Extended Formulations in Mixed-integer Convex Programming

We present a unifying framework for generating extended formulations for the polyhedral outer approximations used in algorithms for mixed-integer convex programming (MICP). Extended formulations lead to fewer iterations of outer approximation algorithms and generally faster solution times. First, we observe that all MICP instances from the MINLPLIB2 benchmark library are conic representable with standard symmetric and nonsymmetric cones. Conic reformulations are shown to be effective extended formulations themselves because they encode separability structure. For mixed-integer conic-representable problems, we provide the first outer approximation algorithm with finite-time convergence guarantees, opening a path for the use of conic solvers for continuous relaxations. We then connect the popular modeling framework of disciplined convex programming (DCP) to the existence of extended formulations independent of conic representability. We present evidence that our approach can yield significant gains in practice, with the solution of a number of open instances from the MINLPLIB2 benchmark library.Comment: To be presented at IPCO 201

Actinomyces associated with persistent vaginal granulation tissue.

BACKGROUND: We report a case of symptomatic actinomycosis associated with vaginal suture erosion and granulation tissue refractory to conservative management, in an outpatient setting. CASE: Three months after total vaginal hysterectomy and uterosacral ligament vaginal vault suspension, a woman complained of painless, intermittent vaginal discharge and spotting. Despite cauterization of granulation tissue, vaginal spotting persisted for another month. On re-examination, braided polyester suture that was found underlying the granulation tissue was removed. Recurrent symptoms, together with a biopsy revealing actinomycetes, prompted a trial of oral penicillin VK. With persistent symptoms and discomfort during attempts in the outpatient clinic, the woman eventually required suture removal in the operating room. Her symptoms subsequently resolved without recurrence, and no further antibiotic treatment was required. CONCLUSIONS: Actinomyces may be associated with persistent granulation tissue and vault suspension suture material. In rare circumstances, when tissue debridement and suture removal in the clinic is unsatisfactory, surgical intervention in the operating room may be necessary. Ten days of antibiotic therapy alone did not eradicate the granulation tissue, and symptoms resolved only after complete removal of the underlying permanent suture

Dynamics of oscillating scalar field in thermal environment

There often appear coherently oscillating scalar fields in particle physics motivated cosmological scenarios, which may have rich phenomenological consequences. Scalar fields should somehow interact with background thermal bath in order to decay into radiation at an appropriate epoch, but introducing some couplings to the scalar field makes the dynamics complicated. We investigate in detail the dynamics of a coherently oscillating scalar field, which has renormalizable couplings to another field interacting with thermal background. The scalar field dynamics and its resultant abundance are significantly modified by taking account of following effects : (1) thermal correction to the effective potential, (2) dissipation effect on the scalar field in thermal bath, (3) non-perturbative particle production events and (4) formation of non-topological solitons. There appear many time scales depending on the scalar mass, amplitude, couplings and the background temperature, which make the efficiencies of these effects non-trivial.Comment: 45 pages, 6 figures; v2: several typos corrected; v3: minor corrections and references added; v4: minor corrections to reflect the published version; v5: minor correction

Magnetic phase evolution in the spinel compounds Zn1−x_{1-x}Cox_xCr2_2O4_4

We present the magnetic properties of complete solid solutions of ZnCr$_2$O$_4$ and CoCr$_2$O$_4$: two well-studied oxide spinels with very different magnetic ground states. ZnCr$_2$O$_4$, with non-magnetic $d^{10}$ cations occupying the A site and magnetic $d^3$ cations on the B site, is a highly frustrated antiferromagnet. CoCr$_2$O$_4$, with magnetic $d^7$ cations (three unpaired electrons) on the A site as well, exhibits both N\'eel ferrimagnetism as well as commensurate and incommensurate non-collinear magnetic order. More recently, CoCr$_2$O$_4$ has been studied extensively for its polar behavior which arises from conical magnetic ordering. Gradually introducing magnetism on the A site of ZnCr$_2$O$_4$ results in a transition from frustrated antiferromagnetism to glassy magnetism at low concentrations of Co, and eventually to ferrimagnetic and conical ground states at higher concentrations. Real-space Monte-Carlo simulations of the magnetic susceptibility suggest that the first magnetic ordering transition and features of the susceptibility across $x$ are captured by near-neighbor self- and cross-couplings between the magnetic A and B atoms. We present as a part of this study, a method for displaying the temperature dependence of magnetic susceptibility in a manner which helps distinguish between compounds possessing purely antiferromagnetic interactions from compounds where other kinds of ordering are present.Comment: 10 pages, 5 figures, 1 tabl

Assessment of Gastrointestinal Autonomic Dysfunction:Present and Future Perspectives

The autonomic nervous system delicately regulates the function of several target organs, including the gastrointestinal tract. Thus, nerve lesions or other nerve pathologies may cause autonomic dysfunction (AD). Some of the most common causes of AD are diabetes mellitus and α-synucleinopathies such as Parkinson’s disease. Widespread dysmotility throughout the gastrointestinal tract is a common finding in AD, but no commercially available method exists for direct verification of enteric dysfunction. Thus, assessing segmental enteric physiological function is recommended to aid diagnostics and guide treatment. Several established assessment methods exist, but disadvantages such as lack of standardization, exposure to radiation, advanced data interpretation, or high cost, limit their utility. Emerging methods, including high-resolution colonic manometry, 3D-transit, advanced imaging methods, analysis of gut biopsies, and microbiota, may all assist in the evaluation of gastroenteropathy related to AD. This review provides an overview of established and emerging assessment methods of physiological function within the gut and assessment methods of autonomic neuropathy outside the gut, especially in regards to clinical performance, strengths, and limitations for each method

Direct observation of incommensurate magnetism in Hubbard chains

The interplay between magnetism and doping is at the origin of exotic strongly correlated electronic phases and can lead to novel forms of magnetic ordering. One example is the emergence of incommensurate spin-density waves with a wave vector that does not match the reciprocal lattice. In one dimension this effect is a hallmark of Luttinger liquid theory, which also describes the low energy physics of the Hubbard model. Here we use a quantum simulator based on ultracold fermions in an optical lattice to directly observe such incommensurate spin correlations in doped and spin-imbalanced Hubbard chains using fully spin and density resolved quantum gas microscopy. Doping is found to induce a linear change of the spin-density wave vector in excellent agreement with Luttinger theory predictions. For non-zero polarization we observe a decrease of the wave vector with magnetization as expected from the Heisenberg model in a magnetic field. We trace the microscopic origin of these incommensurate correlations to holes, doublons and excess spins which act as delocalized domain walls for the antiferromagnetic order. Finally, when inducing interchain coupling we observe fundamentally different spin correlations around doublons indicating the formation of a magnetic polaron

What is geriatric rehabilitation and how should it be organized? A Delphi study aimed at reaching European consensus

© 2019, The Author(s). Purpose: Many European countries have developed services to rehabilitate the increasing number of older people who experience an acute or subacute decrease in function after a medical event such as a hip fracture or stroke. However, there are important differences between countries regarding patient selection, organization of services, length of stay, and content of the rehabilitation process. The lack of consensus around, and quality criteria for, geriatric rehabilitation limits opportunities for exchange of best practice and scientific research. Methods: 33 experts, mostly geriatricians with experience in geriatric rehabilitation, from 18 European countries were invited to participate in a modified Delphi study. They were asked to react to 68 statements using a five-point Likert scale. The statements were formulated on the basis of literature review and practice experience, and were initially piloted among Dutch elderly care physicians. Consensus was defined beforehand as an Interquartile Range (IQR) o