27,492 research outputs found
Coherent States on Hilbert Modules
We generalize the concept of coherent states, traditionally defined as
special families of vectors on Hilbert spaces, to Hilbert modules. We show that
Hilbert modules over -algebras are the natural settings for a
generalization of coherent states defined on Hilbert spaces. We consider those
Hilbert -modules which have a natural left action from another
-algebra say, . The coherent states are well defined in this
case and they behave well with respect to the left action by .
Certain classical objects like the Cuntz algebra are related to specific
examples of coherent states. Finally we show that coherent states on modules
give rise to a completely positive kernel between two -algebras, in
complete analogy to the Hilbert space situation. Related to this there is a
dilation result for positive operator valued measures, in the sense of Naimark.
A number of examples are worked out to illustrate the theory
A complete characterization of phase space measurements
We characterize all the phase space measurements for a non-relativistic
particle.Comment: 11 pages, latex, no figures, iopart styl
Multiple classical limits in relativistic and nonrelativistic quantum mechanics
The existence of a classical limit describing interacting particles in a
second-quantized theory of identical particles with bosonic symmetry is proved.
This limit exists in addition to a previously established classical limit with
a classical field behavior, showing that the limit of the theory
is not unique. An analogous result is valid for a free massive scalar field:
two distinct classical limits are proved to exist, describing a system of
particles or a classical field. The introduction of local operators in order to
represent kinematical properties of interest is shown to break the permutation
symmetry under some localizability conditions, allowing the study of individual
particle properties.Comment: 13 page
Supersymmetric Effects on Isospin Symmetry Breaking and Direct CP Violation in
We argue that one can search for physics beyond the standard model through
measurements of the isospin-violating quantity , its charge conjugate
, and direct CP violation in the partial decay rates of . We illustrate this by working out theoretical profiles of the
charge-conjugate averaged ratio and the CP asymmetry in the
standard model and in some variants of the minimal supersymmetric standard
model. We find that chargino contributions in the large region may
modify the magnitudes and flip the signs of and compared to their standard-model values, providing an
unmistakeable signature of supersymmetry.Comment: 10 pages, 7 figures (requires graphicx
Quantum Transport with Spin Dephasing: A Nonequilibrium Green's Function Approach
A quantum transport model incorporating spin scattering processes is
presented using the non-equilibrium Green's function (NEGF) formalism within
the self-consistent Born approximation. This model offers a unified approach by
capturing the spin-flip scattering and the quantum effects simultaneously. A
numerical implementation of the model is illustrated for magnetic tunnel
junction devices with embedded magnetic impurity layers. The results are
compared with experimental data, revealing the underlying physics of the
coherent and incoherent transport regimes. It is shown that small variations in
magnetic impurity spin-states/concentrations could cause large deviations in
junction magnetoresistances.Comment: NEGF Formalism, Spin Dephasing, Magnetic Tunnel Junctions,
Magnetoresistanc
Recommended from our members
Inequalities in Health and Service Use among People with Borderline Intellectual Impairment
This report, produced in collaboration with Professor Angela Hassiotis and others, sets out the extent to which people with borderline intellectual impairment face inequalities in health and use of services compared with the rest of the population, and seeks to improve awareness of these inequalities.
Findings
- Borderline intellectual impairment is common, affecting at least one adult in ten in England. The term is used here to refer to people with good verbal skills and living in private households, but who may experience cognitive impairments.
- The findings in this report are consistent with previous research: people with borderline intellectual impairment are a disadvantaged group and their needs are not well understood.
- Such adults face high levels of poor mental health, poorer general health, and many limitations in their daily lives.
- Their level of use of mental health treatment and services does not appear to be commensurate with their higher level of need. This indicates that they are underserved compared with the rest of the population.
- This may be due to a lack of professional awareness of their needs, to services not adapting enough to meet those needs, or to difficulties the individual faces in seeking treatment and support.
- Adults with borderline intellectual impairment constitute key users of primary and secondary health care, and employment, education and welfare support. Improving awareness of the needs of this group should form part of wider plans to reduce inequalities in health and service use in England.
Methods
Secondary analysis of data from the Adult Psychiatric Morbidity Survey (APMS) was conducted to profile the circumstances of people with borderline intellectual impairment. APMS is one of the most authoritative and comprehensive national household surveys to assess both intellectual functioning and mental health in adults in England
Pengaruh Konsentrasi Mutagen Sodium Azida (Nan3) terhadap Daya Kecambah dan Keragaan Bibit Padi Gogo Varietas Kulit Manis Generasi M-1
This experiment aims to observe the effect of mutagen concentration of sodium azide to the germination and seedling growth performance of upland rice varieties Kulit Manis generation M-1 and the difference in seedling growth of upland rice varieties in Kulit Manis on the generation M-1 by application Sodium Azide some mutagen concentration. The experiment was conducted in an area behind the of Soil Laboratory, Faculty of Agriculture, University of Riau, from May to July 2015. Research was arranged experimentally using Completely Randomized Design, which consists of 5 treatments concentration of sodium azide (SA), ie (0.0, 0.5, 1.0, 1.5 and 2.0 mM). The mean deviation between treatments tested by Duncan New Multiple Range Test (DNMRT) at the level of 5%. Parameters observed were the first count test, the soil emergence test and the percentage of life seedlings. The result showed that the concentration of Sodium Azide significantly effected on the first count test, the soil emergence test and life seedling percentage. Sodium Azide at the concentration of 2.0 mM produce the first count test, the soil emergence test and the lowest percentage of life seedling
Perspectives: Quantum Mechanics on Phase Space
The basic ideas in the theory of quantum mechanics on phase space are
illustrated through an introduction of generalities, which seem to underlie
most if not all such formulations and follow with examples taken primarily from
kinematical particle model descriptions exhibiting either Galileian or
Lorentzian symmetry. The structures of fundamental importance are the relevant
(Lie) groups of symmetries and their homogeneous (and associated) spaces that,
in the situations of interest, also possess Hamiltonian structures. Comments
are made on the relation between the theory outlined and a recent paper by
Carmeli, Cassinelli, Toigo, and Vacchini.Comment: "Quantum Structures 2004" - Meeting of the International Quantum
Structures Association; Denver, Colorado; 17-22 July, 200
On the nature of the deeply embedded protostar OMC-2 FIR 4
We use mid-infrared to submillimeter data from the Spitzer, Herschel, and
APEX telescopes to study the bright sub-mm source OMC-2 FIR 4. We find a point
source at 8, 24, and 70 m, and a compact, but extended source at 160, 350,
and 870 m. The peak of the emission from 8 to 70 m, attributed to the
protostar associated with FIR 4, is displaced relative to the peak of the
extended emission; the latter represents the large molecular core the protostar
is embedded within. We determine that the protostar has a bolometric luminosity
of 37 Lsun, although including more extended emission surrounding the point
source raises this value to 86 Lsun. Radiative transfer models of the
protostellar system fit the observed SED well and yield a total luminosity of
most likely less than 100 Lsun. Our models suggest that the bolometric
luminosity of the protostar could be just 12-14 Lsun, while the luminosity of
the colder (~ 20 K) extended core could be around 100 Lsun, with a mass of
about 27 Msun. Our derived luminosities for the protostar OMC-2 FIR 4 are in
direct contradiction with previous claims of a total luminosity of 1000 Lsun
(Crimier et al 2009). Furthermore, we find evidence from far-infrared molecular
spectra (Kama et al. 2013, Manoj et al. 2013) and 3.6 cm emission (Reipurth et
al 1999) that FIR 4 drives an outflow. The final stellar mass the protostar
will ultimately achieve is uncertain due to its association with the large
reservoir of mass found in the cold core.Comment: Accpeted by ApJ, 17 pages, 11 figure
- âŠ