bluuebunny/crossref_metadata_2025 huggingface dataset:
Machiavelli'sL'Asino:Troubled Centaur into Conscious Ass
Authors: King Ed
Published: June 2008

Abstract.In this paper I examine some of the allegorical connections Machiavelli made in his unfinished poemL'Asino(The Ass) and make the case that they shed new light on the historical embeddedness of the more overtly political works, especiallyThe Prince. When read alongsideThe Prince,L'Asinoindicates what led Machiavelli to involve himself in politics in the first place, what he hoped to gain by his role as advisor and, afterwards, what his reaction was to his apparent failure to make his case effectively. It also offers us clues as to how Machiavelli conceived of his role as advisor to the Medici and highlights the anger he felt at having allowed himself to believe that his suggestions would be accepted without question and acted upon in the spirit in which they were intended. Some of the most important aspects of the poem I deal with focus on political metamorphoses, especially the prince's apotheosis into a successful Icarus and Machiavelli's less successful transition into Chiron the centaur. I also examine the allegorical significance of Diana and Circe, the message of the Abbot of Gaeta, and the implications of the Dantean allusions in the poem and perhaps most importantly the historical implications of the opening passage for Machiavelli's early entry into the political life of hispatria.

Résumé.Dans cet essai, je montre J'indique comment certains liens allégoriques, établis par Machiavel etablit dans son poème inachevé,l'asino L'Âne(l'ane), font la lumière sur l'imbriquement historique des oeuvres machiavéliques de nature plus explicitement politique, surtoutL e Prince. La lecture del'asino L'Âneen parallèl avecLe Prince, indique indique à la fois ce qui d'abord porta Machiavel à se mêler de politique, ce qu'il espérait gagner en tant que conseiller et, par suite, ce que fut sa réaction face devant son incapacité dea son inabilite a soutenir sa cause. Une telle lecture offre également des indices sur sa façon de concevoir son rôle de conseiller aux Médicis et met en relief la rage qu'il éprouva pour s'être permis de croire que ses conseils seraient accueiqueillis sans questions et qu'on leur donnerait suite dans l'esprit même dans lequel ils furent avaient ét proférés. D'importants aspects aspects du poème traitent de métamorphoses politiques, telles l'apothéose du prince en Icare vainqueur et la moins heureuse transition de Machiavel en Chiron le centaure. J'examine également la légende de Ninus et Sardanapalus, le sens allégorique de Diane et de Circé, le message de l'abbé de Gaëte, le sens des allusions dantesques et boéthiennes et, ce qui est peut-être le plus important,, peut etre plus important, les implications historiques de la première partie du poème pour l'entré de Machiavel dans la vie politique de sapatrie.
The three-dimensional transition in the flow around a rotating cylinder
Authors: EL AKOURY R. , BRAZA M. , PERRIN R. , HARRAN G. , HOARAU Y.
Published: June 2008

The flow around a circular cylinder rotating with a constant angular velocity, placed in a uniform stream, is investigated by means of two- and three-dimensional direct numerical simulations. The successive changes in the flow pattern are studied as a function of the rotation rate. Suppression of vortex shedding occurs as the rotation rate increases (>2). A second kind of instabilty appears for higher rotation speed where a series of counter-clockwise vortices is shed in the upper shear layer. Three-dimensional computations are carried out to analyse the three-dimensional transition under the effect of rotation for low rotation rates. The rotation attenuates the secondary instability and increases the critical Reynolds number for the appearance of this instability. The linear and nonlinear parts of the three-dimensional transition have been quantified by means of the amplitude evolution versus time, using the Landau global oscillator model. Proper orthogonal decomposition of the three-dimensional fields allowed identification of the most energetic modes and three-dimensional flow reconstruction involving a reduced number of modes.
Flow structure behind two staggered circular cylinders. Part 1. Downstream evolution and classification
Authors: HU J. C. , ZHOU Y.
Published: June 2008

Flow structures, Strouhal numbers and their downstream evolutions in the wake of two-staggered circular cylinders are investigated at Re=7000 using hot-wire, flow-visualization and particle-image velocimetry techniques. The cylinder centre-to-centre pitch, P, ranges from 1.2d to 4.0d (d is the cylinder diameter) and the angle (α) between the incident flow and the line through the cylinder centres is 0° ~ 90°. Four distinct flow structures are identified at x/d ≥ 10 (x is the downstream distance from the mid-point between the cylinders), i.e. two single-street modes (S-I and S-II) and two twin-street modes (T-I and T-II), based on Strouhal numbers, flow topology and their downstream evolution. Mode S-I is further divided into two different types, i.e. S-Ia and S-Ib, in view of their distinct vortex strengths. Mode S-Ia occurs at P/d ≤ 1.2. The pair of cylinders behaves like one single body, and shear layers separated from the free-stream sides of the cylinders roll up, forming one street of alternately arranged vortices. The street is comparable to that behind an isolated cylinder in terms of the topology and strength of vortices. Mode S-Ib occurs at α ≤ 10° and P/d > 1.5. Shear layers separated from the upstream cylinder reattach on or roll up to form vortices before reaching the downstream cylinder, resulting in postponed flow separation from the downstream cylinder. A single vortex street thus formed is characterized by significantly weakened vortices, compared with Mode S-Ia. Mode S-II is identified at P/d=1.2~2.5 and α>20° or 1.5≤P/d≤4.0 and 10° < α≤20°, where both cylinders generate vortices, with vortex shedding from the upstream cylinder at a much higher frequency than from the downstream, producing two streets of different widths and vortex strengths at x/d≤5.0. The two streets interact vigorously, resulting in a single street of the lower-frequency vortices at x/d≥10. The vortices generated by the downstream cylinder are significantly stronger than those, originating from the upstream cylinder, in the other row. Mode T-I occurs at P/d≥2.5 and α=20°~88°; the two cylinders produce two streets of different vortex strengths and frequencies, both persisting beyond x/d=10. At P/d≥2.5 and α≥88°, the two cylinders generate two coupled streets, mostly anti-phased, of the same vortex strength and frequency (St≈0.21), which is referred to as Mode T-II. The connection of the four modes with their distinct initial conditions, i.e. interactions between shear layers around the two cylinders, is discussed.
The dipolar field of rotating bodies in two dimensions
Authors: SMITH STEFAN G. LLEWELLYN , MICHELIN SÉBASTIEN , CROWDY D. G.
Published: June 2008

The fluid velocity far from a translating body in two-dimensional irrotational flow is generally dipolar. This is a classical result. Here we ask when the dipolar component vanishes. Lamb (1945, § 126) provides symmetry conditions on the virtual mass tensor for this to be the case. We show that these conditions are not necessary and obtain the sufficient and necessary condition in terms of the shape of the body using conformal maps. Some explicit examples are constructed based on this condition.
Simplified variational principles for barotropic magnetohydrodynamics
Authors: YAHALOM ASHER , LYNDEN-BELL DONALD
Published: June 2008

Variational principles for magnetohydrodynamics have been introduced by previous authors both in Lagrangian and Eulerian form. In this paper we introduce simpler Eulerian variational principles from which all the relevant equations of barotropic magnetohydrodynamics can be derived. The variational principle is given in terms of six independent functions for non-stationary barotropic flows with trivial topologies and three independent functions for stationary barotropic flows. This is less than the seven variables which appear in the standard equations of barotropic magnetohydrodynamics, which are the magnetic field B the velocity field v and the density ρ.

For non-trivial topologies it is necessary to assume that some of the variables introduced in the non-stationary formalism are non-single-valued. That is, it is necessary to introduce a number of branch cuts in order to define single-valued branches of the field variables. In turn, these cuts along with the six field variables constitute an extended number of dynamic variables. The number of cuts necessary depends on the flow. The relations between barotropic magnetohydrodynamics topological constants and the functions of the present formalism will be elucidated.

The equations obtained for non-stationary barotropic magnetohydrodynamics resemble the equations of Frenkel et al. (Phys. Lett. A, vol. 88, 1982, p. 461). The connection between the Hamiltonian formalism introduced in Frenkel et al. (1982) and the present Lagrangian formalism (with Eulerian variables) will be discussed.
Hysteretic and chaotic dynamics of viscous drops in creeping flows with rotation
Authors: YOUNG Y.-N. , BŁAWZDZIEWICZ J. , CRISTINI V. , GOODMAN R. H.
Published: June 2008

We have shown that high-viscosity drops in two-dimensional linear creeping flows with a non-zero vorticity component may have two stable stationary states. One state corresponds to a nearly spherical, compact drop stabilized primarily by rotation, and the other to an elongated drop stabilized primarily by capillary forces. Here we explore consequences of the drop bistability for the dynamics of highly viscous drops. Using both boundary-integral simulations and small-deformation theory we show that a quasi-static change of the flow vorticity gives rise to a hysteretic response of the drop shape, with rapid changes between the compact and elongated solutions at critical values of the vorticity. In flows with sinusoidal temporal variation of the vorticity we find chaotic drop dynamics in response to the periodic forcing. A cascade of period-doubling bifurcations is found to be directly responsible for the transition to chaos. In random flows we obtain a bimodal drop-length distribution. Some analogies with the dynamics of macromolecules and vesicles are pointed out.
Miscible porous media displacements driven by non-vertical injection wells
Authors: UPCHURCH E. , MEIBURG E.
Published: June 2008

High-resolution simulations are employed to identify and analyse the mechanisms dominating miscible porous media displacements generated by inclined injection wells. Compared to vertical injection wells, significant differences are observed that strongly influence breakthrough times and recovery rates. Constant density and viscosity displacements, for which the velocity field is potential in nature, demonstrate the existence of pronounced flow non-uniformities, due to the interaction of the inclined well with the reservoir boundaries. These non-uniformities deform the fronts during the initial displacement stages.

In the presence of a viscosity difference, the non-uniformities of the potential flow field result in a focusing of the fingering instability. If the fluids also have different densities, a gravity tongue will reinforce the dominant finger along one front, while a gravitational instability leads to the disintegration of the dominant finger along the other front. Hence, the two fronts emerging from the inclined injection well usually evolve very differently from each other for variable density and viscosity displacements.

For inclined injection wells and sufficiently large mobility ratios, gravity tongues are seen to evolve dendritically for an intermediate range of density contrasts. While mild gravitational forces are necessary to create the gravity tongue in the first place, large density differences will suppress the growth of the dendritic side branches. Since the dendritic branches appear along the side of the gravity tongue that should be stable according to traditional stability criteria, it can be concluded that the tip region plays a crucial role in their formation.
Scaling laws for drag of a compliant body in an incompressible viscous flow
Authors: ZHU LUODING
Published: June 2008

Motivated by an important discovery on the drag scaling law (the 4/3 power law) of a flexible fibre in a flowing soap film by Albenet al. (Naturevol. 420, 2002, p.479) at high Reynolds numbers (2000<Re<40000), we investigate drag scaling laws at moderateRefor a compliant fibre tethered at the midpoint and submerged in an incompressible viscous flow using the immersed boundary (IB) method. Our work shows that the scaling of drag with respect to oncoming flow speed varies withRe, and the exponents of the power laws decrease monotonically from approximately 2 towards 4/3 asReincreases from 10 to 800.
Asymmetry and transition to turbulence in a smooth axisymmetric constriction
Authors: VÉTEL J. , GARON A. , PELLETIER D. , FARINAS M.-I.
Published: June 2008

The flow through a smooth axisymmetric constriction (a stenosis in medical applications) of 75% restriction in area is measured using stereoscopic and time-resolved particle image velocimetry (PIV) in the Reynolds number range Re ~ 100–1100. At low Reynolds numbers, steady flow results reveal an asymmetry of the flow downstream of the constriction. The jet emanating from the throat of the nozzle is deflected towards the wall causing the formation of a one-sided recirculation region. The asymmetry results from a Coanda-type wall attachment already observed in symmetric planar sudden expansion flows. When the Reynolds number is increased above the critical value of 400, the separation surface cannot remain attached and an unsteady flow regime begins. Low-frequency axial oscillations of the reattachment point are observed along with a slow swirling motion of the jet. The phenomenon is linked to a periodic discharge of the unstable recirculation region inducing alternating laminar and turbulent flow phases. The resulting flow is highly non-stationary and intermittent. Discrete wavelet transforms are used to discriminate between the large-scale motions of the mean flow and the vortical and turbulent fluctuations. Continuous wavelet transforms reveal the spectral structure of flow disturbances. Temporal measurements of the three velocity components in cross-sections are used with the Taylor hypothesis to qualitatively reconstruct the three-dimensional velocity vector fields, which are validated by comparing with two-dimensional PIV measurements in meridional planes. Visualizations of isosurfaces of the swirling strength criterion allow the identification of the topology of the vortices and highlight the formation and evolution of hairpin-like vortex structures in the flow. Finally, with further increase of the Reynolds number, the flow exhibits less intermittency and becomes stationary for Re ~ 900. Linear stochastic estimation identifies the predominance of vortex rings downstream of the stenosis before breakdown to turbulence.
Passive locomotion of a simple articulated fish-like system in the wake of an obstacle
Authors: ELDREDGE JEFF D. , PISANI DAVID
Published: June 2008

The behaviour of a passive system of two-dimensional linked rigid bodies in the wake of a circular cylinder atRe=100 is studied computationally. The three rigid bodies are connected by two frictionless hinges, and the system (‘fish’) is initially aligned with a streamwise axis three diameters behind the cylinder. Once flow symmetry is broken, the wake rolls up into a Kármán vortex street in which the fish is stably trapped, and the passing large-scale vortices induce an undulatory shape change in the articulated system. It is found that, for certain fish lengths relative to cylinder diameter, the fish is propelled upstream toward the cylinder. Furthermore, the fish is propelled equally effectively when the hinges are locked, confirming that induced body undulation is not necessary for achieving a net thrust. An analysis of the forces on constituent bodies shows that leading-edge suction and negative skin friction on the forward portion of the fish are in competition with positive skin friction on the aft portion; propulsion is achieved when the forebody contributions dominate those on the aftbody. It is shown that the so-called ‘suction zone’ behind the cylinder that enables this passive propulsion is double the length of that without a fish present.
Effect on hearing of ganciclovir therapy for asymptomatic congenital cytomegalovirus infection: four to 10 year follow up
Authors: Lackner A , Acham A , Alborno T , Moser M , Engele H , Raggam R B , Halwachs-Baumann G , Kapitan M , Walch C
Published: June 2008

Background:

Congenital cytomegalovirus infection is the leading identified nongenetic cause of congenital sensorineural hearing loss. Most of the infections are asymptomatic but may be detected from umbilical cord vein and/or newborn serum positivity for human cytomegalovirus immunoglobulin M, and from urine positivity (on polymerase chain reaction) for human cytomegalovirus deoxyribonucleic acid in the newborn period. Children infected by cytomegalovirus may later develop sensorineural hearing loss. In symptomatically infected infants, ganciclovir therapy administered in the neonatal period prevents hearing deterioration. However, preventative therapy of asymptomatic congenital cytomegalovirus disease with ganciclovir is controversial, as side effects such as severe neutropenia may occur during treatment.

Methods:

The study population consisted of 23 asymptomatic children with congenital cytomegalovirus infection. Twelve children were treated just after diagnosis of cytomegalovirus infection in the newborn period, with ganciclovir 10 mg/kg bodyweight for 21 days. The other 11 children were observed without therapy. Over a four to 10 year follow-up period, we evaluated all the children's hearing status using pure tone audiometry.

Results:

All 23 children had normal sensorineural hearing at one year follow up. Five of the 23 children (21.7 per cent) were lost to follow up over the four to 11 year follow-up period. Of the remaining 18 children, sensorineural hearing loss occurred in two (11.1 per cent). Neither child had been treated with ganciclovir in the newborn period. An eight-year-old boy showed bilateral high frequency loss and a 10-year-old girl showed severe unilateral sensorineural hearing loss. In the ganciclovir-treated group (nine children), none showed sensorineural hearing loss. During ganciclovir therapy, moderate neutropenia occurred as a side effect in two out of 12 (16.6 per cent) treated children. Speech and general development were normal in all children.

Conclusion:

Asymptomatic congenital cytomegalovirus infection is likely to be a leading cause of sensorineural hearing loss in young children. Intravenous ganciclovir therapy seems to offer a medical option to prevent subsequent sensorineural hearing loss. Further studies including a greater number of children are needed. Cytomegalovirus screening models are mandatory if medical therapy is to be implemented in time.
Use of item response theory to understand differential functioning of DSM-IV major depression symptoms by race, ethnicity and gender
Authors: Uebelacker L. A. , Strong D. , Weinstock L. M. , Miller I. W.
Published: June 2008

Background

Psychological literature and clinical lore suggest that there may be systematic differences in how various demographic groups experience depressive symptoms, particularly somatic symptoms. The aim of the current study was to use methods based on item response theory (IRT) to examine whether, when equating for levels of depression symptom severity, there are demographic differences in the likelihood of reporting DSM-IV depression symptoms.

Method

We conducted a secondary analysis of a subset (n=13 753) of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) dataset, which includes a large epidemiological sample of English-speaking Americans. We compared data from women and men, Hispanics and non-Hispanic Whites, African Americans and Whites, Asian Americans and Whites, and American Indians and Whites.

Results

There were few differences overall, although the differences that we did find were primarily limited to somatic symptoms, and particularly appetite and weight disturbance.

Conclusions

For the most part, individuals responded similarly to the criteria used to diagnose major depression across gender and across English-speaking racial and ethnic groups in the USA.
Self-reported childhood trauma correlates with schizotypal measures in schizophrenia but not bipolar pedigrees
Authors: Schürhoff F. , Laguerre A. , Fisher H. , Etain B. , Méary A. , Soussy C. , Szöke A. , Leboyer M.
Published: June 2008

Background

Strong evidence supports the association between childhood trauma and psychotic disorders. In two different high-risk populations, we looked for a correlation between the magnitude of schizotypal dimensions and the importance of self-reported childhood trauma.

Method

A sample of 138 unaffected first-degree relatives was recruited (67 relatives of schizophrenic probands and 71 relatives of bipolar probands). The relationship between schizotypal dimensions and childhood trauma scores was analyzed by partial correlations.

Results

A positive correlation was found between childhood trauma scores and total schizotypal scores in first-degree relatives of schizophrenic subjects but not in first-degree relatives of bipolar probands. This correlation was primarily due to a strong association with the positive dimension of schizotypy.

Conclusions

The significant correlation between childhood trauma and schizotypal dimensions in subjects at high genetic risk for schizophrenia suggests that susceptibility genes for schizophrenia may interact with childhood trauma to induce the emergence of schizotypal dimensions, mainly positive psychotic features.
HIV testing among individuals with a severe mental illness: review, suggestions for research, and clinical implications
Authors: Senn T. E. , Carey M. P.
Published: July 2008

Background

The prevalence of human immunodeficiency virus (HIV) is elevated among individuals with a severe mental illness (SMI). Because of the benefits of HIV testing, it is important for individuals with SMI to have routine access to testing. The goals of this review are: to summarize knowledge about HIV testing prevalence, correlates, and interventions among individuals with an SMI; to identify research needs; and to discuss clinical implications of the studies reviewed.

Method

Literature searches were conducted using PsycINFO, PubMed, and Medline. Additional articles were obtained from reference lists of relevant articles.

Results

Fewer than one-half of individuals with an SMI have been tested for HIV in the past year. Engaging in sex or drug risk behavior was the only consistent correlate of HIV testing. Interventions for promoting HIV testing among individuals with an SMI have not been well developed or evaluated.

Conclusions

Research on HIV testing among individuals with an SMI is needed. Mental health settings may be opportune venues for HIV testing, even though providers face ethical challenges when implementing testing programs in these settings.
Vulnerable relations: lifecourse, wellbeing and social exclusion in Buenos Aires, Argentina
Authors: LLOYD-SHERLOCK PETER , LOCKE CATHERINE
Published: June 2008

Many have presumed that in developing countries contact with children is beneficial to older people's wellbeing, and particularly that women receive more support from children than men because of their lifelong commitment to family responsibilities. This study questions these stylised notions through an analysis of 22 life histories of older women and men living in a district with high rates of social exclusion in Buenos Aires, Argentina. It focuses on the subjective accounts of relationships with children and grandchildren and their influence on current wellbeing. The life histories reveal complex lived experiences and the significance of key events. The informants speak of the anxiety and harm caused by struggling children, about problems of remote relations with successful children, and of the insecurity of the neighbourhood. The analysis contrasts a materialistic interpretation of the influence of children on older people's wellbeing with the informants' more holistic evaluation of family relationships. By applying a lifecourse framework, we demonstrate among other things that children may be a key source of vulnerability for older people, that the gendering of parent-child relations and later-life wellbeing is nuanced, and that both local and national conditions influence relationships with specific children, with implications for the intergenerational transmission of wellbeing.
In support of innovation theory: innovation in activity patterns and life satisfaction among recently retired individuals
Authors: NIMROD GALIT
Published: June 2008

A central theme of ‘innovation theory’, which the author and a colleague have proposed and which is concerned with the triggers, types and benefits of innovation in later life, is that adding brand-new leisure activities after retiring from work enhances post-retirement wellbeing. The study reported in this article aimed to examine this proposition using quantitative data from a nationwide sample in Israel of 378 recently retired individuals. The study explored the frequency of post-retirement innovation in people's leisure repertoires, the association between innovation and retirees' life satisfaction, and factors in the differing life satisfaction of innovators and non-innovators. The results indicate that the inclination toward innovation significantly associated with the respondents' work and retirement histories, as well as with their self-rated health and world region of origin. Innovators had significantly higher life satisfaction than non-innovators, but this difference could not be explained by the number of new activities. In addition, socio-demographic differences failed to explain innovators' wellbeing. While some support for innovation theory was provided, further research is required to explore the dynamics by which innovation at older ages contributes to retirees' wellbeing.
The housing situation and residential strategies of older people in France
Authors: BONVALET CATHERINE , OGG JIM
Published: June 2008

During the later 20th century, France experienced a dramatic turn around in the quality of its housing. The current cohort of older people witnessed and lived through the transformation. Most people aged over 50 years in France are homeowners and almost one-in-four own a second home. Although the oldest age groups are much less residentially mobile than younger people, home moves are more likely around the age of retirement or widowhood. In recent years, new forms of residential mobility in later life have been emerging. These include a weakening of the commonly observed pattern of a permanent drift away from cities and towns towards areas of childhood origin or family connections. One current trend suggests a preference for preserving residential links with areas of relatively high population density and good access to amenities, coupled with being able to spend time elsewhere, whether in second homes, in children's and grandchildren's homes, or elsewhere. The arrival of the post-1945 baby-boom cohort at retirement has begun, and this may increase the current level of residential mobility and lead to more diverse types, although the change will depend on the development of the housing market as well as residential preferences in old age.
Individual pension-related risk propensities: the effects of socio-demographic characteristics and a spousal pension entitlement on risk attitudes
Authors: CLARK GORDON L. , STRAUSS KENDRA
Published: June 2008

The transition from defined-benefit to defined-contribution occupational-pension plans has placed a premium on the participants' or contributors' decision-making competence. Their attitudes to risk and their responses to available investment options can have far-reaching implications for their retirement income. Behavioural research on risk and uncertainty has raised understanding of the limits of individual decision-making, but the social status and demographic characteristics of plan participants may also affect risk perception and pension choices. By studying a random sample of the British adult population, this paper explores the significance of socio-demographic characteristics for pension-related risk attitudes. It is demonstrated that pension-plan participants do not appear to understand the risks associated with different types of retirement savings and pension plans. The paper also shows that the gender, age and income of plan participants can give rise to distinctive risk propensities, and that marital status and, in particular, whether a spouse also has a pension can also have significant consequences for household risk preferences. These results have implications for those segments of the population that are disadvantaged in the labour market. Employer-provided pensions' education and information programmes may have to be more basic and more closely tailored to the social status of pension plan participants than hitherto assumed or hoped.
Self-focusing effect in Au-target induced by high power pulsed laser at PALS
Authors: Torrisi L. , Margarone D. , Laska L. , Krasa J. , Velyhan A. , Pfeifer M. , Ullschmied J. , Ryc L.
Published: June 2008

Self-focusing effects, induced by ASTERIX pulsed laser at PALS Laboratory of Prague, have been investigated. Laser was employed at the third harmonics (438 nm) and intensities of the order of 1016 W/cm2. Pure Au was used as thin target and irradiated with 30° incidence angle. An ion energy analyzer was employed to detect the energy-to-mass ratio of emitted ions from plasma. Measurements were performed by changing the focal point position with a high spatial resolution step-motor. Results demonstrated that non linear processes, due to self-focusing effects, occurs when the laser beam is focused at about 200 µm in front of the target surface. In such conditions, a new ion group, having high charge state and kinetic energy, is produced because of the increment in temperature of the laser-generated plasma.
Motion analysis of a spherical mobile robot
Authors: Joshi Vrunda A. , Banavar Ravi N.
Published: June 2008

A path planning algorithm for a spherical mobile robot rolling on a plane is presented in this paper. The robot is actuated by two internal rotors that are fixed to the shafts of two motors. These are in turn mounted on the spherical shell in mutually orthogonal directions. The system is nonholonomic due to the nonintegrable nature of the rolling constraints. Further, the system cannot be converted into a chained form, and neither is it nilpotent nor differentially flat. So existing techniques of nonholonomic path planning cannot be applied directly to the system. The approach presented here uses simple geometrical notions and provides numerically efficient and intuitive solutions. We also present the dynamic model and derive motor torques for execution of the algorithm. Along the proposed paths, we achieve dynamic decoupling of the variables making the algorithm more suitable for practical applications.
Impact of maternal malaria and under-nutrition on intrauterine growth restriction: a prospective ultrasound study in Democratic Republic of Congo
Authors: LANDIS S. H. , LOKOMBA V. , ANANTH C. V. , ATIBU J. , RYDER R. W. , HARTMANN K. E. , THORP J. M. , TSHEFU A. , MESHNICK S. R.
Published: June 2008

Maternal malaria and under-nutrition are established risk factors for small-for-gestational-age (SGA) births; however, whether malaria is associated with intrauterine growth restriction (IUGR) is unknown. We investigated IUGR risk among 177 HIV-negative pregnant women enrolled in a longitudinal ultrasound study conducted in Democratic Republic of Congo from May 2005 to May 2006. Malaria infection, maternal anthropometrics, and ultrasound estimated fetal weight were measured monthly. All positive malaria cases were treated and intermittent presumptive therapy (IPTp) provided. Log-binomial regression models for IUGR were fitted using generalized estimating equations to account for statistical clustering of repeat IUGR measurements. Twenty-nine percent of fetuses experienced an episode of IUGR with the majority occurring in the third trimester. The risk of IUGR associated with malaria was greatest after three or more cumulative infections (RR 3·3, 95% CI 1·3–8·2) and was two- to eight-fold higher among women with evidence of under-nutrition. Receiving antimalarial treatment in the previous month (for IPTp or treatment) was significantly protective against IUGR (RR 0·5, 95% CI 0·3–0·7). The interaction observed between malaria and under-nutrition suggests that antenatal programmes in malaria endemic areas should incorporate nutritional screening and supplementation in addition to IPTp.
Towards an anatomically correct repair for anomalous left coronary artery arising from the pulmonary trunk
Authors: Muneer Amanullah M. , Rostron Anthony J. , Leslie Hamilton J. R. , Chaudhari Milind P. , Hasan Asif
Published: June 2008

Background

Anomalous origin of the left coronary artery from the pulmonary trunk is rare, occurring at an incidence of 1 in 300 000. If not diagnosed and treated early, it is life-threatening. Children with the anomaly usually present in infancy with congestive cardiac failure, and are occasionally referred for cardiac transplant. We investigated the medium term outcome for patients following creation of a two-coronary arterial circulation.

Methods

Between 1992 and 2007, we diagnosed 15 patients seen at our Institution as having anomalous origin of the left coronary artery from the pulmonary trunk. Over a period of 13 years, aortic reimplantation was undertaken in 12 of these patients, who form the studied cohort.

Results

Direct reimplantation was performed in 5 patients. In 3 cases, a tension-free anastomosis was created using a caudally based flap. In another 3 cases, an extended flap was used, while a patch arterioplasty was fashioned in the final patient. There were no deaths. Left ventricular function recovered in all but one of the patients, and all patients had a reduction in the degree of mitral regurgitation.

Conclusions

Among the variety of surgical techniques, transfer of the anomalous left coronary artery to the aorta is the ideal method for long-term patency and adequate blood supply. This can be achieved by creating flaps based on the walls of the pulmonary trunk and aorta, producing a dual coronary arterial supply with no mortality and low morbidity.
Pathological changes and myocardial remodelling related to the mode of shunting following surgical palliation for hypoplastic left heart syndrome
Authors: Padalino Massimo A. , Castellani Chiara , Toffoli Silvia , Barbera Mila Della , Milanesi Ornella , Thiene Gaetano , Stellin Giovanni , Angelini Annalisa
Published: June 2008

Background

The modification of placing the shunt from the right ventricle to the pulmonary arteries, also known as Sano procedure, has allegedly improved results over the short term in surgical palliation of hypoplastic left heart syndrome with the Norwood procedure. With this in mind, we reviewed autopsied specimens from neonates and children who did not survive after either a classic arterio-pulmonary shunt, or the modified procedure with the shunt placed from the right ventricle to the pulmonary arteries, so as to evaluate the pathological substrates of the remodelling of the systemic right ventricle, assessing any differences induced by the 2 techniques.

Methods

We obtained the hearts from 11 patients with neonatal diagnosis of hypoplastic left heart syndrome who died after the first or second stages of the Norwood sequence of operations, comparing them with 6 normal hearts matched for age and weight. Macroscopic, microscopic and morphometric analysis were performed on each specimen, evaluating the diameter of the myocytes, extracellular matrix remodelling in terms of fibrosis and type of collagen, and vascularization in terms of capillary density.

Results

Hypertrophy of the myocytes was significantly increased in the hearts from patients having either a classic arterio-pulmonary or the ventriculo-pulmonary modification of the shunt compared to controls (p < 0.05). Myocardial fibrosis was increased in those having a shunt placed from the right ventricle to the pulmonary arteries when compared to the other 2 groups. The ratio of collagen I to collagen III was similar in those undergoing a classic arterio-pulmonary shunt compared to controls (0.94), but was lower in those having a shunt placed from the right ventricle to the pulmonary arteries (0.61), with an increase in collagen type III. The density of capillaries was lower in those who had undergone a classic arterial shunt when compared to the others.

Conclusion

We have shown greater remodelling of the ventricular myocardial extracellular matrix in patients having a shunt from the right ventricle to the pulmonary arteries when compared to those having a classic arterio-pulmonary shunt, with this remodelling progressing even after the neonatal period. This may influence a later suboptimal ventricular performance.
Genetic and geographical divergence in horse gram germplasm from Andhra Pradesh, India
Authors: Sunil N. , Sivaraj N. , Pandravada S. R. , Kamala V. , Raghuram Reddy P. , Varaprasad K. S.
Published: June 2008

Nine characters contributing to seed yield were measured on 20 accessions of horse gram (Macrotyloma uniflorum (Lam.) Verd), and subjected to genetic divergence analysis using Mahalanobis statistic and mapping using DIVA-GIS. The accessions were collected from two eco-geographical regions of Andhra Pradesh (India) – North Coastal and Rayalaseema. Based on D2 values the genotypes were grouped into five clusters. Genetic diversity was not related to eco-geographical distribution. The greatest inter-cluster distance separated clusters II and V, followed by clusters IV, and V, III and IV. Entries in clusters V and II appear suitable as parents for horse gram improvement. The Rayalaseema region is the source of useful variation for days to flowering, maturity and yield.
Assessing farmer interest in participatory plant breeding: Who wants to work with scientists?
Authors: Dawson Julie C. , Goldberger Jessica R.
Published: June 2008

Participatory research, particularly participatory plant breeding (PPB), can increase the relevance of public-sector research to the agricultural community. PPB has mostly been used in developing countries with resource-poor farmers, but there is increasing interest among farmers in developed countries who are dissatisfied with the performance of available varieties. In 2006, scientists associated with the winter and spring wheat breeding programs in the Department of Crop and Soil Sciences and the Department of Community and Rural Sociology at Washington State University (WSU) conducted a survey of members of the Washington Association of Wheat Growers. Through analysis of the survey results, we sought to understand (1) whether or not farmers want to work with scientists in PPB programs and (2) the determinants of PPB interest. Results indicated that 52% of Washington wheat growers were interested in working with WSU scientists in a participatory breeding program. Interested farmers tended to be younger and college educated with fewer years of farming experience. Moreover, PPB interest appeared to be related positively to farm size, the number of wheat varieties planted, use of and interest in alternative production and marketing practices (e.g., seed saving, organic agriculture), and prior experience with WSU. Based on this analysis and ongoing discussions with farmers, we hope to develop a participatory wheat breeding program where farmers are able to choose their level of involvement with the breeding process based on their interest and needs. This new program will increase the relevance of WSU's wheat breeding programs to farmers in the state and could serve as a model for other public agricultural research programs seeking to increase farmer involvement and, thereby, democratize agricultural research.
‘I'm getting desperate’: what we know about farmers' markets that fail
Authors: Stephenson Garry , Lev Larry , Brewer Linda
Published: June 2008

This paper explores hidden problems amid the impressive expansion of farmers' markets in Oregon and throughout the United States. Although markets are growing in number, a surprisingly large number of them fail. A challenge for many markets is inadequate revenue to support market operations such as paying for the management personnel to perform functions necessary to grow and sustain markets. Smaller markets may enter a downward spiral in which they cannot attract additional customers because they do not have sufficient vendors but cannot attract additional vendors because they do not have sufficient customers. The analysis identifies five intertwined factors associated with markets that fail: small size, a high need for products, low administrative revenue, a volunteer or low paid manager and high manager turnover. The paper also examines the more general issue of why some markets struggle by exploring a correlation between new markets and inexperienced managers, and effort thresholds for volunteer managers. Recommendations to assist markets toward success include better planning, manager and board of director training and community financial support. The findings of this study have broad application.
External economic drivers and US agricultural production systems
Authors: Halloran J.M. , Archer D.W.
Published: June 2008

US agriculture operates in a market driven economy, although government policies can have influence on what farmers produce and how they produce it. As with other businesses, agricultural producers respond to economic incentives and disincentives, and make decisions to maximize their welfare; usually measured as net income. We examined how external economic drivers shape the type of agricultural systems that producers adopt. Specifically, we considered the influence of technological advancements, income supports embodied in farm legislation, and changes in market structure and consumer demand. Changes in technology have often favored large-scale and specialized operations. Many of the technological advancements have required large-scale production units to justify the investment. Often the technology has been commodity specific. However, there is some evidence that more diversified production units might be able to achieve economies of both scale and scope. The influence of commodity support programs has been ambiguous. As farm legislation has evolved to decouple production decisions from program benefits, the incentives to specialize in program crops (crops that receive price and/or income benefits under federal legislation, such as corn, other grains and oil seeds) have diminished. However, wealth and risk effects, albeit small, may have promoted or inhibited the adoption of a more integrated system. The ability of producers to adopt more integrated systems has been primarily influenced by their natural resource base and proximity to markets. Changes in market structure, channels and consumer demand in the past five decades have been dramatic with consolidation and specialization in both production and marketing sectors. However, the diversity of consumer demand has also created opportunities for more integrated farm operations. There is an increasing number of consumers who have become concerned about how and where their food has been produced. Markets for organic, locally produced, free range and the like are expected to grow. While price and income supports may have been biased towards specialization (as these programs were targeted to specific commodities), the reduction in risk associated with the programs has enabled producers to expand the number and diversity of their production enterprises. Furthermore, through the use of strategic alliances, cooperation among producers on a regional basis may eventually lead to greater integration and diversification than could be achieved for the individual farm operation.
The VLT Interferometer
Authors: Richichi A.
Published: July 2008

The ESO Very Large Telescope Interferometer (VLTI) is arguably the most powerful optical interferometric facility available at present. In addition to the wide choice of baselines and the light collecting power of its 8.2 m and 1.8 m telescopes, the VLTI also offers a smooth and user-friendly operation which makes interferometry accessible to any astronomer and covers a wide range of scientific applications. Behind the routine scientific operations, however, the VLTI is in constant evolution. I will present some of the technological and instrumental improvements which are planned for the near and mid-term future, and discuss their implications for astrometry in particular. Among them, the PRIMA facility and the proposed GRAVITY instrument are designed to reach the level of 10 microarcseconds in the near-infrared.
Searching for sub-stellar companions among nearby white dwarfs, through common proper motion
Authors: Radiszcz M. , Méndez R. A.
Published: July 2008

The purpose of this work is to do a systematic, deep search for sub-stellar objects orbiting nearby white dwarfs (WDs). The scientific interest spans testing specific predictions of models of common envelope phase, as well as providing constraints to planetary system evolution in advanced stages of its parent star. Additionally, we seek to explore the hypothesis about the origin of metal lines in hydrogen WDs, produced by the accretion of tidal disturbed asteroidal or cometary material. This could be linked to the presence of a planetary object. Here, we show preliminary results of our near-infrared astrometric project.
The new CCD Zenith Tube
Authors: Ron C. , Štefka V. , Vondrák J.
Published: July 2008

The reconstruction of the Photographic Zenith Tube (PZT) at Ondřejov has been finished recently. The main improvement of the instrument consists in the replacement of the photographic plate with the CCD chip, and a completely new electronic control system. In addition to the astrometric use of the observations we intend to derive the variations of the local vertical and compare them with gravimetric observations of the nearby station Pecný.
Finding orbital motion of sub-stellar companions - the case of TWA 5B
Authors: Schmidt T. , Neuhäuser R. , Mugrauer M.
Published: July 2008

TWA 5B is a brown dwarf companion of H=12 mag, 2″ off the ~5 mag brighter triple star CoD-33° 7795 (=TWA 5), a member of the TW Hydrae association of T Tauri stars at ~55 pc. This object is the first brown dwarf around a pre-main-sequence star (confirmed by common proper motion) ever found. In the last year we have newly reduced VLT NaCo data originally taken in 2003 and combined it with all the available astrometric data of the system to investigate possibly detectable orbital motion of the system. Indeed we were able to find linear orbital motion of the system combining data from HST, VLT and Gemini-North.
Study of centering CCD image of faint satellites near a bright primary object
Authors: Tang Z. H. , Li Y. , Yan Y. R. , Wang S. H. , Qiao R. C. , Shen K. X.
Published: July 2008

The polynomial-fit method is applied to remove the uneven background of a satellite when it is near a bright primary object. Detailed analysis of this method is given. Some useful conclusions are drawn from the results of simulated data.