bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Modeling of Fluid Flow in Bath during Combined Side and Top Blowing AOD Refining Process of Stainless Steel: Application of the Model and Results
Authors: Wei Ji‐He , He Yuan , Shi Guo‐Min
Published: February 2011

The mathematical model developed for the molten steel flow in the combined side and top blowing AOD refining process of stainless steel has been used to compute and analyze the flow fields of the liquid phases in the baths of the 120 t AOD converter and its water model unit with a 1/4 linear scale. The influence of the side tuyere number and the angle between each tuyere on the flows has been examined. The results demonstrate that the mathematical model can quite reliably and well model and predict the fluid flow in an AOD bath with the combined blowing. The liquid flow in an AOD converter bath with the combined blowing is resulted from the gas side blowing streams under the influence of a gas top blowing jet. The streams play a governing role on it; and the liquid in the whole bath is in active agitation and circulatory motion during the gas blowing process. The gas jet from the top lance does not change the essential features of the gas stirring and liquid flow in the bath, but can make the local flow pattern of the bath liquid obviously vary and its turbulent kinetic energy enhance. The changes in the tuyere position and number have similarly not altered the basic characteristics and patterns of the gas agitation and liquid flow and turbulent kinetic energy distribution in the bath. At a given tuyere number and gas side blowing rate or a given angular separation between each tuyere and gas side blowing rate, however, the variation of the angle between each tuyere or the tuyere number can locally change them. Using 6 tuyeres with 27° can reach the more uniform flow field and turbulent energy distribution of the liquid in the bath than taking 7 tuyeres with 18° or 22.5° and 6 tuyeres with 22.5°.
Synthesis, Structure Determination, and Magnetic Properties of the New Heterometallic Chain Compound CrCrNi(di‐2,2′‐pyridylamido)4Cl2·Et2O
Authors: Aydin‐Cantürk Dilahan , Nuss Hanne
Published: February 2011

The new heterometallic chain compound CrCrNi(dpa)4Cl2·Et2O (dpa = di‐2,2′‐pyridylamido and Et = ethyl) was synthesized by the reaction of Cr2(dpa)4 and NiCl2 in dry tetrahydrofurane. Recrystallization from CH2Cl2/ethyl ether yielded dark red, block‐shaped crystals suitable for X‐ray structure determination (P21/c(no. 14), a = 159.29(1), b = 157.35(1), c = 169.76(1) pm, β = 98.228(2)°, V = 4211.0(6) pm3, Z = 4). The crystal structure of the title compound exhibits an orientational disorder of the CrCrNi chains, which has been elucidated by applying a well‐defined split model. The Cr–Cr distance of 203.7(2) pm within the chain indicates the presence of quadruply bonded, diamagnetic (Cr2)4+ dimers and paramagnetic, pseudo‐octahedrally coordinated Ni2+ ions. This is in good agreement with the paramagnetic behavior found between 2 and 300 K, which can be described using the Curie–Weiss law. The obtained effective magnetic moment μeff of 3.45 μB clearly shows the existence of pseudo‐octahedrally coordinated Ni2+ (S = 1).
Comparing the Cost‐Effectiveness of Short Orthopedic Missions in Elective and Relief Situations in Developing Countries
Authors: Gosselin Richard A. , Gialamas Gus , Atkin Dave M.
Published: February 2011

Background

The earthquake that occurred in Haiti on 12 January 2010 elicited an unprecedented response from the American orthopedic community. Many small organizations, such as Operation Rainbow, were thrust into the unfamiliar environment of relief surgery, whereas they normally provide short elective reconstruction missions in developing countries.

Materials

Because of the chaotic nature of relief work, it was assumed that the organization’s efforts would be less cost‐effective than their usual elective work. To evaluate this conclusion, the present study was designed to compare the cost‐effectiveness of the organization’s usual elective missions with the emergency relief provided in the wake of the Haiti earthquake.

Results and conclusions

The assumption that emergency costs would be higher was proven wrong, with estimates of $362 per disability‐adjusted life‐year (DALY) averted in the elective group, and $343 per DALY averted in the relief group.
Video‐assisted Thoracoscopic Surgery: Hepatectomy for Liver Neoplasm
Authors: Murakami Masahiko , Aoki Takeshi , Kato Takashi
Published: February 2011

Background

Laparoscopic liver resection has recently gained wide acceptance for various liver tumors, thanks to advances in surgical techniques and devices. However, if the tumor is located in the subdiaphragmatic area of segments 7 and 8, resection is difficult. We demonstrate herein a novel technique for video‐assisted thoracoscopic surgery hepatectomy (VATS‐H) for liver tumors located in the subdiaphragmatic area.

Methods

Five patients underwent VATS‐H for a liver neoplasm. One port or two ports and two laparoscopic protectors were placed on the chest surrounding the tumor. Using intraoperative thoracoscopic ultrasonography (IOTU), the portion of the diaphragm located just above the tumor was cut and opened using laparoscopic coagulating shears. IOTU was performed on the liver surface, and the tumor margin was marked by electrocautery. For liver resection, microwave tissue coagulation or radiofrequency ablation was used for coagulation before liver transection and for coagulation of liver parenchyma during the transection.

Results

The mean operating time was 137 min (range 95–185 min), and the mean operative blood loss was 43 g (range 0–200 g). No postoperative complications were encountered.

Conclusions

VATS‐H appears useful for resecting liver tumors located in the subdiaphragmatic area.
Psychosocial developmental milestones in men with classic galactosemia
Authors: Gubbels Cynthia Sophia , Maurice‐Stam Heleen , Berry Gerard Thomas , Bosch Annet Maria , Waisbren Susan , Rubio‐Gozalbo Maria Estela , Grootenhuis Martha Alexandra
Published: February 2011

Patients with classic galactosemia suffer from several long term effects of their disease. Research in a group of mainly female patients has shown that these patients may also have a developmental delay with regard to their social aptitude. To study if male galactosemia patients achieve psychosocial developmental milestones more slowly than male peers from the general Dutch population, we assessed their development with the Course of Life Questionnaire (CoLQ). A total of 18 male galactosemia patients participated in this study (response rate 69%): 11 Dutch patients and seven American patients. We found severe delays in the social and psychosexual scales of this questionnaire, but not on the autonomy axis. These results are comparable to an earlier study with a limited number of male patients. The observed delays could be secondary to less developed social skills, cognitive dysfunction, or disrupted language development. We strongly recommend screening of galactosemia patients for developmental delays, to ensure early intervention through social skills training.
Investigation of Radialization and Rerouting of the Extensor Digiti Minimi (EDM) in the Abduction Deformity of the Little Finger: A Cadaver Study
Authors: van Aaken Jan , Zhu Jin , Fasel Jean H. D. , Beaulieu Jean-Yves
Published: February 2011

Background

One of several operations to correct abduction deformity of the little finger, (Wartenberg's sign) in ulnar nerve palsy, is a combined procedure that radializes the extensor digiti minimi (EDM) at the level of the fifth metacarpophalangeal (MCP) joint and reroutes it from the fifth to fourth extensor compartment. This cadaveric study was designed to investigate the impact of both elements on adduction.

Materials and Methods

Anatomy of the little finger extensor apparatus was studied in 16 freshly frozen cadaver hands sectioned at mid forearm. We observed little finger motion after different modifications of the EDM. We tested the effect of a rerouting maneuver by pulling on the EDM, as well as radialization of the EDM alone and in combination with rerouting.

Results

The EDM was present in all cases. Little finger extensor digitorum communis (EDCV) was missing in two cadavers. In no case was adduction created by rerouting the EDM to the fourth compartment. Radialization of the EDM corrected the abduction deformity beyond the axis of abduction/adduction of the fifth MCP joint in 13 cases and only up to it in three cases. In one of the three with limited correction, a rerouting maneuver allowed for further adduction.

Conclusion

The key to correct abduction deformity of the little finger is radialization of the EDM, which can be done through a solitary incision at the level of the MCP joint. Rerouting alone does not correct the abduction deformity, and in combination with radialization it does not predictably enhance the correction.
Rayleigh–Bénard convection in the presence of spatial temperature modulations
Authors: FREUND G. , PESCH W. , ZIMMERMANN W.
Published: February 2011

Motivated by recent experiments, we study a rich variation of the familiar Rayleigh–Bénard convection (RBC), where the temperature at the lower boundary varies sinusoidally about a mean value. As usual the Rayleigh number R measures the average temperature gradient, while the additional spatial modulation is characterized by a (small) amplitude δm and a wavevector qm. Our analysis relies on precise numerical solutions of suitably adapted Oberbeck–Boussinesq equations (OBE). In the absence of forcing (δm = 0), convection rolls with wavenumber qc bifurcate only for R above the critical Rayleigh number Rc. In contrast, for δm≠0, convection is unavoidable for any finite R; in the most simple case in the form of ‘forced rolls’ with wavevector qm. According to our first comprehensive stability diagram of these forced rolls in the qm – R plane, they develop instabilities against resonant oblique modes at R ≲ Rc in a wide range of qm/qc. Only for qm in the vicinity of qc, the forced rolls remain stable up to fairly large R > Rc. Direct numerical simulations of the OBE support and extend the findings of the stability analysis. Moreover, we are in line with the experimental results and also with some earlier theoretical results on this problem, based on asymptotic expansions in the limit δm → 0 and R → Rc. It is satisfying that in many cases the numerical results can be directly interpreted in terms of suitably constructed amplitude and generalized Swift–Hohenberg equations.
Lock-exchange gravity currents with a high volume of release propagating over a periodic array of obstacles
Authors: TOKYAY TALIA , CONSTANTINESCU GEORGE , MEIBURG ECKART
Published: February 2011

Large eddy simulations are employed to investigate the structure and evolution of a bottom-propagating compositional gravity current in a rectangular horizontal plane channel containing a series of identical large-scale obstacles (dunes and square ribs) at the channel bottom. Simulation results show that below a certain value of the additional drag force per unit streamwise length induced by the bottom obstacles (low drag cases), the gravity current propagating over an array of obstacles transitions to a regime where the average front velocity is close to constant. Past its initial stages, the total kinetic energy, Ek, increases in time proportional to t1/3, where t is the time since release. This behaviour is similar to the slumping phase observed for currents propagating over a flat bed, with the exception that in the latter case the temporal increase of Ek during the later stages of the slumping phase is much faster (Ek ~ t). Simulation results also show that above certain value of the drag force per unit streamwise length induced by the obstacles (high drag cases), the slumping phase can be very short. In this case, similar to currents propagating in a porous medium, the current transitions to a drag-dominated regime in which the front velocity decays proportionally to tβ, with β = −0.28, once the discharge of lock fluid at the position of the lock gate becomes close to constant in time.
The dynamics of macroparasite host-self-infection: a study of the patterns and processes of pinworm (Oxyuridae) aggregation
Authors: GREAR DANIEL A. , HUDSON PETER
Published: February 2011

Objectives.Among parasites, Taylor's power law identifies a tight relationship in aggregation of macroparasite infection intensity with few exceptions; notably, the nematode family Oxyuridae tends to have higher than expected aggregation. Oxyuridae infect a wide range of mammalian hosts and have a unique reproductive strategy that involves conventional horizontal transmission, as well as re-infection of an already infected host. We asked the question, do the unique aspects of pinworm life-history explain an exception to the widely observed patterns of aggregation of parasite populations?Methods.We empirically examined the differences among Oxyuridae (genus:Syphacia) compared with other helminth (genus:Heligmosomoides) parasite aggregations in 2 rodent hosts with similar ecology: the yellow-necked mouse (Apodemus flavicollis) from Trento, Italy and the white-footed mouse (Peromyscus leucopus) from Pennsylvania, USA. To investigate the effects of pinworm life-history characteristics on generating aggregation, we present a stochastic model that explores aggregation under a range of host-self-infection, parasite death, and transmission scenarios.Results.Oxyuridae parasites had consistently greater aggregation compared to other nematodes regardless of host or parasite species identity, and pinworm aggregation exceeded the range of macroparasite aggregation described previously.Conclusions.Our simulations demonstrate that host-self-infection, on its own, is sufficient to generate aggregation values greater than the predicted values.
The acceptability and safety of praziquantel alone and in combination with mebendazole in the treatment of Schistosoma mansoni and soil-transmitted helminthiasis in children aged 1–4 years in Uganda
Authors: NAMWANJE HARRIET , KABATEREINE NARCIS B. , OLSEN ANNETTE
Published: February 2011

Objective. There is limited information on the acceptability and safety of praziquantel for treatment of schistosomiasis in children below the age of four years. In addition, although mebendazole has been extensively used together with praziquantel against infections with schistosomiasis and soil-transmitted helminthiasis (STH) in school-aged children, no specific acceptability or safety studies have been published on this drug combination in younger children. Methods. A randomized clinical trial was conducted to determine the safety of praziquantel alone and in combination with mebendazole in the treatment of Schistosoma mansoni and STH in children aged 1 to 4 years. Results. A total of 596 children from Bwondha fishing community in Mayuge district and Wang-Kado fishing community in Nebbi district were investigated using duplicate Kato-Katz thick smears of two stool samples and 130 (21·8%) were found infected with S. mansoni. Of these, 19·2% (25) had heavy intensity of infections. Of the infected children, 82 were included and randomised into praziquantel (40 mg/kg) + mebendazole (500 mg) or praziquantel (40 mg/kg) alone. Conclusion. Many symptoms were reported before treatment while very few were reported after treatment and all on treatment day. No serious adverse events were reported or observed after treatment. Praziquantel with or without mebendazole was well tolerated in small children in the study area.
Failing to adapt – the ageing immune system's role in cancer pathogenesis
Authors: Jones Christopher M
Published: February 2011

A person's risk of developing cancer rises exponentially with age, an increase that is widely considered to result from cumulative exposure to mutagenic agents. However, cancer incidence rates decelerate and plateau beyond 85 years of age and numerous malignant pathologies peak in incidence during early or middle life, indicating an important role for additional factors in controlling the timing and nature of cancer development. Given that immune function is known to decrease with age, malignant neoplastic change may be induced by increased chronic infection and the onset of a pervasive low grade inflammatory environment. This article discusses in detail the ageing immune system's role in cancer pathogenesis and demonstrates that key polymorphisms coding for relatively low pro-inflammatory cytokine production act to protect some populations from age-induced neoplastic transformation.
Welfare State Regimes and Reforms: A Classification of Ten European Countries between 1990 and 2006
Authors: Arcanjo Manuela
Published: February 2011

As from the beginning of the 1990s, almost all European countries have introduced wide-reaching social changes, among others in eligibility, entitlement, benefits structures and in the sources of financing. In this article, we propose that a consequence of those reforms may have been a repositioning of some countries in the welfare clusters. To test this hypothesis, we apply the two bi-dimensional classifications of Bonoli (1997) and Kautto (2002) to ten countries as representative of different welfare regimes. Our results reveal an interesting repositioning of some countries, especially Portugal, the UK and Sweden that represents evidence of welfare state reforms.
Relativistic jets: Physics and simulations
Authors: Hawley John F.
Published: February 2011

Jets are one of the more dramatic and visible manifestations of black hole accretion. It is becoming increasingly accepted that magnetic fields underlie the mechanism behind the launching of relativistic jets. At the same time it is now appreciated that the fundamental driving mechanism behind accretion is due to magnetohydrodynamical processes and the stresses they engender. Global disk simulations in full general relativity have begun to reveal the radial dependence of disk stresses and the intimate connections between accretion and jet-launching. This talk will review the issues involved, the recent progress that has been made, and the challenges that remain.
Probing the accretion disk - jet connection via instabilities in the inner accretion flow. From microquasars to quasars
Authors: Janiuk Agnieszka , Czerny Bożena , Mościbrodzka Monika , Siemiginowska Aneta
Published: February 2011

We present various instability mechanisms in the accreting black hole systems which might indicate at the connection between the accretion disk and jet. The jets observed in microquasars can have a peristent or blobby morphology. Correlated with the accretion luminosity, this might provide a link to the cyclic outbursts of the disk. Such duty-cycle type of behaviour on short timescales results from the thermal instability caused by the radiation pressure domination. The same type of instability may explain the cyclic radioactivity of the supermassive black hole systems. The somewhat longer timescales are characteristic for the instability caused by the partial hydrogen ionization. The distortions of the jet direction and complex morphology of the sources can be caused by precession of the disk-jet axis.
Self-consistent spectra from GRMHD simulations with radiative cooling A link to reality for Sgr A*
Authors: Drappeau Samia , Dibi Salomé , Markoff Sera , Fragile Chris
Published: February 2011

Cosmos++ (Anninos et al. 2005) is one of the first fully relativistic magneto-hydro-dynamical (MHD) codes that can self-consistently account for radiative cooling, in the optically thin regime. As the code combines a total energy conservation formulation with a radiative cooling function, we have now the possibility to produce spectra energy density from these simulations and compare them to data. In this paper, we present preliminary results of spectra calculated using the same cooling functions from 2D Cosmos++ simulations of the accretion flow around Sgr A*. The simulation parameters were designed to roughly reproduce Sgr A*'s behavior at very low (10−8–10−7 M⊙/yr) accretion rate, but only via spectra can we test that this has been achieved.
Radiation from matter entrainment in astrophysical jets: the AGN case
Authors: Araudo A. T. , Bosch-Ramon V. , Romero G. E.
Published: February 2011

Jets are found in a variety of astrophysical sources. In all the cases the jet propagates with a supersonic velocity through the external medium, which can be inhomogeneous, and inhomogeneities could penetrate into the jet. The interaction of the jet material with an obstacle produces a bow-like shock within the jet in which particles can be accelerated up to relativistic energies and emit high-energy photons. In this work, we explore the active galactic nuclei scenario, focusing on the dynamical and radiative consequences of the interaction at different jet heights. We find that the produced high-energy emission could be detectable by the current γ-ray telescopes. In general, the jet-clump interactions are a possible mechanism to produce (steady or flaring) high-energy emission in many astrophysical sources in which jets are present.
Unveiling the nature of extragalactic jets with Chandra observations
Authors: Massaro F. , Cheung C. C. , Harris D. E.
Published: February 2011

In 1974 Fanaroff & Riley divided the extended radio sources into two classes, on the basis of their radio morphology and power. For several years we have been collecting basic parameters for extragalactic jets detected in the X-rays, looking for an extension of the classification criterion, based on their radio and X-rays properties. The fact that different processes have been proposed to explain their X-ray radiation, (synchrotron vs inverse Compton emission) suggests the possibility of a new classification scheme. However, comparing the radio-to-X-ray properties of the extragalactic jets, several aspects on their nature became unexpectedly unclear.
Radio variability of blazars
Authors: Fan J. H. , Xu W. , Pan J. , Yuan Y. H.
Published: February 2011

In this work, we present the analysis results using UMRAO preliminary data base. We used the light curves 1) to get the shortest timescales and then to get the brightness temperature so that we can estimate the Doppler factors; 2) to investigate the periodicity and discuss the variability index. We also used the data base to discuss the polarization properties of blazars. We found that the periodicity distribution in BL Lacs and that in the flat spectrum radio quasars should be from the same distribution. The Doppler factor in FSRQs is higher than that in BL. The polarization in BLs are higher than that in the flat spectrum radio quasars
3D-MHD simulations of the evolution of magnetic fields in FR II radio sources
Authors: Huarte-Espinosa Martín , Krause Martin , Alexander Paul
Published: February 2011

3D-MHD numerical simulations of bipolar, hypersonic, weakly magnetized jets and synthetic synchrotron observations are presented to study the structure and evolution of magnetic fields in FR II radio sources. The magnetic field setup in the jet is initially random. The power of the jets as well as the observational viewing angle are investigated. We find that synthetic polarization maps agree with observations and show that magnetic fields inside the sources are shaped by the jets' backflow. Polarimetry statistics correlates with time, the viewing angle and the jet-to-ambient density contrast. The magnetic structure inside thin elongated sources is more uniform than for ones with fatter cocoons. Jets increase the magnetic energy in cocoons, in proportion to the jet velocity. Both, filaments in synthetic emission maps and 3D magnetic power spectra suggest that turbulence develops in evolved sources.
Relativistic jets in Narrow-Line Seyfert 1
Authors: Foschini L. , Angelakis E. , Bonnoli G. , Calderone G. , Colpi M. , D'Ammando F. , Donato D. , Falcone A. , Fuhrmann L. , Ghisellini G. , Ghirlanda G. , Hauser M. , Kovalev Y. Y. , Maraschi L. , Nieppola E. , Richards J. , Stamerra A. , Tagliaferri G. , Tavecchio F. , Thompson D. J. , Tibolla O. , Tramacere A. , Wagner S.
Published: February 2011

Narrow-Line Seyfert 1 (NLS1) class of active galactic nuclei (AGNs) is generally radio-quiet, but a small percent of them are radio-loud. The recent discovery by Fermi/LAT of high-energy γ-ray emission from 4 NLS1s proved the existence of relativistic jets in these systems. It is therefore important to study this new class of γ-ray emitting AGNs. Here we report preliminary results about the observations of the July 2010 γ-ray outburst of PMN J0948+0022, when the source flux exceeded for the first time 10−6 ph cm−2 s−1 (E > 100 MeV).
Investigating accretion disk – radio jet coupling across the stellar mass scale
Authors: Miller-Jones James C. A. , Sivakoff Gregory R. , Altamirano Diego , Körding Elmar G. , Krimm Hans A. , Maitra Dipankar , Remillard Ron A. , Russell David M. , Tudose Valeriu , Dhawan Vivek , Fender Rob P. , Heinz Sebastian , Markoff Sera , Migliari Simone , Rupen Michael P. , Sarazin Craig L.
Published: February 2011

Relationships between the X-ray and radio behavior of black hole X-ray binaries during outbursts have established a fundamental coupling between the accretion disks and radio jets in these systems. I begin by reviewing the prevailing paradigm for this disk-jet coupling, also highlighting what we know about similarities and differences with neutron star and white dwarf binaries. Until recently, this paradigm had not been directly tested with dedicated high-angular resolution radio imaging over entire outbursts. Moreover, such high-resolution monitoring campaigns had not previously targetted outbursts in which the compact object was either a neutron star or a white dwarf. To address this issue, we have embarked on the Jet Acceleration and Collimation Probe Of Transient X-Ray Binaries (JACPOT XRB) project, which aims to use high angular resolution observations to compare disk-jet coupling across the stellar mass scale, with the goal of probing the importance of the depth of the gravitational potential well, the stellar surface and the stellar magnetic field, on jet formation. Our team has recently concluded its first monitoring series, including (E)VLA, VLBA, X-ray, optical, and near-infrared observations of entire outbursts of the black hole candidate H 1743-322, the neutron star system Aquila X-1, and the white dwarf system SS Cyg. Here I present preliminary results from this work, largely confirming the current paradigm, but highlighting some intriguing new behavior, and suggesting a possible difference in the jet formation process between neutron star and black hole systems.
Jet-disk connection in OJ287
Authors: Valtonen Mauri J. , Savolainen Tuomas , Wiik Kaj
Published: February 2011

A model for OJ 287 consisting of two orbiting black holes has been constructed using optical light curve data. The model has successfully predicted the occurrence of sharp optical outbursts of OJ 287 for the past 15 years. Here we test if also the variations in the radio jet position angle can be explained within the framework of this same model, which has most of its parameters fixed by the timing of the optical flares. The model applied here has only three free parameters left, the (trivial) zero point of the jet position angle, the time lag between changes in the disk and jet orientations, and the zero point of the viewing angle. Despite its simplicity and the small number of free parameters, the model appears to be able to reproduce the main properties of the observed position angle variations during the past 30 years. The best fits are obtained when the time lag is either ~4 or ~14 years. However, the jet orientation seems to be unrelated to the direction of the spin of the primary black hole. This implies, assuming that the basic model is correct, that the mean orientation of the jet is determined by the orientation of the inner accretion disk, not by the spin axis of the black hole.
Connections between jet formation and multiwavelength spectral evolution in black hole transients
Authors: Kalemci Emrah , Chun Yoon-Young , Dinçer Tolga , Buxton Michelle , Tomsick John A. , Corbel Stephane , Kaaret Philip
Published: February 2011

Multiwavelength observations are the key to understand conditions of jet formation in Galactic black hole transient (GBHT) systems. By studying radio and optical-infrared evolution of such systems during outburst decays, the compact jet formation can be traced. Comparing this with X-ray spectral and timing evolution we can obtain physical and geometrical conditions for jet formation, and study the contribution of jets to X-ray emission.

In this work, first X-ray evolution - jet relation for XTE J1752-223 will be discussed. This source had very good coverage in X-rays, optical, infrared and radio. A long exposure with INTEGRAL also allowed us to study gamma-ray behavior after the jet turns on. We will also show results from the analysis of data from GX 339-4 in the hard state with SUZAKU at low flux levels. The fits to iron line fluorescence emission show that the inner disk radius increases by a factor of >27 with respect to radii in bright states. This result, along with other disk radius measurements in the hard state will be discussed within the context of conditions for launching and sustaining jets.
A new model of emission from microquasar jets, and possible explanation to the outliers of the fundamental plane
Authors: Pe'er Asaf , Casella Piergiorgio
Published: February 2011

We present a new model of emission from jets in microquasars, which implements elements from the study of jets in gamma-ray bursts to these objects. By assuming that electrons are accelerated once at the base of the jet to a power law distribution above a low energy Maxwellian, and are cooled by synchrotron emission and possible adiabatic energy losses along the jet, a wealth of spectra can be obtained. We show our theoretical results which can explain some of the key observations. In particular, we show that: (I) a flat radio spectrum, as is frequently seen, is a natural outcome of the model; (II) Strong magnetic field results in a flux decay in the optical/UV band as Fν ~ ν−1/2, irrespective of many of the uncertainties of the model. (III) An increase of the magnetic field above a critical value of ~105 G leads to a sharp decrease in the flux at the radio band, while the flux at higher frequencies saturates to a constant value. We conclude that scatter in the values of the magnetic field may provide a natural explanation to the observed scatter in the radio/X ray luminosity correlation seen in these objects.
MHD simulations of jet formation - protostellar jets & applications to AGN jets
Authors: Fendt Christian , Vaidya Bhargav , Porth Oliver , Nezami Somayeh Sheikh
Published: February 2011

Jet formation MHD simulations are presented considering a variety of model setups. The first approach investigates the interrelation between the disk magnetisation profile and jet collimation. Our results suggest (and quantify) that outflows launched from a very concentrated region at the inner disk tend to be weakly collimated. In the second approach, jet formation is investigated from a magnetic field configuration consisting of a stellar dipole superposed by a strong disk field. We find that the central dipole considerably de-collimates the disk wind. In addition, reconnection flares are launched in the interaction region of disk and stellar magnetic field, subsequently changing the outflow mass flux by factors of two. The time interval between flare ejection is about 1000 Keplerian periods - surprisingly similar to the observed time lag between jet knots. The third approach considers radiative pressure effects on jet collimation - an environment which is interesting mainly for outflows from massive young stars (but also for relativistic jets). Finally we present relativistic MHD simulations of jet formation from accretion disks extenting the previous non-relativistic approaches.
Side-entrainment in a jet embedded in a sidewind
Authors: López-Cámara D. , Raga A. C.
Published: February 2011

In this study, we present the results from 3D simulations in which a side-streaming motion pushes the post-bow shock into direct contact with the jet beam. This is a possible mechanism for modeling well collimated molecular jets as an atomic/ionic flow which entrains molecules initially present only in the surrounding environment.
Adolescents’ Perceptions of the Democratic Functioning in their Families
Authors: Stattin Håkan , Persson Stefan , Burk William J. , Kerr Margaret
Published: February 2011

Democratic family functioning has traditionally been interpreted as effects of parenting, leaving little room for the adolescent in shaping the democratic climate. Here we argued that an understanding of the democratic family functioning has to involve both adolescent and parental behaviors. We hypothesized that parental openness and fair treatment, and adolescent openness, each uniquely predict changes in democratic family functioning. Also, we argued that family functioning constellations characterized by parental openness and fair treatment, and adolescent openness, should be the constellations adolescents experience as democratic, and where parents know much about their adolescents’ whereabouts outside home. We used a longitudinal study following a group of 13–15-year-old adolescents (N = 527) over 2 years. Results using variable-oriented methods confirmed that both adolescent and parental behaviors were prospectively linked to adolescents’ perceptions of the democratic family climate. Person-oriented methods showed that adolescents perceived a highly democratic family climate, and that parents’ knowledge was highest, in families characterized by both parental and adolescent openness and parental fair treatment. Over-time changes in family functioning corresponded to changes in parental knowledge and adolescents’ perceptions of democratic family functioning. We conclude that conceptions of the democratic functioning of the family have to include the behaviors of both parents and adolescents, and that mutual responsivity is a marker of the democratic family functioning.
Reset Button and Instructional Advice in Computer Simulations
Authors: Daniel Rey Günter
Published: February 2011

Two experiments involving 107 (Study 1) and 98 (Study 2) students investigated how a computer simulation should be designed and how students should be supported in order to optimize their learning outcome. Thereby, a reset button that served to reset the visualization to its initial state and enabled a more systematic exploration as well as instructional advice were used in the simulation. An introductory text and a simulation were given to students in order to learn fundamental concepts about self-organizing maps, which is a special kind of neural network. Learners who received a reset button in the simulation did not perform better on succeeding retention or transfer tests than learners who did not receive a reset button. Furthermore, nearly 60% learners did not use the button at all (Study 1). Therefore, instructional advice was added before the simulation that asked the student to examine the different parameters in the simulation systematically through the use of the reset button (Study 2). Students who received that advice used the button more often and performed better on transfer than students not receiving that advice. The results can be explained with the extended Scientific Discovery as Dual Search model and with the zone of proximal development.
Longitudinal Association of Maternal Attempt to Lose Weight During the Postpartum Period and Child Obesity at Age 3 Years
Authors: Sonneville Kendrin R. , Rifas‐Shiman Sheryl L. , Oken Emily , Peterson Karen E. , Gortmaker Steven L. , Gillman Matthew W. , Taveras Elsie M.
Published: February 2011

The effect of maternal attempt to lose weight during the postpartum period on later child weight has not been explored. Among 1,044 mother‐infant pairs in Project Viva, we estimated longitudinal associations of maternal attempt to lose weight during the postpartum period with child weight and adiposity at age 3 years and examined differences in associations by type of weight loss strategy used. Using covariate‐adjusted linear and logistic regression models, we estimated associations before and after adjusting for maternal weight‐related variables including prepregnancy BMI. At 6 months postpartum, 53% mothers were trying to lose weight. At age 3 years, mean (s.d.) child BMI z‐score was 0.44 (1.01) and 8.9% of children were obese. Children whose mothers were trying to lose weight at 6 months postpartum had higher BMI z‐scores (0.30 (95% confidence interval (CI) 0.18, 0.42)) and were more likely to be obese (3.0 (95% CI 1.6, 5.8)) at 3 years of age. Addition of maternal prepregnancy BMI to the models attenuated but did not eliminate the associations seen for BMI z‐score (0.24 (95% CI 0.12, 0.36) and obesity (2.4 (95% CI 1.2, 4.7)). Attempting to lose weight by exercising alone was the only weight loss strategy that consistently predicted higher child BMI z‐score (0.36 (95% CI 0.14, 0.58)) and odds of obesity (6.0 (95% CI 2.2, 16.5)) at age 3 years. In conclusion, we observed an association between maternal attempt to lose weight at 6 months postpartum, particularly through exercise alone, measured using a single item and child adiposity at age 3 years. This association should be thoroughly examined in future studies.
Relations of Circulating Resistin and Adiponectin and Cardiac Structure and Function: The Framingham Offspring Study
Authors: McManus David D. , Lyass Asya , Ingelsson Erik , Massaro Joseph M. , Meigs James B. , Aragam Jayashri , Benjamin Emelia J. , Vasan Ramachandran S.
Published: February 2011

Obesity is associated with pathological cardiac remodeling and risk of heart failure (HF). Adipocytokines (ADKs) may mediate the increased risk of cardiovascular disease associated with excess adiposity. Yet data relating ADKs to cardiac remodeling phenotypes are sparse. We related two circulating ADKs, resistin and adiponectin, to three important echocardiographic markers of cardiac remodeling, left ventricular mass (LVM), left atrial diameter (LAD), and LV fractional shortening (LVFS) in 2,615 participants (mean age 61 years, 55% women) in the Framingham Offspring Study. Adiponectin concentrations were inversely related to LVM in multivariable linear regression models adjusting for key clinical correlates including BMI (regression coefficient per s.d.‐increment in ln‐adiponectin = −3.37, P = 0.02; P for trend across quartiles = 0.02). Adiponectin was not associated with LAD or LVFS (P > 0.56). Resistin concentrations were inversely related to LVFS (regression coefficient per s.d.‐increment in ln‐resistin = −0.01, P = 0.03; P for trend across quartiles = 0.04). Resistin was not associated with LVM or LAD (P > 0.05). In our moderate‐sized, community‐based sample, higher circulating concentrations of adiponectin and resistin were associated with lower LVM and lower LVFS, respectively. In conclusion, these associations identify potential mechanisms by which excess adiposity may mediate adverse cardiac remodeling and HF risk.
Emission spectroscopy of laser ablation plasma with time gating by acousto-optic modulator
Authors: Sakka Tetsuo , Irie Kyohei , Fukami Kazuhiro , Ogata Yukio H.
Published: February 2011

The capability of acousto-optic modulator (AOM) to perform time-gated measurements for laser ablation plasma spectroscopy has been examined. Especially, we focused on the capability of the “AOM gating” to exclude the continuum and extremely broadened spectra usually observed immediately after the laser ablation. Final goal of the use of the AOM is to achieve considerable downsizing of the system for in situ and on-site analyses. In the present paper, it is shown that narrow and clear spectral lines can be obtained with the AOM gating even if the target is submerged in water. Also, application of this technique to the targets in air is demonstrated. It has been revealed that the AOM gating is fast enough to exclude the continuum and broadened lines, while effectively acquiring sufficiently narrow atomic lines lasting slightly longer than the continuum.
Size effects on formation energies and electronic structures of oxygen and zinc vacancies in ZnO nanowires: A first-principles study
Authors: Fang D. Q. , Zhang R. Q.
Published: February 2011

We investigated the energetic, structural, and electronic properties of neutral O and Zn vacancies in ZnO nanowires with different sizes based on the first-principles calculations using density functional theory. We found that for ZnO nanowire with an O vacancy on the surface the formation energy is not sensitive to the size change. The presence of the surface O vacancy results in the formation of the metal-metal bonds. From the band structure analysis, we predicted that the optical property relating to the O vacancy can be strongly altered with decreasing the nanowire diameter. Moreover, there is a large structural deformation on the surface in the presence of Zn vacancy. The formation of a Zn vacancy in the ZnO nanowire with diameter of 16.4 Å is more favorable than in those with smaller diameters. Furthermore, the O vacancy is nonmagnetic, whereas the Zn vacancy is spin-polarized with a magnetic moment of 2.0 μB on the surface. Our results are helpful for understanding these defects in ZnO nanowires and thus useful for nanodevice design.
Structural characterization of ZnO nanopillars grown by atmospheric-pressure metalorganic chemical vapor deposition on vicinal 4H-SiC and SiO2/Si substrates
Authors: Tsiaoussis I. , Khranovskyy V. , Dimitrakopulos G. P. , Stoemenos J. , Yakimova R. , Pecz B.
Published: February 2011

The structural characteristics of ZnO nanocrystals epitaxially grown on p-type (0001) 4H-SiC substrates were studied by transmission electron microscopy (TEM). The nanocrystallites were grown by atmospheric-pressure metalorganic chemical vapor deposition. The ZnO nanocrystals were formed at terraces introduced by vicinal 4H-SiC substrates toward the [112¯0] direction. They had the shape of hexagonal nanopillars, with their edges parallel to the 〈112¯0〉 directions and a top c-plane facet, reflecting the crystal symmetry of ZnO. The free surface between the hexagonal nanopillars was covered by a very thin and highly defected epitaxial ZnO film, which strongly suggests the Stranski-Krastanov mode of growth. The ZnO/SiC interface was systematically studied by plane view TEM and cross sectional high resolution TEM. The residual strain in the thin continuous film as well as in the nanopillars was estimated from Moiré patterns and by geometrical phase analysis. ZnO was also deposited on the SiO2/Si substrate for comparison. The films were polycrystalline exhibiting strong preferred orientation, with the c-axes of the grains almost perpendicular to the substrate resulting in the formation of nanopillars. The differences of nanopillar formation in the two substrates, 4H-SiC and SiO2 is also discussed.
Magneto-inductive cable arrays: Estimation and reduction of crosstalk
Authors: Syms R. R. A. , Solymar L.
Published: February 2011

Magneto-inductive waveguides are linear periodic structures consisting of regular arrangements of L-C resonators coupled together by mutual inductances M. Magneto-inductive cable is a low-loss flexible variant, based on overlapping inductors and parallel plate capacitors formed by double-sided patterning of copper-clad polyimide. The properties of cable arrays formed from a set of parallel magneto-inductive lines are investigated. Numerical solutions are provided for typical arrangements. Analytic methods are introduced for estimating the coupling between elements in neighboring cables and the frequency dependence of cross-talk. Theoretical confirmation is provided by experimental results for cables operating at ≈100 MHz. Strategies for reducing cross-talk using alternative element designs that achieve low mutual inductance by cancellation of induced currents are explored.
Effect of Te inclusions in CdZnTe crystals at different temperatures
Authors: Hossain A. , Bolotnikov A. E. , Camarda G. S. , Gul R. , Kim K.-H. , Cui Y. , Yang G. , Xu L. , James R. B.
Published: February 2011

CdZnTe crystals often exhibit nonuniformities due to the presence of Te inclusions and dislocations. High concentrations of such defects in these crystals generally entail severe charge-trapping, a major problem in ensuring the device’s satisfactory performance. In this study, we employed a high-intensity, high-spatial-resolution synchrotron x-ray beam as the ideal tool to generate charges by focusing it over the large Te inclusions, and then observing the carrier’s response at room- and at low-temperatures. A high spatial 5-μm resolution raster scan revealed the fine details of the presence of extended defects, like Te inclusions and dislocations in the CdZnTe crystals. A noticeable change was observed in the efficiency of electron charge collection at low temperature (1 °C), but it was hardly altered at room-temperature.
Hard x-ray nano patterning using a sectioned multilayer
Authors: Lee Su Yong , Cho In Hwa , Kim Jae Myung , Yan Hanfei , Conley Ray , Liu Chian , Macrander Albert T. , Maser Jörg , Stephenson G. Brian , Kang Hyon Chol , Noh Do Young
Published: February 2011

We report a hard x-ray patterning capable of drawing lines with a width below100 nm using x-rays at 0.165 nm. A specially prepared mask based on multilayer growth technology was used as an x-ray mask effectively. The x-ray Talbot effect in near field was investigated and utilized in the patterning. Since multilayers with a few nanometer layer spacing are readily available, the proposed hard x-ray nano patterning, free of the limit imposed by the Rayleigh criterion in optical range, can potentially be an ultimate optical lithography technique.
Nonlinear optical properties of covalently linked graphene-metal porphyrin composite materials
Authors: Krishna M. Bala Murali , Kumar V. Praveen , Venkatramaiah N. , Venkatesan R. , Rao D. Narayana
Published: February 2011

The nonlinear optical (NLO) and optical limiting (OL) properties of covalently linked graphene-porphyrin composite materials were investigated using Z-scan technique in nanosecond regime. We observed enhanced NLO and OL properties of graphene-porphyrin composites in comparison to the individual graphene and porphyrins. The improved OL property of composites is attributed to energy transfer between porphyrin and graphene, which improved excited state absorption and nonlinear scattering. Nonlinear optical susceptibilities χ(3) of graphene and graphene-porphyrin composites were, in the order of 10−12 esu, measured using degenerate four wave mixing technique in nanosecond regime. High values of excited state absorption and two-photon absorption were observed for the composites.
How does the first water shell fold proteins so fast?
Authors: Collet Olivier
Published: February 2011

First shells of hydration and bulk solvent play a crucial role in the folding of proteins. Here, the role of water in the dynamics of proteins has been investigated using a theoretical protein-solvent model and a statistical physics approach. We formulate a hydration model where the hydrogen bonds between water molecules pertaining to the first shell of the protein conformation may be either mainly formed or broken. At thermal equilibrium, hydrogen bonds are formed at low temperature and are broken at high temperature. To explore the solvent effect, we follow the folding of a large sampling of protein chains, using a master-equation evolution. The dynamics shows a clear mechanism. Above the glass-transition temperature, a large ratio of chains fold very rapidly into the native structure irrespective of the temperature, following pathways of high transition rates through structures surrounded by the solvent with broken hydrogen bonds. Although these states have an infinitesimal probability, they act as strong dynamical attractors and fast folding proceeds along these routes rather than pathways with small transition rates between configurations of much higher equilibrium probabilities. At a given low temperature, a broad jump in the folding times is observed. Below this glass temperature, the pathways where hydrogen bonds are mainly formed become those of highest rates although with conformational changes of huge relaxation times. The present results reveal that folding obeys a double-funnel mechanism.