857 research outputs found
Factors influencing the pricing of applications in the Apple App Store: A developers\u2019 perspective
Many know how Apple Inc. owes its success in Mobile Commerce to the introduction of the new \u201cApp Store\u201d business model. This new market is characterized by the opening to third party mobile apps, which are distributed to consumers through the App Store. This paper investigates factors that might influence the pricing of applications in the Apple Mobile Application Store.
By reviewing the existing literature on the issue and analyzing the strategic features characterizing the App Store, we detect three main factors that could influence prices for apps, that is the number of developed apps, the presence of two-sided network externalities and developer\u2019s specialization. An empirical analysis on data from 68,220 apps downloaded from the Italian App Store is used to test the hypotheses. Regression results support our hypotheses. We argue, that even if the research here presented can be considered as a started analysis to the pricing problem in such markets, this work may have important managerial implication for the thousands of developers that are competing in this emerging market
Decision Procedure for Entailment of Symbolic Heaps with Arrays
This paper gives a decision procedure for the validity of en- tailment of
symbolic heaps in separation logic with Presburger arithmetic and arrays. The
correctness of the decision procedure is proved under the condition that sizes
of arrays in the succedent are not existentially bound. This condition is
independent of the condition proposed by the CADE-2017 paper by Brotherston et
al, namely, one of them does not imply the other. For improving efficiency of
the decision procedure, some techniques are also presented. The main idea of
the decision procedure is a novel translation of an entailment of symbolic
heaps into a formula in Presburger arithmetic, and to combine it with an
external SMT solver. This paper also gives experimental results by an
implementation, which shows that the decision procedure works efficiently
enough to use
Coulomb drag between two strange metals
We study the Coulomb drag between two strange-metal layers using the
Einstein-Maxwell-Dilaton model from holography. We show that the
low-temperature dependence of the drag resistivity is ,
which strongly deviates from the quadratic dependence of Fermi liquids. We also
present numerical results at room temperature, using typical parameters of the
cuprates, to provide an estimate of the magnitude of this effect for future
experiments. We find that the drag resistivity is enhanced by the plasmons
characteristic of the two-layer system.Comment: 5 pages, 3 figure
Social Dilemmas and Cooperation in Complex Networks
In this paper we extend the investigation of cooperation in some classical
evolutionary games on populations were the network of interactions among
individuals is of the scale-free type. We show that the update rule, the payoff
computation and, to some extent the timing of the operations, have a marked
influence on the transient dynamics and on the amount of cooperation that can
be established at equilibrium. We also study the dynamical behavior of the
populations and their evolutionary stability.Comment: 12 pages, 7 figures. to appea
The synergistic effect between positivity, socio-demographic factors and smoking cessation: results of a cohort study
OBJECTIVE: To examine the extent to which a effect does exist between Positivity (POS), smoking and socio-demographic factors in determining quitting smoking in subjects participating in a Group Counselling Program (GCP) for smoking cessation.METHODS: 481 subjects were contacted through a telephone call. A logistic regression analysis was carried out. Possible interaction between sociodemographic variables and POS level was tested using the Synergism Index (SI).RESULTS: For individuals with a POS level over or equal to 3.4 the odds of being smoker was significantly higher among females (OR = 1.55), who smoked at home (OR = 2.16) and lower if there had children at home (OR = 0.53). For individuals with a POS level under 3.4, the only significant variable associated with smoking was beinga female (OR = 2.58). As far concerns the synergistic effect between the variables considered does exist between POS levels and having children at home (SI=1.13) and female gender (SI = 2.8).CONCLUSIONS: The synergistic effect between POS and sociodemographic factors adds evidence on the use of POS as possible determinants of individual happiness
Gauge-gravity duality comes to the lab: evidence of momentum-dependent scaling exponents in the nodal electron self-energy of cuprate strange metals
We show that the momentum-dependent scaling exponents of the holographic
fermion self-energy of the conformal-to-AdS Gubser-Rocha model can describe
new findings from angle-resolved photoemission spectroscopy experiments on a
single layer (Pb,Bi)SrLaCuO copper-oxide. In
particular, it was recently observed, in high-precision measurements on
constant energy cuts along the nodal direction, that the spectral function
departs from the Lorentzian line shape that is expected from the
power-law-liquid model of a nodal self-energy, with an imaginary part
featureless in momentum as . By direct comparison with experimental results, we provide
evidence that this departure from either a Fermi liquid or the power-law
liquid, resulting in an asymmetry of the spectral function as a function of
momentum around the central peak, is captured at low temperature and all
dopings by a semi-holographic model that predicts a momentum-dependent scaling
exponent in the electron self-energy as , with the Fermi
momentum
Evolution of Coordination in Social Networks: A Numerical Study
Coordination games are important to explain efficient and desirable social
behavior. Here we study these games by extensive numerical simulation on
networked social structures using an evolutionary approach. We show that local
network effects may promote selection of efficient equilibria in both pure and
general coordination games and may explain social polarization. These results
are put into perspective with respect to known theoretical results. The main
insight we obtain is that clustering, and especially community structure in
social networks has a positive role in promoting socially efficient outcomes.Comment: preprint submitted to IJMP
Approximate Consistency Condition from Running Spectral Index in Slow-Roll Inflationary Models
Density perturbations generated from inflation almost always have a spectral
index n_s which runs (varies with the wavelength). We explore a running
spectral index scenario in which the scalar spectral index runs from blue (n_s
>1) on large length scales to red (n_s<1) on short length scales. Specifically,
we look for a correlation between the length scale at which n_s-1=0 and the
length scale at which tensor to scalar ratio T/S reaches a minimum for single
field slow roll inflationary models. By computing the distribution of length
scale ratios, we conclude that there indeed is a new approximate consistency
condition that is characteristic of running spectral index scenarios that run
from blue to red. Specifically, with strong running, we expect 96% of the slow
roll models to have the two length scales to be within a factor of 2, with the
length scale at which the tensor to scalar ratio reaching a minimum longer than
the wavelength at which n_s-1=0.Comment: 18 pages, 2 figure
Food safety risk analysis from the producers' perspective: prioritisation of production process stages by HACCP and TOPSIS
[EN] From the manufacturers perspective, the Hazard Analysis and Critical Control Point
(HACCP) system nowadays represents the mainly way to implement the food safety risk
management in food industries. Nevertheless, the identification and prioritization of hazards as the
outcome of the first principle of HACCP is not sufficient to identify production process stages that
more significantly and critically contribute to the consumer¿s risks. With this recognition, the
present paper proposes a Quantitative Risk Assessment (QRA) approach based on HACCP and
Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to individuate
production process phases on which implementing corrective actions to improve the consumers¿
safety. The designed methodological approach is implemented on the smoked salmon
manufacturing process of a real Sicilian industry.Certa, A.; Enea, M.; Galante, G.; Izquierdo Sebastián, J.; La Fata, CM. (2018). Food safety risk analysis from the producers' perspective: prioritisation of production process stages by HACCP and TOPSIS. International Journal of Management and Decision Making. 17(4):396-414. https://doi.org/10.1504/IJMDM.2018.095720S39641417
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