10,740 research outputs found
Dopaminergic modulation of lateral amygdala neuronal activity: Differential d1 and d2 receptor effects on thalamic and cortical afferent inputs
Background: In auditory fear conditioning, the lateral nucleus of the amygdala (LA) integrates a conditioned stimulus (CS) from the auditory thalamus (MGN) and the auditory association cortex (Te3) with an aversive unconditioned stimulus. The thalamic input provides a basic version of the CS, while the cortical input provides a processed representation of the stimulus. Dopamine (DA) is released in the LA under heightened arousal during the presentation of the CS. Methods: In this study we examined how D1 or D2 receptor activation affects LA afferent-driven neuronal firing using in vivo extracellular single-unit recordings with local micro-iontophoretic drug application in anesthetized rats. LA neurons that were responsive (~50%) to electrical stimulation in either the MGN or the Te3 were tested by iontophoresis of either the D1 agonist, SKF38393, or the D2 agonist, quinpirole. Results: We found that most of the LA projection neurons exhibited either facilitatory or attenuating effects (changes in evoked probability 15% relative to baseline) on afferent input by activation of D1 or D2 receptors. In general, it required significantly higher stimulation current to evoke ~50% baseline responses to the cortical input. Activation of the D1 receptor showed no difference in modulation between the thalamic or cortical pathways. On the other hand, activation of the D2 receptor had a stronger inhibitory modulation of the cortical pathway, but a stronger excitatory modulation of the thalamic pathway. Conclusions: Our results suggest that there is a shift in balance favoring the thalamic pathway in response to DA acting via the D2 receptor.
Assentication: User Deauthentication and Lunchtime Attack Mitigation with Seated Posture Biometric
Biometric techniques are often used as an extra security factor in
authenticating human users. Numerous biometrics have been proposed and
evaluated, each with its own set of benefits and pitfalls. Static biometrics
(such as fingerprints) are geared for discrete operation, to identify users,
which typically involves some user burden. Meanwhile, behavioral biometrics
(such as keystroke dynamics) are well suited for continuous, and sometimes more
unobtrusive, operation. One important application domain for biometrics is
deauthentication, a means of quickly detecting absence of a previously
authenticated user and immediately terminating that user's active secure
sessions. Deauthentication is crucial for mitigating so called Lunchtime
Attacks, whereby an insider adversary takes over (before any inactivity timeout
kicks in) authenticated state of a careless user who walks away from her
computer. Motivated primarily by the need for an unobtrusive and continuous
biometric to support effective deauthentication, we introduce PoPa, a new
hybrid biometric based on a human user's seated posture pattern. PoPa captures
a unique combination of physiological and behavioral traits. We describe a low
cost fully functioning prototype that involves an office chair instrumented
with 16 tiny pressure sensors. We also explore (via user experiments) how PoPa
can be used in a typical workplace to provide continuous authentication (and
deauthentication) of users. We experimentally assess viability of PoPa in terms
of uniqueness by collecting and evaluating posture patterns of a cohort of
users. Results show that PoPa exhibits very low false positive, and even lower
false negative, rates. In particular, users can be identified with, on average,
91.0% accuracy. Finally, we compare pros and cons of PoPa with those of several
prominent biometric based deauthentication techniques
Building the Brazilian Academic Genealogy Tree
Along the history, many researchers provided remarkable contributions to
science, not only advancing knowledge but also in terms of mentoring new
scientists. Currently, identifying and studying the formation of researchers
over the years is a challenging task as current repositories of theses and
dissertations are cataloged in a decentralized way through many local digital
libraries. Following our previous work in which we created and analyzed a large
collection of genealogy trees extracted from NDLTD, in this paper we focus our
attention on building such trees for the Brazilian research community. For
this, we use data from the Lattes Platform, an internationally renowned
initiative from CNPq, the Brazilian National Council for Scientific and
Technological Development, for managing information about individual
researchers and research groups in Brazil
Human Action Recognition Based on Temporal Pyramid of Key Poses Using RGB-D Sensors
Human action recognition is a hot research topic in computer vision, mainly due to the high number of related applications, such as surveillance, human computer interaction, or assisted living. Low cost RGB-D sensors have been extensively used in this field. They can provide skeleton joints, which represent a compact and effective representation of the human posture. This work proposes an algorithm for human action recognition where the features are computed from skeleton joints. A sequence of skeleton features is represented as a set of key poses, from which histograms are extracted. The temporal structure of the sequence is kept using a temporal pyramid of key poses. Finally, a multi-class SVM performs the classification task. The algorithm optimization through evolutionary computation allows to reach results comparable to the state-of-the-art on the MSR Action3D dataset.This work was supported by a STSM Grant from COST Action IC1303 AAPELE - Architectures, Algorithms and Platforms for Enhanced Living Environments
Implications of sperm banking for health-related quality of life up to 1 year after cancer diagnosis.
Sperm banking is recommended for all men diagnosed with cancer where treatment is associated with risk of long-term gonadatoxicity, to offer the opportunity of fatherhood and improved quality of life. However, uptake of sperm banking is lower than expected and little is known about why men refuse. Our aims were to determine: (i) demographic and medical variables associated with decisions about banking and (ii) differences in quality of life between bankers and non-bankers at diagnosis (Time 1 (T1)) and 1 year later (Time 2 (T2))
On the Alexandrov Topology of sub-Lorentzian Manifolds
It is commonly known that in Riemannian and sub-Riemannian Geometry, the
metric tensor on a manifold defines a distance function. In Lorentzian
Geometry, instead of a distance function it provides causal relations and the
Lorentzian time-separation function. Both lead to the definition of the
Alexandrov topology, which is linked to the property of strong causality of a
space-time. We studied three possible ways to define the Alexandrov topology on
sub-Lorentzian manifolds, which usually give different topologies, but agree in
the Lorentzian case. We investigated their relationships to each other and the
manifold's original topology and their link to causality.Comment: 20 page
Non-universal minimal Z' models: present bounds and early LHC reach
We consider non-universal 'minimal' Z' models, whose additional U(1) charge
is a non-anomalous linear combination of the weak hypercharge Y, the baryon
number B and the partial lepton numbers (L_e, L_mu, L_tau), with no exotic
fermions beyond three standard families with right-handed neutrinos. We show
that the observed pattern of neutrino masses and mixing can be fully reproduced
by a gauge-invariant renormalizable Lagrangian, and flavor-changing neutral
currents in the charged lepton sector are suppressed by a GIM mechanism. We
then discuss the phenomenology of some benchmark models. The electrophilic
B-3L_e model is significantly constrained by electroweak precision tests, but
still allows to fit the hint of an excess observed by CDF in dielectrons but
not in dimuons. The muonphilic B-3L_mu model is very mildly constrained by
electroweak precision tests, so that even the very early phase of the LHC can
explore significant areas of parameter space. We also discuss the hadrophobic
L_mu-L_tau model, which has recently attracted interest in connection with some
puzzling features of cosmic ray spectra.Comment: 29 pages, 13 figure
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