bluuebunny/crossref_metadata_2025 huggingface dataset:
Pituitary hormone production in the placenta
Authors: Jones Sarah A
Published: October 2008

Not only does the placenta function as an organ of exchange between mother and fetus, it also has an endocrine role, producing a number of hormones necessary for the maintenance of pregnancy and the initiation of parturition. There is a large amount of information available which describes the synthesis and secretion of steroids, prostaglandins, human chorionic gonadotrophin (hCG)and placental lactogen by the placenta and fetal membranes. However, the placenta also contains a number of counterparts of hypothalamic-releasing factors and pituitary peptides. Why the human placenta should be the site for the synthesis and secretion of these hypothalamic and pituitary factors is something of a mystery. In man and other vertebrates the nervous system is derived from embryonic ectoderm. In particular, the hypothalamus and pituitary are in part derived from the neural plate and in part from the neural crest. Embryonic ectoderm in the early stages of embryonic development is intimately related spatially to trophoblast, and it is therefore possible that the cells of the ectoderm and trophoblast may be similarly programmed. It is unclear, however, why the trophoblast cells assume similar endocrine functions to those of the pituitary and hypothalamus rather than of other regions of the brain. Furthermore, whether the pituitary and hypothalamic-like peptides are of physiological importance or serve only as an evolutionary and embryological residue remains to be determined.
The ductus arteriosus
Authors: van Eyck Jim
Published: October 2008

The ductus arteriosus is a large vessel which connects the pulmonary trunk with the aorta. During fetal life it serves together with the foramen ovale as a shunt at cardiac level. Due to a complex regulatory mechanism it is capable of maintaining patency during fetal life and of rapid closure after birth. However, in premature neonates ductal patency frequently persists, an occurrence which may even be favourable in some situations. Recent investigations on the ductus arteriosus have provided new information about the regulatory mechanisms involved with its function. Initially, most studies on the fetal ductus arteriosus were conducted in animals. With the introduction of the combined use of two dimensional real-time and Doppler ultrasound systems the opportunity became available to study blood flow within the ductus arteriosus in the human fetus and neonate in a noninvasive manner. The increasing use in obstetric care of cyclo-oxygenase inhibitors for tocolysis and for prevention of the development of pregnancy induced hypertension and pre-eclampsia justifies the re-evaluation of the potential adverse effects of these drugs on the ductus arteriosus.
Obstetric risk scores
Authors: Chard T
Published: October 2008

Risk is defined as the probability of an untoward event. In fetal medicine this event is one or more of the outcomes listed in Table 1. The aim of antenatal care is to predict these events and thereby, hopefully, to avoid them.
Physiology and practical implications of dynamic exercise in pregnancy
Authors: van Doorn Marieke B , Lotgering Frederik K , Wallenburg Henk CS
Published: October 2008

In pregnancy the uterus and its contents constitute a growing mass of tissue with an increasing need for oxygen and substrates. Muscle activity is associated with an even more dramatic increase in metabolic demands. One might question if the physiological adaptations are adequate to provide for the combined demands of exercise and pregnancy.
The investigation of intrauterine death
Authors: Knowles Simon
Published: October 2008

The detection of an intrauterine fetal death or the delivery of a stillborn infant often initiates a futile and haphazard series of investigations set against a background of parental anxiety and clinical discomfort. The changes of successful diagnosis of the cause of intrauterine or intrapartum death are better served by the adoption of a prompt and co-ordinated approach to laboratory and other investigations. The purpose of this review is to examine the ways in which the laboratory can aid in the management of fetal death. Some of the more common causes of fetal death will be outlined, with particular emphasis on the lupus anticoagulant, fetomaternal macrotransfusion and specific infections such as Listeria and parvovirus, as these are all attracting current interest and debate. The problem of the macerated stillbirth is given some prominence in order to put to rest the notion that examination of the fetus in the presence of autolysis is worthless. None of the details are comprehensive but key references to reviews have been included in order to help the perinatologist on the spot.
Neonatal aspects of intrauterine growth retardation
Authors: Tudehope David I
Published: October 2008

The growth-retarded fetus is susceptible to intrauterine death, perinatal asphyxia and subsequently neonatal morbidity. Recent technical advances have only moderately increased the obstetrician's ability to recognize the fetus with intrauterine growth retardation (IUGR) prior to delivery, compared with two decades ago when less than one-third of such infants were identified before labour and delivery.
Intiation of lung ventilation at birth
Authors: Adamson S Lee
Published: October 2008

The newborn baby draws its first postnatal breath either during or within seconds of delivery. Within minutes, a regular breathing rhythm is established and this remains virtually continuous for the remainder of postnatal life. The mechanisms responsible for these sudden, dramatic and vital changes in the respiratory system at birth are only partially understood. Since fetuses make intermittent breathing movements long before birth, understanding the control of the fetal respiratory system may be essential to understanding the rapid onset of respiratory efforts at delivery. In this review the stimuli present at birth will be considered and, based on our current understanding of the fetal and neonatal respiratory control systems, those factors which are likely to play an important role in the initiation of lung ventilation at this time will be examined. Normal respiratory events in the early postnatal period will be concentrated on, but it is important to recognize that in some cases problems occur: a neonate may fail to initiate breathing efforts rapidly, or an apparently healthy premature neonate may suddenly stop breathing a few days after birth. In both cases, clinical intervention may be required to maintain adequate gas exchange and to prevent brain damage or death. Clearly, greater knowledge of respiratory control during this critical time of life would assist in the development of more appropriate and successful treatments for these life-threatening disorders.
Physiology of myometrial function: intercellular coupling and its role in uterine contractility
Authors: Tabb TN , Garfield RE , Thilander G
Published: October 2008

The mammalian uterus is composed of a preponderance of small smooth muscle cells usually aligned in two layers. The number of muscle cells in the human uterus at term is estimated at 200 billion, each minute fusiform cell measuring about 5–10μm in diameter and about 200μm in length. The main function of the uterus is to harbour the developing fetus during pregnancy and then to contract vigorously during labour to expel the products of conception. In order for the uterus to contract rhythmically and forcefully, a mechanism must exist to allow interaction between muscle cells in order to achieve synchronous activity. Phasic or cyclical patterns of contractile activity of the uterus cannot be accounted for by stimulation or inhibition from the nervous or endocrine systems. Since myometrial cells are dependent upon action potentials for their contractile processes, some system must be present between the muscle cells for the propagation of action potentials between them. The observation that gap junctions occur in large numbers between myometrial cells during parturition is thought to be significant in this regard and they are considered to play an essential role in parturition and in the control and co-ordination of uterine contractility. In this brief review, we will discuss the role of gap junctions in the modulation of myometrial contractility and the mechanisms that regulate their synthesis and permeability.
Atrial natriuretic peptide during human pregnancy and puerperium
Authors: Steegers Eric AP
Published: October 2008

In 1981 De Bold and colleagues demonstrated that when extracts of atrial tissue were given intravenously to rats a large diuresis and natriuresis occured promptly. The structure of the hormone concerned, atrial natriuretic peptide (ANP), was elucidated in 1983. Since then, ANP has received attention as a potentially important mediator in the homoeostasis of sodium and fluid volume.
Perspectives in prelabour rupture of the membranes
Authors: Kerslake Siân , Versi Eboo
Published: October 2008

Spontaneous rupture of the membranes usually accompanies the onset of labour, but precedes it in 10% of cases. Management, however, is not clear-cut and various treatments offer both risks and benefits to mother and infant in terms of intervention and nonintervention. Policies have changed over the last decade, moving towards a more conservative approach against a background of improved social conditions and antenatal care. Despite a wealth of literature documenting these changes, randomized controlled trials and unbiased reviews make up only a small proportion of the total number of papers surveyed. To base conclusions about the study of the management of prelabour rupture of the membranes upon statistically valid results, it is necessary to conduct a multicentre trial.
Postterm pregnancy: should all women have labour induced? A review of the literature
Authors: Hannah Mary E
Published: October 2008

All pregnancies are at some risk of adverse fetal and neonatal outcome. The risk increases, however, if the pregnancy ends too soon (preterm), or if it ends too late (postterm).
Congenital heart disorders in the fetus
Authors: Allan Lindsey D
Published: October 2008

The most important congenital heart disorders occurring in children are mainly due to malformations of cardiac structure. The underlying anatomical defect is established soon after the heart is first formed in embryonic life, less than 8 weeks after conception. However, the full echocardiographic picture may not be apparent until after birth or even later in childhood.
The ductus venosus
Authors: Huisman Tjeerd WA , Wladimiroff Juriy W
Published: October 2008

The ductus venosus is a blood vessel functioning exclusively in the fetal circulation. According to many reports it was described for the first time by Giulio Cesare Arantius (Bologna 1530–1589) in his bookDe humano foetu libellus(1563) and it is often referred to as the ductus Arantii. Thorough research, however, has made it clear that Andreas Vesalius described this vessel in 1561 in his bookExamen observationium Falloppii, which was published three years later. Moreover, it has been pointed out that the first and second editions of Arantius’s book did not contain a description of the ductus venosus but that this appeared in the 1571 edition.
Magnetic resonance imaging in obstetrics
Authors: Powell MC
Published: October 2008

The discipline of radiology owes its existence today to the discovery of bands of radiation in the electromagnetic spectrum which can penetrate human tissue, and thus can be exploited as windows for imaging. Magnetic resonance (MR) employs radio-frequency radiation and almost certainly represents the final such window in the electromagnetic spectrum for imaging. It is similar to Computerised Tomography (CT) in providing a cross-sectional display of body anatomy with excellent resolution of soft tissue detail. The images are essentially a map of the distribution density of hydrogen nuclei and parameters reflecting their motion in cellular water and lipids. The total avoidance of ionizing radiation, its lack of known hazard and the penetration of bone and air without attenuation, make it a particularly attractive non-invasive imaging technique.
Preterm labour in multiple pregnancies
Authors: Neilson James P , Crowther Caroline A
Published: October 2008

Multiple pregnancy is associated with a high rate of perinatal loss – mainly due to preterm labour but with important contributions from fetal malformation, intrauterine growth retardation and twin-twin transfusion syndrome. The overall perinatal mortality rate is consistently around six times that of singleton pregnancies but the rate rises progressively with the number of fetuses. Rates of 63,164,200,214 and 416 per 1000 births have been recently reported for twins, triplets, quadruplets, quintuplets and sextuplets respectively. In addition to these alarming figures, it should be emphasized that the restricted concept of perinatal mortality obscures the real extent of loss. If we include late abortion (after 20 weeks), late neonatal deaths and deaths in infancy from perinatal causes, as well as the usual indices of perinatal mortality (stillbirths and early neonatal deaths) we find that the total loss rate from twin pregnancy alone doubles and may be close to 10%. Although the rate of loss from multiple pregnancies is now substantially higher than that associated with the pregnancies of diabetic women, the challenge of multiple pregnancy has not been met with the same commitment or organisation of specialized perinatal services as has diabetes.
Oligohydramnios and associated fetal complications
Authors: Flack Nicola J , Fisk Nicholas M
Published: October 2008

During intrauterine life the fetus is bathed in amniotic fluid which provides a low resistance space for free movement and a buffer against external trauma. This fluid is produced in early pregnancy largely as a maternal dialysate, then as a fetal transudate. Fetal urine is the most important source of amniotic fluid after 16 weeks gestation. The control of amniotic fluid is complex and poorly understood; it arises from secondary partitioning of water within the fetoplacental extracellular space and reflects fetal fluid balance.
Control of the fetoplacental circulation
Authors: Macara Lena M , Kingdom John CP , Kaufmann Peter
Published: October 2008

This year marks the 250th anniversary of the discovery by William Hunter of the existence of two distinct circulations within the human placenta. Until relatively recently the placenta has been viewed with “respect” – a passive structure which occasionally elicited fear and anxiety if implanted either too low or too deep. More recently our understanding of perinatal physiology, blood flow regulation and epidemiological data linking prenatal events with adult disease has created renewed interest in the placenta. This review will focus on the regulation of fetal blood flow in the placenta, the possible mechanisms whereby it may be deranged and why this might be relevant to adult disease.
Biochemical screening for Down’s syndrome in the first trimester of pregnancy
Authors: Macintosh MCM , Chard T
Published: October 2008

Down’s syndrome (DS) is the commonest single cause of severe mental retardation and accounts for just under a third of all cases. Until the late 1980’s population screening was based on offering amniocentensis to older women. This made little impact on the prevalence of DS because the majority (approximately 70%) of babies with DS are born to women under the age of 35 (Figure 1).
Categories of intrauterine growth retardation
Authors: Fay Roger A , Ellwood David A
Published: October 2008

Originally all low birthweight infants were considered to be premature. When prematurity was redefined in terms of gestational age (SGA) and not preterm. With the large scale collection of obstetric data the distributions of birthweight at different gestational ages were described and from these, infants who were SGA could be defined. SGA became synonymous with terms such as growth retardation, but it soon became appearent that the two were not necessarily interchangeable. Scott and Usher found that it was the degree of soft tissue wasting rather than birthweight that related to poor perinatal outcome. Miller and Hassanein stated that: “birthweight by itself is not a valid measure of fetal growth impairment”. They used Rorher’s Ponderal Index (weight (g) × 100/length (cm)) to diagnose the malnourished or excessively wasted infants with reduced soft tissue mass. Most studies of intrauterine growth retardation (IUGR) still use low birthweight for gestational age centile as their only definition of IUGR or only study infants who have a low birthweight. Altman and Hytten expressed disquiet about this definition and stated: “There is now an urgent need to establish true measures of fetal growth from which deviations indicating genuine growth retardation can be derived” and that “it is particularly important that some reliable measures of outcome should be established”. In large series of term deliveries published recently, two groups of IUGR infants with different growth patterens have been identified. These studies confirm that birthweight alone is inadequate to define the different types of IUGR. They established that low Ponderal Index (PI) is a measure of IUGR associated with an increased incidence of perinatal problems and that it is time to re-evaluate IUGR in terms of the different types of aberrant fetal growth.
The fetal origins of adult disease
Authors: Barker DJP
Published: October 2008

Recent studies have shown that babies who are small for dates at birth, or who fail to grow in infancy, have, in adult life, raised blood pressure, impaired glucose tolerance, abnormal serum lipids, raised fibrinogen and high death rates from coronary disease, stroke and obstructive lung disease. This has led to the hypothesis that these diseases are ‘programmed’ in utero in response to an adverse environment.
Trends in prenatal diagnosis
Authors: Fogarty Paul P , Dornan James C
Published: October 2008

Prenatal diagnosis is one of the most rapidly expanding areas in medicine and now forms a significant part of Fetal Medicine subspecialization. With the introduction of new technologies in the areas of human genetics, fetal therapy and fetal pathology, those interested must work hard to keep abreast of the latest advances. General obstetricians and those involved in pregnancy counselling must now be aware of all diseases which can be transmitted and for which prenatal diagnosis and screening tests are available and appropriate. There is a plethora of reviews of current techniques and procedures and it would be repetitive for us to produce another such paper. Rather, this article aims to highlight those areas which by definition are changing and where we see future developments occurring. Those readers seeking in depth reviews of present methods are referred to standard texts.
Maternal cardiac disease and pregnancy
Authors: Lotgering Frederik K
Published: October 2008

A woman with heart disease may benefit from early obstetric counselling because it may help to reduce uncertainty or anxiety with regard to her ability to carry a pregnancy at some time in her life and may help her to prevent unwanted pregnancy or to avoid the need for an abortion. Pregnancy imposes an additional burden upon the circulation of a woman with heart disease and additional precautions may therefore be required during the antenatal period, labour, delivery and the puerperium. Nevertheless, with proper care, maternal and fetal outcome is good in most women with cardiac disease.
Doppler ultrasonography in uteroplacental insufficiency
Authors: Arduini Domenico , Rizzo Giuseppe
Published: October 2008

Much of our understanding of uteroplacental insufficiency has been derived from animal research and the study of the pathology of human placental and uterine biopsies. These studies have shown how the placenta plays a major role in the development of normal pregnancy and how placental dysfunction is generally caused by factors interfering with the normal growth of the uteroplacental and/or fetoplacental circulations. These abnormalities lead to a deficient supply of oxygen and nutrients to the fetus and to several complications of pregnancy such as gestational hypertension, preeclampsia and intrauterine growth retardation (IUGR).
The development of fetal hearing
Authors: Hepper Peter G , Shahidullah BS
Published: October 2008

The developmental origins of the ability to hear have been the subject of much debate and speculation. Since time immemorial, there has been much anecdotal evidence that the fetus responds to sound. In contrast, until the late 19th Century, scientific evidence and opinion held that the newborn was deaf and only developed the ability to hear in the first weeks after birth. At the beginning of the 20th Century the prevailing scientific and clinical view changed and it was accepted that the newborn was able to hear at birth. This led to much speculation about, and limited experimental study of, when the individual first started to hear. Detailed study of the ontogency of auditory abilities had to wait until the 1980’s when scientific opinion regarding the abilities of the newborn changed and the ultrasound technology with which to observe the fetus in utero became widely available. Research thus commenced in earnest to investigate the response of the fetus to sound. Despite this increased interest in fetal hearing, experimental studies have concentrated upon the responsiveness to sound in late pregnancy and not on the developmental origine of auditory abilities. It is the aim of this review to examine the ontogenesis of hearing in the fetus.
Asthma in pregnancy
Authors: Nelson-Piercy Catherine , de Swiet Michael
Published: October 2008

Asthma is the most common significant chronic medical condition affecting young adults and it is therefore often encountered in pregnancy. Approximately 3% of women of child-bearing age suffer some degree of asthma and this prevalence is increasing. Some of the apparent increase is due to heightened awareness of the condition, although air pollution and increased childhood exposure to house dust mite may also be contributing.
Antihypertensive therapy during pregnancy
Authors: Chari Radha S , Friedman Steven A , Sibai Baha M
Published: October 2008

Hypertensive disorders in pregnancy are a leading cause of maternal and perinatal morbidity and mortality. Overall, hypertension complicates approximately 10% of pregnancies. The incidence is higher in patients with predisposing factors including nulliparity, multiple gestation, preexisting hypertension or diabetes, a previous pregnancy complicated by preeclampsia-eclampsia, familial history of preeclampsia, hydrops fetalis and rapidly growing hydatidiform moles.
Prenatal diagnosis using fetal cells in the maternal circulation
Authors: Gänshirt D , Garritsen HSP , Holzgreve W
Published: October 2008

Since the introduction of ultrasound into obstetrics during the 1960s, there has been rapid progress in the detection of genetic and nongenetic defects in utero. With the development of sampling procedures like amniocentesis, chorionic villus sampling (CVS) and fetal blood sampling, the obstetrician has been able to obtain fetal tissue and the parallel improvement in laboratory techniques has allowed the diagnosis of chromosomal anomalies and single gene defects from fetal cells. Amniocentesis and CVS have become well established techniques for routine prenatal diagnosis of chromosomal and metabolic disorders and fetal tissue is now accessible throughout all three trimesters.
Fetal vibroacoustic stimulation test: features of the stimulus
Authors: Abrams Robert M , Gerhardt Kenneth J , Richards Douglas S , Peters Aemil JM
Published: October 2008

Fetal reactivity to acoustic stimulation is a long-recognized phenomenon. Obstetrical interest in this phenomenon is usually considered to have begun with peiper’s report in 1925 of marked fetal movements following a pulsed, loud sound. Occasional attention to the subject was given in the subsequent five decades. Read and Miller are often credited with writing the first comprehensive clinical study of the usefulness of acoustic stimulation in evaluating fetal health. A clear finding in this study was the correlation between an abnormal contraction stress test and faliure of the fetus to respond to stimulation.
Brain function in utero unique to the developing fetus
Authors: Koyanagi Takashi , Nabekura Junichi , Nakano Hitoo
Published: October 2008

Behaviour originally depends on precise and specific interconnections between nerve cells. The nervous system itself develops in a series of appropriately timed steps with a temporal sequence characteristic of each neural structure.
The efficacy of echocardiographic criterions for the diagnosis of carditis in acute rheumatic fever
Authors: Vijayalakshmi Ishwarappa B. , Vishnuprabhu Rajan O. , Chitra Narasimhan , Rajasri Ravindra , Anuradha Thejoor V.
Published: October 2008

Background

There is a great need for echocardiographic criterions for accurate diagnosis of carditis in acute rheumatic fever.

Aim

To test the efficacy of proposed echocardiographic criterions for the diagnosis of carditis.

Materials and methods

We studied 333 patients suspected of having acute rheumatic fever, undertaking detailed clinical examination, laboratory tests and meticulous echocardiography in each case. We used previously established echocardiographic criterions for the diagnosis of carditis and subclinical valvitis. In 220 cases (66.06%), both the echo criterions, and the Jones’ criterions, gave positive results. In 52 cases (15.61%), we found evidence of subclinical carditis, in that clinically no murmur was heard, meaning the Jones’ criterions were negative, but the echocardiographic evaluation was positive. In 4 patients clinically diagnosed as having carditis, the Jones’ criterions were positive, but echocardiographic evaluation showed them to have congenitally malformed hearts. In another 57 cases (17.11%), the Jones’ criterions were negative, as were the results of echocardiographic evaluation. These patients were taken as control subjects. On this basis, the echocardiographic criterions had sensitivity of 81% and specificity of 93%.

Conclusion

Using our echocardiographic criterions, it is possible to make a precise diagnosis of carditis or subclinical valvitis. Hence, echocardiography should, in future, be included as a major criterion in the Jones’ system.
Cognitive Therapy with Children and Families: Treating Internalizing Disorders
Authors: Cartwright-Hatton Sam , Murray James
Published: October 2008

Internalizing disorders of childhood and adolescence are common conditions, but until the past decade, had received little scientific scrutiny. This paper overviews the new knowledge that the past decade of research has given us. The early research began by adopting adult models of disorders, and adult-based modes of treatment. This met with moderate success, but the focus now is on testing whether these models are appropriate for younger clients. The good news is that, for adolescents at least, the adult models do seem to be appropriate. The bad news is that, even in well-resourced treatment trials, barely half of all cases remit. In very recent years, there has been a focus on generating developmentally appropriate models of childhood internalizing disorders, and correspondingly, an increasing interest in developing treatment approaches that are appropriate for young people and their families. The paper concludes with our thoughts on the most important questions for research in the next decade.
From theory to research: Contextual predictors of “estar + adjective” and the study of the SLA of Spanish copula choice – a response to Woolsey
Authors: LAFFORD BARBARA A.
Published: October 2008

The use of social vs. cognitive approaches to the study of second language acquisition (SLA) has engendered considerable debate in the field. For instance, the recent Modern Language Journal Focus Issue (Lafford, 2007a) reviewed the ongoing debate between scholars espousing socially- and cognitively-grounded approaches to SLA research and explored the extent to which SLA scholars have answered Firth and Wagner's (1997, p. 286) call for a reconceptualization of SLA “as a more theoretically and methodologically balanced enterprise that endeavours to attend to, explicate, and explore, in more equal measures and, where possible, in integrated ways, both the social and cognitive dimensions of S/FL [second/foreign language] use and acquisition”. Firth and Wagner (1997, p. 286) specifically called for “(a) a significantly enhanced awareness of the contextual and interactional dimensions of language use, (b) an increased emic (i.e., participant-relevant) sensitivity towards fundamental concepts, and (c) the broadening of the traditional SLA data base”.
The uses of Spanish copulas by Chinese-speaking learners in a free writing task
Authors: CHENG AN CHUNG , LU HUI-CHUAN , GIANNAKOUROS PANAYOTIS
Published: October 2008

This study investigates the developmental rate ofestarproduction by Chinese-speaking learners in planned written production. The forms of Spanish copula verbs have no equivalent forms in Chinese in pre-adjectival position (i.e. no copula verb exists between a referent and an adjective in Chinese). This contrast between languages provides a number of opportunities for novel insights into copula acquisition, including universality and developmental dynamics. Thus, this research examines, particularly, factors that are associated withestaruse in a pre-adjectival position. Unlike early copula acquisition studies which examined accuracy rates, this research examines semantic, pragmatic, and lexical characteristics of copula use (Geeslin, 2000, 2003) within the context of free written essays. Beginner and intermediate level Chinese-speaking learners of Spanish seem to acquire copula choice through a lexical and semantic approach. As learner vocabulary expands, pragmatic and semantic features (prior experience and animate-change) become most salient in relation to higher rates of use of estar in a free writing task. While the research methods of this study differ from those of Geeslin (2000, 2003), some findings are comparable. Results indicate that the methods used here can be used to glean further novel insights from the SLA process of Chinese-speaking learners.
The role of discursive features in SLA modeling and grammatical frequency – a response to Cheng, Lu and Giannakouros
Authors: COLLENTINE JOSEPH
Published: October 2008

Initial studies on the acquisition of two Spanish copulas, ser and estar, emerged from a research agenda exploring whether second language (L2) development was driven by universal mechanisms manifested in stages rather than an accumulation of entities (Rutherford, 1987). Concerning the Spanish copulas, the stages of acquisition through which Spanish L2 learners pass seem – with a few exceptions – to be largely uniform (e.g. estar + locative, ser/estar + adjective; VanPatten, 1987; Ryan & Lafford, 1992; Geeslin, 2000). Cheng, Lu and Giannakouros provide one of the first studies which partially test the assumption of universality, examining Mandarin Chinese speakers' copula behaviors over different levels of development. The work of Geeslin as well as Cheng, Lu and Giannakouros is valuable not so much because it provides insights into copula development but rather because this work is building a model for predicting the interaction in general terms between aspectual, semantic, and pragmatic factors and the acquisition of both grammatical and lexical L2 phenomena.
Eventive and stative passives in Spanish L2 acquisition: A matter of aspect
Authors: DE GARAVITO JOYCE BRUHN , VALENZUELA ELENA
Published: October 2008

This paper reports on an empirical study that examined knowledge of eventive and stative passives in the L2 Spanish grammar of L1 speakers of English. Although the two types of passive exist in English, the difference between them is not signaled in any specific way. In Spanish, in contrast, the distinction is marked by the choice of copula:seris used to form eventive passives,estarfor statives. Researchers agree that the two copulas, both of which translate as English “to be”, differ in relation to aspect:estaris perfective while ser is not marked for aspect (Schmitt, 1992). The question was whether L2 learners would be able to acquire the aspectual difference of the copulas and apply it to the formation of the passives. Two main tests were used, a Grammaticality Judgment Task and a Sentence Selection Task. The Grammaticality Judgment Task examined properties of the passives related, among other things, to aspect and agentivity. The Sentence Selection Task focused on the interpretation of the subject: only the subject of ser can be interpreted as generic. Although the learners in general distinguished between grammatical and ungrammatical sentences, they had not acquired the restriction on subject interpretation. These results are explained in terms of interfaces.
Form–meaning mappings in the aspectual domain: What about the L1? A response to Bruhn de Garavito and Valenzuela
Authors: MONTRUL SILVINA
Published: October 2008

Any person who has taught Spanish as a second language or who has interacted with a non-native speaker of Spanish can easily tell that mastering the correct use of the copulasserandestaris very difficult in both spoken and written production. But L2 learners are not alone. The Spanish copulas also present difficulty and frustration for L2 instructors of Spanish, since most pedagogical explanations of the uses ofserandestarprovided in textbooks are incomplete and inaccurate. However, the acquisition of copular constructions has not received the attention it deserves in the acquisition literature, making a special issue ofBilingualism: Language and Cognitiondedicated to this topic particularly welcome. A reason for the scarcity of research in this area may be related to both the linguistic complexity of Spanishserandestarand the inadequacy of many available theoretical treatments to explain their complementary distribution. Although constructions withserandestarare highly frequent in the input, they are grammatically quite intricate, straddling between the levels of morphology, syntax, semantics and pragmatics. Accordingly, Bruhn de Garavito and Valenzuela correctly frame their study within the current debate on interface vulnerability in language development in general, and in adult L2 acquisition in particular (Sorace, 2004; White, in press). In a nutshell, grammatical areas which require the integration of different levels of linguistic knowledge (e.g., syntax–discourse, syntax–morphology, morphology–semantics, etc.) for processing, production, or interpretation, show developmental delays and instability in monolingual and bilingual acquisition. In the case of monolingual acquisition, instability or non-target-like behavior is temporary, but in L2 grammars, instability can persist up to very advanced levels of proficiency, eventually leading to fossilization.
The acquisition ofser,estar(andbe) by a Spanish–English bilingual child: The early stages
Authors: SILVA-CORVALÁN CARMEN , MONTANARI SIMONA
Published: October 2008

This article studies the acquisition of copulas by a Spanish–English bilingual between the ages of 1;6 and 3;0, examines the possibility of interlanguage influence, and considers the distributional frequencies of copular constructions in the speech of the child and in the language input from adults. The study is of interest because the bilingual child needs to acquire semantic and syntactic contrasts in Spanish that are not explicitly marked in English. This difference raises questions about the timing of acquisition of the Spanish copulas under pressure from a stronger language, in addition to the language-internal questions concerning the acquisition of the semantics and syntax of these verbs. The results show that copular constructions develop autonomously, but with a slight delay in the acquisition ofestarinterpreted as a possible type of influence from English. The distributional analysis reveals parallels between the child's and the adults' uses of copulas, thus supporting a process of acquisition guided by the nature of the interactions that the child enters into with the adults who surround him.
Commentary on “copular acquisition” – a response to Silva-Corvalán and Montanari
Authors: SERA MARIA D.
Published: October 2008

Studies of copular forms are extremely relevant to issues in philosophy, psychology, and linguistics. Psychologists have recently argued that the most distinctive aspect of human language is its combinatorial nature (e.g., Gentner, 2003; Spelke, 2003). They argue that this linguistic component might be what separates human from animal cognition. As combinatorial elements, copular forms have no equal. However, as the quote from Bertrand Russell implies, copular forms are multi-dimensional and complex. A full understanding of their use, linguistic variation, acquisition, and relation to cognition is a formidable task. While other papers in this special-issue volume of Bilingualism: Language and Cognition will address the different syntactic and semantic functions carried by these forms, in this commentary, I will focus on the relation between the acquisition of copular forms and cognitive development, or more specifically on the development of categorization.
Variation in contemporary Spanish: Linguistic predictors ofestarin four cases of language contact
Authors: GEESLIN KIMBERLY L. , GUIJARRO-FUENTES PEDRO
Published: October 2008

In some contact situations between Spanish and English there is an acceleration of the process of the extension ofestarthat may be due to lack of access to the formal written standard, features of English in particular or general processes of simplification that result from the cognitive demands of bilingualism (Silva-Corvalán, 1994). In our large-scale analysis of data from a contextualized preference task collected in four areas of the lberian Peninsula where Spanish is in contact with a regional language (Basque, Catalan, Galician and Valencian) and in monolingual regions of Spain, we identify differences in the numbers of unanimous responses, and frequency and predictors ofestarselection across populations. We show that more frequent selection ofestaris not a characteristic of all bilingual groups, and several linguistic predictors ofestarare common to all groups. Additionally, we find that more frequent selection ofestaroccurs in some varieties even among bilinguals with ample access to the formal standard.
Through a Glass, Less Darkly?
Authors: Rudolph Almut , Schröder-Abé Michela , Schütz Astrid , Gregg Aiden P. , Sedikides Constantine
Published: October 2008

Self-esteem has been traditionally assessed via self-report (explicit self-esteem: ESE). However, the limitations of self-report have prompted efforts to assess self-esteem indirectly (implicit self-esteem: ISE). It has been theorized that ISE and ESE reflect the operation of largely distinct mental systems. However, although low correlations between measures of ISE and ESE empirically support their discriminant validity, similarly low correlations between different measures of ISE do not support their convergent validity. We explored whether such patterns would reemerge if more recently developed, specific, and reliable ISE measures were used. They did, although some convergent validity among ISE measures emerged once confounds resulting from conceptual mismatch, individual differences, and random variability were minimized. Nonetheless, low correlations among ISE measures are not primarily caused by the usual psychometric suspects, and may be the result of other factors including subtle differences between structural features of such measures.
Improvement in the technique to extract gravity wave parameters from lidar data
Authors: Yang Guotao , Clemesha Barclay , Batista Paulo , Simonich Dale
Published: October 2008

From the analysis of 11 years of INPE lidar profiles and some data from the WIPM lidar, we find that the technique proposed by Gardner and Voelz (1987) for gravity wave parameter extraction does not work well at these sites. At São José dos Campos (23° S) and Wuhan (31°N), Nas occurrence is very high, and the background layer is often far from a single symmetrical Gaussian, with the result that most spatial power spectra (∼80%) will be distorted as the given examples show. The power spectrum is used to extract wave parameters in the Gardner and Voelz (1987) technique, but this only works well for an undistorted spectrum. To solve this problem, a new method is developed. First, a “connection layer” is constructed, allowing the determination of approximate wave parameters and an improved background layer. The background layer parameters and the wave parameters are then used as the initial input parameters for a Levenberg‐Marquardt fit, leading to a much better fitted background layer and better wave parameters. This new method achieves good agreement between simulated sodium variations and observations, as well as artificial numerically simulated “observations,” as shown in the examples presented in this paper.
Assimilation of satellite reflectance data into a dynamical leaf model to infer seasonally varying leaf areas for climate and carbon models
Authors: Liu Q. , Gu L. , Dickinson R. E. , Tian Y. , Zhou L. , Post W. M.
Published: October 2008

Leaf area index is an important input for many climate and carbon models. The widely used leaf area products derived from satellite‐observed surface reflectances contain substantial erratic fluctuations in time due to inadequate atmospheric corrections and observational and retrieval uncertainties. These fluctuations are inconsistent with the seasonal dynamics of leaf area, known to be gradual. Their use in process‐based terrestrial carbon models corrupts model behavior, making diagnosis of model performance difficult. We propose a data assimilation approach that combines the satellite observations of Moderate Resolution Imaging Spectroradiometer (MODIS) albedo with a dynamical leaf model. Its novelty is that the seasonal cycle of the directly retrieved leaf areas is smooth and consistent with both observations and current understandings of processes controlling leaf area dynamics. The approach optimizes the dynamical model parameters such that the difference between the estimated surface reflectances based on the modeled leaf area and those of satellite observations is minimized. We demonstrate the usefulness and advantage of our new approach at multiple deciduous forest sites in the United States.
Comparison of single‐channel and multichannel aerosol optical depths derived from MAPSS data
Authors: Laszlo Istvan , Liu Hongqing , Ignatov Alexander
Published: October 2008

Previous comparisons of the single‐channel and multichannel aerosol products reported in the Clouds and the Earth's Radiant Energy System (CERES) Single Scanner Footprint (SSF) data sets showed systematic differences that were partly attributed to differences in sampling and cloud screening. This study concentrates on quantifying the aerosol optical depth (AOD) differences when the above differences are absent and exactly the same clear radiances are inputted to the aerosol algorithms used to generate the two products. This is accomplished by retrieving AOD with the single‐channel algorithm at 22 oceanic locations from the reflectance data in the Moderate Resolution Imaging Spectroradiometer (MODIS) Atmosphere Parameters Subset Statistics (MAPSS) data set for the period of 2000–2007 and then by comparing them to the corresponding MODIS AOD data reported in MAPSS. Comparisons of AODs are performed for two MODIS instruments flown onboard the Terra and Aqua platforms at two wavelengths. On average, the mean differences are wavelength and platform dependent. The single‐channel 644‐nm AODs are larger by 0.004–0.015 (∼2–9%) than those from the multichannel algorithm. The mean AOD at 1632 nm from both algorithms are very similar from Terra, but the single‐channel AOD from Aqua at 2119 nm is lower by 0.02 (∼24%). The mean absolute differences are 0.022–0.025 and do not change much with wavelength or platform. Slight dependence of the mean differences on the scattering angle is observed, which is partially explained by the differences between the retrieved aerosol model in the multichannel retrieval and the fixed aerosol model used in the single‐channel algorithm.
First versus subsequent return‐stroke current and field peaks in negative cloud‐to‐ground lightning discharges
Authors: Nag Amitabh , Rakov Vladimir A. , Schulz Wolfgang , Saba Marcelo M. F. , Thottappillil Rajeev , Biagi Christopher J. , Oliveira Filho Alcides , Kafri Ahmad , Theethayi Nelson , Gotschl Thomas
Published: October 2008

We examine relative magnitudes of electric field peaks of first and subsequent return strokes in negative cloud‐to‐ground lightning flashes recorded in Florida, Austria, Brazil, and Sweden. On average, the electric field peak of the first stroke is appreciably, 1.7 to 2.4 times, larger than the field peak of the subsequent stroke (except for studies in Austria where the ratio varies from 1.0 to 2.3, depending on methodology and instrumentation). Similar results were previously reported from electric field studies in Florida, Sweden, and Sri Lanka. For comparison, directly measured peak currents for first strokes are, on average, a factor of 2.3 to 2.5 larger than those for subsequent strokes. There are some discrepancies between first versus subsequent stroke intensities reported from different studies based on data reported by lightning locating systems (LLS). The ratio of LLS‐reported peak currents for first and subsequent strokes confirmed by video records is 1.7 to 2.1 in Brazil, while in the United States (Arizona, Texas, Oklahoma, and the Great Plains) it varies from 1.1 to 1.6, depending on methodology used. The smaller ratios derived from the LLS studies are likely to be due to poor detection of relatively small subsequent strokes. The smaller values in Austria are possibly related (at least in part) to the higher percentage (about 50% versus 24–38% in other studies) of flashes with at least one subsequent stroke greater than the first. The effects of excluding single‐stroke flashes or subsequent strokes in newly formed channels appear to be relatively small.
Using infrared satellite data to drive a thermo‐rheological/stochastic lava flow emplacement model: A method for near‐real‐time volcanic hazard assessment
Authors: Wright Robert , Garbeil Harold , Harris Andrew J. L.
Published: October 2008

We combine two flow simulation models to provide a computationally efficient means of predicting the final dimensions of active lava flows. By using a stochastic approach to predict all the downhill paths that a lava flow could possibly follow and a thermo–rheological model to terminate these paths once the predicted cooling–limited length for the flow has been attained, this approach allows for rapid assessment of the area likely to be inundated by lava. The 1991–1993 eruption of Mount Etna is used as a case study. Lava effusion rate exerts a strong control on the maximum length a lava flow can attain, and we demonstrate how the model can be driven by time–varying effusion rates, obtained from infrared satellite data. As such data are obtained in near–real–time, this approach allows flow simulations to be updated in a timely manner, in response to changing eruption conditions.