bluuebunny/crossref_metadata_2025 huggingface dataset:
Information Needs and Roles for Family Members of Dialysis Patients
Authors: Isenberg Karen Bandel , Trisolini Michael
Published: February 2008

OBJECTIVE

The purpose of this research was to understand the roles of family members in dialysis care and to identify information gaps that renal professionals and organizations can address to better meet family member needs.

METHODS

Twelve triads were conducted with 41 family members. Triads explored caregiving roles and challenges, sources of dialysis information, and information needs across stages of dialysis care and a range of topics related to dialysis.

RESULTS

Resources and guidance for nutrition management was the most frequently reported information need. It was also the most common challenge and the role family members most frequently experienced with dialysis care. Other roles included providing emotional support, medication management, and transportation. Results also suggested that the information needs of family members may change over time. Stages included: (1) understanding the patient's diagnosis; (2) managing dialysis and its effects; and (3) understanding the long‐term effects of dialysis.

DISCUSSION

Family members' information needs parallel the roles they play in caring for the patient, and these needs can change over time. Renal providers and professionals should acknowledge and address these needs of family members, whether they are new to dialysis or have years of experience. Informational materials tailored to or distributed during different stages of dialysis and greater access to family‐member support opportunities are likely to be beneficial.
Niobia‐Supported Palladium–Manganese Materials: Synthesis and Structural Investigation
Authors: Brayner Roberta , Villain Françoise , Gengembre Leon , Ammar Souad , Bozon‐Verduraz François
Published: February 2008

Pd/niobia, Mn/niobia, and bimetallic Pd–Mn/niobia materials, which are catalysts for the total oxidation of ethanal,were prepared by anchoring molecular precursors, Pd(acac)2and/or Mn(acac)2, on niobia before calcination at 400 °C and reduction by either soft chemical routes in liquid medium (Pd‐based samples) or at 600 °C in H2 (Mn/niobia sample). The structure of the obtained materials was investigated by FTIR spectroscopy of adsorbed CO, transmission electron microscopy, X‐ray photoelectron spectroscopy, and extended X‐ray absorption fine structure–X‐ray absorption near edge spectroscopy. On Mn/niobia, Mn2+ is largely predominant, in spite of the high reduction temperature used for this sample, and it is mainly engaged in manganese niobate MnNb2O6. On Pd/niobia, nanoparticles of palladium metal (mean particle size 2.7 nm) are predominant, with a contribution of Pd2+. The surface structure of Pd–Mn/niobia is rather complex. Palladium is distributed between Pd3Mn nanoparticles and palladium clusters, and both are partially covered by oxygen atoms, whereas Mn2+ ions are engaged in MnO clusters linked to niobia. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Effects of temperature and perch diameter on arboreal locomotion in the snake Elaphe guttata
Authors: Gerald Gary W. , Mackey Mark J. , Claussen Dennis L.
Published: February 2008

Arboreality is widespread in multiple lineages of snakes and these habitats are important for foraging, escaping predators, and thermoregulation for many species. However, very little is known about factors influencing the arboreal locomotor abilities of snakes. Arboreal performance was assessed in a semi‐arboreal snake (Elaphe guttata) using an artificial perch apparatus. Locomotor velocity, body posture, and balance was measured during movement on three perch diameters (3, 6, 10‐cm) at three temperatures (10, 20, 30°C). Velocities attained by E. guttata on perches are much slower than those of terrestrial lateral undulation and swimming and somewhat slower than concertina velocities recorded in other species across the same experimental temperatures. At higher temperatures, faster speeds were associated with a more elongated posture. At lower temperatures, snakes displayed a more looped body posture, but still fell more often than at higher temperatures. Our results suggest that temperature has a large influence on both balance and movement by snakes on perches. Although there were no differences in velocities resulting from perch diameter, snakes fell more often from thicker perches. This differs from arboreal velocities attained by limbed vertebrates, which decrease with decreasing perch diameter, suggesting that snakes have a size‐relative advantage over limbed animals, such as lizards, when traversing a network of narrow branches. Future studies investigating arboreal locomotion among snakes that vary both phylogenetically and morphologically are needed to assess the potential benefits of limblessness in complex, three‐dimensional environments. J. Exp. Zool. 309A:147–156, 2008. © 2008 Wiley‐Liss, Inc.
Effect of a CD‐ROM‐based educational intervention on resident knowledge and adherence to deep venous thrombosis prophylaxis guidelines
Authors: Baskin Cindy , Seetharamu Nagashree , Mazure Brian , Vassallo Linda , Steinberg Harry , Kerpen Howard , Mattana Joseph
Published: February 2008

BACKGROUND

CD‐ROM‐based educational methods are not new to residency training, yet little is known about how they affect resident knowledge and patient care practices.

OBJECTIVE

We evaluated the effects of a CD‐ROM‐based educational tool on residents' knowledge of anticoagulation and their adherence to anticoagulation guidelines.

DESIGN, SETTING AND PARTICIPANTS

Residents in the departments of cardiothoracic surgery, emergency medicine, otolaryngology, internal medicine, neurosurgery, dental medicine, neurology, obstetrics and gynecology, orthopedics, surgery, and urology at a university hospital participated in the study.

INTERVENTION

Residents were provided with CD‐ROM‐based training on the proper use of anticoagulation based on the sixth ACCP guidelines for antithrombotic therapy. Multiple choice testing was carried out before and after the CD‐ROM intervention to assess resident knowledge, and resident compliance with venous thromboembolism prophylaxis guidelines was assessed via inpatient chart review by an independent committee.

MAIN OUTCOME MEASURES

Changes in knowledge were measured via test scores and the rate of compliance with anticoagulation guidelines.

RESULTS

Multiple choice test scores of 117 residents increased significantly after reviewing the CD‐ROM (from 46.7% ± 15.1% to 77.8% ± 15.1%, P < .005). As a control, we administered the same test at the same 2 times at a comparable institution but without the CD‐ROM intervention and found that test scores did not significantly increase. Chart review revealed a rate of compliance with anticoagulation guidelines for prophylaxis of venous thromboembolism of 75% before the CD‐ROM intervention, which increased to 95% after the intervention, an increase that was sustained for at least 7 months.

CONCLUSIONS

These findings suggest that CD‐ROM‐based interventions might be useful not only in enhancing resident knowledge but also in improving the quality of care by favorably affecting clinical practice. Journal of Hospital Medicine 2008;3:42–47. © 2008 Society of Hospital Medicine.
Conducting business in the Philippines: The case of FedEx
Authors: Pettus Michael L. , Mark Munoz J.
Published: February 2008

Development of international markets is crucial for firm growth. As world trade has expanded rapidly in recent years, strategic international expansion has become increasingly important. Michael Porter's Determinates of International Country Attractiveness model (“diamond”) has been the standard used to determine “where” firms should expand internationally. These determinants include (1) demand conditions, (2) related and supporting industries, (3) strategy, structure, and rivalry, and (4) factor conditions. Aside from the issue of “where” firms should expand, thinking through “how” firms should develop international positions is equally important in a successful expansion. This paper uses the resource‐based view of the firm to explain “how” firms should develop international markets and utilizes FedEx's expansion in the Philippines as an example. © 2008 Wiley Periodicals, Inc.
Trust generated by aid agency web page design
Authors: Burt Christopher D. B. , Dunham Annette H.
Published: February 2008

Two experiments examined how material presented on an aid agency web homepage influenced perceptions of trust in the organisation. Experiment 1 manipulated whether the agency's homepage showed photographs of a crisis‐need, photographs of the crisis‐need and the agency's response or photographs of the agency's response. Experiment 2 held the crisis‐need‐response information constant, but manipulated information on the proportion of donated funds which the agency used to cover administration versus those used to deliver services. In both experiments the participants' dispositional (personality) level of trust and altruism was significantly related to rated trust in the charity. Analysis of covariance was used to control for dispositional trust and altruism, and found that the manipulations in both experiments produced significant changes in rated agency trust. The results are discussed in relation to designing aid agency web pages, and to encouraging individuals to make on‐line donations.

Copyright © 2008 John Wiley & Sons, Ltd.
Counting your chickens: density and distribution of chicken remains in archaeological sites of Oceania
Authors: Storey A. A. , Ladefoged T. , Matisoo‐Smith E. A.
Published: February 2008

In an effort to document the density and distribution of prehistoric chicken (Gallus gallus) remains across Oceania, this paper presents the analysis of reported faunal remains from over 500 individual archaeological and natural sites from across the Pacific. We examined the presence and absence of chicken in secure prehistoric contexts and factors which may account for this, including human choice, taphonomy, the influence of other animals on extinction events, differential access to resources, and purposeful extirpation. This research highlights the need for full study of the large percentage (18%) of Pacific avifauna collections which have yet to be analysed, to clarify the range and importance of chicken in prehistory. Copyright © 2008 John Wiley & Sons, Ltd.
A computational study of the interactions of the caespitate molecule with water
Authors: Mammino Liliana , Kabanda Mwadham M.
Published: February 2008

The water solvent effects on the caespitate molecule—an acylated and prenylated phloroglucinol of natural origin exhibiting antibacterial and antifungal activities—are investigated both as bulk effects and considering explicit water molecules H‐bonded to its donor and acceptor centers. All calculations are performed at HF/6‐31G(d,p) level and the bulk effect of the solvent is calculated with the PCM method. PCM calculations without explicit water molecules show a change in the relative energy pattern, for which the five lowest energy conformers have only the intramolecular hydrogen bond involving the carbonyl O atom of the acyl chain and one of the neighboring OH groups of the phloroglucinol moiety (first H‐bond), whereasin vacuo, the 24 lowest energy conformers (accounting for practically all the population) have also the intramolecular hydrogen bond (second H‐bond) involving an O atom of the ester function (with which the prenyl chain ends) and one of the neighboring OH groups of the phloroglucinol moiety. Calculations with explicit water molecules show that the first intramolecular H‐bond is mostly maintained, whereas the second H‐bond is not maintained on competition with intermolecular H‐bonds with water molecules. Preferred geometrical arrangements of water molecules around the caespitate molecule are identified and the effects, on such geometrical preferences, of the presence of the two substituent chains are highlighted by comparison with the adducts of the parent compound. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
A comparative study on low‐energy elastic electron‐NHx (x = 1,2,3) collisions
Authors: Brescansin L. M. , Lee M.‐T. , Machado L. E.
Published: February 2008

In this work, a theoretical study on elastic electron‐NHx (x = 1,2,3) collisions in the low‐energy range is presented. More specifically, calculated elastic differential, integral, and momentum transfer cross‐sections are reported in the (1–30)‐eV energy range. An optical potential composed of static, exchange, and correlation–polarization contributions is used to represent the electron‐target interaction whereas the iterative Schwinger variational method and the method of continued fractions are used to solve the scattering equations. Comparison of the calculated cross‐sections for electron scattering by these targets shows that the results are very similar to each other at higher incident energies. This similarity indicates that the interaction between the scattering electron and the central Nitrogen is dominant. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Schweißverzug, Schweißeigenspannungen und Schalenstabilität
Authors: Loose Tobias
Published: February 2008

Imperfektionen haben Einfluss auf das Stabilitätsverhalten von Kreiszylinderschalen und entstehen unter anderem aus dem Fügeprozess. Dieser Aufsatz befasst sich mit numerischen Untersuchungen von Schweißverzug und Schweißeigenspannungen von Kreiszylinderschalen mit einlagig geschweißter Umfangsnaht und deren Einfluss auf das Stabilitätsverhalten unter Axiallast. Betrachtet werden Zylinder und Zylindersegmente aus den Stählen S235 und S355 mit Blechdicken von 1 mm bis 4 mm und Radien von 200 mm bis 1600 mm.

Am Beispiel eines Zylinders wird der Entstehungsvorgang des Schweißverzuges erläutert und der qualitative Verlauf der Radialverformung nach dem Schweißen gezeigt. Besonderheiten bei den entstehenden Eigenspannungen werden erläutert.

Der Einfluss des transienten Schweißprozesses einlagiger Umfangsnähte auf die Axialgrenzspannung der Kreiszylinderschale wird mit Hilfe einer Parameterstudie betrachtet. Aus dieser Parameterstudie werden Gesetzmäßigkeiten für den Schweißverzug bei unterschiedlichen Zylinderschlankheiten ermittelt.
Zuschriften zu: Held, N.: Effektive Wärmedämmung bei durchlaufenden Stahlträgern
Authors: Lange Jörg
Published: February 2008

[Stahlbau 76 (2007), H. 11, S. 860–861, ]
Piety as Politics amongst Muslim Women in Contemporary Sri Lanka
Authors: HANIFFA FARZANA
Published: February 2008

In this paper I argue that the manner in which piety is perceived and propagated among Muslims in Sri Lanka must be understood as located within the context of ethnic conflict and the polarization between ethnic groups that occurred in its wake. I explore the work of one Muslim women'sda'wa(preaching) group—Al Muslimaat—that pioneered the process of making piety popular among lower-middle and middle-income Muslim women in a semi-urban Colombo neighbourhood. Looking at the group's activities and specifically through analyses of thebayanor lay sermons delivered by their most charismatic member, I look at the nature of the pious practice that is preached. I argue that in making a self-consciously pious Muslim female subject, Al Muslimaatbayansare affecting ideas of masculinity and femininity among the suburban Muslims with whom they work, and recasting Muslimness in a manner exclusive of ethnic others. I argue also that by marginalizing the kafir in propagating the new Muslim, Al Muslimaat and the greater piety movement in Sri Lanka is mirroring the particular incommensurable identities already espoused by the violently strident Sinhala and Tamil nationalisms in the country.
Field intercomparison of a novel optical sensor for formaldehyde quantification
Authors: Friedfeld Stephen , Fraser Matthew , Lancaster David , Leleux Darrin , Rehle Dirk , Tittel Frank
Published: February 2008

A one‐week in situ intercomparison campaign was completed on the Rice University campus for measuring HCHO using three different techniques, including a novel optical sensor based on difference frequency generation (DFG) operating at room temperature. Two chemical derivatization methods, 2,4‐dinitrophenylhydrazine (DNPH) and o‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine (PFBHA), were deployed during the daylight hours for three‐ to four‐hour time‐integrated samples. A real‐time optical sensor based on laser absorption spectroscopy was operated simultaneously, including nighttime hours. This tunable spectroscopic source based on difference frequency mixing of two fiber‐amplified diode lasers in periodically poled LiNbO3 (PPLN) was operated at 3.5315 µm (2831.64 cm−1) to access a strong HCHO ro‐vibrational transition free of interferences from other species. The results showed a bias of −1.7 and −1.2 ppbv and a gross error of 2.6 and 1.5 ppbv for DNPH and PFBHA measurements, respectively, compared with DFG measurements. These results validate the DFG sensor for time‐resolved measurements of HCHO in urban areas.
A multiyear intercomparison of wet troposphere corrections from TOPEX/Poseidon, ERS‐1 and ERS‐2 Microwave Radiometers and the European Centre for Medium‐Range Weather Forecasts model
Authors: Urban T. J. , Pekker T. , Tapley B. D. , Kruizinga G. L. , Shum C. K.
Published: February 2008

Wet troposphere corrections to altimeter measurements calculated from the TOPEX/Poseidon (T/P) Microwave Radiometer (TMR) and the ERS‐1 and ERS‐2 Microwave Radiometers (EMR1 and EMR2) are compared to each other and to European Centre for Medium‐Range Weather Forecasts (ECMWF) model data. The most recently published correction algorithm for the EMR1 data [Stum et al., 1998] is applied. The suggested drift correction for TMR data [Keihm et al., 1998, 2000] is also evaluated. The corrected EMR1 data (1991–1996) produce a global (to ±66° the T/P latitude range) long‐term mean wet troposphere correction 6 and 13 mm lower than TMR and ECMWF, respectively. The EMR2 data (1995–1999) yield a mean wet troposphere correction 2 and 9 mm lower than TMR and ECMWF, respectively. After removing mean differences all three microwave radiometers reproduce similar long‐term zonal wet troposphere corrections compared to the ECMWF model (10–14 mm rms) and to each other (5–9 mm rms) with some zonally periodic differences, most <10 mm. The ECMWF model shows variations compared to the radiometers of over 30 mm before 1995, about 20–30 mm from 1995 to 1997, and up to 20 mm from 1998 to 1999. The intersatellite differences include a latitudinally dependent annual signal, reaching 10 mm in amplitude. Before correcting for the TMR drift there exists a global relative TMR‐EMR1 drift of −1.6±0.4 mm y−1, from 1992 to 1996. After correcting for the TMR drift the TMR‐EMR1 trend is reduced to −0.4±0.2 mm y−1, supporting the TMR drift correction. The TMR‐EMR2 trend changes sign (direction) after an anomaly that occurred in one of the EMR2 brightness temperatures during June 1996. Before the anomaly, with (without) the TMR correction the relative TMR‐EMR2 trend is −3.0±1.9 (−4.0±2.1) mm y−1, again supporting the TMR drift correction. After the anomaly, through 1997 the TMR‐EMR trend is 3.7±1.2 mm y−1, and from 1998 to 1999 it is 0.8±0.6 mm y−1.
Surface wind‐stress threshold for glacial Atlantic overturning
Authors: Montoya Marisa , Levermann Anders
Published: February 2008

Using a coupled model of intermediate complexity the sensitivity of the last glacial maximum (LGM) Atlantic meridional overturning circulation (AMOC) to the strength of surface wind‐stress is investigated. A threshold is found below which North Atlantic deep water formation (DWF) takes place south of Greenland and the AMOC is relatively weak. Above this threshold, DWF occurs north of the Greenland‐Scotland ridge, leading to a vigorous AMOC. This nonlinear behavior is explained through enhanced salt transport by the wind‐driven gyre circulation and the overturning itself. Both pattern and magnitude of the Nordic Sea's temperature difference between strong and weak AMOC states are consistent with those reconstructed for abrupt climate changes of the last glacial period. Our results thus point to a potentially relevant role of surface winds in these phenomena.
Deep structure and structural inversion along the central California Continental Margin from edge seismic profile RU‐3
Authors: McIntosh K. D. , Reed D. L. , Silver E. A. , Meltzer A. S.
Published: February 2008

Deep‐penetration seismic reflection profile RU‐3 crosses the central California continental margin revealing a subducted oceanic plate, a modified accretionary prism, and complex structures of the overlying sedimentary basins. This structural framework was established by subduction processes during Paleogene and earlier time and subsequently was modified by Neogene transform motion combined with apparent components of extension and compression. Subducted rocks are indicated by deep, gently dipping reflectors that extend beneath the continental margin for at least 38 km at a depth of about 15 km. We interpret the subducted crust as either a part of the Pacific plate or, more likely, a subducted fragment derived from the Farallon plate. A set of more steeply dipping, deep events may indicate faulting within the subducted plate or its boundary with a no‐slab zone. The overlying, largely nonreflective layer of accreted material rapidly reaches 10 km in thickness landward of the paleotrench and increases to 15 km in thickness near the coast. The Santa Lucia Basin, landward of the steep continental slope, originated as a slope basin during Paleogene subduction. The lower strata of this basin were deposited onto and partially incorporated into the accretionary complex. The offshore Santa Maria Basin exhibits a variety of compressional structures that formed in the last 3–5 m.y. and whose locations correspond to an earlier framework of extensional faults. Structural inversion has occurred in Miocene depocenters adjacent to the Santa Lucia Bank fault and at the Queenie structure. Miocene and lower Pliocene strata also thicken toward the Hosgri fault zone where subsequent compression is characterized by low‐angle thrusts and folding.
Mesoscale current variability in the Otranto Straits, Adriatic Sea
Authors: Kastanos Nikos , Ferentinos George
Published: February 2008

The study of satellite infrared images and analysis of current measurements in the Strait of Otranto using time and space correlation and power spectra tecniques, has shown the existence of a horizontal velocity shear zone, formed between a northward and a southward flowing current. The shear zone extends from the surface to the seabed along an inclined plane. Time and space scales in the northerly and southerly flowing currents are much larger than those in the shear zone. In the unstable flow field of the shear zone, mesoscale eddies and strong near‐inertial waves are generated. These advective phenomena seem to be the result of mainly barotropic instability processes. The near‐inertial waves are found to be trapped inside the shear zone, and their frequency is found to be affected by the passage of the energy containing eddies and the background flow field vorticity.
Calculation of aerosol backscatter from airborne continuous wave focused CO2 Doppler lidar measurements: 2. Algorithm performance
Authors: Rothermel Jeffry , Bowdle David A. , Vaughan J. Michael
Published: February 2008

The performance of an algorithm to calculate aerosol backscatter coefficients, from measurements with an airborne continuous wave focused CO2 Doppler lidar, is described relative to flight hardware settings and operating characteristics, and theoretical considerations. The algorithm (described in paper 1) is used to analyze measurements by the Laser True Airspeed System (LATAS), operated by the Royal Signals and Radar Establishment (RSRE) and Royal Aircraft Establishment (RAE), United Kingdom. Under optimum signal conditions, backscatter signals are located unambiguously and the backscatter coefficients are accurately determined. Under marginal or subthreshold conditions, with a degraded system sensitivity, false alarms (mistaking noise for signal) occur. Parametric studies show that the false alarm rate under these conditions depends on the search window size and the signal‐to‐noise ratio (SNR) threshold for valid signals. Carefully selected diagnostic parameters are used to estimate the combined sensitivity of the flight hardware system and algorithm. Less than 1% of backscatter measurements for flights over approximately 5 years have been found to be below the measurement sensitivity when the LATAS flight hardware controls were set for optimum sensitivity.
Atmospheric and precipitation chemistry over the North Atlantic Ocean: Shipboard results, April–May 1984
Authors: Church T. M. , Tramontano J. M. , Whelpdale D. M. , Andreae M. O. , Galloway J. N. , Keene W. C. , Knap A. H. , Tokos J.
Published: February 2008

During a North Atlantic cruise from Dakar, Senegal, to Woods Hole, Massachusetts (April 14–May 11, 1984), crossing the area of 14°–48°N; 17°–70°W, we collected atmospheric aerosols (C, N, S species), gases (SO4, HNO3, dimethyl sulfide (DMS), synthetic organic chemicals), and precipitation (major inorganic/organic ions, trace metals). Air masses that had not contacted land for over 5 days had a composition close to that from the remote marine atmosphere. Oxidation of biogenic DMS to SO4= aerosol accounted for most nss‐SO4= in these air masses. Air masses that had transected densely populated North America (in the westerlies) or the Mediterranean/North Africa ( in the easterlies) within 2–5 days of being sampled over the North Atlantic were enriched in acid precursor compounds and synthetic hydrocarbons relative to air that had spent longer over the North Atlantic. Strong acids and trace metals were also elevated in precipitation. Air masses that had transected regions of strong emissions within the preceding 2 days had concentrations of atmospheric pollutants approaching those typically found in continental air masses. More frequent storm tracks between the Icelandic low and the Bermuda high favored transport of North American emissions northeasterly, toward Europe. Trajectory analyses suggested that air masses sampled off the northwest African coast had passed over the Mediterranean. Composition of the aerosol and precipitation of these air masses was also indicative of continental emissions, including biomass and petroleum burning. Transport and deposition of continental emissions to the North Atlantic were significantly influencing surface atmospheric and oceanic chemistry of this region.
Theoretical interpretation of N2O5 measurements
Authors: Toumi R. , Pyle J. A. , Webster C. R. , May R. D.
Published: February 2008

Recent measurements by Webster et al. [1990] have confirmed quantitatively the chemistry controlling the night‐time decay of NO2. Simple equations describing the night‐time behaviour of NO2 and N2O5 are presented here. With measurements of the night‐time ozone and NO2 concentrations, these equations can be used to predict the amount of N2O5 produced at any time during the night. In this way the N2O5 night‐time emission measurement of Roscoe [1982], Kunde et al. [1988] and sunrise measurements of the ATMOS experiment [Rinsland et al., 1989] are all used to test theory. The measurements are found to be both self consistent and confirm our understanding of night‐time NO2 conversion to N2O5. The variation of N2O5 by a factor of two between measurements is found to be consistent with theory.
Methanesulfonic acid in south polar snow layers: A record of strong El Nino?
Authors: Legrand M. , Saigne C. Feniet
Published: February 2008

In this paper we present a detailed study of methanesulfonic acid (MSA) and non‐sea‐salt sulfate (nss‐SO4) content in recent south polar precipitation. These two species are major oxidation products of dimethylsulfide (DMS) which is mainly produced by marine biota. The nss‐SO4 content of south polar snow layers deposited over the 1922–1984 time period remained rather stable except short‐term increases after the Mt Agung (1963) and the El Chichon (1982) eruptions. At the opposite, the MSA profile shows over the same time period several sporadic, 0.5 to 2 years, increases (2 to 10 times background level). Taking into account an uncertainty of 1–3 years in the dating of snow layers, all these MSA events seem to be correlated to major ENSO (El Nino‐Southern oscillation) events having occured over the last sixty years (1925–26, 1941, 1957–58, 1972–73 and 1982–83). The relatively high MSA/nssSO4 weight ratios (R) observed in the corresponding snow layers suggest that these events reflect enhanced DMS emissions from the antarctic ocean. This suggested connection between ENSO and high DMS marine emissions at high southern latitudes is discussed in terms of atmospheric and oceanic circulation.
Space debris and micrometeorite events experienced by WL Experiment 701 in prolonged low Earth orbit
Authors: McKnight D. S. , Dueber R. E. , Taylor E. W.
Published: February 2008

Air Force Systems Command Weapons Laboratory experiment 701 (Space Environment Effects on Fiber Optic Systems) was housed aboard the Long Duration Exposure Facility and placed into orbit on April 6, 1984, by the shuttle Challenger. It was retrieved 69 months later by the shuttle Columbia on January 12, 1990. During this period in orbit, the experiment experienced numerous debris or micrometeorite impacts. Impact flux values, crater characteristics, and shock phenomena on the experiment's space‐exposed surfaces were observed to be similar to returned materials of the Solar Max satellite. This paper presents the analysis of preliminary data, describes data reduction techniques, and outlines areas of future study.
Low‐frequency oscillations associated with a polar cap auroral arc: Local spectral density estimation
Authors: Walker D. N. , Chaturvedi P. K. , Singh M. , Rodriguez P. , Siefring C. L. , Baumback M. M.
Published: February 2008

Enhanced low‐frequency electrostatic oscillations measured from a rocket in the high‐latitude upper F region during the crossing of a polar cap auroral arc are analyzed using local spectral analysis techniques. The turbulent spectra were reduced from measurements made by Langmuir probes whose orientation remained approximately perpendicular to B throughout the flight. The increased low‐frequency turbulence appears at an altitude of 400 km, coincident with electrostatic analyzer indications of increased energetic particle flux. Langmuir probe measurements simultaneously show an increasing temperature and generally decreasing, although irregular, electron density profiles. Electrostatic wave data are analyzed using cross‐correlation analysis to determine phase shift; local wave number approximations provide an estimate of the plasma wave spectral density, S(k, ω). Theoretical expectations for threshold excitation and growth rates of possible instabilities in a two‐component high‐latitude F region ionosphere are investigated. The most likely source for the measured oscillations appears to be excitation of a collisionless electrostatic ion cyclotron mode.
Is System IV independent of System III?
Authors: Yang Y. S. , Dessler A. J. , Sandel B. R.
Published: February 2008

We have investigated the relationship between System III modulation of several Jovian phenomena and their modulation at the 3% longer System IV period. Because these same phenomena also show modulation with a 14.1‐day period, there are two possible but physically dissimilar causes of the System IV modulation. The first possibility is that System IV modulation is a separate phenomenon, independent of System III. Alternatively, if System III were amplitude modulated with a 14.1‐day period, then the 10.2‐hour System IV period would be a sideband of System III, and there would be a second sideband with a period of 9.64 hours. Neither the 9.64‐hour nor the 14.1‐day periods appear in periodogram analyses of EUV data from Voyager 2 and narrow‐band kilometric data from Voyager 1 and 2. Furthermore, we show that System IV modulation cannot be caused by beats or harmonics of periods of System III, Earth's rotation, and Io's revolution. We therefore conclude that System IV is independent of System III.
About the origin of peaks in the spectrum of inner belt electrons
Authors: Pinto O. , Pinto I. R. C. A. , Gonzalez W. D. , Gonzalez A. L. C.
Published: February 2008

A power spectral analysis of geomagnetic data between June and November 1982 from Vassouras, a low‐latitude observatory located in the South Atlantic Magnetic Anomaly (SAMA), is carried out in order to investigate the origin of multiple peaks commonly observed in the energetic electron spectra in the inner magnetosphere. Comparison with energetic electron observations made by the low‐altitude satellite S81‐1 during the same time interval [Datlowe et al., 1985] indicates that even if the peaks are due to a quasi‐resonance process as Cladis [1966] has suggested, whereby energetic electrons are accelerated and transported radially as a result of magnetic fluctuations with periods comparable to their azimuthal drift periods, the driver of such magnetic fluctuations is not the ionospheric current in the equatorial electrojet, modulated by electron precipitation in the SAMA region, such as Cladis [1966] proposed. We suggest that the source of drift‐resonant magnetic fluctuations, if they exist, must instead be sought in the solar wind. Otherwise, the drift‐resonant mechanism cannot be viable.
A dynamic analysis of the radiation excitation from the activation of a current collecting system in space
Authors: Wang J. , Hastings D. E.
Published: February 2008

Current collecting systems moving in the ionosphere will induce electromagnetic wave radiation. The commonly used static analysis is incapable of studying the situation when such systems undergo transient processes. A dynamic analysis has been developed, and the radiation excitation processes are studied. This dynamic analysis is applied to study the temporal wave radiation from the activation of current collecting systems in space. The global scale electrodynamic interactions between a space‐station‐like structure and the ionospheric plasma are studied. The temporal evolution and spatial propagation of the electric wave field after the activation are described. The wave excitations by tethered systems are also studied. The dependencies of the temporal Alfvén wave and lower hybrid wave radiation on the activation time and the space system structure are discussed. It is shown that the characteristics of wave radiation are determined by the matching of two sets of characteristic frequencies, and a rapid change in the current collection can give rise to substantial transient radiation interference. The limitations of the static and linear analysis are examined, and the condition under which the static assumption is valid is obtained.
On the problem of the Martian atmosphere dissipation: Phobos: 2 TAUS Spectrometer results
Authors: Verigin M. I. , Gringauz K. I. , Kotova G. A. , Shutte N. M. , Rosenbauer H. , Livi S. , Richter A. K. , Riedler W. , Schwingenschuh K. , Szego K.
Published: February 2008

The measurements of proton spectra obtained by the TAUS spectrometer on board the Phobos 2 spacecraft in elliptical orbits near Mars are presented. A strong deceleration of the solar wind upstream of the Martian bow shock was revealed. It can be caused by the mass loading of the plasma flow by ions originating from the hot oxygen/hydrogen corona of Mars and/or by protons specularly reflected from the bow shock. In the first case the deceleration of the solar wind by about 100 km/s implies that the hot oxygen corona of Mars could be several times denser than it was anticipated to be (at least during the observation period that was close to solar cycle maximum). Furthermore, the loss of planetary oxygen through the corona appears to be the main process of oxygen loss from Mars. The upper limit of loss rate for such a process is determined to be 1026 oxygen atoms or 2.5 kg of oxygen per second.
Alfven waves and associated energetic ions downstream from Uranus
Authors: Zhang Ming , Belcher John W. , Richardson John D. , Smith Charles W.
Published: February 2008

We report the observation of low‐frequency waves in the solar wind downstream from Uranus. These waves are observed by the Voyager spacecraft for more than 2 weeks after the encounter with Uranus and are present during this period whenever the interplanetary magnetic field is oriented such that the field lines intersect the Uranian bow shock. The magnetic field and velocity components transverse to the background field are strongly correlated, consistent with the interpretation that these waves are Alfvenic and/or fast‐mode waves. The waves have a spacecraft frame frequency of about 10−3 Hz, and when first observed near the bow shock have an amplitude comparable to the background field. As the spacecraft moves farther from Uranus, the amplitude decays. The waves appear to propagate along the magnetic field lines outward from Uranus and are right‐hand polarized. Theory suggests that these waves are generated in the upstream region by a resonant instability with a proton beam streaming along the magnetic field lines. The solar wind subsequently carries these waves downstream to the spacecraft location. These waves are associated with the presence of energetic (>28 keV) ions observed by the low‐energy charged particle instrument. These ions appear two days after the start of the wave activity and occur thereafter whenever the Alfven waves occur, increasing in intensity away from Uranus. The ions are argued to originate in the Uranian magnetosphere, but pitch‐angle scattering in the upstream region is required to bring them downstream to the spacecraft location.
Kilometric radio waves generated along auroral field lines observed by ground facilities: A theoretical model
Authors: Ziebell L. F. , Wu C. S. , Yoon Peter H.
Published: February 2008

A theory of generation of radio waves observed by ground‐based facilities in the frequency range 150–700 kHz is discussed. This work is a continuation of an earlier discussion (Wu et al., 1989) in which it was proposed that the trapped electrons along the auroral field lines can lead to a cyclotron instability which amplifies the whistler waves observed at ground level. The objective of the present study is to investigate the propagation effect on the wave amplification and to examine whether the proposed mechanism is indeed viable.
Permeability of core samples from Cajon Pass Scientific Drill Hole: Results from 2100 to 3500 m depth
Authors: Morrow C. A. , Byerlee J. D.
Published: February 2008

Hydrologic rock properties are important to the debate about the state of stress and heat flow regime of the San Andreas fault. In particular, these properties are pertinent to whether frictional heat generated by high shear stresses can be convected away by circulating ground water, thus accounting for the absence of a measurable heat flow anomaly across the fault. To help resolve this debate, we have conducted laboratory permeability measurements on intact core samples from the Cajon Pass drill hole extracted from depths between 2100 and 3500 m. These rocks were all crystalline in nature, including granodiorites, tonalites, monzogranites and gneisses. Confining and pore pressures matched the in situ pressures for each depth, and distilled water was used as the permeating medium. Permeabilities ranged from 10−22 to 10−19 m2 for effective pressures between 36 and 56 MPa. In general, the permeability values decreased with depth in a manner consistent with earlier studies of rocks between 500 and 2100 m in the drill hole. Petrographic observations indicate that repeated episodes of crack healing and sealing are the mechanisms responsible for the extremely low permeability values. Secondary minerals that seal the microfractures include abundant laumontite, calcite, quartz, chlorite, and other phyllosilicates. The permeability results suggest that water circulation in the vicinity of the drill hole must be restricted to major fracture zones, with minimal exchange of water in more intact regions. This finding is consistent with geochemical evidence of little mixing of the pore waters sampled from different sections of the borehole. The results also suggest that massive water circulation through the bulk of the rock is unlikely as a mechanism for obscuring the heat flow anomaly that would be expected if shear stresses along the San Andreas fault are high.
Impedance inversion experiments with simulated data
Authors: Sarwar A. K. M.
Published: February 2008

Acoustic impedance inversion experiments using simulated seismic data have been presented applying the Gopinath‐Sondhi (GS) method. The purpose is to invert synthetic seismograms to reconstruct impedance profiles. Seismic data have been perturbed by white noise and a band‐limited Butterworth filter. The effect of the dc component of impulse response on the impedance reconstruction has been investigated. The inversion method can be applied for both onshore and offshore explorations due to a similarity between particle velocity and pressure convolution equations. Computer model experiments show that the method is promising for inverting seismograms contaminated with white noise. The study also shows a problem for inversion due to the missing low frequencies including the dc.
Time‐dependent models of vertical deformation for the Yellowstone‐Hebgen Lake Region, 1923–1987
Authors: Holdahl Sandford R. , Dzurisin Daniel
Published: February 2008

Results of repeated levelings have been used to determine the patterns of elevation change associated with the Yellowstone caldera, and apparent viscoelastic rebound following the magnitude 7.3 earthquake near Hebgen Lake in 1959. Models with alternative treatments for nonuniform height change were utilized. Area‐wide levelings in 1923, 1975–1977, and 1987 in Yellowstone National Park allowed derivation of uplift velocities for the periods before and after 1976. Maximum uplift velocity for the earlier period was 14 mm/yr, causing 90 cm of height change from 1923 to 1984. Recent annual levelings on the east side of the caldera show a cessation of uplift in 1984–85, and the beginning of rapid subsidence; −19 mm/yr from 1985 to 1989. The long‐term uplift correlates closely with the caldera rim. After structuring the leveling observations to be insensitive to the 1959 coseismic deformation (−6 m) at Hebgen Lake, the broader spatial pattern of postseismic rebound was resolved, showing uplift of at least 32 cm. As a group, the relevelings converging at nearby West Yellowstone were accomplished at various times, which allowed selection of a best model to fit the temporal character of postseismic motion. The preferred model has a 2‐year decay period indicating that uplift stopped by 1970. Supplementary indications of the uplift near Hebgen Lake were obtained by comparing Global Positioning System data to earlier levelings, facilitated by a new precise geoid by D. G. Milbert and W. T. Dewhurst (submitted manuscript, 1990).
Surface wave propagation in a half‐space with a single set of regular joints
Authors: Murakami H.
Published: February 2008

The dispersion of surface waves is investigated herein for a half‐space of a jointed rock medium with a single set of regular joints with an arbitrary angle between the free surface and the joint plane. The intact rock layers are assumed to be linearly elastic, and the joint response is prescribed by linear traction‐slip relations. Since the exact surface wave analysis of the jointed half‐space is difficult due to a multitude of joints in the domain of the analysis, a high‐order homogenization model, proposed by Murakami and Hegemier (1989) is adopted. The model incorporates accurately the harmonic wave dispersion in a jointed full space and is capable of predicting the surface wave propagation down to the wavelength of the order of approximately two intact layer thicknesses. For a jointed half‐space with the angle between the joint plane and the free surface less than approximately 30° the surface wave phase velocity spectra is found to exhibit dramatic dispersion. The surface wave velocity increases as much as 87% for the angle 0° and 39% for the angle 30° as the wave number or frequency increases. This dispersion characteristic of the surface wave is due to the dispersion of plane shear waves in a jointed full space in the waveguide direction. The effect of surface wave dispersion in the time domain has been investigated by solving Lamb's problem under plane strain. A jointed half‐space with joint planes parallel to the free surface has been analyzed by the finite element method. The time history of velocity and displacement at different observation points exhibits spreading of waves due to dispersion. Surface wave in a half space covered by a solid layer with lower shear wave velocity exhibits the phase velocity reduction with the wave number. It is interesting to note that the surface wave dispersion observed in jointed half‐spaces with joint angle between 0° and 30° exhibits the opposite trend.
The effects of porosity on fault reactivation in sandstones
Authors: Scott Thurman E. , Nielsen K. C.
Published: February 2008

Reactivation of a preexisting weakness in a rock (such as joints or fault surfaces) is governed by the relationship between the coefficients of sliding friction and internal friction and the orientation of the superimposed stress field. Triaxial compression and sliding friction tests were conducted on sandstones with porosities of 6%, 14%, 20%, 21%, 22%, and 28% at confining pressures of 0.1, 5, 10, 30, 50, 70, and 90 MPa under saturated but drained conditions. Results of these tests indicate that porosity has a minimal effect on the coefficient of sliding friction but that the Mohr failure envelopes are greatly affected by porosity. These data are used to plot limiting theta angles (Θa and Θb) versus confining pressure for each sandstone which outline “stability” fields for reactivation of a preexisting surface. Plots for the three lowest porosity sandstones (<20%) have similar patterns of limiting angles with increasing confining pressure causing only slight decreases in theta angles from 4–47° at 5 MPa to 7–44° at 90 MPa. These sandstones exhibit either reactivation of the preexisting surface or brittle shear failure on a more favorably oriented fracture surface. High‐porosity sandstones (>20%) have limiting angles which are greatly affected by confining pressure. These sandstones exhibit four types of deformational behavior: reactivation of preexisting surface, crosscutting shear failure on a new fracture surface, brittle‐ductile transitional behavior, or ductile cataclastic flow. The stability field diagrams exhibit a decrease in the range of limiting angles with increasing confining pressure to a singular value at the brittle‐ductile boundary. Tests conducted on 35° and 45° sawcut cores over the same experimental conditions verify the deformational behavior outlined by the stability field plots.
Ash flows and epithermal features of the Creede Caldera in Colorado: FEasibility of mapping with seismic techniques
Authors: Marcotte Denis , Pesant André
Published: February 2008

Could a seismic survey recognize the different lithologies of the Creede caldera in Colorado? To address this question, petrography and seismic properties of 46 tuff samples were analyzed with linear discriminant analysis and nonhierarchical clustering techniques. Results show that the lithological units mapped in the area can be characterized with petrographical variables (thin section point‐count) but not recognized with seismic velocity, bulk density, and porosity variables. Seismic data are equally ineffective at recognizing samples that share common mineralogy across units. However, seismic data can recognize groups of samples that share similar porosity. We conclude that the study of variations in the porosity is the only feasible purpose of a seismic survey in an area similar to the one where our samples came from. Because of expected variations in porosity within cooling units of ash flow deposits, it may be relevant to run a seismic survey in the northern mining district of Creede to map the cooling history of the volcanic pile.