bluuebunny/crossref_metadata_2025_split huggingface dataset:
A case-controlled study of Dientamoeba fragilis infections in children
Authors: BANIK G. R. , BARRATT J. L. N. , MARRIOTT D. , HARKNESS J. , ELLIS J. T. , STARK D. 
Published: April 2011

SUMMARYDientamoeba fragilis is a pathogenic protozoan parasite that is implicated as a cause of human diarrhoea. A case-controlled study was conducted to determine the clinical signs associated with D. fragilis infection in children presenting to a Sydney Hospital. Treatment options are also discussed. Stool specimens were collected from children aged 15 years or younger and analysed for the presence of D. fragilis. In total, 41 children were included in the study along with a control group. Laboratory diagnosis was performed by microscopy of permanently stained, fixed faecal smears and by real-time PCR. Gastrointestinal symptoms were present in 40/41 (98%) of these children with dientamoebiasis, with diarrhoea (71%) and abdominal pain (29%) the most common clinical signs. Chronic gastrointestinal symptoms were present in 2% of cases. The most common anti-microbial used for treatment was metronidazole (n=41), with complete resolution of symptoms and clearance of parasite occurring in 85% of cases. A treatment failure rate occurred in 15% of those treated with metronidazole. Follow-up treatment comprised of an additional course of metronidazole or iodoquinol was needed in order to achieve complete resolution of infection and symptoms in this group. This study demonstrates the pathogenic potential of D. fragilis in children and as such it is recommended that all laboratories must routinely test for this organism and treat if detected.
Effects of inbreeding on potential and realized immune responses inTenebrio molitor
Authors: RANTALA MARKUS J. , VIITANIEMI HEIDI , ROFF DEREK A. 
Published: April 2011

SUMMARYAlthough numerous studies on vertebrates suggest that inbreeding reduces their resistance against parasites and pathogens, studies in insects have found contradictory evidence. In this study we tested the effect of 1 generation of brother–sister mating (inbreeding) on potential and realized immune responses and other life-history traits inTenebrio molitor. We found that inbreeding reduced adult mass, pre-adult survival and increased development time, suggesting that inbreeding reduced the condition of the adults and thus potentially made them more susceptible to physiological stress. However, we found no significant effect of inbreeding on the potential immune response (encapsulation response), but inbreeding reduced the realized immune response (resistance against the entomopathogenic fungi,Beauveria bassiana). There was a significant family effect on encapsulation response, but no family effect on the resistance against the entomopathogenic fungi. Given that this latter trait showed significant inbreeding depression and that the sample size for the family-effect analysis was small it is likely that the lack of a significant family effect is due to reduced statistical power, rather than the lack of a heritable basis to the trait. Our study highlights the importance of using pathogens and parasites in immunoecological studies.
The effect of retirement and age at retirement on self-perceived health after three years of follow-up in Dutch 55–64-year-olds
Authors: RIJS KELLY J. , COZIJNSEN RABINA , DEEG DORLY J. H. 
Published: April 2011

ABSTRACTHealth consequences of retirement have not been included in the current public debate about increasing the age at retirement, which might be due to the fact that studies aimed at health consequences of retirement show ambiguous results. The literature indicates that various contextual characteristics might explain conflicting results. The current study examines the effect of retirement and age at retirement (55–64 years) on self-perceived health. Characteristics tested for confounding and effect modification were: demographic, health, psychological, job, and retirement characteristics. Subjects were 506 participants in the Longitudinal Aging Study Amsterdam (LASA). After three years, 216 retired and 290 remained employed. Multinomial logistic regression analyses show no main effect for retirement compared to continued employment. Modal (59–60) retirees were more likely to attain excellent or good self-perceived health (less than good self-perceived health as the reference category). Early (55–58) and late (61–64) retirees were unaffected by retirement if they did not receive a disability pension. Early and late retirees who received a disability pension were less likely to attain excellent self-perceived health after retirement. Higher educated were less likely to attain excellent self-perceived health after retirement, especially at late retirement age, although health selection might explain this result. Finally, mastery possibly acts as an adjustment resource. The paper concludes with a discussion on explanations for the effect of retirement and age at retirement.
An exploration of the value and mechanisms of befriending for older adults in England
Authors: LESTER HELEN , MEAD NICKI , GRAHAM CAROLYN CHEW , GASK LINDA , REILLY SIOBHAN 
Published: April 2011

ABSTRACTSocial isolation and loneliness in older adults are growing problems. Empirical research suggests that loneliness can lead to poorer health outcomes including higher mortality rates. Befriending has been shown to decrease loneliness and depression although the exact mechanisms of action are unclear. In this study we aimed to explore experiences and identify key ‘ingredients’ of befriending through interviews conducted with 25 older adults who had used five different befriending services across England. We used Berkman's theoretical model of how individual social networks impact on health to help interpret our data and explore the mechanisms of befriending for older adults. Findings suggest that befriending offers some compensation for loss of elective relationships from older adults’ social networks, providing opportunities for emotional support and reciprocal social exchange through development of safe, confiding relationships. Good conversational skills and empathy were the foundation of successful relationships within which commonalities were then sought. Befrienders broadened befriendees’ perspectives on life (particularly among older adults in residential care). Social engagement was a powerful mechanism of action, particularly in terms of connecting people back into the community, reinforcing meaningful social roles and connecting to a past life that had often been significantly disrupted by loss. Understanding key components and mechanisms of befriending for older adults may facilitate development of more effective and theoretically sound befriending services.
Modeling and control of biologically inspired flying robots
Authors: Couceiro Micael S. , Luz J. Miguel A. , Figueiredo Carlos M. , Ferreira N. M. Fonseca 
Published: April 2011

SUMMARYThis paper covers a wide knowledge of physical and dynamical models useful for building flying robots and a new generation of flying platform developed in the similarity of flying animals. The goal of this work is to develop a simulation environment and dynamic control using the high-level calculation tool MatLab and the modeling, simulation, and analysis of dynamic systems tool Simulink. Once created the dynamic models to study, this work involves the study and understanding of the dynamic stability criteria to be adopted and their potential use in the control of flying models.
Numerical criteria for integral dependence
Authors: ULRICH BERND , VALIDASHTI JAVID 
Published: April 2011

AbstractWe study multiplicity based criteria for integral dependence of modules or of standard graded algebras, known as ‘Rees criteria’. Rather than using the known numerical invariants, we achieve this goal with a more direct approach by introducing a multiplicity defined as a limit superior of a sequence of normalized lengths; this multiplicity is a non-negative real number that can be irrational.
Leading terms of Artin L-series at negative integers and annihilation of higher K-groups
Authors: NICKEL ANDREAS 
Published: April 2011

AbstractLetL/Kbe a finite Galois extension of number fields with Galois groupG. We use leading terms of ArtinL-series at strictly negative integers to construct elements which we conjecture to lie in the annihilator ideal associated to the Galois action on the higher dimensional algebraicK-groups of the ring of integers inL. For abelianGour conjecture coincides with a conjecture of Snaith and thus generalizes also the well-known Coates–Sinnott conjecture. We show that our conjecture is implied by the appropriate special case of the equivariant Tamagawa number conjecture (ETNC) provided that the Quillen–Lichtenbaum conjecture holds. Moreover, we prove induction results for the ETNC in the case of Tate motivesh0(Spec(L))(r), whereris a strictly negative integer. In particular, this implies the ETNC for the pair (h0(Spec(L))(r),), whereLis totally real,r< 0 is odd andis a maximal order containing ℤ[]G, and will also provide some evidence for our conjecture.
Berge's distance 3 pairs of genus 2 Heegaard splittings
Authors: SCHARLEMANN MARTIN 
Published: April 2011

AbstractFollowing an example discovered by John Berge [2], we show that there is a 4-component link L ⊂ (S1 × S2)#(S1 × S2) so that, generically, the result of Dehn surgery on L is a 3-manifold with two inequivalent genus 2 Heegaard splittings, and each of these Heegaard splittings is of Hempel distance 3.
Plücker formulae for singular space curves
Authors: WALL C. T. C. 
Published: April 2011

AbstractIn [4] I extended the Plücker formulae to curves in Pn for any n, under fairly strong genericity hypotheses. In this paper we seek to weaken these hypotheses using the theory of excess intersections. The method applies to just one of the formulae (so the results are complete only for n=3), and for this we obtain a number which is a sum of local contributions, given by an explicit rule. We evaluate these contributions in the cases when they are determined by the terms of least order in the respective Taylor expansions, thus obtaining explicit formulae in numerous cases.
Evolution of supercooling under coastal Antarctic sea ice during winter
Authors: Leonard Gregory H. , Langhorne Patricia J. , Williams Michael J.M. , Vennell Ross , Purdie Craig R. , Dempsey David E. , Haskell Timothy G. , Frew Russell D. 
Published: April 2011

AbstractHere we describe the evolution through winter of a layer of in situ supercooled water beneath the sea ice at a site close to the McMurdo Ice Shelf. From early winter (May), the temperature of the upper water column was below its surface freezing point, implying contact with an ice shelf at depth. By late winter the supercooled layer was c. 40 m deep with a maximum supercooling of c. 25 mK located 1–2 m below the sea ice-water interface. Transitory in situ supercooling events were also observed, one lasting c. 17 hours and reaching a depth of 70 m. In spite of these very low temperatures the isotopic composition of the water was relatively heavy, suggesting little glacial melt. Further, the water's temperature-salinity signature indicates contributions to water mass properties from High Salinity Shelf Water produced in areas of high sea ice production to the north of McMurdo Sound. Our measurements imply the existence of a heat sink beneath the supercooled layer that extracts heat from the ocean to thicken and cool this layer and contributes to the thickness of the sea ice cover. This sink is linked to the circulation pattern of the McMurdo Sound.
Rafting in the Antarctic springtail,Gomphiocephalus hodgsoni
Authors: Hawes T.C. 
Published: April 2011

AbstractCapture by water surfaces is a frequent but stochastic phenomenon for Antarctic collembolans (springtails), with implications for both the survival and dispersal of populations. This paper provides the first field description of the characteristics of rafting aggregations of the springtailGomphiocephalus hodgsoniand provides the first observation of the inclusion of the mite,Stereotydeus mollis, within these aggregations. Field observations of aggregations in meltwater pools are used to develop a picture of the ecological implications of rafting for Antarctic springtails. The potential for marine capture was also demonstrated by additional observations of two springtails aerially deposited on to sea ice as well as springtails floating in the tidewater cracks between the sea ice and land.
In vivo dosimetry; essential or unnecessary?
Authors: Leman Jenna L 
Published: April 2011

AbstractIntroduction: The radiotherapy profession has learned from errors made during treatment planning and delivery. Quality assurance in radiotherapy (QART) procedures are implemented to reduce the risk of an error occuring. The chief medical officer, along with others, has recommended that the QART of all departments includes in vivo dosimetry (IVD) to ensure that the delivered dose equals the planned dose.Why we need IVD: A lot of effort goes into field verification and it is just as vital that dosimetry is verified. Overdose to normal tissue can cause devastating side effects, even death, whilst tumour underdose may compromise control. Without IVD, there is no way of knowing that a patient is receiving an overdose until it is too late. Underdoses are unlikely to manifest without IVD. IVD allows radiotherapists and physicists to correct for dose errors in a timely manner.Why IVD is unnecessary: Radiotherapy accidents are rare. Implementing IVD is expensive, time consuming and takes resources away from developing techniques which will improve patient outcomes. Current IVD methods are not suitable for modern techniques such as intensity modulated radiotherapy (IMRT).Discussion: IVD appears to be a useful QART tool, particularly as dose escalation techniques develop allowing a higher dose to be delivered to the tumour. Departments may be unwilling to spend time and money on an IVD system that is costly and time consuming if it cannot perform IVD on modern techniques. Electronic portal imaging devices (EPIDs) can be utilised to perform IVD on complex techniques, such as IMRT and arc therapy, which current IVD methods cannot, however there is currently no EPID IVD system available commercially.Conclusion: Ideally, all departments would conduct IVD on all new patients. IVD has proven to be an important QART tool, however, until technology is developed to allow EPID to include IVD, the procedure is not likely to be implemented countrywide.
Modeling the prestellar cores in Ophiuchus
Authors: Whitworth Ant , Stamatellos Dimitri , Walch Steffi 
Published: April 2011

AbstractWe present the first results from a project to model the prestellar cores in Ophiuchus, using initial conditions constrained as closely as possible by observation. The prestellar cores in Ophiuchus appear to be evolving in isolation — in the sense that the timescale on which an individual prestellar core collapses and fragments is estimated to be much shorter than the timescale on which it is likely to interact dynamically with another core. Therefore it is realistic to simulate individual cores separately, and this in turn makes it feasible (a) to perform multiple realisations of the evolution of each core (to allow for uncertainties in the initial conditions which persist, even for the most comprehensively observed cores), and (b) to do so at high resolution (so that even the smallest protostars are well resolved). The aims of this project are (i) to address how best to convert the observations into initial conditions; (ii) to explore, by means of numerical simulations, how the observed cores are likely to evolve in the future; (iii) to predict the properties of the protostars that they will form (mass function, multiplicity statistics, etc.); and (iv) to compare these properties with the properties of the observed pre-Main Sequence stars in Ophiuchus. We find that if the observed non-thermal velocities in the Ophiuchus prestellar cores are attributed to purely solenoidal turbulence, they do not fragment; they all collapse to form single protostars. If the non-thermal velocities are attributed to a mixture of solenoidal and compressive turbulence, multiple systems form readily. The turbulence first generates a network of filaments, and material then tends to flow along the filaments, at first into a primary protostar, and then onto a compact accretion disc around this protostar; secondary protostars condense out of the material flowing into the disc along the filaments. If the turbulence is purely solenoidal, but part of the non-thermal velocity dispersion is attributed to solid-body rotation, then again multiple systems form readily, but the pattern of fragmentation is quite different. A primary protostar forms near the centre of the core, and then an extended accretion disc forms around the primary protostar, and eventually becomes so massive that it fragments to produce low-mass secondaries; these frequently end up in hierarchical multiple systems.
Low-mass Star Formation: Observations
Authors: Evans Neal J. 
Published: April 2011

AbstractI briefly review recent observations of regions forming low mass stars. The discussion is cast in the form of seven questions that have been partially answered, or at least illuminated, by new data. These are the following: where do stars form in molecular clouds; what determines the IMF; how long do the steps of the process take; how efficient is star formation; do any theories explain the data; how are the star and disk built over time; and what chemical changes accompany star and planet formation. I close with a summary and list of open questions.
Formation of massive stars
Authors: Beltrán Maria T. 
Published: April 2011

AbstractThe formation of high-mass stars represents a challenge from both a theoretical and an observational point of view. Here, we present an overview of the current status of the observational research on this field, outlining the progress achieved in recent years on our knowledge of the initial phases of massive star formation. The fragmentation of cold, infrared-dark clouds, and the evidence for star formation activity on some of them will be discussed, together with the kinematics of the gas in hot molecular cores, which can give us insights on the mechanism leading to the birth of an OB star.
Pre-main sequence disks
Authors: Duchêne Gaspard 
Published: April 2011

AbstractIn this contribution, I briefly review our empirical knowledge of disks around ≲2M⊙ pre-main sequence (T Tauri) stars, focusing first on the dichotomic question of their frequency before moving on to some more detailed disk properties (overall orientation, total mass, outer radius). Finally, I conclude with a brief discussion of disks around embedded protostars, which will play in the next few years a major role in testing star formation theory and simulations.
Fragmentation and dynamics in Massive Dense Cores in Cygnus-X
Authors: Csengeri T. , Bontemps S. , Schneider N. , Motte F. 
Published: April 2011

AbstractA systematic, high angular-resolution study of IR-quiet Massive Dense Cores (MDCs) of Cygnus-X in continuum and high-density molecular tracers is presented. The results are compared with the quasi-static and the dynamical evolutionary scenario. We find that the fragmentation properties are not compatible with the quasi-static, monolithic collapse scenario, nor are they entirely compatible with the formation of a cluster of mostly low-mass stars. The kinematics of MDCs shows individual velocity components appearing as coherent flows, which indicate important dynamical processes at the scale of the mass reservoir around high-mass protostars.
The Luminosity Problem: Testing Theories of Star Formation
Authors: McKee Christopher F. , Offner Stella R. R. 
Published: April 2011

AbstractLow-mass protostars are less luminous than expected. This luminosity problem is important because the observations appear to be inconsistent with some of the basic premises of star formation theory. Two possible solutions are that stars form slowly, which is supported by recent data, and/or that protostellar accretion is episodic; current data suggest that the latter accounts for less than half the missing luminosity. The solution to the luminosity problem bears directly on the fundamental problem of the time required to form a low-mass star. The protostellar mass and luminosity functions provide powerful tools both for addressing the luminosity problem and for testing theories of star formation. Results are presented for the collapse of singular isothermal spheres, for the collapse of turbulent cores, and for competitive accretion.
Internal Structure of Stellar Clusters: Geometry of Star Formation
Authors: Alfaro Emilio J. , Sánchez Néstor 
Published: April 2011

AbstractThe study of the internal structure of star clusters provides important clues concerning their formation mechanism and dynamical evolution. There are both observational and numerical evidences indicating that open clusters evolve from an initial clumpy structure, presumably a direct consequence of the formation in a fractal medium, toward a centrally condensed state. This simple picture has, however, several drawbacks. There can be very young clusters exhibiting radial patterns maybe reflecting the early effect of gravity on primordial gas. There can be also very evolved clusters showing fractal patterns that either have survived through time or have been generated subsequently by some (unknown) mechanism. Additionally, the fractal structure of some open clusters is much clumpier than the average structure of the interstellar medium in the Milky Way, although in principle a very similar structure should be expected. Here we summarize and discuss observational and numerical results concerning this subject.
Submillimeter Array Observations of Magnetic Fields in Star Forming Regions
Authors: Rao R. , Girart J.-M. , Marrone D. P. 
Published: April 2011

AbstractThere have been a number of theoretical and computational models which state that magnetic fields play an important role in the process of star formation. Competing theories instead postulate that it is turbulence which is dominant and magnetic fields are weak. The recent installation of a polarimetry system at the Submillimeter Array (SMA) has enabled us to conduct observations that could potentially distinguish between the two theories. Some of the nearby low mass star forming regions show hour-glass shaped magnetic field structures that are consistent with theoretical models in which the magnetic field plays a dominant role. However, there are other similar regions where no significant polarization is detected. Future polarimetry observations made by the Submillimeter Array should be able to increase the sample of observed regions. These measurements will allow us to address observationally the important question of the role of magnetic fields and/or turbulence in the process of star formation.