cssi/SciSciGPT-SciSciNet huggingface dataset:
Mild conversion of propargylic alcohols to α,β-unsaturated enones in ionic liquids (ILs); a new ‘metal free’ life for the Rupe rearrangement

Abstract A mild and selective transition metal free protocol for the conversion of propargylic alcohols to cyclic and acyclic α,β-unsaturated enones via the Rupe rearrangement is reported. The method utilizes the Bronsted acidic ionic liquid [BMIM-SO3H][OTf] as catalyst and [BMIM][PF6] as solvent and offers the potential for recycling and reuse of the IL solvent. The feasibility to synthesize bicyclic fused cyclopentenone derivatives via a Rupe → Aldol → Nazarov sequence utilizing this protocol has also been demonstrated.
Synthesis of 3,4,5-Trisubstituted Isoxazoles via Sequential [3 + 2] Cycloaddition/Silicon-Based Cross-Coupling Reactions

A [3 + 2] cycloaddition reaction between alkynyldimethylsilyl ethers and aryl and alkyl nitrile oxides to produce isoxazolylsilanols has been developed. The cross-coupling reactions of these heterocyclic silanols with a variety of aryl iodides affords 3,4,5-trisubstituted isoxazoles. This sequential process allows for rapid variation of substituents at the 3, 4, and 5 positions of the isoxazole.
Synthesis of 1,5-disubstituted tetrazoles via Suzuki–Miyaura cross-coupling of 5-chloro-1-phenyltetrazole

Abstract Suzuki–Miyaura coupling reactions of 5-chloro-1-phenyl-tetrazole with various functionalized arylboronic acids were investigated. In the presence of catalytic amounts of SPhos/Pd(OAc) 2 or RuPhos/Pd(OAc) 2 , the reaction proceeded smoothly to afford 1,5-diaryltetrazoles in good to excellent yields.
Heptacoordination. Synthesis and Characterization of the IOF52- Dianion, an XOF5E species

The new IOF52- dianion was prepared in the form of its cesium salt by heating stoichiometric amounts of CsF, I2O5, and IF5 to 162 °C for 14 days. The white stable solid was characterized by vibrati...
The Black hole information paradox and macroscopic superpositions

We investigate the experimental capabilities required to test whether black holes destroy information. We show that an experiment capable of illuminating the information puzzle must necessarily be able to detect or manipulate macroscopic superpositions (i.e., Everett branches). Hence, it could also address the fundamental question of decoherence versus wavefunction collapse.
Synthesis of novel, nonclassical 2-amino-4-oxo-6-(arylthio)ethylpyrrolo[2,3-d] pyrimidines as potential inhibitors of thymidylate synthase†

A novel series of 14 nonclassical 6-substituted pyrrolo[2,3-d]pyrimidines 2a - 2n were designed as potential inhibitors of thymidylate synthase, based on previously reported 2-amino-4-oxopyrrolo[2,3-d]-pyrimidines 1a and 1b. The synthesis of the target compounds 2a-2n was accomplished by nucleophilic displacement of the mesylate 11 with appropriately substituted aromatic thiols. Most of the target compounds did not show inhibition of either Escherichia coli thymidylate synthase or recombinant human thymidylate synthase at the concentrations tested. However, compounds 2h (2,4-dichloro), 2j (3,4-dichloro) and 2m (4-nitro) did show 25%, 40% and 35% inhibition of human thymidylate synthase at 23 μM, 23 μM and 24 μM, respectively. These observations are in accordance with previous reports, which suggest that strong electron withdrawing substituents on the side chain aromatic ring are conducive to inhibition of thymidylate synthase.
SET-Induced Photorearrangement of 2-Phenylallyl Phosphites. Stereochemistry at Phosphorus. Application to Cyclic Nucleotide Derivatives

The stereochemistry at phosphorus of the SET-induced photorearrangement of diastereomeric 4-tert-butyl-2-phenylallyl-1,3,2-dioxaphosphorinanes (8) to the corresponding 2-phenylallylphosphonates (9), which involves excited singlet 1,4-dicyanonaphthalene (1DCN*) as one-electron oxidant, was investigated. The rearrangement occurs with close to complete retention of configuration at phosphorus. The previously postulated mechanism for this photorearrangement is shown to be consistent with the stereochemical finding. Thus, one-electron reduction by DCN.- of the presumably stereospecifically formed distonic cyclic 1,3-cation radical intermediate 15, generated from cis-8 (Scheme 2), yields the thermodynamically stable diradical 16. β scission of 16 forms phosphonate cis-9. An alternative mechanism involving β scission of 15 to a styryl cation radical, prior to one-electron reduction to 15, is discounted on the basis of unpublished trapping studies using MeOH. The direct, kinetically controlled formation of diradi...
A convenient cross-coupling route to α,β,γ,δ-unsaturated amino acids

Abstract β-Bromoenamide esters are coupled stereospecifically to vinylboronic acids via a palladium-catalyzed Suzuki reaction. This cross-coupling proceeds under mild conditions with Pd(OAc) 2 in 95% EtOH at 50 °C and produces amino acids with 1,3-diene side chains in high yields.
Conversion of Pyranose Glycals to Furanose Derivatives: A New Route to Oligofuranosides

Acetylated pyranose glycals have been converted through a convenient three-step process into protected furanose reducing sugars. Ozonolysis of 2,3,5-tri-O-acetyl-glucal or 2,3,5-tri-O-acetyl-galactal, followed by treatment with dimethyl sulfide and then hydrolysis gave respectively protected arabinofuranose (6) and lyxofuranose (7) derivatives. Conversion of these hemiacetals to oligosaccharides was explored using a number of methods. Activation of 6 or 7 in situ afforded glycosides in modest yield and stereoselectivity. Glycosylation of tetraacetates 16 and 18, obtained from 6 and 7, gave similar results. However, thioglycosides 17 and 19, also derived from 6 and 7, were found to be effective glycosyl donors, producing products in good to excellent yields and with high stereoselectivities. The method was also used to synthesize a disaccharide in which one residue contained uniform 13C enrichment.
Synthesis of 6-acyl-5,8-quinolinediols by photo-Friedel–Crafts acylation using sunlight

Abstract Synthesis of acyl-5,8-quinolinediols using sunlight was investigated. Photo-Friedel–Crafts acylation of quinoline-5,8-dione and aldehyde afforded the corresponding 6-acyl-5,8-quinolinediols regioselectively in moderate to good yields. The compounds have a variety of potential applications.
Mechanical and Microstructural Properties of Pediatric Anterior Cruciate Ligaments and Autograft Tendons used for Reconstruction

Background:Over the past several decades, there has been a steady increase in pediatric anterior cruciate ligament (ACL) tears, particularly in young female basketball and soccer players. Because a...
Electron transfer photochemistry of quadricyclanone: Stereospecific nucleophilic capture of a radical cation and singular rearrangement

Abstract The electron transfer photo-sensitized reaction of quadricyclanone (1) with methanol produces a single product, 7- syn -methoxybicyclo[2.2.1]hept-5-en-2-one (2) via nucleophilic attack of methanol on the radical cation of 1. The structure of the product and the stereochemistry of the methoxy group reveal that the radical cation is captured by backside attack of methanol on one cyclopropane function followed by a specific cyclopropylcarbinyl to butenyl rearrangement.
Quantifying male and female pheromone-based mate choice in Caenorhabditis nematodes using a novel microfluidic technique.

Pheromone cues are an important component of intersexual communication, particularly in regards to mate choice. Caenorhabditis nematodes predominant rely on pheromone production for mate finding and mate choice. Here we describe a new microfluidic paradigm for studying mate choice in nematodes. Specifically, the Pheromone Arena allows for a constant flow of odorants, including pheromones and other small molecules, to be passed in real time from signaling worms to those making a choice without any physical contact. We validated this microfluidic paradigm by corroborating previous studies in showing that virgin C. remanei and C. elegans males have a strong preference for virgin females over mated ones. Moreover, our results suggest that the strength of attraction is an additive effect of male receptivity and female signal production. We also explicitly examine female choice and find that females are more attracted to virgin males. However, a female’s mate choice is strongly dependent on her mating status.
Stereoselective total synthesis of antitumor macrolide (+)-rhizoxin D.

A convergent, stereoselective total synthesis of the macrolide antitumor agent rhizoxin D is described. (+)-DIPCl-promoted asymmetric aldol reaction, Evans−Tishchenko 1,3-diol synthesis, modified Julia coupling, and Horner−Wadsworth−Emmons reactions are featured.
Synthesis of highly substituted ureas and thioureas through 1,3-diaza-Claisen rearrangements

Abstract Isocyanates and isothiocyanates that are not activated by an electron withdrawing group react with azanorbornenes in benzene at reflux to afford ureas and thioureas through the corresponding 1,3-diaza-Claisen rearrangements. At higher temperatures, a triazinone byproduct is observed. Isocyanates and isothiocyanates that are activated by an electron-withdrawing group react at room temperature to give the corresponding ureas and thioureas. The reactions of the activated isocyanates and isothiocyanates are also accompanied by the formation of isoureas and isothioureas. Interestingly, while benzoyl isocyanate reacts with N -benzyl azanorbornene at room temperature to give a 2:1 mixture of urea to isourea, in benzene at reflux the only product observed is the urea. A crossover experiment rules out the possibility that the products are formed through a retro-Diels–Alder, [4+2] cycloaddition sequence instead of a 1,3-diaza-Claisen rearrangement. Competition experiments between isocyanates and isothiocyanates with limiting azanorbornene indicate that isothiocyanates react faster to give the rearrangement product. Since isocyanates are shown to be more electrophilic, these data are consistent with a fast addition step and a rate-determining rearrangement step.
Lifetimes of heavy-flavour hadrons—whence and whither?

A theoretical treatment for the weak decays of heavy-flavour hadrons has been developed that is genuinely based on QCD. Its methodology as it applies to total lifetimes and the underlying theoretical issues are sketched. Predictions are compared with present data. One discrepancy emerges: the beauty baryon lifetime appears to be significantly shorter than expected. The ramifications of those findings are analyzed in detail.
Historical perspectives and current advancements in the bacteriology and medical therapy of struvite urinary stone disease

Struvite calculi have afflicted man for thousands of years. Despite recent advances in surgical technology to treat these disabling stones, high recurrence rates and inability to remove all stone fragments remain significant problems. Previous non-surgical alternatives have been disappointing because of low success rates, increased side effects or poor tolerability. New research in this area continues to provide insight into origins of lithogenesis and non-invasive therapy for calculi caused by infection.
Global accumulation of circRNAs during aging in Caenorhabditis elegans.

Circular RNAs (CircRNAs) are a newly appreciated class of RNAs that lack free 5′ and 3′ ends, are expressed by the thousands in diverse forms of life, and are mostly of enigmatic function. Ostensibly due to their resistance to exonucleases, circRNAs are known to be exceptionally stable. Previous work in Drosophila and mice have shown that circRNAs increase during aging in neural tissues. Here, we examined the global profile of circRNAs in C. elegans during aging by performing ribo-depleted total RNA-seq from the fourth larval stage (L4) through 10-day old adults. Using stringent bioinformatic criteria and experimental validation, we annotated a high-confidence set of 1166 circRNAs, including 575 newly discovered circRNAs. These circRNAs were derived from 797 genes with diverse functions, including genes involved in the determination of lifespan. A massive accumulation of circRNAs during aging was uncovered. Many hundreds of circRNAs were significantly increased among the aging time-points and increases of select circRNAs by over 40-fold during aging were quantified by RT-qPCR. The expression of 459 circRNAs was determined to be distinct from the expression of linear RNAs from the same host genes, demonstrating host gene independence of circRNA age-accumulation. We attribute the global scale of circRNA age-accumulation to the high composition of post-mitotic cells in adult C. elegans, coupled with the high resistance of circRNAs to decay. These findings suggest that the exceptional stability of circRNAs might explain age-accumulation trends observed from neural tissues of other organisms, which also have a high composition of post-mitotic cells. Given the suitability of C. elegans for aging research, it is now poised as an excellent model system to determine whether there are functional consequences of circRNA accumulation during aging.
Synthetic studies towards keramamide F

Abstract This communication describes the synthesis of three fragments of the cytotoxic natural product keramamide F.
Hydraulic resistance of periarterial spaces in the brain.

Periarterial spaces (PASs) are annular channels that surround arteries in the brain and contain cerebrospinal fluid (CSF): a flow of CSF in these channels is thought to be an important part of the brain’s system for clearing metabolic wastes. In vivo observations reveal that they are not concentric, circular annuli, however: the outer boundaries are often oblate, and the arteries that form the inner boundaries are often offset from the central axis. We model PAS cross-sections as circles surrounded by ellipses and vary the radii of the circles, major and minor axes of the ellipses, and two-dimensional eccentricities of the circles with respect to the ellipses. For each shape, we solve the governing Navier–Stokes equation to determine the velocity profile for steady laminar flow and then compute the corresponding hydraulic resistance. We find that the observed shapes of PASs have lower hydraulic resistance than concentric, circular annuli of the same size, and therefore allow faster, more efficient flow of cerebrospinal fluid. We find that the minimum hydraulic resistance (and therefore maximum flow rate) for a given PAS cross-sectional area occurs when the ellipse is elongated and intersects the circle, dividing the PAS into two lobes, as is common around pial arteries. We also find that if both the inner and outer boundaries are nearly circular, the minimum hydraulic resistance occurs when the eccentricity is large, as is common around penetrating arteries. The concentric circular annulus assumed in recent studies is not a good model of the shape of actual PASs observed in vivo, and it greatly overestimates the hydraulic resistance of the PAS. Our parameterization can be used to incorporate more realistic resistances into hydraulic network models of flow of cerebrospinal fluid in the brain. Our results demonstrate that actual shapes observed in vivo are nearly optimal, in the sense of offering the least hydraulic resistance. This optimization may well represent an evolutionary adaptation that maximizes clearance of metabolic waste from the brain.
Indistinguishability Obfuscation from Constant-Degree Graded Encoding Schemes.

We construct a general-purpose indistinguishability obfuscation (IO) scheme for all polynomialsize circuits from constant-degree graded encoding schemes in the plain model, assuming the existence of a subexponentially secure Pseudo-Random Generator (PRG) computable by constantdegree arithmetic circuits (or equivalently in NC), and the subexponential hardness of the Learning With Errors (LWE) problems. In contrast, previous general-purpose IO schemes all rely on polynomial-degree graded encodings. Our general-purpose IO scheme is built upon two key components: • a new bootstrapping theorem that subexponentially secure IO for a subclass of constantdegree arithmetic circuits implies IO for all polynomial size circuits (assuming PRG and LWE as described above), and • a new construction of IO scheme for any generic class of circuits in the ideal graded encoding model, in which the degree of the graded encodings is bounded by a variant of the degree, called type degree, of the obfuscated circuits. In comparison, previous bootstrapping theorems start with IO for NC, and previous constructions of IO schemes require the degree of graded encodings to grow polynomially in the size of the obfuscated circuits. ∗rachel.lin@cs.ucsb.edu. Huijia Lin was partially supported by NSF grants CNS-1528178 and CNS-1514526. This work was done in part while the author was visiting the Simons Institute for the Theory of Computing, supported by the Simons Foundation and by the DIMACS/Simons Collaboration in Cryptography through NSF grant CNS1523467.
Ruthenium‐Catalyzed Olefin Cross Metathesis of Styrenes as an Alternative to the Heck and Cross‐Coupling Reactions

The use of olefin cross metathesis as a method for the formation of styrenyl-olefins is described using allylic substituted olefins and electron-deficient olefins. These methods provide an orthogonal method to alternative olefination strategies, such as the Heck reaction. These methods have also been employed in the total synthesis of 3-flavanols.
Highly Efficient Deprotection of N-p-Toluenesulfinyl Group of β-Branched Baylis–Hillman Adducts by Using Amberlite IR-120 (Plus) Ion-Exchange Resin

Abstract An efficient deprotection of N - p -toluenesulfinyl group of β-branched Baylis–Hillman adducts has been developed by using Amberlite IR-120 (plus) ion-exchange resin in methanol solution at room temperature. Good to quantitative yields have been obtained for six examples. No racemization was detected under the mild conditions. This new method provides a simultaneous deprotection/purification, which has the great advantage over the solution phase deprotection technique of simplicity of work-up.
Simple and Effective Paraphrastic Similarity from Parallel Translations.

We present a model and methodology for learning paraphrastic sentence embeddings directly from bitext, removing the time-consuming intermediate step of creating para-phrase corpora. Further, we show that the resulting model can be applied to cross lingual tasks where it both outperforms and is orders of magnitude faster than more complex state-of-the-art baselines.
Chemical synthesis of hormone receptor probes: high affinity photoactivated enediyne-estrogens

Abstract A family of enediyne-estrogens has been prepared, and evaluated for affinity to hER. The optimal ligand has nM affinity, and undergoes photoBergman cycloaromatization.
Comparison of Orlicz-Lorentz spaces

The final version of this paper appears in "Studia Mathematica" 103.2 (1992): 161-189. Print.
A simple and efficient biphasic method for the preparation of 4-nitrophenyl N-methyl- and N-alkylcarbamates

Abstract Treatment of 4-nitrophenyl chloroformate with alkylammonium hydrochloride salts and solid anhydrous Na2CO3 in either CH2Cl2 or CH3CN gave 4-nitrophenyl N-methylcarbamate and other N-alkylcarbamate analogues in excellent yields. Of particular interest is the observation that 4-nitrophenyl N-methylcarbamate, a safer alternative to the highly toxic methyl isocyanate, is obtained in quantitative yield (⩾95% pure as determined by 1H NMR) after simple filtration and solvent evaporation.
Bipyridinium ionic liquid-promoted cross-coupling reactions between perfluoroalkyl or pentafluorophenyl halides and aryl iodides.

A new room-temperature ionic liquid has been synthesized from 2,2‘-bipyridine. This liquid improved the copper-catalyzed cross-coupling reactions between perfluoroalkyl or pentafluorophenyl halides and aryl iodides. Good recyclability using this solvent system was observed.
Low-Lying Electronic States of M3O9- and M3O92- (M = Mo, W)

Multiple low-lying electronic states of M3O9- and M3O92- (M = Mo, W) arise from the occupation of the near-degenerate low-lying virtual orbitals in the neutral clusters. We used density functional theory (DFT) and coupled cluster theory (CCSD(T)) with correlation consistent basis sets to study the structures and energetics of the electronic states of these anions. The adiabatic and vertical electron detachment energies (ADEs and VDEs) of the anionic clusters were calculated with 27 exchange-correlation functionals including one local spin density approximation functional, 13 generalized gradient approximation (GGA) functionals, and 13 hybrid GGA functionals, as well as the CCSD(T) method. For Mo3O9-, CCSD(T) and nearly all of the DFT exchange-correlation functionals studied predict the 2A1 state arising from the Jahn−Teller distortion due to singly occupying the degenerate e‘ orbital to be lower in energy than the 2A1‘ state arising from singly occupying the nondegenerate a1‘ orbital. For W3O9-, the 2A1 s...
Inorganic chemistry solutions to semiconductor nanocrystal problems

Abstract The optoelectronic and chemical properties of semiconductor nanocrystals heavily depend on their composition, size, shape and internal structure, surface functionality, etc. Available strategies to alter these properties through traditional colloidal syntheses and ligand exchange methods place a premium on specific reaction conditions and surfactant combinations. In this invited review, we apply a molecular-level understanding of chemical precursor reactivity to reliably control the morphology, composition and intimate architecture (core/shell vs. alloyed) of semiconductor nanocrystals. We also describe our work aimed at achieving highly selective, low-temperature photochemical methods for the synthesis of semiconductor–metal and semiconductor–metal oxide photocatalytic nanocomposites. In addition, we describe our work on surface modification of semiconductor nanocrystal quantum dots using new approaches and methods that bypass ligand exchange, retaining the nanocrystal's native ligands and original optical properties, as well as on spectroscopic methods of characterization useful in determining surface ligand organization and chemistry. Using recent examples from our group and collaborators, we demonstrate how these efforts have lead to faster, wider and more systematic application of semiconductor nanocrystal-based materials to biological imaging and tracking, and to photocatalysis of unconventional substrates. We believe techniques and methods borrowed from inorganic chemistry (including coordination, organometallic and solid state chemistry) have much to offer in reaching a better understanding of the synthesis, functionalization and real-life application of such exciting materials as semiconductor nanocrystals (quantum dots, rods, tetrapods, etc.).
Catalytic Reduction of Nitrogen Oxides by Methane over Pd(110)

The catalytic reduction of NO with CH4 has been studied over Pd(110) in the temperature range 700−800 K at a total pressure of 10 Torr. The rate of NO reduction is at a maximum at a high CH4/NO stoichiometry (8/1) and at a minimum at a low (1/4) CH4/NO ratio. Correspondingly, the activation energy for NO reduction decreases with increasing CH4/NO ratio, and the reaction orders are −1.0 in NO and +1.5 in CH4. Unlike NO, the rate of N2O reduction is at a maximum at low CH4 pressures, and the reaction orders are positive in N2O and negative in CH4. In the presence of oxygen, NO is oxidized to NO2, which is in turn reduced back to NO by CH4. The NO/NO2 oxidation/reduction cycle has the effect of delaying NO reduction to N2 (or N2O) until all of the O2 is consumed.
PES: proactive event scheduling for responsive and energy-efficient mobile web computing

Web applications are gradually shifting toward resource-constrained mobile devices. As a result, the Web runtime system must simultaneously address two challenges: responsiveness and energy-efficiency. Conventional Web runtime systems fall short due to their reactive nature: they react to a user event only after it is triggered. The reactive strategy leads to local optimizations that schedule event executions one at a time, missing global optimization opportunities. This paper proposes Proactive Event Scheduling (PES). The key idea of PES is to proactively anticipate future events and thereby globally coordinate scheduling decisions across events. Specifically, PES predicts events that are likely to happen in the near future using a combination of statistical inference and application code analysis. PES then speculatively executes future events ahead of time in a way that satisfies the QoS constraints of all the events while minimizing the global energy consumption. Fundamentally, PES unlocks more optimization opportunities by enlarging the scheduling window, which enables coordination across both outstanding events and predicted events. Hardware measurements show that PES reduces the QoS violation and energy consumption by 61.2% and 26.5%, respectively, over the Android's default Interactive CPU governor. It also reduces the QoS violation and energy consumption by 63.1% and 17.9%, respectively, compared to EBS, a state-of-the-art reactive scheduler.
Pitholides A-D, polyketides from a marine tunicate-derived culture of Pithomyces sp.

Abstract Four new fungi pigments, pitholides A-D (2–5) were isolated from the salt water culture of the fungus Pithomyces sp. separated from the Indo-Pacific tunicate Oxycorynia fascicularis. Their structures include the core of Austdiol (6), an Aspergillus metabolite.
Boron trifluoride catalyzed rearrangement and dehydration of epoxyalkynols

Abstract Epoxyalkynols undergo a rerrangement/dehydration when reacted with boron trifluoride to provide [3]cumulenals and α-hydroxy allenes.
Strategies for Large-Scale Synthesis of Coelenterazine for in Vivo Applications

A new application of two Negishi-type coupling reactions for the synthesis of coelenterazine is reported. The synthesis of coelenterazine in high purity on a gram scale will enable numerous approaches to bioluminescence imaging and possibly photodynamic therapy of deep-seated tumors. Coelenterazine is the substrate for several luciferases, among them Gaussia luciferase (gLuc). This synthesis starts with pyrazin-2-amine and uses inexpensive starting materials and catalysts.
Selective Cleavage of Cbz-Protected Amines

Under conditions of catalytic Ni(0) and in most cases just over 1 equiv of Me2NH·BH3/K2CO3 or Cs2CO3, a Cbz-protected nitrogen, which is part of a heteroaromatic ring, can be chemospecifically clea...
Expedient synthesis of novel β-ketoesters from the Mizoroki–Heck coupling of ethyl 3-ethoxyacrylate with aryl and pyridyl halides

Abstract It is well known that β-ketoesters are useful intermediates for the synthesis of a range of heterocyclic templates. While there are many useful synthetic methods available to access these intermediates, there are still opportunities for the discovery of useful methodologies for their construction from novel starting materials. In this regard, we report on the discovery of a facile Pd-catalyzed Mizoroki–Heck coupling of ethyl 3-ethoxyacrylate with aryl and heteroaryl halides to form substituted alkoxyacrylates which can be hydrolyzed to form novel aryl and heteroaryl β-ketoesters.
Self-Supervised GANs via Auxiliary Rotation Loss

Conditional GANs are at the forefront of natural image synthesis. The main drawback of such models is the necessity for labeled data. In this work we exploit two popular unsupervised learning techniques, adversarial training and self-supervision, and take a step towards bridging the gap between conditional and unconditional GANs. In particular, we allow the networks to collaborate on the task of representation learning, while being adversarial with respect to the classic GAN game. The role of self-supervision is to encourage the discriminator to learn meaningful feature representations which are not forgotten during training. We test empirically both the quality of the learned image representations, and the quality of the synthesized images. Under the same conditions, the self-supervised GAN attains a similar performance to state-of-the-art conditional counterparts. Finally, we show that this approach to fully unsupervised learning can be scaled to attain an FID of 23.4 on unconditional ImageNet generation.
Impacts of Labor Market Institutions and Demographic Factors on Labor Markets in Latin America

This paper documents recent labor market performance in the Latin American region. The paper shows that unemployment, informality, and inequality have been falling over the past two decades, though still remain high. By contrast, productivity has remained stubbornly low. The paper, then, turns to the potential impacts of various labor market institutions, including employment protection legislation (EPL), minimum wages (MW), payroll taxes, unemployment insurance (UI) and collective bargaining, as well as the impacts of demographic changes on labor market performance. The paper relies on evidence from carefully conducted studies based on micro-data for countries in the region and for other countries with similar income levels to draw conclusions on the impact of labor market institutions and demographic factors on unemployment, informality, inequality and productivity. The decreases in unemployment and informality can be partly explained by the reduced strictness of EPL and payroll taxes, but also by the increased shares of more educated and older workers. By contrast, the fall in inequality starting in 2002 can be explained by a combination of binding MW throughout most of the region and, to a lesser extent, by the introduction of UI systems in some countries and the role of unions in countries with moderate unionization rates. Falling inequality can also be explained by the fall in the returns to skill associated with increased share of more educated and older workers.
eMap: A Web Application for Identifying and Visualizing Electron or Hole Hopping Pathways in Proteins.

eMap is a web-based platform for identifying and visualizing electron or hole transfer pathways in proteins based on their crystal structures. The underlying model can be viewed as a coarse-grained...
How does genome size affect the evolution of pollen tube growth rate, a haploid performance trait?

PREMISE Male gametophytes of most seed plants deliver sperm to eggs via a pollen tube. Pollen tube growth rates (PTGRs) of angiosperms are exceptionally rapid, a pattern attributed to more effective haploid selection under stronger pollen competition. Paradoxically, whole genome duplication (WGD) has been common in angiosperms but rare in gymnosperms. Pollen tube polyploidy should initially accelerate PTGR because increased heterozygosity and gene dosage should increase metabolic rates. However, polyploidy should also independently increase tube cell size, causing more work which should decelerate growth. We asked how genome size changes have affected the evolution of seed plant PTGRs. METHODS We assembled a phylogenetic tree of 451 species with known PTGRs. We then used comparative phylogenetic methods to detect effects of neo-polyploidy (within-genus origins), DNA content, and WGD history on PTGR, and correlated evolution of PTGR and DNA content. RESULTS Gymnosperms had significantly higher DNA content and slower PTGR optima than angiosperms, and their PTGR and DNA content were negatively correlated. For angiosperms, 89% of model weight favored Ornstein-Uhlenbeck models with a faster PTGR optimum for neo-polyploids, whereas PTGR and DNA content were not correlated. For within-genus and intraspecific-cytotype pairs, PTGRs of neo-polyploids < paleo-polyploids. CONCLUSIONS Genome size increases should negatively affect PTGR when genetic consequences of WGDs are minimized, as found in intra-specific autopolyploids (low heterosis) and gymnosperms (few WGDs). But in angiosperms, the higher PTGR optimum of neo-polyploids and non-negative PTGR-DNA content correlation suggest that recurrent WGDs have caused substantial PTGR evolution in a non-haploid state.
Partial Searchlight Scheduling is Strongly PSPACE-Complete

The problem of searching a polygonal region for an unpredictably moving intruder by a set of stationary guards, each carrying an orientable laser, is known as the Searchlight Scheduling Problem. Determining the computational complexity of deciding if the polygon can be searched by a given set of guards is a long-standing open problem. Here we propose a generalization called the Partial Searchlight Scheduling Problem, in which only a given subregion of the environment has to be searched, as opposed to the entire area. We prove that the corresponding decision problem is strongly PSPACEcomplete, both in general and restricted to orthogonal polygons where the region to be searched is a rectangle. Our technique is to reduce from the \edge-to-edge" problem for nondeterministic constraint logic machines, after showing that the computational power of such machines does not change if we allow \asynchronous" edge reversals (as opposed to \sequential").
Coding Schemes for Achieving Strong Secrecy at Negligible Cost

We study the problem of achieving strong secrecy over wiretap channels at negligible cost , in the sense of maintaining the overall communication rate of the same channel without secrecy constraints. Specifically, we propose and analyze two source-channel coding architectures, in which secrecy is achieved by multiplexing public and confidential messages. In both cases, our main contribution is to show that secrecy can be achieved without compromising communication rate and by requiring only randomness of asymptotically vanishing rate. Our first source-channel coding architecture relies on a modified wiretap channel code, in which randomization is performed using the output of a source code. In contrast, our second architecture relies on a standard wiretap code combined with a modified source code termed uniform compression code , in which a small shared secret seed is used to enhance the uniformity of the source code output. We carry out a detailed analysis of uniform compression codes and characterize the optimal size of the shared seed.
Factors of IID on Trees

Classical ergodic theory for integer-group actions uses entropy as a complete invariant for isomorphism of IID (independent, identically dis- tributed) processes (a.k.a. product measures). This theory holds for amenable groups as well. Despite recent spectacular progress of Bowen, the situation for non-amenable groups, including free groups, is still largely mysterious. We present some illustrative results and open questions on free groups, which are particularly interesting in combinatorics, statistical physics, and probability. Our results include bounds on minimum and maximum bisection for random cubic graphs that improve on all past bounds.
Neuronal Synchrony in Complex-Valued Deep Networks

Abstract: Deep learning has recently led to great successes in tasks such as image recognition (e.g Krizhevsky et al., 2012). However, deep networks are still outmatched by the power and versatility of the brain, perhaps in part due to the richer neuronal computations available to cortical circuits. The challenge is to identify which neuronal mechanisms are relevant, and to find suitable abstractions to model them. Here, we show how aspects of spike timing, long hypothesized to play a crucial role in cortical information processing, could be incorporated into deep networks to build richer, versatile representations. We introduce a neural network formulation based on complex-valued neuronal units that is not only biologically meaningful but also amenable to a variety of deep learning frameworks. Here, units are attributed both a firing rate and a phase, the latter indicating properties of spike timing. We show how this formulation qualitatively captures several aspects thought to be related to neuronal synchrony, including gating of information processing and dynamic binding of distributed object representations. Focusing on the latter, we demonstrate the potential of the approach in several simple experiments. Thus, neuronal synchrony could be a flexible mechanism that fulfills multiple functional roles in deep networks.
Near-optimal sensor scheduling for batch state estimation: Complexity, algorithms, and limits

In this paper, we focus on batch state estimation for linear systems. This problem is important in applications such as environmental field estimation, robotic navigation, and target tracking. Its difficulty lies on that limited operational resources among the sensors, e.g., shared communication bandwidth or battery power, constrain the number of sensors that can be active at each measurement step. As a result, sensor scheduling algorithms must be employed. Notwithstanding, current sensor scheduling algorithms for batch state estimation scale poorly with the system size and the time horizon. In addition, current sensor scheduling algorithms for Kalman filtering, although they scale better, provide no performance guarantees or approximation bounds for the minimization of the batch state estimation error. In this paper, one of our main contributions is to provide an algorithm that enjoys both the estimation accuracy of the batch state scheduling algorithms and the low time complexity of the Kalman filtering scheduling algorithms. In particular: 1) our algorithm is near-optimal: it achieves a solution up to a multiplicative factor 1/2 from the optimal solution, and this factor is close to the best approximation factor 1/e one can achieve in polynomial time for this problem; 2) our algorithm has (polynomial) time complexity that is not only lower than that of the current algorithms for batch state estimation; it is also lower than, or similar to, that of the current algorithms for Kalman filtering. We achieve these results by proving two properties for our batch state estimation error metric, which quantifies the square error of the minimum variance linear estimator of the batch state vector: a) it is supermodular in the choice of the sensors; b) it has a sparsity pattern (it involves matrices that are block tri-diagonal) that facilitates its evaluation at each sensor set.
Crowding Induces Entropically-Driven Changes to DNA Dynamics That Depend on Crowder Structure and Ionic Conditions

Macromolecular crowding plays a principal role in a wide range of biological processes including gene expression, chromosomal compaction, and viral infection. However, the impact that crowding has on the dynamics of nucleic acids remains a topic of debate. To address this problem, we use single-molecule fluorescence microscopy and custom particle-tracking algorithms to investigate the impact of varying macromolecular crowding conditions on the transport and conformational dynamics of large DNA molecules. Specifically, we measure the mean-squared center-of-mass displacements, as well as the conformational size, shape, and fluctuations, of individual 115 kbp DNA molecules diffusing through various in vitro solutions of crowding polymers. We determine the role of crowder structure and concentration, as well as ionic conditions, on the diffusion and configurational dynamics of DNA. We find that branched, compact crowders (10 kDa PEG, 420 kDa Ficoll) drive DNA to compact, whereas linear, flexible crowders (10 kDa, 500 kDa dextran) cause DNA to elongate. Interestingly, the extent to which DNA mobility is reduced by increasing crowder concentrations appears largely insensitive to crowder structure (branched vs linear), despite the highly different configurations DNA assumes in each case. We also characterize the role of ionic conditions on crowding-induced DNA dynamics. We show that both DNA diffusion and conformational size exhibit an emergent non-monotonic dependence on salt concentration that is not seen in the absence of crowders.
Overconvergent unit-root $F$-isocrystals and isotriviality

We show that a semisimple overconvergent "absolutely unit-root" F-isocrystal on a geometrically connected smooth variety over a finite field becomes constant over a finite covering.
Topological Realizations of Line Arrangements

A venerable problem in combinatorics and geometry asks whether a given incidence relation may be realized by a configuration of points and lines. The classic version of this would ask for algebraic lines over some field or possibly real pseudolines: embedded circles (isotopic to $RP^1$) in the real projective plane. In this paper we investigate whether a configuration is realized by a collection of $2$-spheres embedded, in the symplectic, smooth, or topological (locally flat) categories, in the complex projective plane. We find obstructions to realizability in the topological category, which apply to configurations specified by all projective planes over a finite field. Such obstructions are used to show that certain contact graph manifolds are not (strongly) symplectically fillable. We also show that a configuration of real pseudolines can be complexified to give a configuration of smooth, indeed symplectically embedded, $2$-spheres.
Set Theory-Based Safety Supervisory Control for Wind Turbines to Ensure Adequate Frequency Response

Inadequate frequency response can arise due to a high penetration of wind turbine generators (WTGs) and requires a frequency support function to be integrated in the WTG. The appropriate design for these controllers to ensure adequate response has not been investigated thoroughly. In this paper, a safety supervisory control (SSC) is proposed to synthesize the supportive modes in WTGs to guarantee performance. The concept, region of safety (ROS), is stated for safe switching synthesis. An optimization formula is proposed to calculate the largest ROS. By assuming a polynomial structure, the problem can be solved by a sum of squares program. A feasible result will generate a polynomial, the zero sublevel set of which represents the ROS and is employed as the safety supervisor. A decentralized communication architecture is proposed for small-scale systems. Moreover, a scheduling loop is suggested so that the supervisor updates its boundary with respect to the renewable penetration level to be robust with respect to variations in system inertia. The proposed controller is first verified on a single-machine three-phase nonlinear microgrid, and then implemented on the IEEE 39-bus system. Both results indicate that the proposed framework and control configuration can guarantee adequate response without excessive conservativeness.
Toric geometry of $SL_2(\mathbb{C})$ free group character varieties from outer space

Culler and Vogtmann defined a simplicial space , called outer space, to study the outer automorphism group of the free group . Using representation theoretic methods, we give an embedding of into the analytification of , the character variety of , reproving a result of Morgan and Shalen. Then we show that every point contained in a maximal cell of defines a flat degeneration of to a toric variety . We relate and topologically by showing that there is a surjective, continuous, proper map . We then show that this map is a symplectomorphism on a dense open subset of with respect to natural symplectic structures on and . In this way, we construct an integrable Hamiltonian system in for each point in a maximal cell of , and we show that each defines a topological decomposition of derived from the decomposition of by its torus orbits. Finally, we show that the valuations coming from the closure of a maximal cell in all arise as divisorial valuations built from an associated projective compactification of .
Adversarial Symmetric Variational Autoencoder

A new form of variational autoencoder (VAE) is developed, in which the joint distribution of data and codes is considered in two (symmetric) forms: (i) from observed data fed through the encoder to yield codes, and (ii) from latent codes drawn from a simple prior and propagated through the decoder to manifest data. Lower bounds are learned for marginal log-likelihood fits observed data and latent codes. When learning with the variational bound, one seeks to minimize the symmetric Kullback-Leibler divergence of joint density functions from (i) and (ii), while simultaneously seeking to maximize the two marginal log-likelihoods. To facilitate learning, a new form of adversarial training is developed. An extensive set of experiments is performed, in which we demonstrate state-of-the-art data reconstruction and generation on several image benchmarks datasets.
Generalization and variations of Pellet’s theorem for matrix polynomials

Abstract We derive a generalized matrix version of Pellet’s theorem, itself based on a generalized Rouche theorem for matrix-valued functions, to generate upper, lower, and internal bounds on the eigenvalues of matrix polynomials. Variations of the theorem are suggested to try and overcome situations where Pellet’s theorem cannot be applied.
The representation theory of the exceptional Lie superalgebras F(4) and G(3)

This thesis is a resolution of three related problems proposed by Yu. I. Manin and V. Kac for the so-called exceptional Lie superalgebras F(4) and G(3). The first problem posed by Kac (1978) is the problem of finding character and superdimension formulae for the simple modules. The second problem posed by Kac (1978) is the problem of classifying all indecomposable representations. The third problem posed by Manin (1981) is the problem of constructing the superanalogue of Borel-Weil-Bott theorem.
Rigged modules II: multipliers and duality

In a previous paper with Kashyap we generalized the theory of $W^*$-modules to the setting of modules over nonselfadjoint dual operator algebras, obtaining the class of weak*-rigged modules. The present paper and its contemporaneous predecessor comprise the sequel which we promised at that time would be forthcoming. We give many new results about rigged and weak*-rigged modules and their tensor products, such as an Eilenberg-Watts type theorem.
Compressed Sensing in Multi-Hop Large-Scale Wireless Sensor Networks Based on Routing Topology Tomography

Data acquisition from multi-hop large-scale outdoor wireless sensor network (WSN) deployments for environmental monitoring is full of challenges. This is because of the severe resource constraints on tiny battery-operated motes (e.g., bandwidth, memory, power, and computing capacity), the data acquisition volume from large-scale WSNs, and the highly dynamic wireless link conditions in outdoor harsh communication environments. We present a novel compressed sensing approach, which can recover the sensing data at the sink with high fidelity when a very few data packets need to be collected, leading to a significant reduction of the network transmissions and thus an extension of the WSN lifetime. Interplaying with the dynamic WSN routing topology, the proposed approach is both efficient and simple to implement on the resource-constrained motes without motes’ storing of any part of the random projection matrix, as opposed to other existing compressed sensing-based schemes. We further propose a systematic method via machine learning to find a suitable representation basis, for any given WSN deployment and data field, which is both sparse and incoherent with the random projection matrix in compressed sensing for data collection. We validate our approach and evaluate its performance using a real-world outdoor multi-hop WSN testbed deployment in situ . The results demonstrate that our approach significantly outperforms existing compressed sensing approaches by reducing data recovery errors by an order of magnitude for the entire WSN observation field while drastically reducing wireless communication costs at the same time.
General superpositions of Gaussian beams and propagation errors

Gaussian beams are asymptotically valid high frequency solutions concentrated on a single curve through the physical domain, and superposition of Gaussian beams provides a powerful tool to generate more general high frequency solutions to PDEs. We present a superposition of Gaussian beams over an arbitrary bounded set of dimension $m$ in phase space, and show that the tools recently developed in [ H. Liu, O. Runborg, and N. M. Tanushev, Math. Comp., 82: 919--952, 2013] can be applied to obtain the propagation error of order $k^{1- \frac{N}{2}- \frac{d-m}{4}}$, where $N$ is the order of beams and $d$ is the spatial dimension. Moreover, we study the sharpness of this estimate in examples.