Dijet asymmetry at the Large Hadron Collider

The MARTINI numerical simulation allows for direct comparison of theoretical model calculations and the latest results for dijet asymmetry from the ATLAS and CMS collaborations. In this paper, partons are simulated as undergoing radiative and collisional processes throughout the evolution of central lead-lead collisions at the Large Hadron Collider. Using hydrodynamical background evolution determined by a simulation which fits well with the data on charged particle multiplicities from ALICE and a value of $\alpha_s\approx 0.25-0.3$, the dijet asymmetry is found to be consistent with partonic energy loss in a hot, strongly-interacting medium.Comment: 8 pages, 3 figures. For version 2: ATLAS' latest analysis is included, with some comments and minor changes of wordin

Bound states and magnetic field-induced valley splitting in gate-tunable graphene quantum dots

The magnetic field dependence of energy levels in gapped single- and bilayer graphene quantum dots (QDs) defined by electrostatic gates is studied analytically in terms of the Dirac equation. Due to the absence of sharp edges in these types of QDs, the valley degree of freedom is a good quantum number. We show that its degeneracy is efficiently and controllably broken by a magnetic field applied perpendicular to the graphene plane. This opens up a feasible route to create well-defined and well controlled spin- and valley-qubits in graphene QDs. We also point out the similarities and differences in the spectrum between single- and bilayer graphene quantum dots. Striking in the case of bilayer graphene is the anomalous bulk Landau level (LL) that crosses the gap which results in crossings of QD states with this bulk LL at large magnetic fields in stark contrast to the single-layer case where this LL is absent. The tunability of the gap in the bilayer case allows us to observe different regimes of level spacings directly related to the formation of a pronounced ``Mexican hat'' in the bulk bandstructure. We discuss the applicability of such QDs to control and measure the valley isospin and their potential use for hosting and controlling spin qubits.Comment: 12 pages, 10 figure

Der Zusammenhang von Umweltbewusstsein und Umweltverhalten:Eine explorative Studie zu einem Kernproblem der Umweltsoziologie am Beispiel von Wissensarbeiter*innen

Die Umweltsoziologie befasst sich seit ihrer Entstehung mit dem Zusammenhang von Umweltbewusstsein und Umweltverhalten. Sind sich die Menschen der Krise des gesellschaftlichen Naturverhältnisses bewusst? Und vor allem: Gelingt es ihnen, ihr Umweltbewusstsein und ihren Veränderungswillen in ein anderes Umweltverhalten zu übersetzen? Im vorliegenden Buch werden diese klassischen Fragen der Umweltbewusstseins-Umweltverhaltens-Forschung aufgegriffen und die theoretischen Modelle des Problemfeldes anhand der empirischen Ergebnisse einer Untersuchung zum Umweltbewusstsein und Umweltverhalten von Wissensarbeiter*innen diskutiert und weiterentwickelt. <br

Towards the Standard Model spectrum from elliptic Calabi-Yau

We show that it is possible to construct supersymmetric three-generation models of Standard Model gauge group in the framework of non-simply-connected elliptically fibered Calabi-Yau, without section but with a bi-section. The fibrations on a cover Calabi-Yau, where the model has 6 generations of SU(5) and the bundle is given via the spectral cover description, use a different description of the elliptic fibre which leads to more than one global section. We present two examples of a possible cover Calabi-Yau with a free involution: one is a fibre product of rational elliptic surfaces $dP_9$; another example is an elliptic fibration over a Hirzebruch surface. There we give the necessary amount of chiral matter by turning on in the bundles a further parameter, related to singularities of the fibration and the branching of the spectral cover.Comment: 31 pages, 1 eps-figure, reference added, bundle parameters for dP9 model change

Hybrid Inflation Exit through Tunneling

For hybrid inflationary potentials, we derive the tunneling rate from field configurations along the flat direction towards the waterfall regime. This process competes with the classically rolling evolution of the scalar fields and needs to be strongly subdominant for phenomenologically viable models. Tunneling may exclude models with a mass scale below 10^12 GeV, but can be suppressed by small values of the coupling constants. We find that tunneling is negligible for those models, which do not require fine tuning in order to cancel radiative corrections, in particular for GUT-scale SUSY inflation. In contrast, electroweak scale hybrid inflation is not viable, unless the inflaton-waterfall field coupling is smaller than approximately 10^-11.Comment: 17 pages, 2 figure

An experimental and theoretical guide to strongly interacting Rydberg gases

We review experimental and theoretical tools to excite, study and understand strongly interacting Rydberg gases. The focus lies on the excitation of dense ultracold atomic samples close to, or within quantum degeneracy, to high lying Rydberg states. The major part is dedicated to highly excited S-states of Rubidium, which feature an isotropic van-der-Waals potential. Nevertheless, the setup and the methods presented are also applicable to other atomic species used in the field of laser cooling and atom trapping.Comment: 23 pages, 22 figures, tutoria

Critical behavior of the Random-Field Ising Magnet with long range correlated disorder

We study the correlated-disorder driven zero-temperature phase transition of the Random-Field Ising Magnet using exact numerical ground-state calculations for cubic lattices. We consider correlations of the quenched disorder decaying proportional to r^a, where r is the distance between two lattice sites and a<0. To obtain exact ground states, we use a well established mapping to the graph-theoretical maximum-flow problem, which allows us to study large system sizes of more than two million spins. We use finite-size scaling analyses for values a={-1,-2,-3,-7} to calculate the critical point and the critical exponents characterizing the behavior of the specific heat, magnetization, susceptibility and of the correlation length close to the critical point. We find basically the same critical behavior as for the RFIM with delta-correlated disorder, except for the finite-size exponent of the susceptibility and for the case a=-1, where the results are also compatible with a phase transition at infinitesimal disorder strength. A summary of this work can be found at the papercore database at www.papercore.org.Comment: 9 pages, 13 figure

Allergen immunotherapy in Iceland 1977-2006

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn Skoða/Opna(view/open)INTRODUCTION: The prevelance of allery and asthma has increased rapidly over the last 3 decades and is now estimated that 25-30% of population in Western industrialized countries show symptoms of allergy or asthma. The aim of this study was to reveal the success of allergen immunotherapy (AIT) in Landspitali from 1977-2006. MATERIAL AND METHODS: During the study period a total number of 289 individuals underwent immunotherapy in outpatient clinic of allergy and asthma in Landspítali. A total number of 169 individuals were contacted, of whom 128 (76%) accepted to participate in the study. The evaluation was based on medical records, standardized questionnaire and skin-prick tests. RESULTS: Patients were evaluated on the average of 20 years after finishing treatment. 118 (92%) patients were desensitized to grass pollen, to birch pollen (30%), cat dander (30%) and dust mite (28%). At the time of the study 67% reported to be asymptomatic or with greatly improved allergy symptoms. Males had better response to AIT than women (p=0.04). Participants with positive family history of allergy and/or asthma in first degree relatives also reported better response to AIT (p=0.02). Furthermore, AIT to grass pollen and dust mite seemed to be more effective than AIT to cat dander and birch (p=0.04). AIT was also shown to reduce asthma. CONCLUSION: AIT for 3-5 years provides significant beneficial effect of allergy and asthma symptoms in patients who undergo such therapy. Finally, it s findings support the notion that AIT may reduce the risk of new allergic manifestations.Inngangur: Tíðni ofnæmis hefur farið ört vaxandi á síðastliðnum þremur áratugum og er nú talið að allt að 25-30% íbúa iðnríkjanna sýni einkenni ofnæmis í einhverri mynd. Tilgangur rannsóknarinnar var að varpa ljósi á árangur afnæmismeðferðar yfir 30 ára tímabil á Íslandi. Efniviður og aðferðir: Á rannsóknartímabilinu frá 1977 til 2006 hófu 289 einstaklingar afnæmismeðferð á göngudeild astma- og ofnæmissjúkdóma á Landspítalanum. Haft var samband við 169 manns og samþykktu 128 (76%) þátttöku í rannsókninni. Upplýsinga var aflað með stöðluðum spurningalista og aflestri sjúkraskráa. Sjúklingar voru að auki húðprófaðir. Niðurstöður:Að meðaltali voru 20 ár liðin frá lokum afnæmismeðferðar þegar árangur hennar var metinn í þessari rannsókn. Alls voru 118 (92%) einstaklingar afnæmdir gegn vallarfoxgrasi, 39 (30%) gegn birki, 38 (30%) gegn köttum og 36 (28%) gegn rykmaurum. Við endurmat sjúklinga reynust 86 (67%) vera einkennalausir eða betri. Karlmenn svöruðu að jafnaði meðferð betur en konur (p=0,04). Ættarsaga um ofnæmi eða astma í fyrstu gráðu ættingjum hafði jákvæð áhrif á árangur afnæmismeðferðar (p=0,02). Að auki var sýnt fram á að afnæmismeðferð gegn vallarfoxgrasi og rykmaurum skilaði betri árangri en afnæming gegn birki og köttum (p=0,04). Meðferðin dró úr líkum á astma síðar meir. Ályktanir:Afnæmismeðferð sem stendur yfir í 3-5 ár að meðaltali dregur almennt úr einkennum ofnæmissjúklinga til lengri tíma. Þá má leiða líkur að því að afnæmismeðferð minnki líkur á þróun nýs ofnæmis