102,652 research outputs found
A search for solar dark matter with the IceCube neutrino telescope
No full textDark matter particles in the form of supersymmetric Weakly Interacting Massive Particles (WIMPs) could accumulate in the centre of the Sun because of gravitational trapping. Pair-wise annihilations of WIMPs could create standard model particles out of which neutrinos could reach the Earth. Data from the IceCube 22-string neutrino telescope have been searched for signals from dark matter annihilations in the Sun. Highly sophisticated analysis methods have been developed to discern signal neutrinos from the severe background of atmospheric particle showers. No signal has been found in a dataset of 104 days livetime taken in 2007, and an upper limit has been placed on the muon flux in the South Pole ice induced by neutrinos from the Sun, reaching down to 330 km-2y-1. The flux limit has been converted into an upper limit on the neutralino scattering cross-section, which reaches down to 2.8*10-40 cm2 for spin-dependent interactions.Four articles are appended to the thesis:I. G. Wikström for the IceCube collaboration, Proc. of the 30th ICRC,arXiv/0711.0353 [astro-ph] (2007) 135.II. A. Gross, C. Ha, C. Rott, M. Tluczykont, E. Resconi, T. DeYoung and G. Wikström for the IceCube Collaboration, Proc. of the 30th ICRC,arXiv/0711.0353 [astro-ph] (2007) 11.III. G. Wikström and J. Edsjö, JCAP 04 (2009) 009.IV. R. Abbasi et al. (IceCube collaboration), accepted for publication in Phys. Rev. Lett., arXiv/0902.2460v3 [astro-ph.CO] (2009).IceCub
On shoplifting and tax fraud: An action-theoretic analysis of crime
No full textThe article evaluates different theories of action in the area of crime research. A narrow version of rational choice theory assumes actors to choose in an instrumental, outcome-oriented way. It hypothesises that individuals weight the costs and benefits of criminal acts with subjective probabilities. In contrast, a wide version of the theory allows individuals to derive utility directly from choosing certain actions. Previous studies either do not directly test these theories or yield inconsistent results. We show that a meaningful test of these rival rational choice explanations can only be conducted if a broader view is adopted that takes into account the interplay of moral norms and instrumental incentives. Such a view can be derived from the Model of Frame Selection (Kroneberg 2005) and the Situational Action Theory of Crime Causation (Wikström 2004). Based on these theories, we analyze the willingness to engage in shoplifting and tax fraud in a sample of 2,130 adults from Dresden, Germany. In line with our theoretical expectations, we find that only respondents who do not feel bound by moral norms consider instrumental incentives. Where norms have been strongly internalised and in the absence of neutralisation techniques which legitimise norm-breaking, instrumental incentives are irrelevant.
Developmental and stress induced changes in peptide and catecholamine content of the paraaortic paraganglia
No full textThe paraaortic body (PAB) is the largest extra-adrenal paraganglion and during the perinatal period it contains a substantial amount of catecholamines (CAs). The PAB also contain peptides, whose function in the PAB is not clear. The main object of this thesis was to examine peptides in the PAB, to describe their perinatal development and response to different stimuli. The effect of tumor transition on the expression of peptides was also studied. Enkephalin-(ENK), galanin-(GAL), and neuropeptide Y-(NPY) like immunoreactivities (LI) were demonstrated in paraganglion cells as well as in adrenal medullary cells of fetal or newborn animals of three species; i.e. the rabbit, guinea-pig and pig. However, NPY-LI was not detected in these cells of the pig. In addition, coexistence of NPY/GAL, NPY/ENK, and GAL/ENK was observed within the paraganglion cells of the guinea pig. The coexistence of these peptides was also demonstrated on the subcellular level, since both GAL- and NPY-LI as well as noradrenaline (NA) and adrenaline were present in the chromaffin granule fraction after ultracentrifugation of adrenal gland homogenate on a sucrose density gradient. This strongly suggests that both peptides are stored in chromaffin granules together with CAs. A higher number of peptides is expressed in paraganglion cells, which have undergone tumor transition. In a human paraganglioma, immunoreactivities to ENK, dynorphin, somatostatin, and calbindin were the most frequently expressed peptides, whereas immunoreactivities, to GAL, NPY, and cholecystokinin were less frequent.The PAB is prominent in the fetal and newborn rabbit, why this species was chosen for the subsequent developmental studies. During the perinatal period, the highest content of GAL- and NPY-LI in the rabbit PAB was found at birth and after birth both decreased. In contrast, the content of ENK-LI showed a progressive increase with age, as did the content of the CAs. This suggests that the expression of these peptides is regulated differently. In the adrenal gland, there was a progressive increase with age in the content of all peptides as well as of the CAs. At birth, the PAB content of all these peptides was higher than in the adrenal glands. This is the first report describing the perinatal development of GAL- and NPY-LI in paraganglia and, for GAL-LI, also in the adrenal gland. The PAB content of the peptides did not change in response to asphyxia, insulin-induced hypoglycemia or reserpine, with the exception of an increased content of ENK-LI by 60 minutes of asphyxia. Also in the adrenal gland, ENK-LI tended to increase after asphyxia, whereas the adrenaline content was reduced. The only peptide for which its adrenal content was reduced by insulin-induced hypoglycemia was ENK-LI. The reduction of ENK-LI was strikingly parallel to the reduction of the CAs and was significant at all times between 1.5 and 4 hours after insulin administration (20 U/kg). Reserpine (15 mg/kg) reduced the CA content in both the PAB and adrenal glands three hours after administration, whereas no change in peptide content was observed.The present results demonstrates that there is a relatively homogenous expression of peptides in the three species studied, with the exception for NPY-LI in the pig, and that these peptides can occur in the same chromaffin cells, where they can be localized within the same chromaffin granule as the CAs. During the perinatal period they appear to be regulated differently in the PAB, where the highest amounts of GAL- and NPY-LI are found at birth, whereas the PAB content of ENK-LI increases postnatally. The possible role of these peptides in the PAB has not been established, since the PAB content of these peptides was unchanged in response to all stimuli used.List of scientific papersI. Fried G, Meister B, Wikström M, Terenius L, Goldstein M. (1989). Galanin-, neuropeptide Y- and enkephalin-like immunoreactivities in catecholamine-storing paraganglia of the fetal guinea pig and newborn pig. Cell Tissue Res. 255(3):495-504. https://pubmed.ncbi.nlm.nih.gov/2468416II. Fried G, Wikström LM, Höög A, Arver S, Cedermark B, Hamberger B, Grimelius L, Meister B (1994). Multiple neuropeptide immunoreactivities in a renin-producing human paraganglioma. Cancer. 74(1):142-51. https://pubmed.ncbi.nlm.nih.gov/7911735III. Fried G, Wikström LM, Franck J, Rökaeus Å (1991). Galanin and neuropeptide Y in chromaffin granules from the guinea-pig. Acta Physiol Scand. 142(4):487-93. https://pubmed.ncbi.nlm.nih.gov/1719746IV. Wikström LM, Rökaeus Å, Fried G (1993). Perinatal development of galanin-like immunoreactivity in chromaffin tissues of the rabbit. Regul Pept. 44(3):297-303. https://pubmed.ncbi.nlm.nih.gov/7683437V. Wikström LM, Meister B, Franck J, Fried G (1996). Changes in enkephalin and neuropeptide Y-like immunoreactivity in rabbit chromaffin tissues during perinatal development. Regul Pept. 61(1):37-44. https://pubmed.ncbi.nlm.nih.gov/8701025VI. Wikström LM, Rökaeus Å, Fried G. (1998). Effects of acute stress on the contents of catecholamines and neuropeptides in chromaffin tissues of the newborn rabbit. Regul Pept. 78(1-3):125-31. https://pubmed.ncbi.nlm.nih.gov/9879755</p
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
Water-gated mechanism of proton translocation by cytochrome c oxidase
No full textAbstractCytochrome c oxidase is essential for aerobic life as a membrane-bound energy transducer. O2 reduction at the haem a3–CuB centre consumes electrons transferred via haem a from cytochrome c outside the membrane. Protons are taken up from the inside, both to form water and to be pumped across the membrane (M.K.F. Wikström, Nature 266 (1977) 271 [1]; M. Wikström, K. Krab, M. Saraste, Cytochrome Oxidase, A Synthesis, Academic Press, London, 1981 [2]). The resulting electrochemical proton gradient drives ATP synthesis (P. Mitchell, Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation, Glynn Research, Bodmin, UK, 1966 [3]). Here we present a molecular mechanism for proton pumping coupled to oxygen reduction that is based on the unique properties of water in hydrophobic cavities. An array of water molecules conducts protons from a conserved glutamic acid, either to the Δ-propionate of haem a3 (pumping), or to haem a3–CuB (water formation). Switching between these pathways is controlled by the redox-state-dependent electric field between haem a and haem a3–CuB, which determines the water–dipole orientation, and therefore the proton transfer direction. Proton transfer via the propionate provides a gate to O2 reduction. This pumping mechanism explains the unique arrangement of the metal cofactors in the structure. It is consistent with the large body of biochemical data, and is shown to be plausible by molecular dynamics simulations
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
University education and income – does prior achievement matter?
No full textThe purpose of this study is to find out if the income premium from university entrance differs with respect to prior achievement as measured by previous grades. Using income at the age of 28 to 30, we analyze if high-achievers have larger income premiums from entering university than low-achievers in a sample of Swedish upper secondary school students. We find that income differences generally are positive, albeit larger for females than for males. It is also found that the income premium is larger for high-achievers than for low-achievers. However, especially for males, the income premium rises only marginally with prior achievement for a large part of the grade distribution, indicating that there are only small differences in the returns to university entrance for a majority of upper secondary school graduates.Premium; Predictive validity; Upper secondary GPA; Achievement; University entrance
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