bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology‐Driven Alternatives for Smart Sensor Interfaces
Authors: Baschirotto A. , Malcovati P.
Published: February 2004

The importance of integrated microsystems is continuously growing because of the combination of two trends: the progress of silicon sensor technology and the introduction of new techniques for interface circuits. In this chapter we show how different approaches to the implementation of smart sensor systems, basically driven by the available fabrication technologies, can lead to successful designs. Three examples are presented: a fully integrated current monitor, a biaxial accelerometer, and a rotational accelerometer. The current monitor is an example of single chip implementation. It supports two different operating ranges (20 A and 200 A full scale), provides digitally programmable gain and offset with an on‐chip PROM, and achieves 9 bits of resolution and ± 0.6 LSB of linearity. The biaxial accelerometer and the rotational accelerometer are examples of implementations based on two chips in the same package. They achieve 80 dB of dynamic range with ± 1 g full‐scale signal over a 30 Hz bandwidth and 38 dB of dynamic range with 200 rad/s2full‐scale signal over an 800 Hz bandwidth.
Microelectronic Chips for Molecular and Cell Biology
Authors: Tartagni Marco , Altomare Luigi , Guerrieri Roberto , Fuchs Alexandra , Manaresi Nicolò , Medoro Gianni , Thewes Roland
Published: February 2004

The development of microfabricated devices manufactured in silicon, glass, or plastic materials is a well‐known trend in the research of novel biological techniques and tools over the last two decades, resulting in a multitude of start‐up companies serving the pharmaceutical, biotechnology, and diagnostics markets. However, the idea of implementing such devices on microelectronic substrates has been introduced only recently. This chapter aims to describe the state‐of‐the‐art of microsystems for molecular and cell biology produced in general purpose CMOS (complementary metal oxide semiconductor) technology, emphasizing the advantages of this approach along with their challenges and limitations. This chapter discusses significant examples of fully tested devices in comparison with existing state‐of‐the‐art techniques.
Sensors for Catheter Applications
Authors: French P. J. , Tanase D. , Goosen J. F. L.
Published: February 2004

Minimally invasive techniques enable diagnostics and surgery to be performed through a small incision. This greatly reduces the damage to healthy tissue leading to faster recovery times for the patient. However, the surgeon is deprived of the sensory feedback available with normal surgical techniques. Miniaturised sensors can provide this information about location, diagnostics and the treatment. This application severely limits the size of the device, with some catheters being less than 1 mm in diameter. Catheters are usually defined in multiples of 1/3 mm or 1 french. Further important issues are bio‐compatibility, safety and the ability of the sensor to withstand the working environment. Sensors able to meet these demands are improving the efficiency of operations and are opening new opportunities for minimally invasive techniques.
Microvalve for Fuel Cells and Miniature Gas Chromatographic System
Authors: Hesketh P. J. , Bintoro J. S. , Luharuka R.
Published: February 2004

Microvalves are important for fluid control in a variety of applications, ranging from miniaturized chemical analysis systems, to precision manufacturing and miniature fuel cells. MEMS technology provides the opportunity to miniaturize valves that work with smaller sample volume, operate rapidly with low power and can potentially be integrated with other components on a single chip. A review of actuators for microvalves is provided, including electrostatic, magnetic, piezoelectric, thermal, shape memory alloy and hydrogel. The design and simulation of a magnetic latching microvalve is provided as a case study. The fabrication by surface micromachining with low temperature, potentially CMOS compatible processing is given.
A more Efficient Starch Degradation by the Combination of Hydrolase and Transferase Activities of α‐Amylase and Cyclomaltodextrin Glucanotransferase
Authors: Moreno Alina , Saab‐Rincón Gloria , Santamaría Rosa Isela , Soberón Xavier , López‐Munguía Agustín
Published: February 2004

α‐Amylases catalyze the hydrolysis of internal α‐(1→4) linkages of glucose polymers as their main reaction; however, some α‐amylases catalyze transfer reactions in addition to hydrolysis. It has been observed that those α‐amylases capable of transferring glycoside residues are also those that generate low molecular weight products from their action on starch (i.e. saccharifying α‐amylases). In this paper the product profiles of a liquefying α‐amylase, a cyclomaltodextrin glucanotransferase and both enzymes acting together on starch and maltodextrins are compared. The increase in glucose and maltose concentration, when both enzymes act together, is due to the combined action of the transfer and hydrolytic activity of CGTase and the liquefying α‐amylase, respectively.
In vitro Digestibility of Raw Starches Extracted from five Yam (Dioscorea spp.) Species Grown in Jamaica
Authors: Riley Cliff K. , Wheatley Andrew O. , Hassan Ishmael , Ahmad Mohammed H. , Morrison Errol Y. St. A. , Asemota Helen N.
Published: February 2004

Starch granules from Round leaf yellow yam, Negro yam, Sweet yam, Bitter yam and Chinese yam grown in Jamaica were isolated and characterized. The amylose content, granular size, crystallinity, and digestibility by α‐amylase were determined. The granules obtained were of three crystalline types. Round leaf yellow yam, Negro yam and Sweet yam were found to be type‐B, while Chinese yam and Bitter yam were type‐C and type‐A, respectively. Round leaf yellow yam had the highest amylose content (26.5%) while Chinese yam had the lowest (11.1%). The granule size varied between 1–3 μm for Chinese yam and 16–42 μm for Round leaf yellow yam. Significant variations in digestibility of the granules were observed. Raw starches from Chinese yam and Bitter yam were the most susceptible to α‐amylase digestion (porcine pancreatic α‐amylase, pH 5.5, 0.02% CaCl2, 40°C, 24 h) with 21.27 ± 0.01% and 18.11 ± 0.02% degradation, respectively, while Round leaf yellow yam, Negro yam and Sweet yam starches were the least susceptible, with 13.74 ± 0.03%, 14.98 ± 0.08%, and 15.32 ± 0.04% enzymatic degradation, respectively.
Feasibility Study for Determination of the Dextrose Equivalent (DE) of Starch Hydrolysis Products with Near‐Infrared Spectroscopy (NIRS)
Authors: Storz Elizabeth , Steffens Klaus‐Jürgen
Published: February 2004

Starch hydrolysis products such as maltodextrin and glucose syrup have many applications in the pharmaceutical and food industry. Several physical and functional properties, for example sweetness, compressibility and viscosity vary according to the extent of starch hydrolysis which is characterized by the dextrose equivalent (DE) value. The Pharmacopoeias use the titrimetric Lane Eynon method with alkaline Fehling's solution for determination of DE. In order to replace this empirical method, near‐infrared (NIR) calibration models for the reagent‐free determination of DE were developed. The maltodextrin model with a DE of less than 20 showed very good correlation with r = 0.97. The correlation of the extended model of maltodextrin and spray‐dried glucose syrup with a DE up to 44 was calculated to be r = 0.99. The NIR method is a very effective, rapid and non‐destructive alternative to the current pharmacopoeial procedure.
Synthesis of Starch Copolymers by Silicon Tetrachloride Plasma‐Induced Graft Polymerization
Authors: Ma Yonghui C. , Manolache Sorin , Sarmadi Majid , Denes Ferencz S.
Published: February 2004

Corn starch was surface‐functionalized by 13.56 MHz RF SiCl4‐plasma, in situ reacted with ethylenediamine for stabilization, and subsequently graft‐polymerized using dichlorodimethylsilane as monomer. SiCl4‐plasma treatment was studied and discharge parameters were optimized. X‐ray photoelectron spectroscopy (XPS/ESCA), Fourier transformed infrared spectroscopy (FTIR), scanning electron spectroscopy (SEM), gas chromatography/mass spectroscopy (GC‐MS), and differential thermal analysis/thermal gravimetry (DTA/TG) proved the presence of a polydimethylsiloxane (PDMS) graft‐copolymer layer on the modified starch‐granule surfaces. These analyses show that the surface morphology of starch granules, the thermal properties, the swelling characteristic, and the hydrophilicity of starch were all changed due to the existence of a protective hydrophobic PDMS layer. It is suggested that the starch graft‐copolymer might find its applications as reinforcing component in silicone‐rubber materials for starch‐based composites.
Effective test case selection for component customization and its application to Enterprise JavaBeans
Authors: Yoon Hoijin , Choi Byoungju
Published: February 2004

Component users need to customize components they obtain from providers, because providers usually develop components for general use. Although the customization is accomplished by modifying the interface of a component, faults from customization appear when the implementation part of a component and the interfaces interact. The implementation part is a black‐box, whose source code is not available to a component user, while the interface is a white‐box, whose source code is available for customization. Therefore, customization faults should be tested using both the black‐box part and the white‐box part of a component.

This paper proposes a new technique to test customization faults using software fault injection and mutation testing, and the technique is tailored to Enterprise JavaBeans. Test cases are selected by injecting faults not into the entire interface but into specific parts of the component's interface. The specific parts that are chosen control the effectiveness of the test cases. An empirical study to evaluate the technique is reported. Copyright © 2003 John Wiley & Sons, Ltd.
An AGENDA for testing relational database applications
Authors: Chays David , Deng Yuetang , Frankl Phyllis G. , Dan Saikat , Vokolos Filippos I. , Weyuker Elaine J.
Published: February 2004

Database systems play an important role in nearly every modern organization, yet relatively little research effort has focused on how to test them. This paper discusses issues arising in testing database systems, presents an approach to testing database applications, and describes AGENDA, a set of tools to facilitate the use of this approach. In testing such applications, the state of the database before and after the user's operation plays an important role, along with the user's input and the system output. A framework for testing database applications is introduced. A complete tool set, based on this framework, has been prototyped. The components of this system are a parsing tool that gathers relevant information from the database schema and application, a tool that populates the database with meaningful data that satisfy database constraints, a tool that generates test cases for the application, a tool that checks the resulting database state after operations are performed by a database application, and a tool that assists the tester in checking the database application's output. The design and implementation of each component of the system are discussed. The prototype described here is limited to applications consisting of a single SQL query. Copyright © 2004 John Wiley & Sons, Ltd.
Exploring risk‐based testing and its implications
Authors: Redmill Felix
Published: February 2004

If software cannot be tested exhaustively, it must be tested selectively. But, on what should selection be based in order to maximize test effectiveness? It seems sensible to concentrate on the parts of the software where the risks are greatest, but what risks should be sought and how can they be identified and analysed? ‘Risk‐based testing’ is a term in current use, for example in an accredited test‐practitioner's course syllabus, but there is no broadly accepted definition of the phrase and no literature or body of knowledge to underpin the subject implied by it. Moreover, there has so far been no suggestion that it requires an understanding of the subject of risk. This paper examines what is implied by risk‐based testing, shows that its practice requires an understanding of risk, and points to the need for research into the topic and the development of a body of knowledge to underpin it. Copyright © 2004 John Wiley & Sons, Ltd.
Vitamin D content in Alaskan Arctic zooplankton, fishes, and marine mammals
Authors: Kenny David E. , O'Hara Todd M. , Chen Tai C. , Lu Zhiren , Tian Xiao , Holick Michael F.
Published: February 2004

We postulated that dietary ingestion of vitamin D may be used by some Alaskan Arctic marine mammal species in addition to, or instead of, cutaneous production to meet nutritional requirements. Zooplankton (n=5) sampled near Kaktovik, Alaska, contained no measurable vitamin D2 or D3, but did contain provitamin D (7‐dehydrocholesterol), the cutaneous precursor for previtamin D3 in mammals. Fillets and livers from five fish species were sampled near Barrow, Alaska, and evaluated for vitamin D3 content (no vitamin D2 was detected). Differences in vitamin D3 content appeared significant (P≤0.10) among fish livers (Kruskal‐Wallis [H test]=8.25, df=4, P=0.08) and among fish fillets (H=7.80, df=4, P=0.01). We also found significant differences in several pairwise comparisons (Mann‐Whitney U‐test) of vitamin D3 levels in fillets and livers. Blubber from six species of marine mammals had no detectable vitamin D2. The H test results for blubber vitamin D3 concentration were highly significant: 28.12, df=5, P<0.001. There were also significant differences in vitamin D3 content from blubber in pairwise comparisons of primarily invertebrate feeders (bowhead whale (Balaena mysticetus) [mean=4.20 SD±1.10 ng/g], and Pacific walrus (Odobenus rosmarus divergens) [5.43±2.82 ng/g]) vs. primarily piscivorous feeders (ringed seal (Phoca hispida) [746.57±493.00 ng/g] and beluga whale (Delphinapterus leucas) [426.00±174.92 ng/g]) and a semiaquatic terrestrial carnivore (polar bear (Ursus maritimus) [406.17±311.70 ng/g]). The bearded seal (Erignathus barbatus) had intermediate blubber vitamin D3 concentration (156.83±139.25 ng/g), which may reflect an intermediate‐type feeding strategy or an artifact of the small sample size. Zoo Biol 23:33–43, 2004. © 2004 Wiley‐Liss, Inc.
Successful artificial insemination of an Asian elephant at the National Zoological Park
Authors: Brown Janine L. , Göritz Frank , Pratt‐Hawkes Nancy , Hermes Robert , Galloway Marie , Graham Laura H. , Gray Charlie , Walker Susan L. , Gomez Andres , Moreland Rachel , Murray Suzan , Schmitt Dennis L. , Howard JoGayle , Lehnhardt John , Beck Benjamin , Bellem Astrid , Montali Richard , Hildebrandt Thomas B.
Published: February 2004

For decades, attempts to breed elephants using artificial insemination (AI) have failed despite considerable efforts and the use of various approaches. However, recent advances in equipment technology and endocrine‐monitoring techniques have resulted in 12 elephants conceiving by AI within a 4‐year period (1998–2002). The successful AI technique employs a unique endoscope‐guided catheter and transrectal ultrasound to deliver semen into the anterior vagina or cervix, and uses the “double LH surge” (i.e., identifying the anovulatory LH (anLH) surge that predictably occurs 3 weeks before the ovulatory LH (ovLH) surge to time insemination. This study describes the 6‐year collaboration between the National Zoological Park (NZP) and the Institute for Zoo Biology and Wildlife Research (IZW), Berlin, Germany, that led to the refinement of this AI technique and subsequent production of an Asian elephant calf. The NZP female was the first elephant to be inseminated using the new AI approach, and was the fifth to conceive. A total of six AI trials were conducted beginning in 1995, and conception occurred in 2000. Semen was collected by manual rectal stimulation from several bulls in North America. Sperm quality among the bulls was variable and was thus a limiting factor for AI. For the successful AI, semen quality was good to excellent (75–90% motile sperm), and sperm was deposited into the anterior vagina on the day before and the day of the ovLH surge. Based on transrectal ultrasound, ovulation occurred the day after the ovLH surge. Pregnancy was monitored by serum and urinary progestagen, and serum prolactin analyses in samples collected weekly. Fetal development was assessed at 12, 20, and 28 weeks of gestation using transrectal ultrasound. Elevated testosterone measured in the maternal circulation after 36 weeks of gestation reliably predicted the calf was a male. Parturition was induced by administration of 40 IU oxytocin 3 days after serum progestagens dropped to undetectable baseline levels. We conclude that AI has potential as a supplement to natural breeding, and will be invaluable for improving the genetic management of elephants, provided that problems associated with inadequate numbers of trained personnel and semen donors are resolved. Zoo Biol 23:45–63, 2004. © 2004 Wiley‐Liss, Inc.
Evaluation of behavioral factors influencing reproductive success and failure in captive giant pandas
Authors: Zhang Guiquan , Swaisgood Ronald R. , Zhang Hemin
Published: February 2004

The giant panda (Ailuropoda melanoleuca) breeding center in Wolong, China, has experienced a recent dramatic increase in reproduction, with the population nearly tripling in the past 7 years. Much of this success comes from the development of behavioral management strategies, guided by the application of scientific knowledge. Here we present statistics that illuminate where reproductive problems have occurred, and discuss remedial actions taken with individual animals. During each year of this study (1996–2000), 93% of the females experienced estrus, 72% copulated, and 51% gave birth. Two‐thirds of the males mated each year. Most instances of mating failure were attributed to male behavior. In nearly half of mating failures, the male mounted but did not copulate. In about one‐third of mating failures, the male lacked sexual motivation, and showed excessive aggression 20% of the time. The males varied, and some were more likely to show interest in estrous females in neighboring enclosures and/or mate successfully during introductions. Copulation time was unrelated to reproductive success, but more insemination events (matings and artificial inseminations (AIs) combined) may be related to twinning. We suspect that temperament, stress, and husbandry practices play a role in isolated cases of reproductive failure in females, both pre‐ and postcopulation. Pregnancy or conception failure occurred in 35% of females inseminated naturally or through artificial insemination (AI). Behavioral management at Wolong is holistic and emphasizes biological relevance, including enrichment and well‐being, intensive monitoring of signs of estrus, and male–female familiarization and olfactory communication during the mating season. Zoo Biol 23:15–31, 2004. © 2004 Wiley‐Liss, Inc.
Trends in the captive breeding of threatened and endangered birds in British zoos, 1988–1997
Authors: Whitfort Harriet L. , Young Robert J.
Published: February 2004

The aim of this study was to assess trends in captive breeding of threatened and endangered bird species in British zoos. The measures we recorded were: 1) the total number of species held, 2) the percentage of species held that are listed in the IUCN Red List, 3) the percentage of endangered species breeding, and 4) the number of species in managed breeding programs. These data were gathered from the bird inventories of 10 representative British zoos for the years 1988 and 1997. The data for measures 1–3 were compared between the 2 years using a Wilcoxon matched‐pairs test. We found that the zoos maintained the same number of species (W=10.5; n=10; P=0.093; median=87.5 and 78 for 1988 and 1997, respectively). However, there was a significant increase in the number of birds held that fit each of the IUCN's conservation categories (Endangered: W=43.0; n=10; P<0.05, median=1.48 and 6.64 for 1988 and 1997, respectively; Vulnerable: W=53.0; n=10; P<0.05, median=3.33 and 10.05 for 1988 and 1997, respectively; and Rare: W=55.0; n=10; P<0.01, median=0.00 and 8.33 for 1988 and 1997, respectively). Overall, the percentage of threatened species kept in zoos increased from a median of 4.81 in 1988 to 25.02 in 1997. During this period there was an increase in the number of species in each category of the IUCN Red List. No difference was found in the number of threatened species breeding between 1988 and 1997. Zoo Biol 23:85–89, 2004. © 2004 Wiley‐Liss, Inc.
Iodine deficiency affects hatchability of endangered captive kaki (Black Stilt, Himantopus novaezelandiae)
Authors: Sancha Emily , Heezik Yolanda van , Maloney Richard , Alley Maurice , Seddon Philip
Published: February 2004

A significant increase in hatching and late‐incubation deaths during two breeding seasons in a captive population of endangered black stilts (kaki, Himantopus novaezelandiae) prompted an investigation into the potential role of iodine deficiency. During the 1997 and 1998 breeding seasons, the survival rate of captive‐laid eggs during artificial incubation and hatching was lower than that of eggs laid by wild kaki, which were collected and incubated artificially in the same environment. Necropsy results revealed abnormalities in thyroid structure. These abnormalities had been occurring in captive birds since 1994, but they peaked in 1997 and 1998 at 30% and 81%, respectively, of all diagnosed necropsies. Necropsies of pied stilts, hybrids, and one kaki from the wild revealed no thyroid abnormalities. Gross morphological symptoms observed at hatching in chicks that died were consistent with those described for iodine deficiency in poultry. Serum levels of thyroxine (T4) were considerably higher in wild pied stilts and hybrid chicks than in captive adult, subadult, and kaki chicks. In five individuals from the captive population, serum levels increased after about 160 days of iodine supplementation and approached values in the wild. The constraints associated with working with such a critically endangered species (e.g., small sample size and an urgent need to effect changes) precluded the use of an experimental approach to determine the role iodine deficiency played in peri‐hatching deaths. However, we believe the evidence presented here strongly supports a case for the impact of iodine on survival within the captive population. Our experience also highlights the need for vigilance in captive programs with respect to potential dietary deficiencies when endangered species are raised in captivity for conservation purposes. Zoo Biol 23:1–13, 2004. © 2004 Wiley‐Liss, Inc.
Enzyme‐linked immunosorbent assay to quantitate serum ferritin in the northern fur seal (Callorhinus ursinus)
Authors: Andrews Gordon A. , Chavey Patricia Sue , Mazzaro Lisa M. , Dunn J. Lawrence , Aubin David J. St.
Published: February 2004

Serum ferritin concentration correlates with tissue iron stores in humans, horses, calves, dogs, cats, and pigs. Serum ferritin is considered the best serum analyte to predict total body iron stores in these species, and is more reliable than serum iron or total iron‐binding capacity, both of which may be affected by disorders unrelated to iron adequacy or excess (including hypoproteinemia, chronic infection, hemolytic anemia, hypothyroidism, renal disease, and drug administration). Iron overload has been documented to result in hemochromatosis in captive northern fur seals (Callorhinus ursinus); therefore, we developed an enzyme‐linked immunosorbent assay (ELISA) to measure serum ferritin in this species. The assay uses two murine anti‐canine ferritin monoclonal antibodies in a sandwich arrangement that was originally used in an ELISA to measure serum ferritin in dogs. Ferritin isolated from fur seal liver was used as a standard. Ferritin standards were linear from 0 to 50 ng/ml. Recovery of purified ferritin from fur seal serum varied from 89% to 99%. The within‐assay variability was 6%, and the assay‐to‐assay variability for two different samples was 10% and 16%. Zoo Biol 23:79‐84, 2004.© 2004 Wiley‐Liss, Inc.
Development of an enzyme‐linked immunosorbent assay (ELISA) for Luteinizing Hormone (LH) in the elephant (Loxodonta africana and Elephas maximus)
Authors: Dahl Nancy J. , Olson Deborah , Schmitt Dennis L. , Blasko David R. , Kristipati RamaSharma , Roser Janet F.
Published: February 2004

A simple, rapid enzyme‐linked immunosorbent assay (ELISA) for the measurement of LH in plasma and serum of elephants (Loxodonta africana and Elephas maximus) has been developed, validated, and used for comparative studies. Purified elephant LH (eleLH) diluted in elephant plasma was used as standards (0.78–50 ng/ml). A monoclonal antibody against the β‐subunit of bovine LH (518B7) was used as the capture antibody. The second antibody (a polyclonal rabbit anti‐human LH antibody), conjugated to horseradish peroxidase, cleaved a substrate (tetramethyl benzidine), resulting in a color change. The total assay time was approximately 2½ hr, with incubations at room temperature. Sensitivity was found to be 1.56 ng/ml. Cross‐reactivities to elephant FSH and TSH were low: 0.9% and 0.15%, respectively. The accuracy of the assay was demonstrated by comparing the ELISA with a validated eleLH radioimmunoassay (RIA), progesterone data, and ultrasound observations. Blood samples from 18 Asian and African elephant cows were analyzed with the ELISA and RIA, and an additional 11 cows were used to describe endocrine parameters for LH and progesterone using only RIA. No difference was found in LH peak concentrations between the ELISA and RIA. The time from the progesterone decline to the first LH peak, and the time between the two peaks were similar between species. Asian cows had higher LH peaks than African cows. Ultrasound confirmed the time of ovulation occurring with the second LH peak. Three cows were inseminated and confirmed to be pregnant using this ELISA as a timing device. Instrumentation is not always required, as LH peaks approximating 3 ng/ml can be visually observed. In conclusion, this ELISA can be used as a field test to determine time of ovulation for artificial insemination (AI) or natural breeding of both species of elephants, and thus is an important tool for the preservation of captive populations worldwide. Zoo Biol 23:65–78, 2004. © 2004 Wiley‐Liss, Inc.
Analysis of the fluctuations of the total electron content (TEC) measured at Goose Bay using tools of nonlinear methods
Authors: Kumar K. Satheesh , Kumar C. V. A. , George Benny , Renuka G. , Venugopal C.
Published: February 2004

In this paper we report the evidence of a low‐dimensional chaos in a set of data observed outside laboratories. The dynamic behavior of the time series of the fluctuations of the total electron content (TEC) measured at Goose Bay, which is a high‐latitude station, is analyzed in detail using the tools of nonlinear dynamics. The low‐dimensional character of the dynamics is evident from the estimated value of the fraction of false neighbors for various dimensions and the correlation dimension. The deterministic nature of the dynamics is investigated using recurrence plots and spatiotemporal entropy. The chaotic nature of the underlying dynamics of the fluctuations of TEC is shown by the power spectrum indicating exponential decay and the calculated positive value of Lyapunov exponent. This is also supported by the results of the comparison of the chaotic characteristics of the time series of variations of TEC with the pseudochaotic characteristic of the colored noise time series. The results of the tests based on the prediction error and the time reversal asymmetry statistic reject the hypothesis that TEC belongs to the family of linear stochastic signals. The nonlinear non‐Gaussian nature of the oscillations of variations of TEC is further investigated by the surrogate data test based on several geometrical and dynamical characteristics of the variations of TEC such as mutual information, the fraction of the false nearest neighbours, the local slopes of the correlation sums, the curves giving Lyapunov exponents, and finally, the value of Lyapunov exponents. The results of this analysis show that low‐dimensional chaotic dynamics could be a possible and fruitful concept which can be utilized to study the disturbance in the ionosphere as in the case of magnetospheric dynamics. We feel that the dynamical invariants like Lyapunov exponents and correlation dimension can describe the disturbance in the variations of TEC and thus the disturbance in the ionosphere. Hence the techniques of nonlinear and chaos theory and the measure of the dynamical invariants could be used for the characterization and thus for the modeling of variations of the total electron content.
Effects of ionospheric scintillation on Transit satellite measurement of total electron content
Authors: Knepp D. L.
Published: February 2004

Ionospheric scintillation can affect not only satellite communications but also satellite measurements of the ionosphere, such as the measurements of total electron content (TEC) made using Transit‐like signal transmissions. In this work a numerical phase‐screen propagation simulation is applied to study the accuracy of the measurement of TEC made with Transit‐like signals. To measure TEC, the phase from coherently related 150 and 400 MHz tones is combined to obtain an estimate of the phase imparted to a propagating signal by transmission through the ionosphere. This phase is processed to remove ambiguities of 2π and converted to a relative value of TEC. However, scattering caused by ionospheric irregularities produces amplitude fading and phase variations that degrade the TEC measurement in several ways. Rapid phase variations that may be associated with deep fades can degrade the phase‐ambiguity removal process. Fresnel filtering causes scintillation when intrinsic ionospheric variations are of the size of the Fresnel zone and smaller. Receiver noise also acts to degrade the phase measurements and is especially important during the deepest fades. This paper considers the effects of all these processes and develops rule‐of‐thumb qualifiers to assure the accuracy of Transit‐like measurements of TEC.
High‐latitude plasma structure and scintillation
Authors: Coker Clayton , Bust Gary S. , Doe Richard A. , Gaussiran Thomas L.
Published: February 2004

Observations of high‐latitude plasma structure and scintillation are presented from the January 2001 scintillation campaign timeframe. Comparisons are made using the all‐sky imager and two beacon‐satellite ground receivers located at Sondrestrom, Greenland. The Coherent Ionospheric Doppler Receiver (CIDR) observes 150‐ and 400‐MHz signals transmitted from low‐Earth‐orbiting satellites. The 250‐MHz polar beacon‐satellite system observes signals from highly elliptical orbiting satellites. F region patches, F region precipitation arcs, and auroral arcs were observed. Intermediate‐scale structure was observed on the leading and trailing edges of patches prior to exiting the polar cap. Banded structure was observed across an F region arc. Additional beacon‐satellite receivers in Greenland and Alaska provide a unique opportunity to study the spatial distribution and temporal evolution of patch structures and their associated scintillation.
Analysis of differential GPS performance for marine users during solar maximum
Authors: Skone S. , El‐Gizawy M. , Shrestha S. M.
Published: February 2004

GPS signals are refracted by the dispersive ionosphere, resulting in ranging errors dependent on both the given signal frequency and ionospheric total electron content. Such range errors translate into a degradation of positioning accuracies. While it is possible to mitigate the impact of ionospheric effects on GPS positioning applications through ionosphere modeling and/or differential techniques (DGPS), residual errors may persist in regions where steep gradients or localized irregularities in electron density exist, particularly during periods of high geomagnetic activity. Such effects are an issue for the reliable implementation of safety‐critical GPS systems. A solar maximum was observed in mid 2000 with associated degradations in GPS positioning accuracies. In this paper the impact of solar maximum on DGPS horizontal positioning applications is investigated. Analyses focus on determining limitations in horizontal positioning accuracies for operational marine DGPS systems. Long‐term analyses are conducted using data from permanent GPS reference networks in Canada, Brazil, and the United States. Several million observations are processed in this study during the years 1998–2000. Studies focus on large ionospheric gradients near the equatorial anomaly and at subauroral latitudes (associated with the main trough and storm‐enhanced densities). Results indicate that DGPS horizontal positioning accuracies are degraded by a factor of 2–5 relative to average values.
Modeling the effect of ozone loss on photobleaching of chromophoric dissolved organic matter in the St. Lawrence estuary
Authors: Whitehead Robert F. , de Mora Stephen J.
Published: February 2004

Temporal trends in total ozone for the St. Lawrence estuary were estimated from ground‐based measurements at the NOAA/CMDL station in Caribou, Maine. Linear regression analysis showed that from 1979 to 1999 total ozone has decreased by about 3.3% per decade on an annual basis and ≤6.2% per decade on a monthly basis relative to unperturbed (pre‐CFC) levels. The influence of increased ultraviolet‐B (280–320 nm) radiation associated with ozone depletion on water column photochemical processes was evaluated by modeling the photobleaching of chromophoric dissolved organic material (CDOM). Linear regression analysis showed small (<0.5% per decade), but statistically significant upward trends in maximum noontime photobleaching rates. Most notably, positive trends in relative rates for May, June, and July, when maximum absolute rates are expected, were predicted. A global model based on TOMS ozone data revealed increases in photobleaching of ≤3% per decade at high latitudes in the Southern Hemisphere. Radiation amplification factors for increases in photochemically weighted UV (280–400 nm) in response to ozone depletion were estimated at 0.1 and 0.08 for photobleaching of CDOM absorbance at 300 and 350 nm, respectively. Application of the laboratory‐based model to conditions that more closely resembled those in situ were variable with both overestimation and underestimation of measured rates. The differences between modeled rates and observed rates under quasi‐natural conditions were as large or larger than the predicted increases due to ozone depletion. These comparisons suggest that biological activity and mixing play an important, but as yet ill‐defined, role in modifying photochemical processes.
The link between a detached subauroral proton arc and a plasmaspheric plume
Authors: Spasojević M. , Frey H. U. , Thomsen M. F. , Fuselier S. A. , Gary S. P. , Sandel B. R. , Inan U. S.
Published: February 2004

Observations of detached subauroral proton arcs by the FUV instrument on the IMAGE spacecraft have been recently reported and shown to be produced by ring current ions precipitating in the afternoon local time sector during geomagnetically disturbed periods. Data from June 18, 2001 show a direct link between a subauroral proton arc and a global observation of a plasmaspheric plume by the IMAGE EUV instrument. Using a T96 magnetic field model, the proton arc maps to a broad region of enhanced cold plasma density associated with the plume. The link between the proton arc and plume suggests that the precipitation may be due to pitch angle scattering of energetic protons by electromagnetic ion cyclotron (EMIC) waves, which may be preferentially generated within the plume since the presence of cold, dense ions lowers the threshold for the EMIC instability.
Phenomenological evidence in favor of a remote seismic coupling for large volcanic eruptions
Authors: Marzocchi Warner , Zaccarelli Lucia , Boschi Enzo
Published: February 2004

A correlation has been recently found between large earthquakes and the succeeding largest 9 explosive eruptions of the last century, which has been interpreted as a product of co‐ and post‐seismic stress diffusion. Here, we check the statistical significance of the proposed coupling by using a larger dataset, and investigate the reliability of the causality hypothesis. We find that the volcanoes with VEI ≥ 4 eruptions underwent, in the few decades before the volcanic event, higher seismic stress perturbations due to large earthquakes compared to other volcanic areas. The correlation is statistically significant and it is not explained by a spatio‐temporal clustering of eruptions and earthquakes due to tectonic pulses. This implies that the large earthquakes indeed triggered the eruptions.
Gravity and magma induced spreading of Mount Etna volcano revealed by satellite radar interferometry
Authors: Lundgren P. , Casu F. , Manzo M. , Pepe A. , Berardino P. , Sansosti E. , Lanari R.
Published: February 2004

Mount Etna underwent a cycle of eruptive activity over the past ten years. Here we compute ground displacement maps and deformation time series from more than 400 radar interferograms to reveal Mount Etna's average and time varying surface deformation from 1992 to 2001. We find that during this time interval it experienced magmatic inflation and radial spreading to the West, South, and East. Steady relative motion between the West and South flanks, and between the East and North flanks, during this time interval, suggests they are related to gravitational spreading of the volcanic edifice. Time series analysis shows that growth of a southeastern basal anticline began with the end of magma recharge in 1995, thus showing a direct link between deep‐seated magma intrusions and edifice spreading. These observations support a complex mode of radial gravitational collapse underlain by deeper magma driven basal spreading, although ultimately the two must be related.
Deep structures of the Ecuador convergent margin and the Carnegie Ridge, possible consequence on great earthquakes recurrence interval
Authors: Graindorge David , Calahorrano Alcinoe , Charvis Philippe , Collot Jean‐Yves , Bethoux Nicole
Published: February 2004

The deep structure of the Ecuador subduction zone and adjacent Carnegie Ridge (CR) was investigated using on‐shore off‐shore wide‐angle seimics. A crustal model obtained by 2‐D inversion of traveltimes reveals the overthickened (14 km) oceanic crust of the CR that underthrusts the high velocity (>6 km/s) basement of the upper plate margin wedge, interpreted as part of the accreted oceanic terranes described on‐shore. The plate interface dips 4° to 10° east from the trench to a depth of 15 km. Shadow zones observed on the margin OBS records are interpreted as a low velocity zone consisting of a thin layer of underthrust sediments, and the 3‐km‐thick CR layer 2, whose average seismic velocity of 5.1 km/s is slower than that of the margin wedge. Increased interplate coupling related to the subduction of the thick, buoyant CR may account for an apparent local increased recurrence interval between great interplate earthquakes.
Multiple equilibria and asymmetric climates in the CCM3 coupled to an oceanic mixed layer with thermodynamic sea ice
Authors: Langen Peter L. , Alexeev Vladimir A.
Published: February 2004

Multiple equilibria and asymmetric climates are found in an atmospheric GCM coupled to an upper mixed layer ocean with thermodynamic sea ice on an aquaplanet. The model is run in a configuration close to that employed in the Budyko‐Sellers type energy balance models. All externally specified fields are constant over the year, zonally symmetric and symmetric about the equator. The amplitude of a specified ocean heat transport is varied and within a certain range a number of distinctly different stationary states are found: An ice‐covered planet, a “cold” climate, a “present‐day”‐like climate and an ice‐free “warm” climate. Asymmetric states with large sea ice extents in one hemisphere and none in the other are also found. This work can be considered a step towards understanding why many simpler climate models exhibit multiple equilibria while more comprehensive AGCMs tend not to.
On the role of vibrationally excited H2 as a source of OH in the mesosphere
Authors: Balakrishnan N.
Published: February 2004

It has recently been suggested that the reaction between vibrationally excited H2(v = 1) and O(3P) atoms may be an important source of OH in the upper mesosphere. Here, we report accurate quantum calculations of rate coefficients for the O(3P) + H2(v = 1) reaction and show that the proposed mechanism is not an important source of OH in the mesosphere. Our calculation employs chemically accurate potential energy surfaces for the O + H2 system and quantum mechanical method for the calculation of the relevant cross sections and rate coefficients.
The relationship between exsolution and magnetic properties in hemo‐ilmenite: Insights from Mössbauer spectroscopy with implications for planetary magnetic anomalies
Authors: Dyar M. Darby , McEnroe Suzanne A. , Murad Enver , Brown Laurie L. , Schiellerup Henrik
Published: February 2004

Remanence properties of ilmenites with exsolved hematite have recently been the object of much study, because their high natural remanent magnetization (NRM) is greater than predicted for these two minerals. X‐ray diffraction (XRD) and Mössbauer spectroscopy in conjunction with electron microprobe and NRM measurements were used to explore the possibility that single domain (SD) hematite lamellae in the ilmenite host could explain the observed remanence, and to determine if magnetite is present. XRD results show the presence of ilmenite and hematite. Mössbauer data show that only species assigned to hematite, ilmenite, and a small amount of tetrahedral Fe3+ are present. Magnetic properties at high and low T also indicate that the only magnetic minerals are ilmenite and hematite. Magnetic data suggest that ultra‐fine hematite lamellae are magnetically ordered, and their resultant remanent magnetic anomalies may contribute significantly to magnetism on terrestrial planets, even those without present‐day magnetic fields.
Full particle simulations of short large‐amplitude magnetic structures (SLAMS) in quasi‐parallel shocks
Authors: Tsubouchi K. , Lembège B.
Published: February 2004

Dynamics of SLAMS (short large‐amplitude magnetic structures) is investigated by the use of one‐dimensional, full particle electromagnetic simulations. As previous hybrid simulations and analysis of experimental observations suggested, present results confirm that the SLAMS patterns result from the steepening of long wavelength magnetosonic waves which are excited by diffuse ions (representing the field‐aligned reflected ion beam) interacting with the upstream ambient plasma. Five successive phases have been identified in the SLAMS dynamics: ULF wave growth and symmetric, asymmetric, spiky, and late SLAMS. The present accessibility to high‐resolution (electron) scales leads to the following new features: (1) the leading edge of the SLAMS steepens over a spatial scale from which a large‐amplitude whistler precursor is emitted; (2) this whistler departs from the SLAMS edge and behaves as a new shock front; (3) the spiky SLAMS phase is characterized by the build‐up of a strong spiky electrostatic field (its width is about 0.5 ion inertial length) within the whistler precursor and is intermittent with a lifetime less than one inverse ion gyroperiod; (4) the new shock front suffers a local self‐reformation typical of a quasi‐perpendicular shock in supercritical regime during the late‐SLAMS phase. The features of the spiky SLAMS phase can be used as a typical signature in the time history of the SLAMS dynamics. Spatial/time scales of SLAMS have been measured throughout the different phases and are found in good agreement with results issued from previous hybrid simulations and with experimental measurements made by AMPTE UKS/IRM satellites; these are also compared with recent results from Cluster‐2 space mission.
Latitudinal transport effects on the modulation of a few‐MeV cosmic ray electrons from solar minimum to solar maximum
Authors: Ferreira S. E. S. , Potgieter M. S. , Heber B. , Fichtner H. , Wibberenz G.
Published: February 2004

A three‐dimensional, steady state, numerical model was used to model the propagation of 7 MeV jovian and galactic electrons in the heliosphere. The computations are compared with 3–10 MeV Ulysses/KET electron observations which are still not well explained after ∼1998. To explain these observations, coinciding with solar maximum conditions, it is shown that a reduction in the enhancement of perpendicular transport toward the poles is required compared to solar minimum. The decrease in this enhancement can be correlated to the disappearance of the fast solar wind and/or a heliospheric magnetic field with a meridional component at solar maximum. By assuming a substantial jovian contribution to the total low‐energy electron intensity at high latitudes to explain the Ulysses/KET observations in these regions, important information on the magnitude of perpendicular transport in the polar direction and its time dependence can be deduced.
Whistler waves in Freja observations
Authors: Huang Guang‐Li , Wang De‐Yu , Song Qi‐Wu
Published: February 2004

Several examples of whistler wave packets accompanied by density cavities are detected in F4 experiments of Freja satellite. The density depletion seems to be a fixed structure in space from the cross‐correlation of two Langmuir probes. The wavelet analysis shows the frequency drift from 1 kHz (below the low‐hybrid frequency) to 200 Hz (below the proton cyclotron frequency). The wave packets are always associated with an extremely low frequency component at 20–30 Hz (around the oxygen ion cyclotron frequency). The method of the minimum variance is used to calculate the oblique propagation of the wave packets with an angle decreased from 31 to 17 degrees between the wave vector and the ambient magnetic field. The right polarization of the wave packets is shown in the direction of the ambient magnetic field. Moreover, the phase velocity of the wave packets is inversely proportional to the frequency. These features may support the formation of envelope solitary whistler waves.
Polar Mesospheric Summer Echoes (PMSE) overshoot effect due to cycling of artificial electron heating
Authors: Havnes O.
Published: February 2004

We study the time‐dependent behavior of dust and plasma parameters for artificial electron heating experiments during Polar Mesospheric Summer Echoes (PMSE) conditions, by the use of the model for dusty plasmas introduced by Havnes and Morfill [1984] and Havnes et al. [1990, 1992]. We find that if the heater is run in a long series of cycles with equal and comparatively short (e.g., 10–20 s) intervals in the on and off mode, the difference between the dusty plasma parameters in subsequent heater off phases will be small. This will give the impression that the PMSE, which can be severely weakened during the heater on phase, returns more or less exactly to its value in the former heater off phase. However, we also find that if the heater off phase is kept long (e.g., 160 s), during which the dusty plasma in the radar beam will relax to its undisturbed value or be replaced by unaffected dusty plasma due to horizontal transport by wind, we will see a substantial difference in the plasma parameters from just before the heater is switched on and just after it is switched off. Owing to an additional charging of the dust during the heater on phase and which takes a long time to decharge, the negative charge state of the dust is higher when the heater is switched off than before it was on. This will increase electron gradients in the dusty plasma and also the value of dust charge density to electron density, and we propose that this should lead to a stronger PMSE, or an PMSE overshoot, when the heater is switched off, compared with the value just before it was switched on.