Bootstrapping Newton Gravity

A non-linear equation obtained by adding gravitational self-interaction terms to the Poisson equation for Newtonian gravity is here employed in order to analyse a static spherically sym- metric homogeneous compact source of given proper mass and radius and the outer vacuum. The main feature of this picture is that, although the freedom of shifting the potential by an ar- bitrary constant is of course lost, the solutions remain qualitatively very close to the Newtonian behaviour. We also notice that the negative gravitational potential energy is smaller than the proper mass for sources with small compactness, but for sources that should form black holes according to General Relativity, the gravitational potential energy becomes of the same order of magnitude of the proper mass, or even larger. Moreover, the pressure overcomes the energy density for large values of the compactness, but it remains finite for finite compactness, hence there exists no Buchdahl limit. This classical description is meant to serve as the starting point for investigating quantum features of (near) black hole configurations within the corpuscular picture of gravity in future developments.Comment: 23 pages, 20 plots. New section and appendix about stability and the pressure clarify comparison with GR. Conclusions rewritten to make motivations cleare

Exploring the bulk of tidal charged micro-black holes

We study the bulk corresponding to tidal charged brane-world black holes. We employ a propagating algorithm which makes use of the three-dimensional multipole expansion and analytically yields the metric elements as functions of the five-dimensional coordinates and of the ADM mass, tidal charge and brane tension. Since the projected brane equations cannot determine how the charge depends on the mass, our main purpose is to select the combinations of these parameters for which black holes of microscopic size possess a regular bulk. Our results could in particular be relevant for a better understanding of TeV-scale black holes.Comment: Latex, 15 pages, 1 table, 5 figures; Section 3.2 extended, typos corrected, no change in conclusion

The decay constants of pseudoscalar mesons in a relativistic quark model

The decay constants of pseudoscalar mesons are calculated in a relativistic quark model which assumes that mesons are made of a valence quark antiquark pair and of an effective vacuum like component. The results are given in terms of quark masses and of some free parameters entering the expression of the internal wave functions of the mesons. By using the pion and kaon decay constants $F_{\pi^+}=130.7~MeV,~F_{K^+}=159.8~MeV$ to fix the parameters of the model one gets $60~MeV\leq F_{D^+}\leq 185~MeV,~95~MeV\leq F_{D_s}\leq230~MeV,~80~MeV\leq F_{B^+}\leq205~MeV$ for the light quark masses $m_u=5.1~MeV,~m_d=9.3~MeV,~m_s=175~MeV$ and the heavy quark masses in the range: $1.~GeV\leq m_c\leq1.6~GeV,~4.1~GeV\leq m_b\leq4.5~GeV$. In the case of light neutral mesons one obtains with the same set of parameters $F_{\pi^0}\approx 138~MeV,~F_\eta\approx~130~MeV,F_{\eta'} \approx~78~MeV$. The values are in agreement with the experimental data and other theoretical results.Comment: 11 pages, LaTe

A q-Deformed Schr\"odinger Equation

We found hermitian realizations of the position vector $\vec{r}$, the angular momentum $\vec{\Lambda}$ and the linear momentum $\vec{p}$, all behaving like vectors under the $su_q(2)$ algebra, generated by $L_0$ and $L_\pm$. They are used to introduce a $q$-deformed Schr\" odinger equation. Its solutions for the particular cases of the Coulomb and the harmonic oscillator potentials are given and briefly discussed.Comment: 14 pages, latex, no figure

A spiral journey: The quest for profound learning

In a competitive world, where information is accessible and continually increasing, authentic learning has become more than ever a necessity for the development of humankind. Apart form being beneficial for everyone in a distant future, it is also valuable for the “here and now” of each person. The present paper proposes the discovery of viable solutions for ensuring a profound learning based on versatile competences and thus indicates the spiral curriculum as such solution. Hence, this paper’s aim is not only to identify how the spiral curriculum operates in practice, but also to underline its benefits when it comes to planning the competencies’ attainment, a process not deprived of difficultie

Heterotic compactifications and nearly-Kahler manifolds

We propose that under certain conditions heterotic string compactifications on half-flat and nearly-Kahler manifolds are equivalent. Based on this correspondence we argue that the moduli space of the nearly-Kahler manifolds under discussion consists only of the Kahler deformations moduli space and there is no correspondent for the complex structure deformations.Comment: 5 pages, references added, typos correcte

Asymptotic Stability for a Class of Metriplectic Systems

Using the framework of metriplectic systems on $\R^n$ we will describe a constructive geometric method to add a dissipation term to a Hamilton-Poisson system such that any solution starting in a neighborhood of a nonlinear stable equilibrium converges towards a certain invariant set. The dissipation term depends only on the Hamiltonian function and the Casimir functions

Inter-observer reliability of ultrasound detection of tendon abnormalities at the wrist and ankle in patients with rheumatoid arthritis

OBJECTIVE: To assess inter-observer reliability in US detection of tendon inflammatory and structural changes at wrists and ankles in RA patients. METHODS: Fourteen consecutive RA patients underwent bilateral US assessment of the extensor carpi ulnaris (ECUT) and tibialis posterior tendons (TPTs) by two blinded rheumatologists, with different level of experience in musculoskeletal (MS) US. Grey scale and power Doppler (PD) US assessment was focused on detection of tenosynovitis, tenosynovial and intra-tendon PD signal and structural lesions (i.e. tendinosis, tendon erosion, partial or total rupture). RESULTS: The frequency of US findings detected by Investigator 1 was 28.6% for inflammatory changes and 51.8% for structural damage changes while Investigator 2 detected 34 and 53.6% for the corresponding abnormalities. A high overall agreement (82.7%) was found for inflammatory pathology and 89.7% for structural lesions in all tendons. Mean kappa (κ) values for all tendons and pathology was moderate (κ = 0.42), with fair level of agreement for the wrist region (0.27-0.34) and moderate to good values for the ankle region (κ = 0.47-0.62). Subclinical abnormalities were detected in 37.5% of the tendons by Investigator 1 and 28.6% of the tendons by Investigator 2. CONCLUSIONS: MSUS showed high overall agreement and fair to moderate inter-observer κ-values between investigators with different levels of experience in detection of tendon pathology at the wrist and ankle in RA patients. Further standardization of scanning method and pathology definitions may improve MSUS reproducibility

Analysis of customer profiles on an electrical distribution network

It has become increasingly important for electrical distribution companies to understand the drivers of demand. The maximum demand at any given substation can vary materially on an annual basis which means it is difficult to create a load related investment plan that is robust and stable. Currently, forecasts are based only on historical demand with little understanding about contributions to load profiles. In particular, the unique diversity of customers on any particular substation can affect load profile shape and future forecasts. Domestic and commercial customers can have very different behaviours generally and within these groups there is room for variation due to economic conditions and building types. This paper analyses customer types associated to substations on a distribution network by way of principal component analysis and identification of substations which deviate from the national demand trend. By examining the variance spread of this deviation, data points can be labelled in the principal component space. Groups of substations can then be categorised as having typical or atypical load profiles. This will support the need for further investigation into particular customer types and highlight the key factors of customer categorisation

Alcoholic liver cirrhosis, more than a simple hepatic disease – A brief review of the risk factors associated with alcohol abuse

Liver cirrhosis is a significant public health problem, being an important cause of mortality and morbidity, responsible for approximately 1.8% of the total number of deaths in Europe. Chronic alcohol consumption is the most common cause of liver cirrhosis in developed countries. Europe has the highest level of alcohol consumption among all the global World Health Organisation (WHO) regions. In this paper, we briefly review major factors leading to excessive alcohol consumption in order to draw attention to the fact that alcoholic liver cirrhosis is more than a simple liver disease, and if those risk/causal factors can be prevented, the incidence of this disease could be reduced greatly. Although excessive alcohol consumption is regarded as the cause of alcoholic liver cirrhosis, the etiology is complex, involving multiple factors that act in synchrony, and which, if prevented, could greatly reduce the incidence of this disease. Children of addicts are likely to develop an alcohol-related mental disorder; however, there is no “gene for alcoholism”