bluuebunny/crossref_metadata_2025 huggingface dataset:
Noninvasive Vascular Testing—A 35‐Year Reflection
Authors: Lavenson George S.
Published: April 2005

Noninvasive vascular testing has made a major contribution to the care of vascular surgery patients. This article a reflection on a 35‐year corroborative association with Doctor Norman Rich, during which many of the advances in noninvasive vascular testing have been witnessed and effected. I served my vascular surgery fellowship under Doctor Rich in 1967–68 at Walter Reed Army Hospital. The only noninvasive vascular equipment then was a pencil probe Doppler. The value of the Doppler in the management of peripheral vascular disease that year and in determining limb viability in combat surgery in Vietnam the following year was established, and both experiences were published. Later, Doctor Rich established the annual Military Vascular Surgery Meeting and was appointed as the first Chair of the Department of Surgery at the Uniformed Services University for Health Sciences (USU). I entered private practice in Central California in 1976, and ultrasonic imaging was developed which allowed noninvasive examination of the carotid arteries. I then developed a protocol to screen for the three silent, immediate causes of stroke, employing a “a quick carotid scan” for carotid artery disease, a lead II rhythm strip for atrial fibrillation, and blood pressure determination for hypertension so that these common causes of strokes could be recognized and treated, and potentially prevent the majority of strokes. My association with USU, Doctor Rich, and others involved proved instrumental in initiating implementation of stroke prevention screening. The structure established at USU provides a means of establishing the protocol nationally. Noninvasive vascular testing is an addition to Medical Science that has led to significant improvements in individual patient care and that has the potential of allowing a major reduction in death and disability from stroke and other vascular diseases. Throughout a 35‐year collaborative association with Doctor Norman M. Rich, I have witnessed and developed many of these advances. These contributions to noninvasive vascular testing reflect the value of our collaboration.
Abdominal War Wounds—Experiences from Red Cross Field Hospitals
Authors: Leppäniemi Ari K.
Published: April 2005

The traditional approach to abdominal war wounds consists of triage, eche‐loned care, and mandatory laparotomy for penetrating abdominal injuries, and it remains valid in modern conventional wars with well‐organized evacuation and surgical services. Expectant management of abdominal casualties can be considered under difficult circumstances with a high influx of patients exhausting the available resources. This can occur in regional conflicts associated with mass movements of people and with collapsed infrastructure. While always combined with adequate fluid resuscitation, antibiotic treatment, and other supportive care, the expectant approach in patients with penetrating abdominal injuries could be indicated for asymptomatic patients with multiple fragment wounds or for patients presenting several days post‐injury in good condition. The focus of surgical resources and competence should be on the majority of patients with intestinal perforation only, who need surgery to save life—but not necessarily on an urgent basis—and who have a good chance of survival. The limited availability of blood products to correct blood loss and coagulation factor deficiencies, and the lack of sophisticated monitoring of hemodynamic variables that call into question the value of a damage‐control approach for the most severely injured. Even if the bleeding could be temporarily controlled, the subsequent need for adequate resuscitation before returning the patient to the operating room could be difficult to achieve and would result in incompletely resuscitated patients being reoperated while acidotic, coagulopathic, and even hypothermic. Perhaps, in mass casualty situations these patients should be recognized during triage or at least early during operation, and aggressive surgery should be replaced with adequate expectant management with sedation and analgesics.
Cardiopulmonary Assessment: Is Improvement Needed?
Authors: Van De Water Joseph M. , Dalton Martin L. , Parish David C. , Vogel Robert L. , Beatty John C. , Adeniyi Said O.
Published: April 2005

Clinical parameters alone have repeatedly been proven unreliable in assessing cardiopulmonary status, especially in hemodynamically unstable patients. To learn if we had a diagnostic problem in our hospital, we compared physician assessment of cardiac index (CI) and thoracic fluid content (TFC) to values obtained using impedance cardiography (ICG). We selected the newest available ICG monitor, the BioZ, which employs this noninvasive technology. For CI measurements we have shown it to be equivalent to thermodilution and to be more reproducible (variability: 6.3% vs. 24.7%). Physician assessment of CI and TFC (high, normal, or low) was compared to the BioZ monitor’s results in 186 patients, considered to be hemodynamically unstable, from the emergency room, the intensive care units, and the floors. Normal values were defined for CI (2.5–4.2 L/min m2) and for TFC (males: 30–50 kohm−1 and females: 21–37 kohm−1). The concordance between physician assessment and the BioZ was 51% for CI with Kappa of 0.14 and 58% for TFC with Kappa of 0.19. Attendings did slightly better than the surgical residents with CI (52% vs. 48%) but slightly worse with TFC (57% vs. 61%). The potentially serious conditions of low CI and high TFC were misdiagnosed 42% and 46% of the time, respectively, by all physicians. Analysis of the data revealed that physician use of clinically available objective hemodynamic data, such as heart rate, blood pressure, and pulse pressure index, would not have been helpful. Furthermore, assistance from the pulmonary artery catheter (PAC) is often not available in our hospital, which has experienced a 90% decrease in its utilization over the past six years. Considering the increasing acuity of our aging patient population, accurate assessment of cardiopulmonary status is needed. The use of ICG could be a valuable addition to the physician’s armamentarium.
Multi-site Management of Library and Information Services
Authors: Miskin Christine
Published: April 2005

The following articles were written by law librarians employed by a variety of organisations in response to a questionnaire sent out by the Editorial Board. The aim of this brief survey was to try and find out what the key issues are facing librarians who operate in such situations. We were unable to get a contribution from an academic library operating a multi-site system. Some of the articles have followed the format of the questions posed in the survey and others are more discursive, but the Editorial Board hopes that readers will find useful nuggets of information in these different accounts. They certainly offer interesting organisational schemas.
Die Wundt-Bühler-Kontroverse aus der Sicht der heutigen kognitiven Psychologie
Authors: Massen Cristina , Bredenkamp Jürgen
Published: April 2005

Zusammenfassung. In der Wundt-Bühler-Kontroverse (1907-1908) geht es um die auch für die heutige Denkpsychologie noch bedeutsame Frage, ob der Selbstbericht von Probanden über die eigenen Denkprozesse als wissenschaftliche Methode der Datengewinnung akzeptiert werden kann, wie vor etwa einem Jahrhundert von Karl Bühler vertreten, oder auf Grund von mangelnder Validität abgelehnt werden sollte, wie von Wilhelm Wundt gefordert. In dem vorliegenden Beitrag wird diese Kontroverse aufgegriffen und anhand neuerer empirischer Befunde diskutiert. Besonderes Augenmerk wird dabei auf die Reaktivität und Veridikalität von Berichten über die Denktätigkeit sowie auf das Problem möglicher unbewusster Denkprozesse gelegt. Unter Berücksichtigung der neueren Befundlage gelangen wir zu dem Schluss, dass viel für die einst von Wilhelm Wundt vertretene Position spricht.
Evaluation von Beurteilungen:
Authors: Eckes Thomas
Published: April 2005

Zusammenfassung. Auf der Grundlage des Multifacetten-Rasch-Modells ( Linacre, 1989 ; Linacre & Wright, 2002 ) wird eine Systematik von Methoden präsentiert, die eine detaillierte Untersuchung der psychometrischen Qualität von Beurteilungen in verschiedenen Anwendungsbereichen (z.B. bei Leistungs- oder Eignungsbeurteilungen) erlauben. Wesentliche Ziele sind: (a) Messung der Strenge der Beurteiler, der Fähigkeit der beurteilten Personen und der Schwierigkeit von Aufgaben und Kriterien in einem einheitlichen Bezugssystem, (b) Konstruktion fairer Leistungsmaße durch Berücksichtigung der Beurteilerstrenge sowie der Aufgaben- bzw. Kriterienschwierigkeit, (c) Erfassung der Konsistenz des Bewertungsverhaltens, (d) Prüfung weiterer Beurteilereffekte (z.B. zentrale Tendenz und Halo-Effekte), (e) Analyse von Interaktionseffekten und differenziellen Facettenfunktionen. Perspektiven für die Entwicklung und Anwendung möglichst objektiver, genauer und fairer Beurteilungsverfahren werden diskutiert.
Die Abhängigkeit der Zufriedenheit mit dem Medizinstudium von Studienzielen und ihrer Realisierbarkeit
Authors: Hiemisch Anette , Westermann Rainer , Michael Andrea
Published: April 2005

Zusammenfassung. Untersucht wird der Zusammenhang zwischen der allgemeinen Studienzufriedenheit, den Gründen für die Studienwahl sowie den Studienzielen bei Studierenden der Medizin und Zahnmedizin. 203 Studierende wurden unmittelbar zu Beginn des Studiums sowie ein weiteres Mal im zweiten Semester (N = 124) befragt. Während für die Zufriedenheit mit den Studieninhalten zu beiden Zeitpunkten die Gründe für das Medizinstudium besonders bedeutsam sind, weist für die Zufriedenheit mit den Studienbedingungen die Realisierbarkeit der Studienziele eine höhere Vorhersagekraft auf. Dies gilt besonders für den zweiten Erhebungszeitpunkt. Für die Zufriedenheit mit der Bewältigung von Studienbelastungen erweisen sich sowohl die Realisierbarkeit der Ziele auch als die Gründe bedeutsam. Vom ersten zum zweiten Erhebungszeitpunkt nimmt die Bedeutung der Realisierbarkeit der Ziele für die Zufriedenheit mit den Studienbedingungen und mit der Bewältigung der Studienbelastungen deutlich zu. Von den zu Beginn des Studiums erhobenen Prädiktoren erweisen sich besonders die Gründe für das Medizinstudium zur Vorhersage der Zufriedenheit mit den Studieninhalten im zweiten Semester als geeignet.
Spatial and temporal patterns of solar eclipses by Phobos on Mars
Authors: Bills Bruce G. , Comstock Robert L.
Published: April 2005

The spatial and temporal patterns associated with motion of the shadow of Phobos across the surface of Mars are quite different than those associated with solar eclipses on Earth. We present a simple analysis of variations in the position, velocity, size, and shape of the shadow. Simple expressions give reasonably accurate depictions of the shadow motion, which mainly consists of a subdiurnal longitude cycle and an annual latitude cycle. Over most of each year, there are an average of 3.22 shadow transits per day. The duration of the shadow transit depends on latitude. It is maximum at the equator and is then 11.8% of the orbital synodic period. As the subsolar point moves north, the shadow moves south, and vice versa. There is a narrow band, centered on the equator of Mars, within which every point is eclipsed at least once during each semiannual eclipse season. Outside that band, the density of coverage decreases slowly with increasing distance from the equator, until the limiting latitudes are reached. During epochs, like the present, when the obliquity of Mars is in excess of 21.2°, there are portions of each year during which no eclipses occur. As the obliquity increases beyond that transition value, the durations of the eclipse seasons decrease. The minimum possible eclipse season duration, expressed as a fraction of the Mars year, is the same as the maximum shadow transit duration, expressed as a fraction of the Phobos synodic period, since both ratios depend on the same geometry, which is essentially just the radius of the orbit of Phobos, compared to the radius of Mars.
Sea‐to‐air CO2 flux from 1948 to 2003: A model study
Authors: Wetzel P. , Winguth A. , Maier‐Reimer E.
Published: April 2005

Trends and variability in the ocean‐atmosphere CO2 flux and the uptake of anthropogenic CO2 are simulated for the period 1948–2003, using a biogeochemical carbon cycle model (HAMOCC5) coupled online to a global ocean general circulation model (MPI‐OM). The model is forced by daily National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data from 1948 to 2003. We find a global interannual variability of ±0.50 PgC yr−1 (2σ) which is largely dominated by ocean dynamics in the equatorial Pacific. On decadal scale, two patterns are of global importance. First, the regime shift that occurs in 1975–1977 when the modeled interannual variability of the equatorial Pacific changes from ±0.32 PgC yr−1 to ±0.23 PgC yr−1 and the mean outgasing of CO2 decreases from 0.70 PgC yr−1 to 0.58 PgC yr−1. Second, the trend that occurs in the Southern Ocean, where we find an increase of the CO2 fluxes over the full 56‐year simulation period. The flux results from stronger upwelling and deeper mixed layers which are caused by increasing wind velocities. We estimate an average CO2 flux into the ocean of 1.49 PgC yr−1 for 1980–1989 and 1.74 PgC yr−1 for 1990–1999, with extremes of 1.20 PgC yr−1 at the La Niña event in 1996 and 2.10 PgC yr−1 during the El Niño events in 1993 and 1998. Because of the rising buffer factor, the uptake of anthropogenic CO2 is slowing down in regions of shallow mixing toward the end of the simulation. Overall, about 124 Pg of anthropogenic carbon has accumulated in the model ocean until the end of 2003.
A noniterative solution of the (U‐Th)/He age equation
Authors: Meesters A. G. C. A. , Dunai T. J.
Published: April 2005

We present a direct solution of the (U‐Th)/He age equation for age that obviates the need for an iterative solution. The uncertainties of this solution are sufficiently small to allow its use as a quasi‐analytical solution of this age equation. The direct algorithm has the obvious advantage of greater simplicity. Moreover inversion algorithms for (U‐Th)/He age profiles and coupled three‐dimensional thermal‐age‐landscape models will profit from the resulting gain in computational speed.
Vertical variation of NLC particle sizes retrieved from Odin/OSIRIS limb scattering observations
Authors: von Savigny C. , Petelina S. V. , Karlsson B. , Llewellyn E. J. , Degenstein D. A. , Lloyd N. D. , Burrows J. P.
Published: April 2005

The vertical variation of noctilucent cloud (NLC) particle sizes is derived from limb scattering observations in the UV‐B spectral range performed with the Optical Spectrograph and InfraRed Imager System (OSIRIS) on the Odin satellite. The particle sizes are determined under the assumptions that NLC particles can be treated as Mie particles with a known refractive index, and that their size distribution can be approximated by a log‐normal distribution. A sample data set of 16 bright NLCs observed during the 2003 Northern Hemisphere NLC season and the 2003/2004 Southern Hemisphere NLC season was selected for this study. In almost all the cases the derived NLC particle sizes increase with decreasing altitudes. This is in agreement with the standard assumption of larger particles sedimenting out of the cloud bottom. The derived particle radii are between about 10–50 nm.
Atmospheric impact of quasiliquid layers on ice surfaces
Authors: Voss Laura F. , Henson Bryan F. , Wilson Kevin R. , Robinson Jeanne M.
Published: April 2005

We present a fully thermodynamically constrained model to calculate the thickness of the quasiliquid layer on ice surfaces and apply this model to atmospherically relevant situations to calculate the quasiliquid thickness and volume for ice aerosols and snow pack. These volumes are comparable to the liquid volumes present in a representative liquid‐droplet cloud. The pure water calculations represent conservative lower bounds to the volume possible from more complex solutions. Incorporation of solution chemistry into the model demonstrates both the effect played by impurities when studying this phenomenon and how the formation of the quasiliquid layer concentrates impurities on the ice surface.
Measured volume, heat, and salt fluxes from the Atlantic to the Arctic Mediterranean
Authors: Østerhus Svein , Turrell William R. , Jónsson Steingrímur , Hansen Bogi
Published: April 2005

The flow of warm and saline Atlantic water towards the Arctic crosses the Greenland‐Scotland Ridge in three current branches. Since the mid 1990's, extensive monitoring with quasi‐permanent moorings and regular CTD cruises has been in operation on three sections crossing the branches. Averaged over the years 1999 to 2001, values of volume, heat (relative to 0°C) and salt flux due to the total Atlantic inflow across the Greenland‐Scotland Ridge into the Nordic Seas are estimated as 8.5 Sv (1 Sv = 106 m3·s−1), 313·1012 W, and 303·106 kg·s−1. In this period, the average temperature and salinity of the Atlantic inflow were 8.5°C and 35.25, respectively. Within the observational uncertainty, we do not find any significant seasonal variation of the volume flux, but a negative correlation between the inflow flux through the Faroe‐Shetland Channel and through the other two gaps was indicated.
Global distribution of the thermospheric total mass density derived from CHAMP
Authors: Liu H. , Lühr H. , Henize V. , Köhler W.
Published: April 2005

A global distribution of the thermospheric total mass density at 400 km altitude is derived from the high‐accuracy accelerometer on board the CHAMP satellite with good temporal and spatial coverage. It shows two interesting features. One is the anomalous distribution at low latitudes. Instead of maximizing at the dayside equator, the thermospheric density shows maxima at about 20°–25° geomagnetic latitude on both sides of the equator between 10 and 20 magnetic local time. This latitudinal distribution resembles fairly well the equatorial ionization anomaly, thus indicating strong magnetic control of the thermospheric mass density via ionosphere‐thermosphere coupling. The thermospheric density shows a secondary maximum at the nightside equator shortly before midnight, in reminiscence of the well‐known thermospheric midnight temperature maximum. Another feature to notice is that the thermospheric density is highly structured at high latitudes, with localized density enhancements possibly related to Joule/particle heating. This structure is, however, different from the cellular structure recognized by the National Center for Atmospheric Research thermosphere general circulation model at altitudes of 120–300 km. This indicates that the exact cellular structure may not necessarily extend to 400 km. A comparison between observations and the Mass Spectrometer Incoherent Scatter 1990 (MSIS90) model predictions shows that although the model describes the general structure of the observed density reasonably well, it misses the double peaks at low latitudes completely. This causes an underestimation of the total mass density by 15–20% in the crest region. At high latitudes an underestimation of 20–30% occurs in the midnight sector and the cusp region. Outside these localized areas the agreement between observations and predictions is quite good, with only ∼5% difference on average under quiet geomagnetic conditions.
Three‐dimensional position and shape of the bow shock and their variation with upstream Mach numbers and interplanetary magnetic field orientation
Authors: Merka J. , Szabo A. , Slavin J. A. , Peredo M.
Published: April 2005

Peredo et al. (1995) derived a frequently used three‐dimensional bow shock model parameterized by the upstream Alfvénic Mach number from the set of approximately 550 bow shock crossings provided by 17 distinct spacecraft over the period of 1963–1980. However, several studies reported some systematic biases in the bow shock model predictions. Therefore we have attempted to improve upon the bow shock model of Peredo et al. (1995) using their original data set and methodology in an effort to better understand these effects. We have performed three‐dimensional best fits to the bow shock crossings binned by the upstream Mach numbers MA, MS, and MMS and found that the best fitting surfaces were best ordered with the MA. In agreement with predictions from the magnetohydrodynamic theory, the results show that the bow shock surface expands when the MA decreases. The found dawn‐dusk asymmetry in the bow wave is consistent with previous studies only in the Geocentric Plasma Ecliptic System (GPE) coordinates but not in the Geocentric Interplanetary Medium (GIPM) coordinates which suggests that the employed data set is not comprehensive enough for resolving this asymmetry. Nor is the Mach cone asymmetry resolved in our data set (not even in the GIPM frame). We have derived two models predicting the statistical position and shape of the bow shock in the GPE or GIPM coordinates. Error analysis shows that the GPE‐based model is more accurate and applicable for MA = 3–20 except the nose region where the model underestimates the bow shock position for MA < 5. A direct comparison of the model predictions with 5870 IMP 8 bow shock crossings demonstrated high accuracy of predictions and, for the GPE‐based model, an exceptional stability of predictions even under extreme upstream conditions. Indeed, the new GPE‐based bow shock model is more accurate and equally or more stable than the Formisano (1979), Němeček and Šafránková (1991), Farris and Russell (1994), Cairns and Lyon (1995), Peredo et al. (1995), or Verigin et al. (2001) models.
Comparisons of aerosol optical depth and surface shortwave irradiance and their effect on the aerosol surface radiative forcing estimation
Authors: Kim Sang‐Woo , Jefferson Anne , Yoon Soon‐Chang , Dutton Ellsworth G. , Ogren John A. , Valero Francisco P. J. , Kim Jiyoung , Holben Brent N.
Published: April 2005

Column aerosol optical depth (AOD) and surface shortwave irradiance (SSI) measurements relevant to computation of the aerosol surface radiative forcing (ΔF) and forcing efficiency (β) were taken as part of Aerosol Characterization Experiment‐Asia (ACE‐Asia) at the Gosan surface site in Korea in April 2001. We compare the AOD and SSI derived from three different types of Sun photometers and three sets of radiometers. We also estimate the ΔF and β using two methods and quantify the observational uncertainties of these parameters. A comparison of the AOD at 500 nm shows that the three Sun photometers generally agreed within 0.014 (mean), 0.0142 (bias), and 0.0298 (root mean square) for coincident observations. Over the course of the comparison, the mean differences between the SSI measurements were 1.6, 11.7, and 10.1 Wm−2 for direct, diffuse and global irradiances, respectively. However, for both the AOD and the SSI comparisons, relatively high instantaneous differences between the instruments were apparent on days with heavy dust at the surface. The mean β and associated deviations, which were estimated by the combinations of different instrument‐derived AODs and SSIs, for simultaneous observation data at a 60° solar zenith angle are −79.50 ± 3.92 and −82.57 ± 5.70 Wm−2/τ500 for globalshaded (sum of direct and diffuse irradiances) and globalunshaded (measured by the unshaded pyranometer) irradiances, respectively. The uncertainties in β associated with uncertainties in the AOD and SSI (in parentheses) for globalshaded and globalunshaded irradiance are about 8.6% and 3.2% (10.7%), respectively. A 2% difference between the measured global irradiances for a given 9 days was translated into an uncertainty of 19% in ΔF. This difference in ΔF between instruments caused a 14% deviation in β.
Measurement of total PM2.5 mass (nonvolatile plus semivolatile) with the Filter Dynamic Measurement System tapered element oscillating microbalance monitor
Authors: Grover Brett D. , Kleinman Michael , Eatough Norman L. , Eatough Delbert J. , Hopke Philip K. , Long Russell W. , Wilson William E. , Meyer Michael B. , Ambs Jeffrey L.
Published: April 2005

Field studies have been performed in Lindon, Utah (February 2003) and Rubidoux, California (July 2003) to determine if the Rupprecht and Patashnick (R&P) Filter Dynamic Measurement System (FDMS) determines total fine particulate mass, including the semivolatile ammonium nitrate and organic material. Collocated measurements were made with the FDMS, a conventional tapered element oscillating microbalance (TEOM) monitor with a heated filter, an R&P differential TEOM monitor, the Brigham Young University (BYU) Real‐Time Total Ambient Mass Sampler (RAMS), the BYU particle concentrator‐organic sampling system (PC‐BOSS), a PM2.5 Federal Reference Method (FRM), a PM2.5 speciation sampler, an R&P continuous nitrate monitor, and two Sunset continuous carbon monitors (one to measure quartz filter‐retained particulate carbon and one to measure particulate semivolatile carbonaceous material lost from the particles on a filter during sampling). The RAMS and PC‐BOSS samplers have been shown to determine fine particulate material, including both the semivolatile and the nonvolatile components. Linear regression analysis at the Lindon site between the FDMS (X) and the PC‐BOSS (Y), and the FDMS (X) and the RAMS (Y), resulted in zero‐intercept slopes of 1.01 ± 0.06 (r2 = 0.63) and 1.00 ± 0.01 (r2 = 0.69), respectively. At the Rubidoux sampling site, linear regression analysis between the PC‐BOSS (X) and the FDMS (Y) gave a zero‐intercept slope of 0.96 ± 0.02 (r2 = 0.90). Linear regression analysis between the FDMS (X) and the RAMS (Y) resulted in a zero‐intercept slope of 0.99 ± 0.01 (r2 = 0.80). Measurements made at the two sites indicate that the FDMS and the R&P differential TEOM monitors do measure total fine particulate mass, including the semivolatile ammonium nitrate and organic material. Both the heated TEOM monitor and PM2.5 FRM did not measure the semivolatile material. The difference between the FDMS and a heated TEOM monitor was explained by the semivolatile ammonium nitrate and organic material measured by the various chemical composition monitors.
Cloud condensation nucleus activation properties of biogenic secondary organic aerosol
Authors: VanReken Timothy M. , Ng Nga L. , Flagan Richard C. , Seinfeld John H.
Published: April 2005

Organic aerosols in general and secondary organic aerosol (SOA) in particular are known to contribute significantly to the atmospheric population of cloud condensation nuclei (CCN). However, current knowledge is limited with respect to the nature of this contribution. This study presents a series of experiments wherein the potential for biogenically derived SOA to act as CCN is explored. Five compounds were studied: four monoterpenes (α‐pinene, β‐pinene, limonene, and Δ3‐carene) and one terpenoid alcohol (terpinene‐4‐ol). In each case the aerosol formation was driven by the reaction of ozone with the biogenic precursor. The SOA produced in each experiment was allowed to age for several hours, during which CCN concentrations were periodically measured at four supersaturations: S = 0.27%, 0.32%, 0.54%, and 0.80%. The calculated relationships between particle dry diameter and critical supersaturation were found to fall in the range of previously reported data for single‐component organic aerosols; of the systems studied, α‐pinene SOA was the least CCN active, while limonene SOA exhibited the strongest CCN activity. Interestingly, the inferred critical supersaturation of the SOA products was considerably more sensitive to particle diameter than was found in previous studies. Furthermore, the relationships between particle size and critical supersaturation for the monoterpene SOA shifted considerably over the course of the experiments, with the aerosol becoming less hygroscopic over time. These results are consistent with the progressive oligomerization of the SOA.
Large alluvial fans on Mars
Authors: Moore Jeffrey M. , Howard Alan D.
Published: April 2005

Several dozen distinct alluvial fans, 10 to ∼40 km long downslope, have been observed in highlands craters. Within a search region between 0° and 30°S, alluvial fan‐containing craters were found only between 18° and 29°S, and they all occur at around ±1 km of the MOLA‐defined Martian datum. Within the study area they are not randomly distributed but instead form three distinct clusters. Fans typically descend >1 km from where they disgorge from their alcoves. Longitudinal profiles show that their surfaces are very slightly concave with a mean slope of 2°. Many fans exhibit very long, narrow, low‐relief ridges radially oriented downslope, often branching at their distal ends, suggestive of distributaries. Morphometric data for 31 fans were derived from MOLA data and compared with terrestrial fans with high‐relief source areas, terrestrial low‐gradient alluvial ramps in inactive tectonic settings, and older Martian alluvial ramps along crater floors. The Martian alluvial fans generally fall on the same trends as the terrestrial alluvial fans, whereas the gentler Martian crater floor ramps are similar in gradient to the low‐relief terrestrial alluvial surfaces. For a given fan gradient, Martian alluvial fans generally have greater source basin relief than terrestrial fans in active tectonic settings. This suggests that the terrestrial source basins either yield coarser debris or have higher sediment concentrations than their Martian counterpoints. Martian fans (and terrestrial Basin and Range fans) have steeper gradients than the older Martian alluvial ramps (and terrestrial low‐relief alluvial surfaces), which is consistent with the construction of Martian fans from dominantly gravel‐sized sediment (rather than sand and silt). Martian fans are relatively large and of low gradient, similar to terrestrial fluvial fans rather than debris flow fans (although gravity‐scaling uncertainties make the flow regime forming Martian fans uncertain). However, evidence of bedforms accentuated by differential erosion, such as scroll bars, supports the contention that these are fluvially formed fans. Martian fans, at least those in Holden crater, apparently formed around the time of the Noachian‐Hesperian boundary. We infer that these fans formed during an episode of enhanced precipitation (probably snow) and runoff, which exhibited both sudden onset and termination.
Energetic electrons, 50 keV to 6 MeV, at geosynchronous orbit: Their responses to solar wind variations
Authors: Li Xinlin , Baker D. N. , Temerin M. , Reeves G. , Friedel R. , Shen C.
Published: April 2005

Using simultaneous measurements of the upstream solar wind and of energetic electrons at geosynchronous orbit, we analyze the response of electrons over a wide energy range, 50 keV to 6 MeV, to solar wind variations. Enhancements of energetic electron fluxes over this whole energy range are modulated by the solar wind speed and the polarity of the interplanetary magnetic field (IMF). The solar wind speed seems to be a dominant controlling parameter for electrons of all energy. Electron enhancements occur after solar wind speed enhancements with a time delay that increases with energy and that also depends on the average polarity of the IMF. The electron enhancements have a shorter delay if the IMF Bz < 0 and a longer delay if the IMF Bz > 0 during the solar wind speed enhancement. The dependence on solar wind condition varies for different energy electrons, with lower‐energy electrons (<200 keV) responding more to the polarity of the IMF and higher energy electrons (>1 MeV) responding more to the solar wind speed. The variations of different energy electrons are well correlated among themselves. For five years, 1995–1999, the correlation coefficients of 1.1–1.5 MeV electrons with lower‐energy electrons, 50–75, 105–150, 225–315, and 500–750 keV, are 0.55, 0.64, 0.74, and 0.90. This correlation is enhanced if a time shift proportional to their energy difference is included. The optimal time shifts and the corresponding correlation coefficients for the four lower energy electrons are 36, 32, 13, and 7 hours and 0.75, 0.77, 0.81, and 0.92, respectively.
Modeling the August 2002 minor warming event
Authors: Coy L. , Siskind D. E. , Eckermann S. D. , McCormack J. P. , Allen D. R. , Hogan T. F.
Published: April 2005

Hindcasts of the Southern Hemisphere minor stratospheric warming and mesospheric cooling event of August 2002, made with a new high altitude version of the Navy's operational forecast model, are compared with temperatures acquired by SABER (Sounding of the Atmosphere using Broadband Emission Radiometry). Results show realistic hemispheric evolution of both the stratospheric warming and mesospheric cooling over a 10‐day time period. Use of Rayleigh friction to model mesospheric gravity wave drag shows improvement in the upper mesosphere over a hindcast without Rayleigh friction. The limited vertical extent of the main mesospheric cooling signature disagrees with the Liu and Roble (2002) model results but is supported by SABER temperature observations (Siskind et al., 2005). Examination of 3D EP‐flux vectors over the 10‐day forecast suggests that the planetary wave responsible for the warming/cooling event originated from a horizontally localized region of the troposphere.
Solar radiation budgets in atmospheric model intercomparisons from a surface perspective
Authors: Wild Martin
Published: April 2005

Solar radiation budgets from 20 general circulation models (GCMs) participating in the second phase of the Atmospheric Model Intercomparison Project (AMIPII) are analyzed. The models largely differ in their global mean radiation budgets, particularly at the surface. Compared to a comprehensive data set of 760 worldwide‐distributed surface stations from the Global Energy Balance Archive, the models tend to overestimate the land surface insolation by 9 Wm−2 on average. The biases in the net solar fluxes at the top of atmosphere are generally smaller. This suggests that the excessive surface insolation in the GCMs is rather related to inaccurate partitioning of solar absorption between surface and atmosphere than to excessive absorption by the planet as a whole. This applies also to 13 state‐of‐the‐art GCMs participating in IPCC AR4. Uncertainties in the solar absorption by the atmospheric constituents are thus still significant in current GCMs and contribute to the large discrepancies amongst the GCM radiation budgets and their biases compared to surface observations.
Release of Bradykinin and Expression of Kinin B2 Receptors in the Brain: Role for Cell Death and Brain Edema Formation After Focal Cerebral Ischemia in Mice
Authors: Gröger Moritz , Lebesgue Diane , Pruneau Didier , Relton Jane , Kim Seong-Woong , Nussberger Jürg , Plesnila Nikolaus
Published: April 2005

Pharmacological studies using bradykinin B2 receptor antagonists suggest that bradykinin, an early mediator of inflammation and the main metabolite of the kallikrein-kinin system, is involved in secondary brain damage after cerebral ischemia. However, the time-course of bradykinin production and kinin receptor expression as well as the conclusive role of bradykinin B2 receptors for brain damage after experimental stroke have not been elucidated so far. C57/Bl6 mice were subjected to 45 mins of middle cerebral artery occlusion (MCAO) and 2, 4, 8, 24, and 48 h later brains were removed for the analysis of tissue bradykinin concentration and kinin B2 receptor mRNA and protein expression. Brain edema, infarct volume, functional outcome, and long-term survival were assessed in WT and B2−/− mice 24 h or 7 days after MCAO. Tissue bradykinin was maximally increased 12 h after ischemia (three-fold), while kinin B2 receptor mRNA upregulation peaked 24 to 48 h after MCAO (10- to 12-fold versus naïve brain tissue). Immunohistochemistry revealed that kinin B2 receptors were constitutively and widely expressed in mouse brain, were upregulated 2 h after ischemia in cells showing signs of ischemic damage, and remained upregulated in the penumbra up to 24 h after ischemia. B2−/− mice had improved motor function ( P<0.05), smaller infarct volumes (–38%; P<0.01), developed less brain edema (–87%; P<0.05), and survived longer ( P<0.01) as compared with wild-type controls. The current results show that bradykinin is produced in the brain, kinin B2 receptors are upregulated on dying cells, and B2 receptors are involved in cell death and brain edema formation after experimental stroke.
Activation of the PI3-K/Akt Pathway Mediates cGMP Enhanced-Neurogenesis in the Adult Progenitor Cells Derived from the Subventricular Zone
Authors: Wang Lei , Zhang Zheng Gang , Zhang Rui Lan , Chopp Michael
Published: April 2005

The intracellular mechanisms that regulate neurogenesis remain unclear. Using neurospheres isolated from the subventricular zone (SVZ) of the adult rat, we investigated the effect of cyclic guanosine monophosphate (cGMP) and its signaling pathway on the induction of neurogenesis. Neurospheres expressed phosphodiesterase 5 (PDE5) and treatment of neurospheres with Sildenafil, a specific inhibitor of PDE5, significantly increased cGMP levels and neurogenesis. In addition, incubation of neurospheres with Sildenafil significantly phosphorylated Akt, which was associated with an increase of phosphorylation of glycogen synthase kinase 3 (GSK-3), a downstream target of Akt. Coincubation of neurospheres with Sildenafil and LY 294002, a pharmacological inhibitor of PI3-K/Akt, abolished Sildenafil-induced phosphorylated Akt and GSK-3. Furthermore, LY 294002 blocked Sildenafil-increased SVZ cell proliferation. These data suggest that Sildenafil-enhanced neurogenesis likely occurs through activation of the PI3-K/Akt/GSK-3 pathway.
Signaling Mechanisms of HIV-1 Tat-Induced Alterations of Claudin-5 Expression in Brain Endothelial Cells
Authors: András Ibolya E , Pu Hong , Tian Jing , Deli Mária A , Nath Avindra , Hennig Bernhard , Toborek Michal
Published: April 2005

Exposure of brain microvascular endothelial cells (BMEC) to human immunodeficiency virus-1 (HIV-1) Tat protein can decrease expression and change distribution of tight junction proteins, including claudin-5. Owing to the importance of claudin-5 in maintaining the blood–brain barrier (BBB) integrity, the present study focused on the regulatory mechanisms of Tat-induced alterations of claudin-5 mRNA and protein levels. Real-time reverse-transcription-polymerase chain reaction revealed that claudin-5 mRNA was markedly diminished in BMEC exposed to Tat. However, U0126 (an inhibitor of mitogen-activated protein kinase kinase1/2, MEK1/2) protected against this effect. In addition, inhibition of the vascular endothelial growth factor receptor type 2 (VEGFR-2) by SU1498, phosphatidylinositol-3 kinase (PI-3 K) by LY294002, nuclear factor-κB (NF-κB) by peptide SN50, and intracellular calcium by BAPTA/AM partially prevented Tat-mediated alterations in claudin-5 protein levels and immunoreactivity patterns. In contrast, inhibition of protein kinase C did not affect claudin-5 expression in Tat-treated cells. The present findings indicate that activation of VEGFR-2 and multiple redox-regulated signal transduction pathways are involved in Tat-induced alterations of claudin-5 expression. Because claudins constitute the major backbone of tight junctions, the present data are relevant to the disturbances of the BBB in the course of HIV-1 infection.
Construction of a natural partition of incomplete horseshoes
Authors: Jung C. , Emmanouilidou A.
Published: April 2005

We present a method for constructing a partition of an incomplete horseshoe in a Poincare map. The partition is based only on the unstable manifolds of the outermost fixed points and eventually their limits. Consequently, this partition becomes natural from the point of view of asymptotic scattering observations. The symbolic dynamics derived from this partition coincides with the one derived from the hierarchical structure of the singularities of the scattering functions.
Nanoscale piezoelectric coefficient measurements in ionic conducting ferroelectrics
Authors: Agronin A. , Molotskii M. , Rosenwaks Y. , Strassburg E. , Boag A. , Mutchnik S. , Rosenman G.
Published: April 2005

In this work the piezoresponse mode of the atomic force microscope has been applied for piezoelectric coefficient measurements in nanometer scale in high conductive RbTiOPO4 and KTiOPO4 ferroelectric crystals with specifically tailored domain configurations. A strong dependence of the amplitude and phase contrast between oppositely polarized domains on the frequency of the measuring alternate voltage was observed, and allowed the finding of the optimal conditions for piezoelectric coefficient measurements. A theoretical method, taking into account the inhomogeneity of the electric field under the atomic force microscope tip apex, the screening of the applied electric field, and the elastic clamping of the piezoelectrically excited region by the surrounding matrix has been developed for obtaining d33 in ferroelectrics with high ionic conductivity.
Nonlinear longitudinal strain wave interacting with point defect in metal plates
Authors: Mirzade F. Kh.
Published: April 2005

A model of nonlinear longitudinal strain wave propagation in metal plates with quadratic nonlinearity of elastic continuum, exposed to laser impulses, is developed in view of the interaction with the fields of point defects (vacancies and interstitials). The influence of the recombination-generation processes in a defect subsystem on elastic strain wave propagation is analyzed. The existence of a nonlinear elastic shock wave of low intensity is revealed in the system and its structure is studied. The shock waves can have either an oscillatory or a monotonic profile. The estimations of the wave front depth and velocity are performed. The contributions to the linear elastic modulus, as well as to the lattice dispersion parameters are found, which are due to the interaction of the elastic strain field and the field of defects.
Possible two-step solar energy release mechanism due to turbulent magnetic reconnection
Authors: Fan Quan-Lin , Feng Xue-Shang , Xiang Chang-Qing
Published: April 2005

In this paper, a possible two-step solar magnetic energy release process attributed to turbulent magnetic reconnection is investigated by magnetohydrodynamic simulation for the purpose of accounting for the closely associated observational features including canceling magnetic features and different kinds of small-scale activities such as ultraviolet explosive events in the lower solar atmosphere. Numerical results based on realistic transition region physical parameters show that magnetic reconnections in a vertical turbulent current sheet consist of two stages, i.e., a first slow Sweet–Parker-like reconnection and a later rapid Petschek-like reconnection, where the latter fast reconnection phase seems a direct consequence of the initial slow reconnection phase when a critical state is reached. The formation of coherent plasmoid of various sizes and their coalescence play a central role in this complex nonlinear evolution. The “observed” values of the rate of cancellation flux as well as the approaching velocity of magnetic fragments of inverse polarity in present simulation are well consistent with the corresponding measurements in the latest observations. The difference between our turbulent magnetic reconnection two-step energy release model and other schematic two-step models is discussed and then possible application of present outcome to solar explosives is described.
Strongly coupled large-angle stimulated Raman scattering of short laser pulse in plasma-filled capillary
Authors: Kalmykov Serguei , Mora Patrick
Published: April 2005

Strongly coupled large-angle stimulated Raman scattering (LA SRS) of a short intense laser pulse develops in a plane plasma-filled capillary differently than in a plasma with open boundaries. Coupling the laser pulse to a capillary seeds the LA SRS in the forward direction (scattering angle smaller than π∕2) and can thus produce a high instability level in the vicinity of the entrance plane. In addition, oblique mirror reflections off capillary walls partly suppress the lateral convection of scattered radiation and increase the growth rate of the SRS under arbitrary (not too small) angle. Hence, the saturated convective gain falls with an angle much slower than in an unbounded plasma and even for the near-forward SRS can be close to that of the direct backscatter. At a large distance, the LA SRS evolution in the interior of the capillary is dominated by quasi-one-dimensional leaky modes whose damping is related to the leakage of scattered radiation through the walls.
Electrical properties of ferroelectric BaTi2O5 and dielectric Ba6Ti17O40 ceramics
Authors: Beltrán Héctor , Gómez Beatriz , Masó Nahum , Cordoncillo Eloisa , Escribano Purificación , West Anthony R.
Published: April 2005

Single phase powders of BaTi2O5 and Ba6Ti17O40 were made by a sol-gel method with final heating at 1100–1200°C. Ceramic samples were prepared and fired at temperatures in the range 1100–1300°C. Both sets were highly insulating, with conductivities of, e.g., 10−6–10−7Scm−1 at 600°C and activation energies for conduction in the range 1.75–1.86eV. BaTi2O5 compositions are ferroelectric with a permittivity maximum dependent on firing conditions: εmax′=122 at 450°C on firing at 1100°C; and εmax′=130 at 475°C on firing at 1225°C. Ba6Ti17O40 is a dielectric with ε′∼57–55 over the range 40–400°C.
Surface energy anisotropy of FePt nanoparticles
Authors: Hong Suklyun , Yoo M. H.
Published: April 2005

To investigate the surface energy anisotropy of FePt nanoparticles, we have performed self-consistent pseudopotential density-functional calculations. Wulff plots are constructed based on the calculated surface energy anisotropy, and these are used to analyze the structural feature in the reported high-resolution transmission electron microscopy images of FePt nanoparticles.
Pellet fueling technology development leading to efficient fueling of ITER burning plasmas
Authors: Baylor L. R. , Combs S. K. , Jernigan T. C. , Houlberg W. A. , Owen L. W. , Rasmussen D. A. , Maruyama S. , Parks P. B.
Published: April 2005

Pellet injection is the primary fueling technique planned for core fueling of ITER [ITER Technical Basis 2002 ITER EDA Documentation Series (Vienna: IAEA)] burning plasmas. Efficient core plasma fueling with deuterium and tritium D–T is a requirement for achieving high fusion gain and it cannot be achieved with gas fueling. Injection of pellets from the inner wall has been shown on present day tokamarks to provide efficient fueling and is planned for use on ITER. Modeling of the fueling deposition from inner wall pellet injection using the Parks E×B drift model indicates that pellets have the capability to fuel well inside the separatrix. Gas fueling calculations show very poor neutral penetration due to the high density and wide scrape off layer. Isotopically mixed D–T pellets can provide efficient tritium fueling that will minimize tritium wall loading when compared to gas puffing. Currently the performance of the ITER inner wall guide tube design is under test with initial results indicating that pellet speeds in excess of 300 m/s will lead to fragmented pellets. The ITER pellet injection technology requirements and remaining development issues are discussed along with a plan to reach the design goal for employment on ITER.