the exponentially decaying ring-down waveform. This scheme improves on traditional cavity ring-down spectroscopy setups by increasing signal acquisition rates to tens of kilohertz and reducing measurement noise sources. For example, an absorption spectrum of a weak CO2 transition at 1064 nm is obtained in less than 10 s at a spectral resolution of 75 kHz employing a cavity with an empty-cavity ring-down decay lifetime of 2.8 μs and a total roundtrip path length of 42 cm. The analog detection system enables laser frequency scan rates greater than 500 MHz/s. The long-term sensitivity of this system is 8.8×10−12 cm−1 Hz−1/2 and the short-term sensitivity is 1.0×10−12 cm−1 Hz−1/2.
Direct extraction of the electron tunneling effective mass in ultrathin SiO2
Authors: Brar B. , Wilk G. D. , Seabaugh A. C.
Published: July 2002

Electron transport in ultrathin (tox<40 Å) Al/SiO2/n−Si structures is dominated by direct tunneling of electrons across the SiO2 barrier. By analyzing the tunneling currents as a function of the SiO2 layer thickness for a comprehensive set of otherwise identical samples, we are able to extract an effective mass for the tunneling electron in the SiO2 layer. Oxide films 16–35 Å thick were thermally grown in situ in a dry oxygen ambient. The oxide thicknesses were determined by capacitance–voltage measurements and by spectroscopic ellipsometry. The tunneling effective mass was extracted from the thickness dependence of the direct tunneling current between an applied voltage of 0 and 2 V, a bias range that has not been previously explored. Employing both a parabolic and a nonparabolic assumption of the E−κ relationship in the oxide forbidden gap, we found the SiO2 electron mass to be mP*=0.30±0.02me, and mNP*=0.41±0.01me, respectively, independent of bias. Because this method is based on a large sample set, the uncertainty in the mass determination is significantly reduced over prior current-voltage fitting methods.
Temperature derivatives of the fundamental elastic constants of isotropic materials
Authors: Ballandras S. , Gavignet E. , Bigler E. , Henry E.
Published: July 2002

The calculation of the first temperature derivatives of the fundamental elastic constants proposed by Sinha and Tiersten [J. Appl. Phys. 50, 2732 (1979)] for quartz is applied to isotropic materials. Numerical applications are provided for metals used in acoustic wave devices and which may affect the thermal properties of the latter.
Temperature dependent lasing characteristics of multi-stacked quantum dot lasers
Authors: Shoji Hajime , Nakata Yoshiaki , Mukai Kohki , Sugiyama Yoshihiro , Sugawara Mitsuru , Yokoyama Naoki , Ishikawa Hiroshi
Published: July 2002

Temperature dependence of self-formed quantum dot lasers with a multi-stacked dot layer has been investigated in detail. Lasers oscillating at different subbands exhibit different behaviors against temperature change both in the spectral characteristics and the threshold current. A discontinuous shift of lasing wavelength from the second subband to the ground state is observed with lowering temperature, which is strongly related to emission efficiency of quantum dots and thermal excitation of carriers to higher-order subbands. High characteristic temperature over 300 K has been achieved in a laser with high-reflection coating on both facets in the temperature range 60–200 K.
Direct evidence for Vögel–Fulcher freezing in relaxor ferroelectrics
Authors: Glazounov A. E. , Tagantsev A. K.
Published: July 2002

Direct evidence for freezing in two relaxor ferroelectrics, PbMg1/3Nb2/3O3 and PbSc1/2Ta1/2O3, at a certain temperature Tf≠0 K was obtained from the temperature dependence of the maximum relaxation time, τmax. It was shown that τmax(T) follows the Vögel–Fulcher (VF) law, and tends toward infinity as temperature approaches Tf. The freezing temperature Tf derived from τmax(T) coincides with the value of Tf obtained from the fit of frequency, ω, dependence of the temperature, Tmax, of the dielectric permittivity maximum to the same VF law. Thus, this result solves the controversy that the VF law for ω(Tmax) may not correspond to the freezing of the spectrum.