1,188 research outputs found

    Self-consistent variational theory for globules

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    A self-consistent variational theory for globules based on the uniform expansion method is presented. This method, first introduced by Edwards and Singh to estimate the size of a self-avoiding chain, is restricted to a good solvent regime, where two-body repulsion leads to chain swelling. We extend the variational method to a poor solvent regime where the balance between the two-body attractive and the three-body repulsive interactions leads to contraction of the chain to form a globule. By employing the Ginzburg criterion, we recover the correct scaling for the θ\theta-temperature. The introduction of the three-body interaction term in the variational scheme recovers the correct scaling for the two important length scales in the globule - its overall size RR, and the thermal blob size ξT\xi_{T}. Since these two length scales follow very different statistics - Gaussian on length scales ξT\xi_{T}, and space filling on length scale RR - our approach extends the validity of the uniform expansion method to non-uniform contraction rendering it applicable to polymeric systems with attractive interactions. We present one such application by studying the Rayleigh instability of polyelectrolyte globules in poor solvents. At a critical fraction of charged monomers, fcf_c, along the chain backbone, we observe a clear indication of a first-order transition from a globular state at small ff, to a stretched state at large ff; in the intermediate regime the bistable equilibrium between these two states shows the existence of a pearl-necklace structure.Comment: 7 pages, 1 figur

    The Impact and Burden of Neurological Sequelae Following Bacterial Meningitis: A Narrative Review

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    The burden, impact, and social and economic costs of neurological sequelae following meningitis can be devastating to patients, families and communities. An acute inflammation of the brain and spinal cord, meningitis results in high mortality rates, with over 2.5 million new cases of bacterial meningitis and over 236,000 deaths worldwide in 2019 alone. Up to 30% of survivors have some type of neurological or neuro-behavioural sequelae. These include seizures, hearing and vision loss, cognitive impairment, neuromotor disability and memory or behaviour changes. Few studies have documented the long-term (greater than five years) consequences or have parsed out whether the age at time of meningitis contributes to poor outcome. Knowledge of the socioeconomic impact and demand for medical follow-up services among these patients and their caregivers is also lacking, especially in low- and middle-income countries (LMICs). Within resource-limited settings, the costs incurred by patients and their families can be very high. This review summarises the available evidence to better understand the impact and burden of the neurological sequelae and disabling consequences of bacterial meningitis, with particular focus on identifying existing gaps in LMICs

    Approximate multi-parametric programming based B&B algorithm for MINLPs

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    In this work an improved B&B algorithm for MINLPs is proposed. The basic idea of the proposed algorithm is to treat binary variables as parameters and obtain the solution of the resulting multi-parametric NLP (mp-NLP) as a function of the binary variables, relaxed as continuous variables, at the root node of the search tree. It is recognized that solving the mp-NLP at the root node can be more computationally expensive than exhaustively enumerating all the terminal nodes of the tree. Therefore, only a local approximate parametric solution, and not a complete map of the parametric solution, is obtained and it is then used to guide the search in the tree

    Subsystem symmetry enriched topological order in three dimensions

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    We introduce a model of three-dimensional (3D) topological order enriched by planar subsystem symmetries. The model is constructed starting from the 3D toric code, whose ground state can be viewed as an equal-weight superposition of two-dimensional (2D) membrane coverings. We then decorate those membranes with 2D cluster states possessing symmetry-protected topological order under line-like subsystem symmetries. This endows the decorated model with planar subsystem symmetries under which the loop-like excitations of the toric code fractionalize, resulting in an extensive degeneracy per unit length of the excitation. We also show that the value of the topological entanglement entropy is larger than that of the toric code for certain bipartitions due to the subsystem symmetry enrichment. Our model can be obtained by gauging the global symmetry of a short-range entangled model which has symmetry-protected topological order coming from an interplay of global and subsystem symmetries. We study the non-trivial action of the symmetries on boundary of this model, uncovering a mixed boundary anomaly between global and subsystem symmetries. To further study this interplay, we consider gauging several different subgroups of the total symmetry. The resulting network of models, which includes models with fracton topological order, showcases more of the possible types of subsystem symmetry enrichment that can occur in 3D.Comment: 21 pages. v2: Published version. Updated Section IV with new figure and tabl

    Tailoring three-dimensional topological codes for biased noise

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    Tailored topological stabilizer codes in two dimensions have been shown to exhibit high storage threshold error rates and improved subthreshold performance under biased Pauli noise. Three-dimensional (3D) topological codes can allow for several advantages including a transversal implementation of non-Clifford logical gates, single-shot decoding strategies, parallelized decoding in the case of fracton codes as well as construction of fractal lattice codes. Motivated by this, we tailor 3D topological codes for enhanced storage performance under biased Pauli noise. We present Clifford deformations of various 3D topological codes, such that they exhibit a threshold error rate of 50%50\% under infinitely biased Pauli noise. Our examples include the 3D surface code on the cubic lattice, the 3D surface code on a checkerboard lattice that lends itself to a subsystem code with a single-shot decoder, the 3D color code, as well as fracton models such as the X-cube model, the Sierpinski model and the Haah code. We use the belief propagation with ordered statistics decoder (BP-OSD) to study threshold error rates at finite bias. We also present a rotated layout for the 3D surface code, which uses roughly half the number of physical qubits for the same code distance under appropriate boundary conditions. Imposing coprime periodic dimensions on this rotated layout leads to logical operators of weight O(n)O(n) at infinite bias and a corresponding exp[O(n)]\exp[-O(n)] subthreshold scaling of the logical failure rate, where nn is the number of physical qubits in the code. Even though this scaling is unstable due to the existence of logical representations with O(1)O(1) low-rate Pauli errors, the number of such representations scales only polynomially for the Clifford-deformed code, leading to an enhanced effective distance.Comment: 51 pages, 34 figure

    Eccentric lamellar keratolimbal grafts harvested with a manually guided microkeratome

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    Background: To perform lamellar keratolimbal allograft transplantation in a one- step procedure with a single graft, we investigated the feasibility of harvesting eccentric lamellar keratolimbal grafts from conventionally processed corneoscleral buttons using a manually guided microkeratome in conjunction with an artificial anterior chamber system. Methods: We used the Moria LSK- One microkeratome and the automated lamellar therapeutic keratoplasty ( ALTK) system ( Antony, France). Ten human donor eyes were used to obtain single- piece lamellar keratolimbal grafts. Specimens were processed for light and electron microscopy. Results: Eccentric keratolimbal grafts could be obtained from all human donor buttons. Grafts include a crescent- shaped limbal and a large corneal portion. No visible damage to the limbal region was discernible. Conclusion: Our data show that the LSK- One microkeratome in conjunction with the ALTK system allows harvesting eccentric keratolimbal grafts from donor corneoscleral buttons. Copyright (c) 2007 S. Karger AG, Basel

    Norfloxacin and metronidazole topical formulations for effective treatment of bacterial infections and burn wounds.

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    INTRODUCTION: Our various previous findings have shown the suitability of norfloxacin in the treatment of bacterial infections and burn wounds in alone as well as in combination with Curcuma longa in various topical (ointments, gels, and creams) and transdermal drug delivery systems. AIMS AND METHODS: Keeping these facts in consideration, we have made an another attempt to prepare semisolid formulations containing 1% w/w of norfloxacin and metronidazole with different bases like Carbopol, polyethylene glycol, and hydroxypropylmethyl cellulose for effective treatment of bacterial infections and burn wounds. The prepared formulations were evaluated for physicochemical parameters, in vitro drug release, antimicrobial activity, and burn wound healing properties. RESULTS: The prepared formulations were compared with Silver Sulfadiazine cream 1%, USP. Antimicrobial activity of norfloxacin semisolid formulations was found to be equally effective against both aerobic and anaerobic bacteria in comparison to a marketed formulation of Silver Sulfadiazine 1% cream, USP. Based on the burn wound healing property, the prepared norfloxacin semisolid formulation was found to be in good agreement with marketed Silver Sulfadiazine 1% cream, USP. CONCLUSIONS: These findings suggest formulations containing norfloxacin and metronidazole may also prove as an effective alternative for existing remedies in the treatment of bacterial infections and burn wounds
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