bluuebunny/crossref_metadata_2025 huggingface dataset:
The WASH study (Warfarin/Aspirin Study in Heart failure) rationale, design and end‐points
Authors:   The WASH study Steering Committee and Investigators
Published: July 2002

Background:

Athero‐thrombotic events are common among patients with heart failure but there is no evidence that anti‐thrombotic therapy is safe or effective in this clinical setting.

Aims and Methods:

The WASH study is a prospective, randomised, open‐label, blinded‐end‐point pilot study comparing the outcome of management without anti‐thrombotic therapy compared to treatment with aspirin or warfarin in three parallel arms in patients with chronic heart failure due to left ventricular systolic dysfunction. The primary aim of the study is to assess the feasibility of conducting a large study in which one‐third of patients would be randomised to no anti‐thrombotic therapy. The principal secondary aim of the study is to compare the effects of treatment on the combined end‐point of death, non‐fatal myocardial infarction and non‐fatal stroke.

Results:

279 patients have been randomised and by study close there were 626 patient‐years of follow‐up. The majority of patients randomised had heart failure secondary to coronary artery disease. We expect to commence data analysis in early 1999 and report later in that year.

Conclusions:

This pilot study demonstrated that it is technically feasible to conduct a study that included a no anti‐thrombotic treatment arm but that recruitment to such a study would be slow and costly. A large trial comparing the effects of aspirin, warfarin and clopidogrel in three separate groups without a placebo arm is now intended.
Improvement of Heterologous Protein Productivity by Controlling Postinduction Specific Growth Rate in Recombinant Escherichia coli under Control of the PL Promoter
Authors: Lim Hyung‐Kwon , Jung Kyung‐Hwan
Published: July 2002

To develop the optimal operational strategy for the PL promoter of interferon (IFN)‐γ‐producing Escherichia coli, some rational medium feeding methods, carried out just after temperature induction to control the postinduction specific growth rate (μi), were designed. Using experimental data from various batch cultures, we correlated μi with specific IFN‐γ production rate (qpi) to find out how μi just after induction affected qpi. It was revealed that sustaining μi above a certain value after induction was the key factor for high‐level production of IFN‐γ. Stepwise and constant‐rate medium feeding, in which the temperature induction was done simultaneously, at the late‐exponential growth phase of batch culture resulted in a dramatic extension of the production period as a result of sustaining μi after temperature induction. These methods led to the overcoming of harsh conditions after temperature induction and the improvement of IFN‐γ productivity. Finally, by both a high‐cell‐density culture using an exponential fed‐batch culture for cell growth and constant‐rate medium feeding after temperature induction for IFN‐γ production, we accomplished an increase in IFN‐γ production by 23‐fold, 7.43 g/L, as compared with that of batch culture.
Biochemical characterization and subcellular localization of human copper transporter 1 (hCTR1)
Authors: KLOMP Adriana E.M. , TOPS Bastiaan B.J. , vandenBERG Inge E.T. , BERGER Ruud , KLOMP Leo W.J.
Published: July 2002

The human copper transporter 1 gene (hCTR1) was previously identified by functional complementation in ctr1-deficient yeast. Overexpression of hCTR1 in wild-type yeast leads to increased sensitivity to copper toxicity, and mice with a homozygous disruption at the Ctr1 locus die early during embryogenesis. It is proposed that hCTR1 is responsible for high-affinity copper uptake into human cells, but the underlying molecular mechanisms are unknown. To begin to investigate the biochemical characteristics of hCTR1, a polyclonal antiserum was raised against recombinant hCTR1-fusion peptides. Biosynthetic studies using this antiserum revealed that hCTR1 was synthesized as a precursor protein of 28kDa containing N-linked oligosaccharides, and is then converted to a mature protein of approx. 35kDa, which is ubiquitously expressed. Immunofluorescence studies showed that subcellular hCTR1 localization differed markedly between cell types. In some cell lines, hCTR1 was located predominantly in an intracellular vesicular perinuclear compartment, and in others hCTR1 was located predominantly at the plasma membrane. In contrast with the copper export P-type ATPases mutated in Wilson disease and Menkes disease, the localization of hCTR1 was not influenced by copper concentrations. Inhibition of endocytosis by methyl-β-cyclodextrin caused a partial redistribution of hCTR1 to the cell surface of HeLa cells. Taken together, the results in this study suggest a cell-specific control of copper uptake, which involves subcellular localization of the hCTR1 protein.
Apparent cure of Graves‐Basedow disease after sibling allogeneic bone marrow transplantation
Authors: Díez Santiago , Banias Helena , Díez‐Martin José L. , Briz Montserrat , Estrado Janvier , Barceló Balbino
Published: July 2002

Evidence that allogeneic bone marrow transplantation (BMT) can cure or alter the course of intractable autoimmune diseases comes from both extensive experimental work in animal models and anecdotal case reports in humans.

We describe a female patient diagnosed as having severe aplastic anaemia (SAA), hyperthyroidism and ophthalmopathy of Graves‐Basedow disease who received a BMT from her histocompatible sister.

Fifty‐three months after BMT, complete remission of hyperthyroidism and ocular signs persists. The SAA is cured and she is free of any chronic graft‐versus‐host disease (GVHD).

In the early post‐BMT period, PCR analysis of bone marrow and peripheral blood cells confirmed a complete chimerism of donor origin. Thus, it is plausible to attribute the resolution of the patient's thyroid hyperfunction and opththalmopathy to the replacement of the host immune system.
Normal human immunoglobulin G4 is bispecific: it has two different antigen‐combining sites
Authors: Schuurman J. , Van Ree R. , Perdok G. J. , Van Doorn H. R. , Tan K. Y. , Aalberse R. C.
Published: July 2002

Unlike other immunoglobulin G (IgG) subclasses, IgG4 antibodies in plasma have been reported to be functionally monovalent. In this paper we show that the apparent monovalency of circulating IgG4 is caused by asymmetry of plasma IgG4. A large fraction of plasma IgG4 molecules have two different antigen‐binding sites, resulting in bispecificity. Sera from patients with IgG4 antibodies to both house dust mite and grass pollen induced cross‐linking of Sepharose‐bound grass pollen antigen to radiolabelled house dust mite allergen Der p I. This bispecific binding activity was not observed in sera with IgG4 antibodies to either grass pollen or house dust mite exclusively. Depletion of IgG4 antibodies resulted in disappearance of the bispecific activity. By size exclusion chromatography we excluded the possibility that bispecific activity was caused by aggregation of IgG4 antibodies. These results indicate that circulating (polyclonal) IgG4 antibodies have two different antigen‐binding sites and therefore are functionally monovalent antibodies.
Biogeographical patterns of benthic macroinvertebrates in the Southeastern Pacific littoral
Authors: Lancellotti D. A. , Vásquez J. A.
Published: July 2002

Aim To use new collections and taxonomic reviews of the Chilean coastal biota, and studies on biodiversity on a reappraisal of Southeastern Pacific littoral biogeography.

Location The temperate coastline of the Southeastern Pacific, extending over 6000 km from northern Peru to the southern tip of Chile.

Methods Records of coastal macroinvertebrates were assigned to ten geographic zones along the Chilean coast. The Spearman rank correlation coefficient, ρ, was used to establish the relationship between the total number of species and the number of single records for each zone. Regions and underlying faunal gradient were verified via an unweighted paired group method using arithmetic averages (UPGMA), and ordination non‐metric multidimensional scaling (nMDS) analysis based on a disagreement distance matrix of presence/absence data. Abundance down‐weighting was preferred to rare species down‐weighting, owing to the nature of the records, where a larger number of references for a given taxon did not necessarily indicate a greater abundance or commonness. The dissimilarity matrices between the different zones were used to establish the degree of agreement between the different levels of analysis, using a weighted Spearman rank correlation coefficient ρw. Statistical significance was established using a randomization (permutation) test.

Main conclusions Analysis of new macroinvertebrate data and taxonomic reviews of the Chilean coastal fauna indicates a Transitional‐Temperate Region for the Southeastern Pacific littoral, located between 35°S and 48°S where a gradual mixing and replacement of species negates previous hypotheses on the existence of a marked distributional break at 42°S.
An exploratory study into Dutch consumers’ experiences with implementing dietary recommendations to reduce fat intake
Authors: van Assema P. , Kempers B. , Brug J. , Glanz K.
Published: July 2002

Background: Nutrition education messages for the Dutch public include many different dietary recommendations for reducing fat intake, e.g. use low‐fat milk, reduce meat intake, etc. The purpose of this exploratory study was to assess which types of dietary recommendations are difficult to implement for consumers and which are easier.

Methods: Twenty‐five recommendations that are often used in educational messages were selected and classified by type of recommendation. Two classifications were used for each recommendation: the product group the recommendation relates to, and the recommended type of behavioural change. Sixty‐six adults of all ages were recruited to implement as many of the recommendations as possible over a period of four weeks. Beforehand, participants completed a food frequency list to assess which recommendations they had already implemented. After the 4 weeks, they completed a written questionnaire measuring intention, implementation and perceived difficulties for each of the remaining recommendations.

Results: Based on the classification according to product group, recommendations concerning spreads and butter, sauces and gravy were rated as least difficult to implement, while recommendations on snacks were most difficult to implement. As far as the type of behavioural change recommendations, preparing a product differently was easiest to implement, while recommendations to eat less of a high‐fat product were considered as most difficult to implement.

Conclusions: The results show that there are differences in difficulties consumers experience in implementing different types of recommendations for reducing fat intake. Further research should extend this line of inquiry to help design optimally effective nutrition interventions.
A stochastic tessellation for modelling and simulating colour aluminium grain images
Authors: LEE T. C. M.
Published: July 2002

The work described in this article is motivated by the need for modelling and simulating some colour aluminium grain images. One possible approach for modelling these colour aluminium grain images is to approximate the images by trivariate piecewise constant functions corrupted by additive and correlated noise. Such a piecewise constant function modelling approach is naturally divided into three parts: shape, colour and noise. The main focus of this article is to present a new tessellation model which can be applied to model the shape characteristics of the aluminium grain images. One special feature of the new tessellation model is that it is capable of generating tessellation patterns having rough boundaries. Some empirical properties and variants of the tessellation model are also described. Then, as a secondary focus, this article describes models and methods for modelling the observable colour values and noise of the aluminium grain images. Both visual and empirical comparisons between real and simulated images suggest that our modelling is reasonable.
Non‐uniform systematic sampling in stereology*
Authors: Dorph‐Petersen K.‐A. , Gundersen H. J. G. , Jensen E. B. V.
Published: July 2002

Non‐uniform systematic sampling designs in stereology are studied. Various methods of constructing non‐uniform systematic sampling points from prior knowledge of the measurement function are presented. As an example, we consider area estimation from lengths of linear intercepts. The efficiency of two area estimators, based on non‐uniform sampling of parallel lines, is compared to that of the classical 2D Cavalieri estimator, based on uniform sampling, in a sample of planar profiles from transverse sections of 41 small myelinated axons. The comparison is based on simulations. It is concluded that for profiles of this type one of the non‐uniform sampling schemes is more efficient than the traditional uniform sampling scheme. Other examples where non‐uniform systematic sampling may be used are in area estimation from lines emanating from a fixed point, area estimation from concentric circles or spirals and curve length estimation from sweeping lines. It is shown that proportional‐to‐size sampling is a special case of non‐uniform systematic sampling. Finally, the effect of noise in the observations is discussed.
Response of One‐Humped Camel (Camelus dromedarius) to Intravenous Glucagon Injection and to Infusion of Glucose and Volatile Fatty Acids, and the Kinetics of Glucagon Disappearance from the Blood
Authors: Abdel‐Fattah M. , Amer H. , Ghoneim M. A. , Warda M. , Megahed Y.
Published: July 2002

The effects of glucagon injection and infusion of glucose and volatile fatty acids were studied in one‐humped camels. Twenty adult male camels were divided into four equal groups. The first group was infused with physiological saline and served as a control. The second group was injected with a single dose of glucagon, the third group was infused with glucose (50 %) in sterile saline, and the fourth group was infused with a volatile fatty acid (VFA) mixture. In the first, third and fourth groups, sampling was performed before the beginning of infusions (control time), and at 15, 30, 60 and 120 min post‐infusion. Plasma glucagon concentrations were monitored in the second group at 5, 10, 15, 20, 30, 45, 90, 105 and 120 min after injection. For glucagon injection, glucose concentration peaked at 15 min post‐injection, and tended to decrease thereafter. Plasma glucose concentrations showed significant rises above the basal value at all times after glucose infusion. VFA infusion had no apparent effect on plasma glucose concentration. After injection of glucagon, the plasma lactate concentration dropped significantly at 15 and 30 min, then increased gradually until it reached the original concentration of lactate at 120 min. However, glucose infusion elevated the plasma lactate concentration only at the end of the infusion period. A decrease in plasma lactate was observed at 60 min after VFA infusion. The present investigation provides evidence that the glucagon level in camels is higher than that in other ruminants and in man, and suggests that this is a probable species specificity, which would explain the higher level of glucose in the blood of camels than in that of other ruminants. The disappearance curve of injected glucagon had, as in other ruminants, an exponential two‐compartment function. The hormone was rapidly distributed and was eliminated with a high rate of clearance.
Factors associated with use of glaucoma medications in a population of older people: The Blue Mountains Eye Study
Authors: Hourihan Fleur , Mitchell Paul
Published: July 2002

Purpose: To examine factors associated with use of glaucoma medications in a population of older people.

Methods: The Blue Mountains Eye Study examined 3654 people aged 49–97 years. Participants completed an interviewer‐administered questionnaire which included information on current medication use. Open‐angle glaucoma (OAG) was diagnosed if matching glaucomatous visual field defects and optic disc cupping were present. Ocular hypertension (OH) was diagnosed in subjects without glaucomatous disc and field changes who had an intraocular pressure (IOP) of ≥ 22 mmHg in either eye or who had lower IOP levels but reported treatment with glaucoma medication.

Results: Use of glaucoma medication was reported by 3.3% of persons in this population (119/3644), including 44% of OAG and 28% of OH cases. Among newly diagnosed OAG and OH cases, 30% had never visited an ophthalmologist. Factors associated with a previous diagnosis of OAG or OH in a multivariate model included use of one or more general medications (OR 7.5; 95% CI 2.5–22.9), a history of other eye disease (OR 3.4; 95% CI 1.9–6.2) and first‐degree family history of glaucoma (OR 3.6; 95% CI 1.8–7.2).

Conclusions: Glaucoma screening may need to target individuals with OAG risk factors who are less likely to visit a general practitioner or ophthalmologist.

Key words: glaucoma, glaucoma medication, Australia, older population.
Comparison of colour Doppler imaging of orbital vessels in elderly compared with young adult patients
Authors: Gillies W E , Brooks A M V , Scott M , Ryan L
Published: July 2002

Purpose: Colour Doppler imaging provides an estimate of the velocity of blood flow in vessels supplying the eye.

Methods: To assess changes in orbital blood flow with age, we used a method to study peak systolic velocity in 20 young normal patients, mean age 25.2 ± 2.4 years and 30 elderly normal patients, mean age 69.5 ± 7.9 years.

Results: Peak systolic velocity was significantly higher in the central retinal artery and the temporal division of the posterior ciliary artery in elderly patients. There was greater variation in the peak systolic velocity readings in the distal part of the ophthalmic artery in the elderly than in the younger group. There was greater variation in the pulsatility index in the central retinal artery in young subjects.

Conclusions: Though not large, these differences suggest changes in the orbital blood vessels with age which could affect the development of disease processes in elderly patients. These changes should be taken into account when assessing blood flow in elderly patients.
Australian Experience with the Freehand System®for Restoring Graspin Quadriplegia
Authors: Carroll Sara , Coope Catherine , Brown Douglas , Sormann Gerard , Flood Stephen , Denison Michael
Published: July 2002

Background: The purpose of the present study was to document the value of
an implanted multichannel neuroprosthesis (Freehand Systemê) for
restoring hand grasp in the first Australians to receive this device.

Methods: Hand function in C5 quadriplegic patients was assessed via measurement
of pinch forces, a grasp release test and tests of activities of daily living (ADL).
Comparisons were made between presurgery scores and scores recorded after rehabilitation
when the neuroprosthesis was and was not in use.

Results: A significant difference for both lateral pinch (P = 0.003)
and palmar grasp (P = 0.003) was found between forces recorded with and without
the use of the neuroprosthesis after rehabilitation, but not between forces recorded
presurgery and during rehabilitation without the neuroprosthesis. All subjects were
able to grasp, move and release more objects within the 30‐s test period with the
neuroprosthesis than without it. Collective results for the eight ADL tests for all
six subjects show that, in 35 of the 48 (73%) occasions, less physical assistance
and/or adaptive equipment was required when the Freehand systemê
was employed compared to when it was not used. In 41 of the 48 (85%) occasions,
the six subjects expressed a preference for using the neuroprosthesis to perform
these activities of daily living. Twelve months after rehabilitation, five of the
six subjects still used the neuroprosthesis daily or every second day.

Conclusion: The Freehand neuroprosthesis has provided useful hand function
with few surgical and technical difficulties in these patients. Regular ongoing use
of the device indicates user satisfaction.
Practical skill development in new nurses
Authors: Torunn Bjørk Ida
Published: July 2002

This paper reports the results of an empirical study of new nurses’ development of practical skill. Actual practice and clinical learning of new nurses has received minor attention in nursing research. This may build on the assumption that practical skill naturally improve as a result of working in the clinical setting. In the present study nurses were videotaped several times as they performed in the clinical setting, and interviewed after each filming. Analysis of skill development was rendered possible by comparing characteristics of performance over time. A model of practical skill performance was developed during the analysis. This model advances a broader understanding of practical skill by incorporating the following constructs: substance and sequence, accuracy, fluency, integration and caring comportment. The nurses’ trajectories of practical skill development are presented on the basis of this model. Individual and common trends in practical skill development are discussed, and the idea of development of practical skill as a natural happening in the clinical setting is critiqued.
The Trp64Arg mutation of the adrenergic β‐3 receptor gene impairs insulin secretion: a twin study
Authors: Christiansen C. , Poulsen P. , Beck‐Nielsen H.
Published: July 2002

Aims The physiological role of the adrenergic β‐3 receptor is poorly understood in man but the Trp64Arg mutation of the receptor gene has been related to the insulin resistance syndrome, an earlier onset of diabetes and rapid weight gain. This study set out to examine the effects of the mutation on glycaemic responses after an oral glucose tolerance test.

Methods A standard oral glucose tolerance test (75 g glucose) was performed in 196 dizygotic twins. Serum insulin and glucose responses were measured at 0, 30 and 120 min.

Results In the twins discordant for the mutation (21 pairs), no effects of the mutation were found on the plasma glucose responses. The insulin response given as incremental area under curve (iAUC) (median 13.8 (25–75th percentile 9.3–21.0) vs. 23.3 (14.2–29.2) mmol.l–1.min, P < 0.021) and the insulinogenic index ((insulin30 min– insulin0 min)/(glucose30 min– glucose0 min)), a measure of the insulin secretory capacity (44 (34–58) vs. 75 (42–124), P < 0.006), were considerably lower in the variant type. The results were confirmed when using non‐paired statistics on all subjects.

Conclusion It was concluded that the adrenergic β‐3 receptor, in addition to its already known effects, may be involved in the regulation of insulin secretion and that patients with the Trp64Arg mutation present an impaired insulin secretion.
Effects of the amylin analogue pramlintide on hepatic glucagon responses and intermediary metabolism in Type 1 diabetic subjects
Authors: Ørskov L. , Nyholm B. , Hove K. Yde , Gravholt C. H. , Møller N. , Schmitz O.
Published: July 2002

Aims Hepatic glycogen stores have been shown to be depleted, and glucagon stimulated hepatic glucose production reduced, in Type 1 diabetic subjects. Co‐administration of amylin and insulin has been shown to replete hepatic glycogen stores in diabetic animal models. The aim of the present study was to investigate the effect of amylin replacement on hepatic glucagon responsiveness in humans.

Methods Thirteen Type 1 diabetic men were studied in a double‐blind, placebo‐controlled, cross‐over study after 4 weeks of subcutaneous pramlintide (30 μg q.i.d.) or placebo administration. Following an overnight fast, plasma glucose was kept above 5 mmol/l (baseline 210–240 min) with an insulin infusion rate of 0.25 mU.kg–1.min–1. To control portal glucagon levels, somatostatin was infused at a rate of 200 μg/h. Basal growth hormone (2 ng.kg–1.min–1) and glucagon (0.7 ng.kg–1.min–1) were replaced. Glucagon infusion was increased to 2.1 ng.kg–1.min–1 at 240–360 min (step 1) and to 4.2 ng.kg–1.min–1 at 360–420 min (step 2).

Results Baseline plasma glucose (5.59 ± 0.16 vs. 5.67 ± 0.25 mmo/l) and endogenous glucose production (EGP) (1.32 ± 0.22 vs. 1.20 ± 0.13 mg.kg–1. min–1) were similar and the response to glucagon was unaffected by pramlintide (glucose: step 1; 6.01 ± 0.31 vs. 5.94 ± 0.38 mmo/l, step 2; 6.00 ± 0.37 vs. 5.96 ± 0.50 mmol/l, EGP: step 1; 1.91 ± 0.18 vs. 1.83 ± 0.15 mg.kg–1.min–1, step 2; 2.08 ± 0.17 vs. 1.96 ± 0.16 ng.kg–1.min–1, pramlintide vs. placebo). Glucose disposal rates were similar at baseline (2.44 ± 0.13 vs. 2.28 ± 0.09 mg.kg–1.min–1, pramlintide vs. placebo) as well as during the glucagon challenge (P‐values all > 0.2).

Conclusions Co‐administration of pramlintide and insulin to Type 1 diabetic subjects for 4 weeks does not change the plasma glucose or endogenous glucose production response to a glucagon challenge, following an overnight fast. In addition, pramlintide administration does not appear to alter insulin‐mediated glucose disposal.
The lipoprotein profile differs during insulin treatment alone and combination therapy with insulin and sulphonylureas in patients with Type 2 diabetes mellitus
Authors: Lindström T. , Nyström F. H. , Olsson A. G. , Ottosson A. ‐M. , Arnqvist H. J.
Published: July 2002

Aims To study whether changes in endogenous insulin secretion at the same glycaemic control affect the plasma concentrations of lipoproteins in patients with Type 2 diabetes mellitus.

Methods Fifteen patients, age 59 ± 2 years (mean ±sem), body weight 86.3 ± 3.0 kg, body mass index 29.6 ± 0.9 kg/m2 were treated with sulphonylurea and insulin in combination or with insulin alone in a randomized, double‐blind, crossover study. All patients were treated with a multiple daily injection regimen with the addition of glibenclamide 10.5 mg daily or placebo tablets.

Results During combination therapy, the dose of insulin was 25% less (P < 0.002) and there was a 29% increase in plasma C‐peptide concentration (P = 0.01). Plasma levels of free insulin were not changed. Plasma levels of sex hormone‐binding globulin (SHBG) and insulin‐like growth factor‐binding protein (IGFBP)‐1 were lowered. There were no differences in the 24‐h blood glucose profiles or HbA1c (6.0 ± 0.2 vs. 6.3 ± 0.2%; P = 0.16). Body weight was similar. There was a significant decrease in plasma LDL cholesterol (3.04 ± 0.24 vs. 3.41 ± 0.21 mmol/l; P = 0.04), apolipoprotein A1 and of lipoprotein(a) but an increase in VLDL‐triglycerides (1.36 ± 0.31 vs. 0.96 ± 0.16 mmol/l; P = 0.02) during combination therapy. The ratio between LDL cholesterol and apolipoprotein B concentrations was significantly lower during combination therapy (P < 0.01).

Conclusions Combination therapy with insulin and sulphonylureas increases portal insulin supply and thereby alters liver lipoprotein metabolism when compared with insulin therapy alone.
Does transvaginal ultrasound of the cervix predict preterm premature rupture of membranes in a high‐risk population?
Authors: Odibo A. O. , Berghella V. , Reddy U. , Tolosa J. E. , Wapner R. J.
Published: July 2002

Objectives

To determine in patients with a cervical length < 25 mm on transvaginal ultrasound if the severity of cervical length shortening can be used to predict preterm premature rupture of membranes (PPROM) and the contribution of PPROM to preterm delivery in these patients.

Methods

We retrospectively reviewed asymptomatic singleton pregnancies between 14 and 24 weeks at high risk of preterm delivery by obstetric history and transvaginal cervical length < 25 mm. Cases developing subsequent PPROM were compared with controls for transvaginal sonographic cervical characteristics.

Results

Of 69 patients identified to have a cervical length < 25 mm, 27 (39%) had PPROM, and 42 (61%) did not. Mean ± standard deviation (SD) cervical length was 12.7 ± 8.7 mm and 17.0 ± 7.6 mm in the two groups, respectively (
P = 0.04). Mean ± SD cervical funneling was 57.4 ± 31.4% and 40.0 ± 28.1%, respectively (
P = 0.01). The characteristics most predictive of PPROM were: cervical length of < 10 mm (sensitivity, specificity, positive and negative predictive values of 33, 90, 69, and 68%, respectively; odds ratio, 4.8; 95% confidence interval, 1.3–17.5) and cervical funneling > 75% (sensitivity, specificity, positive and negative predictive values of 33, 93, 75 and 68%, respectively; odds ratio, 6.5; 95% confidence interval, 1.6–26.9). Stepwise logistic regression revealed cervical length to be a significant predictor of PPROM (odds ratio, 4.0; 95% confidence interval, 1.1–14.2).

Conclusion

In patients at high risk for preterm delivery because of obstetric history and transvaginal sonographic cervical length < 25 mm, a cervical length < 10 mm and cervical funneling > 75% were most predictive of PPROM. PPROM was the major contributor to preterm delivery in these patients. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Atomic abruptness in InGaAsP/InP quantum well heterointerfaces grown by low-pressure organometallic vapor phase epitaxy
Authors: Thijs P. J. A. , Montie E. A. , van Kesteren H. W. , ’t Hooft G. W.
Published: July 2002

High quality quantum well structures of InGaAsP (λ=1.55 μm)/InP were grown by low-pressure organometallic vapor phase epitaxy on 0.2° and 2° misoriented (001) InP substrates. Multiple-line 2 K photoluminescence emission was observed for the first time from thin quantum wells of InGaAsP grown on 0.2° misoriented substrates. The multiple-line emission is interpreted to result from half-monolayer well width variations within one well with lateral sizes larger than the excitonic radius. Quantum wells grown on substrates with 2° misorientation showed generally wider single-line photoluminescence emission due to well width variations within one well with lateral sizes smaller than the excitonic radius. The studied well thicknesses ranged from ≊70 Å down to ≊4 Å, which showed emission as short as 905 nm (1.37 eV) corresponding to a spectral upshift of 514 meV. The very high quality of the quantum wells of InGaAsP is indicated by a 2 K photoluminescence linewidth of 8.8 meV for a ≊6 Å well.
Infrared power limiting and self-switching in CdTe
Authors: Steier William H. , Kumar Jayant , Ziari Mehrdad
Published: July 2002

Power limiting and self-switching which is caused by the field shielding effects of charge created by photoconductivity at 1.06 μm in CdTe have been demonstrated. The effect has a relatively low threshold of ∼100 μW/cm2, an extrapolated switching time of microseconds, and can be used over the wavelength band of approximately 0.9–1.3 μm.
Solid phase epitaxy and doping of Si through Sb-enhanced recrystallization of polycrystalline Si
Authors: Gong S. F. , Hentzell H. T. G. , Radnoczi G. , Charai A.
Published: July 2002

We have investigated a Sb-enhanced solid phase epitaxy of Si on a p-type (100)Si substrate through intermixing of amorphous Si and Sb thin films and a subsequent recrystallization of the polycrystalline Si (poly-Si). By using cross-sectional transmission electron microscopy, we show that a high concentration of Sb enhances recrystallization of poly-Si, which eventually results in an epitaxial growth of Si. This is most likely due to an enhanced Si self-mobility caused by a Sb diffusion in the vicinity of the grain boundaries of the poly-Si. At the same time the doped layer was observed to serve as a diffusion source for doping the Si substrate. Secondary ion mass spectrometry measurements reveal the concentrations and the depth profiles of Sb in the Si substrate.
Infrared double-heterostructure diode lasers made by molecular beam epitaxy of Pb1−xEuxSe
Authors: Tacke M. , Spanger Beate , Lambrecht A. , Norton P. R. , Böttner H.
Published: July 2002

Infrared (IR) diode lasers have been made by growing heterostructures or graded structures of Pb1−xEuxSe. This IV-VI ternary has a small lattice variation within the IR band-gap range. Double-heterostructure lasers with PbSe active layers were operated up to T=174 K cw and 220 K pulsed mode; they reached the highest cw operation temperature reported for this type of laser in the mid IR. Their tuning range was 7.8–5.7 μm cw. Lasers with the ternary as the active layer were operated up to the shortest wavelength of 2.88 μm at 100 K cw. At present lasers made by molecular beam epitaxy of this material cover the widest wavelength region at T>77 K around 5 μm in cw operation.
Use of independently controlled Cl radical and Ar ion beams for anisotropic chemically enhanced etching of GaAs
Authors: Skidmore J. A. , Coldren L. A. , Hu E. L. , Merz J. L. , Asakawa K.
Published: July 2002

We have implemented a novel dry etching technique that combines chlorine radicals generated in a microwave plasma with an argon ion beam. This uniquely provides separate control of the radical flux and ion flux so that the degree of anisotropy and chemical enhancement can be arbitrarily varied. We demonstrate that this etching technique should be capable of producing smooth structures with low damage for applications in optoelectronics.
A Monte Carlo study of electron-hole scattering and steady-state minority-electron transport in GaAs
Authors: Sadra K. , Maziar C. M. , Streetman B. G. , Tang D. S.
Published: July 2002

We report the first bipolar Monte Carlo calculations of steady-state minority-electron transport in room-temperature p-GaAs including multiband electron-hole scattering with and without hole overlap factors. Our results show how such processes, which make a significant contribution to the minority-electron energy loss rate, can affect steady-state minority-electron transport. Furthermore, we discuss several other issues which we believe should be investigated before present Monte Carlo treatments of electron-hole scattering can provide quantitative information.
Nucleation and growth of YBaCuO on SrTiO3
Authors: Clemens B. M. , Nieh C. W. , Kittl J. A. , Johnson W. L. , Josefowicz J. Y. , Hunter A. T.
Published: July 2002

We have studied transmission electron microscopy (TEM) cross sections and plan views of YBaCuO films on SrTiO3 single-crystal substrates at various stages of post-deposition anneal. These TEM studies reveal in extraordinary detail the process of nucleation of epitaxial crystal structure characteristic of the films. In partially annealed samples sputtered from separate Cu, Y, and BaF2 sources, we see the 2-4-8 phase nucleates at the substrate interface, with the c axis parallel to the [001] substrate direction (surface normal). Upon further annealing, the 1-2-3 phase nucleates on this layer with the c axis parallel to each of the [100], [010], and [001] substrate directions. Rapid growth in the a- and b-axis directions results in an uneven ‘‘basket weave’’ surface texture. This information is crucial to the successful control and optimization of crystal orientation and surface morphology of superconducting thin films necessary for the application of this material to multilayer structures for electronic devices.
Constant-current-density model for the anomalous Hall effects in Hg0.8Cd0.2Te
Authors: Pan D. S. , Lu Y. , Chu M.
Published: July 2002

This letter presents a simple model developed for calculating the Hall coefficient and Hall mobility in inhomogeneous narrow-band-gap semiconductors, including inclusions with opposite conduction type. The model is based on one assumption that the current density is a uniform constant in the sample in spite of the inhomogeneities. This assumption is supported by a variational calculation based on the principle of least entropy production rate. The model is then applied to explain the anomalous Hall data in the n-type Hg0.8Cd0.2Te, and a good fit is obtained when p-type Hg0.8Cd0.2Te is considered to be the inclusions. The results show that some assumptions in a previous layer model are not necessary in order to explain the observed phenomena. By using this simplified treatment of material inhomogeneity, it will be easier to design experiments to investigate the cause of such inhomogeneity.
Superconducting Bi-Ca-Sr-Cu oxide thin films by spray pyrolysis of metal acetates
Authors: Vaslow Dale F. , Dieckmann Gunter H. , Elli David Dawson , Ellis Arthur B. , Holmes D. Scott , Lefkow Anthony , MacGregor Mark , Nordman James E. , Petras Michael F. , Yang Yifeng
Published: July 2002

Superconducting Bi-Ca-Sr-Cu oxide thin films have been prepared on ZrO2-coated silicon (111) wafers by spray pyrolysis of metal acetate precursors followed by rapid annealing to 850 °C in air. Resistivity measurements indicate a broad superconducting transition with Tc onset near 90 K and zero resistivity below 60 K. The films are highly oriented with the c axis normal to the substrate surface and can be indexed to a tetragonal structure with lattice parameters of a=3.832(1) Å and c=30.78(5) Å. Both x-ray photoelectron spectroscopy and x-ray diffraction measurements indicate the loss of Ca to the ZrO2 buffer layer.
Crystallography and microstructure of Tl-Ca-Ba-Cu-O superconducting oxides
Authors: Beyers R. , Parkin S. S. P. , Lee V. Y. , Nazzal A. I. , Savoy R. , Gorman G. , Huang T. C. , La Placa S.
Published: July 2002

We report on the crystallography and microstructure of six oxides in the Tl-Ca-Ba-Cu-O system with nominal compositions Tl1Ba2Cu1O5, Tl1Ca1Ba2Cu2O7, Tl1Ca2Ba2Cu3O9, Tl2Ba2Cu1O6, Tl2Ca1Ba2Cu2O8, and Tl2Ca2Ba2Cu3O10. The structures consist of one, two, or three Cu perovskite-like units sandwiched between Tl-O monolayers or bilayers. The predominant defects in the crystals with bilayer and trilayer Cu perovskite-like units are stacking faults that produce local intergrowths of related structures. The density of stacking defects in these oxides correlates with changes in the superconducting transition temperatures.
Use of electron beam lithography to selectively decompose metalorganics into patterned thin-film superconductors
Authors: Mantese J. V. , Catalan A. B. , Hamdi A. H. , Micheli A. L. , Studer-Rabeler K.
Published: July 2002

Fine line superconductors, approximately 5 μm in width and 260 nm thick, were formed from Y-Ba-Cu on 〈100〉SrTiO3 by the combined methods of metalorganic deposition and selective area electron beam exposure. The lines were written in metal neodecanoates using an electron beam having a spot size of 0.25 μm and an energy of 25 kV. The dosage of the exposure was 1200 μC/cm2. Unexposed areas were removed with a 30 s xylene wash. A 500 °C pyrolysis in air for 300 s followed by rapid thermal annealing in oxygen produced lines having superconducting onsets above 90 K and zero resistance at 69 K.
Modulation bandwidth of GaAs/AlGaAs single quantum well lasers operating at the second quantized state
Authors: Larsson Anders , Lindström Carsten
Published: July 2002

The dynamic properties of GaAs/AlGaAs graded index separate confinement heterostructure single quantum well lasers have been investigated. The sublinear gain-carrier density relation imposes bandwidth limitations on these lasers. However, a considerable increase in the resonance frequency (∼55% for a quantum well width of 140 Å) was observed for lasers with cavities shorter than a certain cavity length. This discontinuous increase in bandwidth with decreasing cavity length coincides with the transition from first to second quantized state lasing and the associated recovery of the differential gain.
Low-temperature mobility of two-dimensional electron gas in selectively doped pseudomorphic N-AlGaAs/GaInAs/GaAs structures
Authors: Ohno H. , Luo J. K. , Matsuzaki K. , Hasegawa H.
Published: July 2002

Low-field mobility of two-dimensional electron gas (2DEG) in selectively doped pseudomorphic N-Al0.3Ga0.7As/ Ga0.8In0.13As/GaAs structures was measured as a function of carrier concentration as well as a function of temperature. In order to explain the observed mobility characteristics, scattering due to clustering has been considered. It is shown that the low-field mobility of 2DEG at low temperature (<40 K) can be explained by the scattering due to clustering together with the remote ionized impurity scattering.
Temperature effects on the photoluminescence of GaAs grown on Si
Authors: Chen Y. , Freundlich A. , Kamada H. , Neu G.
Published: July 2002

Photoluminescence properties of as-grown and post-growth annealed GaAs directly grown on Si substrates by metalorganic vapor phase epitaxy are studied at various temperatures. At low temperature, three extrinsic lines and an intrinsic exciton line split by residual biaxial tensile stress are observed. The extrinsic lines give evidence of growth-induced defects. One of these lines, involving the presence of Si acceptors, appears after post-growth annealing (10 min at 800 °C). The biaxial stress deduced from the intrinsic lines varies with temperature; extrapolation to zero stress results in a temperature slightly below the growth temperature.
Threefold upconversion laser at 0.85, 1.23, and 1.73 μm in Er:YLF pumped with a 1.53 μm Er glass laser
Authors: Pollack S. A. , Chang D. B. , Birnbaum M.
Published: July 2002

Lasing action at 1.73, 1.23, and 0.85 μm was obtained by a threefold upconversion process in Er:YLF at 110 K using a 1.53 μm Er:glass pump laser. The 1.73 μm transition had the lowest threshold and highest pump conversion efficiency.
Ga1−xAlxAs purification during its liquid phase epitaxial growth in the presence of Yb
Authors: Raczynska J. , Fronc K. , Langer J. M. , Lischka K. , Pesek A.
Published: July 2002

The influence of Yb added to the melt, on the near-band-gap emission of Ga1−xAlxAs grown by liquid phase epitaxy, is reported. No characteristic Yb3+ emission is found, but a pronounced narrowing of the bound-exciton spectrum is observed for Yb concentrations in the Ga melt below 100 ppm. A similar effect is seen in conduction band to acceptor transitions, for which the smallest linewidth observed is limited by fluctuations in composition and agrees well with the currently accepted 66:34 band-offset partition between the conduction and valence bands of GaAs/Ga1−xAlxAs heterojunctions in the direct band-gap range.
Dopant redistribution during oxidation of SiGe
Authors: LeGoues F. K. , Rosenberg R. , Meyerson B. S.
Published: July 2002

This letter compares diffusion of boron in Si during oxidation both for pure Si and for Si covered with a very thin layer of SiGe alloy. It demonstrates that the thin layer of SiGe suppresses oxidation enhanced diffusion of boron. A mechanism is proposed based on suppression of Si interstitials. This phenomenon is then related to the faster rate of oxidation of bulk SiGe and SiGe-covered Si samples reported previously.
Negative transconductance and negative differential resistance in a grid-gate modulation-doped field-effect transistor
Authors: Ismail K. , Chu W. , Yen A. , Antoniadis D. A. , Smith Henry I.
Published: July 2002

We report on transport measurements in grid-gate lateral-surface-superlattice (LSSL) field-effect transistors on a modulation-doped GaAs/AlGaAs heterostructure. The LSSL is created by a 0.2 μm period Ti/Au grid on top of the AlGaAs layer, which presents a tunable, two-dimensional periodic potential modulation to the electrons traveling from source to drain. Current measurements at 4.2 K as a function of gate bias exhibit negative transconductance at a fixed drain bias below 15 mV, providing evidence of a superlattice effect (i.e., coherent back-diffraction). In addition, negative differential resistance is observed at a fixed gate bias and a drain bias around 100 mV, which could be a manifestation of sequential resonant tunneling.
Transient absorption spectra of a modulation-doped Ga0.47In0.53As/Al0.48In0.52As multiple quantum well structure measured by picosecond infrared pulses
Authors: Elsaesser T. , Bäuerle R. J. , Kaiser W. , Lobentanzer H. , Stolz W. , Ploog K.
Published: July 2002

Intersubband and intrasubband scattering of hot electron-hole pairs is studied with picosecond infrared pulses. The carrier distribution function is derived directly from the transient absorption spectra after selective excitation of carriers to the n=1 and 2 subbands. Band filling of the n=1 conduction band results in a strong bleaching of the corresponding interband absorption and in large changes of the refractive index. An absorption change due to the population of the n=2 subbands is not detected, indicating their fast relaxation within less than 3 ps. The hot plasma cools by LO phonon emission on a time scale of several tens of picoseconds.
Theory of the rf sheath in the regime between the ion and electron plasma frequencies
Authors: Biehler S.
Published: July 2002

The collisionless space-charge sheath of a capacitivelyc oupled rf discharge is investigated in the frequency regime ωpi ≪ω≪ωpe . Assuming Boltzmann distributed electrons and starting from an existing charge exchange model of the presheath a self-consistent analysis is presented.
Examination of rapid thermal annealed GaAs using cathodoluminescence
Authors: Third C. E. , Weinberg F. , Young L.
Published: July 2002

Samples of semi-insulating GaAs were annealed for 5–18 s at 650–950 °C using rapid thermal annealing. Cathodoluminescence was used to compare as-received and annealed samples to determine the effect of the heat treatment. Cathodoluminescence images of the surface of samples show a change in background intensity after heating. Images of cleaved cross sections indicate that the change is not uniform throughout the thickness of the sample.
Near-ideal lateral scaling in abrupt Al0.48In0.52As/In0.53Ga0.47As heterostructure bipolar transistors prepared by molecular beam epitaxy
Authors: Jalali B. , Nottenburg R. N. , Chen Y. K. , Levi A. F. J. , Sivco D. , Cho A. Y. , Humphrey D. A.
Published: July 2002

We demonstrate near-ideal lateral scaling in abrupt junction Al0.48In0.52As /In0.53Ga0.47As heterostructure bipolar transistors. Current gain β=162 and 122 has been realized in transistors with emitter stripe width of 50 and 0.6 μm, respectively. The excellent lateral scaling occurs because the 0.5 eV emitter injection energy results in nonequilibrium vertical electron transport in the thin (700 Å) InGaAs base.
Novel pseudomorphic high electron mobility transistor structures with GaAs-In0.3Ga0.7As thin strained superlattice active layers
Authors: Ballingall J. M. , Ho P. , Tessmer G. J. , Martin P. A. , Lewis Nathan , Hall Ernest L.
Published: July 2002

The thin strained superlattice (TSSL) concept is introduced as a means for extending the practical range of application for pseudomorphic Inx Ga1−x As on GaAs. Growth and characterization results are presented for pseudomorphic high electron mobility transistor structures with GaAs-In0.3 Ga0.7 As TSSL active layers grown by molecular beam epitaxy. The TSSLs are composed of three periods of GaAs(15 Å)- In0.3 Ga0.7 As(h2 ), where h2 ranges from 30 to 52 Å. Modulation doping of the TSSLs is provided by atomic planar-doped Al0.3 Ga0.7 As overlayers with 45 Å undoped spacers. 77 K Hall effect and transmission electron microscopy reveal that relatively thick TSSLs can be grown with high electronic and structural quality, comparable to much thinner In0.3 Ga0.7 As single quantum wells. Results are compared with a model for critical layer thickness and discussed in light of in situ reflection high-energy electron diffraction measurements.
Optical control of microwave propagation in superconducting devices
Authors: Glass N. E. , Rogovin D.
Published: July 2002

We have examined a theory of the microwave electrodynamics of superconducting films driven far from equilibrium by laser radiation and have found that low laser powers can dramatically change the propagation characteristics of wave guiding devices operating at centimeter through submillimeter wavelengths. At low temperatures, the attenuation of a superconducting stripline can be enhanced by orders of magnitude at frequencies near twice the energy gap. The phase velocity of microwaves well below the pair-splitting frequency can also be dramatically changed. These changes are predicted to be achievable on subnanosecond time scales when the driving laser fields are pulsed. Such behavior offers device applications as microwave intensity modulators and phase shifters.