Small Twists Research Articles

Anticipating Immunity: Vaccine-induced Immunity and Vaccine Safety in the Finnish News Coverage of COVID-19 Vaccines

In this article I draw on the concept of anticipation to examine Finnish news discourse on the development, licensing and administration of COVID-19 vaccines. I explore the interplay of anticipation of vaccine-induced immunity and vaccine safety concerns, and trace how ideas of protection and risk were invoked in relation to specific vaccine technologies as well as different accounts of biomedical pasts, including cases of narcolepsy associated with one of the 2009 H1N1 influenza vaccines. I demonstrate that anticipation around vaccine development during a public health emergency operates through a series of small shifts and twists that magnify affects around novel vaccines in news media discourse. I argue that even a slight shift in the biomedical knowledge about immunity or in the historical framing of specific vaccine technologies may significantly reshape vaccine-induced immunity as an object of anticipation.

Small bowel volvulus (SBV) due to multiple adhesion in the small intestine: A case report

Introduction: Small bowel volvulus (SBV) is a rare but significant cause of small intestinal obstruction. Ischemia or even infarction is frequently the result. Morbidity and death rates rise when surgical intervention and diagnosis are delayed. Volvulus is a special form of mechanical intestinal obstruction. It happens when a loop of small intestine twists abnormally around the axis of its mesentery. An acute abdomen is a clinical presentation. The bowel itself may become constricted, strangulation of the blood supply, or both may be the source of the symptoms. Case Description: A-49-year old female patient was delivered to the emergency department because of severe pain around her abdomen that lasted for one day with a bloated abdomen. Other symptoms she complained of were nausea, vomiting, fever and constipation since one day before hospitalization. She was transferred to the medical ward and initially diagnosed with abdominal pain due to severe dyspepsia. After four days, her complaints were not improved, and she was diagnosed with intraabdominal obstruction and decided to undergo an emergency laparotomy. During surgery, there was a small bowel volvulus due to multiple adhesion in the small intestine, which caused all of her symptoms. After total 8 days of hospitalization, the patient was finally discharged. Conclusion: Diagnosing SBV can be difficult, especially if the sign of ileus obstruction is not yet fully developed. Early diagnosis and suspicion are pivotal in SBV because a delay in the surgical treatment can be disastrous.

Graphene Twistronics: Tuning the Absorption Spectrum and Achieving Metamaterial Properties

Graphene twistronics using multilayer graphene is presented in such a way that it provides a metamaterial effect. This manuscript also analyzes the prediction of behavior using machine learning. The metamaterial effect is achieved by twisting the graphene layers. Graphene twistronics is a new concept for changing the electrical and optical properties of bilayer graphene by applying a small angle twist between the layers. The angle twists of 5°, 10°, and 15° are analyzed for the proposed graphene twistronics design. Tuning in the absorption spectrum is achieved by applying small twists to the angles of the bilayer graphene. Results in the form of absorption, conductivity, permeability, permittivity, and impedance are presented for different twist angles. The twisted graphene layers also demonstrate negative permittivity and negative permeability, similar to metamaterials. These negative refraction properties of graphene twistronics provide flexibility and transparency, which can be applied in photovoltaic applications. Machine-learning-based regression models are used to reduce the simulation time and resources. The results show that a regression model can reliably estimate intermediate wavelength absorption values with an R2 of 0.9999.

Stacking and Twisting of Layered Materials Enabled by Screw Dislocations and Non-Euclidean Surfaces

ConspectusThe rise of van der Waals layered materials such as graphene, hexagonal boron nitride, and transition-metal dichalcogenides opens up enormous opportunities for exploring novel quantum phenomena at the two-dimensional (2D) atomic limit. The physical properties of van der Waals materials are often affected by the symmetry of the crystal lattices. For example, breaking the inversion symmetry can lead to a variety of phenomena, such as second-harmonic generation, valley polarization, and ferroelectricity. The symmetry and symmetry breaking of layered materials are determined by the atomic arrangements within the layer and the layer stackings. The screw-dislocation-driven growth mechanism is general to 2D materials and can provide effective kinetic pathways to influence the layer stacking and generate diverse and complex layer stackings with different symmetry.Furthermore, different van der Waals layered materials can also be stacked vertically to create artificial new structures. In such stacked structures, the interlayer twist angle between stacked layers results in the formation of large-scale moiré superlattices that manipulate the electronic structures of van der Waals materials and provide an additional degree of freedom for tuning their physical properties. The stacking and twisting of layered materials lead to observations of new quantum phenomena, such as unconventional superconductivity, tunable Mott insulators, moiré excitons, and various magnetic and ferroelectric orderings. Previously, such twisted 2D structures were often fabricated by mechanically stacking exfoliated layers, but it was recently demonstrated that twisted van der Waals structures can form via direct growth. Moreover, continuously twisted structures of 2D materials can be realized through two distinct mechanisms that involve screw dislocations. The Eshelby twist mechanism induced by the strain of screw dislocation gives rise to twisted van der Waals nanowires with small interlayer twists. Beyond the Eshelby twist mechanism, supertwisted spirals have recently been enabled by a non-Euclidean twist mechanism which arises from the mismatched geometry between van der Waals crystals and non-Euclidean (curved) surfaces.In this Account, we start with reviewing the stacking configurations in the diverse polytypic structures of layered materials using transition-metal dichalcogenides as examples. We further discuss the twisted structures of layered materials from a structural point of view. After introducing screw-dislocation-driven growth and showing its generality in the crystal growth of layered materials, we further discuss how the unique structures of screw dislocations influence the stacking and symmetry of layered materials. Moreover, we highlight how screw dislocations enable interlayer twisting through the Eshelby twist mechanism and the non-Euclidean twist mechanism. In the end, the challenges and future perspectives are discussed for the study of screw-dislocated layered materials to control the stacking and twist for exotic physical properties.

Flat Bands in Magic-Angle Bilayer Photonic Crystals at Small Twists.

The new physics of magic-angle twisted bilayer graphene (TBG) motivated extensive studies of flat bands hosted by moiré superlattices in van der Waals structures, inspiring the investigations into their photonic counterparts with potential applications including Bose-Einstein condensation. However, correlation between photonic flat bands and bilayer photonic moiré systems remains unexplored, impeding further development of moiré photonics. In this work, we formulate a coupled-mode theory for low-angle twisted bilayer honeycomb photonic crystals as a close analogy of TBG, discovering magic-angle photonic flat bands with a non-Anderson-type localization. Moreover, the interlayer separation constitutes a convenient degree of freedom in tuning photonic moiré bands without high pressure. A phase diagram is constructed to correlate the twist angle and separation dependencies to the photonic magic angles. Our findings reveal a salient correspondence between fermionic and bosonic moiré systems and pave the avenue toward novel applications through advanced photonic band or state engineering.

Exact space–time prism of an activity program: bidirectional searches in multi-state supernetwork

ABSTRACT Space–time prism (STP) modeling for activity programs with various realizations of activity chains has been a challenging research topic. This study claims that a bidirectional search scheme in a multi-state supernetwork is capable of pinpointing the exact STP of an activity program. The correctness and search space are first analyzed for the existing two-stage bidirectional search methods originally suggested for constructing trip-based STPs. Two simultaneous bidirectional search methods are further suggested. Travel time lower bounds based on A*, landmarks, and triangular inequalities are applied in goal-directed searches to reduce the search space. The small twists in formalism over the existing methods ensure accuracy and computational efficiency. The performances of the different search methods are compared for conducting activity programs in large networks.

Amplification of magnetic field twisting by a stagnation point flow

Context.Flows are a common feature of many processes occurring in the solar atmosphere, such as the formation of prominences where evaporated plasma from the chromosphere condensates along thin prominence threads that are seen to twist and oscillate.Aim.We aim to investigate the twisting of these threads by plasma condensation during their formation.Methods.We introduce a simple model with fixed critical points where the flow speed matches the Alfvén speed. This allows us to study the problem separately in the sub-Alfvénic and super-Alfvénic regimes. The temporal and spatial evolution of small amplitude initial twists along a thread is investigated analytically and numerically.Results.Analytical solutions are constructed in terms of the generalised hypergeometric functions. The solutions grow in time, despite the absence of any influxes of energy or magnetic fields. These results are confirmed numerically: We find oscillations with an amplifying amplitude and increasing period in the sub-Alfvénic regime. In the super-Alfvénic regime, we find twist amplification without any accompanying oscillations. An interesting result is the convergence of the twists at the critical points that leads to the formation of steep gradients and small scales. Energy is transferred from the flow to the amplifying twists.Conclusions.Magnetic field lines may be twisted by a stagnation point flow without the influx of any azimuthal field or energy. This twisting could assist in the formation of topology that is able to support the growth of prominences. The formation of steep gradients and small scales at the critical point is a new phenomenon which requires further investigation in the non-linear regime with the inclusion of magnetic diffusion.

Small Bowel Volvulus In Adult: A Review Of Literature

A Small bowel volvulus is a rare entity where the small bowel loop twists around its own mesentery. These twisting may produce a mechanical obstruction, vascular compromise, or both. In North America and Western Europe, the annual incidence of small bowel volvulus is 1.7 to 5.7 cases per 100,000, but much higher rates of 24 to 60 cases per 100,000 have been observed in Africa, Asia, the Middle East, and India. Small bowel volvulus can be classified as primary and secondary subtypes. In primary variety, there is no known cause whereas secondary variety occurs due to the presence of predisposing lesions, either congenital or acquired of which postoperative adhesion is the most common responsible factor. The most commonly accepted explanation for the initiation of primary small bowel volvulus is the abnormal bowel peristalsis generated due to the sudden overfilling of the empty bowel loop with a large portion of meal after prolong fasting. Secondary small bowel volvulus is commonly seen in the elderly population with mixed gender distribution. There are no specific clinical features or laboratory findings and a high index of suspicion is required to reach a diagnosis. Abdominal pain is the most common presenting feature of small bowel volvulus. CT scan is the investigation of choice and a whirl sign is the characteristic finding of bowel volvulus. Urgent Surgical exploration is the treatment of choice to prevent complications due to vascular compromise. Although small bowel volvulus is rare, it has a mortality rate between 9% and 35%, which can reach up to 100% if associated with bowel necrosis.

Torsion experiment and cracking-torque formulae of hollow prestressed concrete beams

Torsion experiments involving prestressed concrete (PC) beams have had a number of limitations, and the literature has rarely examined hollow PC beam specimens. Following the advances in testing the torsion of solid PC beams, a new experimental project was conducted to test 10 hollow PC-beam specimens under pure torsion. This new torsion test of hollow PC beams achieved an accurate measurement of small twists before and around cracking. It also improved other aspects, such as providing a precise measurement of prestressing forces and prestress transfer. This test also enabled assessment of relatively large specimens with medium to high prestress levels and high concrete strengths. Experimental results from 10 specimens are presented in this paper. The experimental values of cracking torque Tcr for the 10 specimens are compared, with the Tcr values calculated using a recently developed rational formula for reinforced concrete. Using these comparisons, a new Tcr formula for thin- and thick-walled hollow PC beams is proposed, which accurately predicts the cracking torques of the 10 specimens.

Closed form solutions for large deformation of cylinders under combined extension-torsion

In this paper, the mechanical response of an incompressible isotropic nonlinear elastic solid circular cylinder is investigated under combined extension and torsion. Since the deformation tensor in extension-torsion is non-diagonal, implementing stretch based energy functions are complex. Hence, in this study, an analytical solution is proposed for both invariant- and stretch-based models. Moreover, finite element analysis of extension-torsion of hyperelastic materials is carried out using both UHYPER and VUMAT user-defined subroutine in ABAQUS to verify the presented analytical methods. Both stretch and invariant-based exponential forms of strain energy function are employed, and its corresponded material parameters are calibrated for silicon-rubber. The finite element results for stress distribution show a good agreement with analytical findings which confirms the validity and accuracy of the proposed method. Results show that the both invariant- and stretch-based exp-exp models are less conservative for a relatively small stretch and twist while for large stretches they yield higher stresses than the other models and the rate of stress variation increases significantly, especially for a stretch-based exp-exp model. For both Invariant- and stretch-based exp-exp models, an alteration axial stretch is identified where the torsion induced axial force alters from tensile to compressive. For stretches smaller than this alteration point, the cylinder always elongates while for the larger stretches, the cylinder tends to shorten for small twists and then elongates on further twisting. Also, as the axial stretch increases the alteration point appears in larger twists.

Syntomic cohomology and $p$-adic motivic cohomology

We prove a mixed characteristic analog of the Beilinson-Lichtenbaum Conjecture for p-adic motivic cohomology. It gives a description, in the stable range, of p-adic motivic cohomology (defined using algebraic cycles) in terms of differential forms. This generalizes a result of Geisser [10] from small Tate twists to all twists and uses as a critical new ingredient the comparison theorem between syntomic complexes and p-adic nearby cycles proved recently in [8].

Acute sigmoid volvulus

• Cases of sigmoid volvulus rarely present in the pediatric population. • Sigmoid Volvulus occurs when a portion of small bowel twists about its mesentery. • Our approach in management proves equally unique as affective management required deviation from accepted standards of practice.

Pre- and post-cracking torsion in prestressed concrete beams: experimental study

Experimental cracking-twist data on torsional concrete beams display significant variations due to the difficulty of measuring small twists during torsion tests of concrete beams. A recent torsion experiment on large reinforced concrete (RC) beam specimens developed a new method that was able to accurately measure small twists before and around cracking. In the current study, the test method was extended to torsion experiments on prestressed concrete (PSC) beam specimens. In addition to addressing the issue of small-twist measurement, the new method also improved other aspects, such as precise measurement and examination of prestressing forces and prestress transfer, and the testing of relatively large specimens with medium to high prestressing levels. This paper describes the test apparatus and method, presents the experimental results of six PSC beam specimens, and discusses and compares the experimental results. The experimental cracking torques Tcr,Test are compared with the Tcr,RC values calculated using a rational formula for RC members. It was found that the Tcr,Test/Tcr,RC ratio for solid PSC beams increases almost linearly with increasing prestress ratio (fpc/f′c) when fpc/f′c is in the range of approximately 0·09 to 0·16, and asymptotically approaches an upper limit of 1·80 when fpc/f′c exceeds 0·16.

3,5-Diamino-4H-1,2,4-triazol-1-ium 4-nitrobenzoate dihydrate

The crystal of the title salt hydrate, C2H6N5+·C7H4NO4−·2H2O, is built up from a 3,5-diamino-4H-1,2,4-triazol-1-ium cation linked to a 4-nitrobenzoate anion and to two water molecules through strong hydrogen bonds. The triazolyl ring is virtually planar, with the maximum deviation from the mean plane being 0.003 (1) Å. Small twists are noted in the anion with the dihedral angles between the ring and carboxylate and nitro groups being 7.82 (13) and 9.10 (15)°, respectively. In the crystal, molecules are linked by N—H...O, N—H...N, O—H...O and C—H...O interactions, forming layers parallel to (-101). The sheets are linked by O—H...O hydrogen bonds and π–π interactions between triazole and benzene rings [inter-centroid separation = 3.4967 (8) Å] to form a three-dimensional structure.

Two di-alkyl-ammonium salts of 2-amino-4-nitro-benzoic acid: crystal structures and Hirshfeld surface analysis.

The crystal structures of two ammonium salts of 2-amino-4-nitro-benzoic acid are described, namely di-methyl-aza-nium 2-amino-4-nitro-benzoate, C2H8N+·C7H5N2O4-, (I), and di-butyl-aza-nium 2-amino-4-nitro-benzoate, C8H20N+·C7H5N2O4-, (II). The asymmetric unit of (I) comprises a single cation and a single anion. In the anion, small twists are noted for the carboxyl-ate and nitro groups from the ring to which they are connected, as indicated by the dihedral angles of 11.45 (13) and 3.71 (15)°, respectively; the dihedral angle between the substituents is 7.9 (2)°. The asymmetric unit of (II) comprises two independent pairs of cations and anions. In the cations, different conformations are noted in the side chains in that three chains have an all-trans [(+)-anti-periplanar] conformation, while one has a distinctive kink resulting in a (+)-synclinal conformation. The anions, again, exhibit twists with the dihedral angles between the carboxyl-ate and nitro groups and the ring being 12.73 (6) and 4.30 (10)°, respectively, for the first anion and 8.1 (4) and 12.6 (3)°, respectively, for the second. The difference between anions in (I) and (II) is that in the anions of (II), the terminal groups are conrotatory, forming dihedral angles of 17.02 (8) and 19.0 (5)°, respectively. In each independent anion of (I) and (II), an intra-molecular amino-N-H⋯O(carboxyl-ate) hydrogen bond is formed. In the crystal of (I), anions are linked into a jagged supra-molecular chain by charge-assisted amine-N-H⋯O(carboxyl-ate) hydrogen bonds and these are connected into layers via charge-assisted ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds. The resulting layers stack along the a axis, being connected by nitro-N-O⋯π(arene) and methyl-C-H⋯O(nitro) inter-actions. In the crystal of (II), the anions are connected into four-ion aggregates by charge-assisted amino-N-H⋯O(carboxyl-ate) hydrogen bonding. The formation of ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds, involving all ammonium-N-H and carboxyl-ate O atoms leads to a three-dimensional architecture; additional C-H⋯O(nitro) inter-actions contribute to the packing. The Hirshfeld surface analysis confirms the importance of the hydrogen bonding in both crystal structures. Indeed, O⋯H/H⋯O inter-actions contribute nearly 50% to the entire Hirshfeld surface in (I).

MAGNETIC FIELD TWISTING BY INTERGRANULAR DOWNDRAFTS

ABSTRACT The interaction of an intergranular downdraft with an embedded vertical magnetic field is examined. It is demonstrated that the downdraft may couple to small magnetic twists leading to an instability. The descending plasma exponentially amplifies the magnetic twists when it decelerates with depth due to increasing density. Most efficient amplification is found in the vicinity of the level, where the kinetic energy density of the downdraft reaches equipartition with the magnetic energy density. Continual extraction of energy from the decelerating plasma and growth in the total azimuthal energy occurs as a consequence of the wave-flow coupling along the downdraft. The presented mechanism may drive vortices and torsional motions that have been detected between granules and in simulations of magnetoconvection.

Syntomic complexes and p-adic nearby cycles

We compute syntomic cohomology of semistable affinoids in terms of cohomology of $$(\varphi ,\Gamma )$$ -modules which, thanks to work of Fontaine–Herr, Andreatta–Iovita, and Kedlaya–Liu, is known to compute Galois cohomology of these affinoids. For a semistable scheme over a mixed characteristic local ring this implies a comparison isomorphism, up to some universal constants, between truncated sheaves of p-adic nearby cycles and syntomic cohomology sheaves. This generalizes the comparison results of Kato, Kurihara, and Tsuji for small Tate twists (where no constants are necessary) as well as the comparison result of Tsuji that holds over the algebraic closure of the field. As an application, we combine this local comparison isomorphism with the theory of finite dimensional Banach Spaces and finiteness of étale cohomology of rigid analytic spaces proved by Scholze to prove a Semistable conjecture for formal schemes with semistable reduction.

XMM-NEWTONOBSERVATIONS OF SGR 1806–20 OVER SEVEN YEARS FOLLOWING THE 2004 GIANT FLARE

We report on the study of 14 XMM-Newton observations of the magnetar SGR 1806-20 spread over a period of 8 years, starting in 2003 and extending to 2011. We find that in mid 2005, a year and a half after a giant flare (GF), the torques on the star increased to the largest value yet seen, with a long term average rate between 2005 and 2011 of $\lvert\dot{\nu}\rvert\approx1.35\times10^{-11}$ Hz s$^{-1}$, an order of magnitude larger than its historical level measured in 1995. The pulse morphology of the source is complex in the observations following the GF, while its pulsed-fraction remained constant at about $7\%$ in all observations. Spectrally, the combination of a black-body (BB) and power-law (PL) components is an excellent fit to all observations. The BB and PL fluxes increased by a factor of 2.5 and 4, respectively, while the spectra hardened, in concordance with the 2004 major outburst that preceded the GF. The fluxes decayed exponentially back to quiescence with a characteristic time-scale of $\tau\sim1.5$ yrs, although they did not reach a constant value until at least 3.5 years later (2009). The long-term timing and spectral behavior of the source point to a decoupling between the mechanisms responsible for their respective behavior. We argue that low level seismic activity causing small twists in the open field lines can explain the long lasting large torques on the star, while the spectral behavior is due to a twist imparted onto closed field lines after the 2004 large outburst.

A New Apparatus and Method for Torsion Test of Large-size Reinforced Concrete Beams

Abstract This paper describes a novel apparatus and method for conducting torsion tests on large-size hollow reinforced concrete (RC) beams. Previous torsion tests of concrete beams often used metal components to clamp the concrete beam specimen while exerting a twisting torque. This type of apparatus could allow gaps and slips between the clamping metal components and the concrete specimen, introducing errors into the small deformation measurement. In this study we used a monolithic transverse RC beam to convey a twisting torque without gaps to the twist end of the longitudinal test beam and constructed a monolithic RC block at the fixed end. Pre-tensioning forces were used to fasten the RC blocks of the specimens to the underlying steel seat and to the strong floor, thus producing a slippage-free mechanism for the fixed end. The test apparatus also incorporated devices to eliminate any constraints on the longitudinal elongation of the test beams. Seven quantities were experimentally determined for each of the specimens through continuous measurement, using various measurement lengths. The test results show that the test apparatus is rather efficient in determining small twists and that the initial branches of the obtained torque-twist curves exhibit a high degree of linearity. The results also demonstrate that a measurement length should be long enough to incorporate the entire failure region, but not too long, as too much length can cause the twist angles to be underestimated. Furthermore, the experimental values of the shear flow zone thickness decrease drastically around the cracking and remain relatively constant after cracking. The obtained elongation-twist curves are smooth when the measurement length covers the entire failure region, but otherwise they have abrupt turns due to drastic losses of measured twist angles.

Bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) 2,5-dicarboxybenzene-1,4-dicarboxylate–2,9-dimethyl-1,10-phenanthroline–benzene-1,2,4,5-tetracarboxylic acid (1/2/1)

The asymmetric unit of the title co-crystal, 2C14H13N2 +·C10H4O8 2−·2C14H12N2·C10H6O8, comprises a 2,9-dimethyl-1,10-phenanthrolin-1-ium cation (Me2PhenH+) and a 2,9-dimethyl-1,10-phenanthroline mol­ecule (Me2Phen), each in a general position, and half each of a 2,5-di­carb­oxy­benzene-1,4-di­carboxyl­ate dianion (LH2 2−) and a benzene-1,2,4,5-tetra­carb­oxy­lic acid mol­ecule (LH4), each being disposed about a centre of inversion. Small twists are evident in the dianion [the C—C—C—O torsion angles are 168.41 (18) and 16.2 (3)°], whereas a major twist is found for one carb­oxy­lic acid group in the neutral mol­ecule [C—C—C—O = 66.3 (2) and 18.2 (3)°]. The most prominent feature of the crystal packing is the formation of linear supra­molecular chains along [001] mediated by charge-assisted O—H⋯O− hydrogen bonding between alternating LH4 and LH2 2−. These are connected to the Me2PhenH+ and Me2Phen species by N—H⋯O and O—H⋯N hydrogen bonds, respectively. A three-dimensional architecture is formed by C—H⋯O and π–π inter­actions [inter-centroid distance = 3.5337 (17) Å].