38 research outputs found
Where to stand when playing darts?
This paper analyzes the question of where one should stand when playing
darts. If one stands at distance and aims at , then
the dart (modelled by a random vector in ) hits a random
point given by . Next, given a payoff function , one considers and asks if this is decreasing in ; i.e., whether it is
better to stand closer rather than farther from the target. Perhaps
surprisingly, this is not always the case and understanding when this does or
does not occur is the purpose of this paper.
We show that if has a so-called selfdecomposable distribution, then it is
always better to stand closer for any payoff function. This class includes all
stable distributions as well as many more.
On the other hand, if the payoff function is , then it is always
better to stand closer if and only if the characteristic function
is decreasing on . We will then show that if there are at least two
point masses, then it is not always better to stand closer using . If
there is a single point mass, one can find a different payoff function to
obtain this phenomenon.
Another large class of darts for which there are bounded continuous
payoff functions for which it is not always better to stand closer are
distributions with compact support. This will be obtained by using the fact
that the Fourier transform of such distributions has a zero in the complex
plane. This argument will work whenever there is a complex zero of the Fourier
transform.
Finally, we analyze if the property of it being better to stand closer is
closed under convolution and/or limits.Comment: 31 page
Exploring Consumers’ Attitudes of Smart TV Related Privacy Risks
A number of privacy risks are inherent in the Smart TV ecosystem. It is likely that many consumers are unaware of these privacy risks. Alternatively, they might be aware but consider the privacy risks acceptable. In order to explore this, we carried out an online survey with 200 participants to determine whether consumers were aware of Smart TV related privacy risks. The responses revealed a meagre level of awareness. We also explored consumers’ attitudes towards specific Smart TV related privacy risks.
We isolated a number of factors that influenced rankings and used these to develop awareness-raising messages. We tested these messages in an online survey with 155 participants. The main finding was that participants were generally unwilling to disconnect their Smart TVs from the Internet because they valued the Smart TV’s Internet functionality more than their privacy. We subsequently evaluated the awareness-raising messages in a second survey with 169 participants, framing the question differently. We asked participants to choose between five different Smart TV Internet connection options, two of which retained functionality but entailed expending time and/or effort to preserve privacy
Why doesn’t Jane protect her privacy?
End-to-end encryption has been heralded by privacy and security researchers as an effective defence against dragnet surveillance, but there is no evidence of widespread end-user uptake. We argue that the non-adoption of end-to-end encryption might not be entirely due to usability issues identified by Whitten and Tygar in their seminal paper “Why Johnny Can’t Encrypt”. Our investigation revealed a number of fundamental issues such as incomplete threat models, misaligned incentives, and a general absence of understanding of the email architecture. From our data and related research literature we found evidence of a number of potential explanations for the low uptake of end-to-end encryption. This suggests that merely increasing the availability and usability of encryption functionality in email clients will not automatically encourage increased deployment by email users. We shall have to focus, first, on building comprehensive end-user mental models related to email, and email security. We conclude by suggesting directions for future research
Enterocolitis necrotizante en recién nacidos ingresados en el Servicio de Neonatología del Hospital Escuela "Carlos Roberto Huembes" en el período comprendido de Enero 2011 a Diciembre 2013
La enterocolitis necrotizante en el recién nacido presenta un amplio espectro de manifestaciones clínicas, caracterizándose principalmente por la tríada de distensión abdominal, sangramiento gastrointestinal y neumatosis intestinal. A pesar del avance en el cuidado intensivo neonatal, persiste como una enfermedad grave, que afecta habitualmente al recién nacido pretérmino, especialmente de muy bajo peso
Minimal matchings of point processes
Suppose that red and blue points form independent homogeneous Poisson processes of equal intensity in R-d. For a positive (respectively, negative) parameter gamma we consider red-blue matchings that locally minimize (respectively, maximize) the sum of gamma th powers of the edge lengths, subject to locally minimizing the number of unmatched points. The parameter can be viewed as a measure of fairness. The limit gamma -> -infinity is equivalent to Gale-Shapley stable matching. We also consider limits as gamma approaches 0, 1-, 1+ and infinity. We focus on dimension d = 1. We prove that almost surely no such matching has unmatched points. (This question is open for higher d). For each gamma < 1 we establish that there is almost surely a unique such matching, and that it can be expressed as a finitary factor of the points. Moreover, its typical edge length has finite rth moment if and only if r < 1 /2. In contrast, for gamma = 1 there are uncountably many matchings, while for gamma > 1 there are countably many, but it is impossible to choose one in a translation-invariant way. We obtain existence results in higher dimensions (covering many but not all cases). We address analogous questions for one-colour matchings also
Importance of motives, self-efficacy, social support and satisfaction with travel for behavior change during travel intervention programs
The present field study investigates the reduction of car use through a voluntary travelbehavior intervention program that provides participants with temporary free publictransportation. Three factors – self-efficacy, social support and satisfaction – have previ-ously been shown to be important for behavior change during physical activity interven-tion programs. In travel behavior interventions, however, these factors have often beenstudied individually and less is known about their combined effects on travel behaviorchange. Furthermore, while motives for participating in travel behavior interventions havebeen frequently studied within travel behavior interventions research, there is a lack ofstudies investigating the influence of motives on travel behavior change. To better under-stand the importance of different motives as well as the importance of self-efficacy, socialsupport, and satisfaction with travel on behavior change, a series of surveys were admin-istered to 181 participants before, during, and after their participation in a voluntary travelbehavior intervention. The results show that greater self-efficacy and social support duringthe intervention led to greater travel behavior change. These results indicate that in orderto gain better results from travel behavior interventions, individuals should be helped toincrease their travel-related self-efficacy, and significant others should be involved to pro-vide social support. We discuss possible ways of accomplishing this