bluuebunny/crossref_metadata_2025 huggingface dataset:
Das Biegedrillknickverhalten von Glasträgern aus Verbundglas
Authors: Kasper Ruth , Sedlacek Gerhard , Feldmann Markus
Published: February 2007

Bei der Bemessung von Trägern aus Verbundglas stellt sich stets die Frage, inwieweit eine Verbundwirkung der Zwischenfolie mit visko‐elastischem Materialverhalten (PVB‐Folie), welche die Biegedrillknickanfälligkeit erheblich reduzieren würde, in Ansatz gestellt werden kann. Die Berücksichtigung des zeit‐ und temperaturabhängigen Verhaltens mit ständigen und variablen Lastanteilen sowie Temperaturzyklen ist zwar wirtschaftlich wünschenswert, aber die Umsetzung wird in der Praxis als schwierig angesehen. Im folgenden werden die wichtigsten Lösungs‐ und Arbeitsschritte eines neu entwickelten Bemessungskonzeptes [1] vorgestellt, mit dem das Biegedrillknickverhalten von Verbundglasträgern, ausgehend von dem experimentell ermittelten zeit‐ und temperaturabhängigen Steifigkeitsverhalten der am meisten verwendeten PVB‐Folie und erweiterten Verwölbungsansätzen für den Verbundquerschnitt, über Versuche und Simulationen verifiziert werden kann. Dabei liegt der Schwerpunkt auf der Einbezugnahme des zeitabhängigen Effektes.
A discussion of the concept of “feudal”
Authors: Jianxin HOU
Published: February 2007

The Western terms “feudal” and “feudalism” have been widely and improperly translated as “fengjian” in contemporary China. The early Western Sinologists and Chinese scholars, including Yan Fu, did not originally make such a translation. Yan initially transliterated the term “feudalism” as fute zhi in his early translations. It was not until the 20th century, when Western classical evolutionism found its way into China, that “feudalism” was reduced to an abstrac t concept, and the Western European model was generalized as a framework for understanding development in China and the whole world. Only then did Yan Fu first equate “feudalism” with “fengjian,” and China was believed to have experienced a “feudal society” in the same sense as Europe. From the perspective of intellectual history, using evidential and theoretical analyses, this article attempts to show that feudalism was a historical product in the development of Western Europe and existed only in Europe, “fengjian” is a system appropriate only in discussions of pre-Qin China, and China from the Qin to the Qing experienced instead a system of imperial autocracy. The medieval periods in the West and in China evidence widely divergent social forms and hence should not be confused with the same label.
The emperor’s four bodies: Embodied rulership and legal culture in early Ming China
Authors: Yanhong WU , Yonglin JIANG
Published: February 2007

This essay explores how the emperor’s body was perceived in the imperial rulership and treated uniquely in legal culture in early Ming China. It argues that the ruling elite articulated four types of imperial bodies, i.e., the body cosmic, the body politic, the body social, and the body physical, each of which exemplified a specific dimension of rulership. The emperor’s four bodies are manifested in the imperial laws. The imperial laws place the emperor’s body cosmic inferior to Heaven, ensure the emperor’s sole authority in communicating with Heaven, require the officials’ faithful service to the ruler, urge the ruler to observe rules, and strictly protect the emperor’s physical body. The imperial laws, by regulating the different relationships in the embodied rulership, serve as the essential instrument to create the ideal cosmic order.
Behavior and attitude towards the world: A comparative analysis between the Cynics and the School of Zhuangzi
Authors: Juping YANG
Published: February 2007

During the fourth and third centuries B.C., both the ancient Greek and Chinese civilizations evolved into key periods of social transformation. The Cynics and the School of Zhuangzi responded most acutely to these great social changes. Both of them denied the legitimacy of the existing political systems, denounced the upper rulers and felt disappointed at the comprehensive reality of societies, and were indifferent to fame and gain, and willing to live simply and smile at death. But compared with the Zhuangzi School, the Cynics were more extreme and defiant. Viewed from both macro and micro perspectives, the differences in civilizations, geographical conditions, and historical traditions determined the difference in behavior and attitudes of the two schools in terms of their behavior in the world. Nevertheless, their similarities outweigh their differences because of the similar development stages of their civilizations, similar socio-historical periods and similar social and living problems confronted.
Egyptian women’s position in the family in the time of the Pharaohs
Authors: Ye ZHANG , Hongcai LIU
Published: February 2007

Although many scholars have assert that the Egyptian women’s position in the family was high during the time of the Pharaohs, no research in China has made a comprehensive and systematic discussion over this issue so far. Based on both documents and archaeological materials, this article approaches this question in three aspects: (1) Egyptian women’s position in the family economy; (2) the affection between the husband and the wife; (3) the position and role of the mother.
The Treaty of Peace with Japan and the Korean truce negotiations
Authors: Zhihua SHEN
Published: February 2007

The outbreak of the Korean War caused the U.S.A. to become determined in excluding the People’s Republic of China (PRC) from the Treaty of Peace with Japan, the signing of which is hoped to be hastened by winning the Korean War. Before the signing of the treaty, the U.S.A. intentionally delayed the Korean truce negotiations in order to prevent the PRC from attending the San Francisco Peace Conference. After the signing, the U.S.A. preferred an immediate cessation of hostilities in Korea, whereas the Soviet Union and the PRC, bogged down in the Far East by the terms of the treaty, were determined to take a hard-line stance, hoping that the U.S.A. would become tied down and drained on the Korean battlefield. Thus, there was a subtle relationship between the treaty and the negotiations in the context of the Cold War.
A critique of relativism in the sociology of scientific knowledge
Authors: Si SUN
Published: February 2007

“The Strong Programme” is put forward as a metaphysical theory of sociology by the Edinburgh School (SSK) to study the social causes of knowledge. Barry Barnes and David Bloor are the proponents of the School. They call their programme “the Relativist View of Knowledge” and argue against rationalism in the philosophy of science. Does their relativist account of knowledge present a serious challenge to rationalism, which has dominated 20th century philosophy of science? I attempt to answer this question by criticizing the main ideas of SSK and defending rationalism theories in modern philosophy of science.
Queries on Hempel’s solution to the paradoxes of confirmation
Authors: Xinguo DUN
Published: February 2007

To solve the highly counterintuitive paradox of confirmation represented by the statement, “A pair of red shoes confirms that all ravens are black,” Hempel employed a strategy that retained the equivalence condition but abandoned Nicod’s irrelevance condition. However, his use of the equivalence condition is fairly ad hoc, raising doubts about its applicability to this problem. Furthermore, applying the irrelevance condition from Nicod’s criterion does not necessarily lead to paradoxes, nor does discarding it prevent the emergence of paradoxes. Hempel’s approach fails to adequately resolve the paradox.
Appreciating nature in view of practical aesthetics
Authors: Keping WANG
Published: February 2007

Appreciating nature may at its best feature have three levels of experience according to practical aesthetics. The first level is more sensuous as it largely pleases the ear and eye, the second level is more psychological as it chiefly pleases the mind and mood, and the third level is more sublimate as it mainly pleases the will and spirit. In Chinese culture the affinity between man and nature can be traced back to the traditional conception of tian ren he yi 天人合一 as heaven-human oneness, which will be ultimately conducive to the artistic realm or aesthetic state of being.
Transesterification Kinetics of Soybean Oil for Production of Biodiesel in Supercritical Methanol
Authors: He Huayang , Sun Shiyao , Wang Tao , Zhu Shenlin
Published: February 2007

A kinetic study on soybean oil transesterification without a catalyst in subcritical and supercritical methanol was made at pressures between 8.7 and 36 MPa. It was found that the conversion of soybean oil into the corresponding methyl esters was enhanced considerably in the supercritical methanol. The apparent activation energies of the transesterification are different with the subcritical and the supercritical states of methanol, which are 11.2 and 56.0 kJ/mol (molar ratio of methanol to oil: 42, pressure: 28 MPa), respectively. The reaction pressure considerably influenced the yield of fatty acid methyl esters (FAME) in the pressure range from ambient pressure up to 25 MPa (280 °C, 42:1). The reaction activation volume of transesterification in supercritical methanol is approximately −206 cm3/mol. The PΔV≠ term accounts for nearly 10% of the apparent activation energy, and can not be ignored (280 °C, 42:1).
Military industrialization and economic development: Jordan's defense industry
Authors: Amara Jomana
Published: February 2007

Jordan is a recent entrant to the domestic defense industry with the establishment of King Abdullah II Design and Development Bureau (KADDB) in 1999. The defense industrial initiative is intended to jumpstart industrialization across a range of sectors. With the Jordanian defense expenditures at 8.7% of GDP, the Jordanian authorities created the defense industry to utilize defense budget spending power and to assist in economic growth without placing additional demands on the national budget. This study examines Jordan's attempt to establish a defense industry and reviews its accomplishment. The study also compares the economic achievements of the defense industry to those of the Qualified Industrial Zone (QIZ), another major government facilitated economic development mechanism.
U.S. corporate bond returns: A study of market anomalies based on broad industry groups
Authors: Nippani Srinivas , Arize Augustine C.
Published: February 2007

We examine three major U.S. corporate bond market indices for calendar‐based anomalies over the period 1982–2002. The analysis covers the entire corporate bond market and two broad industry classes: industrials and utilities. We find mixed support for the weekend effect in the overall bond index and the industrials index and to a lesser extent in the utilities index. We also show strong evidence of a January effect. This paper not only updates the study of corporate bond market anomalies through the period 2002 but also is the first examination based on broad industry classes.
Nitrate and ammonium losses from surface-applied organic and inorganic fertilizers
Authors: KING K. W. , TORBERT H. A.
Published: February 2007

Animal manures are a valuable resource, providing readily available plant nutrients; however, runoff from lands receiving animal manure has been shown to contribute to water pollution. Understanding the loss of nutrients from slow release fertilizers, such as animal manure, after application is critical in determining and designing practices to reduce and/or control the temporal availability and potential offsite transport of NO3-N and NH4-N after application. A block study was designed to compare and contrast the temporal losses of NO3-N and NH4-N from three slow release fertilizers (sulphur-coated urea, composted dairy manure, and poultry litter) and one fast release fertilizer (ammonium nitrate) applied to bermudagrass (Cynodon dactylon L. Pers.) turf. Cumulative NO3-N loss from plots receiving application of the manufactured (NH4NO3 and sulphur-coated urea) products was significantly (P<0·05) greater than the measured losses from plots receiving application of natural products (composted dairy manure and poultry litter). The cumulative NO3-N recovered in the runoff expressed as a proportion of applied N was 0·37 for ammonium nitrate, 0·25 for sulphur-coated urea, 0·10 for composted dairy manure, and 0·07 for poultry litter during the 10-week study period. Cumulative NH4-N recovery fractions were an order of magnitude less than the cumulative NO3-N fractions and no significant differences (P>0·05) were measured across treatments. Significant differences (P<0·05) in NH4-N and NO3-N loss through time were measured for the four treatments. The findings of the present study indicate that land-applied animal manures are less susceptible to initial losses of N when compared to manufactured fertilizers.
About the most unstable modes encountered in beam plasma interaction
physics
Authors: BRET ANTOINE , FIRPO MARIE-CHRISTINE , DEUTSCH CLAUDE
Published: February 2007

A thorough analysis of the electromagnetic instabilities encountered
in the beam plasma interaction physics shows that the most unstable modes
are not the ones which are usually studies. We characterize these most
unstable modes and determine the patterns they create.
Study of laser induced ablation with focused ion beam/scanning electron microscope devices
Authors: BUSSOLI MARCO , BATANI DIMITRI , DESAI TARA , CANOVA FEDERICO , MILANI MARZIALE , TRTICA MILAN , GAKOVIC BILJANA , KROUSKY EDOUARD
Published: February 2007

We propose the use of Focused Ion Beam/Scanning Electron Microscope (FIB/SEM) devices for the analysis of ablation results. Ablated samples have been obtained by irradiating an Al planar target with an optically smoothed iodine laser working at 0.44 μm. The interpretation of FIB images shows the high potentiality of the technique.
Stochastic heating in ultra high intensity laser-plasma
interaction
Authors: BOURDIER A. , PATIN D. , LEFEBVRE E.
Published: February 2007

Stochastic instabilities are studied considering the motion of one
particle in a very high intensity wave propagating along a constant
homogeneous magnetic field, and in a high intensity wave propagating in a
nonmagnetized medium perturbed by one or two low intensity traveling
waves. Resonances are identified and conditions for resonance overlap are
studied. The part of chaos in the electron acceleration is analyzed. PIC
code simulation results confirm the stochastic heating.
Laser ablation of ion irradiated CR-39
Authors: BASHIR SHAZIA , RAFIQUE M. SHAHID , UL-HAQ FAIZAN
Published: February 2007

The effects of multiple pulses of a CO2 laser with energy
of 2.5 J and pulse duration of 200 ns on the surface morphology of ion
irradiated CR-39 is investigated in light of the modification in its track
registration properties. For this purpose, a CR-39 was exposed by a
CO2 laser generated hydrogen, argon, cadmium, air molecular
ions (N2 and O2, etc.), high energy (300 KeV) proton
beam from Cock Croft Walton accelerator, and α (5 MeV) from 0.5
μCi Pu239 source. The registered tracks were enlarged after
6 h of 6.25 N NaOH etching. These etched detectors were then exposed to
different number of CO2 laser shots. The etched detectors were
then analyzed by a computer controlled optical microscope (Lexica DMR
series). It was observed that even a single shot of CO2 laser,
irrespective of the registered ions tracks, can change the track
registration properties of CR-39, and can remove the vaporization
resistant skin present on the polymer (CR-39). A significant change in
track density and track shaping regardless of the ions is observed. At the
outside of the focal area, the ion density of different registered tracks
is compared graphically before and after laser irradiation. Laser ablation
of unexposed CR-39 is also done with multiple pulses CO2 laser.
In this regard, the coherent and non-coherent structures, diffraction
patterns, circular fringes with corrugations and ripples, droplets, chain
like structures with cluster formation, chain folded crystallites, and
hole drilling were observed. The irradiation induced ablation of the
polymer is of great importance in electronics industry, lithography,
etc.
Indications of Holocene sea-level rise in Beaver Lake, East Antarctica
Authors: Wagner Bernd , Hultzsch Nadja , Melles Martin , Gore Damian B.
Published: February 2007

A 100 cm long sediment sequence was recovered from Beaver Lake in Amery Oasis, East Antarctica, using gravity and piston corers. Sedimentological and mineralogical analyses and the absence of micro and macrofossils indicate that the sediments at the base of the sequence formed under glacial conditions, probably prior to c. 12 500 cal. yr BP. The sediments between c. 81 and 31 cm depth probably formed under subaerial conditions, indicating that isostatic uplift since deglaciation has been substantially less than eustatic sea-level rise and that large areas of the present-day floor of Beaver Lake must have been subaerially exposed following deglaciation. The upper 31 cm of the sediment sequence were deposited under glaciomarine conditions similar to those of today, supporting geomorphic observations that the Holocene was a period of relative sea-level highstand in Amery Oasis.
Smoking supernovae
Authors: Gomez H.L. , Eales S.A. , Dunne L.
Published: February 2007

The question ‘Are supernovae important sources of dust?’ is a contentious one. Observations with the Infrared Astronomical Satellite (IRAS) and the Infrared Space Observatory (ISO) only detected very small amounts of hot dust in supernova remnants. Here, we review observations of two young Galactic remnants with the Submillimetre Common User Bolometer Array (SCUBA), which imply that large quantities of dust are produced by supernovae. The association of dust with the Cassiopeia A remnant is in question owing to the contamination of foreground material. In this paper, we compare the emission from cold dust with CO emission towards Kepler’s supernova remnant. We detect very little CO at the location of the submillimetre peaks. A comparison of masses from the CO and the dust clouds are made, and we estimate the 3σ upper limit on the gas-to-dust ratios to be in the range 20–60. These results suggest that we cannot yet rule out freshly-formed or swept-up circumstellar dust in Kepler’s supernova remnant.
A case for immunological approaches in detection and investigation of alien life
Authors: Tang Bor Luen
Published: February 2007

The feasibility of immunological detection using antibodies as an approach to detect and study alien life forms is examined. The latter could either mean alternative forms of life on planet Earth or extraterrestrial life. As a detection reagent for biological substances, antibodies have the advantage of being conformational, rather than sequence-dependent. Their high affinity to cognate antigens allows detection at picomolar levels. Antibodies could serve both as tools for detection as well as for the concentration of samples. Panels of highly specific antibodies could be made against a plethora of natural or synthetic biomarkers, for example stereoisomers of amino acids, nucleotide analogues, lipids, polysaccharides and polycyclic aromatic hydrocarbons. With detection reagents efficiently packaged and miniaturized as immunosensor chips in analytical panels, antibody microarrays could serve as the first line of detection and identification of biological remnants in situ during exploratory missions. Specific antibodies could also be used for affinity concentration of possible biomarkers obtained from sample return missions. Furthermore, antibodies raised against any alien biological samples could be the first specific probes made for further detection of, or investigations on, alien biology.
Caregiving at the end of life: Perspectives from spousal caregivers and care recipients
Authors: JO SUSAN , BRAZIL KEVIN , LOHFELD LYNNE , WILLISON KATHLEEN
Published: February 2007

Objective: The purpose of this study is to examine the perspectives of both the spousal caregiver and care recipient on the caregiving experience in home-based palliative care.

Methods: A qualitative research strategy involving home-based face-to-face interviews with older palliative care patients and their spousal caregivers was used to examine the caregiving experience.

Results: Ten spousal caregivers and care recipient dyads participated in the study. Most informal caregivers viewed caregiving as an extension of the family relationship where caregiving responsibilities evolved over time. Spousal caregivers identified many negative reactions to caregiving, such as fatigue or weariness, depression, anger and sadness, financial stresses, and lack of time. Care recipients acknowledged the emotional and financial strain and expressed concern for their spouses. Both caregivers and care recipients were appreciative of home care services although they identified the need for additional services. They also identified difficulties in communication with formal providers and poor coordination of care among the various services. Both caregivers and care recipients disclosed some challenges with informal supports, but on the whole felt that their presence was positive. Additional positive aspects of caregiving reported by spouses included strengthened relationship with their spouse and discovering emotional strength and physical abilities in managing care.

Significance of results: Health care and social service professionals need to recognize and understand both caregiver and care recipient perspectives if they are to successfully meet the needs of both members of the dyad.
Does social support from family and friends work as a buffer against reactions to stressful life events such as terminal cancer?
Authors: RINGDAL GERD INGER , RINGDAL KRISTEN , JORDHØY MARIT S. , KAASA STEIN
Published: February 2007

Objective: To examine the relationship between social support and emotional functioning and stress reactions. Our hypothesis is that patients who reported a high degree of social support will experience better emotional functioning and less serious stress reactions than patients with a low degree of social support.

Method: The sample was comprised of 434 patients at the Palliative Medicine Unit (PMU), University Hospital of Trondheim in Norway. The patients completed a questionnaire monthly including questions about social support from the MacAdam's Scale, subjective stress measured by the Impact of Event Scale (IES), and emotional functioning measured by the subscale in the EORTC QLQ-30.

Results: Although our hypothesis was not supported at the baseline assessment, it was supported at the second assessment, 2 months later. Patients with high social support reported better emotional functioning and less serious stress reactions, in terms of lower scores on the IES avoidance subscale, than patients with a low degree of social support.

Significance of the results: The mixed findings may indicate that social support has only small effects on emotional functioning and stress reactions. Our results on the second assessment indicate, however, that social support might work as a buffer against reactions toward external stressful events such as terminal cancer.
When Multiplication Doesn't Equal Quick Addition: Examining
Intersectionality as a Research Paradigm
Authors: Hancock Ange-Marie
Published: February 2007

In the past twenty years, intersectionality has emerged as a
compelling response to arguments on behalf of identity-based politics
across the discipline. It has done so by drawing attention to the
simultaneous and interacting effects of gender, race, class, sexual
orientation, and national origin as categories of difference.
Intersectional arguments and research findings have had varying levels of
impact in feminist theory, social movements, international human rights,
public policy, and electoral behavior research within political science
and across the disciplines of sociology, critical legal studies, and
history. Yet consideration of intersectionality as a research paradigm has
yet to gain a wide foothold in political science. This article closely
reads research on race and gender across subfields of political science to
present a coherent set of empirical research standards for
intersectionality.
Atmospheric scaling of cosmogenic nuclide production: Climate effect
Authors: Staiger Jane , Gosse John , Toracinta Rick , Oglesby Bob , Fastook James , Johnson Jesse V.
Published: February 2007

Absorption of cosmic rays by atmospheric mass varies temporally due to a redistribution of atmospheric pressure by ice sheets during glaciations, the compression and expansion of the atmosphere due to cooling and warming, and changes in katabatic winds near large ice masses. These atmospheric processes can result in changes in production rates of cosmogenic nuclides which, when integrated over long exposure durations may result in 0% to >5% adjustments in site production rates depending on location. Combining a CCM3 model with imbedded ice sheets for 20 ka, we show that production rates changes (relative to today) are greatest at high elevations (6–7% at 5 km altitude) due to atmospheric compression from decreased temperature. Production rates at specific times for sites near ice sheet margins can be reduced more than 10% due to a combination of katabatic winds draining off the ice sheet margins and atmospheric cooling. Nunatak settings may be significantly affected by the climate effect due to persistent glacial atmospheric conditions. Atmospheric variability may explain some of the disparities among cosmogenic nuclide production rate calibrations.
Second critical endpoint in the peridotite‐H2O system
Authors: Mibe Kenji , Kanzaki Masami , Kawamoto Tatsuhiko , Matsukage Kyoko N. , Fei Yingwei , Ono Shigeaki
Published: February 2007

The second critical endpoint in the peridotite‐H2O system has been determined using an X‐ray radiography technique together with a Kawai‐type, double‐stage, multianvil system driven by DIA‐type cubic press (SPEED‐1500) installed at SPring‐8, Japan. The pressure of the second critical endpoint was determined by the appearance and disappearance of round shape in the radiographic images with changing the experimental pressure. In the experiments up to 3.6 GPa, two fluid phases (i.e., aqueous fluid and hydrous silicate melt) were observed. At 4.0 GPa, however, we could not distinguish these two phases in the radiographic images. These observations indicate the second critical endpoint occurs at around 3.8 GPa and 1000°C (corresponding to a depth of ∼110 km) in the peridotite‐H2O system. Our experimental results suggest that hydrous silicate melt and aqueous fluid in the Earth's mantle become indistinguishable from each other and that melting temperature of hydrous mantle peridotite can no longer be defined beyond this critical condition. This position of the second critical endpoint could explain the previously observed drastic changes in composition and connectivity of aqueous fluid in mantle peridotite at around 3–4 GPa and could play an important role in magmatism and chemical evolution of the Earth's interior.
On the relationship between the water mass pathways and eddy variability in the Western Mediterranean Sea
Authors: Demirov E. K. , Pinardi N.
Published: February 2007

The role of eddies on the formation and spreading of water masses in the Western Mediterranean Sea is studied with an ocean general circulation model. The model is forced with interannually variable surface forcing for the years from 1979 to 1999. It is found that the model reproduces the major features of the observed mesoscale variability in the Gulf of Lions and the large eddies evolution in the Algerian Basin. The seasonal evolution of circulation in the Gulf of Lions and processes of spreading of newly formed intermediate deep waters in the postconvection period is studied for years 1987 and 1992. The model results are compared with data from observations. It is shown that the instability of the transition zone between old and newly formed deep waters, which takes place after the violent mixing stages of the deep convection, leads to collapse of the mixed patch and formation of mesoscale eddies. Some of these eddies propagate out of the Gulf of Lions transporting deep waters into the Algerian Basin. The rest of the mesoscale eddies filled with newly formed deep waters remain in the Gulf of Lions and tend to merge and enlarge. After the cyclonic eddies reach the Algerian Basin they interact with the intense mesoscale field existing there. The energy analysis shows that the winter and spring are seasons of intensified baroclinic instability of the mean flow in the two regions of interest, the Gulf of Lions and Algerian Basin. The kinetic energy is released by baroclinic instability in spring and summer. The spring spectra in the two regions have maximums at horizontal scales of about 80–100 km which is the typical scale of the eddies in the model. These eddies propagate a cyclonic circuit. The resulting eddy‐induced mass transport in deep and intermediate layers is directed out of the Gulf of Lions and toward the Gibraltar Strait. Equivalently, we can argue the intermediate and deep waters conveyor belt of the Western Mediterranean Sea is eddy‐driven.
Formation of Mangala Fossa, the source of the Mangala Valles, Mars: Morphological development as a result of volcano‐cryosphere interactions
Authors: Leask Harald J. , Wilson Lionel , Mitchell Karl L.
Published: February 2007

The morphology of the Mangala Fossa graben forming the source of the Mangala Valles implies that two episodes of graben subsidence took place, each induced by lateral dike intrusion from Arsia Mons. Quantitative modeling suggests that graben boundary faults breaching the cryosphere provided pathways for water release from an underlying aquifer at a peak rate of ∼107 m3 s−1. In the first event, the graben subsided by ∼200 m, and water carrying a thin ice layer filled the graben, overflowing after ∼2.5 hours, mainly at a low point on the north rim. This captured the water flux, eroding a gap in the north wall which, with an erosion rate of ∼100 μm s−1 and a duration of ∼1 month, was ∼250 m deep by the end of water release. Erosion of the graben floor also took place, at ∼20 μm s−1, lowering it by ∼50 m. Subsequently, heat from the cooling dike melted cryosphere ice, causing a further ∼150 m of subsidence on compaction. In the second event, with a similar duration and peak discharge, the graben again subsided by ∼200 m and filled with ice‐covered water until overflow through the gap began at a water depth of ∼350 m. The gap was eroded down by a further ∼400 m, and the floor was eroded by a further ∼50 m. Finally, heat from the second dike sublimed cryosphere ice, lowering the floor by ∼100 m. In places, combined erosion and subsidence of the graben floor exposed ∼200 m of the first dike.
Glacial/interglacial changes in mineral dust and sea‐salt records in polar ice cores: Sources, transport, and deposition
Authors: Fischer Hubertus , Siggaard‐Andersen Marie‐Louise , Ruth Urs , Röthlisberger Regine , Wolff Eric
Published: February 2007

Sea‐salt and mineral dust records as represented by Na+ and Ca2+ concentrations, respectively, in Greenland and Antarctic ice cores show pronounced glacial/interglacial variations. For the Last Glacial Maximum (LGM), mineral dust (sea salt) concentrations in Greenland show an increase of a factor of approximately 80 (15) compared to the Holocene and significant shifts by a factor of 15 (5) during Dansgaard‐Oeschger events. In Antarctica the dust (sea salt) flux is enhanced by a factor of 15 (3) during the LGM compared to the Holocene, and variations by approximately a factor of 8 (1–2) exist in parallel to Antarctic warm events. Primary glacial dust sources are the Asian deserts for Greenland and Patagonia for Antarctica. Ice core evidence and model results show that both changes in source strength as well as atmospheric transport and lifetime contributed to the observed changes in Greenland ice cores. In Antarctica, changes in ice core fluxes are in large parts related to source variations both for sea salt and dust, where the formation of sea‐salt aerosol from sea ice may play a pivotal role. Summarizing our latest estimates on changes in sources, transport, and deposition, these processes are roughly able to explain the glacial increase in sea salt in both polar regions, while they fall short by at least a factor of 4–7 for mineral dust. Future improvements in model resolution and in the formulation of source and transport processes together with new ice core records, e.g., on dust size distributions, will eventually allow convergence of models and observations.
Upscaling of mass transfer rate coefficient for the numerical simulation of dense nonaqueous phase liquid dissolution in heterogeneous aquifers
Authors: Saenton Satawat , Illangasekare Tissa H.
Published: February 2007

Mass transfer from entrapped dense nonaqueous phase liquids (DNAPLs) in heterogeneous aquifers takes place in natural, three‐dimensional groundwater flow fields. However, mass transfer processes are characterized in the laboratory in columns or flow cells under conditions of one‐dimensional or two‐dimensional water flow. Dissolution data generated in these test systems are used to determine empirical parameters of correlations that relate a dimensionless form of a mass transfer coefficient (Sherwood number) to other dimensionless groups that capture the basic processes contributing to mass transfer (e.g., Reynolds and Schmidt numbers). These phenomologically based empirical correlations, which are referred to as Gilland‐Sherwood models, are not directly applicable in predicting the dissolution of DNAPLs in the field as they do not capture the effects of aquifer heterogeneity and DNAPL entrapment morphology (referred to as DNAPL entrapment architecture). Numerical simulation of DNAPL dissolution requires the discretization of the problem domain into computational grid blocks and assignment of an effective mass transfer coefficient to each of these blocks containing DNAPL. A methodology for upscaling is needed to determine the grid‐scale effective mass transfer coefficient from the laboratory‐determined empirical correlations. It is our hypothesis that the upscaled effective mass transfer coefficient needs to contain information on the field‐scale heterogeneity and DNAPL entrapment architecture. This hypothesis was tested through a Monte‐Carlo‐based numerical experiment using a laboratory‐validated dissolution model with the goal of developing and testing an upscaling method. The developed upscaling method involves the use of geostatistical parameters that capture the aquifer heterogeneity and the DNAPL entrapment architecture. These parameters were determined to be the variance of log hydraulic conductivity, correlation lengths, and the normalized second moments of DNAPL mass distribution in the entrapment zone. Monte Carlo numerical simulation experiments combined with inverse modeling were used in this theoretical development and to determine parameters of the proposed upscaled Gilland‐Sherwood mass transfer correlation. Through these numerical modeling studies, the upscaled mass transfer correlation was successfully verified. Sensitivity analyses indicate that the normalized second moment, which describes the spreading of DNAPL mass in the vertical directions, was the most sensitive parameter in simulating the mass transfer at large scales.
Variable‐density saturated flow with modified Darcy's law: The salt lake problem and circulation
Authors: Wooding Robin A.
Published: February 2007

For unsteady variable‐density seepage flow, alternative solutions are obtained by taking, respectively, the curl and the divergence of a linear form of Darcy's law, and solving each problem directly, using compatible boundary conditions. This gives a vector potential formulation depending upon the horizontal density gradient, and a pressure formulation depending upon the vertical density gradient, resulting in two complementary solutions. Two velocity fields are obtained by taking the curl of the vector potential solution, and by solving Darcy's law using the gradient of the pressure solution, and corresponding vector potentials are obtained, fairly symmetrically, from these velocities. The novelty is that a linear combination of the two solutions can be made by simple addition or subtraction, with independent scalar coefficients, having broader scope than each of the alternative solutions alone. A two‐dimensional model, based on convective plumes in a Hele‐Shaw experiment with a macroscopic Rayleigh number of 3975, is treated as a benchmark salt lake problem, having a uniform evaporation layer with 1% noise along one‐third part of the upper boundary, with appropriate saline recharge. The coefficients are optimized for maximum circulation. This determines the ratio of the pressure‐based solution to the vector potential–based solution, modifying the Rayleigh number downward to an effective value of 3455. Numerical streamlines reveal secondary flow typical of Henry circulation, measured by a peak stream function equal to the circulation flux. From finger geometry, there is better agreement between the numerically calculated plumes and the experimental plumes than has been achieved previously.
Stratigraphy of the Hawai‘i Scientific Drilling Project core (HSDP2): Anatomy of a Hawaiian shield volcano
Authors: Garcia Michael O. , Haskins Eric H. , Stolper Edward M. , Baker Michael
Published: February 2007

The Hawai‘i Scientific Drilling Project (HSDP2) successfully drilled ∼3.1 km into the island of Hawai‘i. Drilling started on Mauna Loa volcano, drilling 247 m of subaerial lavas before encountering 832 m of subaerial Mauna Kea lavas, followed by 2019 m of submarine Mauna Kea volcanic and sedimentary units. The 2.85 km stratigraphic record of Mauna Kea volcano spans back to ∼650 ka. Mauna Kea subaerial lavas have high average olivine contents (13 vol.%) and low average vesicle abundances (10 vol.%). Most subaerial Mauna Kea flows are ‘a‘ā (∼63%), whereas the Mauna Loa section contains nearly equal amounts of pāhoehoe and ‘a‘ā (like its current surface). The submarine Mauna Kea section contains an upper, ∼900 m thick, hyaloclastite‐rich section and a lower, ∼1100 m thick, pillow‐lava‐dominated section. These results support a model that Hawaiian volcanoes are built on a pedestal of pillow lavas capped by rapidly quenched, fragmented lava debris. The HSDP2 section is compared here to a 1.7 km deep hole (SOH1) on Kilauea's lower east rift zone. Differences in the sections reflect the proximity to source vents and the lower magma supply to Kilauea's rift zone. Both drill core sections are cut by intrusions, but the higher abundance of intrusions in SOH1 reflects its location within a rift zone, causing more extensive alteration in the SOH1 core. The HSDP2 site recovered a relatively unaltered core well suited for geochemical analyses of the single deepest and most complete borehole ever drilled through a Hawaiian or any other oceanic island volcano.
Transport of plasma sheet material to the inner magnetosphere
Authors: Denton M. H. , Thomsen M. F. , Lavraud B. , Henderson M. G. , Skoug R. M. , Funsten H. O. , Jahn J.‐M. , Pollock C. J. , Weygand J. M.
Published: February 2007

The reaction of the plasma sheet in response to an increase in magnetospheric convection is examined using a combination of energetic neutral atom (ENA) imaging and in situ observations. Data from the IMAGE/MENA instrument are examined in conjunction with observations from the magnetospheric plasma analyzer (MPA) instrument onboard the Los Alamos 1994‐084 satellite located in geosynchronous orbit. Examination of the MENA data during an enhanced convection event reveal that between 12:00 and 14:30 UT on 26 June 2001, ENA emissions from the plasma sheet material are observed to strengthen and move Earthwards. A simple calculation of the motion of the peak in ENA emissions following an increase in the convection gives an averaged speed of this sunward surge of around 8 km s−1 between 12:00 and 14:30 UT.
Influence of atmospheric transport on the inter‐annual variation of the CO2 seasonal cycle downward zero‐crossing
Authors: Murayama S. , Higuchi K. , Taguchi S.
Published: February 2007

Using a 3‐dimensional atmospheric transport model driven by the ECMWF winds and the non‐interannually varying seasonal biospheric flux from the CASA global ecosystem model, we show that a significant change in the downward‐zero crossing day (DZCD) of the atmospheric CO2 seasonal cycle in the Northern Hemisphere above 30°N latitude can be obtained by year‐to‐year changes in the atmospheric transport alone. The transport model is able to reproduce both the trend and standard deviation of DZCD observed at Pt. Barrow. With only atmospheric transport changing from year to year, eastern North Atlantic, Europe, southern Eurasia, southeastern United States and western North America show DZCD starting earlier by 5–10 days after 21 years of model integration. If DZCD obtained from CO2 monitoring stations is going to be used as a proxy for determining the growing season length, then it is important to take into account of that portion caused by the atmospheric transport.
Postseismic deformation following the 1991 Racha, Georgia, earthquake
Authors: Podgorski J. , Hearn E. H. , McClusky S. , Reilinger R. , Taymaz T. , Tan O. , Prilepin M. , Guseva T. , Nadariya M.
Published: February 2007

The 1991, Ms = 7.0 Racha earthquake is the largest ever recorded in the Caucasus Mountains. Approximately three months after this thrust‐faulting earthquake, a GPS network was set up to measure postseismic surface deformation. We present an analysis of these data, which indicate accelerated postseismic motions at several near‐field sites. We model this deformation as either afterslip on the rupture surface or viscoelastic relaxation of the lower crust. We find that the postseismic motions are best explained by shallow afterslip on the earthquake rupture plane. The minimum postseismic moment release is estimated at 6.0 × 1018 N m, which is over 200 times the moment released by aftershocks in this same period and about 20% of the coseismic moment. We also show that the effective viscosity of the lower crust in the western Greater Caucasus region exceeds 1018 Pa s.
4D simulation of explosive eruption dynamics at Vesuvius
Authors: Neri Augusto , Esposti Ongaro Tomaso , Menconi Gianluca , De'Michieli Vitturi Mattia , Cavazzoni Carlo , Erbacci Giovanni , Baxter Peter J.
Published: February 2007

We applied a new simulation model, based on multiphase transport laws, to describe the 4D (3D spatial coordinates plus time) dynamics of explosive eruptions. Numerical experiments, carried out on a parallel supercomputer, describe the collapse of the volcanic eruption column and the propagation of pyroclastic density currents (PDCs), for selected medium scale (sub‐Plinian) eruptive scenarios at Vesuvius, Italy. Simulations provide crucial insights into the effects of the generation mechanism of the flows ‐ partial collapse vs boiling‐over ‐ on their evolution and hazard potential, the unstable dynamics of the fountain, and the influence of Mount Somma on the propagation of PDCs into the circum‐Vesuvian area, one of the world's most hazardous volcanic settings. Results also show that it is possible to characterize the volcanic column behavior in terms of percentage of the mass of pyroclasts collapsed to the ground and how this parameter strongly influences the dynamics and hazard of the associated PDCs.
Numerical simulation of fine structure in the Io plasma torus produced by the centrifugal interchange instability
Authors: Wu H. , Hill T. W. , Wolf R. A. , Spiro R. W.
Published: February 2007

The Io plasma torus as a whole has a radial width scale ∼1 RJ, much larger than the width of the localized Io plasma source (∼1 RIo ≈ RJ/39). One of the most prominent features of the Io torus observed by the Voyager spacecraft and Earth‐based instruments is the “ribbon” structure near Io's orbit. The stability properties of this narrower ribbon structure embedded within the larger torus have been investigated by the Rice Convection Model for Jupiter. Four initial plasma distributions having different radial widths are each represented by 82 longitudinally symmetric edges establishing 41 levels of the flux tube mass content η with the peak η value at Io's orbit. The same initial perturbation is put on each of these edges and is subjected to centrifugal interchange. Our simulations produce regularly spaced long, thin fingers moving outward from the outer edges. It is shown that the azimuthal width of the interchange convection cells (the distance between outflowing fingers in the nonlinear stage of development) is proportional to the radial width scale of the initial distribution that produced them. The constant of proportionality is ≈0.5. Since the exponential growth rate is essentially proportional to the azimuthal wave number of the disturbance and hence is inversely proportional to its azimuthal width, the ribbon‐scale interchange structures grow faster than torus‐scale interchange structures.
Self‐potential observations during hydraulic fracturing
Authors: Moore Jeffrey R. , Glaser Steven D.
Published: February 2007

The self‐potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of −200 mV/MPa. However, for pressure drops >2 MPa, the magnitude of the Cc increases by 80% in an exponential trend. This increasing Cc is related to increasing permeability at high pore pressures caused by dilatancy of microcracks and is explained by a decrease in the hydraulic tortuosity. Resistivity measurements reveal a decrease of 2% prior to hydraulic fracturing and a decrease of ∼35% after fracturing. An asymmetric spatial SP response created by injectate diffusion into dilatant zones is observed prior to hydraulic fracturing, and in most cases this SP variation revealed the impending crack geometry seconds before failure. At rupture, injectate rushes into the new fracture area where the zeta potential is different than in the rock porosity, and an anomalous SP spike is observed. After fracturing, the spatial SP distribution reveals the direction of fracture propagation. Finally, during tensile cracking in a point load device with no water flow, a SP spike is observed that is caused by contact electrification. However, the time constant of this event is much less than that for transients observed during hydraulic fracturing, suggesting that SP created solely from material fracture does not contribute to the SP response during hydraulic fracturing.
Hydrothermal fluid flow and deformation in large calderas: Inferences from numerical simulations
Authors: Hurwitz Shaul , Christiansen Lizet B. , Hsieh Paul A.
Published: February 2007

Inflation and deflation of large calderas is traditionally interpreted as being induced by volume change of a discrete source embedded in an elastic or viscoelastic half‐space, though it has also been suggested that hydrothermal fluids may play a role. To test the latter hypothesis, we carry out numerical simulations of hydrothermal fluid flow and poroelastic deformation in calderas by coupling two numerical codes: (1) TOUGH2 [Pruess et al., 1999], which simulates flow in porous or fractured media, and (2) BIOT2 [Hsieh, 1996], which simulates fluid flow and deformation in a linearly elastic porous medium. In the simulations, high‐temperature water (350°C) is injected at variable rates into a cylinder (radius 50 km, height 3–5 km). A sensitivity analysis indicates that small differences in the values of permeability and its anisotropy, the depth and rate of hydrothermal injection, and the values of the shear modulus may lead to significant variations in the magnitude, rate, and geometry of ground surface displacement, or uplift. Some of the simulated uplift rates are similar to observed uplift rates in large calderas, suggesting that the injection of aqueous fluids into the shallow crust may explain some of the deformation observed in calderas.