bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the Material Homogeneity of Components Made of Steel Grade 100Cr6 on Distortion
Authors: Prinz Christian , Clausen Brigitte , Hoffmann Franz
Published: February 2011

The influence of the material homogeneity of components made of steel SAE 52100 (100Cr6) on quench hardening distortion was investigated. The homogeneity was varied by electromagnetic stirring during casting, and by using spray formed semi‐finished material. The distortion was identified at forged cylindrical rings in a designed experiment. The material homogeneity shows no significant influence on the resulting size and shape changes after single part hardening of symmetric cylindrical parts. Additionally the distortion of eccentrically extracted rings was investigated to decrease strain and increase material inhomogeneity of the samples. Even these samples show no influence on distortion by non‐uniform distributions of the alloying elements. The independency of size and shape changes of the homogeneity of the local chemical composition might be a result of the uniform martensitic structure through the cross section of the investigated samples after quench hardening. So, distortion of other steel grades with lower hardenabilities or of components with other geometries might become influenced by the material homogeneity.
Human α‐amylase and starch digestion: An interesting marriage
Authors: Butterworth Peter J. , Warren Frederick J. , Ellis Peter R.
Published: February 2011

α‐Amylase catalyses the first step in the digestion of starch, a main source of carbohydrate in the human diet. Amylase present in human saliva was one of the first enzymes ever to be recognised but many puzzles remain about the molecular mechanisms involved in amylolysis of starch and even of the physiological role of the salivary amylase itself. Native starch granules represent a formidable challenge for attack from an enzyme in solution. Moreover the frequently reported differences in the susceptibility to amylolysis of starches from various botanical species, plus the changes that occur in starch structure and properties during domestic and commercial food processing means that studies of the enzymology of starch digestion can be challenging. We review the molecular properties of mammalian α‐amylase including its genetics, and speculate on the role of salivary amylase in digestion of dietary starch. Also considered are enzyme kinetic approaches that have been used in vitro studies of amylase digestion of starches. Such studies can result in better understanding of reasons for the differences in glycaemic responses of humans following ingestion of different starch containing foods.
Persistent Elevation of C‐Reactive Protein Following Esophagogastric Cancer Resection as a Predictor of Postoperative Surgical Site Infectious Complications
Authors: Dutta Sumanta , Fullarton Grant M. , Forshaw Matthew J. , Horgan Paul G. , McMillan Donald C.
Published: February 2011

Background

Infectious complications, particularly in the form of anastomotic leaks (ALs) or surgical site infections (SSIs), represent a serious morbidity after esophagogastric cancer resections. Therefore, early detection is of paramount importance. Although markers of the systemic inflammatory response, including C‐reactive protein (CRP) and white cell count (WCC), have been used in this regard, their relative predictive value is unclear. The aim of the present study was to examine serial postoperative WCC, albumin, and CRP and their diagnostic accuracy in case of infectious complications.

Patients and Methods

White cell count, albumin, and CRP were routinely measured postoperatively for 7 days in 136 consecutive patients who had undergone esophagogastric cancer resection. All postoperative complications were recorded. The diagnostic accuracy of the WCC, albumin, and CRP values were analyzed by receiver operating characteristics curve analysis with surgical site and remote infectious complications as outcome measures.

Results

Fifty‐four (40%) patients developed infectious complications, and 17 of them developed an AL. CRP was significantly higher from postoperative day (POD) 3 onward in those patients who developed an AL. On POD 3, a threshold reading of 180 mg/l was associated with development of an AL, providing a sensitivity of 82% and a specificity of 63%. On POD 4, the same CRP threshold of 180 mg/l provided 71% sensitivity and 83% specificity.

Conclusions

Postoperative CRP measurements on PODs 3 and 4 are clinically useful in predicting surgical site infectious complications, in particular an AL, after resection for esophagogastric cancer.
Temporal shifts and niche overlapping in Copestylum (Diptera, Syrphidae) communities reared in cactus species in a central Mexican scrubland
Authors: Martínez‐Falcón Ana Paola , Marcos‐García Ma. Ángeles , Moreno Claudia E.
Published: February 2011

Semiarid scrubland communities are highly dynamic in terms of their species composition, abundance, and functioning, given the drastic changes in climate among seasons. Spatiotemporal patterns of saprophagous Copestylum (Diptera: Syrphidae) communities in different cactus species richness have not yet been studied, although seasonal changes and plant species richness have been shown to strongly impact the diversity and distribution of many insect communities in scrublands. We analyzed the impact of seasonality and of habitat type (disturbed and undisturbed) on Copestylum communities reared from cactus species at the Barranca de Metztitlán Biosphere Reserve, in central Mexico, by comparing their community structure between seasons and habitats, and assessing the contribution of diversity components for the total diversity of this genus. We also measured patterns of temporal niche overlap among hoverfly species considering their breeding medium. Seasonal variation influenced Copestylum community composition most significantly. Species richness and abundance of Copestylum were higher in the rainy season. Additive partitioning of diversity showed that the main component for species richness is beta diversity between seasons. We detected high niche overlap during the dry season and low overlap during the rainy season. This study provides evidence of temporal shifts in xeric hoverfly communities and suggests that the Copestylum species partition resources over time.
Epicondylectomy versus Denervation for Lateral Humeral Epicondylitis
Authors: Berry Nada , Neumeister Michael W. , Russell Robert C. , Dellon A. Lee
Published: February 2011

Background

Traditional management of lateral humeral epicondylitis (“tennis elbow”) relies upon antiinflammatory medication, rehabilitation, steroid injection, counterforce splinting, and, finally, surgery to the common extensor origin. The diversity of surgical approaches for lateral humeral epicondylitis (LHE) suggests perhaps that the ideal technique has not been determined. Denervation of the lateral humeral epicondyle is the concept of interrupting the neural pathway that transmits the pain message. Epicondylectomy may accomplish its relief of LHE by denervating the epicondyle.

Methods

Since it is known that the posterior branch of the posterior cutaneous nerve of the forearm innervates the lateral humeral epicondyle, 30 patients who were treated surgically for refractory LHE were retrospectively evaluated. Group 1 consisted of 17 patients who were treated with epicondylectomy alone, group II consisted of seven patients who were treated with lateral epicondylectomy plus neurectomy, and group III consisted of seven patients treated with lateral denervation alone.

Results

Denervation alone gave statistically significantly greater improvement in pain relief ( p<0.001) and statistically significantly faster return to work than did epicondylectomy alone ( p<0.001). Denervation plus epicondylectomy gave results that were the same as denervation alone.

Conclusion

It is concluded that denervation gives significant relief from LHE once traditional non-surgical treatment has failed.
Non‐uptake of colposcopy in a resource‐poor setting
Authors: Chigbu Chibuike O. , Aniebue Uzo U.
Published: February 2011

Objective

To determine the rate of acceptance/refusal of colposcopy and the reasons for refusal by women referred for the procedure in southeast Nigeria.

Methods

An audit was performed of the computerized database for all women referred for colposcopy at the University of Nigeria Teaching Hospital, Enugu, from August 1, 2009, to July 31, 2010. The characteristics of those who accepted colposcopy were compared with those who refused the procedure. An interviewer‐administered questionnaire was used to assess reasons for refusal and the subsequent treatment chosen.

Results

During the study period, 154 women were referred for colposcopy: 103 (66.9%) accepted and 51 (33.1%) refused. Those who refused were younger and tended to be nulliparous (P = 0.029 and P = 0.004, respectively). The most common reasons for refusal were fears of possible diagnosis of cervical cancer and compromise of future fertility. Most women who refused resorted to spiritual healing.

Conclusion

The rate of refusal of colposcopy in southeast Nigeria was high, indicating an urgent need for appropriate remedial measures instituted through intensive education of women regarding cervical cancer and its prevention. Targeted counseling should be initiated early as part of prescreening counseling.
Genetic structure and diversity of a collection ofBrassica rapasubsp.rapaL. revealed by simple sequence repeat markers
Authors: SOENGAS P. , CARTEA M. E. , FRANCISCO M. , LEMA M. , VELASCO P.
Published: February 2011

Brassica rapasubsp.rapaL. includes three different crops: turnips (roots), turnip greens (leaves) and turnip tops (inflorescences). A collection ofB. rapasubsp.rapafrom north-western Spain is currently kept at ‘Misión Biológica de Galicia’ (a research centre of the Consejo Superior de Investigaciones Científicas (CSIC), Spain). This collection has been characterized based on morphological and agronomical traits. A better understanding of the genetic diversity present in the collection is necessary in order to optimize its use and maintenance. The objectives of the present work were to assess the genetic diversity present in theB. rapasubsp.rapacollection, to establish genetic relationships among populations and to study the genetic structure of the collection. Eighty populations were analysed based on 18 simple sequence repeats (SSRs). Populations showed a broad range of genetic diversity, thus offering good potential for further genetic improvement. Most of the variability was found within the population level, probably due to high rates of allogamy, to migration and/or interchange of seed among local growers. Populations showed a low level of differentiation, grouping in just one cluster, and therefore they can be considered as samples of a highly variable metapopulation that can be used forB. rapabreeding programmes.
Peristaltic pumping of rigid objects in an elastic tube
Authors: TAKAGI D. , BALMFORTH N. J.
Published: February 2011

A mathematical model is developed for long peristaltic waves propelling a suspended rigid object down a fluid-filled axisymmetric tube. The fluid flow is described using lubrication theory and the deformation of the tube using linear elasticity. The object is taken to be either an infinitely long rod of constant radius or a parabolic-shaped lozenge of finite length. The system is driven by a radial force imposed on the tube wall that translates at constant speed down the tube axis and with a form chosen to generate a periodic wave train or a solitary wave. These waves exert a traction on the enclosed object, forcing it into motion. Periodic waves drive the infinite rod at a speed that attains a maximum at a moderate forcing amplitude and approaches approximately one quarter of the wave speed in the large-amplitude limit. The finite lozenge can be entrained and driven at the same speed as a solitary wave or periodic wave train if the forcing is sufficiently strong. For weaker forcing, the lozenge is either left behind the solitary wave or interacts repeatedly with the waves in the periodic train to generate stuttering forward progress. The threshold forcing amplitude for entrainment increases weakly with the radial span of the enclosed object, but strongly with the axial length, with entrainment becoming impossible if the object is too long.
The differential effects of EPA and DHA on cardiovascular risk factors
Authors: Cottin S. C. , Sanders T. A. , Hall W. L.
Published: February 2011

Compelling evidence exists for the cardioprotective benefits resulting from consumption of fatty acids from fish oils, EPA (20:5n-3) and DHA (22:6n-3). EPA and DHA alter membrane fluidity, interact with transcription factors such as PPAR and sterol regulatory element binding protein, and are substrates for enzymes including cyclooxygenase, lipoxygenase and cytochrome P450. As a result, fish oils may improve cardiovascular health by altering lipid metabolism, inducing haemodynamic changes, decreasing arrhythmias, modulating platelet function, improving endothelial function and inhibiting inflammatory pathways. The independent effects of EPA and DHA are poorly understood. While both EPA and DHA decrease TAG levels, only DHA appears to increase HDL and LDL particle size. Evidence to date suggests that DHA is more efficient in decreasing blood pressure, heart rate and platelet aggregation compared to EPA. Fish oil consumption appears to improve arterial compliance and endothelial function; it is not yet clear as to whether differences exist between EPA and DHA in their vascular effects. In contrast, the beneficial effect of fish oils on inflammation and insulin sensitivity observedin vitroand in animal studies has not been confirmed in human subjects. Further investigation to clarify the relative effects of consuming EPA and DHA at a range of doses would enable elaboration of current understanding regarding cardioprotective effects of consuming oily fish and algal sources of long chainn-3 PUFA, and provide clearer evidence for the clinical therapeutic potential of consuming either EPA or DHA-rich oils.
Molecular and morphological circumscription ofMesocestoidestapeworms from red foxes (Vulpes vulpes) in central Europe
Authors: HRČKOVA GABRIELA , MITERPÁKOVÁ MARTINA , O'CONNOR ANNE , ŠNÁBEL VILIAM , OLSON PETER D.
Published: February 2011

Here we examine 3157 foxes from 6 districts of the Slovak Republic in order to determine for the first time the distribution, prevalence and identity ofMesocestodesspp. endemic to this part of central Europe. During the period 2001–2006, an average of 41·9% of foxes were found to harbourMesocestoidesinfections. Among the samples we confirmed the widespread and common occurrence ofM. litteratus(Batsch, 1786), and report the presence, for the first time, ofM. lineatus(Goeze, 1782) in the Slovak Republic, where it has a more restricted geographical range and low prevalence (7%). Using a combination of 12S rDNA, CO1 and ND1 mitochondrial gene sequences together with analysis of 13 morphometric characters, we show that the two species are genetically distinct and can be differentiated by discrete breaks in the ranges of the male and female reproductive characters, but not by the more commonly examined characters of the scolex and strobila. Estimates of interspecific divergence withinMesocestoidesranged from 9 to 18%, whereas intraspecific variation was less than 2%, and phylogenetic analyses of the data showed that despite overlapping geographical ranges, the two commonly reported European species are not closely related, withM. litteratusmore closely allied to North American isolates ofMesocestoidesthan toM. lineatus. We confirm that morphological analysis of reproductive organs can be used to reliably discriminate between these often sympatric species obtained from red foxes.
A new actinospore type Unicapsulactinomyxon (Myxozoa), infecting the marine polychaete,Diopatra neapolitana(Polychaeta: Onuphidae) in the Aveiro Estuary (Portugal)
Authors: RANGEL LUÍS F. , CECH GÁBOR , SZÉKELY CSABA , SANTOS MARIA J.
Published: February 2011

This work reports a new type of actinospore, Unicapsulactinomyxon, which exhibits a unique morphological characteristic in that it has a single and large polar capsule (9·3×4·1μm) (which possesses a longitudinally-folded polar filament) instead of the 3 polar capsules previously described for actinosporeans. The spore has a binucleated sporoplasm and 3 valves, each of which forms a long process. The spore has a total length of 241·3μm. This parasite develops in groups of 8 inside pansporocysts in the coelomic cavity of the polychaete host. Molecular investigations on the SSU rDNA show that the new actinospore type is most closely related toEnteromyxumspecies (81–84% similarity). A survey of actinospore infections of the marine polychaeteDiopatra neapolitanain 2007 and 2009, in the Aveiro Estuary (Portugal), showed an annual prevalence of 1·0% and 0·3%, respectively.
Exploring causal effects of combining work and intergenerational support on depressive symptoms among middle-aged women
Authors: OPREE SUZANNA J. , KALMIJN MATTHIJS
Published: February 2011

In debates about ageing western societies it is often assumed that many middle-aged women struggle to combine paid employment and intergenerational support, and that the subsequent stress leads them to experience an increase in depressive symptoms. Cross-sectional studies have supported this notion, but the question remains whether combining work and intergenerational support actuallycausesan increase in depressive symptoms. In order to fill a gap in the literature, this study examines the proportion of middle-aged women combining paid work and support to an adult child and/or parent, and the extent to which combining these roles affects women's depressive symptoms over time. For this purpose, we make use of the Survey of Health, Ageing, and Retirement in Europe (SHARE) data set which includes longitudinal data collected on European women aged 50+. Descriptive analyses indicated that 14 per cent of middle-aged women combine the roles of employee, support provider to an adult child, and/or support provider to a parent. Results from semi-dynamic and full-dynamic regression analyses indicate that combining roles can take away some, of the positive mental health effects of fulfilling a role. These findings support the role combination stress hypothesis.
Anticipated Parental Leave Take Up in Luxembourg
Authors: Valentova Marie
Published: February 2011

Luxembourg introduced a parental leave scheme in 1999 as a policy effort to stimulate equality between men and women with regard to bringing up children and to allow for reconciliation of family and professional life, so that the caring parents do not have to withdraw from the labour market after having a child. The analysis presented in this paper is one of the first systematic attempts to assess the parental leave take up of women in Luxembourg and to analyze it in light of micro-level characteristics of potential beneficiaries. The paper aims to explore the acceptance of parental leave provisions by the population of young women residing in Luxembourg and to examine which of their socio-demographic and labour market characteristics determine hypothetical parental leave take up. Attention is also paid to anticipated labour market strategies of women after parental leave.
Equality and Human Rights in Britain: Principles and Challenges
Authors: Riddell Sheila , Watson Nick
Published: February 2011

In the UK and many other European countries, there continue to be concerns about a range of social issues including the position of immigrants, the educational attainment of marginalised groups and the persistence of the gender pay gap. Increasingly, governments and NGOs assert that the promotion of equality and human rights policies are central to addressing these issues, with a view to creating societies which are both more equitable and more efficient. Over the past decade and a half, a period of economic growth followed recently by a major recession, the equality and human rights agenda enjoyed a high political profile. However, as we discuss in this review article, the social and economic optimism of the late nineties and early to mid noughties has been followed by economic retrenchment, a commitment to the shrinking of the state and the public sphere across Europe and a general move to the political right. In this article, we first review the political context which led to the rise of the equality and human rights agenda. Subsequently, we examine competing conceptualisations of equality and their operationalisation within British social policy. Finally, we assess the progress which has been made towards achieving a more equal society in the UK over recent years drawing on data gathered and analysed by the National Equality Panel (NEP, 2010).
The formation of relativistic cosmic jets
Authors: Meier David L.
Published: February 2011

I review current ideas on the launching, acceleration, collimation and propagation of relativistic jets and the influence of strong magnetic fields in the process. Recently, several important elements of the entire jet “engine” structure have been shown to play key roles in the production of an astrophysical jet. Depending on the type of system, these include the spin of the central black hole, the thermal and/or magnetic state of the accretion flow, the presence of a re-collimation point in the jet outflow far away from the central object, and the behavior of MHD shocks and kink instabilities in the final jet. While these physical processes probably are at work in all types of relativistic jets (and many even in more benign stellar outflows), I shall concentrate on ones produced by lower luminosity black hole sources, both in active galactic nuclei and in X-ray binaries. I also will discuss the connection between the theoretical concepts and the large body of observational data now available on these systems.
Relativistic jets at high energies
Authors: Levinson Amir
Published: February 2011

A recent progress in the study of γ-ray jets is reviewed, with a focus on some theoretical interpretations of the VHE emission from M87, and possibly other misaligned blazars; the connection between the GeV breaks exhibited by bright LAT blazars and opacity sources in the broad line region; the consequences of the detection of GeV emission from GRBs to models of magnetic outflows; and the implications of the thermal emission observed is some GRBs to dissipation of the outflow bulk energy.
The optimal locations for shock acceleration in MHD jets
Authors: Polko Peter , Meier David L. , Markoff Sera
Published: February 2011

Jets can contribute to the spectra of X-ray binaries (XRBs) and active galactic nuclei (AGN) from the radio through the γ-ray bands; thus understanding their physics is key for interpreting the data. Recent VLBI observations suggest that jets begin to accelerate particles into power-law distributions at a point offset from the black hole by ~104rg, possibly via a collimation shock. Spectral fitting of simultaneous, broadband data from both XRBs and AGN in jet-dominated states corroborates this picture. From a magnetohydrodynamical (MHD) point of view, it is natural to associate the onset of particle acceleration with the final MHD critical point in the flow, the modified fast point (MFP), where causal contact with the upstream flow is broken. In this way a standing disruption like a shock can form, and this location might vary with the physical parameters of the jet. In order to study this issue, we have used the self-similar formalism of Vlahakis & Königl (2003, hereafter VK03) to simplify the MHD equations and to derive solutions that cross the critical points. We have found a new parameter space of solutions that cross the MFP at a finite height above the disc and are relativistic, spanning a range of Lorentz factors Γ ≤ 10 (Polko et al. 2010). We present these results, as well as preliminary work connecting the relativistic formalism to the non-relativistic conditions with gravity near the base of the jets.
On the reprocessing of gamma-rays produced by jets
Authors: Orellana M. , Pellizza L. J. , Romero G. E.
Published: February 2011

Systems of two very different sizescales are known to produce very high-energy (VHE) radiation in their jets: AGNs and microquasars. The produced VHE photons (Eγ ~ 1 TeV) can be absorbed by the intense environmental soft photon fields, coming from the companion star (in high mass binaries) or from the accreting material (disk+corona in AGNs), as these are the dominant sources at energies around ~(mec2)2/Eγ. Energetic pairs are created by the photon-photon annihilation, and, depending on how efficient are the competing cooling channels, the absorption can lead to a reprocessing by Inverse Compton pair-cascade development. A self-consistent modeling of these systems as gamma-ray sources should then include, along with the emission and absorption processes, a thorough treatment of the pair cascades. We discuss here on this issue, focusing on our (preliminary) results of numerical simulations devoted to a study case similar to the high-mass microquasar candidate LS 5039.
Numerical theory of accretion flow and jet launching: A study on the galactic center
Authors: Dibi Salomé , Drappeau Samia , Markoff Sera , Fragile Chris
Published: February 2011

We obtained the first spectral predictions from a simulation of the Galactic Center to include radiative processes internally. We performed simulations with and without cooling, with and without spin, and for different initial configurations of the magnetic field, in order to test the effect on jet launching and inner accretion disk characteristics. By exploring parameter space, we will attempt to place new constraints on the controversial question about the presence or not of a jet from Sgr A*, as well as study jet launching in general. We have shown that, as expected, the spin of the BH affects the structure of the jet. The presence of cooling also strongly influences the inner structure of the accretion disk and therefore affects jet launching. These results show that radiative cooling is not negligible, as is usually assumed for the very underluminous supermassive BH, Sgr A*. On the contrary, the inclusion of cooling has a very visible influence on the accretion disk. Furthermore it creates an important difference in the resulting spectra.
Long-term simulations of extragalactic jets: cavities and feedback
Authors: Perucho Manel , Quilis Vicent , Martí José María
Published: February 2011

We present long-term numerical simulations of powerful extragalactic relativistic jets in two dimensions. The jets are injected in a realistic atmosphere with powers 1044, 1045 and 1046 erg/s, during tens of Myrs. After this time, the jet injection is switched off. We follow the evolution of the jets and associated shocks from 1 kpc to hundreds of kiloparsecs during more than 100 Myrs. The 1045 erg/s jet was simulated with leptonic and baryonic composition. Our results show that, for powerful jets, the main heating mechanisms are the driving shock-wave and mixing. We discuss the implications that these results have in the frame of cooling flows in clusters.
The far-infrared view of M87 as seen by the Herschel Space Observatory
Authors: Baes M. , Clemens M. , Xilouris E. M. , Fritz J. , Cotton W. D. , Davies J. I. , Bendo G. J. , Bianchi S. , Cortese L. , De Looze I. , Pohlen M. , Verstappen J. , Böhringer H. , Bomans D. J. , Boselli A. , Corbelli E. , Dariush A. , di Serego Alighieri S. , Fadda D. , Garcia-Appadoo D. A. , Gavazzi G. , Giovanardi C. , Grossi M. , Hughes T. M. , Hunt L. K. , Jones A. P. , Madden S. , Pierini D. , Sabatini S. , Smith M. W. L. , Vlahakis C. , Zibetti S.
Published: February 2011

The origin of the far-infrared emission from the nearby radio galaxy M87 remains a matter of debate. Some studies find evidence of a far-infrared excess due to thermal dust emission, whereas others propose that the far-infrared emission can be explained by synchrotron emission without the need for an additional dust emission component. We observed M87 with PACS and SPIRE as part of the Herschel Virgo Cluster Survey (HeViCS). We compare the new Herschel data with a synchrotron model based on infrared, submm and radio data to investigate the origin of the far-infrared emission. We find that both the integrated SED and the Herschel surface brightness maps are adequately explained by synchrotron emission. At odds with previous claims, we find no evidence of a diffuse dust component in M87.
An additional broad line region in 3C 390.3 associated with the jet
Authors: Nazarova L. S. , Bochkarev N. G.
Published: February 2011

We suggest the existence of two BLRs in 3C 390.3 which have different locations. The BLR1 is located at a distance in accordance to the hydrogen line time lags of ≈20 days. This disk-like region emits predominantly low ionization lines. The BLR2 forms around the radio-jet and is located at the distance corresponding to time lags of ≈ 40-80 days. The BLR2 is responsible for most of the emission in UV lines. The Lα line partly forms in BLR2 (40-60%) and partly in BLR1.
Evidence for shock-shock interaction in the jet of CTA 102
Authors: Fromm C. M. , Perucho M. , Savolainen T. , Ros E. , Lobanov A. P. , Zensus J. A. , Lähteenmäki A.
Published: February 2011

We have found evidence for interaction between a standing and a traveling shock in the jet of the blazar CTA 102. Our result is based in the study of the spectral evolution of the turnover frequency-turnover flux density (νm, Sm) plane. The radio/mm light curves were taken during a major radio outburst in April 2006.
Evolution of the parsec-scale jet in 3C 345
Authors: Schinzel F. K. , Lobanov A. P. , Zensus J. A. , Taylor G. B. , Jorstad S. , Marscher A.
Published: February 2011

The 16m quasar 3C 345 is one of the best examples of an AGN showing structural and flux variability on parsec scales around a compact unresolved radio core. It has been observed from radio to γ-ray wavebands with a special focus on Very Long Baseline Interferometry (VLBI) observations in the range 1-100 GHz that cover a period of over 30 years. The complex pc-scale jet of 3C 345 exemplifies an archetypal “superluminal” jet with helical substructure. Existing VLBI observations of 3C 345 form an unprecedented database enabling a unique insight into the long-term evolution of the pc-scale radio emission. Here we present the latest results from our ongoing long-term VLBI monitoring of 3C 345, focusing on the morphological, kinematic, and spectral evolution of the pc-scale jet. Special attention will be given to the recent onset of a new period of high activity in the source that has been manifesting itself since 2008 from radio through γ-rays. Recent VLBI and high energy observations to study the relation between the radio emission and the production of high energy photons in 3C 345 are combined.
Suzaku studies of microquasars
Authors: Ueda Yoshihiro , Shidatsu Megumi
Published: February 2011

We report our recent results from multiwavelengths studies of microquasars, focusing on X-ray data of GX 339–4 and GRS 1915+105 obtained with Suzaku and other observatories. The broad band coverage and high energy resolution achieved with Suzaku (or a combination of Chandra/HETGS and RXTE) enable us to perform the most reliable spectral analysis both on iron-K features and continuum, and thus to best constrain the accretion disk structure of microquasars and its relation to the jet formation at various mass accretion rates.
Accretion-outflow connection in the outliers of the “universal” radio/X-ray correlation
Authors: Coriat M. , Corbel S. , Prat L. , Miller-Jones J. C. A. , Cseh D. , Tzioumis A. K. , Brocksopp C. , Rodriguez J. , Fender R. P. , Sivakoff G. R.
Published: February 2011

In recent years, numerous efforts have been devoted to unravel the connection between accretion flow and jets in accreting compact objects. Here we report new constraints on these issues, through the long term study of the radio and X-ray behaviour of the black hole candidate H 1743–322. This source is known to be one of the “outliers” of the universal radio/X-ray correlation, i.e. a group of stellar mass accreting black holes displaying fainter radio emission for a given X-ray luminosity, than expected from the correlation. In this work we find, at high X-ray luminosity in the hard state, a tight radio/X-ray correlation with an unusual steep slope of b = 1.38 ± 0.03. This correlation then breaks below ~5 × 10−3LEdd (M/10M⊙)−1 in X-rays and becomes shallower. When compared with radio/X-ray data from other black hole X-ray binaries, we see that the deviant points of H 1743–322 join the universal correlation and seem to follow it at low luminosity. Based on these results, we investigate several hypotheses that could explain both the b ~ 1.4 slope and the transition toward the universal correlation.
The pertinence of jet emitting discs in microquasars. Theory and comparison to observations
Authors: Petrucci Pierre-Olivier , Ferreira Jonathan , Henri Gilles , Malzac Julien , Foellmi Cedric
Published: February 2011

Jet Emitting Disc (JED) has dynamical properties quite different from both the standard and advection dominated discs. It also exhibits three different thermal equilibrium branches at a given radius: two stable (cold and hot) and one intermediate unstable. The hot solution has all the characteristics of the so-called “hot corona” generally invoked in XrB sytems in the Low/Hard states. We detail the energetics and radiative expectations of our model and show their good agreement with those observed in Cygnus X-1 in terms of jet power, jet velocity and spectral emission.
Conditions for jet formation in accreting neutron stars: the magnetic field decay
Authors: García Federico , Aguilera Deborah N. , Romero Gustavo E.
Published: February 2011

Accreting neutron stars can produce jets only if they are weakly magnetized (B ~ 108 G). On the other hand, neutron stars are compact objects born with strong surface magnetic fields (B ~ 1012 G). In this work we study the conditions for jet formation in a binary system formed by a neutron star and a massive donor star once the magnetic field has decayed due to accretion. We solve the induction equation for the magnetic field diffusion in a realistic neutron star crust and discuss the possibility of jet launching in systems like the recently detected Supergiant Fast X-ray Transients.
A leptonic/hadronic jet model for the low-mass microquasar XTE J1118+480
Authors: Vila Gabriela S. , Romero Gustavo E.
Published: February 2011

We present a one–zone jet model that fits the data from simultaneous broadband radio-to-X-rays observations of XTE J1118+480. We calculate the radiative contribution to the non-thermal spectrum of both relativistic electrons and protons, as well as that from secondary muons, charged pions and electron-positron pairs produced at high-energy hadronic interactions. The distributions in energy of all the particle species are obtained taking into account the energy losses, injection, decay and escape from the emission region. We also include absorption effects on the emission spectrum due to photon-photon annihilation. Finally, we discuss the detectability of XTE J1118+480 at high energies with the present instruments according to the predictions of our model for the gamma-ray band.
Spectral evolution of the galactic microquasars XTE J1550-564 and GRO J1655-40 during outbursts
Authors: Lutovinov Alexander A. , Tsygankov Sergei S. , Arefiev Vadim A. , Revnivtsev Mikhail G.
Published: February 2011

We present results of a broadband spectroscopy of the galactic microquasars and black hole candidates XTE J1550-564 and GRO J1655-40, performed with the INTEGRAL and RXTE observatories during strong outbursts in 2003 and 2005, respectively. The spectral parameters evolution was traced during brightening and fading phases of each outburst to search a possible hysteresis and transitions from state to state. We estimated a size and optical depth of different regions around XTE J1550-564, like a hot plasma zone and optically thick accretion disk. Upper limits to the annihilation 511 keV line emission were obtained for both sources using data of the SPI spectrometer onboard the INTEGRAL observatory.
Evidence of an irradiated accretion disc in XTE J1818–245
Authors: Heras J. A. Zurita , Chaty S. , Bel M. Cadolle , Prat L.
Published: February 2011

The X-ray transient source XTE J1818–245 went through an outburst in 2005 that was observed during a multi-wavelength campaign from radio to soft γ-rays. We performed new optical observations with the ESO/NTT telescope at La Silla. The broad-band spectral energy distribution revealed that the outer parts of the accretion disc had to be irradiated by its inner parts to explain the optical emission.
Large-scale radio nebula around the Ultra-Luminous X-ray Source IC 342 X-1
Authors: Cseh Dávid , Lang Cornelia , Corbel Stéphane , Kaaret Philip , Grisé Fabien
Published: February 2011

We present discovery of a radio nebula associated with the ultraluminous X-ray source (ULX) IC 342 X-1 using the Very Large Array (VLA). Taking the surrounding nebula as a calorimeter, one can constrain the intrinsic power of the ULX source. We compare the obtained power that is needed to supply the radio nebula with the W50 nebula powered by the microquasar SS433 and with other ULXs. We find that the power required is at least two orders of magnitude greater than that needed to power radio emission from the W50 nebula associated with the microquasar SS433. In addition, we report the detection of a compact radio core at the location of the X-ray source.
Gamma Ray Bursts: basic facts and ideas
Authors: Ghisellini Gabriele
Published: February 2011

The recent years witnessed a dramatic improvement in our knowledge of the phenomenology and physics of Gamma Ray Bursts (GRBs). However, our “pillars of knowledge” remain a few, while many aspects remain obscure and not understood. There is no general agreement on the radiation mechanism of the prompt emission, nor on the process able to convert the bulk motion of the fireball into random energy of the emitting leptons. The afterglow phase can now be studied at very early phases, showing an unforeseen phenomenology, still to be understood. In this context, the detection of ~GeV emission from ~10% of GRBs, made possible by the Fermi satellite, can hopefully shed light on some controversial issues.
Gamma Ray Bursts Spectral–Energy correlations: recent results
Authors: Ghirlanda Giancarlo
Published: February 2011

The correlations between the rest frame peak of the νFν spectrum of GRBs (Epeak) and their isotropic energy (Eiso) or luminosity (Liso) could have several implications for the understanding of the GRB prompt emission. These correlations are presently founded on the time–averaged spectral properties of a sample of 95 bursts, with measured redshifts, collected by different instruments in the last 13 years (pre–Fermi). One still open issue is wether these correlations have a physical origin or are due to instrumental selection effects. By studying 10 long and 14 short GRBs detected by Fermi we find that a strong time–resolved correlation between Epeak and the luminosity Liso is present within individual GRBs and that it is consistent with the time–integrated correlation. This result is a direct proof of the existence in both short and long GRBs of a similar physical link between the hardness and the luminosity which is not due to instrumental selection effects. The origin of the Epeak – Liso correlation should be searched in the radiation mechanism of the prompt emission.
Molecular and atomic jets in young low-mass stars: Properties and origin
Authors: Cabrit Sylvie , Ferreira J. , Dougados C.
Published: February 2011

The key characteristics of molecular and atomic ejection from young stars are summarized, with emphasis on similarities across evolutionary stages, and the need for efficient magnetic collimation and ejection extracting a large fraction of the accretion power. The jet kinematics, and its dust and molecular content, are confronted to steady MHD jet models, and the probable contribution of non-steady processes is pointed out.
On the time variability of the HH jet ejection process
Authors: De Colle Fabio
Published: February 2011

Two-dimensional emission line images of the HH30 jet were recently used (De Colle et al. 2010) to recover the three-dimensional structure of the jet by applying standard tomographic technique (“Tikhonov regularization techniques”). In this paper I show that it is possible to determine the ejection history of the HH30 jet by directly comparing the outcome of numerical simulations with the results of the tomographic inversion. In particular, it is shown that the HH30 jet electron density map is best reproduced by assuming a velocity variation at the base of the jet with a large scale periodicity (with a period of ~3 yrs) added to small scales velocity variation (with periods ≲months).
Modelling of T Tauri jets with low mass accretion rate
Authors: Globus N. , Sauty C. , Cayatte V. , Meliani Z. , Lima J. J. G. , Tsinganos K. , Michaut C.
Published: February 2011

We show that low mass accreting T Tauri stars may have a strong stellar jet component which can effectively brake the star to the observed rotation speed. By means of meridional self similarity, we construct semi analytical solutions describing the complete dynamics and topology of the stellar component of the jet emerging from the corona of the star. We show two typical solutions with the same mass loss rate but different magnetic lever arms and jet radius, corresponding to differente phases of T Tauri star activity.
Geospace Environment Modeling 2008–2009 Challenge: Ground magnetic field perturbations
Authors: Pulkkinen A. , Kuznetsova M. , Ridley A. , Raeder J. , Vapirev A. , Weimer D. , Weigel R. S. , Wiltberger M. , Millward G. , Rastätter L. , Hesse M. , Singer H. J. , Chulaki A.
Published: February 2011

Acquiring quantitative metrics‐based knowledge about the performance of various space physics modeling approaches is central for the space weather community. Quantification of the performance helps the users of the modeling products to better understand the capabilities of the models and to choose the approach that best suits their specific needs. Further, metrics‐based analyses are important for addressing the differences between various modeling approaches and for measuring and guiding the progress in the field. In this paper, the metrics‐based results of the ground magnetic field perturbation part of the Geospace Environment Modeling 2008–2009 Challenge are reported. Predictions made by 14 different models, including an ensemble model, are compared to geomagnetic observatory recordings from 12 different northern hemispheric locations. Five different metrics are used to quantify the model performances for four storm events. It is shown that the ranking of the models is strongly dependent on the type of metric used to evaluate the model performance. None of the models rank near or at the top systematically for all used metrics. Consequently, one cannot pick the absolute “winner”: the choice for the best model depends on the characteristics of the signal one is interested in. Model performances vary also from event to event. This is particularly clear for root‐mean‐square difference and utility metric‐based analyses. Further, analyses indicate that for some of the models, increasing the global magnetohydrodynamic model spatial resolution and the inclusion of the ring current dynamics improve the models' capability to generate more realistic ground magnetic field fluctuations.
Reproducibility and quantitation of amplicon sequencing-based detection
Authors: Zhou Jizhong , Wu Liyou , Deng Ye , Zhi Xiaoyang , Jiang Yi-Huei , Tu Qichao , Xie Jianping , Van Nostrand Joy D , He Zhili , Yang Yunfeng
Published: February 2011

To determine the reproducibility and quantitation of the amplicon sequencing-based detection approach for analyzing microbial community structure, a total of 24 microbial communities from a long-term global change experimental site were examined. Genomic DNA obtained from each community was used to amplify 16S rRNA genes with two or three barcode tags as technical replicates in the presence of a small quantity (0.1% wt/wt) of genomic DNA from Shewanella oneidensis MR-1 as the control. The technical reproducibility of the amplicon sequencing-based detection approach is quite low, with an average operational taxonomic unit (OTU) overlap of 17.2%±2.3% between two technical replicates, and 8.2%±2.3% among three technical replicates, which is most likely due to problems associated with random sampling processes. Such variations in technical replicates could have substantial effects on estimating β-diversity but less on α-diversity. A high variation was also observed in the control across different samples (for example, 66.7-fold for the forward primer), suggesting that the amplicon sequencing-based detection approach could not be quantitative. In addition, various strategies were examined to improve the comparability of amplicon sequencing data, such as increasing biological replicates, and removing singleton sequences and less-representative OTUs across biological replicates. Finally, as expected, various statistical analyses with preprocessed experimental data revealed clear differences in the composition and structure of microbial communities between warming and non-warming, or between clipping and non-clipping. Taken together, these results suggest that amplicon sequencing-based detection is useful in analyzing microbial community structure even though it is not reproducible and quantitative. However, great caution should be taken in experimental design and data interpretation when the amplicon sequencing-based detection approach is used for quantitative analysis of the β-diversity of microbial communities.
Benzotriazole containing conjugated polymers for multipurpose organic electronic applications
Authors: Balan Abidin , Baran Derya , Toppare Levent
Published: February 2011

Benzotriazole (BTz) containing polymers are reviewed from a general perspective in terms of their potential use in organic electronic applications namely electrochromics (ECs), organic solar cells (OSCs) and organic light emitting diodes (OLEDs) in comparison with the structurally similar polymers.
Degradable polymers from ring-opening polymerization of α-angelica lactone, a five-membered unsaturated lactone
Authors: Chen Tieniu , Qin Zhangfeng , Qi Yongqin , Deng Tiansheng , Ge Xiaojing , Wang Jianguo , Hou Xianglin
Published: February 2011

A degradable polymer was prepared from α-angelica lactone, a five-membered unsaturated lactone, by ring-opening polymerization.
Three-beam interference lithography methodology
Authors: Stay J. L. , Burrow G. M. , Gaylord T. K.
Published: February 2011

Three-beam interference lithography represents a technology capable of producing two-dimensional periodic structures for applications such as micro- and nanoelectronics, photonic crystal devices, metamaterial devices, biomedical structures, and subwavelength optical elements. In the present work, a systematic methodology for implementing optimized three-beam interference lithography is presented. To demonstrate this methodology, specific design and alignment parameters, along with the range of experimentally feasible lattice constants, are quantified for both hexagonal and square periodic lattice patterns. Using this information, example photonic crystal rodlike structures and holelike structures are fabricated by appropriately controlling the recording wavevector configuration along with the individual beam amplitudes and polarizations, and by changing between positive- or negative-type photoresists.