cssi/SciSciGPT-SciSciNet huggingface dataset:
Predicting volatility: getting the most out of return data sampled at different frequencies

Abstract We consider various mixed data sampling (MIDAS) regressions to predict volatility. The regressions differ in the specification of regressors (squared returns, absolute returns, realized volatility, realized power, and return ranges), in the use of daily or intra-daily (5-min) data, and in the length of the past history included in the forecasts. The MIDAS framework allows us to compare regressions across all these dimensions in a very tightly parameterized fashion. Using equity return data, we find that daily realized power (involving 5-min absolute returns) is the best predictor of future volatility (measured by increments in quadratic variation) and outperforms models based on realized volatility (i.e. past increments in quadratic variation). Surprisingly, the direct use of high-frequency (5 min) data does not improve volatility predictions. Finally, daily lags of 1–2 months are sufficient to capture the persistence in volatility. These findings hold both in- and out-of-sample.
Exchange Rate Fundamentals and Order Flow

We address whether transaction flows in foreign exchange markets convey fundamental information. Our General Equilibrium model includes fundamental information that first manifests at the micro level and is not symmetrically observed by all agents. This produces foreign exchange transactions that play a central role in information aggregation, providing testable links between transaction flows, exchange rates, and future fundamentals. We test these links using data on all end-user currency trades received at Citibank over 6.5 years, a sample sufficiently long to analyze real-time forecasts at the quarterly horizon. The predictions are borne out in four empirical findings that define this paper's main contribution: (1) transaction flows forecast future macro variables such as output growth, money growth, and inflation, (2) transaction flows forecast these macro variables significantly better than the exchange rate does, (3) transaction flows (proprietary) forecast future exchange rates, and (4) the forecasted part of fundamentals is better at explaining exchange rates than standard measured fundamentals.
A New Approach to Taxing Financial Intermediation Services Under a Value-Added Tax

This paper contains a proposal (referred to as the "modi- fi ed reverse-charging" approach) to tax fi nancial intermediation services under a VAT. At the heart of the proposal is the application of a reverse charge that shifts the collection of the VAT on deposit interest from depositors to banks, in conjunction with the establish- ment of a franking mechanism managed by banks that effectively transfers the VAT so collected to borrowers as credits against the VAT on their loan interest on a transaction-by-transaction basis. The proposal is fully compatible with an invoice-credit VAT and is capable of delivering the correct theoretical result at minimal administrative costs.
Economic implications for Turkey of a Customs Union with the European Union

Abstract With a CGE model, we quantify the impact of the Customs Union between Turkey and the European Union (EU). Since the average tariff on non-agricultural imports will be less than 2 percent, the trade diversion costs of the Customs Union are quite small. Improved access to third country markets (through reciprocal preferential access agreements of the EU) results in the largest gains from the Customs Union, estimated overall to be about 1–1.5 percent of Turkish GDP. Applying the VAT uniformly (rather than raising it to compensate for the tariff revenue loss) will increase the welfare gain from joining the EU.
Ultrafast Polariton-Phonon Dynamics of Strongly Coupled Quantum Dot-Nanocavity Systems

We investigate the influence of exciton-phonon coupling on the dynamics of a strongly coupled quantum dot-photonic crystal cavity system and explore the effects of this interaction on different schemes for nonclassical light generation. By performing time-resolved measurements, we map out the detuning-dependent polariton lifetime and extract the spectrum of the polariton-to-phonon coupling with unprecedented precision. Photon-blockade experiments for different pulse-length and detuning conditions (supported by quantum optical simulations) reveal that achieving high-fidelity photon blockade requires an intricate understanding of the phonons' influence on the system dynamics. Finally, we achieve direct coherent control of the polariton states of a strongly coupled system and demonstrate that their efficient coupling to phonons can be exploited for novel concepts in high-fidelity single-photon generation.
Is There a Right Way to Nudge? The Practice and Ethics of Choice Architecture

Cass Sunstein and Richard Thaler’s Nudge: Improving Decisions about Health, Wealth, and Happiness presents an influential account of why ‘choice architecture’ should be used to ‘nudge’ people into making better decisions than they would otherwise make. In this essay we: (1) explain the main concepts that Thaler and Sunstein rely upon to defend their project; (2) clarify the main conceptual problems that have arisen in discussions about nudges; (3) clarify practical difficulties that can arise during nudge practice; (4) review the main ethical and political objections that have been raised against nudging; and (5) clarify why issues related to meaning can pose methodological problems for creating effective choice architecture.
Competition and contracting in service industries

Abstract In service industries with congestion effects, two very different contractual structures are commonly observed, depending on whether or not firms choose to offer a guaranteed service level. We analyze the impact of these choices on market outcomes in oligopolistic industries. Our results highlight how different contractual agreements change the intensity of price competition in service industries. Broadly speaking, we show that competition is intensified when firms choose to offer service level guarantees.
The influence of body weight on social network ties among adolescents

Evidence of negative stereotypes, prejudice and discrimination towards obese individuals has been widely documented. However, the effect of a larger body size on social network ties or friendship formations is less well understood. In this paper, we explore the extent to which higher body weight results in social marginalization of adolescents. Using data from a nationally representative sample of adolescents, we estimate endogeneity-corrected models including school-level fixed effects that account for bi-directionality and unobserved confounders to ascertain the effect of body weight on social network ties. We find that obese adolescents have fewer friends and are less socially integrated than their non-obese counterparts. We also find that such penalties in friendship networks are present among whites but not African-Americans or Hispanics, with the largest effect among white females. These results are robust to common environmental influences at the school-level and to controls for preferences, risk attitudes, low self-esteem and objective measures of physical attractiveness.
Discussion of “The revolving door and the SEC׳s enforcement outcomes: Initial evidence from civil litigation” by deHaan, Kedia, Koh, and Rajgopal (2015)

Abstract The study by deHaan et al. (2015) provides an empirical analysis of the effects of revolving door incentives at the SEC. Using a sample of SEC lawyers prosecuting civil cases of accounting misrepresentation, the authors examine how three measures of enforcement outcomes are related to the lawyers׳ career paths. I discuss specific elements of the study׳s research design, including the measurement of the study׳s two key elements, revolving door incentives and regulatory oversight, and comment on the paper׳s findings. While the study is interesting and creative, I believe that its limitations are too great to allow for meaningful conclusions.
Corporate Social Responsibility, Tax Avoidance, and Earnings Performance

ABSTRACT: I investigate the influence of pretax earnings performance on the relation between corporate social responsibility (CSR) and tax avoidance. Prior studies of the relation between CSR and ...
Word of Mouth for Movies: Its Dynamics and Impact on Box Office Revenue:

Abstract This article uses actual word-of-mouth (WOM) information to examine the dynamic patterns of WOM and how it helps explain box office revenue. The WOM data were collected from the Yahoo Movies Web site. The results show that WOM activities are the most active during a movie's prerelease and opening week and that movie audiences tend to hold relatively high expectations before release but become more critical in the opening week. More important, WOM information offers significant explanatory power for both aggregate and weekly box office revenue, especially in the early weeks after a movie opens. However, most of this explanatory power comes from the volume of WOM and not from its valence, as measured by the percentages of positive and negative messages.
The Basel III Liquidity Coverage Ratio and Financial Stability

Banks and other financial institutions may increase the amount of credit available in the financial system by borrowing for short terms and lending for long terms. Though this “maturity transformation” is a useful and productive function of banks, it gives rise to the possibility that even prudently managed banks could fail due to a lack of liquid assets. The financial crisis of 2007-2008 revealed the extent to which the U.S. financial system is exposed to the risk of a system-wide failure from insufficient liquidity. Financial regulators from economies around the world have responded to the crisis by proposing new, internationally uniform bank liquidity standards, augmenting the existing Basel Capital Accord. This Note argues that a major component of these standards, the Liquidity Coverage Ratio requirement, may work to undermine the goals of effective liquidity regulation and instead contribute to issues of systemic risk.
China's Turn Against Law

Chinese authorities are reconsidering legal reforms they enacted in the 1980s and 1990s. These reforms had emphasized law, litigation, and courts as institutions for resolving civil grievances between citizens and administrative grievances against the state. But social stability concerns have led top leaders to question these earlier reforms. Central Party leaders now fault legal reforms for insufficiently responding to (or even generating) surging numbers of petitions and protests.Chinese authorities have now drastically altered course. Substantively, they are de-emphasizing the role of formal law and court adjudication. They are attempting to revive pre-1978 Maoist-style court mediation practices. Procedurally, Chinese authorities are also turning away from the law. They are relying on political, rather than legal, levers in their effort to remake the Chinese judiciary. This Article analyzes the official Chinese turn against law. These Chinese developments are not entirely unique. American courts have also experienced a broad shift in dispute resolution patterns over the last century. Litigation has fallen out of favor. Court trials have dropped in number. Alternative dispute resolution mechanisms have increased in number. Observing such long-term patterns, Marc Galanter concluded that the United States experienced a broad “turn against law” over the 20th century. China’s shift also parallels those in other developing countries. In recent decades, nations such as India, Indonesia, and the Philippines have resuscitated or formalized traditional mediative institutions. This is part of a global reconsideration of legal norms and institutions imported or transplanted from the West.Despite these similarities with global trends, this Article argues that Chinese leaders’ shift against law is a distinct domestic political reaction to building pressures in the Chinese system. It is a top-down authoritarian response motivated by social stability concerns. This Article also analyzes the risks facing China as a result of the shift against law. It argues that the Chinese leadership’s concern with maintaining social stability in the short term may be leading them to take steps that are having severe long-term effects of undermining Chinese legal institutions and destabilizing China.Last, this Article argues for rethinking the trajectory of Chinese legal studies. Scholars need to shift away from focusing on formal Chinese law and legal institutions in order to understand how the Chinese legal system actually operates and the direction it is heading.
Conceptualizing Complicity in Alien Tort Cases

The Alien Tort Statute (ATS) indisputably brings international law into U.S. courts. The question is: How much international law? The U.S. Supreme Court was recently precluded from addressing this question in cases involving alleged corporate complicity in the crime of apartheid because four judges recused themselves, leaving the court without a quorum. The answer to this question can determine the outcome of cases brought against corporations for alleged complicity in international law violations by foreign governments. It will also shape the extent to which U.S. courts in ATS cases continue to interpret and apply international law, thereby contributing to the development and enforcement of international law standards. This Article provides an analytic roadmap for courts confronting accomplice liability claims in ATS cases. Part I concludes that U.S. courts should look to international law on accomplice liability, rather than federal common law. Part II examines international law doctrine on accomplice liability and concludes that the Second Circuit in the South African apartheid cases misstated the applicable standard, which prohibits knowingly providing assistance that has a substantial effect on the commission of the wrongful act. Part III considers the implications of this doctrinal analysis for broader concerns about the indeterminacy of international law and notions of international comity. By applying well-established international law to defendants' conduct, U.S. courts can provide domestic remedies for international wrongs while avoiding criticisms of illegitimately applying U.S. substantive law outside U.S. territory.
After Flint: Environmental Justice as Equal Protection

The lead crisis in Flint, Michigan has captivated the nation, prompting calls for reform. Even so, the discourse surrounding Flint’s aftermath has been surprisingly unimaginative. In this Essay, we conceptualize Flint as an archetypical case of underenforcement — that is, a denial of the equal protection of laws guaranteed by the U.S. Constitution. Vulnerable populations are particularly harmed by enforcement deficits in the environmental and public health arenas. These harms are in many respects functionally equivalent to the unredressed private violence that motivated the Fourteenth Amendment. Viewed as such, the inadequacy of environmental regulation can be understood as a failure of equal protection: a failure that extends beyond the confines of Flint; a failure that demands a far more expansive duty to protect vulnerable populations. We offer two suggestions for combatting the underenforcement of environmental laws: (1) reallocating some or all of the investigatory and enforcement responsibility now vested in EPA to the Department of Justice, and (2) broadening the kinds legal actions available to the federal government as means to effectuate environmental justice.
Federal Enforcement of Police Reform

Congress passed 42 U.S.C. § 14141 in an effort to combat police misconduct and incentivize proactive reform in local law enforcement agencies. The statute gives the U.S. Attorney General the power to initiate structural reform litigation against local police departments engaged in a pattern or practice of unconstitutional behavior. While academics initially praised the law’s passage, many have since worried that the Department of Justice (DOJ) has not effectively administered the measure. Little research has analyzed how the DOJ has used its authority to initiate structural police reform. Using a combination of qualitative and quantitative methods, I fill this gap in the available literature by detailing the DOJ’s use of structural police reform over time. I conclude that the DOJ has historically underenforced § 14141, due in part to resource limitations that prevent the agency from aggressively pursuing all reported cases of systemic misconduct. I also show that the DOJ has unevenly enforced § 14141 over time. Changes in leadership and internal policies have influenced the DOJ’s use of structural police reform. These changes affected both the breadth and depth of enforcement. In some cases where systemic police misconduct did appear to exist, a phenomenon I refer to as “political spillover” deterred the DOJ from turning to structural police reform. Based on these findings, I argue that the DOJ must adopt a more transparent internal case selection process that incentivizes proactive reform in local police agencies. And given the resource limitations facing the DOJ in enforcing § 14141, I contend that state and national policymakers should seek alternative routes to increase the number of structural police reform cases. Combined, these changes could ensure that structural police reform lives up to its potential as a transformative tool for combating police wrongdoing.
Science, Politics, Law and the Arc of the Clean Water Act: The Role of Assumptions in the Adoption of a Pollution Control Landmark

This article examines the assumptions upon which Congress relied in enacting the 1972 Clean Water Act and the extent to which they have been borne out or belied as the federal and state governments have implemented their statutory responsibilities in the quest to achieve acceptably clean water. It traces the development of federal water pollution control legislation before 1972, highlighting the deficiencies that contributed to the need for a new approach in 1972. It then examines the scientific and technical, political, and legal assumptions that helped shape the 1972 Clean Water Act in an effort to determine whether the failure to achieve fully the statute’s goals is inherent in the statute’s design or is more likely the result of the law’s incomplete implementation. The article concludes that a surprisingly large share of the assumptions upon which Congress built the Clean Water Act were valid and have helped to make the statute an environmental success story. The statute’s failure to perform even more admirably than it has is due largely to a lack of legislative clarity in addressing the role of wetlands in preserving the integrity of aquatic ecosystems and to Congress’ unwillingness to adopt, or force the states to adopt, measures to control nonpoint source pollution.
Between Rights and Contract: Arbitration Agreements and Non-Compete Covenants as a Hybrid Form of Employment Law

The employment relationship is governed largely by contract, but with a heavy overlay of “rights”: minimum terms and individual rights that are established by external law and are typically nonwaivable. But some terms of employment are governed neither by ordinary contract nor by ordinary rights, nor even by ordinary waivable rights. Both of the two most controversial contractual instruments in employment law today—non-compete covenants and mandatory arbitration agreements—take the form of written contracts; both waive important employee rights (the right to compete postemployment, the right to litigate future claims); and both are subject to substantive criteria of validity that are set by external law. Both bodies of law may be usefully described as recognizing “conditionally waivable” rights. This Article aims first to show structural parallels between non-compete covenants and mandatory arbitration agreements that place them at a distinct intermediate point along the spectrum between nonwaivable rights and ordinary contract. Second, it seeks to uncover a common logic underlying the law’s choice of this particular hybrid of rights and contract. The linchpin of that common logic lies in the threat that an unregulated waiver of one right (the right to compete or to litigate future claims) poses to adjacent employee rights that the law deems nonwaivable. Third, this Article deploys that underlying logic to offer a critical assessment of the law governing non-competes and arbitration agreements. Finally, this Article tentatively explores the broader potential usefulness of conditional waivability as a way of regulating some terms of employment. The intriguing potential of conditional waivability lies in its injection of some of the virtues of contract—especially flexibility and variability in the face of widely divergent and changing circumstances—into the pursuit of public goals and the realization of rights in the workplace.
One perspective on sentencing reform in the United States

The most difficult part of constructing a system of criminal sentencing is to be able to give a rationale for each sentence. Historically, this has been an unsurmountable hurdle because it required reformers to resolve the irresolvable conflict between utility and desert as sentencing goals and to measure the immeasurably complex relative utility of the alterative utilitarian strategies of deterrence, incapacitation, and rehabilitation.
Ensuring Effective Counsel for Parents: Extending Padilla to Termination of Parental Rights Proceedings

The increase in the number of incarcerated women, combined with the severe effects of ASFA's 15/22 rule, has dramatically increased the risk that a incarcerated mother face a termination of her parental rights. Currently, existing ethical and statutory protections have been insufficient to protect these parents’ rights to their children. However, after Padilla v. Kentucky, it is likely that there is a Sixth Amendment obligation on criminal defense attorneys to advise their clients about the effect of the criminal process on a TPR proceeding. This advice should not be limited to a mere suggestion that clients seek legal advice from an attorney specializing in TPR law. Instead, criminal defense attorneys are obligated to protect this unique population by providing advice and counsel throughout the criminal proceeding to their clients concerning how best to protect the family unit from TPR proceedings.
Season of Birth and Later Outcomes: Old Questions, New Answers

Season of birth is associated with later outcomes; what drives this association remains unclear. We consider a new explanation: variation in maternal characteristics. We document large changes in maternal characteristics for births throughout the year; winter births are disproportionally realized by teenagers and the unmarried. Family background controls explain nearly half of season-of-birth's relation to adult outcomes. Seasonality in maternal characteristics is driven by women trying to conceive; we find no seasonality among unwanted births. Prior seasonality-in-fertility research focuses on conditions at conception; here expected conditions at birth drive variation in maternal characteristics while conditions at conception are unimportant.
The Predictive Power of the Yield Curve across Countries and Time

In recent years, there has been renewed interest in the yield curve (or alternatively, the term premium) as a predictor of future economic activity. In this article, we re-examine the evidence for this predictor for both the United States and other advanced economies. We examine the sensitivity of the results to the selection of countries, and to time periods. We find that the predictive power of the yield curve has deteriorated in the last half of the sample period, although there is evidence of a reversal in the lead-up to the Great Recession. There is reason to believe that European country models perform better than those with non-European countries when using more recent data. In addition, the yield curve proves to have predictive power even after accounting for other leading indicators of economic activity.
Uniqueness of Morava K-theory

We show that there is an essentially unique S -algebra structure on the Morava K -theory spectrum K ( n ), while K ( n ) has uncountably many MU or -algebra structures. Here is the K ( n )-localized Johnson–Wilson spectrum. To prove this we set up a spectral sequence computing the homotopy groups of the moduli space of A ∞ structures on a spectrum, and use the theory of S -algebra k -invariants for connective S -algebras found in the work of Dugger and Shipley [ Postnikov extensions of ring spectra , Algebr. Geom. Topol. 6 (2006), 1785–1829 (electronic)] to show that all the uniqueness obstructions are hit by differentials.
A climate-constrained nepa

The fight to force climate change into environmental impact assessment pursuant to the National Environmental Policy Act (NEPA) to date has been long, bitter and mostly pointless. Even where agencies have relented in litigation or have proactively worked to integrate climate change considerations into their NEPA documents, the factoring done has consigned these considerations to the margins. Impact assessment naturally does so. Every such action/assessment will involve what amounts to a drop in a bucket of contributory causes to a globally-scaled, temporally remote catastrophe. Aggregative analyses minimize such contributions behind other, more immediate choice factors. A 2014 proposed guidance on climate change and NEPA from the Council on Environmental Quality ignored this fact. Likewise, the Office of Management & Budget’s “social cost of carbon” estimates allow almost everything they inform to go forward essentially unchanged. This article argues that a new approach is urgently needed and available. The approach sketched here consists in the development of programmatic alternatives pursuant to NEPA § 102(2)(E). That provision of the Act requires all agencies to study and develop alternative uses of “available resources” regardless of the magnitude or timing of their actions’ marginal environmental impact. The article makes the case that our principal “resource” where climate change is concerned now is what remains of our “burnable” carbon. Especially if we are to pursue the mitigation goals the U.S. Government committed to in Paris in December 2015, this approach is urgently needed. The steps outlined in Part IV of the article will help speed the U.S.’s development of mitigation options without many of the frictions other approaches will entail.
Fully non-linear degenerate elliptic equations in complex geometry

Abstract We derive an a priori real Hessian estimate for solutions of a large family of geometric fully non-linear elliptic equations on compact Hermitian manifolds, which is independent of a lower bound for the right-hand side function. This improves on the estimates of Szekelyhidi [57] and additionally applies to elliptic equations with a degenerate right-hand side. As an application, we establish the optimal C 1 , 1 regularity of envelopes of ( θ , m ) -subharmonic functions on compact Hermitian manifolds.
Proof Discontinuities and Civil Settlements

This Article explores settlement incentives under three different burden of proof rules. The conventional burden of proof is a discontinuous step-function, jumping from no damages to full damages at the 0.5 jury confidence level. Continuous burdens of proof, by contrast, would permit sanctions to steadily increase as juror confidence rises from 0 to 1, with no discontinuity. Linear burdens, which have received extensive attention in prior literature, escalate sanctions steadily across the whole range of confidence levels, while the logistic burden takes a nonlinear form. Using a data simulation approach guided by the empirical realities of American civil litigation, I consider the incentives that each of these rules creates for parties contemplating settlement, using a model in which parties make divergent forecasts of their expected outcomes at trial due to optimism bias. Based on this analysis, I conclude that a linear burden would likely raise our settlement rate by a modest amount, except in very large cases and in “easy” cases, in which an unbiased person would predict that a trial factfinder would have a level of confidence in liability quite close to either zero or one. I also compare the expected error rate of the settlements that each rule produces, and fnd that the linear rule modestly lowers the expected error rate of settlement overall, although this benefit does not hold for easy cases or those with very high damages. Lastly, I conduct a similar analysis for the logistic burden, finding that it induces a similar quality and quantity of settlements as we currently achieve using conventional burdens.
Generic tropical initial ideals of Cohen-Macaulay algebras

Abstract We study the generic tropical initial ideals of a positively graded Cohen-Macaulay algebra R over an algebraically closed field k. Building on work of Romer and Schmitz, we give a formula for each initial ideal, and we express the associated quasivaluations in terms of certain I-adic filtrations. As a corollary, we show that in the case that R is a domain, every initial ideal coming from the codimension 1 skeleton of the tropical variety is prime, so “generic presentations of Cohen-Macaulay domains are well-poised in codimension 1.”
Cooperative Activation of Cellulose with Natural Calcium.

Naturally occurring metals, such as calcium, catalytically activate the intermonomer β-glycosidic bonds in long chains of cellulose, initiating reactions with volatile oxygenates for renewable appl...
Angle-Based Sensor Network Localization

This paper studies angle-based sensor network localization (ASNL) in a plane, which is to determine locations of all sensors in a sensor network, given locations of partial sensors (called anchors) and angle constraints based on bearings measured in the local coordinate frame of each sensor. We firstly show that a framework with a non-degenerate bilateration ordering must be angle fixable, which implies that it can be uniquely determined by angles between edges up to translation, rotation, scaling, and reflection. Then we prove that an ASNL problem has a unique solution if and only if its grounded framework is angle fixable and anchors are not all collinear. Subsequently, ASNL is solved under centralized and distributed approaches, respectively. The noise-free centralized ASNL is formulated as a rank-constrained optimization problem, and shown to be equivalent to a linear semi-definite program (SDP) when the grounded framework is acute-triangulated. In order to deal with large and sparse ASNL, a decomposition strategy is proposed to recast the centralized ASNL as an SDP with semi-definite constraints on multiple submatrices in reduced sizes.
Implementing the United States’ Domestic and International Climate Mitigation Goals: A Supportive Fiscal Policy Approach

The United States has pledged to become carbon neutral by 2050, meet sectoral objectives (e.g., for carbon free power, electric vehicles) and encourage greater mitigation among large emitting countries and of international transportation emissions. Fiscal policies at the national, sectoral, and international level could play a critical role in implementing these objectives, along with investment, regulatory, and technology policies. Fiscal instruments are cost-effective, can enhance political acceptability, and do not worsen, or could help alleviate, budgetary pressures. Domestically, a fiscal policy package could contain a mix of economy-wide carbon pricing and revenue-neutral feebates (i.e., tax-subsidy schemes) with the latter reinforcing mitigation in the transport, power, industrial, building, forestry, and agricultural sectors. Internationally, a carbon price floor among large emitters (with flexibility to implement equivalent measures) could effectively scale up global mitigation, while levies/feebates offer a practical approach for reducing maritime and aviation emissions.
A fast saddle-point dynamical system approach to robust deep learning.

Abstract Recent focus on robustness to adversarial attacks for deep neural networks produced a large variety of algorithms for training robust models. Most of the effective algorithms involve solving the min–max optimization problem for training robust models (min step) under worst-case attacks (max step). However, they often suffer from high computational cost from running several inner maximization iterations (to find an optimal attack) inside every outer minimization iteration. Therefore, it becomes difficult to readily apply such algorithms for moderate to large size real world data sets. To alleviate this, we explore the effectiveness of iterative descent–ascent algorithms where the maximization and minimization steps are executed in an alternate fashion to simultaneously obtain the worst-case attack and the corresponding robust model. Specifically, we propose a novel discrete-time dynamical system-based algorithm that aims to find the saddle point of a min–max optimization problem in the presence of uncertainties. Under the assumptions that the cost function is convex and uncertainties enter concavely in the robust learning problem, we analytically show that our algorithm converges asymptotically to the robust optimal solution under a general adversarial budget constraints as induced by l p norm, for 1 ≤ p ≤ ∞ . Based on our proposed analysis, we devise a fast robust training algorithm for deep neural networks. Although such training involves highly non-convex robust optimization problems, empirical results show that the algorithm can achieve significant robustness compared to other state-of-the-art robust models on benchmark data sets.
Free products of finite-dimensional and other von Neumann algebras in terms of free Araki–Woods factors

Abstract We show that any free product of finite-dimensional von Neumann algebras equipped with non-tracial states is isomorphic to a free Araki–Woods factor with its free quasi-free state possibly direct sum a finite-dimensional von Neumann algebra. This gives a complete answer to questions posed by Dykema in [5] and Shlyakhtenko in [10] , which had been partially answered by Houdayer in [7] and Ueda in [16] . We also extend this to suitable infinite-dimensional von Neumann algebras with almost periodic states.
Tuning the valence and concentration of europium and luminescence centers in GaN through co-doping and defect association

Defect physics of europium (Eu) doped GaN is investigated using first-principles hybrid density-functional defect calculations. This includes the interaction between the rare-earth dopant and native point defects (Ga and N vacancies) and other impurities (O, Si, C, H, and Mg) unintentionally present or intentionally incorporated into the host material. While the trivalent ${\mathrm{Eu}}^{3+}$ ion is often found to be predominant when Eu is incorporated at the Ga site in wurtzite GaN, the divalent ${\mathrm{Eu}}^{2+}$ is also stable and found to be predominant in a small range of Fermi-level values in the band-gap region. The ${\mathrm{Eu}}^{2+}$/${\mathrm{Eu}}^{3+}$ ratio can be tuned by tuning the position of the Fermi level and through defect association. We find co-doping with oxygen can facilitate the incorporation of Eu into the lattice. The unassociated ${\mathrm{Eu}}_{\mathrm{Ga}}$ is an electrically and optically active defect center and its behavior is profoundly impacted by local defect-defect interaction. Defect complexes such as ${\mathrm{Eu}}_{\mathrm{Ga}}\text{\ensuremath{-}}{\mathrm{O}}_{\mathrm{N}}$, ${\mathrm{Eu}}_{\mathrm{Ga}}\text{\ensuremath{-}}{\mathrm{Si}}_{\mathrm{Ga}}$, ${\mathrm{Eu}}_{\mathrm{Ga}}\text{\ensuremath{-}}{\mathrm{H}}_{i}$, ${\mathrm{Eu}}_{\mathrm{Ga}}\text{\ensuremath{-}}{\mathrm{Mg}}_{\mathrm{Ga}}$, and ${\mathrm{Eu}}_{\mathrm{Ga}}\text{\ensuremath{-}}{\mathrm{O}}_{\mathrm{N}}\text{\ensuremath{-}}{\mathrm{Mg}}_{\mathrm{Ga}}$ can efficiently act as deep carrier traps and mediate energy transfer from the host into the ${\mathrm{Eu}}^{3+}\phantom{\rule{4pt}{0ex}}4f$-electron core which then leads to sharp red intra-$f$ luminescence. Eu-related defects can also give rise to defect-to-band luminescence. The unassociated ${\mathrm{Eu}}_{\mathrm{Ga}}$, for example, is identified as a possible source of the broad blue emission observed in $n$-type, ${\mathrm{Eu}}^{2+}$-containing GaN. This work calls for a re-assessment of certain assumptions regarding specific defect configurations previously made for Eu-doped GaN and further investigation into the origin of the photoluminescence hysteresis observed in (Eu,Mg)-doped samples.
Kinetic Simulations of Electron Pre-energization by Magnetized Collisionless Shocks in Expanding Laboratory Plasmas

Collisionless shocks are common features in space and astrophysical systems where supersonic plasma flows interact, such as in the solar wind, the heliopause, and supernova remnants. Recent experimental capabilities and diagnostics allow detailed laboratory investigations of high-Mach-number shocks, which therefore can become a valuable way to understand shock dynamics in various astrophysical environments. Using 2D particle-in-cell simulations with a Coulomb binary collision operator, we demonstrate the mechanism for generation of energetic electrons and experimental requirements for detecting this process in the laboratory high-Mach-number collisionless shocks. We show through a parameter study that electron acceleration by magnetized collisionless shocks is feasible in laboratory experiments with laser-driven expanding plasmas.
Steady-state analysis of load balancing with Coxian-2 distributed service times

This paper studies load balancing for many-server ($N$ servers) systems assuming Coxian-$2$ service time and finite buffer with size $b-1$ (i.e. a server can have at most one job in service and $b-1$ jobs in queue). We focus on steady-state performance of load balancing policies in the heavy traffic regime such that the load of system is $\lambda = 1 - N^{-\alpha}$ for $0<\alpha<0.5.$ We identify a set of policies that achieve asymptotic zero waiting. The set of policies include several classical policies such as join-the-shortest-queue (JSQ), join-the-idle-queue (JIQ), idle-one-first (I1F) and power-of-$d$-choices (Po$d$) with $d=O(N^\alpha\log N)$. The proof of the main result is based on Stein's method and state space collapse. A key technical contribution of this paper is the iterative state space collapse approach that leads to a simple generator approximation when applying Stein's method.
Dorsal CA1 hippocampal place cells form a multi-scale representation of megaspace

Spatially firing "place cells" within the hippocampal CA1 region form internal maps of the environment necessary for navigation and memory. In rodents, these neurons have been almost exclusively studied in small environments (<4 m2). It remains unclear how place cells encode a very large open 2D environment that is commensurate with the natural environments experienced by rodents and other mammals. Such an ethologically realistic environment would require a complex spatial representation, capable of simultaneously representing space at multiple overlapping fine-to-coarse informational scales. Here, we show that in a "megaspace" (18.6 m2), the majority of dorsal CA1 place cells exhibited multiple place subfields of different sizes, akin to those observed along the septo-temporal axis. Furthermore, the total area covered by the subfields of each cell was not correlated with the number of subfields, and increased with the scale of the environment. The multiple different-sized subfields exhibited by place cells in the megaspace suggest that the ensemble population of subfields form a multi-scale representation of space within the dorsal hippocampus. Our findings point to a new dorsal hippocampus ensemble coding scheme that simultaneously supports navigational processes at both fine- and coarse-grained resolutions. VIDEO ABSTRACT.
Probability density of fractional Brownian motion and the fractional Langevin equation with absorbing walls

Fractional Brownian motion and the fractional Langevin equation are models of anomalous diffusion processes characterized by long-range power-law correlations in time. We employ large-scale computer simulations to study these models in two geometries, (i) the spreading of particles on a semi-infinite domain with an absorbing wall at one end and (ii) the stationary state on a finite interval with absorbing boundaries at both ends and a source in the center. We demonstrate that the probability density and other properties of the fractional Langevin equation can be mapped onto the corresponding quantities of fractional Brownian motion driven by the same noise if the anomalous diffusion exponent $\alpha$ is replaced by $2-\alpha$. In contrast, the properties of fractional Brownian motion and the fractional Langevin equation with reflecting boundaries were recently shown to differ from each other qualitatively. Specifically, we find that the probability density close to an absorbing wall behaves as $P(x) \sim x^\kappa$ with the distance $x$ from the wall in the long-time limit. In the case of fractional Brownian motion, $\kappa$ varies with the anomalous diffusion exponent $\alpha$ as $\kappa=2/\alpha -1$, as was conjectured previously. We also compare our simulation results to a perturbative analytical approach to fractional Brownian motion.
On Accurate and Reliable Anomaly Detection for Gas Turbine Combustors: A Deep Learning Approach

Monitoring gas turbine combustors' health, in particular, early detecting abnormal behaviors and incipient faults, is critical in ensuring gas turbines operating efficiently and in preventing costly unplanned maintenance. One popular means of detecting combustors’ abnormalities is through continuously monitoring exhaust gas temperature profiles. Over the years many anomaly detection technologies have been explored for detecting combustor faults, however, the performance (detection rate) of anomaly detection solutions fielded is still inadequate. Advanced technologies that can improve detection performance are in great need. Aiming for improving anomaly detection performance, in this paper we introduce recently-developed deep learning (DL) in machine learning into the combustors’ anomaly detection application. Specifically, we use deep learning to hierarchically learn features from the sensor measurements of exhaust gas temperatures. And we then use the learned features as the input to a neural network classifier for performing combustor anomaly detection. Since such deep learned features potentially better capture complex relations among all sensor measurements and the underlying combustors’ behavior than handcrafted features do, we expect the learned features can lead to a more accurate and robust anomaly detection. Using the data collected from a real-world gas turbine combustion system, we demonstrated that the proposed deep learning based anomaly detection significantly indeed improved combustors’ anomaly detection performance.Deep learning, one of the breakthrough technologies in machine learning, has attracted tremendous research interests in recent years in the domains such as computer vision, speech recognition and natural language processing.Deep learning, to the best of our knowledge, has not been used for any PHM applications, however. It is our hope that our initial work presented in this paper would shed some light on how deep learning as an advanced machine learning technology can benefit PHM applications and, more importantly, can stimulate more research interests in our PHM community.
HOW THE RICH STAY RICH: USING A FAMILY TRUST COMPANY TO SECURE A FAMILY FORTUNE

This Article is about family trust companies and the role they play in preserving great fortunes. A family trust company is a corporation formed to provide fiduciary services to a related group of people, in contrast to banking institutions established to offer similar services to a larger public. The province of the mega-rich (who remain very much upon the American landscape, the recent economic crisis notwithstanding), these entities have received scant attention from the academic bar. While family trust companies are not new, recent changes in the law in some states have made these entities far easier to create and to operate - much more accessible to wealthy families looking to preserve their fortunes far into the future. To appreciate the significance of the contemporary family trust company, however, we must not only attend to the particulars of these new rules, but we must also examine this entity in situ, as the very wealthy often employ it - as the centerpiece in a megawatt estate plan, the masterstroke in a series of aggressive planning techniques that potentially secure and indeed grow a fortune to benefit a family for untold generations to come. There is also a normative dimension to the family trust company and to those strategies that would employ it to secure the very wealthy in their fortunes. It has long been a commonplace of democratic theory that, while democracy is largely immune to some degree of material difference within a polity, intransigent, radical differences in means are problematic. For this reason, the dissipation of great fortunes has been viewed as salubrious in a democratic polity. For those concerned about the well-being of the American polity, it is then of some moment that, of late, the very wealthy and those who advise them in planning for the inter-generational transfer of assets have focused on this problem of dissipation as the last frontier in the preservation of great fortunes. And the platform that these families are using to redress this problem - their crowning implement - is the family trust company.
Multivariate extensions of isotonic regression and total variation denoising via entire monotonicity and Hardy–Krause variation

We consider the problem of nonparametric regression when the covariate is d dimensional, where d≥1. In this paper, we introduce and study two nonparametric least squares estimators (LSEs) in this setting—the entirely monotonic LSE and the constrained Hardy–Krause variation LSE. We show that these two LSEs are natural generalizations of univariate isotonic regression and univariate total variation denoising, respectively, to multiple dimensions. We discuss the characterization and computation of these two LSEs obtained from n data points. We provide a detailed study of their risk properties under the squared error loss and fixed uniform lattice design. We show that the finite sample risk of these LSEs is always bounded from above by n−2/3 modulo logarithmic factors depending on d; thus these nonparametric LSEs avoid the curse of dimensionality to some extent. We also prove nearly matching minimax lower bounds. Further, we illustrate that these LSEs are particularly useful in fitting rectangular piecewise constant functions. Specifically, we show that the risk of the entirely monotonic LSE is almost parametric (at most 1/n up to logarithmic factors) when the true function is well approximable by a rectangular piecewise constant entirely monotone function with not too many constant pieces. A similar result is also shown to hold for the constrained Hardy–Krause variation LSE for a simple subclass of rectangular piecewise constant functions. We believe that the proposed LSEs yield a novel approach to estimating multivariate functions using convex optimization that avoid the curse of dimensionality to some extent.