42,517 research outputs found

    Labor Problems of the Transportation Industry

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    The age related prevalence of aggression and self-injury in persons with an intellectual disability: A review

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    The aim of this study was to analyse statistically published data regarding the age related prevalence of aggression and self-injury in persons with intellectual disability. Studies including prevalence data for aggression and/or self-injury broken down by age band were identified and relative risk analyses conducted to generate indices of age related change. Despite conflicting results, the analysis conducted on included studies considered to be the most methodologically robust indicated that the relative risk of self-injury, and to a lesser extent aggression, increased with age until mid-adulthood, with some indication of a curvilinear relationship for self-injury. These conclusions have implications for the understanding of the development of different forms of challenging behavior and the importance of early intervention strategies

    Antony van Leeuwenhoek: Creation “Magnified” Through His Magnificent Microscopes

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    Although van Leeuwenhoek was not the inventor of the microscope, he advanced it more than anyone else for seeing living things. Antony van Leeuwenhoek1 (Fig. 1) found great joy in God’s smallest creatures. He first discovered protozoans in his youth. The Dutch haberdasher retained a child-like joy of discovery from his youth until his death at age 90. He lived to see tiny microbes though his homemade microscopes. He loved to grind and focus a new lens in order to see the unseen world. Leeuwenhoek spent countless hours grinding tiny lenses and looking through them. This Christian lay biologist even used candlelight to see specimens at night. For Leeuwenhoek, the amazing diversity of tiny life forms revealed under his homemade microscopes glorified God as much as looking at stars through a telescope. Leeuwenhoek was born in South Holland in 1632. As a young adult, he became a cloth merchant (also called a draper, or haberdasher). In 1668, he started his biological study as a hobby after seeing beautiful microscopic pictures while making a visit to London. After years of careful study, Leeuwenhoek (Fig. 2) made the microscope famous. In his lifetime, he became the father of microbiology and opened mankind to the world of microorganisms

    Constraints on neutrino and dark radiation interactions using cosmological observations

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    Observations of the cosmic microwave background (CMB) and large-scale structure (LSS) provide a unique opportunity to explore the fundamental properties of the constituents that compose the cosmic dark radiation background (CDRB), of which the three standard neutrinos are thought to be the dominant component. We report on the first constraint to the CDRB rest-frame sound speed, ceff^2, using the most recent CMB and LSS data. Additionally, we report improved constraints to the CDRB viscosity parameter, cvis^2. For a non-interacting species, these parameters both equal 1/3. Using current data we find that a standard CDRB, composed entirely of three non-interacting neutrino species, is ruled out at the 99% confidence level (C.L.) with ceff^2 = 0.30 +0.027 -0.026 and cvis^2 = 0.44 +0.27 -0.21 (95% C.L.). We also discuss how constraints to these parameters from current and future observations (such as the Planck satellite) allow us to explore the fundamental properties of any anomalous radiative energy density beyond the standard three neutrinos.Comment: 6 pages, 3 figures, comments welcome; v2: updated with SPT data, corrected minor typos; v3: version accepted for publication in PR

    Note on new interesting baryon channels to measure the photon polarization in b -> s gamma

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    At LHC a large number of b-flavored baryons will be produced. In this note we propose new baryon modes to determine the photon helicity of the penguin transition bsγb \to s \gamma. The decay ΛbΛγ\Lambda_b \to \Lambda \gamma has the drawback that the Λ\Lambda, being neutral and long-lived, will escape detection most of the time. To overcome this difficulty, transitions of the type ΛbΛγ\Lambda_b \to \Lambda^{*} \gamma have been proposed, where Λ\Lambda^{*} denotes an excited state decaying strongly within the detector into the clean mode pKp K^-. The doublet Ξb\Xi_b, that decays weakly, has a number of good features. The charged baryon Ξb\Xi_b^- will decay into the mode Ξγ\Xi^- \gamma, where the ground state hyperon Ξ\Xi^-, although it will decay most of the time outside the detector, can be detected because it is charged. We consider also the decay of Ξb\Xi_b into Ξγ\Xi^{*} \gamma, where a higher mass state Ξ\Xi^{*} can decay strongly within the detector. We point out that the initial transverse polarization of Ξb\Xi_b has to be known in all cases. To determine this parameter through the transition ΞbJ/Ψ Ξ\Xi_b \to J/\Psi\ \Xi, we distinguish between different cases, and underline that in some situations one needs {\it theoretical input} on the asymmetry parameter αΞb\alpha_{\Xi_b} of the primary decay. {\it A fortiori} the same considerations apply to the case of the Λb\Lambda_b

    Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: Effect of helium

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    Prominences are partially ionized, magnetized plasmas embedded in the solar corona. Damped oscillations and propagating waves are commonly observed. These oscillations have been interpreted in terms of magnetohydrodynamic (MHD) waves. Ion-neutral collisions and non-adiabatic effects (radiation losses and thermal conduction) have been proposed as damping mechanisms. We study the effect of the presence of helium on the time damping of non-adiabatic MHD waves in a plasma composed by electrons, protons, neutral hydrogen, neutral helium (He I), and singly ionized helium (He II) in the single-fluid approximation. The dispersion relation of linear non-adiabatic MHD waves in a homogeneous, unbounded, and partially ionized prominence medium is derived. The period and the damping time of Alfven, slow, fast, and thermal waves are computed. A parametric study of the ratio of the damping time to the period with respect to the helium abundance is performed. The efficiency of ion-neutral collisions as well as thermal conduction is increased by the presence of helium. However, if realistic abundances of helium in prominences (~10%) are considered, this effect has a minor influence on the wave damping. The presence of helium can be safely neglected in studies of MHD waves in partially ionized prominence plasmas.Comment: Research note submitted in A&

    Robert Koch, Creation, and the Specificity of Germs

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    Microbiology is dominated by evolution today. Just look at any text, journal article, or the topics presented at professional scientific meetings. Darwin is dominant. Microbiology is dominated by evolution today. Just look at any text, journal article, or the topics presented at professional scientific meetings. Darwin is dominant. Many argue that “nothing in biology makes sense except in the light of evolution” (Dobzhansky 1973). But it was not always this way. In fact, a review of the major founders of microbiology has shown that they were creationists.1 We would argue that a better idea thanevolution and one of much more practical importance is the germ theory of disease, originally put forth primarily by non-Darwinian biologists (Gillen and Oliver 2009). In our previous article (Gillen and Oliver 2009), we documented these and many other creation and Christian contributions to germ theory. But only recently has it become known that another important microbiology founder, Robert Koch (Fig. 1) and his co-workers were Linnaean creationists in their classification.2 This is due, in part, to additional works of Robert Koch that were translated from German to English. The year 2010 marks the 100thanniversary of his death (died: May 27, 1910). Although Koch and other German microbiologists were fairly secular in their thinking, their acceptance of Darwinian evolution was minimal
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