5,125 research outputs found
Alas, the dark matter structures were not that trivial
The radial density profile of dark matter structures has been observed to
have an almost universal behaviour in numerical simulations, however, the
physical reason for this behaviour remains unclear. It has previously been
shown that if the pseudo phase-space density, rho/sigma_d^epsilon, is a
beautifully simple power-law in radius, with the "golden values" epsilon=3 and
d=r (i.e., the phase-space density is only dependent on the radial component of
the velocity dispersion), then one can analytically derive the radial variation
of the mass profile, dispersion profile etc. That would imply, if correct, that
we just have to explain why rho/sigma^3_r ~r^{-alpha}, and then we would
understand everything about equilibrated DM structures. Here we use a set of
simulated galaxies and clusters of galaxies to demonstrate that there are no
such golden values, but that each structure instead has its own set of values.
Considering the same structure at different redshifts shows no evolution of the
phase-space parameters towards fixed points. There is also no clear connection
between the halo virialized mass and these parameters. This implies that we
still do not understand the origin of the profiles of dark matter structures.Comment: 4 pages, 3 figures, accepted for publication in ApJ
Predictions for the First Parker Solar Probe Encounter
We examine Alfv\'en Wave Solar atmosphere Model (AWSoM) predictions of the
first Parker Solar Probe (PSP) encounter. We focus on the 12-day closest
approach centered on the 1st perihelion. AWSoM (van der Holst et al., 2014)
allows us to interpret the PSP data in the context of coronal heating via
Alfv\'en wave turbulence. The coronal heating and acceleration is addressed via
outward-propagating low-frequency Alfv\'en waves that are partially reflected
by Alfv\'en speed gradients. The nonlinear interaction of these
counter-propagating waves results in a turbulent energy cascade. To apportion
the wave dissipation to the electron and anisotropic proton temperatures, we
employ the results of the theories of linear wave damping and nonlinear
stochastic heating as described by Chandran et al. (2011). We find that during
the first encounter, PSP was in close proximity to the heliospheric current
sheet (HCS) and in the slow wind. PSP crossed the HCS two times, namely at
2018/11/03 UT 01:02 and 2018/11/08 UT 19:09 with perihelion occuring on the
south of side of the HCS. We predict the plasma state along the PSP trajectory,
which shows a dominant proton parallel temperature causing the plasma to be
firehose unstable.Comment: 16 pages, 5 figures; accepted for publication in the Astrophysical
Journal Letter
EXPLAINING SATISFACTION IN DOUBLE DEVIATION SCENARIOS: THE EFFECTS OF ANGER AND DISTRIBUTIVE JUSTICE
Research has shown that more than half of attempted recovery efforts only reinforce dissatisfaction, producing a ‘double deviation’ effect. Surprisingly, these double deviation effects have received little attention in service marketing literature. Yet no study has specifically investigated which are the main determinants of the formation of customer satisfaction judgments in double deviation contexts. To fill this gap, we develop and empirically test a model based on the existing service recovery literature. Specifically, we focus on two theoretical frameworks: social justice theory and theories of emotion. We examine the effect of anger with service recovery on satisfaction with service recovery, as well as the role of distributive justice on the elicitation of the specific emotion of anger with service recovery and satisfaction with service recovery. Results support the model and highlight the important role of specific recovery-related emotions in double deviation contexts. Implications for practice and future research are discussed. La investigación previa ha mostrado que más de la mitad de los esfuerzos de recuperación sólo refuerzan la insatisfacción, produciendo un efecto de desviación doble. Sorprendentemente, estos efectos de desviación doble han recibido muy poca atención en la literatura de marketing de servicios. Hasta la fecha, ningún trabajo ha investigado empíricamente cuáles son los principales determinantes en la formación de los juicios de satisfacción en contextos de desviación doble. Para cubrir este hueco, desarrollamos y analizamos empíricamente un modelo basado en la literatura de recuperación de servicios existente. Específicamente, nos basamos en dos esquemas conceptuales: la teoría de la justicia social y las teorías sobre emociones. Examinamos el efecto del enfado con la recuperación del servicio en la satisfacción con la recuperación del servicio, así como el papel de la justicia distributiva como activador de emociones específicas de enfado y como antecedente de la satisfacción con la recuperación del servicio. Los resultados confirman el modelo propuesto y ponen de manifiesto el importante papel de las emociones específicas relacionadas con la recuperación en contextos de desviación doble. Finalmente, se discuten las implicaciones de gestión y las líneas futuras de investigación.enfado con la recuperación del servicio, justicia distributiva, satisfacción con la recuperación del servicio, desviación doble, industria bancaria anger with service recovery, distributive justice, satisfaction with service recovery, double deviation, banking industry
Bad Times, Good Credit
Banks' limited knowledge about borrowers' creditworthiness constitutes an important friction in credit markets. Is this friction deeper in recessions, thereby contributing to cyclical swings in credit, or is the friction reduced, as bad times reveal information about firm quality? We test these alternative hypotheses using internal ratings data from a large Swedish cross-border bank and credit scores from a credit bureau. The ability to classify corporate borrowers by credit quality is greater during bad times and worse during good times. Soft and hard information measures both display countercyclical patterns. Our results suggest that information frictions in corporate credit markets are intrinsically countercyclical and not due to cyclical variation in monitoring effort. The presence of countercyclical information frictions provides a rationale for countercyclical provisions or capital in banks to smooth credit cycles
Stringent Phenomenological Investigation into Heterotic String Optical Unification
For the weakly coupled heterotic string (WCHS) there is a well-known factor
of twenty conflict between the minimum string coupling unification scale,
Lambda_H ~5x10^(17) GeV, and the projected MSSM unification scale, Lambda_U ~
2.5x10^(16) GeV, assuming an intermediate scale desert (ISD). Renormalization
effects of intermediate scale MSSM-charged exotics (ISME) (endemic to
quasi-realistic string models) can resolve this issue, pushing the MSSM scale
up to the string scale. However, for a generic string model, this implies that
the projected Lambda_U unification under ISD is accidental. If the true
unification scale is 5.0x10^(17) GeV, is it possible that illusionary
unification at 2.5x10^(17) GeV in the ISD scenario is not accidental? If it is
not, then under what conditions would the assumption of ISME in a WCHS model
imply apparent unification at Lambda_U when ISD is falsely assumed? Geidt's
"optical unification" suggests that Lambda_U is not accidental, by offering a
mechanism whereby a generic MSSM scale Lambda_U < Lambda_H is guaranteed. A
WCHS model was constructed that offers the possibility of optical unification,
depending on the availability of anomaly-cancelling flat directions meeting
certain requirements. This paper reports on the systematic investigation of the
optical unification properties of the set of stringent flat directions of this
model. Stringent flat directions can be guaranteed to be F-flat to all finite
order (or to at least a given finite order consistent with electroweak scale
supersymmetry breaking) and can be viewed as the likely roots of more general
flat directions. Analysis of the phenomenology of stringent flat directions
gives an indication of the remaining optical unification phenomenology that
must be garnered by flat directions developed from them.Comment: standard latex, 18 pages of tex
- …