A modified standard embedding with jumps in nonlinear optimization

The paper deals with a combination of pathfollowing methods (embedding approach) and feasible descent direction methods (so-called jumps) for solving a non-linear optimization problem with equality and inequality constraints. Since the method that we propose here uses jumps from one connected component to another one, more than one connected component of the solution set of the corresponding one-parametric problem can be followed numerically. It is assumed that the problem under consideration belongs to a generic subset which was introduced by Jongen, Jonker and Twilt. There already exist methods of this type for which each starting point of a jump has to be an endpoint of a branch of local minimizers. In this paper the authors propose a new method by allowing a larger set of starting points for the jumps which can be constructed at bifurcation and turning points of the solution set. The topological properties of those cases where the method is not successful are analyzed and the role of constraint qualifications in this context is discussed. Furthermore,this new method is applied to a so-called modified standard embedding which is a particular construction without equality constraints. Finally, an algorithmic version of this new method as well as computational results are presented

Integration of highly crystalline C8-BTBT thin-films into simple logic gates and circuits

Highly crystalline organic thin films possess the charge carrier mobilities needed for high-performance, low-cost flexible electronics. However, only few reports exist that show the integration of these films into short-channel organic circuits. This work describes the integration of highly crystalline layers of the thermally and chemically fragile small molecule C8-BTBT. Thin films of this material are processed by a combination of zone-casting and homoepitaxial vacuum evaporation and display an average charge carrier mobility of 7.5 cm2/V in long channel transistors. The integration of these films into a circuit technology based on a 5 μm channel-length bottom-gate bottom-contact transistor topology results in inverters with gains up to 40 as well as a robust 19-stage ring oscillator. This circuit requires the simultaneous operation of 80 TFTs and displays a stage delay of 40 μs, resulting in an operating frequency of 630 Hz at an operating voltage of 10 V. With the help of circuit modelling, we quantify the relationship between the speed of ring oscillators and the contact resistance of individual transistors. Indeed, the successful integration of highly-crystalline layers with high intrinsic mobility stresses the need for advances in contact engineering

Sensitivities of cloud radiative effects to large-scale meteorology and aerosols from global observations

The radiative effects of clouds make a large contribution to the Earth's energy balance, and changes in clouds constitute the dominant source of uncertainty in the global warming response to carbon dioxide forcing. To characterize and constrain this uncertainty, cloud-controlling factor (CCF) analyses have been suggested that estimate sensitivities of clouds to large-scale environmental changes, typically in cloud-regime-specific multiple linear regression frameworks. Here, local sensitivities of cloud radiative effects to a large number of controlling factors are estimated in a regime-independent framework from 20 years (2001–2020) of near-global (60° N–60°S) satellite observations and reanalysis data using statistical learning. A regularized linear regression (ridge regression) is shown to skillfully predict anomalies of shortwave (R2=0.63) and longwave cloud radiative effects (CREs) (R2=0.72) in independent test data on the basis of 28 CCFs, including aerosol proxies. The sensitivity of CREs to selected CCFs is quantified and analyzed. CRE sensitivities to sea surface temperature and estimated inversion strength are particularly pronounced in low-cloud regions and generally in agreement with previous studies. The analysis of CRE sensitivities to three-dimensional wind field anomalies reflects the fact that CREs in tropical ascent regions are mainly driven by variability of large-scale vertical velocity in the upper troposphere. In the subtropics, CRE is sensitive to free-tropospheric zonal and meridional wind anomalies, which are likely to encapsulate information on synoptic variability that influences subtropical cloud systems by modifying wind shear and thus turbulence and dry-air entrainment in stratocumulus clouds, as well as variability related to midlatitude cyclones. Different proxies for aerosols are analyzed as CCFs, with satellite-derived aerosol proxies showing a larger CRE sensitivity than a proxy from an aerosol reanalysis, likely pointing to satellite aerosol retrieval biases close to clouds, leading to overestimated aerosol sensitivities. Sensitivities of shortwave CREs to all aerosol proxies indicate a pronounced cooling effect from aerosols in stratocumulus regions that is counteracted to a varying degree by a longwave warming effect. The analysis may guide the selection of CCFs in future sensitivity analyses aimed at constraining cloud feedback and climate forcings from aerosol–cloud interactions using data from both observations and global climate models

NAC transcription factors ANAC087 and ANAC046 control distinct aspects of programmed cell death in the Arabidopsis columella and lateral root cap

Programmed cell death in plants occurs both during stress responses and as an integral part of regular plant development. Despite the undisputed importance of developmentally controlled cell death processes for plant growth and reproduction, we are only beginning to understand the underlying molecular genetic regulation. Exploiting the Arabidopsis thaliana root cap as a cell death model system, we identified two NAC transcription factors, the little-characterized ANAC087 and the leaf-senescence regulator ANAC046, as being sufficient to activate the expression of cell death-associated genes and to induce ectopic programmed cell death. In the root cap, these transcription factors are involved in the regulation of distinct aspects of programmed cell death. ANAC087 orchestrates postmortem chromatin degradation in the lateral root cap via the nuclease BFN1. In addition, both ANAC087 and ANAC046 redundantly control the onset of cell death execution in the columella root cap during and after its shedding from the root tip. Besides identifying two regulators of developmental programmed cell death, our analyses reveal the existence of an actively controlled cell death program in Arabidopsis columella root cap cells

Brightening of Long, Polymer-Wrapped Carbon Nanotubes by sp3^{3} Functionalization in Organic Solvents

The functionalization of semiconducting single-walled carbon nanotubes (SWNTs) with sp$^{3}$ defects that act as luminescent exciton traps is a powerful means to enhance their photoluminescence quantum yield (PLQY) and to add optical properties. However, the synthetic methods employed to introduce these defects are so far limited to aqueous dispersions of surfactant-coated SWNTs, often with short tube lengths, residual metallic nanotubes and poor film formation properties. In contrast to that, dispersions of polymer-wrapped SWNTs in organic solvents feature unrivaled purity, higher PLQY and are easily processed into thin films for device applications. Here, we introduce a simple and scalable phase-transfer method to solubilize diazonium salts in organic nonhalogenated solvents for the controlled reaction with polymer-wrapped SWNTs to create luminescent aryl defects. Absolute PLQY measurements are applied to reliably quantify the defect-induced brightening. The optimization of defect density and trap depth results in PLQYs of up to 4 % with 90 % of photons emitted through the defect channel. We further reveal the strong impact of initial SWNT quality and length on the relative brightening by sp$^{3}$ defects. The efficient and simple production of large quantities of defect-tailored polymer-sorted SWNTs enables aerosol-jet printing and spin-coating of thin films with bright and nearly reabsorption-free defect emission, which are desired for carbon nanotube-based near-infrared light-emitting devices

Band structure calculation and tunneling measurements in (BEDT-TTF)2X (X=I3, IAuI)

At about the same time when little proposed room-temperature superconductivity in organic polymers, it was suggested that the high-Tc of the more conventional A-15's is associated with their one-dimensional electronic band structure. When TTF-TCNQ was discovered in 1973, it was suggested that the electron-phonon coupling in this 1-D organic molecular crystal is responsible for the metal-to-insulator (Peierls) transition at 52 K2, and reducing λ will cause a crossover to a superconducting state. Since then, the electronic structure, the conduction mechanism, and the superconducting mechanism were subject to controversy. Therefore, it is of some importance to establish whether the electronic band structure, and conduction mechanism, are similar to those in more conventional metals, and whether the superconductivity mechanism is the normal BCS phonon-mediated interaction

High-mobility, trap-free charge transport in conjugated polymer diodes

Charge transport in conjugated polymer semiconductors has traditionally been thought to be limited to a low mobility regime by pronounced energetic disorder. Much progress has recently been made in advancing carrier mobilities in field-effect transistors through developing low-disorder conjugated polymers. However, in diodes these polymers have to date not shown much improved mobilities, presumably reflecting the fact that in diodes lower carrier concentrations are available to fill up residual tail states in the density of states. Here, we show that the bulk charge transport in low-disorder polymers is limited by water-induced trap states and that their concentration can be dramatically reduced through incorporating small molecular additives into the polymer film. Upon incorporation of the additives we achieve space-charge limited current characteristics that resemble molecular single crystals such as rubrene with high, trap-free SCLC mobilities up to 0.2 cm2/Vs and a width of the residual tail state distribution comparable to kBT.We gratefully acknowledge financial support the Engineering and Physical Sciences Research Council (EPSRC) through a Programme Grant (EP/M005141/1). M.N. acknowledges financial support from the European Commission through a Marie-Curie Individual Fellowship (EC Grant Agreement Number: 747461)

KIRA1 and ORESARA1 terminate flower receptivity by promoting cell death in the stigma of Arabidopsis

Flowers have a species-specific functional life span that determines the time window in which pollination, fertilization and seed set can occur. The stigma tissue plays a key role in flower receptivity by intercepting pollen and initiating pollen tube growth toward the ovary. In this article, we show that a developmentally controlled cell death programme terminates the functional life span of stigma cells in Arabidopsis. We identified the leaf senescence regulator ORESARA1 (also known as ANAC092) and the previously uncharacterized KIRA1 (also known as ANAC074) as partially redundant transcription factors that modulate stigma longevity by controlling the expression of programmed cell death-associated genes. KIRA1 expression is sufficient to induce cell death and terminate floral receptivity, whereas lack of both KIRA1 and ORESARA1 substantially increases stigma life span. Surprisingly, the extension of stigma longevity is accompanied by only a moderate extension of flower receptivity, suggesting that additional processes participate in the control of the flower's receptive life span

Particle-flow reconstruction and global event description with the CMS detector

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions