bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Exercises in Pure Mathematics with Expository Comments
Authors: Weston J. D. , Godwin H. J.
Published: April 2010

This book is about some of the ideas that are important for students of mathematics at the stage of transition from school to university. It contains 200 exercises on a wide range of interrelated topics in algebra, analysis and geometry, with explanations and informative comments. It has a comprehensive index, and can be used either as a reference book or as a framework for a systematic course of study. The book originated in sets of annotated exercises prepared for students and teachers working to an experimental syllabus of the Welsh Joint Education Committee. It will be useful to undergraduates and others who wish to develop their understanding of fundamental mathematics.
Byzantine Jewry in the Mediterranean Economy
Authors: Holo Joshua
Published: April 2010

Using primary sources, Joshua Holo uncovers the day-to-day workings of the Byzantine-Jewish economy in the middle Byzantine period. Built on a web of exchange systems both exclusive to the Jewish community and integrated in society at large, this economy forces a revision of Jewish history in the region. Paradoxically, the two distinct economic orientations, inward and outward, simultaneously advanced both the integration of the Jews into the larger Byzantine economy and their segregation as a self-contained body economic. Dr Holo finds that the Jews routinely leveraged their internal, even exclusive, systems of law and culture to break into - occasionally to dominate - Byzantine markets. In doing so, they challenge our concept of Diaspora life as a balance between the two competing impulses of integration and segregation. The success of this enterprise, furthermore, qualifies the prevailing claim of Jewish economic decline during the Commercial Revolution.
The effects of a 30-month dietary intervention on bone mineral density: The Postmenopausal Health Study
Authors: Moschonis George , Katsaroli Ioanna , Lyritis George P. , Manios Yannis
Published: April 2010

Low dietary Ca intake and vitamin D insufficiency have been implicated as part of the aetiology leading to osteoporosis. The aim of the present study was to examine the effects of a 30-month dietary intervention that combined supplementation of dairy products fortified with Ca and vitamin D3 and lifestyle and nutrition counselling sessions on bone mineral density (BMD) of postmenopausal women. Sixty-six postmenopausal women (aged 55–65 years) were randomised into a dietary group (DG; n 35), receiving daily and for the first 12 months 1200 mg Ca and 7·5 μg vitamin D3, while for the next 18 months of intervention 1200 mg Ca and 22·5 μg vitamin D3 through fortified dairy products, and a control group (CG; n 31) receiving neither counselling nor dairy products. The DG was found to have more favourable changes in arms (P < 0·001), total spine (P = 0·001) and total body BMD (P < 0·001) compared with the CG. Furthermore, a significant increase was observed for the DG in lumbar spine BMD (0·056; 95 % CI 0·009, 0·103), which was not found to differentiate significantly compared with the change observed in the CG (P = 0·075). In conclusion, the present study showed that intakes of vitamin D of about 22·5 μg/d and of Ca close to the recommended level of 1200 mg from fortified dairy foods for 30 months, with compliance ensured by lifestyle and nutrition counselling sessions, can induce favourable changes in arms, total spine and total body BMD of postmenopausal women.
Remembering Asian Anticolonialism, Again
Authors: Morris Rosalind C.
Published: April 2010

Gertrude Stein once remarked that history must be understood not as the passage of time, but as the killing of centuries. This killing of centuries takes a very long time, she added, and she discerned the final death throes of the nineteenth century—a period in thrall to science and the idea of civilizational progress—in the middle of World War II. Being an American Jew in France, that denouement was realized, for her, by Hitler's Germany, in the moment that it fell to American industrial war making. But Stein's insight might as easily and as correctly be applied to the analysis of anticolonialism and the collapse of European rule in South and Southeast Asia. It was there, after all, that the ideology of a civilizational mission was revealed in all its hypocrisy. Such, at least, is the impression one gathers from reading the works of Christopher Bayly and Tim Harper, Leela Gandhi, and Benedict Anderson, each of whom offers a perspective on the history of empire's end, and the rise of revolutionary and nationalist independence movements in Asia. As counterpoint to their insistently particularizing narration of these movements, James C. Scott sketches a deep history of recurrent antistatism as the context in which European empires made their ill-fated claims to civilizational exceptionalism, and in which anarchism could emerge as a technics of ungovernability.
The wake behind a cylinder rolling on a wall at varying rotation rates
Authors: STEWART B. E. , THOMPSON M. C. , LEWEKE T. , HOURIGAN K.
Published: April 2010

A study investigating the flow around a cylinder rolling or sliding on a wall has been undertaken in two and three dimensions. The cylinder motion is specified from a set of five discrete rotation rates, ranging from prograde through to retrograde rolling. A Reynolds number range of 20–500 is considered. The effects of the nearby wall and the imposed body motion on the wake structure and dominant wake transitions have been determined. Prograde rolling is shown to destabilize the wake flow, while retrograde rotation delays the onset of unsteady flow to Reynolds numbers well above those observed for a cylinder in an unbounded flow.

Two-dimensional simulations show the presence of two recirculation zones in the steady wake, the lengths of which increase approximately linearly with the Reynolds number. Values of the lift and drag coefficient are also reported for the steady flow regime. Results from a linear stability analysis show that the wake initially undergoes a regular bifurcation from a steady two-dimensional flow to a steady three-dimensional wake for all rotation rates. The critical Reynolds number Rec of transition and the spanwise wavelength of the dominant mode are shown to be highly dependent on, but smoothly varying with, the rotation rate of the cylinder. Varying the rotation from prograde to retrograde rolling acts to increase the value of Rec and decrease the preferred wavelength. The structure of the fully evolved wake mode is then established through three-dimensional simulations. In fact it is found that at Reynolds numbers only marginally (~5%) above critical, the three-dimensional simulations indicate that the saturated state becomes time dependent, although at least initially, this does not result in a significant change to the mode structure. It is only at higher Reynolds numbers that the wake undergoes a transition to vortex shedding.

An analysis of the three-dimensional transition indicates that it is unlikely to be due to a centrifugal instability despite the superficial similarity to the flow over a backward-facing step, for which the transition mechanism has been speculated to be centrifugal. However, the attached elongated recirculation region and distribution of the spanwise perturbation vorticity field, and the similarity of these features with those of the flow through a partially blocked channel, suggest the possibility that the mechanism is elliptic in nature. Some analysis which supports this conjecture is undertaken.
Internal waves and turbulence in a stable stratified jet
Authors: PHAM HIEU T. , SARKAR SUTANU
Published: April 2010

Direct numerical simulations are performed to investigate the interaction between a stably stratified jet and internal gravity waves from an adjacent shear layer with mild stratification. Results from two simulations are presented: one with the jet located far from the shear layer (far jet) and the other with the shear layer right on top of the jet (near jet). The near jet problem is motivated by velocity and stratification profiles observed in equatorial undercurrents. In the far case, internal waves excited by the Kelvin–Helmholtz (K-H) rollers do not penetrate the jet. They are reflected and trapped in the region between the shear layer and the jet and lead to little dissipation. In the near case, internal waves with wavelength larger than that of the K-H rollers are found in and below the jet. Pockets of hot fluid, associated with horseshoe vortices that originate from the shear layer, penetrate into the jet region, initiate turbulence and disrupt the internal wave field. Coherent patches of enhanced dissipation moving with the mean velocity are observed. The dissipation in the stably stratified near jet is large, up to three orders of magnitude stronger than that in the propagating wave field or the jet of the far case.
Internal gravity waves generated by convective plumes
Authors: ANSONG JOSEPH K. , SUTHERLAND BRUCE R.
Published: April 2010

We present experimental results of the generation of internal gravity waves by a turbulent buoyant plume impinging upon the interface between a uniform density layer of fluid and a linearly stratified layer. The wave field is observed and its properties are measured non-intrusively using axisymmetric Schlieren. In particular, we determine the fraction of the energy flux associated with the plume at the neutral buoyancy level that is extracted by the waves. On average, this was found to be approximately 4%. Within the limits of the experimental parameters, the maximum vertical displacement amplitude of waves were found to depend linearly upon the maximum penetration height of the plume beyond the neutral level. The frequency of the waves was found to lie in a narrow range relative to the buoyancy frequency. The results are used to interpret the generation of waves in the atmosphere by convective storms impinging upon the tropopause via the mechanical oscillator effect.
Scaling of decaying shallow axisymmetric swirl flows
Authors: DURAN-MATUTE M. , KAMP L. P. J. , TRIELING R. R. , van HEIJST G. J. F.
Published: April 2010

There is a lack of rigour in the usual explanation for the scaling of the vertical velocity of shallow flows based on geometrical arguments and the continuity equation. In this paper we show, by studying shallow axisymmetric swirl flows, that the dynamics of the flow are crucial to determine the proper scaling. In addition, we present two characteristic scaling parameters for such flows: Reδ2 for the radial velocity and Reδ3 for the vertical velocity, where Re is the Reynolds number of the swirl flow and δ=H/L is the flow aspect ratio with H the fluid depth and L a typical horizontal length scale. This scaling contradicts the common assumption that the vertical velocity should scale with the primary motion proportional to the aspect ratio δ. Moreover, if this scaling applies, then the primary flow can be considered as quasi-two-dimensional. Numerical simulations of a decaying Lamb–Oseen vortex served to test the analytical results and to determine their range of validity. It was found that the primary flow can be considered as quasi-two-dimensional only if δRe1/2≲3 and δRe1/3≲1.
Immunological responses against human papilloma virus and human papilloma virus induced laryngeal cancer
Authors: Chitose S , Sakazaki T , Ono T , Kurita T , Mihashi H , Nakashima T
Published: April 2010

Objective:

This study aimed to clarify the local immune status in the larynx in the presence of infection or carcinogenesis associated with human papilloma virus.

Methods:

Cytological samples (for human papilloma virus detection) and laryngeal secretions (for immunoglobulin assessment) were obtained from 31 patients with laryngeal disease, during microscopic laryngeal surgery. On histological examination, 12 patients had squamous cell carcinoma, four had laryngeal papilloma and 15 had other benign laryngeal disease. Cytological samples were tested for human papilloma virus DNA using the Hybrid Capture 2 assay.

Results:

High risk human papilloma virus DNA was detected in 25 per cent of patients (three of 12) with laryngeal cancer. Low risk human papilloma virus DNA was detected only in three laryngeal papilloma patients. The mean laryngeal secretion concentrations of immunoglobulins M, G and A and secretory immunoglobulin A in human papilloma virus DNA positive patients were more than twice those in human papilloma virus DNA negative patients. A statistically significant difference was observed between the secretory immunoglobulin A concentrations in the two groups. Patients with laryngeal cancer had higher laryngeal secretion concentrations of each immunoglobulin type, compared with patients with benign laryngeal disease. The study assessed the mean laryngeal secretion concentrations of each immunoglobulin type in the 12 laryngeal cancer patients, comparing human papilloma virus DNA positive patients (n = 3) and human papilloma virus DNA negative patients (n = 9); the mean concentrations of immunoglobulins M, G and A and secretory immunoglobulin A tended to be greater in human papilloma virus DNA positive cancer patients, compared with human papilloma virus DNA negative cancer patients.

Conclusion:

These results suggest that the local laryngeal immune response is activated by infection or carcinogenesis due to human papilloma virus. The findings strongly suggest that secretory IgA has inhibitory activity against infection or carcinogenesis associated with human papilloma virus in the larynx.
The prevalence of family childhood adversities and their association with first onset of DSM-IV disorders in metropolitan China
Authors: Lee S. , Guo W. J. , Tsang A. , He Y. L. , Huang Y. Q. , Zhang M. Y. , Liu Z. R. , Shen Y. C. , Kessler R. C.
Published: April 2010

Background

The prevalence of family childhood adversities (FCAs) and their joint effects on the first onset of subsequent mental disorders throughout the life course are rarely examined, especially in Asian communities.

Method

Face-to-face household interviews of 5201 people aged 18–70 years in Beijing and Shanghai were conducted by a multi-stage household probability sampling method. The first onsets of four broad groups of mental disorders and six categories of FCAs were assessed using The World Mental Health Composite International Diagnostic Interview (WMH-CIDI). Joint effects of FCAs were analyzed by the best fitting of several competitive multivariate models.

Results

FCAs were highly prevalent and inter-correlated. Half of them were in a family-dysfunction cluster. The best-fitting model included each of six types of FCA (with family-dysfunction FCAs being the strongest predictors), number of family-dysfunction FCAs, and number of other FCAs. Family-dysfunction FCAs had a significant subadditive association with subsequent disorders. Little specificity was found for the effects of particular FCAs with particular disorders. Predictive effects of FCAs reached the highest in ages 13–24 compared to ages 4–12 and ⩾25. Estimates of population-attributable risk proportions indicated that all FCAs together explained 38.5% of all first-onset disorders.

Conclusions

Chinese children were exposed to a broad spectrum of inter-related FCAs, as found in Western countries. FCAs related to family dysfunction were especially associated with subsequent mental disorders. Biological and/or environmental factors that mediate these long-term effects should be studied in prospective research on broad groups of FCAs.
Some further reflections regarding the Talbott–Crisp debate on the Augustinian concept of everlasting punishment
Authors: EHRLICH DROR
Published: April 2010

This article consists of a critical discussion of the debate between Thomas Talbott and Oliver Crisp on the philosophical justification for the traditional Augustinian concept of everlasting punishment in hell. First, I outline the debate, describing Talbott's challenges to the Augustinian retributivist understanding of everlasting punishment and Crisp's responses to them. Next, I analyse their main points of disagreement, indicating the strengths and weaknesses of their arguments. Finally, I present conclusions arising from analysis of the debate in the framework of Christian theology, and I discuss possible implications for the thesis of everlasting punishment in monotheistic religious thought in general.
Medium request: Talking language shift into being
Authors: Gafaranga Joseph
Published: April 2010

In his landmark contribution to the field of language shift/maintenance, Fishman maintains that, for language shift to be reversed, “face-to-face, small-scale social life must be pursued in their own right and focused upon directly.” This article responds to this call to examine language shift at the level of face-to-face interaction. It describes a specific interactional practice, referred to as “medium request,” observed in the Rwandan community in Belgium, where language shift is taking place from Kinyarwanda-French bilingualism to French monolingualism. The practice consists in the fact that younger members of the community, when in interaction with adult members, constantly (albeit indirectly) request the latter to “medium-switch” from Kinyarwanda to French. The article therefore describes the practice as a specific type of language/medium negotiation, examines its various strategies, and shows how, through this interactional practice, members of the community actually talk language shift into being. (Medium request, language shift, language maintenance, language/medium negotiation, other-initiated medium repair, embedded medium repair, generalized content repair, targeted content repair, understanding check)
Identity and social conduct in a transient multilingual setting
Authors: Goebel Zane
Published: April 2010

This article focuses on the question of how systems of expectations for social conduct develop in a context characterized by diversity and transience. The empirical focus is a series of women's neighborhood meetings in a transient urban milieu in Indonesia. Drawing on work on semiotic register formation, I argue that expectations for social conduct within this neighborhood are constructed through the positioning of self and others in talk across speech situations. In doing so, I explore interdiscursive relationships between this conversational activity and more perduring signs of personhood and social relations. (Enregisterment, identity, Indonesia, migration, trust)*
CONTRIBUTIONS OF GEOARCHAEOLOGY TO MESOAMERICAN STUDIES
Authors: Sheets Payson
Published: April 2010

A survey of the Mesoamerican geoarchaeological literature published from 1990 to the present—in celebration of Ancient Mesoamerica's first 20-year katun anniversary—shows the full spectrum of small, focused projects to broad-range programs. Some scholars defend subdisciplinary boundaries and only do their research as physical science. Others combine natural with social science investigations, and some delve well into the humanities. I suggest here that the more successful programs are the latter because I believe the human experience in ancient Mesoamerica does not fit neatly into one or two of our Western disciplinary categories. Hopefully the next katun can be characterized by more open inquiry including the fullest range of scholarship from the natural sciences, through the social sciences, and embracing the humanities. The growth of new “bottom-up” approaches and post-structural theory—often including agency, practice theory, and resistance—help broaden inquiry and therefore bode well for the next katun.
AZTEC STUDIES
Authors: Nichols Deborah L. , Evans Susan Toby
Published: April 2010

Aztec culture provides a gateway to Mesoamerican studies because it represents the connecting point between the pre-Hispanic past and the globalized present. Current research on the Aztecs comes from several disciplines: anthropology, history, art history, religion, and literature. The nearly fifty articles on the Aztecs published by Ancient Mesoamerica since its inception in 1990 encompass the various branches of Aztec scholarship. In this article we discuss major themes in recent scholarship on the Aztecs: environment and subsistence, settlement and demography, economy, politics, and social relations, ideology and masterworks, and interregional relations.
The Early Career Paths and Employment Conditions of the Academic Profession in 17 Countries
Authors: Bennion Alice , Locke William
Published: April 2010

The expansion of higher education systems, new demands on institutions and growing pressures on resources have become common trends across most developed countries. They bring increased expectations of academic staff and appear to lead to greater differentiation in their work roles and activities. At the same time, the backgrounds of some academics are changing and they are developing new specialisms and interdisciplinary collaborations, becoming more mobile domestically and internationally and, for some, the profession is becoming increasingly insecure. The Changing Academic Profession study has produced a rich set of data on the preparation of academics for their roles and the individual circumstances of their working lives, among other aspects of the profession. Respondents to the survey reported on the degrees they have attained, the countries in which they studied for them, the age at which they qualified and the nature of the doctoral training they received. This paper explores the early career paths of academics, makes initial comparisons between different higher education systems and begins to explore how some of these national systems interrelate with each other through academic mobility. Respondents also reported on the disciplines they studied and now teach, the number of institutions worked in and their contractual conditions and income. These data give an indication of the various degrees of flexibility and mobility required of – or chosen by – academics in the early and later stages of their careers and the stability, or perhaps rigidity, of different higher education systems and national career patterns. The data also supplement other evidence of the employment conditions and remuneration of scholars in an increasingly globalised academic labour market.1,2 The conditions of academic work are explored through analysis of the views of survey respondents on the facilities, resources and personnel needed to support it and the degree of research collaboration undertaken. Academics from the 17 countries in the study seem more content with the physical and technical resources provided by their institutions than the personnel and funds available to support teaching and research. Finally, it is suggested that the propensity for collaborative or individual research may be partially related to national differences in academics’ mobility during their training for the profession.
Comparison of computational methods for the evaluation of learning potential in schizophrenia
Authors: FISZDON JOANNA M. , JOHANNESEN JASON K.
Published: April 2010

Learning potential (LP) refers to the ability to improve cognitive performance as a result of training. It is typically assessed by test-train-test administrations of a task, wherein changes in pre-post performance are an index of LP. In schizophrenia research, LP has been suggested as a mediator of the relationship between static neurocognition and functional outcome. While a number of studies do indicate that LP assessment improves prediction of functioning beyond standard administrations of the same task, multiple approaches of computing LP indices have been used in this work. Multiple psychometric issues have been raised with respect to computation of change scores, but have not been widely recognized in LP assessment. To address this issue, the current study aimed to evaluate the test-retest reliability, interrelatedness, construct, and criterion validity of several conventional indices of LP, obtained from a test-train-test version of a list-learning task administered to 43 individuals with chronic schizophrenia. Overall, test-retest and intercorrelation coefficients indicated variable reliability and convergence across methods. While LP indices generally correlated more highly with independent measures of neurocognition and community functioning than pretraining list learning scores, coefficients were comparably small. Recommendations and measurement issues inherent to the LP construct are discussed. (JINS, 2010, 16, 613–620.)
Endemic goitre and excessive iodine in urine and drinking water among Saharawi refugee children
Authors: Henjum Sigrun , Barikmo Ingrid , Gjerlaug Anne Karine , Mohamed-Lehabib Abderraháman , Oshaug Arne , Arne Strand Tor , Torheim Liv Elin
Published: April 2010

Objective

To assess the prevalence of enlarged thyroid volume (Tvol) in Saharawi refugee children, and their urinary iodine concentration (UIC), and to identify possible sources of excess iodine intake.

Design

A cross-sectional survey was performed during January–February 2007. Tvol was measured by ultrasound and iodine concentration was analysed in casual urine samples, in household drinking water and in milk samples from household livestock.

Setting

The study was undertaken in four refugee camps in the Algerian desert.

Subjects

The subjects were 421 Saharawi children, 6–14 years old.

Results

Enlarged Tvol was found in 56 % (Tvol-for-age) and 86 % (Tvol-for-body-surface-area) of the children. The median (25th percentile–75th percentile, P25–P75) UIC was 565 (357–887) μg/l. The median (P25–P75) iodine concentration in household drinking water was 108 (77–297) μg/l. None of the children had UIC below 100 μg/l, 16 % had UIC between 100 and 299 μg/l, and 84 % had UIC above 300 μg/l. There was a positive association between Tvol and whether the household possessed livestock.

Conclusions

The children are suffering from endemic goitre and high UIC caused probably by an excessive intake of iodine. The excessive iodine intakes probably originate from drinking water and milk.
SHARP LOGARITHMIC DERIVATIVE ESTIMATES WITH APPLICATIONS TO ORDINARY DIFFERENTIAL EQUATIONS IN THE UNIT DISC
Authors: CHYZHYKOV I. , HEITTOKANGAS J. , RÄTTYÄ J.
Published: April 2010

New estimates are obtained for the maximum modulus of the generalized logarithmic derivatives f(k)/f(j), where f is analytic and of finite order of growth in the unit disc, and k and j are integers satisfying k>j≥0. These estimates are stated in terms of a fixed (Lindelöf) proximate order of f and are valid outside a possible exceptional set of arbitrarily small upper density. The results obtained are then used to study the growth of solutions of linear differential equations in the unit disc. Examples are given to show that all of the results are sharp.
Low temperature CH4 and CO2 clathrate hydrate near to mid-IR spectra
Authors: Dartois E. , Schmitt B. , Deboffle D. , Bouzit M.
Published: April 2010

The physical behaviour of methane and carbon dioxide clathrate hydrates, specific crystallographic ice crystals are of major importance for the earth and may control the stability of gases in many astrophysical bodies such as the planets, comets and possibly interstellar grains. Such models claim they provide an alternative trapping mechanism modifying the absolute and relative composition of icy bodies and can be at the source of late time injection of gaseous species in planetary atmospheres. However, there is a clear need to detect them directly. We provide in this study the laboratory recorded signatures of clathrate hydrates in the near to mid-infrared for astrophysical remote detection. These laboratory experiments will in a near future allow to follow the kinetic formation by diffusion in dedicated experiments, another important step to implement, to understand and model their possible presence in space.
Sedna, 2004 VN112 and 2000 CR105: the tip of an iceberg
Authors: Gomes Rodney S. , Soares Jean S.
Published: April 2010

We review two main scenarios that may have implanted Sedna, 2004 VN112 and 2000 CR105 on their current peculiar orbits. These scenarios are based on perihelion lifting mechanisms that acted upon primordial scattered icy bodies. Supposing that the Sun was formed in a dense star cluster and that the gas giants were also forming while the cluster was still dense, an inner Oort cloud that includes Sedna at its inner edge could have been formed by the circularization of icy leftovers orbits scattered by the gas giants. A putative planetary mass solar companion can also produce a similar population of icy bodies through a perihelion lifting mechanism induced by secular resonances from the companion. A third scenario also dependent on a primordial dense cluster may contribute to adding a significant number of extrasolar icy bodies to the main solar component of the population created by the cluster model. These extrasolar objects are transferred to Sun orbits from the scattered disk of passing stars that were numerous in the dense primordial environment. We compare the scenarios as to the orbital distribution of the induced populations as well as their total mass. We conclude that both the cluster model and the solar companion model can produce icy body populations consistent with Sedna's orbit. It is also quite possible that this inner Oort cloud may be composed of roughly one tenth of extrasolar objects.
The discovery rate of new comets in the age of large surveys. Trends, statistics, and an updated evaluation of the comet flux
Authors: Fernández Julio A.
Published: April 2010

We analyze a sample of 58 Oort cloud comets (OCCs) (original orbital energiesxin the range 0 <x< 100, in units of 10−6AU−1), plus 45 long-period comets with negative orbital energies or poorly determined or undeterminedx, discovered during the period 1999-2007. To analyze the degree of completeness of the sample, we use Everhart's (1967 Astr. J 72, 716) concept of “excess magnitude” (in magnitudes × days), defined as the integrated magnitude excess that a given comet presents over the time above a threshold magnitude for detection. This quantity is a measure of the likelihood that the comet will be finally detected. We define two sub-samples of OCCs: 1)new comets(orbital energies 0 <x< 30) as those whose perihelia can shift from outside to the inner planetary region in a single revolution; and 2)inner cloud comets(orbital energies 30 ≤x< 100), that come from the inner region of the Oort cloud, and for which external perturbers (essentially galactic tidal forces and passing stars) are not strong enough to allow them to overshoot the Jupiter-Saturn barrier. From the observed comet flux and making allowance for missed discoveries, we find a flux of OCCs brighter than absolute total magnitude 9 of ≃0.65 ± 0.18 per year within Earth's orbit. From this flux, about two-thirds corresponds to new comets and the rest to inner cloud comets. We find striking differences in theq-distribution of these two samples: while new comets appear to follow an uniformq-distribution, inner cloud comets show an increase in the rate of perihelion passages withq.
Non-gravitational forces and masses of some long-period comets. The cases of Hale-Bopp and Hyakutake
Authors: Sosa Andrea , Fernández Julio A.
Published: April 2010

By means of a simple non-gravitational force model of the cometary nucleus, which relies on the observed light curves assumed to be a good representation of the water sublimation rate, we estimate the masses of a sample of long-period comets (LPCs).

A critical issue of our method is the assumption of a correlation between visual heliocentric magnitudes and water production rates. This is a necessary assumption because of the sparse observational data of gas production rates (with the exception of very few comets like Hale-Bopp or Hyakutake). In this regard we present here a new correlation for LPCs. We also present the preliminary results for the masses of comets Hale-Bopp and Hyakutake.
Numerical simulations of Jupiter Family Comets; physical and dynamical effects
Authors: Di Sisto Romina P. , Fernández Julio A. , Brunini Adrián
Published: April 2010

We present results from numerical simulations of a Jupiter family comet (JFC) population (orbital periods P < 20 yr and Tisserand parameters in the range 2 < T < 3.1) originated in the Scattered Disk and transferred to the Jupiter's zone through gravitational interactions with the Jovian planets. We shall call ‘non-JFCs’ those comets coming from the same source, but that do not fulfill the previous criteria (mainly because they have periods P > 20 yr). We have carried out series of numerical simulations of fictitious comets with a purely dynamical model and also with a more complete dynamical - physical model that includes besides nongravitational forces, sublimation and splitting mechanisms. We obtained better fits with models including physical effects, and in particular our best fits are for four splitting models with a relative weak dependence on q, and a mass loss in every splitting event that is smaller/greater for higher/lower frequencies respectively. The mean lifetime of JFCs with radii R > 1 km and q < 1.5 AU is found to be of about 150-200 revolutions (~103 yr). We find a total population of JFCs with radii R > 1 km within Jupiter's zone of 450 ± 50 and a mean lifetime of about 150-200 revolutions (~103 yr) for those getting q < 1.5 AU. The population of JFCs + non-JFCs with radii R > 1 km in Jupiter-crossing orbits may be about ~2,250 ± 250. Most of non-JFCs have perihelia close to Jupiter's orbit.

We also present maps of the densest zones of JFCs in the orbital element space.
How to take into account the relativistic effects in dynamical studies of comets
Authors: Venturini Julia , Gallardo Tabaré
Published: April 2010

Comet-like orbits with low perihelion distances tend to be affected by relativistic effects. In this work we discuss the origin of the relativistic corrections, how they affect the orbital evolution and how to implement these corrections in a numerical integrator. We also propose a model that mimics the principal relativistic effects and, contrary to the original “exact” formula, has low computational cost. Our model is appropriated for numerical simulations but not for precise ephemeris computations.
Long-term dynamics of Methone, Anthe and Pallene
Authors: Callegari Nelson , Yokoyama Tadashi
Published: April 2010

We numerically investigate the long-term dynamics of the Saturn's small satellites Methone (S/2004 S1), Anthe (S/2007 S4) and Pallene (S/2004 S2). In our numerical integrations, these satellites are disturbed by non-spherical shape of Saturn and the six nearest regular satellites. The stability of the small bodies is studied here by analyzing long-term evolution of their orbital elements.

We show that long-term evolution of Pallene is dictated by a quasi secular resonance involving the ascending nodes (Ω) and longitudes of pericentric distances (ϖ) of Mimas (subscript 1) and Pallene (subscript 2), which critical argument is ϖ2−ϖ1−Ω1+Ω2. Long-term orbital evolution of Methone and Anthe are probably chaotic since: i) their orbits randomly cross the orbit of Mimas in time scales of thousands years); ii) long-term numerical simulations involving both small satellites are strongly affected by small changes in the initial conditions.
The Distribution of Main Belt Asteroids with Featureless Spectra from the Sloan Digital Sky Survey Photometry
Authors: Ribeiro Anderson O. , Roig Fernando
Published: April 2010

In this work, we propose to analyse the existence of possible correlations between the taxonomic classes of asteroids showing featureless spectra –i.e. a flat continuum with no absorption bands– and their orbital properties. We compute the mean spectral slope of 14 753 asteroids using the photometric data from the Sloan Digital Sky survey Moving Objects Catalog (SDSS-MOC4). Although the quality of these data is not comparable in resolution to the spectroscopic data, the amount of observations in the SDSS-MOC4 is more than 20 times larger that in the available spectral databases. This allows us to obtain a statistically significant result.
A Simple Model for the Secular Light Curve of Comet C/1996 B2 Hyakutake
Authors: Rondón Eduardo , Ferrín Ignacio
Published: April 2010

The secular light curves of comets (Ferrín, 2005) give a large amount of physical information on the cometary nucleus. We have developed a model that allows the prediction of a secular light curve, from which we derive parameters like the orientation of the rotational axis (I, φ) and optical thickness of the cometary coma. The model is based on the paper published by (Cowan & A'Hearn, 1979). To do the calculation we found a correlation between the water production rate and the reduced magnitude. We obtain probable orientations of the nucleus pole for several combinations of parameters for comet C/1996 B2 Hyakutake.
The Development of End-State Comfort Planning in Preschool Children
Authors: Weigelt Matthias , Schack Thomas
Published: April 2010

We investigated the development of the end-state comfort effect in young children. Fifty-one children from three age-groups (3, 4, and 5 years old) participated in the study. They performed the dowel placing task, which required them to reach for a horizontal dowel and to insert one of its ends into a target disk. Depending on which end was instructed, end-state comfort could be reached by picking up the dowel either with an overhand or with an underhand grip. All children reached for the dowel with an overhand grasp when this resulted in a comfortable end-state (i.e., thumb-up posture). A different pattern emerged when an underhand grip had to be selected. Here, 18% of the 3-year-olds, 45% of the 4-year-olds, and 67% of the 5-year-olds used an underhand grip and finished the action comfortably. For the first time, these results show a distinct pattern of gradual improvement in children’s sensitivity to reach end-state comfort across three age-groups.
Spatiotemporal variability of the precipitation dipole transition zone in the western United States
Authors: Wise Erika K.
Published: April 2010

El Niño‐Southern Oscillation‐related hydroclimatic variability in the western United States is characterized by a north–south dipole pattern of precipitation anomalies with opposing signs. Here I use a high‐resolution dataset to analyze spatiotemporal patterns in the transition zone between the centers of opposite association. Results indicate that the transition zone is spatially limited west of the continental divide, consisting of a narrow zone within the 40–42°N latitude band and portions of eastern Washington, eastern Oregon, and western Colorado. The transition zone was narrower when the Southern Oscillation Index and the Pacific Decadal Oscillation (PDO) were in a constructive phase and during the negative Atlantic Multidecadal Oscillation phase. Although the transition zone has remained remarkably stationary across the Great Basin, shifts (likely PDO‐related) have occurred over time in the West Coast states. Implications for water resource planning in river basins underlying the transition zone vary by region.
On the relationship between lower magnitude thresholds and bias in epidemic‐type aftershock sequence parameter estimates
Authors: Schoenberg Frederic Paik , Chu Annie , Veen Alejandro
Published: April 2010

Modern earthquake catalogs are often described using spatial‐temporal point process models such as the epidemic‐type aftershock sequence (ETAS) models of Ogata (1998). Earthquake catalogs often have issues of incompleteness and other inaccuracies for earthquakes of magnitude below a certain threshold, and such earthquakes are typically removed prior to fitting a point process model. This paper investigates the bias in the parameters in ETAS models introduced by the removal of the smallest events. It is shown that in the case of most of the ETAS parameters, the bias increases approximately exponentially as a function of the lower magnitude cutoff.
Martian atmosphere as observed by VIRTIS‐M on Rosetta spacecraft
Authors: Coradini A. , Grassi D. , Capaccioni F. , Filacchione G. , Tosi F. , Ammannito E. , De Sanctis M. C. , Formisano V. , Wolkenberg P. , Rinaldi G. , Arnold G. , Barucci M. A. , Bellucci G. , Benkhoff J. , Bibring J. P. , Blanco A. , Bockelee‐Morvan D. , Capria M. T. , Carlson R. , Carsenty U. , Cerroni P. , Colangeli L. , Combes M. , Combi M. , Crovisier J. , Drossart P. , Encrenaz T. , Erard S. , Federico C. , Fink U. , Fonti S. , Ip W.‐H. , Irwin P. G. J. , Jaumann R. , Kuehrt E. , Langevin Y. , Magni G. , McCord T. , Mennella V. , Mottola S. , Neukum G. , Orofino V. , Palumbo P. , Piccioni G. , Rauer H. , Schmitt B. , Tiphene D. , Taylor F. W. , Tozzi G. P.
Published: April 2010

The Rosetta spacecraft accomplished a flyby of Mars on its way to 67P/Churyumov‐Gerasimenko on 25 February 2007. In this paper we describe the measurements obtained by the M channel of the Visual and Infrared Thermal Imaging Spectrometer (VIRTIS‐M) and the first scientific results derived from their analysis. The broad spectral coverage of the VIRTIS‐M in the IR permitted the study of various phenomena occurring in the Martian atmosphere; observations were further exploited to achieve accurate absolute radiometric calibration. Nighttime data from the VIRTIS‐M constrain the air temperature profile in the lower atmosphere (5–30 km), using variations in CO2 opacity at 4.3 μm. A comparison of this data with the global circulation model (GCM) by Forget et al. (1999) shows a trend of slightly higher air temperature in the VIRTIS‐M retrievals; this is accompanied by the presence of moderate decreases (∼5 K) in large sections of the equatorial region. This is potentially related to the occurrence of water ice clouds. Daytime data from the VIRTIS‐M reveal CO2 non–local thermodynamic equilibrium emission in the high atmosphere. A mapping of emission intensity confirms its strict dependence on solar zenith angle. Additionally, devoted limb observations allowed the retrieval of vertical emission intensity profiles, indicating a peak around 105 km in southern tropical regions. Ozone content can be effectively monitored by the emission of O2 (a1Δg) at 1.27 μm. Retrieved emission intensity shows that polar regions are particularly rich in ozone. Aerosol scattering was observed in the 1–2.5 μm region above the night region above the night disk, suggesting the occurrence of very high noctilucent clouds.
Impact experiments with a new technique for acceleration of projectiles to velocities higher than Earth's escape velocity of 11.2 km/s
Authors: Kadono T. , Sakaiya T. , Hironaka Y. , Otani K. , Sano T. , Fujiwara T. , Mochiyama T. , Kurosawa K. , Sugita S. , Sekine Y. , Nishikanbara W. , Matsui T. , Ohno S. , Shiroshita A. , Miyanishi K. , Ozaki N. , Kodama R. , Nakamura A. M. , Arakawa M. , Fujioka S. , Shigemori K.
Published: April 2010

The impact velocities of asteroids on Earth and other terrestrial planets can be greater than 10 km/s, and impacts at these high velocities can produce significant effects on the planetary surfaces. However, since macroscopic (>∼0.1 mm) projectiles with an aspect ratio of ∼1 are not easily accelerated to more than 10 km/s in laboratories, there are few detailed experimental studies. In this paper, we demonstrate that impact velocities greater than 10 km/s can be achieved with glass and aluminum projectiles of 0.1–0.3 mm in diameter using a high‐power laser, GEKKO XII‐HIPER at Institute of Laser Engineering, Osaka University. The velocity of the projectiles is estimated based on the images taken by high‐speed X‐ray streak and framing cameras. Projectiles collide into copper or LiF plate targets. The copper plates are recovered for analysis. The sizes of craters on the copper plates are not far from the extrapolations from previous work with lower velocities. A tantalum witness plate placed near the copper plates records a large number of secondary craters from each impact. In the case of the impacts of the LiF plates, we observe two emission lines of Li gas using a spectrometer with a streak camera. Thus, we can simulate the hypervelocity impacts with velocities higher than 10 km/s in laboratories.
Magnitude determination using strong ground‐motion attenuation in earthquake early warning
Authors: Lin Ting‐Li , Wu Yih‐Min
Published: April 2010

We use 1661 strong‐motion accelerograms with peak ground acceleration (PGA) larger than 80 Gal (1 Gal = 1.0 cm/s2) from 77 earthquakes recorded by the Taiwan Strong Motion Instrumentation Program (TSMIP) stations to derive a strong‐motion attenuation relationship. This relationship can be used to dynamically define a “Mpga magnitude” for earthquakes using earthquake locations determined by earthquake early warning process. The Mpga magnitude using this strong‐motion attenuation relationship corresponds well with Mw given a sufficient number of PGA readings. MEMS (Micro Electro Mechanical Systems) acceleration sensor could be widely used for ground motion monitoring purposes. Thus, we propose that once a large earthquake has begun, that we might be able to use strong, near‐field (tens of kilometers) PGA values to quickly estimate the earthquake's magnitude, which would improve earthquake early warning.
Microburst precipitation of energetic electrons associated with chorus wave generation
Authors: Hikishima Mitsuru , Omura Yoshiharu , Summers Danny
Published: April 2010

Electron microbursts, which are short‐duration (<1 sec) bursts of energetic electrons that precipitate into the Earth's atmosphere, comprise an important loss process from the outer radiation belt. By means of a self‐consistent full‐particle simulation, we show that microburst precipitation of electrons of energies 10 keV–100 keV accompanies the generation of discrete bursty chorus wave emissions. Specifically, we demonstrate a one‐to‐one correspondence between the electron microbursts and the generation of discrete chorus elements. This simulation study is the first to establish such an exact correlation between electron microbursts and the generation of chorus elements.
Observational evidence for propagation of decadal spiciness anomalies in the North Pacific
Authors: Sasaki Yoshi N. , Schneider Niklas , Maximenko Nikolai , Lebedev Konstantin
Published: April 2010

The propagation of density‐compensated (warm/salty or cool/fresh) spiciness anomalies in the North Pacific thermocline is investigated using Argo profiles for the period 2001–2008. A cool/fresh spiciness anomaly on 25 < σθ < 25.5 kg m−3 isopycnals appears in the eastern subtropical North Pacific at 120°W–150°W in 2003–2004 with a salinity anomaly of about −0.15 PSS‐78. This spiciness anomaly migrates southwestward, and arrives in the western tropical North Pacific at 145°E–175°W in 2008 with the salinity anomaly decreasing to about −0.043 PSS‐78. Two warm/salty anomalies are observed to propagate along the same path from 2003 to 2005, and after 2005. The propagation path and speed of the anomalies are in good agreement with advection by the mean geostrophic current. In the course of propagation, the anomalies are diffused and are subject to high frequency injection of spiciness anomalies, especially in the eastern subtropical North Pacific.
SAID: A turbulent plasmaspheric boundary layer
Authors: Mishin E. V. , Puhl‐Quinn P. A. , Santolik O.
Published: April 2010

This paper presents novel features of subauroral ion drifts (SAID) observed from a unique conjunction of the Cluster, DMSP, and Polar satellites, including the discovery of SAID‐related plasma waves. These observations confirm and expand on our proposed concept of the SAID channel being a turbulent boundary layer, formed via a short circuit of the substorm‐injected plasmoid by the plasmasphere. We show that SAID formation is related to enhanced lower hybrid/fast magnetosonic waves. Their excitation leads to anomalous circuit resistivity and magnetic diffusion, similar to the well‐documented plasmoid‐magnetic barrier problem, including impulsive penetration at the magnetopause.