bluuebunny/crossref_metadata_2025 huggingface dataset:
Does “Cystic” Biliary Atresia Represent a Distinct Clinical and Etiological Subgroup? A Series of Three Cases
Authors: De Matos Vera , Erlichman Jessi , Russo Pierre A. , Haber Barbara A.
Published: November 2005

We describe a unique series of 3 cases of biliary atresia (BA) associated with a choledochal cyst. All 3 children presented with jaundice at birth and had no other abnormalities. Although these children had a fetal form of BA, their presentation and outcome differed from those of biliary atresia splenic malformation syndrome (BASM), the well-described form of early onset BA. Unlike those with BASM, these children had no other associated malformations, had a normal birth weight, and did not yet require a liver transplant. We believe that the present series of patients and their associated pathology may represent a distinct phenotype with a common, prenatally acquired etiology that is different from other fetal forms of BA, such as BASM, and from patients who present with the classic perinatal form of BA.
Focal Segmental Glomerulosclerosis Associated with Mitochondrial Cytopathy: Report of Two Cases with Special Emphasis on Podocytes
Authors: Güçer Şafak , Talim Beril , Aşan Esin , Korkusuz Petek , Özen Seza , Ünal Şule , Kalkanoğlu Serap H. , Kale Gülsev , Çağlar Melda
Published: November 2005

We report two children with focal segmental glomerulosclerosis (FSGS) associated with mitochondrial cytopathy (MC). Case 1 was diagnosed as MC with the findings of ptosis, ophthalmoplegia, failure to thrive, high serum lactate and pyruvate levels, ragged red fibers in muscle biopsy and the common 4.9 kb deletion in mtDNA when she was four years old. She subsequently developed FSGS four years later. Case 2 was a four month-old girl presenting with feeding difficulty from birth, with vomiting, seizures and nystagmoid eye movements, nephrotic proteinuria and hematuria. Renal biopsy revealed FSGS. Ultrastructural study demonstrated markedly pleomorphic mitochondria in podocytes with a severe effacement of foot processes. The analyses of muscle biopsy and skin fibroblasts for respiratory chain enzymes were found to be normal, while mitochondrial DNA analysis revealed the population of a single deleted mtDNA in the heteroplasmic state. The present cases illustrate FSGS as a rare renal complication of mitochondrial disease and provide further evidence of podocytes possessing abnormal mitochondria which may cause glomerular epithelial cell damage leading to glomerulosclerosis.
Alpha-Thalassemia Major Presenting in a Term Neonate without Hydrops
Authors: Monaco Sara E. , Davis Mary , Huang Ay-chyn , Bhagat Govind , Baergen Rebecca N. , Lorenz John M. , Chung Wendy K. , Thaker Harshwardhan M.
Published: November 2005

We describe the clinical and pathologic features of an unusual case of alpha-thalassemia major in a patient who survived to term and lived for 9 days. The neonate was nonhydropic and the clinical picture was dominated by severe hypoxia with pulmonary hypertension. The diagnosis was not suspected until postnatal examination of the blood smear, which prompted the performance of hemoglobin electrophoresis and subsequent molecular confirmation. This case illustrates that alpha-thalassemia major should be in the differential diagnosis of hypoxic neonates even in the absence of hydrops.
Genetic Haploinsufficiency as a Phenotypic Determinant of a Deletion 13q Syndrome
Authors: Kasyan Armen G. , Benirschke Kurt
Published: November 2005

Two cases of newborns with deletion 13q syndrome were identified and studied using electron microscopy and histologic, immunohistochemical, and special stained sections. We reviewed the published literature on genes that are haploinsufficient in the deletion 13q syndrome. The complexity of the deletion 13q syndrome phenotype is due at least in part to the haploinsufficiency of dosage-sensitive genes. Future studies need to be performed to identify their precise role in the cellular function and the development of the deletion 13q syndrome phenotype.
Multiple Gastric Stromal Tumors in a Child without Syndromic Association Lacks Common KIT or PDGFRα Mutations
Authors: O'Sullivan Maureen J. , McCabe Amanda , Gillett Peter , Penman Iain D. , MacKinlay Gordon A. , Pritchard on
Published: November 2005

A diagnosis of multiple gastric stromal tumors that were nonmetastatic at presentation was made in an 11-year-old girl who presented with hematemesis. Gastrointestinal stromal tumor (GIST) is a rare diagnosis in childhood and reported multiple lesions are generally seen in the context of familial disease, occasionally with syndromic associations. Although there are no reports of genetic mutation in cases of pediatric GIST, very many cases of multiple GISTs investigated on a molecular level have shown germline KIT or platelet-derived growth factor receptor-α mutation; these were familial cases. Despite the negative family history in our patient, the multiplicity of lesions in such a young patient raised concern for a genetic predisposition and prompted extensive molecular workup. Repeat evaluation of distinct aliquots of tumor tissue by polymerase chain amplification followed by sequence analysis of selected coding sequences of KIT and platelet-derived growth factor receptor-α previously shown to harbor mutations in GIST, yielded no evidence of even a somatic mutation. This clinically unique case is discussed in the context of a literature review.
Pediatric Renal Cell Carcinomas with Xp11.2 Rearrangements are Immunoreactive for hMLH1 and hMSH2 Proteins
Authors: Rakheja Dinesh , Kapur Payal , Tomlinson Gail E. , Margraf Linda R.
Published: November 2005

Alveolar soft part sarcoma and pediatric renal cell carcinoma share a similar chromosomal abnormality, t(X;17)(p11.2;q25). Recently, it has been suggested that the inactivation of DNA mismatch repair genes hMLH1 and hMSH2 may play an additional role in the pathogenesis of alveolar soft part sarcoma. Immunohistochemical expression of the proteins hMLH1 and hMSH2 is indicative of the activation status of the corresponding genes. We performed immunohistochemistry for hMLH1 and hMSH2 in 4 cases of pediatric renal cell carcinomas with Xp11.2 rearrangements. All cases showed nuclear immunoreactivity for both proteins, although the staining was patchy. Our study demonstrates that inactivation of the DNA mismatch repair genes hMLH1 and hMSH2 does not appear to play a role in the tumorigenesis of pediatric renal cell carcinomas with Xp11.2 rearrangements.
Expression of Inhibitor-of-Apoptosis Protein (IAP) Livin by Neuroblastoma Cells: Correlation with Prognostic Factors and Outcome
Authors: Kim Dae-Kwang , Alvarado Carlos S. , Abramowsky Carlos R. , Gu Lubing , Zhou Muxiang , Soe Minn-Minn , Sullivan Kevin , George Bradley , Schemankewitz Erwin , Findley Harry W.
Published: November 2005

Livin is a recently identified member of the Inhibitor-of-Apoptosis protein (IAP) family of antiapoptosis proteins, and expression has been reported in melanoma and some types of carcinoma. We evaluated livin expression in paraffin-embedded tumor tissue from 68 patients with neuroblastoma (NB) and 7 NB cell lines by immunoperoxidase using an anti-livin monoclonal antibody. Eighteen (26.5%) of the 68 NB tumor tissues showed high livin expression, 36 (53%) showed low-intermediate expression, and 14 (20.5%) were negative. Similarly, 4 NB cell lines showed high livin expression, and 3 showed intermediate expression. In primary NB tissue, livin was observed mainly in tumor neuropil, an extension of tumor cell cytoplasm, and the cytoplasm itself. By reverse transcriptase–polymerase chain reaction, livin expression was confirmed in all 7 NB lines and in frozen tissue from 1 of 3 primary tumors examined to date, in agreement with immunohistochemical data; both livin α and β isoforms were detected. In the NB cases, we further analyzed the correlation between livin expression and clinical and biological features with established prognostic significance (i.e., age at diagnosis, stage, histology, and MYCN oncogene status), and patients' outcome. Livin expression alone did not appear to have an effect on survival; however, patients with high livin expression and amplified MYCN had significantly decreased survival compared with patients lacking both markers or with either of these markers alone. These results suggest that (a) livin is expressed in primary and cultured neuroblastoma cells and (b) high livin expression may identify a subset of neuroblastoma patients with a particularly poor prognosis among those with MYCN amplified tumors.
Toe-to-Hand Transfers: More Than 20 Years Follow-Up of Five Post-Traumatic Cases
Authors: GÜLGÖNEN A. , GUDEMEZ E.
Published: November 2005

In post-traumatic losses of the thumb and fingers, reconstruction can be performed with success using various combinations of toe transfers. In this study, we have presented second toe and combined toe transfers which have been followed up for more than 20 years. Second toe transfer was used in four patients for reconstruction of the thumb. Combined second and third toe transfer was performed in two patients with a metacarpal hand for finger reconstruction. Long-term follow-up results show that patients with toe-to-hand transfers have acceptable adaptation to the reconstructed hand and good hand function. Toe transfer should be individually planned and carefully executed to obtain optimal results and minimal disability in the donor foot.
An Imagined Geography: Ideology, Urban Space, and Protest in the Creation of Barcelona's “Chinatown”, c.1835–1936
Authors: Ealham Chris
Published: November 2005

Henri Lefebvre famously seized upon the duality of the modern city: how for some it is a space of play and liberation, and for others a centre for power and repression. This article explores this duality through an analysis of the changing historical geography of Barcelona's Raval district, an inner-city working-class community and the birthplace of Catalan industrialization. From the 1920s onwards, elite groups and social commentators defined the Raval as Barcelona's “Chinatown”, an imagined geography that continues to influence historical representations of the area. Through a social history of the Raval, it is argued that the “Chinatown” myth served specific political ends, that it formed part of a cultural project to impose a slum myth on Barcelona's most important and most rebellious working class district. The article concludes with an analysis of how this “moral geography” culminated in far-reaching plans for the moral and physical reordering of the Raval for the benefit of urban elites.
The International Trade-Union Movement and the Founding of the International Labour Organization
Authors: Tosstorff Reiner
Published: November 2005

Accounts of the founding of the International Labour Organization (ILO) usually emphasize the role of social-reformist intellectuals and politicians. Despite the indisputable role of these actors, however, the international labour movement was the actual initiator of this process. Over the course of World War I, the international labour movement proposed a comprehensive programme of protection for the working classes, which, conceived as compensation for its support of the war, was supposed to become an international agreement after the war. In 1919, politicians took up this programme in order to give social stability to the postwar order. However, the way in which the programme was instituted disappointed the high expectations of trade unions regarding the fulfilment of their demands. Instead, politicians offered them an institution that could be used, at best, to realize trade-union demands. Despite open disappointment and sharp critique, however, the revived International Federation of Trade Unions (IFTU) very quickly adapted itself to this mechanism. The IFTU now increasingly oriented its international activities around the lobby work of the ILO.
Beyond Benedict Anderson: Nation-Building and Popular Democracy in Latin America
Authors: Baud Michiel
Published: November 2005

Beyond Imagined Communities. Reading and Writing the Nation in Nineteenth-Century Latin America. Ed. by Sara Castro-Klarén and John Charles Chasteen. Woodrow Wilson Center Press, Washington DC; Johns Hopkins University Press, Baltimore [etc.] 2003. 280 pp. $45.00. (Paper: $22.95.)

Boyer, Christopher Robert. Becoming Campesinos. Politics, Identity, and Agrarian Struggle in Postrevolutionary Michoacán, 1920–1935. Stanford University Press, Stanford (Cal.) 2003. xii, 320 pp. Ill. £45.95.

Forment, Carlos A. Democracy in Latin America, 1760–1900. Volume I, Civic Selfhood and Public Life in Mexico and Peru. [Morality and Society Series.] University of Chicago Press, Chicago [etc.] 2003. xxix, 454 pp. Maps. $35.00; £24.50.

Larson, Brooke. Trials of Nation Making. Liberalism, Race, and Ethnicity in the Andes, 1810–1910. Cambridge University Press, Cambridge [etc.] 2004. xiii, 299 pp. Ill. Maps. $70.00; £45.00. (Paper: $24.99; £17.99.)

Studies in the Formation of the National State in Latin America. Ed. by James Dunkerley. Institute of Latin American Studies, University of London, London, 2002. 298 pp. £14.95; € 20.00; $19.95.
Prospects for survival in the Southern Ocean: vulnerability of benthic species to temperature change
Authors: PECK L.S.
Published: November 2005

Organisms have a limited number of responses that enhance survival in changing environments. They can: 1. Cope within existing physiological flexibility; 2. Adapt to changing conditions; or 3. Migrate to sites that allow survival. Species inhabiting coastal seabed sites around Antarctica have poorer physiological capacities to deal with change than species elsewhere. They die when temperatures are raised by only 5–10°C above the annual average, and many species lose the ability to perform essential functions, e.g. swimming in scallops or burying in infaunal bivalve molluscs when temperatures are raised only 2–3°C. The ability to adapt, or evolve new characters to changing conditions depends, at least in part, on generation time. Antarctic benthic species grow slowly and develop at rates often x5–x10 slower than similar temperate species. They also live to great age, and exhibit deferred maturity. Longer generation times reduce the opportunities to produce novel mutations, and result in poorer capacities to adapt to change. Intrinsic capacities to colonize new sites and migrate away from deteriorating conditions depend on adult abilities to locomote over large distances, or for reproductive stages to drift for extended periods. The slow development of Antarctic benthic species means their larvae do spend extended periods in the water column. However, whereas most continents have coastlines extending over a wide range of latitude, Antarctica is almost circular in outline, is isolated from other oceans by the circumpolar current, and its coastline covers few degrees of latitude. Thus in a warming environment there are fewer places to migrate to. On all three major criteria Antarctic benthic species appear less capable than species elsewhere of responding to change in ways that can enhance survival.
Biodiversity and ecosystem functioning in terrestrial habitats of Antarctica
Authors: WALL DIANA H.
Published: November 2005

Are we failing to acknowledge the impact of global changes (e.g. UVB, invasive species, climate, land use, atmosphere) on the terrestrial biodiversity and ecosystem processes of Antarctica? Antarctica is considered a pristine environment and has low terrestrial species diversity and trophic complexity, and yet while scientifically possible, we still do not know the number of species, where they are, or how their influence on ecosystem processes (e.g. nutrient cycling, carbon flux, decomposition, feedbacks to climate, hydrology) will be affected by multiple global changes. Increased recognition of human dependence on services provided by biodiversity and ecosystem functioning combined with documented impacts of global change already occurring on Antarctic soil ecosystems, increases the urgency to expand investigations regionally in Antarctica. We cannot measure the effects of global change or sustainably manage Antarctica's future if we underestimate the contribution of soil communities. Evidence indicates habitats of rocky moraines, soils and cyroconite holes of glaciers in the continental interior may host not only microbes, but also a complexity of algae and invertebrates. Scientists of many disciplines, together, need to assess the benefits humans derive from Antarctic terrestrial biodiversity and ecosystem processes, how these will be affected by global change, and link their findings to the rest of the world.
Risks posed to the Antarctic marine environment by acoustic instruments: a structured analysis
Authors:   SCAR ACTION GROUP ON THE IMPACTS OF ACOUSTIC TECHNOLOGY ON THE ANTARCTIC MARINE ENVIRONMENT, BOEBEL O. , CLARKSON P. , COATES R. , LARTER R. , O'BRIEN P.E. , PLOETZ J. , SUMMERHAYES C. , TYACK T. , WALTON D.W.H. , WARTZOK D.
Published: November 2005

The risks posed by a range of acoustic scientific instruments were assessed by the construction of matrices of scale and likelihood. We recognized six levels of impact ranging from none or short term, minimal behavioural response (Level 1) to multiple injuries and fatalities and/or compromised populations (Level 6) and six levels of likelihood ranging from “Expected in almost all instances” (Level 1) to “cannot see how it could happen” (Level 6). Typical scientific instruments ranging from acoustic releases to large air gun arrays were assessed. To provide a perspective for the risks of scientific operations, other activities were also ranked. These included large chemical explosions, submarine detection sonars implicated in some mass strandings of cetaceans and normal Antarctic shipping activities. The conclusion reached was that most scientific instruments pose a similar or lower risk than normal shipping operations. High source-level equipment poses some risk to individual animals' hearing and so should be mitigated. Likewise, survey planning should be designed to avoid trapping animals in narrow, constricted sea ways. Long term, cumulative impacts are still difficult to detect in areas with greater anthropogenic noise than the Antarctic but we concluded that any possible long term impacts should be mitigated by maintaining the low levels of activity using high source-level equipment through data sharing and survey planning.
Antarctic glacial isostatic adjustment: a new assessment
Authors: IVINS ERIK R. , JAMES THOMAS S.
Published: November 2005

The prediction of crustal motions and gravity change driven by glacial isostatic adjustment (GIA) in Antarctica is critically dependent on the reconstruction of the configuration and thickness of the ice sheet during the Late Pleistocene and Holocene. The collection and analysis of field data to improve the reconstruction has occurred at an accelerated pace during the past decade. At the same time, space-based imaging and altimetry, combined with on-ice velocity measurements using Global Positioning System (GPS) geodesy, has provided better assessments of the present-day mass balance of the Antarctic ice sheet. Present-day mass change appears to be dominated by deglaciation that is, in large part, a continuation of late-Holocene evolution. Here a new ice load model is constructed, based on a synthesis of the current constraints on past ice history and present-day mass balance. The load is used to predict GIA crustal motion and geoid change. Compared to existing glacioisostatic models, the new ice history model is significantly improved in four aspects: (i) the timing of volume losses in the region ranging from the Ross Sea sector to the Antarctic Peninsula, (ii) the maximum ice heights in parts of the Ellsworth and Transantarctic Mountains, (iii) maximum grounding line position in Pine Island Bay, the Antarctic Peninsula, and in the Ross Sea, (iv) incorporation of present-day net mass balance estimates. The predicted present-day GIA uplift rates peak at 14–18 mm yr−1 and geoid rates peak at 4–5 mm yr−1 for two contrasting viscosity models. If the asthenosphere underlying West Antarctica has a low viscosity then the predictions could change substantially due to the extreme sensitivity to recent (past two millennia) ice mass variability. Future observations of crustal motion and gravity change will substantially improve the understanding of sub-Antarctic lithospheric and mantle rheology.
Astronomy from Antarctica
Authors: STOREY J.W.V.
Published: November 2005

Astronomers have always sought the very best locations for their telescopes. From observatories in city centres, astronomers moved first to nearby mountain tops, then to remote sites in distant countries, to aircraft, and into space. In the past decade we have come to realize that the best astronomical observing conditions on the surface of the earth are to be found on the Antarctic plateau. The combination of high altitude, low temperature, low absolute humidity, low wind and extremely stable atmosphere offers astronomers gains in sensitivity and measurement precision that can exceed two orders of magnitude over even the best temperate sites. In addition, spectral windows are opened up – particularly in the far-infrared and terahertz regions – that are otherwise only accessible from high-flying aircraft or from space. Established and highly successful telescopes at the South Pole are soon to be joined by a new generation of facilities at Concordia Station, including large telescopes and interferometers. It has even been suggested that the largest optical telescopes currently proposed, with diameters of up to 100 m, might achieve their science goals at a lower overall cost if they are built on the Antarctic plateau rather than at a temperate site. Such telescopes offer the possibility of not only detecting earth-like planets in other star systems, but also of analysing their atmospheres spectroscopically.
Judging quality in science
Authors: WALTON DAVID
Published: November 2005

The joint inspection report by Australia, Peru and the United Kingdom, presented at the last ATCM in Stockholm, contained an unusual recommendation. On the basis of the science that they had seen at the research stations the inspection team had concluded that there was both very good science and very poor science being undertaken. They apparently believed that this pattern was probably true of the whole continent but needed a more expert examination. Their recommendation was that SCAR should undertake an in situ assessment of all scientific research in the Antarctic.
Northwest African upwelling and its effect on offshore organic carbon export to the deep sea
Authors: Helmke Peer , Romero Oscar , Fischer Gerhard
Published: November 2005

We combined the analysis of sediment trap data and satellite‐derived sea surface chlorophyll to quantify the amount of organic carbon export to the deep sea in the upwelling induced high production area off northwest Africa. In contrast to the generally global or basin‐wide adoption of export models, we used a regionally fitted empirical model. Furthermore, the application of our model was restricted to a dynamically defined region of high chlorophyll concentration in order to restrict the model application to an environment of more homogeneous export processes. We developed a correlation‐based approximation to estimate the surface source area for a sediment trap deployed from 11 June 1998 to 7 November 1999 at 21.25°N latitude and 20.64°W longitude off Cape Blanc. We also developed a regression model of chlorophyll and export of organic carbon to the 1000 m depth level. Carbon export was calculated for an area of high chlorophyll concentration (>1 mg m−3) adjacent to the coast on a daily basis. The resulting zone of high chlorophyll concentration was 20,000–800,000 km2 large and yielded a yearly export of 1.123 to 2.620 Tg organic carbon. The average organic carbon export within the area of high chlorophyll concentration was 20.6 mg m−2 d−1 comparable to 13.3 mg m−2 d−1 as found in the sediment trap results if normalized to the 1000 m level. We found strong interannual variability in export. The period autumn 1998 to summer 1999 was exceeding the mean of the other three comparable periods by a factor of 2.25. We believe that this approach of using more regionally fitted models can be successfully transferred even to different oceanographic regions by selecting appropriate definition criteria like chlorophyll concentration for the definition of an area to which it is applicable.
Oceanic forcing of the late 20th century Sahel drought
Authors: Lu Jian , Delworth Thomas L.
Published: November 2005

The Sahel region of Africa underwent a pronounced interdecadal drying trend in the latter half of the 20th century. In order to investigate this drying trend, several ensembles of numerical experiments are conducted using a recently developed atmospheric general circulation model (AM2, developed at NOAA's Geophysical Fluid Dynamics Laboratory). When the model is forced with the time series of observed SSTs and sea ice from 1950 to 2000, it successfully reproduces the observed interdecadal variability of Sahelian rainfall. Additional experiments are used to estimate the separate contributions to Sahel drought from SST anomalies in various ocean basins. In these, SST anomalies are applied only in the tropics, or only in the Atlantic, Indian and Pacific oceans separately. Forcing from the tropical oceans is dominant in driving the Sahelian rainfall trend. The response of Sahel rainfall to a general warming of the tropical oceans suggests a possible link to greenhouse gas‐induced climate change.
The impacts of the Luni‐Solar oscillation on the Arctic oscillation
Authors: Ramos da Silva Renato , Avissar Roni
Published: November 2005

The Arctic Oscillation (AO) has a major impact on climate variability in the extra tropical regions of the Northern Hemisphere. In this study, we show that specific alignments between the Sun, the Moon and the Earth known as the Luni‐Solar Oscillation (LSO) that occur at frequencies of nearly 9 and 18 years are unambiguously correlated with the AO since the mid‐1960's. The occurrence of the LSO peaks is predictable and, as a result, it improves climate predictability. Furthermore, we hypothesize that the recent observed increase in the AO amplitude maybe due to ice melting in the Arctic and SST increases at northern latitudes combined with the recent LSO peaks.
Seismic evidence for significant crustal thickening beneath Jabalpur earthquake, 21 May 1997, source region in Narmada–Son lineament, central India
Authors: Rai S. S. , Vijay Kumar T. , Jagadeesh S.
Published: November 2005

We investigate crustal properties beneath the deep crustal (∼35 km) Jabalpur earthquake of 21 May 1997, Narmada‐Son Lineament (NSL), central India, in search of a possible cause of stress accumulation in the region. Teleseismic receiver functions computed at nine digital seismographs along a 250 km long profile suggests Moho downwarp to ∼52 km across the width of the lineament, in contrast with an average 40 km depth elsewhere. In addition, the crust beneath the NSL has higher Vp/Vs of 1.84 compared to ∼1.73 in the surrounding, suggestive of a high‐density mafic mass at depth that compensates the crustal root, also supported by small topographic variation (200 m) across the lineament. Presence of such an anomalous mass in the deep crust may lead to gravitationally induced stresses in the lower crust that contribute to the failure of rock along the pre‐existing Narmada‐Son fault leading to the earthquake in deep crust.
A comparison between Monte Carlo simulations of runaway breakdown and terrestrial gamma‐ray flash observations
Authors: Dwyer J. R. , Smith D. M.
Published: November 2005

Monte Carlo simulations of the runaway breakdown of air are used to calculate the spectra of terrestrial gamma‐ray flashes (TGFs), which are then compared with RHESSI and CGRO/BATSE observations. It is found that the recent RHESSI spectrum is not consistent with a source altitude above 24 km but can be well fit by a source in the range of 15–21 km, depending upon the electric field geometry of the source. Because 15 km is not unusual for the tops of thunderstorms, especially at low latitudes, and is lower than typical minimum sprite altitudes, the RHESSI data imply that thunderstorms and not sprites may be the source of these TGFs. On the other hand, the soft energy spectrum seen in some BATSE TGFs is inconsistent with such large atmospheric depths, indicating that there may exist two distinct sources of TGFs, with altitudes below 21 km and above 30 km.
Clues of postseismic relaxation for the 1915 Fucino earthquake (central Italy) from modeling of leveling data
Authors: Amoruso A. , Crescentini L. , D'Anastasio E. , De Martini P. M.
Published: November 2005

We study five high precision leveling lines located around the epicentral area of 13 January 1915, Mw = 6.7 Fucino earthquake (Italy), that possibly recorded late stage postseismic relaxation movements. The geodetic signal is expected to comprise both large‐scale uplift of the Apennines and postseismic relaxation effects. In order to verify this hypothesis and to estimate the amount of each contribution, we compute gravitational visco‐elastic postseismic relaxation by inverting leveling data. Results indicate that the elastic upper crust is relatively thin (about 10 km) and post‐seismic contribution could be set at 30% of the geodetic signal. Model parameters are consistent with previous knowledge of the 1915 Fucino earthquake source, local seismic hypocentral determinations and crustal models derived from surface waves.
Late 20th century attribution of drying trends in the Sahel from the Regional Climate Model (RegCM3)
Authors: Jenkins Gregory S. , Gaye Amadou T. , Sylla Bamba
Published: November 2005

The RegCM3 has been integrated for the period of 1960–2002 using initial and lateral boundary conditions from the NCEP re‐analyses at 6‐hour intervals. Greenhouse gas concentrations remain fixed and the land‐use/soil properties are not altered. The RegCM3 accurately portrays a trend from wetter conditions in the 1960s to very dry conditions in the 1980s. The dry 1980s temperatures in the Sahel are approximately 3°K warmer than the wet 1960s, caused by a reduction in precipitation and clouds leading to an increase in the net absorbed solar radiation at the surface. This anomalous warming maintains the steepest meridional temperature gradient and therefore the African Easterly Jet in lower latitudes. The initiation of dry conditions starts in June and persists through July and August in the model simulations. The initiation of dry conditions appears to be related to a weaker Tropical Easterly Jet which may be linked to warmer Indian Ocean temperatures over the past several decades.
Discrete Langmuir waves in density structure
Authors: Yoon Peter H. , LaBelle James
Published: November 2005

Recent wideband observations of Langmuir waves in the auroral ionosphere show complex structure (McAdams and LaBelle, 1999) interpreted as resulting from discretization of the normal modes in the presence of a parabolic density cavity (McAdams et al., 2000). We formalize the theory of discrete Langmuir waves trapped within a one‐dimensional density cavity or enhancement in a magnetized plasma, assuming a Lorentzian density profile, and show that discrete spectrum of electric field is largely determined by the electrostatic wave equation although a very low level of electromagnetic waves is also present. In the overdense case (fpe > fce), the Langmuir waves are trapped in density depletions, and the predicted frequency spacings of the eigenmodes are comparable to those estimated by McAdams et al. (2000) using an approximate theory. We furthermore calculate the eigenfunctions associated with the first four eigenmodes in a Lorentzian density structure, showing that an Airy function approximation provides a close match to the exact solutions obtained numerically. Finally, we analyze synthesized time series simulating the signals which would be obtained by a rocket electric field receiver traversing the wave structures. This analysis reveals subtle predictions of the theory which can be measured with appropriate rocket or satellite observations. Specifically, the analysis predicts that there are nulls in the spectral lines of observed discrete emission which should be detectable in principle.
Refinements to flare energy estimates: A followup to “Energy partition in two solar flare/CME events” by A. G. Emslie et al.
Authors: Emslie A. G. , Dennis B. R. , Holman G. D. , Hudson H. S.
Published: November 2005

Emslie et al. (2004) reported estimates of the energy in the different flare and coronal mass ejection (CME) components of two major solar events with unprecedented observational coverage, one on 21 April 2002 and the other on 23 July 2002. On the basis of these estimates, it appeared that the summed energy content of the different flare components was significantly lower than the total energy of the CME, leading them to reach the “cautious” conclusion that “in both events the coronal mass ejection has the dominant component of the released energy,” amounting to approximately 30% of the available magnetic energy. In this note we present revised estimates of the flare thermal energies in the two events and also add a consideration of the total radiant energy of the events obtained by scaling the measured soft X‐ray luminosity based on Solar Radiation and Climate Experiment (SORCE) total solar irradiance measurements for the 28 October 2003 event. Recognizing that many of these energetic components are interrelated, we also take care to distinguish between “primary” components of energy (e.g., the magnetic field), “intermediate” components (e.g., accelerated particles and thermal plasma), and “final” components (e.g., kinetic energy of ejecta, radiant energy in various wave bands). We note that since the values of these components are not all independent, careful tallying is necessary to arrive at an overall energy budget for the event. The best estimates for the energies of the various components still show that the CME contains the greatest fraction of the released energy in both events. However, given the large uncertainties in the energies of the different flare components and the higher estimates of radiant energy obtained by scaling from the SORCE measurements, the results are also consistent with the flare and CME energies in both events being comparable, with a common value of ∼1032 ergs.
Low‐frequency electrical response to microbial induced sulfide precipitation
Authors: Ntarlagiannis Dimitrios , Williams Kenneth Hurst , Slater Lee , Hubbard Susan
Published: November 2005

We investigated the sensitivity of low‐frequency electrical measurements to microbe‐induced metal sulfide precipitation. Three identical sand‐packed monitoring columns were used; a geochemical column, an electrical column and a control column. In the first experiment, continuous upward flow of nutrients and metals in solution was established in each column. Cells of Desulfovibrio vulgaris (D. vulgaris) were injected into the center of the geochemical and electrical columns. Geochemical sampling and post‐experiment destructive analysis showed that microbial induced sulfate reduction led to metal precipitation on bacteria cells, forming motile biominerals. Precipitation initially occurred in the injection zone, followed by chemotactic migration of D. vulgaris and ultimate accumulation around the nutrient source at the column base. Results from this experiment conducted with metals show (1) polarization anomalies, up to 14 mrad, develop at the bacteria injection and final accumulation areas, (2) the onset of polarization increase occurs concurrently with the onset of lactate consumption, (3) polarization profiles are similar to calculated profiles of the rate of lactate consumption, and (4) temporal changes in polarization and conduction correlate with a geometrical rearrangement of metal‐coated bacterial cells. In a second experiment, the same biogeochemical conditions were established except that no metals were added to the flow solution. Polarization anomalies were absent when the experiment was replicated without metals in solution. We therefore attribute the polarization increase observed in the first experiment to a metal‐fluid interfacial mechanism that develops as metal sulfides precipitate onto microbial cells and form biominerals. Temporal changes in polarization and conductivity reflect changes in (1) the amount of metal‐fluid interfacial area, and (2) the amount of electronic conduction resulting from microbial growth, chemotactic movement and final coagulation. This polarization is correlated with the rate of microbial activity inferred from the lactate concentration gradient, probably via a common total metal surface area effect.
Measurement of wet deposition of inorganic and organic nitrogen in a forest environment
Authors: Hill Kimberly A. , Shepson Paul B. , Galbavy Edward S. , Anastasio Cort
Published: November 2005

Dissolved inorganic (NO3− and NH4+) and organic nitrogen (DON) were measured in precipitation at the University of Michigan Biological Station (UMBS) near Pellston, Michigan, in an open field and under the forest canopy from June to August 2004. Experiments to test the stability of the rain samples were conducted to evaluate different collection methods. Comparison of the two data sets allows the interactions between precipitation and the forest canopy to be examined. In addition, the measurements of wet‐deposited total nitrogen were compared to calculated estimates of total dry‐deposited nitrogen. Stability tests of the samples indicated that the samples must be frozen during collection. The average distribution of wet‐deposited nitrogen for the summer was 32.9 (±0.5)% nitrate, 52.5 (±0.3)% ammonium, and 14.6 (±0.9)% DON in an open field and 42.5 (±0.9)% nitrate, 38.9 (±1.0)% ammonium, and 18.8 (±1.4)% DON under the forest canopy. Canopy‐precipitation interactions were observed to cause a 68 (±4)% increase in nitrate, a 4 (±2)% decrease in ammonium, and an 81 (±16)% increase in DON in the collectors under the forest canopy. A comparison of wet and dry nitrogen deposition indicated that dry deposition may contribute more nitrogen than wet deposition to this site. However, our measurements indicate that much of the dry‐deposited nitrogen is lost, some of which is likely revolatilized.
Flood pulse influences on terrestrial organic matter export from an agricultural watershed
Authors: Dalzell Brent J. , Filley Timothy R. , Harbor Jon M.
Published: November 2005

Riverine export of terrestrial organic carbon (TOC) plays an important role in the global C cycle through influences on coastal productivity, sedimentary preservation, and CO2 efflux. In order to examine the influence of hydrologic variability and upland processes on TOC export from a midwestern agricultural watershed, we applied lignin phenol and stable carbon isotope analyses to assess quantity, source, and relative degradation state of TOC in soils, sediments, and size‐fractioned aquatic OC from stream water. Flood conditions exported 90 times more dissolved organic carbon (DOC) than baseflow owing to increases in both discharge and concentration, indicating mobilization of additional DOC pools. These observations are supported by increased TOC contributions to aquatic OC during flooding. Furthermore, stable carbon isotope values show that OC exported during flooding is enriched in C4‐derived C by up to 38% (for high molecular weight DOC) with respect to baseflow, indicating different TOC sources are mobilized dependant on hydrologic conditions. Lignin phenols isolated from the colloid size fraction show progressive increases in the ratio of carboxylic acid to aldehyde functional groups (a measure of relative degradation state) with distance downstream suggesting selective partitioning to mineral surfaces and/or degradation to this size fraction. This study shows that TOC quantity, source, and relative degradation state can change dependant on hydrologic conditions and in‐stream transport in a small agricultural watershed. Moreover, these results are important in showing variability in TOC source and chemistry exported from headwater systems that might otherwise not be detected in studies of larger rivers.
Wavelet coherency analysis to relate saturated hydraulic properties to soil physical properties
Authors: Si Bing Cheng , Zeleke Takele B.
Published: November 2005

A soil property may be related to another and the relationships may change depending on the scale and location. Understanding these scale‐ and location‐dependent relationships is important for prediction of one soil property based on another. The objective of this study is to use wavelet coherency analysis to examine whether the relationship between hydraulic properties and soil physical properties are scale‐ and location‐dependent. Undisturbed cores were collected along a transect from the sandy loam soil of a farm field in northern Saskatchewan, Canada. Saturated hydraulic conductivity (Ks), sand content, and organic carbon content (OC) were measured on these cores, and their relationships as a function of scale and location were analyzed using wavelets. Results indicated that the wavelet coherency between Ks and sand content is only significantly different from that of red noises at the scales around 48 m. The cross‐wavelet spectrum and wavelet coherency are predominantly in phase, suggesting a positive correlation between Ks and sand. For Ks and OC, significant coherency exists at scales from 30 to 48 and around 80 m. At the scales of 30–48 and around 80 m the relationships are predominantly out of phase, suggesting negative correlation. Therefore relationships between Ks and sand or Ks and OC are not only scale‐dependent but also location‐dependent. Scale and location dependence have an important implication for understanding the scaling relationships between Ks and sand and OC and for the prediction of Ks from sand and OC.
The wild‐type Schizosaccharomyces pombe mat1 imprint consists of two ribonucleotides
Authors: Vengrova Sonya , Dalgaard Jacob Z
Published: November 2005

The imprint at the mat1 locus of Schizosaccharomyces pombe acts to initiate the replication‐coupled recombination event that underlies mating‐type switching. However, the nature of the imprint has been an area of dispute. Two alternative models have been proposed: one stated that the imprint is a nick in the DNA, whereas our data suggested that it consists of one or two ribonucleotides incorporated into the otherwise intact DNA duplex. Here, we verify key predictions of the RNA model by characterization of wild‐type genomic DNA purified under conditions known to hydrolyse DNA–RNA–DNA hybrid strands. First, we observe one‐nucleotide gap at the hydrolysed DNA, as expected from the presence of two ribonucleotides. Second, using a novel assay based on ligation‐mediated PCR, a 3′‐terminal ribonucleotide is detected at the hydrolysed imprint. Our observations allow the unification of available data sets characterizing the wild‐type imprint.
High-pressure and -temperature viscosity measurements of methanol and 4:1 methanol:ethanol solution
Authors: Grocholski Brent , Jeanloz Raymond
Published: November 2005

Viscosity (η) measurements using rolling sphere viscometry in a resistance-heated diamond-anvil pressure cell yield activation energies of 18–98kJ∕mol over a pressure range of 1.1–6.1GPa for methanol and 26–78kJ∕mol over a pressure range of 2.9–5.4GPa for a 4:1 methanol:ethanol solution. Nonlinear models of logη (free-volume and power-law models) yield statistically better fits than the Arrhenius model at room temperature and extrapolate to lower glass-transition (1012Pas) pressures. Glass-transition pressures for the free-volume model change little over the temperature range studied (298–338K), whereas the power-law values converge to those of the Arrhenius model at temperatures above 320K.
A combinatorial approach to the electron correlation problem
Authors: Thom Alex J. W. , Alavi Ali
Published: November 2005

Starting from a path-integral formulation of quantum statistical mechanics expressed in a space of Slater determinants, we develop a method for the Monte Carlo evaluation of the energy of a correlated electronic system. The path-integral expression for the partition function is written as a contracted sum over graphs. A graph is a set of distinct connected determinants on which paths can be represented. The weight of a graph is given by the sum over exponentially large numbers of paths which visit the vertices of the graph. We show that these weights are analytically computable using combinatorial techniques, and they turn out to be sufficiently well behaved to allow stable Monte Carlo simulations in which graphs are stochastically sampled according to a Metropolis algorithm. In the present formulation, graphs of up to four vertices have been included. In a Hartree-Fock basis, this allows for paths which include up to sixfold excitations relative to the Hartree-Fock determinant. As an illustration, we have studied the dissociation curve of the N2 molecule in a VDZ basis, which allows comparison with full configuration-interaction calculations.
Gauge-origin-independent magnetizabilities of solvated molecules using the polarizable continuum model
Authors: Ferrighi Lara , Marchesan Domenico , Ruud Kenneth , Frediani Luca , Coriani Sonia
Published: November 2005

We present an implementation of the polarizable continuum model in its integral equation formulation for the calculation of the magnetizabilities of solvated molecules. The gauge-origin independence of the calculated magnetizabilities and the fast basis set convergence are ensured through the use of London atomic orbitals. Our implementation can use Hartree-Fock and multiconfigurational self-consistent-field (MCSCF) wave functions as well as density-functional theory including hybrid functionals such as B3LYP. We present the results of dielectric continuum effects on water and pyridine using MCSCF wave functions, as well as dielectric medium effects on the magnetizability of the aromatic amino acids as a model for how a surrounding protein environment affects the magnetizability of these molecules. It is demonstrated that the dielectric medium effects on the magnetizability anisotropies of the aromatic amino acids may be substantial, being as large as 25% in the case of tyrosine.
Efficient linear-response method circumventing the exchange-correlation kernel: Theory for molecular conductance under finite bias
Authors: Neuhauser Daniel , Baer Roi
Published: November 2005

An iterative approach for calculating the frequency domain linear response of molecular systems within time-dependent density-functional theory is presented. The method completely avoids computing the exchange-correlation kernel which is typically the most expensive step for large systems. In particular, virtual orbitals are not needed. This approach may be useful for treating the response of large systems. We give an outline of the theory and a demonstration on a jellium model of an elliptic gold cluster. A detailed theory is appended discussing the computation of conductance and ac impedance of molecular junctions under bias.
Electronic structure and spectrum of UO22+ and UO2Cl42−
Authors: Pierloot Kristine , van Besien Els
Published: November 2005

A theoretical study is presented of the electronic spectra of the UO22+ and UO2Cl42− ions, based on multiconfigurational perturbation theory (CASSCF/CASPT2), combined with a recently developed method to treat spin-orbit coupling [P.-Å. Malmqvist et al., Chem. Phys. Lett. 357, 230 (2002); B. O. Roos and P.-Å. Malmqvist, Phys. Chem. Chem. Phys. 6, 2919 (2004)]. The results are compared to the experimental spectroscopic data obtained for uranyl ions in Cs2UO2Cl4 crystals from Denning [Struct. Bonding (Berlin) 79, 215 (1992)] and to previous theoretical calculations performed using a combined configuration-interaction spin-orbit treatment [Z. Zhang and R. M. Pitzer, J. Phys. Chem. A 103, 6880 (1999); S. Matsika and R. M. Pitzer, J. Phys. Chem. A. 105, 637 (2001)]. As opposed to the latter results, the calculations performed in this work point to a significant effect of the weakly bound equatorial chlorine ligands on the excitation energies.