1,215 research outputs found
On the estimation of time dependent lift of a European Starling during flapping
We study the role of unsteady lift in the context of flapping wings in birds'
flight. Both aerodynamicists and biologists attempt to address this subject,
yet it seems that the contribution of the unsteady lift still holds many open
questions. The current study deals with the estimation of unsteady aerodynamic
forces on a freely flying bird through analysis of wingbeat kinematics and near
wake flow measurements using time resolved particle image velocimetry. The
aerodynamic forces are obtained through unsteady thin airfoil theory and lift
calculation using the momentum equation for viscous flows. The unsteady lift is
comprised of circulatory and non-circulatory components. Both are presented
over wingbeat cycles. Using long sampling data, several wingbeat cycles have
been analyzed in order to cover the downstroke and upstroke phases. It appears
that the lift varies over the wingbeat cycle emphasizing its contribution to
the total lift and its role in power estimations. It is suggested that the
circulatory lift component cannot assumed to be negligible and should be
considered when estimating lift or power of birds in flapping motion
An efficient CDMA decoder for correlated information sources
We consider the detection of correlated information sources in the ubiquitous
Code-Division Multiple-Access (CDMA) scheme. We propose a message-passing based
scheme for detecting correlated sources directly, with no need for source
coding. The detection is done simultaneously over a block of transmitted binary
symbols (word). Simulation results are provided demonstrating a substantial
improvement in bit-error-rate in comparison with the unmodified detector and
the alternative of source compression. The robustness of the error-performance
improvement is shown under practical model settings, including wrong estimation
of the generating Markov transition matrix and finite-length spreading codes.Comment: 11 page
Gender, war and militarism: making and questioning the links
The gender dynamics of militarism have traditionally been seen as straightforward, given the cultural mythologies of warfare and the disciplining of ‘masculinity’ that occurs in the training and use of men's capacity for violence in the armed services. However, women's relation to both war and peace has been varied and complex. It is women who have often been most prominent in working for peace, although there are no necessary links between women and opposition to militarism. In addition, more women than ever are serving in many of today's armies, with feminists rather uncertain on how to relate to this phenomenon. In this article, I explore some of the complexities of applying gender analyses to militarism and peace work in sites of conflict today, looking most closely at the Israeli feminist group, New Profile, and their insistence upon the costs of the militarized nature of Israeli society. They expose the very permeable boundaries between the military and civil society, as violence seeps into the fears and practices of everyday life in Israel. I place their work in the context of broader feminist analysis offered by researchers such as Cynthia Enloe and Cynthia Cockburn, who have for decades been writing about the ‘masculinist’ postures and practices of warfare, as well as the situation of women caught up in them. Finally, I suggest that rethinking the gendered nature of warfare must also encompass the costs of war to men, whose fundamental vulnerability to psychological abuse and physical injury is often downplayed, whether in mainstream accounts of warfare or in more specific gender analysis. Feminists need to pay careful attention to masculinity and its fragmentations in addressing the topic of gender, war and militarism
Paradoxical augmented relapse in alcohol-dependent rats during deep-brain stimulation in the nucleus accumbens
Case reports indicate that deep-brain stimulation in the nucleus accumbens may
be beneficial to alcohol-dependent patients. The lack of clinical trials and
our limited knowledge of deep-brain stimulation call for translational
experiments to validate these reports. To mimic the human situation, we used a
chronic-continuous brain-stimulation paradigm targeting the nucleus accumbens
and other brain sites in alcohol-dependent rats. To determine the network
effects of deep-brain stimulation in alcohol-dependent rats, we combined
electrical stimulation of the nucleus accumbens with functional magnetic
resonance imaging (fMRI), and studied neurotransmitter levels in nucleus
accumbens-stimulated versus sham-stimulated rats. Surprisingly, we report here
that electrical stimulation of the nucleus accumbens led to augmented relapse
behavior in alcohol-dependent rats. Our associated fMRI data revealed some
activated areas, including the medial prefrontal cortex and caudate putamen.
However, when we applied stimulation to these areas, relapse behavior was not
affected, confirming that the nucleus accumbens is critical for generating
this paradoxical effect. Neurochemical analysis of the major activated brain
sites of the network revealed that the effect of stimulation may depend on
accumbal dopamine levels. This was supported by the finding that brain-
stimulation-treated rats exhibited augmented alcohol-induced dopamine release
compared with sham-stimulated animals. Our data suggest that deep-brain
stimulation in the nucleus accumbens enhances alcohol-liking probably via
augmented dopamine release and can thereby promote relapse
Processing second-order stochastic dominance models using cutting-plane representations
This is the post-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2011 Springer-VerlagSecond-order stochastic dominance (SSD) is widely recognised as an important decision criterion in portfolio selection. Unfortunately, stochastic dominance models are known to be very demanding from a computational point of view. In this paper we consider two classes of models which use SSD as a choice criterion. The first, proposed by Dentcheva and Ruszczyński (J Bank Finance 30:433–451, 2006), uses a SSD constraint, which can be expressed as integrated chance constraints (ICCs). The second, proposed by Roman et al. (Math Program, Ser B 108:541–569, 2006) uses SSD through a multi-objective formulation with CVaR objectives. Cutting plane representations and algorithms were proposed by Klein Haneveld and Van der Vlerk (Comput Manage Sci 3:245–269, 2006) for ICCs, and by Künzi-Bay and Mayer (Comput Manage Sci 3:3–27, 2006) for CVaR minimization. These concepts are taken into consideration to propose representations and solution methods for the above class of SSD based models. We describe a cutting plane based solution algorithm and outline implementation details. A computational study is presented, which demonstrates the effectiveness and the scale-up properties of the solution algorithm, as applied to the SSD model of Roman et al. (Math Program, Ser B 108:541–569, 2006).This study was funded by OTKA, Hungarian
National Fund for Scientific Research, project 47340; by Mobile Innovation Centre, Budapest University of Technology, project 2.2; Optirisk Systems, Uxbridge, UK and by BRIEF (Brunel University Research Innovation and Enterprise Fund)
Revisiting Politicide: State Annihilation in Israel/Palestine
State annihilation is a persistent concern in Israel/Palestine. While the specter of Israel’s destruction increasingly haunts Israeli public political debates, the actual materialization of Palestinian statehood seems to be permanently suspended, caught in an ever-protracted process of state-building. The current paper claims that to understand the unfolding of the discursive formations, as well as the spatial dimensions of conflict and control in Israel/Palestine, we should explicate the workings of the processes of politicide. Politicide, in this regard, denotes the eradication of the political existence of a group and sabotaging the turning of a community of people into a polity. This analysis suggests that the insistence that the State of Israel is under threat of extinction should be understood as a speech act, a performative reiteration, which allows for the securitization of Israeli rule in the occupied Palestinian territory, a securitization which then serves to rationalize the ongoing concrete politicide of the Palestinians. Elaborating on the concept of politicide, and diverging from defining it solely through the use of brute violence, this examination suggests that what is often overlooked in discussions of politicide are the seemingly more benign means of its implementation, the micro-power mechanisms of spatial control, prohibitions and regulations
Being asked to tell an unpleasant truth about another person activates anterior insula and medial prefrontal cortex
"Truth" has been used as a baseline condition in several functional magnetic resonance imaging (fMRI) studies of deception. However, like deception, telling the truth is an inherently social construct, which requires consideration of another person's mental state, a phenomenon known as Theory of Mind. Using a novel ecological paradigm, we examined blood oxygenation level dependent (BOLD) responses during social and simple truth telling. Participants (n = 27) were randomly divided into two competing teams. Post-competition, each participant was scanned while evaluating performances from in-group and out-group members. Participants were asked to be honest and were told that their evaluations would be made public. We found increased BOLD responses in the medial prefrontal cortex, bilateral anterior insula and precuneus when participants were asked to tell social truths compared to simple truths about another person. At the behavioral level, participants were slower at responding to social compared to simple questions about another person. These findings suggest that telling the truth is a nuanced cognitive operation that is dependent on the degree of mentalizing. Importantly, we show that the cortical regions engaged by truth telling show a distinct pattern when the task requires social reasoning
Generalized Near Horizon Extreme Binary Black Hole Geometry
We present a new vacuum solution of Einstein’s equations describing the near horizon region of two neutral, extreme (zero-temperature), corotating, nonidentical Kerr black holes. The metric is stationary, asymptotically near horizon extremal Kerr (NHEK), and contains a localized massless strut along the symmetry axis between the black holes. In the deep infrared, it flows to two separate throats which we call “pierced-NHEK” geometries: each throat is NHEK pierced by a conical singularity. We find that in spite of the presence of the strut for the pierced-NHEK geometries the isometry group SL(2,R)×U(1) is restored. We find the physical parameters and entropy
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