The electric field surrounding a single positron in a metal is screened by an increase in the local electron density which, in the case of nearly freeelectron metals (like Al, Na, etc.), has a radial distribution similar to that of the electron in positronium (Ps). In such metals, a singlet pair of positrons would experience an attractive interaction and at low enough electron densities could possibly form a bound state that is held together by exchange and correlation energies, thus forming structures analogous to that of the positronium molecule (Ps
We investigate the feasibility of inlaboratory tomographic Xray particle tracking velocimetry (TXPTV) and consider creeping flows with nearly density matched flow tracers. Specifically, in these proofofconcept experiments we examined a Poiseuille flow, flow through porous media and a multiphase flow with a Taylor bubble. For a full 360
 Award ID(s):
 1922877
 Publication Date:
 NSFPAR ID:
 10362696
 Journal Name:
 Experiments in Fluids
 Volume:
 63
 Issue:
 1
 ISSN:
 07234864
 Publisher:
 Springer Science + Business Media
 Sponsoring Org:
 National Science Foundation
More Like this

Abstract ), with binding energies of a few tenths of an eV. Such dipositrons could be prevalent at positron densities of around 10$$_2$$ ${}_{2}$ cm$$^{18}$$ ${}^{18}$ and, if so, would be evident from an apparent broadening of the sharp step at the Fermi surface in measurements of the electron momentum distribution by the angular correlation of the 2$$^{3}$$ ${}^{3}$ annihilation radiation. Even if dipositrons are not directly formed in a metal, optical spectroscopy of Ps$$\gamma $$ $\gamma $ formed in vacuum via pairs of positrons simultaneously being emitted from the surface could be applied to the direct measurement of the momentum distribution of Cooper pairs. If they exist, dipositrons in metals would yield interesting information about electron and positron interactions andmore »$$_2$$ ${}_{2}$Graphic Abstract 
Abstract We report on a series of detailed BreitPauli and Dirac Bspline Rmatrix (DBSR) differential cross section (DCS) calculations for excitation of the
and$$5\,^2\textrm{S}_{1/2} \rightarrow 5\,^2\textrm{P}_{1/2}$$ $5{\phantom{\rule{0ex}{0ex}}}^{2}{\text{S}}_{1/2}\to 5{\phantom{\rule{0ex}{0ex}}}^{2}{\text{P}}_{1/2}$ states in rubidium by 40 eV incident electrons. The early BP computations shown here were carried out with both 5 states and 12 states, while the DBSR models coupled 150 and 325 states, respectively. We also report corresponding results from a limited set of DCS measurements on the unresolved$$5\,^2\textrm{S}_{1/2}\rightarrow 5\,^2\textrm{P}_{3/2}$$ $5{\phantom{\rule{0ex}{0ex}}}^{2}{\text{S}}_{1/2}\to 5{\phantom{\rule{0ex}{0ex}}}^{2}{\text{P}}_{3/2}$ states, with the experimental data being restricted to the scattered electron angular range 2–$$5\,^2\textrm{P}_{1/2,3/2}$$ $5{\phantom{\rule{0ex}{0ex}}}^{2}{\text{P}}_{1/2,3/2}$ . Typically, good agreement is found between our calculated and measured DCS for excitation of the unresolved$$10^\circ $$ ${10}^{\circ}$ states, with best accord being found between the DBSR predictions and the measured data. The present theoretical and experimental results are also compared with predictions from earlier 40 eV calculations using the nonrelativistic DistortedWave Born Approximation and a Relativistic DistortedWave model.$$5\,^2\textrm{P}_{1/2,3/2}$$ $5{\phantom{\rule{0ex}{0ex}}}^{2}{\text{P}}_{1/2,3/2}$Graphic abstract 
Abstract Microscale inorganic particles (d > 1 µm) have reduced surface area and higher density, making them negatively buoyant in most dipcoating mixtures. Their controlled delivery in hardtoreach places through entrainment is possible but challenging due to the density mismatch between them and the liquid matrix called liquid carrier system (LCS). In this work, the particle transfer mechanism from the complex density mismatching mixture was investigated. The LCS solution was prepared and optimized using a polymer binder and an evaporating solvent. The inorganic particles were dispersed in the LCS by stirring at the just suspending speed to maintain the pseudo suspension characteristics for the heterogeneous mixture. The effect of solid loading and the binder volume fraction on solid transfer has been reported at room temperature. Two coating regimes are observed (i) heterogeneous coating where particle clusters are formed at a low capillary number and (ii) effective viscous regime, where full coverage can be observed on the substrate. ‘Zero’ particle entrainment was not observed even at a low capillary number of the mixture, which can be attributed to the presence of the binder and hydrodynamic flow of the particles due to the stirring of the mixture. The critical film thickness for particle entrainment is
formore »$${h}^{*}=0.16a$$ ${h}^{\ast}=0.16a$ 
Abstract Given a suitable solution
V (t ,x ) to the Korteweg–de Vries equation on the real line, we prove global wellposedness for initial data . Our conditions on$$u(0,x) \in V(0,x) + H^{1}(\mathbb {R})$$ $u(0,x)\in V(0,x)+{H}^{1}\left(R\right)$V do include regularity but do not impose any assumptions on spatial asymptotics. We show that periodic profiles satisfy our hypotheses. In particular, we can treat localized perturbations of the muchstudied periodic traveling wave solutions (cnoidal waves) of KdV. In the companion paper Laurens (Nonlinearity. 35(1):343–387, 2022.$$V(0,x)\in H^5(\mathbb {R}/\mathbb {Z})$$ $V(0,x)\in {H}^{5}(R/Z)$https://doi.org/10.1088/13616544/ac37f5 ) we show that smooth steplike initial data also satisfy our hypotheses. We employ the method of commuting flows introduced in Killip and Vişan (Ann. Math. (2) 190(1):249–305, 2019.https://doi.org/10.4007/annals.2019.190.1.4 ) where . In that setting, it is known that$$V\equiv 0$$ $V\equiv 0$ is sharp in the class of$$H^{1}(\mathbb {R})$$ ${H}^{1}\left(R\right)$ spaces.$$H^s(\mathbb {R})$$ ${H}^{s}\left(R\right)$ 
Abstract Background Protein–protein interaction (PPI) is vital for life processes, disease treatment, and drug discovery. The computational prediction of PPI is relatively inexpensive and efficient when compared to traditional wetlab experiments. Given a new protein, one may wish to find whether the protein has any PPI relationship with other existing proteins. Current computational PPI prediction methods usually compare the new protein to existing proteins one by one in a pairwise manner. This is time consuming.
Results In this work, we propose a more efficient model, called deep hash learning proteinandprotein interaction (DHLPPI), to predict allagainstall PPI relationships in a database of proteins. First, DHLPPI encodes a protein sequence into a binary hash code based on deep features extracted from the protein sequences using deep learning techniques. This encoding scheme enables us to turn the PPI discrimination problem into a much simpler searching problem. The binary hash code for a protein sequence can be regarded as a number. Thus, in the prescreening stage of DHLPPI, the string matching problem of comparing a protein sequence against a database with
M proteins can be transformed into a much more simpler problem: to find a number inside a sorted array of lengthM . This prescreening process narrows down themore »Conclusions The experimental results confirmed that DHLPPI is feasible and effective. Using a dataset with strictly negative PPI examples of four species, DHLPPI is shown to be superior or competitive when compared to the other stateoftheart methods in terms of precision, recall or F1 score. Furthermore, in the prediction stage, the proposed DHLPPI reduced the time complexity from
to$$O(M^2)$$ $O\left({M}^{2}\right)$ for performing an allagainstall PPI prediction for a database with$$O(M\log M)$$ $O(MlogM)$M proteins. With the proposed approach, a protein database can be preprocessed and stored for later search using the proposed encoding scheme. This can provide a more efficient way to cope with the rapidly increasing volume of protein datasets.