Proximal Methods for Elliptic Optimal Control Problems with Sparsity Cost Functional

First-order proximal methods that solve linear and bilinear elliptic optimal control problems with a sparsity cost functional are discussed. In particular, fast convergence of these methods is proved. For benchmarking purposes, inexact proximal schemes are compared to an inexact semismooth Newton method. Results of numerical experiments are presented to demonstrate the computational effectiveness of proximal schemes applied to infinite-dimensional elliptic optimal control problems and to validate the theoretical estimates.

Photocatalytic C–X borylation of aryl halides by hierarchical SiC nanowire-supported Pd nanoparticles

Hierarchical Si C nanowire-supported Pd nanoparticles showed high photocatalytic activity for the C–X(X = Br, I) borylation of aryl halides at 30 °C. The Si C/Pd Mott-Schottky contact enhances the rapid transfer of the photogenerated electrons from Si C to the Pd nanoparticles. As a result, the concentrated energetic electrons in the Pd nanoparticles can facilitate the cleavage of C–I or C–Br bonds, which normally requires high-temperature thermal processes. We show that the present Pd/Si C photocatalyst is capable of catalyzing the transformation of a large variety of aryl halides to their corresponding boronate esters under visible light irradiation, with excellent yields.

Multigrid Solution of an Elliptic Fredholm Partial Integro-Differential Equation with a Hilbert-Schmidt Integral Operator

An efficient multigrid finite-differences scheme for solving elliptic Fredholm partial integro-differential equations (PIDE) is discussed. This scheme combines a second-order accurate finite difference discretization of the PIDE problem with a multigrid scheme that includes a fast multilevel integration of the Fredholm operator allowing the fast solution of the PIDE problem. Theoretical estimates of second-order accuracy and results of local Fourier analysis of convergence of the proposed multigrid scheme are presented. Results of numerical experiments validate these estimates and demonstrate optimal computational complexity of the proposed framework.

Two-photon emission from a superlattice-based superconducting light-emitting structure

Superconductor-semiconductor hybrid devices can bridge the gap between solid-state-based and photonics-based quantum systems,enabling new hybrid computing schemes,offering increased scalability and robustness.One example for a hybrid device is the superconducting light-emitting diode(SLED).SLEDs have been theoretically shown to emit polarization-entangled photon pairs by utilizing radiative recombination of Cooper pairs.However,the twophoton nature of the emission has not been shown experimentally before.We demonstrate two-photon emission in a GaAs/AlGaAs SLED.Measured electroluminescence spectra reveal unique two-photon superconducting features below the critical temperature(Tc),while temperature-dependent photon-pair correlation experiments(g(2)(τ,T))demonstrate temperature-dependent time coincidences below Tc between photons emitted from the SLED.Our results pave the way for compact and efficient superconducting quantum light sources and open new directions in light-matter interaction studies.

Modeling and Numerical Solution of a Cancer Therapy Optimal Control Problem

A mathematical optimal-control tumor therapy framework consisting of radio- and anti-angiogenesis control strategies that are included in a tumor growth model is investigated. The governing system, resulting from the combination of two well established models, represents the differential constraint of a non-smooth optimal control problem that aims at reducing the volume of the tumor while keeping the radio- and anti-angiogenesis chemical dosage to a minimum. Existence of optimal solutions is proved and necessary conditions are formulated in terms of the Pontryagin maximum principle. Based on this principle, a so-called sequential quadratic Hamiltonian (SQH) method is discussed and benchmarked with an “interior point optimizer—a mathematical programming language” (IPOPT-AMPL) algorithm. Results of numerical experiments are presented that successfully validate the SQH solution scheme. Further, it is shown how to choose the optimisation weights in order to obtain treatment functions that successfully reduce the tumor volume to zero.

On Optimal Sparse-Control Problems Governed by Jump-Diffusion Processes

A framework for the optimal sparse-control of the probability density function of a jump-diffusion process is presented. This framework is based on the partial integro-differential Fokker-Planck (FP) equation that governs the time evolution of the probability density function of this process. In the stochastic process and, correspondingly, in the FP model the control function enters as a time-dependent coefficient. The objectives of the control are to minimize a discrete-in-time, resp. continuous-in-time, tracking functionals and its L2- and L1-costs, where the latter is considered to promote control sparsity. An efficient proximal scheme for solving these optimal control problems is considered. Results of numerical experiments are presented to validate the theoretical results and the computational effectiveness of the proposed control framework.

Linguistic Economy Applied to Programming Language Identifiers

Though many different readability metrics have been created, there still is no universal agreement defining readability of software source code. The lack of a clear agreement of source code readability has ramifications in many areas of the software development life-cycle, not least of which being software maintainability. We propose a measurement based on Linguistic Economy to bridge the gap between mathematical and behavioral aspects. Linguistic Economy describes efficiencies of speech and is generally applied to natural languages. In our study, we create a large corpus of words that are likely to be found in a programmer’s vocabulary, and a corpus of existing identifiers found in a collection of open-source projects. We perform a usage analysis to create a database from both of these corpora. Linguistic Economy suggests that words requiring less effort to speak are used more often than words requiring more effort. This concept is applied to measure how difficult program identifiers are to understand by extracting them from the program source and comparing their usage to the database. Through this process, we can identify source code that programmers find difficult to review. We validate our work using data from a survey where programmers identified unpleasant to review source files. The results indicate that source files identified as unpleasant to review source code have more linguistically complicated identifiers than pleasant programs.

西天山高压脉及主岩的氧同位素研究——古俯冲带深部流体及俯冲特征的启示

位于中国南天山的西天山高压变质带代表了伊犁-中天山与塔里木两个板块间古生代南天山洋的古俯冲混杂岩带。高压变质带内广泛发育高压脉。为探讨古俯冲深部流体来源及运移特点及板块俯冲特征，对高压脉和主岩的全岩及主要的高压变质矿物的氧同位素进行了分析。高压脉的δ^18O值变化于＋8．28‰与＋10．70‰之间，多数在＋9．50‰±1范围内。基性变质岩的主岩与高压脉具相似的氧同位素组成，变化于＋9．25‰～＋10．10‰之间。高压脉和主岩的全岩δ^18O值变化不大。高压脉与相邻主岩间、同一高压脉中间与边部间氧同位素组成的变化没有明显的规律，一般变化不大，对于大多数脉-主岩对，变化小于1‰。与全岩完全不同的是，单矿物氧同位素组成显示出很大的变化范围，石英、石榴石、绿辉石的δ^18O值分别为＋11．40‰～＋15．20‰，＋3．59‰-＋11．60‰和＋8．30‰～＋13．05‰，多硅白云母和蓝闪石δ^18O的变化较小，分别为＋10．00‰～＋11．10‰和＋9．26‰-＋9．94‰。榴辉质岩石中高压变质矿物间氧同位素分馏广泛不平衡。全岩氧同位素组成特征表明，俯冲带深部流体主体来自邻近主岩，外来流体对氧同位素贡献有限。单矿物氧同位素广泛不平衡特征可能指示古俯冲带俯冲板片的快速俯冲和折返以及部分外来流体的参与。

Origin of the deep fluids in the paleosubduction zones in western Tianshan:Evidence from Pb-and Sr-isotope compositions of high-pressure veins and host rocks

Fluids in the deep subduction zones play an important role in crust-mantle ex-change related to the subduction process. Identification of fluids origin, internal or external, can help us to evaluate the contribution of crust materials to mantle during this process. High-pressure veins, which developed in the western Tianshan HP-metamorphic belt extensively, are the direct products of the fluids in subduction zones. In western Tianshan, high-pressure veins and host rocks have overall Pb- and Sr-isotope compositions. At t = 340 Ma, the high-pressure metamorphic time, the ratios of 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb and 87Sr/86Sr of high pressure veins are 17.122―18.431, 15.477―15.611, 37.432―38.689 and 0.70529―0.70705, and are 17.605―17.834, 15.508―15.564, 37.080―38.145 and 0.70522―0.70685 for host rocks. However, high-pressure veins show a much larger variation in Pb-isotope composi-tions than host rocks. Plots of samples are distributed roughly along a line parallel to and far away from the Northern Hemisphere reference line (NHRL) on the plot of 206Pb/204Pb vs 207Pb/204Pb. On the plot of 206Pb/204Pb vs 208Pb/204Pb, plots of data are distributed nearby mid-ocean-ridge basalts (MORB) area or along a line parallel to and not far away from NHRL, which shows that the data plots are farther away from MORB and ocean island basalts (OIB) areas on the plot of 206Pb/204Pb vs 207Pb/204Pb than on the plot of 206Pb/204Pb vs 208Pb/204Pb. The compositions of Pb- and Sr-isotopes of these high-pressure metamorphic rocks are between that of enriched mantle 1(EMI) and of sediments or upper crust. A notable characteristic can be seen from plots of Pb-isotope ratio vs Pb-isotope ratio and 206Pb/204Pb vs 87Sr/86Sr that array of plots shows an evident tendency of mixture of two end members. Ratios of Rb/Ba, Ce/Pb, Nb/U and Ta/U of high-pressure veins and host rocks are between that of OIB or MORB and that of conti-nental crust, which indicates that continental crust materials probably have been incorporated into the rocks. The fluids in the paleosubduction zones in western Tianshan are mixtures of two sources, one originating from the devolatilzation of the host rocks with protolithes similar to ocean basalts from enriched mantle 1 (EMI), the other from the dehydration of subducted sediments.

Interbasinal marker intervals——A case study from the Jurassic basins of Kachchh and Jaisalmer, western India

The Kachchh Basin and the Jaisalmer Basin are two neighboring Mesozoic sedimentary basins at the western margin of the Indian craton. The Jurassic succession of the Kachchh Basin is more complete and more fossiliferous than that of the Jaisalmer Basin. Consequently, intrabasinal correlation of the sedimentary units has been possible in the Kachchh Basin, but not in the Jaisalmer Basin. However, some marker beds existing in the Kachchh Basin can be recognized also in the Jaisalmer Basin. Ammonite evidence shows that they are time-equivalent. The following four units form marker intervals in both basins: (1) the pebbly rudstone unit with Isastrea bernardiana and Leptosphinctes of the Kaladongar Formation (Kachchh Basin) and the Isastrea bernardiana-bearing rudstone of the Jaisalmer Formation (Jaisalmer Basin) both represent transgressive systems tract deposits dated as Late Bajocian; (2) bioturbated micrites with anomalodesmatan bivalves within the Goradongar Yellow Flagstone Member (Kachchh Basin) and bioturbated units in the Fort Member (Jaisalmer Basin) represent maximum flooding zone deposits of the Middle to Late Bathonian; (3) trough-crossbedded, sandy packto grainstones of the Raimalro Limestone Member (Kachchh Basin) and the basal limestone-sandstone unit of the Kuldhar section of the Jaisalmer Formation (Jaisalmer Basin) correspond to Late Bathonain transgressive systems tract deposits; and (4) ferruginous ooid-bearing carbonates with hardgrounds of the Dhosa Oolite member (Kachchh Basin) and the middle part of the Jajiya Member (Jaisalmer Basin) are Oxfordian transgressive systems tract deposits. The fact that in both basins similar biofacies prevailed during certain time intervals demonstrates a common control of their depositional history. As the two basins represent different tectonic settings, the most likely controlling factors were the relative sea-level changes produced by eustatic processes, a common subsidence history of the northwestern margin of the Indian craton, and the paleoclimate.

Direct Comparison of Catalyst-Free and Catalyst-Induced GaN Nanowires

GaN nanowires have been grown by molecular beam epitaxy either catalyst-free or catalyst-induced by means of Ni seeds.Under identical growth conditions of temperature andⅤ/Ⅲratio,both types of GaN nanowires are of wurtzite structure elongated in the Ga-polar direction and are constricted by M-plane facets.However,the catalyst-induced nanowires contain many more basal-plane stacking faults and their photoluminescence is weaker.These differences can be explained as effects of the catalyst Ni seeds.

Cavity-assisted ultrafast long-range periodic energy transfer between plasmonic nanoantennas

Radiationless energy transfer is at the core of diverse phenomena,such as light harvesting in photosynthesis1,energy-transfer-based microspectroscopies2,nanoscale quantum entanglement3 and photonic-mode hybridization4.Typically,the transfer is efficient only for separations that are much shorter than the diffraction limit.This hampers its application in optical communication and quantum information processing,which require spatially selective addressing.Here,we demonstrate highly efficient radiationless coherent energy transfer over a distance of twice the excitation wavelength by combining localized and delocalized5 plasmonic modes.Analogous to the Tavis–Cummings model,two whispering-gallery-mode antennas6 placed in the foci of an elliptical plasmonic cavity7 fabricated from single-crystal gold plates act as a pair of oscillators coupled to a common cavity mode.Time-resolved two-photon photoemission electron microscopy(TR 2P-PEEM)reveals an ultrafast long-range periodic energy transfer in accordance with the simulations.Our observations open perspectives for the optimization and tailoring of mesoscopic energy transfer and long-range quantum emitter coupling.

The efect of landscape structure on the evolution of two alternative dispersal strategies

Background:Dispersal is an important event for most organisms at least once in their life cycle.The evolution of dispersal can be infuenced by local adaptation,landscape structure,and perceived temporal and spatial variation.The interaction between local adaptation,landscape heterogeneity,temporal variability and rules of dispersal may be more complex than previously assumed.Therefore,we sought to understand the infuence of emigration rules and landscape structure on emerging dispersal rates and traits.Here,we implemented an individual-based model(IBM)of trait evolution in scenarios characterized by diferent landscape structures and diferent degrees of spatial heterogeneity and global temporal variation.Individuals could evolve two traits coding for their environmental niche(position of niche optimum and niche width),and two traits determining nearest-neighbor dispersal:an individual emigrates with a probability defned by the frst trait(random emigration),but emigrates with certainty if the fertility expected in the patch of residence falls below a threshold specifed by the second trait(habitat-dependent emigration).Results:We note an interaction efect between dispersal strategy and spatial variance—lower emigration under habitat-dependent than under random emigration if spatial heterogeneity is low,but eventually a reversal of this ranking if heterogeneity becomes large.Landscapes with sharp transition of habitat attributes result in a high degree of spatial sorting,while fractal landscapes do not.Emigration rates are overall lowest,when spatial variation is highest.Conclusions:We conclude that emergent emigration rates are infuenced more by landscape structure and spatiotemporal heterogeneity than by the emigration strategy.With the ongoing land use change more research into this topic could help highlight the difculties species might face under the change from landscapes characterized by gradual transition zones to landscapes dominated by abrupt ecotones,the latter typical for agricultural and urban settings.

Quantum-optical spectroscopy of a twolevel system using an electrically driven micropillar laser as a resonant excitation source

Two-level emitters are the main building blocks of photonic quantum technologies and are model systems for the exploration of quantum optics in the solid state.Most interesting is the strict resonant excitation of such emitters to control their occupation coherently and to generate close to ideal quantum light,which is of utmost importance for applications in photonic quantum technology.To date,the approaches and experiments in this field have been performed exclusively using bulky lasers,which hinders the application of resonantly driven two-level emitters in compact photonic quantum systems.Here we address this issue and present a concept for a compact resonantly driven single-photon source by performing quantum-optical spectroscopy of a two-level system using a compact high-βmicrolaser as the excitation source.The two-level system is based on a semiconductor quantum dot(QD),which is excited resonantly by a fiber-coupled electrically driven micropillar laser.We dress the excitonic state of the QD under continuous wave excitation,and trigger the emission of single photons with strong multi-photon suppression(ge2Te0T?0:02)and high photon indistinguishability(V=57±9%)via pulsed resonant excitation at 156 MHz.These results clearly demonstrate the high potential of our resonant excitation scheme,which can pave the way for compact electrically driven quantum light sources with excellent quantum properties to enable the implementation of advanced quantum communication protocols.

Investigation of environmental and land use impacts in forested permafrost headwaters of the Selenga-Baikal river system,Mongolia-Effects on discharge,water quality and macroinvertebrate diversity

Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact of land cover(especially forest cover),environment and human usage on runoff,chemical water quality and macroinvertebrate fauna in a river basin under discontinuous permafrost conditions in an arid,sparsely populated region of Mongolia.To verify our hypotheses that different landuses and environmental impacts in permafrost headwaters influence water quality,we investigated 105 sampling sites,37 of them at intermittent stream sections without water flow.Discharge was positively impacted by land cover types steppe,grassland and forest and negatively by shrubland,forest burnt by wild fires(indicating a reduction of permafrost)and slope.Water quality was affected by altitude,longitude and latitude,shrub growth and water temperature.Shannon diversity of macroinvertebrates was driven by water temperature,iron content of the water,flow velocity,and subbasin size(adjusted R^(2)=0.54).Sample plots clustered in three groups that differed in water chemistry,macroinvertebrate diversity,species composition and bio-indicators.Our study confirms that steppes and grasslands have a higher contribution to runoff than forests,forest cover has a positive impact on water quality,and diversity of macroinvertebrates is higher in sites with less nutrients and pollutants.The excellent ecological status of the upper reaches of the Kharaa is severely threatened by forest fires and human-induced climate change and urgently needs to be conserved.

Emission from quantum-dot high-β microcavities: transition from spontaneous emission to lasing and the effects of superradiant emitter coupling

Measured and calculated results are presented for the emission properties of a new class of emitters operating in the cavity quantum electrodynamics regime.The structures are based on high-finesse GaAs/AlAs micropillar cavities,each with an active medium consisting of a layer of InGaAs quantum dots(QDs)and the distinguishing feature of having a substantial fraction of spontaneous emission channeled into one cavity mode(highβ-factor).This paper demonstrates that the usual criterion for lasing with a conventional(lowβ-factor)cavity,that is,a sharp non-linearity in the input–output curve accompanied by noticeable linewidth narrowing,has to be reinforced by the equal-time second-order photon autocorrelation function to confirm lasing.The paper also shows that the equal-time second-order photon autocorrelation function is useful for recognizing superradiance,a manifestation of the correlations possible in high-βmicrocavities operating with QDs.In terms of consolidating the collected data and identifying the physics underlying laser action,both theory and experiment suggest a sole dependence on intracavity photon number.Evidence for this assertion comes from all our measured and calculated data on emission coherence and fluctuation,for devices ranging from light-emitting diodes(LEDs)and cavity-enhanced LEDs to lasers,lying on the same two curves:one for linewidth narrowing versus intracavity photon number and the other for g(2)(0)versus intracavity photon number.

Multigrid Solution of a Lavrentiev-Regularized State-Constrained Parabolic Control Problem

A mesh-independent,robust,and accurate multigrid scheme to solve a linear state-constrained parabolic optimal control problem is presented.We first consider a Lavrentiev regularization of the state-constrained optimization problem.Then,a multigrid scheme is designed for the numerical solution of the regularized optimality system.Central to this scheme is the construction of an iterative pointwise smoother which can be formulated as a local semismooth Newton iteration.Results of numerical experiments and theoretical twogrid local Fourier analysis estimates demonstrate that the proposed scheme is able to solve parabolic state-constrained optimality systems with textbook multigrid efficiency.

永历帝肇庆朝廷里的瞿安德和卜弥格

本文原题为'Andreas Koffler and Michael Boym at the Court of the Yongli Emperor in Zhaoqing',是柯兰霓(Claudia von Collani)于2016年在肇庆学院举办的'第四届利玛窦与中西文化交流国际学术研讨会'提交的会议报告。该文梳理了服务于永历帝肇庆朝廷的两位传教士瞿安德(Wolfgang Andreas XavierKoffler,1603—1652)和卜弥格(MichaelBoym,1612—1659)的人生际遇,讲述了南明王朝帝王家庭可能皈依基督教的情形。柯兰霓,德国维尔茨堡大学(Universit?t Würzburg)宗教学系教授。她在早期中德文化交流,特别是在儒家、道家思想西传方面颇有研究,在比较宗教学和传教史研究方面学术成果丰硕。她在1985年完成的博士论文《耶稣会士白晋的生平与著作》('P. Joachim Bouvet S. J.:Sein Leben und sein Werk')已译成中文,于2009年由大象出版社出版。她已发表学术专著5部、译著3部,学术论文百余篇,书评90余篇。

是否存在“风险社会的刑法”?

乌尔里希·贝克的“风险社会”概念虽经劳尔、斯宾万格等人的发展也未能达到明确,且尚未完全被接受为法学研究的基础.人们基于预防新型风险的需要,提出了“风险社会的刑法”理论.较之于公法领域,“风险社会”概念在私法领域已经作为一个重要的注解概念得以确立.而许多刑法学者则理性地认识到“风险社会的刑法”本身所存在的风险并反对通过刑法来掌控与解决风险,认为该理论意味着传统的教义学框架在法治国家的最大程度的灵活化.通过对产品责任领域的“皮革喷雾剂案”的分析,笔者认为该判决并非“风险刑法”之征兆,刑法也并非不可避免地要对“风险社会”做出回应.