1,318 research outputs found
Meta-dynamical adaptive systems and their applications to a fractal algorithm and a biological model
In this article, one defines two models of adaptive systems: the
meta-dynamical adaptive system using the notion of Kalman dynamical systems and
the adaptive differential equations using the notion of variable dimension
spaces. This concept of variable dimension spaces relates the notion of spaces
to the notion of dimensions. First, a computational model of the Douady's
Rabbit fractal is obtained by using the meta-dynamical adaptive system concept.
Then, we focus on a defense-attack biological model described by our two
formalisms
Dynamical symmetry breaking and the Nambu-Goldstone theorem in the Gaussian wave functional approximation
We analyze the group-theoretical ramifications of the Nambu-Goldstone [NG]
theorem in the self-consistent relativistic variational Gaussian wave
functional approximation to spinless field theories. In an illustrative example
we show how the Nambu-Goldstone theorem would work in the O(N) symmetric
scalar field theory, if the residual symmetry of the vacuum were
lesser than O(N-1), e.g. if the vacuum were O(N-2), or O(N-3),... symmetric.
[This does not imply that any of the "lesser" vacua is actually the absolute
energy minimum: stability analysis has not been done.] The requisite number of
NG bosons would be (2N - 3), or (3N - 6), ... respectively, which may exceed N,
the number of elementary fields in the Lagrangian. We show how the requisite
new NG bosons would appear even in channels that do not carry the same quantum
numbers as one of N "elementary particles" (scalar field quanta, or
Castillejo-Dalitz-Dyson [CDD] poles) in the Lagrangian, i.e. in those "flavour"
channels that have no CDD poles. The corresponding Nambu-Goldstone bosons are
composites (bound states) of pairs of massive elementary (CDD) scalar fields
excitations. As a nontrivial example of this method we apply it to the
physically more interesting 't Hooft model (an extended
bosonic linear model with four scalar and four pseudoscalar fields),
with spontaneously and explicitly broken chiral symmetry.Comment: 17 pages, no figure
Measures of User experience in a Streptococcal pharyngitis and Pneumonia Clinical Decision Support Tools
Objective: To understand clinician adoption of CDS tools as this may provide important insights for the implementation and dissemination of future CDS tools. Materials and Methods: Clinicians (n=168) at a large academic center were randomized into intervention and control arms to assess the impact of strep and pneumonia CDS tools. Intervention arm data were analyzed to examine provider adoption and clinical workflow. Electronic health record data were collected on trigger location, the use of each component and whether an antibiotic, other medication or test was ordered. Frequencies were tabulated and regression analyses were used to determine the association of tool component use and physician orders. Results: The CDS tool was triggered 586 times over the study period. Diagnosis was the most frequent workflow trigger of the CDS tool (57%) as compared to chief complaint (30%) and diagnosis/antibiotic combinations (13%). Conversely, chief complaint was associated with the highest rate (83%) of triggers leading to an initiation of the CDS tool (opening the risk prediction calculator). Similar patterns were noted for initiation of the CDS bundled ordered set and completion of the entire CDS tool pathway. Completion of risk prediction and bundled order set components were associated with lower rates of antibiotic prescribing (OR 0.5; CI 0.2-1.2 and OR 0.5; CI 0.3-0.9, respectively). Discussion: Different CDS trigger points in the clinician user workflow lead to substantial variation in downstream use of the CDS tool components. These variations were important as they were associated with significant differences in antibiotic ordering. Conclusions: These results highlight the importance of workflow integration and flexibility for CDS success
Spacetime as a membrane in higher dimensions
By means of a simple model we investigate the possibility that spacetime is a
membrane embedded in higher dimensions. We present cosmological solutions of
d-dimensional Einstein-Maxwell theory which compactify to two dimensions. These
solutions are analytically continued to obtain dual solutions in which a
(d-2)-dimensional Einstein spacetime "membrane" is embedded in d-dimensions.
The membrane solutions generalise Melvin's 4-dimensional flux tube solution.
The flat membrane is shown to be classically stable. It is shown that there are
zero mode solutions of the d-dimensional Dirac equation which are confined to a
neighbourhood of the membrane and move within it like massless chiral
(d-2)-dimensional fermions. An investigation of the spectrum of scalar
perturbations shows that a well-defined mass gap between the zero modes and
massive modes can be obtained if there is a positive cosmological term in (d-2)
dimensions or a negative cosmological term in d dimensions.Comment: 30 pages, 4 figures in 10 files, epsf. This early brane world paper
is being placed on the archive to make it more easily accessible, as its
results are used in a new brane world construction in an accompanying
submissio
See-Saw Realization of the Texture Zeros in the Neutrino Mass Matrix
We study the see-saw realization of seven textures of the neutrino mass
matrix, which were presented by Frampton, Glashow and Marfatia. Two of them B_1
and B_2 are not realized in the see-saw mechanism without fine-tuning of
parameters. We present some specific textures of the Dirac neutrino mass matrix
and the right-handed Majorana neutrino one. In order to test these textures, we
discuss the effect on the branching ratio of mu --> e gamma. We also study the
U(1)_X times U(1)_{X'} flavor symmetry, in which U(1)_X is anomalous and
U(1)_{X'} is non-anomolous, to reproduce texture zeros. We present examples of
U(1) charges for two textures A_1 and A_2$.Comment: Latex file, 15 pages, the sign of charge is revise
Field-portable reflection and transmission microscopy based on lensless holography
We demonstrate a lensfree dual-mode holographic microscope that can image specimens in both transmission and reflection geometries using in-line transmission and off-axis reflection holography, respectively. This field-portable dual-mode holographic microscope has a weight of ~200 g with dimensions of 15 x 5.5 x 5cm, where a laser source is powered by two batteries. Based on digital in-line holography, our transmission microscope achieves a sub-pixel lateral resolution of â€2 ”m over a wide field-of-view (FOV) of ~24 mm2 due to its unit fringe magnification geometry. Despite its simplicity and ease of operation, in-line transmission geometry is not suitable to image dense or connected objects such as tissue slides since the reference beam gets distorted causing severe aberrations in reconstruction of such objects. To mitigate this challenge, on the same cost-effective and field-portable assembly we built a lensless reflection mode microscope based on digital off-axis holography where a beam-splitter is used to interfere a tilted reference wave with the reflected light from the object surface, creating an off-axis hologram of the specimens on a CMOS sensor-chip. As a result of the reduced space-bandwidth product of the off-axis geometry compared to its in-line counterpart, the imaging FOV of our reflection mode is reduced to ~9 mm2, while still achieving a similar sub-pixel resolution of â€2 ”m. We tested the performance of this compact dual-mode microscopy unit by imaging a US-air force resolution test target, various micro-particles as well as a histopathology slide corresponding to skin tissue. Due to its compact, cost-effective, and lightweight design, this dual-mode lensless holographic microscope might especially be useful for field-use or for conducting microscopic analysis in resource-poor settings
Cancellations in Neutrinoless Double Beta Decay and the Neutrino Mass Matrix
In a degenerate scheme with mass m_0 a complete analysis of the allowed range
of the effective electron neutrino Majorana mass is performed. Special
attention is paid to effects of cancellations caused either by intrinsic CP
parities of the eigenstates (CP invariance) or by complex mixing matrix
elements (CP violation). We investigate all possibilities and give in each case
constraints on the phases, the relative CP parities or the neutrino mass scale.
A solar mixing angle \sin^2 2 \theta smaller than 0.7 jeopardizes the
degenerate mass scheme. A key value of /m_0 is identified, which is
independent on the solar solution and would rule out certain schemes. Also it
would answer the question regarding the presence of CP violation. Even if a
total neutrino mass scale and an effective mass is measured, the value of the
phases or parities is not fixed, unless in some special cases. The resulting
uncertainty in the other mass matrix elements is at least of the same order
than the one stemming from nuclear matrix elements calculations.Comment: 20 pages, 10 figures. Title, abstract and parts of the text change
The TEMPO Survey I: Predicting Yields of the Transiting Exosatellites, Moons, and Planets from a 30-day Survey of Orion with the Nancy Grace Roman Space Telescope
We present design considerations for the Transiting Exosatellites, Moons, and
Planets in Orion (TEMPO) Survey with the Nancy Grace Roman Space Telescope.
This proposed 30-day survey is designed to detect a population of transiting
extrasolar satellites, moons, and planets in the Orion Nebula Cluster (ONC).
The young (1-3 Myr), densely-populated ONC harbors about a thousand bright
brown dwarfs (BDs) and free-floating planetary-mass objects (FFPs). TEMPO
offers sufficient photometric precision to monitor FFPs with for transiting satellites. The survey is also capable of detecting
FFPs down to sub-Saturn masses via direct imaging, although follow-up
confirmation will be challenging. TEMPO yield estimates include 14 (3-22)
exomoons/satellites transiting FFPs and 54 (8-100) satellites transiting BDs.
Of this population, approximately of companions would be "super-Titans"
(Titan to Earth mass). Yield estimates also include approximately
exoplanets transiting young Orion stars, of which will orbit
mid-to-late M dwarfs and approximately ten will be proto-habitable zone,
terrestrial () exoplanets. TEMPO would
provide the first census demographics of small exosatellites orbiting FFPs and
BDs, while simultaneously offering insights into exoplanet evolution at the
earliest stages. This detected exosatellite population is likely to be markedly
different from the current census of exoplanets with similar masses (e.g.,
Earth-mass exosatellites that still possess H/He envelopes). Although our yield
estimates are highly uncertain, as there are no known exoplanets or exomoons
analogous to these satellites, the TEMPO survey would test the prevailing
theories of exosatellite formation and evolution, which limit the certainty
surrounding detection yields.Comment: Submitted to PAS
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