2,467 research outputs found
Airstart performance of a digital electronic engine control system in an F-15 airplane
The airstart performance of the F100 engine equipped with a digital electronic engine control (DEEC) system was evaluated in an F-15 airplane. The DEEC system incorporates closed-loop airstart logic for improved capability. Spooldown and jet fuel starter-assisted airstarts were made over a range of airspeeds and altitudes. All jet fuel starter-assisted airstarts were successful, with airstart time varying from 35 to 60 sec. All spooldown airstarts at airspeeds of 200 knots and higher were successful; airstart times ranged from 45 sec at 250 knots to 135 sec at 200 knots. The effects of altitude on airstart success and time were small. The flight results agreed closely with previous altitude facility test results. The DEEC system provided successful airstarts at airspeeds at least 50 knots lower than the standard F100 engine control system
Dark Universe and distribution of Matter as Quantum Imprinting: the Quantum Origin of Universe
In this paper we analyze the Dark Matter problem and the distribution of
matter through two different approaches, which are linked by the possibility
that the solution of these astronomical puzzles should be sought in the quantum
imprinting of the Universe. The first approach is based on a cosmological model
formulated and developed in the last ten years by the first and third authors
of this paper; the so-called Archaic Universe. The second approach was
formulated by Rosen in 1933 by considering the Friedmann-Einstein equations as
a simple one-dimensional dynamical system reducing the cosmological equations
in terms of a Schroedinger equation. As an example, the quantum memory in
cosmological dynamics could explain the apparently periodic structures of the
Universe while Archaic Universe shows how the quantum phase concernts not only
an ancient era of the Universe, but quantum facets permeating the entire
Universe today.Comment: 18 page
Einstein and Rastall Theories of Gravitation in Comparison
We profit by a recent paper of Visser claiming that Rastall gravity is
equivalent to Einstein gravity to compare the two gravitational theories in a
general way. Our conclusions are different from Visser's ones. We indeed argue
that these two theories are not equivalent. In fact, Rastall theory of gravity
is an "open" theory when compared to Einstein general theory of relativity.
Thus, it is ready to accept the challenges of observational cosmology and
quantum gravity.Comment: 8 pages, comment on the paper arXiv:1711.11500, "Rastall gravity is
equivalent to Einstein gravity", by Matt Visser. Final version matching the
paper published in the European Physical Journal
Quantum oscillations in the black hole horizon
By applying Rosen's quantization approach to the historical Oppenheimer and
Snyder gravitational collapse and by setting the constraints for the formation
of the Schwarzschild black hole (SBH), in a previous paper [1] two of the
Authors (CC and FF) found the gravitational potential, the Schrodinger
equation, the solution for the energy levels, the area quantum and the quantum
representation of the ground state at the Planck scale of the SBH. Such results
are consistent with previous ones in the literature. It was also shown that the
traditional classical singularity in the core of the SBH is replaced by a
quantum oscillator describing a non-singular two-particle system where the two
components, named the "nucleus" and the "electron", strongly interact with each
other through a quantum gravitational interaction. In agreement with the de
Broglie hypothesis, the "electron" is interpreted in terms of the quantum
oscillations of the BH horizon. In other words, the SBH should be the
gravitational analogous of the hydrogen atom. In this paper, it is shown that
these results allow us to compute the SBH entropy as a function of the BH
principal quantum number in terms of Bekenstein-Hawking entropy and three
sub-leading corrections. In addition, the coefficient of the formula of
Bekenstein-Hawking entropy is reduced to a quarter of the traditional value.
Then, it is shown that, by performing a correct rescaling of the energy levels,
the semi-classical Bohr-like approach to BH quantum physics, previously
developed by one of the Authors (CC), is consistent with the obtained results
for large values of the BH principal quantum number. After this, Hawking
radiation will be analysed by discussing its connection with the BH quantum
structure. Finally, it is shown that the time evolution of the above mentioned
system solves the BH information paradox.Comment: 29 pages.Comments are welcome. arXiv admin note: text overlap with
arXiv:1912.0647
Influenza molecular diagnostic testing in a 1000-bed academic Italian hospital during the 2018\u201319 influenza season
Aim: The aims of this study were to examine the requests for influenza molecular tests processed by the Virology Laboratory of the University Hospital of Udine during the 2018\u201319 influenza season and to assess the test results and to estimate costs. Subjects and methods: We analyzed various administrative databases of the hospital health information system, which can be deterministically linked at the individual level through an anonymous stochastic key. Requests for influenza molecular tests from November 1, 2018, to April 15, 2019, and test results were described by week and, for hospitalized patients, hospital ward. Previous vaccination status of tested patients, outcomes and estimated test costs were assessed. Results: In the 2018\u201319 influenza season, 979 influenza A and B virologic tests were processed by the laboratory, corresponding to 758 patients. Requests had more than doubled compared with the previous influenza season. Rapid real-time PCR tests, routinely available at the University Hospital of Udine since January 2019, represented 17% of requests. Six hundred forty-eight patients were hospitalized. Medical wards requested the test after a median of 1 day after admission, whereas requests were delayed for surgical and oncologic patients. The number of tests, proportion of positivity and consumption of rapid tests varied by medical specialty. Overall consumption of oseltamivir was similar to that of the previous influenza season. Conclusions: This analysis, benefiting from the availability of integrated health administrative databases, provided useful information to support public health decision-making and managing the supply and demand for diagnostic tests
Appropriateness of antibiotic prescription for prophylactic purposes among italian dental practitioners: Results from a cross-sectional study
The primary objective of this study was to investigate the pattern of antibiotic prescription for prophylaxis purposes among Italian DPs (dental practitioners). A nationwide cross-sectional study was conducted using a multi-stage sampling design. A structured questionnaire was used to collect socio-demographic data and information about antibiotic prophylaxis (AP) prescriptions for selected dental diagnoses and surgical procedures. The presence of an indication and appropriateness of AP were defined according to international guidelines. In total, 563 DPs answered the questionnaire (response rate 52.6%). The proportions of DPs who prescribed AP in the presence of an indication ranged from 39.1% for luxation injury with soft tissue trauma to 73.1% for dental implants, whilst DPs who prescribed AP in healthy patients ranged from 41.9% in luxation injury with soft tissue trauma to 70.3% for bone grafting. The course of AP reported by DPs was not consistent with the guidelines in 70.9% of explored procedures. A high proportion of AP prescriptions before dental procedures were unnecessary. This highlights the urgent need to incorporate recommendations for best practices into national and local protocols as soon as they are established. Specific antibiotic stewardship strategies targeted to DPs should be implemented and assessed for effectiveness in improving prescribing of antibiotics
Un modello semplificato per la previsione dell'incremento di pressione interstiziale indotto da carichi ciclici
Le procedure che consentono la valutazione dell’incremento di pressione interstiziale indotto da azioni sismiche in terreni sabbiosi saturi si basano, tipicamente, sui risultati di prove cicliche di laboratorio a tensione o deformazione controllata. In tali procedure la storia di carico irregolare a cui è sottoposto in terreno in sito deve essere semplificata con una azione equivalente tale che produca, su provini di terreno sottoposti a prove cicliche di laboratorio, lo stesso incremento delle pressioni interstiziali atteso nel sito. In alternativa, nel caso di propagazione monodimensionale, è possibile utilizzare un unico parametro, detto ‘parametro di danno’, per modellare gli incrementi di pressione interstiziale misurati in laboratorio. Questo parametro consente di applicare direttamente i risultati di laboratorio per predire l’incremento di pressione interstiziale generato in sito da storie irregolari di tensione o deformazione dovute all’azione sismica. Tale procedura, per la sua semplicità di applicazione, consente di effettuare analisi della risposta dinamica di depositi sabbiosi saturi senza adottare sofisticati modelli costitutivi del terreno e pertanto si presta all’implementazione in codici di calcolo che operano nel dominio del tempo
Syntax for free: representing syntax with binding using parametricity
We show that, in a parametric model of polymorphism, the type ∀ α. ((α → α) → α) → (α → α → α) → α is isomorphic to closed de Bruijn terms. That is, the type of closed higher-order abstract syntax terms is isomorphic to a concrete representation. To demonstrate the proof we have constructed a model of parametric polymorphism inside the Coq proof assistant. The proof of the theorem requires parametricity over Kripke relations. We also investigate some variants of this representation
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