2,177 research outputs found
Perceptual representations mediate effects of stimulus properties on liking for music.
Perceptual pleasure and its concomitant hedonic value play an essential role in everyday life, motivating behavior and thus influencing how individuals choose to spend their time and resources. However, how pleasure arises from perception of sensory information remains relatively poorly understood. In particular, research has neglected the question of how perceptual representations mediate the relationships between stimulus properties and liking (e.g., stimulus symmetry can only affect liking if it is perceived). The present research addresses this gap for the first time, analyzing perceptual and liking ratings of 96 nonmusicians (power of 0.99) and finding that perceptual representations mediate effects of feature-based and information-based stimulus properties on liking for a novel set of melodies varying in balance, contour, symmetry, or complexity. Moreover, variability due to individual differences and stimuli accounts for most of the variance in liking. These results have broad implications for psychological research on sensory valuation, advocating a more explicit account of random variability and the mediating role of perceptual representations of stimulus properties
Risk-Driven Design Processes: Balancing Efficiency with Resilience in Product Design
Current design methods and approaches focus on increasing the efficiency of the product design system by, for example, eliminating waste and focusing on value creation. However, continuing failures in the development of complex, large scale products and systems point towards weaknesses in the existing approaches. We argue that product development organizations are hindered by the many uncertainties that are inherent in the process. Common management heuristics ignore uncertainty and thus overly simplify the decision making process. Creating transparency regarding uncertainties and the associated risks (i.e. effect of uncertainties on design objectives) is not seen as an explicit priority. Consequently organizations are unable to balance risk and return in their development choices. Product development processes do not emphasize reduction of risks, particularly those risks that are apparent early in the process. In addition, the resilience of the PD system, i.e. its ability to deliver on-target results under uncertainty, is not deliberately designed to match the level of residual uncertainty. This chapter introduces the notion of Risk-Driven Design and its four principles of 1. Creating transparency regarding design risks; 2. Risk-driven decision making; 3. Minimizing uncertainty; and 4. Creating resilience.Massachusetts Institute of Technology. Lean Advancement InitiativeCenter for Clean Water and Clean Energy at MIT and KFUP
Asymmetric WIMP dark matter
In existing dark matter models with global symmetries the relic abundance of
dark matter is either equal to that of anti-dark matter (thermal WIMP), or
vastly larger, with essentially no remaining anti-dark matter (asymmetric dark
matter). By exploring the consequences of a primordial asymmetry on the coupled
dark matter and anti-dark matter Boltzmann equations we find large regions of
parameter space that interpolate between these two extremes. Interestingly,
this new asymmetric WIMP framework can accommodate a wide range of dark matter
masses and annihilation cross sections. The present-day dark matter population
is typically asymmetric, but only weakly so, such that indirect signals of dark
matter annihilation are not completely suppressed. We apply our results to
existing models, noting that upcoming direct detection experiments will
constrain a large region of the relevant parameter space.Comment: 32 pages, 6 figures, updated references, updated XENON100 bounds,
typo in figure caption correcte
Aidnogenesis via Leptogenesis and Dark Sphalerons
We discuss aidnogenesis, the generation of a dark matter asymmetry via new
sphaleron processes associated to an extra non-abelian gauge symmetry common to
both the visible and the dark sectors. Such a theory can naturally produce an
abundance of asymmetric dark matter which is of the same size as the lepton and
baryon asymmetries, as suggested by the similar sizes of the observed baryonic
and dark matter energy content, and provide a definite prediction for the mass
of the dark matter particle. We discuss in detail a minimal realization in
which the Standard Model is only extended by dark matter fermions which form
"dark baryons" through an SU(3) interaction, and a (broken) horizontal symmetry
that induces the new sphalerons. The dark matter mass is predicted to be
approximately 6 GeV, close to the region favored by DAMA and CoGeNT.
Furthermore, a remnant of the horizontal symmetry should be broken at a lower
scale and can also explain the Tevatron dimuon anomaly.Comment: Minor changes, discussion of present constraints expanded. 16 pages,
2 eps figures, REVTeX
Closing in on Asymmetric Dark Matter I: Model independent limits for interactions with quarks
It is argued that experimental constraints on theories of asymmetric dark
matter (ADM) almost certainly require that the DM be part of a richer hidden
sector of interacting states of comparable mass or lighter. A general requisite
of models of ADM is that the vast majority of the symmetric component of the DM
number density must be removed in order to explain the observed relationship
via the DM asymmetry. Demanding the efficient
annihilation of the symmetric component leads to a tension with experimental
limits if the annihilation is directly to Standard Model (SM) degrees of
freedom. A comprehensive effective operator analysis of the model independent
constraints on ADM from direct detection experiments and LHC monojet searches
is presented. Notably, the limits obtained essentially exclude models of ADM
with mass 1GeV 100GeV annihilating to SM quarks via
heavy mediator states. This motivates the study of portal interactions between
the dark and SM sectors mediated by light states. Resonances and threshold
effects involving the new light states are shown to be important for
determining the exclusion limits.Comment: 18+6 pages, 18 figures. v2: version accepted for publicatio
Firms' investment under financial constraints: a Euro area investigation
In this paper we describe a model of optimal investment of various types of financially constrained firms. We show that the resulting relationship between internal funds and investment is non-monotonic. In particular, the magnitude of the cash flow sensitivity of the investment is lower for firms with credit rationing compared to firms that are able to obtained short-term external financing. The inverse relationship is driven by the leverage multiplier effect. A positive cash flow shock increases the short-term borrowing capacity of the firm, which in turn has a positive effect on investment and firm's growth. Moreover, the leverage multiplier effect is the highest for firms relying on short-term credits and it is lower for firms that are able to obtain long-term financing. Analysing a large euro area data set we find strong empirical support for our theoretical predictions. The results also help to explain some contrasting findings in the financial constraints literature
Separation of Oligosaccharides from Lotus Seeds via Medium-pressure Liquid Chromatography Coupled with ELSD and DAD
peer-reviewedLotus seeds were identified by the Ministry of Public Health of China as both food and medicine. One general function of lotus seeds is to improve intestinal health. However, to date, studies evaluating the relationship between bioactive compounds in lotus seeds and the physiological activity of the intestine are limited. In the present study, by using medium pressure liquid chromatography coupled with evaporative light-scattering detector and diode-array detector, five oligosaccharides were isolated and their structures were further characterized by electrospray ionization-mass spectrometry and gas chromatography-mass spectrometry. In vitro testing determined that LOS3-1 and LOS4 elicited relatively good proliferative effects on Lactobacillus delbrueckii subsp. bulgaricus. These results indicated a structure-function relationship between the physiological activity of oligosaccharides in lotus seeds and the number of probiotics applied, thus providing room for improvement of this particular feature. Intestinal probiotics may potentially become a new effective drug target for the regulation of immunity
Electroweak Baryogenesis and Dark Matter with an approximate R-symmetry
It is well known that R-symmetric models dramatically alleviate the SUSY
flavor and CP problems. We study particular modifications of existing
R-symmetric models which share the solution to the above problems, and have
interesting consequences for electroweak baryogenesis and the Dark Matter (DM)
content of the universe. In particular, we find that it is naturally possible
to have a strongly first-order electroweak phase transition while
simultaneously relaxing the tension with EDM experiments. The R-symmetry (and
its small breaking) implies that the gauginos (and the neutralino LSP) are
pseudo-Dirac fermions, which is relevant for both baryogenesis and DM. The
singlet superpartner of the U(1)_Y pseudo-Dirac gaugino plays a prominent role
in making the electroweak phase transition strongly first-order. The
pseudo-Dirac nature of the LSP allows it to behave similarly to a Dirac
particle during freeze-out, but like a Majorana particle for annihilation today
and in scattering against nuclei, thus being consistent with current
constraints. Assuming a standard cosmology, it is possible to simultaneously
have a strongly first-order phase transition conducive to baryogenesis and have
the LSP provide the full DM relic abundance, in part of the allowed parameter
space. However, other possibilities for DM also exist, which are discussed. It
is expected that upcoming direct DM searches as well as neutrino signals from
DM annihilation in the Sun will be sensitive to this class of models.
Interesting collider and Gravity-wave signals are also briefly discussed.Comment: 50 pages, 10 figure
Light dark matter and dark force at colliders
Light Dark Matter, GeV, with sizable direct detection rate is an
interesting and less explored scenario. Collider searches can be very powerful,
such as through the channel in which a pair of dark matter particle are
produced in association with a jet. It is a generic possibility that the
mediator of the interaction between DM and the nucleus will also be accessible
at the Tevatron and the LHC. Therefore, collider search of the mediator can
provide a more comprehensive probe of the dark matter and its interactions. In
this article, to demonstrate the complementarity of these two approaches, we
focus on the possibility of the mediator being a new gauge boson, which
is probably the simplest model which allows a large direct detection cross
section for a light dark matter candidate. We combine searches in the
monojet+MET channel and dijet resonance search for the mediator. We find that
for the mass of between 250 GeV and 4 TeV, resonance searches at the
colliders provide stronger constraints on this model than the monojet+MET
searches.Comment: 23 pages and 14 figure
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