Publications

Palladium‐Catalyzed α‐Arylation of Aldehydes with Bromo‐ and Chloroarenes Catalyzed by [{Pd(allyl)Cl}₂] and dppf or Q‐phos

Substrate jeder Art: Ein allgemeines Verfahren für die palladiumkatalysierte α-Arylierung von Aldehyden (siehe Schema) verknüpft lineare und verzweigte Aldehyde mit elektronenarmen und elektronenreichen Brom- und Chlorarenen. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2008/z705357_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Dominant Resource Fairness: Fair Allocation of Heterogeneous Resources in Datacenters

This paper investigates how different resources can be fairly allocated among users that possibly prioritize them differently. We introduce a fairness policy, called Dominant Resource Fairness (DRF), which is an adaptation of max-min fairness from networking to datacenter environments. We show that DRF, unlike other policies which we investigated, satisfies a number of desirable properties that a fair datacenter scheduler should have, including guaranteeing that every user gets 1/N of some resource and that users can relinquish resources without hurting other users' allocations. DRF is also envy-free, incentivizing users to correctly report their resource demand. When compared to other intuitive schedulers, as well as competing ones from microeconomic theory, DRF is more fair.

ChemInform Abstract: Iridium‐Catalyzed Enantioselective Allylic Substitution of Enol Silanes from Vinylogous Esters and Amides.

Abstract Enol silanes of vinylogous esters and amides react as nucleophiles with a wide range of allylic carbonates affording the allylated products with high enantioselectivities and excellent branched‐to‐linear ratios.

U-Pb Baddeleyite Geochronology of the Bushveld Igneous Complex

Hydrogen-Substituted Osmium Silylene Complexes:  Effect of Charge Localization on Catalytic Hydrosilation

Addition of bulky primary silanes to the osmium benzyl compound, Cp*(iPr3P)OsCH2Ph, afforded two neutral hydrogen-substituted silylene complexes via activation of two Si-H bonds. These species have been structurally characterized, and their reactivity has been examined experimentally and computationally. Comparison of these neutral silylene complexes with their cationic analogue highlights the dramatic influence of charge distribution on the reaction chemistry of metal silylene complexes.

ChemInform Abstract: Oxydehydrogenation of Ethane over ZSM‐5 Zeolite Catalysts. Effect of Steam.

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A theory of physician-hospital integration: contending institutional and market logics in the health care field.

This article proposes a theory of physician-hospital integration. The theory is developed by building on three streams of scholarship: "new" institutionalism, "old" institutionalism, and the theory of economic markets. The theory uses several key concepts from these theoretical frameworks, including the notions of environmental demands for legitimacy, market demands for efficiency, and agency. To enhance the predictive power of the theory, two new concepts are introduced: directionality of influence between institutional and market forces at the macro-societal level, and degree of separation of institutional and market domains at the local level--which add important predictive power to the theory. Using these concepts, a number of hypotheses are proposed regarding the ideal types of physician-hospital arrangements that are likely to emerge under different combinations of directionality of influence and institutional and market domain separation. Moreover, the theory generates hypotheses regarding organizational dynamics associated with physician-hospital integration, including the conditions associated with high and low prevalence of physician-hospital integration, the extent to which the integrated organization is physician-centric or hospital-centric, and whether physician-hospital integration is likely to be based on loose contractual arrangements or tight, ownership-based arrangements.

Late Cretaceous (85--80 Ma), syn-arc cleavage development in metamorphic rocks of the Ritter Range, central Sierra Nevada California

Extensive, high quality exposures make the Ritter Range an appropriate place to investigate the deformation field in wallrocks of the Late Cretaceous Sierran magmatic arc. Faulting, tilting, cleavage development and shearing above affected pre-batholithic strata of upper Paleozoic to mid-Cretaceous age. The authors present Ar/Ar data for metamorphic amphibole, white mica and biotite from upper Paleozoic and Early to Middle Jurassic rocks of the section. These data re interpreted in light of temperatures of metamorphism and microstructural analysis of each sample. Syn- to post-kinematic amphibole from a foliated and lineated mafic amphibolite yields an age of 85 Ma for amphibole-derived gas. Peak metamorphic temperature was under 500 C. at this locality, so negligible Ar loss in the amphibole is expected. The authors interpret 85 Ma as the age of amphibole growth and cleavage development in this sample. Syn- to post-kinematic white mica and four biotites from five samples yield ages clustering at about 80 Ma. Since the micas probably grew above their Ar closure temperatures, the ages of the post-kinematic micas are minima for their fabrics. These data indicate that the dominant cleavage in the upper Paleozoic to Middle Jurassic rocks of the Ritter Range formed penecontemporaneously with emplacement ofmore » the adjacent Mono Pass and Tuolumne intrusive series, and suggests that the heat of these granitoids was instrumental in catalyzing widespread deformation in their wallrocks.« less

Early Results from GLASS-JWST. XIX: A High Density of Bright Galaxies at $z\approx10$ in the Abell 2744 Region

We report the detection of a high density of redshift $z\approx 10$ galaxies behind the foreground cluster Abell 2744, selected from imaging data obtained recently with NIRCam onboard {\it JWST} by three programs -- GLASS-JWST, UNCOVER, and DDT\#2756. To ensure robust estimates of the lensing magnification $μ$, we use an improved version of our model that exploits the first epoch of NIRCam images and newly obtained MUSE spectra, and avoids regions with $μ>5$ where the uncertainty may be higher. We detect seven bright $z\approx 10$ galaxies with demagnified rest-frame $-22 \lesssim M_{\rm UV}\lesssim -19$ mag, over an area of $\sim37$ sq. arcmin. Taking into account photometric incompleteness and the effects of lensing on luminosity and cosmological volume, we find that the density of $z\approx 10$ galaxies in the field is about $10\times$ ($3\times$) larger than the average at $M_{UV}\approx -21~ (-20)$ mag reported so far. The density is even higher when considering only the GLASS-JWST data, which are the deepest and the least affected by magnification and incompleteness. The GLASS-JWST field contains 5 out of 7 galaxies, distributed along an apparent filamentary structure of 2 Mpc in projected length, and includes a close pair of candidates with $M_{\rm UV}< -20$ mag having a projected separation of only 16 kpc. These findings suggest the presence of a $z\approx 10$ overdensity in the field. In addition to providing excellent targets for efficient spectroscopic follow-up observations, our study confirms the high density of bright galaxies observed in early {\it JWST} observations, but calls for multiple surveys along independent lines of sight to achieve an unbiased estimate of their average density and a first estimate of their clustering.

A risc approach to sensing and manipulation

Abstract This article describes sensing and manipulation strategies that use simple, modular robot hardware. To bridge the gap between automation and robotic technologies, we suggest that traditional automation hardware, such as parallel‐jaw grippers and optical beam sensors, can be combined with geometric planning and sensing algorithms. The resulting systems should be cost‐effective, reliable, and easy to set up and reconfigure. They should also be flexible enough to support small batch sizes and rapid changes in part design needed in forthcoming flexible/agile manufacturing systems. The RISC acronym, borrowed from computer architecture, suggests the parallels between the two technologies. RISC robots perform complex operations by composing simple elements. The elements may be individual light beam sensors, grouped together to form an array for recognition. Or a complex manipulation task may be performed via a sequence of grasp steps by different grippers specialized for acquisition and placement. This article emphasizes three areas: (i) RISC sensing, primarily optical beam sensing, (ii) RISC manipulation using simple parallel‐jaw grippers or minimal configurations of fingers, and (iii) Computer‐aided design of RISC workcells. © 1995 John Wiley & Sons, Inc.

Junction field-effect-transistor-based germanium photodetector on silicon-on-insulator

We propose and demonstrate a novel Ge photodetector on silicon-on-insulator based on a junction field effect transistor structure, where the field-effect transistor gate is replaced by a Ge island with no contact on it. Light incident on the Ge switches on the device by altering the conductance of the Si channel through secondary photoconductivity. The device's sensitivity is also enhanced by a vast reduction in parasitic capacitance. In cw measurements, proof-of-concept detectors exhibit up to a 33% change in Si channel conductance by absorbing only 200 nW of power at 1.55 microm. In addition, pulsed response tests have shown that rise times as low as 40 ps can be achieved.

Phase-transition–induced p-n junction in single halide perovskite nanowire

Significance Functional semiconductor heterojunctions are fundamental units for building up advanced optoelectronics and circuits. Halide perovskites, representing a new class of semiconductors with soft and reconfigurable ionic bonding, hold promise for a variety of applications because of their many unusual, tunable physical properties. This paper reports the formation of the current-rectifying p-n heterojunction in single-crystalline CsSnI 3 nanowires via localized phase transition between the n-type yellow and p-type black phases. We attribute the distinction of majority carrier types in these two phases to the different formation energies of the cation and anion vacancies. The present approach to heterojunction formation could inspire deeper understanding of phase-transition dynamics and enable precise control over the design of functional heterostructures using halide perovskite building blocks.

Communication-efficient distributed SGD with Sketching

Large-scale distributed training of neural networks is often limited by network bandwidth, wherein the communication time overwhelms the local computation time. Motivated by the success of sketching methods in sub-linear/streaming algorithms, we introduce Sketched SGD, an algorithm for carrying out distributed SGD by communicating sketches instead of full gradients. We show that Sketched SGD has favorable convergence rates on several classes of functions. When considering all communication -- both of gradients and of updated model weights -- Sketched SGD reduces the amount of communication required compared to other gradient compression methods from $\mathcal{O}(d)$ or $\mathcal{O}(W)$ to $\mathcal{O}(\log d)$, where $d$ is the number of model parameters and $W$ is the number of workers participating in training. We run experiments on a transformer model, an LSTM, and a residual network, demonstrating up to a 40x reduction in total communication cost with no loss in final model performance. We also show experimentally that Sketched SGD scales to at least 256 workers without increasing communication cost or degrading model performance.

A<i>SPITZER</i>SURVEY FOR DUST IN TYPE IIn SUPERNOVAE

Recent observations suggest that Type IIn supernovae (SNe IIn) may exhibit\nlate-time (&gt;100 days) infrared (IR) emission from warm dust more than other\ntypes of core-collapse SNe. Mid-IR observations, which span the peak of the\nthermal spectral energy distribution, provide useful constraints on the\nproperties of the dust and, ultimately, the circumstellar environment,\nexplosion mechanism, and progenitor system. Due to the low SN IIn rate (&lt;10% of\nall core-collapse SNe), few IR observations exist for this subclass. The\nhandful of isolated studies, however, show late-time IR emission from warm dust\nthat, in some cases, extends for five or six years post-discovery. While\nprevious Spitzer/IRAC surveys have searched for dust in SNe, none have targeted\nthe Type IIn subclass. This article presents results from a warm Spitzer/IRAC\nsurvey of the positions of all 68 known SNe IIn within a distance of 250 Mpc\nbetween 1999 and 2008 that have remained unobserved by Spitzer more than 100\ndays post-discovery. The detection of late-time emission from ten targets\n(~15%) nearly doubles the database of existing mid-IR observations of SNe IIn.\nAlthough optical spectra show evidence for new dust formation in some cases,\nthe data show that in most cases the likely origin of the mid-IR emission is\npre-existing dust, which is continuously heated by optical emission generated\nby ongoing circumstellar interaction between the forward shock and\ncircumstellar medium. Furthermore, an emerging trend suggests that these SNe\ndecline at ~1000--2000 days post-discovery once the forward shock overruns the\ndust shell. The mass-loss rates associated with these dust shells are\nconsistent with luminous blue variable (LBV) progenitors.\n

A Dual Sugar Challenge Test for Lipogenic Sensitivity to Dietary Fructose

Context: Increased hepatic de novo lipogenesis (DNL) in response to dietary sugar is implicated in dyslipidemia, fatty liver, and insulin resistance. Objective: The aim of the study was to develop a simple outpatient tolerance test for lipogenic sensitivity to dietary sugar. Design and Setting: In inpatients given repeated doses of fructose, protocol 1 compared the acute increase in DNL determined from the percentage of palmitate (“new palmitate”) and the percentage of isotopically labeled palmitate (“%DNL”) in very low-density lipoprotein triglyceride (TG). Protocol 2 compared the increase in new palmitate in outpatients given three different sugar beverages in a randomized crossover design. Participants: There were 15 lean and overweight volunteers in protocol 1 and 15 overweight volunteers in protocol 2. Interventions: In protocol 1, subjects received 1.4 g/kg fructose in divided oral doses over 6 h; in protocol 2, subjects received 0.5 g/kg fructose, 0.5 g/kg fructose plus 0.5g/kg glucose, or 1 g/kg fructose plus 1g/kg glucose each as a single oral bolus. Main Outcome Measures: We measured the increase in DNL by two methods. Results: After repeated doses of fructose, new palmitate was significantly correlated with the increase in %DNL (Δ, r = 0.814; P &amp;lt; 0.001) and with fasting insulin levels (area under the curve, r = 0.754; P = 0.001). After a single sugar dose, new palmitate showed a dose effect and was greater after fructose plus glucose. Very low-density lipoprotein TG and total TG significantly increased in both protocols. Conclusions: A single oral bolus of fructose and glucose rapidly increases serum TG and TG palmitate in overweight subjects. A dual sugar challenge test could prove useful to identify individuals at risk for carbohydrate-induced dyslipidemia and other adverse effects of increased DNL.

The Birth of the Euro (review)

H$\alpha$ Reverberation Mapping of the Intermediate-Mass Active Galactic Nucleus in NGC 4395

We present the results of a high-cadence spectroscopic and imaging monitoring campaign of the active galactic nucleus (AGN) of NGC 4395. High signal-to-noise-ratio spectra were obtained at the Gemini-N 8 m telescope using the GMOS integral field spectrograph (IFS) on 2019 March 7, and at the Keck-I 10 m telescope using the Low-Resolution Imaging Spectrometer (LRIS) with slitmasks on 2019 March 3 and April 2. Photometric data were obtained with a number of 1 m-class telescopes during the same nights. The narrow-line region (NLR) is spatially resolved; therefore, its variable contributions to the slit spectra make the standard procedure of relative flux calibration impractical. We demonstrate that spatially-resolved data from the IFS can be effectively used to correct the slit-mask spectral light curves. While we obtained no reliable lag owing to the lack of strong variability pattern in the light curves, we constrain the broad line time lag to be less than 3 hr, consistent with the photometric lag of $\sim80$ min reported by Woo et al. (2019). By exploiting the high-quality spectra, we measure the second moment of the broad component of the H$\alpha$ emission line to be $586\pm19$ km s$^{-1}$, superseding the lower value reported by Woo et al. (2019). Combining the revised line dispersion and the photometric time lag, we update the black hole mass as $(1.7\pm 0.3)\times10^4$ M$_{\odot}$.

Federalism, Fiscal Restraints, and European Monetary Union

A prominent feature of the Maastricht Treaty on European Union is the restrictions it places on fiscal policy. Under the provisions of the Excessive Deficit Procedure, or EDP, the success of member states in avoiding during the transition to economic and monetary union (EMU) is one of four criteria governing admission to the monetary union. Once monetary union has begun, member states are unconditionally required to avoid deficits. A state has an when it is so declared by the European Council upon a report by the European Commission and a judgment by the Monetary Committee. The EDP is set in motion if a country's deficit and general government debt respectively exceed 3 percent and 60 percent of GDP.' The justification for these procedures is that member states participating in the monetary union must be restrained from overborrowing to avoid destabilizing the common currency. If excessive deficits cause a debt crisis, the European Central Bank (ECB) will come under pressure to bail out the imperiled government. The bailout could be ex post (in which case the ECB would monetize the government's debt) or ex ante (in which case it would keep interest rates low to lighten the debt-service burden). Either way, unfettered fiscal policies could create inflationary pressures that the ECB will find difficult to resist.