bluuebunny/crossref_metadata_2025 huggingface dataset:
The Ethiopian wolf – an endangered endemic canid
Authors: Gottelli Dada , Sillero-Zubiri Claudio
Published: April 2009

The Ethiopian wolf is a social canid endemic to the highlands of Ethiopia. Today perhaps only 500 individuals survive, making it the world's rarest and probably most endangered canid. Its range has already been reduced and it is threatened by further loss of habitat to high-altitude subsistence agriculture and overgrazing by livestock. Today it survives in only six locations, with the largest and probably only genetically viable population being found in the Bale Mountains National Park. The most immediate threats for the survival of Ethiopian wolves are disease, domestic dogs and human persecution. Improved management in Bale and Simien Mountains National Parks and the establishment of a captive-breeding programme are urgently needed to prevent the extinction of this species.
Causes of land-bird extinctions in French Polynesia
Authors: Roland  , Seitre Julia
Published: April 2009

During a 4-month study in French Polynesia, the authors visited 28 islands, seven of which had never been explored by ornithologists. They collected ecological data on endemic land birds, introduced animals and habitats, focusing particularly on the factors involved in population declines and extinctions. As well as hunting and habitat destruction, it appears that introduced predators play a major role, with the roof rat Rattus rattus being the most dangerous. Rapid action to eradicate introduced predators, coupled with translocations, would be the most effective way to ensure the survival of the remaining bird species.
Protecting Argentina's Wildlife
Authors: Erize Francisco
Published: April 2009

In two years the new Wildlife Foundation in Argentina has created two reserves, one to protect a new species of grebe that was only discovered in 1974 in its only known habitat, the other to protect the endangered endemic race of the pampas deer.
Solution for Siberut?
Authors: Whitten Tony , Whitten Jane , House Alan
Published: April 2009

The authors describe the conservation plan they prepared at WWF's request while they were engaged on a two-year study of the Indonesian island of Siberut in 1976–78. Their plan is designed to conserve as much as possible of both the remarkable wildlife, which includes many endemic species, and the people's traditional way of life. Edited and coordinated by Jeff McNeely, whose article describing Siberut is on page 159, this plan is now being considered by the Indonesian Government.
International Trade in Harp and Hooded Seals
Authors: Barzdo Jon
Published: April 2009

Every year the killing of harp and hooded seals off Newfoundland and in the St Lawrence Gulf raises a public outcry, especially over the clubbing of the whitecoat pups. In 1979 IUCN scientists suggested to the Canadian Government that the quotas were too high and could be imperilling the stocks. Little was known about the trade in seal products that resulted from the hunts, and in 1978 FPS commissioned Jon Barzdo to make a study of this aspect. This article is a summary of his report, a 30,000-word document with detailed figures, obtainable from the FPS office for £3, including p&p.
Protection in Cuba
Authors: Varona Luis S.
Published: April 2009

Cuba is making a big effort to protect endangered vertebrate species. By Resolution No. 21–79, the Government has forbidden all hunting throughout the year in certain areas that are important for wildlife; outside these areas hunting of the commonest species is permitted from July to February. Time will show whether the law can be enforced.
The Barbary macaque—the future
Authors: Fa J. E.
Published: April 2009

The Barbary macaque Macaca sylvanus has been listed in the IUCN Red Data Book since 1975. This monkey is the only African non-human primate found north of the Sahara and the only member of its genus found outside Asia. It originally ranged throughout most of North Africa but its present and restricted distribution is the result of centuries of human interference and incursions into the once widespread primaeval habitats where it was common. It is now confined to a few pockets in Morocco and Algeria where it is threatened by further habitat destruction as well as hunting.
Ladakh, threatened stronghold of rare Himalayan mammals
Authors: Osborne B.C. , Mallon D.R. , Fraser S.J.R.
Published: April 2009

Ladakh, a remote region of India lying between the Himalayas and Tibet, is ethnically and geographically distinct from the rest of the country. Because of its isolation, change came later to Ladakh than to other parts of the Himalayas, but recent years have seen the familiar pattern of social change, human population increase, tourism and rural development beginning to affect the environment. The authors, jointly and individually, made a series of visits to the area to investigate the status of the wildlife and to look at conservation measures.
Monfragüe: a conservation success in Spain
Authors: Bangs Paul R.
Published: April 2009

In 1978, Bernd-Ulrich and Christiane Meyburg reported in Oryx the efforts to safeguard a very special area of Extremadura in Western Spain. On 4 April 1979, 17,582 hectares was designated as a Parque Natural (a nature park or reserve) by the Government. Perhaps readers of the Meyburgs' article, especially those who responded to its appeal for moral and financial support, would hail this as a great success for conservation in Spain: but there is much more to the story than that …
The manatee in Haiti
Authors: Rathbun Galen B , Woods Charles A , Ottenwalder Jose A
Published: April 2009

The future looks bleak for the manatee population in the waters around Haiti. Results of a survey conducted by the US Fish and Wildlife Service suggest that numbers have declined drastically over the last 50 years. The best hope for the few remaining is that the hunting expertise will vanish with the older generation.
Wildlife research in Madagascar: how foreigners are helping
Authors: Durrell Lee
Published: April 2009

Much of Madagascar's wildlife is threatened and remains poorly known despite a long history of research and conservation, both by the country's governments and by foreign scientists and conservationists. The fast growing human population and fragmentation of the country's forests mean that there is an urgent need for research. Lee Durrell is Chairman of the International Advisory Group of Scientists set up in February 1983 to vet research projects in Madagascar proposed by foreign workers. In December 1984, at a London meeting held jointly by the FFPS and the British Ornithological Union, she presented a paper on recent research by foreigners; the following is an updated extract.
The rarest tortoise on earth
Authors: Curl David
Published: April 2009

The Madagascan tortoise Geochelone yniphora, known locally as the ‘angonoka’, is found only near isolated patches of bamboo forest in the vicinity of Baly Bay in north-western Madagascar. As part of an Oxford University Expedition, and with some help from the Oryx 100% Fund, the author, together with Ian Scoones, Mike Guy and Gilbert Rakotoarisoa, has recently carried out a survey of the area. In this article, he discusses the conservation of this highly endangered animal.
The orang-utan in Sabah
Authors: Davies Glyn
Published: April 2009

A survey of orangutans in Sabah, Borneo, which was carried out by the author and John Payne, resulted in an encouraging picture. In the primary forest of eastern Sabah alone, there are at least 4000 orangutans, but habitat destruction is fragmenting the population. Hunting is also common, especially in the central and western areas where orangutans are already scarce. Some orangutans are protected in conservation areas, but the future of the species outside these places depends on logging being carried out in a more conservation-oriented way. Among other things, we need to discover the size of primary-forest patches that need to be left in logged forest to support a viable population of orang-utans, which will be able to recolonize the logged forest as it regenerates.
The giant river otter in El Tuparro National Park, Colombia
Authors: Defler Thomas R.
Published: April 2009

Giant river otters were once widespread in the rivers and creeks of the greater Amazon Basin. Hunting for their skins caused many local extinctions and only small scattered populations now remain, although total numbers are unknown. It is seriously endangered in Colombia, and one of the places where it still occurs in any numbers, El Tuparro National Park, is becoming increasingly accessible to people, while the otter populations in adjacent rivers outside the park are even more vulnerable to poaching.
The rare deer of Cedros Island, Mexico
Authors: Povilitis Anthony , Ceballos Enrique
Published: April 2009

The mule deer endemic to Cedros Island, off Baja California, was believed to be endangered until a survey in 1980 revealed that around 300 still remained. The authors carried out a follow-up survey in 1985 in order to discover whether the status of the deer had changed and to devise a method for the long-term monitoring of its population.
The decline of elephant and black rhinoceros in Ethiopia
Authors: Largen M. J. , Yalden D. W.
Published: April 2009

From the authors' review of the mammals of Ethiopia, undertaken during the last 14 years, it is clear that Ethiopia's elephants and rhinoceroses have suffered massive declines since the beginning of the century. There are perhaps 9000 elephants left, but poaching for ivory and agricultural encroachment continue to threaten them, and only a few rhinoceroses still survive. Ethiopia has limited resources to protect these remaining animals, and needs help and encouragement from outside its boundaries.
Southern bearded sakis beyond the brink
Authors: Johns A. D. , Ayres J. M.
Published: April 2009

The southern bearded saki is a critically endangered Amazonian primate, occurring only in a small area of north-eastern Brazil. The animal is poorly known, and recent evidence suggests that the species may comprise several critically endangered subspecies. All existing forms are threatened by the continuing economic development of their rain-forest habitat. The fate of this monkey is only an example of the dark future faced by many species as forest clearance spreads through the region.
Threatened Galápagos snails
Authors: Coppois Guy , Wells Sue
Published: April 2009

The endemic snails of the Galápagos are threatened—by introduced fire ants, by black rats and by the destruction of the Scalesia forest that is home to many of them. More than 30 endemic bulimulid snails are now considered endangered there, many of them occurring only in the 10 per cent of the Galápagos that does not have national park status. The problems of protecting them are formidable, and failure would mean the loss not only of individual species, but of a rare opportunity to study speciation in a natural laboratory.
Distribution and exploitation of manatees in Sierra Leone
Authors: Reeves Randall R. , Tuboku-Metzger Daphne , Kapindi Richard A.
Published: April 2009

West African manatees are believed to be declining over much of their range, including in Sierra Leone. They are nominally protected there, but they are traditionally caught and eaten because of their delicious meat and also because they are considered as pests by rice growers and fishermen. The authors' surveys in 1986–1987 showed that manatees are still widely distributed in coastal districts of the country, but that they are being regularly caught in some places, at levels that may not be sustainable. Much more needs to be known to guide appropriate action to ensure that the manatee remains a part of Sierra Leone's wildlife. It is encouraging that one of the authors has begun, under the government Fisheries Division, to implement a manatee research programme.
Semen banking—is it now feasible for captive endangered species?
Authors: Holt W. V. , Moore H. D. M.
Published: April 2009

This article proposes that serious consideration should now be given to the establishment of banks of genetic material from rare and endangered species. In the light of advances in the technology associated with semen assessment and preservation, the limitations that have so far discouraged the practice of semen freezing and banking can now be minimized and circumvented. The authors review these developments and suggest that semen preservation should be reconsidered as a practical means of preserving the genetic diversity currently contained within captive stocks of wild animals.
Status of white-necked picathartes – another reason for the conservation of the Peninsula Forest, Sierra Leone
Authors: Thompson Hazell S. S.
Published: April 2009

A survey of the Western Area Peninsula Forest in Sierra Leone in 1990 located eight breeding sites of the white-necked picathartes–a striking endemic West African forest bird threatened with extinction. Several breeding sites were in areas of fairly intense human activity and in danger of imminent destruction. Subsequent observations revealed successful breeding in 1990 and unsuccessful attempts in 1991. This population is probably only just viable. The discovery of Jentink's duiker–Africa's rarest duiker–in the same forest in 1988 and the presence of three threatened primate species prompted calls for urgent conservation action. The precarious status of the white-necked picathartes population provides another compelling reason for such action.
Pangolins in south-west Nigeria – current status and prognosis
Authors: Sodeinde Olufemi A. , Adedipe Segun R.
Published: April 2009

Despite being officially listed as endangered in Nigeria, pangolins are still hunted in Ogun State, where deforestation has fragmented and reduced their forest habitat. To investigate pangolin status in the state, the authors interviewed hunters, forest workers and market traders selling wild animals or their parts for medicinal use. The authors also counted pangolins stocked by market traders during weekly visits to markets in six towns/villages. Only one of Nigeria's three pangolin species, Manis tricuspis, was encountered frequently. Hunters' reports and evidence of forest destruction suggest that even this species is becoming rare. An estimate of extinction-susceptibility shows that pangolins are at fairly high risk. Creation of sanctuaries for pangolins and other important sympatric vertebrates in forest relicts in south-west Nigeria and the establishment of semicaptive pangolin populations are advocated.
A census of marsh deer in Iberá Natural Reserve, its Argentine stronghold
Authors: Beccaceci Marcelo D.
Published: April 2009

The marsh deer Blastocerus dichotomus is one of the largest mammals in South America. It is classified as vulnerable by IUCN (1990) and is listed on Appendix I to the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Very little field-work has been done to ascertain its status and current distribution and the survey described here is the first attempt to census the marsh deer numbers in the Iberd Natural Reserve, the Argentine stronghold of the species. The survey found only 1100 individuals with a smaller percentage of yearlings than would be expected in a healthy population. Hunting, competition with domestic stock for grazing and transmission of diseases from cattle may be combining to limit population growth and further research is needed to form the basis of a mangement plan for the species.
Butterfly ranching: sustainable use of insects and sustainable benefit to habitats
Authors: New T. R.
Published: April 2009

Butterfly ranching is an important facet of promoting habitat conservation in tropical regions. Recent developments, emphasizing centralized co-ordination of rural cottage industries, are summarized to indicate progress in integration of trade and larger scale species and habitat sustainability.
Saving Europe's dolphins
Authors: Simmonds Mark P.
Published: April 2009

Current evidence suggests that Europe's dolphins in the 1990s require urgent action to conserve them. This paper reviews the nature of the threats to these animals and outlines some measures designed to help counter them.
Tropical forest logging—primates and can they co-exist?
Authors: Johns Andrew D.
Published: April 2009

The destruction of tropical forests is perhaps one of the most widely discussed conservation problems of our time. But still scientists know relatively little about the ecosystem as a whole and, more specifically, little about the effects of, for example, selective logging on other forest species. The author, investigating the response of primates to logging in West Malaysia, discovered that, although logging initially causes mortality, the populations of the species he studied all recovered rapidly if the forest was left to regenerate.
CONTINGENCIES OF PERFORMANCE: THE GAP AS VENUE
Authors: Ọláníyan Tejúmólá
Published: April 2009

Anyone who has staged a show has an idea of the numberless odd things that can go wrong. We expect, of course, that they will go right. From experience and knowledge, we can conceive the contingencies in categories; they range from the personal to the institutional and the natural (as in a force of nature). Contingencies of performance are the many variables that could impact performance in any number of ways, mostly unforeseen, and even if foreseen, mostly unpredictable in effect. Of course, contingency factors are time and space dependent, as what is contingent in one context or time may be completely under control in another context or time. We need to conceive of performance as fundamentally “a changing function of multiple variables,” as Barbara H. Smith once said of value. This changing function is a concept we need to hold tightly as we navigate common challenges of performance: What is our purpose or goal? What should we perform? What are the mechanics of the performance? Where should we perform? When? And for whom? These challenges are theoretically of indeterminate and indeterminable chronological sequence, and beginning from and working diligently through any one of them is bound to lead us into the others.
FROM ADAPTATION TO TRANSFORMATION: SHAKESPEARE CREOLIZED ON CAPE VERDE'S FESTIVAL STAGE
Authors: McMahon Christina S.
Published: April 2009

This is a tale of two directors. The setting is the Republic of Cape Verde, a former Portuguese colony and a tiny archipelago nestled off the coast of Senegal in West Africa. Framing the story is Cape Verde's annual Mindelact International Theatre Festival, which since 1997 has invited Lusophone theatre artists from three continents to perform a wide array of theatre genres on a mainstage program alongside Cape Verdean troupes. João Branco, a Portuguese director who moved to the islands in the early 1990s, is the artistic director of both the Mindelact Festival and the veteran Cape Verdean theatre troupe GTCCPM (Grupo de Teatro do Centro Cultural Português do Mindelo/Theatre Group of the Mindelo Portuguese Cultural Center). For Mindelact 2003, GTCCPM performed an abridged version ofKing Learrendered in Cape Verdean Crioulo, a mix of Portuguese and several West African languages. Beyond bolstering Branco's cherished goal of creolizing Shakespeare's plays by transporting them to Cape Verde's Afro-European cultural milieu,Rei Learworked in concert with the festival's media blitz to extol local spectators in Mindelact's host city, Mindelo, for their good taste. Two years later, Herlandson Duarte, a young Cape Verdean director and Branco's former theatre student, staged a Crioulo-languageMidsummer Night's Dreamat Mindelact with his new theatre company, Solaris. Duarte's production transformed Bottom's play-within-a-play into a searing critique of Mindelense audiences and the structures of authority that prop up the festival itself.
GRAMMAR & GHOSTS: THE PERFORMATIVE LIMITS OF AFRICAN FREEDOM
Authors: Wilderson Frank B.
Published: April 2009

When a group comprised primarily of African-derived “people”—yes, the scare quotes matter—gather at the intersection of performance and subjectivity, the result is often not a renewed commitment to practice or an explicit ensemble of questions, but rather a palpable structure of feeling, a shared sense that violence and captivity are the grammar and ghosts of our every gesture. This structure of feeling is palpable even in the place-names “Africa” and “the Caribbean,” names whose articulation (grammar) and memory (ghosts) would not be names at all were it not for the trade in human cargo. The promise of sense and meaning, when these place-names are spoken, is imbricated in the syntax and morphology of structural violence. Isolation of its performative and episodic instances (the violent event) often robs us of our ability to see it as a grammar of emergence and being: the Maafa, or African Holocaust, as the condition for the emergence of African being, just as grammar conditions the emergence of speech. We know the apparitions: ghosts of lost ancestors whom Ghanaians mourn each year at the sea when they mark the Maafa on their side of the Atlantic; the strange surnames on this side, haunted by the memory of names unknown; that empty space between children and their grandparents where the scourge of AIDS walks in silence; civil wars and famines induced by “natural” disasters like World Bank policies and U.S. intervention—one need not name each and every ghost to remind oneself of their omnipresence.
WHAT ARE YOU READING?
Authors: Canning Charlotte M.
Published: April 2009

All I seem to be able to read about recently is war. Some of that reading is predictable—I read the New York Times and the local paper every day—but lately it has seemed to me that in each book I pick up, no matter what the subject or purpose, passages about war leap out at me. Until I realized this, I made no conscious attempt to select books about war, but over this past spring and into the summer, I have been choosing to read about war.
Enhanced ion acceleration by collisionless electrostatic shock in thin foils irradiated by ultraintense laser pulse
Authors: Liu M.-P. , Xie B.-S. , Huang Y.-S. , Liu J. , Yu M.Y.
Published: April 2009

The formation of collisionless electrostatic shock (CES) and ion acceleration in thin foils irradiated by intense laser pulse is investigated using particle-in-cell simulation. The CES can appear in the expanding plasma behind the foil when self-induced transparency occurs. The transmitting laser pulse can expel target-interior electrons, in addition to the electrons from the front target surface. The additional hot electrons lead to an enhanced and spatially-extended sheath field behind the foil. As the CES propagates in the plasma, it also continuously forward-reflects many of the upstream ions to higher energies. The latter ions are further accelerated by the enhanced sheath field and can overtake and shield the target-normal sheath accelerated ions. The energy gain of the CES accelerated ions can thus be considerably higher than that of the latter.
Theoretical calculation of atomic data for plasma spectroscopy
Authors: Stancalie V.
Published: April 2009

In the present article, a number of theoretical approximations and numerical methods, varying in complexity, are reviewed, in order to facilitate their selection for plasma diagnostic purposes. Results refer to highly charged ions, particularly in the lithium isoelectronic sequence. This article describes progress in understanding the role of laser induced degenerate state phenomenon on resonances obtained by using lasers. This type of process, implicitly included in the R-matrix Floquet calculation, contributes to some degree, to the overall behavior of the resonance profiles. The present article gives comparative results obtained fromab initionon-perturbative treatment and perturbative calculation of autoionization widths in Be-like ions. The effective oscillator strength for complex highly ionized atoms is, also, provided. Such calculations are of interest as they represent accurate benchmark data for beam emission spectroscopy, Zeff analysis, or complex atoms modeling in fusion plasma devices.
Trajectory tracking control in workspace-defined tasks for nonholonomic mobile manipulators
Authors: Mazur Alicja
Published: April 2009

This paper considers a problem of tracking control design for different types of nonholonomic mobile manipulators. The mobile platform is in form of a unicycle. In the first step, an input–output decoupling controller is developed. The proposed selection of output functions is in more general form than the output functions previously introduced by others [Yamamoto and Yun]. It makes possible to move simultaneously, the mobile platform and the manipulator built on it. Regularity conditions that guarantee the existence of the input–output decoupling control law are presented. In the second step, trajectory and path tracking controllers are formulated and presented. Theoretical considerations are illustrated with simulations for the mobile manipulator consisting of a vertical, three degree of freeedom (DOF) pendulum (with holonomic or nonholonomic drives) mounted atop of a unicycle.
Amino acid carryover in the subzonal space of mouse fertilized ova affects subsequent transport kinetics
Authors: Rudraraju Nirmala , Baltz Jay M.
Published: April 2009

We have investigated whether culture in glycine-containing medium affects subsequent glycine transport by the specific transport system, GLYT1, which is the sole glycine transporter in fertilized mouse ova. When fertilized ova were maintained for 6 h in culture with a physiological level of glycine (1 mM), subsequent transport of radiolabelled glycine was decreased by 40% compared with fertilized ova that had been maintained in glycine-free medium. Kinetic measurements showed that the apparent glycine affinity was decreased after culture with glycine (Kmincreased from 0.20 to 0.41 mM), but maximal transport rate was unchanged (similar Vmaxof 20 and 23 fmol/fertilized ovum/min). These findings could have reflected activation of GLYT1 by prolonged substrate starvation, similar to some other amino acid transport systems. However, our findings were instead consistent with the alteration in glycine transport being due to trapping of glycine within the zona pellucida resulting in competitive transport inhibition even after ova were removed from glycine-containing media. First, even very brief exposures to glycine resulted in decreased subsequent glycine transport rates, with a maximal effect apparent within ~6 min. Second, extensive washing (at least six) reversed the effect. Third, the effect was absent when zona-free fertilized ova were used. Thus, it appears that components of the external environment of preimplantation embryos may continue to affect transport kinetics for a period even after embryos are removed from environments that contain them.
Learning human multimodal dialogue strategies
Authors: RIESER V. , LEMON O.
Published: April 2009

We investigate the use of different machine learning methods in combination with feature selection techniques to explore human multimodal dialogue strategies and the use of those strategies for automated dialogue systems. We learn policies from data collected in a Wizard-of-Oz study where different human ‘wizards’ decide whether to ask a clarification request in a multimodal manner or else to use speech alone. We first describe the data collection, the coding scheme and annotated corpus, and the validation of the multimodal annotations. We then show that there is a uniform multimodal dialogue strategy across wizards, which is based on multiple features in the dialogue context. These are generic features, available at runtime, which can be implemented in dialogue systems. Our prediction models (for human wizard behaviour) achieve a weighted f-score of 88.6 per cent (which is a 25.6 per cent improvement over the majority baseline). We interpret and discuss the learned strategy. We conclude that human wizard behaviour is not optimal for automatic dialogue systems, and argue for the use of automatic optimization methods, such as Reinforcement Learning. Throughout the investigation we also discuss the issues arising from using small initial Wizard-of-Oz data sets, and we show that feature engineering is an essential step when learning dialogue strategies from such limited data.
Detection of a quorum sensing signal molecule of Acidovorax avenae subsp. citrulli and its regulation of pathogenicity
Authors: Tao Chen , Guo-Liang Qian , Xiao-Li Yang , Jun-Yi Ma , Bai-Shi Hu , Feng-Quan Liu
Published: April 2009

An efficient AHL (N-acyl-homoserine lactone) bioassay strain, JZA1, of Agrobacterium tumefaciens was used to detect the AHL production from Acidovorax avenae subsp. citrulli [the pathogen causing bacterial fruit blotch (BFB) of melons], and the results showed that A. avenae subsp. citrulli produced a 3-O-C8-homoserine (HSL) type signal molecule. Gene aiiA, which could degrade AHL molecules, was transformed into A. avenae subsp. citrulli strain NJF10, creating strain NJF10-aiiA. The AHL production from NJF10-aiiA was significantly reduced compared with wild-type NJF10. Inoculation tests showed that NJF10-aiiA had an obvious reduction of virulence on watermelon fruits. Our finds showed that AHL production by A. avenae subsp. citrulli was related to its pathogenicity. This work might provide a novel way to control BFB by QS (quorum sensing) interference.
Discharge processes, electric field, and electron energy in ISUAL‐recorded gigantic jets
Authors: Kuo Cheng‐Ling , Chou J. K. , Tsai L. Y. , Chen A. B. , Su H. T. , Hsu R. R. , Cummer S. A. , Frey H. U. , Mende S. B. , Takahashi Y. , Lee L. C.
Published: April 2009

This article reports the first high time resolution measurements of gigantic jets from the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) experiment. The velocity of the upward propagating fully developed jet stage of the gigantic jets was ∼107 m s−1, which is similar to that observed for downward sprite streamers. Analysis of spectral ratios for the fully developed jet emissions gives a reduced E field of 400–655 Td and average electron energy of 8.5–12.3 eV. These values are higher than those in the sprites but are similar to those predicted by streamer models, which implies the existence of streamer tips in fully developed jets. The gigantic jets studied here all contained two distinct photometric peaks. The first peak is from the fully developed jet, which steadily propagates from the cloud top (∼20 km) to the lower ionosphere at ∼90 km. We suggest that the second photometric peak, which occurs ∼1 ms after the first peak, is from a current wave or potential wave–enhanced emissions that originate at an altitude of ∼50 km and extend toward the cloud top. We propose that the fully developed jet serves as an extension of the local ionosphere and produces a lowered ionosphere boundary. As the attachment processes remove the charges, the boundary of the local ionosphere moves up. The current in the channel persists and its contact point with the ionosphere moves upward, which produces the upward surging trailing jets. Imager and photometer data indicate that the lightning activity associated with the gigantic jets likely is in‐cloud, and thus the initiation of the gigantic jets is not directly associated with cloud‐to‐ground discharges.
The 27‐day modulation of the low‐latitude ionosphere during a solar maximum
Authors: Min Kyoung , Park Jaeheung , Kim Heejun , Kim Vitaly , Kil Hyosub , Lee Jaejin , Rentz Stefanie , Lühr Hermann , Paxton Larry
Published: April 2009

The 27‐day solar modulation of the low‐latitude ionosphere is investigated for the solar maximum period using in situ satellite measurement data and the total electron contents (TEC) estimated from the satellite signals of the global positioning system (GPS). Whereas the density and temperature of the topside ionosphere observed at an altitude of 685 km manifest delayed responses to the 27‐day variations in the daily F10.7 values, similar to those previously reported for an altitude of 840 km, the nighttime‐scale height, obtained by comparing the densities observed at altitudes of 685 and 840 km at similar local times, was shown to vary in accordance with the changes in F10.7 with the same time delay. The oxygen ion fraction measured at an altitude of 840 km shows a similar response regardless of the local time. Moreover, the GPS TEC values, most of which come from the F peak region, also exhibit similar delayed modulations in accordance with solar rotation. The TEC value correlates well with the thermospheric neutral density, and both are observed to be modulated with the solar rotation with time delay, especially when a long‐term variation is filtered out. The present result confirms that the whole thermospheric and ionospheric system is modulated with solar rotation.
Thickness of Saturn's ring current determined from north‐south Cassini passes through the current layer
Authors: Kellett S. , Bunce E. J. , Coates A. J. , Cowley S. W. H.
Published: April 2009

We investigate magnetic field and plasma electron data from six Cassini orbits during which, unique within the mission to date, the spacecraft passed almost directly north‐south through Saturn's equatorial plane within the ring current region of the middle magnetosphere. Three passes took place in the postnoon sector and three took place in the postmidnight sector, each at radial distances of ∼9, ∼12, and ∼15 RS. (RS is Saturn's radius, equal to 60,268 km). These data allow for the first time an essentially direct determination of the north‐south field and plasma structure in this region at approximately constant radius and local time. The dayside data indicate the presence of an equatorial current disk with a near constant half‐thickness of ∼1.5 RS. Comparison of the magnetic data with simultaneous electron spectrograms shows that the current layer is located within a significantly broader layer of hot plasma. More variable conditions are found on the nightside. In the inner region a thin equatorial current layer of half‐thickness ∼0.5 RS is found embedded at the center of a much broader layer of current and plasma. In the central and outer passes the current sheet corresponds to essentially the whole of the hot equatorial electron layer, with a half‐thickness of ∼2.5 RS for the central pass, falling strongly to ∼0.4 RS for the outer pass. The data also provide confirmatory evidence of northward displacements of the center of the current layer from Saturn's equatorial plane in the outer regions, on both the dayside and the nightside of the planet.
Motion of polar cap patches: A statistical study with all‐sky airglow imager at Resolute Bay, Canada
Authors: Hosokawa K. , Kashimoto T. , Suzuki S. , Shiokawa K. , Otsuka Y. , Ogawa T.
Published: April 2009

A highly sensitive all‐sky airglow imager (part of the Optical Mesosphere Thermosphere Imagers [OMTIs]) has been operating for 3 years at Resolute Bay, Canada (geographic latitude 74.7°N; geomagnetic latitude 82.9°N) since January 2005. One of its major applications is the observation of polar cap patches. Polar cap patches are generated in the vicinity of the cusp during southward interplanetary magnetic field (IMF) conditions, and they exhibit dynamic movement, possibly in association with the changes in the IMF orientation. In order to determine how their motions are controlled by the upstream IMF conditions, we applied a motion‐tracking algorithm that was based on two‐dimensional cross‐correlation analysis to consecutive images obtained from January 2005 to December 2007 by the all‐sky airglow imager at Resolute Bay. We identified and extracted 561 individual patches and then carried out a statistical study of their motion. It is demonstrated that the speed of patches is primarily controlled by the IMF Bz. Furthermore, the dawn‐dusk component of the patch drift velocities is well correlated with the IMF By, which is in good agreement with the published By dependence of the nightside polar cap convection. This enables us to monitor the plasma convection within the polar cap by using polar cap patches as tracers.
A central California coastal ocean modeling study: 1. Forward model and the influence of realistic versus climatological forcing
Authors: Veneziani M. , Edwards C. A. , Doyle J. D. , Foley D.
Published: April 2009

We report on a numerical simulation of the California Current circulation using the Regional Ocean Modeling System model, focusing on the region of northern and central California during the 5‐year period from 2000 to 2004. Unlike previous model studies of the California Current System, the present configuration is characterized by both realistic external forcing and a spatial domain covering most of the North American West Coast. Specifically, this configuration is driven at the surface by high‐resolution meteorological fields from the Coupled Ocean‐Atmosphere Mesoscale Prediction System and at the lateral open boundaries by output from the project Estimating the Circulation and Climate of the Ocean supported by the Global Ocean Data Assimilation Experiment. The simulation is evaluated favorably through quantitative comparisons with the California Cooperative Fisheries Investigations data set, satellite‐derived sea surface temperature, and surface drifters–derived eddy kinetic energy. The impact of adopting realistic versus climatological surface forcing is demonstrated by comparing mean and mesoscale circulation characteristics. Realistic surface forcing qualitatively alters the seasonal cycle of the mean alongshore jet and better reproduces the summer spatial structure and intensity of the eddy kinetic energy field along the central California coast.
Pathways of inflow and dispersion of warm waters in the Nordic seas
Authors: Rossby T. , Prater M. D. , Søiland H.
Published: April 2009

In this study, we use 22 acoustically tracked RAFOS floats to examine the routes and spreading of warm North Atlantic waters entering the Norwegian Sea between Iceland and the Faroes. The majority of floats crossed the Iceland‐Faroe Ridge at the eastern end where it is deepest. They joined the Iceland‐Faroe Front, but rather than continue north with the outer branch of the Norwegian Atlantic Current into the Nordic seas, most of them jumped over to the inner branch, which continues the inflow through the Faroe‐Shetland Channel northeast over the Vøring Plateau toward the Lofoten Basin. Indeed, 17 floats, whether deployed near Iceland or the Faroes, did so; only 2 floats continued north along the outer branch. Despite the small numbers, these results highlight (1) the strong influence of topography on flow patterns, (2) the strong crossover of Iceland‐Faroes waters to the inner branch, and (3) the rapid and structured spreading into the Nordic seas.
Five years of Arctic sea ice freeboard measurements from the Ice, Cloud and land Elevation Satellite
Authors: Farrell Sinead L. , Laxon Seymour W. , McAdoo David C. , Yi Donghui , Zwally H. J.
Published: April 2009

Using data from the first Earth‐orbiting laser altimeter, the Geoscience Laser Altimeter System (GLAS), onboard the Ice, Cloud and land Elevation Satellite (ICESat), we analyze sea ice freeboard in the Arctic Ocean. We describe a new method for sea surface height retrieval, which relies on an algorithm that discriminates laser pulse reflections originating over leads or thin ice. The lead detection algorithm is based on surface reflectivity and analysis of parameters associated with the shape of reflected waveforms. Using knowledge of the local sea surface height and sea ice elevation, we estimate sea ice freeboard and present, for the first time, a time series of Arctic freeboard spanning 5 years between March 2003 and 2008. While the autumn (October–November) and winter (February–March) data illustrate the seasonal and interannual variations in freeboard, following the September 2007 record minimum sea ice extent, the autumn 2007 and winter 2008 spatially averaged freeboards are below the seasonal means at −4.5 cm and −6.8 cm, respectively. Over the observation period, mean freeboard has declined at a rate of ∼−1.8 cm/a during the autumn period and ∼−1.6 cm/a during the winter period, in the region bounded by the northern limit of ICESat coverage at 86°N. Because of the short 5‐year observation period, it is unclear whether these results represent a long‐term, downward trend in Arctic freeboard or are part of a natural variability. Furthermore, since the variability of snow thickness is included in the ICESat freeboard signal, a decrease in the freeboard cannot wholly be attributed to a decrease in sea ice thickness.
Ocean's response to Hurricane Frances and its implications for drag coefficient parameterization at high wind speeds
Authors: Zedler S. E. , Niiler P. P. , Stammer D. , Terrill E. , Morzel J.
Published: April 2009

The drag coefficient parameterization of wind stress is investigated for tropical storm conditions using model sensitivity studies. The Massachusetts Institute of Technology (MIT) Ocean General Circulation Model was run in a regional setting with realistic stratification and forcing fields representing Hurricane Frances, which in early September 2004 passed east of the Caribbean Leeward Island chain. The model was forced with a NOAA‐HWIND wind speed product after converting it to wind stress using four different drag coefficient parameterizations. Respective model results were tested against in situ measurements of temperature profiles and velocity, available from an array of 22 surface drifters and 12 subsurface floats. Changing the drag coefficient parameterization from one that saturated at a value of 2.3 × 10−3 to a constant drag coefficient of 1.2 × 10−3 reduced the standard deviation difference between the simulated minus the measured sea surface temperature change from 0.8°C to 0.3°C. Additionally, the standard deviation in the difference between simulated minus measured high pass filtered 15‐m current speed reduced from 15 cm/s to 5 cm/s. The maximum difference in sea surface temperature response when two different turbulent mixing parameterizations were implemented was 0.3°C, i.e., only 11% of the maximum change of sea surface temperature caused by the storm.
Structure of the Venus neutral atmosphere as observed by the Radio Science experiment VeRa on Venus Express
Authors: Tellmann Silvia , Pätzold Martin , Häusler Bernd , Bird Michael K. , Tyler G. Leonard
Published: April 2009

The European Space Agency Venus Express Radio Science experiment (VeRa) obtained 118 radio occultation measurements of the Venusian atmosphere between July 2006 and June 2007. Southern latitudes are uniformly sampled; measurements in the northern hemisphere are concentrated near the pole. Radial profiles of neutral number density derived from the occultations cover the altitude range 40–90 km, which are converted to profiles of temperature (T) and pressure (p) versus height (h). Profiles of static stability are found to be latitude‐dependent and nearly adiabatic in the middle cloud region. Below the clouds the stability decreases at high latitudes. At an altitude of 65 km, the VeRa T[p(h)] profiles generally lie between the Venus International Reference Atmosphere (VIRA) and VIRA‐2 models; the retrieved temperatures at any given pressure level typically are within 5 K of those derived from the Pioneer Venus Orbiter Radio Occultation experiments. A large equator‐to‐pole temperature contrast of ∼30 K is found at the 1‐bar (1000 hPa) level. The VeRa observations reveal a distinct cold collar region in the southern hemisphere, complementing that in the north. At the latitudes of the cold collars, the tropopause altitude increases relative to higher and lower latitudes by ≈7 km while the temperature drops roughly 60 K. The observations indicate the existence of a wave number 2 structure poleward of ±75° latitude at altitudes of 62 km.
Reconstruction of sediment supply from mass accumulation rates in the Northern Adriatic Basin (Italy) over the past 19,000 years
Authors: Brommer Marit B. , Weltje Gert Jan , Trincardi Fabio
Published: April 2009

Reconstruction of sediment supply is hampered by the incompleteness of the stratigraphic record. This problem may be partly circumvented by studying mass accumulation rates in closed systems, i.e., basins in which no sediment has bypassed the site of deposition over the time interval of interest. We present time‐averaged basin‐wide mass accumulation rates and their associated uncertainties from a well‐documented closed basin, the Northern Adriatic Basin (Italy), spanning the time interval from 19 ka B.P. to the present. The sediment masses of five basin‐wide lithosomes and their associated uncertainties are derived by means of stochastic simulation, using high‐resolution seismic data, porosity profiles, and radiocarbon datings. This study demonstrates that inferring rates of sediment supply from conformity‐bounded stratigraphic units is feasible, as indicated by the excellent agreement of our results of mass accumulation over the past 400 years with two independently derived estimates. Formation of the stratigraphic record is not an instantaneous process. By comparing spatial patterns of mass accumulation rates on three different timescales (decadal, centennial, and millennial) we demonstrate a low preservation potential of sediments presently accumulating near the coast, and a continuous cross‐shore and alongshore sediment transport regime. The change from transient to persistent accumulation patterns in the highstand systems tract of the Northern Adriatic Basin occurs at the centennial to millennial timescale. Intrabasinal erosion and recycling of sediments obscure the relation between rates of sediment supply and net basin‐wide mass accumulation, which limits the amount of information that can be extracted from the stratigraphic record. Hence, a mismatch between rates of sediment supply and accumulation rates is expected for unconformity‐bounded sequence‐stratigraphic units. Given the uncertainties associated with our estimates, we are unable to reject the hypothesis that net basin‐wide mass accumulation rates have been constant over the time interval of 19,000 years (at a 10% significance level).
Compact monopole‐like slot antenna and band‐notched design for ultrawideband applications
Authors: Qing Xianming , Chen Zhi Ning
Published: April 2009

A compact monopole‐like slot antenna and its extended band‐notched design are presented for ultrawideband (UWB) applications. The proposed antenna is etched on a printed circuit board and fed by a microstrip fork‐shaped feeding stub. The characteristics of the proposed antenna are investigated numerically and validated experimentally. The prototype with an overall size of 25 mm × 25 mm × 0.8 mm achieves good impedance matching, constant gain, stable radiation patterns, and consistent group delay over an operating bandwidth of 3.0–12.9 GHz (124.5%). In addition, the proposed antenna features less ground plane dependence. By adding two grounded open‐circuited stubs, the proposed antenna features band‐notched characteristics at 5–6 GHz while it maintains the desirable performance over lower/upper UWB bands of 3.1–4.8 GHz/6.2–9.7 GHz.