12,910 research outputs found
Dynamics of the entanglement spectrum in spin chains
We study the dynamics of the entanglement spectrum, that is the time
evolution of the eigenvalues of the reduced density matrices after a
bipartition of a one-dimensional spin chain. Starting from the ground state of
an initial Hamiltonian, the state of the system is evolved in time with a new
Hamiltonian. We consider both instantaneous and quasi adiabatic quenches of the
system Hamiltonian across a quantum phase transition. We analyse the Ising
model that can be exactly solved and the XXZ for which we employ the
time-dependent density matrix renormalisation group algorithm. Our results show
once more a connection between the Schmidt gap, i.e. the difference of the two
largest eigenvalues of the reduced density matrix and order parameters, in this
case the spontaneous magnetisation.Comment: 16 pages, 8 figures, comments are welcome! Version published in JSTAT
special issue on "Quantum Entanglement In Condensed Matter Physics
Digging deep the oil world: corporate liability and environmental justice strategies
The impacts provoked by the expanding oil industry encompass environmental destruction, health impacts and violations of human rights. The increasing contamination jeopardizes safe conditions of life and destroys means of livelihood of vulnerable communities and of those relying on healthy ecosystems. Local communities, feeling that they are simply sacrificed to the oil industry, see themselves involved in social conflict. They are experiencing forms of environmental discrimination and might even face criminalisation of the protest when they stand up to defend their rights promoting the chilly effect on others who need and want to defend themselves and the environment. In fact, the number of lawsuits demanding justice for environmental, social, economical and cultural damages provoked by oil companies are increasing as well as their media visibility. Yet most outcomes are not satisfactory in tackling impacted communities claims for justice. This paper describes the most recent trends regarding oil corporations’ responsibilities and use of procedural justice by civil society through the review of emblematic legal cases
Italian translation and cross cultural comparison with the Childhood Attachment and Relational Trauma Screen (CARTS)
Background: The Childhood Attachment and Relational Trauma Screen (CARTS) is a computer-administered survey designed to assess retrospectively the socio-ecological context in which instances of child abuse may have occurred. To date, studies supporting the validity
of the CARTS have only been undertaken in English-speaking North American populations.
Validation projects in other countries and cross-cultural comparisons are therefore warranted.
Objective: Develop and preliminarily evaluate the psychometric properties of an Italian version of the CARTS on college students and compare such observations to data acquired from Canadian students.
Method: Seventy-nine undergraduate students from the University of Padua (Italy) completed an Italian translation of the CARTS as well as measures of childhood experiences, mental health and attachment, responses to which were compared to those obtained in 288 Canadian students who completed the CARTS in English.
Results: Internal consistency and convergent validity with the Childhood Trauma Questionnaire and Parental Bonding Instrument were found to be acceptable for the Italian translation. Within the Italian sample, correlation analyses suggested that CARTS Mother ratings referring to attachment and abuse were associated with romantic attachment, whereas CARTS Father ratings were significantly correlated to PTSD symptoms and other symptoms of psychopathology-distress. Significant differences between Italian and Canadian students across the relationship types for the CARTS abuse and attachment scales were found, indicating that Italian students rated their mothers and fathers as simultaneously less abusive, but also less as a source of secure attachment.
Conclusions: The results of this preliminary study seem to suggest convergent validity of the Italian CARTS and the association between childhood attachment-related experiences and romantic attachment. Cultural variations were identified between Canadian and Italian
students in both attachment and abuse scales. Future studies to investigate cross-cultural variations in the relational context of childhood abuse and in order to boost Italian CARTS psychometric features are warranted
Methamphetamine: The Effect On The Child From Womb, Birth And Beyond
Globally the use of methamphetamine surpasses that of heroin and cocaine combined. As a drug that facilitates weight loss and provides the user with increased energy, it is particularly appealing to women. This raises concerns about its use by pregnant women. This poster highlights what is known about the effects of methamphetamine by pregnant women on the unborn child, and on the long term consequences for the children of these women
A quantum computational semantics for epistemic logical operators. Part I: epistemic structures
Some critical open problems of epistemic logics can be investigated in the framework
of a quantum computational approach. The basic idea is to interpret sentences like
“Alice knows that Bob does not understand that π is irrational” as pieces of quantum information
(generally represented by density operators of convenient Hilbert spaces). Logical
epistemic operators (to understand, to know. . .) are dealt with as (generally irreversible)
quantum operations, which are, in a sense, similar to measurement-procedures. This approach
permits us to model some characteristic epistemic processes, that concern both human
and artificial intelligence. For instance, the operation of “memorizing and retrieving
information” can be formally represented, in this framework, by using a quantum teleportation
phenomenon
Gravitational wave generation from bubble collisions in first-order phase transitions: an analytic approach
Gravitational wave production from bubble collisions was calculated in the
early nineties using numerical simulations. In this paper, we present an
alternative analytic estimate, relying on a different treatment of
stochasticity. In our approach, we provide a model for the bubble velocity
power spectrum, suitable for both detonations and deflagrations. From this, we
derive the anisotropic stress and analytically solve the gravitational wave
equation. We provide analytical formulae for the peak frequency and the shape
of the spectrum which we compare with numerical estimates. In contrast to the
previous analysis, we do not work in the envelope approximation. This paper
focuses on a particular source of gravitational waves from phase transitions.
In a companion article, we will add together the different sources of
gravitational wave signals from phase transitions: bubble collisions,
turbulence and magnetic fields and discuss the prospects for probing the
electroweak phase transition at LISA.Comment: 48 pages, 14 figures. v2 (PRD version): calculation refined; plots
redone starting from Fig. 4. Factor 2 in GW energy spectrum corrected. Main
conclusions unchanged. v3: Note added at the end of paper to comment on the
new results of 0901.166
Impact of spatially constrained sampling of temporal contact networks on the evaluation of the epidemic risk
The ability to directly record human face-to-face interactions increasingly
enables the development of detailed data-driven models for the spread of
directly transmitted infectious diseases at the scale of individuals. Complete
coverage of the contacts occurring in a population is however generally
unattainable, due for instance to limited participation rates or experimental
constraints in spatial coverage. Here, we study the impact of spatially
constrained sampling on our ability to estimate the epidemic risk in a
population using such detailed data-driven models. The epidemic risk is
quantified by the epidemic threshold of the
susceptible-infectious-recovered-susceptible model for the propagation of
communicable diseases, i.e. the critical value of disease transmissibility
above which the disease turns endemic. We verify for both synthetic and
empirical data of human interactions that the use of incomplete data sets due
to spatial sampling leads to the underestimation of the epidemic risk. The bias
is however smaller than the one obtained by uniformly sampling the same
fraction of contacts: it depends nonlinearly on the fraction of contacts that
are recorded and becomes negligible if this fraction is large enough. Moreover,
it depends on the interplay between the timescales of population and spreading
dynamics.Comment: 21 pages, 7 figure
Entanglement detection in hybrid optomechanical systems
We study a device formed by a Bose Einstein condensate (BEC) coupled to the
field of a cavity with a moving end-mirror and find a working point such that
the mirror-light entanglement is reproduced by the BEC-light quantum
correlations. This provides an experimentally viable tool for inferring
mirror-light entanglement with only a limited set of assumptions. We prove the
existence of tripartite entanglement in the hybrid device, persisting up to
temperatures of a few milli-Kelvin, and discuss a scheme to detect it.Comment: 6 pages, 7 figures, published versio
- …