bluuebunny/crossref_metadata_2025 huggingface dataset:
Major depression in community-dwelling middle-aged and older adults: prevalence and 2- and 4-year follow-up symptoms
Authors: MOJTABAI RAMIN , OLFSON MARK
Published: May 2005

Background. Although major depression is a common condition across the age range, there is some evidence from clinical studies that it may be more persistent and disabling in older adults. This study examined the demographic, socio-economic and clinical factors associated with major depression and with persistence of depressive symptoms at 2- and 4-year follow-ups in a large population sample of middle-aged and older adults.

Method. In a sample of 9747 participants aged over 50 in the 1996 wave of the US Health and Retirement Study, the authors assessed the 12-month prevalence of major depression using the Composite International Diagnostic Interview – Short Form (CIDI-SF). Significant depressive symptoms at the time of 1996, 1998 and 2000 interviews were assessed using a short form of the Center for Epidemiological Studies Depression Scale (CES-D).

Results. The 12-month prevalence of CIDI-SF major depression was 6·6%. With age, prevalence declined, but the likelihood of significant depressive symptoms at follow-ups increased. Both prevalence and persistence of significant depressive symptoms at follow-ups were associated with socio-economic disadvantage and physical illness. Persistence of depressive symptoms at follow-ups was also associated with symptoms of anhedonia, feelings of worthlessness, and thoughts of death at baseline.

Conclusions. Sociodemographic, physical health and a specific profile of depressive symptoms are associated with a poorer course of major depression in the middle-aged and older adults. These indicators may identify a subgroup of patients in need of more careful follow-up and intensive treatment.
The relation between suicidal feelings and mental disorders in the elderly: results from the Berlin Aging Study (BASE)
Authors: BARNOW S. , LINDEN M. , FREYBERGER H.-J.
Published: May 2005

Background. The purpose of this study was to demonstrate the influence of several risk factors (particularly physical and mental disorders, loneliness and housing conditions) on the wish to die in the elderly.

Method. Using data from a population-based sample of 516 senior citizens (70 to 103 years of age) in Berlin (Germany), we compared 54 persons with death wishes with 462 persons without death wishes on several psychosocial risk factors, physical health and psychiatric diagnoses. A logistic regression analysis was also conducted.

Results. The data indicate that the wish to die is strongly associated with the presence of a mental disorder, especially major depression, while higher age, female gender, subjective assessment of physical health and negative living conditions were all only moderately related to death wishes.

Conclusions. Our results emphasize the need for very careful diagnosis of death wishes in the very old and question the view that it is a normal and understandable phenomenon in older age.
Functional magnetic resonance imaging of the cerebral response to visual stimulation in medically unexplained visual loss
Authors: WERRING D. J. , WESTON L. , BULLMORE E. T. , PLANT G. T. , RON M. A.
Published: May 2005

Background. Medically unexplained visual loss occurs in 1 to 5% of patients attending ophthalmology clinics and for many it runs a chronic course. A psychogenic aetiology is presumed in such cases, but little is known about the underlying neural mechanisms. Recent studies have established the value of functional magnetic resonance imaging (fMRI) in understanding the mechanisms of unexplained motor and sensory symptoms. The purpose of this study was to use a similar strategy (fMRI) to evaluate the cerebral responses to visual stimulation in a group of patients with medically unexplained visual loss, in an attempt to determine the underlying neural mechanisms.

Method. Brain activation induced by periodic (monocular) 8 Hz visual stimulation was detected by fMRI in five patients with unexplained visual loss who fulfilled DSM-IV criteria for conversion disorder, and seven normal volunteers. Between-group differences in mean power of activation were estimated by fitting a one-way analysis of variance (ANOVA) model at each intracerebral voxel in standard space.

Results. Compared with controls, patients showed reduced activation in visual cortices, but increased activation in left inferior frontal cortex, left insula-claustrum, bilateral striatum and thalami, left limbic structures, and left posterior cingulate cortex.

Conclusions. This preliminary study has identified novel neural correlates in patients with unexplained visual loss. The abnormal pattern of activation may reflect inhibition of primary visual cortex or a shift towards non-conscious (implicit) processing.
Persecutory delusions and the determination of self-relevance: an fMRI investigation
Authors: BLACKWOOD N. J. , BENTALL R. P. , FFYTCHE D. H. , SIMMONS A. , MURRAY R. M. , HOWARD R. J.
Published: May 2005

Background. People with persecutory delusions regard ambiguous data in the social domain as self-relevant and selectively attend to threatening information. This study aimed to characterize these social cognitive biases in functional neuroanatomical terms.

Method. Eight schizophrenic patients with active persecutory delusions and eight matched normal controls underwent functional magnetic resonance imaging while determining the self-relevance of ambiguous self-relevant or unambiguous other-relevant neutral and threatening statements.

Results. In determining self-relevance, the deluded subjects showed a marked absence of rostral–ventral anterior cingulate activation together with increased posterior cingulate gyrus activation in comparison to the normal subjects. The influence of threat on self-relevance determination did not yield statistically significant differences between deluded and normal subjects.

Conclusions. Abnormalities of cingulate gyrus activation while determining self-relevance suggest impaired self-reflection in the persecutory deluded state. This may contribute to persecutory belief formation and maintenance.
Functional neuroimaging of psychiatric disorders: exploring hidden behaviour
Authors: FLETCHER P. C.
Published: May 2005

From the outset, people have had high expectations of functional neuroimaging. Many will have been disappointed. After roughly a decade of widespread use, even an enthusiastic advocate must be diffident about the impact of the two most frequently used techniques – positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) – upon clinical psychiatry. Perhaps this disappointment arises from an unrealistic expectation of what these techniques are able to tell us about the workings of the normal and the disordered brain. Anyone who hoped for intricate and unambiguous region-to-function mapping was always going to be disappointed. This expectation presupposes, among other things, a thorough understanding of the cognitive functions that are to be mapped onto the brain regions. This understanding, however, while developing, is still rudimentary. Mapping disorder along comparable lines is even more complex since it demands two levels of understanding. The first is of the healthy region-to-function mapping, the second of the disordered region-to-function mapping, which immediately demands a consideration of the nature of the function in the disordered state. After all, someone with schizophrenia, when confronted with a psychological task, might tackle it in a very different way, in terms of the cognitive strategies used, from a healthy person confronted with the same task. The observation that brain activity differs across the two individuals would only be interpretable insofar as one thoroughly understood the processes that each individual invoked in response to the task demands.
Administrative fees and costs of mandatory private pensions in transition economies
Authors: DOBRONOGOV ANTON , MURTHI MAMTA
Published: May 2005

This paper discusses fees and costs of pension companies in transition economies drawing on examples from four countries – Croatia, Hungary, Kazakhstan and Poland – where second pillar pensions have the longest history of implementation. It finds that at current levels, charges are likely to reduce returns on individual account balances by around 1% per annum on average. Exact rates vary by country and company. Fee structures are complex and, generally speaking, poorly understood by consumers. The limited information on costs that is available suggests that, by and large, companies are able to meet their operating costs within a few years after starting operations. There are large sunk costs in setting up business. As a result the industry displays strong economies of scale. Based on the available evidence, the paper estimates fixed costs to be of the order of $35 per account per year (the 95% confidence interval is $21–$49 per account per year). Given costs of this order of magnitude, individual accounts need to be of the order of 4–6% of average wages for the second pillar to be viable i.e. to deliver a return greater than what can be expected from an unchanged first pillar.
Pension reform, savings behavior, and capital market performance
Authors: BÖRSCH-SUPAN AXEL H. , JENS KÖKE F. , WINTER JOACHIM K.
Published: May 2005

This paper shows that the capital market effects of population aging and pension reform are particularly strong in continental European economies such as France, Germany, and Italy. Reasons are threefold: these countries have large and ailing pay-as-you-go public pension systems, relatively thin capital markets and less than benchmark capital performance. The aging process will force the younger generations in these countries to provide more retirement income through own private saving. Capital markets will therefore grow in size and active institutional investors will become more important as intermediaries. The aim of this paper is to show that these changes are likely to generate beneficial side effects in terms of improved productivity and aggregate growth.
Public pensions and the role of real versus financial capital
Authors: WIGGER BERTHOLD U.
Published: May 2005

The paper introduces an unfunded public pension program into an overlapping generations framework recently proposed by Magill and Quinzii (2003). The crucial distinction of the Magill and Quinzii framework is that the financial value of a firm may be lower than the replacement value of its capital. The present paper shows that in this framework unfunded public pensions negatively affect the financial value of firms but have no effect on real capital accumulation and welfare.
On the evaluation of ‘saving-consumption’ plans
Authors: VANDUFFEL STEVEN , DHAENE JAN , GOOVAERTS MARC
Published: May 2005

Knowledge of the distribution function of the stochastically compounded value of a series of future (positive and/or negative) payments is needed for solving several problems in an insurance or finance environment, see e.g. Dhaene et al. (2002a,b). In Kaas et al. (2000), convex lower-bound approximations for such a sum have been proposed. In case of changing signs of the payments however, the distribution function or the quantiles of the lower bound are not easy to determine, as the approximation for the random compounded value of the payments will in general not be a comonotonic sum.

In this paper, we present a method for determining accurate and easy computable approximations for risk measures of such a sum, in case one first has positive payments (savings), followed by negative ones (consumptions).

This particular cashflow pattern is observed in ‘saving–consumption’ plans. In such plans, a person saves money on a regular basis for a certain number of years. The amount available at the end of this period is then used to generate a yearly pension for a fixed number of years. Using the results of this paper we can find accurate and easy to compute answers to questions such as: ‘What is the minimal required yearly savings effort, α, during a fixed number of years, such that we will be able to meet, with a probability of at least (1−ε), a given consumption pattern during the withdrawal period?’
Overview of the Issue
Authors: BROWN JEFFREY , HABERMAN STEVEN , MILEVSKY MOSHE , ORSZAG MIKE
Published: May 2005

This issue features two research articles, three issues & policy articles and a book review section. The first article in the issue is by Berthold Wigger (University of Erlangen-Nuremberg). Wigger's article, “Public Pensions and the Role of Real versus Financial Capital”, revisits the Diamond (1965) model in light of the imperfect markets framework of Magill and Quinzii (2003). Whereas in Diamond (1965), the introduction of a social security system can make a transition generation better off, Wigger derives an equilibrium in imperfect markets in which the outcome is different. The essential difference is that in Diamond's model capital can be changed into consumption goods whereas in the Magill and Quinzii (2003) framework the investment in capital goods such as their housing is irreversible. Though the old benefit from the introduction of social security, the value of their capital goods declines. Hence, the abnormal gains observed by transition generations in social security may be offset elsewhere. This is a potentially relevant result for the US social security debate in which a key focus is how to allocate the legacy burden of social security.
Community outreach to patients with AIDS at the end of life in the
inner city: Reflections from the trenches
Authors: LA FOSSE HECTOR , SCHWARTZ CHARLES E. , CARABALLO ROSA J. , GOEREN WILLIAM , SELWYN PETER A.
Published: May 2005

Indigenous community health outreach workers (CHWs), who serve as a
bridge between underserved, difficult-to-reach minority populations and
health professionals, can play a critical role in bringing palliative care
to patients dying of AIDS and other illnesses in the inner city. Although
the contribution of CHWs in the delivery of “curative” and
preventive services has been well established, little attention has been
given to CHWs in palliative care.

Integrating the medical literature with experiences of a team
providing HIV palliative care in the Bronx, a descriptive typology of
critical stages and components in the work of CHWs in end-of-life care in
the inner city is presented. A longitudinal case narrative, told from the
perspective of the CHW, is used to demonstrate the richness and complexity
of the CHW's role.

The article concludes with a description of the experience of the CHW,
straddling two worlds—the world of the inner city patient and the
world of the health care providers—and explores the special
characteristics of the individuals who can fill this vital role in
palliative care.
Brain cancer and sexual health: A case report
Authors: KRYCHMAN MICHAEL L. , AMSTERDAM ALISON , CARTER JEANNE , CASTIEL MERCEDES , DeANGELIS LISA
Published: May 2005

Objective: Cancer patients often encounter sexual concerns
during the diagnosing, treatment, and recovery phase of their illness.
However, the sexual concerns of these patients are often overlooked. Brain
cancer patients are no exception to this oversight.

Methods: A case report of a 39-year-old patient with a
history of high-grade anaplastic astrocytoma presented to the Sexual
Health Program at the Memorial Sloan-Kettering Cancer Center complaining
of vaginal discharge and several months of amenorrhea. Although the
patient was administered extensive aggressive antineoplastic treatments,
her disease rapidly progressed.

Results: Despite the patient's terminal illness she
continued to have normal sexual thoughts, feelings, and desires; however,
she had difficulty discussing these issues with her partner and caregiver,
who was her mother. An examination by the sexual medicine gynecologist
noted no clinical signs of genital infections; however, there was minimal
vaginal atrophy. Her sexual health laboratory evaluation was extensively
abnormal. Her treatment consisted of intravaginal non-hormonal
moisturizers and vaginal lubricants, counseling, and sexual education. The
patient successfully engaged in sexual contact with her partner by the
third counseling session.

Significance of Results: Almost all oncology patients have
sexual concerns during or following cancer treatment. These patients
should be referred to comprehensive sexual health programs for treatment,
if available.
Living with Multiple Sclerosis: A spiritual journey of loss
Authors: BREITBART WILLIAM
Published: May 2005

I have been living with Multiple Sclerosis (MS) for 20 years. For 20
years I have gone to sleep with MS, awakened with MS, worked with MS, fell
in love with MS, got married with MS, went through five miscarriages with
MS, gave birth to a beautiful son with MS, raised a son whose life would
be marked by the MS of a parent, and most importantly, I will go on living
with MS for as long as fate allows. My wife Rachel has MS.
Das hätte ich nicht essen sollen!
Authors: Hachl Peter , Pietrowsky Reinhard
Published: May 2005

Zusammenfassung. Theoretischer Hintergrund: Auswirkungen gezügelten Essverhaltens auf kognitive Funktionen zeigen sich auch in Ereigniskorrelierten Potentzialen (EKPs). Fragestellung: Verändert die Rückmeldung über den Kaloriengehalt eines Preloads die Wahrnehmung von Nahrungsreizen bei nicht gezügelten und gezügelten Esserinnen? Methode: Gezügelten und nicht gezügelten Esserinnen wurden tachistoskopisch nahrungsbezogene und nicht nahrungsbezogene Worte präsentiert, dabei wurden EKPs abgeleitet. Ergebnisse: In einem frühen Stadium der Reizverarbeitung zeigte sich anhand der P2 ein Effekt bei den nicht gezügelten Esserinnen, hier führten Nahrungsworte zu geringeren Amplituden. Die P3 als Maß für eine bereits kontrollierte Verarbeitung war nur bei gezügelten Esserinnen auf Nahrungsworte größer. Die Rückmeldung eines hohen Kaloriengehalts verstärkte leicht diesen Effekt. Schlussfolgerung: Es scheint elektrophysiologisch nachweisbare Unterschiede in der Wahrnehnung von Nahrungsreizen zwischen den beiden Gruppen zu geben.
Furchtreduktion durch wiederholte Reizkonfrontation bei Spezifischer Phobie vom Tier-Typus
Authors: Weike Almut I. , Hamm Alfons O.
Published: May 2005

Zusammenfassung. Theoretischer Hintergrund: Habituation phobischer Furcht wird häufig als zentraler Wirkmechanismus von Konfrontationsbehandlung angesehen. Neurobiologische Modelle der Furchtreduktion gehen jedoch davon aus, dass für das Verlernen von Furcht komplexere Interaktionen zwischen subkortikalen Affektzentren und frontalen kortikalen Strukturen erforderlich sind. Fragestellung: Ziel der vorliegenden Studie war daher die Untersuchung des Verlaufs der Furchtreduktion bei wiederholter Konfrontation von Phobie-relevanten Reizen bei Spinnen/Schlangen-Phobikern (n = 16) im Vergleich zu einer entsprechenden Kontrollgruppe (n = 16). Methode: Gemessen wurden Hautleitwertreaktionen sowie die Größe der Schreckreaktionen, die beim wiederholten Betrachten Phobie-relevanter im Vergleich zu neutralen Bildern ausgelöst wurden. Ergebnisse: Die Schreckreaktionen der Phobiker waren während des Betrachtens Phobie-relevanter Reize deutlich potenziert im Vergleich zu neutralen Bildinhalten. Diese Potenzierung blieb während der wiederholten Präsentation der Reize unverändert erhalten. Spinnen- und Schlangenbilder führten bei dieser Gruppe auch zu deutlich stärkeren Hautleitwertreaktionen, deren Amplitude sich im Zuge der wiederholten Stimulation aber verringerte und sich schließlich nicht mehr von den Reaktionsgrößen auf neutrale Reize unterschied. Schlussfolgerungen: Diese Befunde illustrieren deutlich, dass sich durch Habituation zwar die Intensität der Furchtreaktion reduzieren lässt, dass aber die neuronalen Schaltkreise, welche der Furchtregulation zu Grunde liegen, kortikal aktiv gehemmt werden müssen.
Biocyberpsychologie:
Authors: Mühlberger Andreas , Petrusek Sonja , Herrmann Martin J. , Pauli Paul
Published: May 2005

Zusammenfassung. Eine erfolgreiche Angsttherapie (Exposition) geht einher mit der Aktivierung und Umstrukturierung von Furchtnetzwerken ( Foa & Kozak, 1986 ). Aktivierung und Umstrukturierung zeigen sich in subjektiven und physiologischen Angstreaktionen, die im Verlauf der Exposition abnehmen. Um die Angstexpositionsbehandlung in der virtuellen Realität (VR) zu untersuchen, wurden in der vorliegenden Studie subjektive Angst sowie Herzraten- und Hautleitfähigkeitsreaktionen von Flugphobikern und Kontrollpersonen während vier virtueller Flüge hinsichtlich Aktivierungs- und Habituationseffekten analysiert. Flugphobiker zeigten erhöhte subjektive und physiologische Reaktionen. Zusätzlich wurden bei Flugphobikern und Kontrollpersonen differenzielle Reaktionen in spezifischen Flugphasen sowie eine Habituation der Angst und der Herzratenreaktion während der vier VR-Flüge gefunden. Virtuelle Flüge aktivieren also die Furchtnetzwerke bei Flugphobikern und sind daher als Test für die Diagnose von Flugphobie sowie zur Expositionsbehandlung anwendbar. Durch die subjektive Angstreaktion und die Herzratenreaktion scheint eine Prognose des Therapieerfolgs möglich.
Reduzierte geruchliche Sensitivität bei Psychopharmaka-freien Patienten mit Major Depression
Authors: Pause Bettina M. , Lembcke Julia , Reese Ina , Hinze-Selch Dunja , Aldenhoff Josef B. , Ferstl Roman
Published: May 2005

Zusammenfassung. Theoretischer Hintergrund: Akut depressiv erkrankte Patienten zeigen eine reduzierte geruchliche Sensitivität, die am deutlichsten in Studien mit medikamentös behandelten Patienten beobachtet wurde. Fragestellung: Es sollte untersucht werden, ob die reduzierte geruchliche Sensitivität genuin mit der depressiven Erkrankung zusammenhängt, oder sekundär mit den Effekten antidepressiver Psychopharmaka einhergeht. Methode: Es wurden 11 Psychopharmaka-freie Patienten in einer akuten Episode einer Major Depression untersucht und mit 11 nicht-depressiven Kontroll-Probanden verglichen. Die geruchliche Sensitivität wurde über die absolute Wahrnehmungsschwelle für Phenyl-ethylalkohol und Menthol bestimmt. Außerdem wurde das subjektive Ausmaß der Angenehmheit, Unangenehmheit, Intensität und Bekanntheit der Gerüche erhoben. Ergebnisse: Die geruchlichen Wahrnehmungsschwellen der depressiven Patienten waren signifikant höher als die der Kontroll-Probanden. Die Reduktion der Sensitivität korrelierte mit dem Schweregrad der Erkrankung. Das Ausmaß der Unangenehmheit der Gerüche wurde von den Patienten tendenziell niedriger eingeschätzt. Schlussfolgerungen: Es wird diskutiert, ob Funktionsabweichungen in Geruchs- und emotionsverarbeitenden Gehirn-Gebieten miteinander einhergehen.
Kognitive Veränderungen beim Fasten
Authors: Pönicke Julia , Albacht Birgit , Leplow Bernd
Published: May 2005

Zusammenfassung. Theoretischer Hintergrund: Auf Grund der extrem eingeschränkten Kalorienzufuhr beim Fasten kommt es zu verschiedenen hormonellen- und Stoffwechselveränderungen. Fragestellung: Sind kognitive Funktionen bei einer Fastendauer von 72 Stunden beeinträchtigt? Methode: Es wurden 15 Teilnehmer eines Buchinger-Fastenkurses und eine nach Geschlecht, Alter und höchstem Schulabschluss parallelisierte Kontrollgruppe an zwei Untersuchungszeitpunkten neuropsychologisch getestet (Aufmerksamkeit, visuo-konstruktive Fähigkeiten, konditional-assoziative Lernfähigkeit, Befindlichkeit). Ergebnisse: In der Fastengruppe ergaben sich nach 72 Stunden signifikant schlechtere Leistungen in Aufmerksamkeitstests und im konditional-assoziativen Lernen. Das allgemeine Befinden war jedoch deutlich besser ausgeprägt als in der nicht fastenden Kontrollgruppe. Das verbale Lernen, die verbale und visuo-räumliche Merkfähigkeit sowie die Visuokonstruktion waren dagegen unbeeinträchtigt. Schlussfolgerung: Bereits nach einer extremen Nahrungseinschränkung von 72 Stunden zeigen sich selektive Beeinträchtigungen der kognitiven Funktionen, welche in milder Ausprägungen denen von Anorexiepatientinnen entsprechen.
Fasten und (Über)-essen:
Authors: Coles Justine , Vögele Claus , Hilbert Anja , Tuschen-Caffier Brunna
Published: May 2005

Zusammenfassung. Theoretischer Hintergrund: Ergebnisse tierexperimenteller Studien lassen darauf schließen, dass Fastenperioden mit reduzierter sympathischer Aktivierung verbunden sind, während Zeiten der normalen Ernährung oder des Überessens mit einer erhöhten sympathischen Aktivierung einhergehen. Fragestellung: In der vorliegenden Studie wurden Parameter der kardialen sympatho-vagalen Balance zu endokrinologischen Variablen des Ernährungszustandes in Beziehung gesetzt. Methode: Sechzehn Frauen mit der Diagnose Bulimia nervosa wurden anhand ihres Serum-Profils in verschiedenen endokrinologischen Parametern (Glukose, Prä-Albumin, Somatomedin-C, TSH, Leptin) in zur Zeit mangelernährt (fastend) und nicht-mangelernährt (nicht-fastend) kategorisiert und mit 14 alters- und BMI-parallelisierten gesunden Frauen verglichen. Zur Bestimmung der sympatho-vagalen Erregungslage wurden die spektralanalytischen Komponenten der Herzfrequenzvariabilität mit autoregressiven Analysen von Ruhedaten berechnet. Ergebnisse: Wie erwartet war die Ruhepulsfrequenz bei fastenden Bulimikerinnen signifikant niedriger als bei nicht-fastenden Bulimikerinnen oder Kontrollpersonen. Nicht-fastende Bulimikerinnen zeigten die niedrigsten vagalen und die höchsten sympathischen Frequenzkomponenten in der Herzfrequenzvariabilität. Schlussfolgerungen: Diese Ergebnisse bestätigen die Hypothese kardialer sympathischer Hemmung während des Fastens und der erhöhten sympathischen Aktivierung bei normaler Ernährung oder Überessen.
Computergestütztes Schreiben von Lernprotokollen
Authors: Schwonke Rolf , Nückles Matthias , Hauser Sabine , Berthold Kirsten , Renkl Alexander
Published: May 2005

Zusammenfassung. Universitäres Lernen fordert von den Studierenden die Entwicklung effektiver Lern- und Arbeitsstrategien. Eine solche Strategie zum Erwerb flexibel anwendbaren Wissens ist die Lerntagebuchmethode. Wir haben untersucht, inwieweit diese Lernstrategie im Rahmen eines Blended-Learning-Szenarios vermittelt werden kann. Als Ergänzung zu einem Seminar schrieben die Studierenden Lernprotokolle in der computergestützten Lernumgebung eHELp. Die Software regt zur Selbstanalyse bisheriger Lern- und Arbeitsgewohnheiten an und unterstützt auf dieser Grundlage (z.B. durch adaptive Bearbeitungshinweise) die Planung, Bearbeitung und Revision von Lernprotokollen sowie deren netzbasierten Austausch zum wechselseitigen Kommentieren und Bewerten. Die Lernumgebung wird in Grundzügen vorgestellt, und erste Evaluationsergebnisse zu ihrer Gebrauchstauglichkeit sowie experimentelle Befunde zur Effektivität der adaptiven Bearbeitungshinweise werden berichtet. Insgesamt zeigen die Befunde, dass das vorgestellte computerbasierte Lernwerkzeug ein Lernen durch Schreiben effektiv unterstützten konnte.
Accelerated polar rain electrons as the source of Sun‐aligned arcs in the polar cap during northward interplanetary magnetic field conditions
Authors: Carlson H. C. , Cowley S. W. H.
Published: May 2005

Identifying the source of electrons producing polar cap arcs (P‐C arcs), ubiquitous under northward interplanetary magnetic field (IMF) conditions, should be a notable step toward solving the long‐standing problem of determining the topology of the magnetosphere for northward IMF. We calculate several electrodynamics limits that follow from a kinetic theory perspective of electrons precipitating into the polar cap from the electron reservoir in the distant magnetospheric tail, for currents sustainable without electron acceleration. We then calculate mutual relationships between several electrodynamics parameters for currents beyond these limits, if electron acceleration processes were to draw the additional current‐carrying electrons from this same reservoir. We compare these theoretical limits and mutual relationships with those actually observed in the polar cap. We conclude that for typical P‐C arc conditions, there is no need to look further than the magnetospheric tail for the source reservoir of electrons needed to provide observed fluxes in either polar rain or P‐C arcs. We close by putting this into the context of relevant models.
Auroral kilometric radiation and magnetosphere‐ionosphere coupling process during magnetic storms
Authors: Seki T. , Morioka A. , Miyoshi Y. S. , Tsuchiya F. , Misawa H. , Gonzalez W. , Sakanoi T. , Oya H. , Matsumoto H. , Hashimoto K. , Mukai T.
Published: May 2005

This paper presents an investigation of a magnetosphere‐ionosphere (M‐I) coupling process during magnetic storms, using observations of auroral kilometric radiation (AKR) in the field‐aligned acceleration region and plasma density variation in the plasma sheet. The main phase electron precipitation, which AKR does not accompany, was confirmed as not characterized by inverted‐V type precipitation but rather by precipitation with Maxwellian type distribution. This indicates the absence of the field‐aligned potential in the M‐I coupling region during the early phase of the magnetic storm. We found that the superdense plasma in the plasma sheet is closely concerned with the AKR activity; that is, the appearance of the superdense plasma sheet seems to suppress the AKR activity. On the basis of these observations we discuss the current‐voltage relation between the magnetosphere and ionosphere. The occurrence of the superdense plasma sheet accompanied with the AKR disappearance was found to be caused by coronal mass ejection (CME) with magnetic cloud. The overall story from the arrival of CME at the Earth to the AKR disappearance in the M‐I coupling region is presented.
Ozone profile retrieval from Stratospheric Aerosol and Gas Experiment (SAGE III) limb scatter measurements
Authors: Rault Didier F.
Published: May 2005

The ability of SAGE III to retrieve the ozone vertical distribution within the atmosphere from limb scatter measurements is being investigated. The sunlight scattered by atmospheric gases and particulates (aerosol and clouds) and the Earth's surface is measured and spectrally dispersed by the SAGE III high vertical resolution spectrometer. The spectral data are shown to contain sufficient information to retrieve ozone density from 10 km (or cloud top) to 50 km at a resolution of about 1 km using ultraviolet and visible channels. Since SAGE III was not designed to operate in limb scatter mode, the radiance measurements are contaminated with significant stray light, and a method had to first be developed and implemented to deconvolve instrumental effects from the data. Furthermore, SAGE III has limited attitude determination capability, and tangent altitude registration has to be derived mostly from measured radiance profiles. Two retrieval algorithms were implemented to infer ozone profiles from measured radiance data: the first one is based on the wavelength triplet method, and the second one uses the multiple linear regression technique. Retrieved ozone profiles are shown for a series of cases and compared with available correlative data measured by ozone sondes, SAGE III in occultation mode, and OSIRIS.
Aerosol particles from tropical convective systems: 2. Cloud bases
Authors: Kojima Tomoko , Buseck Peter R. , Reeves J. Michael
Published: May 2005

Aerosol particles were collected at the altitudes of cloud bases during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment (CRYSTAL‐FACE) and analyzed using transmission electron microscopy. The particles consist of ammonium sulfate (45–90% by number), sea salt (5–45%), mineral dust (1–20%), and anthropogenic materials such as soot and fly ash (<3%). Ammonium sulfate particles have rather uniform, submicron sizes (mostly 0.5 μm across). Sea‐salt particles are larger, apparently having been deliquesced. However, submicron particles are also common. Many contain Na and mixed cation sulfates in addition to NaCl. Mineral dust consists largely of tabular clay particles. Samples from the 28 July flight contain much mineral dust, probably because of transport from the Saharan Desert. Aggregates of sea salt and mineral dust, ammonium sulfate, and soot particles are common. Such mixed aggregates are especially abundant in in‐cloud samples. Cirrus samples from CRYSTAL‐FACE contain many H2SO4 droplets (Kojima et al., 2004), but acidic sulfate particles are rare at the altitudes of cloud bases. H2SO4 probably formed at higher altitudes through oxidation of SO2 in cloud droplets. Sea salt and mineral dust have been reported to be abundant in cloud particles collected using a counterflow virtual impactor (Cziczo et al., 2004), suggesting that these particles were incorporated into the convective systems from the cloud bases and akted as ice nuclei while being vertically transported.
Latitude and altitude variability of carbon monoxide in the Atlantic detected from ship‐borne Fourier transform spectrometry, model, and satellite data
Authors: Velazco Voltaire , Notholt Justus , Warneke Thorsten , Lawrence Mark , Bremer Holger , Drummond James , Schulz Astrid , Krieg Jürgen , Schrems Otto
Published: May 2005

Carbon monoxide (CO) volume mixing ratio (VMR) profiles have been retrieved from ship‐borne solar absorption spectra recorded in the Atlantic between 80°N and 70°S. CO profiles can be retrieved up to 30 km with a maximum altitude resolution of 4 km for a few layers. CO enhancements due to biomass burning have been detected. Recurring enhancements of CO were detected in the upper troposphere (10–15 km) in the equatorial regions and in the southern Atlantic (20°S–30°S). These enhancements could be traced back to African biomass burning sources as well as sources as far as South America. Similar results are observed in CO measurements from space by the Measurements of Pollution in the Troposphere (MOPITT) instrument. However, some enhancements in the upper troposphere especially above the source regions are difficult to distinguish from the MOPITT data. Results from the Model of Atmospheric Transport and Chemistry from the Max Planck Institute for Chemistry (MATCH‐MPIC) show good agreement with the FTIR results. An analysis of the model data allows the quantification of the contributions of different sources such as biomass burning, fossil fuel combustion, and oxidation of methane (CH4) and nonmethane hydrocarbons (NMHC).
Estimation of the aerodynamic roughness length in arid and semi‐arid regions over the globe with the ERS scatterometer
Authors: Prigent Catherine , Tegen Ina , Aires Filipe , Marticorena Béatrice , Zribi Merhez
Published: May 2005

Estimates of the aerodynamic roughness lengths z0 in arid and semi‐arid regions are for the first time provided for the whole globe, using satellite ERS scatterometer observations. A statistical relationship is derived between the ERS scatterometer backscattering coefficients and quality in situ and geomorphological z0 estimates. It is a practical solution to provide realistic roughness maps with large‐scale spatial patterns that are consistent with independent surface characterization. In addition, it makes it possible to analyze the seasonal and interannual variations of this parameter on a global basis. The satellite‐derived surface roughness parameters have been implemented into the dust emission scheme of a global dust cycle model. Dust emission computations are improved when using the ERS derived z0 as input parameter. The spatial correlation between the TOMS observation frequency and the model dust events increases from 0.34 when using fixed z0 to 0.52 when using the satellite‐derived estimates.
Diurnal characteristics of surface level O3 and other important trace gases in New England
Authors: Talbot Robert , Mao Huiting , Sive Barkley
Published: May 2005

Data obtained from spring 2001 to summer 2003 in New England by the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) program were used to document the diurnal characteristics of O3, CO2, NO, and during selected intervals hydrocarbon and oxygenated species. The diurnal cycles of O3 and oxygenated species showed a monotonic rise in mixing ratio following sunrise (replenishment) that was mirrored by nighttime removal (depletion) under the nocturnal inversion. The median depletion rate of O3 was 4.9 ppbv h−1 compared to a replenishment rate of 6.2 ppbv h−1. The significant and rapid loss of O3 at night combined with an anthropogenic hydrocarbon signature dominated by a vehicular source led us to the hypothesis that nocturnal O3 depletion represented the combined effects of dry deposition and titration by NO released from mobile sources. Nighttime removal of O3 averaged 31 ppbv (median of 27 ppbv), with ∼11 ppbv due to dry deposition and ∼20 ppbv loss by titration with NO and NO2. The seasonally averaged diurnal cycles of O3 and NO were very similar from year to year, indicating that although there was large variability in the daily levels of these species, their sources/sinks were quite consistent. Moreover, CO2 and selected hydrocarbons exhibited a diurnal cycle opposite to that of O3, with the highest mixing ratios occurring at night. The diurnal cycles of oxygenated compounds such as methanol, acetaldehyde, methyl ethyl ketone, acetone + propanal, methyl vinyl ketone + methacrolein were investigated for a 2 day time period in July 2003. Our data are among the first to illustrate the diurnal cycle of these compounds. We used these species to demonstrate the importance of vertical mixing in driving the diurnal cycle of ground level O3 in New England. Day/night ratios ranged from 2.3 for acetone + propanal to 11 for methyl vinyl ketone + methacrolein. Deposition velocities of 0.5–1 m s−1 were estimated for these species, which are significantly higher than values used in many models. Such efficient removal may have important implications for the chemical impact of these species, at least on a regional scale.
Lightning electromagnetic environment in the presence of a tall grounded strike object
Authors: Baba Yoshihiro , Rakov Vladimir A.
Published: May 2005

We have analyzed and compared distance dependences of electric and magnetic fields due to a lightning strike to a tall object and due to the same lightning strike to flat ground. In both cases, lightning was represented by a transmission line energized by a lumped voltage source connected at the channel attachment point. The resultant total charge transfer to ground was the same regardless of the presence of strike object. The electric field for the strike‐object case is reduced relative to the flat‐ground case at closer distances from the object. If we assume, in an idealized case, that the return stroke wave front speed is equal to the speed of light, v = c, the current reflection coefficient at the bottom of the strike object ρbot = 1 (grounding impedance Zgr = 0), and that at the top of the object for upward‐propagating waves ρtop = 0 (characteristic impedance of the object is equal to that of the channel Zob = Zch), the ratio of the vertical electric fields on ground for the strike‐object and flat‐ground cases (electric field attenuation factor) will be d/√(d2 + h2), where h is the height of the strike object and d is the horizontal distance from the object. The corresponding ratio for the azimuthal magnetic field is equal to unity. We show that the ratio for either electric or magnetic field increases with decreasing ρbot (ρbot < 1), decreasing ρtop (ρtop < 0 except for the case of ρbot = 0), and decreasing v (v < c), and at larger distances can become greater than unity. We additionally show that the ratio of the far fields for the strike‐object and flat‐ground cases is given by (1 − ρtop) (c/v + 1)/(1 + ρgr), where ρgr is the current reflection coefficient at the lightning channel base when the channel terminates directly on ground. For realistic values of ρtop = −0.5, ρgr = 1, and v = 0.5c, this ratio (far field enhancement factor) is equal to 2.3.
Infrared characterization of water uptake by low‐temperature Na‐montmorillonite: Implications for Earth and Mars
Authors: Frinak E. K. , Mashburn C. D. , Tolbert M. A. , Toon O. B.
Published: May 2005

A large fraction of atmospheric mineral aerosol is composed of clays, such as smectites. Smectites are known to expand upon addition of water, and thus their properties in the atmosphere may vary strongly with relative humidity (RH). Here we report on the adsorption of water to Na‐montmorillonite, a smectite clay. We probe the water uptake under conditions representative of the Earth's troposphere, as well as those relevant for the surface of Mars, of which montmorillonite is a proposed component. Using a vacuum chamber equipped with transmission Fourier transform infrared spectroscopy, we find that Na‐montmorillonite contains 10% water by mass at temperatures from 212 K to 231 K at 50% RH. Surprisingly, the water uptake by Na‐montmorillonite is almost as great as that of deliquesced ammonium sulfate. We also find that although water adsorption to Na‐montmorillonite depends strongly on RH, there is not a strong dependence on absolute temperature. In addition, we find the time required for the clay to become saturated with water decreases with increasing water vapor pressure and is much shorter than suggested in previous studies. We discuss the implications of these results for the Earth's troposphere and the potential role of montmorillonite in the Martian hydrologic cycle.
A simple formula for estimating the magnetic fields generated by tsunami flow
Authors: Tyler R. H.
Published: May 2005

Ocean flow is known to generate magnetic fields which reach land and satellite observatories with detectable amplitudes. But because the expected signal‐to‐noise ratio is poor, one must typically know in advance of the data analyses much about the expected behavior in order to identify these small oceanic contributions. We show that in the case of ocean flow associated with tsunamis, a very simple formula (relating both amplitudes and phase) allows the expected magnetic fields to be directly related to the sea surface displacement. Using sea surface data from Jason 1, the formula gives maximum magnetic amplitudes of about 2 nT for the recent Dec. 26, 2004 tsunami which occurred near the magnetic equator. But near the magnetic poles, the maximum amplitudes reach about 20 nT per meter sea surface displacement. Determining the feasibility for extraction of tsunami generated magnetic signals is of interest in designing early‐warning systems and for remotely tracking tsunami development.
Modelling of strong heterogeneities in aerosol single scattering albedos over a polluted region
Authors: Mallet M. , Pont V. , Liousse C.
Published: May 2005

To date, most models dedicated to the investigation of aerosol direct or semi‐direct radiative forcings have assumed the various aerosol components to be either completely externally mixed or homogeneously internally mixed. Some recent works have shown that a core‐shell treatment of particles should be more realistic, leading to significant differences in the radiative impact as compared to only externally or well‐internally mixed states. To account for these studies, an optical module, ORISAM‐RAD, has been developed for computing aerosol radiative properties under the hypothesis of internally mixed particles with a n‐layer spherical concentric structure. Mesoscale simulations using ORISAM‐RAD, coupled with the 3D mesoscale model Meso‐NH‐C, have been performed for one selected day (06/24/2001) during the ESCOMPTE experiment in the Marseilles‐Fos/Berre region, which illustrate the ability of this new module to reproduce spatial heterogeneities of measured single scattering albedo (ωo), due to industrial and/or urban pollution plumes.
Seismic anisotropy in the Izu‐Bonin subduction system
Authors: Anglin D. Karen , Fouch Matthew J.
Published: May 2005

We evaluated shear wave splitting in local S and teleseismic sS phases from earthquakes that sample the Izu‐Bonin subduction system backarc to examine the dynamics of slab deformation and mantle flow. Splitting times for local S phases range from 0.6 to 1.7 s and 0.9 to 3.2 s for teleseismic sS phases. Fast polarization directions range from ∼NW‐SE to ∼ENE‐WSW and suggest complex mantle deformation across the region. Mantle flow induced by both plate motion and trench‐parallel flow likely combine with fossil slab fabric to control the shear wave splitting observations in the southern portion of Izu‐Bonin. Strong variations in fast polarization directions beneath northern Izu‐Bonin suggest a diversion to trench‐parallel mantle flow behind the Philippine Sea plate. This study demonstrates that many regions of subduction previously inaccessible by conventional shear wave splitting techniques may now be feasibly examined through the use of new, complementary shear wave splitting data sets.
Inositol phosphoceramide synthase is a regulator of intracellular levels of diacylglycerol and ceramide during the G1 to S transition in Saccharomyces cerevisiae
Authors: CERBÓN Jorge , FALCON Alejandro , HERNÁNDEZ-LUNA Carlos , SEGURA-COBOS David
Published: May 2005

We recently reported that DAG (diacylglycerol) generated during sphingomyelin synthesis plays an important role in protein kinase C activation and cell proliferation in Madin–Darby canine kidney cells [Cerbon and Lopez-Sanchez (2003) Biochem. J. 373, 917–924]. In yeast cells, IPC (inositol phosphoceramide) synthase catalyses the transfer of phosphoinositol from phosphatidylinositol to ceramide to form IPC and generates DAG. In the present study, we found that, during the G1 to S transition after N2-starvation, there was a significant increase in the synthesis of IPC accompanied by a progressive increase (up to 6-fold) in the level of DAG. The increased DAG levels coincided with decrements in ceramide and sphingoid base levels, conditions that are adequate for the activation of putative protein kinase C required for the G1 to S transition and proliferation of yeast cells. To separate the role of DAG generated during IPC synthesis from that originating from other sources, we utilized β-chloroalanine and myriocin, inhibitors of serine:palmitoyl-CoA transferase, the first committed step in sphingolipid synthesis, to avoid accumulation of sphingolipid intermediates. When the synthesis of sphingolipids was inhibited, DAG accumulation was significantly decreased and the G1 to S transition was blocked; such blockage was avoided by metabolic complementation with phytosphingosine. The DAG/ceramide ratio was 0.27 and it changed to 2.0 during growth re-initiation, suggesting that the synthesis of phosphosphingolipids could act to switch growth arrest (increased ceramide) to a mitogenic signal (increased DAG), and that this signalling process is preserved in yeast and mammalian cells.