1,973 research outputs found
Fast post-adiabatic waveforms in the time domain: Applications to compact binary coalescences in LIGO and Virgo
We present a computationally efficient (time-domain) multipolar waveform model for quasi-circular spin-aligned compact binary coalescences. The model combines the advantages of the numerical-relativity informed, effective-one-body (EOB) family of models with a post-adiabatic solution of the equations of motion for the inspiral part of the two-body dynamics. We benchmark this model against other state-of-the-art waveforms in terms of efficiency and accuracy. We find a speed-up of one to two orders of magnitude compared to the underlying time-domain EOB model for the total mass range . More specifically, for a low total-mass system, such as a binary neutron star with equal masses of , like GW170817, the computational speedup is around 100 times; for an event with total mass and mass ratio , like GW190412, the speedup is by a factor of , while for a binary system of comparable masses and total mass of , like GW150914, it is by a factor of . We demonstrate that the new model is extremely faithful to the underlying EOB model with unfaithfulness less than across the entire applicable region of parameter space. Finally, we present successful applications of this new waveform model to parameter estimation studies and tests of general relativity
Embedding a Carbon Nanotube across the Diameter of a Solid State Nanopore
A fabrication method for positioning and embedding a single-walled carbon nanotube (SWNT) across the diameter of a solid state nanopore is presented. Chemical vapor deposition (CVD) is used to grow SWNTs over arrays of focused ion beam (FIB) milled pores in a thin silicon nitride membrane. This typically yields at least one pore whose diameter is centrally crossed by a SWNT. The final diameter of the FIB pore is adjusted to create a nanopore of any desired diameter by atomic layer deposition, simultaneously embedding and insulating the SWNT everywhere but in the region that crosses the diameter of the final nanopore, where it remains pristine and bare. This nanotube-articulated nanopore is an important step towards the realization of a new type of detector for biomolecule sensing and electronic characterization, including DNA sequencing.Engineering and Applied SciencesMolecular and Cellular BiologyPhysic
Percutaneous Transhepatic Bile Duct Ablation with n-Butyl Cyanoacrylate in the Treatment of a Biliary Complication after Split Liver Transplantation
Biliary complications continue to be a major cause of morbidity after split-liver transplantation (SLT). In this report we describe an uncommon late biliary complication. One year after SLT the patient showed an intrahepatic bile dicy dilatation with severe cholangitis episodes. The segmentary bile duct of hepatic segment VI-VII draining in the left duct was unidentified and tied at the time of the in situ split-liver procedure. We perform a permanent obliteration of the dilated intrahepatic ducts by a percutaneous embolization using an n-butyl cyanoacrylate (NABC). The management of biliary complications after SLT requires a multidisciplinary approach. The use of NBCA in obliteration of a dilated bile duct seems to be a safe procedure with good results providing a less invasive option than hepatic resection and decreasing the morbidity associated with chronic external biliary drainage. Further studies are needed to determine whether this approach is effective and safe and whether it could reduce hospital stay and cost
First-principles equation of state of CHON resin for inertial confinement fusion applications
A wide-range (0 to 1044.0 g/cm3 and 0 to 109 K) equation-of-state (EOS) table for a CH1.72O0.37N0.086 quaternary compound has been constructed based on density-functional theory (DFT) molecular-dynamics (MD) calculations using a combination of Kohn-Sham DFT MD, orbital-free DFT MD, and numerical extrapolation. The first-principles EOS data are compared with predictions of simple models, including the fully ionized ideal gas and the Fermi-degenerate electron gas models, to chart their temperature-density conditions of applicability. The shock Hugoniot, thermodynamic properties, and bulk sound velocities are predicted based on the EOS table and compared to those of C-H compounds. The Hugoniot results show the maximum compression ratio of the C-H-O-N resin is larger than that of CH polystyrene due to the existence of oxygen and nitrogen; while the other properties are similar between CHON and CH. Radiation hydrodynamic simulations have been performed using the table for inertial confinement fusion targets with a CHON ablator and compared with a similar design with CH. The simulations show CHON outperforms CH as the ablator for laser-direct-drive target designs
WORKING TOGETHER: EDUCATION, RESEARCH AND DEVELOPMENT FOR 5G NETWORKS
In the new world of globalization of ideas and mobility difficulties in knowledge diffusion still remains. The effectiveexchange of experiences and skills in new generation networks is not guaranteed by the enormous potentialsofinternetworking systems and devices. Conceptual model for performance modeling and evaluation of multiservicenetworks has been major interest for mobile networks providers. It is essential to assess the performance ofmobile system architectures in order to identify where potential bottlenecks and data packet blocking probabilityare possible to occur. Educational platforms, new simulations opportunities represent a good opportunity to reducethe digital divide and to ensure faster and higher communication trends. Several universities and companies arecurrently involved in using educational platforms to provide better results. Conceptual model for teletrafficengineering in educational platform and applications focuses on some important aspects: tutorials, exercise,simulations, and expectation values of parameters, testing and estimation of students work. In the same time thesame model is very appropriate for simulation of network management for the new generation networks. Thiseducational platform for academics, students and researchers, puts together some of the critical aspects ofdistributed systems and their characteristics, parameters and probability of blocking.</p
Carfilzomib-lenalidomide-dexamethasone vs lenalidomide-dexamethasone in relapsed multiple myeloma by previous treatment
Carfilzomib, a proteasome inhibitor, is approved as monotherapy and in combination with dexamethasone or lenalidomide-dexamethasone (Rd) for relapsed or refractory multiple myeloma. The approval of carfilzomib-lenalidomide-dexamethasone (KRd) was based on results from the randomized, phase 3 study ASPIRE (NCT01080391), which showed KRd significantly improved progression-free survival (PFS) vs Rd (median 26.3 vs 17.6 months; hazard ratio (HR)=0.690; P=0.0001). This subgroup analysis of ASPIRE evaluated KRd vs Rd by number of previous lines of therapy and previous exposure to bortezomib, thalidomide or lenalidomide. Treatment with KRd led to a 12-month improvement in median PFS vs Rd after first relapse (HR 0.713) and a 9-month improvement after 2 previous lines of therapy (HR 0.720). Treatment with KRd led to an approximate 8-month improvement vs Rd in median PFS in bortezomib-exposed patients (HR 0.699), a 15-month improvement in thalidomide-exposed patients (HR 0.587) and a 5-month improvement in lenalidomide-exposed patients (HR 0.796). Objective response and complete response or better rates were higher with KRd vs Rd, irrespective of previous treatment. KRd had a favorable benefit-risk profile and should be considered an appropriate treatment option for patients with 1 or 2 previous lines of therapy and those previously exposed to bortezomib, thalidomide or lenalidomide
Моделирование спектров излучения импульсных рентгеновских трубок
Наведені результати моделювання спектрів гальмівного рентгенівського випромінювання в імпульсних трубках рефлекторного та трансмісійного типу, які враховують конструкцію анодно-катодного вузла, матеріали анода та вихідного вікна, змінювання анодної напруги і анодного струму під час імпульсу рентгенівського випромінювання в трубках з вибуховою емісією, а також кут нахилу траєкторій електронів до поверхні анода. З використанням програми MathCAD, в якій експериментальні залежності коефіцієнтів поглинання матеріалами анода і вихідного вікна від енергії фотонів, вольт-секундні та ампер-секундні характеристики анодної напруги та струму інтерполювалися кубічними та квадратичними сплайнами, а залежність константи Томсона-Віддінгтона від анодної напруги апроксимувалися експонентою, розраховані миттєві та сумарні (за тривалість імпульсу) спектри однонаправленого осьового) напрямку випромінювання і для різних кутів випромінювання, які утворюють панорамне тіньове зображення контрольованих матеріалів або виробів. Конкретні приклади змодельованих сумарних спектрів наведені для рефлекторних трубок з анодом у вигляді конусної поверхні і катода, утвореного одиночною загостреною з внутрішньої сторони шайбою, а в трубках трансмісійного типу анод має форму плоскої фольги.The results of modeling the spectra of X-ray braking radiation of pulsed tubes of reflex and transmission type have been shown. They consider the design of anode-cathode unit, material of anode and outlet window, changing of the anode voltage and anode current during the pulse in tubes with explosive emission and also angle between trajectories of electrons and anode surface. Using MathCAD software there were calculated instant and total (per pulse) spectra of single directional (axial) radiation and radiation for different angles, that form a panorama shadow image of controlled materials or products. The experimental dependence of the absorption of the anode material and the outlet window and the photon energy, volt-second and ampere-second characteristics of anode voltage and current were interpolated by cubic and quadratic splines. The dependence of Thomson-Viddington constants and anode voltage was exponential approximated. Specific examples of simulated total spectra of reflex tubes were shown with an anode as conical surface and the cathode formed by a solitary sharp washer on the inside, and transmission type anode tubes is shaped like a flat foil.Приведены результаты моделирования спектров тормозного рентгеновского излучения в импульсных трубках рефлекторного и трансмиссионного типа, которые учитывают конструкцию анодно-катодного узла, материалы анода и выпускного окна, изменения анодного напряжения и анодного тока в течение длительности импульса в трубках с взрывной эмиссией, а также угол наклона траекторий электронов к поверхности анода. С использованием программы MathCAD, в которой экспериментальные зависимости коэффициентов поглощения материалами анода и выпускного окна от энергии фотонов, вольт-секундные и ампер-секундные характеристики анодного напряжения и тока интерполировались кубическими и квадратичными сплайнами, а зависимость константы Томсона-Виддингтона от анодного напряжения аппроксимировались экспонентой. Рассчитаны мгновенные и суммарные (за длительность импульса) спектры однонаправленного (осевого) направления излучения и для разных углов излучения, которые образуют панорамное теневое изображение контролируемых материалов или изделий. Конкретные примеры смоделированных суммарных спектров приведены для рефлекторных трубок с анодом в виде конусной поверхности и катода, образованного одиночной заостренной с внутренней стороны шайбой, а в трубках трансмиссионного типа анод имеет форму плоской фольги
Transition of EMRIs through resonance: Corrections to higher order in the on-resonance flux modification
Extreme mass ratio in-spirals (EMRIs) are candidate events for gravitational
wave detection in the millihertz range (by detectors like LISA and eLISA).
These events involve a stellar-mass black hole, or a similar compact object,
descending in the gravitational field of a supermassive black hole, eventually
merging with it. Properties of the in-spiralling trajectory away from resonance
are well known and have been studied extensively, however little is known about
the behaviour of these binary systems at resonance, when the radial and lateral
frequencies of the orbit become commensurate. We describe the two existing
models, the instantaneous frequency approach used by Gair, Bender, and Yunes,
and the standard two timescales approach implemented by Flanagan and Hinderer.
In both cases, the exact treatment depends on the modelling of the
gravitational self-force, which is currently not available. We extend the
results in Gair, Bender and Yunes to higher order in the on-resonance flux
modification, and argue that the instantaneous frequency approach is also a
valid treatment of the resonance problem. The non-linear differential equations
which arise in treating resonances are interesting from a mathematical view
point. We present our algorithm for perturbative solutions and the results to
third order in the infinitesimal parameter, and discuss the scope of this
approach
Geminin Is Required for Zygotic Gene Expression at the Xenopus Mid-Blastula Transition
In many organisms early development is under control of the maternal genome and zygotic gene expression is delayed until the mid-blastula transition (MBT). As zygotic transcription initiates, cell cycle checkpoints become activated and the tempo of cell division slows. The mechanisms that activate zygotic transcription at the MBT are incompletely understood, but they are of interest because they may resemble mechanisms that cause stem cells to stop dividing and terminally differentiate. The unstable regulatory protein Geminin is thought to coordinate cell division with cell differentiation. Geminin is a bi-functional protein. It prevents a second round of DNA replication during S and G2 phase by binding and inhibiting the essential replication factor Cdt1. Geminin also binds and inhibits a number of transcription factors and chromatin remodeling proteins and is thought to keep dividing cells in an undifferentiated state. We previously found that the cells of Geminin-deficient Xenopus embryos arrest in G2 phase just after the MBT then disintegrate at the onset of gastrulation. Here we report that they also fail to express most zygotic genes. The gene expression defect is cell-autonomous and is reproduced by over-expressing Cdt1 or by incubating the embryos in hydroxyurea. Geminin deficient and hydroxyurea-treated blastomeres accumulate DNA damage in the form of double stranded breaks. Bypassing the Chk1 pathway overcomes the cell cycle arrest caused by Geminin depletion but does not restore zygotic gene expression. In fact, bypassing the Chk1 pathway by itself induces double stranded breaks and abolishes zygotic transcription. We did not find evidence that Geminin has a replication-independent effect on transcription. We conclude that Geminin is required to maintain genome integrity during the rapid cleavage divisions, and that DNA damage disrupts zygotic gene transcription at the MBT, probably through activation of DNA damage checkpoint pathways
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