1,677 research outputs found
Effective Edge-Fault-Tolerant Single-Source Spanners via Best (or Good) Swap Edges
Computing \emph{all best swap edges} (ABSE) of a spanning tree of a given
-vertex and -edge undirected and weighted graph means to select, for
each edge of , a corresponding non-tree edge , in such a way that the
tree obtained by replacing with enjoys some optimality criterion (which
is naturally defined according to some objective function originally addressed
by ). Solving efficiently an ABSE problem is by now a classic algorithmic
issue, since it conveys a very successful way of coping with a (transient)
\emph{edge failure} in tree-based communication networks: just replace the
failing edge with its respective swap edge, so as that the connectivity is
promptly reestablished by minimizing the rerouting and set-up costs. In this
paper, we solve the ABSE problem for the case in which is a
\emph{single-source shortest-path tree} of , and our two selected swap
criteria aim to minimize either the \emph{maximum} or the \emph{average
stretch} in the swap tree of all the paths emanating from the source. Having
these criteria in mind, the obtained structures can then be reviewed as
\emph{edge-fault-tolerant single-source spanners}. For them, we propose two
efficient algorithms running in and time, respectively, and we show that the guaranteed (either
maximum or average, respectively) stretch factor is equal to 3, and this is
tight. Moreover, for the maximum stretch, we also propose an almost linear time algorithm computing a set of \emph{good} swap edges,
each of which will guarantee a relative approximation factor on the maximum
stretch of (tight) as opposed to that provided by the corresponding BSE.
Surprisingly, no previous results were known for these two very natural swap
problems.Comment: 15 pages, 4 figures, SIROCCO 201
AFLOW-QHA3P: Robust and automated method to compute thermodynamic properties of solids
Accelerating the calculations of finite-temperature thermodynamic properties is a major challenge for rational materials design. Reliable methods can be quite expensive, limiting their applicability in autonomous high-throughput workflows. Here, the three-phonon quasiharmonic approximation (QHA) method is introduced, requiring only three phonon calculations to obtain a thorough characterization of the material. Leveraging a Taylor expansion of the phonon frequencies around the equilibrium volume, the method efficiently resolves the volumetric thermal expansion coefficient, specific heat at constant pressure, the enthalpy, and bulk modulus. Results from the standard QHA and experiments corroborate the procedure, and additional comparisons are made with the recently developed self-consistent QHA. The three approaches—three-phonon, standard, and self-consistent QHAs—are all included within the open-source ab initio framework aflow, allowing the automated determination of properties with various implementations within the same framework
HBV vaccination with Fendrix is effective and safe in pre-dialysis CKD population
Background: Patients with chronic kidney disease have a poor response to hepatitis B vaccine due to the immunodeficiency conferred from chronic uremia. A recombinant HB vaccine containing an improved adjuvant system AS04 (HBV-AS04) has been manufactured but scarce evidence exists on HBV-AS04 use among patients with CKD. Aim: To assess efficacy and safety of an adjuvanted recombinant vaccine (HBV-AS04) in a large cohort of CKD patients at pre-dialysis stage (with susceptibility to HBV infection). Methods: Patients were prospectively enrolled to receive four 20-mcg doses of HBV-AS04 by intramuscular route (deltoid muscle) at months 1, 2, 3, and 4. Anti-HBs surface antibody concentrations were tested at intervals of 1, 2, 3, 4, and 12 months. Multivariate analyses were performed to assess the parameters, which predicted immunologic response to HBV-AS04 vaccine. Results: One hundred and seven patients were included and 102 completed the study. At completion of vaccine schedule, the frequency of responders (anti-HBs titers 65 10 mIU/mL) was 95% (97/102) (mean anti-HBs antibody titers, 688.9 \ub1 385 mIU/mL), according to per-protocol analysis. Serum haemoglobin levels were greater in responder than non- or low-responder patients to HBV-AS04 (P = 0.04) and this was confirmed by multivariate analysis. The seroprotection rate at month 50 was 88% (30/34) with lower anti-HBs antibody titers (218.5 \ub1 269.6 mIU/mL, P = 0.001). No major side effects were observed. Conclusions: Our prospective study performed in a real-world setting showed a high immunogenicity and safety of HBV-AS04 vaccine in patients with CKD not yet on maintenance dialysis. Studies provided with longer follow-ups are under way to assess the durability of seroprotection in responders
Electric Field Induced Phase Transitions in Polymers: A Novel Mechanism for High Speed Energy Storage
This article discusses electric field induced phase transitions in polymers
4′-Amino-2,2′′-dioxo-2,2′′,3,3′′-tetrahydro-1H-indole-3-spiro-1′-cyclopent-3′-ene-2′-spiro-3′′-1H-indole-3′,5′,5′-tricarbonitrile dihydrate
In the title compound, C22H12N6O2·2H2O, the cyclopentene ring adopts an envelope conformation, with the spiro C atom bonded to the dicyano-substituted C atom deviating by 0.437 (2) Å from the plane of the remaining four atoms in the ring. The puckering and smallest displacement asymmetry parameters for the ring are q
2 = 0.275 (2) Å, ϕ = 212.4 (4)° and Δs(C2) = 2.7 (2). The dihedral angle between the two indole groups is 60.1 (1)°. The structure contains intermolecular N—H⋯O hydrogen bonds involving the indole groups and O—H⋯O and O—H⋯N hydrogen bonds involving the water molecules
Optimal two-stage spatial sampling design for estimating critical parameters of SARS-CoV-2 epidemic: Efficiency versus feasibility
The COVID-19 pandemic presents an unprecedented clinical and healthcare challenge for the many medical researchers who are attempting to prevent its worldwide
spread. It also presents a challenge for statisticians involved in designing appropriate
sampling plans to estimate the crucial parameters of the pandemic. These plans are
necessary for monitoring and surveillance of the phenomenon and evaluating health
policies. In this respect, we can use spatial information and aggregate data regarding
the number of verifed infections (either hospitalized or in compulsory quarantine)
to improve the standard two-stage sampling design broadly adopted for studying
human populations. We present an optimal spatial sampling design based on spatially balanced sampling techniques. We prove its relative performance analytically
in comparison to other competing sampling plans, and we also study its properties
through a series of Monte Carlo experiments. Considering the optimal theoretical
properties of the proposed sampling plan and its feasibility, we discuss suboptimal
designs that approximate well optimality and are more readily applicable
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