Search Results (24)

(1) Background: Fragmentation after double and triple photoionization of the CCl₄ molecule in the valence, Cl 2p, and C 1s regions have been reported; (2) Methods: We have used photoion-photoion (PIPICO) coincidence technique combined with synchrotron radiation. In addition, ab initio quantum mechanical calculations were done at multiconfigurational self-consistent and multireference configuration interaction to describe ground and inner-shell states; (3) Results: We have observed coincidences involving singly and doubly charged fragments coming from the doubly and triply ionized molecule. We have also found a well agreement between the quantum mechanical calculations and the total ion yield spectrum. It is shown that the Cl⁺ ion is the predominant product resulting from the fragmentation of the doubly and triply charged CCl₄ molecule. The CCl⁺ + Cl⁺ pair is the dominant coincidence in the spectra from valence up to the C 1s edge; (4) Conclusions: The kinetic energy of the fragments is compatible with the Coulomb explosion model. Full article

We present a generalization of Bregman divergences in finite-dimensional symplectic vector spaces that we term symplectic Bregman divergences. Symplectic Bregman divergences are derived from a symplectic generalization of the Fenchel–Young inequality which relies on the notion of symplectic subdifferentials. The symplectic Fenchel–Young inequality is obtained using the symplectic Fenchel transform which is defined with respect to the symplectic form. Since symplectic forms can be built generically from pairings of dual systems, we obtain a generalization of Bregman divergences in dual systems obtained by equivalent symplectic Bregman divergences. In particular, when the symplectic form is derived from an inner product, we show that the corresponding symplectic Bregman divergences amount to ordinary Bregman divergences with respect to composite inner products. Some potential applications of symplectic divergences in geometric mechanics, information geometry, and learning dynamics in machine learning are touched upon. Full article

A black hole’s spin effects on the jet emissions of high-energy neutrinos and $\gamma$-rays from black hole X-ray binary systems (BHXRBs) are investigated. The BHXRBs consist of a stellar black hole, a companion (donor) star, a BH accretion disk, a BH corona, and two jets emitted from the black hole perpendicular to the accretion disk. For their description, properties of the accretion disk, specifically the accretion disk’s inner radius $R_{in}$ and the accretion disk’s temperature profile $T\left(R\right)$, play key roles since they depend on the black hole’s dimensionless spin parameter ${\alpha }_{\ast }$. In this work, we focus on the main reaction mechanisms taking place inside jets from which high-energy $\gamma$-rays and neutrinos are created. The intensities and integral fluxes of neutrinos and $\gamma$-rays are obtained by integrating the respective source functions. Lastly, the $\gamma$-ray absorption due to $e^{-}$-$e^{+}$ pair production is considered, particularly absorption from the accretion disk. For concrete applications, we have chosen the BHXRB systems MAXI J1820+070, XTE J1550-564, and XTE J1859+226. Full article

The concept of symmetry has played a major role in Hilbert space setting owing to the structure of a complete inner product space. Subsequently, different studies pertaining to symmetry, including symmetric operators, have investigated real Hilbert spaces. In this paper, we study the solutions to multiple-set split feasibility problems for a pair of finite families of $\beta$-enriched, strictly pseudocontractive mappings in the setup of a real Hilbert space. In view of this, we constructed an iterative scheme that properly included these two mappings into the formula. Under this iterative scheme, an appropriate condition for the existence of solutions and strong and weak convergent results are presented. No sum condition is imposed on the countably finite family of the iteration parameters in obtaining our results unlike for several other results in this direction. In addition, we prove that a slight modification of our iterative scheme could be applied in studying hierarchical variational inequality problems in a real Hilbert space. Our results improve, extend and generalize several results currently existing in the literature. Full article

To the existing list of alternative formulations of quantum mechanics, a new version of the non-Hermitian interaction picture is added. What is new is that, in contrast to the more conventional non-Hermitian model-building recipes, the primary information about the observable phenomena is provided not only by the Hamiltonian but also by an additional operator with a real spectrum (say, $R\left(t\right)$) representing another observable. In the language of physics, the information carried by $R\left(t\right)\ne R^{†}\left(t\right)$ opens the possibility of reaching the exceptional-point degeneracy of the real eigenvalues, i.e., a specific quantum phase transition. In parallel, the unitarity of the system remains guaranteed, as usual, via a time-dependent inner-product metric $\mathsf{\Theta }\left(t\right)$. From the point of view of mathematics, the control of evolution is provided by a pair of conjugate Schrödiner equations. This opens the possibility od an innovative dyadic representation of pure states, by which the direct use of $\mathsf{\Theta }\left(t\right)$ is made redundant. The implementation of the formalism is illustrated via a schematic cosmological toy model in which the canonical quantization leads to the necessity of working with two conjugate Wheeler-DeWitt equations. From the point of view of physics, the “kinematical input” operator $R\left(t\right)$ may represent either the radius of a homogeneous and isotropic expanding empty Universe or, if you wish, its Hubble radius, or the scale factor $a\left(t\right)$ emerging in the popular Lemaitre-Friedmann-Robertson-Walker classical solutions, with the exceptional-point singularity of the spectrum of $R\left(t\right)$ mimicking the birth of the Universe (“Big Bang”) at $t=0$. Full article

The efficacy of the available genome-walking methods is restricted by low specificity, high background, or composite operations. We herein conceived bridging PCR, an efficient genome-walking approach. Three primers with random sequences, inner walker primer (IWP), bridging primer (BP), and outer walker primer (OWP), are involved in bridging PCR. The BP is fabricated by splicing OWP to the 5′-end of IWP’s 5′-part. A bridging PCR set is constituted by three rounds of amplification reactions, sequentially performed by IWP, BP plus OWP, and OWP, respectively pairing with three nested sequence-specific primers (SSP). A non-target product arising from IWP alone undergoes end-lengthening mediated by BP. This modified non-target product is a preferentially formed hairpin between the lengthened ends, instead of binding with shorter OWP. Meanwhile, a non-target product, triggered by SSP alone or SSP plus IWP, is removed by nested SSP. As a result, only the target DNA is accumulated. The efficacy of bridging PCR was validated by walking the gadA/R genes of Levilactobacillus brevis CD0817 and the hyg gene of rice. Full article

Shrub encroachment, which is the increase in shrubs or woody plants in grassland, is one of the important ecological problems facing grassland worldwide. The study was conducted in the ecotones between the forest and grassland of Inner Mongolia. Using a simple random sampling method, 40 shrubland sample plots, evenly distributed in the typical forest-grass transition area, were selected for community investigation. According to the steppe shrub encroachment index, the grassland was divided into different levels. The species diversity and interspecific association of different levels of sample plots were statistically analyzed and compared. It was found that the Shannon-Wiener index (H) and Simpson index (P) were negatively associated with the shrub encroachment index (p < 0.01) and gradually decreased with increasing levels of shrub encroachment. When the grassland transitioned to severe shrub formation, the species diversity of the community significantly decreased, and H and P were significantly lower than those of the mild and moderate shrub-steppe, and the lowest values were 1.37 and 0.48, respectively. With the increase in the shrub encroachment index, biomass showed a trend of first increasing and then decreasing. The aboveground biomass of shrub interspace and total aboveground biomass in the severe shrub encroachment steppe were significantly lower than those in the mildly and moderately shrub-steppe, with the lowest values of 101.86 g/m² and 189.69 g/m², respectively. Shrub encroachment led to a change in the overall association of shrub communities in the ecotones between the forest and grassland of Inner Mongolia from positive to negative. The vast majority of species pairs in the shrub community showed no significant association, and the interspecies association was relatively weak. The results showed that shrub encroachment would affect community species diversity; mild and moderate shrub encroachment had no significant impact on community species diversity, but severe shrub encroachment significantly reduced the community species diversity. There was no significant effect of shrub encroachment on aboveground biomass, which increased first and then decreased, and the herbaceous plant population played a leading role in grassland productivity. The interspecific association of grassland is loose and weak. The community was in the early stage of unstable succession, and it was possible to continue shrub encroachment or reverse succession into a typical grassland in response to the interference of human or environmental factors. Full article

MLL3, also known as KMT2C, is a lysine mono-methyltransferase in charge of the writing of an epigenetic mark on lysine 4 from histone 3. The catalytic site of MLL3 is composed of four tyrosines, namely, Y44, Y69, Y128, and Y130. Tyrosine residues are highly conserved among lysine methyltransferases’ catalytic sites, although their complete function is still unclear. The exploration of how modifications on these residues from the enzymatic machinery impact the enzymatic activity of MLL3 could shed light transversally into the inner functioning of enzymes with similar characteristics. Through the use of QMMM calculations, we focus on the effect of the mutation of each tyrosine from the catalytic site on the enzymatic activity and the product specificity in the current study. While we found that the mutations of Y44 and Y128 by phenylalanine inactivated the enzyme, the mutation of Y128 by alanine reactivated the enzymatic activity of MLL3. Moreover, according to our models, the Y128A mutant was even found to be capable of di- and tri-methylate lysine 4 from histone 3, what would represent a gain of function mutation, and could be responsible for the development of diseases. Finally, we were able to establish the inactivation mechanism, which involved the use of Y130 as a water occlusion structure, whose conformation, once perturbed by its mutation or Y128 mutant, allows the access of water molecules that sequester the electron pair from lysine 4 avoiding its methylation process and, thus, increasing the barrier height. Full article

As one of few animals with the capability to execute agile yawing maneuvers, it is quite desirable to take inspiration from hummingbird flight aerodynamics. To understand the wing and body kinematics and associated aerodynamics of a hummingbird performing a free yawing maneuver, a crucial step in mimicking the biological motion in robotic systems, we paired accurate digital reconstruction techniques with high-fidelity computational fluid dynamics (CFD) simulations. Results of the body and wing kinematics reveal that to achieve the pure yaw maneuver, the hummingbird utilizes very little body pitching, rolling, vertical, or horizontal motion. Wing angle of incidence, stroke, and twist angles are found to be higher for the inner wing (IW) than the outer wing (OW). Unsteady aerodynamic calculations reveal that drag-based asymmetric force generation during the downstroke (DS) and upstroke (US) serves to control the speed of the turn, a characteristic that allows for great maneuvering precision. A dual-loop vortex formation during each half-stroke is found to contribute to asymmetric drag production. Wake analysis revealed that asymmetric wing kinematics led to leading-edge vortex strength differences of around 59% between the IW and OW. Finally, analysis of the role of wing flexibility revealed that flexibility is essential for generating the large torque necessary for completing the turn as well as producing sufficient lift for weight support. Full article

A quasi-least-squares (QLS) mixed finite element method (MFE) based on the $L^2$-inner product is utilized to solve an incompressible magnetohydrodynamic (MHD) model. These models are associated with the three unknown terms, i.e., fluid velocity, fluid pressure, and magnetic field. For the MHD-based models, common theories and algorithms for approximation of the solutions are not always applicable because of the choice of the functional spaces during the utilization of the weak formulation. It is well known that the spaces used for the approximation of the different unknowns, e.g., the spaces for the unknowns, cannot be chosen independently for the variational formulation, and may have to satisfy strict stability conditions such as the inf-sup, or Ladyzhenskaya–Babuska–Brezzi (LBB) condition. The dependency of the selection of the spaces for the unknowns are critical and always not applicable for some pair of unknowns. Because of this, the numerical or theoretical solutions must have to face some stability issue. The proposed scheme ($L^2$-inner product) is introduced to circumvent this deficiency of the conditions (inf-sup or LBB) and obtained a well-posed solution theoretically. The model equations are nonlinear and highly coupled with the combination of Navier–Stokes and Maxwell relations. First, these nonlinear models are made linear around a specific state wherein the modified system represents an algebraic equation in a first-order symmetric form. Secondly, a direct iteration technique is applied to solve the nonlinearities and obtain a theoretical convergent rate for a general initial guess. Theoretical results show that only a single parameter with a single initial guess is sufficient to establish the well-posedness of the solution. Full article

Let (X,d) be a metric linear space and a∈X. The point a divides the space into three sets: H_a = {x ∈ X: d(0,x) < d(x,a)}, M_a = {x ∈ X: d(0,x) = d(x,a)} and L_a = {x ∈ X: d(0,x) > d(x,a)}. If the distance is generated by a norm, H_a is called the Leibnizian halfspace of a, M_a is the perpendicular bisector of the segment 0,a and L_a is the remaining set L_a = X\(H_a∪ M_a). It is known that the perpendicular bisector of the segment [0,a] is an affine subspace of X for all a ∈ X if, and only if, X is an inner product space, that is, if and only if the norm is generated by an inner product. In this case, it is also true that if x,y ∈ L_a ∪ M_a, then x + y ∈ L_a∪ M_a. Otherwise written, the set L_a∪ M_a is a semi-group with respect to addition. We investigate the problem: for what kind of norms in X the pair (L_a ∪ M_a,+) is a semi-group for all a ∈ X? In that case, we say that “$\left(X,\Vert .\Vert \right)$has the semi-group property” or that “the norm $\Vert .\Vert$ has the semi-group property”. This is a threedimensional property, meaning that if all the three-dimensional subspaces of X have it, then X also has it. We prove that for two-dimensional spaces, (L_a,+) is a semi-group for any norm, that $\left(X,\Vert .\Vert \right)$ has the semi-group property if, and only if, the norm is strictly convex, and, in higher dimensions, the property fails to be true even if the norm is strictly convex. Moreover, studying the L^p norms in higher dimensions, we prove that the semi-group property holds if, and only if, p = 2. This fact leads us to the conjecture that in dimensions greater than three, the semi-group property holds if, and only if, X is an inner-product space. Full article

Vibrio parahaemolyticus can cause acute gastroenteritis, wound infection, and septicemia in humans. In this study, a simple, specific, and user-friendly diagnostic tool was developed for the first time for the qualitative and quantitative detection of toxins and infection process-associated genes opaR, vpadF, tlh, and ureC in V. parahaemolyticus using the loop-mediated isothermal amplification (LAMP) technique. Three pairs of specific inner, outer, and loop primers were designed for targeting each of these genes, and the results showed no cross-reaction with the other common Vibrios and non-Vibrios pathogenic bacteria. Positive results in the one-step LAMP reaction (at 65 °C for 45 min) were identified by a change to light green and the emission of bright green fluorescence under visible light and UV light (302 nm), respectively. The lowest limit of detection (LOD) for the target genes ranged from 1.46 × 10⁻⁵ to 1.85 × 10⁻³ ng/reaction (25 µL) for the genomic DNA, and from 1.03 × 10⁻² to 1.73 × 10⁰ CFU/reaction (25 µL) for the cell culture of V. parahaemolyticus. The usefulness of the developed method was demonstrated by the fact that the bacterium could be detected in water from various sources and commonly consumed aquatic product samples. The presence of opaR and tlh genes in the Parabramis pekinensis intestine indicated a risk of potentially virulent V. parahaemolyticus in the fish. Full article

In generalized inner product Sobolev spaces we investigate elliptic differential problems with additional unknown functions or distributions in boundary conditions. These spaces are parametrized with a function OR-varying at infinity. This characterizes the regularity of distributions more finely than the number parameter used for the Sobolev spaces. We prove that these problems induce Fredholm bounded operators on appropriate pairs of the above spaces. Investigating generalized solutions to the problems, we prove theorems on their regularity and a priori estimates in these spaces. As an application, we find new sufficient conditions under which components of these solutions have continuous classical derivatives of given orders. We assume that the orders of boundary differential operators may be equal to or greater than the order of the relevant elliptic equation. Full article

With the recent advances in mobile technologies, biometric verification is being adopted in many smart devices as a means for authenticating their owners. As biometric data leakage may cause stringent privacy issues, many proposals have been offered to guarantee the security of stored biometric data, i.e., biometric template. One of the most promising solutions is the use of a remote server that stores the template in an encrypted form and performs a biometric comparison on the ciphertext domain, using recently proposed functional encryption (FE) techniques. However, the drawback of this approach is that considerable computation is required for the inner-pairing product operation used for the decryption procedure of the underlying FE, which is performed in the authentication phase. In this paper, we propose an enhanced method to accelerate the inner-pairing product computation and apply it to expedite the decryption operation of FE and for faster remote biometric verification. The following two important observations are the basis for our improvement—one of the two arguments for the decryption operation does not frequently change over authentication sessions, and we only need to evaluate the product of multiple pairings, rather than individual pairings. From the results of our experiments, the proposed method reduces the time required to compute an inner-pairing product by 30.7%, compared to the previous best method. With this improvement, the time required for biometric verification is expected to decrease by up to 10.0%, compared to a naive method. Full article

Inner product encryption, first introduced by Katz et al., is a type of predicate encryption in which a ciphertext and a private key correspond to an attribute vector and a predicate vector, respectively. Only if the attribute and predicate vectors satisfy the inner product predicate will the decryption in this scheme be correct. In addition, the ability to use inner product encryption as an underlying building block to construct other useful cryptographic primitives has been demonstrated in the context of anonymous identity-based encryption and hidden vector encryption. However, the computing cost and communication cost of performing inner product encryption are very high at present. To resolve this problem, we introduce an efficient inner product encryption approach in this work. Specifically, the size of the private key is only one $\mathbb{G}$ element and one ${\mathbb{Z}}_p$ element, and decryption requires only one pairing computation. The formal security proof and implementation result are also demonstrated. Compared with other state-of-the-art schemes, our scheme is the most efficient in terms of the number of pairing computations for decryption and the private key length. Full article