cssi/SciSciGPT-SciSciNet huggingface dataset:
Spectrally-truncated kernel ridge regression and its free lunch

Kernel ridge regression (KRR) is a well-known and popular nonparametric regression approach with many desirable properties, including minimax rate-optimality in estimating functions that belong to common reproducing kernel Hilbert spaces (RKHS). The approach, however, is computationally intensive for large data sets, due to the need to operate on a dense n×n kernel matrix, where n is the sample size. Recently, various approximation schemes for solving KRR have been considered, and some analyzed. Some approaches such as Nystrom approximation and sketching have been shown to preserve the rate optimality of KRR. In this paper, we consider the simplest approximation, namely, spectrally truncating the kernel matrix to its largest r<n eigenvalues. We derive an exact expression for the maximum risk of this truncated KRR, over the unit ball of the RKHS. This result can be used to study the exact trade-off between the level of spectral truncation and the regularization parameter. We show that, as long as the RKHS is infinite-dimensional, there is a threshold on r, above which, the spectrally-truncated KRR surprisingly outperforms the full KRR in terms of the minimax risk, where the minimum is taken over the regularization parameter. This strengthens the existing results on approximation schemes, by showing that not only one does not lose in terms of the rates, truncation can in fact improve the performance, for all finite samples (above the threshold). Moreover, we show that the implicit regularization achieved by spectral truncation is not a substitute for Hilbert norm regularization. Both are needed to achieve the best performance.
The Markoff equation over polynomial rings

When $$A=3$$ , the positive integral solutions of the so-called Markoff equation $$\begin{aligned} M_A:x^2 + y^2 + z^2 = Axyz \end{aligned}$$ can be generated from the single solution (1, 1, 1) by the action of certain automorphisms of the hypersurface. Since Markoff’s proof of this fact, several authors have showed that the structure of $$M_A(R)$$ , when R is $${\mathbb Z}[i]$$ or certain orders in number fields, behave in a similar fashion. Moreover, for $$R={\mathbb Z}$$ and $$R={\mathbb Z}[i]$$ , Zagier and Silverman, respectively, have found asymptotic formulae for the number of integral points of bounded height. In this paper, we investigate these problems when R is a polynomial ring over a field K of odd characteristic. We characterize the set $$M_A(K[t])$$ in a similar fashion as Markoff and previous authors. We also give an asymptotic formula that is similar to Zagier’s and Silverman’s formula.
Estimating Treatment Effects with Observed Confounders and Mediators

Given a causal graph, the do-calculus can express treatment effects as functionals of the observational joint distribution that can be estimated empirically. Sometimes the do-calculus identifies multiple valid formulae, prompting us to compare the statistical properties of the corresponding estimators. For example, the backdoor formula applies when all confounders are observed and the frontdoor formula applies when an observed mediator transmits the causal effect. In this paper, we investigate the over-identified scenario where both confounders and mediators are observed, rendering both estimators valid. Addressing the linear Gaussian causal model, we demonstrate that either estimator can dominate the other by an unbounded constant factor. Next, we derive an optimal estimator, which leverages all observed variables, and bound its finite-sample variance. We show that it strictly outperforms the backdoor and frontdoor estimators and that this improvement can be unbounded. We also present a procedure for combining two datasets, one with observed confounders and another with observed mediators. Finally, we evaluate our methods on both simulated data and the IHDP and JTPA datasets.
Towards milli-Hertz laser frequency noise on a chip

A fundamental frequency noise of 9 mHz•Hz/Hz is demonstrated in an on-chip Brillouin laser. The noise measurement uses the frequency discrimination method enhanced by cross-correlator. The results set new performance targets for chip-based laser platforms.
Sparse nonlinear models of chaotic electroconvection.

Convection is a fundamental fluid transport phenomenon, where the large-scale motion of a fluid is driven, for example, by a thermal gradient or an electric potential. Modelling convection has give...
Boundary Layer Transition over Blunt Hypersonic Vehicles Including Effects of Ablation-Induced Out-Gassing

Computations are performed to study the boundary layer instability mechanisms pertaining to hypersonic flow over blunt capsules. For capsules with ablative heat shields, transition may be influenced both by out-gassing associated with surface pyrolysis and the resulting modification of surface geometry including the formation of micro-roughness. To isolate the effects of out-gassing, this paper examines the stability of canonical boundary layer flows over a smooth surface in the presence of gas injection into the boundary layer, with an emphasis on the case of massive injection used in previous ground facility experiments. For a slender cone, the effects of out-gassing on the predominantly second mode instability are found to be stabilizing. In contrast, for a blunt capsule flow dominated by first mode instability, out-gassing is shown to be destabilizing. Analogous destabilizing effects of out-gassing are also noted for both stationary and traveling modes of crossflow instability over a blunt sphere-cone configuration at angle of attack.
Effect of film processing on cryogenic properties of poly(ethylene terephthalate)

Abstract The effects of stretch temperature, heat-set temperature, and heat-set time on the cryogenic mechanical properties of PET film were studied by using a two-level factorial experiment. Squares of amorphous PET sheet were given a simultaneous biaxial 3x stretch in a laboratory film stretcher at either 85 or 95°C. The levels of heat-set temperature and time investigated were 190 and 210°C and 15 and 120 sec, respectively. Crystallinities of the films were determined by the density-gradient technique. Tensile properties were measured in liquid nitrogen (77°K) and liquid hydrogen (20°K). Biaxial burst properties were obtained in liquid nitrogen. It was found that processing variables significantly affect the stress-strain properties of PET film at cryogenic temperatures. These results and encouraging values of flexibility offer leads for possible use of specially processed PET films for cryogenic space applications.
hep_tables: Heterogeneous Array Programming for HEP

Array operations are one of the most concise ways of expressing common filtering and simple aggregation operations that are the hallmark of a particle physics analysis: selection, filtering, basic vector operations, and filling histograms. The High Luminosity run of the Large Hadron Collider (HL-LHC), scheduled to start in 2026, will require physicists to regularly skim datasets that are over a PB in size, and repeatedly run over datasets that are 100’s of TB’s – too big to fit in memory. Declarative programming techniques are a way of separating the intent of the physicist from the mechanics of finding the data and using distributed computing to process and make histograms. This paper describes a library that implements a declarative distributed framework based on array programming. This prototype library provides a framework for different sub-systems to cooperate in producing plots via plug-in’s. This prototype has a ServiceX data-delivery sub-system and an awkward array sub-system cooperating to generate requested data or plots. The ServiceX system runs against ATLAS xAOD data and flat ROOT TTree’s and awkward on the columnar data produced by ServiceX.
Principles of spintronic THz emitters

Significant progress has been made in answering fundamental questions about how and, more importantly, on what time scales interactions between electrons, spins, and phonons occur in solid state materials. These complex interactions are leading to the first real applications of terahertz (THz) spintronics: THz emitters that can compete with traditional THz sources and provide additional functionalities enabled by the spin degree of freedom. This Tutorial article is intended to provide the background necessary to understand, use, and improve THz spintronic emitters. A particular focus is the introduction of the physical effects that underlie the operation of spintronic THz emitters. These effects were, for the most part, first discovered through traditional spin-transport and spintronic studies. We, therefore, begin with a review of the historical background and current theoretical understanding of ultrafast spin physics that has been developed over the past 25 years. We then discuss standard experimental techniques for the characterization of spintronic THz emitters and—more broadly—ultrafast magnetic phenomena. We next present the principles and methods of the synthesis and fabrication of various types of spintronic THz emitters. Finally, we review recent developments in this exciting field including the integration of novel material platforms such as topological insulators as well as antiferromagnets and materials with unconventional spin textures.
Edge removal in undirected networks

The edge-removal problem asks whether the removal of a $\lambda$ -capacity edge from a given network can decrease the communication rate between source-terminal pairs by more than $\lambda$ . We prove that for undirected networks, removing a $\lambda$ capacity edge decreases the rate by $O(\lambda$ . Through previously known reductive arguments, here newly applied to undirected networks, our result implies that the zero-error capacity region of an undirected network equals its vanishing-error capacity region. Whether it is possible to prove similar results for directed networks remains an open question.
Autonomous Cave Surveying With an Aerial Robot

This article presents a method for cave surveying in total darkness using an autonomous aerial vehicle equipped with a depth camera for mapping, downward-facing camera for state estimation, and forward and downward lights. Traditional methods of cave surveying are labor-intensive and dangerous due to the risk of injury when operating in darkness, and the potential structural instability of the subterranean environment. Although these dangers can be mitigated by deploying robots to map dangerous passages and voids, real-time feedback is often needed to operate robots safely and efficiently. Few state-of-the-art, high-resolution perceptual modeling techniques attempt to reduce their high bandwidth requirements to work well with low bandwidth communication channels. To bridge this gap in the state-of- the-art, this work compactly represents sensor observations as Gaussian mixture models and maintains a local occupancy grid map for a motion planner that greedily maximizes an information-theoretic objective function. The approach accommodates both limited field of view (FoV) depth cameras and larger FoV LiDAR sensors and is extensively evaluated in long duration simulations on an embedded PC. An aerial system is leveraged to demonstrate the repeatability of the approach in a flight arena as well as the effects of communication dropouts. Finally, the system is deployed in Laurel Caverns, a commercially owned and operated cave in southwestern Pennsylvania, USA, and a wild cave in West Virginia, USA. Videos of the simulation and hardware results are available at https://youtu.be/iwi3p7IENjE and https://youtu.be/H8MdtJ5VhyU.
Tbx5 drives Aldh1a2 expression to regulate a RA-Hedgehog-Wnt gene regulatory network coordinating cardiopulmonary development

The gene regulatory networks that coordinate the development of the cardiac and pulmonary systems are essential for terrestrial life but poorly understood. The T-box transcription factor Tbx5 is critical for both pulmonary specification and heart development, but how these activities are mechanistically integrated remains unclear. Here using Xenopus and mouse embryos, we establish molecular links between Tbx5 and retinoic acid (RA)-signaling in the mesoderm and between RA signaling and sonic hedgehog expression in the endoderm to unveil a conserved RA-Hedgehog-Wnt signaling cascade coordinating cardiopulmonary development. We demonstrate that Tbx5 directly maintains expression of aldh1a2, the RA-synthesizing enzyme, in the foregut lateral plate mesoderm via an evolutionarily conserved intronic enhancer. Tbx5 promotes posterior second heart field identity in a positive feedback loop with RA, antagonizing a Fgf8-Cyp regulatory module to restrict FGF activity to the anterior. We find that Tbx5/Aldh1a2-dependent RA signaling directly activates shh transcription in the adjacent foregut endoderm through a conserved MACS1 enhancer. Hedgehog signaling coordinates with Tbx5 in the mesoderm to activate expression of wnt2/2b, which induces pulmonary fate in the foregut endoderm. These results provide mechanistic insight into the interrelationship between heart and lung development informing cardiopulmonary evolution and birth defects.
Communication-avoiding micro-architecture to compute Xcorr scores for peptide identification

Database algorithms play a crucial part in systems biology studies by identifying proteins from mass spectrometry data. Many of these database search algorithms incur huge computational costs by computing similarity scores for each pair of sparse experimental spectrum and candidate theoretical spectrum vectors. Modern MS instrumentation techniques which are capable of generating high-resolution spectrometry data require comparison against an enormous search space, further emphasizing the need of efficient accelerators. Recent research has shown that the overall cost of scoring, and deducing peptides is dominated by the communication costs between different hierarchies of memory and processing units. However, these communication costs are seldom considered in accelerator-based architectures leading to inefficient DRAM accesses, and poor data-utilization due to irregular memory access patterns. In this paper, we propose a novel communication-avoiding microarchitecture to compute cross-correlation based similarity score by utilizing efficient local cache, and peptide pre-fetching to minimize DRAM accesses, and a custom-designed peptide broadcast bus to allow input reuse. An efficient bus arbitration scheme was designed, and implemented to minimize synchronization cost and exploit parallelism of processing elements. Our simulation results show that the proposed micro-architecture performs on average 24x better than a CPU implementation running on a 3.6 GHz Intel i7-4970 processor with 16GB memory.
A gentle introduction to the non-equilibrium physics of trajectories: Theory, algorithms, and biomolecular applications

Despite the importance of non-equilibrium statistical mechanics in modern physics and related fields, the topic is often omitted from undergraduate and core-graduate curricula. Key aspects of non-equilibrium physics, however, can be understood with a minimum of formalism based on a rigorous trajectory picture. The fundamental object is the ensemble of trajectories, a set of independent time-evolving systems, which easily can be visualized or simulated (e.g., for protein folding) and which can be analyzed rigorously in analogy to an ensemble of static system configurations. The trajectory picture provides a straightforward basis for understanding first-passage times, “mechanisms” in complex systems, and fundamental constraints on the apparent reversibility of complex processes. Trajectories make concrete the physics underlying the diffusion and Fokker–Planck partial differential equations. Last but not least, trajectory ensembles underpin some of the most important algorithms that have provided significant advances in biomolecular studies of protein conformational and binding processes.
Federalism, Race, and the Politics of Turnaround: U.S. Public Opinion on Improving Low-Performing Schools and Districts:

Public support for school improvement policies can increase the success and durability of those reforms. However, little is known about public views on turnaround. We capitalize on a nationally rep...
Leveraging Machine Learning to Detect Data Curation Activities

This paper describes a machine learning approach for annotating and analyzing data curation work logs at ICPSR, a large social sciences data archive. The systems we studied track curation work and coordinate team decision-making at ICPSR. Archive staff use these systems to organize, prioritize, and document curation work done on datasets, making them promising resources for studying curation work and its impact on data reuse, especially in combination with data usage analytics. A key challenge, however, is classifying similar activities so that they can be measured and associated with impact metrics. This paper contributes: 1) a set of data curation activities; 2) a computational model for identifying curation actions in work log descriptions; and 3) an analysis of frequent data curation activities at ICPSR over time. We first propose a set of data curation actions to help us analyze the impact of curation work. We then use this set to annotate a set of data curation logs, which contain records of data transformations and project management decisions completed by archive staff. Finally, we train a text classifier to detect the frequency of curation actions in a large set of work logs. Our approach supports the analysis of curation work documented in work log systems as an important step toward studying the relationship between research data curation and data reuse.
Functional additive models for optimizing individualized treatment rules.

A novel functional additive model is proposed, which is uniquely modified and constrained to model nonlinear interactions between a treatment indicator and a potentially large number of functional and/or scalar pretreatment covariates. The primary motivation for this approach is to optimize individualized treatment rules based on data from a randomized clinical trial. We generalize functional additive regression models by incorporating treatment-specific components into additive effect components. A structural constraint is imposed on the treatment-specific components in order to provide a class of additive models with main effects and interaction effects that are orthogonal to each other. If primary interest is in the interaction between treatment and the covariates, as is generally the case when optimizing individualized treatment rules, we can thereby circumvent the need to estimate the main effects of the covariates, obviating the need to specify their form and thus avoiding the issue of model misspecification. The methods are illustrated with data from a depression clinical trial with electroencephalogram functional data as patients' pretreatment covariates.
Approaches for Modeling Self-Organization in Plasmas

Pattern formations and self-organization of plasmas are phenomena that have been reported for various applications in which plasmas interact with media. These include material synthesis, electric propulsion, and medicine. Patterns vary by plasmas found in different discharge processes such as vacuum or high-pressure arc, low- and high-pressure glow, and streamer discharges. The existing breadth of research in this area shows that pattern formations depend on experimental conditions such as current, pressure, plasma species composition, properties and topology of material interacting with the plasma.
Temporal inhibition of chromatin looping and enhancer accessibility during neuronal remodeling

During development, looping of an enhancer to a promoter is frequently observed in conjunction with temporal and tissue-specific transcriptional activation. The chromatin insulator-associated protein Alan Shepard (Shep) promotes Drosophila post-mitotic neuronal remodeling by repressing transcription of master developmental regulators, such as brain tumor (brat), specifically in maturing neurons. Since insulator proteins can promote looping, we hypothesized that Shep antagonizes brat promoter interaction with an as yet unidentified enhancer. Using chromatin conformation capture and reporter assays, we identified two enhancer regions that increase in looping frequency with the brat promoter specifically in pupal brains after Shep depletion. The brat promoters and enhancers function independently of Shep, ruling out direct repression of these elements. Moreover, ATAC-seq in isolated neurons demonstrates that Shep restricts chromatin accessibility of a key brat enhancer as well as other enhancers genome-wide in remodeling pupal but not larval neurons. These enhancers are enriched for chromatin targets of Shep and are located at Shep-inhibited genes, suggesting direct Shep inhibition of enhancer accessibility and gene expression during neuronal remodeling. Our results provide evidence for temporal regulation of chromatin looping and enhancer accessibility during neuronal maturation. Long-range looping of an enhancer to a promoter (E-P looping) is a key feature of gene activation; thus, regulation of E-P looping could serve as an effective strategy to precisely control gene expression. Here the authors propose the Drosophila chromatin insulator antagonist Shep represses expression of genes during neuronal maturation by preventing E-P looping.
Communication: Effect of Oxidation on Excited State Dynamics of Neutral TinO2n-x (n<10, x<4) Clusters

Excited state lifetimes of neutral titanium oxide clusters (TinO2n-x, n < 10, x < 4) were measured using a sequence of 400 nm pump and 800 nm probe femtosecond laser pulses. Despite large differences in electronic properties between the closed shell stoichiometric TinO2n clusters and the suboxide TinO2n-x (x = 1-3) clusters, the transient responses for all clusters contain a fast response of 35 fs followed by a sub-picosecond excited state lifetime. In this non-scalable size regime, subtle changes in the sub-ps lifetimes are attributed to variations in the coordination of Ti atoms and localization of charge carriers following UV photoexcitation. In general, clusters exhibit longer lifetimes with increased size and also with addition of O atoms. This suggests that removal of O atoms develops stronger Ti-Ti bonds as the system transitions from a semiconducting character into a fast metallic electronic relaxation mechanism.
Can Facing the Truth Improve Outcomes? Effects of Information in Consumer Finance

This article explores when consumers avoid learning information about their credit scores and how viewing one’s credit score impacts future credit scores.
Strategic Remote Attestation: Testbed for Internet-of-Things Devices and Stackelberg Security Game for Optimal Strategies.

Internet of Things (IoT) devices and applications can have significant vulnerabilities, which may be exploited by adversaries to cause considerable harm. An important approach for mitigating this threat is remote attestation, which enables the defender to remotely verify the integrity of devices and their software. There are a number of approaches for remote attestation, and each has its unique advantages and disadvantages in terms of detection accuracy and computational cost. Further, an attestation method may be applied in multiple ways, such as various levels of software coverage. Therefore, to minimize both security risks and computational overhead, defenders need to decide strategically which attestation methods to apply and how to apply them, depending on the characteristic of the devices and the potential losses.
Quantifying Information via Shannon Entropy in Spatially Structured Optical Beams

While information is ubiquitously generated, shared, and analyzed in a modern-day life, there is still some controversy around the ways to assess the amount and quality of information inside a noisy optical channel. A number of theoretical approaches based on, e.g., conditional Shannon entropy and Fisher information have been developed, along with some experimental validations. Some of these approaches are limited to a certain alphabet, while others tend to fall short when considering optical beams with a nontrivial structure, such as Hermite-Gauss, Laguerre-Gauss, and other modes with a nontrivial structure. Here, we propose a new definition of the classical Shannon information via the Wigner distribution function, while respecting the Heisenberg inequality. Following this definition, we calculate the amount of information in Gaussian, Hermite-Gaussian, and Laguerre-Gaussian laser modes in juxtaposition and experimentally validate it by reconstruction of the Wigner distribution function from the intensity distribution of structured laser beams. We experimentally demonstrate the technique that allows to infer field structure of the laser beams in singular optics to assess the amount of contained information. Given the generality, this approach of defining information via analyzing the beam complexity is applicable to laser modes of any topology that can be described by well-behaved functions. Classical Shannon information, defined in this way, is detached from a particular alphabet, i.e., communication scheme, and scales with the structural complexity of the system. Such a synergy between the Wigner distribution function encompassing the information in both real and reciprocal space and information being a measure of disorder can contribute into future coherent detection algorithms and remote sensing.
Relaxing Local Robustness

Certifiable local robustness, which rigorously precludes small-norm adversarial examples, has received significant attention as a means of addressing security concerns in deep learning. However, for some classification problems, local robustness is not a natural objective, even in the presence of adversaries; for example, if an image contains two classes of subjects, the correct label for the image may be considered arbitrary between the two, and thus enforcing strict separation between them is unnecessary. In this work, we introduce two relaxed safety properties for classifiers that address this observation: (1) relaxed top-k robustness, which serves as the analogue of top-k accuracy; and (2) affinity robustness, which specifies which sets of labels must be separated by a robustness margin, and which can be $\epsilon$-close in $\ell_p$ space. We show how to construct models that can be efficiently certified against each relaxed robustness property, and trained with very little overhead relative to standard gradient descent. Finally, we demonstrate experimentally that these relaxed variants of robustness are well-suited to several significant classification problems, leading to lower rejection rates and higher certified accuracies than can be obtained when certifying "standard" local robustness.
Dither computing: a hybrid deterministic-stochastic computing framework

Stochastic computing has a long history as an alternative method of performing arithmetic on a computer. While it can be considered an unbiased estimator of real numbers, it has a variance and MSE on the order of $\displaystyle \Omega(\frac{1}{N})$ . On the other hand, deterministic variants of stochastic computing remove the stochastic aspect, but cannot approximate arbitrary real numbers with arbitrary precision and are biased estimators. However, they have an asymptotically superior MSE on the order of $O(\frac{1}{N^{2}})$ . Recent results in deep learning with stochastic rounding suggest that the bias in the rounding can degrade performance. We proposed an alternative framework, called dither computing, that combines aspects of stochastic computing and its deterministic variants and that can perform computing with similar efficiency, is unbiased, and with a variance and MSE also on the optimal order of $\displaystyle \Theta(\frac{1}{N^{2}})$ . We also show that it can be beneficial in stochastic rounding applications as well. We provide implementation details and give experimental results to comparatively show the benefits of the proposed scheme.
Psychology: The Adaptive Mind

In this introductory psychology text, the author treats research and theory from an adaptive problem-solving perspective. The subject matter of psychology is "reframed" by placing the major emphasis on how particular behaviours, cognitive processes, and emotions help people solve important adaptive problems, not just survival problems, but everyday problems. For example, the principles of classical conditioning are introduced as "solutions" to the problem of how people learn about signals in their environment; neural transmission is introduced as a "solution" to the problems associated with communicating internally; short-term memory is introduced as a "solution" to the problem of how people remember information over the short-term, and so on.
Fire-Sale FDI and Liquidity Crises

In placing capital market imperfections at the center of emerging market crises, the theoretical literature has associated a liquidity crisis with low foreign investment and the exit of investors from the crisis economy. However, a liquidity crisis is equally consistent with an inflow of foreign capital in the form of mergers and acquisitions (M&A). To support this hypothesis, we use a firm-level dataset to show that foreign acquisitions increased by 88% in East Asia between 1996 and 1998, while intra-national merger activity declined. Firm liquidity plays a significant and sizeable role in explaining both the increase in foreign acquisitions and the decline in the price of acquisitions during the crisis. This effect is most prominent in the tradable sectors and represents a significant departure from the pattern of M&A observed both before and after the crisis. Quantitatively, the observed decline in liquidity can explain nearly 30% of the increase in foreign acquisition activity in the tradable sectors. We argue that the nature of M&A activity during the crisis contradicts productivity-based explanations of the East Asian crisis.
Model indicators for maternal and child health: an overview of process, product, and applications.

Objectives: Further improvements in the health of mothers and children depend, in part, on collecting, analyzing, and interpreting relevant data correctly. Despite consistent efforts to improve data capacity and use during the past two decades, the need persists for a model set of maternal and child health (MCH) indicators to guide decisions about health conditions to be monitored, elements to be included in data sets, and definitions of measures. This article describes development, key characteristics, and major applications of a set of MCH Model Indicators (MCH MI) created to address these needs. Methods: A conceptual model with five domains was created to organize and guide development of the indicators. The development process included systematic specification of concepts, formulas, age/gender groups, and data sources, as well as recommendations for frequency of surveillance. Information sources included published reports and expert opinion. Results: There are 217 indicators distributed across domains as follows: 75 health status, 9 contextual characteristics, 16 health systems capacity and adequacy, 49 risk/protective status, and 68 health and related services. Twenty of the indicators, all of them in the health status domain, are recommended for routine surveillance. Conclusions: The indicators can be used to identify and address MCH problems, to complement and expand other sets of MCH indicators, to serve as standards for consistent definitions, to provide guidance for creation and revision of MCH and related data bases, and to provide a foundation for the development of related sets of indicators. Some of the indicators require further development, but the total MCH MI package constitutes a solid foundation for subsequent work, as well as for ongoing modifications that are essential if the Model Indicators are to remain responsive to MCH needs.
Using grammars to generate very large scale neighborhoods for the traveling salesman problem and other sequencing problems

Local search heuristics are among the most popular approaches to solve hard optimization problems. Among them, Very Large Scale Neighborhood Search techniques present a good balance between the quality of local optima and the time to search a neighborhood. We develop a language to generate exponentially large neighborhoods for sequencing problems using grammars. We develop efficient generic dynamic programming solvers that determine the optimal neighbor in a neighborhood generated by a grammar for sequencing problems such as the Traveling Salesman Problem or the Linear Ordering Problem. This framework unifies a variety of previous results on exponentially large neighborhood for the Traveling Salesman Problem and generalizes them to other sequencing problems.
A Prescriptive Approach To Introducing An Experiential Entrepreneurship Course In Undergraduate Education

Universities are continually adding entrepreneurship courses to their curriculum. Duhaime and Hitt (2000) found 82% of schools offered entrepreneurship courses at the undergraduate level and 69% of masters programs had offerings in entrepreneurship. A much smaller number of programs offer courses that require that the students actually start the business. The requirement of new venture creation adds an enormous amount of complexity to the teaching experience. Although each pedagogical endeavor will vary, this manuscript details one such experience, including the challenges and various successes of the course and offers recommendations for those professors and/or deans interested in adding a real-life experiential entrepreneurship course to their curriculum.
Autoimmune hemolytic anemia in chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis is an immunodeficiency disease characterized by T-cell dysregulation and chronic superficial candidal infections. We report on three patients with chronic mucocutaneous candidiasis who developed autoantibodies to erythrocytes. Our first patient, a 19-year-old female, developed autoimmune hemolytic anemia (AIHA) that required multiple courses of treatment, including corticosteroids, intravenous immunoglobulin, and danazol. During the last exacerbation of AIHA, intensive treatment with corticosteroids and intravenous immunoglobulin failed and yet the patient responded to plasmapheresis. Our second patient, a 21-year-old male, developed AIHA which responded to oral corticosteroid therapy. Our third patient, a 6-year-old female without evidence of hemolysis, was found to have erythrocyte autoantibodies on routine screening. These three patients had positive direct antiglobulin tests, and the first patient had both immunoglobulin G (IgG) and IgM erythrocyte autoantibodies, while the remaining two patients had only IgG autoantibody. This is the first report of the association of AIHA with chronic mucocutaneous candidiasis. We suggest that all patients with chronic mucocutaneous candidiasis be screened periodically for erythrocyte autoantibodies. Plasmapheresis, a safe ancillary procedure in the management of AIHA, may be life-saving in some cases. The occurrence of erythrocyte autoantibodies in mucocutaneous candidiasis may be related to immunoregulatory disorders in this disease.
Stellar S-Process Diagnostics

We argue that the solar-system σN curve can be best understood if the s-process is largely produced by stars in the mass range of M ∿ 2–4 MO. Several observations are then studied as indicators of the validity of this hypothesis. We find that isotopic Zr abundances and elemental (Ba/Sr) vs. (Ba/Nd) ratios are consistent with these conditions. The elemental (Tc/Nb) ratio is found not to be an indicator of temperature as has been suggested but rather a measure of the age of an AGB star in the third dredge-up phase.
Global sensitivity analysis of ozone production and O3–NOx–VOC limitation based on field data

Abstract Global sensitivity analysis was performed to study the effects of model uncertainties on the predictions of urban ozone production and its limitation by NO x or VOCs. Uncertainties were assigned for hundreds of model parameters including measurements used to constrain the model as well as kinetic rate coefficients and product yields of chemical reactions. Monte Carlo simulations were run using a zero-dimensional box model with 76 representative base cases of different initial conditions extracted from the measurements of a field campaign conducted in Houston, Texas. The results showed that relative uncertainty (±1 σ ) of ozone production exhibits a pattern of higher uncertainty at morning rush hour (about 30–40%) and lower uncertainty in the afternoon (about 20–30%). The model uncertainty comes mostly from uncertainties in chemical schemes while the uncertainties in measurements are less influential. The most important model parameters are generally associated with the amounts of acetaldehyde, the photolysis of HONO and HCHO(→HO 2 ), and the reactions of OH with NO 2 , HO 2 with NO, and xylenes with OH. The uncertainties in these parameters could also shift the ozone–precursor relation between the NO x -sensitive and VOC-sensitive regimes. The greater values of the NO amount and the reaction rates of NO 2 + OH, NO + HO 2 and ISOP (isoprene peroxy radicals) + NO increase VOC-sensitivity, while greater values of aldehydes amounts and kinetic rate coefficients for reactions of OH with aldehydes and xylenes and of ISOP with HO 2 increase NO x -sensitivity of ozone under the studied conditions.
Is sociology the science of the irrational? Conceptions of rationality in sociological theory

This paper explores the role of the concept of rationality in (especially classical) sociological theory. This exploration is prompted by widely held views, especially among economists and rational choice theorists, that classical sociology is the science of the irrational lacking a conception of rationality. By using pertinent examples (mostly) from classical and post-classical (or early contemporary) sociological theory, the paper casts serious doubt on such claims. Specifically, classical sociological theory is characterized by the following features in analyzing rationality: conceptual and methodological pluralism, theoretical and empirical richness, treating rationality as a complex social phenomenon, differentiating economic and noneconomic rationality, acknowledging the social character and foundation of (economic) rationality, and contrasting epistemological or scientific rationality and ontological or reallife irrationality, including the revelation of the irrationality of extreme (economic) rationality.
Measurements of heat transfer coefficients between turbulent liquid jets and a radially finned heated disk placed at the bottom of an open vertical circular cavity

Experiments have been performed to assess the impact of an extended surface on the heat transfer enhancement for axisymmetric, turbulent liquid jet impingement on a heated round disk. The disk, with an array of integral radial fins mounted on its surface, is placed at the bottom of an open vertical circular cavity. Hydrodynamic and heat transfer data were obtained for a dielectric fluorocarbon liquid FC-77. For a fixed circular heater of diameter D=22.23 mm, several geometric parameters were tested: the nozzle diameter (4.42≤d≤9.27 mm), the confining wall diameter of the vertical cavity (22.23≤Dc≤30.16 mm), and the nozzle-to-heater spacing (0.5≤S/d≤5.0). The FC-77 flow rates varied from =0.2 to 11.0 l/min producing Reynolds numbers in the wide interval 700≤Red≤44,000. For d=4.42 mm, the heat transfer response to the separation distance S/d was small but increased gradually with increasing nozzle diameter up to d=9.27 mm. The thermal resistance Rth increased with the confining wall diameter Dc and also with the nozzle diameter d. A minimum value of the thermal resistance of Rth,min=0.4 cm2 K/W was attained for a combination of d=4.42 mm, Dc=22.23 mm, S/d=1, and =7.5 l/min. Based on a simplified heat transfer model, reasonable agreement was obtained between measured values of the thermal resistance and the Rth-predictions. The total fin effectiveness ɛf was shown to increase with increasing nozzle diameter, but was invariant with the flow rate (or the jet exit velocity). More than a three-fold heat transfer enhancement was realized through the addition of the array of integral radial fins on the heated round disk.
Paradigms in Industrial Relations: Original, Modern and Versions In‐between

This article argues that the industrial relations (IR) field has had two distinct paradigms — an original paradigm centred on the employment relationship, and a modern paradigm centred on unions and labour‐management relations. In practice, IR scholars in the decades after the Second World War frequently adopted the former as a broad principle but followed the latter in research and teaching. The narrower labour‐management paradigm has created a significant survival challenge for the IR field, given the marked long-term decline in union density in most countries. I join with others in arguing that to survive and prosper in the years ahead, the field needs to return to an updated version of the original ‘employment relationship’ paradigm. To promote this end, I describe the major features of the original paradigm, including its core positive and normative principle. I also outline how this core principle provides the foundation for an integrative IR theory of the employment relationship, which the field greatly needs to move ahead.
On herding behavior

Abstract Herding behavior in ungulates is executed mainly by males. There are several forms of herding: guarding a single estrous female; rounding up a bunch of females during the rutting season; territorial herding by which a male keeps females inside his territory; herding of a moving, permanent, harem group; social herding in which group members of both sexes are herded by one dominant male. When put into this sequence, a phenotypical trend is illustrated, leading from an intimate connection of herding with mating behavior toward an increasing independence from sexual behavior and culminating in a complete socialization of herding. Aspects and problems of herding behavior are the recognition of, and the animal's respect for, partners in gregarious species; the animal “taking offense” at activities of others which deviate from its own activity; the active coordination and synchronization of group activities; the use of, and the effects of, threat, dominance and courtship displays in herding; the possibility of substitution among expressive displays in relation to partners of different sex; the communicative function of the animal's orientation relative to the partner; social hierarchy and leadership in a group; the possibility of interspecific herding, particularly in man-animal relationships, which is closely linked to the process of domestication.
Salmon-rich diet inhibits arachidonate cyclooxygenation in healthy men

Abstract Dietary long-chain omega-3 polyunsaturated fatty acids (PUFA) influence cardiovascular and immunological parameters. Eicosanoid-mediated processes are believed to be key metabolic components of the underlying mechanisms. With a view toward developing a biochemical basis to rationalize the phenomena observed, we compared the effect of a salmon (S, ω6 ω3 PUFA ratio = 3.6 ) and of a reference (R, ω6 ω3 = 19.5 ) diet on the biosynthesis of E prostaglandins in 10 male volunteers by measuring the major urinary metabolite. PGE-M, in 24-hr urine by gas chromatography-mass spectrometry. Energy contributions (en%) from proteins, carbohydrates, and fat were virtually identical in both diets: 19, 56, and 25%, respectively. The subjects were confined in a nutrition suite at the Western Human Nutrition Research Center for 100 days. During a stabilization period of 20 days, they were placed on the R diet. Then half were fed the S diet for 40 days while the others remained on the reference diet. The two groups switched diets for the last 40-day period. The menu cycle was 5 days, and all diets were calculated to provide adequate amounts of essential nutrients. Diet S was associated with an average 24% reduction in PGE-M daily output, in comparison to diet R ( P = 0.001). This reduction in the synthetic rate of E prostaglandins was attained by incorporating less than 500 g/day of salmon in the diet. Omega-6 PUFA were maintained constant in both diets. An alteration of PGE synthesis of this size is likely to have clinically significant repercussions on cardiovascular and immune functions. Although these effects appear to occur in a predominantly favorable direction, other physiological systems (e.g., the renal system) might be affected in ways yet to be determined.
Changes in mumps virus neurovirulence phenotype associated with quasispecies heterogeneity

Mumps virus is a highly neurotropic virus with evidence of central nervous system invasion (CNS) in approximately half of all cases of infection. In countries where live attenuated mumps virus vaccines were introduced, the number of mumps cases declined dramatically; however, recently, the safety of some vaccine strains has been questioned. For example, one of the most widely used vaccines, the Urabe AM9 strain, was causally associated with meningitis, leading to the withdrawal of this product from the market in several countries. This highlights the need for a better understanding of the attenuation process and the identification of markers of attenuation. To this end, we further attenuated the Urabe AM9 strain by serial passage in cell culture and compared the complete nucleotide sequences of the parental and passaged viruses. Interestingly, despite a dramatic decrease in virus virulence (as assayed in rats), the only genomic changes were in the form of changes in the level of genetic heterogeneity at specific genome sites, i.e., either selection of one nucleotide variant at positions where the starting material exhibited nucleotide heterogeneity or the evolution of an additional nucleotide to create a heterogenic site. This finding suggests that changes in the level of genetic heterogeneity at specific genome sites can have profound neurovirulence phenotypic consequences and, therefore, caution should be exercised when evaluating genetic markers of virulence or attenuation based only on a consensus sequence.
Morphological studies on cardiac lethal mutant salamander hearts in organ cultures

Recessive mutant gene c in Ambystoma mexicanum results in an absence of embryonic heart function. When mutant hearts are transplanted into normal embryos, the defect is corrected and the mutant hearts beat. In reciprocal transplants normal hearts do not beat. These experiments suggest that there is either a lack of induction from surrounding tissues or an inhibitory influence of some kind. We undertook the present study to determine whether the influence in vivo might be an inhibitory one which could be corrected simply by removing the heart from the embryo and growing it in culture. Hearts from normal and mutant siblings from stages 35–40 were explanted into hangingdrop cultures in Holtfreter's solution. Normal hearts continued to beat strongly while mutant hearts failed to beat. After five to seven days, cultured hearts were compared to in vivo hearts at the same period of development using light and electron microscopy. The myocardium of normal hearts is composed of highly differentiated muscle cells with numerous well-organized myofibrils. The mutant myocardial cells contain a few filaments and an occasional Z body, however, sarcomere organization is not apparent. In general, no major differences in morphology or function could be found between the cultured and in vivo hearts at the same period of development. Thus, the cultures closely mimick the in vivo situation and present evidence against an inhibitory process causing the defect.