Most cancers are multifactorial diseases. Yet, epidemiological modeling of the effect of ionizing radiation (IR) exposures based on the linear no-threshold model at low doses (LNT) has generally not ...included co-exposure to chemicals, dietary, socio-economic and other risk factors also known to cause the cancers imputed to IR. When so, increased cancer incidences are incorrectly predicted by being solely associated with IR exposures. Moreover, to justify application of the LNT to low doses, high dose-response data, e.g., from the bombing of Hiroshima and Nagasaki, are linearly interpolated to background incidence (which usually has large uncertainty). In order for this interpolation to be correct, it would imply that the biological mechanisms leading to cancer and those that prevent cancer at high doses are exactly the same as at low doses. We show that linear interpolations are incorrect because both the biological and epidemiological evidence for thresholds, or other non-linearities, are more than substantial. We discuss why the LNT model suffers from misspecification errors, multiple testing, and other biases. Moreover, its use by regulatory agencies conflates vague assertions of scientific causation, by conjecturing the LNT, for administrative ease of use.
Laguerrian derivatives and related autofunctions are presented that allow building new special functions determined by the action of a differential isomorphism within the space of analytical ...functions. Such isomorphism can be iterated every time, so that the resulting construction can be re-submitted endlessly in a cyclic way. Some applications of this theory are made in the field of population dynamics and in the solution of Cauchy’s problems for particular linear dynamical systems.
Regulatory analyses, modeling the carcinogenic effect of ionizing radiations (IR) (e.g., alpha and beta particles, x-, and gamma rays, neutrons) and chemicals continue to use the linear no-threshold ...(LNT) model from zero to some low dose. The LNT is an omnibus causal default in regulatory occupational and health risk analysis. Its use raises four issues that make this default an open question. The first is that the LNT applied to study a single agent excludes co-exposure to other known risk factors: physical, dietary, socio-economic, and other. Causation is inappropriately specified because cancer incidence is imputed to the single agent's doses, although most cancers are multifactorial diseases. The second, linear interpolation from high to zero dose and response, is incorrect because biological and epidemiological evidence identify different mechanisms and modes of action at those doses. Third, additivity of exposure effect to background effect is questionable and certainly variable. Fourth, the default overestimates the probabilities and consequences at low doses, supplanting rational decision-making in which alternative models may be more or less likely to be correct. Recent converging scientific evidence against the LNT hypothesis answers the open question. The LNT use in regulation conflates science with administrative ease and risk aversion by policymakers. It should be replaced by models that are based on biologically motivated mechanistic understandings within an evolutionary biology framework that integrates adaptive strategies/processes in their formulation.
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•The LNT model has been the key model for cancer risk assessment.•The LNT has serious flaws that preclude accurate risk predictions.•The LNT should not be used for cancer risk assessment.
Bell polynomials have already been used in many different fields, ranging from number theory to operator theory. Here another application in Laplace Transform (LT) theory is shown, describing a ...method for computing the LT of nested functions. A table containing the first few values of complete Bell polynomials is shown, and a program for deriving the next ones is given. A program for approximating the Laplace Transform of composed analytic functions is also presented.
Common anionic nucleophiles such as those derived from inorganic salts have not been used for enantioselective catalysis because of their insolubility. Here, we report that merging hydrogen bonding ...and phase-transfer catalysis provides an effective mode of activation for nucleophiles that are insoluble in organic solvents. This catalytic manifold relies on hydrogen bonding complexation to render nucleophiles soluble and reactive, while simultaneously inducing asymmetry in the ensuing transformation. We demonstrate the concept using a chiral bis-urea catalyst to form a tridentate hydrogen bonding complex with fluoride from its cesium salt, thereby enabling highly efficient enantioselective ring opening of episulfonium ion. This fluorination method is synthetically valuable considering the scarcity of alternative protocols and points the way to wider application of the catalytic approach with diverse anionic nucleophiles.
A strategy for assembling biaryls linked through a medium‐sized ring is herein presented. π‐Complexation of fluoroarenes to chromium tricarbonyl activates the molecule towards both C−H activation and ...nucleophilic aromatic substitution without covalently altering the molecular connectivity of the arene. The construction of bridged biaryl molecules with 6–10‐membered core rings is achieved through a one‐pot C−H arylation/nucleophilic aromatic substitution sequence. The methodology is applicable to the synthesis of heterocyclic as well as fully carbocyclic rings.
One‐pot, two‐step, three rings: An intermolecular cyclisation reaction has been developed, combining direct C−H arylation with nucleophilic aromatic substitution. π‐Complexation of fluoroarenes to Cr(CO)3 greatly enhances the reactivity of both steps. Rings with 6 to 10 members are accessible through cyclisation with O, N and C‐centered nucleophiles.
In a recent article, the first and second kinds of multivariate Chebyshev polynomials of fractional degree, and the relevant integral repesentations, have been studied. In this article, we introduce ...the first and second kinds of pseudo-Lucas functions of fractional degree, and we show possible applications of these new functions. For the first kind, we compute the fractional Newton sum rules of any orthogonal polynomial set starting from the entries of the Jacobi matrix. For the second kind, the representation formulas for the fractional powers of a r×r matrix, already introduced by using the pseudo-Chebyshev functions, are extended to the Lucas case.
A set of about 25,000 residential reinforced concrete (RC) buildings has been investigated in this study to define fragility curves. The sample originates from a wide database, reported in the online ...Da.D.O. (
Database of Observed Damage
) platform, related to about 320,000 buildings inspected in the aftermath of the nine most devastating earthquakes occurred in Italy between 1976 and 2012 (Friuli 1976; Irpinia 1980; Abruzzo 1984; Umbria-Marche 1997; Pollino 1998; Molise 2002; Emilia 2003; L’Aquila 2009; Emilia 2012). The coherence of data has been guaranteed by a thorough critical analysis among all databases. Then a refined procedure dealing with the completeness of survey campaigns at Municipality level has been applied to avoid biases in fragility fitting. The final sample is then subdivided in different structural design types, determined as a function of the evolution of seismic classification for investigated areas and the sequence of technical codes enforced through the years. The available shakemaps in terms of PGA values, derived by National Institute of Geophysics and Volcanology, are used to characterize seismic ground motion at buildings’ site. The opportunity of enriching the sample of data with undamaged supplementary buildings, located in areas very far from epicenter but missing in the database (only because survey inspections were not required) is deeply discussed and investigated. Finally, according to such a set of data, different classes of buildings representative of existing RC building portfolio in Italy are defined and relevant vulnerability and fragility curves are determined.
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