bluuebunny/crossref_metadata_2025 huggingface dataset:
Uterine artery Doppler at 11 + 0 to 13 + 6 weeks and 21 + 0 to 24 + 6 weeks in the prediction of pre‐eclampsia
Authors: Plasencia W. , Maiz N. , Poon L. , Yu C. , Nicolaides K. H.
Published: July 2008

Objective

To evaluate the performance of screening for pre‐eclampsia by uterine artery pulsatility index (PI) at 11 + 0 to 13 + 6 weeks' gestation and the change in uterine artery PI between 11 + 0 to 13 + 6 and 21 + 0 to 24 + 6 weeks.

Methods

In 3107 singleton pregnancies attending for routine care at 11 + 0 to 13 + 6 and 21 + 0 to 24 + 6 weeks' gestation we recorded maternal characteristics and medical and obstetric history, and measured uterine artery PI. The distributions of uterine artery PI were made Gaussian after logarithmic transformation and the log of the ratio of uterine artery PI at 21 + 0 to 24 + 6 weeks to that at 11 + 0 to 13 + 6 weeks was calculated. Multiple regression analysis was used to determine which of the maternal variables and Doppler findings were significant predictors of early and late pre‐eclampsia. The performance of screening was described by receiver–operating characteristics curves.

Results

Pre‐eclampsia developed in 93 (3.0%) pregnancies, including 22 (0.7%) in which delivery was before 34 weeks (early pre‐eclampsia) and 71 (2.3%) with delivery at 34 weeks or more (late pre‐eclampsia). Seventy‐three (2.3%) women developed gestational hypertension, 346 (11.1%) delivered small‐for‐gestational‐age (SGA) babies with no hypertensive disorders and 2595 (83.5%) were unaffected by pre‐eclampsia, gestational hypertension or SGA. Multiple regression analysis demonstrated that maternal variables, uterine artery PI at 11 + 0 to 13 + 6 weeks and the change in uterine artery PI between 11 + 0 to 13 + 6 and 21 + 0 to 24 + 6 weeks' gestation provided significant independent contributions to the prediction of pre‐eclampsia. For a false positive rate of 5% the predicted detection rates of early and late pre‐eclampsia were 90.9 and 31.0%, respectively. The same performance of screening was achieved by reserving second‐trimester testing for only the 20% of women at the highest risk after first‐trimester screening.

Conclusion

The decrease in uterine artery PI between 11 + 0 to 13 + 6 and 21 + 0 to 24 + 6 weeks is steeper in pregnancies with a normal outcome than in those developing pre‐eclampsia. Effective screening for pre‐eclampsia can be achieved by the Doppler measurement of uterine artery PI at 11 + 0 to 13 + 6 weeks and the change in PI between 11 + 0 to 13 + 6 and 21 + 0 to 24 + 6 weeks. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Internal fixation of proximal humeral fractures with a Polarus humeral nail
Authors: Koike Yoichi , Komatsuda Tatsuro , Sato Katsumi
Published: July 2008

Background

Proximal humeral fractures occur frequently. Displaced or unstable fractures require open reduction and internal fixation. Our objective was to investigate the clinical and radiographic results of the internal fixation using Polarus humeral nails for fractures of the proximal humerus.

Materials and methods

From January 2001 to April 2006, 54 shoulders of 54 patients (44 females, 10 males) underwent the intramedullary fixation using Polarus humeral nail. Mean age of the patients was 66-year-old (39–89) at the time of the surgery. Fracture-type by Neer classification was 2-part (29 shoulders), 3-part (22 shoulders) and 4-part (3 shoulders). The clinical and radiological outcomes were evaluated.

Results

All the shoulders after osteosynthesis obtained bone-union. There was no osteonecrosis of the humeral head. Functional outcome measured by JOA score averaged 81 points. Totally 43 patients (79%) had satisfactory to excellent results. Varus deformity was seen in 4 shoulders (8%) and the deformity of the greater tuberosity in 4 (8%).

Conclusion

The Polarus intramedullary humeral nail is effective for the treatment of proximal humeral fractures.
Within-brood social status and consequences for winter hierarchies amongst Mallard Anas platyrhynchos ducklings
Authors: Poisbleau Maud , Guillemain Matthieu , Demongin Laurent , Carslake David , David Joan
Published: July 2008

Juveniles of many birds establish dominance hierarchies within family social units, only to leave and compete to acquire dominance status in new social groups. Little is known about the role of sex, body mass, size or experience during the duckling period on subsequent dominance rank and adult social relationships. We used captive MallardAnas platyrhynchosducklings to test for the role of individual characteristics and growth parameters in establishing within-brood hierarchies, the maintenance of within-brood hierarchies in the subsequent wintering group and differences in social ranks between broods. Strong stable linear hierarchies were present within each brood and, later, within each phase of the winter. There was a reorganisation of the hierarchical order between the duckling period and early winter, but only few modifications afterwards during the winter. None of the tested “hatching”, “duckling” and “adult” traits explained either the within-brood or the winter hierarchies, but winter rank was related to brood of origin with ducklings from the same brood having similar social ranks. These differences between broods were maintained through the whole winter in most cases, though one brood drastically progressed in the hierarchy during late-winter. These results suggest that the factors affecting the establishment of social relationships within broods differ from those in winter groups, and that brood-related mechanisms influence social relationships during winter. We discuss our results in the light of direct and indirect maternal influence.
Interspecific dominance and asymmetric competition with respect to nesting habitats between two snowfinch species in a high‐altitude extreme environment
Authors: Zeng Xianhai , Lu Xin
Published: July 2008

Interference competition over shared resources is expected to be intensive in harsh environments between phylogenetically and morphologically similar species. We document interspecific dominance and nest habitat selection by two pika‐burrow nesting Montifringilla species, white‐rumped snowfinches M. taczanowskii (WRS), and rufous‐necked snowfinches M. ruficollis (RNS), which commonly inhabit alpine meadows in the northeastern Tibetan plateau. Relative to the critical point (<0.60) for coexistence, high overlaps (0.68–0.86) between the two species in egg‐laying date, nest site distribution and nesting burrow attributes suggested strong interspecific competition over these niches. This is also predicted by the ratios of inter‐species body mass (1.4) and linear dimensions (1.1–1.2) below the minimum value (2.0 and 1.3) for stable coexistence of closely related species. Larger‐sized WRS was behaviorally dominant over pikas and over small‐sized RNS. Being dominant, WRS established nesting territories in areas with moderately steep slopes from which they required most of the food resources during the breeding season; in contrast, RNS exhibited no territoriality and had to nest at margins between WRS's territories and fed at dispersed sites. For the same reason, WRS mainly used active, and RNS used inactive, pika burrows. The asymmetric competition over nesting habitats could contribute to the relatively high nesting success and breeding density of the superior species. We argue that there is a spectrum in interspecific competition strength, from stable coexistence to complete exclusion along a gradient of increased environmental harshness, and the guild of the two snowfinch species is at a mediate position of the spectrum.
Case Report of Spontaneous, Nonspinal Fractures in a Multiple Myeloma Patient on Long-term Pamidronate and Zoledronic Acid
Authors: Wernecke Greg , Namduri Surena , DiCarlo Edward F. , Schneider Robert , Lane Joseph
Published: July 2008

Pamidronate and zoledronic acid are two potent intravenous bisphosphonates used in the treatment of multiple myeloma as well as osteoporosis. While the concern for heightened fracture risk in a patient on long-term bisphosphonate treatment for malignancy has been previously noted, we present the first case of spontaneous, nonspinal fractures in a patient undergoing treatment for multiple myeloma. The patient had a positive 9-year history of bisphosphonate treatment and presented with sequential subtrochanteric stress fractures of the left and right femurs. Pathological reports of fracture site biopsies demonstrate signs consistent with ametabolic bone and no malignancy. These findings point to extreme inhibition of bone turnover by bisphosphonates as the cause of this patient's morbidity. This is a single retrospective case study (level IV evidence).
The development of Chinese ethnic minority historiography and the formation of the concept of a united multiethnic nation
Authors: Lindong QU
Published: July 2008

Chinese culture is established by bringing together many nationalities. Chinese historiography has recorded the development of this great culture. Among these records, ethnic minority historiography reflects one important aspect for identifying the historic trend of the formation of a united multiethnic nation. A comprehensive study on the development of Chinese ethnic minority historiography shows that it can be divided into six phases: the Pre-Qin period to the Qin and Han dynasties; the Wei, Jin, Southern-Northern and Sui-Tang dynasties; the Liao, Song, Xia, Jin and Yuan dynasties; the Ming and Qing dynasties (before 1840); the modern times (1840–1949); and the contemporary times. Deep analysis of these phases would inevitably improve the study of the history of Chinese historiography.
Textual discourses and behavior criterion: The historiographic significance of Tibetan biographies of the religious figures
Authors: Lin SUN
Published: July 2008

From the perspective of historical anthropology, this article examines a great deal of the biographies of religious figures in Tibetan history, reveals their special way of writing, classification, and circulation. In Tibetan Buddhism, biographies of religious figures are considered as a subject’s demise (lung-rgyun) and have their special meanings. They are the text of the largest quantity in the historical works of Tibet and had great influence on Tibetan historiography. A comprehensive research on their cultural characteristic, historical evolvement and historical influence will help us understand the Tibetan culture in depth.
Taoist tradition, gentry culture, and local societies: The cult of Zougong at Sibao in western Fujian Province since the Song and Ming dynasties
Authors: Yonghua LIU
Published: July 2008

Zougong, the most important local deity at Sibao, Tingzhou Prefecture, was worshipped by local villagers at least from the Yuan and the Ming dynasties on. The Zou lineages in the area regarded Zougong as their common ancestor. Existing literature usually identifies Zougong as Zou Yinglong, a zhuangyuan in the Southern Song Dynasty. However, such identification appeared only in the late Ming period when local elites of several Zou lineages consciously tried to unite and consolidate their lineages. Before that, Zougong was a mighty ritual master in a series of magic contest stories popular at Tingzhou, rather than a zhuangyuan. The change of his identity from ritual master to zhuangyuan was a result of convergence of Taoist tradition, gentry culture and local culture, which may be called “cultural hybridization,” rather than a simple process by which local culture gave way to gentry culture.
The temporal characteristics of border trading along the Great Wall during the Qing Dynasty
Authors: Meiqin QI
Published: July 2008

Comparison study on the border trading between the Ming and the Qing dynasties shows that during the Qing Dynasty, the Great Wall become an important means for the government to rule other nations like Mongolian; the border trading markets in the Qing were more than that in the Ming, and the folk trading along the Great Wall played an important role; the management about the border trading by the Qing government was embodied in the control of the structure and scale of border trading market and the mutual trading; the trading premise, the market nature, the market value for existence, and the market function of the border trading in the Qing were different from that of the Ming Dynasty.
The decline of traditional industrial and commercial cities in modern China: Exemplified with Suzhou, Hangzhou and Yangzhou
Authors: Yimin HE
Published: July 2008

Resulted from different causes, the majority of traditional cities in modern China underwent a decline in various degrees. The causes of the decline of Suzhou, Hangzhou, and Yangzhou which have started to develop their new industry and commerce since mid-Qing Dynasty lies in such aspects as: the lose of transportation superiority in modern China; the fatal destruction caused by Taiping Revolution; the affects of the rising of Shanghai; the recession of traditional economy and slowed development of new economy; and the conservatism in thinking and ideas etc.
Pediatric Ganglion Cysts of the Hand and Wrist: An Epidemiologic Analysis
Authors: Coffey Michael J. , Rahman M. Fazlur , Thirkannad Sunil M.
Published: July 2008

We analyzed all hand and wrist ganglions in patients aged 12 years and younger that were treated at our institution during a 3-year period. Our patients were predominately female (1.8:1). Volar ganglions were more common (1.2:1), whereas dorsal ganglions have been reported to be more common in adults. Ganglions had a higher incidence of arising from tendon sheaths in our patients (33%) compared to what has been previously reported for ganglions in studies of all age groups (5% to 16%). While observation and/or splinting alone will likely be helpful in resolution of a majority of pediatric hand and wrist ganglions, surgical excision should be employed in those that are symptomatic and/or do not resolve with observation.
Dietary Conjugated Linoleic Acid Renal Benefits and Possible Toxicity vary with Isomer, Dose and Gender in Rat Polycystic Kidney Disease
Authors: Ogborn Malcolm R. , Nitschmann Evan , Goldberg Aviva , Bankovic‐Calic Neda , Weiler Hope A. , Aukema Harold M.
Published: July 2008

Conjugated linoleic acid (CLA) is anti‐proliferative and anti‐inflammatory in the Han:SPRD‐cy rat model of kidney disease. We used different doses of CLA and examined effects on renal histological benefit, the renal PPARγ system and hepatic and renal levels of CLA isomers. Male and female offspring of Han:SPRD‐cy heterozygotes were fed diets with 0, 1 or 2% CLA isomer mixture for 12 weeks before dual‐energy X‐ray absorptiometry, harvest of renal and hepatic tissue for histologic and lipid analysis. Both CLA diets reduced body fat content in both genders but did not change lean body mass. CLA produced a dose dependent reduction in female renal cystic change. CLA reduced fibrosis, but this reduction was significantly less with higher dose in males. CLA reduced macrophage infiltration, tissue oxidized LDL content and proliferation of epithelial cells. Serum creatinine rose significantly in female animals fed CLA diets. CLA treatment did not change PPARγ activation. A significant negative correlation with renal content of the 18:2 c9,t11 isomer and the sum of histologic effects was identified. CLA reduces histologic renal injury in the Han:SPRD‐cy rat model probably inversely proportionate to c9,t11 renal content. Possible functional CLA toxicity at high dose in female animals warrants further exploration.
Pharmakogenetik der oralen Antikoagulation mit Cumarinen
Authors: Oldenburg J. , Rost S. , Seidel H. , Watzka M. , Müller-Reible C.R.
Published: July 2008

Die Klonierung desVKORC1-Gens hat maßgeblich zu einem besseren Verständnis des Vitamin-K-Zyklus beigetragen. Das VKORC1-Protein konnte als der molekulare Zielort (Target) der Cumarine identifiziert werden. Mutationen und SNP innerhalb der translatierten und nichttranslatierten Regionen desVKORC1-Gens verursachen eine partielle bis totale Cumarinresistenz oder -sensitivität. Die Verfügbarkeit einer molekulargenetischen Diagnostik (VKORC1,CYP2C9) und einer Laboranalytik mittels HPLC (zur Bestimmung des Cumarin-, Vitamin-K- und Vitamin-K-Epoxid-Spiegels) ist hilfreich in der Detektion hereditärer und erworbener Einflussgrößen der Cumarintherapie und könnte zukünftig für eine individualisierte, risikoärmere orale Antikoagulationstherapie zum Einsatz kommen.
Ehhmbp45 is a novel hemoglobin‐binding protein identified in Entamoeba histolytica
Authors: Cruz-Castañeda Areli , Olivares-Trejo José J.
Published: July 2008

Hemoglobin‐binding proteins are necessary for pathogens to obtain iron from Hb. Entamoeba histolytica can grow using Hb as source of iron, but the underlying mechanism has not previously been established. In this work, we identified a 45 kDa Hb‐binding protein of E. histolytica, which we named Ehhmbp45. In silico analysis showed that Ehhmbp45 contains the conserved domains needed for Hb‐binding, while overlay assays demonstrated that Ehhmbp45 is able to bind Hb. In addition, we found that Ehhmbp45 mRNA levels were up‐regulated under iron starvation conditions and were subsequently restored to basal levels when Hb was added to the cell cultures. These findings provide the first insights on the role of Ehhmbp45 in iron acquisition from Hb.
The roles of plant dsRNA‐binding proteins in RNAi‐like pathways
Authors: Curtin Shaun J. , Watson John M. , Smith Neil A. , Eamens Andrew L. , Blanchard Chris L. , Waterhouse Peter M.
Published: July 2008

Dicers are associated with double‐stranded RNA‐binding proteins (dsRBPs) in animals. In the plant, Arabidopsis, there are four dicer‐like (DCL) proteins and five potential dsRBPs. These DCLs act redundantly and hierarchically. However, we show there is little or no redundancy or hierarchy amongst the DRBs in their DCL interactions. DCL1 operates exclusively with DRB1 to produce micro (mi)RNAs, DCL4 operates exclusively with DRB4 to produce trans‐acting (ta) siRNAs and 21nt siRNAs from viral RNA. DCL2 and DCL3 produce viral siRNAs without requiring assistance from any dsRBP. DRB2, DRB3 and DRB5 appear unnecessary for mi‐, tasi‐, viral si‐, or heterochromatinising siRNA production but act redundantly in a developmental pathway.
NADPH‐dependent thioredoxin reductase and 2‐Cys peroxiredoxins are needed for the protection of Mg–protoporphyrin monomethyl ester cyclase
Authors: Stenbaek Anne , Hansson Andreas , Wulff Ragna Peterson , Hansson Mats , Dietz Karl-Josef , Jensen Poul Erik
Published: July 2008

The chloroplast‐localized NADPH‐dependent thioredoxin reductase (NTRC) has been found to be able to reduce hydrogen peroxide scavenging 2‐Cys peroxiredoxins. We show that the Arabidopsis ntrc mutant is perturbed in chlorophyll biosynthesis and accumulate intermediates preceding protochlorophyllide formation. A specific involvement of NTRC during biosynthesis of protochlorophyllide is indicated from in vitro aerobic cyclase assays in which the conversion of Mg–protoporhyrin monomethyl ester into protochlorophyllide is stimulated by addition of the NTRC/2‐Cys peroxiredoxin system. These findings support the hypothesis that this NADPH‐dependent hydrogen peroxide scavenging system is particularly important during periods with limited reducing power from photosynthesis, e.g. under chloroplast biogenesis.
Helix swapping leads to dimerization of the N‐terminal domain of the c‐type cytochrome maturation protein CcmH from Escherichia coli
Authors: Ahuja Umesh , Rozhkova Anna , Glockshuber Rudolf , Thöny-Meyer Linda , Einsle Oliver
Published: July 2008

In the process of cytochrome c maturation, heme groups are covalently attached to reduced cysteines of specific heme‐binding motifs (CXXCH) in an apocytochrome c sequence. In Escherichia coli, the CcmH protein maintains apo‐protein cysteines in a reduced state prior to heme attachment. We have purified and biophysically, as well as structurally characterized the soluble, N‐terminal domain of E. coli CcmH that carries the functionally relevant LRCXXC‐motif. In contrast to a recently presented structure of the homologous domain from Pseudomonas aeruginosa, the E. coli protein forms a tightly interlinked dimer by swapping its N‐terminal helix between two monomers. We propose that an altered environment of the functional motif may help to discern between the two redox partners CcmG and apocytochrome c.
PEG10 directly regulated by E2Fs might have a role in the development of hepatocellular carcinoma
Authors: Wang Chaochen , Xiao Ying , Hu Zhonghua , Chen Yibin , Liu Na , Hu Gengxi
Published: July 2008

PEG10 is an imprinted gene which is up‐regulated in hepatocelluar carcinoma (HCC). However, the mechanism of PEG10 regulation remains to be elucidated. In this work the transcription factors E2F‐1 and ‐4 were demonstrated to bind directly to the promoter of PEG10 and thereby regulate its expression. The expression profile of HCC tissues also suggested E2Fs were involved in PEG10 regulation. Further functional analysis showed that PEG10 was involved in the repression of apoptosis induced by serum deprivation and chemotherapeutic drugs. These findings link cancer genetics and epigenetics by showing that E2F acts directly upstream of an anti‐apoptosis imprinted gene, PEG10.
A unique residue in rab3c determines the interaction with novel binding protein Zwint‐1
Authors: van Vlijmen Thijs , Vleugel Mathijs , Evers Melvin , Mohammed Shabaz , Wulf Phebe S. , Heck Albert J.R. , Hoogenraad Casper C. , van der Sluijs Peter
Published: July 2008

Exocytic events are tightly regulated cellular processes in which rab GTPases and their interacting proteins perform an important function. We set out to identify new binding partners of rab3, which mediates regulated secretion events in specialized cells. We discovered Zwint‐1 as a rab3 specific binding protein that bound preferentially to rab3c. The interaction depends on a critical residue in rab3c that determines the binding efficiency of Zwint‐1, which is immaterial for interaction with rabphilin3a. Rab3c and Zwint‐1 are expressed highly in brain and colocalized extensively in primary hippocampal neurons. We also found that SNAP25 bound to the same region in Zwint‐1 as rab3c, suggesting a new role for the kinetochore protein Zwint‐1 in presynaptic events that are regulated by rab3 and SNAP25.
Amplification of an RNA ligase ribozyme under alternating temperature conditions
Authors: Kim Ki-Sun , Oh Sangtaek , Yea Sung Su , Yoon Moon-Young , Kim Dong-Eun
Published: July 2008

Amplification of an RNA template molecule was examined using the ligase ribozyme and its corresponding RNA substrates under alternating temperature conditions. Alternating temperatures enhanced the rate of the thermodynamically unfavorable dissociation of the annealed products into the two separate RNA templates, reminiscent of the polymerase chain reaction. Under these conditions, the RNA ligase ribozyme system was observed to amplify through a mainly cross‐catalytic process, generating additional copies of the starting RNA template molecules. Thus, template‐directed RNA ligation using the ribozyme under thermally fluctuating conditions will be an intriguing point to consider when explaining the primordial event of chemical evolution.
What happened in the sixties?
Authors: AGAR JON
Published: July 2008

In general history and popular culture, the long 1960s, a period roughly beginning in the mid-1950s and ending in the mid-1970s, has been held to be a period of change. This paper offers a model which captures something of the long 1960s as a period of ‘sea change’ resulting from the interference of three waves. Wave One was an institutional dynamic that drew out experts from closed and hidden disagreement into situations where expert disagreement was open to public scrutiny. Wave One also accounts for the multiplication of experts. Wave Two consisted of social movements, institutions and audiences that could carry public scrutiny and provide a home for sea-change cultures. In particular, Wave Two provided the stage, audience and agents to orchestrate a play of disagreeing experts. Wave Three was marked by an orientation towards the self, in diverse ways. Modern science studies is a phenomenon of Wave Three. All three waves must be understood in the context of the unfolding Cold War.
‘Greenwich Observatory Time for the public benefit’: standard time and Victorian networks of regulation
Authors: ROONEY DAVID , NYE JAMES
Published: July 2008

The widespread adoption of standard time in Britain took more than fifty years and simple public access to a representation of it took longer still. Whilst the railways and telegraph networks were crucial in the development of standardized time and time-distribution networks, very different contexts existed, from the Victorian period onwards, where time was significant in both its definition and its distribution. The moral drive to regulate and standardize aspects of daily life, from factory work to the sale of liquor, led to time being used as a tool for control. Yet, as a tool, it was problematic, both in its own regulation and in the regulation of its distribution. Companies such as the Standard Time Company, in creating businesses out of time distribution, found themselves at the heart of discussions of time and standards, acting, as they did, as a nexus between the nation's master timekeeper, the Royal Observatory, and London public houses, Lancashire cotton mills and myriad small businesses. We can see this network both literally, in electric wires, clocks, batteries and relays, and metaphorically, transmitting Victorian moral concerns of ‘power’ and ‘intelligence’ between imperial state and individual. Naturally enough, the network itself was as contested as the message it transmitted.
Coupled Langmuir and nonlinear ion acoustic waves in the presence of non-thermal electrons
Authors: ALINEJAD H. , ROBINSON P. A. , SKJAERAASEN O. , CAIRNS I. H.
Published: July 2008

A new set of equations describing the coupling of high-frequency electrostatic waves with ion fluctuations is obtained taking into account a non-thermal electron distribution. It is shown that there exist stationary envelope solitons which have qualitatively different structures from the solutions reported earlier. In particular, the Langmuir field envelopes are found with similar width and strong field intensities in comparison to the isothermal case. It is also shown that the presence of the fast or non-thermal electrons significantly modifies the nature of Langmuir solitons in the transition from a single-hump solution to a double-hump solution as the Mach number increases to unity. The low-frequency electrostatic potential associated with the high-frequency Langmuir field has the usual single-dip symmetric structure whose amplitude increases with increasing Mach number. Furthermore, the dip at the center of the double-hump Langmuir soliton is found to become smaller as the proportion of non-thermal electrons increases.
Graph lambda theories
Authors: BUCCIARELLI ANTONIO , SALIBRA ANTONINO
Published: July 2008

A longstanding open problem in lambda calculus is whether there exist continuous models of the untyped lambda calculus whose theory is exactly the λβ or the least sensible λ-theory ℋ (which is generated by equating all the unsolvable terms). A related question is whether, given a class of lambda models, there are a minimal λ-theory and a minimal sensible λ-theory represented by it. In this paper, we give a positive answer to this question for the class of graph models à la Plotkin, Scott and Engeler. In particular, we build two graph models whose theories are the set of equations satisfied in, respectively, any graph model and any sensible graph model. We conjecture that the least sensible graph theory, where ‘graph theory’ means ‘λ-theory of a graph model’, is equal to ℋ, while in one of the main results of the paper we show the non-existence of a graph model whose equational theory is exactly the λβ theory.

Another related question is whether, given a class of lambda models, there is a maximal sensible λ-theory represented by it. In the main result of the paper, we characterise the greatest sensible graph theory as the λ-theory ℬ generated by equating λ-terms with the same Böhm tree. This result is a consequence of the main technical theorem of the paper, which says that all the equations between solvable λ-terms that have different Böhm trees fail in every sensible graph model. A further result of the paper is the existence of a continuum of different sensible graph theories strictly included in ℬ.
Observations of an active thin current sheet
Authors: Runov A. , Baumjohann W. , Nakamura R. , Sergeev V. A. , Amm O. , Frey H. , Alexeev I. , Fazakerley A. N. , Owen C. J. , Lucek E. , André M. , Vaivads A. , Dandouras I. , Klecker B.
Published: July 2008

We analyze observations of magnetotail current sheet dynamics during a substorm between 2330 and 2400 UT on 28 August 2005 when Cluster was in the plasma sheet at [−17.2, −4.49, 0.03] RE (GSM) with the foot points near the IMAGE ground‐based network. Observations from the Cluster spacecraft, ground‐based magnetometers, and the IMAGE satellite showed that the substorm started in a localized region near midnight, expanding azimuthally. A thin current sheet with a thickness of less than 900 km and current density of about 30 nA/m2 was observed during 5 min around the substorm onset. The thinning of the current sheet was accompanied by tailward plasma flow at a velocity of −700 km/s and subsequent reversal to earthward flow at Vx ≈ 500 km/s coinciding with a Bz turning from −5 to +10 nT. The analysis of magnetic and electric fields behavior and particle distributions reveals signatures of impulsive (with ∼1 min timescale) activations of the thin current sheet. These observations were interpreted in the framework of transient reconnection, although the data analysis reveals serious disagreements with the classical 2.5‐D X line model.
Venting of a separate CO2‐rich gas phase from submarine arc volcanoes: Examples from the Mariana and Tonga‐Kermadec arcs
Authors: Lupton John , Lilley Marvin , Butterfield David , Evans Leigh , Embley Robert , Massoth Gary , Christenson Bruce , Nakamura Ko‐ichi , Schmidt Mark
Published: July 2008

Submersible dives on 22 active submarine volcanoes on the Mariana and Tonga‐Kermadec arcs have discovered systems on six of these volcanoes that, in addition to discharging hot vent fluid, are also venting a separate CO2‐rich phase either in the form of gas bubbles or liquid CO2 droplets. One of the most impressive is the Champagne vent site on NW Eifuku in the northern Mariana Arc, which is discharging cold droplets of liquid CO2 at an estimated rate of 23 mol CO2/s, about 0.1% of the global mid‐ocean ridge (MOR) carbon flux. Three other Mariana Arc submarine volcanoes (NW Rota‐1, Nikko, and Daikoku), and two volcanoes on the Tonga‐Kermadec Arc (Giggenbach and Volcano‐1) also have vent fields discharging CO2‐rich gas bubbles. The vent fluids at these volcanoes have very high CO2 concentrations and elevated C/3He and δ13C (CO2) ratios compared to MOR systems, indicating a contribution to the carbon flux from subducted marine carbonates and organic material. Analysis of the CO2 concentrations shows that most of the fluids are undersaturated with CO2. This deviation from equilibrium would not be expected for pressure release degassing of an ascending fluid saturated with CO2. Mechanisms to produce a separate CO2‐rich gas phase at the seafloor require direct injection of magmatic CO2‐rich gas. The ascending CO2‐rich gas could then partially dissolve into seawater circulating within the volcano edifice without reaching equilibrium. Alternatively, an ascending high‐temperature, CO2‐rich aqueous fluid could boil to produce a CO2‐rich gas phase and a CO2‐depleted liquid. These findings indicate that carbon fluxes from submarine arcs may be higher than previously estimated, and that experiments to estimate carbon fluxes at submarine arc volcanoes are merited. Hydrothermal sites such as these with a separate gas phase are valuable natural laboratories for studying the effects of high CO2 concentrations on marine ecosystems.
Global column density retrievals of mesospheric and thermospheric Mg I and Mg II from SCIAMACHY limb and nadir radiance data
Authors: Scharringhausen Marco , Aikin Arthur C. , Burrows John P. , Sinnhuber Miriam
Published: July 2008

The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography instrument (SCIAMACHY) instrument exhibits useful observational abilities to separate meteoric metal total content within different levels of the atmosphere. In this work, we present an algorithm to give the total content and to separate the total column into two partial columns in the thermosphere and the mesosphere, using measurements of resonant radiation by the SCIAMACHY instrument. Limb and nadir measurements are used. The results presented here constitute the first simultaneous measurements of mesospheric and thermospheric column densities including the successful separation of same. We present column density measurements of Mg II and Mg I in the mesosphere and the thermosphere and the total content. The data set considered here covers the latitude range from 80°S to 80°N and covers the time range from 2002 to 2006. Measurements are taken on a global scale to investigate seasonal and spatial variations. Total columns range from 107 to 1010 cm−2, in good agreement with previous satellite measurements and model calculations. The temporal evolution of both Mg I species is investigated over the time range from mid‐2002 until the end of 2006. A pronounced minimum in 2003 and a subsequent increase until 2006 are observed for the ionized species. The global distribution of both Mg I and Mg II is found to be seasonally varying, exhibiting maximum column densities within the summer hemisphere. No significant correlation with the solar activity is found. Increased abundances of Mg II are observed within regions of high geomagnetic activity (i.e., the northern and southern auroral ovals) only if the background abundance of Mg II is low. It is concluded that the increase of Mg II due to particle impact is a minor effect.
Characterization of the composition, structure, and seasonal variation of the mixing layer above the extratropical tropopause as revealed by MOZAIC measurements
Authors: Brioude J. , Cammas J.‐P. , Cooper O. R. , Nedelec P.
Published: July 2008

The chemical composition of the mixing layer above the tropopause, which is mainly influenced by stratosphere troposphere exchange, impacts the chemistry and radiative balance of the troposphere. A better understanding of its seasonal and spatial variation is needed to reduce uncertainties of global chemistry‐transport models. In this paper, we use the Measurements of Ozone, Water Vapour, Nitrogen Oxides and Carbon Monoxide by Airbus In‐Service Aircraft (MOZAIC) ozone and carbon monoxide data from 2003. The five MOZAIC aircraft fly daily between Europe and North America and between Europe and Asia, at 9–12 km crossing the tropopause when transecting upper level troughs. We present a new coordinate system consisting of potential vorticity on the y axis and the angle between the local PV surface and the horizontal on the x axis to study the mixing that occurs in the tropopause region. This coordinate system allows us to view the typical distribution of ozone and CO within upper level troughs. Using in situ measurements and a Lagrangian analysis, we have identified a mixing layer associated with stirring and mixing in the tropopause region between 2 and 6 pvu. Regional variations of the ozone and CO distributions and chemical anomalies between the center and the borders of the upper level troughs are found within the mixing layer.
Modeled and observed atmospheric radiation balance during the West African dry season: Role of mineral dust, biomass burning aerosol, and surface albedo
Authors: Milton S. F. , Greed G. , Brooks M. E. , Haywood J. , Johnson B. , Allan R. P. , Slingo A. , Grey W. M. F.
Published: July 2008

The global radiation balance of the atmosphere is still poorly observed, particularly at the surface. We investigate the observed radiation balance at (1) the surface using the ARM Mobile Facility in Niamey, Niger, and (2) the top of the atmosphere (TOA) over West Africa using data from the Geostationary Earth Radiation Budget (GERB) instrument on board Meteosat‐8. Observed radiative fluxes are compared with predictions from the global numerical weather prediction (NWP) version of the Met Office Unified Model (MetUM). The evaluation points to major shortcomings in the NWP model's radiative fluxes during the dry season (December 2005 to April 2006) arising from (1) a lack of absorbing aerosol in the model (mineral dust and biomass burning aerosol) and (2) a poor specification of the surface albedo. A case study of the major Saharan dust outbreak of 6–12 March 2006 is used to evaluate a parameterization of mineral dust for use in the NWP models. The model shows good predictability of the large‐scale flow out to 4–5 days with the dust parameterization providing reasonable dust uplift, spatial distribution, and temporal evolution for this strongly forced dust event. The direct radiative impact of the dust reduces net downward shortwave (SW) flux at the surface (TOA) by a maximum of 200 W m−2 (150 W m−2), with a SW heating of the atmospheric column. The impacts of dust on terrestrial radiation are smaller. Comparisons of TOA (surface) radiation balance with GERB (ARM) show the “dusty” forecasts reduce biases in the radiative fluxes and improve surface temperatures and vertical thermodynamic structure.
Topography of valley networks on Mars from Mars Express High Resolution Stereo Camera digital elevation models
Authors: Ansan Véronique , Mangold Nicolas , Masson Philippe , Gailhardis Evelyne , Neukum Gerhard
Published: July 2008

Martian valley networks have been identified mainly in the Noachian heavily cratered uplands. The geometry of valley networks can be studied using Mars Orbiter Laser Altimeter (MOLA) altimetry, which is sufficient to map large valleys without a detailed 3‐D shape of valley networks. Imaging from the Mars Express High Resolution Stereo Camera (HRSC) is used to generate digital elevation models (DEMs) with resolution ≤50 m and vertical accuracy <60 m. We studied valleys near Huygens crater and in the Aeolis region both in the Noachian bedrock and on the West Echus plateau in Hesperian bedrock. HRSC DEMs in these areas show that (1) drainage density is 3 times higher than is observed in MOLA data, (2) degree of ramification is 1 order more than with MOLA, (3) transverse valley profiles show a V shape more accurately and a minimum depth of ∼20 m, and (4) higher drainage density shows greater headward extension that is not correlated to greater valley depth. The deepest valleys (400 m) are found in the Huygens region, where the density in the DEM is 0.1 km−1, compared to shallow valleys (<100 m) of the Echus region, where the density is higher (∼0.3 km−1). These regional differences are due to spatially variable preservation and bedrock lithology. Longitudinal profiles suggest variations in duration of activity: profile concavity is only developed in some Noachian terrains. Valleys visible in HRSC images correspond to topographic features in DEMs showing the same geometry as terrestrial valleys thought to be formed by overland flows and seepage.
Meteorological predictions for candidate 2007 Phoenix Mars Lander sites using the Mars Regional Atmospheric Modeling System (MRAMS)
Authors: Michaels T. I. , Rafkin S. C. R.
Published: July 2008

The 2007 Phoenix Mars lander will land in the late afternoon at a high northern latitude in the late northern hemisphere spring season. Various types of Mars atmospheric model simulations (general circulation model, mesoscale, and large‐eddy simulation) were used to investigate the plausible range of meteorological conditions that the lander will likely experience during its landed mission and entry, descent, and landing phase. These studies were carried out in support of Phoenix mission atmospheric risk assessment tasks. The model results reveal a circumpolar jet with associated relatively weak transient baroclinic disturbances that appear not to severely impact the potential Phoenix landing sites, even under differing plausible atmospheric dust loading scenarios. At the local time of landing, modeling results indicate vigorous (dry) planetary boundary layer convection extending from the surface to perhaps 5 km.
Hydrodynamic planetary thermosphere model: 2. Coupling of an electron transport/energy deposition model
Authors: Tian Feng , Solomon Stanley C. , Qian Liying , Lei Jiuhou , Roble Raymond G.
Published: July 2008

An electron transport/energy deposition model is expanded to include atomic nitrogen and is coupled with a 1‐D hydrodynamic thermosphere model. The coupled model is used to investigate the response of the Earth's thermosphere under extreme solar EUV conditions and is compared with previous studies. It is found that (1) the parameterization of Swartz and Nisbet (1972) underestimates the ambient electron heating by photoelectrons significantly in the upper thermosphere of the Earth under conditions with greater than 3 times the present solar EUV irradiance; (2) the transition of the Earth's thermosphere from a hydrostatic equilibrium regime to a hydrodynamic regime occurs at a smaller solar EUV flux condition when enhanced, more realistic, and self‐consistent, ambient electron heating by photoelectrons is accounted for; (3) atomic nitrogen becomes the dominant neutral species in the upper thermosphere (competing against atomic oxygen) under extreme solar EUV conditions, and the electron impact processes of atomic nitrogen are important for both the chemistry and energetics in the corresponding thermosphere/ionosphere; (4) N+ remains a minor ion compared to O+, even when atomic nitrogen dominates the exobase; and (5) adiabatic cooling does not play an important role in electron gas energy budget. These findings highlight the importance of an electron transport/energy deposition model when investigating the thermosphere and ionosphere of terrestrial planets in their early evolutionary stages.
Size‐frequency distributions of rocks on the northern plains of Mars with special reference to Phoenix landing surfaces
Authors: Golombek M. P. , Huertas A. , Marlow J. , McGrane B. , Klein C. , Martinez M. , Arvidson R. E. , Heet T. , Barry L. , Seelos K. , Adams D. , Li W. , Matijevic J. R. , Parker T. , Sizemore H. G. , Mellon M. , McEwen A. S. , Tamppari L. K. , Cheng Y.
Published: July 2008

The size‐frequency distributions of rocks >1.5 m diameter fully resolvable in High Resolution Imaging Science Experiment (HiRISE) images of the northern plains follow exponential models developed from lander measurements of smaller rocks and are continuous with rock distributions measured at the landing sites. Dark pixels at the resolution limit of Mars Orbiter Camera thought to be boulders are shown to be mostly dark shadows of clustered smaller rocks in HiRISE images. An automated rock detector algorithm that fits ellipses to shadows and cylinders to the rocks, accurately measured (within 1–2 pixels) rock diameter and height (by comparison to spacecraft of known size) of ∼10 million rocks over >1500 km2 of the northern plains. Rock distributions in these counts parallel models for cumulative fractional area covered by 30–90% rocks in dense rock fields around craters, 10–30% rock coverage in less dense rock fields, and 0–10% rock coverage in background terrain away from craters. Above ∼1.5 m diameter, HiRISE resolves the same population of rocks seen in lander images, and thus size‐frequency distributions can be extrapolated along model curves to estimate the number of rocks at smaller diameters. Extrapolating sparse rock distributions in the Phoenix landing ellipse indicate <1% chance of encountering a potentially hazardous rock during landing or that could impede the opening of the solar arrays. Extrapolations further suggest rocks large enough to depress the ground ice table and small enough to be picked up or pushed by the robotic arm should be present within reach for study after landing.
Environmental controls on ecosystem‐scale CH4 emission from polygonal tundra in the Lena River Delta, Siberia
Authors: Sachs Torsten , Wille Christian , Boike Julia , Kutzbach Lars
Published: July 2008

We present the first ecosystem‐scale methane flux data from a northern Siberian tundra ecosystem covering the entire snow‐free period from spring thaw until initial freeze‐back. Eddy covariance measurements of methane emission were carried out from the beginning of June until the end of September in the southern central part of the Lena River Delta (72°22′N, 126°30′E). The study site is located in the zone of continuous permafrost and is characterized by Arctic continental climate with very low precipitation and a mean annual temperature of −14.7°C. We found relatively low fluxes of on average 18.7 mg m−2 d−1, which we consider to be because of (1) extremely cold permafrost, (2) substrate limitation of the methanogenic archaea, and (3) a relatively high surface coverage of noninundated, moderately moist areas. Near‐surface turbulence as measured by the eddy covariance system in 4 m above the ground surface was identified as the most important control on ecosystem‐scale methane emission and explained about 60% of the variance in emissions, while soil temperature explained only 8%. In addition, atmospheric pressure was found to significantly improve an exponential model based on turbulence and soil temperature. Ebullition from waterlogged areas triggered by decreasing atmospheric pressure and near‐surface turbulence is thought to be an important pathway that warrants more attention in future studies. The close coupling of methane fluxes and atmospheric parameters demonstrated here raises questions regarding the reliability of enclosure‐based measurements, which inherently exclude these parameters.
Comparing the ability of a genetic algorithm based clustering analysis and a physically based dynamic vegetation model to predict vegetation distribution
Authors: Sun Xiaoming , Wang Guiling
Published: July 2008

This study explores the applicability of data‐driven clustering analysis in predicting vegetation distribution over two continents where water is an important controlling factor for vegetation growth, South America and Africa, and compares the ability of clustering analysis with that of a physically based dynamic vegetation model to predict vegetation distribution. A clustering analysis algorithm based on the genetic‐algorithm‐based K‐means is tested, with the number of clusters determined a priori according to the primary plant functional types observed to exist in the study domain. The most important variables upon which the clustering analysis is based include available water, its seasonality, and evaporative demand. The dynamic vegetation model used is the Community Land Model version 3 coupled with a Dynamic Global Vegetation Model (CLM3‐DGVM) with modifications targeted to address some known biases of the model. Results from both the clustering analysis and the modified CLM3‐DGVM are compared against observations derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). Both methods reasonably reproduced the general pattern of dominant plant functional type distribution. There is no clear winner between the two methods, as the DGVM outperforms the clustering analysis approach in some aspects and is outperformed in others. It is therefore suggested that clustering analysis can be a useful tool in biogeography estimation, although it cannot be used in mechanistic studies as the process‐based DGVMs are.