bluuebunny/crossref_metadata_2025 huggingface dataset:
A microscope‐based screening platform for large‐scale functional protein analysis in intact cells
Authors: Liebel Urban , Starkuviene Vytaute , Erfle Holger , Simpson Jeremy C , Poustka Annemarie , Wiemann Stefan , Pepperkok Rainer
Published: October 2003

A modular microscope‐based screening platform, with applications in large‐scale analysis of protein function in intact cells is described. It includes automated sample preparation, image acquisition, data management and analysis, and the genome‐wide automated retrieval of bioinformatic information. The modular nature of the system ensures that it is rapidly adaptable to new biological questions or sets of proteins. Two automated functional assays addressing protein secretion and the integrity of the Golgi complex were developed and tested. This shows the potential of the system in large‐scale, cell‐based functional proteomic projects.
India's First Virtual Community and the Telegraph General Strike of 1908
Authors: Choudhury Deep Kanta Lahiri
Published: October 2003

The telegraph strike of 1908 occurred at many nodes of the telegraph system in British India and Burma, paralysing governance and business. In this paper, I suggest that the strike was a symptom of the systemic crisis in world telegraphy faced with technological change and competition. I introduce the category of transregional economic general strike as a tool to analyse strikes in the communication sectors. The strike demonstrated the ability of one of the earliest virtual communities in India to combine and organize worker protest. This multistage strike momentarily transcended the specific, and usually rigid, distinctions of race, class, and ethnicity through the production of community-at-a-distance. The strike occurred simultaneously among different sections of workers in Rangoon, Moulmein, Calcutta, Allahabad, Agra, Bombay, Madras, Lahore, and Karachi, to name just a few of the places involved. Both telegraph signallers as well as the subordinate staff went on strike. By concentrating on the relationship between technological change and labour, the paper demonstrates how workers across this part of the British Empire were capable of charting a general agenda in the first decade of the twentieth century, using technology to combine and combat technological rationalization.
Perpetually Laborious: Computing Electric Power Transmission Before The Electronic Computer
Authors: Tympas Aristotle
Published: October 2003

Placing Thomas Edison at the beginning of a history on electric power transmission hardly needs justification. Thomas Edison's abundant supply of pictures of himself as an inventive genius – and America's pressing demand for a myth of an ingenious inventor – combined to bestow a “Eureka” moment upon Edison's pioneering Pearl Street (New York) Station electric lighting network. But the history of the laborious computations that took place at Menlo Park and the division-of-computing labor of which Edison took advantage suggests a different view of inventive genius. The story of the computational pyramid formed by the labors of Francis R. Upton, Charles L. Clarke, and Samuel D. Mott (1879–1880) can be reconstructed from the existing literature. In his reminiscences from Menlo Park, Edison's employee, Francis Jehl, detailed how Edison thought of constructing a miniaturized network to be used as a computer of the actual network. Knowing that constructing, maintaining, and using the miniature network required a considerable amount of skilled labor, Edison decided to hire an employee for it, Dr Herman Claudius. Edison enthusiastically welcomed Claudius to perform a type of computing work “requiring nerve and super abundance of patience and knowledge”. Jehl remembered that the labor of constructing a miniature network of conductors, “all in proportion, to show Mr Edison what he would have to install in New York City in connection with the Pearl Street Station” was “gigantic”. Following the pattern of the Pearl Street Station electric lighting network, several similar networks were built in the early 1880s. In response, Edison's labor pyramid was enlarged by giving Claudius an assistant, Hermann Lemp, who performed the monotonous task of constructing the new miniature networks, which Edison needed for computation. Inconvenient as it might be for those who assume that technological change is the product of inventive genius, electrification was, from the beginning, laboriously computed; it was not, like Athena, a deity that leapt from a godly head.
On generic and derivation views of God's trinitarian substance
Authors: Cross Richard
Published: October 2003

The view that the divine substance is some item common to the three persons is frequently rejected in modern trinitarian thought in favour of the view that the divine substance is properly identical with the Father in a way that it is not identical with the Son or Spirit. I argue that these views cannot safeguard the monarchy of the Father, and that in order to safeguard this latter doctrine, it is necessary to hold that the divine substance is some item common to the three persons. I show how this view does not require that there is any sense in which the divine substance is prior to the divine persons.
Inverse position analysis, workspace determination and position synthesis of parallel manipulators with 3-RSR topology
Authors: Di Gregorio Raffaele
Published: October 2003

Manipulators with 3-RSR topology are three-degree-of-freedom parallel manipulators that may be either spherical or mixed-motion manipulators. The inverse position analysis (IPA) and the workspace determination of 3-RSR manipulators are addressed by means of a new approach. The new approach is centered on a particular form of the closure equations called compatibility equations. The compatibility equations contain only the six
coordinates (end-effector coordinates) which locates the end-effector pose (position and
orientation) with respect to the frame, and the geometric constants of the manipulator. When the manipulator geometry is assigned, the common solutions of the compatibility equations are the end-effector coordinates which identify the end-effector poses belonging to the manipulator workspace. Moreover, they can be the starting point to easily solve the IPA. The presented compatibility equations can be also used to solve the position synthesis of the 3-RSR manipulator. This way of solving the position synthesis will demonstrate that only
approximated solutions exist when more than eight end-effector poses are given.
Data reduction for manipulator path planning
Authors: Korb Werner , Troch Inge
Published: October 2003

Today, in robot applications continuous paths often result from CAD or other planning tools. We present here an approach to the question that has been discussed for a long time, i.e. how to approximate a given path by a second one in such a way that the latter
lies in a tube of given radius ε around the first. The approximation should be a (normally cubic) spline with a small number of breakpoints. The strategy is based on
algorithms used in “computer aided geometric design” and is applied
to examples from industrial and surgical robotics.
Post-hurricane recovery of a herbaceous understorey plant in a tropical rain forest in Puerto Rico
Authors: Meléndez-Ackerman Elvia , Calisto-Pérez Carlos , Morales-Vargas Mariety , Fumero-Cabán José
Published: October 2003

Ecologists agree on the importance of hurricanes in community dynamics in tropical forests but little is known of the responses of herbaceous species to large disturbances. The passage of Hurricane Georges over the island of Puerto Rico provided a unique opportunity to study the post-hurricane recovery of Heliconia caribaea, a large understorey herb. Five weeks after Georges, the types of vegetative damage, mortality and recovery were recorded and their relationship with plant size was established. The relationship between recovery strategy and leaf or stem damage severity was also determined. The abundance of H. caribaea seedlings in sites with severe or little forest canopy damage was recorded to determine the effects of canopy cover on seedling establishment. Most individuals showed severe leaf and stem damage. This was not related to plant size. Mortality was low and caused by fallen trees. Recovery was not associated with severity of leaf damage but more individuals with no signs of regeneration appeared among plants that had severe stem damage. Seedling abundance was higher in areas with severe canopy damage relative to those with closed canopy suggesting that hurricanes may benefit H. caribaea by creating suitable habitats for seedling establishment. We argue that recovery strategies like those exhibited by H. caribaea may be common among understorey plants, particularly in areas regularly subjected to large-scale disturbances.
Methodologies for the development of knowledge-based systems, 1982–2002
Authors: PLANT ROBERT , GAMBLE ROSE
Published: October 2003

Knowledge-based systems have often been criticised for the limited theoretical base upon which they are constructed. This view asserts that systems are often
developed in an ad hoc, individual way that leads to unmaintainable, unreliable and non-rigorous systems. The last decade, however, has seen an increased effort to produce methodologies to counter this view as well as continued research into validation and verification techniques. This paper presents a brief discussion of some of the important research in knowledge-based system life cycles and development methods. Methodologies are considered and are discussed in light of two sets of quality assurance criteria.
The “Falun Gong Problem”: Politics and the Struggle for the Rule of Law in China
Authors: Keith Ronald C. , Lin Zhiqiu
Published: October 2003

This article examines the CCP's “falun gong problem” with reference to PRC law and policy on “heretical cults,” paying particular attention to the implications of this problem for the ongoing struggle to establish human rights under the rule of law. Official PRC commentary contends that the falun gong not only committed criminal acts but also wilfully sought to undermine the rule of law itself. Human rights critics and agencies, such as the US Commission on International Religious Freedom, have, on the other hand, attacked the PRC for a “repressive legal framework” that threatens human rights. The “falun gong problem” is an important chapter in the struggle for the rule of law in China, and it appears that the law has not been able to transcend the conceptual bias of past criminal law on counter-revolution. The related politicization of the law through a revived principle of “flexibility” challenges the internal process of criminal justice reform and the recent reform focus on the balance of human rights protection and public order.
The Emergence of Labour Camps in Shandong Province,
1942–1950
Authors: Dikötter Frank
Published: October 2003

This article analyses the emergence of labour camps in the CCP base area of Shandong province from 1942 to 1950. By using original archival material, it provides a detailed understanding of the concrete workings of the penal system in a specific region, thus giving flesh and bone to the more general story of the prison in China. It also shows that in response to military instability, organizational problems and scarce resources, the local CCP in Shandong abandoned the idea of using prisons (jiansuo) to confine convicts much earlier than the Yan'an authorities, moving towards a system of mobile labour teams and camps dispersed throughout the countryside which displayed many of the key hallmarks of the post-1949 laogai. Local authorities continued to place faith in a penal philosophy of reformation (ganhua) which was shared by nationalists and communists, but shifted the moral space where reformation should be carried out from the prison to the labour camp, thus introducing a major break in the history of confinement in 20th-century China.
The Chinese Cultural Revolution Database. By Edited and compiled by the Editorial Board of the Chinese Cultural Revolution Database, editor-in-chief Song Yongyi. CD-ROM with hard copy indexes in Chinese and English. [Hong Kong: Universities' Service Centre for China Studies, The Chinese University of Hong Kong, 2002. 80 MB+index 384 pp. $1,000.00. ISBN 962-996-071-0.]
Authors: Schoenhals Michael
Published: October 2003

What will not be lost on students of revolutionary chromatography is the fact that the hard cover index accompanying this CD-ROM is a huge black book. In the professional jargon of Cultural Revolutionary historians everywhere, The Chinese Cultural Revolution Database is already being referred to, tongue-in-cheek, as the hei cailiao – “black materials” – of editor-in-chief, Song Yongyi. Readable on most MS Windows platforms capable of displaying Chinese characters, it comes with a built-in search-engine and comprises nearly 30 million words. Suddenly, it is as if Eric Hobsbawm already had China's Cultural Revolution – and not merely the former Soviet Union – in mind when he observed, after the fall of the wall, that “Inadequacy of sources is the last thing we can complain about” (On History, p. 239).
Creating a Chinese Harbin: Nationalism in an International City, 1916–1932. By James H. Carter. [Ithaca, NY and London: Cornell University Press, 2002. xiv+217 pp. ISBN 0-8014-3966-3.]
Authors: Mitter Rana
Published: October 2003

In the early 20th century, the cognoscenti put forward a rival to Shanghai as their nominee for the title of “Paris of the East” – the far north-eastern city of Harbin. As they pointed out, although it took weeks for goods or people to make their way by sea to Shanghai, Harbin was accessible from Europe in just a few days via the Trans-Siberian railway. A cosmopolitan, colonial place, Harbin was, like Shanghai, a product of late 19th-century imperialism, but in this case based on railways rather than shipping, and with the Russians, not the British, as the driving force.
The Goldilocks problem
Authors: HULUBEI TUDOR , FREUDER EUGENE C. , WALLACE RICHARD J.
Published: October 2003

Constraint-based reasoning is often used to represent and find
solutions to configuration problems. In the field of constraint
satisfaction, the major focus has been on finding solutions to
difficult problems. However, many real-life configuration problems,
although not extremely complicated, have a huge number of solutions,
few of which are acceptable from a practical standpoint. In this paper
we present a value ordering heuristic for constraint solving that
attempts to guide search toward solutions that are acceptable. More
specifically, by considering weights that are assigned to values and
sets of values, the heuristic can guide search toward solutions for
which the total weight is within an acceptable interval. Experiments
with random constraint satisfaction problems demonstrate that, when a
problem has numerous solutions, the heuristic makes search extremely
efficient even when there are relatively few solutions that fall within
the interval of acceptable weights. In these cases, an algorithm that
is very effective for finding a feasible solution to a given constraint
satisfaction problem (the “maintained arc consistency”
algorithm or MAC) does not find a solution in the same weight interval
within a reasonable time when it is run without the heuristic.
Dietary analysis confirms that Rickett's big‐footed bat (Myotis ricketti) is a piscivore
Authors: Ma Jie , Jones Gareth , Zhang Shuyi , Shen Junxian , Metzner Walter , Zhang Libiao , Liang Bing
Published: October 2003

The diet of Myotis ricketti was examined by faecal analysis, and foraging behaviour was observed in the field. Scales from at least three species of small fish were found in the droppings, together with fragments of insects from six orders. This study demonstrates that M. ricketti is a fish‐eating bat. As with other trawling bats in the genus Myotis, M. ricketti emits short, broadband echolocation sounds. The sounds recorded from bats released from the hand swept downward from c. 70 to 28 kHz in 4 ms, and contained most energy at 41 kHz.
Melatonin secretion in a strictly subterranean mammal, the Damaraland mole‐rat (Cryptomys damarensis)
Authors: Richter T. A. , Malpaux B. , Fleming P. A. , Molteno A. J. , Bennett N. C.
Published: October 2003

Subterranean mammals inhabit an environment that is normally devoid of light and are therefore deprived of photoperiodic information that can be used to time important life‐history events. An assessment was made of whether melatonin secretion in a strictly subterranean rodent, the Damaraland mole‐rat Cryptomys damarensis, can be modified by photoperiod. In experiment 1, a clear diurnal rhythm of melatonin secretion in animals housed under a neutral photoperiod (12L:12D) was observed, with significantly higher melatonin concentrations in the dark compared to the light phase. The same diurnal melatonin rhythm was found 1 day after animals were transferred to either continuous light or continuous dark, suggesting that a circadian rhythm was maintained under acute exposure to light and dark. In experiment 2, melatonin secretion was monitored in a long (14L:10D) and short day (10L:14D) photoperiod and was found to be modified by the photoperiodic change. We therefore suggest that the Damaraland mole‐rat possesses a circadian melatonin rhythm that can be physiologically modulated in response to photoperiod.
The transmission history of the Proper chant for St Gregory: the eighth-mode tract Beatus uir
Authors: Hornby Emma
Published: October 2003

The tract for the feast of St Gregory, Beatus uir, appears in very different versions in the Old Roman and Gregorian traditions, and in more than one version in the Gregorian tradition. Close study of the melodies of these different versions and of the second-mode tract Ecce uir, attached to the feast in Corbie, Bec and Bec-influenced institutions, permits tentative conclusions to be drawn about the adoption of Roman chant in early eighth-century England and mid-eighth-century Francia. Before the concerted Carolingian effort to learn the entire Roman Mass Proper, Beatus uir appears to have been adopted north of the Alps at least twice: in early eighth-century England, and at St Denis in the 750s.
Friedrich Ludwig's ‘Musicology of the Future’: a commentary and
translation
Authors: Haines John
Published: October 2003

Friedrich Ludwig's appointment in medieval music at the University of Straßburg came at a
crucial time for German musicology, then a new discipline in a flourishing academic environment.
Upon entering his post at Straßburg in the autumn of 1905, Ludwig delivered a formal lecture, here translated, in which he outlined the goals for twentieth-century medieval musicology. While many of these goals, in particular the editing of certain theorists and late medieval repertories, have been achieved, other directions implied in Ludwig's synthetic approach have received less attention. Ludwig's own musicology was a creative combination of forces: on the one hand, a reaction to earlier French scholarship in archaeology and philology; on the other, a borrowing of recent German trends in historiography, philosophy and music. Most notable is the influence of Ranke and Hegel on Ludwig's then new concept of latent rhythm (i.e., ‘modal rhythm’) in medieval music. A century of scholarship later, Ludwig's vision for musicology as an innovative interdisciplinary conjunction has much to teach us.
Pronucleus formation, DNA synthesis and metaphase entry in porcine oocytes following intracytoplasmic injection of murine spermatozoa
Authors: Kim Bong-Ki , Cheon Sun Hong , Lee Youn Jeong , Choi Sun Ho , Cui Xiang Shun , Kim Nam-Hyung
Published: October 2003

The onset of pronucleus formation and DNA synthesis in porcine oocytes following the injection of porcine or murine sperm was determined in order to obtain insights into species-specific paternal factors that contribute to fertilisation. Similar frequencies of oocytes with female pronuclei were observed after injection with porcine sperm or with murine sperm. In contrast, male pronuclei formed 8-9 h following the injection of porcine sperm, and 6-8 h following the injection of murine sperm. After pronucleus formation maternally derived microtubules were assembled and appeared to move both male and female pronuclei to the oocyte centre. A few porcine oocytes entered metaphase 22 h after the injection of murine sperm, but normal cell division was not observed. The mean time of onset of S-phase in male pronuclei was 9.7 h following porcine sperm injection and 7.4 h following mouse sperm injection. Ultrastructural observation revealed that male pronuclei derived from murine sperm in porcine oocytes are morphologically similar to normal male pronuclei in porcine zygotes. These results suggest that species-specific paternal factors influence the onset of pronucleus formation and DNA synthesis. However, normal nuclear cytoplasmic interactions were observed in porcine S-phase oocytes following murine sperm injection.
The Burkitt affair revisited. Colonial implications and identity politics in early South African prehistoric research
Authors: Schlanger Nathan
Published: October 2003

The alleged professional misconduct of Cambridge prehistorian Miles Burkitt, over his guided archaeological trip to South Africa in 1927 and the single-authored publication that resulted, has been taken to epitomize colonial relations of expropriation. However, unexploited archival and printed resources show that the affair has far more interesting implications, and that in South Africa of the 1920s and 1930s prehistoric archaeology became something of a ‘national discipline’, bearing both on national prestige abroad and on national unity at home, in the stormy relations between the English- and Afrikaans-speaking communities.
Imagery rehearsal in the treatment of posttraumatic nightmares in Australian veterans with chronic combat‐related PTSD: 12‐month follow‐up data
Authors: Forbes David , Phelps Andrea J. , McHugh Anthony F. , Debenham Paul , Hopwood Malcolm , Creamer Mark
Published: October 2003

Nightmares are often a distressing symptom for veterans with chronic combat‐related posttraumatic stress disorder (PTSD). A psychological treatment that has recently shown considerable promise is Imagery Rehearsal Therapy (IRT). In a pilot study by the current authors, IRT was demonstrated to be effective in the treatment of posttraumatic nightmares in a group of combat veterans up to 3‐month posttreatment. This study reports the 12‐month follow‐up data of the pilot study, examining the longer term outcome of the IRT treatment. Twelve Australian Vietnam veterans with chronic combatrelated PTSD were treated with 6 once weekly sessions of imagery rehearsal and assessed using standardised measures of nightmare frequency and intensity, PTSD, depression, anxiety and broader symptomatology at intake, posttreatment, and 3‐and 12‐month follow‐up. Significant improvements in targeted nightmare frequency and intensity were evident to 12‐month posttreatment. Similarly, improvements in overall PTSD, depression, anxiety, and broader based symptomatology were also maintained to 12 months. This study provides preliminary evidence that the positive treatment effects of IRT on posttraumatic nightmares, PTSD, and broader symptomatology in males with chronic combat‐related PTSD are maintained in the longer term.
Posttraumatic stress disorder (PTSD) in the armed forces: Health economic considerations
Authors: McCrone Paul , Knapp Martin , Cawkill Paul
Published: October 2003

This paper addresses the use of health economics in relation to posttraumatic stress disorder (PTSD) in the Armed Forces, with a view to assessing the feasibility of carrying out future evaluative studies. Although psychological and pharmacological interventions can be used to treat PTSD, no economic evaluations are known to exist. There is an economic burden associated with PTSD, and treatments require the use of scarce resources. Health economics provides tools (including cost‐effectiveness, cost‐benefit, and cost‐utility analyses) to ascertain the relative efficiency of different treatment options. The paper concludes that the quality of life and resource consequences of PTSD require a better understanding of the economics of the disorder and the alternative ways to treat it.
A preliminary examination of treatment for posttraumatic stress disorder in chronic pain patients: A case study
Authors: Shipherd Jillian C. , Beck J. Gayle , Hamblen Jessica L. , Lackner Jeffrey M. , Freeman Jennifer B.
Published: October 2003

Manualized treatments have become popular, despite concern about their use when comorbid diagnoses are present. In this report, the efficacy of manualized posttraumatic stress disorder (PTSD) treatment was examined in the presence of chronic pain. Additionally, the effect of PTSD treatment on chronic pain and additional psychiatric diagnoses was explored. Six female patients with both PTSD and chronic pain following motor vehicle accidents were treated for PTSD using a multiple baseline design. The results indicate that manualized treatment for PTSD was effective in reducing PTSD symptoms in these patients. Although there were no changes in subjective pain, there were pain‐related functional improvements and reductions in other psychiatric diagnoses for the majority of patients.
The Psychological Dimension of Informed Consent: Dissonance Processes in Genetic Testing
Authors: Grover Sonja
Published: October 2003

This paper discusses the issue of the psychological dimension of informed consent. In this paper, the author proposes that informed consent is a continuous variable rather than a dichotomous one. When clients better understand their motives and actual, rather than just perceived degree of choice in pursuing a particular option in a medical setting, their level of informed consent is greater. Findings from existing literature in the field of genetic testing are examined in terms of dissonance theory. These findings suggest that testing candidates sometimes overestimate their coping skills and minimize the threat to psychological integrity that a particular genetic result may pose. Counseling directed towards realistic appraisal of degree of choice in pursuing testing is examined as an aspect of supporting informed consent and possibly reducing the potential for adverse psychological outcome in the longer term.
Mapping secondary mineral formation in porous media using heavy metal tracers
Authors: Tenthorey Eric , Scholz Christopher H.
Published: October 2003

A new technique is presented which allows easy identification of secondary minerals, formed during experimental diagenesis. Reacting fluids are doped with Ba and Sr; heavy metals which substitute into the alkali‐bearing authigenic minerals that precipitate because of alteration of primary labradorite and quartz. The main secondary phases observed are a Ba‐rich zeolite mineral, strontianite, and a Ba‐rich calcite. When polished sections of postexperiment specimens are viewed using scanning electron microscope backscatter imaging, secondary phases appear as bright patches due to their higher density and average atomic number. The more difficult method of X‐ray elemental mapping confirms that these zones represent secondary minerals rich in Ba and Sr. This technique allows the spatial distribution of secondary minerals to be mapped out at the specimen scale in a short time frame. Image analysis shows that observed reductions in permeability are caused primarily by mineral precipitation in narrow pore throats and in areas containing an abundance of fine‐grained material. Secondary mineral formation is concentrated near the top of the sample and is interpreted to migrate through the sample as a reaction front. Mineral coverage is then quantified and used to explain the observed permeability evolution.
Measurements near the Atmospheric Surface Flux Group tower at SHEBA: Near‐surface conditions and surface energy budget
Authors: Persson P. Ola G. , Fairall Christopher W. , Andreas Edgar L. , Guest Peter S. , Perovich Donald K.
Published: October 2003

Measurements at the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) Atmospheric Surface Flux Group (ASFG) tower site from October 1997 to October 1998 are used to describe the annual cycle of the near‐surface environment and the surface energy budget (SEB). Comparisons with historical data and climatological estimates suggest that the SHEBA site was 3–8°C warmer in March and April. The unique SHEBA profile measurements showed that the mean near‐surface environment is strongly stable during 6 winter months, and near neutral or weakly stable during the other months. However, one‐hour data show that neutral stratification does occur 25% of the time during the winter. The monthly mean flux profiles suggest that turbulent processes cool the near‐surface atmosphere during the winter and warm it during the summer, though the sign of the sensible heat flux is negative during both the winter and July. The SHEBA SEB calculation is unique in its nearly exclusive use of observed rather than derived values. The magnitude of the best estimate of the annual net observed surface energy surplus at SHEBA (8.2 W m−2) was consistent with the observed surface ice and snowmelt and was in reasonable agreement with most previous estimates of the net annual SEB over the Arctic pack ice. However, the partitioning of the various components of the SEB differed in the SHEBA data. The SHEBA site had unusually large incoming longwave radiation in the fall and spring, giving an annual mean that was larger by 10.4–19.3 W m−2. The site also had substantially less incoming solar radiation during most months than in previous estimates, producing a difference in the annual mean of 5.0–9.5 W m−2 when compared to these estimates. The observed magnitudes of the sensible (−2.2 W m−2) and latent (1.1 W m−2) heat fluxes at SHEBA were smaller than previous climatological estimates, as were the conductive flux estimates (2.4–5.0 W m−2) at this site. Estimates of the measurement errors suggest that they are not likely to alter the conclusions concerning the SEB terms presented here but will prevent us from conclusively determining the reasons for the net thinning of the ice observed during SHEBA.
University of Michigan MHD results of the Geospace Global Circulation Model metrics challenge
Authors: Ridley A. J. , Hansen K. C. , Tóth G. , De Zeeuw D. L. , Gombosi T. I. , Powell K. G.
Published: October 2003

We present University of Michigan MHD code results of the “metrics challenge.” We have simulated the magnetospheric and ionospheric configuration during the 16–17 April 1999 CME, the 10–11 December 1998 time period, and the 5–6 November 1998 time period. The simulation results were compared to the DMSP cross‐track velocities, and the RMS differences were examined. We have found that the code reproduces the DMSP data quite accurately except for the sharpness of the gradients and the transients which were observed. The cross polar cap potential was well matched, as was the location of the convection reversal boundary. In addition, the code reproduced features of statistical models of the ionospheric electric potential.
Wind observations of foreshock cavities: A case study
Authors: Sibeck D. G. , Phan T.‐D. , Lin R. , Lepping R. P. , Szabo A.
Published: October 2003

We present a case study of plasma, energetic particle, and magnetic field perturbations seen by Wind in the dawn foreshock on 19 April 1996. A comparison with the results of hybrid simulations confirms model predictions for a diamagnetic cavity flanked by regions of enhanced density and magnetic field strength but filled with a suprathermal ion population. In contrast to previously reported hot flow anomalies, flow velocities within the foreshock cavities are nearly identical to those in the ambient solar wind, ion temperatures do not rise greatly, thermal pressures are only slightly greater than those in the ambient solar wind, and the events do not lie centered upon interplanetary magnetic field (IMF) tangential discontinuities intersecting the bow shock. We attribute the cavities to the diamagnetic effects of ions Fermi accelerated within the foreshock. A review suggests that foreshock cavities are far more common than hot flow anomalies.
Assessing vertical axis rotations in large‐magnitude extensional settings: A transect across the Death Valley extended terrane, California
Authors: Petronis Michael S. , Geissman John W. , Holm Daniel K. , Wernicke Brian , Schauble Edwin
Published: October 2003

Models for Neogene crustal deformation in the central Death Valley extended terrane, southeastern California, differ markedly in their estimates of upper crustal extension versus shear translations. Documentation of vertical axis rotations of range‐scale crustal blocks (or parts thereof) is critical when attempting to reconstruct this highly extended region. To better define the magnitude, aerial extent, and timing of vertical axis rotation that could mark shear translation of the crust in this area, paleomagnetic data were obtained from Tertiary igneous and remagnetized Paleozoic carbonate rocks along a roughly east‐west traverse parallel to about 36°N latitude. Sites were established in ∼7 to 5 Ma volcanic sequences (Greenwater Canyon and Brown's Peak) and the ∼10 Ma Chocolate Sundae Mountain granite in the Greenwater Range, ∼8.5 to 7.5 Ma and 5 to 4 Ma basalts on the east flank of the Black Mountains, the 10.6 Ma Little Chief stock and upper Miocene(?) basalts in the eastern Panamint Mountains, and Paleozoic Pogonip Group carbonate strata in the north central Panamint Mountains. At the site level, most materials yield readily interpretable paleomagnetic data. Group mean directions, after appropriate structural corrections, suggest no major vertical axis rotation of the Greenwater Range (e.g., D = 359°, I = 46°, α95 = 8.0°, N = 12 (7 normal (N), 5 reversed (R) polarity sites)), little post‐5 Ma rotation of the eastern Black Mountains (e.g., D = 006°, I = 61°, α95 = 4.0°, N = 9 N, 6 R sites), and no significant post‐10 Ma rotation of the Panamint Range (e.g., D = 181°, I = −51°, α95 = 6.5°, N = 9 R sites). In situ data from the Greenwater Canyon volcanic rocks, Chocolate Sundae Mountain granite, Funeral Peak basalt rocks, the Little Chief stock, and Paleozoic carbonate rocks (remagnetized) are consistent with moderate south east‐side‐down tilting of the separate range blocks during northwest directed extension. The paleomagnetic data reported here suggest that the Panamints shared none of the 7 Ma to recent clockwise rotation of the Black Mountains crystalline core, as proposed in recent models for transtensional development of the central Death Valley extended terrane.
Focusing of magma in the upper mantle through dike interaction
Authors: Ito Garrett , Martel Stephen J.
Published: October 2003

We use laboratory experiments and numerical models to quantify the effects of dike interaction on the focusing of magma as it ascends in the upper mantle. Laboratory experiments involve injecting buoyant fluid into the base of a tank filled with solidified gelatin. When we initiate two dikes parallel to each other, but separated by a horizontal distance x, they tend to merge as they ascend. This behavior is also predicted by numerical models of two‐dimensional dikes. The key parameters that control the maximum horizontal separation xc over which dikes will intersect are dike driving pressures, dike head lengths L (i.e., the length over which driving pressure is large), and the difference between the principal stresses of the remote stress field. When the remote differential stress is small compared to the dike driving pressure, two dikes of equal driving pressure and length will intersect over distances of xc ∼ L. This distance decreases with increasing remote differential stress. We quantify the effects on magma transport from a broad lateral distribution of magma using numerical simulations of multiple‐dike interaction. When the average dike spacing prior to interaction is within ∼3L and remote differential stresses are insignificant, dike interaction can focus magma over horizontal distances many times L but at least ∼6L. Dike interaction can focus magma in the asthenosphere beneath mid‐ocean ridges for low mantle viscosities (≤1019 Pa s) and if dikes initiate with average separations of a few hundred meters, or less. Such focusing is predicted to grow dikes of increasing magma flux approaching lateral separations of a kilometer.
Characterization of the mechanical behavior of sea ice as a frictional material
Authors: Lade Poul V.
Published: October 2003

The mechanical properties of sea ice are determined by the formation process, and the consequent material behavior at the element scale exhibits viscoelastic behavior at the early loading stages, followed by brittle fracture or ductile, irrecoverable deformation that may be captured by hardening/softening plasticity models with nonassociated flow. Failure of sea ice under different loading conditions follows a pattern that demonstrates its highly cross‐anisotropic nature as well as its behavior as a frictional material. The interactions between the floes in the pack ice resemble those observed in granular materials. These materials are frictional in nature, they exhibit both contractive and dilative volume changes, the plastic flow is nonassociated, and their stiffnesses and strengths increase with confining pressure, but they do not have any strength when unconfined. The overall behavior of the pack ice may be close to isotropic. Constitutive modeling of this behavior may be achieved by models used in geotechnical engineering. Formation of leads and subsequent freezing of the water results in cementation between the ice floes, and the pack ice becomes stronger. The behavior of the pack ice may now be compared with that observed in cemented soils or concrete. For these materials, increasing amounts of cementation result in increasing rates of dilation when sheared, and this accounts for the largest contribution to the increase in shear strength.
Permanent strain of thermal expansion and thermally induced microcracking in Inada granite
Authors: Lin Weiren
Published: October 2003

I made measurements of the permanent strain of thermal expansion, compressional wave velocity, and density of microcracks of Inada granite, which was subjected to slow and homogeneous temperature change under atmospheric pressure. The permanent strain implying the cumulative amount of newly generated microcracks and the opening of preexisting microcracks appeared distinctly at a temperature between 100° and 125°C and increased almost exponentially in the range from 200°C to immediately before the temperature of α‐β transition in quartz (573°C) as the peak temperature of the thermal cycle was elevated. At 600°C, the strain increased further. The density of the microcracks was heightened as the peak temperature increased. Moreover, the said trend coincided with that of the crack density parameter estimated from the compressional wave velocity. At the same time, the maximum width of the microcracks, which was determined by microscopic observation, and the average width increment of the microcracks, calculated from the permanent strain and microcrack density, showed a similar trend. Using the mercury intrusion porosimetry method, the average width increment of the microcracks coincided with the equivalent width of the microcracks measured. There are two causes of thermally induced microcracking: the mismatching of the coefficients of thermal expansion between the adjacent mineral grains and the decrepitation of the fluid inclusions. The density of the fluid inclusion microcracks showed a remarkable increase starting from the peak temperature of 300°C. At temperatures equal to or higher than 400°C, the fluid inclusion microcracks accounted for approximately 35% of all the intragranular cracks.
Weathering and damage
Authors: Hoke Gregory D. , Turcotte Donald L.
Published: October 2003

Weathering of rock surfaces is often associated with a surface dissolution process. Chemical interactions occur on grain boundaries and diffusion is the controlling process. A dissolution boundary layer (rind) develops adjacent to the weathering surface. We quantify the extent of dissolution by introducing a damage variable f, f = 0 for pristine rock, and when f = f0 the rock disintegrates. We assume that the variations of the damage variable are given by the diffusion equation. We solve two problems. The first is for the structure of the transient dissolution boundary layer prior to surface disintegration. We find an incubation time ti before active weathering (disintegration) begins. The second is the solution for steady state weathering with a constant weathering velocity vw. Our results are entirely consistent with weathering studies on Carrera marble gravestones in the United Kingdom.
Uncertainties in sea surface turbulent flux algorithms and data sets
Authors: Brunke Michael A. , Zeng Xubin , Anderson Steven
Published: October 2003

An intercomparison of eight bulk sea surface turbulent flux algorithms used in data set generation as well as weather and climate prediction is performed for the tropical Pacific and midlatitude Atlantic. The results show some significant differences in fluxes due to differences in the way the algorithms consider wave spectrum, convective gustiness, and salinity as well as the way the algorithms parameterize roughness lengths and turbulent exchange coefficients. For instance, for sea surface temperature between 27.75°C and 28.25°C, the maximum differences in monthly latent heat flux and wind stress among algorithms over the tropical Pacific are about 23 W m−2 (or 16% relative to the algorithm‐averaged flux) and 0.013 N m−2 (or 19% relative to the algorithm‐averaged value) respectively. Evaluation of these algorithms using 270 hourly samples of observed turbulent flux data over the midlatitude Pacific shows that algorithms are largely consistent with observations. However, some algorithms show significant deviations from observations under certain conditions (e.g., weak wind conditions). Insights from the above intercomparison are then used to evaluate ocean surface turbulent fluxes from two global data sets, one is derived from satellite remote sensing while the other is a reanalysis. Over two buoy sites in the eastern and western tropical Pacific, the mean heat flux differences between the two data sets are primarily caused by differences in bulk variables (e.g., wind speed) rather than by differences in bulk algorithms. However, bulk algorithm differences could contribute up to 17 W m−2 to the long‐term averaged latent heat flux over the tropical Pacific if different algorithms were used. This suggests that both bulk algorithms and the deviation of environmental variables need to be further improved in order to produce ocean surface turbulent fluxes with an accuracy of 10 W m−2.
Alfven resonator in the topside ionosphere beneath the auroral acceleration region
Authors: Pilipenko V. A. , Fedorov E. N. , Engebretson M. J.
Published: October 2003

The possible occurrence of a new resonator in the topside ionosphere at auroral latitudes is proposed. This resonator is formed between the E‐layer of the ionosphere and the bottom boundary of the auroral acceleration region (AAR), which has a localized field‐aligned potential drop. The AAR is shown to effectively reflect Alfven waves with transverse scales less than the Alfven transit scale λA. The proposed resonator can trap and accumulate Alfvenic small‐scale disturbances with periods from a few seconds to a few tens of seconds, and with transverse scales from a kilometers to a few tens of kilometers. The eigenfrequencies of the AAR‐associated resonator are estimated to be lower than that of the ionospheric Alfven resonator. The small‐scale Alfvenic structures commonly observed by satellites can be generated by a nonsteady field‐aligned current transported by precipitating electrons and trapped in the AAR‐associated resonator. Observations by ground‐based magnetometers at auroral latitudes often show the occurrence of intensifications in the dynamic spectra of Pi1 pulsations in accordance with the predictions of the model.
A statistical analysis of ionospheric velocity and magnetic field power spectra at the time of pulsed ionospheric flows
Authors: Abel G. A. , Freeman M. P.
Published: October 2003

We analyze the power spectrum of the line‐of‐sight ionospheric velocity measured by the SuperDARN CUTLASS Finland radar and of contemporaneous magnetic field perturbations measured by nearby IMAGE magnetometers. The measurements come from 69–87° AACGM latitude and 0415–2230 MLT during 58 intervals of pulsed ionospheric flow between March 1995 and September 1996. The median power spectrum of both the velocity and magnetic field is of power law form with a best fit exponent of −0.5 and −1.3, respectively. By simulating the effect of the finite sample window on the measured spectral exponent and on the structure seen in the power spectral density of individual spectra, we show that the measured spectral exponent actually corresponds to a true exponent of −0.95 for the velocity and −1.8 for the magnetic field. Furthermore, it is shown that the difference in the exponents of the velocity and magnetic field spectra is at least in part due to a spatial smoothing effect that causes the spectral exponent of the ground magnetic spectrum to be less than that of the ionospheric current spectrum producing it. The power law power spectrum implies that there is no preferred timescale for ionospheric velocity and current fluctuations in the observed frequency range. It is proposed that this scale‐free nature may arise from the intermittent, turbulent nature of the interplanetary magnetic field causing magnetic reconnection to occur at the magnetopause on a wide range of spatial and temporal scales.
Hybrid simulations of solar wind interaction with magnetized asteroids: General characteristics
Authors: Omidi N. , Blanco‐Cano X. , Russell C. T. , Karimabadi H. , Acuna M.
Published: October 2003

Using electromagnetic hybrid (kinetic ions, fluid electrons) simulations, the interaction between solar wind and a magnetized asteroid is investigated. At no or very low levels of asteroid magnetization the solar wind remains undisturbed. As the level of magnetization is increased, a phase standing whistler wake is generated which owing to its propagation characteristics remains confined to planes close to that containing the solar wind flow velocity and the interplanetary magnetic field (IMF). No density perturbations are associated with this wake. Further increase in asteroid magnetization results in the additional generation of fast and slow magnetosonic wakes, which fall behind the whistler wake and are associated with the formation of a plasma tail. Because of their propagation characteristics, these wakes are more symmetric than the whistler wake. At still higher levels of magnetization where plasma pileup occurs upstream of the asteroid, the fast magnetosonic wake becomes dominant and eventually exhibits shock‐like behavior. In general, the size of the interaction region increases with the level of asteroid's magnetic field strength. This interaction region is highly structured and asymmetric owing to wave propagation characteristics and the IMF direction. In addition, once the fast magnetosonic wake is strong enough to result in ion reflection the subsequent E × B motion of these ions results in considerable asymmetry in the interaction region. This is a purely ion kinetic effect which comes about as a result of the overall interaction region being comparable to ion scale lengths.