An Energy-conscious Transport Protocol for Multi-hop Wireless Networks

We present a transport protocol whose goal is to reduce power consumption without compromising delivery requirements of applications. To meet its goal of energy efficiency, our transport protocol (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgements and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within a recently developed ultra low-power multi-hop wireless network system, extensive simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network.Defense Advanced Research Projects Agency (NBCHC050053

Modelling human factors in perceptual multimedia quality: On the role of personality and culture

Perception of multimedia quality is shaped by a rich interplay between system, context, and human factors. While system and context factors are widely researched, few studies in this area consider human factors as sources of systematic variance. This paper presents an analysis on the influence of personality (Five-Factor Model) and cultural traits (Hofstede Model) on the perception of multimedia quality. A set of 144 video sequences (from 12 short movie excerpts) were rated by 114 participants from a cross-cultural population, producing 1232 ratings. On this data, three models are compared: a baseline model that only considers system factors; an extended model that includes personality and culture as human factors; and an optimistic model in which each participant is modeled as a random effect. An analysis shows that personality and cultural traits represent 9.3% of the variance attributable to human factors while human factors overall predict an equal or higher proportion of variance compared to system factors. In addition, the quality-enjoyment correlation varied across the movie excerpts. This suggests that human factors play an important role in perceptual multimedia quality, but further research to explore moderation effects and a broader range of human factors is warranted

The Other Natural Two Higgs Doublet Model

We characterize models where electroweak symmetry breaking is driven by two light Higgs doublets arising as pseudo-Nambu-Goldstone bosons of new dynamics above the weak scale. They represent the simplest natural two Higgs doublet alternative to supersymmetry. We construct their low-energy effective Lagrangian making only few specific assumptions about the strong sector. These concern their global symmetries, their patterns of spontaneous breaking and the sources of explicit breaking. In particular we assume that all the explicit breaking is associated with the couplings of the strong sector to the Standard Model fields, that is gauge and (proto)-Yukawa interactions. Under those assumptions the scalar potential is determined at lowest order by very few free parameters associated to the top sector. Another crucial property of our scenarios is the presence of a discrete symmetry, in addition to custodial SO(4), that controls the $T$-parameter. That can either be simple CP or a $Z_2$ that distinguishes the two Higgs doublets. Among various possibilities we study in detail models based on SO(6)/SO(4)$\times$ SO(2), focussing on their predictions for the structure of the scalar spectrum and the deviations of their couplings from those of a generic renormalizable two Higgs doublet model.Comment: 54 page

Gaugino mass in AdS space

We study supersymmetric QED in AdS4 with massless matter. At 1-loop the ultra-violet regulator of the theory generates a contribution to the gaugino mass that is naively inconsistent with unbroken supersymmetry. We show that this effect, known in flat space as anomaly mediated supersymmetry breaking, is required to cancel an infra-red contribution arising from the boundary conditions in AdS space, which necessarily break chiral symmetry. We also discuss an analogous UV/IR cancellation that is independent of supersymmetry.Comment: 20 pages, 1 figur

Anderson localization of ballooning modes, quantum chaos and the stability of compact quasiaxially symmetric stellarators

The radially local magnetohydrodynamic(MHD) ballooning stability of a compact, quasiaxially symmetric stellarator (QAS), is examined just above the ballooning beta limit with a method that can lead to estimates of global stability. Here MHDstability is analyzed through the calculation and examination of the ballooning modeeigenvalue isosurfaces in the 3-space (s,α,θk); s is the edge normalized toroidal flux, α is the field linevariable, and θk is the perpendicular wave vector or ballooning parameter. Broken symmetry, i.e., deviations from axisymmetry, in the stellarator magnetic field geometry causes localization of the ballooning mode eigenfunction, and gives rise to new types of nonsymmetric eigenvalue isosurfaces in both the stable and unstable spectrum. For eigenvalues far above the marginal point, isosurfaces are topologically spherical, indicative of strong “quantum chaos.” The complexity of QAS marginal isosurfaces suggests that finite Larmor radius stabilization estimates will be difficult and that fully three-dimensional, high-nMHD computations are required to predict the beta limit.Research supported by U.S. DOE Contract No. DEAC02-76CH0373. John Canik held a U.S. DOE National Undergraduate Fellowship at Princeton Plasma Physics Laboratory, during the summer of 2000

Supersymmetry phenomenology beyond the MSSM after 5/fb of LHC data

We briefly review the status of motivated beyond-the-MSSM phenomenology in the light of the LHC searches to date. In particular, we discuss the conceptual consequences of the exclusion bounds, of the hint for a Higgs boson at about 125 GeV, and of interpreting the excess of direct CP violation in the charm sector as a signal of New Physics. We try to go into the various topics in a compact way while providing a relatively rich list of references, with particular attention to the most recent developments.Comment: 20 pages + refs. v2: minor modifications, published versio

Axion-Higgs Unification

In theories with no fundamental scalars, one gauge group can become strong at a large scale Lambda and spontaneously break a global symmetry, producing the Higgs and the axion as composite pseudo-Nambu-Goldstone bosons. We show how KSVZ and DFSZ axion models can be naturally realised. The assumption Lambda around 10^{11} GeV is phenomenologically favoured because: a) The axion solves the QCD theta problem and provides the observed DM abundance; b) The observed Higgs mass is generated via RGE effects from a small Higgs quartic coupling at the compositeness scale, provided that the Higgs mass term is fine-tuned to be of electroweak size; c) Lepton, quark as well as neutrino masses can be obtained from four-fermion operators at the compositeness scale. d) The extra fermions can unify the gauge couplings.Comment: 19 pages. Refs. added and eq. 3.6 fixe

Auswirkungen von depressiven Störungen auf die kognitive Leistungsfähigkeit und die Fahrkompetenz

Depressive Störungen können neben den Erstrangsymptomen „depressive Stimmung“, „Verlust von Interesse oder Freude“ und „erhöhte Ermüdbarkeit“ mit einer großen Anzahl an weiteren Symptomen einhergehen. Folgende kognitive Defizite sind kennzeichnend: Störungen der kognitiven Flexibilität, des Arbeitsgedächtnisses, des freien Abrufs von Gedächtnisinhalten, der geteilten Aufmerksamkeit und von Teilbereichen der selektiven Aufmerksamkeit. Die Bundesanstalt für Straßenwesen (BASt) und wissenschaftliche Forschungsarbeiten konnten eine Reihe an Leistungs- und Persönlichkeitsmaßen identifizieren, welche eine ausreichende psychische Leistungsfähigkeit im Straßenverkehr gewährleisten sollen. Obwohl sich die hierbei hervorgehobenen kognitiven Leistungsfunktionen nahezu umfassend mit den Defizitbereichen bei depressiven Störungen überschneiden und bisher kein rein linearer Zusammenhang zwischen der Schwere der depressiven Symptomatik und dem Ausprägungsgrad kognitiver Beeinträchtigungen gefunden werden konnte, besagt die aktuelle Rechtslage, dass lediglich bei schweren depressiven Episoden die Fahreignung anzuzweifeln sei. Ziele der vorliegenden Arbeit: Zum einen sollte überprüft werden, ob sich die in der Literatur berichteten Unterschiede zwischen depressiven Patienten und gesunden Vergleichspersonen in der kognitiven Leistungsfähigkeit, bei der Fahrkompetenz, bei der Selbstbeschreibung und im Risikoverhalten finden lassen. Zum anderen wurde zu bestimmen versucht, welche dieser Maße hauptverantwortlich für Unterschiede in der Fahrkompetenz sind. Methode: Hierzu bearbeitete eine Gruppe stationär-psychiatrischer Patienten mit unipolarer Depression jeweils unmittelbar nach stationärer Aufnahme und bei Entlassung (neuro-) psychologische Testverfahren. Darüber hinaus wurde zeitnah zu den Testungen eine praktische Fahrerprobung in einem Fahrschulauto durchgeführt. Ein dritter Schwerpunkt der vorliegenden Arbeit bestand darin, die wissenschaftliche Güte dieser praktischen Fahrverhaltensprobe zu überprüfen. Alle Untersuchungen wurden parallel auch mit einer Kontrollgruppe körperlich und psychisch gesunder Probanden durchgeführt. Ergebnisse: Die Fahrverhaltensprobe konnte strenge wissenschaftliche und verkehrspsychologische Anforderungen erfüllen. Es zeigte sich, dass sich die Patienten neben dem Ausmaß ihrer subjektiven und objektiven Depressivität, auch in einer Reihe von Leistungs- und Persönlichkeitsmaßen von den Kontrollpersonen unterschieden. Es ließen sich sowohl einzelne wie auch Kombinationen an Variablen identifizieren, die bereits für die eher geringe Stichprobengröße der Studie die Fahrkompetenz der Probanden mit einem zufrieden stellenden Maß an Sensitivität und Spezifität vorhersagten. Diskussion: Mit dieser Arbeit wurde erstmals bei Patienten mit mittelschwerer Depression sowohl anhand neuropsychologischer Testverfahren als auch mit Hilfe einer praktischen Fahrverhaltensprobe untersucht, welche Auswirkungen deren Erkrankung auf die Fahrkompetenz hat. Vorangegangene Studien konnten aber bereits die Annahme der BASt, dass nur bei schweren depressiven Episoden die Fahreignung fraglich sei, deutlich in Frage stellen. Die vorliegende Studie stützt die bisherigen Erkenntnisse und zeigt zusätzlich auf, dass auch bei einer praktischen Fahrverhaltensprobe, die den Anforderungen der BASt entspricht, nicht von vergleichbaren Leistungen bei depressiven Patienten und gesunden Kontrollen auszugehen ist. Die geringe Stichprobengröße lässt allerdings eine Generalisierung der Ergebnisse nicht zu. Weitere Forschungsarbeit in dieser Richtung ist erforderlich

Spin and a Running Radius in RS1

We develop a renormalization group formalism for the compactified Randall-Sundrum scenario wherein the extra-dimensional radius serves as the scaling parameter. Couplings on the hidden brane scale as we move within local effective field theories with varying size of the warped extra dimension. We consider this RG approach applied to U(1) gauge theories and gravity. We use this method to derive a low energy effective theory.Comment: 18 pages, minor changes, references adde

Bounding wide composite vector resonances at the LHC

In composite Higgs models (CHMs), electroweak precision data generically push colourless composite vector resonances to a regime where they dominantly decay into pairs of light top partners. This greatly attenuates their traces in canonical collider searches, tailored for narrow resonances promptly decaying into Standard Model final states. By reinterpreting the CMS same-sign dilepton (SS2$\ell$) analysis at the Large Hadron Collider (LHC), originally designed to search for top partners with electric charge $5/3$, we demonstrate its significant coverage over this kinematical regime. We also show the reach of the 13 TeV run of the LHC, with various integrated luminosity options, for a possible upgrade of the SS2$\ell$ search. The top sector of CHMs is found to be more fine-tuned in the presence of colourless composite resonances in the few TeV range.Comment: 9 pages, 5 figures. Minor corrections for publication in JHE