1,416 research outputs found

    Conventional versus single-ladder-splitting contributions to double parton scattering production of two quarkonia, two Higgs bosons and ccˉccˉc \bar c c \bar c

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    The double parton distributions (dPDF), both conventional and those corresponding to parton splitting, are calculated and compared for different two-parton combinations. The conventional and splitting dPDFs have very similar shape in x1x_1 and x2x_2. We make a first quantitative evaluation of the single-ladder-splitting contribution to double parton scattering (DPS) production of two S- or P-wave quarkonia, two Higgs bosons and ccˉccˉc \bar c c \bar c. The ratio of the single-ladder-splitting to conventional contributions is discussed as a function of centre-of-mass energy, mass of the produced system and other kinematical variables. Using a simple model for the dependence of the conventional two-parton distribution on transverse parton separation (Gaussian and independent of xix_i and scales), we find that the 2v1 contribution is as big as the 2v2 contribution discussed in recent years in the literature. This means that the phenomenological analyses of σeff\sigma_{eff} including only the conventional DPS mechanism have to be revised including explicitly the single-ladder-splitting contributions discussed here. The differential distributions in rapidity and transverse momenta calculated for conventional and single-ladder-splitting DPS processes are however very similar which causes their experimental separation to be rather difficult, if not impossible. The direct consequence of the existence of the two components (conventional and splitting) is the energy and process dependence of the empirical parameter σeff\sigma_{eff}. This is illustrated in our paper for the considered processes.Comment: 20 pages, 11 figures, 3 table

    Is Transhumanism Heading Towards Redefinition of Human Being or Towards Utopia?

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    Transhumanism has enormous affect on temporary philosophical thought by forcing philosophers to take on many intellectual challenges generated by scientists who try to create technological solutions that enable implementation of transhuman-istic ideas. The question is whether all these ideas will be realized. The purpose of the article is to show that the ulitmate goal of transhumanism, to create posthumanistic society, is impossible to realize. The first reason is that transhumanism limits human’s understanding to the material dimension (from a theological viewpint). While this is understandable in the naturalistic paradigm, this approach is insufficient when it comes to all complexity of human being and for this reason transhumanism represents too narrow a human’s understanding to be able to implement its all assumptions. The second reason is that to enable people to become posthumans the latest technologies would have to be available to everyone and this seems impossible. If so, such a sit-uation will divide people into ordinary ones and posthumans and this could lead to conflicts that transhumanists want to avoid after all. Finally, the body-mind problem is essentially limited to emergentism, which corresponds to the naturalistic paradigm. It seems, however, that without the concept of the soul it is impossible to understand who a man is, their identity and consciousness and this is crucial for mind uploading

    Observation of thermally-induced magnetic relaxation in a magnetite grain using off-axis electron holography

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    A synthetic basalt comprising magnetic Fe3O4 grains (~ 50 nm to ~ 500 nm in diameter) is investigated using a range of complementary nano-characterisation techniques. Off-axis electron holography combined with in situ heating allowed for the visualisation of the thermally-induced magnetic relaxation of an Fe3O4 grain (~ 300 nm) from an irregular domain state into a vortex state at 550˚C, just below its Curie temperature, with the magnetic intensity of the vortex increasing on cooling

    Open charm meson production at LHC

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    We discuss charm production at the LHC. The production of single ccˉc \bar c pairs is calculated in the ktk_t-factorization approach. We use Kimber-Martin-Ryskin unintegrated gluon distributions in the proton. The hadronization is included with the help of Peterson fragmentation functions. Transverse momentum and pseudorapidity distributions of charmed mesons are presented and compared to recent results of the ALICE, LHCb and ATLAS collaborations. Furthermore we discuss production of two pairs of ccˉc \bar c within a simple formalism of double-parton scattering (DPS). Surprisingly large cross sections, comparable to single-parton scattering (SPS), are predicted for LHC energies. We discuss perspectives how to identify the double scattering contribution. We predict much larger cross section for large rapidity distance between charm quarks from different hard parton scatterings compared to single scattering.Comment: 5 pages, 4 figures, talk given by R. Maciula at the MESON2012 - 12th International Workshop on Meson Production, Properties and Interaction, 31 May - 5 June 2012, Krakow, Polan

    Homotopy Brunnian links and the κ\kappa-invariant

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    We provide an alternative proof that Koschorke's κ\kappa-invariant is injective on the set of link homotopy classes of nn-component homotopy Brunnian links BLM(n)BLM(n). The existing proof (by Koschorke \cite{Koschorke97}) is based on the Pontryagin--Thom theory of framed cobordisms, whereas ours is closer in spirit to techniques based on Habegger and Lin's string links. We frame the result in the language of Fox's torus homotopy groups and the rational homotopy Lie algebra of the configuration space Conf(n)\text{Conf}(n) of nn points in R3\mathbb{R}^3. It allows us to express the relevant Milnor's μ\mu--invariants as homotopy periods of Conf(n)\text{Conf}(n).Comment: 15 pages, 2 figures, to appear in PAM

    Admissibility of retarded diagonal systems with one-dimensional input space

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    We investigate infinite-time admissibility of a control operator BB in a Hilbert space state-delayed dynamical system setting of the form z˙(t)=Az(t)+A1z(tτ)+Bu(t)\dot{z}(t)=Az(t)+A_1 z(t-\tau)+Bu(t), where AA generates a diagonal C0C_0-semigroup, A1L(X)A_1\in\mathcal{L}(X) is also diagonal and uL2(0,;C)u\in L^2(0,\infty;\mathbb{C}). Our approach is based on the Laplace embedding between L2L^2 and the Hardy space H2(C+)H^2(\mathbb{C}_+). The results are expressed in terms of the eigenvalues of AA and A1A_1 and the sequence representing the control operator.Comment: 25 pages, 2 figure

    Interactions of the Gasotransmitters Contribute to Microvascular Tone (Dys)regulation in the Preterm Neonate

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    Background & Aims Hydrogen sulphide (H2S), nitric oxide (NO), and carbon monoxide (CO) are involved in transitional microvascular tone dysregulation in the preterm infant; however there is conflicting evidence on the interaction of these gasotransmitters, and their overall contribution to the microcirculation in newborns is not known. The aim of this study was to measure the levels of all 3 gasotransmitters, characterise their interrelationships and elucidate their combined effects on microvascular blood flow. Methods 90 preterm neonates were studied at 24h postnatal age. Microvascular studies were performed by laser Doppler. Arterial COHb levels (a measure of CO) were determined through co-oximetry. NO was measured as nitrate and nitrite in urine. H2S was measured as thiosulphate by liquid chromatography. Relationships between levels of the gasotransmitters and microvascular blood flow were assessed through partial correlation controlling for the influence of gestational age. Structural equation modelling was used to examine the combination of these effects on microvascular blood flow and derive a theoretical model of their interactions. Results No relationship was observed between NO and CO (p = 0.18, r = 0.18). A positive relationship between NO and H2S (p = 0.008, r = 0.28) and an inverse relationship between CO and H2S (p = 0.01, r = -0.33) exists. Structural equation modelling was used to examine the combination of these effects on microvascular blood flow. The model with the best fit is presented. Conclusions The relationships between NO and H2S, and CO and H2S may be of importance in the preterm newborn, particularly as NO levels in males are associated with higher H2S levels and higher microvascular blood flow and CO in females appears to convey protection against vascular dysregulation. Here we present a theoretical model of these interactions and their overall effects on microvascular flow in the preterm newborn, upon which future mechanistic studies may be based.The authors would like to acknowledge the parents of the neonates enrolled in the 2CANS study for their participation, the staff of the Kaleidoscope Neonatal Intensive Care Unit at the John Hunter Children’s Hospital, and Kimberly-Clark Australia for providing the diapers used in this stud

    Soul, mind – brain, body – what makes us the same?

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    The question whether I am the same person at different moments has brought many difficulties for a long time. The problem with identity of things through time was already known in the ancient times especially when Plutarch asked whether a ship of Theseus with exchanged elements is still the same ship as before renovation. Today, we continue these considerations asking, for instance, if things, apart from their physical parts, also have temporal parts. The number of the proposed solutions to the problem of identity and identity of persons at different times resembles wandering in a dark room with a scarf on your eyes. As a result, rather than coming closer to the light switch, we find concepts which suggest that personal identity is not important, or what is important is psychological continuity or identity which is only a matter of degree. So I can be the same person as I was in some part, in some degree. It sounds like a constitution person who likes darkness and does not need light anymore. Unfortunately, first of all, we still use successfully the concept of identity in an ordinary language, and what is more, the abandonment of the notion of personal identity results in a greater number of absurdities, so in consequence, we still do not have an idea how to treat personal identity

    AutoBiasTest: Controllable Sentence Generation for Automated and Open-Ended Social Bias Testing in Language Models

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    Social bias in Pretrained Language Models (PLMs) affects text generation and other downstream NLP tasks. Existing bias testing methods rely predominantly on manual templates or on expensive crowd-sourced data. We propose a novel AutoBiasTest method that automatically generates sentences for testing bias in PLMs, hence providing a flexible and low-cost alternative. Our approach uses another PLM for generation and controls the generation of sentences by conditioning on social group and attribute terms. We show that generated sentences are natural and similar to human-produced content in terms of word length and diversity. We illustrate that larger models used for generation produce estimates of social bias with lower variance. We find that our bias scores are well correlated with manual templates, but AutoBiasTest highlights biases not captured by these templates due to more diverse and realistic test sentences. By automating large-scale test sentence generation, we enable better estimation of underlying bias distribution
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