bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of maternal characteristics on fetal growth in the third trimester: a population‐based study
Authors: Lindell G. , Maršál K. , Källén K.
Published: February 2012

Objectives

To investigate the association between maternal characteristics and fetal growth during the third trimester of pregnancy.

Methods

Using a population‐based perinatal register, 48 809 term singleton pregnancies were identified for which a routine ultrasound examination in the third trimester had been performed between 1995 and 2009. Fetal and infant weight were expressed as gestational age‐specific standard deviation scores (z‐scores) using a Swedish ultrasound‐based reference curve. The growth of each fetus was assessed using the difference between the birth‐weight z‐score and the fetal‐weight z‐score estimated at the ultrasound examination, adjusted for gestational age, and divided by the time elapsed between the ultrasound examination and delivery. Analyses were performed using multivariable linear and polynomial regression analyses.

Results

Positive associations were found between maternal body mass index (BMI), height, pre‐existing diabetes mellitus, female fetal gender and fetal growth, whereas maternal smoking had a negative association. In the univariate analyses, primiparity and parity with four or more previous children were significantly associated with reduced fetal growth, but in the multivariable analysis, no association between parity and fetal growth could be detected. Both univariate and multivariable analyses revealed a significant inverse U‐shaped association between maternal age and fetal growth.

Conclusions

Third‐trimester fetal growth was positively associated with increasing maternal BMI, height and pre‐existing diabetes mellitus, and negatively associated with maternal smoking.
Population‐based review of tetralogy of Fallot with absent pulmonary valve: is prenatal diagnosis really associated with a poor prognosis?
Authors: Mivelaz Y. , Lim K. I. , Templeton C. , Campbell A. I. , Potts J. E. , Sandor G. G. S.
Published: February 2012

Objectives

Tetralogy of Fallot with absent pulmonary valve syndrome (TETAPV) is reported in obstetric literature to have an extremely poor prognosis. We sought to determine the clinical outcome associated with TETAPV and whether prenatal diagnosis confers a poor prognosis.

Methods

All cases of TETAPV diagnosed in British Columbia between 1980 and 2009 were reviewed and grouped according to time of diagnosis, either prenatal or postnatal. The groups were compared with respect to mortality, respiratory problems, number of interventions and functional capacity at last follow‐up.

Results

Eight and 11 patients were included in the prenatally and postnatally diagnosed groups, with overall long‐term survival of 71% and 82%, respectively. There was no significant difference in mortality, frequency of preoperative intubation, number of interventions or functional capacity between groups.

Conclusion

From a population‐based retrospective analysis of TETAPV cases identified over three decades it is concluded that the prognosis for TETAPV is better than that previously reported in the obstetric literature. This information should be used to guide prenatal counseling. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Toric K3-fibred Calabi-Yau manifolds with del Pezzo divisors for string compactifications
Authors: Cicoli Michele , Kreuzer Maximilian , Mayrhofer Christoph
Published: February 2012

Abstract

We analyse several explicit toric examples of compact K3-fibred Calabi-Yau three-folds. These manifolds can be used for the study of string dualities and are crucial ingredients for the construction of LARGE Volume type IIB vacua with promising applications to cosmology and particle phenomenology. In order to build a phenomenologically viable model, on top of the two moduli corresponding to the base and the K3 fibre, we demand also the existence of two additional rigid divisors: the first supporting the non-perturbative effects needed to achieve moduli stabilisation, and the second allowing the presence of chiral matter on wrapped D-branes. We clarify the topology of these rigid divisors by discussing the interplay between a diagonal structure of the Calabi-Yau volume and D-terms. Del Pezzo divisors appearing in the volume form in a completely diagonal way are natural candidates for supporting non-perturbative effects and for quiver constructions, while ‘non-diagonal’ del Pezzo and rigid but not del Pezzo divisors are particularly interesting for model building in the geometric regime. Searching through the existing list of four dimensional reflexive lattice polytopes, we find 158 examples admitting a Calabi-Yau hypersurface with a K3 fibration and four Kähler moduli where at least one of the toric divisors is a ‘diagonal’ del Pezzo. We work out explicitly the topological details of a few examples showing how, in the case of simplicial polytopes, all the del Pezzo divisors are ‘diagonal’, while ‘non-diagonal’ ones appear only in the case of non-simplicial polytopes. A companion paper will use these results in the study of moduli stabilisation for globally consistent explicit Calabi-Yau compactifications with the local presence of chirality.
Malt-induced premature yeast flocculation: current perspectives
Authors: Panteloglou Apostolos G , Smart Katherine A , Cook David J
Published: February 2012

Premature yeast flocculation (PYF) is a sporadic problem for the malting and brewing industries which can have significant financial and logistical implications. The condition is characterised by abnormally heavy (and sometimes early) flocculation of yeast during brewery fermentations. The resulting low suspended yeast cell counts towards the end of the fermentation can result in flavour defects and incomplete attenuation (fermentation of sugars to alcohol). Despite several decades of research into the phenomenon, its precise nature and mechanisms have not been fully elucidated. In part this is because the term PYF has become a ‘catch-all’ syndrome which can have multiple origins. Furthermore, there are complex interactions in the malting and brewing processes which together mean that the PYF status of a malt sample is hard to predict at a generic level. Whether or not PYF is observed depends not only on barley quality, but on process factors in the maltings and to a substantial extent on the brewing yeast strain concerned. This article highlights the significance of PYF, and reviews current knowledge relating to the origins of this complex phenomenon.
Single dose NTBC‐treatment of hereditary tyrosinemia type I
Authors: Schlune A. , Thimm E. , Herebian D. , Spiekerkoetter U.
Published: February 2012

NTBC (2‐(2‐nitro‐4‐trifluoromethylbenzoyl)‐1,3cyclohexanedione) is the mainstay of treatment in tyrosinemia type 1 (HT 1). The current recommendation is to divide the total daily dose of NTBC into two doses. We monitored the plasma NTBC concentrations in a series of seven patients who were changed from multiple divided doses to a single daily dose of NTBC. Two additional patients were started on a single daily dose of NTBC after the diagnosis of HT 1 was established. In three patients, NTBC kinetics were performed over 6 and 24 hours, respectively. The use of multiple divided doses or a single daily dose did not significantly affect plasma NTBC concentrations or the mean daily dose needed to attain therapeutic plasma NTBC concentrations. Moreover, kinetic studies demonstrated that plasma NTBC concentrations were completely stable over a period of 24 hours with a single dose regimen, as expected given the known NTBC plasma half life of 54 hours. Although these preliminary results need to be confirmed in more patients, our findings show that administration of NTBC in a single daily dose may be as effective as a multiple‐dose regimen in reaching therapeutic plasma NTBC concentrations and suppressing succinylacetone formation in patients with HT 1. In fact, single dose treatment may increase patients’ compliance with the drug treatment and improve metabolic control.
Hispanic Infants with Cystic Fibrosis Show Low CFTR Mutation Detection Rates in the Illinois Newborn Screening Program
Authors: Watts Kimberly Danieli , Layne Benjamin , Harris Ann , McColley Susanna A.
Published: February 2012

States develop specific protocols for cystic fibrosis (CF) newborn screening to reflect the population served. We hypothesized that mutation distribution and detection rates would differ between Hispanic and non‐Hispanic CF patients diagnosed by IL newborn screen with more Hispanic infants carrying mutations not detected by the state panel. Data from CF cases diagnosed via newborn screen in IL between 3/1/2008 and 10/31/2010 were reviewed. More Hispanic infants with CF had one or more undefined mutations after screening, in comparison to non‐Hispanic Caucasian patients (40% vs. 9.5%; p < 0.002). The risk of having a positive diagnosis of CF with only one mutation noted by positive newborn screen increases 2‐fold in Hispanic Caucasian versus non‐Hispanic Caucasian infants (5% vs. 2.4%). Health care providers must be aware of the limitations of CF newborn screening to ensure appropriate counseling and prompt referral for a positive newborn screen, even when zero or one mutations are identified.
Optimized Production of MLM Triacylglycerols Catalyzed by Immobilized Heterologous Rhizopus oryzae Lipase
Authors: Nunes P. A. , Pires‐Cabral P. , Guillén M. , Valero F. , Ferreira‐Dias S.
Published: February 2012

Response surface methodology was used to model and optimize the acidolysis of virgin olive oil with caprylic (C8:0) or capric (C10:0) acids, aimed at the production of low caloric triacylglycerols (TAG) of MLM type, in solvent free media, catalyzed by the heterologous Rhizopus oryzae lipase (r‐ROL) immobilized in Eupergit® C. This lipase was produced in the methylotrophic yeast Pichia pastoris Muts phenotype (experiments with C10:0) or a Mut+ phenotype (experiments with C8:0), under different operational conditions. The r‐ROL used in experiments with C10:0 presented a hydrolytic activity about 5 times of that presented by r‐ROL used in acidolysis with C8:0. The experiments were carried out following a central composite rotatable design, as a function of the molar ratio (MR) medium chain fatty acid/TAG (1.6–4.4) and temperature (25–55 °C). Convex surfaces described by second order polynomials as a function of MR and temperature were well fitted to fatty acid incorporation values. After 24‐h reaction, the predicted maximum incorporation of caprylic (15.5 mol%) or capric (33.3 mol%) acids in olive oil occurs at 37 and 35 °C, respectively, and at C8:0/TAG of 2.8:1 or C10:0/TAG of 3:1. These predicted optima were experimentally validated. Fermentation conditions used in r‐ROL production highly affected hydrolytic activity and to a lesser extent interesterification activity.
Multidetector CT cystography for imaging colovesical fistulas and iatrogenic bladder leaks
Authors: Tonolini Massimo , Bianco Roberto
Published: February 2012

Multidetector computed tomography (MDCT) cystography currently represents the modality of choice to image the urinary bladder in traumatized patients. In this review we present our experience with MDCT cystography applications outside the trauma setting, particularly for diagnosing bladder fistulas and leaks. A detailed explanation is provided concerning exam preparation, acquisition technique, image reconstruction and interpretation. Colovesical fistulas most commonly occur as a complication of sigmoid diverticular disease, and often remain occult after extensive diagnostic work-up including cystoscopy and contrast-enhanced CT. We consistently achieved accurate preoperative visualization of colovesical fistulas using MDCT cystography. Urinary leaks and injuries represent a non-negligible occurrence after pelvic surgery, particularly obstetric and gynaecological procedures: in our experience MDCT cystography is useful to investigate iatrogenic bladder leaks or fistulas. In our opinion, MDCT cystography should be recommended as the first line modality for direct visualization or otherwise confident exclusion of both spontaneous enterovesical fistulas and bladder injuries following instrumentation procedures, obstetric or surgical interventions.

Main Messages

• Explanation of exam preparation, acquisition technique, image reconstruction and interpretation.

• Preoperative visualization of colovesical fistulas, usually secondary to sigmoid diverticulitis.

• Visualization or exclusion of iatrogenic bladder injuries following instrumentation or surgery.
Increased miR‐222 in H. pylori‐associated gastric cancer correlated with tumor progression by promoting cancer cell proliferation and targeting RECK
Authors: Li Na , Tang Bin , Zhu En-Dong , Li Bo-sheng , Zhuang Yuan , Yu Shu , Lu Dong-shui , Zou Quan-Ming , Xiao Bin , Mao Xu-Hu
Published: February 2012

Little is known about the potential role of microRNAs (miRNAs) in the carcinogenesis of gastric cancer induced by Helicobacter pylori (H. pylori). Here, we showed that microRNA‐222 (miR‐222) was up‐regulated in H. pylori‐infected gastric mucosa and gastric cancer. Ectopic expression of miR‐222 promoted cell proliferation and colony formation in vitro. Mechanistically, we identified RECK as a novel target of miR‐222, and also confirmed their relationship by the inverse correlation of mRNA expression ex vivo. Furthermore, we found that RNA interference silencing of RECK can mimic the oncogenic effects of miR‐222. Collectively, H. pylori may function as an initiator in the process of carcinogenesis by up‐regulating miR‐222, which further participates in the progression of cancer by promoting proliferation and inhibiting RECK.
Pro42 and Val45 of staphylokinase modulate intermolecular interactions of His43–Tyr44 pair and specificity of staphylokinase–plasmin activator complex
Authors: Singh Satish , Ashish  , Dikshit Kanak L.
Published: February 2012

SAK
enzymaticly reacts
Pg
by enzymatic study (View Interaction: 1, 2, 3, 4, 5)
Neocortical disruption and behavioral impairments in rats following in utero RNAi of candidate dyslexia risk gene Kiaa0319
Authors: Szalkowski Caitlin E. , Fiondella Christopher G. , Galaburda Albert M. , Rosen Glenn D. , LoTurco Joseph J. , Fitch R. Holly
Published: February 2012

Within the last decade several genes have been identified as candidate risk genes for developmental dyslexia. Recent research using animal models and embryonic RNA interference (RNAi) has shown that a subset of the candidate dyslexia risk genes—DYX1C1, ROBO1, DCDC2, KIAA0319—regulate critical parameters of neocortical development, such as neuronal migration. For example, embryonic disruption of the rodent homolog of DYX1C1 disrupts neuronal migration and produces deficits in rapid auditory processing (RAP) and working memory—phenotypes that have been reported to be associated with developmental dyslexia. In the current study we used a modified prepulse inhibition paradigm to assess acoustic discrimination abilities of male Wistar rats following in utero RNA interference targeting Kiaa0319. We also assessed spatial learning and working memory using a Morris water maze (MWM) and a radial arm water maze. We found that embryonic interference with this gene resulted in disrupted migration of neocortical neurons leading to formation of heterotopia in white matter, and to formation of hippocampal dysplasia in a subset of animals. These animals displayed deficits in processing complex acoustic stimuli, and those with hippocampal malformations exhibited impaired spatial learning abilities. No significant impairment in working memory was detected in the Kiaa0319 RNAi treated animals. Taken together, these results suggest that Kiaa0319 plays a role in neuronal migration during embryonic development, and that early interference with this gene results in an array of behavioral deficits including impairments in rapid auditory processing and simple spatial learning.
Gesund und aktiv älter werden – Kooperationen der BZgA mit den Bundesändern
Authors: Köster Monika , Altgeld Thomas
Published: February 2012

Einleitung

Im Rahmen ihres Schwerpunkts „Gesund und aktiv älter werden“ fördert die Bundeszentrale für gesundheitliche Aufklärung (BZgA) die Vernetzung von Bundes-, Länder- und regionaler Ebene. Mit Blick auf eine zielgerichtete Zusammenarbeit führt die BZgA Regionalkonferenzen in allen Bundesländern durch - gemeinsam mit den Ministerien und Akteuren auf Länderebene. Vor dem Hintergrund des demografischen Wandels werden zentrale Herausforderungen, Erfolg versprechende Strategien und Möglichkeiten der Zusammenarbeit auf dem Gebiet der Gesundheitsförderung ressourcen- und umsetzungsorientiert erörtert. Hierbei stehen die Vernetzung unterschiedlicher Professionen und Akteure, der Transfer guter Praxis sowie Fragen der Qualitätssicherung im Vordergrund.
GLOBAL WELL-POSEDNESS FOR THE GENERALISED FOURTH-ORDER SCHRÖDINGER EQUATION
Authors: WANG YUZHAO
Published: February 2012

We study the Cauchy problem for the generalised fourth-order Schrödinger equation for data u0 in critical Sobolev spaces $\dot {H}^{1/2-3/2k}$. With small initial data we obtain global well-posedness results. Our proof relies heavily on the method developed by Kenig et al. [‘Well-posedness and scattering results for the generalised Korteweg–de Vries equation via the contraction principle’, Commun. Pure Appl. Math.46 (1993), 527–620].
Pseudoprime Reductions of Elliptic Curves – CORRIGENDUM
Authors: COJOCARU ALINA CARMEN , LUCA FLORIAN , SHPARLINSKI IGOR E.
Published: February 2012

Unfortunately, there are two inaccuracies in the argument of [CLS]. First, the statements of Lemmas 3, 4, 6, and 7 of [CLS] hold only under the additional condition gcd(m, ME) = 1 for some integer ME ≥ 1 depending only on E. Second, the divisibility condition (3·6) in [CLS] implies that tb(ℓ) | nE(p)−1 (rather than tb(ℓ) | nE(p), as it was erroneously claimed on p. 519 in [CLS]). In particular, instead of the divisibility ℓtb(ℓ) | nE(p) (see the last displayed formula on p. 519 in [CLS]), we conclude that for every prime ℓ | L there is an integer aℓ such that
(0.1)
However, the final result is correct and can easily be recovered. To do so, we remark that under the condition gcd(m,ME) =1, we have full analogues of Lemmas 6, 7, 9, and 10 of [CLS] for the function Π(x;m,a) defined as the number of primes p ≤ x with nE(p) ≡ a (mod m) (rather than just for Π(x;m) = Π(x;m,0) as in [CLS]). Define ρ*(n) as the largest square-free divisor of n which is relatively prime to ME. We then derive from (0.1) above that

Therefore
(0.2)
Since

we see that (0.2) above implies the bound (3·7) from [CLS], and the result now follows without any further changes.
The Interdependence of Subtype and Severity: Contributions of Clinical and Neuropsychological Features to Melancholia and Non-melancholia in an Outpatient Sample
Authors: Quinn Candice , Harris Anthony , Kemp Andrew
Published: February 2012

Major depressive disorder is often considered to be a homogenous disorder that changes in terms of severity; however, the presence of distinct subtypes and a variety of presenting symptoms suggests much heterogeneity. Aiming to better understand the relationship between heterogeneity and diagnosis we used an exploratory approach to identify subtypes of depression on the basis of clinical symptoms and neuropsychological performance. Cluster analysis identified two groups of patients distinguished by level of cognitive dysfunction with the more severe cluster being associated with melancholic depression. While the relationship between cluster and subtype was significant, only 58% of melancholic patients were assigned to cluster 1 (the more severe cluster) and 66% of non-melancholic patients assigned to cluster 2. Subtypes also displayed a distinctive profile of impairment such that melancholic patients (n = 65) displayed more variability in attention while non-melancholic patients (n = 59) displayed memory recall impairment. While melancholia and non-melancholia are associated with a more severe and less severe form of depression respectively, findings indicate that differences between melancholia and non-melancholia are more than simple variation on severity. In summary, findings provide support for the heterogeneity of depression. (JINS, 2012, 18, 361–369)
A New Approach to the Determination of Concentration Profiles in Atom Probe Tomography
Authors: Felfer Peter J. , Gault Baptiste , Sha Gang , Stephenson Leigh , Ringer Simon P. , Cairney Julie M.
Published: February 2012

Atom probe tomography (APT) provides three-dimensional analytical imaging of materials with near-atomic resolution using pulsed field evaporation. The processes of field evaporation can cause atoms to be placed at positions in the APT reconstruction that can deviate slightly from their original site in the material. Here, we describe and model one such process—that of preferential retention of solute atoms in multicomponent systems. Based on relative field evaporation probabilities, we calculate the point spread function for the solute atom distribution in the “z,” or in-depth direction, and use this to extract more accurate solute concentration profiles.
Structural Factors Affecting the Assignment of Word Stress in German
Authors: Röttger Timo B. , Domahs Ulrike , Grande Marion , Domahs Frank
Published: February 2012

This paper aims to shed light on regularities underlying German stress assignment. The results of a pseudoword production task suggest that rhyme complexity of the final syllable is a strong predictor of main stress position in German. We also found that antepenult rhyme complexity and orthographic rhyme structure have significant effect on stress assignment. In general, the effects seem to be probabilistic rather than categorical. Our results suggest that phonological theories of German word stress need to allow for multiple probabilistic factors, including syllabic structure of all stressable syllables and orthographic coding.*
Diverse microbial species survive high ammonia concentrations
Authors: Kelly Laura C. , Cockell Charles S. , Summers Stephen
Published: February 2012

Planetary protection regulations are in place to control the contamination of planets and moons with terrestrial micro-organisms in order to avoid jeopardizing future scientific investigations relating to the search for life. One environmental chemical factor of relevance in extraterrestrial environments, specifically in the moons of the outer solar system, is ammonia (NH3). Ammonia is known to be highly toxic to micro-organisms and may disrupt proton motive force, interfere with cellular redox reactions or cause an increase of cell pH. To test the survival potential of terrestrial micro-organisms exposed to such cold, ammonia-rich environments, and to judge whether current planetary protection regulations are sufficient, soil samples were exposed to concentrations of NH3from 5 to 35% (v/v) at −80°C and room temperature for periods up to 11 months. Following exposure to 35% NH3, diverse spore-forming taxa survived, including representatives of theFirmicutes(Bacillus, Sporosarcina, Viridibacillus, Paenibacillus, StaphylococcusandBrevibacillus) andActinobacteria(Streptomyces). Non-spore forming organisms also survived, includingProteobacteria(Pseudomonas) andActinobacteria(Arthrobacter) that are known to have environmentally resistant resting states.Clostridiumspp. were isolated from the exposed soil under anaerobic culture. High NH3was shown to cause a reduction in viability of spores over time, but spore morphology was not visibly altered. In addition to its implications for planetary protection, these data show that a large number of bacteria, potentially including spore-forming pathogens, but also environmentally resistant non-spore-formers, can survive high ammonia concentrations.
Methodological Advances for Detecting Physiological Synchrony During Dyadic Interactions
Authors: McAssey Michael P. , Helm Jonathan , Hsieh Fushing , Sbarra David A. , Ferrer Emilio
Published: February 2012

A defining feature of many physiological systems is their synchrony and reciprocal influence. An important challenge, however, is how to measure such features. This paper presents two new approaches for identifying synchrony between the physiological signals of individuals in dyads. The approaches are adaptations of two recently-developed techniques, depending on the nature of the physiological time series. For respiration and thoracic impedance, signals that are measured continuously, we use Empirical Mode Decomposition to extract the low-frequency components of a nonstationary signal, which carry the signal’s trend. We then compute the maximum cross-correlation between the trends of two signals within consecutive overlapping time windows of fixed width throughout each of a number of experimental tasks, and identify the proportion of large values of this measure occurring during each task. For heart rate, which is output discretely, we use a structural linear model that takes into account heteroscedastic measurement error on both series. The results of this study indicate that these methods are effective in detecting synchrony between physiological measures and can be used to examine emotional coherence in dyadic interactions.
Geomagnetic detection of the sectorial solar magnetic field and the historical peculiarity of minimum 23–24
Authors: Love Jeffrey J. , Joshua Rigler E. , Gibson Sarah E.
Published: February 2012

Analysis is made of the geomagnetic‐activityaaindex covering solar cycle 11 to the beginning of 24, 1868–2011. Autocorrelation shows 27.0‐d recurrent geomagnetic activity that is well‐known to be prominent during solar‐cycle minima; some minima also exhibit a smaller amount of 13.5‐d recurrence. Previous work has shown that the recent solar minimum 23–24 exhibited 9.0 and 6.7‐d recurrence in geomagnetic and heliospheric data, but those recurrence intervals were not prominently present during the preceding minima 21–22 and 22–23. Using annual‐averages and solar‐cycle averages of autocorrelations of the historicalaadata, we put these observations into a long‐term perspective: none of the 12 minima preceding 23–24 exhibited prominent 9.0 and 6.7‐d geomagnetic activity recurrence. We show that the detection of these recurrence intervals can be traced to an unusual combination of sectorial spherical‐harmonic structure in the solar magnetic field and anomalously low sunspot number. We speculate that 9.0 and 6.7‐d recurrence is related to transient large‐scale, low‐latitude organization of the solar dynamo, such as seen in some numerical simulations.
A global model: Empirical orthogonal function analysis of total electron content 1999–2009 data
Authors: A Ercha , Zhang Donghe , Ridley Aaron J. , Xiao Zuo , Hao Yongqiang
Published: February 2012

A global ionospheric total electron content (TEC) model based on the empirical orthogonal function (EOF) analysis method is constructed using the global ionosphere maps provided by Jet Propulsion Laboratory during the years 1999–2009. The importance of different types of variation to the overall TEC variability as well as the influence of solar radiation and geomagnetic activity toward TEC can be well represented by the characteristics of EOF base functions Ek and associated coefficients Pk. The quick convergence of EOF decomposition makes it possible to use the first four orders of the EOF series to represent 99.04% of the overall variance of the original data set. E1 represents the essential feature of global spatial and diurnal variation of the TEC. E2 contains a hemispherically asymmetric pattern manifesting the summer‐to‐winter annual variation. E3 and E4 can well reflect the equatorial anomaly phenomenon. P1 contains an obvious solar cycle variation pattern as well as annual and semiannual variation components. P2 mainly includes an annual fluctuation component. P3 has a strong annual variation and a weak seasonal variation pattern. P4 has both evident annual and semiannual oscillation components. The Fourier series as a combination of trigonometric and linear functions are used to represent the solar cycle, annual, and semiannual variation of the coefficients. Therefore the global TEC model is established through incorporating the modeled EOF series. The accuracy and quality of the model have been validated through the model‐data comparison, which indicates that the model can reflect the majority of the variations and the feature of temporal‐spatial distribution of the global ionospheric TEC.
Longitudinal variation of ionospheric vertical drifts during the 2009 sudden stratospheric warming
Authors: Fang Tzu‐Wei , Fuller‐Rowell Tim , Akmaev Rashid , Wu Fei , Wang Houjun , Anderson David
Published: February 2012

The Whole Atmospheric Model (WAM) initialized with a data assimilation scheme is capable of simulating real sudden stratospheric warming (SSW) events. The electrodynamics in the Coupled Thermosphere Ionosphere and Plasmasphere with Electrodynamics model (CTIPe) was driven by the WAM thermospheric winds in January 2009 to study the response of ionospheric drifts during the SSW. Simulation results are compared with observations of the vertical drift at Jicamarca and the equatorial electrojet (EEJ) in the Asian sectors. Early morning upward drift and afternoon downward drift are reproduced in all longitudes in the simulations, and are consistent with the available observations. Results also show that the occurrence time of the early morning upward drift and afternoon downward drift have significant phase differences between different longitudes. Simulations suggest that during the SSW the longitude dependence of the amplitude and phase of the equatorial vertical plasma drift is caused by the changing magnitudes of the migrating tides modulated by the geometry of the geomagnetic field. Some additional day‐to‐day variability and modulation of the phase structures at different longitudes in ionospheric vertical drifts during the SSW are possibly produced by the short‐term changes in the non‐migrating tides and by planetary waves.
The role of air‐sea fluxes in Subantarctic Mode Water formation
Authors: Holte James W. , Talley Lynne D. , Chereskin Teresa K. , Sloyan Bernadette M.
Published: February 2012

Two hydrographic surveys and a one‐dimensional mixed layer model are used to assess the role of air‐sea fluxes in forming deep Subantarctic Mode Water (SAMW) mixed layers in the southeast Pacific Ocean. Forty‐two SAMW mixed layers deeper than 400 m were observed north of the Subantarctic Front during the 2005 winter cruise, with the deepest mixed layers reaching 550 m. The densest, coldest, and freshest mixed layers were found in the cruise's eastern sections near 77°W. The deep SAMW mixed layers were observed concurrently with surface ocean heat loss of approximately −200 W m−2. The heat, momentum, and precipitation flux fields of five flux products are used to force a one‐dimensional KPP mixed layer model initialized with profiles from the 2006 summer cruise. The simulated winter mixed layers generated by all of the forcing products resemble Argo observations of SAMW; this agreement also validates the flux products. Mixing driven by buoyancy loss and wind forcing is strong enough to deepen the SAMW layers. Wind‐driven mixing is central to SAMW formation, as model runs forced with buoyancy forcing alone produce shallow mixed layers. Air‐sea fluxes indirectly influence winter SAMW properties by controlling how deeply the profiles mix. The stratification and heat content of the initial profiles determine the properties of the SAMW and the likelihood of deep mixing. Summer profiles from just upstream of Drake Passage have less heat stored between 100 and 600 m than upstream profiles, and so, with sufficiently strong winter forcing, form a cold, dense variety of SAMW.
Localization of microbarom sources using the IMS infrasound network
Authors: Landès Matthieu , Ceranna Lars , Le Pichon Alexis , Matoza Robin S.
Published: February 2012

Multiyear continuous infrasound monitoring with the global International Monitoring System (IMS) demonstrates that microbaroms, generated by nonlinear interaction of opposing oceanic surface waves, are globally observed at equatorial, middle, and high latitudes. Direction of arrival of microbarom signals are systematically estimated at all IMS infrasound stations. Using a cross‐bearing method, we perform a monthly localization of worldwide microbarom sources. At most stations, microbarom detections show clear seasonal trends, driven by stratospheric wind reversals and source effects. Five‐year averaging of the detections provides global and statistical observations of seasonal source variations. Our microbarom source locations represent a first attempt to infer ocean swell characteristics from global and long‐term measurements. We show that the monthly averaged source locations exhibit clear seasonal switching between the northern and southern hemispheres. Such an approach can help with evaluating the network detection capability, and provides new insights into quantitative relationships between infrasonic observables, atmospheric specifications, and ocean–atmosphere interactions.
Methane transport mechanisms and isotopic fractionation in emergent macrophytes of an Alaskan tundra lake
Authors: Chanton Jeffrey P. , Martens Christopher S. , Kelley Cheryl A. , Crill Patrick M. , Showers William J.
Published: February 2012

The carbon isotopic composition of methane emitted by the Alaskan emergent aquatic plantsArctophila fulva, a tundra mid‐lake macrophyte, andCarex rostrata, a tundra lake margin macrophyte, was −58.6 ± 0.5 (n=2) and −66.6±2.5 (n= 6) ‰ respectively. The methane emitted by these species was found to be depleted in13C by 12‰ and 18‰, relative to methane withdrawn from plant stems 1 to 2 cm below the waterline. As the macrophyte‐mediated methane flux represented approximately 97% of the flux from these sites, these results suggest the more rapid transport of12CH4relative to13CH4through plants to the atmosphere. This preferential release of the light isotope of methane, possibly combined with CH4oxidation, caused the buildup of the heavy isotope within plant stems. Plant stem methane concentrations ranged from 0.2 to 4.0% (, 1.4; standard deviation (sd), 0.9;n=28) inArctophila, with an isotopic composition of −46.1±4.3 ‰ (n= 8).Carexstem methane concentrations were lower, ranging from 150 to 1200 ppm (, 500; standard deviation, 360; n = 8), with an isotopic composition of −48.3±1.4‰ (n=3). Comparisons of the observed isotopic fractionations with those predicted from gas phase effusion and diffusion coefficients suggest a combination of one or both of these gas transport mechanisms with bulk (non‐fractionationating) flow.
Emissions of biogenic sulfur gases from Alaskan tundra
Authors: Hines Mark E. , Morrison Michael C.
Published: February 2012

Fluxes of the biogenic sulfur gases carbonyl sulfide (COS), dimethyl sulfide (DMS), methyl mercaptan (MeSH), and carbon disulfide (CS2) were determined for several freshwater and coastal marine tundra habitats using a dynamic enclosure method and gas chromatography. In the freshwater tundra sites, highest emissions, with a mean of 6.0 nmol m−2 h−1 (1.5–10) occurred in the water‐saturated wet meadow areas inhabited by grasses, sedges and Sphagnum mosses. In the drier upland tundra sites, highest fluxes occurred in areas inhabited by mixed vegetation and labrador tea at 3.0 nmol m−2 h−1 (0–8.3) and lowest fluxes were from lichen‐dominated areas at 0.9 nmol m−2 h−1. Sulfur emissions from a lake surface were also low at 0.8 nmol m−2 h−1. Of the compounds measured, DMS was the dominant gas emitted from all of these sites. Sulfur emissions from the marine sites were up to 20‐fold greater than fluxes in the freshwater habitats and were also dominated by DMS. Emissions of DMS were highest from intertidal soils inhabited by Carex subspathacea (150–250 nmol m−2 h−1). This Carex sp. was grazed thoroughly by geese and DMS fluxes doubled when goose feces were left within the flux chamber. Emissions were much lower from other types of vegetation which were more spatially dominant. Sulfur emissions from tundra were among the lowest reported in the literature. When emission data were extrapolated to include all tundra globally, the global flux of biogenic sulfur from this biome is 2–3 × 108 g yr−1. This represents less than 0.001% of the estimated annual global flux (∼50 Tg) of biogenic sulfur and <0.01% of the estimated terrestrial flux. The low emissions are attributed to the low availability of sulfate, certain hydrological characteristics of tundra, and the tendency for tundra to accumulate organic matter.
Numerical simulation of the ozone chemistry observed over forested tropical areas during DECAFE experiments
Authors: Lopez A. , Huertas M. L. , Lacome J. M.
Published: February 2012

During Dynamique et Chimie de l'Atmosphère en Forêt Equatoriale (DECAFE) experiments, ozone mixing ratios higher than 65 ppb have been detected in the northern equatorial continental layer above the monsoon layer. In order to understand these data we have carried out simulation experiments with a numerical model which had been developed earlier in our laboratory. These studies show that the large amounts of ozone detected cannot be only due to the chemistry of biogenic emissions in forested areas. A remote origin related to the presence of neighboring savanna areas must be considered. The amounts of remote emissions in NO and light hydrocarbons (HC) necessary to account for the observed ozone ratios should be of the order of 400 μg N/m2h and 1800 μg C/m2h, respectively. These values can be interpreted in terms of biogenic biomass combustion. On the basis of the hypothesis it is shown that biogenic emissions coming from the forest account only for 20% of the total amount of ozone measured.
Methane emissions from tundra environments in the Yukon‐Kuskokwim delta, Alaska
Authors: Bartlett Karen B. , Crill Patrick M. , Sass Ronald L. , Harriss Robert C. , Dise Nancy B.
Published: February 2012

Over a 6‐week period from July 3 to August 10, 1988, we made measurements of the flux of methane by enclosure techniques from major tundra environments in the Yukon‐Kuskokwim Delta of Alaska (60°45′N). Emissions from wet meadow tundra averaged 144 ± 31 mg CH4/m2/d and ranged from 15.6 to 426 mg CH4/m2/d, varying with soil moisture and temperature. Flux from the drier upland tundra was approximately 2 orders of magnitude lower and averaged 2.3 ± 1.1 mg CH4/m2/d. Consumption of ambient levels of methane was sporadically measured at these drier sites, and emissions ranged between −2.1 and 18.1 mg CH4/m2/d. Tundra lakes emit methane from the open water surface as well as from fringing aquatic vegetation. The presence of vegetation significantly enhanced flux over open water rates. Average fluxes from a variety of sites with vegetation ranged between 62.7 and 153.5 mg CH4/m2/d. Calculated diffusive fluxes from open water varied with lake size, the large lakes emitting 3.8 mg CH4/m2/d and small lakes emitting an average of 77 mg CH4/m2/d. An updated estimate of global emissions from tundra indicates an annual flux of approximately 11 ± 3 Tg CH4.
Sulfur gases and aerosols in and above the equatorial African rain forest
Authors: Bingemer H. G. , Andreae M. O. , Andreae T. W. , Artaxo P. , Helas G. , Jacob D. J. , Mihalopoulos N. , Nguyen B. C.
Published: February 2012

We determined the distribution of gaseous and particulate sulfur compounds in the canopy of the tropical rain forest of northern Congo and the overlying atmosphere during February 12–25, 1988. Hydrogen sulfide and dimethylsulfide decayed exponentially with altitude from approximately 30–40 ppt at ground level to 3–5 ppt at around 3 km altitude. Emission fluxes from the forest to the atmosphere were estimated by fitting a one‐dimensional time‐dependent numerical model of chemistry and transport of the sulfur compounds to their observed vertical profiles. Emission fluxes of 0.6–1.0 nmol H2S m−2 min−1 and 0.3–0.7 nmol DMS m−2 min−1 were consistent with the observed vertical profiles of H2S and DMS. These fluxes compare well with fluxes reported previously for the Amazon rain forest during the dry season and support the view of a subordinate role of land biota in the global cycling of sulfur. The particulate sulfur concentration of 248 ppt was found below the forest canopy. Biomass burning is considered to be an important contributor to this particulate sulfur. Carbonyl sulfide was found to be enhanced above the 500 ppt tropospheric background throughout the mixing layer of 2–3 km depth, likely due to biomass burning.
Tropospheric ozone and aerosol observations: The Alaskan Arctic
Authors: Gregory Gerald L. , Anderson Bruce E. , Warren Linda S. , Browell Edward V. , Bagwell Donald R. , Hudgins Charles H.
Published: February 2012

NASA's Arctic Boundary Layer Expedition (ABLE 3A) conducted during the summer of 1988 focused on the distribution of trace species in the Alaskan Arctic troposphere (altitudes <7 km) and the relative importance of surface sources/sinks, local emissions, distant transport, and tropospheric/stratospheric exchange. In situ ozone and aerosol number density and size data obtained during aircraft flights from Point Barrow and Bethel, Alaska, are discussed. Data are also presented for the ferry flights between Wallops Island, Virginia, and Point Barrow, Alaska, via Thule, Greenland. The major source of summer ozone for the troposphere is the intrusion of stratospheric air and subsequent transport to the lower altitudes. Photochemistry of mixed layer emissions and ozone transported from high northern latitude urban/industrialized areas do not appear to play major roles as sources of ozone for the Alaska region. Ozone gradients reflect the loss at the surface and supply from the stratosphere. Free‐tropospheric ozone (3‐ to 7‐km altitude) averaged 74 ppbv compared to 32 ppbv for the mixed layer. All four mixed layers studied (water, wet tundra, dry tundra, and boreal forest) are net ozone sinks. Ozone loss mechanisms are a combination of the destruction via photochemistry, chemical reactions with surface emissions, and direct loss through deposition to the surface. The boreal forest is the most efficient of the ozone sinks. Aerosol data showed that, of the mixed layers studied, the boreal forest has the largest increase in aerosol number density relative to the free troposphere. With the exception of the boreal forest, a significant portion of mixed layer aerosols are from the free troposphere. Results also show that while, in theory, free‐tropospheric air can be classified as originating from continental or maritime regions (Siberia, Canada, Pacific Ocean, Gulf of Alaska), little difference was found in the ozone and fine aerosol number density composition of the air. This is attributed, in part, to modification of the air during transport from its source region.
Modeling the land surface boundary in climate models as a composite of independent vegetation stands
Authors: Koster Randal D. , Suarez Max J.
Published: February 2012

An efficient strategy for modeling the land surface boundary in general circulation models (GCMs) is presented which accounts for the effects of vegetation on surface energy fluxes and allows for an arbitrary number of vegetation types to coexist in a grid square. The GCM grid square is depicted as a “mosaic” of vegetation “tiles,” with each tile consisting of a single vegetation type. The energy balance equation for each tile follows closely that of a single vegetation version of the simple biosphere (SiB) model of Sellers et al. (1986) but is simplified enough to be written in Penman‐Monteith form. Each tile in the square is coupled independently to the GCM atmosphere, and tiles affect each other only through the atmosphere. This coupling strategy differs conceptually from that of models such as SiB that assume a homogeneous mixture of vegetation types within a GCM grid square. A quantitative comparison of the two strategies is presented.
The impact of global warming on river runoff
Authors: Miller James R. , Russell Gary L.
Published: February 2012

River runoff from the world's major rivers is an important part of the hydrologic cycle. Runoff changes in response to global greenhouse‐induced warming will have impacts in many areas, including agriculture, water resources, and land use. A global atmospheric model is used to calculate the annual river runoff for 33 of the world's major rivers for the present climate and for a doubled CO2 climate. The model has a horizontal resolution of 4° × 5°, but the runoff from each model grid box is quartered and added to the appropriate river drainage basin on a 2° × 2.5° resolution. The computed runoff depends on the model's precipitation, evapotranspiration, and soil moisture storage. For the doubled CO2 climate, the runoff increased for 25 of the 33 rivers, and in most cases the increases coincided with increased rainfall within the drainage basins. There were runoff increases in all rivers in high northern latitudes, with a maximum increase of 47%. At low latitudes there were both increases and decreases ranging from a 96% increase to a 43% decrease. The effect of the simplified model assumptions of land‐atmosphere interactions on the results is discussed.
Sensitivity of groundwater recharge estimates to climate variability and change, Columbia Plateau, Washington
Authors: Vaccaro John J.
Published: February 2012

The sensitivity of groundwater recharge estimates was investigated for the semiarid Ellensburg basin, located on the Columbia Plateau, Washington, to historic and projected climatic regimes. Recharge was estimated for predevelopment and current (1980s) land use conditions using a daily energy‐soil‐water balance model. A synthetic daily weather generator was used to simulate lengthy sequences with parameters estimated from subsets of the historical record that were unusually wet and unusually dry. Comparison of recharge estimates corresponding to relatively wet and dry periods showed that recharge for predevelopment land use varies considerably within the range of climatic conditions observed in the 87‐year historical observation period. Recharge variations for present land use conditions were less sensitive to the same range of historical climatic conditions because of irrigation. The estimated recharge based on the 87‐year historical climatology was compared with adjustments to the historical precipitation and temperature records for the same record to reflect CO2‐doubling climates as projected by general circulation models (GCMs). Two GCM scenarios were considered: an average of conditions for three different GCMs with CO2 doubling, and a most severe “maximum” case. For the average GCM scenario, predevelopment recharge increased, and current recharge decreased. Also considered was the sensitivity of recharge to the variability of climate within the historical and adjusted historical records. Predevelopment and current recharge were less and more sensitive, respectively, to the climate variability for the average GCM scenario as compared to the variability within the historical record. For the maximum GCM scenario, recharge for both predevelopment and current land use decreased, and the sensitivity to the CO2‐related climate change was larger than sensitivity to the variability in the historical and adjusted historical climate records.