bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cost‐effectiveness acceptability curves – facts, fallacies and frequently asked questions
Authors: Fenwick Elisabeth , O'Brien Bernie J. , Briggs Andrew 
Published: April 2004

AbstractCost‐effectiveness acceptability curves (CEACs) have been widely adopted as a method to quantify and graphically represent uncertainty in economic evaluation studies of health‐care technologies. However, there remain some common fallacies regarding the nature and shape of CEACs that largely result from the ‘textbook’ illustration of the CEAC. This ‘textbook’ CEAC shows a smooth curve starting at probability 0, with an asymptote to 1 for higher money values of the health outcome (λ). But this familiar ‘ogive’ shape which makes the ‘textbook’ CEAC look like a cumulative distribution function is just one special case of the CEAC. The reality is that the CEAC can take many shapes and turns because it is a graphic transformation from the cost‐effectiveness plane, where the joint density of incremental costs and effects may ‘straddle’ quadrants with attendant discontinuities and asymptotes. In fact CEACs: (i) do not have to cut the y‐axis at 0; (ii) do not have to asymptote to 1; (iii) are not always monotonically increasing in λ; and (iv) do not represent cumulative distribution functions (cdfs). Within this paper we present a ‘gallery’ of CEACs in order to identify the fallacies and illustrate the facts surrounding the CEAC. The aim of the paper is to serve as a reference tool to accompany the increased use of CEACs within major medical journals. Copyright © 2004 John Wiley & Sons, Ltd.
Habit formation and college students' demand for alcohol
Authors: Williams Jenny 
Published: April 2004

AbstractThis research investigates whether the positive association between college students' current and high‐school drinking is due to habit formation or whether it is solely due to the influence of unobserved individual characteristics that are correlated over time. The empirical investigation is based on individual level data from the 1997 and 1999 waves of the Harvard School of Public Health's College Alcohol Study (CAS). Amemyia's generalized least squares is used to address the heterogeneity issue in examining the relationship between past and current drinking. The results suggest that after controlling for correlation in unobserved characteristics that influence alcohol use, high‐school drinking has a significant and positive impact on college drinking, indicating the existence of habit formation. Both structural evidence of habit formation and reduced form results reveal that stricter drunk driving laws faced while in high‐school have a long lived effect, reducing drinking while in college. The results also highlight the importance of access to alcohol, both on campus and in the college neighborhood, as a determinant of college students' drinking behavior. Copyright © 2004 John Wiley & Sons, Ltd.
An inner product lemma
Authors: Gustafson Karl 
Published: April 2004

AbstractGiven the operator product BA in which both A and B are symmetric positive‐definite operators, for which symmetric positive‐definite operators C is BA symmetric positive‐definite in the C inner product 〈x, y〉C? This question arises naturally in preconditioned iterative solution methods, and will be answered completely here. Copyright © 2004 John Wiley & Sons, Ltd.
Normal degree
Authors: Gustafson Karl 
Published: April 2004

AbstractThe H‐normal degree n(A,H) associated with GCG‐LS algorithms is shown to be independent of H, thereby correcting an incompleteness in the literature. The normal degree n(A) for any normalizable matrix A when n(A)>1 is shown to sometimes occur sharply in the interval $\sqrt{m}$≦n(A)≦m−1, where m is the degree of A's minimum polynomial, thereby clarifying previous estimates in the literature. Copyright © 2004 John Wiley & Sons, Ltd.
Computing projections via Householder transformations and Gram–Schmidt orthogonalizations
Authors: Dax Achiya 
Published: April 2004

AbstractLet x* denote the solution of a linear least‐squares problem of the form

where A is a full rank m × n matrix, m > n. Let r*=b ‐ Ax* denote the corresponding residual vector. In most problems one is satisfied with accurate computation of x*. Yet in some applications, such as affine scaling methods, one is also interested in accurate computation of the unit residual vector r*/∥r*∥2. The difficulties arise when ∥r*∥2 is much smaller than ∥b∥2. Let x̂ and r̂ denote the computed values of x* and r*, respectively. Let εdenote the machine precision in our computations, and assume that r̂ is computed from the equality r̂ =b‐Ax̂. Then, no matter how accurate x̂ is, the unit residual vector û =r̂/∥r̂∥2 contains an error vector whose size is likely to exceed ε∥b∥2/∥r*∥2. That is, the smaller ∥r*∥2 the larger the error. Thus although the computed unit residual should satisfy ATû=0, in practice the size of ∥ATû∥2 is about ε∥A∥2∥b∥2/∥r*∥2. The methods discussed in this paper compute a residual vector, r̂, for which ∥ATr̂∥2 is not much larger than ε∥A∥2∥r̂∥2. Numerical experiments illustrate the difficulties in computing small residuals and the usefulness of the proposed safeguards. Copyright © 2004 John Wiley & Sons, Ltd.
An expanded mixed covolume method for elliptic problems
Authors: Rui Hongxing , Lu Tongchao 
Published: April 2004

AbstractWe consider the mixed covolume method combining with the expanded mixed element for a system of first‐order partial differential equations resulting from the mixed formulation of a general self‐adjoint elliptic problem with a full diffusion tensor. The system can be used to model the transport of a contaminant carried by a flow in porous media. We use the lowest order Raviart‐Thomas mixed element space. We show the first‐order error estimate for the approximate solution in L2 norm. We show the superconvergence both for pressure and velocity in certain discrete norms. We also get a finite difference scheme by using proper approximate integration formulas. Finally we give some numerical examples. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
A comparison between Nova T and Copper T 200 Ag in Hungary
Authors: Batar Istvan , Lampe Laszlo , Rakoczi Istvan , Gati Istvan , Allonen Hannu 
Published: April 2004

AbstractIn a comparative use‐effectiveness study, 855 Nova T and 883 TCu 200 Ag devices were inserted in a randomised sequence. By the end of the first year the gross rate of unplanned pregnancy was 1.1 per 100 users of Nova T and 2.1 per 100 users of TCu. After 2 years the pregnancy rates for Nova T and TCu were 3.1 and 4.8 per 100 users, respectively. Although there was no statistically significant difference between the rates for the two devices, they suggest a higher contraceptive efficacy for Nova T.
Urethral prolapse in the premenarcheal female
Authors: Carlson Nancy J. , Mercer Lane J. , Hajj Samir N. 
Published: April 2004

AbstractUrethral prolapse in the premenarcheal female manifests as vaginal bleeding and a periurethral mass. In the past, the recommended management was surgical excision or cautery. However, conservative management has been shown to have excellent results. Five premenarcheal patients with urethral prolapse treated by conservative therapy are presented. Treatment regimen consisted of local hygiene with sitz baths, hexachlorophene soap, topical providone iodine and estrogen cream. There were no complications or recurrences. Surgery is not warranted in the treatment of urethral prolapse in the premenarcheal female. Medical management is equally effective and less traumatic in this age group.
Patent ductus arteriosus after prolonged treatment with indomethacin during pregnancy: Case report
Authors: Atad J. , Lissak A. , Rofe A. , Abramovici H. 
Published: April 2004

AbstractIndomethacin was administered to suppress premature uterine contractions in a twin pregnancy from the 27th until the 32nd week of pregnancy. Patent ductus arteriosus was diagnosed after delivery in one twin and persisted patent for a period of 4 weeks. A hypothesis of the constrictive influence of prostaglandin synthetase inhibitors on the fetal ductus arteriosus during intrauterine and neonatal periods is suggested.
Progesterone challenge test and estrogen assays in menopausal women with endometrial adenomatous hyperplasia
Authors: Toppozada M.K. , Ismail A.A.A. , Hamed R.S.M. , Sid Ahmed K. , EL‐Faras A. 
Published: April 2004

AbstractIn an attempt to detect asymptomatic endometrial adenomatous hyperplasia in postmenopausal women, 40 cases were subjected to progesterone challenge test (PCT), measurement of serum estrogen and endometrial curettage. Group A (n = 30) included asymptomatic postmenopausal women, while group B (control group; n = 10) were cases with adenomatous hyperplasia (AH) diagnosed by biopsy. PCT showed a 100% sensitivity, 92% specificity, 71.4% predictive value of a positive test and 100% predictive value of a negative test in the detection of AH. Mean serum concentrations of E1 and E2 were significantly higher in patients with AH compared to cases with other endometrial histologies. Serum E1 and E2 and PCT can be used as screening tests to identify postmenopausal women with endometrial AH and thus at a greater risk of developing carcinoma.
The effect of mesterolone on sperm count, on serum follicle stimulating hormone, luteinizing hormone, plasma testosterone and outcome in idiopathic oligospermic men
Authors: Varma T.R. , Patel R.H. 
Published: April 2004

AbstractTwo hundred fifty subfertile men with idiopathic oligospermia (count less than 20 million/ml) were treated with mesterolone (100–150 mg/day) for 12 months. Seminal analysis were assayed 3 times and serum follicle stimulating hormone (FSH) luteinizing hormone (LH) and plasma testosterone were assayed once before treatment and repeated at 3, 6, 9 and 12 months after the initiation of treatment. One hundred ten patients (44%) had normal serum FSH, LH and plasma testosterone, 85 patients (34%) had low serum FSH, LH and low plasma testosterone. One hundred seventy‐five patients (70%) had moderate oligospermia (count 5 to <20 million/ml) and 75 patients (30%) had severe oligospermia (count <5 million/ml). Seventy‐five moderately oligospermic patients showed significant improvement in the sperm density, total sperm count and motility following mesterolone therapy whereas only 12% showed improvement in the severe oligospermic group. Mesterolone had no depressing effect on low or normal serum FSH and LH levels but had depressing effect on 25% if the levels were elevated. There was no significant adverse effect on testosterone levels or on liver function. One hundred fifteen (46%) pregnancies resulted following the treatment, 9 of 115 (7.8%) aborted and 2 (1.7%) had ectopic pregnancy. Mesterolone was found to be more useful in patients with a sperm count ranging between 5 and 20 million/ml. Those with severe oligospermia (count <5 million) do not seem to benefit from this therapy.
Single ectopic ureter opening into blind vagina, with renal dysplasia and associated utero‐vaginal duplication
Authors: Acien P. , Garcia‐Lopez F. , Ferrando J. , Chehab H.E. 
Published: April 2004

AbstractA rare case of single ectopic ureter opening into a blind vagina with renal dysplasia and associated uterovaginal duplication is reported. The findings are interesting from the clinical diagnostic viewpoint and also contribute to our knowledge of the embryology of the female genitourinary system, especially concerning the origin of the vagina.
Assessment of fetal growth and serum hCG titers after in vitro fertilization and embryo transfer
Authors: Nisikori K. , Nagoshi K. , Shimizu K. , Yoshida N. 
Published: April 2004

AbstractFetal growth in early pregnancy was estimated by transvaginal ultrasonic measurement and serum hCG measurement in 13 women who became pregnant through in vitro fertilization and embryo transfer treatment. The first day of observation of a gestational sac (GS) or fetal heart movement (FHM) of over 120 beats/min confirmed the pregnancy. There were 6 or 7 days difference in GS or FHM confirmation within 20 or 30 days after insemination, although statistical deviations were very small (GS: 21.3 ± 1.8, FHM: 29.5 ± 1.8 days after insemination, mean ± S.D.). Increases in crown‐rump length (CRL) and serum hCG were used as indicators of fetal growth. There was a good correlation between CRL or serum hCG and days after insemination (CRL: r = 0.95, n = 55; hCG: r = 0.96, n = 77), and individual cases had almost the same velocity of CRL growth and serum hCG elevation as each regression line. This data suggests that each embryo has a different growth velocity from the fertilized oocyte until the first clinical confirmation of pregnancy.
Educational Inequality and the Expansion of UK Higher Education
Authors: Blanden Jo , Machin Stephen 
Published: April 2004

AbstractIn this paper we explore changes over time in higher education (HE) participation and attainment between people from richer and poorer family backgrounds during a time period when the UK higher education system expanded at a rapid rate. We use longitudinal data from three time periods to study temporal shifts in HE participation and attainment across parental income groups for children going to university in the 1970s, 1980s and 1990s. The key finding is a highly policy relevant one, namely that HE expansion has not been equally distributed across people from richer and poorer backgrounds. Rather, it has disproportionately benefited children from relatively rich families. Despite the fact that many more children from higher income backgrounds participated in HE before the recent expansion of the system, the expansion acted to widen participation gaps between rich and poor children. This finding is robust to different measures of education participation and inequality. It also emerges from non‐parametric estimations and from a more detailed econometric model allowing for the sequential nature of education choices with potentially different income associations at different stages of the education sequence.
Unemployment Benefits, Contract Length and Nominal Wage Flexibility
Authors: Calmfors Lars , Johansson Åsa 
Published: April 2004

AbstractIn a bargaining model, we show that a decrease in the unemployment benefit level increases not only equilibrium employment, but also nominal wage flexibility, and thus reduces employment variations in the case of nominal shocks. Long‐term wage contracts lead to higher expected real wages and hence higher expected unemployment than short‐term contracts. Therefore, a decrease in the benefit level reduces the expected utility gross of contract costs of a union member more with long‐term than with short‐term contracts, thereby creating an incentive for shorter contracts. Incentives for employers are shown to change in the same direction.
Energy failure in astrocytes increases the vulnerability of neurons to spreading depression
Authors: Lian Xiao‐Yuan , Stringer Janet L. 
Published: April 2004

AbstractA neuroprotective role of astrocytes has been hypothesized, but the mechanism is debated and in vivo evidence is limited. To test this hypothesis, a sublethal stressor (spreading depression) and fluorocitrate (FC), a selective inhibitor of the astrocytic Krebs cycle, were used in urethane‐anaesthetized adult rats. Neuronal damage was assessed 24 h after treatment with silver stain and immunoreactivity for a 72‐kDa heat‐shock protein. ATP levels and mitochondrial aconitase activity, a marker indicating exposure to reactive oxygen species, were measured after 4 and 24 h. Spreading depression alone did not affect ATP levels, mitochondrial aconitase activity, or induce neuronal injury in the cortex. Local or intraventricular injection of FC significantly decreased ATP levels and mitochondrial aconitase activity, but did not produce neuronal damage. In animals receiving injections of FC and then spreading depression, there was evidence of significant neuronal stress and damage. Isocitrate, which bypasses the metabolic inhibition produced by FC, prevented all of the changes seen after the combination of FC and spreading depression. One‐hour pretreatment with dimethyl sulfoxide (a scavenger of hydroxyl radicals), deferoxamine (an iron chelator) or fructose‐1,6‐bisphosphate also blocked inactivation of mitochondrial aconitase, ATP depletion and the neuronal damage induced by FC and spreading depression. These experiments demonstrate that inhibition of the metabolism of astrocytes, with a decrease in ATP levels, will increase the susceptibility of neurons to the stress induced by spreading depression. The neuroprotective effects of dimethyl sulfoxide, deferoxamine and fructose‐1,6‐bisphosphate suggest that oxidative stress contributes to the neurotoxicity in this situation.
Stage‐specific and opposing roles of BDNF, NT‐3 and bFGF in differentiation of purified callosal projection neurons toward cellular repair of complex circuitry
Authors: Catapano Lisa A. , Arlotta Paola , Cage Tene A. , Macklis Jeffrey D. 
Published: April 2004

AbstractCellular repair of neuronal circuitry affected by neurodegenerative disease or injury may be approached in the adult neocortex via transplantation of neural precursors (“neural stem cells”) or via molecular manipulation and recruitment of new neurons from endogenous precursors in situ. A major challenge for potential future approaches to neuronal replacement will be to specifically direct and control progressive differentiation, axonal projection and connectivity of neural precursors along a specific neuronal lineage. This goal will require a progressively more detailed understanding of the molecular controls over morphologic differentiation of specific neuronal lineages, including neurite outgrowth and elongation, in order to accurately permit and direct proper neuronal integration and connectivity. Here, we investigate controls over the morphologic differentiation of a specific prototypical lineage of cortical neurons: callosal projection neurons (CPN). We highly enriched CPN to an essentially pure population, and cultured them at three distinct stages of development from embryonic and postnatal mouse cortex by retrograde fluorescence labelling, followed by fluorescence‐activated cell sorting. We find that specific peptide growth factors exert direct stage‐specific positive and negative effects over the morphologic differentiation and process outgrowth of CPN. These effects are distinct from the effects of these growth factors on CPN survival [Catapano et al. (2001)J. Neurosci., 21, 8863–8872]. These data may be critical for the future goal of directing lineage‐specific neuronal differentiation of transplanted or endogenous precursors/“stem cells” toward cellular repair of complex cortical circuitry.
Subunit‐specific P2X‐receptor expression defines chemosensory properties of trigeminal neurons
Authors: Spehr Jennifer , Spehr Marc , Hatt Hanns , Wetzel Christian H. 
Published: April 2004

AbstractThe facial innervation pattern of trigeminal nerve fibres comprises the innervation of the nasal epithelium, where free trigeminal nerve endings contribute to detection and discrimination of chemical stimuli including odourants. The signal transduction mechanisms in sensory nerve endings underlying perception of chemical stimuli remain widely uncovered. Here, we characterized trigeminal ATP‐activated P2X receptors in cultured rat trigeminal neurons and investigated their role in chemoperception. We identified a new subpopulation of neurons lacking typical nociceptive characteristics and expressing homomeric P2X2 receptors. Using a certain group of chemicals known as trigeminal stimuli we found no direct activation of trigeminal neurons, but a modulation of P2X2 receptor mediated currents. In contrast, P2X3 receptor mediated currents of nociceptive trigeminal neurons remained unaffected by the tested chemicals. Therefore, we assume a functional role for the newly identified subpopulation in chemodetection of certain trigeminal stimuli.
Nigral GABAergic inhibition upon mesencephalic dopaminergic cell groups in rats
Authors: Saitoh Kazuya , Isa Tadashi , Takakusaki Kaoru 
Published: April 2004

AbstractSynaptic inhibition from the substantia nigra pars reticulata (SNr) to the mesencephalic dopaminergic neurons, which was mediated by gamma (γ)‐amino‐butyric acid (GABA), was investigated in a midbrain slice preparation of Wistar rats. Whole‐cell patch‐clamp recordings were used to record synaptic potentials/currents from the dopaminergic neurons (n = 93) located in the retrorubral field (n = 22), the substantia nigra pars compacta (n = 47) and the ventral tegmental area (n = 24). In the presence of ionotropic glutamate receptor antagonists electrical stimulation of the SNr induced inhibitory postsynaptic potentials (IPSPs) and/or currents (IPSCs) in 83 neurons. The IPSPs/IPSCs were comprised early and late components. The early IPSPs/IPSCs were mediated by chloride currents through GABAA receptors. The late IPSPs/IPSCs were mediated by potassium currents through GABAB receptors. Both GABAA‐ and GABAB‐IPSPs were amplified by repetitive stimuli with frequencies between 25 and 200 Hz. This frequency range covers the firing frequencies of SNr neurons in vivo. It was observed that an application of a GABAB receptor antagonist increased the amplitude of the GABAA‐IPSPs. The amplification was followed by a rebound depolarization that induced transient firing of dopaminergic neurons. These properties of the IPSPs were common in all of the three dopaminergic nuclei. These results suggest that postsynaptic GABAA‐ and GABAB‐inhibition contribute to transient and persistent alternations of the excitability of dopaminergic neurons, respectively. These postsynaptic mechanisms may be, in turn, regulated by presynaptic GABAB‐inhibition. Nigral GABAergic input may provide the temporospatial regulation of the background excitability of mesencephalic dopaminergic systems.
Functional maturation of isolated neural progenitor cells from the adult rat hippocampus
Authors: Hogg Ron C. , Chipperfield Hiram , Whyte Kathryn A. , Stafford Mark R. , Hansen Mitchell A. , Cool Simon M. , Nurcombe Victor , Adams David J. 
Published: April 2004

AbstractAlthough neural progenitor cells (NPCs) may provide a source of new neurons to alleviate neural trauma, little is known about their electrical properties as they differentiate. We have previously shown that single NPCs from the adult rat hippocampus can be cloned in the presence of heparan sulphate chains purified from the hippocampus, and that these cells can be pushed into a proliferative phenotype with the mitogen FGF2 [Chipperfield, H., Bedi, K.S., Cool, S.M. & Nurcombe, V. (2002) Int. J. Dev. Biol., 46, 661–670]. In this study, the active and passive electrical properties of both undifferentiated and differentiated adult hippocampal NPCs, from 0 to 12 days in vitro as single‐cell preparations, were investigated. Sparsely plated, undifferentiated NPCs had a resting membrane potential of ≈ −90 mV and were electrically inexcitable. In > 70%, ATP and benzoylbenzoyl‐ATP evoked an inward current and membrane depolarization, whereas acetylcholine, noradrenaline, glutamate and GABA had no detectable effect. In Fura‐2‐loaded undifferentiated NPCs, ATP and benzoylbenzoyl‐ATP evoked a transient increase in the intracellular free Ca2+ concentration, which was dependent on extracellular Ca2+ and was inhibited reversibly by pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulphonic acid (PPADS), a P2 receptor antagonist. After differentiation, NPC‐derived neurons became electrically excitable, expressing voltage‐dependent TTX‐sensitive Na+ channels, low‐ and high‐voltage‐activated Ca2+ channels and delayed‐rectifier K+ channels. Differentiated cells also possessed functional glutamate, GABA, glycine and purinergic (P2X) receptors. Appearance of voltage‐dependent and ligand‐gated ion channels appears to be an important early step in the differentiation of NPCs.