1,207 research outputs found
To bnAb or Not to bnAb: Defining Broadly Neutralising Antibodies Against HIV-1
Since their discovery, antibodies capable of broad neutralisation have been at the forefront of HIV-1 research and are of particular interest due to in vivo passive transfer studies demonstrating their potential to provide protection. Currently an exact definition of what is required for a monoclonal antibody to be classed as a broadly neutralising antibody (bnAb) has not yet been established. This has led to hundreds of antibodies with varying neutralisation breadth being studied and has given insight into antibody maturation pathways and epitopes targeted. However, even with this knowledge, immunisation studies and vaccination trials to date have had limited success in eliciting antibodies with neutralisation breadth. For this reason there is a growing need to identify factors specifically associated with bnAb development, yet to do this a set of criteria is necessary to distinguish bnAbs from non-bnAbs. This review aims to define what it means to be a HIV-1 bnAb by comparing neutralisation breadth, genetic features and epitopes of bnAbs, and in the process highlights the challenges of comparing the array of antibodies that have been isolated over the years
Lessons learned from humoral responses of HIV patients
L.E.M. receives support from an FP7 Marie Curie International Outgoing Fellowship for Career Development number 623038
Finite-size scaling properties of random transverse-field Ising chains : Comparison between canonical and microcanonical ensembles for the disorder
The Random Transverse Field Ising Chain is the simplest disordered model
presenting a quantum phase transition at T=0. We compare analytically its
finite-size scaling properties in two different ensembles for the disorder (i)
the canonical ensemble, where the disorder variables are independent (ii) the
microcanonical ensemble, where there exists a global constraint on the disorder
variables. The observables under study are the surface magnetization, the
correlation of the two surface magnetizations, the gap and the end-to-end
spin-spin correlation for a chain of length . At criticality, each
observable decays typically as in both ensembles, but the
probability distributions of the rescaled variable are different in the two
ensembles, in particular in their asymptotic behaviors. As a consequence, the
dependence in of averaged observables differ in the two ensembles. For
instance, the correlation decays algebraically as 1/L in the canonical
ensemble, but sub-exponentially as in the microcanonical
ensemble. Off criticality, probability distributions of rescaled variables are
governed by the critical exponent in both ensembles, but the following
observables are governed by the exponent in the microcanonical
ensemble, instead of the exponent in the canonical ensemble (a) in the
disordered phase : the averaged surface magnetization, the averaged correlation
of the two surface magnetizations and the averaged end-to-end spin-spin
correlation (b) in the ordered phase : the averaged gap. In conclusion, the
measure of the rare events that dominate various averaged observables can be
very sensitive to the microcanonical constraint.Comment: 24 page
Convalescent plasma for COVID-19: a meta-analysis, trial sequential analysis, and meta-regression
Background:
SARS-CoV-2-specific antibodies, particularly those preventing interaction between the viral spike receptor-binding domain and the host angiotensin-converting enzyme 2 receptor, may prevent viral entry into host cells and disease progression. /
Objective:
We performed a systematic review, meta-analysis, trials sequential analysis (TSA) and meta-regression of randomized control trials (RCTs) to evaluate the benefit of convalescent plasma for COVID-19. The primary outcome was 28-30-day mortality. Secondary outcomes included need for mechanical ventilation and intensive care (ICU) admission. /
Data sources:
PubMed, Embase, MedRxiv, and the Cochrane library on 2nd July 2021. /
Results:
Seventeen RCTs were identified recruiting 15,587 patients with 8027 (51.5%) allocated to receive convalescent plasma. Convalescent plasma use was not associated with a mortality benefit (24.7% vs. 25.5%; OR 0.94 (0.85 – 1.04); p = 0.23; I2 = 4%; TSA adjusted CI 0.84 – 1.05), or reduction in need for mechanical ventilation (15.7% vs. 15.4%; OR 1.01 [0.92 – 1.11]; p = 0.82; I2 = 0%; TSA adjusted CI 0.91 – 1.13), or ICU admission (22.4% vs. 16.7%; OR 0.80 (0.21 – 3.09); p = 0.75; I2 = 63%; TSA adjusted CI 0.0 – 196.05). Meta-regression did not reveal any association with titre of convalescent plasma, timing of administration, nor risk of death and treatment effect (p>0.05). Risk of bias was high in most studies. /
Conclusions:
In patients with COVID-19, there was no clear mortality benefit associated with convalescent plasma. In patients with mild disease, convalescent plasma did not prevent either the need for mechanical ventilation or ICU admission.
PROSPERO registration
CRD42021234201
Hydroacoustics for the discovery and quantification of Nassau grouper (Epinephelus striatus) spawning aggregations
Unitary representations of the Galilean line group: Quantum mechanical principle of equivalence
We present a formalism of Galilean quantum mechanics in non-inertial
reference frames and discuss its implications for the equivalence principle.
This extension of quantum mechanics rests on the Galilean line group, the
semidirect product of the real line and the group of analytic functions from
the real line to the Euclidean group in three dimensions. This group provides
transformations between all inertial and non-inertial reference frames and
contains the Galilei group as a subgroup. We construct a certain class of
unitary representations of the Galilean line group and show that these
representations determine the structure of quantum mechanics in non-inertial
reference frames. Our representations of the Galilean line group contain the
usual unitary projective representations of the Galilei group, but have a more
intricate cocycle structure. The transformation formula for the Hamiltonian
under the Galilean line group shows that in a non-inertial reference frame it
acquires a fictitious potential energy term that is proportional to the
inertial mass, suggesting the equivalence of inertial mass and gravitational
mass in quantum mechanics
The Two-Dimensional Disordered Boson Hubbard Model: Evidence for a Direct Mott Insulator-to-Superfluid Transition and Localization in the Bose Glass Phase
We investigate the Bose glass phase and the insulator-to-superfluid
transition in the two-dimensional disordered boson Hubbard model in the Villain
representation via Monte Carlo simulations. In the Bose glass phase the
probability distribution of the local susceptibility is found to have a tail and the imaginary time Green's function decays algebraically
, giving rise to a divergent global susceptibility. By
considering the participation ratio it is shown that the excitations in the
Bose glass phase are fully localized and a scaling law is established. For
commensurate boson densities we find a direct Mott insulator to superfluid
transition without an intervening Bose glass phase for weak disorder. For this
transition we obtain the critical exponents and , which agree with those for the classical three-dimensional XY
model without disorder. This indicates that disorder is irrelevant at the tip
of the Mott-lobes and that here the inequality is violated.Comment: 15 pages RevTeX, 18 postscript-figures include
The Intrinsic Coupling in Integrable Quantum Field Theories
The intrinsic 4-point coupling, defined in terms of a truncated 4-point
function at zero momentum, provides a well-established measure for the
interaction strength of a QFT. We show that this coupling can be computed
non-perturbatively and to high accuracy from the form factors of an
(integrable) QFT. The technique is illustrated and tested with the Ising model,
the XY-model and the O(3) nonlinear sigma-model. The results are compared to
those from high precision lattice simulations.Comment: 69 pages, Late
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