bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic Monte Carlo approach for triangular‐shaped Pt islands on Pt(111) surfaces
Authors: Deák Robert , Néda Zoltán
Published: May 2012

Formation of triangular‐shaped Pt adatom islands on a Pt(111) surface is investigated using a kinetic Monte Carlo approach. The energy barriers are calculated with the generalized embedded atom method and the nudged elastic band approach. The numerical results reveal that the preferential orientation of the triangles cannot be explained solely by the differences in the diffusion coefficients of the atoms along the topologically non‐equivalent edges of the islands. For a self‐consistent explanation of the triangle orientations, one has to examine the topological and energetic details of the diffusion paths for all the edge diffusion processes, kink‐formation or kink‐breaking events, and corner to edge jumps.
Metabonomic Study of Genkwa Flos–induced Hepatotoxicity and Effect of Herb‐Processing Procedure on Toxicity
Authors: Geng Lulu , Ma Chao , Zhang Li , Yang Guoguang , Cui Yan , Su Dan , Zhao Xu , Liu Zhenzhen , Bi Kaishun , Chen Xiaohui
Published: May 2012

A urinary metabonomic approach based on ultraperformance liquid chromatography coupled with mass spectrometry (UPLC‐MS) was developed to study the metabolic disturbances caused by the administration of Genkwa Flos (GF) to rats. Potential biomarkers of GF‐induced toxic effects were screened out and identified, and the underlying toxicological mechanism as well as the detoxification of vinegar‐processing procedure on this herb was discussed. Urine samples were analyzed by the established UPLC‐MS method. With the help of serum biochemistry and histopathology results, metabolic disturbances induced by the exposure to GF and the detoxification of processing procedure were confirmed. The differences in the metabolic profiles of healthy and treated rats were clearly discriminated with the principal component analysis of the chromatographic data. Eight significantly changed metabolites were identified and interpreted as biomarkers for the hepatotoxicity and detoxification of processing procedure. This study indicated that a UPLC‐MS‐based metabonomic analysis of urine samples could be considered as a promising tool to predict the hepatotoxicity induced by the GF and the detoxification of traditional vinegar‐processing procedure on this herb. Copyright © 2012 John Wiley & Sons, Ltd.
Screening of Venezuelan Medicinal Plant Extracts for Cytostatic and Cytotoxic Activity Against Tumor Cell Lines
Authors: Taylor Peter , Arsenak Miriam , Abad María Jesús , Fernández Ángel , Milano Balentina , Gonto Reina , Ruiz Marie‐Christine , Fraile Silvia , Taylor Sofía , Estrada Omar , Michelangeli Fabian
Published: May 2012

There are estimated to be more than 20,000 species of plants in Venezuela, of which more than 1500 are used for medicinal purposes by indigenous and local communities. Only a relatively small proportion of these have been evaluated in terms of their potential as antitumor agents. In this study, we screened 308 extracts from 102 species for cytostatic and cytotoxic activity against a panel of six tumor cell lines using a 24‐h sulphorhodamine B assay. Extracts from Clavija lancifolia, Hamelia patens, Piper san‐vicentense, Physalis cordata, Jacaranda copaia, Heliotropium indicum, and Annona squamosa were the most cytotoxic, whereas other extracts from Calotropis gigantea, Hyptis dilatata, Chromolaena odorata, Siparuna guianensis, Jacaranda obtusifolia, Tapirira guianensis, Xylopia aromatica, Protium heptaphyllum, and Piper arboreum showed the greatest cytostatic activity. These results confirm previous reports on the cytotoxic activities of the abovementioned plants as well as prompting further studies on others such as C. lancifolia and H. dilatata that have not been so extensively studied. Copyright © 2012 John Wiley & Sons, Ltd.
Characterization of 31 nonperiodic layers of alternate SiO2/Nb2O5 on glass for optical filters by SIMS, XRR, and ellipsometry
Authors: Schiffmann Kirsten I. , Vergöhl Michael
Published: May 2012

In case of periodic multilayers, such as for optical filters, X‐ray reflectivity (XRR) is mostly used for precise determination of the thickness and density of the layers. However, nonperiodic multilayer systems of more than four to five layers generally cannot be solved by XRR because of the numerous fitting parameters. For a 31‐layer system, 96 fitting parameters (which will not converge to a unique solution) have to be matched. Here, secondary ion mass spectroscopy (SIMS) may help by giving reliable start values for the thicknesses. To achieve this, optimum depth resolution and a correction of the different sputter rates of the alternating materials is necessary. Iterative optimization of XRR fit and SIMS layer thicknesses finally yield good correspondence, with a mean deviation of 1.8 nm or 3%. Spectroscopic variable angle ellipsometry has been taken as a third method for the characterization of the layer stack but has yielded slightly larger deviations. Copyright © 2012 John Wiley & Sons, Ltd.
Phosphosulindac (OXT-328) Selectively Targets Breast Cancer Stem Cells In Vitro and in Human Breast Cancer Xenografts
Authors: Zhu Caihua , Cheng Ka-Wing , Ouyang Nengtai , Huang Liqun , Sun Yu , Constantinides Panayiotis , Rigas Basil
Published: May 2012

Pharmacological targeting of breast cancer stem cells (CSCs) is highly promising for the treatment of breast cancer, as the small population of CSCs appears responsible for tumor initiation and progression and also for resistance to conventional treatment. Here we report that the novel phosphosulindac (OXT-328, PS) selectively and effectively eliminates breast CSCs both in vitro and in vivo. PS reduced cell proliferation and induced apoptosis in various breast CSCs. Breast CSCs are resistant to conventional cancer drugs but are sensitive to PS. Long-term treatment of mixtures of cultured breast CSCs and breast cancer cells with PS preferentially eliminated the CSCs. PS impaired the ability of CSCs to form mammospheres and markedly suppressed the expression of CSC-related genes. More importantly, PS prevented by half (p =.06) the formation of tumors initiated by CSCs in immunodeficient mice, and inhibited by 83% (p <.05) the growth of already formed breast cancer xenografts, reducing the proportion of CSCs in them. PS suppressed the Wnt/β-catenin pathway by stimulating the degradation of β-catenin and its relocalization to the cell membrane and also blocked the epithelial–mesenchymal transition and the generation of breast CSCs. These results indicate that PS has a strong inhibitory effect against breast cancer, acting, at least in part, by targeting CSCs through a signaling mechanism involving Wnt signaling.
Phosphane Ligands with Enaminoketone Scaffold and their Palladium Complexes
Authors: Schmidt Michael , Heck Jürgen
Published: May 2012

The reaction of (Z)‐4‐aminopent‐3‐en‐2‐one with different chlorodiorganylphosphanes established three new ligands composed of a hard and soft coordination site. The soft phosphane site is easily coordinated to palladium(II) as a first step in the potential formation of heterodinuclear complexes. Surprisingly, the formed square‐planar dichloridopalladium(II) complexes exhibit exclusively trans configuration. A cis configurated palladium(II) complex can be formed, when the linker between the phosphane and the enaminoketone unit is enlarged and allows more flexibility. The reaction between (Z)‐4‐(2′‐hydroxyethylamino)pent‐3‐en‐2‐one and chlorodiorganylphosphanes revealed two new ligands that coordinate to palladium(II). With phenyl substituents at the phosphorus atom a cis palladium complex was obtained, whereas for isopropyl substituents a trans complex was formed. Molecular structures of all complexes were analyzed by single‐crystal X‐ray diffraction.
Reaktionen von Bis(trimethylsilyl)aminochlorsilanen mit Lithium – N, Si‐Trimethylsilylgruppenwanderung oder Selbstkondensation von Bis(trimethylsilyl)aminosilyllithiumverbindungen
Authors: Popowski Eckhard , Rietz Ildiko , Fischer Christian , Erben Siegfried , Harloff Jörg , Reinke Helmut
Published: May 2012

The chlorosilanes [(Me3Si)2N]HMeSiCl (1), [(Me3Si)2N]2MeSiCl (2) and [(Me3Si)2N]RPhSiCl (3: R = Me, 4: R = Ph, 5: R = (Me3Si)2N, 6: R = H) were allowed to react with lithium metal in tetrahydrofuran (THF) or in a mixture of THF/Et2O/n‐pentane in the volume ratio 4:1:1 (Trapp mixture). 1 and 2 did not react with lithium in THF at room temperature. A mixture of 1 and Me3SiCl in molar ratio 1:1 reacted with lithium to give [(Me3Si)2N]HMeSi–SiMeH[N(SiMe3)2] (7) and [(Me3Si)2N]HMeSi–SiMe3 (8). The analogous reaction of 2, Me3SiCl and lithium afforded [(Me3Si)2N]2MeSi–SiMe3 (10) only. [(Me3Si)2N]MePhSiLi (11) and [(Me3Si)2N]Ph2SiLi (16) prepared by reaction of 3 and 4 with lithium in THF underwent a partial rearrangement to form the lithium amides [(Li)(Me3Si)N]MePhSi–SiMe3 (12) and [(Li)(Me3Si)N]Ph2Si–SiMe3 (17), respectively, when the temperature raised from –78 °C to room temperature. In the reaction of 5 with lithium in THF at –78 °C, the amide [(Li)(Me3Si)N][(Me3Si)2N]PhSi–SiMe3 (21) was formed. [(Me3Si)2N]2PhSiLi (20) was obtained by reaction of 5 with lithium in the Trapp mixture at –110 °C. The silyllithiums 11, 16, 20 and the lithium amides 12, 17, 21 were trapped with HMe2SiCl resulting in the following products: [(Me3Si)2N]MePhSi–SiMe2H (13), [(Me3Si)2N]Ph2Si–SiMe2H (18), [(Me3Si)2N]2PhSi–SiMe2H (24), [(HMe2Si)(Me3Si)N]MePhSi–SiMe3 (14), [(HMe2Si)(Me3Si)N]Ph2Si–SiMe3 (19), and [(HMe2Si)(Me3Si)N][(Me3Si)2N]PhSi–SiMe3 (22). The silyllithiums 11, 16, and 20 were formed directly by reaction of the corresponding aminochlorosilanes with lithium at –78 °C (11 and 16) and at –110 °C (20), respectively. In the reaction of the aminochlorosilane 6 with lithium in THF at –78 °C a mixture of [(Me3Si)2N]HPhSiLi (25) and [(Me3Si)2N]HPhSi–SiHPhLi (26) was obtained. Compounds 25 and 26 were trapped with HMe2SiCl to give [(Me3Si)2N]HPhSi–SiMe2H (27) and [(Me3Si)2N]HPhSi–SiHPh–SiMe2H (28). The molecular structures of 19, 22 and 24 were determined.
Copper Bismuth Chalcogenide Halogenides with Extensively Disordered and Mobile Copper(I) Cations
Authors: Heerwig Andreas , Müller Ulrike , Nitsche Fabian , Ruck Michael
Published: May 2012

A new family of quaternary phases with the general sum formula Cu3+δBi5–δSe8–2δX2+2δ (X = Cl, Br) was discovered by slow cooling of high temperature melts. Cu3.58(1)Bi4.42(1)Se6.84(2)Cl3.16(2) (δ = 0.58) and Cu4.52(1)Bi3.48(1)Se4.96(2)Br5.04(2) (δ = 1.52) crystallize isostructural in the orthorhombic space group type Pnnm with a = 1332.3(1)/1340.2(3) pm, b = 1683.7(2)/1717.2(1) pm, and c = 406.2(1)/407.1(2) pm. The new structure type resembles in some aspects the hollandite as well as the pavonite type. A framework of face‐ and edge‐sharing anion polyhedra around Bi3+ cations hosts Cu+ cations. The characteristic motif is an infinite band of polyhedra that has the width of five polyhedra, with three octahedra being enclosed by capped trigonal prisms. The octahedrally coordinated Bi3+ cations are partially substituted by Cu+ (in octahedra faces), while Se2– anions are replaced by X–. The sulfide iodide Cu3.33(2)Bi2S3.33(2)I2.67(2) crystallizes in the monoclinic space group C2/m with a = 2803.6(9) pm, b = 409.9(1) pm, c = 1058.0(3) pm, and β = 110.68(2)°. Double strands of face‐sharing [BiS1/1S2/2I4/4] as well as [BiS3/3I2/2(S0.33/I0.67)2/2] polyhedra run along [010]. In between them, the Cu+ cations are spread over numerous closely spaced sites. They define a ladder‐shaped continuous path for ion conduction along [010].
Mutational analysis reveals a dual role of Mdm2 acidic domain in the regulation of p53 stability
Authors: Dolezelova Pavlina , Cetkovska Katerina , Vousden Karen H. , Uldrijan Stjepan
Published: May 2012

MDM2
physically interacts with
S6a
by anti bait coimmunoprecipitation (View interaction)
SHORT VEGETATIVE PHASE (SVP) protein negatively regulates miR172 transcription via direct binding to the pri‐miR172a promoter in Arabidopsis
Authors: Cho Hyun Jung , Kim Jae Joon , Lee Jeong Hwan , Kim Wanhui , Jung Jae-Hoon , Park Chung-Mo , Ahn Ji Hoon
Published: May 2012

Plant microRNAs (miRNAs) are non‐coding RNAs that negatively regulate expression of their target genes. Although much is known about miRNA biogenesis and repression of target genes by miRNAs, the molecular mechanisms underlying the transcriptional regulation of miRNA itself are poorly understood. Here, we report that SHORT VEGETATIVE PHASE (SVP) protein is a direct transcriptional regulator of miR172. The levels of mature miR172 and pri‐miR172a were anti‐correlated with SVP activity. miR172a has multiple transcription start sites, among which the transcript starting with cytosine (−671 bp, relative to the mature miR172a) was a major species. EMSA and ChIP analysis demonstrated that SVP protein binds to the CArG motifs in the miR172a promoter. These results suggest that SVP protein directly regulates miR172 transcription in Arabidopsis.
Significant energy transfer from CpcG2‐phycobilisomes to photosystem I in the cyanobacterium Synechococcus sp. PCC 7002 in the absence of ApcD‐dependent state transitions
Authors: Deng Guoping , Liu Fei , Liu Xianwei , Zhao Jindong
Published: May 2012

Hemidiscoidal phycobilisomes (PBS), the major light harvesting complexes of photosynthesis in most cyanobacteria, are composed of rods and cores, which are linked by the linker CpcG1 (LRC). Another type of PBS, CpcG2‐PBS exits and their function in energy transfer has not been fully understood. We measured growth rates, absorption cross‐sections and quantum efficiency of photosystem I in mutant strains of Synechococcus PCC sp. 7002 lacking the linker CpcG2. Our results showed that energy transfer from CpcG2‐PBS to PSI in the absence of state transitions could be significant under PBS‐absorbing light and energy transfer from two types of PBS is independent to each other. Evidence also suggested that CpcG2 anchors the CpcG2‐PBS to thylakoid membranes.
Genetically encoded RNA photoswitches as tools for the control of gene expression
Authors: Jäschke Andres
Published: May 2012

An important goal in chemical and synthetic biology is controlling the expression of defined sets of genes by external stimuli, and one of the most attractive stimuli is light. Current approaches to the photocontrol of biological processes utilize photoresponsive proteins. In this article, I will illustrate the prospects of synthetic systems in which the receptor is a photoresponsive nucleic acid, and will review the different tools already in place to develop photoresponsive systems based on RNA. A particular focus is on genetically encoded photoswitches that can be expressed in prokaryotic or eukaryotic cells, and respond to photoisomerizable, cell‐permeable small molecules.
Nerds and Barbarians: Race and Class Encounters through Affirmative Action in a Brazilian University
Authors: CICALO ANDRÉ
Published: May 2012

This ethnographic article discusses how race emerges between discourses of class and space at the University of the State of Rio de Janeiro. Following a legal decision, this academic institution was required to implement racial quotas to combat social exclusion and raise the number of ‘black’ students in public higher education. A crucial question is whether such racially based policies help redress social inequalities, or whether they actually increase discrimination by reifying ‘racial’ differences in Brazil. I argue that the social diversity promoted by quotas at the university stresses certain urban tensions and unequal dynamics that come to be reflected within the university. However, it also reveals novel and positive paths by which policies can negotiate these contrasts.
‘Fifty Years in Five’ and What's in It for Us? Development Promotion, Populism, Industrial Workers andCarestiain 1950s Brazil
Authors: IORIS RAFAEL R.
Published: May 2012

In the mid-twentieth century, the Brazilian federal government embarked upon an ambitious plan of fast-paced industrialisation aimed at responding to the growing needs of the country's ever more urbanised population. While the plan achieved rapid economic growth, rising levels of discontent defined much of the political behaviour of urban labour in the period. By critically examining some of the main events affecting industrial unions during the so-called ‘developmental decade’ of the 1950s, this article argues that amidst pervasive top-down economic transformations Brazilian workers consistently advanced an alternative position on national development. By investigating how metalworkers in São Paulo and Rio de Janeiro understood and responded to the main developmental trends and difficulties of the period, the paper reveals some of the creative strategies articulated by urban workers to promote a more socially inclusive path for the country. By becoming actively involved in ever more assertive cross-professional mobilisations, particularly those aimed at curbing the rising cost of living (a problem known ascarestia), industrial workers not only protected their own economic interests but also significantly challenged the very bases of the populist political arrangements that defined post-war Brazilian society.
Athletics, army recruitment and heroisation: L. Sep. Fl. Flavillianus of Oinoanda
Authors: Milner N.P.
Published: May 2012

This article presents an inscribed statue base discovered at Oinoanda by Professor Martin Ferguson Smith in 2002. The new inscription is placed in its historical context, and the commentary traces the implications for our understanding of Roman army recruitment, the role of the civic élite in responding to the demands of the imperial government and the practice of heroisation in the competition for honour among the notables who were also the city's victorious athletes.
Seasonal variation in the incidence rate of tuberculous meningitis is associated with sunshine hours
Authors: VISSER D. H. , SCHOEMAN J. F. , VAN FURTH A. M.
Published: May 2012

Tuberculous meningitis (TBM) is a severe complication of tuberculosis and occurs mainly during early childhood. The incidence rate of TBM varies with season, and serum vitamin D levels, which are dependent on sunlight, might play a role. We studied the association between TBM incidence rate and hours of sunshine in Cape Town, South Africa and found a significant association between the incidence rate of TBM and hours of sunshine 3 months earlier (incidence rate ratio per 100 sunshine hours 0·69, 95% confidence interval 0·54–0·88, P = 0·002). The association supports the hypothesis that vitamin D might play a role in the pathophysiology of TBM. Further prospective studies in which vitamin D status is measured are necessary to determine causality.
Analysis of coronary flow haemodynamics in homozygous familial hypercholesterolaemic adolescents with aortic supravalvular stenosis
Authors: Wang Zheng , Yang Ya , LI Zhi'an , Zhang Xiaoshan , Lin Jie , Wang Lvya
Published: May 2012

Objective

To study coronary artery haemodynamics in adolescents with homozygous familial hypercholesterolaemia and aortic supravalvular stenosis.

Methods

Patients diagnosed with familial hypercholesterolaemia who were younger than 16 years and who had undergone transthoracic echocardiography from 2007 to 2010 were included in this study. We included patients with homozygous familial hypercholesterolaemia and aortic supravalvular stenosis and those with heterozygous familial hypercholesterolaemia. All patients underwent stress echocardiography, and left anterior descending coronary artery flow was successfully detected. Coronary flow velocity reserve was calculated as the ratio of hyperaemic mean diastolic flow velocity after injection of adenosine to basal mean diastolic flow velocity. Changes in coronary haemodynamics and the relationship between lipid concentrations were determined.

Results

A total of 11 patients with homozygous familial hypercholesterolaemia were enrolled in this study. Lipid concentrations were measured, and the mean coronary flow velocity reserve was 1.97 plus or minus 0.51. Seven children were included in the group of patients with heterozygous familial hypercholesterolaemia. In these children, the mean coronary flow velocity reserve was 3.08 plus or minus 0.84.

Conclusion

The coronary flow velocity reserve of homozygous familial hypercholesterolaemic patients is lower than that of heterozygous familial hypercholesterolaemic patients, and it is associated with a high concentration of low-density lipoprotein cholesterol. Aortic stenosis and plaques compromised the ostia of the coronary artery and caused increased basal mean diastolic coronary velocity with blunted increase in peak velocity, which decreased the coronary flow velocity reserve.
The Kālacakra Tantra on the Sādhana and Maṇḍala: A Review Article
Authors: REIGLE DAVID
Published: May 2012

The Kālacakra Tantra was the last Buddhist tantra to appear in India, before the disappearance of Buddhism there, roughly a thousand years ago. This is the third book on Kālacakra by Vesna Wallace. We must be very grateful to her for another helpful contribution to our knowledge of this complex system. Her first one, The Inner Kālacakratantra: A Buddhist Tantric View of the Individual (New York, 2001), provides an overview of the whole system, drawing on all five chapters of the Kālacakra Tantra. Her next one, The Kālacakratantra: The Chapter on the Individual together with the Vimalaprabhā (New York, 2004), presents a translation of the second chapter of the Kālacakra Tantra along with the indispensable Vimalaprabhā commentary thereon. The Kālacakra Tantra is written entirely in the sragdharā metre, in which the length of every syllable is regulated. When a complex system is presented in a complex metre, we have a text that is hard to understand in the extreme. It would be almost incomprehensible without the full and detailed Vimalaprabhā commentary.
Validation and extension of a simple questionnaire to assess physical activity in pre-school children
Authors: Bayer Otmar , Jarczok Marc , Fischer Joachim , von Kries Rüdiger , De Bock Freia
Published: May 2012

Objective

To (i) validate a recently proposed questionnaire tool for the simple assessment of physical activity (PA) in pre-school children by comparison with accelerometry and heart-rate recordings; and (ii) extend the tool by adding more questions to improve validity and to refine the classification from two to three categories (PA low, medium, high).

Setting

Baseline data of an intervention evaluation study.

Subjects

Pre-school children.

Design

Children were categorized as either physically active or non-active, based on their parents’ answers to the five-item questionnaire. Activity and heart rate were recorded for 6 d (Actiheart device; CamNtech, Cambridge, UK). Nightly sleeping periods were removed and mean accelerometry counts (MACT), time spent in moderate-to-vigorous intensity physical activity (MVPA) and time spent in sedentary behaviour (SB) were computed. In a second step, additional questions that improved validity were added, resulting in an extended seven-item questionnaire.

Results

For 748 (90·4 %) of the participating children aged 2·3–6·7 years, the questionnaires were filled out sufficiently for classification. Children classified as physically active showed 9·6 % higher MACT (P< 0·0003), spent more time in MVPA and insignificantly less time in SB. Using the extended questionnaire, children with PA classified as medium (reference: low) showed 11·0 % more MACT, spent 11·8 % more time in MVPA and 4·8 % less time in SB. Children with PA classified as high showed 16·9 % more MACT, spent 20·2 % more time in MVPA and 7·2 % less time in SB.

Conclusions

With validated PA questionnaires for pre-school children lacking, the proposed questionnaire might be a reasonable option to include for PA assessment in epidemiological studies where more elaborate measurements are unavailable.
Optimal BMI cut-off values for predicting diabetes, hypertension and hypercholesterolaemia in a multi-ethnic population
Authors: Cheong Kee Chee , Yusoff Ahmad F , Ghazali Sumarni M , Lim Kuang H , Selvarajah Sharmini , Haniff Jamaiyah , Khor Geok L , Shahar Suzana , Rahman Jamalludin Abd , Zainuddin Ahmad A , Mustafa Amal N
Published: May 2012

Objective

To determine the optimal cut-offs of BMI for Malaysian adults.

Design

Population-based, cross-sectional study. Receiver operating characteristic curves were used to determine the cut-off values of BMI with optimum sensitivity and specificity for the detection of three cardiovascular risk factors: diabetes mellitus, hypertension and hypercholesterolaemia. Gender-specific logistic regression analyses were used to examine the association between BMI and these cardiovascular risk factors.

Setting

All fourteen states in Malaysia.

Subjects

Malaysian adults aged ≥18 years (n32 703) who participated in the Third National Health and Morbidity Survey in 2006.

Results

The optimal BMI cut-off value for predicting the presence of diabetes mellitus, hypertension, hypercholesterolaemia or at least one of these cardiovascular risk factors varied from 23·3 to 24·1 kg/m2for men and from 24·0 to 25·4 kg/m2for women. In men and women, the odds ratio for having diabetes mellitus, hypertension, hypercholesterolaemia or at least one cardiovascular risk factor increased significantly as BMI cut-off point increased.

Conclusions

Our findings indicate that BMI cut-offs of 23·0 kg/m2in men and 24·0 kg/m2in women are appropriate for classification of overweight. We suggest that these cut-offs can be used by health professionals to identify individuals for cardiovascular risk screening and weight management programmes.
Rocky exoplanet characterization and atmospheres
Authors: Kaltenegger L. , Miguel Y. , Rugheimer S.
Published: May 2012

A decade of exoplanet search has led to surprising discoveries, from giant planets close to their star, to planets orbiting two stars, all the way to the first extremely hot, rocky worlds with potentially permanent lava on their surfaces due to the star's proximity. Observation techniques have reached the sensitivity to explore the chemical composition of the atmospheres as well as physical structure of some detected gas planets and detect planets of less than 10 Earth masses (MEarth), the so-called super-Earths, among them some that may potentially be habitable. Three confirmed non-transiting planets, and several transiting Kepler planetary candidates, orbit in the habitable zone (HZ) of their host star. The detection and characterization of rocky and potentially Earth-like planets is approaching rapidly with future ground and space missions that can explore the planetary environments by analysing their atmosphere remotely. This paper discusses how to characterize a rocky exoplanet remotely.
Photoelectron flows in the polar wind during geomagnetically quiet periods
Authors: Kitamura N. , Seki K. , Nishimura Y. , Terada N. , Ono T. , Hori T. , Strangeway R. J.
Published: May 2012

Characteristics of photoelectron flows and presence of a field‐aligned potential drop on the open magnetic field lines in the polar cap are systematically investigated using the data obtained by the FAST satellite during geomagnetically quiet periods in July 2002. We found high occurrence frequencies of the potential drop larger than ∼10 V, reaching ∼90% (small field‐aligned current (FAC) case) and ∼83% (all data). A typical magnitude of the potential drop above ∼3800 km altitude is ∼20 V. This value is significantly larger than the potential drop below ∼3800 km altitude (probably ∼1–3 V), although the typical potential drop is smaller by a factor of ∼2–3 in comparison to the modeling results that suggested presence of a field‐aligned potential jump at several earth radii. The net escaping electron number flux negatively correlates with the upward electron number flux and with the magnitude of the potential drop. This relation is contrary to expectation from photoelectron‐driven polar wind models that an increase in the photoelectrons drives the larger polar wind flux, since the net escaping electron number flux balances the flux of polar wind ions under zero net FAC conditions. An increase in the upward backscatter of reflected electrons with an increasing potential drop may explain the negative correlations. A potential drop at high altitudes would provide a polar wind system regulated by a negative feedback, and the most appropriate balance for polar wind ions would be achieved near the median of the reflection potential.
ITRF2008 plate motion model
Authors: Altamimi Z. , Métivier L. , Collilieux X.
Published: May 2012

The ITRF2008 velocity field is demonstrated to be of higher quality and more precise than past ITRF solutions. We estimated an absolute tectonic plate motion model made up of 14 major plates, using velocities of 206 sites of high geodetic quality (far from plate boundaries, deformation zones and Glacial Isostatic Adjustment (GIA) regions), derived from and consistent with ITRF2008. The precision of the estimated model is evaluated to be at the level of 0.3 mm/a WRMS. No GIA corrections were applied to site velocities prior to estimating plate rotation poles, as our selected sites are outside the Fennoscandia regions where the GIA models we tested are performing reasonably well, and far from GIA areas where the models would degrade the fit (Antarctica and North America). Our selected velocity field has small origin rate bias components following the three axis (X, Y, Z), respectively 0.41 ± 0.54, 0.22 ± 0.64 and 0.41 ± 0.60 (95 per cent confidence limits). Comparing our model to NNR‐NUVEL‐1A and the newly available NNR‐MORVEL56, we found better agreement with NNR‐MORVEL56 than with NNR‐NUVEL‐1A for all plates, except for Australia where we observe an average residual rotation rate of 4 mm/a. Using our selection of sites, we found large global X‐rotation rates between the two models (0.016°/Ma) and between our model and NNR‐MORVEL56 of 0.023°/Ma, equivalent to 2.5 mm/a at the Earth surface.
Absolute calibration of a wideband antenna and spectrometer for accurate sky noise temperature measurements
Authors: Rogers Alan E. E. , Bowman Judd D.
Published: May 2012

A new method of absolute calibration of sky noise temperature using a three‐position switched spectrometer, measurements of antenna and low noise amplifier impedance with a vector network analyzer, and ancillary measurements of the amplifier noise waves is described and compared with other methods of calibration. An initial test of the method has been made using brief observations from 55 to 110 MHz at West Forks, Maine, to estimate the sky noise spectral index. Estimates are made of the accuracy that might ultimately be achieved with observations to detect or set limits on the red‐shifted 21 cm line at a radio quiet site. It is concluded that an antenna reflection coefficient better than about −20 dB is required to avoid being limited by the accuracy of the antenna reflection coefficient measurements using a vector network analyzer.
Provenance and time constraints on the formation of the first bend of the Yangtze River
Authors: Kong Ping , Zheng Yong , Caffee Marc W.
Published: May 2012

The upper Yangtze River flows southward on the southeastern Tibet characterizing by uniquely low and continuous relief. The river makes a sharp turn at Shigu, heading northeast, and forms the first bend of the Yangtze River. Many previous studies assumed southward flow of the ancestral Yangtze River from Shigu to the South China Sea. However, field evidence of southward flow of the paleo‐Yangtze is lacking. In this paper we report our identification, based on detrital zircon U‐Pb age distributions, of a range of fluvial sands left by the paleo‐Yangtze in Tongdian, Madeng and Nanjian basins. Cosmogenic10Be and 26Al burial dating provides burial ages for these fluvial sands from 1.7 to over 8.7 Ma. Rerouting of the Yangtze River therefore occurred within the last 1.7 Ma, postdating the major uplift of the central Tibet. We attribute the rerouting of the Yangtze River to response to activation of the Dali fault system, and in a larger scale, initiation of crustal deformation by clockwise rotation around eastern Himalayan syntaxis 2–4 Ma ago. Reorganization of the Yangtze drainage pattern most likely reflects regional uplift and displacement due to lower crust flowing beneath major faults in the southeastern Tibet and Yunnan.
Two years of oceanic observations below the Fimbul Ice Shelf, Antarctica
Authors: Hattermann Tore , Nøst Ole Anders , Lilly Jonathan M. , Smedsrud Lars H.
Published: May 2012

The mechanisms by which heat is delivered to Antarctic ice shelves are a major source of uncertainty when assessing the response of the Antarctic ice sheet to climate change. Direct observations of the ice shelf‐ocean interaction are extremely scarce and in many regions melt rates from ice shelf‐ocean models are not constrained by measurements. Our two years of data (2010 and 2011) from three oceanic moorings below the Fimbul Ice Shelf in the Eastern Weddell Sea show cold cavity waters, with average temperatures of less than 0.1°C above the surface freezing point. This suggests low basal melt rates, consistent with remote sensing‐based, steady‐state mass balance estimates for this sector of the Antarctic coast. Oceanic heat for basal melting is found to be supplied by two sources of warm water entering below the ice: (i) eddy‐like bursts of Modified Warm Deep Water that access the cavity at depth for eight months of the record; and (ii) fresh surface water that flushes parts of the ice base with temperatures above freezing during late summer and fall. This interplay of processes implies that basal melting at the Fimbul Ice Shelf cannot simply be parameterized by coastal deep ocean temperatures, but instead appears directly linked to both solar forcing at the surface as well as to the dynamics of the coastal current system.
A simplified model for frictionally dominated tidal flows
Authors: Van Oyen T. , Lanzoni S. , D'Alpaos A. , Temmerman S. , Troch P. , Carniello L.
Published: May 2012

The response of vegetated tidal wetlands to environmental changes is governed by vegetation‐flow‐landscape feedbacks occurring over large spatial and temporal scales, and thus typically studied using simplified models. Here, we present a new simplified approach to describe frictionally dominated tidal flows, characteristic of tidal wetlands. The derivation of the model follows from an expansion of the momentum and mass conservation equations in terms of small dimensionless parameters, which arise once the relevant variables are suitably scaled. A comparison with a full‐fledged finite element model indicates that the proposed simplified approach ensures a reliable description of the flow field; suggesting that the model provides a key advancement to study the bio‐morphodynamic feedbacks which shape intertidal landscapes.
Signature of the coronal hole near the north crest equatorial anomaly over Egypt during the strong geomagnetic storm 5 April 2010
Authors: Shimeis A. , Fathy I. , Amory‐Mazaudier C. , Fleury R. , Mahrous A. M. , Yumoto K. , Groves K.
Published: May 2012

In this paper we study the ionospheric–magnetic disturbance during a strong magnetic storm on 5 April 2010 associated to a coronal hole. The Earth was under the influence of a high speed solar wind stream during four days, and IMF was southward during a very long period. The variation of the disturbed magnetic observations and GPS‐TEC are compared with the variation of quiet days during the same month in order to obtain the characteristics of GPS‐TEC and magnetic disturbances due to the coronal hole effect. We use multi‐instruments as SCINDA‐GPS station at Helwan, Egypt (29.86°N, 31.32°E) and ASW‐MAGDAS station at Aswan, Egypt (23.59°N, 32.51°E) in the equatorial region. At the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field which strongly increases the TEC. During the recovery phase of the storm, we observe on TEC and magnetic data, the signature of the ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. It is the first time that we observe an anti‐Sq circulation on magnetic data during four consecutive days associated to the high speed solar wind streams.
Atmospheric semidiurnal lunar tide climatology simulated by the Whole Atmosphere Community Climate Model
Authors: Pedatella N. M. , Liu H.‐L. , Richmond A. D.
Published: May 2012

The atmospheric semidiurnal lunar tide is added to the Whole Atmosphere Community Climate Model (WACCM) through inclusion of an additional forcing mechanism. The simulated climatology of the semidiurnal lunar tide in surface pressure and zonal and meridional winds in the mesosphere and lower thermosphere (MLT) is presented. Prior observations and modeling results demonstrate characteristic seasonal and latitudinal variability of the semidiurnal lunar tide in surface pressure, and the WACCM reproduces these features. In the MLT, the WACCM simulations reveal a primarily semiannual variation with maxima near December and June solstice. The peak amplitudes in the MLT zonal and meridional winds are ∼5–10 ms−1, and occur at mid to high latitudes in the summer hemisphere. We have further compared the WACCM simulation results in the MLT with those from the Global Scale Wave Model (GSWM). The overall latitude and seasonal variations are consistent between these two models. However, the GSWM peak amplitudes are ∼2–3 times larger than those in the WACCM. This is thought to be related to deficiencies in the GSWM and not the WACCM simulations. With the exception of smaller amplitudes during Northern Hemisphere summer months, the WACCM simulations of the semidiurnal lunar tide in the MLT are also shown to be generally consistent with prior observations and modeling results. The reduced amplitudes in the WACCM simulations during Northern Hemisphere summer months are thought to be related to the influence of the cold‐pole bias in WACCM on the propagation of the lunar tide during these months.
Mesoscale variability in the northeastern tropical Pacific: Forcing mechanisms and eddy properties
Authors: Liang Jun‐Hong , McWilliams James C. , Kurian Jaison , Colas François , Wang Peng , Uchiyama Yusuke
Published: May 2012

The generation mechanisms and properties of the mesoscale eddies in the northeastern tropical Pacific (NETP) are studied using a series of numerical solutions and satellite observations. The spatial and temporal resolution of mountain wind jets over the Gulfs of Tehuantepec and Papagayo are essential for an accurate modeling of the regional mesoscale variability. Three previously proposed eddy generation mechanisms are the local transient wind forcing, the combined low‐frequency wind and boundary forcing, and the remote equatorial Kelvin wave forcing. In our model, the transient wind‐forcing was represented by wind fields with synoptic variability, and the remote equatorial Kelvin wave forcing by 5‐day open boundary conditions with interannual variability. Solutions with and without high‐frequency forcings are contrasted to evaluate the contributions of the three mechanisms. The combined low‐frequency wind and boundary forcing is the primary eddy forcing mechanism in the NETP. In the Tehuantepec region, the high‐frequency wind‐forcing contributes more to the mesoscale variability than the remote equatorial Kelvin wave forcing, while in the Papagayo region, their contributions are comparable. Eddies in the Tehuantepec and Papagayo regions are larger in both amplitude and size, and are more likely to deflect equatorward than eddies in the rest of the NETP. The maximum temperature anomaly of eddies is at around 50 m depth. Eddies with lifetimes >6 weeks are more likely anticyclonic, while eddies with lifetimes <6 weeks are more likely cyclonic. The anticyclone‐dominance for large‐amplitude long‐lived eddies is the combined consequence of wind‐driven asymmetric dipole spin‐up and the evolutionary fragility of large‐amplitude cyclones.
Overview. Type I interferons as primers, activators and inhibitors of innate and adaptive immune responses
Authors: Hertzog Paul J
Published: May 2012

The innate immune response recognises pathogens and sterile danger signals to generate effector cytokines, such as type I interferons (IFNs), with a high degree of sophistication. The May/June 2012 issue provides a series of reviews of the role of type I IFNs in regulating immune responses. Topics to be covered include the reason for the induction of IFNs, type I IFNs interactions with and regulation of target cells (e.g. T cells, B cells and Th10 cells) in the immune system, and the roles and mechanisms of IFNs in specific organs or diseases. The accompanying web focus presents links to related articles from across Nature Publishing Group to provide more background information about these proteins.
Two‐Dimensional Strain and Twist by Vector Velocity Imaging in Adolescents With Severe Obesity
Authors: Obert Philippe , Gueugnon Carine , Nottin Stéphane , Vinet Agnes , Gayrard Sandrine , Rupp Thomas , Dumoulin Gilles , Tordi Nicolas , Mougin Fabienne
Published: May 2012

The prevalence of severe obesity is increasing worldwide in adolescents. Whether it is associated with functional myocardial abnormalities remains largely unknown, potentially because of its frequent association with other cardiovascular risk factors and also use of insensitive techniques to detect subclinical changes in myocardial function. We used 2D vector velocity imaging (VVI) to investigate early changes in left ventricular (LV) myocardial function in youths with isolated severe obesity. Thirty‐seven asymptomatic severely obese adolescents free of diabetes and hypertension, and 24 lean controls were enrolled. LV longitudinal, basal, and apical circumferential strain, strain rate (SR), rotations, and LV twist were measured. Obese adolescents had greater LV mass and reduced systolic and early diastolic tissue Doppler imaging (TDI) velocities than lean counterparts. L strain (−24%) and systolic and early diastolic SR were also diminished in the obese, whereas no intergroup differences existed for the circumferential deformation indexes. LV twist was more pronounced in the obese (+1.7°, P < 0.01) on account of greater apical rotation only (4.1 ± 0.9 vs. 5.2 ± 1.2°, P < 0.01), potentially compensating for the loss in longitudinal function. Systolic—diastolic coupling, an important component of early filling and diastolic function, was maintained with severe obesity. No intergroup differences were reported regarding time to peak values for all VVI indexes highlighting that dynamics of strain and twist/untwist along the cardiac cycle was preserved with severe obesity. Isolated severe obesity in adolescents, at a preclinical stage, is associated with changes in myocardial deformation and torsional mechanics that could be in part related to alterations in relaxation and contractility properties of subendocardial fibers.
Reproduktionsmedizin. A. R. T. und Krebs
Authors: Westhof Gregor
Published: May 2012

Zwei Fragen lassen sich unter dem Titel „Assistierte Reproduktionstechnologie (ART) und Krebs“ diskutieren:
Child Abuse and Neglect: Screening for Risks During the Perinatal Period
Authors: Besier T. , Pillhofer M. , Botzenhart S. , Ziegenhain U. , Kindler H. , Spangler G. , Bovenschen I. , Gabler S. , Künster A.
Published: May 2012

Purpose: Currently, there is a claim for earlier interventions for families in order to prevent child maltreatment. Here, a screening instrument to assess risk indicators for child abuse and neglect already in the context of maternity clinics is introduced. The present study is the first report on the psychometric properties of this instrument, the “short questionnaire for risk indices around birth” (RIAB). Material and Methods: Data were collected in the context of three different studies conducted at Ulm University Hospital. To examine interrater reliability eight case vignettes were rated by n = 90 study participants (50 students and 40 experts working at a maternity clinic). Criterion validity was examined in two studies applying the German version of the child abuse potential inventory CAPI (n = 96 families at risk and n = 160 additional families). Results: Both laymen and experts were able to understand and use the screening instrument
correctly, leading to a high agreement with the sample solutions given. A high concordance was found between parentsʼ and expertsʼ ratings: In case of no reported risk factors applying the screening instrument RIAB, parents themselves reported significantly less stressors and burdens, compared to those parents with an indication for a thorough examination as pointed out in the RIAB. Conclusion: In the context of maternity clinics the RIAB is a useful, broadly applicable instrument, screening for existing risk factors at the earliest and thus allowing for the initiation of specific interventions when needed.
Onkologie. ETC-Regime: Hilfe für Hochrisikopatientinnen mit Mammakarzinom
Authors: Möbus Volker
Published: May 2012

Uneingeschränkt zu Recht wird die Berücksichtigung der biologischen Eigenschaften des Tumors für die Festlegung der adjuvanten Therapie gefordert, die im Idealfall zielgerichtet sein sollte und eine Übertherapie vermeidet. Unabhängig von dieser berechtigten Forderung gilt aber auch im Jahre 2012 unverändert die Aussage, dass die Anzahl der tumorös befallenen Lymphknoten den härtesten Prognosefaktor darstellt. Bei 1–3 tumorös befallenen Lymphknoten ist die Indikation zu einer Chemotherapie nicht zwingend obligat. Sie wird in Abhängigkeit vom Genprofil bzw. dem immunhistologischen Profil des Tumors (z. B. Luminal A vs. Luminal B, basal-like, normal breast like, HER2-positiv) gestellt. Dagegen besteht Konsens, dass Patientinnen mit 4 und mehr tumorös befallenen Lymphknoten eine moderne adjuvante Chemotherapie benötigen. Neben den anerkannten Anthrazyklin-/Taxan-haltigen Schemata der 3. Generation müssen in dieser Hochrisikokonstellation vor dem Hintergrund der Datenlage dosisdichte Regime bevorzugt eingesetzt werden.
Rare Benign Entities of the Breast – Myoid Hamartoma and Capillary Hemangioma
Authors: Schäfer F. , Biernath-Wuepping J. , Eckmann-Scholz C. , Order B. , Mathiak M. , Hilpert F. , Strauss A. , Jonat W. , Schäfer P.
Published: May 2012

Hamartomas can occur in different areas of the breast, but they are rarely found in the breast. Myoid hamartomas with smooth muscle cells of the type described here are particularly unusual. The pathogenesis of this benign entity with its tendency to growth and recurrence is not clear. Excision is the therapy of choice. Capillary hemangiomas are rare vascular malformations of the breast which, in contrast to cavernous hemangiomas, usually remain clinically occult. It is important to differentiate these benign findings from malignant angiosarcoma. The possible heterogeneities between myoid hamartoma and capillary hemangioma using current breast imaging methods for the differential diagnosis (high-resolution ultrasound, duplex sonography, shear wave elastography, digital mammography, minimally invasive intervention) are discussed together with an overview of the literature.
Effect of resonance electron-phonon interactions on the electronic spectra of tungsten and gallium
Authors: Burma N. G. , Avramenko Yu. A. , Petrishin A. I. , Fil V. D.
Published: May 2012

Features of the angular dependences of the Fermi velocity of charge carriers in tungsten and gallium associated with resonance electron-phonon interactions are studied. These features show up as a substantial reduction, by at least a factor of 1.5, in the velocity in the direction of the normals to the flattened parts of the Fermi surfaces of these metals and as a much smaller, on the order of 5%, reduction in the velocity on a cylindrical Fermi surface.