bluuebunny/crossref_metadata_2025 huggingface dataset:
Abdominal trauma in war
Authors: Rignault Daniel P.
Published: August 2005

In war, the percentage of casualties with abdominal wounds on battle‐fields is near 20%. Roughly half of these casualties die almost immediately from bleeding. Wounding agents are most often either bullets or fragments from various detonating devices. Severity of pathology induced by these agents and prolonged lag time between injury and treatment constitute major differences between peace and war abdominal injuries. Since the means of diagnosis is unsophisticated in war, penetrating abdominal injury leads to systematic exploratory laparotomy, although 10% to 20% of explorations are negative. The management of colon lesions remains a controversial issue. In modern war surgery manuals, primary colon repair is not totally condemned and is generally considered acceptable, but under stricter criteria than in civilian practice. In abdominal war wounds, mortality rate dropped from 53% during World War I to 18–36% at the end of World War II. In Vietnam it went down near 10% in some limited hospital series. But other data collected during that conflict show a less rosy picture. Of 476 abdominal casualties, the total mortality reached 42%. The hospital mortality among the survivors was 11.5%. Death in cases where abdominal wound was the primary lesion was due to hemorrhage in 60%, sepsis in 25%, and pulmonary insufficiency in 15%. Survivors had an average of 1.8 injured organs.
Multifactorial analysis of septic bile and septic complications in biliary surgery
Authors: Landau Ofer , Kott Itamar , Deutsch Alexander A. , Stelman Eldad , Reiss Rafael
Published: August 2005

A unifactorial analysis for possible risk factors was applied to 2,700 consecutive operations for benign disease of the biliary tract. A series of high risk factors in relation to positive bacteriology and septic complication could be identified. These risk factors were patients who were elderly (>70 years;p<0.001), those who were diabetic, those who had a serum bilirubin >1.1 mg% (p<0.001), those who had acute cholecystitis (p<0.001), and those in whom choledochal stones were found (p<0.001). Using a multivariate analysis, we concluded that in patients with no risk factors (56.9%) the incidence of a positive bacteriology was low (10.9%) and they should receive no antibiotic prophylaxis. Patients with one risk factor (24%), had a 36% incidence of positive bacteriology and minimal pre‐operative prophylaxis is recommended. Patients with two or more risk factors (19.1%) had a 77.6% incidence of positive bacteriology and full peri‐operative prophylaxis is recommended, starting pre‐operatively and continuing for 3 to 5 days postoperatively. The aim of this study was to identify patients at risk for septic complication in biliary surgery and to create new guidelines for the antibiotic treatment of selected groups.
Small bowel anastomosis with the biofragmentable anastomosis ring and manual suture: A prospective, randomized study
Authors: Gullichsen Risto , Ovaska Jari , Rantala Arto , Havia Tapani
Published: August 2005

A total of 170 patients undergoing upper gastrointestinal surgery requiring a jejuno‐jejunal enteroanastomosis were randomized into two groups according to the method to be employed at the enteroanastomosis. The most common procedures were partial gastrectomy for benign disease (84 patients), partial or total gastrectomy for malignant disease (35 patients), and bilioenteral bypass (31 patients, 25 for malignant disease). The enteroanastomosis was created by manual suture (3‐0 Dexon®, two layers) in 89 patients and with the Biofragmentable Anastomosis Ring (Valtrac‐BAR®) in 81 patients. Both end‐to‐side (101 patients) and side‐to‐side (69 patients) reconstructions were done. No ruptures or obstructions of the jejuno‐jejunal anastomosis occurred. The postoperative recovery of the gastrointestinal tract was similar in the two groups in duration of nasogastric drainage, intravenous fluid therapy, and intestinal paralysis. Nor was there any difference between the groups in the duration of the postoperative hospital stay. Ten patients, 7 in suture‐group and 3 in BAR‐group, died postoperatively of causes unrelated to the enteroanastomosis. Thus the mortality rate was 7.9% in the suture group and 3.7% in the BAR group. The biofragmentable ring offers a safe alternative to manual sutures for small bowel anastomoses.
Chondrosarcomas of the head and neck
Authors: Ruark Deborah S. , Schlehaider Uwe K. , Shah Jatin P.
Published: August 2005

Chondrosarcomas of the head and neck are uncommon. Over a 35‐year period (1950–1985) at our institution, 557 patients had an established diagnosis of chondrosarcoma. In 28 (5%) of these patients, the tumor was located in the head and neck region. A retrospective analysis was performed in an attempt to accurately define clinical characteristics, management, and outcome in these 28 patients. The patient population consisted of 15 males and 13 females whose ages ranged from 10 to 72 years, with a median of 38 years. Ten (36%) patients were untreated and 18 (64%) previously treated patients were referred for further management. The primary sites were maxilla (11), cervical vertebrae (7), mandible (3), skull (2), sphenoid and ethmoid sinuses (2), frontal sinus (1), nasal septum (1), and orbit (1). Lesions arising in the larynx were excluded from this study. The most common presenting symptom was a painless mass. Surgery was the definitive treatment in all patients. However, adjuvant radiation therapy or chemotherapy was utilized for residual disease in almost half of the cases (13 patients). Follow‐up ranged from 5 to 35 years. Twelve (43%) of the 28 patients were known to be alive and free of disease more than 5 years after surgery. The most common cause of death was uncontrollable local disease (88%). However, only 3 of the 10 previously untreated patients developed local recurrence. For all patients, the median interval from time of first recurrence until death was 25 months (range 6 to 70 months). Positive margins in 8 of 12 patients resulted in local recurrence and eventual death. Distant metastases were documented in 18% of patients, most often involving the lungs. Analysis of a subgroup of patients treated more recently (1975–1985) reveals 7 (78%) of 9 patients to be alive and free of disease at 5 years postoperatively.
Burn depth: A review
Authors: Heimbach David , Engrav Loren , Grube Baiba , Marvin Janet
Published: August 2005

Despite the plethora of technologic advances, the most common technique for diagnosing burn depth remains the clinical assessment of an experienced burn surgeon. It is clear that this assessment is accurate for very deep and very shallow burns. But since clinical judgment is not precise in telling whether a dermal burn will heal in 3 weeks, efforts to develop a burn depth indicator are certainly warranted to accurately determine which dermal burns to excise and graft. This review summarizes the considerable literature in which a variety of techniques to determine burn depth have been used.
Burn shock resuscitation
Authors: Warden Glenn D.
Published: August 2005

The goal of fluid resuscitation in the burn patient is maintenance of vital organ function at the least immediate or delayed physiological cost. To optimize fluid resuscitation in severely burned patients, the amount of fluid should be just enough to maintain vital organ function without producing iatrogenic pathological changes. The composition of the resuscitation fluid in the first 24 hours postburn probably makes very little difference; however, it should be individualized to the particular patient. The utilization of the advantages of hypertonic, crystalloid, and colloid solutions at various times postburn will minimize the amount of edema formation. The rate of administration of resuscitation fluids should be that necessary to maintain satisfactory organ function, with maintenance of hourly urine outputs of 30 cc to 50 cc in adults and 1–2 cc/kg/% burn in children. When a child reaches 30 kg to 50 kg in weight, the urine output should be maintained at the adult level. With our current knowledge of the massive fluid shifts and vascular changes that occur, mortality related to burn‐induced hypovolemia has decreased considerably. The failure rate for adequate initial volume restoration is less than 5% even for patients with burns of more than 85% of the total body surface area. These improved statistics, however, are derived from experience in burn centers, where there is substantial knowledge of the pathophysiology of burn injury. Inadequate volume replacement in major burns is, unfortunately, common when clinicians lack sufficient knowledge in this area.
Benefits and limitations of burn wound excision
Authors: Monafo William W. , Bessey Palmer Q.
Published: August 2005

This review is intended to provide a balanced view of the role of surgical burn wound excision and closure within the larger context of the total care and rehabilitation of patients with burn injury. The historical background leading to present practice is outlined. The salient technical and logistical problems associated with the performance of wound excision are discussed, with emphasis on the necessity for expeditiously completing these procedures which are associated with major blood loss. A realistic analysis of the results of excisional therapy in patients with burns of varying severity is presented. Benefits attributable to the surgical phase of therapy become progressively more difficult to identify as the size of deep burns increases beyond 20% of total body surface area.
Burn wound closure using permanent skin replacement materials
Authors: Tompkins Ronald G. , Burke John F.
Published: August 2005

Over the past decade, very significant advances in the development of clinically useful, permanent skin replacement materials have taken place. The most prominent and successful approaches to the physiological closure of an open wound have been either by creating a totally artificial dermal matrix material, by using culture techniques to expand cell populations for autologous transplantation, or by using a combination of these methods. As a result of substantial early progress in this field, permanent skin replacement materials as a treatment modality promise significant contributions to improved wound management and increased survival rates for patients with devastating soft tissue destruction such as massive burn injuries.
Evaluation of the laparoscopic cholecystectomy on patients with simple and complicated cholecystolithiasis
Authors: Fabre Jean M. , Pyda Przemyslaw , de Charles Seguin des Hons , Lepage Bernard , Balmes Michel , Baumel Hughes , Domergue Jacques
Published: August 2005

Laparoscopic cholecystectomy is now a well described method for the treatment of cholelithiasis. The purpose of this paper is to define its implementation, limits, risks and indications. Following a prospective method, the results of this treatment were compared in 187 patients with simple cholelithiasis and 75 patients with complicated cholelithiasis. Cholecystectomy was performed with a straight optic introduced through the paraumbilical region, and coupled with video camera. Two, 3, or 4 other trocars were inserted and placed as required by anatomic conditions. In the group with simple cholelithiasis, laparoscopic cholecystectomy was performed in 99% of the patients while in the group with complicated cholelithiasis the procedure was achieved in 75% of the patients. Immediate laparotomy was done in 1% and 25% of cases respectively in both groups. No interventional mortality occurred. Post‐operative complications have been acceptable (1.6% and 2.7%), with no late complications reported. Our study shows that laparoscopic cholecystectomy is feasible in the majority of cases of complicated cholelithiasis and that the main advantages of this method were retained.
The surgical management of benign and malignant thyroid neoplasms in marshall islanders exposed to hydrogen bomb fallout
Authors: Dobyns Brown M. , Hyrmer Barbara A.
Published: August 2005

On March 1, 1954, a serious fallout accident occurred during the United States atomic testing program at Bikini in the Trust Territory of the Pacific Islands. Following the detonation of a large thermonuclear device (known as Bravo) an unexpected shift in winds resulted in deposition of radioactive debris on several inhabited atolls in the Marshall Islands. During the early post‐detonation period military, sea, and air surveys traced the hottest portion of the parabolic cloud as it drifted in an ever widening pattern of diminishing concentration eastward and southeast of Bikini. The center of the cloud passed North of the Rongelap Atoll, which was the nearest inhabited atoll. This report concerns the development of thyroid lesions, the special circumstances encountered during thyroid surgery, and the results of the surgical management of benign and malignant lesions that were subsequently encountered in this population.
Omental Flap in Pancreaticoduodenectomy for Protection of Splanchnic Vessels
Authors: Maeda Atsuyuki , Ebata Tomoki , Kanemoto Hideyuki , Matsunaga Kazuya , Bando Etsuro , Yamaguchi Shigeki , Uesaka Katsuhiko
Published: August 2005

Intraabdominal bleeding, the most life‐threatening complication following pancreaticoduodenectomy (PD), most often is associated with failure of a pancreaticojejunostomy anastomosis or with intraabdominal infection. We investigated whether placement of an omental flap around the splanchnic vessels in PD could reduce the occurrence of intraabdominal bleeding and other postoperative complications. One hundred consecutive patients who underwent PD at the authors’ institution between January 2000 and October 2004 were enrolled in this prospective study. After dissection of the hepatoduodenal ligament, the major splanchnic arteries and the portal vein were covered by the omental flap. Preoperative condition, incidence of pancreatic fistula, intra‐abdominal bleeding, other complications, treatment mortality, and hospital stay were analyzed for interrelationships. The frequency of pancreatic fistula (20%) differed little from those in previous reports. However, intraabdominal bleeding was observed in only 1 (1.0%) patient, who was considered to have too thin a flap. No intraabdominal abscess was encountered. No mortality or complications occurred in relation to the omental flap. Thus, wrapping an omental flap around dissected splanchnic vessels in PD reduced postoperative intraabdominal bleeding and infection, but failed to prevent pancreatic fistulas.
Mammalian mitochondria contain a soluble acyl carrier protein
Authors: Cronan John E. , Fearnley Ian M. , Walker John E.
Published: August 2005

Plant and fungal mitochondria contain type II fatty acid synthesis systems closely related to those of bacteria in which the individual reactions are catalyzed by separate soluble proteins acting on intermediates bound to acyl carrier protein (ACP). Mammalian mitochondria are thought to synthesize fatty acids, but evidence for the key ACP component was lacking since the only reported ACP was the SDAP subunit of the membrane‐bound NADH:ubiquinone oxidoreductase, We report that most of the SDAP is found in the soluble (matrix) fraction of bovine heart mitochondria and is therefore available to carry the intermediates of type II fatty acid synthesis.
Regulation of human erythrocyte glyceraldehyde‐3‐phosphate dehydrogenase by ferriprotoporphyrin IX
Authors: Omodeo Salè Fausta , Vanzulli Elisa , Caielli Simone , Taramelli Donatella
Published: August 2005

Erythrocyte glyceraldehyde‐3‐phosphate dehydrogenase (G3PD) is a glycolytic enzyme containing critical thiol groups and whose activity is reversibly inhibited by binding to the cell membrane. Here, we demonstrate that the insertion of ferriprotoporphyrin IX (FP) into the red cell membranes exerts two opposite effects on membrane bound G3PD. First, the enzyme is partially inactivated through oxidation of critical thiols. Dithiothreitol restores part of the activity, but some critical thiols are irreversibly oxidized or crosslinked to products of FP‐induced lipid peroxidation. Second, G3PD binding to the membrane is modified and the enzyme is activated through displacement into the cytosol and/or release from its binding site.
Emergency obstetric care in Pakistan: Potential for reduced maternal mortality through improved basic EmOC facilities, services, and access
Authors: Ali M. , Hotta M. , Kuroiwa C. , Ushijima H.
Published: August 2005

Objective: To ascertain and compare compliance with UN emergency obstetric care (EmOC) recommendations by public health care centers in Pakistan's Punjab and Northwest Frontier Province (NWFP) provinces. Method: Cross‐sectional data were collected from July through September 2003 using UN process indicators. From each province, 30% of districts (n = 19); were randomly selected; all public health facilities providing EmOC services (n = 170) were included. Results: The study found that out of 170 facilities only 22 were providing basic and 37 comprehensive EmOC services in the areas studied. Only 5.7% of births occurred in EmOC health facilities. Met need was 9% and 0.5% of women gave birth by cesarean section. The case fatality rate was a low 0.7%, probably due to poor record keeping. Access and several indicators were better in NWFP than in Punjab. Conclusion: Almost all indicators were below UN recommendations. Health policy makers and planners must take immediate, appropriate measures at district and hospital levels to reduce maternal mortality.
Who said politicians cannot be conservativeŒ Comparing reform capacity in the Czech and Hungarian telecom administrations
Authors: Nørgaard Ole , Møller Luise Pape
Published: August 2005

Hungary outpaced the Czech Republic in reforms of the telecom sector during the first decade of transition. In the Czech Republic, prices remained low, competition limited and the state maintained ownership of the incumbent operator. Hungary, in contrast, experienced extensive privatization, liberalization of prices and some deregulation. This outcome challenges the assumption that institutional veto points (frameworks that constrain or enable political agents) manipulated by conservative bureaucrats hindered the initiatives of reform minded politicians in Hungary, while allowing reforms to occur in the also reforming Czech Republic. It is shown that the Czech telecom administration had only a few possibilities to block policy decisions through veto points. The slow reform process was rather a result of a conscious political strategy of maintaining control and accommodating a conservative constituency in context of a relatively sound economic environment. In Hungary, bureaucrats acting as agents of change pushed though the reforms despite opposition from politicians. This insight challenges the traditional picture of civil servants in post-communist systems as inherently conservative and anti-reform.
Ultra‐low‐frequency electrodynamics of the magnetosphere‐ionosphere interaction
Authors: Streltsov A. V. , Lotko W.
Published: August 2005

The results presented in this paper provide an explanation for electromagnetic oscillations with frequencies much less than the fundamental eigenfrequency of the magnetosphere measured in the regions where the ionospheric conductivity is low and a small‐amplitude, large‐scale electric field in the ionosphere exists. This study is based on numerical simulations of a reduced two‐fluid MHD model describing propagation of dispersive Alfvén waves in the highly inhomogeneous magnetospheric plasma and interaction between these waves and the active ionosphere. Simulations show that electromagnetic oscillations with frequency below 10 mHz can be generated by a strongly nonlinear interaction between magnetic field‐aligned currents and the ionosphere called ionospheric feedback instability. To produce oscillations in ULF frequency range, this mechanism requires neither very stretched geometry of the ambient magnetic field nor coupling between shear and slow MHD waves. These features of the ionospheric feedback mechanism makes it particularly suitable for the explanation of the ULF oscillations detected on midlatitude and low‐latitude, nightside field lines when the background ionospheric conductivity is low and the magnitude of the perpendicular electric field in the ionosphere is small.
Response of the Pacific and Atlantic oceans to interannual variations in net atmospheric freshwater
Authors: Huang Boyin , Mehta Vikram M.
Published: August 2005

The response of the Pacific and Atlantic Oceans to net atmospheric freshwater (evaporation minus precipitation (EmP)) between 1988 and 2000 was studied using a global ocean general circulation model developed in the Massachusetts Institute of Technology. Evaporation estimates from the Goddard Satellite Surface Turbulent Fluxes and precipitation estimates from the Global Precipitation Climatology Project were used. Model simulations showed that the spatial distribution of the average sea surface salinity (SSS) changes during the 1988–2000 period resembled that of average EmP changes, because SSS changes were primarily associated with anomalous vertical mixing forced by the anomalous EmP. The spatial distribution of average near‐surface temperature anomalies, however, was different from those of average EmP and SSS anomalies. Analyses indicated that temperature changes in the subtropical North and South Pacific resulted from anomalous heat advection which, in turn, resulted from changes in the subtropical gyre circulations. Temperature changes in the tropical Pacific were associated with anomalous heat advection due to changes in the South Equatorial Current (SEC). Furthermore, the changes in the subtropical gyres and the SEC resulted largely from anomalous EmP in the subtropical Pacific. Temperature changes in the Atlantic, however, were largely associated with vertical mixing changes due to anomalous EmP. Observed interannual variations of SSS in the Western Pacific Warm Pool were simulated successfully. A large difference between simulated and observed SSS, however, was found in the central equatorial Pacific. Simulated SSS and temperature varied at interannual and longer timescales in most of the Pacific and Atlantic Oceans. Large changes in SSS and temperature due to anomalous EmP in the Pacific and Atlantic strongly suggest that EmP variability can play an important role in ocean and climate variabilities at interannual and longer timescales.
Error analysis for GNSS radio occultation data based on ensembles of profiles from end‐to‐end simulations
Authors: Steiner A. K. , Kirchengast G.
Published: August 2005

Radio occultation (RO) observations using the Global Navigation Satellite System (GNSS) globally provide high quality atmospheric data which can support the advancement of climate monitoring and modeling as well as the improvement of numerical weather prediction. In order to make optimal use of the data, e.g., via data assimilation systems, the characterization of measurement errors is of importance. Within this context we present results of an empirical error analysis based on quasi‐realistically simulated GNSS RO data. The study is based on an end‐to‐end forward‐inverse simulation involving (1) modeling of the neutral atmosphere and ionosphere, (2) simulation of RO observations, (3) forward modeling of excess phase observables including realistic observation system error modeling, and (4) retrieval of atmospheric parameters. Occultation observations were simulated for one day from which an ensemble of 300 occultation events was chosen, with 100 events in each of three latitude bands (low, middle, high). Phase path profiles were computed showing a realistic rms error of the ionosphere corrected phase paths of 2–3 mm at mesospheric and stratospheric heights at 10 Hz sampling rate. Atmospheric profiles were retrieved by applying a dry air retrieval in the stratosphere and an optimal estimation retrieval in the troposphere. The retrieved profiles were referenced to the “true” co‐located ones of the analysis field of the European Centre for Medium‐range Weather Forecasts (ECMWF). We empirically estimated bias profiles and covariance matrices (standard deviations and correlation functions) for the retrieval products such as bending angle, refractivity, pressure, geopotential height, temperature, and specific humidity. Results include the refractivity error showing a relative standard deviation of 0.1–0.75% and a relative bias of <0.1% at 5–40 km height. Temperature exhibits a standard deviation of 0.2–1 K at 3–31 km height and a bias of <0.1–0.5 K below 33 km and of <0.1 K below 20 km. Simple analytical error covariance formulations are presented for refractivity, as deduced from the empirically estimated covariance matrices. The reasonably realistic error estimates presented are a good basis for further retrieval algorithm improvements and for proper specification of observational errors in data assimilation systems.
Oxygen isotopic fractionation in the photochemistry of nitrate in water and ice
Authors: McCabe J. R. , Boxe C. S. , Colussi A. J. , Hoffmann M. R. , Thiemens M. H.
Published: August 2005

We recently reported the first multiple oxygen isotope composition of nitrate (NO3−) in ice cores (Alexander et al., 2004). Postdepositional photolysis and volatilization may alter the isotopic signatures of snowpack nitrate. Therefore the precise assessment of the geochemical/atmospheric significance of O‐isotopic signatures requires information on the relative rates of photolysis (λ > 300 nm) of N16O3−, N16O217O−, and N16O218O− in ice. Here we report on 17O‐ and 18O‐fractionation in the 313‐nm photolysis of 10‐mM aqueous solutions of normal Fisher KNO3 (i.e., Δ17O = −0.2 ± 0.2‰) and 17O‐enriched USGS‐35 NaNO3 (Δ17O = 21.0 ± 0.4‰) between −30° and 25°C. We found that Fisher KNO3 undergoes mass‐dependent O‐fractionation, i.e., a process that preserves Δ17O = 0. In contrast, Δ17O in USGS‐35 NaNO3 decreased by 1.6 ± 0.4‰ and 2.0 ± 0.4‰ at 25°C, 1.2 ± 0.4‰ and 1.3 ± 0.4‰ at −5°C, and 0.2 ± 0.4‰ and 1.1 ± 0.4‰ at −30°C, after 12 and 24 hours, respectively. Since the small quantum yield (∼0.2%) of NO3− photodecomposition into (NO2 + OH) is due to extensive cage recombination of the primary photofragments rather than to intramolecular processes, the observed Δ17O decreases likely reflect competitive O‐isotope exchange of geminate OH‐radicals with H2O (Δ17O = 0) and escape from the solvent cage, in addition to residual O‐isotope mixing of the final photoproducts NO, NO2, NO2−, with H2O. At the prevailing low temperatures, photochemical processing will not impair the diagnostic value of O‐isotopic signatures in tracing the chemical ancestry of nitrate in polar ice.
Contribution of particulate nitrate to airborne measurements of total reactive nitrogen
Authors: Miyazaki Y. , Kondo Y. , Takegawa N. , Weber R. J. , Koike M. , Kita K. , Fukuda M. , Ma Y. , Clarke A. D. , Kapustin V. N. , Flocke F. , Weinheimer A. J. , Zondlo M. , Eisele F. L. , Blake D. R. , Liley B.
Published: August 2005

Simultaneous measurements of speciated, total reactive nitrogen (NOy) and particulate NO3− (particle diameter <1.3 μm) were made on board the NASA P‐3B aircraft over the western Pacific in February–April 2001 during the Transport and Chemical Evolution over the Pacific (TRACE‐P) experiment. Gas‐phase and particulate NOy was measured using a gold tube catalytic converter. For the interpretation of particulate NOy, conversion efficiencies of particulate NH4NO3, KNO3, NaNO3, and Ca(NO3)2 were measured in the laboratory. Only NH4NO3 showed quantitative conversion, and its conversion efficiency was as high as that for HNO3. NOy measured on board the aircraft was found to be systematically higher by 10–30% than the sum of the individual NOy gas components (∑(NOy)i) at 0–4 km. Particulate NO3− concentrations measured by a particle‐into‐liquid sampler (PILS) were nearly equal to NOy − ∑(NOy)i under low‐dust‐loading conditions. The PILS data showed that the majority of the particulate NO3− was in the form of NH4NO3 under these conditions, suggesting that NH4NO3 particles were quantitatively converted to detectable NO by the NOy converter, consistent with the laboratory experiments. The contribution of particulate NO3− to NOy was most important at 0–2 km, where NO3− constituted 10–30% of NOy during TRACE‐P. On average, the amounts of particulate NO3− and gas‐phase HNO3 were comparable in this region.
Thermospheric responses to gravity waves: Influences of increasing viscosity and thermal diffusivity
Authors: Vadas Sharon L. , Fritts David C.
Published: August 2005

A gravity wave anelastic dispersion relation is derived that includes molecular viscosity and thermal diffusivity to explore the damping of high‐frequency gravity waves in the thermosphere. The time dependence of the wave amplitudes and general ray trace equations are also derived. In the special case that the thermal structure is isothermal and the Prandtl number (Pr) equals 1, exact linear solutions are obtained. For high‐frequency gravity waves with ωIr/N ≪ 1 an upward propagating gravity wave dissipates at an altitude given by ≃ z1 + H ln(ωIr/2H∣m∣3ν1), where H is the density scale height, N is the buoyancy frequency, ν1 is the viscosity at z = z1, and ωIr and m are the gravity wave intrinsic frequency and vertical wave number, respectively. Thus high‐frequency gravity waves with large vertical wavelengths dissipate at the highest altitudes, resulting in momentum and energy inputs extending to very high altitudes. We find that the vertical wavelength of a gravity wave with an initially large vertical wavelength decreases significantly by the time it dissipates just below where it begins to reflect. The effect of diffusion on a gravity wave is similar to the effect of shear in the sense that as the molecular viscosity and thermal diffusivity increase due to decreasing background density, the intrinsic frequency plus mν/H decreases and the vertical wave number increases in order to satisfy the dispersion relation for Pr = 1. We also briefly explore the results with different Prandtl numbers using numerical ray tracing. Gravity waves in a Pr = 0.7 environment dissipate just a few kilometers below those in a Pr = 1 environment when H = 7 km, showing the utility of the analytic, Pr = 1 solutions.
A 25‐year data record of atmospheric ozone in the Pacific from Total Ozone Mapping Spectrometer (TOMS) cloud slicing: Implications for ozone trends in the stratosphere and troposphere
Authors: Ziemke J. R. , Chandra S. , Bhartia P. K.
Published: August 2005

The newly reprocessed solar backscatter ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) version 8 data from 1979 to 2003 are used to estimate the seasonal cycle, latitude dependence, and long‐term trends in ozone averaged over the Pacific region (120°W to 120°E) in three broad layers of the atmosphere: upper stratosphere (32 hPa and above), lower stratosphere (32 hPa to tropopause), and the troposphere. The ozone amount in these layers is derived by first determining stratospheric column ozone in the Pacific from TOMS using deep convective clouds, which are numerous in the region. Tropospheric column ozone (TCO) for the Pacific is then determined by taking the difference between total column ozone and stratospheric column ozone. This “cloud‐slicing” technique is extensively tested from the tropics extending to ±60° latitude using stratospheric ozone data from the Stratospheric Aerosol and Gas Experiment II instrument. The validity of the cloud‐slicing technique in obtaining TCO is also tested using data from ozonesondes over a wide range of latitude. SBUV ozone profiles are used to measure upper stratospheric column ozone for the Pacific region. Lower stratospheric column ozone is then derived from the difference between stratospheric column ozone and upper stratospheric column ozone. This process yields a unique 25‐year record of Pacific mean ozone in three atmospheric layers covering all latitudes and seasons. The analysis of the data shows that the seasonal cycles, latitude dependence, and trends in these layers are substantially different. Over the 25‐year record most ozone depletion has occurred in the lower stratosphere below ∼25 km altitude. In middle and high latitudes, ozone losses are 3–4 times larger in the lower stratosphere compared with the upper stratosphere, even though the ozone amounts in the two regions are about the same. For the troposphere, TCO shows a statistically significant upward trend in the midlatitudes of both hemispheres but not in the tropics.
Postcorrelation radio frequency interference excision at low frequencies
Authors: Lane W. M. , Cohen A. S. , Kassim N. E. , Lazio T. J. W. , Perley R. A. , Cotton W. D. , Greisen E. W.
Published: August 2005

We present examples of radio frequency interference from our experience with editing data from the Very Large Array and Very Long Baseline Array at frequencies of 74 and 330 MHz and discuss postcorrelation excision schemes commonly used at low radio frequencies (<1 GHz), including those employed for targeted observations, as well as broader brush automated schemes appropriate for surveys and other large data sets. We elaborate on the strengths and weaknesses of currently employed procedures, with an eye to providing a summary of existing methods for those developing future, more sophisticated postdetection data editing algorithms as well as new low‐frequency instruments such as the Long Wavelength Array and Low Frequency Array.
Diurnal variations in the rate of dissipation of turbulent energy in the equatorial upper mesosphere–lower thermosphere
Authors: Roper R. G. , Brosnahan J. W.
Published: August 2005

The diurnal variation of the rate of dissipation of turbulent energy over Arecibo (18°N, 67°W) for the 1989 Arecibo Initiative on Dynamics of the Atmosphere (AIDA '89) campaigns from 1–10 April and 2–9 May 1989 have been estimated using the random velocity field deduced from imaging Doppler interferometry data. A method for extraction of the vertical component of the gravity wave spectrum has been applied to the random velocity. There is a tendency for the turbulence to maximize at dawn and dusk. Estimates of the RMS vertical gravity wave component range from 2 to 5 m s−1, and estimates of the RMS turbulent energy range from 5 to 100 mW kg−1. Estimates of the vertical eddy diffusivity have also been calculated, ranging from <50 to 300 m2 s−1. The buoyancy scale ranges from <100 m to 1 km. A cautionary note is added regarding the applicability of the Kolmogorov theory above 100 km.
Oligocene range uplift and development of plateau morphology in the southern central Andes
Authors: Carrapa B. , Adelmann D. , Hilley G. E. , Mortimer E. , Sobel E. R. , Strecker M. R.
Published: August 2005

The Puna‐Altiplano plateau in South America is a high‐elevation, low internal relief landform that is characterized by internal drainage and hyperaridity. Thermochronologic and sedimentologic observations from the Sierra de Calalaste region in the southwestern Puna plateau, Argentina, place new constraints on early plateau evolution by resolving the timing of uplift of mountain ranges that bound present‐day basins and the filling pattern of these basins during late Eocene‐Miocene time. Paleocurrent indicators, sedimentary provenance analyses, and apatite fission track thermochronology indicate that the original paleodrainage setting was disrupted by exhumation and uplift of the Sierra de Calalaste range between 24 and 29 Ma. This event was responsible for basin reorganization and the disruption of the regional fluvial system that has ultimately led to the formation of internal drainage conditions, which, in the Salar de Antofalla, were established not later than late Miocene. Upper Eocene‐Oligocene sedimentary rocks flanking the range contain features that suggest an arid environment existed prior to and during its uplift. Provenance data indicate a common similar source located to the west for both the southern Puna and the Altiplano of Bolivia during the late Eocene‐Oligocene with sporadic local sources. This suggests the existence of an extensive, longitudinally oriented foreland basin along the central Andes during this time.
PSEM_2D: A physically based model of erosion processes at the plot scale
Authors: Nord Guillaume , Esteves Michel
Published: August 2005

This paper presents the development and first applications of the Plot Soil Erosion Model 2D (PSEM_2D). Infiltration is computed using a Green and Ampt model, overland flow is computed using the depth‐averaged two‐dimensional unsteady flow equations (Saint Venant equations), and soil erosion is computed by combining the equation of mass conservation of sediment and a detachment‐transport coupling model for erosion by runoff. A shear stress approach is used to determine the transport capacity. The formation of a covering cohesionless layer as a result of depositing sediment and action of rainfall impact before runoff is considered. The erosion processes involved are rainfall and runoff detachment of original soil, rainfall redetachment, and overland flow entrainment of sediment from the deposited layer, and deposition. The model uses a single representative particle size. Complex rainfall events on natural slopes can be simulated. The accuracy of the predictions for erosion of planar surfaces is tested by comparison with observed data obtained from experiments and with an analytical solution. Good agreement between the calculated results and measured data was found. A sensitivity analysis was also performed. Limitations related to the description of overland flow on plane soil surface are pointed out. Finally, an application to a nonplanar natural surface of 75 m2 illustrated the distribution of erosion and sedimentation over the plot.
Simulation of gaseous diffusion in partially saturated porous media under variable gravity with lattice Boltzmann methods
Authors: Chau Jessica Furrer , Or Dani , Sukop Michael C.
Published: August 2005

Liquid distributions in unsaturated porous media under different gravitational accelerations and corresponding macroscopic gaseous diffusion coefficients were investigated to enhance understanding of plant growth conditions in microgravity. We used a single‐component, multiphase lattice Boltzmann code to simulate liquid configurations in two‐dimensional porous media at varying water contents for different gravity conditions and measured gas diffusion through the media using a multicomponent lattice Boltzmann code. The relative diffusion coefficients (Drel) for simulations with and without gravity as functions of air‐filled porosity were in good agreement with measured data and established models. We found significant differences in liquid configuration in porous media, leading to reductions in Drel of up to 25% under zero gravity. The study highlights potential applications of the lattice Boltzmann method for rapid and cost‐effective evaluation of alternative plant growth media designs under variable gravity.
The first South Atlantic hurricane: Unprecedented blocking, low shear and climate change
Authors: Pezza Alexandre Bernardes , Simmonds Ian
Published: August 2005

In March 2004 the first‐ever reported hurricane in the South Atlantic hit southern Brazil. Here we show that Catarina initiated as an extratropical cyclone in a frontal system, undergoing Tropical Transition two days later under persistent low vertical wind shear over near‐average water temperatures. The trajectory derived from an automatic tracking scheme showed a rare loop before the cyclone approached the coast for a second time. The vertical structure presented anticyclonic relative vorticity above and a small 300 hPa warm core embedded in a cold area. A mid‐to‐high latitude‐blocking index showed that the five days before the genesis were in the 0.6% first percentile of intensity considered over the last 25 years, followed by an unprecedented combination with low shear. The observed and predicted trends towards an increasingly positive phase of the Southern Annular Mode in global warming scenarios could favor similar conditions, increasing the probability of more Tropical Cyclones in the South Atlantic.
European spring and autumn temperature variability and change of extremes over the last half millennium
Authors: Xoplaki E. , Luterbacher J. , Paeth H. , Dietrich D. , Steiner N. , Grosjean M. , Wanner H.
Published: August 2005

We evaluate variability, trends, uncertainties, and change of extremes of reconstructed and observed European spring and autumn temperature back to 1500. Spring and autumn temperature experienced systematic century‐scale cooling compared to present conditions. The coldest springs appeared during the Maunder Minimum (ΔT = −1 K wrt 1901–2000). The amplitude of spring temperature variations at decadal and multidecadal scales doubles that of autumn and is most expressed in northeastern Europe. The decade 1995–2004 was very likely the warmest of the last half millennium. Anomalously warm springs and autumns have generally become more extreme in recent decades. However, the recent changes are statistically not significant with respect to the pre‐industrial period.
Dynamic relationship between the outer radiation belt and the plasmapause during March–May 2001
Authors: Goldstein J. , Kanekal S. G. , Baker D. N. , Sandel B. R.
Published: August 2005

The dynamic spatial relationship between the outer radiation belt electrons and the plasmapause during the two‐month period 30 March–30 May 2001 is determined using SAMPEX daily averaged fluxes of 2–6 MeV electrons and IMAGE EUV 10‐min global images of the plasmasphere. In two events, severe erosion moved the plasmapause inside L = 2 and 2–3 days later the outer belt was located in the normal slot region. We determine on what time scale the outer belt location responds to changes in plasmapause location and find the inner extent of the outer belt matched (to within ΔL ≈ 0.1) with a 3.5‐day running average of the plasmapause location, implying a ≥3.5‐day loss time scale from pitch‐angle scattering by plasmaspheric hiss and EMIC waves.
A review of the solar cycle length estimates
Authors: Benestad R. E.
Published: August 2005

New estimates of the solar cycle length are calculated from an up‐to‐date monthly sunspot record using a novel but mathematically rigorous method involving multiple regression, Fourier approximation, and analytical expressions for the first derivative based on calculus techniques. The sensitivity of the estimates to smoothing are examined and the analysis is used to identify possible systematic changes in the sun. The solar cycle length analysis indicates a pronounced change in the sun around 1900, before which the estimates fluctuate strongly and after which the estimates show little variability. There have been speculations about an association between the solar cycle length and Earth's climate, however, the solar cycle length analysis does not follow Earth's global mean surface temperature. A further comparison with the monthly sunspot number, cosmic galactic rays and 10.7 cm absolute radio flux since 1950 gives no indication of a systematic trend in the level of solar activity that can explain the most recent global warming.
Sensitivity of groundwater monitoring networks to contaminant source width for various seepage velocities
Authors: Hudak Paul F.
Published: August 2005

This study evaluated the effect of contaminant source width on the detection efficiency of five, six, and seven well monitoring networks for a range of groundwater seepage velocities. Wells were positioned downgradient of a rectangular landfill oriented obliquely to groundwater flow. A buffer zone boundary, establishing a distance limit within which contaminant plumes should be detected, was located 100 m from the landfill's downgradient corner. Various combinations of seepage velocity, from 0.01 to 10.0 m/d, and contaminant source width, from 0.1 to 5.0 m, were input to a computer model, which computed the detection capability of alternative monitoring networks. Smaller networks were more sensitive to changes in contaminant source width and seepage velocity. The smallest network showed a 21.6% greater range in detection efficiency than the largest network over the range of input values. Each network was considerably more sensitive to contaminant source width than seepage velocity, suggesting uncertainty in contaminant source width warrants attention in field applications. The type of analysis illustrated in this study may be useful for identifying appropriate monitoring networks given uncertainty in contaminant source width and seepage velocity at field settings.
An analytical solution for slug tracer tests in fractured reservoirs
Authors: Shan Chao , Pruess Karsten
Published: August 2005

The transport of chemicals or heat in fractured reservoirs is strongly affected by the fracture‐matrix interfacial area. Under unsaturated conditions, such as in vapor‐dominated geothermal reservoirs, this area can be estimated from inert gas tracer tests that produce a characteristic tail in tracer breakthrough curves (BTCs). For water‐saturated conditions, molecular diffusion is orders of magnitude smaller, and tails in BTCs from diffusive exchange between fractures and matrix are too weak to be practically useful as a characterization tool for fracture spacings of practical interest. However, recent studies suggest that reversibly sorbing solute tracers can generate strong tails in BTCs that may allow a determination of the fracture‐matrix interfacial area. To theoretically explore such a useful phenomenon, this paper develops an analytical solution for BTCs in slug tracer tests in a water‐saturated fractured reservoir, idealized here as a set of uniformly spaced plane, parallel, identical fractures. The solution shows that increased sorption should have the same effect on BTCs as an increase of the diffusion coefficient. The solution is useful for understanding transport mechanisms, verifying numerical codes, and identifying appropriate chemicals as tracers for the characterization of fractured reservoirs.
Neutralization of solvated protons and formation of noble-gas hydride molecules: Matrix-isolation indications of tunneling mechanisms?
Authors: Khriachtchev Leonid , Lignell Antti , Räsänen Markku
Published: August 2005

The (NgHNg)+ cations (Ng=Ar and Kr) produced via the photolysis of HF∕Ar, HF∕Kr, and HBr∕Kr solid mixtures are studied, with emphasis on their decay mechanisms. The present experiments provide a large variety of parameters connected to this decay phenomenon, which allows us to reconsider various models for the decay of the (NgHNg)+ cations in noble-gas matrices. As a result, we propose that this phenomenon could be explained by the neutralization of the solvated protons by electrons. The mechanism of this neutralization reaction probably involves tunneling of an electron from an electronegative fragment or another trap to the (NgHNg)+ cation. The proposed electron-tunneling mechanism should be considered as a possible alternative to the literature models based on tunneling-assisted or radiation-induced diffusion of protons in noble-gas solids. As a novel experimental observation of this work, the efficient formation of HArF molecules occurs at 8K in a photolyzed HF∕Ar matrix. It is probable that the low-temperature formation of HArF involves local tunneling of the H atom to the Ar–F center, which in turn supports the locality of HF photolysis in solid Ar. In this model, the decay of (ArHAr)+ ions and the formation of HArF molecules observed at low temperatures are generally unconnected processes; however, the decaying (ArHAr)+ ions may contribute to some extent to the formation of HArF molecules.