cssi/SciSciGPT-SciSciNet huggingface dataset:
Distinct Laminar Processing of Local and Global Context in Primate Primary Visual Cortex.

Summary Visual perception is affected by spatial context. In visual cortex, neuronal responses to stimuli inside the receptive field (RF) are suppressed by stimuli in the RF surround. To understand the circuits and cortical layers processing spatial context, we simultaneously recorded across all layers of macaque primary visual cortex while presenting stimuli at increasing distances from the recorded cells’ RF. We find that near versus far-surround stimuli activate distinct layers, thus revealing unique laminar contributions to the processing of local and global spatial context. Stimuli in the near-surround evoke the earliest subthreshold responses in superficial and upper-deep layers, and earliest suppression of spiking responses in superficial layers. Conversely, far-surround stimuli evoke the earliest subthreshold responses in feedback-recipient layer 1 and lower-deep layers, and earliest suppression of spiking responses almost simultaneously in all layers, except 4C, where suppression emerges last. Our results suggest distinct circuits for local and global signal integration. Video Abstract Download : Download video (54MB)
Sialic acid aldolase-catalyzed condensation of pyruvate and N-substituted mannosamine: A useful method for the synthesis of N-substituted sialic acids

Abstract Several N-substituted sialic acids were synthesized based on the sialic acid aldolase-catalyzed aldol condensation of N-substituted mannosamines and pyruvate.
Palladium-Catalyzed Homocoupling Reactions between Two Csp3−Csp3 Centers

A novel palladium-catalyzed coupling reaction between two Csp3−Csp3 centers has been investigated. This protocol is initiated by the oxidative addition of an α-halo carbonyl compound to a palladium(0) species, followed by the double transmetalation. The key dialkyl palladium intermediate undergoes reductive elimination to form the desired coupling product.
Covalent Protein Labeling by SpyTag–SpyCatcher in Fixed Cells for Super‐Resolution Microscopy

Labeling proteins with high specificity and efficiency is a fundamental prerequisite for microscopic visualization of subcellular protein structures and interactions. Although the comparatively small size of epitope tags makes them less perturbative to fusion proteins, they require the use of large antibodies that often limit probe accessibility and effective resolution. Here we use the covalent SpyTag-SpyCatcher system as an epitope-like tag for fluorescent labeling of intracellular proteins in fixed cells for both conventional and super-resolution microscopy. We also applied this method to endogenous proteins by gene editing, demonstrating its high labeling efficiency and capability for isoform-specific labeling.
Palladium-catalyzed heteroannulation of cyclic alkenes by functionally substituted aryl iodides

Indolines and 2,3-dihydrobenzofurans are produced in good yields by the Pd(0)-catalyzed heteroannulation of cyclic and bicyclic alkenes by o-amino- and o-hydroxyaryl iodides. These processes are only successful with cyclic olefins in which the key alkylpalladium intermediate cannot undergo facile palladium β-hydride elimination. These reactions appear to involve: (1) oxidative addition of the aryl iodide to the palladium catalyst, (2) arylpalladation of the olefin, (3) possible coordination of the internal nucleophile to the palladium, (4) formation of a six-membered palladacycle, and (5) reductive elimination of the organopalladium intermediate to give the heteroannulation product and regenerate Pd(0).
Syntheses, Structures, and Optical Properties of Yellow Ce2SiS5, Ce6Si4S17, and Ce4Si3S12 Materials

The Ce−S−Si system has been explored in search of new, yellow nontoxic pigments. We prepared a new Ce−S−Si phase (Ce6Si4S17), determined the crystal structures of Ce2SiS5, Ce4Si3S12, and Ce6Si4S17, and measured the chromatic properties of these Ce−S−Si phases. The differences in the yellow hue of these compounds were probed by analyzing their Ce3+ ion environments and calculating their electronic band structures. Ce6Si4S17 is distinguished from Ce2SiS5 and Ce4Si3S12 in terms of the Ce3+ structural environment and the Ce3+ 4f1→5d0 transition gap. This gap is wider for Ce6Si4S17 than for Ce2SiS5 and Ce4Si3S12 (i.e., 2.51 vs. ∼2.36 eV), and Ce6Si4S17 exhibits room-temperature luminescence whereas Ce2SiS5 and Ce4Si3S12 do not. Ce4Si3S12 and Ce6Si4S17 possess chromatic properties similar to those found for industrial pigments such as PbCrO4, BiVO4, and CdS, and show thermal and chemical stabilities.
Synthesis of benzo[b]thiophenes by electrophilic cyclization

Abstract 2,3-Disubstituted benzo[b]thiophenes are readily prepared in excellent yields under very mild reaction conditions by the Pd/Cu-catalyzed cross-coupling of commercially available o-iodothioanisole and terminal alkynes, followed by electrophilic cyclization by I2, Br2, NBS, p-O2NC6H4SCl or PhSeCl.
Synthesis of 4-sulfonatobenzylphosphines and their application in aqueous-phase palladium-catalyzed cross-coupling

Abstract Aqueous-biphasic catalysis offers the potential for safer and more environmentally sustainable synthetic processes. In addition, hydrophilic supporting ligands allow homogeneous catalysts to be readily separated from organic products and potentially reused. The synthesis of two new water-soluble ligand precursors, di-tert-butyl(4-sulfonatobenzyl)phosphonium and di-1-adamantyl(4-sulfonatobenzyl)phosphonium, are reported. The air-stable, zwitterionic phosphonium salts were prepared by the reaction of dialkylphosphines with ethyl 4-bromomethylbenzenesulfonate, which results in a one-pot alkylation followed by deprotection of the ethyl sulfonate. This methodology provides an operationally simpler route to sulfonated benzylphosphines than electrophilic sulfonation. The new phosphine ligands were applied to aqueous-phase Suzuki and Sonogashira couplings of aryl bromides.
An efficient asymmetric synthesis of (2S,3S)- and (2R,3R)-β-hydroxyornithine

Abstract Asymmetric syntheses of (2 S ,3 S )- and (2 R ,3 R )-β-hydroxyornithine have been achieved in four steps and 46% overall yield. The key step in this synthesis involved an aldol reaction between a chiral glycine boron enolate and (3-oxo-propyl)-carbamic acid benzyl ester.
Total synthesis of (±)-heliannuol C and E via aromatic Claisen rearrangement

The total synthesis of heliannuol C and E from a common intermediate are described. Key steps in the synthesis include a regioselective aromatic Claisen rearrangement to install the (1-vinyl)-4-methyl-3-pentenyl substituent and regioselective biomimetic 7-endo and 6-exo phenol epoxide cyclizations to form the cyclic ether moieties.
A literature review at genome scale: improving clinical variant assessment.

Over 150,000 variants have been reported to cause Mendelian disease in the medical literature. It is still difficult to leverage this knowledge base in clinical practice, as many reports lack strong statistical evidence or may include false associations. Clinical laboratories assess whether these variants (along with newly observed variants that are adjacent to these published ones) underlie clinical disorders. We investigated whether citation data—including journal impact factor and the number of cited variants (NCV) in each gene with published disease associations—can be used to improve variant assessment. Surprisingly, we found that impact factor is not predictive of pathogenicity, but the NCV score for each gene can provide statistical support for prediction of pathogenicity. When this gene-level citation metric is combined with variant-level evolutionary conservation and structural features, classification accuracy reaches 89.5%. Further, variants identified in clinical exome sequencing cases have higher NCVs than do simulated rare variants from the Exome Aggregation Consortium database within the same set of genes and functional consequences (P < 2.22 × 10−16). Aggregate citation data can complement existing variant-based predictive algorithms, and can boost their performance without the need to access and review large numbers of papers. The NCV is a slow-growing metric of scientific knowledge about each gene’s association with disease.
A modular synthesis of chiral aminoindanol-derived imidazolium salts

Abstract A modular synthesis of N-substituted chiral imidazolium salts derived from (1R,2S)-(+)-1-amino-2-indanol is described. A wide range of amines are amenable to late stage introduction of the N-substituent to provide N-aryl, N-alkyl, and N-amino imidazolium salts, which serve as precursors to chiral N-heterocyclic carbenes (NHCs). A multi-gram synthesis of the N-mesityl derivative provides an important imidazolium salt for ongoing studies aimed at the development and understanding of NHC-catalyzed annulations. Critical to the success of this synthetic strategy is a chemoselective alkylation, 6-exo-tet ring closure of a formamide onto an epoxide, and a heterocyclic interconversion strategy.
Phosphatidylinositol 4,5 Bisphosphate Controls the cis and trans Interactions of Synaptotagmin 1

Abstract Synaptotagmin 1 acts as the Ca2+ sensor for synchronous neurotransmitter release; however, the mechanism by which it functions is not understood and is presently a topic of considerable interest. Here, we describe measurements on full-length membrane-reconstituted synaptotagmin 1 using site-directed spin labeling in which we characterize the linker region as well as the cis (vesicle membrane) and trans (cytoplasmic membrane) binding of its two C2 domains. In the full-length protein, the C2A domain does not undergo membrane insertion in the absence of Ca2+; however, the C2B domain will bind to and penetrate in trans to a membrane containing phosphatidylinositol 4,5 bisphosphate, even if phosphatidylserine (PS) is present in the cis membrane. In the presence of Ca2+, the Ca2+ binding loops of C2A and C2B both insert into the membrane interface; moreover, C2A preferentially inserts into PS-containing bilayers and will bind in a cis configuration to membranes containing PS even if a phosphatidylinositol 4,5 bisphosphate membrane is presented in trans. The data are consistent with a bridging activity for synaptotagmin 1 in which the two domains bind to opposing vesicle and plasma membranes. The failure of C2A to bind membranes in the absence of Ca2+ and the long unstructured segment linking C2A to the vesicle membrane indicates that synaptotagmin 1 could act to significantly shorten the vesicle-plasma membrane distance with increasing levels of Ca2+.
Extended field-of-view single-molecule imaging by highly inclined swept illumination

Single-molecule imaging inside cells is a valuable tool to study subcellular structures, gene expression, and the dynamics of biomolecules. Here, we present highly inclined swept tile illumination microscopy. By sweeping a thin highly inclined and laminated optical sheet (HILO) with confocal slit detection, our method provides a twofold thinner illumination and greater than fortyfold larger imaging area than conventional HILO microscopy, enabling 3D single-molecule imaging with a high signal-to-background ratio. We demonstrate single-molecule mRNA imaging with a few probes or a single probe in cultured cells and mouse brain tissues, and video-rate live-cell imaging.
Chemistry of Tetraazapentalenes

2,4,8,10-Tetranitrobenzotriazolo[2,1-a]benzotriazole (TACOT), although thermally very stable and insensitive as an explosive, is susceptible to attack by nucleophiles. Reaction with azide ion results in displacement of nitro groups at the 4,10-positions, treatment with methoxide ion effects displacement of the hydrogen atom at the 1-position and scission of the remote triazole ring, while “vicarious nucleophilic amination” displaces all the aromatic hydrogens. 3,5,7-Trinitro-1,2,3-triazolo[2,1-a]benzotriazole and 3,5,7-trinitro-1,2,3-triazolo[1,2-a]benzotriazole are prepared readily by nitration of the parent triazolobenzotriazoles. However they are thermally less stable than TACOT and more sensitive to initiation by impact. Furthermore, attempted further nitration and reaction with nucleophiles such as azide and methoxide ions both effect scission of the triazole ring to leave 4,6-dinitrobenzotriazole.
13C and 1H NMR analysis of the nitration products of 2-amino-4-oxo-(3H)-5-trifluoromethylquinazoline and 2-amino-4-oxo-(3H)-5-fluoroquinazoline

Nitration of 2-amino-4-oxo-(3H)-5-trifluoromethylquinazoline is shown to occur exclusively at C6 as determined from an analysis of long range 1H and 19F scalar couplings to ring carbons. Nitration of 2-amino-4-oxo-(3H)-5-fluoroquinazoline is found to occur both at C6 and C8 as evident from an analysis of the 19F and 1H couplings of the ring protons.
Metal alkoxide catalysis of catecholborane and borane reductions. Mechanistic studies

Abstract Catalytic quantities of transition metal alkoxides such as Ti(O i Pr) 4 have been found to accelerate dramatically the rate of catecholborane and BH 3 ·THF reductions of ketones. Experiments suggest catalysis is achieved by the formation of alkoxyborohydrides.
MEDIUM RING ETHERS VIA 1,2-SHIFT OF ACETAL-DERIVED OXONIUM YLIDES

Abstract Cyclic acetals and ketals with pendant diazoketones rearranged to O-bridged medium ring ethers in the presence of catalytic Rh2(OAc)4 or Cu(hfacac)2. This process proceeds via fused bicyclic oxonium ylides which undergo [1,2]-shift reactions. The observation of efficient migration by alkyl substituted carbons lacking any conjugating groups is especially notable. Overall, this chemistry fumishes functionalized medium ring ethers in a few steps from simple precursors.
Intracellular Signaling by the comRS System in Streptococcus mutans Genetic Competence

ABSTRACT Entry into genetic competence in streptococci is controlled by ComX, an alternative sigma factor for genes that enable the import of exogenous DNA. In Streptococcus mutans, the immediate activator of comX is the ComRS quorum system. ComS is the precursor of XIP, a seven-residue peptide that is imported into the cell and interacts with the cytosolic receptor ComR to form a transcriptional activator for both comX and comS. Although intercellular quorum signaling by ComRS has been demonstrated, observations of bimodal expression of comX suggest that comRS may also function as an intracellular feedback loop, activating comX without export or detection of extracellular XIP. Here we used microfluidic and single-cell methods to test whether ComRS induction of comX requires extracellular XIP or ComS. We found that individual comS-overexpressing cells activate their own comX, independently of the rate at which their growth medium is replaced. However, in the absence of lysis they do not activate comS-deficient mutants growing in coculture. We also found that induction of comR and comS genes introduced into Escherichia coli cells leads to activation of a comX reporter. Therefore, ComRS control of comX does not require either the import or extracellular accumulation of ComS or XIP or specific processing of ComS to XIP. We also found that endogenously and exogenously produced ComS and XIP have inequivalent effects on comX activation. These data are fully consistent with identification of intracellular positive feedback in comS transcription as the origin of bimodal comX expression in S. mutans. IMPORTANCE The ComRS system can function as a quorum sensing trigger for genetic competence in S. mutans. The signal peptide XIP, which is derived from the precursor ComS, enters the cell and interacts with the Rgg-type cytosolic receptor ComR to activate comX, which encodes the alternative sigma factor for the late competence genes. Previous studies have demonstrated intercellular signaling via ComRS, although release of the ComS or XIP peptide to the extracellular medium appears to require lysis of the producing cells. Here we tested the complementary hypothesis that ComRS can drive comX through a purely intracellular mechanism that does not depend on extracellular accumulation or import of ComS or XIP. By combining single-cell, coculture, and microfluidic approaches, we demonstrated that endogenously produced ComS can enable ComRS to activate comX without requiring processing, export, or import. These data provide insight into intracellular mechanisms that generate noise and heterogeneity in S. mutans competence.
Synthesis of (−)-lapatin B

Abstract The synthesis of (−)-lapatin B (1) has been achieved from l -tryptophan. The key reactions involve oxidative cyclization of N,N-diacetylglyantrypine (8) using PhI(OH)(OTs), and an indole-to-oxindole transformation in the penultimate step.
Synthesis and Structure of BaPtIn3 and BaTl0.63In3.33. Two Contrasting Examples of Preferential Site Occupation in BaAl4-Type Structures†

The title compounds have been synthesised by high temperature means and characterized by single crystal X-ray diffraction analysis. The compounds crystallize in the tetragonal structure type of BaAl4, I4/mmm, Z = 2 (a = 4.8130(7), 5.0196(8) A; c = 11.669(2), 11.900(3) A for BaPtIn3 and BaTl0.63In3.37, respectively).Platinum and thallium randomly substitute for 50 % of the In in the apical 4e and for 30 % in the basal 4d positions in the two networks, respectively. Consistent with both size and relative electronegativity factors, the basal positions in BaAl4-type structure are appropriate for substitution by dimensionally and chemically similar atoms (Tl), which is different from the apical sites in which electronegativities or bond strengths are more important (Pt).
Stabilization of an All-Nitrogen Molecule by Oxygen Insertion: Dissociation Pathways of N8O6

Nitrogen molecules Nx have been the subject of much recent research because of their potential as high energy density materials (HEDM). The reaction Nx → (x/2) N2 is exothermic by more than 50 kcal/mol per nitrogen atom. The difficulty in identifying practical nitrogen HEDM is that many small Nx molecules are not kinetically stable enough to serve as practical energy sources. Small three-coordinate Nx cages with all single bonds are especially unstable, due to the high angle strain and torsional strain of the molecules. However, the strain in these molecules can be relieved by the insertion of oxygen atoms into the N−N single bonds. For example, if an N8 cube has oxygen inserted into all of its N−N bonds, a molecule of N8O12 would result. The molecule would be much less strained than cubic N8, but it may be possible to stabilize the N8 cube with less than 12 oxygen atoms. In the present work, a molecule of N8O6 is examined by theoretical calculations to determine the energetics of its dissociation pathway...
Impact of microbial iron oxide reduction on the transport of diffusible tracers and non-diffusible nanoparticles in soils

Abstract In subsurface bioremediation, electron donor addition promotes microbial Fe(III)-oxide mineral reduction that could change soil pore structure, release colloids, and alter soil surface properties. These processes in turn may impact bioremediation rates and the ultimate fate of contaminants. Columns packed with water-stable, Fe-oxide-rich soil aggregates were infused with acetate-containing artificial groundwater and operated for 20 d or 60 d inside an anoxic chamber. Soluble Fe(II) and soil colloids were detected in the effluent within one week after initiation of the acetate addition, demonstrating Fe(III)-bioreduction and colloid formation. Diffusible Br−, less diffusible 2,6-difluorobenzoate (DFBA), and non-diffusible silica-shelled silver nanoparticles (SSSNP) were used as tracers in transport experiments before and after the bioreduction. The transport of Br− was not influenced by the bioreduction. DFBA showed earlier breakthrough and less tailing after the bioreduction, suggesting alterations in flow paths and soil surface chemistry during the 20-d bioreduction treatment. Similarly, the bioreduction increased the transport of SSSNP very significantly, with mass recovery increasing from 1.7% to 25.1%. Unexpectedly, the SSSNP was completely retained in the columns when the acetate injection was extended from 20 to 60 d, while the mass recovery of DFBA decreased from 89.1% to 84.1% and Br− showed no change. The large change in the transport of SSSNP was attributed to soil aggregate breakdown and colloid release (causing mechanical straining of SSSNP) and the exposure of iron oxide surfaces previously unavailable within aggregate interiors (facilitating attachment of SSSNP). These results suggest a time-dependent fashion of microbial effect on the transport of diffusivity-varying tracers.
Caterpillars lack a resident gut microbiome.

Many animals are inhabited by microbial symbionts that influence their hosts’ development, physiology, ecological interactions, and evolutionary diversification. However, firm evidence for the existence and functional importance of resident microbiomes in larval Lepidoptera (caterpillars) is lacking, despite the fact that these insects are enormously diverse, major agricultural pests, and dominant herbivores in many ecosystems. Using 16S rRNA gene sequencing and quantitative PCR, we characterized the gut microbiomes of wild leaf-feeding caterpillars in the United States and Costa Rica, representing 124 species from 15 families. Compared with other insects and vertebrates assayed using the same methods, the microbes that we detected in caterpillar guts were unusually low-density and variable among individuals. Furthermore, the abundance and composition of leaf-associated microbes were reflected in the feces of caterpillars consuming the same plants. Thus, microbes ingested with food are present (although possibly dead or dormant) in the caterpillar gut, but host-specific, resident symbionts are largely absent. To test whether transient microbes might still contribute to feeding and development, we conducted an experiment on field-collected caterpillars of the model species Manduca sexta. Antibiotic suppression of gut bacterial activity did not significantly affect caterpillar weight gain, development, or survival. The high pH, simple gut structure, and fast transit times that typify caterpillar digestive physiology may prevent microbial colonization. Moreover, host-encoded digestive and detoxification mechanisms likely render microbes unnecessary for caterpillar herbivory. Caterpillars illustrate the potential ecological and evolutionary benefits of independence from symbionts, a lifestyle that may be widespread among animals.
Is great information good enough? Evidence from physicians as patients.

Abstract We place an upper bound on the degree to which policies aimed at improving the information deficiencies of patients may lead to greater adherence to clinical guidelines and recommended practices. To do so, we compare the degree of adherence attained by a group of patients that should have the best possible information on health care practices—i.e., physicians as patients—with that attained by a comparable group of non-physician patients, taking various steps to account for unobservable differences between the two groups. Our results suggest that physicians, at best, do only slightly better in adhering to both low- and high-value care guidelines than non-physicians.
Hidden in Plain Sight For Too Long: Using Text Mining Techniques to Shine a Light on Workplace Sexism and Sexual Harassment

Objective: The goal of this study is to understand how people experience sexism and sexual harassment in the workplace by discovering themes in 2,362 experiences posted on the Everyday Sexism Project's website this http URL. Method: This study used both quantitative and qualitative methods. The quantitative method was a computational framework to collect and analyze a large number of workplace sexual harassment experiences. The qualitative method was the analysis of the topics generated by a text mining method. Results: Twenty-three topics were coded and then grouped into three overarching themes from the sex discrimination and sexual harassment literature. The Sex Discrimination theme included experiences in which women were treated unfavorably due to their sex, such as being passed over for promotion, denied opportunities, paid less than men, and ignored or talked over in meetings. The Sex Discrimination and Gender harassment theme included stories about sex discrimination and gender harassment, such as sexist hostility behaviors ranging from insults and jokes invoking misogynistic stereotypes to bullying behavior. The last theme, Unwanted Sexual Attention, contained stories describing sexual comments and behaviors used to degrade women. Unwanted touching was the highest weighted topic, indicating how common it was for website users to endure being touched, hugged or kissed, groped, and grabbed. Conclusions: This study illustrates how researchers can use automatic processes to go beyond the limits of traditional research methods and investigate naturally occurring large scale datasets on the internet to achieve a better understanding of everyday workplace sexism experiences.
Prescribing capacitary curvature measures on planar convex domains

For $$p\in (1,2]$$ and a bounded, convex, nonempty, open set $$\Omega \subset {\mathbb {R}}^2$$ let $$\mu _p({\bar{\Omega }},\cdot )$$ be the p-capacitary curvature measure (generated by the closure $${\bar{\Omega }}$$ of $$\Omega $$) on the unit circle $${\mathbb {S}}^1$$. This paper shows that such a problem of prescribing $$\mu _p$$ on a planar convex domain: “Given a finite, nonnegative, Borel measure $$\mu $$ on $${\mathbb {S}}^1$$, find a bounded, convex, nonempty, open set $$\Omega \subset {\mathbb {R}}^2$$ such that $$d\mu _p({\bar{\Omega }},\cdot )=d\mu (\cdot )$$” is solvable if and only if $$\mu $$ has centroid at the origin and its support $$\mathrm {supp}(\mu )$$ does not comprise any pair of antipodal points. And, the solution is unique up to translation. Moreover, if $$d\mu _p({\bar{\Omega }},\cdot )=\psi (\cdot )\,d\ell (\cdot )$$ with $$\psi \in C^{k,\alpha }$$ and $$d\ell $$ being the standard arc-length element on $${\mathbb {S}}^1$$, then $$\partial \Omega $$ is of $$C^{k+2,\alpha }$$.
Dense 3-D Mapping with Spatial Correlation via Gaussian Filtering

Constructing an occupancy representation of the environment is a fundamental problem for robot autonomy. Many accurate and efficient methods exist that address this problem but most assume that the occupancy states of different elements in the map representation are statistically independent. The focus of this paper is to provide a model that captures correlation of the occupancy of map elements. Correlation is important not only for improved accuracy but also for quantifying uncertainty in the map and for planning autonomous mapping trajectories based on the correlation among known and unknown areas. Recent work proposes Gaussian Process (GP) regression to capture covariance information and enable resolution-free occupancy estimation. The drawback of techniques based on GP regression (or classification) is that the computation complexity scales cubically with the length of the measurement history. Our main contribution is a new approach for occupancy mapping that models the binary nature of occupancy measurements precisely, via a Bernoulli distribution, and provides an efficient approximation of GP classification with complexity that does not scale with time. We prove that the error between the estimates provided by our method and those provided by GP classification is negligible. The proposed method is evaluated using both simulated data and real data collected using a Velodyne Puck 3-D range sensor.
Exploiting Symmetry and/or Manhattan Properties for 3D Object Structure Estimation from Single and Multiple Images

Many man-made objects have intrinsic symmetries and Manhattan structure. By assuming an orthographic projection model, this paper addresses the estimation of 3D structures and camera projection using symmetry and/or Manhattan structure cues, which occur when the input is single-or multiple-image from the same category, e.g., multiple different cars. Specifically, analysis on the single image case implies that Manhattan alone is sufficient to recover the camera projection, and then the 3D structure can be reconstructed uniquely exploiting symmetry. However, Manhattan structure can be difficult to observe from a single image due to occlusion. To this end, we extend to the multiple-image case which can also exploit symmetry but does not require Manhattan axes. We propose a novel rigid structure from motion method, exploiting symmetry and using multiple images from the same category as input. Experimental results on the Pascal3D+ dataset show that our method significantly outperforms baseline methods.
Conjectures and Computations about Veronese Syzygies

We formulate several conjectures which shed light on the structure of Veronese syzygies of projective spaces. These conjectures are motivated by experimental data that we derived from a high-speed ...
Synthesis of Gaussian trees with correlation sign ambiguity: An information theoretic approach

A new layered encoding scheme is proposed to effectively generate a random vector with prescribed joint density that induces a latent Gaussian tree structure. The encoding algorithm relies on the learned structure of tree to use minimal number of common random variables to synthesize the desired density, which we argue such algorithm is also computationally efficient. We characterize the achievable rate region for the rate tuples of multi-layer latent Gaussian tree, through which the number of bits needed to simulate such Gaussian joint density are determined. The random sources used in our algorithm are the latent variables at the top layer of tree along with Bernoulli sign inputs, which capture the correlation signs between the variables. In latent Gaussian trees the pairwise correlation signs between the variables are intrinsically unrecoverable. Such information is vital since it completely determines the direction in which two variables are associated. As a by-product of determining the achievable rate region, we quantify the amount of information loss due to unrecoverable sign information. It is shown that maximizing the achievable rate-region is equivalent to finding the worst case density for Bernoulli sign inputs where maximum amount of sign information is lost.
Bell inequalities from group actions of single-generator groups

We study a method of generating Bell inequalities by using group actions of single-generator Abelian groups. Two parties, Alice and Bob, each make one of $M$ possible measurements on a system, with each measurement having $K$ possible outcomes. The probabilities for the outcomes of these measurements are $P({a}_{j}=k,{b}_{{j}^{\ensuremath{'}}}={k}^{\ensuremath{'}})$, where $j,{j}^{\ensuremath{'}}\ensuremath{\in}{1,2,...,M}$ and $k,{k}^{\ensuremath{'}}\ensuremath{\in}{0,1,...,K\ensuremath{-}1}$. The sums of some subsets of these probabilities have upper bounds when the probabilities result from a local, realistic theory that can be violated if the probabilities come from quantum mechanics. In our case the subsets of probabilities are generated by a group action, in particular, a representation of a single-generator group acting on product states in a tensor-product Hilbert space. We show how this works for several cases, including $M=2$, $K=3$, and general $M$, $K=2$. We also discuss the resulting inequalities in terms of nonlocal games.
On the geometry of stabilizer states

Large-scale quantum computation is likely to require massive quantum error correction (QEC). QEC codes and circuits are described via the stabilizer formalism, which represents stabilizer states by keeping track of the operators that preserve them. Such states are obtained by stabilizer circuits (consisting of CNOT, Hadamard and Phase gates) and can be represented compactly on conventional computers using Θ(n2) bits, where n is the number of qubits [18]. As an additional application, the work in [1, 2] suggests the use of superpositions of stabilizer states to represent arbitrary quantum states. To aid in such applications and improve our understanding of stabilizer states, we characterize and count nearest-neighbor stabilizer states, quantify the distribution of angles between pairs of stabilizer states, study succinct stabilizer superpositions and stabilizer bivectors, explore the approximation of non-stabilizer states by single stabilizer states and short linear combinations of stabilizer states, develop an improved inner-product computation for stabilizer states via synthesis of compact canonical stabilizer circuits, propose an orthogonalization procedure for stabilizer states, and evaluate several of these algorithms empirically.
Superconducting metamaterials and qubits

Superconducting thin-film metamaterial resonators can provide a dense microwave mode spectrum with potential applications in quantum information science. We report on the fabrication and low-temperature measurement of metamaterial transmission-line resonators patterned from Al thin films. We also describe multiple approaches for numerical simulations of the microwave properties of these structures, along with comparisons with the measured transmission spectra. The ability to predict the mode spectrum based on the chip layout provides a path towards future designs integrating metamaterial resonators with superconducting qubits.
Beyond the spectral theorem: Spectrally decomposing arbitrary functions of nondiagonalizable operators

Nonlinearities in finite dimensions can be linearized by projecting them into infinite dimensions. Unfortunately, the familiar linear operator techniques that one would then hope to use often fail since the operators cannot be diagonalized. The curse of nondiagonalizability also plays an important role even in finite-dimensional linear operators, leading to analytical impediments that occur across many scientific domains. We show how to circumvent it via two tracks. First, using the well-known holomorphic functional calculus, we develop new practical results about spectral projection operators and the relationship between left and right generalized eigenvectors. Second, we generalize the holomorphic calculus to a meromorphic functional calculus that can decompose arbitrary functions of nondiagonalizable linear operators in terms of their eigenvalues and projection operators. This simultaneously simplifies and generalizes functional calculus so that it is readily applicable to analyzing complex physical systems. Together, these results extend the spectral theorem of normal operators to a much wider class, including circumstances in which poles and zeros of the function coincide with the operator spectrum. By allowing the direct manipulation of individual eigenspaces of nonnormal and nondiagonalizable operators, the new theory avoids spurious divergences. As such, it yields novel insights and closed-form expressions across several areas of physics in which nondiagonalizable dynamics arise, including memoryful stochastic processes, open nonunitary quantum systems, and far-from-equilibrium thermodynamics. The technical contributions include the first full treatment of arbitrary powers of an operator, highlighting the special role of the zero eigenvalue. Furthermore, we show that the Drazin inverse, previously only defined axiomatically, can be derived as the negative-one power of singular operators within the meromorphic functional calculus and we give a new general method to construct it. We provide new formulae for constructing spectral projection operators and delineate the relations among projection operators, eigenvectors, and left and right generalized eigenvectors. By way of illustrating its application, we explore several, rather distinct examples. First, we analyze stochastic transition operators in discrete and continuous time. Second, we show that nondiagonalizability can be a robust feature of a stochastic process, induced even by simple counting. As a result, we directly derive distributions of the time-dependent Poisson process and point out that nondiagonalizability is intrinsic to it and the broad class of hidden semi-Markov processes. Third, we show that the Drazin inverse arises naturally in stochastic thermodynamics and that applying the meromorphic functional calculus provides closed-form solutions for the dynamics of key thermodynamic observables. Finally, we draw connections to the Ruelle–Frobenius–Perron and Koopman operators for chaotic dynamical systems and propose how to extract eigenvalues from a time-series.
Dense computability, upper cones, and minimal pairs

This paper concerns algorithms that give correct answers with (asymptotic) density $1$. A dense description of a function $g : \omega \to \omega$ is a partial function $f$ on $\omega$ such that $\left\{n : f(n) = g(n)\right\}$ has density $1$. We define $g$ to be densely computable if it has a partial computable dense description $f$. Several previous authors have studied the stronger notions of generic computability and coarse computability, which correspond respectively to requiring in addition that $g$ and $f$ agree on the domain of $f$, and to requiring that $f$ be total. Strengthening these two notions, call a function $g$ effectively densely computable if it has a partial computable dense description $f$ such that the domain of $f$ is a computable set and $f$ and $g$ agree on the domain of $f$. We compare these notions as well as asymptotic approximations to them that require for each $\epsilon > 0$ the existence of an appropriate description that is correct on a set of lower density of at least $1 - \epsilon$. We determine which implications hold among these various notions of approximate computability and show that any Boolean combination of these notions is satisfied by a c.e. set unless it is ruled out by these implications. We define reducibilities corresponding to dense and effectively dense reducibility and show that their uniform and nonuniform versions are different. We show that there are natural embeddings of the Turing degrees into the corresponding degree structures, and that these embeddings are not surjective and indeed that sufficiently random sets have quasiminimal degree. We show that nontrivial upper cones in the generic, dense, and effective dense degrees are of measure $0$ and use this fact to show that there are minimal pairs in the dense degrees.
Proof of the Log-Convex Density Conjecture

We completely characterize isoperimetric regions in R^n with density e^h, where h is convex, smooth, and radially symmetric. In particular, balls around the origin constitute isoperimetric regions of any given volume, proving the Log-Convex Density Conjecture due to Kenneth Brakke.
Towards a link theoretic characterization of smoothness

A theorem of Mumford states that, on complex surfaces, any normal isolated singularity whose link is diffeomorphic to a sphere is actually a smooth point. While this property fails in higher dimensions, McLean asks whether the contact structure that the link inherits from its embedding in the variety may suffice to characterize smooth points among normal isolated singularities. He proves that this is the case in dimension 3. In this paper, we use techniques from birational geometry to extend McLean's result to a large class of higher dimensional singularities. We also introduce a more refined invariant of the link using CR geometry, and conjecture that this invariant is strong enough to characterize smoothness in full generality.
Graph operations and upper bounds on graph homomorphism counts

We construct a family of countexamples to a conjecture of Galvin [5], which stated that for any n-vertex, d-regular graph G and any graph H (possibly with loops), hom(G,H)≤maxhom(Kd,d,H)n2d,hom(Kd+1,H)nd+1, where hom(G,H) is the number of homomorphisms from G to H. By exploiting properties of the graph tensor product and graph exponentiation, we also find new infinite families of H for which the bound stated above on hom(G,H) holds for all n-vertex, d-regular G. In particular, we show that if HWR is the complete looped path on three vertices, also known as the Widom–Rowlinson graph, then hom(G,H WR )≤hom(Kd+1,H WR )nd+1 for all n-vertex, d-regular G. This verifies a conjecture of Galvin.
Warped products admitting a curvature bound

Abstract This paper completes a fundamental construction in Alexandrov geometry. Previously we gave a new construction of metric spaces with curvature bounds either above or below, namely warped products with intrinsic metric space base and fiber, and with possibly vanishing warping functions – thereby extending the classical cone and suspension constructions from interval base to arbitrary base, and furthermore encompassing gluing constructions. This paper proves the converse, namely, all conditions of the theorems are necessary. Note that in the cone construction, both the construction and its converse are widely used. We also show that our theorems for curvature bounded above and below, respectively, are dual. We give the first systematic development of basic properties of warped products of metric spaces with possibly vanishing warping functions, including new properties.
Locality and Availability in Distributed Storage

This paper studies the problem of information symbol availability in codes: we refer to a systematic code as code with $(r, t)$ -availability if every information (systematic) symbol can be reconstructed from $t$ disjoint groups of other code symbols, each of the sizes at most $r$ . This paper shows that it is possible to construct codes that can support a scaling number of parallel reads while keeping the rate to be an arbitrarily high constant. It further shows that this is possible with the minimum Hamming distance arbitrarily close to the Singleton bound. This paper also presents a bound demonstrating a tradeoff between rate, minimum Hamming distance, and availability parameters. Our codes match the aforementioned bound, and their constructions rely on certain combinatorial structures. Resolvable designs provide one way to realize these required combinatorial structures. The two constructions presented in this paper require field sizes, which are linear and exponential in the code length, respectively. From a practical standpoint, our codes are relevant for distributed storage applications involving hot data, i.e., the information, which is frequently accessed by multiple processes in parallel.
Swapout: learning an ensemble of deep architectures

We describe Swapout, a new stochastic training method, that outperforms ResNets of identical network structure yielding impressive results on CIFAR-10 and CIFAR-100. Swapout samples from a rich set of architectures including dropout [20], stochastic depth [7] and residual architectures [5, 6] as special cases. When viewed as a regularization method swapout not only inhibits co-adaptation of units in a layer, similar to dropout, but also across network layers. We conjecture that swapout achieves strong regularization by implicitly tying the parameters across layers. When viewed as an ensemble training method, it samples a much richer set of architectures than existing methods such as dropout or stochastic depth. We propose a parameterization that reveals connections to exiting architectures and suggests a much richer set of architectures to be explored. We show that our formulation suggests an efficient training method and validate our conclusions on CIFAR-10 and CIFAR-100 matching state of the art accuracy. Remarkably, our 32 layer wider model performs similar to a 1001 layer ResNet model.
A learning and masking approach to secure learning

Deep Neural Networks (DNNs) have been shown to be vulnerable against adversarial examples, which are data points cleverly constructed to fool the classifier. In this paper, we introduce a new perspective on the problem. We do so by first defining robustness of a classifier to adversarial exploitation. Further, we categorize attacks in literature into high and low perturbation attacks. Next, we show that the defense problem can be posed as a learning problem itself and find that this approach effective against high perturbation attacks. For low perturbation attacks, we present a classifier boundary masking method that uses noise to randomly shift the classifier boundary at runtime. We also show that both our learning and masking based defense can work simultaneously to protect against multiple attacks. We demonstrate the efficacy of our techniques by experimenting with the MNIST and CIFAR-10 datasets.
The monodromy of real Bethe vectors for the Gaudin model

The Bethe algebras for the Gaudin model act on the multiplicity space of tensor products of irreducible $ \mathfrak{gl}_r $-modules and have simple spectrum over real points. This fact is proved by Mukhin, Tarasov and Varchenko who also develop a relationship to Schubert intersections over real points. We use an extension to $ \overline{M}_{0,n+1}(\mathbb{R}) $ of these Schubert intersections, constructed by Speyer, to calculate the monodromy of the spectrum of the Bethe algebras. We show this monodromy is described by the action of the cactus group $ J_n $ on tensor products of irreducible $ \mathfrak{gl}_r $-crystals.
On the relationship between conditional (CAR) and simultaneous (SAR) autoregressive models

Abstract We clarify relationships between conditional (CAR) and simultaneous (SAR) autoregressive models. We review the literature on this topic and find that it is mostly incomplete. Our main result is that a SAR model can be written as a unique CAR model, and while a CAR model can be written as a SAR model, it is not unique. In fact, we show how any multivariate Gaussian distribution on a finite set of points with a positive-definite covariance matrix can be written as either a CAR or a SAR model. We illustrate how to obtain any number of SAR covariance matrices from a single CAR covariance matrix by using Givens rotation matrices on a simulated example. We also discuss sparseness in the original CAR construction, and for the resulting SAR weights matrix. For a real example, we use crime data in 49 neighborhoods from Columbus, Ohio, and show that a geostatistical model optimizes the likelihood much better than typical first-order CAR models. We then use the implied weights from the geostatistical model to estimate CAR model parameters that provides the best overall optimization.
Localization in Mobile Networks via Virtual Convex Hulls

In this paper, we develop a distributed algorithm to localize an arbitrary number of agents moving in a bounded region of interest. We assume that the network contains at least one agent with known location (hereinafter referred to as an anchor), and each agent measures a noisy version of its motion and the distances to the nearby agents. We provide a geometric approach , which allows each agent to (i) continually update the distances to the locations where it has exchanged information with the other nodes in the past; and (ii) measure the distance between a neighbor and any such locations. Based on this approach, we provide a linear update to find the locations of an arbitrary number of mobile agents when they follow some convexity in their deployment and motion. Since the agents are mobile, they may not be able to find nearby nodes (agents and/or anchors) to implement a distributed algorithm. To address this issue, we introduce the notion of a virtual convex hull with the help of the aforementioned geometric approach. In particular, each agent keeps track of a virtual convex hull of other nodes, which may not physically exist, and updates its location with respect to its neighbors in the virtual hull. We show that the corresponding localization algorithm, in the absence of noise, can be abstracted as a linear time-varying system, with nondeterministic system matrices, which asymptotically tracks the true locations of the agents. We provide simulations to verify the analytical results and evaluate the performance of the algorithm in the presence of noise on the motion as well as on the distance measurements.