cssi/SciSciGPT-SciSciNet huggingface dataset:
Three-dimensional Fermi surface and small effective masses in Mo8Ga41

We report Fermi surface characteristics of Mo8Ga41, a two-gap superconductor with a critical temperature of T c ∼ 10 K, obtained from quantum oscillation measurements. Four major frequencies have been observed with relatively small quasiparticle masses. The angular dependence of major frequencies indicates three-dimensional Fermi surface sheets. This argues for a relatively isotropic superconducting state and, given its relatively high Tc, shows that a search for materials in this class could be of interest for superconducting wire applications.
Conformal symmetry breaking and thermodynamics of near-extremal black holes

It has been argued recently by Almheiri and Polchinski that the near-horizon conformal symmetry of extremal black holes must be broken due to gravitational backreaction at an IR scale linear in G N . In this paper, we show that this scale coincides with the so-called ‘thermodynamic mass gap’ of near-extremal black holes, a scale which signals the breakdown of their thermodynamic description. We also develop a method which extends the analysis of Almheiri and Polchinski to more complicated models with extremal throats by studying the bulk linearized quantum field theory. Moreover, we show how their original model correctly captures the universal physics of the near-horizon region of near-extremal black holes at tree level, and conclude that this equivalence of the conformal breaking and mass gap scale is general.
Feeding your inflaton: Non-Gaussian signatures of interaction structure

Primordial non-Gaussianity is generated by interactions of the inflaton field, either self-interactions or couplings to other sectors. These two physically different mechanisms can lead to nearly indistinguishable bispectra of the equilateral type, but generate distinct patterns in the relative scaling of higher order moments. We illustrate these classes in a simple effective field theory framework where the flatness of the inflaton potential is protected by a softly broken shift symmetry. Since the distinctive difference between the two classes of interactions is the scaling of the moments, we investigate the implications for observables that depend on the series of moments. We obtain analytic expressions for the Minkowski functionals and the halo mass function for an arbitrary structure of moments, and use these to demonstrate how different classes of interactions might be distinguished observationally. Our analysis casts light on a number of theoretical issues, in particular we clarify the difference between the physics that keeps the distribution of fluctuations nearly Gaussian, and the physics that keeps the calculation under control.
THE OLD, SUPER-METAL-RICH OPEN CLUSTER, NGC 6791—ELEMENTAL ABUNDANCES IN TURN-OFF STARS FROM KECK/HIRES SPECTRA

The study of star clusters has advanced our understanding of stellar evolution, Galactic chemical evolution, and nucleosynthesis. Here we investigate the composition of turn-off stars in the intriguing open cluster, NGC 6791, which is old, but super-metal-rich with high-resolution (R = 46,000) Keck/HIRES spectra. We find [Fe/H] = +0.30 ± 0.02 from measurements of some 40 unblended, unsaturated lines of both Fe I and Fe II in eight turn-off stars. Our O abundances come from the O I triplet near 7774 A and we perform a differential analysis relative to the Sun from our Lunar spectrum also obtained with Keck/HIRES. The O results are corrected for small nLTE effects. We find consistent ratios of [O/Fe]{sub n} with a mean of –0.06 ± 0.02. This is low with respect to field stars that are also both old and metal-rich and continue the trend of decreasing [O/Fe] with increasing [Fe/H]. The small range in our oxygen abundances is consistent with a single population of stars. Our results for the alpha elements [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe] are near solar and compare well with those of the old, metal-rich field stars. The two Fe-peak elements, Cr and Ni, are consistent with Fe. These turn-off-star abundances provide benchmark abundances tomore » investigate whether there are any observable abundance differences with the giants that might arise from nuclear-burning and dredge-up processes. Determinations of upper limits were found for Li by spectrum synthesis and are consistent with the upper limits in similar stars in the relatively old, super-metal-rich cluster NGC 6253. Our results support the prediction from standard theory that higher-metallicity stars deplete more Li. Probably no stars in NGC 6791 have retained their initial Li.« less
Relativistic Diskoseismology. I. Analytical Results for “Gravity Modes”

We generalize previous calculations to a fully relativistic treatment of adiabatic oscillations that are trapped in the inner regions of accretion disks by non-Newtonian gravitational effects of a black hole. We employ the Kerr geometry within the scalar potential formalism of Ipser and Lindblom, neglecting the gravitational field of the disk. This approach treats perturbations of arbitrary stationary, axisymmetric, perfect fluid models. It is applied here to thin accretion disks. Approximate analytic eigenfunctions and eigenfrequencies are obtained for the most robust and observable class of modes, which corresponds roughly to the gravity (internal) oscillations of stars. The dependence of the oscillation frequencies on the mass and angular momentum of the black hole is exhibited. These trapped modes do not exist in Newtonian gravity, and thus provide a signature and probe of the strong-field structure of black holes. Our predictions are relevant to observations that could detect modulation of the X-ray luminosity from stellar mass black holes in our Galaxy and the UV and optical luminosity from supermassive black holes in active galactic nuclei.
Interpreting the electron EDM constraint

The ACME collaboration has recently announced a new constraint on the electron EDM, |de| < 1.1 × 10−29e cm, from measurements of the ThO molecule. This is a powerful constraint on CP-violating new physics: even new physics generating the EDM at two loops is constrained at the multi-TeV scale. We interpret the bound in the context of different scenarios for new physics: a general order-of-magnitude analysis for both the electron EDM and the CP-odd electron-nucleon coupling; 1-loop SUSY, probing sleptons above 10 TeV; 2-loop SUSY, probing multi-TeV charginos or stops; and finally, new physics that generates the EDM via the charm quark or top quark Yukawa couplings. In the last scenario, new physics generates a “QULE operator” $$ \left({q}_f{\overline{\sigma}}^{\mu \nu }{\overline{u}}_f\right)\kern0.5em \cdotp \kern0.5em \left(\ell {\overline{\sigma}}_{\mu \nu}\overline{e}\right) $$ , which in turn generates the EDM through RG evolution. If the QULE operator is generated at tree level, this corresponds to a previously studied leptoquark model. For the first time, we also classify scenarios in which the QULE operator is generated at one loop through a box diagram, which include (among others) SUSY and leptoquark models. The electron EDM bound is the leading constraint on a wide variety of theories of CP-violating new physics interacting with the Higgs boson or the top quark. We argue that any future nonzero measurement of an electron EDM will provide a strong motivation for constructing new colliders at the highest feasible energies.
Global existence of strong solutions to a groundwater flow problem

In this paper, we study the initial boundary value problem for the system $$\Delta v= u_{x_1},\ u_t-\text{ div }\left( \left( (a|{\mathbf {q}}|+m)I+(b-a)\frac{{\mathbf {q}}\otimes {\mathbf {q}}}{|{\mathbf {q}}|}\right) \nabla u\right) =-\nabla u\cdot {\mathbf {q}}$$ , where $${\mathbf {q}}=(-v_{x_2}, v_{x_1})^{\mathrm{T}}, {\mathbf {q}}\otimes {\mathbf {q}}={\mathbf {q}}{\mathbf {q}}^{\mathrm{T}}$$ . This problem has been proposed as a model for a fluid flowing through a porous medium under the influence of gravity and hydrodynamic dispersion. For each $$T>0$$ , we obtain a so-called strong solution (v, u) in the function space $$L^\infty (0,T; \left( W^{1,\infty }(\Omega )\right) ^2)$$ , where $$\Omega $$ is a bounded domain in $${\mathbb {R}}^2$$ . The key ingredient in our approach is the decomposition $$A^2=\text{ tr } (A)A-\text{ det }(A) I$$ for any $$2\times 2$$ symmetric matrix A. By exploring this decomposition, we are able to derive an equation of parabolic type for the function $$\left( \left( (a|{\mathbf {q}}|+m)I+(b-a)\frac{{\mathbf {q}}\otimes {\mathbf {q}}}{|{\mathbf {q}}|}\right) \nabla u\cdot \nabla u\right) ^j, j\ge 1$$ . With the aid of this equation, we obtain a uniform bound for $$\nabla u$$ .
Global consensus of multi‐agent systems with intermittent directed communication in the presence of actuator saturation

This paper studies the global leader-following consensus problem for a multi-agent system with intermittent directed communication in the presence of actuator saturation. Both the follower agents and the leader agent are described by a chain of integrators of an arbitrary length. A bounded consensus algorithm is constructed for each follower agent which utilizes the information obtained from the communication network intermittently. Global leader-following consensus is achieved by the consensus algorithms when the communication topology among all agents, when active, contains a spanning tree rooted at the leader agent. Simulation results illustrate the theoretical conclusions.
Improved measurement of the 'head-tail' effect in nuclear recoils

We present new results with a prototype detector that is being developed by the DMTPC collaboration for the measurement of the direction tag ('head-tail') of dark matter wind. We use neutrons from a 252Cf source to create low-momentum nuclear recoils in elastic scattering with the residual gas nuclei. The recoil track is imaged in low-pressure time-projection chamber with optical readout. We measure the ionization rate along the recoil trajectory, which allows us to determine the direction tag of the incoming neutrons.
Relative merits of phononics vs. plasmonics: the energy balance approach

The common feature of various plasmonic schemes is their ability to confine optical fields of surface plasmon polaritons (SPPs) into sub-wavelength volumes and thus achieve a large enhancement of linear and nonlinear optical properties. This ability, however, is severely limited by the large ohmic loss inherent to even the best of metals. However, in the mid and far infrared ranges of the spectrum there exists a viable alternative to metals, polar dielectrics and semiconductors in which dielectric permittivity (the real part) turns negative in the Reststrahlen region. This feature engenders the so-called surface phonon polaritons (SPhPs) capable of confining the field in a way akin to their plasmonic analogues, the SPPs. Since the damping rate of polar phonons is substantially less than that of free electrons, it is not unreasonable to expect that phononic devices may outperform their plasmonic counterparts. Yet a more rigorous analysis of the comparative merits of phononics and plasmonics reveals a more nuanced answer, namely that while phononic schemes do exhibit narrower resonances and can achieve a very high degree of energy concentration, most of the energy is contained in the form of lattice vibrations so that enhancement of the electric field, and hence the Purcell factor, is rather small compared to what can be achieved with metal nanoantennas. Still, the sheer narrowness of phononic resonances is expected to make phononics viable in applications where frequency selectivity is important.
Geometry-Informed Material Recognition

Our goal is to recognize material categories using images and geometry information. In many applications, such as construction management, coarse geometry information is available. We investigate how 3D geometry (surface normals, camera intrinsic and extrinsic parameters) can be used with 2D features (texture and color) to improve material classification. We introduce a new dataset, GeoMat, which is the first to provide both image and geometry data in the form of: (i) training and testing patches that were extracted at different scales and perspectives from real world examples of each material category, and (ii) a large scale construction site scene that includes 160 images and over 800,000 hand labeled 3D points. Our results show that using 2D and 3D features both jointly and independently to model materials improves classification accuracy across multiple scales and viewing directions for both material patches and images of a large scale construction site scene.
Tori detect invertibility of topological field theories

A once-extended d-dimensional topological field theory Z is a symmetric monoidal functor (taking values in a chosen target symmetric monoidal (infty,2)-category) assigning values to (d-2)-manifolds, (d-1)-manifolds, and d-manifolds. We show that if Z is at least once-extended and the value assigned to the (d-1)-torus is invertible, then the entire topological field theory is invertible, that is it factors through the maximal Picard infty-category of the target. Results are obtained in the presence of arbitrary tangential structures.
Geolocation with FDOA measurements via polynomial systems and RANSAC

The problem of geolocation of a radio-frequency transmitter via time difference of arrival (TDOA) and frequency difference of arrival (FDOA) is given as a system of polynomial equations. This allows for the use of homotopy continuation-based methods from numerical algebraic geometry. A novel geolocation algorithm employs numerical algebraic geometry techniques in conjunction with the random sample consensus (RANSAC) method. This is all developed and demonstrated in the setting of only FDOA measurements, without loss of generality. Additionally, the problem formulation as polynomial systems immediately provides lower bounds on the number of receivers or measurements required for the solution set to consist of only isolated points.
NONLINEAR REALIZATIONS OF SUPERSYMMETRY AND OTHER SYMMETRIES

Simultaneous nonlinear realizations of spontaneously broken supersymmetry in conjunction with other spontaneous and/or explicitly broken symmetries including R symmetry, global chiral symmetry, dilatations and the superconformal symmetries is reviewed.
Symmetric Fermion Mass Generation as Deconfined Quantum Criticality

Author(s): You, YZ; He, YC; Xu, C; Vishwanath, A | Abstract: Massless (2+1)D Dirac fermions arise in a variety of systems from graphene to the surfaces of topological insulators, where generating a mass is typically associated with breaking a symmetry. However, with strong interactions, a symmetric gapped phase can arise for multiples of eight Dirac fermions. A continuous quantum phase transition from the massless Dirac phase to this massive phase, which we term symmetric mass generation, is necessarily beyond the Landau paradigm and is hard to describe even at the conceptual level. Nevertheless, such transition has been consistently observed in several numerical studies recently. Here, we propose a theory for the symmetric mass generation transition which is reminiscent of deconfined criticality and involves emergent non-Abelian gauge fields coupled both to Dirac fermions and to critical Higgs bosons. We motivate the theory using an explicit parton construction and discuss predictions for numerics. Additionally, we show that the fermion Green's function is expected to undergo a zero-to-pole transition across the critical point.
High performance non-binary spatially-coupled codes for flash memories

Modern dense Flash memory devices operate at very low error rates, which require powerful error correcting coding (ECC) techniques. An emerging class of graph-based ECC techniques that has broad applications is the class of spatially-coupled (SC) codes, where a block code is partitioned into components that are then rewired multiple times to construct an SC code. Here, our focus is on SC codes with the underlying circulant-based structure. In this paper, we present a three-stage approach for the design of high performance non-binary SC (NB-SC) codes optimized for practical Flash channels; we aim at minimizing the number of detrimental general absorbing sets of type two (GASTs) in the graph of the designed NB-SC code. In the first stage, we deploy a novel partitioning mechanism, called the optimal overlap partitioning, which acts on the protograph of the SC code to produce optimal partitioning corresponding to the smallest number of detrimental objects. In the second stage, we apply a new circulant power optimizer to further reduce the number of detrimental GASTs. In the third stage, we use the weight consistency matrix framework to manipulate edge weights to eliminate as many as possible of the GASTs that remain in the NB-SC code after the first two stages (that operate on the unlabeled graph of the code). Simulation results reveal that NB-SC codes designed using our approach outperform state-of-the-art NB-SC codes when used over Flash channels.
Finite rigid sets in arc complexes

For any compact, connected, orientable, finite-type surface with marked points other than the sphere with three marked points, we construct a finite rigid set of its arc complex: a finite simplicial subcomplex of its arc complex such that any locally injective map of this set into the arc complex of another surface with arc complex of the same or lower dimension is induced by a homeomorphism of the surfaces, unique up to isotopy in most cases. It follows that if the arc complexes of two surfaces are isomorphic, the surfaces are homeomorphic. We also give an exhaustion of the arc complex by finite rigid sets. This extends the results of Irmak and McCarthy (Turkish J. Math. 34 (2010) 339–354).
Morphological complexity of protostellar envelopes

Extinction maps at 8μm from the Spitzer Space Telescope show that many Class 0 protostars exhibit complex, irregular, and non-axisymmetric structure within the densest regions of their dusty envelopes. Many of the systems have highly irregular and non-axisymmetric morphologies on scales ~1000 AU, with a quarter of the sample exhibiting filamentary or flattened dense structures. Complex envelope structure is observed in regions spatially distinct from outflow cavities, and the densest structures often show no systematic alignment perpendicular to the cavities. We suggest that the observed envelope complexity is the result of collapse from protostellar cores with initially non-equilibrium structures. The striking non-axisymmetry in many envelopes could provide favorable conditions for the formation of binary systems. We then show that the kinematics around L1165 as probed with N 2 H + are indicative of asymmetric infall; the velocity gradient is not perpendicular to the outflow.
Gradient Boosting Decision Tree Algorithm for the Prediction of Postoperative Intraocular Lens Position in Cataract Surgery

Purpose To develop a method for predicting postoperative anterior chamber depth (ACD) in cataract surgery patients based on preoperative biometry, demographics, and intraocular lens (IOL) power. Methods Patients who underwent cataract surgery and had both preoperative and postoperative biometry measurements were included. Patient demographics and IOL power were collected from the Sight Outcomes Research Collaborative (SOURCE) database. A gradient-boosting decision tree model was developed to predict the postoperative ACD. The mean absolute error (MAE) and median absolute error (MedAE) were used as evaluation metrics. The performance of the proposed method was compared with five existing formulas. Results In total, 847 patients were assigned randomly in a 4:1 ratio to a training/validation set (678 patients) and a testing set (169 patients). Using preoperative biometry and patient sex as predictors, the presented method achieved an MAE of 0.106 ± 0.098 (SD) on the testing set, and a MedAE of 0.082. MAE was significantly lower than that of the five existing methods (P < 0.01). When keratometry was excluded, our method attained an MAE of 0.123 ± 0.109, and a MedAE of 0.093. When IOL power was used as an additional predictor, our method achieved an MAE of 0.105 ± 0.091 and a MedAE of 0.080. Conclusions The presented machine learning method achieved greater accuracy than previously reported methods for the prediction of postoperative ACD. Translational Relevance Increasing accuracy of postoperative ACD prediction with the presented algorithm has the potential to improve refractive outcomes in cataract surgery.
Uniform bounds for periods of endomorphisms of varieties

Abstract Suppose X is a variety defined over a finite extension K of Q p and suppose X admits a model X defined over the ring of integers R of K. Let f : X → X be an endomorphism of X defined over K that can be extended to an endomorphism of X defined over R. We apply a method of Fakhruddin to prove an explicit upper bound for the primitive period of periodic points defined over R.
Reward modulates cortical representations of action.

Abstract People are capable of rapid improvements in performance when they are offered a reward. The neural mechanism by which this performance enhancement occurs remains unclear. We investigated this phenomenon by offering people monetary reward for successful performance in a sequence production task. We found that people performed actions more quickly and accurately when they were offered large reward. Increasing reward magnitude was associated with elevated activity throughout the brain prior to movement. Multivariate patterns of activity in these reward-responsive regions encoded information about the upcoming action. Follow-up analyses provided evidence that action decoding in pre-SMA and other motor planning areas was improved for large reward trials and successful action decoding in SMA was associated with improved performance. These results suggest that reward may enhance performance by enhancing neural representations of action used in motor planning.
Persistence time of solutions of the three-dimensional Navier-Stokes equations in Sobolev-Gevrey classes

Abstract In this paper, we study existence times of strong solutions of the three-dimensional Navier-Stokes equations in time-varying analytic Gevrey classes based on Sobolev spaces H s , s > 1 2 . This complements the seminal work of Foias and Temam (1989) [26] on H 1 based Gevrey classes, thus enabling us to improve estimates of the analyticity radius of solutions for certain classes of initial data. The main thrust of the paper consists in showing that the existence times in the much stronger Gevrey norms (i.e. the norms defining the analytic Gevrey classes which quantify the radius of real-analyticity of solutions) match the best known persistence times in Sobolev classes. Additionally, as in the case of persistence times in the corresponding Sobolev classes, our existence times in Gevrey norms are optimal for 1 2 s 5 2 .
Exploring valence bias as a metric for frontoamygdalar connectivity and depressive symptoms in childhood.

Negativity bias is a core feature of depression that is associated with dysfunctional frontoamygdalar connectivity; this pathway is associated with emotion regulation and sensitive to neurobiological change during puberty. We used a valence bias task (ratings of emotional ambiguity) as a potential early indicator of depression risk and differences in frontoamygdalar connectivity. Previous work using this task demonstrated that children normatively have a negative bias that attenuates with maturation. Here, we test the hypothesis that persistence of this negativity bias as maturation ensues may reveal differences in emotion regulation development, and may be associated with increased risk for depression. In children aged 6-13 years, we tested the moderating role of puberty on relationships between valence bias, depressive symptoms, and frontoamygdalar connectivity. A negative bias was associated with increased depressive symptoms for those at more advanced pubertal stages (within this sample) and less regulatory frontoamygdalar connectivity, whereas a more positive bias was associated with more regulatory connectivity patterns. These data suggest that with maturation, individual differences in positivity biases and associated emotion regulation circuitry confer a differential risk for depression. Longitudinal work is necessary to determine the directionality of these effects and explore the influence of early life events.
Measuring Node Contribution to Community Structure With Modularity Vitality

Community-aware centrality is an emerging research area in network science concerned with the importance of nodes in relation to community structure. Measures are a function of a network's structure and a given partition. Previous approaches extend classical centrality measures to account for community structure with little connection to community detection theory. In contrast, we propose cluster-quality vitality measures, i.e., modularity vitality, a community-aware measure which is well-grounded in both centrality and community detection theory. Modularity vitality quantifies positive and negative contributions to community structure, which indicate a node's role as a community bridge or hub. We derive a computationally efficient method of calculating modularity vitality for all nodes in $O(M+NC)$ time, where $C$ is the number of communities. We systematically fragment networks by removing central nodes, and find that modularity vitality consistently outperforms existing community-aware centrality measures. We show measures well-grounded in community theory are over 8 times more effective on a million-node infrastructure network. This result does not generalize to social media communication networks, which exhibit extreme robustness to all community-aware centrality attacks. This robustness suggests that user-based interventions to mitigate misinformation diffusion will be ineffective. Finally, we demonstrate that modularity vitality provides a new approach to community-deception.
TFP during a credit crunch

Abstract The financial crisis of 2008 was followed by sharp contractions in aggregate output and employment and an unusual increase in aggregate total factor productivity (TFP). This paper attempts to explain these facts by modeling the creation and destruction of jobs in the presence of heterogeneity in firm productivity and frictional credit and labor markets. The aggregate level of TFP is determined by both the underlying distribution of firm productivity and the structures of the credit and labor markets. Adverse shocks to credit markets destroy the least productive jobs and slow job creation, thus raising aggregate TFP and unemployment, and reducing output.
Crime, Punishment, and Politics: An Analysis of Political Cycles in Criminal Sentencing

Abstract We present evidence that Washington State judges respond to political pressure by sentencing serious crimes more severely. Sentences are around 10% longer at the end of a judge's political cycle than at the beginning; judges' discretionary departures above the sentencing guidelines range increase by 50% across the electoral cycle, accounting for much of the greater severity. Robustness specifications, nonlinear models, and falsification exercises allow us to distinguish among explanations for increased sentencing severity at the end of judges' political cycles. Our findings inform debates over judicial elections, and highlight the interaction between judicial discretion and the influence of judicial elections.
Corporate financial and investment policies when future financing is not frictionless

Abstract We study a model in which future financing constraints lead firms to have a preference for investments with shorter payback periods, investments with less risk, and investments that utilize more pledgeable assets. The model also shows how investment distortions towards more liquid, safer assets vary with the marginal cost of external financing and with firm internal cash flows. Our theory helps reconcile and interpret a number of patterns reported in the empirical literature, in areas such as risk-taking behavior, capital structure choices, hedging strategies, and cash management policies. For example, contrary to Jensen and Meckling [Jensen, M., Meckling, W., 1976. Theory of the Firm: managerial behavior, agency costs, and ownership structure. Journal of Financial Economics 305–360], we show that firms may reduce rather than increase risk when leverage increases exogenously. Furthermore, firms in economies with less developed financial markets will not only take different quantities of investment, but will also take different kinds of investment (safer, short-term projects that are potentially less profitable). We also point out to several predictions that have not been empirically examined. For example, our model predicts that investment safety and liquidity are complementary: constrained firms are specially likely to decrease the risk of their most liquid investments.
NATIONAL DEFENSE, OIL IMPORTS, AND BIO‐ENERGY TECHNOLOGY

Terrorist disruptions of crude oil supplies anywhere in the world now pose a serious threat to the U.S. economy. Price shocks from terrorist acts could have a pervasive negative effect on producer costs and consumer behavior, with the potential to derail the current eco-nomic recovery. The authors pro-pose insulating U.S. energy prices from world price volatility by gradu-ally eliminating imports of crude oil from non-Western Hemisphere sources. The U.S. now operates with half of its crude supply from offshore sources. As much as half of these imports could be replaced by ex-panded production from projects that have been shelved for political reasons or because prices are cur-rently too low. The remainder could come from an extensive and cur-rently untapped supply of crude oil substitutes, particularly bio-energy sources such as ethanol from corn and switchgrass. These sources would be much less vulnerable to terrorist disruption. The authors also argue that the expected costs of pursuing a strat-egy of eliminating imports would not be nearly as large as the con-ventional wisdom suggests. Even though crude prices would be some-what higher than current levels, they would also be much more stable, and this price stability would help promote a stronger and more secure economy in the long run.
A General Option Valuation Approach to Discount for Lack of Marketability

A general option-based approach to estimating the discount for lack of marketability is offered. It is general enough to capture maturity, volatility, hedging availability, and investor skill, as well as other important factors. The model is shown to contain several option-based models as special cases. The model also contains two weighting variables that provide valuation professionals much needed flexibility in addressing the unique challenges of each nonmarketable valuation assignment. Selected prior empirical results are reinterpreted with this approach.
Mass probation: Toward a more robust theory of state variation in punishment

Scholarship on the expansion of the U.S. carceral state has primarily focused on imprisonment rates. Yet the majority of adults under formal criminal justice control are on probation, an "alternative" form of supervision. This article develops the concept of mass probation and builds a typology of state control regimes that theorizes both the scale and type of punishment states employ. Drawing on Bureau of Justice Statistics data from 1980 and 2010, I analyze whether mass probation developed in the same places, affecting the same demographic groups and driven by the same criminal justice trends, as mass imprisonment. The results show that mass probation was a unique state development, expanding in unusual places like Minnesota and Washington. The conclusions argue for a reimagining of the causes and consequences of the carceral state to incorporate the expansion of probation.
Assessing Professionalism: Measuring Progress in the Formation of an Ethical Professional Identity

The Carnegie Foundation's 2007 study of legal education, Educating Lawyers: Preparation for the Practice of Law, observes that "Across the otherwise disparate-seeming educational experiences of seminary, medical school, nursing school, engineering school, and law school, [we] identified a common goal: professional education aims to initiate novice practitioners to think, to perform, and to conduct themselves (that is to act morally and ethically) like professionals." This article focuses on the third goal of legal education - to help law students to conduct themselves morally and ethically as professionals. Carnegie calls this the apprenticeship of professional identity formation or the apprenticeship of professionalism. This essay outlines why a clear definition of professionalism is important, and notes the failure of scholarship in both law and medicine to provide a clear definition. The article proposes a definition consisting of five elements of an ethical professional identity. The article then provides criteria by which measures to assess the professionalism of a student or practicing lawyer should be evaluated, and then applies those criteria to current tools we have available to assess student and practicing lawyer professionalism. The article recommends the development of new professionalism assessment tools tailored specifically for the legal profession.
Labor Force Participation and Monetary Policy in the Wake of the Great Recession

In this paper, we provide compelling evidence that cyclical factors account for the bulk of the post-2007 decline in the U.S. labor force participation rate. We then proceed to formulate a stylized New Keynesian model in which labor force participation is essentially acyclical during "normal times" (that is, in response to small or transitory shocks) but drops markedly in the wake of a large and persistent aggregate demand shock. Finally, we show that these considerations can have potentially crucial implications for the design of monetary policy, especially under circumstances in which adjustments to the short-term interest rate are constrained by the zero lower bound.
Of PhDs, Pirates and the Public: Three-Dimensional Printing Technology and the Arts

The confluence of three-dimensional printing, three-dimensional scanning, and the Internet will erode the dividing line between the physical and the digital worlds and will bring millions of laypeople into intimate contact with the full spectrum of intellectual property laws. One of the areas most affected by 3D printers will be three-dimensional art. This Article analyzes several ways in which 3D printing technology will affect the creation, delivery, and consumption of art. Not only does 3D printing offer great promise for creative works, but it also presents a problem of piracy that may accompany the digitization of three-dimensional works. As 3D printing technology’s relationship to intellectual property law is largely unexplored, this Article explores foundational issues regarding how copyright law applies to 3D printing technology, laying the groundwork upon which further analysis of 3D printing’s effects on copyright law may be built.
The Law and Economics of Hedge Funds: Financial Innovation and Investor Protection

A persistent theme underlying contemporary debates about financial regulation is how to protect investors from the growing complexity of financial markets, new risks, and other changes brought about by financial innovation. Increasingly relevant to this debate are the leading innovators of complex investment strategies known as hedge funds. A hedge fund is a private investment pool not subject to the full range of restrictions on investment activities and disclosure obligations imposed by the federal securities laws, that compensates management in part with an annual performance fee, and typically engages in the active trading of financial instruments. Hedge funds engage in financial innovation by pursuing novel investment strategies that lower market risk (beta) and may increase returns attributable to manager skill (alpha). Despite the funds’ unique costs and risk properties, the historical performance of hedge funds suggests that the ultimate result of hedge fund innovation is to help investors reduce economic losses during market downturns. In 2008, as losses from the U.S. mortgage market transformed to an international financial crisis, global equities dropped 42 percent while hedge funds worldwide lost a comparatively smaller 19 percent for their investors. By increasing investors’ ability to maximize risk-adjusted returns, hedge funds advance the same goal that federal investor protection regulation seeks to advance. This Article shows that the economic outcomes attained by hedge funds are in part attributable to the legal regime under which they operate. The hedge fund legal regime includes not only federal securities law but also the entity and contract law provisions governing the fund, its manager, and investors. Federal law applicable to hedge funds enables the funds to pursue innovative investment strategies employing the trifecta of leverage, short sales, and derivatives. The entity and contract law governance of hedge funds provides high-powered incentives for fund managers to engage in and capture the gains from financial innovation while maintaining a relatively healthy balance between risk taking and risk management. A general lesson from the law and economics of hedge funds is that when a legal regime permits financial intermediaries to be flexible in their investment strategies and aligns the incentives of investors and innovators through performance fees and co-investment by managers, financial innovation is likely to complement investor protection without wideranging regulation. The role of the funds in advancing the same goal as investor protection suggests that they should legally be available to a broader class of investors.
Military Lawyering at the Edge of the Rule of Law at Guantanamo: Should Lawyers Be Permitted to Violate the Law?

“Where were the lawyers?” is the familiar refrain in the legal profession’s reflection on various corporate scandals. What is the legal and moral obligation of lawyers who have knowledge of ongoing illegality and criminal behavior of their clients? What should or must those lawyers do? What about government lawyers who have knowledge of such behavior? This Article considers that question in the context of military lawyers at Guantanamo—those lawyers with direct knowledge of the treatment of prisoners at Guantanamo, treatment criticized throughout the world as violative of fundamental principles of international law. In essence, where were the lawyers for the government and for individual detainees when the government began to violate the most fundamental norms of the rule of law? This Article discusses the proud history of several military lawyers at Guantanamo who consistently demonstrated an unwavering commitment to the Constitution and to the rule of law. They were deeply offended about the actions of the government they served as it
Wong Kim Ark and Sentencia que Declara Constitucional La Ley General de Migración 285-04 in Comparative Perspective: Constitutional Interpretation, Jus Soli Principles, and Political Morality

ion, a theory.""' Bickel's point, very legitimate and unfortunately born out by the history of this country, is that it is far easier to see an individual as a person than a "citizen," and by necessity, far easier to think of someone as a non-citizen than a
INTERNATIONAL TRADE AND THE BUSINESS CYCLE

This paper develops a new empirical framework for analysing the dynamics of the trade balance in response to different types of macroeconomic shocks. The model provides a synthetic perspective on the conditional correlations between the business cycle and the trade balance that are generated by different shocks and attempts to reconcile these results with unconditional correlations found in the data. The results suggest that, in the post-Bretton Woods period, nominal shocks have been an important determinant of the forecast error variance for fluctuations in the trade balance in G-7 countries. The world economy has become increasingly integrated in recent years, spurred by rapid expansions in trade and financial flows across national borders. The rising share of international trade in world output suggests that trade could potentially have a greater influence on business cycle fluctuations, both within and across countries. Hence, understanding the factors driving fluctuations in international trade is important from a number of different perspectives, including macroeconomic forecasting as well as for short-run domestic policy considerations and international policy coordination. The existing empirical literature on international aspects of business cycle fluctuations has followed a number of different approaches. One strand of literature uses error component models to identify the sources of business cycle fluctuations and to assess the importance of common international shocks relative to country-specific or industry-specific shocks (see Stockman, 1988; Glick and Rogoff, 1995). Another approach has been to document the role of international trade in the transmission of business cycles across countries (as in
Setting Congress Up to Fail

In Shelby County v. Holder the Supreme Court invalidated key provisions of the Voting Rights Act of 1965 based on Congress’s failure to justify the formula used to determine which jurisdictions would be subject to the Act’s pre-clearance requirement of submitting all changes to voting procedures to the Justice Department for prior approval. This short essay explores one problematic feature of the Court’s analysis: its refusal to consider the legislative record as adequate because it was created to justify the coverage formula after the fact, rather than to facilitate deliberation on the coverage formula before a decision had been made. This reasoning essentially imports from administrative law a rule called the Chenery principle, and as this essay explains, it does so without justification. The differences between administrative and legislative decision making processes compel different treatment by the courts, and treating legislative records like administrative ones, in essence, asks of Congress something it is institutionally ill-equipped to perform. It sets Congress up to fail.
Evidence on the Usefulness of Capital Expenditures as an Alternative Measure of Depreciation

Investment professionals often suggest that accounting earnings is a more useful indicator of share value if adjusted by substituting current capital expenditures for reported depreciation. We investigate the usefulness of this alternative depreciation measure by comparing the ability of reported earnings and adjusted earnings to explain the cross-sectional distribution of stock prices for a large sample of manufacturing firms. We find that adjusted earnings explains a much smaller fraction of the variation in share prices than earnings based on reported depreciation, and provide evidence on the reasons for this difference.
Search Engine Optimization: What Drives Organic Traffic to Retail Sites?

The lion's share of retail traffic through search engines originates from organic (natural) rather than sponsored (paid) links. We use a dataset constructed from over 12,000 search terms and 2 million users to identify drivers of the organic clicks that the top 759 retailers received from search engines in August 2012. Our results are potentially important for search engine optimization (SEO). We find that a retailer's investments in factors such as the quality and brand awareness of its site increases organic clicks through both a direct and an indirect effect. The direct effect stems purely from consumer behavior: The higher the quality of an online retailer, the greater the number of consumers who click its link rather than a competitor in the list of organic results. The indirect effect stems from our finding that search engines tend to place higher quality sites in better positions, which results in additional clicks because consumers tend to click links in more favorable positions. We also find that consumers who are older, wealthier, conduct searches from work, use fewer words, or include a brand name product in their search are more likely to click a retailer's organic link following a product search. Finally, the quality of a retailer's site appears to be especially important in attracting organic traffic from individuals with higher incomes. The beneficial direct and indirect effects of an online retailer's brand equity on organic clicks, coupled with the spillover effects on traffic through other online and traditional channels, leads us to conclude that investments in the quality and brand awareness of a site should be included as part of an SEO strategy.
Mitigating Estimation Risk in Asset Allocation: Diagonal Models Versus 1/N Diversification

Recent literature suggests that optimal asset-allocation models struggle to consistently outperform the 1/N naive diversification strategy, which highlights estimation-risk concerns. We propose a dichotomous classification of asset-allocation models based on which elements of the inverse covariance matrix that a model uses: diagonal only versus full matrix. We argue that parsimonious diagonal-only strategies, which use limited information such as volatility or idiosyncratic volatility, are likely to offer a good tradeoff between incorporating limited information while mitigating estimation risk. Evaluating five sets of portfolios over 1926–2012, we find that 1/N is generally not optimal when compared with these diagonal strategies.
Monetary policy and sectoral shocks : did the Federal Reserve react properly to the high-tech crisis?

The authors present an identification strategy that allows them to study the sectoral effects of monetary policy and the role that monetary policy plays in the transmission of sectoral shocks. They apply their methodology to the case of the United States and find some significant differences in the sectoral responses to monetary policy. They also find that monetary policy is a significant source of sectoral transfers. In particular, a shock to equipment and software investment, which one identifies with the high-tech crisis, induces a response by the monetary authority that generates a temporary boom in residential investment and durables consumption but has almost no effect on the high-tech sector. Finally, the authors perform an exercise evaluating the model's predictions about the automatic and more aggressive monetary policy response to a shock similar to the one that hit the United States in early 2001. They find that the actual drop in interest rates is in line with the predictions of the model.
Reforming public pensions in the US and the UK

This essay describes the current debate on reforming Social Security in the US, along with a brief description of how the programme works. Along the way it comments on the quality of some reform proposals as well as their political standing. Where issues are similar, some inferences are drawn for the UK. While the focus of this essay is the political debate, the debate and my analysis do draw on the academic literature, which is not surprising since academics have played a number of roles in the debate, making reform proposals, being on and staffing the commission appointed by President Bush, and working for the Bush administration. Each year the Office of the Actuary of Social Security prepares a projection of the finances of the system for the next 75 years (Board of Trustees, 2005). The Office also does projections for reform proposals. Despite the presence of three cabinet members among the five Trustees who have the power to set the economic and demographic assumptions, the projections have wide acceptance and are viewed as coming from widely-respected civil servants, not the cabinet members officially in charge. They play a key role in the political process, although recently the Congressional Budget Office has started doing projections as well (Congressional Budget Office, 2005).