cssi/SciSciGPT-SciSciNet huggingface dataset:
From cookies to cooks: insights on dietary patterns via analysis of web usage logs

Nutrition is a key factor in people's overall health. Hence, understanding the nature and dynamics of population-wide dietary preferences over time and space can be valuable in public health. To date, studies have leveraged small samples of participants via food intake logs or treatment data. We propose a complementary source of population data on nutrition obtained via Web logs. Our main contribution is a spatiotemporal analysis of population-wide dietary preferences through the lens of logs gathered by a widely distributed Web-browser add-on, using the access volume of recipes that users seek via search as a proxy for actual food consumption. We discover that variation in dietary preferences as expressed via recipe access has two main periodic components, one yearly and the other weekly, and that there exist characteristic regional differences in terms of diet within the United States. In a second study, we identify users who show evidence of having made an acute decision to lose weight. We characterize the shifts in interests that they express in their search queries and focus on changes in their recipe queries in particular. Last, we correlate nutritional time series obtained from recipe queries with time-aligned data on hospital admissions, aimed at understanding how behavioral data captured in Web logs might be harnessed to identify potential relationships between diet and acute health problems. In this preliminary study, we focus on patterns of sodium identified in recipes over time and patterns of admission for congestive heart failure, a chronic illness that can be exacerbated by increases in sodium intake.
Frequency locking in a forced Mathieu–van der Pol–Duffing system

Optically actuated radio frequency microelectromechanical system (MEMS) devices are seen to self-oscillate or vibrate under illumination of sufficient strength (Aubin, Pandey, Zehnder, Rand, Craighead, Zalalutdinov, Parpia (Appl. Phys. Lett. 83, 3281–3283, 2003)). These oscillations can be frequency locked to a periodic forcing, applied through an inertial drive at the forcing frequency, or subharmonically via a parametric drive, hence providing tunability. In a previous work~(Aubin, Zalalutdinov, Alan, Reichenbach, Rand, Zehnder, Parpia, Craighead (IEEE/ASME J. Micromech. Syst. 13, 1018–1026, 2004)), this MEMS device was modeled by a three-dimensional system of coupled thermo-mechanical equations requiring experimental observations and careful finite element simulations to obtain the model parameters. The resulting system of equations is relatively computationally expensive to solve, which could impede its usage in a complex network of such resonators. In this paper, we present a simpler model that shows similar behavior to the MEMS device. We investigate the dynamics of a Mathieu–van der Pol–Duffing equation, which is forced both parametrically and nonparametrically. It is shown that the steady-state response can consist of either 1:1 frequency locking, or 2:1 subharmonic locking, or quasiperiodic motion. The system displays hysteresis when the forcing frequency is slowly varied. We use perturbations to obtain a slow flow, which is then studied using the bifurcation software package AUTO.
Small fan-in is beautiful

The starting points of this paper are two size-optimal solutions: (i) one for implementing arbitrary Boolean functions; and (ii) another one for implementing certain sub-classes of Boolean functions. Because VLSI implementations do not cope well with highly interconnected nets-the area of a chip grows with the cube of the fan-in-this paper analyses the influence of limited fan-in on the size optimality for the two solutions mentioned. First, we extend one result from Horne and Hush (1994) valid for fan-in /spl Delta/=2 to arbitrary fan-in. Second, we prove that size-optimal solutions are obtained for small constant fan-ins for both constructions, while relative minimum size solutions can be obtained for fan-ins strictly lower than linear. These results are in agreement with similar ones proving that for small constant fan-ins (/spl Delta/=6...9) there exist VLSI-optimal (i.e., minimising AT/sup 2/) solutions, while there are similar small constants relating to our capacity of processing information.
CONSTRAINING A MODEL OF TURBULENT CORONAL HEATING FOR AU MICROSCOPII WITH X-RAY, RADIO, AND MILLIMETER OBSERVATIONS

Many low-mass pre-main-sequence stars exhibit strong magnetic activity and coronal X-ray emission. Even after the primordial accretion disk has been cleared out, the star's high-energy radiation continues to affect the formation and evolution of dust, planetesimals, and large planets. Young stars with debris disks are thus ideal environments for studying the earliest stages of non-accretion-driven coronae. In this paper we simulate the corona of AU Mic, a nearby active M dwarf with an edge-on debris disk. We apply a self-consistent model of coronal loop heating that was derived from numerical simulations of solar field-line tangling and magnetohydrodynamic turbulence. We also synthesize the modeled star's X-ray luminosity and thermal radio/millimeter continuum emission. A realistic set of parameter choices for AU Mic produces simulated observations that agree with all existing measurements and upper limits. This coronal model thus represents an alternative explanation for a recently discovered ALMA central emission peak that was suggested to be the result of an inner 'asteroid belt' within 3 AU of the star. However, it is also possible that the central 1.3 mm peak is caused by a combination of active coronal emission and a bright inner source of dusty debris. Additional observations of this source's spatialmore » extent and spectral energy distribution at millimeter and radio wavelengths will better constrain the relative contributions of the proposed mechanisms.« less
Bridging the Front Stage and Back Stage in Service System Design

Service management and design has thus far primarily focused on the interactions between employees and customers. This perspective holds that the quality of the "service experience" is determined by the customer during this final "service encounter" that takes place in the "front stage." This emphasis discounts the contribution of the activities in the "back stage" of the service value chain where materials or information needed by the front stage are processed. However, the vast increase in web-driven consumer self-service applications and other automated services requires new thinking about service design and service quality. It is essential to consider the entire network of services that comprise the back and front stages as complementary parts of a "service system." We need new concepts and methods in service design that recognize how back stage information and processes can improve the front stage experience. This paper envisions a methodology for designing service systems that synthesizes (front-stage-oriented) user-centered design techniques with (back-stage) methods for designing information-intensive applications.
SEMICONDUCTOR THIN FILMS AND THIN FILM DEVICES FOR ELECTROTEXTILES

We discuss the evolution from wearable electronics and conductive textiles to electrotextiles with embedded semiconducting films and semiconductor devices and review different semiconductor technologies competing for applications in electrotextiles. We also report on fabrication, characterization, and properties of nanocrystalline semiconductor and metal films and thin-film device structures chemically deposited on fibers, cloth, and large area flexible substrates at low temperatures (close to room temperature). Our approach is based on a new process of depositing polycrystalline CdSe (1.75 eV), CdS (2.4 eV), PbS (0.4 eV), PbSe (0.24 eV) and CuxS (semiconductor/metal) films on flexible substrates from the water solutions of complex-salt compounds. We have covered areas up to 8 × 10 inches but the process can be scaled up. The film properties are strongly affected by processing. We fabricated a lateral solar cell with alternating Cu2-xS and nickel contact stripes deposited on top of a view foil. These sets of contacts represented "ohmic" and "non-ohmic" contacts, respectively. Then CdS films of approximately 0.5 μm thick were deposited on top. We also fabricated a "sandwich" type photovoltaic cell, where the CdS film was sandwiched between an In2O3 layer deposited on a view foil and a Cu2-xS layer deposited on top. Both structures exhibited transient response under light, with the characteristic response time decreasing with the illumination wavelength. This is consistent with having deeper localized states in the energy gap determining the transients for shorter wavelength radiation. (Slow transients related to trapping effects are typical for polycrystalline CdS materials.) We also report on the photovoltaic effect in CdS/CuS films deposited on trylene threads and on a field effect in these films deposited on a flexible copper wire. CdS films deposited on viewfoils exhibit unique behavior under stress and UV radiation exposure with reproducible resistance changes of several orders of magnitude with bending up to 10 mm curvature. Our results clearly demonstrate the feasibility of using this technology for photovoltaic and microelectronics applications for electrotextiles and wearable electronics applications.
Optical coherence tomography: a novel tool for micron-resolution biomedical diagnostics

Optical coherence tomography (OCT) is a novel method for non-invasive sub-surface imaging of biological tissue micro-structure. OCT is based on low-coherence interferometry. OCT achieves high spatial resolution (/spl sim/15 /spl mu/m in three dimensions) and high sensitivity (<-100 dB) in a fiber-optically integrated system which is suitable for application in minimally invasive diagnostics, including endoscopy. The authors present in vitro cross-sectional OCT images obtained non-invasively in gastrointestinal (GI) tissues to illustrate contrast between histological layers of the GI mucosa and differentiation of the mucosa from submucosa. The authors also present a novel technique, termed color Doppler OCT (CDOCT) which is an extension of OCT for performing spatially localized optical Doppler velocimetry. The authors demonstrate micron-scale resolution tomographic imaging of bi-directional blood flow in sub-surface vessels in living tissue using CDOCT. Both OCT and CDOCT have several potential medical applications.
Mixed Bundling in Two-Sided Markets in the Presence of Installed Base Effects

We analyze mixed bundling in two-sided markets where installed base effects are present and find that the pricing structure deviates from traditional bundling as well as the standard two-sided markets literature—we determine prices on both sides fall with bundling. Mixed bundling acts as a price discrimination tool segmenting the market more efficiently. Consequently, as a by-product of this price discrimination, the two sides are better coordinated, and social welfare is enhanced. We show unambiguously that platform participations increase on both sides of the market. After theoretically evaluating the impact mixed bundling has on prices and welfare, we take the model predictions to data from the portable video game console market. We find empirical support for all theoretical predictions. This paper was accepted by J. Miguel Villas-Boas, marketing.
Instabilities near the onset of spin density wave order in metals

We discuss the low energy theory of two-dimensional metals near the onset of spin density wave order. It is well known that such a metal has a superconducting instability induced by the formation of spin-singlet pairs of electrons, with the pairing amplitude changing sign between regions of the Fermi surface connected by the spin density wave ordering wavevector. Here we review recent arguments that there is an additional instability which is nearly as strong: towards the onset of a modulated bond order which is locally an Ising-nematic order. This new instability is a consequence of an emergent 'pseudospin' symmetry of the low energy theory—the symmetry maps the sign-changing pairing amplitude to the bond order parameter.
Heat trace and functional determinant in one dimension

We study the spectral properties of the Laplace type operator on the circle. We discuss various approximations for the heat trace, the zeta function, and the zeta-regularized determinant. We obtain a differential equation for the heat kernel diagonal and a recursive system for the diagonal heat kernel coefficients, which enables us to find closed approximate formulas for the heat trace and the functional determinant which become exact in the limit of infinite radius. The relation to the generalized Korteweg-de Vries hierarchy is discussed as well.
The relationship between migraine and infant colic: A systematic review and meta-analysis

ContextInfant colic is a common and distressing disorder of early infancy. Its etiology is unknown, making treatment challenging. Several articles have suggested a link to migraine.ObjectiveThe objective of this article was to perform a systematic review and, if appropriate, a meta-analysis of the studies on the relationship between infant colic and migraine.Data sourcesStudies were identified by searching PubMed and ScienceDirect and by hand-searching references and conference proceedings.Study selectionFor the primary analysis, studies specifically designed to measure the association between colic and migraine were included. For the secondary analysis, studies that collected data on colic and migraine but were designed for another primary research question were also included.Data extractionData were abstracted from the original studies, through communication with study authors, or both. Two authors independently abstracted data.Main outcomes and measuresThe main outcome measure was the association betwe...
Synthesis of tricyclo[6.2.2.01,6]Dodeca-6,9-dienes. An approach to clerodane diterpenes.

Abstract The preparation of tricyclo[6.2.2.0 1,6 ]dodeca-6,9-dienes via Lewis acid catalyzed intramolecular cycloadditions is reported. The cycloadditions proceed through boat transition states.
A randomized, controlled trial of the effect of rilpivirine versus efavirenz on cardiovascular risk in healthy volunteers

OBJECTIVES The HIV NNRTI rilpivirine is being evaluated as a possible agent for HIV pre-exposure prophylaxis. We have recently shown that the NNRTI efavirenz may impair endothelial function assessed as flow-mediated dilation (FMD), but whether this impairment is also found with rilpivirine is unknown. We sought to compare cardiovascular risk profiles between efavirenz and rilpivirine in healthy volunteers. METHODS We performed a prospective, randomized, open-label trial in 40 HIV-uninfected healthy volunteers who were randomized 1: 1 to either efavirenz or rilpivirine. Vascular indices, metabolic parameters, inflammatory biomarkers and oxidative stress were measured before and after 4 weeks of treatment. This study is registered at ClinicalTrials.gov (NCT01585038). RESULTS There were no significant differences in 4 week mean (SD) changes in FMD between efavirenz and rilpivirine [0.089 (3.65)% versus 0.63 (2.42)%; P = 0.77]. There were also no significant differences in 4 week changes in high-sensitivity C-reactive protein, IL-6, soluble vascular cell adhesion molecule-1, HDL-cholesterol, triglycerides or homeostasis model assessment-insulin resistance. However, efavirenz led to significant increases in total cholesterol [19.39 (23.9) versus -5.78 (16.5) mg/dL; P < 0.001], LDL-cholesterol [13.29 (19.5) versus -2.24 (13.4) mg/dL; P = 0.009] and F2-isoprostanes [92.7 (178.6) versus -101.4 (215.7) pg/mL; P = 0.019] compared with rilpivirine. Two participants from each study group discontinued prematurely for adverse events. CONCLUSIONS There were no significant differences in the changes in endothelial function over 1 month between the efavirenz and rilpivirine groups, although efavirenz had worse lipid changes compared with rilpivirine. Longer-term studies are required for confirmation.
Model Systems for Studying Polyvalent Carbohydrate Binding Interactions

This chapter describes several classes of model systems that have been used for studies of polyvalent binding interactions between carbohydrates and proteins. This review is divided into two parts. The first section provides a mechanistic analysis of polyvalent recognition. The second section utilizes this mechanistic framework to describe and analyze several major classes of model systems. The description of each model system is accompanied by a summary of recent experimental results from the literature. The chapter concludes with a comparison of the model systems and an introduction to several novel model systems that promise to broaden the scope of future studies in polyvalent carbohydrate-protein interactions.
Assessing the Feasibility of Cosmic-Ray Acceleration by Magnetic Turbulence at the Galactic Center

The presence of relativistic particles at the center of our galaxy is evidenced by the diffuse TeV emission detected from the inner ∼2 ◦ of the Galaxy. Although it is not yet entirely clear whether the origin of the TeV photons is due to hadronic or leptonic interactions, the tight correlation of the intensity distribution with the distribution of molecular gas along the Galactic ridge strongly points to a pionic-decay process involving relativistic protons. In earlier work, we concluded that point-source candidates, such as the supermassive black hole Sagittarius A* (identified with the HESS source J1745-290), or the pulsar wind nebulae dispersed along the Galactic plane, could not account for the observed diffuse TeV emission from this region. Motivated by this result, we consider here the feasibility that the cosmic rays populating the Galactic Center (GC) region are accelerated in situ by magnetic turbulence. Our results indicate that even in a highly conductive environment, this mechanism is efficient enough to energize protonswithin the intercloud medium to the & TeV energies required to produce the HESS emission. Subject headings: Cosmic Rays – diffusion – ISM – molecular clouds
New layered uranium phosphate fluorides: syntheses, structures, characterizations, and ion-exchange properties of A(UO2)F(HPO4).xH2O (A = Cs+, Rb+, K+; x = 0-1).

Single crystals of three new layered uranium phosphate fluorides, A(UO2)F(HPO4)·xH2O (A = Cs+, Rb+, and K+; x = 0−1) have been synthesized by hydrothermal reactions using UO3, H3PO4, HF, and corresponding alkali metal halides as reagents. Although all three new materials have layered structures, each of them contains different structural motifs within the layer. While Cs(UO2)F(HPO4)·0.5H2O and Rb(UO2)F(HPO4) reveal noncentrosymmetric crystal structures, K(UO2)F(HPO4)·H2O crystallizes in a centrosymmetric space group. In addition, the ion-exchanged phases for all three materials are highly crystalline. Crystal data: Cs(UO2)F(HPO4)·0.5H2O, orthorhombic, space group Pca21 (No. 29), with a = 25.656(5) A, b = 6.0394(12) A, c = 9.2072(18) A, and Z = 4; Rb(UO2)F(HPO4), orthorhombic, space group Cmc21 (No. 36), with a = 17.719(4) A, b = 6.8771(14) A, c = 12.139(2) A, and Z = 8; K(UO2)F(HPO4)·H2O, monoclinic, P21/n (No. 14), with a = 6.7885(14) A, b = 8.7024(17) A, c = 12.020(2) A, β = 94.09(3)°, and Z = 4.
A Neowicksellian in a New Classical World: The Methodology of Michael Woodford's Interest and Prices

Michael Woodford's Interest and Prices: Foundations of a Theory of Monetary Policy (2003) is an important book. Woodford's title is, of course, a conscious revival of Wicksell's own famous work and it points to an effort to recast the analysis of monetary policy as centered on interest rates. I believe that Woodford's theoretical orientation is essentially correct. In repairing to Wicksell, he places the monetary aggregates into a more reasonable perspective, correcting the distortions of the monetarist and Keynesian diversions with respect to money. My money is, so to speak, where my mouth is: My own textbook-in-progress is also based around an IS/interest-rate rule/AS model, in which financial markets cleared by price rather than the LM curve are emphasized. Such an approach, as Woodford notes, has become standard in central banks, but has not yet captured either core undergraduate or graduate textbooks and instruction. My task here, however, was not to praise Woodford's economics nor to trace or evaluate its Wicksellian routes, but to consider Interest and Prices from a methodological point of view.
Does the size distribution of mineral dust aerosols depend on the wind speed at emission

Abstract. The size distribution of mineral dust aerosols partially determines their interactions with clouds, radiation, ecosystems, and other components of the Earth system. Several theoretical models predict that the dust size distribution depends on the wind speed at emission, with larger wind speeds predicted to produce smaller aerosols. The present study investigates this prediction using a compilation of published measurements of the size-resolved vertical dust flux emitted by eroding soils. Surprisingly, these measurements indicate that the size distribution of naturally emitted dust aerosols is independent of the wind speed. The recently formulated brittle fragmentation theory of dust emission is consistent with this finding, whereas other theoretical models are not. The independence of the emitted dust size distribution with wind speed simplifies both the interpretation of geological records of dust deposition and the parameterization of dust emission in atmospheric circulation models.
A note on convergence of low energy critical points of nonlinear elasticity functionals, for thin shells of arbitrary geometry

We prove that the critical points of the 3d nonlinear elasticity functional on shells of small thickness h and around the mid-surface S of arbitrary geometry, converge as h → 0t o the critical points of the von Karman functional on S, recently proposed in (Lewicka et al., Ann. Scuola Norm. Sup. Pisa Cl. Sci. (to appear)). This result extends the statement in (Muller and Pakzad, Comm. Part. Differ. Equ. 33 (2008) 1018-1032), derived for the case of plates when S ⊂ R 2 . The convergence holds provided the elastic energies of the 3d deformations scale like h 4 and the external body forces scale like h 3 .
Prediction, time variance, and classification of hydraulic response to recharge in two karst aquifers

Many karst aquifers are rapidly filled and depleted and therefore are likely to be susceptible to changes in short- term climate variability. Here we explore methods that could be applied to model site-specific hydraulic responses, with the intent of simulating these responses to different climate scenarios from high-resolution climate models. We compare hydraulic responses (spring flow, groundwater level, stream base flow, and cave drip) at several sites in two karst aquifers: the Edwards aquifer (Texas, USA) and the Madison aquifer (South Dakota, USA). A lumped-parameter model simulates nonlinear soil moisture changes for estimation of recharge, and a time-variant convolution model simulates the aquifer response to this recharge. Model fit to data is 2.4 % better for calibration periods than for validation periods according to the Nash-Sutcliffe coefficient of efficiency, which ranges from 0.53 to 0.94 for validation periods. We use metrics that describe the shapes of the impulse-response functions (IRFs) obtained from convolution modeling to make comparisons in the distribution of response times among sites and between aquifers. Time-variant IRFs were applied to 62 % of the sites. Principal component analysis (PCA) of metrics describing the shapes of the IRFs indicates three principal components that together account for 84 % of the variability in IRF shape: the first is related to IRF skewness and temporal spread and accounts for 51 % of the variability; the second and third largely are related to time-variant properties and together ac- count for 33 % of the variability. Sites with IRFs that domi- nantly comprise exponential curves are separated geograph- ically from those dominantly comprising lognormal curves in both aquifers as a result of spatial heterogeneity. The use of multiple IRF metrics in PCA is a novel method to charac- terize, compare, and classify the way in which different sites and aquifers respond to recharge. As convolution models are developed for additional aquifers, they could contribute to an IRF database and a general classification system for karst aquifers.
Photometric redshifts with surface brightness priors

We use galaxy surface brightness as prior information to improve photometric redshift (photo-z) estimation. We apply our template-based photo-z method to imaging data from the ground-based VVDS survey and the space-based GOODS field from HST, and use spectroscopic redshifts to test our photometric redshifts for different galaxy types and redshifts. We find that the surface brightness prior eliminates a large fraction of outliers by lifting the degeneracy between the Lyman and 4000-A breaks. Bias and scatter are improved by about a factor of 2 with the prior in each redshift bin in the range 0.4 < z < 1.3, for both the ground and space data. Ongoing and planned surveys from the ground and space will benefit, provided that care is taken in measurements of galaxy sizes and in the application of the prior. We discuss the image quality and signal-to-noise ratio requirements that enable the surface brightness prior to be successfully applied.
On the Dimensions of Certain LDPC Codes Based on $q$ -Regular Bipartite Graphs

An explicit construction of a family of binary low-density parity check (LDPC) codes called LU(3,q), where q is a power of a prime, was recently given. A conjecture was made for the dimensions of these codes when q is odd. The conjecture is proved in this note. The proof involves the geometry of a four-dimensional (4-D) symplectic vector space and the action of the symplectic group and its subgroups
Monotone Equilibrium in Multi-Unit Auctions

In two-sided multi-unit auctions having a variety of payment rules, including uniform-price and discriminatory auctions, a monotone pure strategy equilibrium (MPSE) exists when bidders are risk-neutral with independent multi-dimensional types and interdependent values. In fact, all mixed strategy equilibria are ex post allocation- and interim expected payment-equivalent to MPSE. Thus, for standard expected surplus / revenue analysis, there is no loss restricting attention to monotone strategies.
Utilizing protein structure to identify non-random somatic mutations

Human cancer is caused by the accumulation of somatic mutations in tumor suppressors and oncogenes within the genome. In the case of oncogenes, recent theory suggests that there are only a few key “driver” mutations responsible for tumorigenesis. As there have been significant pharmacological successes in developing drugs that treat cancers that carry these driver mutations, several methods that rely on mutational clustering have been developed to identify them. However, these methods consider proteins as a single strand without taking their spatial structures into account. We propose an extension to current methodology that incorporates protein tertiary structure in order to increase our power when identifying mutation clustering. We have developed iPAC (identification of Protein Amino acid Clustering), an algorithm that identifies non-random somatic mutations in proteins while taking into account the three dimensional protein structure. By using the tertiary information, we are able to detect both novel clusters in proteins that are known to exhibit mutation clustering as well as identify clusters in proteins without evidence of clustering based on existing methods. For example, by combining the data in the Protein Data Bank (PDB) and the Catalogue of Somatic Mutations in Cancer, our algorithm identifies new mutational clusters in well known cancer proteins such as KRAS and PI3KC α. Further, by utilizing the tertiary structure, our algorithm also identifies clusters in EGFR, EIF2AK2, and other proteins that are not identified by current methodology. The R package is available at: http://www.bioconductor.org/packages/2.12/bioc/html/iPAC.html . Our algorithm extends the current methodology to identify oncogenic activating driver mutations by utilizing tertiary protein structure when identifying nonrandom somatic residue mutation clusters.
FAST PIN-DIODE BEAM LOSS MONITORS AT TEVATRON

Abstract The article is devoted to results of fine temporal structure of particle losses in the Tevatron ring obtained with use of fast beam loss monitors (BLM) based on PIN-diodes. In the Tevatron fixed target operation regime, these monitors were able to distinguish proton losses from bunches spaced by only 19 ns. Besides measurements of main characteristics of the BLMs, we studied the proton losses over 10 decades of time intervals – from a dozen of minutes to a dozen of nanoseconds. Due to huge dynamical range and fast response the PIN-BLMs perfectly fit the task of the beam loss detection at the Tevatron collider upgrade with as small as 132 ns bunch spacing.
Switching-ripple-based current sharing for paralleled power converters

This paper presents the implementation and experimental evaluation of a new current-sharing technique for paralleled power converters. This technique uses information naturally encoded in the switching ripple to achieve current sharing and requires no intercell connections for communicating this information. Practical implementation of the approach is addressed and an experimental evaluation, based on a three-cell prototype system, is also presented. It is shown that accurate and stable load sharing is obtained over a wide load range. Finally, an alternate implementation of this current-sharing technique is described and evaluated.
Opportunities and challenges with autonomous micro aerial vehicles

We survey the recent work on micro unmanned aerial vehicles (UAVs), a fast-growing field in robotics, outlining the opportunities for research and applications, along with the scientific and technological challenges. Micro-UAVs can operate in three-dimensional environments, explore and map multi-story buildings, manipulate and transport objects, and even perform such tasks as assembly. While fixed-base industrial robots were the main focus in the first two decades of robotics, and mobile robots enabled most of the significant advances during the next two decades, it is likely that UAVs, and particularly micro-UAVs, will provide a major impetus for the next phase of education, research, and development.
Modeling of Image Formation in Multi-Spacecraft Interferometric Imaging Systems

In this paper, we develop a detailed model of the process of image formation in Multi- Spacecraft Interferometric Imaging Systems (MSIIS). We show that the Modulation Trans- fer Function of, and the noise corrupting, the synthesized optical instrument are dependent on the trajectories of the constituent spacecraft and obtain these explicit functional rela- tionships. We show that "good" imaging using MSIIS is equivalent to painting a "large disk" with smaller "paintbrushes" while maintaining a minimum thickness of paint, given that the goal of imaging is the correct classification of the formed images. This implies that the trajectories of the constituent spacecraft have to be "dense" enough in a given region, while making sure that they are "slow" enough. This is illustrated through an example. In this paper, we model the process of image formation in an MSIIS. We also model the noise inherent in such systems. We show that both the Modulation Transfer function (MTF) of the synthesized optical instrument and the noise corrupting the image formed by such an optical instrument are dependent on the trajectories of the constituent spacecraft. Further, if we formulate the goal of imaging as the correct classifi- cation of the formed images, we show that satisfactory imaging by an MSIIS is analogous to the "painting" of a large resolution disk with smaller "coverage" disks or "paintbrushes" while maintaining a minimum thickness of paint. The problem of design of MSIIS is related to the fields of synthetic aperture optics and formation flying. The relationship of our work to these topics is discussed next. The topic of long baseline interferometry falls under the category of synthetic aperture optics, 4 that was first developed in the context of synthetic aperture radars (SAR). 5 The method consists of emulating a large optical instrument by a number of smaller ones and combining their contributions in a proper way to obtain an image that has resolution comparable to that of the large optical instrument. For a discussion of the various metrics used in the optimization of these systems, please refer to 6 and the references therein. All the abovementioned designs optimize the locations of the constituent telescopes such that some metric of image quality is maximized. Thus, these correspond to static optimization problems. However, for an MSIIS, due to the high resolution requirements, the "design variables" are the trajectories of the constituent spacecraft. In fact, we show the explicit dependence of the MTF on the trajectories of the constituent spacecraft. Further, we show that the noise corrupting the image in an MSIIS is a function of the spacecraft trajectories and the rate of arrival of photons on the observation plane. Given that the goal of imaging is the correct classification of images, the design of an MSIIS reduces
Quaternary Carbon Stereogenic Centers through Copper‐Catalyzed Enantioselective Allylic Substitutions with Readily Accessible Aryl‐ or Heteroaryllithium Reagents and Aluminum Chlorides

Catalytic enantioselective allylic substitution (EAS) reactions[i] are among the most versatile classes of transformations in organic chemistry: such processes convert readily available achiral substrates to enantiomerically enriched products bearing a stereogenic center adjacent to a readily functionalizable alkene. We have devised chiral amino acid-based[ii] and bidentate N-heterocyclic carbene (NHC) Cu complexes[iii] that promote EAS processes with dialkylzinc reagents and generate quaternary carbon stereogenic centers[iv] with high site- and enantioselectivity. Catalytic enantioselective Cu-free additions of alkylmagnesium halides to allylic halides,[v] as well as dialkylzinc and trialkylaluminum reagents[vi] to phosphates, have also been developed. Nonetheless, significant and compelling problems remain unaddressed. Catalytic EAS transformations involving aryl nucleophiles and which deliver quaternary carbon centers are notoriously scarce, and protocols that involve hetero-arylmetals do not exist (including those that furnish tertiary C–C bonds). The only reported cases of aryl additions by catalytic EAS that generate quaternary carbons correspond to Si-substituted alkenes and involve diarylzinc reagents,[vii] which are relatively difficult to prepare in high purity and offer only one of the two aryl units. Such considerations underline a shortcoming in the state-of-the-art: the absence of EAS methods that deliver quaternary carbon stereogenic centers through reactions with mono-arylmetal reagents, in particular those that are easily accessible and atom-economical.[i]
Estimating Latent Processes on a Network From Indirect Measurements

In a communication network, point-to-point traffic volumes over time are critical for designing protocols that route information efficiently and for maintaining security, whether at the scale of an Internet service provider or within a corporation. While technically feasible, the direct measurement of point-to-point traffic imposes a heavy burden on network performance and is typically not implemented. Instead, indirect aggregate traffic volumes are routinely collected. We consider the problem of estimating point-to-point traffic volumes, , from aggregate traffic volumes, , given information about the network routing protocol encoded in a matrix A. This estimation task can be reformulated as finding the solutions to a sequence of ill-posed linear inverse problems, , since the number of origin-destination routes of interest is higher than the number of aggregate measurements available. Here, we introduce a novel multilevel state-space model (SSM) of aggregate traffic volumes with realistic features. We imp...
Consistent particle-based algorithm with a non-ideal equation of state

A thermodynamically consistent particle-based model for fluid dynamics with continuous velocities and a non-ideal equation of state is presented. Excluded-volume interactions are modeled by means of biased stochastic multiparticle collisions which depend on the local velocities and densities. Momentum and energy are conserved locally. The equation of state is derived and compared to independent measurements of the pressure. Results for the kinematic shear viscosity and self-diffusion constants are presented. For fixed density, a caging and order/disorder transition is observed with increasing collision frequency.
An Eddy Diffusivity–Mass Flux Approach to the Vertical Transport of Turbulent Kinetic Energy in Convective Boundary Layers

AbstractIn this study a new approach to the vertical transport of the turbulent kinetic energy (TKE) is proposed. The principal idea behind the new parameterization is that organized updrafts or convective plumes play an important role in transferring TKE vertically within convectively driven boundary layers. The parameterization is derived by applying an updraft environment decomposition to the vertical velocity triple correlation term in the TKE prognostic equation. The additional mass flux (MF) term that results from this decomposition closely resembles the features of the TKE transport diagnosed from the large-eddy simulation (LES) and accounts for 97% of the LES-diagnosed transport when the updraft fraction is set to 0.13. Another advantage of the MF term is that it is a function of the updraft vertical velocity and can be readily calculated using already existing parameterization. The new MF approach, combined with several eddy diffusivity (ED) formulations, is implemented into a simplified 1D TKE p...
Receptor inhibition by immunoglobulins: specific inhibition by autistic children, their relatives, and control subjects.

Forty-two parents of children with autistic disorder, 15 children with autistic disorder, 17 siblings of children with autistic disorder, and 12 unrelated normal adult controls were studied to determine if immunoglobulins isolated from their plasma would inhibit binding of the 5HT 1A agonist, [ 3 H]-8-hydroxy-N,N-dipropyl-2-aminotetralin (DPAT) to 5HT 1A receptors in human hippocampal membranes. There were no significant differences among the means of percentage inhibition of DPAT binding of parents, children with autistic disorder, siblings, or unrelated controls. In addition, there were no differences in the proportion of subjects with >15% DPAT inhibition among autistic children, their parents, their siblings, or unrelated controls. Immunoglobulin inhibition was not specific for the 5HT 1A receptor binding site, since immunoglobulins inhibited binding to 5HT 2 , D 1 , D 2 , and α2-adrenergic binding sites. The immunoglobulins isolated from normal controls inhibited [ 3 H]-rauwolscine binding at α2-adrenergic sites less than immunoglobulins of children with autistic disorder and their parents and siblings. This study did not support the hypothesis that autoantibodies to 5HT 1A or 5HT 2 receptors are characteristic of autistic disorder.
Corporate Control Through Board Dismissals and Takeovers

This paper examines some policy issues related to the interaction between internal and external corporate control mechanisms—board dismissals and takeovers—by focusing on the information aggregation and other effects related to this interaction. We model the functioning of corporate control mechanisms as an example of a multilayered principal-agent relationship in which shareholders delegate the task of monitoring management quality to the board and rely on the external takeover market to provide additional disciplining of the manager as well as of the board. This gives rise to two () effects: 1 a substitution effect, whereby the takeover market partially substitutes for board dismissal of the manager, leading to greater lenience toward the manager by a board acting in the shareholders' best interest, and () 2 a kick-in-the-pants effect, whereby the board is stricter with the manager because it may be dismissed by a successful acquirer who views it as lax. The interaction of these two effects leads to various implications about the behavior of boards and potential acquirers. In particular, a well-functioning () internal control mechanism the board does not obviate the need for external () control takeovers . Moreover, somewhat counterintuitively, there may be a greater incidence of takeovers when the internal control mechanism is working well than when it is not.
New and Old Concepts in Thermoelectric Materials

Herein we cover the key concepts in the field of thermoelectric materials research, present the current understanding, and show the latest developments. Current research is aimed at increasing the thermoelectric figure of merit (ZT) by maximizing the power factor and/or minimizing the thermal conductivity. Attempts at maximizing the power factor include the development of new materials, optimization of existing materials by doping, and the exploration of nanoscale materials. The minimization of the thermal conductivity can come through solid-solution alloying, use of materials with intrinsically low thermal conductivity, and nanostructuring. Herein we describe the most promising bulk materials with emphasis on results from the last decade. Single-phase bulk materials are discussed in terms of chemistry, crystal structure, physical properties, and optimization of thermoelectric performance. The new opportunities for enhanced performance bulk nanostructured composite materials are examined and a look into the not so distant future is attempted.
Assessing the Effectiveness of Saving Incentives

Concluding that IRAs and 401(k)s do increase saving, this text provides a fresh cost-benefit approach for analyzing the "success" of savings incentives. It compares the new savings to the government tax revenue lost through contributions to IRAs and 401(k)s.
Scanning Tunneling Microscope-Induced Luminescence Studies of Defects in GaN Layers and Heterostructures

We present the scanning tunneling microscope-induced luminescence (STL) imaging of defects in optoelectronic materials. Resolution is first discussed using cross-sectional images of InGaAs/GaAs quantum dots. Proof of concept is then provided through the nanometer-scale imaging of GaN layers and quantum wells. The expected λ=356±25 nm range dominates the low temperature STL of GaN. Mapping of luminescence shows circular non-emitting areas around threading dislocations. Extent of dark areas suggests a hole diffusion length of Ld=30-55 nm, in agreement with reported values. The expected λ=450±35 nm range dominates the STL from a buried InGaN/GaN multiple quantum well. Imaging reveals 30-100 nm wide smooth fluctuations of luminescence.
Shielding requirements on-site loading and acceptance testing of the leksell gamma knife☆

On August 14, 1987, the first stereotactic radiosurgical procedure using the gamma knife was performed in North America. Located in a self-contained radiosurgical suite in the basement of Presbyterian-University Hospital in Pittsburgh, Pennsylvania. This device uses 201 highly focused beams 60Co for the single-treatment closed-skull irradiation of brain lesions localized by stereotactic techniques (radiosurgery). One hundred and fifty-two patients with intracranial arteriovenous malformations or brain tumors were treated in the first year of operation. The Presbyterian University Hospital of Pittsburgh gamma knife is the first such unit in which the 60Co sources were loaded on-site. This effort required us to solve some difficult and unusual problems encountered during site preparation, delivery, and loading of the unit in a busy hospital setting. The solutions developed enabled installation and use of the gamma knife with minimal disruption of hospital activities while maintaining acceptable levels of exposure to radiation. Environmental surveys performed during the loading of the 201 radioactive sources (total, 219 TBq) confirmed that on-site loading is possible and practical. Our experience in the design, construction, and implementation of the first North American gamma knife supports the practicality and safety of on-site loading and may be of value in the planning and development of future gamma knife installations.
Effect of favorable pressure gradients on turbulent boundary layers

Large favorable pressure gradients can cause the drag of a turbulent boundary layer on a solid surface to decrease; if large enough, such gradients can cause a return to laminar flow. Scaling relations and a computational model for the viscous wall layer, recently developed in this laboratory are used to interpret this phenomenon.
China's Changing Trade Elasticities

China’s sectoral trade composition, product quality mix, and the import content of processing exports have all changed substantially during the past decade. This has rendered trade elasticities estimated using aggregate data highly unstable, with more recent data pointing to significantly higher demand and price elasticities. Sectoral differences in these parameters are also very wide. All this suggests greater caution should be exercised when using historical data to simulate the response of China’s economy to external shocks and exchange rate changes. Analyses based on models with estimated coefficients largely representative of China in the 1980s and 1990s are likely to turn out to be wrong, perhaps even dramatically.
Numerical Simulation of Transport in Optical Fiber Drawing with Core–Cladding Structure

Optical fibers are typically drawn from silica preforms, which usually consist of two concentric cylinders called the core and the cladding, heated in a high-temperature furnace. For optical communication purposes, the core always has a higher refractive index than the cladding to obtain total internal reflection. In order to investigate the effect of this core-cladding structure on optical fiber drawing, a numerical model has been developed in this work. Axisymmetric flows of a double-layer glass and aiding purge gas in a concentric cylindrical furnace are considered. The thermal and momentum transport in both glass layers and gas are coupled at the interface boundaries. The neck-down profile is generated using an iterative numerical scheme. The zonal method is applied to model the radiation transfer in the glass preform. The gas is taken as nonparticipating. Coordinate transformations are used to convert the resulting complex domains into cylindrical regions. The stream function, vorticity, and energy equations for the core, the cladding, and the purge gas are solved by finite difference methods, using a false transient approach coupled with the alternating direction implicit method. A second-order differencing scheme is used for discretization. The numerical results are validated by comparing with results available in the literature. The effects of changes in the refractive index and absorption coefficient due to doping on fiber drawing are investigated. This problem has received very little attention in the literature, particularly with respect to modeling, and this paper presents an initial study of the underlying transport.