bluuebunny/crossref_metadata_2025 huggingface dataset:
Substituent effect of large conjugate groups on the DNA base pair derivatives: Density functional study
Authors: Meng Fancui , Wang Huanjie , Xu Weiren , Liu Chengbu
Published: April 2005

The substituent effects caused by 2‐nitro‐naphthalen (aNO2), 2‐hydroxyl‐naphthalen (aOH), 1‐nitro‐4‐vinyl‐benzene (bNO2), and 1‐hydroxyl‐4‐vinyl‐benzene (bOH) have been investigated in this report. The geometries of various substituted base pairs have been optimized using the B3LYP method at the 6‐31G* level with no constraints. The vertical ionization potential energy has been calculated. Natural bond orbital (NBO) and CHelp analyses have also been carried out on both the neutral and cationic systems at the same level. The outcomes show that the hydrogen bond lengths of these substituted base pairs are similar to unsubstituted bases, while the geometries of the substituted bases have an interesting aspect; i.e., the substituent and the substituted base are nonplanar when the substituted base is pyrimide, while it is coplanar when the substituted base is purine. The stabilization energies changed slightly as compared with the corresponding A:T or G:C base pairs. NBO analysis shows that charge transfer is the largest in aOH‐T:A, while it is small in the other derivatives. Population analysis shows that the NPA and Mulliken charge of H has a relationship with the H‐bond lengths, while that of Chelp does not. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A parallel search game
Authors: Goyal Navin , Saks Michael
Published: April 2005

We answer in negative a question of Gál and Miltersen [Proc 30th Int Coll Automata, Languages, and Programming (ICALP) 2003, pp. 332–344] about a combinatorial game arising in the study of time‐space trade‐offs for data structures. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2005
Combat Casualty Care Research: From Bench to the Battlefield
Authors: Alam Hasan B. , Koustova Elena , Rhee Peter
Published: April 2005

Hemorrhagic shock is the leading cause of death in civilian and combat trauma. Effective hemorrhage control and better resuscitation strategies have the potential of saving lives. The Trauma Readiness and Research Institute for Surgery (TRRI‐Surg) was established to address the core mission of the Uniformed Services University, “Learning to Care for Those in Harm’s Way,” by conducting research to improve the outcome of combat casualties. This article highlights the salient achievements of this research effort in the areas of hemorrhage control, resuscitation, design and testing of devices, and some novel concepts such as the use of profound hypothermia. The impact of these basic science research findings on changes in military medical care and outcome of injured soldiers is also described.
Wound Healing Enhancement: Electroporation to Address a Classic Problem of Military Medicine
Authors: Ferguson Mark , Byrnes Colman , Sun Leon , Marti Guy , Bonde Pramod , Duncan Mark , Harmon John W.
Published: April 2005

The major goal of wound healing biology is to determine how a wound can be induced to repair damaged tissue faster and more efficiently. Enhancement of dermal and epidermal regeneration is an extremely important goal for the treatment of many different types of wounds. Exogenous application of growth factors to the wound site has been shown to have potential to improve wound healing. Frequent applications of large amounts of growth factor have been required. This is because proteases in the wound quickly destroy peptide growth factor. Gene therapy has the potential to produce growth factors deep within the wound, where they can be effective as well as able to constantly replenish growth factor that is destroyed by peptidases. We have shown that application of plasmid DNA expression vectors directly into the wound is an inefficient modality. Electroporation, the application of an electrical field across cells to permeabilize the cell membrane has led us to explore the possibility of utilizing the technique to enhance transfection efficiency. We have identified electroporation parameters that improve the efficiency of DNA transfection in cutaneous wounds, and we have shown that electroporation itself does not impair wound healing. We are now on the threshold of exploring whether electroporation‐assisted transfection with DNA plasmid expression vectors for growth factors will be an effective modality for enhancing cutaneous wound healing.
The Military Medical School of Mexico: A Tradition of Excellence
Authors: Villavicencio J. Leonel , Merrill Daniel M. , Rich Norman M.
Published: April 2005

It is a historical fact that warfare and surgery have been linked together as far back as military history has been recorded. In the 18th century, the tendency of most armies to dismiss their medical services at the end of every major conflict resulted in higher mortality at the beginning of the next war. This became evident in the French and British Armies during the Battle of Waterloo. These countries went to great efforts to mobilize their civilian reserve physicians, only to discover that more than half of the medical personnel declined to serve. The scarcity of physicians and the inexperience of those caring for the wounded resulted in a high casualty rate. The current armed conflicts throughout the world with their high number of victims are living evidence of the need for preparedness of the military medical personnel. In this article, we review the systems of military medical education in several countries, and offer the example of the Escuela Medico Militar (Military Medical School) of Mexico, a prestigious source of military medical physicians for the Mexican armed forces.
Experience of Treating Gunshot Wounds of Large Vessels in Afghanistan
Authors: Brusov P. G. , Nikolenko V. K.
Published: April 2005

The problem of treating injuries of large vessels in times of peace has been sufficiently well developed both in theoretical and practical aspects. In times of war, however, due to the large numbers of the wounded, a shortage of expert angiosurgeons, and multiple gunshot wounds, many theoretical tenets lose their academic regularity. The present study is based on the experience of treating 302 patients wounded during the Afghanistan war (1981–1985). Most of the injuries were to the vessels of the extremities. The gunshot wounds were complex. They included extensive destruction of tissue in the damaged segments of the extremities with simultaneous damage of large veins (42.0% of the cases), nerves (45.5%), and bones (47.4%). Multiple‐vessel injuries were encountered in 4% of the cases, with combined injuries comprising 17.5%. Most of the wounded (83.7%) were in a state of shock, with 6.4% in a terminal condition. The blood loss amounted to 15% to 65% of the total volume. Ninety percent of the wounded were admitted to hospitals in the first 6 hours. A two‐stage method was used to treat 71 of the wounded. The method included temporary bypass of the injured arteries and veins while evacuating the wounded and during surgery. Two hundred ninety‐five wounded underwent vessel surgery. Out of the total number of injuries of arteries and veins, vessel sutures were used in 36.9% and 35.9% of the cases, vessel plastics in 41.4% and 7.1% of the cases, and vessel ligation in 21.7% and 60.0% of the cases, respectively. Surgery was completed by fixing the bone fragments externally with the help of special devices using the Ilizarov method. Amputation was performed in 13.9% of the cases. In 7.3% of the cases amputation was performed according to primary indications (no reconstructive surgery attempted on the vessels). In 6.6% of the cases extremities were amputated during the early postoperative period as a result of vessel thrombosis and an increase of tissue ischemia. The mortality rate after vessel surgery was 5.3%. We believe that for patients with gunshot wounds involving vessel injuries, early one‐time reconstruction of the destroyed anatomical structures should be performed.
The LORD Project
Authors: Hemming Ann , Pettit Sue
Published: April 2005

At the 2004 BIALL Conference the Legal Online Resources Database (LORD) was finally launched. LORD is still growing and demonstrates a practical benefit of developing a good working relationship with the legal publishing profession. Ann Hemming gives an outline of the project to date.
Individuelle Lebenssituation und autobiographisches raumbezogenes Wissen
Authors: Xu Guo , Heineken Edgar
Published: April 2005

Zusammenfassung. Die Verfügbarkeit verschiedener Arten raumbezogenen Wissens über die eigene Heimatstadt wird nach einem Retentionsintervall von 22 Jahren bei 127 Bürgern der chinesischen Stadt Tangshan ermittelt. Die Stadt wurde durch ein Erdbeben im Jahre 1976 völlig zerstört und nach einem neuen Plan wiederaufgebaut, so dass während des Retentionsintervalls keine neuen Erfahrungen mit dem alten Stadtbild möglich waren. Eine dreifache Aufteilung der befragten Bürger in unversehrte Ortsansässige, durch das Erdbeben querschnittsgelähmte ortsansässige Personen sowie unmittelbar nach dem Beben an einen anderen Ort verzogene Unversehrte, erlaubt es, den Effekt der individuellen Lebenssituation im Retentionsintervall auf den Wissensabruf zu erfassen. Alle befragten Personen haben nach 22 Jahren Erinnerungen an die Topographie der Stadt, wobei das Landmarkenwissen ausgeprägter ist als das Routenwissen. Das Überblickswissen ist in der Nord-Süd-Dimension besser als in der West-Ost-Dimension. Geschlechtsspezifische Unterschiede zeigen sich allein im Richtungswissen, das bei den Männern verfügbarer ist als bei den Frauen. Ortsansässigkeit erleichtert den raumbezogenen Wissensabruf: “Spurenstärke“ und Grad der Aktivierbarkeit des vor 22 Jahren erworbenen Routenwissens und routenbezogenen Überblickswissens werden durch die Ortsansässigkeit bestimmt. Im Überblickswissen sind die Querschnittsgelähmten den Unversehrten überlegen. Diese Leistungsunterschiede werden im Zusammenhang mit Interferenz- und Rehearsalprozessen gesehen, die durch die jeweilige Lebenssituation der Befragten nach dem Erdbeben bedingt sind.
Innovationsförderliche Führung - Eine empirische Analyse
Authors: Krause Diana E.
Published: April 2005

Zusammenfassung. Auf der Basis des innovationskontextspezifisch adaptierten Lazarus-Modells entwickelt dieser Beitrag ein Modell, das kognitive Prozesse der Wahrnehmung der betrieblichen Situation (wahrgenommene Veränderungsbedürftigkeit und Veränderungsfähigkeit), Innovationsverhalten (Ideengenerierung/-prüfung, Implementierung) und innovationshinderliche Verhaltensweisen (intrapsychische Anpassung, Flucht) durch das Führungsverhalten erklärt. Das Führungsverhalten wird über ausgewählte Einflussgrundlagen beschrieben, die der Vorgesetzte gegenüber der geführten Führungskraft im Innovationsprozess einsetzt (persönliche Ausstrahlung, Expertenwissen/Information, Gewährung von Freiheitsgraden und Autonomie, innovationsbezogene Unterstützung, Verzicht auf Manipulation). Die Erklärungskraft des Modells wird organisations- und branchenübergreifend empirisch überprüft. Hierarchische Regressionsanalysen zeigen, dass die Gewährung von Freiheitsgraden und Autonomie sowie Expertenwissen und Information die stärksten positiven Effekte auf die kognitiven Prozesse und das Innovationsverhalten, und die stärksten negativen Effekte auf die innovationshinderlichen Verhaltensweisen haben.
Coincident buoy‐ and SAR‐derived surface fluxes in the western Weddell Sea during Ice Station Weddell 1992
Authors: Geiger Cathleen A. , Drinkwater Mark R.
Published: April 2005

We examine sea ice kinematics relevant to surface fluxes using ERS‐1 synthetic aperture radar (SAR) images coincident with buoys in the western Weddell Sea in austral autumn of 1992. Careful matching of temporal and spatial scales shows that buoy‐ and SAR‐derived velocities differ in root‐mean‐square error (RMSE) by 0.6 cm s−1 and 7.80° in magnitude and direction, respectively. These values represent agreements of 91.3% and 92.7%, respectively, and correspond to instrument uncertainties. Scaling analysis shows that shear matching is best at the smallest scales (≤5 km), while divergence is better represented at scales of 40 km and larger. Sensitivity to error propagation shows lower agreement for divergence (47.4%; RMSE = 7.46 × 10−8 s−1), but we find these results sufficient for integrated surface flux comparisons. Using a toy model, we test the effects of aliasing in surface flux determination. The results show that variability associated with storms, ocean tides, inertial oscillations, and other high‐frequency forcing affects integrated sea ice growth rates along this continental slope location. Integrated salt and new ice production rates computed from buoys are found to be two times larger than those computed from ERS‐1 SAR motion products. We show that these differences in salt and ice production rates result primarily from inadequate temporal resolution of heat flux variability and sea ice divergence. Comparison with other studies shows that the problem is widespread, thereby impacting the modeling of sea ice mass balance and variability. The small‐scale processes cited here have significant ramifications for larger scales and the global thermohaline circulation.
Geochemistry of serpentinized peridotites from the Mariana Forearc Conical Seamount, ODP Leg 125: Implications for the elemental recycling at subduction zones
Authors: Savov Ivan P. , Ryan Jeffrey G. , D'Antonio Massimo , Kelley Katherine , Mattie Patrick
Published: April 2005

Recent examinations of the chemical fluxes through convergent plate margins suggest the existence of significant mass imbalances for many key species: only 20–30% of the to‐the‐trench inventory of large‐ion lithophile elements (LILE) can be accounted for by the magmatic outputs of volcanic arcs. Active serpentinite mud volcanism in the shallow forearc region of the Mariana convergent margin presents a unique opportunity to study a new outflux: the products of shallow‐level exchanges between the upper mantle and slab‐derived fluids. ODP Leg 125 recovered serpentinized harzburgites and dunites from three sites on the crests and flanks of the active Conical Seamount. These serpentinites have U‐shaped rare earth element (REE) patterns, resembling those of boninites. U, Th, and the high field strength elements (HFSE) are highly depleted and vary in concentration by up to 2 orders of magnitude. The low U contents and positive Eu anomalies indicate that fluids from the subducting Pacific slab were probably reducing in nature. On the basis of substantial enrichments of fluid‐mobile elements in serpentinized peridotites, we calculated very large slab inventory depletions of B (79%), Cs (32%), Li (18%), As (17%), and Sb (12%). Such highly enriched serpentinized peridotites dragged down to depths of arc magma generation may represent an unexplored reservoir that could help balance the input‐output deficit of these elements as observed by Plank and Langmuir (1993, 1998) and others. Surprisingly, many species thought to be mobile in fluids, such as U, Ba, Rb, and to a lesser extent Sr and Pb, are not enriched in the rocks relative to the depleted mantle peridotites, and we estimate that only 1–2% of these elements leave the subducting slabs at depths of 10 to 40 km. Enrichments of these elements in volcanic front and behind‐the‐front arc lavas point to changes in slab fluid composition at greater depths.
On the uncertainties in hot spot reconstructions and the significance of moving hot spot reference frames
Authors: O'Neill Craig , Müller Dietmar , Steinberger Bernhard
Published: April 2005

It is widely accepted that substantial relative motion has occurred between the Indo‐Atlantic and Pacific hot spots since the Late Cretaceous. At the same time, a fixed Indo‐Atlantic hot spot reference frame has been argued for and used since the advent of plate tectonics, implying relatively little motion between the hot spots in this domain since about 130 Ma. Most plumes purported to have caused these hot spots, while being advected in the global‐scale mantle flow field, are assumed to move an order of magnitude more slowly than plates. However, the lifetime of a plume may be over ∼100 Myr, and the integrated motion of a plume is expected to be significant over these times. The uncertainties inherent in hot spot reconstructions are of a magnitude similar to the expected plume motion, and so any differences between a fixed and moving frame of reference must be discernible beyond the level of these uncertainties. We present a method for constraining hot spot reconstruction uncertainties, similar to that in use for relative plate motion. We use a modified Hellinger criterion of fit for the hot spot problem, using track geometries and radiometric dating, and derive covariance matrices for our Indo‐Atlantic rotations for the last 120 Myr. However, any given mantle convection model introduces additional uncertainties into such models, based on its model parameters and starting conditions (e.g., choice of global tomography model, viscosity profile, nature of mantle phase transitions). We use an interactive evolutionary approach, where we constrain the hot spot motion resulting from convection models to fit paleomagnetic constraints, and converge on an acceptable motion solution by varying unknowns over several generations of simulations. Our hot spot motion model shows large motion (5–10°) of the Indo‐Atlantic hot spots for times >80 Ma, consistent with available paleomagnetic constraints. The differences between the fixed and moving hot spot reference frames are not discernible over the level of uncertainty in such rotations for times <80 Ma.
Impact of barrier layer on winter‐spring variability of the southeastern Arabian Sea
Authors: Masson S. , Luo J.‐J. , Madec G. , Vialard J. , Durand F. , Gualdi S. , Guilyardi E. , Behera S. , Delecluse P. , Navarra A. , Yamagata T.
Published: April 2005

In the present study, we use a coupled model to evaluate the effect of shallow salinity stratification on the sea surface temperature (SST) and on the monsoon onset in the southeastern Arabian Sea (SEAS). A 100‐year control experiment shows that the coupled model reproduces the main climatic features in this region in terms of SST, precipitation and barrier layer (BL). A 100‐year sensitivity experiment (where BL effects have been suppressed in the SEAS) shows that BL enhances the spring SST warming by 0.5°C, and leads to a statistically significant increase of precipitation in May (3 mm/day) linked to an early (10 to 15 days) monsoon onset. This suggests that the BL extent may be a useful predictor of the summer monsoon onset in the area with a two‐month lead‐time. However the effect above is mostly concentrated in the SEAS, and there is no significant impact over continental India.
Time‐height evolution of intraseasonal oscillations in the tropical lower atmosphere: Multilevel wind observations using UHF radar
Authors: Krishnan Praveena , Kunhikrishnan P. K. , Nair S. Muraleedharan
Published: April 2005

Signatures of the low frequency intraseasonal oscillations (ISO) and their time‐height evolution in the lower atmosphere are studied using multilevel wind observations made at a tropical Indian site, Gadanki using UHF radar during the period from March 1999 to September 2000. Spectral analysis using Fast Fourier transform (FFT) and wavelet transform showed the presence of oscillations in zonal wind and revealed their evolution in height and time during the observational period. 10–25 day and 30–60 day oscillations are predominantly observed during pre‐monsoon and southwest (SW) monsoon respectively. The amplitude of these oscillations are found to be weak in the lower altitudes and strengthened across the lower Atmospheric Boundary Layer (ABL) and this is quite prominent in the case of 30–60 day oscillations. All these oscillations strengthened at higher altitudes especially above mean ABL height >1 km. It is observed that intense 10–25 day oscillations present during pre monsoon become 30–60 day oscillations as monsoon intensifies. Spectral analysis carried out using NCEP wind for the same period also showed the existence of increasing time scale along SW monsoon season even though 10–25 day and 80–90 day oscillations are found to be relatively weak. Further use of NCEP zonal wind in 2001 and 2002 showed a remarkably different behaviour during the dry year of 2002 with an early development of low‐frequency oscillations prior to the monsoon season.
New constraints on mechanisms of remotely triggered seismicity at Long Valley Caldera
Authors: Brodsky Emily E. , Prejean Stephanie G.
Published: April 2005

Regional‐scale triggering of local earthquakes in the crust by seismic waves from distant main shocks has now been robustly documented for over a decade. Some of the most thoroughly recorded examples of repeated triggering of a single site from multiple, large earthquakes are measured in geothermal fields of the western United States like Long Valley Caldera. As one of the few natural cases where the causality of an earthquake sequence is apparent, triggering provides fundamental constraints on the failure processes in earthquakes. We show here that the observed triggering by seismic waves is inconsistent with any mechanism that depends on cumulative shaking as measured by integrated energy density. We also present evidence for a frequency‐dependent triggering threshold. On the basis of the seismic records of 12 regional and teleseismic events recorded at Long Valley Caldera, long‐period waves (>30 s) are more effective at generating local seismicity than short‐period waves of comparable amplitude. If the properties of the system are stationary over time, the failure threshold for long‐period waves is ∼0.05 cm/s vertical shaking. Assuming a phase velocity of 3.5 km/s and an elastic modulus of 3.5 × 1010Pa, the threshold in terms of stress is 5 kPa. The frequency dependence is due in part to the attenuation of the surface waves with depth. Fluid flow through a porous medium can produce the rest of the observed frequency dependence of the threshold. If the threshold is not stationary with time, pore pressures that are >99.5% of lithostatic and vary over time by a factor of 4 could explain the observations with no frequency dependence of the triggering threshold.
Validation of GOME polarization measurements by method of limiting atmospheres
Authors: Krijger J. M. , Tanzi C. P. , Aben I. , Paul F.
Published: April 2005

A method is presented for validation of space‐based polarization measurements. The method is based on a determination of limits in the (fractional) polarization of reflected solar light as measured by the GOME instrument. These empirical limits were used to study the instrument performance during the first 5.5 years of GOME operation (1996–2001), which revealed a wavelength and viewing angle‐dependent degradation of the GOME polarization measurement devices. Degradation correction factors are derived under the assumption that these polarization limits remain constant in time. Using results from earlier GOME studies on clouds, Lambertian equivalent reflectance, and geolocations, it is shown that these limits correspond to cloud‐free scenes with minimal aerosol load and minimal surface albedo in the case of highly polarized observations, or to clouded scenes in the case of unpolarized observations. The polarization state of the atmosphere corresponding to observations of extremely highly polarized scenes is verified using vector radiative transfer calculations.
The 800 year long ion record from the Lomonosovfonna (Svalbard) ice core
Authors: Kekonen Teija , Moore John , Perämäki Paavo , Mulvaney Robert , Isaksson Elisabeth , Pohjola Veijo , van de Wal Roderik S. W.
Published: April 2005

We present a high‐resolution record of water‐soluble ion chemistry from a 121 m ice core spanning about 800 years. The core is well dated to 2/3 depth using cycle counting and reference horizons and a simple but close fitting model for the lower 1/3 of the core. This core suffers from modest seasonal melt, and so we present concentration data in decadal running means to minimize percolation effects. Sea‐salt ions (Na+, Cl−, Mg2+, and K+) account for more than 70% of all ions. In general, sea‐salt ion concentrations are rather variable and have no clear association with climatic variations. Sulfate, with 74% being from non‐sea‐salt sources, has higher concentrations than seen on Vestfonna ice cap but lower than in Ny‐Ålesund aerosols, suggesting central Spitsbergen receives more marine (westerly) air masses than Ny‐Ålesund but more sulfate enriched (easterly) air masses than Nordaustlandet. Clear anthropogenic impacts are found for sulfate, nitrate, and ammonium (and probably excess chloride) after the mid twentieth century, with sulfate showing a significant rise by the end of the nineteenth century. Sulfate and methanesulfonate concentrations correlate well during the twentieth century, and it is clear that most of the preindustrial sulfate is of biogenic origin. Terrestrial component (Ca2+) has the highest concentrations in the coldest part of the Little Ice Age, suggesting more windy conditions, transporting local terrestrial dust to the ice cap. All ion concentrations decrease at the end of the twentieth century, which reflects loss of ions by runoff, with non‐sea‐salt magnesium being particularly sensitive to melting.
Close electric field signatures of dart leader/return stroke sequences in rocket‐triggered lightning showing residual fields
Authors: Rakov V. A. , Kodali V. , Crawford D. E. , Schoene J. , Uman M. A. , Rambo K. J. , Schnetzer G. H.
Published: April 2005

Vertical electric field waveforms due to dart leader/return stroke sequences measured on the ground 15 and 30 m from the negative lightning channel are used to examine the so‐called residual electric field, the difference between the leader electric field change, and the following return stroke electric field change. At these distances, no residual field is expected if the return stroke neutralizes essentially all the charge deposited by the leader within a few hundred meters above ground. There is a clear tendency for strokes having larger peak currents to be associated with larger residual electric fields. The ratio of residual electric fields at 15 and 30 m suggests that the residual field varies as r−1.5, where r is the horizontal distance from the lightning channel. The residual electric field is found from modeling to be associated with an equivalent point charge of the order of hundreds of microcoulombs to a few millicoulombs at a height of 15 to 30 m deposited by the leader but presumably left unneutralized by the return stroke. This residual point charge decays exponentially on a timescale of the order of milliseconds to tens of milliseconds. While the nature of the residual charge is unknown, it could be associated with small branches formed near the descending leader tip just prior to or during the attachment process. In long laboratory spark experiments, such branches have apparently been observed to lose their connection with the main channel.
The NH4+‐NO3−‐Cl−‐SO42−‐H2O aerosol system and its gas phase precursors at a pasture site in the Amazon Basin: How relevant are mineral cations and soluble organic acids?
Authors: Trebs Ivonne , Metzger Swen , Meixner Franz X. , Helas Günter , Hoffer András , Rudich Yinon , Falkovich Alla H. , Moura Marcos A. L. , da Silva Rosiberto S. , Artaxo Paulo , Slanina Jacob , Andreae Meinrat O.
Published: April 2005

Real‐time measurements of ammonia, nitric acid, hydrochloric acid, sulfur dioxide and the water‐soluble inorganic aerosol species, ammonium, nitrate, chloride, and sulfate were performed at a pasture site in the Amazon Basin (Rondônia, Brazil). The measurements were made during the late dry season (biomass burning), the transition period, and the onset of the wet season (clean conditions) using a wet‐annular denuder (WAD) in combination with a Steam‐Jet Aerosol Collector (SJAC). Measurements were conducted from 12 September to 14 November 2002 within the framework of LBA‐SMOCC (Large‐Scale Biosphere Atmosphere Experiment in Amazonia ‐ Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate). Real‐time data were combined with measurements of sodium, potassium, calcium, magnesium, and low‐molecular weight (LMW) polar organic acids determined on 12‐, 24‐, and 48‐hours integrated filter samples. The contribution of inorganic species to the fine particulate mass (Dp ≤ 2.5 μm) was frequently below 20% by mass, indicating the preponderance of organic matter. The measured concentration products of NH3 × HNO3 and NH3 × HCl persistently remained below the theoretical equilibrium dissociation constants of the NH3/HNO3/NH4NO3 and NH3/HCl/NH4Cl systems during daytime (RH < 90%). The application of four thermodynamic equilibrium models (EQMs) indicates that the fine mode aerosol anions NO3−, Cl−, and SO42− were balanced predominantly by mineral cations (particularly pyrogenic K+) during daytime. At nighttime (RH > 90%) fine‐mode NH4NO3 and NH4Cl are predicted to be formed in the aqueous aerosol phase. Probably, Cl− was driven out of the aerosol phase largely by reaction of pyrogenic KCl with HNO3 and H2SO4. As shown by an updated version of the equilibrium simplified aerosol model (EQSAM2), which incorporates mineral aerosol species and lumped LMW polar organic acids, daytime aerosol NH4+ was mainly balanced by organic compounds.
Causes of differing temperature trends in radiosonde upper air data sets
Authors: Free Melissa , Seidel Dian J.
Published: April 2005

Differences between trends in different radiosonde temperature products resulting from the varying choices made by the developers of the data sets create obstacles for use of those products in climate change detection and attribution. To clarify the causes of these differences, one must examine results using a common subset of locations to minimize spatial sampling effects. When this is done for the Lanzante‐Klein‐Seidel (LKS) and Hadley Center (HadRT) radiosonde data sets, differences are reduced by at least one third. Differing homogeneity adjustment methods and differences in the source data are both important factors contributing to the remaining discrepancies. In contrast, subsampling the microwave sounding unit (MSU) satellite data sets according to the radiosonde coverage does not generally bring the trends in the satellite data closer to those in the radiosonde data so that adjustments and other processing differences appear to be the predominant sources of satellite‐radiosonde discrepancies. Experiments in which we subsample globally complete data sets provide additional insight into the role of sampling errors. In the troposphere, spatial sampling errors are frequently comparable to the trends for 1979–1997, while in the stratosphere the errors are generally small relative to the trends. Sampling effects estimated from National Centers for Environmental Prediction reanalysis and MSU satellite data for seven actual radiosonde networks show little consistent relation between sampling error and network size. These results may have significant implications for the design of future climate monitoring networks. However, estimates of sampling effects using the reanalysis and the satellite data sets differ noticeably from each other and from effects estimated from actual radiosonde data, suggesting that these globally complete data sets may not fully reproduce actual sampling effects.
Modeling of the northern hemisphere ice sheets during the last glacial cycle and glaciological sensitivity
Authors: Zweck Chris , Huybrechts Philippe
Published: April 2005

We present a new three‐dimensional thermomechanically coupled ice sheet model of the northern hemisphere to reconstruct the Quaternary ice sheets during the last glacial cycle. The model includes basal sliding, internally calculated surface mass balance, glacial isostasy, and a treatment for marine calving. The time dependent forcing consists of temperature and precipitation anomalies from the United Kingdom Meteorological Office (UKMO) General Circulation Model scaled to the Greenland Ice Core Project (GRIP) ice core δ18O record. Model parameters were chosen to best match geomorphological inferences on Last Glacial Maximum extent and global eustatic sea level change. For our standard run we find a maximum ice volume of 57 × 106 km3 at 18.5 ka cal BP. This corresponds to a eustatic sea level lowering of 110 m after correction for hydro‐isostatic displacement and anomalous ice resulting from defects in the specified boundary conditions of the Paleoclimate Model Intercomparison Project (PMIP) for which the UKMO GCM results were generated. Of this 110 m, 82 m was stored in the North American ice sheet and 25 m in the Eurasian ice sheet. We determine the qualitative and quantitative response of the model from a comprehensive sensitivity study in which 11 important parameters were varied over their respective ranges of uncertainty. Model outputs comparable to the observational record were explored in detail as a linear function along the axes of parameter space of the reference model. The method reveals the dominance of climate uncertainty when modeling the Last Glacial Maximum configuration of the northern hemisphere ice sheets, but also highlights the role of ice rheology and basal processes for ice sheet thickness, and glacial isostasy and calving for the timing of maximum ice volume.
Evaluation of a wind power parameterization using tower observations
Authors: Lazarus Steven M. , Bewley Jennifer
Published: April 2005

The spatial and temporal components of a published wind power parameterization method are evaluated using observed winds (9 m to 90 m) from 7 years of data collected at four towers in the Kennedy Space Center/Cape Canaveral Air Force Station network. The temporal component is governed by two parameterization inputs which represent the amplitude and mean of an assumed sinusoidal diurnal variation of the ratio of the 80 m to 10 m winds, respectively. Comparison with tower observations shows that the estimates of the mean ratio are robust but biased high, indicating that the temporal variation of the observations can be approximated by, but is not, a pure sinusoid. The observed and parameterized amplitude are poorly correlated as the amplitude estimate is sensitive to small phase shifts in the diurnal variation of the ratio of the wind speeds. The observed annual wind power for the site is consistent with what is known about the wind energy potential in Florida, while wind power estimates based on the temporal extrapolation are more than twice that observed. The erroneous wind power estimate is shown to be related to an assumption that negative amplitude estimates are indicative of a diurnal phase shift in the ratio of the 80 m to 10 m winds. When the assumed phase shift is removed from the data and the observed inputs are applied, the parameterized 80 m wind power estimates were comparable to those observed. The spatial component of the parameterization depends on a least squares fit of four different wind extrapolation methods to 0000 and 1200 UTC wind profiles. Comparison of the observed 80 m winds with those obtained via the least squares method indicates that the 0000 UTC 80 m wind and power estimates exceed (by as much as 1 m s−1 and 200 W m−2, respectively) the observed 80 m winds and power for all months. When compared against the 0000 UTC regression, the 1200 UTC 80 m wind and power estimates are closer to the observed power for all months. The power law often yields the lowest residual (on the order of 15–20% of the time) but is also largely responsible for high power estimates. The positive power bias (i.e., estimated greater than observed) is a result of the combination of two factors, namely, (1) the 0000/1200 UTC profiles and 10 m winds are, in general, not representative of the daily averaged values, with the 0000 and 1200 UTC 10 m winds less than their daily average, and (2) the differences between the observed 80 m and 10 m 0000 and 1200 UTC winds are greater than the difference between the daily averaged 80 m and 10 m mean winds. These results illustrate the potentially problematic nature of combining the lowest residual producing (extrapolation) method, obtained from a fit to the 0000 or 1200 UTC wind profiles, and the daily‐averaged 10 m wind to produce a daily‐averaged 80 m wind estimate.
Enhancing cuttings removal with gas blasts while drilling on Mars
Authors: Zacny K. A. , Quayle M. C. , Cooper G. A.
Published: April 2005

Future missions to Mars envision use of drills for subsurface exploration. Since the Martian atmosphere precludes the use of liquids for cuttings removal, proposed drilling machines utilize mechanical cuttings removal systems such as augers. However, an auger can substantially contribute to the total power requirements, and in the worst scenario it can choke. A number of experiments conducted under Martian pressures showed that intermittent blasts of gas at low differential pressures can effectively lift the cuttings out of the hole. A gas flushing system could be incorporated into the drill assembly for assistance in clearing the holes of rock cuttings or for redundancy in case of auger jamming. A number of variables such as the particle size distribution of the rock powder, the type of gas used, the bit and auger side clearances, the initial mass of cuttings, and the ambient pressure were investigated and found to affect the efficiency. In all tests the initial volume of gas was close to 1 L and the differential pressure was varied to achieve desired clearing efficiencies. Particles were being lifted out of the hole at a maximum speed of 6 m/s at a differential pressure of 25 torr and ambient pressure of 5 torr. Flushing tests lasted on average for 2 s. The power required to compress the thin Martian atmosphere to achieve a sufficient gas blast every minute or so at 10% efficiency was calculated to be of the order of a few watts.
Investigation of the performance of a coring bit in frozen mud under Martian conditions of low temperature and pressure
Authors: Zacny K. A. , Cooper G. A.
Published: April 2005

A diamond‐impregnated bit will be the most probable choice for Mars drilling applications. This is because it can be used to drill or cut the hardest rocks, including the most common rocks on Mars, i.e., basalt and andesite (Bandfield et al., 2000). Recent results suggest a possibility of the Martian regolith containing clay minerals (Webster and Savage, 2004; Ruff, 2003), products of chemical weathering of certain minerals such as, for example, olivine (Hoefen et al., 2003) in the presence of water. Thus, in addition to volcanic rocks, the bit might also have to drill through other geological formations, including, for example, clay‐rich soils commonly known as mud. This argument supposes that the Martian drill will have no option for changing bits. Thus the question exists, whether a bit of the diamond‐impregnated type can also be used successfully in frozen mud. It was found that mud exhibits three different physical conditions, depending on its temperature. The bit can effectively drill and the entire core can be successfully recovered provided that the mud is kept in the temperature region between approximately −8°C and 0°C. Above 0°C the mud becomes sticky. Below −8°C the mud is hard frozen and the bit cannot penetrate it successfully. Measurement of the electrical resistance of the mud directly below the bit while drilling was used together with the bit temperature to assess the physical state of the mud below the bit.
Variability of unusual distributions of alkenones in the surface waters of the Nordic seas
Authors: Bendle James , Rosell‐Melé Antoni , Ziveri Patrizia
Published: April 2005

Samples of filtered particulate organic matter (POM) were obtained during the summers of 1999 and 2000 from the surface waters of the Nordic seas to monitor the spatial distribution of long‐chain alkenones. The aim of the study was to appraise existing alkenone‐based climatic proxies in northern high latitudes. Unusually high percentages of the tetraunsaturated alkenone were measured in the polar waters of the East Greenland Current, with C37:4 of up to 77% in 80% of sea‐ice cover. Values of percent C37:4 across the Nordic seas showed a strong association with water mass type. Analysis of coccoliths in filters indicated that calcified Emiliania huxleyi could not be discounted as the biological precursor of alkenones in all the water masses. A combined data set of 69 samples of POM revealed a stronger correlation of percent C37:4 to sea surface salinity (SSS; R2 = 0.72) than to sea surface temperature (SST; R2 = 0.50). Values of percent C37:4 in sea surface POM were much higher than those in surficial sediments of the northern North Atlantic. To explain the discrepancy in sedimentary and surface water column percent C37:4, we propose that the alkenone contents in surface sediments underlying arctic and polar waters are a combination of autochthonous and allochthonous inputs of alkenones. Our results show that percent C37:4 can be used to reconstruct the relative extension of arctic/polar water masses in the North Atlantic. However, the results prevent confirmation of percent C37:4 as a paleo‐SSS proxy in the Nordic seas, given its multivariate nature in our data set and the decoupling between its range of values in surface waters and sediments.
Improved estimation of terrestrial water storage changes from GRACE
Authors: Han Shin‐Chan , Shum C. K. , Jekeli Christopher , Alsdorf Doug
Published: April 2005

The temporal variations in the Earth's gravity field caused by fluctuations in terrestrial water mass can be inferred from changes in GRACE monthly gravity field solutions. Such methods have limited spatial resolution due to a necessary and possibly arbitrary truncation and smoothing of the coefficients. Limiting the temporal resolution to one month was necessary to solve the gravity field by a global representation. Our alternative method uses GRACE satellite‐to‐satellite tracking and accelerometer data to obtain the along‐track geopotential differences and directly estimate the temporal gravity variations regionally. This method was tested on the estimation of hydrological mass anomaly over the Amazon and Orinoco river basins. Compared to conventional spherical harmonic methods, the spatial extent of the estimated GRACE water height anomaly achieved finer resolution and is shown to follow more closely the boundaries of the river basins and significant systematic variation could be discerned at 15‐day temporal resolutions.
Convergence of Laplacian diffusion versus resolution of an ocean model
Authors: Wallcraft Alan J. , Kara A. Birol , Hurlburt Harley E.
Published: April 2005

This paper presents a convergence study for second order finite difference Laplacian diffusion used in ocean models. For demonstration, ocean model simulations are performed over a rectangular domain, based on the North Pacific subtropical gyre region with grid resolution between 1/2° and 1/32° and with horizontal eddy viscosity coefficient (AH) ranging from 8000 to 30 m2 s−1. A range of AH which is appropriate for useful model simulations of an oceanic domain is found to exist. This range is determined by examining the spatial patterns of Eddy kinetic energy and mean sea surface height. The results fall into three broad categories: (a) converged, (b) converging, and (c) numerical problems. Solutions in the “converged” category do not change with increased grid resolution, and solutions in the “numerical problems” category exhibit distinct differences to the converged result at the same AH.
Expression of Cellular FLICE Inhibitory Proteins (cFLIP) in Normal and Traumatic Murine and Human Cerebral Cortex
Authors: Hainsworth Atticus H , Bermpohl Daniela , Webb Tania E , Darwish Ribal , Fiskum Gary , Qiu Jianhua , McCarthy Deirdre , Moskowitz Michael A , Whalen Michael J
Published: April 2005

Cellular Fas-associated death domain-like interleukin-1-beta converting enzyme (FLICE) inhibitory proteins (cFLIPs) are endogenous caspase homologues that inhibit programmed cell death. We hypothesized that cFLIPs are differentially expressed in response to traumatic brain injury (TBI). cFLIP-alpha and cFLIP-delta mRNA were expressed in normal mouse brain—specifically cFLIP-delta (but not cFLIP-alpha) protein was robustly expressed. After controlled cortical impact (CCI), cFLIP-alpha expression increased initially then decreased to control levels at 12 h, increasing again at 24-72 h ( P<0.05). cFLIP-delta expression was decreased in brain homogenates by 12 h after CCI, then increased again at 24 to 72 h ( P<0.05). cFLIP-delta immunostaining was markedly reduced in injured cortex, but not hippocampus, at 3 to 72 h after CCI. In cortex, reduced cFLIP-delta staining was found in TUNEL-positive cells, but in hippocampus TUNEL-positive cells expressed cFLIP-delta immunoreactivity. cFLIP-delta was increased in a subset of reactive astrocytes in pericontusional cortex and hippocampus at 48 to 72 h. Low levels of both cFLIP isoforms were detected in human cortical tissue with no TBI, from four patients undergoing brain surgery for epilepsy and <24 h post mortem from three patients without CNS pathologic assessment. In cortical tissue surgically removed <18 h after severe TBI ( n = 3), cFLIP-alpha expression was increased relative to epilepsy controls ( P<0.05) but not relative to post-mortem controls. The data suggest differential spatial and temporal regulation of cFLIP-alpha and cFLIP-delta expression that may influence the magnitude of cell death and further implicate programmed mechanisms of cell death after TBI.
Endothelin-1 Overexpression Leads to Further Water Accumulation and Brain Edema after Middle Cerebral Artery Occlusion via Aquaporin 4 Expression in Astrocytic End-Feet
Authors: Lo Amy CY , Chen Ann YS , Hung Victor KL , Yaw Lai Ping , Fung Maggie KL , Ho Maggie CY , Tsang Margaret CS , Chung Stephen SM , Chung Sookja K
Published: April 2005

Stroke patients have increased levels of endothelin-1 (ET-1), a strong vasoconstrictor, in their plasma or cerebrospinal fluid. Previously, we showed high level of ET-1 mRNA expression in astrocytes after hypoxia/ischemia. It is unclear whether the contribution of ET-1 induction in astrocytes is protective or destructive in cerebral ischemia. Here, we generated a transgenic mouse model that overexpress ET-1 in astrocytes (GET-1) using the glial fibrillary acidic protein promoter to examine the role of astrocytic ET-1 in ischemic stroke by challenging these mice with transient middle cerebral artery occlusion (MCAO). Under normal condition, GET-1 mice showed no abnormality in brain morphology, cerebrovasculature, absolute cerebral blood flow, blood-brain barrier (BBB) integrity, and mean arterial blood pressure. Yet, GET-1 mice subjected to transient MCAO showed more severe neurologic deficits and increased infarct, which were partially normalized by administration of ABT-627 (ETA antagonist) 5 mins after MCAO. In addition, GET-1 brains exhibited more Evans blue extravasation and showed decreased endothelial occludin expression after MCAO, correlating with higher brain water content and increased cerebral edema. Aquaporin 4 expression was also more pronounced in astrocytic end-feet on blood vessels in GET-1 ipsilateral brains. Our current data suggest that astrocytic ET-1 has deleterious effects on water homeostasis, cerebral edema and BBB integrity, which contribute to more severe ischemic brain injury.