6,265 research outputs found
Projective Loop Quantum Gravity I. State Space
Instead of formulating the state space of a quantum field theory over one big
Hilbert space, it has been proposed by Kijowski to describe quantum states as
projective families of density matrices over a collection of smaller, simpler
Hilbert spaces. Beside the physical motivations for this approach, it could
help designing a quantum state space holding the states we need. In
[Oko{\l}\'ow 2013, arXiv:1304.6330] the description of a theory of Abelian
connections within this framework was developed, an important insight being to
use building blocks labeled by combinations of edges and surfaces. The present
work generalizes this construction to an arbitrary gauge group G (in
particular, G is neither assumed to be Abelian nor compact). This involves
refining the definition of the label set, as well as deriving explicit formulas
to relate the Hilbert spaces attached to different labels.
If the gauge group happens to be compact, we also have at our disposal the
well-established Ashtekar-Lewandowski Hilbert space, which is defined as an
inductive limit using building blocks labeled by edges only. We then show that
the quantum state space presented here can be thought as a natural extension of
the space of density matrices over this Hilbert space. In addition, it is
manifest from the classical counterparts of both formalisms that the projective
approach allows for a more balanced treatment of the holonomy and flux
variables, so it might pave the way for the development of more satisfactory
coherent states.Comment: 81 pages, many figure
Doing public participatory archaeology with “difficult” conflict heritage : Experiences from Finnish Lapland and the Scottish Highlands
Public participatory archaeology can take many forms, and there is no ‘one size fits all’ approach to engaging with communities and non-professional enthusiasts. Similarly, not all archaeological heritage is the same, and some comes with the label of ‘difficult’, ‘contested’ or ‘dark’ heritage. Particularly, in this article I explore how archaeological heritage that is connected with periods of conflict, namely the Second World War, fares in the sphere of public archaeology. My case studies from Scotland and Finland also illustrate very different community heritage models, and I reflect on the role of the public archaeologist in these scenarios.Peer reviewe
Single-atom interferometer based on two-dimensional spatial adiabatic passage
In this work we propose a novel single-atom interferometer based on a fully
two-dimensional spatial adiabatic passage process using a system of three
identical harmonic traps in a triangular geometry. While the transfer of a
single atom from the ground state of one trap to the ground state of the most
distant one can successfully be achieved in a robust way for a broad range of
parameter values, we point out the existence of a specific geometrical
configuration of the traps for which a crossing of two energy eigenvalues
occurs and the transfer of the atom fails. Instead the wavefunction is robustly
split into a coherent superposition between two of the traps. We show that this
process can be used to construct a single-atom interferometer and discuss its
performance in terms of the final population distribution among the asymptotic
eigenstates of the individual traps. This interferometric scheme could be used
to study space dependent fields from ultrashort to relatively large distances,
or the decay of the coherence of superposition states as a function of the
distance.Comment: 8 pages, 9 figure
Dissociation between Cervical Mucus and Urinary Hormones during the Postpartum Return of Fertility in Breastfeeding Women
Identifying the return of fertility with cervical mucus observations is challenging during the postpartum period. Use of urinary measurements of estrogen and progesterone can assist in understanding the return to fertility during this period. The purposes of this study were to describe the postpartum return of fertility by an analysis of total estrogen (TE) and pregnanediol glucuronide (PDG) profiles and to correlate these profiles with cervical mucus observations. Twenty-six participants collected urine samples during the postpartum period and recorded mucus scores. TE and PDG hormones were analyzed and compared with mucus scores. During amenorrhea, mucus reflected TE changes in only 35 percent of women; after amenorrhea, typical mucus patterns were seen in 33 percent of cycles. We concluded that postpartum mucus and hormone profiles are significantly dissociated but that monitoring urinary hormones may assist in identifying the return of fertility. We also identified different hormonal patterns in the return to fertility.
The postpartum period is a challenging time for identifying the return of fertility. The purposes of this study were to describe the hormonal patterns during the return of fertility and to correlate these patterns with cervical mucus observations. Twenty-six postpartum women collected urine samples and recorded mucus scores. Urinary estrogen and progesterone hormones were analyzed and compared with mucus scores. Before the return of menses, mucus reflected hormonal changes in only 35 percent women and after first menses in 33 percent of cycles. We found that hormone profiles do not correlate well with mucus observations during the postpartum return of fertility
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