Elemental Composition of Cosmic Rays near the Knee by Multiparameter Measurement of Air Showerss

The small change in the spectral slope of the overall intensity of cosmic rays near 1 PeV may be associated with the endpoint energy of supernova shock acceleration. A crucial test of this connection and other ideas of the origin of the spectral `knee' is the reliable determination of the variation of elemental composition in this region. Recent measurements at the DICE/CASA/MIA air shower installation in Dugway, Utah, USA have provided several independent air shower parameters for each event. The derivation of elemental composition from a combination of Cherenkov size, depth of shower maximum in the atmosphere, muon size and electron size at ground level and the reliability of these results are discussed. There is no evidence from these data for a large change in the mean mass of cosmic rays across the `knee'. These measurements show the cosmic rays are composed of ~ 70% protons and alpha-particles near total energies of 10PeV.Comment: 29 pages including 10 figures Accepted for publication by Astroparticle Physics, 17th Sept. 199

Calcium-loaded hydrophilic hypercrosslinked polymers for extremely high defluoridation capacity via multiple uptake mechanisms

Hydrophilic hypercrosslinked porous polymer networks were synthesised from 2,2-biphenol (HHCP1) and bisphenol A (HHCP2) monomers, which were assessed for remediation of highly fluoridated water. The networks were hydrophilic and the hypercrosslinking radically altered the acidity of protonation sites within the polymeric scaffolds. The polymers were metallated to produce novel, hybrid Ca-loaded adsorbents. The metal-loading affected the electron distribution of the quinonoid structures formed during polymerisation. HHCP1 had a greater exchange capacity (6.34 ± 0.17 mmol g−1) and adsorbed more Ca2+, yet retained much of its original surface area, whereas HHCP2 was rendered non-porous upon metallation. Ca-loading included covalent interactions and formation of crystalline CaCO3 (vaterite), from preferential CO2 binding under ambient conditions. Both networks were effective defluoridating media, with Ca-loaded HHCP1 exhibiting a capacity among the highest yet reported for any extractant (267 ± 34 mg g−1). HHCP2-Ca had a lower capacity of 96.2 ± 10 mg g−1, but faster uptake kinetics and was more effective at lower concentrations, attributed to stronger binding interactions. Crystalline CaF2 (fluorite) was the dominant fluoride species formed, from both vaterite and covalently bound Ca. The networks could be used in a dynamic column system, extracted fluoride in the presence of multiple coexisting anions and were regenerable, with a potential pathway demonstrated for recovery of the adsorbed fluoride

Somatic cell nuclear transfer is associated with altered expression of angiogenic factor systems in bovine placentomes at term

Low efficiency of somatic cell cloning by nuclear transfer has been associated with alterations of placental vascular architecture. Placental growth and function depend on the growth of blood vessels; VEGF-A and bFGF are the most important factors controlling neovascularization and vascular permeability in the placenta. We hypothesize that the VEGF-A and bFGF systems are disrupted in placentomes from cloned animals, contributing to the placental abnormalities that are common in these clones. We determined mRNA expression and protein tissue localization of VEGF-A, bFGF, and their receptors in placentomes from cloned and non-cloned bovine fetuses at term. Real-time RT-PCR revealed that VEGFR-2 mRNA was increased in cloned male-derived placentomes, while mRNA of bFGF and its receptors were decreased in placentomes of cloned females. VEGF-A system proteins were found to be located in placentomal endothelial, maternal and fetal epithelial and stromal cells; there was a variable pattern of cellular distribution of these proteins in both cloned and non-cloned animals. Alterations in the expression of VEGF-A and bFGF systems suggest that angiogenic factors are involved in abnormal placental development in cloned gestations, contributing to impaired fetal development and poor survival ratesFAPESP 02/07392-7CAPES (PROBRAL grant 272/7)\ud CAPES (PROBRAL grant D/06/33937

Upravljanje silom mišićno-koštanog manipulatora pogonjenog spiralnim motorom

This paper presents force control of musculoskeletal manipulator driven by spiral motors. The kinematic and dynamic properties are shown to address the presence of ennvironmental contact with the manipulator. From this contact, the force control schemes were explored, by comparing between monoarticular-only structure and biarticular structure manipulator. Force control schemes were divided into independent muscle control, end effector step force command, and muscular viscoelasticity control. The results show advantages of biarticular actuation compared to monoarticular-only actuation in the feasibility of magnetic levitation (gap) control alongside force control.U ovome radu predstavljeno je upravljanje silom mišićno-koštanog manipulatora pogonjenog spiralnim motorom. Kinematička i dinamička svojstva prikazuju prisutnost kontakta manipulatora s okolinom. Na temelju kontakta istraženo je upravljanje silom usporedbom jednozglobne i dvozglobne strukture manipulatora. Upravljanje silom podijeljeno je u neovisno upravljanje mišićima, upravljanje alatom manipulatora (eng. end effector) i upravljanje mišićnom viskoelastičnosti. Rezultati pokazuju prednost dvozglobne strukture u odnosu na jednozglobnu u smislu izvedivosti upravljanja magnetskom levitacijom pored upravljanja silom

Incydenty sercowo-naczyniowe u pacjentów stosujących sildenafil - wyniki badania International Men’s Health Study

Wstęp: Celem pracy było oszacowanie częstości występowania poważnych incydentów sercowo-naczyniowych (np. zawał serca, udar) oraz całkowitej śmiertelności wśród mężczyzn z zaburzeniami erekcji otrzymujących sildenafil. Metody: Prospektywnym, obserwacyjnym badaniem kohortowym International Men’s Health Study (IMHS) objęto pacjentów ze zdiagnozowanymi zaburzeniami erekcji oraz wcześniej stosujących sildenafil lub dopiero zaczynających przyjmować ten preparat. Dane wyjściowe oraz z obserwacji odległej dotyczące chorób sercowo-naczyniowych (CVD), czynników ryzyka oraz zaburzeń erekcji uzyskano za pomocą odpowiednich kwestionariuszy. Do osób, które przebyły epizod sercowo-naczyniowy, wysłano kwestionariusze w celu zebrania informacji związanych z ekspozycją na sildenafil/leczeniem zaburzeń erekcji przed incydentem. Wyniki: W analizowanej grupie (n = 3813) odnotowano 35 incydentów sercowo-naczyniowych u 30 chorych. Częstość zgonu z jakiejkolwiek przyczyny, zawału serca oraz udaru wynosiła odpowiednio 0,4; 0,6 i 0,1 na każdych 100 pacjentolat obserwacji. W grupie 6 mężczyzn, którzy zgłosili stosowanie sildenafilu na miesiąc przed incydentem sercowo-naczyniowym, 2 podało jego użycie w czasie 24 godzin poprzedzających zdarzenie. Wnioski: Wyniki badania IMHS potwierdzają wcześniejsze doniesienia o współwystępowaniu zaburzeń erekcji oraz CVD i o podobnych czynnikach ryzyka tych chorób

Political apologies and the question of a ‘shared time’ in the Australian context

Although conceptually distinct, ‘ time ’ and ‘community’ are multiply intertwined within a myriad of key debates in both the social sciences and the humanities. Even so, the role of conceptions of time in social practices of inclusion and exclusion has yet to achieve the prominence of other key analytical categories such as identity and space. This article seeks to contribute to the development of this field by highlighting the importance of thinking time and community together through the lens of political apologies. Often ostensibly offered in order to re-articulate both the constitution of ‘the community’ and its future direction, official apologies are prime examples of deliberate attempts to intervene in shared understandings of political community and its temporality. Offering a detailed case study of one of these apologies, I will focus on Australian debates over the removal of indigenous children from their families, known as the Stolen Generations, and examine the temporal dimensions of the different responses offered by former prime ministers John Howard and Kevin Rudd

Implications of H.E.S.S. observations of pulsar wind nebulae

In this review paper on pulsar wind nebulae (PWN) we discuss the properties of such nebulae within the context of containment against cross-field diffusion (versus normal advection), the effect of reverse shocks on the evolution of offset ``Vela-like'' PWN, constraints on maximum particle energetics, magnetic field strength estimates based on spectral and spatial properties, and the implication of such field estimates on the composition of the wind. A significant part of the discussion is based on the High Energy Stereoscopic System ({\it H.E.S.S.} or {\it HESS}) detection of the two evolved pulsar wind nebulae Vela X (cocoon) and HESS J1825-137. In the case of Vela X (cocoon) we also review evidence of a hadronic versus a leptonic interpretation, showing that a leptonic interpretation is favored for the {\it HESS} signal. The constraints discussed in this review paper sets a general framework for the interpretation of a number of offset, filled-center nebulae seen by {\it HESS}. These sources are found along the galactic plane with galactic latitudes $|b|\sim 0$, where significant amounts of molecular gas is found. In these regions, we find that the interstellar medium is inhomogeneous, which has an effect on the morphology of supernova shock expansion. One consequence of this effect is the formation of offset pulsar wind nebulae as observed.Comment: to appear in Springer Lecture Notes on Neutron Stars and Pulsars: 40 years after their discovery, eds. W. Becke

Environmental Electrokinetics for a sustainable subsurface

International audienceSoil and groundwater are key components in the sustainable management of the subsurface environment. Source contamination is one of its main threats and is commonly addressed using established remediation techniques such as in-situ chemical oxidation (ISCO), in-situ chemical reduction (ISCR; most notably using zero-valent iron [ZVI]), enhanced in-situ bioremediation (EISB), phytoremediation, soil-washing, pump-and-treat, soil vapour extraction (SVE), thermal treatment, and excavation and disposal. Decades of field applications have shown that these techniques can successfully treat or control contaminants in higher permeability subsurface materials such as sands, but achieve only limited success at sites where low permeability soils, such as silts and clays, prevail. Electrokinetics (EK), a soil remediation technique mostly recognized in in-situ treatment of low permeability soils, has, for the last decade, been combined with more conventional techniques and can significantly enhance the performance of several of these remediation technologies, including ISCO, ISCR, EISB and phytoremediation. Herein, we discuss the use of emerging EK techniques in tandem with conventional remediation techniques, to achieve improved remediation performance. Furthermore, we highlight new EK applications that may come to play a role in the sustainable treatment of the contaminated subsurface

Topical Issues for Particle Acceleration Mechanisms in Astrophysical Shocks

Particle acceleration at plasma shocks appears to be ubiquitous in the universe, spanning systems in the heliosphere, supernova remnants, and relativistic jets in distant active galaxies and gamma-ray bursts. This review addresses some of the key issues for shock acceleration theory that require resolution in order to propel our understanding of particle energization in astrophysical environments. These include magnetic field amplification in shock ramps, the non-linear hydrodynamic interplay between thermal ions and their extremely energetic counterparts possessing ultrarelativistic energies, and the ability to inject and accelerate electrons in both non-relativistic and relativistic shocks. Recent observational developments that impact these issues are summarized. While these topics are currently being probed by astrophysicists using numerical simulations, they are also ripe for investigation in laboratory experiments, which potentially can provide valuable insights into the physics of cosmic shocks.Comment: 13 pages, no figures. Invited review, accepted for publication in Astrophysics and Space Science, as part of the HEDLA 2006 conference proceeding