Controlled locomotion of a droplet propelled by an encapsulated squirmer

We work out the propulsion of a viscous drop which is driven by two mechanisms: the active velocity of an encapsulated squirmer and an externally applied force acting on the squirmer. Of particular interest is the existence of a stable comoving state of drop and squirmer, allowing for controlled manipulation of the viscous drop by external forcing. The velocities of droplet and squirmer, as well as the conditions for a stable comoving state are worked out analytically for the axisymmetric configuration with a general displacement of the squirmer from the center of the droplet Graphic abstract

Shibboleth

In the Book of Judges, the Gileadites use the word shibboleth to target and kill members of a closely related tribe, the Ephraimites, who cannot pronounce the initial shin phoneme. In modern European languages, shibboleth has come to mean a hard-to-falsify sign that winnows identities and establishes and confirms borders; it has also acquired the ancillary meanings of slogan or cliché. The semantic field of shibboleth thus seems keyed to the waning of the logos in an era of technical reproducibility—to the proliferation of technologies and practices of encryption, decryption, exclusion and inclusion that saturate modern life. In the context of an unending refugee crisis and a general displacement, monitoring and quarantining of populations within a global regime of technics, Paul Celan’s subtle yet fierce reorientation of shibboleth merits scrupulous reading. Building on Jacques Derrida’s Shibboleth: For Paul Celan, but following its own itinerary, this book interprets the episode in Judges together with texts by Celan, passages from William Faulkner’s Absalom! Absalom!, and Doris Salcedo’s 2007 installation Shibboleth at the Tate Modern, pursuing the track of a word to which no language can properly lay claim—a word that is both less and more than a word, that signifies both the epitome and the ruin of border control technology, and that thus, despite its violent role in the Biblical story, offers Celan a locus of poetico-political affirmation.

Replisome bypass of a protein-based R-loop block by Pif1

Efficient and faithful replication of the genome is essential to maintain genome stability. Replication is carried out by a multiprotein complex called the replisome, which encounters numerous obstacles to its progression. Failure to bypass these obstacles results in genome instability and may facilitate errors leading to disease. Cells use accessory helicases that help the replisome bypass difficult barriers. All eukaryotes contain the accessory helicase Pif1, which tracks in a 5′–3′ direction on single-stranded DNA and plays a role in genome maintenance processes. Here, we reveal a previously unknown role for Pif1 in replication barrier bypass. We use an in vitro reconstitutedSaccharomyces cerevisiaereplisome to demonstrate that Pif1 enables the replisome to bypass an inactive (i.e., dead) Cas9 (dCas9) R-loop barrier. Interestingly, dCas9 R-loops targeted to either strand are bypassed with similar efficiency. Furthermore, we employed a single-molecule fluorescence visualization technique to show that Pif1 facilitates this bypass by enabling the simultaneous removal of the dCas9 protein and the R-loop. We propose that Pif1 is a general displacement helicase for replication bypass of both R-loops and protein blocks.

Seismic Design of a Double Deck Floating Roof Type Used for Liquid Storage Tanks

Sloshing response of a cylindrical liquid storage tank with the double deck type floating roof (DDFR) subjected to seismic excitation is considered in this paper. The aim of the paper is to clarify the significant parameters that should be considered in the seismic design of a DDFR and proposing a practical seismic design procedure for evaluating the dynamic stresses inside a DDFR. A numerical method including fluid–structure interaction and the geometry details of a DDFR tank are established. The geometric nonlinear effects on the seismic behavior of the DDFR as well as the accuracy of common analytical solution suggested in the literature are examined by the numerical model. The numerical results show that the geometric nonlinear effects can considerably reduce the seismic stress in DDFR, but have no significant effect on the liquid hydrodynamic pressure exerted on the DDFR and the roof's vertical displacement. It is also revealed that not only the general displacement of DDFR but also the local effects of liquid hydrodynamic pressure on the bottom plate should be considered for seismic design of a DDFR. Finally, a design procedure for the evaluation of dynamic stress in the DDFR due to the seismic loads is proposed and discussed.

BEHAVIOUR ANALYSIS AND ENGINEERING CALCULATION OF THE STRESS-RIBBON BRIDGE WITH EXTERNAL TENDONS / DVIJUOSČIO LANKSTAUS KABAMOJO PLIENO TILTO ELGSENOS ANALIZĖ IR INŽINERINIS SKAIČIAVIMAS

The current article discusses a single-span composite steel pedestrian bridge, the load-bearing structure of which is comprised of a stress-ribbon with extended tendons. The analysis is focused on the behaviour of such structure under symmetric loads. The article reviews the general displacement thrust force of load-bearing suspension structures of such bridge as well as presents calculation analysis values of such displacements and the thrust force. In addition, it provides results of the numerical experiment and comparative analysis of the stress-ribbon structure with extended tendons. Santrauka Straipsnyje aptariama vieno tarpatramio pėsčiųjų kombinuotų tiltų lanksti dvijuostė kabamoji konstrukcija. Analizuojama tokios konstrukcijos elgsena veikiant simetrinėms apkrovoms. Apžvelgiami tokių tiltų laikančiųjų kabamųjų konstrukcijų bendrieji poslinkiai ir skėtimo jėgos, pateikiamos tokių poslinkių ir skėtimo jėgų skaičiavimo analizinės išraiškos. Pateikiami skaitinio eksperimento rezultatai, bei vienajuostės ir dvijuostės kabamųjų konstrukcijų lyginamoji analizė.

On the Regulus Associated With the General Displacement of a Line and Its Application in Determining Displacement Screws

In the two position theory of finite kinematics, we are concerned with not only the displacement of a rigid body, but also with the displacement of a certain element of the body. This paper deals with the displacement of a line and unveils the regulus that corresponds to such a displacement. The regulus is then used as a basic entity to determine the displacements of a rigid body from line specifications. Residing on a special hyperbolic paraboloid, the regulus is obtained by the intersection of three linear line complexes corresponding to a specific set of basis screws of a three-system. When determining the displacements of a rigid body from line specifications, a displacement screw is obtained by fitting a linear line complex to two or more line reguli. When two exact pairs of homologous lines are specified, we obtain a unique linear line complex, which determines the corresponding displacement screw. When more than two pairs of homologous lines with measurement errors are specified, it becomes a redundantly specified problem, and a linear line complex that has the best fit to more than two reguli is determined.

ENERGY–MOMENTUM FOR RANDALL–SUNDRUM MODELS

We investigate the conservation law of energy–momentum for Randall–Sundrum models by the general displacement transform. The energy–momentum current has a superpotential and are therefore identically conserved. It is shown that for Randall–Sundrum solution, the momentum vanishes and most of the bulk energy is localized near the Planck brane. The energy density is ε = ε0 e-3k|y|.

On the Regulus Associated With the General Displacement of a Line

In the two position theory of finite kinematics, we are concerned with not only the displacement of a rigid body, but also with the displacement of a certain element of the body. This paper deals with the displacement of a line and reveals the regulus that characterizes such a displacement. Residing on a special hyperbolic paraboloid, the regulus is obtained by the intersection of three linear line complexes corresponding to a specific set of basis screws of a 3-system. The degeneration of the regulus when two positions of a line intersect is also discussed. In this paper, the regulus of intersection is obtained geometrically as well as analytically. The discovery of the regulus lays a geometric foundation for dealing with line-based problems in computational kinematics and computational line geometry.