An observation of neutron-antineutron oscillations (n-nover ¯), which violate both B and B-L conservation, would constitute a scientific discovery of fundamental importance to physics and cosmology. ...A stringent upper bound on its transition rate would make an important contribution to our understanding of the baryon asymmetry of the Universe by eliminating the postsphaleron baryogenesis scenario in the light quark sector. We show that one can design an experiment using slow neutrons that in principle can reach the required sensitivity of τ_{n-nover ¯}∼10^{10} s in the oscillation time, an improvement of ∼10^{4} in the oscillation probability relative to the existing limit for free neutrons. The improved statistical accuracy needed to reach this sensitivity can be achieved by allowing both the neutron and antineutron components of the developing superposition state to coherently reflect from mirrors. We present a quantitative analysis of this scenario and show that, for sufficiently small transverse momenta of n/nover ¯ and for certain choices of nuclei for the n/nover ¯ guide material, the relative phase shift of the n and nover ¯ components upon reflection and the nover ¯ annihilation rate can be small enough to maintain sufficient coherence to benefit from the greater phase space acceptance the mirror provides.
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The values of the antineutron-nucleus scattering lengths, and, in particular, their imaginary parts, are needed to evaluate the feasibility of using neutron mirrors in laboratory experiments to ...search for neutronantineutron oscillations. We analyze existing experimental and theoretical constraints on these values with emphasis on low-A nuclei and use the results to suggest materials for the neutron-antineutron guide and to evaluate the systematic uncertainties in estimating the neutron-antineutron oscillation time. As an example, we discuss a scenario for a future neutron-antineutron oscillation experiment proposed for the European Spallation Source. We also suggest future experiments which can provide a better determination of the values of antineutron-nuclei scattering lengths.
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We have studied neutron quantum states in the potential well formed by the earth’s gravitational field and a horizontal mirror. The estimated characteristic sizes of the neutron wave functions in the ...two lowest quantum states correspond to expectations with an experimental accuracy. A position-sensitive neutron detector with an extra-high spatial resolution of \(\sim 2 \mathrm{\mu} \)m was developed and tested for this particular experiment, to be used to measure the spatial density distribution in a standing neutron wave above a mirror for a set of some of the lowest quantum states. The present experiment can be used to set an upper limit for an additional short-range fundamental force. We studied methodological uncertainties as well as the feasibility of improving further the accuracy of this experiment.
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DOBA, FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An upper limit to non-Newtonian attracive forces is obtained from the measurement of quantum states of neutrons in the Earth's gravitational field. It is established in a completely new way and ...supports the existing constrains in the nanometer range.
Short-range fundamental forces Antoniadis, I.; Baessler, S.; Büchner, M. ...
Comptes rendus. Physique,
10/2011, Volume:
12, Issue:
8
Journal Article
Peer reviewed
We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent ...forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments.
Nous considérons les motivations théoriques pour rechercher des forces fondamentales supplémentaires à courte portée ainsi que des expériences contraignant leurs paramètres. Les forces peuvent être de deux types : 1) les forces indépendantes du spin ; 2) les forces dépendant du spin, de type axion. Différentes techniques expérimentales sont sensibles dans des domaines différents de distances caractéristiques. Les expériences incluent des mesures de gravité à courte distance, la recherche dʼinteractions supplémentaires en plus de la force de Casimir, des expériences atomiques et neutroniques de précision. Comme nous mettons lʼaccent sur les contraintes neutroniques, la gamme de distances caractéristiques considérées ici correspond à la plage accessible pour les expériences avec les neutrons.
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Coherent forward neutron propagation in gas is discussed as a new approach to search for neutron-antineutron oscillations (n−n¯), which violate both B and B−L conservation. We show that one can ...increase the probability of neutron - antineutron transitions in the presence of a nonzero external magnetic field to essentially free neutron oscillation probability by tuning the density of an appropriate mixture of gases so that the neutron optical potential of the gas cancels that from the magnetic field.
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Cardiac complications of non-cardiac surgeries are an actual and unresolved interdisciplinary problem of clinical medicine today. The incidence of cardiovascular events after non-cardiac surgery is ...higher than in the general population and does not tend to decrease. The risk of cardiac complications in cancer surgery is the highest. Evidence-based approaches to risk assessment and prevention of cardiovascular events in surgical patients with malignant neoplasms have not been developed. In current clinical guidelines on the prevention, prognosis and treatment of cardiac complications of non-cardiac surgeries, the aspects of this problem in surgical oncology are not considered separately.
The aim of this review
was to analyze the current sources of literature on the prediction of cardiovascular complications in surgical treatment of cancer patients. The distinctive features of cancer surgery and additional factors causing an increased risk of adverse cardiac outcomes in patients with malignant neoplasms are described. The article presents the results of large cohort studies on the search for reliable predictors of cardiac complications in non-cardiac surgery and on the development of stratification scales and algorithms for preoperative risk assessment. Particular attention is paid to the possibilities and prospects of using these predictive tools in the surgical treatment of cancer. The surgical risks of interventions for malignant neoplasms are described, as well as methods for calculating cardiac risk and functional status assessment that have been validated in oncological patients cohorts. The data of recent studies on the role of serum biomarkers of myocardial damage and increased cardiovascular risk (cardiac troponins and brain natriuretic peptide) in predicting postoperative cardiac events in non-cardiac surgery are presented. Further prospects for the inclusion of biomarkers in risk stratification systems in patients with malignant neoplasms are discussed.
The problem of finding reliable predictors of the arterial hypertension (HTN) development in people with initially normal blood pressure level has not been resolved yet.
Objective
. The purpose of ...this review was to present and analyze current data on the role and prospects for the use of circulating serum biomarkers in predicting the HTN development. To establish the predictive value of biomarkers and their causal relationships with HTN, the results of prospective and retrospective cohort studies, studies of Mendelian randomization, randomized controlled trials, systematic reviews and meta-analyses on the study of both previously known and relatively new potential risk factors for HTN were analyzed: uric acid, vitamin D, homocysteine, inflammatory biomarkers, soluble ST2, natriuretic peptides, and cardiac troponins. There is evidence of an independent prognostic value of uric acid and inflammatory biomarkers (C-reactive protein) in the HTN development and the possibility of their use as risk markers of HTN. Despite the found relationships of all considered biomarkers with the level of blood pressure in cross-sectional and experimental studies, their causal role in the HTN development in studies of a high level of evidence has not received unambiguous confirmation.
Quantum states in the earth’s gravitational field have been observed, with ultra-cold neutrons falling under gravity. The experimental results can be described by the quantum mechanical scattering ...model presented here. We also discuss other geometries of the experimental setup, which correspond to the absence or the reversion of gravity. Since our quantum mechanical model quantitatively describes, particularly, the experimentally realized situation of reversed gravity, we can practically rule out alternative explanations of the quantum states, in terms of pure confinement effects.
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DOBA, FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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