Can coarse-graining introduce long-range correlations in a symbolic sequence?

We present an exactly solvable mean-field-like theory of correlated ternary sequences which are actually systems with two independent parameters. Depending on the values of these parameters, the variance on the average number of any given symbol shows a linear or a superlinear dependence on the length of the sequence. We have shown that the available phase space of the system is made up a diffusive region surrounded by a superdiffusive region. Motivated by the fact that the diffusive portion of the phase space is larger than that for the binary, we have studied the mapping between these two. We have identified the region of the ternary phase space, particularly the diffusive part, that gets mapped into the superdiffusive regime of the binary. This exact mapping implies that long-range correlation found in a lower dimensional representative sequence may not, in general, correspond to the correlation properties of the original system.Comment: 10 pages including 1 figur

Central extensions of current groups in two dimensions

In this paper we generalize some of these results for loop algebras and groups as well as for the Virasoro algebra to the two-dimensional case. We define and study a class of infinite dimensional complex Lie groups which are central extensions of the group of smooth maps from a two dimensional orientable surface without boundary to a simple complex Lie group G. These extensions naturally correspond to complex curves. The kernel of such an extension is the Jacobian of the curve. The study of the coadjoint action shows that its orbits are labelled by moduli of holomorphic principal G-bundles over the curve and can be described in the language of partial differential equations. In genus one it is also possible to describe the orbits as conjugacy classes of the twisted loop group, which leads to consideration of difference equations for holomorphic functions. This gives rise to a hope that the described groups should possess a counterpart of the rich representation theory that has been developed for loop groups. We also define a two-dimensional analogue of the Virasoro algebra associated with a complex curve. In genus one, a study of a complex analogue of Hill's operator yields a description of invariants of the coadjoint action of this Lie algebra. The answer turns out to be the same as in dimension one: the invariants coincide with those for the extended algebra of currents in sl(2).Comment: 17 page

Reversed anisotropies and thermal contraction of FCC (110) surfaces

The observed anisotropies of surface vibrations for unreconstructed FCC metal (110) surfaces are often reversed from the "common sense" expectation. The source of these reversals is investigated by performing ab initio density functional theory calculations to obtain the surface force constant tensors for Ag(110), Cu(110) and Al(110). The most striking result is a large enhancement in the coupling between the first and third layers of the relaxed surface, which strongly reduces the amplitude of out-of-plane vibrations of atoms in the first layer. This also provides a simple explanation for the thermal contraction of interlayer distances. Both the anisotropies and the thermal contraction arise primarily as a result of the bond topology, with all three (110) surfaces showing similar behavior.Comment: 13 pages, in revtex format, plus 1 postscript figur

Two-Dimensional Magnetic Resonance Tomographic Microscopy using Ferromagnetic Probes

We introduce the concept of computerized tomographic microscopy in magnetic resonance imaging using the magnetic fields and field gradients from a ferromagnetic probe. We investigate a configuration where a two-dimensional sample is under the influence of a large static polarizing field, a small perpendicular radio-frequency field, and a magnetic field from a ferromagnetic sphere. We demonstrate that, despite the non-uniform and non-linear nature of the fields from a microscopic magnetic sphere, the concepts of computerized tomography can be applied to obtain proper image reconstruction from the original spectral data by sequentially varying the relative sample-sphere angular orientation. The analysis shows that the recent proposal for atomic resolution magnetic resonance imaging of discrete periodic crystal lattice planes using ferromagnetic probes can also be extended to two-dimensional imaging of non-crystalline samples with resolution ranging from micrometer to Angstrom scales.Comment: 9 pages, 11 figure

Siegert pseudostates: completeness and time evolution

Within the theory of Siegert pseudostates, it is possible to accurately calculate bound states and resonances. The energy continuum is replaced by a discrete set of states. Many questions of interest in scattering theory can be addressed within the framework of this formalism, thereby avoiding the need to treat the energy continuum. For practical calculations it is important to know whether a certain subset of Siegert pseudostates comprises a basis. This is a nontrivial issue, because of the unusual orthogonality and overcompleteness properties of Siegert pseudostates. Using analytical and numerical arguments, it is shown that the subset of bound states and outgoing Siegert pseudostates forms a basis. Time evolution in the context of Siegert pseudostates is also investigated. From the Mittag-Leffler expansion of the outgoing-wave Green's function, the time-dependent expansion of a wave packet in terms of Siegert pseudostates is derived. In this expression, all Siegert pseudostates--bound, antibound, outgoing, and incoming--are employed. Each of these evolves in time in a nonexponential fashion. Numerical tests underline the accuracy of the method

The role of self-care interventions on men’s health-seeking behaviours to advance their sexual and reproductive health and rights

Background: Self-care interventions are influencing people’s access to, expectation and understanding of healthcare beyond formal health delivery systems. In doing so, self-care interventions could potentially improve health-seeking behaviours. While many men proactively engage in maintaining and promoting their health, the focus on men’s health comes from the recognition, at least partially, that male socialization and social norms can induce men and boys to have a lower engagement in institutionalized public health entities and systems around their sexual and reproductive health and rights, that could impact negatively on themselves, their partners and children. Main text: A research agenda could consider the ways that public health messaging and information on self care practices for sexual and reproductive health and rights could be tailored to reflect men’s lived realities and experiences. Three examples of evidence-based self-care interventions related to sexual and reproductive health and rights that men can, and many do, engage in are briefly discussed: condom use, HIV self-testing and use of telemedicine and digital platforms for sexual health. We apply four core elements that contribute to health, including men’s health (people-centred approaches, quality health systems, a safe and supportive enabling environment, and behaviour-change communication) to each intervention where further research can inform normative guidance. Conclusion: Engaging men and boys and facilitating their participation in self care can be an important policy intervention to advance global sexual and reproductive health and rights goals. The longstanding model of men neglecting or even sabotaging their wellbeing needs to be replaced by healthier lifestyles, which requires understanding how factors related to social support, social norms, power, academic performance or employability conditions, among others, influence men’s engagement with health services and with their own self care practices

Non Abelian TQFT and scattering of self dual field configuration

A non-abelian topological quantum field theory describing the scattering of self-dual field configurations over topologically non-trivial Riemann surfaces, arising from the reduction of 4-dim self-dual Yang-Mills fields, is introduced. It is shown that the phase space of the theory can be exactly quantized in terms of the space of holomorphic structures over stable vector bundles of degree zero over Riemann surfaces. The Dirac monopoles are particular static solutions of the field equations. Its relation to topological gravity is discussed.Comment: 13 pages, Late

Pulmonary Embolism in Patients Hospitalized With COVID-19 (From a New York Health System)

© 2020 Elsevier Inc. Pulmonary embolisms (PEs) in coronavirus disease 2019 (COVID-19) have increasingly been reported in observational studies. However, limited information describing their clinical characteristics and outcomes exists. Our study aims to describe clinical features and risk stratification strategies of hospitalized COVID-19 patients with PE. We retrospectively analyzed 101 hospitalized patients with COVID-19 infection and acute PE. Clinical outcomes measured were intensive care unit admission, mechanical ventilation, bleeding and transfusion events, acute kidney injury (AKI) and mortality. Pulmonary severity index (PESI) scores were used for risk stratification. The most common comorbidities were hypertension (50%), obesity (27%) and hyperlipidemia (32%) among this cohort. Baseline D-dimer abnormalities (4,647.0 ± 8,281.8) were noted on admission with a 3-fold increase at the time of PE diagnosis (13,288.4 ± 14,917.9; p 85), which portended a worse prognosis with higher mortality rate and length of stay. In conclusion, this study provides characteristics and early outcomes for hospitalized patients with COVID-19 and acute pulmonary embolism. PESI scores were utilized for risk stratifying clinical outcomes. Our results should serve to alert the medical community to heighted vigilance of this VTE complication associated with COVID-19 infection

Brauer group of moduli spaces of pairs

We show that the Brauer group of any moduli space of stable pairs with fixed determinant over a curve is zero.Comment: 12 pages. Final version, accepted in Communications in Algebr