4,696 research outputs found
The bigravity black hole and its thermodynamics
We argue that the Isham-Storey exact solution to bigravity does not describe
black holes because the horizon is a singular surface. However, this is not a
generic property of bigravity, but a property of a particular potential. More
general potentials do accept regular black holes. For regular black holes, we
compute the total energy and thermodynamical parameters. Phase transitions
occur for certain critical temperatures. We also find a novel region on phase
space describing up to 4 allowed states for a given temperature.Comment: 14 pages, 9 figure
Music as evil: deviance and metaculture in classical music
This paper aims to apply the sociology of deviance and the concept of metaculture
to the sociology of high-art and music. Examples of classical music criticisms over
time are presented and discussed. Music critics have engaged in metaculture and
norm promotion by labeling certain composers or styles of music as negatively
deviant in a number of ways. Composers or styles of classical music have been
labeled as not music, not worthy of being considered the future of music, a threat
to culture, politically unacceptable, evil, and even criminal. Critics have linked
composers they are critical of with other deviant categories, and ethnocentrism,
racism, and other biases play a role in criticsâ attempts to engage in norm
promotion and affect the public temper. As society changes, musical norms and
therefore deviant labels concerning music also change. Maverick composers push
musical ideas forward, and those music critics who resist these changes are unable
to successfully promote their dated, more traditional norms. Implications of the
findings for the sociology of deviance and the sociology of music are discussed
CORONAcredits: Program Innovations to Aid Student Completion of Disrupted Fieldword Abroad Due to the COVID-19 Pandemic
The Spring 2020 semester provided unique challenges for global experiences of all types to meet the intended learning objectives for students due to the COVID-19 pandemic disruption. This was especially true for experiential language and cultural immersion programs where engineering students were in the midst of their fieldwork experience abroad. The COVID-19 disruption presented unique challenges to recreate language and cultural understanding within international engineering fieldwork experiences in the US. This article outlines the response to the COVID-19 pandemic by the Interdisciplinary Global Programs (IGP) at Northern Arizona University (NAU). The IGP response was an innovative interdisciplinary and cross-institutional collaboration between NAUâs international office and faculty across three academic colleges to assist students in completing the interdisciplinary engineering, language, and cultural understanding objectives, absent direct immersion abroad. IGP developed âCORONAcreditsâ focused on exploration of the worldwide impact of COVID-19 to help students complete their fieldwork experience. The CORONAcredits engaged students in exploration of their personal experiences within the greater context of how different cultures handled the worldwide pandemic, enabling students to continue to build their global understanding from the US. Students analyzed the worldwide response of the unfolding pandemic across cultures and engaged in a mix of assignments that included discussion contributions where students shared their personal experiences abroad. CORONAcredits exposed students to a diversity of approaches to highlight cultural differences and deepen understanding of global, economic, environmental, and societal contexts present in the way that each student navigated the pandemic both domestically and abroad. Findings highlight the importance of flexibility and an interdisciplinary design, guiding students in their intercultural reflections, and incorporating new materials into module design. CORONAcredits can provide a âbreak in case of emergencyâ navigation plan that can be employed when unforeseen circumstances arise in engineering study abroad contexts
Communication: UV photoionization of cytosine catalyzed by Ag+
The photo-induced damages of DNA in interaction with metal cations, which are found in various environments, still remain to be characterized. In this paper, we show how the complexation of a DNA base (cytosine (Cyt)) with a metal cation (Ag+) changes its electronic properties. By means of UV photofragment spectroscopy of cold ions, it was found that the photoexcitation of the CytAg+ complex at low energy (315-282) nm efficiently leads to ionized cytosine (Cyt+) as the single product. This occurs through a charge transfer state in which an electron from the p orbital of Cyt is promoted to Ag+, as confirmed by ab initio calculations at the TD-DFT/B3LYP and RI-ADC(2) theory level using the SV(P) basis set. The low ionization energy of Cyt in the presence of Ag+ could have important implications as point mutation of DNA upon sunlight exposition.Fil: Taccone, MartĂn Ignacio. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en FĂsico-quĂmica de CĂłrdoba. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Instituto de Investigaciones en FĂsico-quĂmica de CĂłrdoba; ArgentinaFil: FĂ©raud, Geraldine. Aix Marseille UniversitĂ©. Physique des Interactions Ioniques et MolĂ©culaires; FranciaFil: Berdakin, Matias. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en FĂsico-quĂmica de CĂłrdoba. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Instituto de Investigaciones en FĂsico-quĂmica de CĂłrdoba; ArgentinaFil: Dedonder Lardeux, Claude. Aix Marseille UniversitĂ©. Physique des Interactions Ioniques et MolĂ©culaires; FranciaFil: Jouvet, Christophe. Physique des Interactions Ioniques et MolĂ©culaires; FranciaFil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en FĂsico-quĂmica de CĂłrdoba. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Instituto de Investigaciones en FĂsico-quĂmica de CĂłrdoba; Argentin
Evidence for a Very Large-Scale Fractal Structure in the Universe from Cobe Measurements
In this work, we analyse the temperature fluctuations of the cosmic microwave
background radiation observed by COBE and show that the distribution can be
fitted by a fractal distribution with a fractal dimension .
This value is in close agreement with the fractal dimension obtained by Coleman
and Pietronero (1992) and Luo and Schramm (1992) from galaxy-galaxy and
cluster-cluster correlations up to . The fact that the
observed temperature fluctuations correspond to scales much larger than and are signatures of the primordial density fluctuations at the
recombination layer suggests that the structure of the matter at the early
universe was already fractal and thus non-homogeneous on those scales. This
result may have important consequences for the theoretical framework that
describes the universe.Comment: 11 pages, postscript file, 2 figures available upon request. To
appear in ApJ Letter
On the Design of Cryptographic Primitives
The main objective of this work is twofold. On the one hand, it gives a brief
overview of the area of two-party cryptographic protocols. On the other hand,
it proposes new schemes and guidelines for improving the practice of robust
protocol design. In order to achieve such a double goal, a tour through the
descriptions of the two main cryptographic primitives is carried out. Within
this survey, some of the most representative algorithms based on the Theory of
Finite Fields are provided and new general schemes and specific algorithms
based on Graph Theory are proposed
PP2A/B56 and GSK3/Ras suppress PKB activity during Dictyostelium chemotaxis
We have previously shown that the Dictyostelium protein phosphatase 2A regulatory subunit B56, encoded by psrA, modulates Dictyostelium cell differentiation through negatively affecting glycogen synthase kinase 3 (GSK3) function. Our follow-up research uncovered that B56 preferentially associated with GDP forms of RasC and RasD, but not with RasG in vitro, and psrAâ cells displayed inefficient activation of multiple Ras species, decreased random motility, and inefficient chemotaxis toward cAMP and folic acid gradient. Surprisingly, psrAâ cells displayed aberrantly high basal and poststimulus phosphorylation of Dictyostelium protein kinase B (PKB) kinase family member PKBR1 and PKB substrates. Expression of constitutively active Ras mutants or inhibition of GSK3 in psrAâ cells increased activities of both PKBR1 and PKBA, but only the PKBR1 activity was increased in wild-type cells under the equivalent conditions, indicating that either B56- or GSK3-mediated suppressive mechanism is sufficient to maintain low PKBA activity, but both mechanisms are necessary for suppressing PKBR1. Finally, cells lacking RasD or RasC displayed normal PKBR1 regulation under GSK3-inhibiting conditions, indicating that RasC or RasD proteins are essential for GSK3-mediated PKBR1 inhibition. In summary, B56 constitutes inhibitory circuits for PKBA and PKBR1 and thus heavily affects Dictyostelium chemotaxis
Magnetic Field Effects on the Structure and Evolution of Overdense Radiatively Cooling Jets
We investigate the effect of magnetic fields on the propagation dynamics and
morphology of overdense, radiatively cooling, supermagnetosonic jets, with the
help of fully three-dimensional SPMHD simulations. Evaluated for a set of
parameters which are mainly suitable for protostellar jets (with density ratios
between the jet and the ambient medium 3-10, and ambient Mach number ~ 24),
these simulations are also compared with baseline non-magnetic and adiabatic
calculations. We find that, after amplification by compression and
re-orientation in nonparallel shocks at the working surface, the magnetic field
that is carried backward with the shocked gas into the cocoon improves the jet
collimation relative to the purely hydrodynamic (HD) systems. Low-amplitude,
approximately equally spaced internal shocks (which are absent in the HD
systems) are produced by MHD K-H reflection pinch modes. The longitudinal field
geometry also excites non-axisymmetric helical modes which cause some beam
wiggling. The strength and amount of these modes are, however, reduced (by ~
twice) in the presence of radiative cooling relative to the adiabatic cases.
Besides, a large density ratio between the jet and the ambient medium also
reduces, in general, the number of the internal shocks. As a consequence, the
weakness of the induced internal shocks makes it doubtful that the magnetic
pinches could produce by themselves the bright knots observed in the overdense,
radiatively cooling protostellar jets.Comment: To appear in ApJ; 36 pages + 16 (gif) figures. PostScript files of
figures are available at http://www.iagusp.usp.br/preprints/preprint.htm
- âŠ