170 research outputs found
Representations of U(1,q) and Constructive Quaternion Tensor Products
The representation theory of the group U(1,q) is discussed in detail because
of its possible application in a quaternion version of the Salam-Weinberg
theory.
As a consequence, from purely group theoretical arguments we demonstrate that
the eigenvalues must be right-eigenvalues and that the only consistent scalar
products are the complex ones. We also define an explicit quaternion tensor
product which leads to a set of additional group representations for integer
``spin''.Comment: 28 pages, Latex, Dipartimento di Fisica, Universita di Lecce
INFN-Sezione di Lecc
Timelapse
We discuss the existence in an arbitrary frame of a finite time for the
transformation of an initial quantum state into another e.g. in a decay.
This leads to the introduction of a timelapse in analogy with
the lifetime of a particle. An argument based upon the Heisenberg uncertainty
principle suggests the value of . Consequences for the
exponential decay formula and the modifications that introduces
into the Breit-Wigner mass formula are described.Comment: 5 pages [2 figs], ReV-Te
Survival law in a potential model
The radial equation of a simple potential model has long been known to yield
an exponential decay law in lowest order (Breit-Wigner) approximation. We
demonstrate that if the calculation is extended to fourth order the decay law
exhibits the quantum Zeno effect. This model has further been studied
numerically to characterize the extra exponential time parameter which
compliments the lifetime. We also investigate the inverse Zeno effect.Comment: 16 pages, 2 tables, 3 figures, AMS-Te
Quaternionic Electroweak Theory and CKM Matrix
We find in our quaternionic version of the electroweak theory an apparently
hopeless problem: In going from complex to quaternions, the calculation of the
real-valued parameters of the CKM matrix drastically changes. We aim to explain
this quaternionic puzzle.Comment: 8, Revtex, Int. J. Theor. Phys. (to be published
Remarks upon the mass oscillation formulas
The standard formula for mass oscillations is often based upon the
approximation and the hypotheses that neutrinos have been
produced with a definite momentum or, alternatively, with definite energy
. This represents an inconsistent scenario and gives an unjustified
reduction by a factor of two in the mass oscillation formulas. Such an
ambiguity has been a matter of speculations and mistakes in discussing flavour
oscillations. We present a series of results and show how the problem of the
factor two in the oscillation length is not a consequence of gedanken
experiments, i.e. oscillations in time. The common velocity scenario yields the
maximum simplicity.Comment: 9 pages, AMS-Te
Recommended from our members
Phase 1 User Instruction Manual. A Geological Formation - Drill String Dynamic Interaction Finite Element Program (Geodyn)
User instructions for the GEODYN Interactive Finite Element Computer Program are presented. The program is capable of performing the analysis of the three-dimensional transient dynamic response of a Polycrystalline Diamond Compact Bit - Bit Sub arising from the intermittent contact of the bit with the downhole rock formations. The program accommodates non-linear, time dependent, loading and boundary conditions
Chemical signature of colorectal cancer: case–control study for profiling the breath print
Background: Effective screening for colorectal cancer can reduce mortality by early detection of tumours
and colonic polyps. An altered pattern of volatile organic compounds (VOCs) in exhaled breath has been
proposed as a potential non-invasive diagnostic tool for detection of cancer. The aim of this study was
to evaluate the reliability of breath-testing for colorectal cancer screening and early diagnosis using an
advanced breath sampler.
Methods: The exhaled breath of patients with colorectal cancer and non-cancer controls with negative
findings on colonoscopy was collected using the ReCIVA® Breath Sampler. This portable device is
able to capture the alveolar breath fraction without environmental contamination. VOCs were desorbed
thermally and analysed by gas chromatography–mass spectrometry. The discriminatory ability of VOCs
in detecting colorectal cancer was evaluated by receiver operating characteristic (ROC) curve analysis for
each VOC, followed by cross-validation by the leave-one-out method, and by applying stepwise logistic
regression analysis.
Results: The study included 83 patients with colorectal cancer and 90 non-cancer controls. Fourteen
VOCs were found to have significant discriminatory ability in detecting patients with colorectal cancer.
The model with the diagnosis of cancer versus no cancer resulted in a statistically significant likelihood
of discrimination of 173â‹…45 (P <0â‹…001), with an area under the ROC curve of 0â‹…979. Cross-validation of
the model resulted in a true predictive value for colorectal cancer of 93 per cent overall. Reliability of the
breath analysis was maintained irrespective of cancer stage.
Conclusion: This study demonstrated that analysis of exhaled VOCs can discriminate patients with
colorectal cancer from those without. This finding may eventually lead to the creation of a smart online
sensory device, capable of providing a binary answer (cancer/no cancer) and directing to further screening
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