bluuebunny/crossref_metadata_2025 huggingface dataset:
African Americans and U.S. Politics: The Gradual Progress of Black Women in Political Representation
Authors: Kaba Amadu Jacky , Ward Deborah E.
Published: February 2009

This paper argues that since the 1960s, African Americans have substantially increased their political participation in the U.S. political system. It claims that Blacks in the U.S. have built a strong political foundation and that their influence in the country's political system has grown within the past four decades. The paper highlights, however, that more Black women tend to be active participants in the electoral process than Black men and that there is the potential for Black women to equal or surpass Black men in the number of elected officials within their race in the years and decades to come.
Sound climate, energy, and transport policy for a carbon constrained world
Authors: Sovacool Benjamin K
Published: February 2009

This article briefly surveys three emerging global challenges related to climate change, electricity and energy, and transportation before summarizing the contributions from this special issue of Policy & Society. Articles in the issue attempt to inform policymakers, scholars, and even members of the public to make better decisions about energy, electricity, modes of transport, and greenhouse gas emissions. In doing so, they cover a wide range of technologies, policies, scales, and case studies. Such a discussion is urgently needed given the interconnected nature of the world's impending climate, energy, and transport needs.
Host tree age as a selective pressure leading to local adaptation of a population of a polyphagous Lepidoptera in virgin boreal forest
Authors: Berthiaume R. , Bauce É. , Hébert C. , Brodeur J.
Published: February 2009

We tested the hypothesis that host tree age may act as a selective factor and lead to local adaptation of the hemlock looper (Lambdina fiscellaria), a geometrid Lepidoptera that has a wide geographical distribution and has evolved in different eco-zones characterized by different levels of floristic composition, age structure and fragmentation level. Considering that hemlock looper outbreaks mainly occurred in old forests, we compared the biological performances of two populations. The first population was collected in the northern virgin boreal forest, which is dominated by mature and overmature coniferous stands that have not suffered from human disturbance. The other population was collected in the southern mixed-wood forest, which is more diversified and has been modified by forest harvesting. Larvae were reared under controlled conditions on foliage from three age classes of balsam fir trees: juvenile, mature and overmature. Although we measured significant variations of biological performances between the two populations, no significant effect of the age of the balsam fir trees could be detected for males from both populations or for females from the southern population. However, northern females were strongly affected by the age of balsam fir trees on which they fed, as their pupal weight was 12% higher and their fecundity increased by 27% on overmature trees compared with juvenile ones. These results indicate that under the same selective pressure, females adapt their strategy to maximize their fitness, and thus they appear as the driving force of evolution through the local adaptation concept. Furthermore, the two populations evolved in distinct habitats and their adaptation reflects selective pressures occurring inside their original environment. This is the first report on local adaptation of an herbivore that is mediated by host tree age. Changes in forest age structure may have a considerable impact on insect local adaptation and presumably on their population dynamics.
ASSESSING INNOVATIONS LACKING DEVELOPED SUPPLY MARKETS: A SIMPLE EX ANTE MODEL APPLIED TO ROCK PHOSPHATE USE IN RICE IN WEST AFRICA
Authors: ERENSTEIN OLAF
Published: February 2009

New technologies often lack a developed supply market, which makes it problematic to estimate future profitability. This paper develops a simple methodology to circumvent this problem based on the concepts of break-even and expected marginal rate of return. The methodology estimates ex ante a range of target threshold prices: the range of maximum prices that farmers are likely to be willing to pay. Only if the future market is able to supply the new technology within or below the threshold price range is significant adoption likely. The target threshold prices can be used to reorient technology development and delimit recommendation domains. The paper applies the methodology to the case of rock phosphate in upland rice in western Cote d'Ivoire. The paper shows that for rock phosphate to be viable for upland rice farmers its on-farm price should generally not surpass Euro cents 5.7–8.1 per kg of rock phosphate.
Vagrant benthos (Annelida; Polychaeta) associated with Upper Ordovician carbonate mud-mounds of subsurface Gotland, Sweden
Authors: ERIKSSON MATS E. , HINTS OLLE
Published: February 2009

Micropalaeontological investigations of Upper Ordovician carbonate mud-mounds and enclosing strata of subsurface Gotland, Sweden, demonstrate that jaw-bearing polychaetes formed the most diverse faunal element associated with these build-ups. Although not present within the mound cores (intra-mound facies), scolecodonts, or polychaete jaws, occur abundantly immediately below and particularly above the mounds; the supra-mound facies also has the most diverse fossil assemblages. By contrast to the scolecodont distribution, the most diverse conodont faunas were recorded in the intra-mound facies. This reinforces the fact that scolecodont and conodont abundance and diversity numbers are commonly inverse to one another, suggesting that these metazoans occupied different niches and responded differently to taphonomical processes. The polychaete assemblage has no less than 27 species belonging to 12 genera, of whichOenonites,MochtyellaandPistoprionare the most abundant. The assemblage has a characteristic Baltic signature and is similar in taxonomic composition to coeval ones from other areas of the Baltoscandian palaeobasin, such as that of present-day Estonia. A principal component analysis clusters the Gotland assemblage most closely to those recorded from shallow to transitional shelf environments of Estonia, indicating that the mud-mounds were formed in such environments.
Narrative performance and parental scaffolding of shy and nonshy children
Authors: REYNOLDS KAILEY PEARL , EVANS MARY ANN
Published: February 2009

This study examined differences in performance between 20 shy and 20 matched nonshy children on a narrative task and in the way parents scaffolded their narrative performance when reading the wordless bookFrog, Where Are You, by Mercer Mayer. Consistent with previous research, results demonstrated that shy children spoke less than their nonshy peers and volunteered less story content. Parents, however, did not differ in how they scaffolded their children's speech turns, nor in the amount of semantic information they provided. Thus, these communicative differences were not accounted for by differential adult scaffolding. Implications for encouraging more verbal behavior from shy children and for the design of wordless storybooks are discussed.
VALIDITY OF SUBSAMPLING AND “PLUG-IN ASYMPTOTIC” INFERENCE FOR PARAMETERS DEFINED BY MOMENT INEQUALITIES
Authors: Andrews Donald W.K. , Guggenberger Patrik
Published: February 2009

This paper considers inference for parameters defined by moment inequalities and equalities. The parameters need not be identified. For a specified class of test statistics, this paper establishes the uniform asymptotic validity of subsampling,mout ofnbootstrap, and “plug-in asymptotic” tests and confidence intervals for such parameters. Establishing uniform asymptotic validity is crucial in moment inequality problems because the pointwise asymptotic distributions of the test statistics of interest have discontinuities as functions of the true distribution that generates the observations.

The size results are quite general because they hold without specifying the particular form of the moment conditions—only 2 +δmoments finite are required. The results allow for independent and identically distributed (i.i.d.) and dependent observations and for preliminary consistent estimation of identified parameters.
REX BERGSTROM’S CONTRIBUTIONS TO CONTINUOUS TIME MACROECONOMETRIC MODELING
Authors: Nowman K. Ben
Published: February 2009

This paper reviews the contributions of Rex Bergstrom to the development of continuous time dynamic disequilibrium macroeconomic modeling since the early 1960s. The models provide an elegant integration of economic theory with analysis of steady state and stability properties. The subsequent contributions of his Ph.D. students, spawned by Bergstrom’s work over the years, is also reviewed. It was Bergstrom’s early pioneering vision 40 years ago of formulating and estimating continuous time models that underlies much of the research in that area of econometrics and finance today.
A more efficient technique to collect seeds dispersed by bats
Authors: Galindo-González Jorge , Vázquez-Domínguez Guillermo , Saldaña-Vázquez Romeo A. , Hernández-Montero Jesús R.
Published: February 2009

Seeds dispersed and deposited by wind, animals and other dispersal agents are a fundamental component of natural forest succession, plant regeneration and population maintenance, aside from increasing a population's genetic pool in tropical ecosystems (Henry & Jouard 2007, Muscarella & Fleming 2007, Wilson & Traveset 2000). Frugivorous bats and birds are ideal vectors for long-distance seed dispersal; therefore, studies of the food habits of frugivores and the specific identities of the dispersers are essential for understanding ecological patterns and processes in tropical environments. Studies related to succession processes, the frequency, number and composition of seeds dispersed by animals are essential in order to generate new data and hypotheses, consequently the method and quality of obtaining data are important.
The geometry of complex hyperbolic packs
Authors: PLATIS IOANNIS D.
Published: February 2009

Complex hyperbolic packs are hypersurfaces of complex hyperbolic planeH2ℂwhich may be considered as dual to the well known bisectors. In this paper we study the geometric aspects associated to packs.
Population size, breeding performance and habitat use of the Black-winged Pratincole Glareola nordmanni
Authors: KAMP JOHANNES , KOSHKIN MAXIM A. , SHELDON ROBERT D.
Published: February 2009

The population of the Black-winged Pratincole Glareola nordmanni has declined significantly during the course of the 20th century, resulting in a classification as ‘Near Threatened’ and ‘Endangered’ in the Global and European Red Data Books, respectively. Reasons for the decline are largely unknown due to a lack of information on the breeding ecology of the species. We studied breeding performance and habitat use of the Black-winged Pratincole in two areas in Kazakhstan and evaluated a new world population estimate. Colony size ranged from two to 180 pairs and differed significantly between the study areas. Mean breeding success was 1.30 ± 0.16 (mean ± SE) fledged chicks per breeding pair in Central Kazakhstan, and 0.59 ± 0.13 (mean ± SE) fledged chicks per breeding pair in NE Kazakhstan. Habitat types preferred were intensively grazed natural steppe, abandoned and fallow fields, shores of freshwater and brackish lakes and solonchaks (salt pans). Factors influencing habitat selection were quantified the first time for this species: the probability of occurrence of breeding colonies was highest near human settlements, within 3km of open water and where sward heights were low or intermediate, indicating a reliance on heavy grazing and water.

Using data from six surveys across the whole breeding range, we calculated a new world population estimate of 76,000–95,000 breeding pairs, which is substantially higher than previous estimates. We discuss colony size, habitat use and population trends in the light of changing landscape conditions in the steppe zone and suggest an increase in habitat available to Black-winged Pratincole due to an increase in the area of fallow fields and a change in grazing regimes since the collapse of the Soviet Union in 1991.
The status of the Fuerteventura StonechatSaxicola dacotiae: a new evaluation using distance sampling and GIS
Authors: GARCIA-DEL-REY EDUARDO
Published: February 2009

The status of the ‘Endangered’ Fuerteventura StonechatSaxicola dacotiae,a western Palearctic single island endemic, was assessed 22 years after the first population estimate of 1,300–1,700 individuals was made by Bibby and Hill (1987). Using GIS and Distance Sampling methodologies, the population on Fuerteventura in 2008 was estimated at 1,035 birds (832–1,287) with the species more abundant on hillsides than in gullies. Within the island's three main massifs (i.e. north, west and south) the highest encounter rate was recorded in the northern massif. This study supports the category of ‘Endangered’ for this species, which does face the obvious threat from development, particularly in the south of the island. The species is also on the endangered list nationally (Spain) and in Europe but has not as yet been evaluated by the Canarian Government. I suggest, based on results of this study, that serious effort should be put in to improving knowledge of the distribution range of this endemic (either by modelling or by systematic visits to sites). An official monitoring programme should be developed and implemented with special attention paid to the three main mountain ranges of this island and particularly to the southern massif which is suffering the highest rate of habitat loss.
Random Graphs from a Minor-Closed Class
Authors: McDIARMID COLIN
Published: February 2009

A minor-closed class of graphs is addable if each excluded minor is 2-connected. We see that such a classof labelled graphs has smooth growth; and, for the random graphRnsampled uniformly from then-vertex graphs in, the fragment not in the giant component asymptotically has a simple ‘Boltzmann Poisson distribution’. In particular, asn→ ∞ the probability thatRnis connected tends to 1/A(ρ), whereA(x) is the exponential generating function forand ρ is its radius of convergence.
SUBSTANCE MISUSE DURING PREGNANCY: ITS EFFECTS AND TREATMENT
Authors: MORAN P , MADGULA RM , GILVARRY E , FINDLAY M
Published: February 2009

Prenatal care reduces the impact of illicit drug use on perinatal outcomes. Women who misuse substances are often excluded from mainstream society and, on becoming pregnant, feel guilty about their drug misuse and the potential effects this could have on their unborn baby. These women are vulnerable in many ways and agencies must ensure that they are not excluded from antenatal care. The latest enquiry into maternal deaths published in the UK (CEMACH report) highlights how women with socially complex lives who died were far less likely to have sought antenatal care early in pregnancy or to remain in regular contact with maternity services. Of the women who died from any cause, 11% had problems with substance abuse of whom 60% were registered addicts. Gaps in communication between agencies was highlighted as a particular problem.
Transcatheter closure of a patent arterial duct with the Amplatzer duct occluder in the area of a large thoracic aortic aneurysm
Authors: Ghazi Payam , Haji-Zeinali Ali-Mohammad
Published: February 2009

We describe successful closure of a persistently patent arterial duct, using an Amplatzer occluder, in the presence of a large thoracic aortic aneurysm in the area of the ductal ampulla. Although percutaneous closure is more difficult in this setting, because of the risk of traumatising the fragile tissues, it can safely be performed. In our case, it produced a decrease in the size of the aneurysm, and permitted us to delay endovascular repair of the thoracic aorta.
Fracture and dislocation of a pulmonary stent after cardiac massage
Authors: Moszura Tomasz , Michalak Krzysztof W. , Sysa Andrzej
Published: February 2009

Following a Glenn procedure, a stent was implanted into the pulmonary artery to relieve stenosis. After the procedure, the patient developed bradycardia and became asystolic. Resuscitation was successful following cardiac massage, but subsequent catheterization revealed the stent to be broken in two, with shift of the distal fragment. The two parts were stabilized and connected by implantation of an additional CP stent.
Suspicion, diagnosis, and successful surgical treatment of anomalous origin of the anterior descending coronary artery from the pulmonary trunk
Authors: Semizel Evren , Bostan Ozlem M. , Cil Ergün
Published: February 2009

Anomalous origin of the anterior descending coronary artery from the pulmonary trunk is very rare. We suspected such anomalous origin in a boy aged 2.5 years owing to the echocardiographic demonstration of mitral regurgitation and abnormal diastolic flow in the ventricular septum. The diagnosis was confirmed by angiography. The anomalous artery was successfully reimplanted into the aorta.
New anticoagulants – towards the development of an "ideal" anticoagulant
Authors: Haas
Published: February 2009

Currently available anticoagulants, such as unfractionated heparin, low molecular weight heparins and vitamin K antagonists, have proved effective in the prevention and treatment of thromboembolic disorders. However, these drugs have some drawbacks, such as unpredictability (in the case of unfractionated heparin), non-specificity and parenteral mode of administration, which limit their use in the clinical setting. There is a need for new agents with efficacy similar to that of these classes of anticoagulants and none of their associated drawbacks. Advances are being made in the development of more convenient and more specific drugs, with the aim to improve substantially the prevention and management of thromboembolic disorders. This review will emphasize how the development of an ideal anticoagulant, with potential benefits including high efficacy, safety, low levels of bleeding, fixed dosing, rapid onset of action, ability to bind clot-bound coagulation factors and no requirement for therapeutic monitoring, is a considerable challenge. This review will present the most relevant preclinical data, as well as the clinical studies performed to date, for several drug classes. Direct thrombin inhibitors, such as dabigatran etexilate, will be reviewed, as well as indirect (fondaparinux and idraparinux) and direct (rivaroxaban, apixaban, among others) Factor Xa inhibitors, Factor IXa inhibitors and monoclonal antibodies against Factor IX/IXa.
New techniques for endovascular treatment of peripheral artery disease with focus on chronic critical limb ischemia
Authors: Zeller  , Sixt  , Rastan
Published: February 2009

Chronic critical limb ischemia (CLI) represents the most advanced stage of peripheral arterial disease. CLI is associated with a high risk for limb loss and revascularization, either by surgical or endovascular means, is absolutely mandatory. With traditional techniques such as balloon angioplasty, limb salvage was reported in 80 to 90%. However, in case of failed revascularization attempt, limb loss was 40 to 50% and mortality approximately 20%. This review summarizes new developments in endovascular techniques which increase the acute and chronic success rate of endovascular procedures and therefore potentially further improve limb salvage rates. Special crossing and re-entry devices designed for femoro-popliteal application may even facilitate recanalization of long chronic occlusions. Improved stent design, atherectomy devices and drug coated balloons improve patency rates and may result in improved wound healing rates. Moreover, downsizing the catheter tools for infrapopliteal artery disease opens new horizons also for the treatment of complex below-the-knee lesions representing an increasing patient population due to the increasing prevalence of diabetes and end-stage renal failure.
Nephrogenic systemic fibrosis
Authors: Vosshenrich  , Reimer
Published: February 2009

Neprogenic Systemic Fibrosis (NSF) is a relative new disease affecting predominantly patients with severely impaired kidney function. Strict adherence to a concordant clinical and pathological definition has allowed for careful separation of this entity from other fibrosing disorders, leading eventually to the realization that gadolinium based contrast agents were closely associated with its onset. Gadodiamide and similarly unstable Gd-CA should the refore not be used in patients with renal insufficiency. The clinical symptoms of NSF vary considerably from patient to patient. NSF should be suspected in renal failure patients presenting any possible NSF symptom appearing in the weeks after Gdenhanced MRI. Suspected cases should have a skin biopsy taken from an affected region for the histological confirmation or rejection of the diagnosis. There are no established curative treatments to NSF patients. Prevention is the only alternative. Guidelines for the daily routine seem to be the right way. When NSF is identified the primary goal is reversal of underlying renal failure or renal transplantation. In addition, use of physical therapy and pain control is mandatory. One of the best news in late 2007 is the decreasing rate of newly detected NSF cases. In the case this development continues, NSF may become an historical disease in the near future.
Coarctation of the abdominal aorta: Demonstration of a rare anomaly using contrast-enhanced MR-angiography
Authors: Schubert
Published: February 2009

We describe a case of aortic coarctation at the level of the infrarenal abdominal aorta which is encountered in less than six individuals in one million. In contrast to aortic narrowing above or including the renal arteries, this seems to be a relatively benign anomaly without systemic hypertension or impaired renal function. For the first time in this type of anomaly, contrast-enhanced MR angiography (ce-MRA) on a multi-receiver channel MR system, with an 8-channel phased array coil and parallel imaging was used. Ce-MRA displayed a tortuous, narrowed aortic segment that was found to be associated with mesenteric artery stenosis and compression of the orthotopic left renal vein, also known as the nutcracker phenomenon. All major aortic branches could be depicted using 3D surface-shaded displays and subvolume maximum intensity projections (MIPs). Collateral vessels of the abdominal wall were identified using whole-volume MIPs. Since the majority of aortic malformations are diagnosed at a younger age, and many suffer from renal insufficiency, we conclude that ce-MRA will eventually place conventional DSA as the modality of choice in malformations of the abdominal aorta.
Messung dispositioneller Selbstkontroll-Kapazität
Authors: Bertrams Alex , Dickhäuser Oliver
Published: February 2009

Zusammenfassung. Selbstkontrolle ist definiert als die Überwindung oder Modifikation von Reaktionstendenzen. Die dispositionelle Selbstkontroll-Kapazität hängt positiv gerichtet mit einer Vielzahl von Maßen adaptiven Verhaltens zusammen. Zur ökonomischen Messung dispositioneller Selbstkontroll-Kapazität wurde in der vorliegenden Arbeit die vornehmlich eingesetzte Kurzform der Self-Control Scale von Tangney, Baumeister und Boone (2004) ins Deutsche adaptiert. Dazu wurde die übersetzte Gesamtskala bestehend aus 36 Items Studierenden (N = 316, Studie 1) und Schülern (N = 335, Studie 2) vorgelegt. Die in der Gesamtskala enthaltene Kurzskala aus 13 Items erwies sich in beiden Studien als eindimensional, reliabel und valide bezüglich erwarteter Zusammenhänge mit Kriteriumsvariablen. Der Vergleich zwischen Kurz- und Gesamtskala zeigte, dass die Kosten der ökonomischeren Messung hinsichtlich Reliabilität und Validität gering sind.
Effekte des adaptiven Testens auf die Motivation zur Testbearbeitung am Beispiel des Frankfurter Adaptiven Konzentrationsleistungs-Tests
Authors: Frey Andreas , Hartig Johannes , Moosbrugger Helfried
Published: February 2009

Zusammenfassung. Seit den 1970er Jahren wird weithin angenommen, dass adaptives Testen im Vergleich zu nicht-adaptivem Testen eine motivationssteigernde Wirkung hat. In den letzten Jahren wurde jedoch wiederholt auch die gegensätzliche Sichtweise vertreten, dass sich adaptives Testen motivationsmindernd auswirken kann. Zur Klärung dieser Kontroverse wurde der Effekt adaptiven Testens mit dem Frankfurter Adaptiven Konzentrationsleistungs-Test (FAKT; Moosbrugger & Heyden, 1997 ) auf die Motivation zur Testbearbeitung experimentell untersucht (N = 79). Zwei unabhängige Stichproben bearbeiteten entweder eine adaptive oder eine nicht-adaptive Testform des FAKT. Die Motivation zur Testbearbeitung fiel in der adaptiven Versuchsbedingung signifikant niedriger aus als in der nicht-adaptiven Versuchsbedingung, p = .045, η2 = .051. Das Ergebnis widerspricht dem seit drei Dekaden weitgehend als Faktum angenommenen motivationssteigernden Effekt adaptiven Testens. Weitere Analysen zeigen, dass der motivationsmindernde Effekt adaptiven Testens vor allem auf die subjektive Einschätzung der Erfolgswahrscheinlichkeit zurückzuführen ist und nicht auf andere motivationale Komponenten wie die subjektive Misserfolgsbefürchtung oder die empfundene Herausforderung.
Evolution of tidal amplitudes in the eastern Pacific Ocean
Authors: Jay David A.
Published: February 2009

Global sea level (GSL) rise is well documented. However, changes in high waters, including the tidal contribution, are sometimes more relevant than GSL rise. Analysis of 34 long tidal records from the Eastern Pacific Ocean shows that K1 and M2 amplitudes (∣K1∣ and ∣M2∣) are increasing, except for ∣M2∣ in the Gulf of Panama. North of 18°N, ∣K1∣ and ∣M2∣ are both growing at 2.2% century−1. The mean increase in total tidal amplitude (0.59 mmyr−1) is less than the present GSL rise (1.7 mmyr−1). However, mean sea level is nearly constant in the NE Pacific, so tidal evolution plays a major regional role in changes in high water levels. The spatial pattern of tidal evolution suggests the influence of large‐scale processes, and the similarity in spatial patterns for ∣K1∣ and ∣M2∣ excludes mechanisms with strong frequency dependence. Increasing tidal amplitudes may impact ocean mixing, nutrient supply, primary production, fisheries, and coastal erosion.
Simulation of the Middle Miocene Climate Optimum
Authors: You Y. , Huber M. , Müller R. D. , Poulsen C. J. , Ribbe J.
Published: February 2009

Proxy data constraining land and ocean surface paleo‐temperatures indicate that the Middle Miocene Climate Optimum (MMCO), a global warming event at ∼15 Ma, had a global annual mean surface temperature of 18.4°C, about 3°C higher than present and equivalent to the warming predicted for the next century. We apply the latest National Center for Atmospheric Research (NCAR) Community Atmosphere Model CAM3.1 and Land Model CLM3.0 coupled to a slab ocean to examine sensitivity of MMCO climate to varying ocean heat fluxes derived from paleo sea surface temperatures (SSTs) and atmospheric carbon dioxide concentrations, using detailed reconstructions of Middle Miocene boundary conditions including paleogeography, elevation, vegetation and surface temperatures. Our model suggests that to maintain MMCO warmth consistent with proxy data, the required atmospheric CO2 concentration is about 460–580 ppmv, narrowed from the most recent estimate of 300–600 ppmv.
Strontium‐86 labeling experiments show spatially heterogeneous skeletal formation in the scleractinian coral Porites porites
Authors: Houlbrèque Fanny , Meibom Anders , Cuif Jean‐Pierre , Stolarski Jaroslaw , Marrocchi Yves , Ferrier‐Pagès Christine , Domart‐Coulon Isabelle , Dunbar Robert B.
Published: February 2009

This paper presents the results of an effort to label calcium carbonates formed by marine organisms with stable isotopes to obtain information about the biomineralization processes. The growing skeleton of the scleractinian coral Porites porites was labeled three times with enhanced abundances of 86Sr. The distribution of 86Sr in the skeleton was imaged with the NanoSIMS ion microprobe with a spatial resolution of ∼200 nm and combined with images of the skeletal ultra‐structure. Importantly, the distribution of the 86Sr label in the P. porites skeleton was found to be strongly heterogeneous. This constrains the physical dimensions of the hypothetical Extracellular Calcifying Fluid (ECF) reservoir at the surface of the growing skeleton, which is implicit in most geochemical models for coral biomineralization. These new experimental capabilities allow for a much more detailed view of the growth dynamics for a wide range of marine organisms that biomineralize carbonate structures.
Three‐dimensional ionospheric electron density structure of the Weddell Sea Anomaly
Authors: Lin C. H. , Liu J. Y. , Cheng C. Z. , Chen C. H. , Liu C. H. , Wang W. , Burns A. G. , Lei J.
Published: February 2009

This paper provides the first three‐dimensional description of the ionospheric density structure of the Weddell Sea Anomaly (WSA). The WSA is characterized by a nighttime ionospheric density greater than that in daytime in the Weddell Sea region around the Antarctic Peninsula during the southern hemisphere summer. It was first observed by ground‐based ionosondes located in the Antarctica back in the 1950s and was further investigated by two‐dimensional maps over the oceans using TEC measurements collected by the TOPEX/Poseidon recently. Although these TEC maps have provided two‐dimensional views for tracking the time‐evolution and spatial coverage of the WSA, the vertical distribution of this peculiar feature is still unavailable. With the vertical ionospheric density profiles observed by the FORMOSAT‐3/COSMIC, three‐dimensional density structure of the WSA is presented here for the first time. Meanwhile, a similar WSA signature is observed in the northern and eastern hemisphere during June solstice by both the GPS‐TEC and the FORMOSAT‐3/COSMIC electron density observations. From the observed altitudinal structure of the WSA during 1800–2400 LT and the similar feature occurred in the opposite hemisphere suggest that the southward offset of the magnetic equator with respect to the geographic equator plays a major role for the WSA formation.
HF radar polar patch and its relation with the cusp during BY‐dominated IMF: Simultaneous observations at two altitudes
Authors: Taguchi S. , Hosokawa K. , Nakao A. , Collier M. R. , Moore T. E. , Sato N. , Yukimatu A. S.
Published: February 2009

Recent studies have shown that the motion of the cusp can be deduced from the energetic neutral atom signals detected in the magnetosphere by the Low Energy Neutral Atom (LENA) imager on the IMAGE spacecraft. We use this approach to understand the characteristics of the formation of a polar patch seen in the dayside ionosphere. During a period of the 28 March 2001 LENA cusp signal event, the SuperDARN radars at Syowa East, Syowa South, and Kerguelen Island identified large‐scale features of a polar patch. A region of high backscatter power observed by the radars separates into two parts around 77°, and its high‐latitude part moves in the poleward and duskward direction. The separation latitude is about 5° higher than the equatorward boundary of the cusp, which is deduced from the LENA cusp signal. We interpret these observations, including features obtained with other SuperDARN radars in the northern hemisphere, as being due to the IMF BY‐controlled zonal jet flow that occurred during a period of increase in ∣BY/BZ∣, without requiring the change in BY polarity that has been often invoked in previous studies. The sharp equatorward boundary of the radar signatures of the polar patch would be an interface between the preexisting flow generally in the antisunward direction and the enhanced zonal flow. The flow enhancement appears to be a fundamental process that forms the large‐scale polar patch at latitudes several degrees higher than the cusp.
Computer simulations on sprite initiation for realistic lightning models with higher‐frequency surges
Authors: Asano T. , Suzuki T. , Hiraki Y. , Mareev E. , Cho M. G. , Hayakawa M.
Published: February 2009

Computer simulations on transient luminous emissions in the mesosphere and lower ionosphere have been performed for realistic lightning modelings with fast‐varying current surges (M components) superimposed on the lightning continuing current (CC). The algorithm used here is an electromagnetic (EM) code, which enables us to estimate self‐consistently the reduced electric field, electron density, conductivity, and luminosity as a function of space and time by solving the Maxwell equations. It is found that M components in the CC with small amplitudes, but with a fast‐varying EM effect, can initiate or enhance the occurrence of sprites. Even for a return stroke (RS) without CC, subsequent high‐frequency current variations (like M components) are found to lead to dramatic changes in the sprite occurrence. The physics underlying these changes is studied by means of, e.g., temporal and spatial variations of luminosity, electron density, and conductivity. As the conclusion, the RS is a fundamental agency for spites, but high‐frequency variations as EM effects exhibit an additional essential influence on sprite occurrence. These computational results are used to offer some useful ideas concerning the unsolved problems of sprites and halos, including polarity asymmetry, long‐delay characteristics, and morphological shapes of sprites.
Numerical modeling of multidimensional diffusion in the radiation belts using layer methods
Authors: Tao Xin , Albert Jay M. , Chan Anthony A.
Published: February 2009

A new code using layer methods is presented to solve radiation belt diffusion equations and is used to explore effects of cross diffusion on electron fluxes. Previous results indicate that numerical problems arise when solving diffusion equations with cross diffusion when using simple finite difference methods. We show that layer methods, which are based on stochastic differential equations, are capable of solving diffusion equations with cross diffusion and are also generalizable to three dimensions. We run our layer code using two chorus wave models and a combined magnetosonic wave and hiss wave model (MH wave model). Both chorus and magnetosonic waves are capable of accelerating electrons to MeV levels in about a day. However, for the chorus wave models, omitting cross diffusion overestimates fluxes at high energies and small pitch angles, while for the MH wave model, ignoring cross diffusion overestimates fluxes at high energies and large pitch angles. These results show that cross diffusion is not ignorable and should be included when calculating radiation belt electron fluxes.
Seismic wave triggering of nonvolcanic tremor, episodic tremor and slip, and earthquakes on Vancouver Island
Authors: Rubinstein Justin L. , Gomberg Joan , Vidale John E. , Wech Aaron G. , Kao Honn , Creager Kenneth C. , Rogers Garry
Published: February 2009

We explore the physical conditions that enable triggering of nonvolcanic tremor and earthquakes by considering local seismic activity on Vancouver Island, British Columbia during and immediately after the arrival of large‐amplitude seismic waves from 30 teleseismic and 17 regional or local earthquakes. We identify tremor triggered by four of the teleseismic earthquakes. The close temporal and spatial proximity of triggered tremor to ambient tremor and aseismic slip indicates that when a fault is close to or undergoing failure, it is particularly susceptible to triggering of further events. The amplitude of the triggering waves also influences the likelihood of triggering both tremor and earthquakes such that large amplitude waves triggered tremor in the absence of detectable aseismic slip or ambient tremor. Tremor and energy radiated from regional/local earthquakes share the same frequency passband so that tremor cannot be identified during these smaller, more frequent events. We confidently identify triggered local earthquakes following only one teleseism, that with the largest amplitude, and four regional or local events that generated vigorous aftershock sequences in their immediate vicinity. Earthquakes tend to be triggered in regions different from tremor and with high ambient seismicity rates. We also note an interesting possible correlation between large teleseismic events and episodic tremor and slip (ETS) episodes, whereby ETS events that are “late” and have built up more stress than normal are susceptible to triggering by the slight nudge of the shaking from a large, distant event, while ETS events that are “early” or “on time” are not.
Induced liquefaction experiment in relatively dense, clay‐rich sand deposits
Authors: Hatzor Yossef H. , Gvirtzman Haim , Wainshtein Ilia , Orian Itay
Published: February 2009

In this paper we report results from a controlled blast‐induced liquefaction experiment at the field scale. The physical and mechanical properties of the materials at the subsurface are characterized by a suite of in situ and laboratory tests, including the Standard Penetration Test (SPT); downhole and cross‐hole seismic velocity tests; density, porosity, and gradation tests; and direct shear tests. Since the blast experiment was performed above groundwater table, the subsurface was saturated by a sequence of controlled infiltration tests. A 50‐kg TNT charge was detonated at a depth of 10 m, and seismic ground motions were recorded in a vertical geophone array positioned at a horizontal distance of 30 m from the blast borehole. Obtained liquefaction features include a water fountain that erupted from the blast borehole, prolonged bubbling of the water surface inside the infiltration trench (a process equivalent to “sand boils” typically observed at sites which have experienced liquefaction), lateral spreading, and surface settlement. We argue that in contrast to conventional predictions, liquefaction may be induced in relatively dense silty and clayey sands (shear wave velocity >300 m s−1; relative density = 63–89%) relatively rich in clays (fines content >30%) and that the driving mechanism should not necessarily be restricted to cyclic shear stress loading.
Satellite‐based midlatitude cyclone statistics over the Southern Ocean: 1. Scatterometer‐derived pressure fields and storm tracking
Authors: Patoux Jérôme , Yuan Xiaojun , Li Cuihua
Published: February 2009

A wavelet‐based method is described for incorporating swaths of surface pressure derived from scatterometer measurements into surface pressure analyses obtained from the European Centre for Medium‐range Weather Forecasts (ECMWF). The resulting modified pressure fields are used to identify low‐pressure centers over the Southern Ocean and to build statistics of midlatitude cyclones during 7 years of the SeaWinds‐on‐QuikSCAT operational period (July 1999 to June 2006). The impact of the scatterometer‐derived pressure swaths is assessed with a statistical analysis of cyclone characteristics (central pressure, radius, depth) performed in parallel on the ECMWF and on the modified pressure fields. More low‐pressure centers (5–10% depending on the season) are identified with the modified pressure fields, in particular incipient lows captured earlier than ECMWF and more short‐lived mesoscale cyclones (with a life span less than 4 days). The cyclones identified with the modified pressure fields are characterized by lower central pressure and tighter isobars on average. A parallel spectral analysis reveals ∼1% additional energy at scales less than 2000 km in the modified pressure fields.
Martian oxygen density at the exobase deduced from O I 130.4‐nm observations by Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars on Mars Express
Authors: Chaufray J. Y. , Leblanc F. , Quémerais E. , Bertaux J. L.
Published: February 2009

Several observations of the O I 130.4‐nm triplet have been analyzed to determine the oxygen density in the Martian upper atmosphere using a three‐dimensional Monte Carlo radiative transfer model describing each line of the triplet. Solar resonant scattering is the dominant source of excitation of the O I 130.4‐nm triplet in the upper atmosphere of Mars. The atomic oxygen density at the exobase is found to be 1.2−0.5+1.2 × 107 cm−3 for solar zenith angles between 20° and 55° and to decrease by a factor of 2 for solar zenith angles between 55° and 90°. Although the major contribution to the observed brightness is produced above the exobase, it is possible to extrapolate the density profile below the exobase and to estimate the [O]/[CO2] mixing ratio as 0.6–1.2% at 135 km. The major source of uncertainty comes from the uncertainty in the absolute calibration, as expected for an optically thick emission, and also, to a lesser degree, from the temperature at the exobase. The profiles are better reproduced by a large exospheric temperature (>300 K), which may suggest the presence of a hot oxygen population.
Analytical solutions for the flow fields near funnel‐and‐gate reactive barriers with hydraulic losses
Authors: Klammler Harald , Hatfield Kirk
Published: February 2009

Permeable reactive barriers (PRBs) are a passive in situ technology that is based on the interception and physical, chemical, and/or biological remediation of a contaminant plume through installation of reactive material in an aquifer. The present work is an extension and generalization of a previous paper and derives analytical expressions for flow fields toward PRBs in two dimensions on the basis of the conformal mapping approach. Considered is the classic funnel‐and‐gate configuration with perpendicular funnel arms (PFGs) as well as PRBs with velocity equalization walls. While the aquifer is assumed to be homogeneous in a uniform far field, the hydraulic conductivity of the reactive material is allowed to take arbitrary values above or below the aquifer conductivity. At the up‐ and down‐gradient interfaces between reactor and aquifer, highly permeable gravel packs are assumed to establish constant head conditions. The flow fields are analyzed regarding the widths and shapes of respective capture zones as functions of PRB type and dimensions, reactor hydraulic resistance (including flow divergence and longevity), and ambient groundwater flow direction. Expressions for discharge fields are developed as needed for particle‐tracking algorithms. Charts of relative capture width are given to facilitate PRB design and may be included in more comprehensive PRB design/optimization approaches. An efficient approach is presented to estimate reactor conductivity and capture flow from monitoring the hydraulic loss at the reactor. Inherent assumptions and results are validated against numerical flow field solutions and water level field data for the PFG PRB at the Moffett Federal Airfield, California.
Siderophore production and biofilm formation as linked social traits
Authors: Harrison Freya , Buckling Angus
Published: February 2009

The virulence of pathogenic microbes can depend on individual cells cooperating in the concerted production of molecules that facilitate host colonization or exploitation. However, cooperating groups can be exploited by social defectors or ‘cheats’. Understanding the ecology and evolution of cooperation is therefore relevant to clinical microbiology. We studied two genetically linked cooperative traits involved in host exploitation by the opportunistic human pathogen Pseudomonas aeruginosa. Clones that defected from cooperative production of iron-scavenging siderophores were deficient in biofilm formation. The presence of such clones in mixed biofilms with a wild-type clone led to reduced biofilm mass. The fitness advantage of siderophore-deficient mutants in the presence of wild-type bacteria was no greater in biofilm than in planktonic culture, suggesting that these mutants did not gain an additional advantage by exploiting wild-type biofilm polymer. Reduced biofilm formation therefore represents a pleiotropic cost of defection from siderophore production.
Time- and vector-resolved magneto-optical Kerr effect measurements of large angle precessional reorientation in a 2×2μm2 ferromagnet
Authors: Keatley P. S. , Kruglyak V. V. , Neudert A. , Delchini M. , Hicken R. J. , Childress J. R. , Katine J. A.
Published: February 2009

The precessional dynamics of a 2×2μm2 CoFe∕NiFe (4.6nm) element stimulated by an in-plane pulsed magnetic field have been investigated using time- and vector-resolved Kerr microscopy measurements and micromagnetic simulations. The time-resolved signals were normalized to in-plane hysteresis loops obtained from the patterned material, and suggest that the magnetization reorients through an angle of 100°±10°. The simulations reveal that only the magnetization of the center region undergoes large angle reorientation, while the canted magnetization at the edges of the element remains pinned. An enhanced Gilbert damping parameter of 0.1 was required to reproduce the experimentally observed Kerr signals.
Electromagnetic properties of ferroelectric/ferromagnetic composite materials base on low temperature cofired ceramic technology
Authors: Ling Weiwei , Zhang Huaiwu , Li Yuanxun , Xie Yunsong , He Ying , Peng Long , Bai Feiming
Published: February 2009

The Ni–Cu–Zn ferrite(NCZF)/BaTiO3(BT) composite materials with mass ratio of BT/NCZF (x)=10%, 20%, 30%, and 40% were synthesized by usual ceramic technology and sintered at 900°C to adapt to the low temperature cofired ceramic technology. The sintered density of the composite with x=40% is 5.454g∕cm3 which is higher than that of the Ni–Cu–Zn ferrite (5.349g∕cm3). The composites with x=10% and 20% have stable values of ε′ and lower values of tanδ. The ε′ of the composite with x=40% decreased from 256 to 39 when the frequency increased from 1MHzto1GHz. The microstructures of the sintered ceramics were observed and analyzed by scanning electron microscopy. The permeability spectra of the composites with different BT contents had been resolved into contributions of domain wall resonance and spin rotation relaxation. The fitting results of permeability dispersion revealed the relationships among the above two mechanisms and microstructures. The influences of different composition on the electromagnetic properties of the composites were investigated.
Study on the dynamics of NaHXO4 and Na3H(XO4)2 (X=S,Se) crystals by observation of the H1 and N23a spin-lattice relaxations
Authors: Lim Ae Ran
Published: February 2009

The relaxation times of the H1 and N23a nuclei in NaHXO4 and Na3H(XO4)2 (X=S,Se) single crystals were investigated. The H1 spin-lattice relaxation times T1 obtained for the four crystals were found to be very different from those determined for MeHXO4 and Me3H(XO4)2 crystals containing metals other than Na. Short H1 relaxation times were found at high temperatures for MeHXO4 and Me3H(XO4)2 when Me=K, Rb, or Cs and X=S or Se, but not for NaHXO4 and Na3H(XO4)2. The reason for this behavior is that the NaHXO4 and Na3H(XO4)2 crystals possess very short hydrogen bonds, these bonds being longer in NaHSO4 than in the other three sodium-based crystals. Furthermore, the temperature dependences of the relaxation rates observed for the N23a nuclei in NaHSeO4, Na3H(SO4)2, and Na3H(SeO4)2 were found to be in accordance with a Raman process (i.e.,T1−1∝T2), whereas the spin-lattice relaxation rate for the N23a nucleus in NaHSO4 exhibited a very strong temperature dependence (T1−1∝T7). This strong temperature dependence and the longer hydrogen bonds in the NaHSO4 crystals may both be related to the superionic character of NaHSO4 at high temperatures.