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ABSTRACTWe consider a single server queueing system with a finite capacity buffer in which the server is subject to breakdowns and repairs. At the time of a breakdown, the customers, if any, present in the system will either decide to stay or abandon according to a probabilistic mechanism. This decision is made by every customer present in the system independent of the others. We assume that the arrivals of customers occur according to a Markovian arrival process (MAP). The shocks that create breakdowns of the servers are also assumed to follow a MAPindependent of the other MAP. The service and the repair times of the server are assumed to follow (possibly) different phase type (PH) distributions. An arriving customer finding the buffer full will be lost. Further, an arriving customer finding the server under repair may decide to balk or join the queue at that instant. This queueing system, which generalizes some of the well-known queueing models in the literature, is studied as a GI/ M/ 1- type with a finite state space. The model is analyzed in steady-state and illustrative numerical examples including an optimization problem of interest are presented.

Coupling Weyl quasiparticles and charge density waves (CDWs) can lead to fascinating band renormalization and many-body effects beyond band folding and Peierls gaps. For the quasi-one-dimensional chiral compound (TaSe4)2I with an incommensurate CDW transition at TC= 263 K, photoemission mappings thus far are intriguing due to suppressed emission near the Fermi level. Models for this unconventional behavior include axion insulator phases, correlation pseudogaps, polaron subbands, bipolaron bound states, etc. Our photoemission measurements show sharp quasiparticle bands crossing the Fermi level at T> TC, but for T< TC, these bands retain their dispersions with no Peierls or axion gaps at the Weyl points. Instead, occupied band edges recede from the Fermi level, opening a spectral gap. Our results confirm localization of quasiparticles (holes created by photoemission) is the key physics, which suppresses spectral weights over an energy window governed by incommensurate modulation and inherent phase defects of CDW.

Eukaryotes have evolved towards one of two extremes along a spectrum of strategies for remodelling the nuclear envelope during cell division: disassembling the nuclear envelope in an open mitosis or constructing an intranuclear spindle in a closed mitosis1,2. Both classes of mitotic remodelling involve key differences in the core division machinery but the evolutionary reasons for adopting a specific mechanism are unclear. Here we use an integrated comparative genomics and ultrastructural imaging approach to investigate mitotic strategies in Ichthyosporea, close relatives of animals and fungi. We show that species in this clade have diverged towards either a fungal-like closed mitosis or an animal-like open mitosis, probably to support distinct multinucleated or uninucleated states. Our results indicate that multinucleated life cycles favour the evolution of closed mitosis.

A single-server retrial queue with a MAP flow, PH service times and a pool of finite capacity for accumulation of the customers and their group service is considered. Service to the next group is not provided until the number of customers in the pool will reach a certain predefined threshold value. The service time of a group depends on its size and it is less than the sum of the individual service times. The dependencies of the basic performance measures of the system on the capacity of the pool and the threshold are obtained. Numerical results are presented.

In recent years, the interest for narrow band gap colloidal quantum dots (CQDs) has shifted from materials optimized for solar cells (with EG≈ 1.2 eV) to materials with properties at longer wavelengths. This shift necessitates a systematic investigation of their electronic properties to optimize photodiode designs effectively. In this study, we utilized X-ray photoemission to systematically determine how the band gap (with absorption maximum wavelengths of 1000, 1200, 1400, and 1550 nm) and surface chemistry (short halides and thiols) influence the band alignment and the core levels in PbS nanocrystals. Our research provides evidence for a shift from a quasi-intrinsic behavior for the narrowest band gap to an exclusively n-type nature for the particles with the largest size, potentially indicating the emergence of degenerate doping. Core-level analysis reveals that the effect of ligands extends beyond dipole behavior, also inducing charge transfer leading to the formation of metallic islands, which might be detrimental to photodetection. Furthermore, by employing scanning photoemission microscopy, we gained direct access to the photodiode’s built-in potential, a parameter typically obtained through indirect modeling. We then discussed how the particle size influences this property. This study lays the foundation for a more rational design of PbS CQD-based photodiodes operating in the short-wave infrared spectrum.

A priority queueing model with many types of requests and restricted processor sharing is considered. A novel discipline of requests admission and service is proposed. This discipline assumes restriction of the bandwidth (capacity) of the server and the number of requests that can receive service in the system at the same time. This discipline is some kind of realistic hybrid of the traditional discipline of service in a multi-server system and the discipline of the limited processor sharing. The requests of the highest priority can push out from the service the low priority requests. Therefore, the important problem is fitting of the number of requests that can receive service at the same time to the bandwidth of the server. This problem is solved via construction and analysis of a multi-dimensional Markov chain describing operation of the system under any fixed set of the system parameters.

Magic-angle twisted bilayer graphene exhibits correlated phenomena such as superconductivity and Mott insulating states related to the weakly dispersing flat band near the Fermi energy. Such a flat band is expected to be sensitive to both the moiré period and lattice relaxations. Thus, clarifying the evolution of the electronic structure with the twist angle is critical for understanding the physics of magic-angle twisted bilayer graphene. Here we combine nano-spot angle-resolved photoemission spectroscopy and atomic force microscopy to resolve the fine electronic structure of the flat band and remote bands, as well as their evolution with twist angle from 1.07° to 2.60°. Near the magic angle, the dispersion is characterized by a flat band near the Fermi energy with a strongly reduced band width. Moreover, we observe a spectral weight transfer between remote bands at higher binding energy, which allows to extract the modulated interlayer spacing near the magic angle. Our work provides direct spectroscopic information on flat band physics and highlights the important role of lattice relaxations.

Electron doping of graphene has been extensively studied on graphene-supported surfaces, where the metallicity is influenced by the substrate. Herewith we propose potassium adsorption on free-standing nanoporous graphene, thus eluding any effect due to the substrate. We monitor the electron migration in the π* downward-shifted conduction band. In this rigid band shift, we correlate the spectral density of the π* state in the upper Dirac cone with the associated plasmon, blue-shifted with increasing K dose, as deduced by electron energy loss spectroscopy. These results are confirmed by the Dirac plasmon activated by the C 1s emitted electrons, thanks to spatially resolved photoemission. This crosscheck constitutes a reference on the correlation between the electronic π* states in the conduction band and the Dirac plasmon evolution upon in situ electron doping of fully free-standing graphene.

A multi-server queueing system with two types of customers is analyzed. Both types of customers have own reserved servers and also there is a pool of servers that can be used by both types of customers. Type 1 customers have almost preemptive priority with flexible use of a priority depending on the current number of customers of this type in an infinite buffer. Type 2 customers do not have an input buffer and are lost in cases of absence of available servers upon arrival or expelling (forced termination) from service by Type 1 customers. A multi-dimensional Markov chain, which defines the dynamics of the considered system under the fixed total number of servers, numbers of reserved servers, a pattern of the correlated arriving processes, service rates, and the thresholds defining the mechanism of expelling Type 2 customers from service, is analyzed. A numerical example of solving an optimization problem based on the obtained results is considered. Results can be used for the elaboration of enhanced protocols of servers scheduling in many real-world systems including cognitive radio networks with channels leasing.

Propulsion is a critical subsystem of many spacecraft1–4. For efficient propellant usage, electric propulsion systems based on the electrostatic acceleration of ions formed during electron impact ionization of a gas are particularly attractive5,6. At present, xenon is used almost exclusively as an ionizable propellant for space propulsion2–5. However, xenon is rare, it must be stored under high pressure and commercial production is expensive7–9. Here we demonstrate a propulsion system that uses iodine propellant and we present in-orbit results of this new technology. Diatomic iodine is stored as a solid and sublimated at low temperatures. A plasma is then produced with a radio-frequency inductive antenna, and we show that the ionization efficiency is enhanced compared with xenon. Both atomic and molecular iodine ions are accelerated by high-voltage grids to generate thrust, and a highly collimated beam can be produced with substantial iodine dissociation. The propulsion system has been successfully operated in space onboard a small satellite with manoeuvres confirmed using satellite tracking data. We anticipate that these results will accelerate the adoption of alternative propellants within the space industry and demonstrate the potential of iodine for a wide range of space missions. For example, iodine enables substantial system miniaturization and simplification, which provides small satellites and satellite constellations with new capabilities for deployment, collision avoidance, end-of-life disposal and space exploration10–14.

ABSTRACTIn this paper, we study a tandem queuing system in which the arrivals occur according to a versatile Markovian point process. The buffer sizes in the first and second nodes are, respectively, infinite and finite. We incorporate the impatience of the customers in both the nodes. The service times in both nodes are assumed to be of phase type. While the services in the first node are offered on a first-come-first-served basis, we assume that in the second node the services are provided in batches of varying sizes based on two pre-determined thresholds. The system is studied as a multi-dimensional continuous time Markov chain and a few illustrative numerical examples are reported.

Abstract: The effect of irradiation with helium ions of thin cobalt films on a layer of heavy metals (Pt and W) on the interfacial Dzyaloshinskii–Moriya interaction (iDMI) is studied experimentally. The iDMI value is measured via Brillouin light scattering (BLS). The hysteresis loops of the samples are measured via optical magnetometry. The iDMI value varies nonmonotonically in the range of 0.1–0.6 J m–2at fluences of 1014‒1016cm–2.

Abstract: The possibility of using implantation of 20-keV He+ions for modification of the domain structure and magnetic properties of CoPt films (formed by the electron-beam evaporation method) with different cobalt contents (Co0.45Pt0.55and Co0.35Pt0.65) has been investigated. A decrease in the coercive field (narrowing of the hysteresis loop in the magnetic-field dependences of the Faraday angle and magnetization) with an increase in the He+ion fluence from 2 × 1014to 4 × 1014cm–2has been found for the irradiated CoPt samples of both compositions. The residual magnetization of the Co0.35Pt0.65films coincides with the saturation magnetization, and a decrease in the residual magnetization is observed for Co0.45Pt0.55. It is shown by magnetic force microscopy that the largest number of round isolated domains (skyrmions) for the Co0.45Pt0.55alloy are formed when the ion fluence increases to 3 × 1014cm–2, while 360-degree domain walls (1D skyrmions) are observed along with round isolated domains for the Co0.35Pt0.65films irradiated with a He+fluence of 4 × 1014cm–2. An analysis of CoPt films by Mandelstam–Brillouin spectroscopy revealed an increase in the shift between the Stokes and anti-Stokes components of the spectrum and a significant enhancement of the Dzyaloshinski–Moriya interaction in the irradiated samples. Model calculations performed using the SRIM program showed that the ion irradiation facilitates asymmetric mixing of Co and Pt atoms in CoPt films, which may underlie the mechanism of the observed effects of ion irradiation on their magnetic properties and domain structure.

Radiation stability of ZnO hollow particles under 100 keV proton and electron exposure have been investigated. The experimental data were compared with the calculated ones obtained by modeling in the GEANT4 software package. Hollow particles have better radiation stability compared with bulk microparticles cause by low defects accumulation in the hollow particles, which was confirmed by simulation in GEANT4.

•Single server queue with limited processor sharing and customers impatience is analyzed.•Markov arrival process and phase type distribution of service time are considered.•Laplace-Stieltjes transform of sojourn time distribution is computed.•Bad quality of simple approximations of the model is numerically demonstrated.•Possibility of optimal choice of the server capacity is shown.

The doping mechanism of fully suspended nanoporous graphene with alkali metals unveils the charge redistribution between the donors and graphene. The evolution of the electronic charge induced in the graphene upper Dirac cone has been correlated with the electron–phonon interaction by employing complementary electronic and vibrational spectroscopic techniques in ultra high vacuum ambient. K and Cs doping induces a significant rigid band shift and Dirac cone filling correlated with the neat formation of a π*-plasmon mode and a clear signature of electron–phonon interaction in the Raman spectra, while Na doping slightly influences the graphene electronic and vibrational response, fostered by adatom Na clustering.

The electrodeposition mechanism of gold nanoparticles (NPs) on pristine single walled carbon nanotubes (SWNTs) at high driving forces has been elucidated using the microcapillary electrochemical method. Here, a small capillary (internal diameter ∼50−100 μm) filled with a gold plating solution, and positioned so that the capillary meniscus makes contact with a two-dimensional SWNT random network, was used to record current−time transients. Nucleation and growth transients were observed in which the current increased with time to a maximum value beyond which the current decreased (planar diffusion regime). With increased driving force, the current maximum shifted dramatically to increasingly shorter times. Atomic force microscopy (AFM) analysis indicated that this was not due to significant differences in NP growth rates, but rather to increased densities of NPs formed at more cathodic potentials. Detailed microscopic analysis showed that the size of the NPs initially increased with deposition time and the particle surface coverage was constant. However, at the highest driving forces the NP density decreased with deposition time and AFM revealed the presence of both larger and smaller particles at long times. This was attributed to electrochemically induced Ostwald ripening, whereby larger particles grow at the expense of smaller ones. As NP nucleation and growth on SWNT two dimensional network electrodes is highly directional and enforced in particular locations, it is inappropriate to analyze electrochemical data using conventional models. There is thus a need to complement chronoamperometric measurements with high resolution microscopy to fully interpret nucleation on complex electrode surfaces.

Aim:This study aimed to investigate the incidence of BRAFmutation in cutaneous melanoma in the Ukrainian population with respect to clinical and histopathological data. Materials & methods:This single-center retrospective cohort study enrolled 299 primary CM with known BRAFstatus assessed by RT-PCR. Results:The overall BRAFmutation rate was 56.5% in CM and demonstrated a link with the younger age (p < 0.001), anatomical site (p < 0.001) and histological type of CM (p = 0.022). BRAF-positive CM possessed a slightly higher mitotic rate (p = 0.015) and Breslow thickness (p = 0.028) but did not relate to tumor-infiltrating lymphocytes. Conclusion:The high rate of BRAFmutations in CM patients in the Ukrainian cohort was associated with superficial spreading histology, higher depth of invasion and proliferation.

The effect of ion irradiation on magnetic properties of films of the ferromagnetic CoPt alloy fabricated by electron-beam evaporation has been studied. It is found that the coercive force decreases and the lateral component of the easy-magnetization axis increases as the He+ion fluence increases from 1 × 1013to 1 × 1016cm–2. It is shown by magnetic-force microscopy and the Mandelstam–Brillouin spectroscopy that the formation of isolated circle domains which are magnetic skirmions in the CoPt layer is activated at certain ion-irradiation fluence (3 × 1014cm–2).

Topological semimetals in crystals with a chiral structure (which possess a handedness due to a lack of mirror and inversion symmetries) are expected to display numerous exotic physical phenomena, including fermionic excitations with large topological charge1, long Fermi arc surface states2,3, unusual magnetotransport4and lattice dynamics5, as well as a quantized response to circularly polarized light6. So far, all experimentally confirmed topological semimetals exist in crystals that contain mirror operations, meaning that these properties do not appear. Here, we show that AlPt is a structurally chiral topological semimetal that hosts new four-fold and six-fold fermions, which can be viewed as a higher spin generalization of Weyl fermions without equivalence in elementary particle physics. These multifold fermions are located at high symmetry points and have Chern numbers larger than those in Weyl semimetals, thus resulting in multiple Fermi arcs that span the full diagonal of the surface Brillouin zone. By imaging these long Fermi arcs, we experimentally determine the magnitude and sign of their Chern number, allowing us to relate their dispersion to the handedness of their host crystal. AlPt is shown to be a chiral topological material with four-fold and six-fold degeneracies in the band structure. Fermi arc edge states span the whole Brillouin zone and their dispersion enables identification of the handedness of the chiral material.

This paper examines the influence of etching regimes on the reflectance of black silicon formed by Ni-assisted chemical etching. Black silicon exhibits properties of high light absorptance. The measured minimum values of the reflectance (R-min) of black silicon with thickness of 580 nm formed by metal-assisted chemical etching (MACE) for 60 minutes at 460 lx illumination were 2,3% in the UV region (200–400 nm), 0,5% in the visible region (400–750 nm) and 0,3% in the IR region (750–1300 nm). The findings showed that the reflectance of black silicon depends on its thickness, illumination and treatment duration. In addition, the porosity and refractive index were calculated.

The fission yeast Schizosaccharomyces japonicuscan switch from yeast to filamentous growth. This study shows that its hyphae are unusual, as they lack Spitzenkörper, remain mononuclear, and divide fully. It provides a description of the transition, which involves an increase in cytoskeletal rates and a shift from symmetric to asymmetric growth and cell division.

The major breakthroughs in understanding of topological materials over the past decade were all triggered by the discovery of the Z2-type topological insulator—a type of material that is insulating in its interior but allows electron flow on its surface. In three dimensions, a topological insulator is classified as either ‘strong’ or ‘weak’1,2, and experimental confirmations of the strong topological insulator rapidly followed theoretical predictions3–5. By contrast, the weak topological insulator (WTI) has so far eluded experimental verification, because the topological surface states emerge only on particular side surfaces, which are typically undetectable in real three-dimensional crystals6–10. Here we provide experimental evidence for the WTI state in a bismuth iodide, β-Bi4I4. Notably, the crystal has naturally cleavable top and side planes—stacked via van der Waals forces—which have long been desirable for the experimental realization of the WTI state11,12. As a definitive signature of this state, we find a quasi-one-dimensional Dirac topological surface state at the side surface (the (100) plane), while the top surface (the (001) plane) is topologically dark with an absence of topological surface states. We also find that a crystal transition from the β-phase to the α-phase drives a topological phase transition from a nontrivial WTI to a normal insulator at roughly room temperature. The weak topological phase—viewed as quantum spin Hall insulators stacked three-dimensionally13,14—will lay a foundation for technology that benefits from highly directional, dense spin currents that are protected against backscattering.

Triangular, concave-base ‘Streletskian points’ are documented in several assemblages from the Kostёnki complex of Upper Palaeolithic sites in south-western Russia. Some of these assemblages have been argued to evidence very early modern human occupation of Eastern Europe. However, Streletskian points are also recorded from younger contexts, notably at Kostёnki 11, where examples are attributed both to Layer V and the stratigraphically higher Layer III. The apparent relatively young age of Layer III has led some to view it as the latest manifestation of the Streletskian, although its assemblage has also been compared to the non-Streletskian Layer I of Kostёnki 8, with the two described together as the Anosovka-Tel’manskaya Culture.Radiocarbon dates of 24–23,000 bp(c.28,500–27,000 cal bp) for a wolf burial associated with Layer III of Kostёnki 11 confirm the layer as younger than other Streletskian assemblages at Kostёnki. New radiocarbon dates for Kostёnki 8 Layer I show that the two layers are broadly contemporary, and that both are close in age to assemblages of Kostёnki’s (Late Gravettian) Kostёnki-Avdeevo Culture. In the light of these new radiocarbon dates the context of the Streletskian point from Kostёnki 11 Layer III is considered. Although firm conclusions are not possible, unresolved stratigraphic problems and the lack of technological context for this single artefact at the very least leave a question mark over its association with other material from the layer.

A single-server queueing system with an infinite buffer is considered. The service of a customer is possible only in the presence of at least one unit of energy, and during the service the number of available units decreases by one. New units of energy arrive in the system at random instants of time if the finite buffer for maintenance of energy is not full. Customers are impatient and leave the system without service after a random amount of waiting time. Such a queueing system describes, e.g., the operation of a sensor node which harvests energy necessary for information transmission from the environment. Aiming to minimize the loss of customers due to their impatience (and maximize the throughput of the system), a new strategy of control by providing service is proposed. This strategy suggests that service temporarily stops if the number of customers or units of energy in the system becomes zero. The server is switched off (is in sleep mode) for some time. This time finishes (the server wakes up) if both the number of customers in the buffer and the number of energy units reach some fixed threshold values or when the number of energy units reaches some threshold value and there are customers in the buffer. Arrival flows of customers and energy units are assumed to be described by an independent Markovian arrival process. The service time has a phase-type distribution. The system behavior is described by a multi-dimensional Markov chain. The generator of this Markov chain is derived. The ergodicity condition is presented. Expressions for key performance measures are given. Numerical results illustrating the dependence of a customer’s loss probability on the thresholds defining the discipline of waking up the server are provided. The importance of the account of correlation in arrival processes is numerically illustrated.

This paper proposes a redundancy-reduction (compression) method for the remote Earth-probing data of gray-scale images. This method is based on an image-restructuring prototype and principal component analysis. A technique is developed for analyzing the quality of the redundancy-reduction method for remote-probing data, based on which the method developed here is compared with existing data-compression standards used with remote probing. It is shown that the results of this data-redundancy-reduction method have better quality than those of analogous methods. Particular recommendations are formulated for using this method.

The effect of protons exposure on the diffuse reflectance spectra of the zinc oxide with different shape particles has been investigated. Particles were micro-, nanocrystals, star and flower shape particles. The synthesis of the particles was carried out by the hydrothermal method using zinc acetate chemicals. The surface morphology, surface area and crystal structure of the particles have been investigated. Evaluating the changes in spectral reflectance it was found that the radiation stability of the micro particles is higher than the radiation stability of the other nanostructured particles. The high stability of the micro particles optical properties is due to the effect of low accumulation of radiation-induced defects.

Recent advances in wireless communication networks led to possibility of multi-rate transmission of information. In terms of queueing theory this means that a group of requests from users can be processed simultaneously in parallel and processing of the whole group is considered finished if processing of all individual requests belonging to this group is over. In this paper we consider a novel retrial queueing model where the requests (customers) are served in groups of finite size which are formed during a period of random length that is called admission period. The problem of choosing the optimal length of admission period and optimal size of the groups is faced here under assumptions that the input flow of customers is described by a Markovian Arrival Process (MAP), length of admission period and individual service time have phase type distribution. Advantages of the proposed customers service discipline are numerically illustrated.

A novel customer batch service discipline for a single server queue is introduced and analyzed. Service to customers is offered in batches of a certain size. If the number of customers in the system at the service completion moment is less than this size, the server does not start the next service until the number of customers in the system reaches this size or a random limitation of the idle time of the server expires, whichever occurs first. Customers arrive according to a Markovian arrival process. An individual customer’s service time has a phase-type distribution. The service time of a batch is defined as the maximum of the individual service times of the customers which form the batch. The dynamics of such a system are described by a multi-dimensional Markov chain. An ergodicity condition for this Markov chain is derived, a stationary probability distribution of the states is computed, and formulas for the main performance measures of the system are provided. The Laplace–Stieltjes transform of the waiting time is obtained. Results are numerically illustrated.

We consider the M/M/1 → •, M/M/1/0 type retrial queueing system with state dependent parameters. The intensities of input, service (at both stations) and retrials depend in an arbitrary way on the current number of customers in the orbit. Because operation of the first station of this tandem does not depend on the state of the second station, analysis of the system is implemented in two steps. At the first step, we compute the marginal distribution of the states of the first station in a simple form. At the second step, analytical formulas are presented for computation of the steady state-distribution of the tandem. Formulas for computing the most important performance measures of the system are derived. Results can be used for solving various problems of optimal control by the system operation.

The study has reviled the benefits of amaranth groat flour application into wheat bread making towards enhancing the technological efficiency and the quality of the bread, prolonging the freshness of the product without artificial improvers involved in the formulations. Paying attention to textural characteristics of the wheat-amaranth bread during its shelf-life, amaranth groat flour as a derived product of amaranth grain processing presented a positive impact on the change of textural properties of the bread crumb during wheat-amaranth bread shelf-life. The effect of ranging 5–30% substitution of common wheat high-grade flour by the amaranth flour derived from partially defatted amaranth grain was investigated and the complex organoleptic quality of the bread made of the composite flour reached the highest level at 15% of the amaranth flour in the formulation. The technological parameters of bread making such as the duration of proofing, shape stability, specific volume, crumb porosity, baking and drying losses, when wheat high-grade flour was partially replaced by the amaranth grain-derived milling product showed better performance for the bread enriched by the amaranth flour at higher substitution level approving the wider application of the pseudocereal flour in the food industry. The freshness of the bread made of the composite flour is related to the textural characteristics of the crumb which tend to change drastically due to styling. The amaranth groat flour application into the wheat bread formulation led to changes in compressive force and tension of the crumb, the stress value at relative strain ε = 25%, the elastic modulus, and the statical elastic hysteresis index. The resulting application of the amaranth groat flour into bread formulation allowed to ensure a 2-2.5-fold increase in the freshness of wheat bread with a 15% amaranth groat flour content when providing higher comprehensive quality of the product.

Exfoliated magnetic 2D materials enable versatile tuning of magnetization, e.g., by gating or providing proximity-induced exchange interaction. However, their electronic band structure after exfoliation has not been probed, presumably due to their photochemical sensitivity. Here, we provide micrometer-scale angle-resolved photoelectron spectroscopy of the exfoliated intralayer antiferromagnet MnPS3above and below the Néel temperature down to one monolayer. Favorable comparison with density functional theory calculations enables identifying the orbital character of the observed bands. Consistently, we find pronounced changes across the Néel temperature for bands consisting of Mn 3d and 3p levels of adjacent S atoms. The deduced orbital mixture indicates that the superexchange is relevant for the magnetic interaction. There are only minor changes between monolayer and thicker films, demonstrating the predominant 2D character of MnPS3. The novel access is transferable to other MPX3materials (M: transition metal, P: phosphorus, X: chalcogenide), providing several antiferromagnetic arrangements.

Planning and design of cellular networks is associated with the creation of traffic models for the transfer of signal using schemes with priorities within which assess the probability parameters of quality of service is performed. The study of these parameters is associated with the creation of a simulation model and an algorithm of broadband handover.

Although best known for its spectacular Gravettian features and art, the open-air site of Kostenki 1 (located near Voronezh on the Don River [Russian Federation]) also has played an important role in the study of the early Upper Paleolithic (EUP) of Eastern Europe. New excavations at Kostenki 1 were undertaken in 2004–2012 with a focus on the EUP layers (Layers III–V), which represent temporal zones of recurring occupation, buried in low-energy slope deposits (5% slope). Soils formed during periods of increased surface stability. A new set of radiocarbon estimates on wood charcoal indicates that Layer III dates between 33,000 and 38,000cal BP. Layer V underlies the CI tephra (~40,000cal BP), which is redeposited and identified only by microscopic analysis of sediment samples in most of the (downslope) areas of the site excavated during 2004–2012. Large and medium mammal remains recovered from the EUP layers include mammoth, horse, reindeer, arctic fox, and wolf, and taphonomic analyses indicate that carcasses were processed at the site. All EUP layers yielded artifacts typical of the East European Streletsindustry (e.g., bifaces, side-scrapers), but earlier excavation (1948–1953) of Layer III also produced diagnostic Aurignacian artifacts (e.g., carinated scrapers, retouched bladelets). The new chronology for Layer III suggests an association between the Aurignacian of the central East European Plain and the warm intervals (GI 8–GI 7) following the HE4 cold period (~38,000–40,000cal BP).

Multicellular groups can arise either by clonal development (cells stay together following cell division) or by aggregation (single cells come together). For decades it has been assumed that clonal development facilitates evolution of multicellularity; however, this hypothesis has never been directly tested.Here budding yeast populations that can form either clonal (snowflake yeast, ace2Δ) or aggregative (flo1Δ) multicellular groups were allowed to evolve for hundreds of generations. Genomic analyses and mathematical modeling show that clonal development drives the transition to multicellularity more efficiently than aggregation.This study experimentally establishes for the first time how and why clonal development is the widespread strategy for the evolution of complex multicellular organisms and sets a robust framework for understanding multicellular evolution.

Body axes establishment during animal embryogenesis often relies on the intrinsic asymmetry generated early on in the oocyte by the Wnt/β-catenin pathway. However, it's still unclear how the initial asymmetry arises.Here imaging experiments show that in starfish embryos, Disheveled (Dvl), an essential cytoplasmic transducer of Wnt signaling, becomes polarized at the vegetal pole via a dissolution-condensation mechanism coupled to meiotic progression. The authors further show that Dvl reformation is dependent on a maternally expressed Wnt signaling receptor Frizzled (Fzd1).This study identifies a novel link between the cell cycle and the body plan establishment and thus is relevant to a broad audience of developmental and evolutionary cell biologists.

Background Cleft lip, with or without cleft palate (CL±P), is the most common craniofacial anomaly in newborns. The incidence of CL±P varies among different ethnic populations and is presumed to be higher in developing countries. In the Middle East, the incidence has variably been reported as 0.3 to 2.19 per 1000 live births and is generally regarded as similar to Caucasians. There is currently no literature reporting the incidence of clefting in Palestinians living in the territories. Reports from Palestinian populations in Israel and Jordan infer an incidence of 1.39 per 1000 live births. However, the reported incidence in stable populations may not reflect the actual incidence of clefting in the territories.Methods This is a retrospective study examining all newborn records at Makassed Maternity Hospital in Jerusalem between January 1,1986, and December 12, 1995. Data were collected by the senior author (A.D.) and interpreted by coauthors. Frequencies were established based on the number of isolated and nonisolated CL±P born during this time period.Results During the 10-year period from January 1, 1986, to December 12, 1995, there were 33,239 live births. Among these births, there were 35 isolated and nonisolated combined CL±P born (1.05/1000 live births).Conclusions Based on this limited data set from a single, tertiary referral hospital, we conclude that the prevalence rate of CL±P among a Palestinian population may be less than that reported in surrounding areas. However, more broadly based studies using nationalized birth registries are required to determine an accurate prevalence rate of CL±P among Palestinians.

The photoluminescence spectra of erbium centers in SiO2films with ion-synthesized silicon nanoclusters under nonresonant excitation were investigated. Erbium was introduced into thermal SiO2films by ion implantation. The dependences of photoluminescence intensity on the dose, the order of ion implantation of Si and Er, the annealing temperature, and additional Ar+and P+ion irradiation regimes, i.e., factors determining the influence of radiation damage and doping on sensitization of erbium luminescence by silicon nanoclusters, were determined. It was found that the sensitization effect and its amplification due to doping with phosphorus are most pronounced under the conditions where nanoclusters are amorphous. The quenching of photoluminescence due to radiation damage in this case manifests itself to a lesser extent than for crystalline nanoclusters. The role of various factors in the observed regularities was discussed in the framework of the existing concepts of the mechanisms of light emission and energy exchange in the system of silicon nanoclusters and erbium centers.

•A queueing model consisting of two multi-server queueing systems is analyzed.•The queueing systems compete to the common flow of customers via the rating mechanism.•Multi-dimensional Markov chain describing the behavior of the queueing model is analysed.•Performance measures of the queueing model and cost criteria for both systems are computed.•Numerical results useful in decision making about the reasonability of establishing new business are presented.

The appearance and progression of idiopathic scoliosis (IS) are considered to be the result of an inequality of the spinal column and spinal cord longitudinal growths. Consequently, normal afferent input from spinal cord elements to the highest parts of the central nervous system (CNS) is altered even by a minor hyperextension of spinal cord structures. De-afferentiation leads to forming a hyperactive deterministic structure and inadequacy of neurohumoral processes of regulation in thalamus–hypothalamus–hypophysis. The resulting neurohumoral abnormalities could be defined in experimental models via patients' blood serum testings.

Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30–70 μm, filled with solution containing a redox-active mediator (FcTMA+((trimethylammonium)methylferrocene), Fe(CN)64–, or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler–Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k0, up to ca. 1 cm s–1can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA+/2+electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k0> 2 ± 1 cm s–1). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale.

Concise syntheses of the natural products cavicularin (ten steps) and riccardin C (seven steps) are reported. Key features of the new synthetic route are a convergent strategy to assemble acyclic precursors and a sequence of regioselective reduction and halogenation steps to facilitate Wittig macrocyclisation and transannular ring contraction reactions.