cssi/SciSciGPT-SciSciNet huggingface dataset:
DeepNav: Learning to Navigate Large Cities

We present DeepNav, a Convolutional Neural Network (CNN) based algorithm for navigating large cities using locally visible street-view images. The DeepNav agent learns to reach its destination quickly by making the correct navigation decisions at intersections. We collect a large-scale dataset of street-view images organized in a graph where nodes are connected by roads. This dataset contains 10 city graphs and a total of more than 1 million street-view images. We propose 3 supervised learning approaches for the navigation task, and show how A* search in the city graph can be used to generate labels for the images. Our annotation process is fully automated using publicly available mapping services, and requires no human input. We evaluate the proposed DeepNav models on 4 held-out cities for navigating to 5 different types of destinations and show that our algorithms outperform previous work that uses hand-crafted features and Support Vector Regression (SVR) [19].
THE MULTIPLY OPERATED PATIENT: A LONG DAY'S JOURNEY INTO NIGHT

Despite our best efforts, occasionally, certain patients will have multiply operated, failed reconstructions after TKA. There are situations where further attempts at arthroplasty are unwise, for example, chronic infections with multiple failed staged reconstructions. A careful preoperative evaluation of the patient is critical to guide decision-making. An assessment of medical comorbidity, functional demands, and expectations is important. Regarding the extremity, the severity of bone loss, soft tissue defects, ligamentous competency, and neurovascular status is important. The next step is to determine whether the knee is infected. The details of such a workup are covered in other lectures, however, the author prefers to aspirate all such knees and obtain C reactive protein and Sedimentation Rates. For equivocal cases, PCR may be helpful. If no infection is present, complex reconstruction is considered. Segmental megaprosthesis and hinged prostheses may be helpful. Often, soft tissue reconstruction with an extensor mechanism allograft or muscle flap is required. Obviously, these are massive undertakings and should be done by experienced surgeons. If a prosthesis is not a good option, other options include definitive resection, knee arthrodesis, or above knee amputation. A careful discussion with the patient about the pros and cons is necessary to allow them to partner with the surgeon in the decision-making. Definitive resections are reserved for minimal to non-ambulators with significant co-morbidity that do not desire an AKA. AKA is often the best option, however, it should be noted that the majority of these patients will never ambulate with a prosthesis due to the energy requirements necessary to do so. High complication rates and reoperation rates have been reported with AKA after TKA. Functional outcome studies have generally shown better function with arthrodesis than with AKA. Arthrodesis can be effective and can be accomplished with several methods. If active infection is present, and external fixator is typically chosen. If no infection is present then plating or long intramedullary nailing is considered. Plating requires healthy anterior soft tissues due the bulk associated with double plating techniques. The highest union rates have been reported with long nails. The author therefore prefers to use long nails after eradicating infection with a staged procedure (interval spacer) rather than to use an external fixator. Union rates are higher with nails, but the risk of re-infection is slightly higher as well. Careful attention to detail is necessary to minimise complications.
Collective motion under beacon-referenced cyclic pursuit

Abstract Cyclic pursuit frameworks, which are built upon pursuit interactions between neighboring agents in a cycle graph, provide an efficient way to create useful global behaviors in a collective of autonomous robots. Previous work had considered cyclic pursuit with a constant bearing (CB) pursuit law, and demonstrated the existence of circling equilibria for the corresponding dynamics. In this work, we propose a beacon-referenced version of the CB pursuit law, wherein a stationary beacon provides an additional reference for the individual agents in a collective. When implemented in a cyclic framework, we show that the resulting dynamics admit relative equilibria corresponding to a circling orbit around the beacon, with the circling radius and the distribution of agents along the orbit determined by parameters of the proposed pursuit law. We also derive necessary conditions for stability of the circling equilibria, which provides a guide for parameter selection. Finally, by introducing a change of variables, we demonstrate the existence of a family of invariant manifolds related to spiraling motions around the beacon which preserve the “pure shape” of the collective, and study the reduced dynamics on a representative manifold.
CARTILAGE REPAIR AND KNEE JOINT PRESERVATION: A REALISTIC OPTION OR FORESTALLING THE INEVITABLE?

Cartilage is known to have limited intrinsic repair capabilities and cartilage defects can progress to osteoarthritis (OA). OA is a major economic burden of the 21st century, being among the leading causes of disability. The risk of disability from knee OA is as great as that derived from cardiovascular disease; a fact that becomes even more concerning when considering that even isolated cartilage defects can cause pain and disability comparable to that of severe OA. Several cartilage repair procedures are in current clinical application, including microfracture, osteochondral autograft transfer, osteochondral allograft transplantation, and autologous chondrocyte implantation (ACI). Given the economic challenges facing our health care system, it appears prudent to choose procedures that provide the most durable long-term outcome. Comparatively few studies have examined long-term outcomes, an important factor when considering the substantial differences in cost and morbidity among the various treatment options. This study reviews the clinical outcomes of autologous chondrocyte implantation at a minimum of 10 years after treatment of chondral defects of the knee. Mean age at surgery was 36 ± 9 years; mean defect size measured 8.4 ± 5.5cm2. Outcome scores were prospectively collected pre- and postoperatively at the last follow up. We further analyzed potential factors contributing to failure in hopes of refining the indications for this procedure. Conclusions: ACI provided durable outcomes with a survivorship of 71% at 10 years and improved function in 75% of patients with symptomatic cartilage defects of the knee at a minimum of 10 years after surgery. A history of prior marrow stimulation as well as the treatment of very large defects was associated with an increased risk of failure.
The de Rham-Federer theory of differential characters and character duality

The theory of differential characters is developed completely from a de Rham-Federer viewpoint. Characters are defined as equivalence classes of special currents, called sparks, which appear naturally in the theory of singular connections. As in de Rham-Federer cohomology, many different spaces of currents are shown to yield the character groups. The fundamental exact sequences are derived, and a multiplication of de Rham-Federer characters is defined using new transversality/intersection results for flat and rectifiable currents. An equivalence of de Rham-Federer characters with the classical Cheeger-Simons characters is given, as in de Rham cohomology, via integration. This discussion rounds out the approach to characters introduced by Gillet-Soule and Harris. The groups of differential characters have a natural topology and smooth Pontrjagin duals (introduced here) which fit into fundamental exact sequences. A principal result is the formulation and proof of duality for characters on oriented manifolds. It is shown that the pairing ( a, b ) [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01i" /] a * b ([ X ]) defined by multiplication and evaluation on the fundamental cycle, gives an isomorphism of the group of differential characters of degree k with the dual to characters in degree n - k -1 where n = dim( X ). Thom homomorphisms, which refine the usual ones in de Rham theory and integral cohmology, are established for differential characters. Gysin maps for characters are similarly established. New examples, namely Morse sparks and Hodge sparks, are introduced and examined in detail.
SUPERCAPSULAR PERCUTANEOUS-ASSISTED TOTAL HIP REPLACEMENT: EARLY RESULTS FROM A SINGLE SURGEON'S INITIAL 50 ELECTIVE CASES

INTRODUCTION The direct anterior approach to THR has become an increasingly popular minimally-invasive technique in an effort to minimize dislocation risk, facility early recovery, and diminish soft tissue injury. However, it has been associated with unique complications including intraoperative femur fracture, cutaneous nerve palsy, stem subsidence, and wound healing complications. These risk of these complications have been documented to be more likely in the surgeon's early experience with the approach. The minimally-invasive Supercapsular Percutaneous-Assisted (SuperPATH) technique was developed to minimize capsular and short-external rotator injury, minimize dislocation risk, and provide an easier transition from the standard posterior approach. METHODS Fifty (50) consecutive elective total hip replacements in 48 patients were performed using the SuperPATH technique. These also represented the first fifty elective THRs the surgeon performed in practice. Indications were primary or secondary osteoarthritis (92%), avascular necrosis (6%), and impending pathologic fracture (2%). Patients were evaluated retrospectively for dislocation, major, and minor complications. RESULTS At average follow-up of 10.9 months (Range 1–27 months), there were no dislocation events. There was one periprosthetic fracture identified at 14-day follow-up that required femoral revision surgery in an elderly female patient with osteoporosis. Otherwise, there were no reoperations for any reason. There were no wound complications or deep infections. There was one stem subsidence (2%) of 4 mm. There were no neurovascular injuries. CONCLUSION The SuperPATH technique can likely be performed at an early experience level with low early complication risk and lower early dislocation risk. This minimally-invasive technique deserves further interest and evaluation as it may present a gentle learning-curve to surgeons.
Expectations and forecasting during the Great Depression: Real-time evidence from the business press☆

Abstract How was the Great Depression viewed in real time? This paper yields a new perspective on this question by quantifying the qualitative statements of economic analysts in the business press and at the Federal Reserve Board. We compare the statements of economic analysts about current and future conditions to what actually happened to the American economy in the Great Depression. While Depression-era economic forecasters were able to accurately assess what was happening contemporaneously in the economy, forecasters were persistently optimistic that “the corner had been turned” and that a strong recovery was imminent even as the economy continued to decline. This optimism was based on the use of analogies and forecasting rules-of-thumb of how an economy should behave, which were derived from the experience of previous recessions (Haney, 1931).
Symmetries in CR complexity theory

Abstract We introduce the Hermitian-invariant group Γ f of a proper rational map f between the unit ball in complex Euclidean space and a generalized ball in a space of typically higher dimension. We use properties of the groups to define the crucial new concepts of essential map and the source rank of a map. We prove that every finite subgroup of the source automorphism group is the Hermitian-invariant group of some rational proper map between balls. We prove that Γ f is non-compact if and only if f is a totally geodesic embedding. We show that Γ f contains an n-torus if and only if f is equivalent to a monomial map. We show that Γ f contains a maximal compact subgroup if and only if f is equivalent to the juxtaposition of tensor powers. We also establish a monotonicity result; the group, after intersecting with the unitary group, does not decrease when a tensor product operation is applied to a polynomial proper map. We give a necessary condition for Γ f (when the target is a generalized ball) to contain automorphisms that move the origin.
Broadband parametric amplifiers based on nonlinear kinetic inductance artificial transmission lines

We present broadband parametric amplifiers based on the kinetic inductance of superconducting NbTiN thin films in an artificial (lumped-element) transmission line architecture. We demonstrate two amplifier designs implementing different phase matching techniques: periodic impedance loading and resonator phase shifters placed periodically along the transmission line. Our design offers several advantages over previous CPW-based amplifiers, including intrinsic 50 Ω characteristic impedance, natural suppression of higher pump harmonics, lower required pump power, and shorter total trace length. Experimental realizations of both versions of the amplifiers are demonstrated. With a transmission line length of 20 cm, we have achieved gains of 15 dB over several GHz of bandwidth.
Evaluating testing strategies for identifying youths with HIV infection and linking youths to biomedical and other prevention services

Importance Most human immunodeficiency virus (HIV)–infected youths are unaware of their serostatus (approximately 60%) and therefore not linked to HIV medical or prevention services. The need to identify promising and scalable approaches to promote uptake of HIV testing among youths at risk is critical. Objective To evaluate a multisite HIV testing program designed to encourage localized HIV testing programs focused on self-identified sexual minority males and to link youths to appropriate prevention services after receipt of their test results. Design, Setting, and Participants Testing strategies were evaluated using an observational design during a 9-month period (June 1, 2015, through February 28, 2016). Testing strategies were implemented by 12 adolescent medicine HIV primary care programs and included targeted testing, universal testing, or a combination. Data were collected from local youth at high risk of HIV infection and, specifically, sexual minority males of color. Main Outcomes and Measures Proportion of sexual minority males and sexual minority males of color tested, proportion of previously undiagnosed HIV-positive youths identified, and rates of linkage to prevention services. Results A total of 3301 youths underwent HIV testing. Overall, 35 (3.6%) of those who underwent universal testing in primary care clinical settings, such as emergency departments and community health centers, were sexual minority males (35 [3.6%] were males of color) compared with 236 (46.7%) (201 [39.8%] were males of color) who were tested through targeted testing and 693 (37.8%) (503 [27.4%] were males of color) through combination efforts. Identification of new HIV-positive cases varied by strategy: 1 (0.1%) via universal testing, 39 (2.1%) through combination testing, and 16 (3.2%) through targeted testing. However, when targeted tests were separated from universal testing results for sites using a combined strategy, the rate of newly identified HIV-positive cases identified through universal testing decreased to 1 (0.1%). Rates of new HIV-positive cases identified through targeted testing increased to 49 (6.3%). Youths who tested through targeted testing (416 [85.1%]) were more likely to link successfully to local HIV prevention services, including preexposure prophylaxis, compared with those who underwent universal testing (328 [34.1%]). Conclusions and Relevance The findings suggest that community-based targeted approaches to HIV testing are more effective than universal screening for reaching young sexual minority males (especially males of color), identifying previously undiagnosed HIV-positive youths, and linking HIV-negative youths to relevant prevention services. Targeted, community-based HIV testing strategies hold promise as a scalable and effective means to identify high-risk youths who are unaware of their HIV status.
Misclassification in travel surveys and implications to choice modeling: application to household auto ownership decisions

Travel surveys that elicit responses to questions regarding daily activity and travel choices form the basis for most of the transportation planning and policy analysis. The response variables collected in these surveys are prone to errors leading to mismeasurement or misclassification. Standard modeling methods that ignore these errors while modeling travel choices can lead to biased parameter estimates. In this study, methods available in the econometrics literature were used to quantify and assess the impact of misclassification errors in auto ownership choice data. The results uncovered significant misclassification rates ranging from 1 to 40% for different auto ownership alternatives. Also, the results from latent class models provide evidence for variation in misclassification probabilities across different population segments. Models that ignore misclassification were not only found to have lower statistical fit but also significantly different elasticity effects for choice alternatives with high misclassification probabilities. The methods developed in this study can be extended to analyze misclassification in several response variables (e.g., mode choice, activity purpose, trip/tour frequency, and mileage) that constitute the core of advanced travel demand models including tour and activity-based models.
Decomposing the Effects of Monetary Policy Using an External Instruments SVAR

We study the effects of monetary policy on economic activity separately identifying the effects of a conventional change in the fed funds rate from the policy of forward guidance. We use a structural VAR identified using external instruments from futures market data. The response of output to a fed funds rate shock is found to be consistent with typical monetary VAR analyses. However, the effect of a forward guidance shock that increases long-term interest rates has an expansionary effect on output. This counterintuitive response is shown to be tied to the asymmetric information between the Federal Reserve and the public.
Direct stabilization of optomechanical oscillators

We demonstrate a simple and effective technique for stabilization of optomechanical oscillators. We show that using oscillation amplitude and laser detuning as the feedback and control parameters provide long term stability and reduce system complexity.
Self- and Peer-Identified Victims in Late Childhood: Differences in Perceptions of the School Ecology

Patterns of adjustment for youth victimized by peers vary depending on whether youth are identified as victims through self-reports, peer-reports, or both. In order to provide more targeted strategies that may help mitigate negative consequences associated with specific victimization groups, more information is needed about how these youth perceive their school ecology (bullying and academic ecology), their feelings of school belonging, and their valuing of school. Based on the convergence of self- and peer-reports of victimization, we identified four victim groups from a sample of students in 5th grade classrooms (N = 1360; 52.8% girls, 53.1% White, 34.6% Black or Hispanic, 12.2% Native American, Asian, or other) using Latent Profile Analysis (LPA): convergent victims (high self- and peer-reports), self-identified victims (high self-, low peer-reports), peer-identified victims (low self-, high peer-reports), and nonvictims (low self- and peer-reports). Convergent victims’ perceptions were similar to nonvictims with key differences being convergent victims’ greater willingness to protect peers being bullied but lower feelings of school belonging compared to nonvictims. Peer-identified and self-identified victims perceived differences in the bullying and academic ecology including peer-identified victims’ greater willingness to protect peers and expectations for more peers to encourage bulling against them compared to self-identified victims. However, both peer- and self-identified victims perceived greater emotional risk of participating in class and had lower feelings of school belonging compared to nonvictims. Implications for supporting youth with divergent self- and peer-reported victimization status as they transition to middle school are discussed.
The campus as entrepreneurial ecosystem: the University of Chicago

This paper employs Frederick Jackson Turner’s Frontier Thesis of American democracy to construct a framework for understanding the U.S. university campus as an entrepreneurial ecosystem. One question that immediately comes to mind when studying ecosystem performance is what the proper unit of analysis is: the country, the state, the city, the region, or something smaller, like an incubator or accelerator? This paper suggests that the open, innovative American frontier that closed at the end of the twentieth century has reemerged in the entrepreneurial economy on the U.S. campus. The contemporary campus entrepreneurial ecosystem offers the characteristics of Turner’s frontier: available assets, liberty, and diversity while creating opportunity, and fostering entrepreneurship and innovation. A case study of the University of Chicago explores governance of the campus as an entrepreneurial ecosystem and the output produced by that campus ecosystem.
An interval estimate for the number of signals

We propose a multi-step procedure for constructing a confidence interval for the number of signals present. The proposed procedure uses the ratios of a sample eigenvalue and the sum of different sample eigenvalues sequentially to determine the upper and lower limits for the confidence interval. A preference zone in the parameter space of the population eigenvalues is defined to separate the signals and the noise. We derive the probability of a correct estimation, P(CE), and the least favorable configuration (LFC) asymptotically under the preference zone. Some important procedure properties are shown. Under the asymptotic LFC, the P(CE) attains its minimum over the preference zone in the parameter space of all eigenvalues. Therefore a minimum sample size can be determined in order to implement our procedure with a guaranteed probability requirement.
Higher Order Approximate Feedback Linearization About a Manifold

Abstract We consider the problem of approximately feedback linearizing a single input nonlinear system around the equilibrium manifold e while making the error terms be of highest order on e. Necessary and sufficient conditions are given for approximately feedback linearizing the system around e with error terms of order p on e. A constructive procedure is presented and illustrated with a simple example.
Maximal Planar Subgraphs of Fixed Girth in Random Graphs

In 1991, Bollobas and Frieze showed that the threshold for $G_{n,p}$ to contain a spanning maximal planar subgraph is very close to $p = n^{-1/3}$. In this paper, we compute similar threshold ranges for $G_{n,p}$ to contain a maximal bipartite planar subgraph and for $G_{n,p}$ to contain a maximal planar subgraph of fixed girth $g$.
Intravesical and Systemic Chemotherapy in the Management of Superficial Bladder Cancer

Before deciding to begin intravesical prophylaxis, the physician must categorize the patient with respect to the stage of the tumor and the multiplicity of lesions. This may require mucosal biopsies in order to determine whether the patient had unifocal or multifocal disease. Thiotepa, mitomycin C, and doxorubicin hydrochloride are discussed specifically and compared.
The Utility of Serum Albumin Values in the Nutritional Assessment of Hospitalized Patients

Nutritional assessment was performed on 47 patients admitted to a nephrology service; renal failure was present in 39 of the 47 patients. Values for serum albumin, total iron binding capacity, arm muscle circumference, triceps skin fold, and percent of ideal body weight for height and sex were determined. The 25 patients who had low serum albumin values at admission stayed in the hospital significantly (P less than 0.025) longer than those who had normal serum albumin values. No other abnormal nutrition-related finding or combination of findings was associated with a significantly (P less than or equal to 0.05) longer hospital stay. Low serum albumin values were also found in 11 of the 15 patients with infection. Low serum albumin values were far and away the most common abnormal nutrition-related findings in these infected patients in addition to the finding significantly (P less than 0.025) associated with a longer hospital stay.
Long-Term Effects of 24-Hr Unilateral Ureteral Obstruction on Renal Function in the Rat

Long-term effects of 24-hr unilateral ureteral obstruction on renal function in the rat. To characterize the pattern of recovery following release of unilateral ureteral obstruction of 24-hr duration, rats were studied with whole kidney clearance techniques, 3hrs, 8, 14, and 60 days after release. The single nephron glomerular filtration rate (SNGFR) of superficial and juxtamedullary nephrons was estimated with a modification of Hanssen's technique in rats studied 8 and 60 days after ureteral release. The whole kidney glomerular filtration rates (GFR) were decreased markedly 3hrs after relief of obstruction, but gradually increased and by 14 days, the GFR of the postobstructed kidney (POK) and the contralateral kidney (CK) were comparable. This recovery of GFR was not a consequence of a homogeneous improvement in SNGFR. At 8 days, more than 15% of superficial and juxtamedullary nephrons were not filtering in the POK. This decrease in the percent of filtering nephrons persisted to 60 days post release, indicating a permanent loss of nephron units. The SNGFR of the residual nephrons of the POK was significantly greater than that of the CK at 8 and 60 days following ureteral release. Thus, acute unilateral ureteral obstruction results in a permanent loss of filtering nephrons, which is offset by hyperfiltration of those remaining.
Parsing with Traces: An O(n^4) Algorithm and a Structural Representation

General treebank analyses are graph structured, but parsers are typically restricted to tree structures for efficiency and modeling reasons. We propose a new representation and algorithm for a class of graph structures that is flexible enough to cover almost all treebank structures, while still admitting efficient learning and inference. In particular, we consider directed, acyclic, one-endpoint-crossing graph structures, which cover most long-distance dislocation, shared argumentation, and similar tree-violating linguistic phenomena. We describe how to convert phrase structure parses, including traces, to our new representation in a reversible manner. Our dynamic program uniquely decomposes structures, is sound and complete, and covers 97.3% of the Penn English Treebank. We also implement a proof-of-concept parser that recovers a range of null elements and trace types.
Exercise contagion in a global social network

We leveraged exogenous variation in weather patterns across geographies to identify social contagion in exercise behaviours across a global social network. We estimated these contagion effects by combining daily global weather data, which creates exogenous variation in running among friends, with data on the network ties and daily exercise patterns of ∼1.1M individuals who ran over 350M km in a global social network over 5 years. Here we show that exercise is socially contagious and that its contagiousness varies with the relative activity of and gender relationships between friends. Less active runners influence more active runners, but not the reverse. Both men and women influence men, while only women influence other women. While the Embeddedness and Structural Diversity theories of social contagion explain the influence effects we observe, the Complex Contagion theory does not. These results suggest interventions that account for social contagion will spread behaviour change more effectively. Some argue that health-related behaviours, such as obesity, are contagious, but empirical evidence of health contagion remains inconclusive. Here, using a large scale quasi-experiment in a global network of runners, Aral and Nicolaides show that this type of contagion exists in fitness behaviours.
Lying, risk and accuracy

Almost all philosophers agree that a necessary condition on lying is that one says what one believes to be false. But, philosophers haven’t considered the possibility that the true requirement on lying concerns, rather, one’s degree-of-belief. Liars impose a risk on their audience. The greater the liar’s confidence that what she asserts is false, the greater the risk she’ll think she’s imposing on the dupe, and, therefore, the greater her blameworthiness. From this, I arrive at a dilemma: either the belief requirement is wrong, or lying isn’t interesting. I suggest an alternative necessary condition for lying on a degree-of-belief framework.
THE CEMENTLESS KNEE: AN EMERGENT GAME CHANGER – AFFIRMS

Over the past 30 years, cemented, cementless, and hybrid fixation options have been utilised with various total knee arthroplasty (TKA) implant systems. While cemented components are widely used and considered the most reliable method of fixation, historical results may not be applicable to contemporary patients, who are increasingly younger than 65 years of age. Moreover, the literature is not definitive on which method of TKA fixation obtains the best clinical, functional, and radiographic results. A recent Cochrane meta-analysis on roentgen stereophotogrammetric analysis (RSA) included five randomised clinical trials (RCTs) in 297 participants. The authors observed that cemented fixation of tibial components demonstrated smaller displacement in relation to cementless fixation. However, the risk of future aseptic loosening with uncemented fixation was approximately half that of cemented fixation (risk ratio = 0.47, 95% CI 0.24 to 0.92) with a 16% absolute risk difference between groups. Almost all included studies recorded functional measures of Knee Society and Hospital for Special Surgery knee scores, but the authors of each study found no significant difference between the groups. Recently, highly porous metals have become an attractive fixation option in TKA due to their biomechanical properties. In a large RCT of 397 patients, Pulido et al found that uncemented highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with traditional cemented modular tibias. While longer-term studies are needed, cementless TKAs may be a durable and reliable alternative with highly porous metals, particularly in younger patients.
A remark on finite type conditions

We prove that a certain positivity condition, considerably more general than pseudoconvexity, enables one to conclude that the regular and singular orders of contact agree when either of these numbers is 4.
Preventive Repression: Two Types of Moral Hazard

Authoritarian leaders maintain their grip on power primarily through preventive repression, routinely exercised by specialized security agencies with the aim of preventing any opponents from organizing and threatening their power. We develop a formal model to analyze the moral hazard problems inherent in the principal-agent relationship between rulers and their security agents in charge of preventive repression. The model distinguishes two types of moral hazard: “politics,” through which the security agents can exert political influence to increase their payoff by decreasing the ruler’s rents from power, and “corruption,” through which the agents can increase their payoff by engaging in rent-seeking activities that do not decrease the ruler’s rents from power. The surprising conclusion is that both the ruler and the security agent are better off when the only moral hazard problem available is politics rather than when the agent can choose between politics and corruption. We also show that the equilibrium probability of ruler’s survival in power is higher when politics is the only moral hazard available to the agent. These findings lead to our central conclusion that opportunities for corruption undermine authoritarian rule by distorting the incentives of the security agencies tasked with preventing potential threats to an authoritarian ruler’s grip on power.
Using Options and Covariance Testing for Long Horizon Off-Policy Policy Evaluation

Evaluating a policy by deploying it in the real world can be risky and costly. Off-policy policy evaluation (OPE) algorithms use historical data collected from running a previous policy to evaluate a new policy, which provides a means for evaluating a policy without requiring it to ever be deployed. Importance sampling is a popular OPE method because it is robust to partial observability and works with continuous states and actions. However, the amount of historical data required by importance sampling can scale exponentially with the horizon of the problem: the number of sequential decisions that are made. We propose using policies over temporally extended actions, called options, and show that combining these policies with importance sampling can significantly improve performance for long-horizon problems. In addition, we can take advantage of special cases that arise due to options-based policies to further improve the performance of importance sampling. We further generalize these special cases to a general covariance testing rule that can be used to decide which weights to drop in an IS estimate, and derive a new IS algorithm called Incremental Importance Sampling that can provide significantly more accurate estimates for a broad class of domains.
Human Factors Impacts of Light-Emitting Diode Airfield Lighting

Light-emitting diodes (LEDs) differ from incandescent light sources in several ways that are relevant to energy and maintenance requirements of airfield lighting systems. They have higher luminous efficacy and, when designed properly, have longer useful operating lives; both factors make LEDs attractive candidates for airfield lighting. The photometric, colorimetric, and temporal characteristics of LEDs also differ from those of incandescent light sources, and these can have important implications for the appearance of runway and taxiway lighting systems. The present paper reviews publications summarizing experimental and analytical investigations designed to assess these implications with respect to the following human factors impacts: color identification, brightness and glare, visibility in fog and haze, response to onset of flashing lights, and stroboscopic effects such as the phantom array. Overall, this review of experimental evidence suggests that, in addition to their reduced energy use and mainte...
Measuring Investor Sentiment

Investor sentiment indicates how far an asset value deviates from its economic fundamentals. In this article, we review various measures of investor sentiment based on market, survey, and text and ...
Bayesian versus heuristic-based choice under sleep restriction and suboptimal times of day

Abstract This paper examines how a commonly experienced cognitive state, sleepiness, impacts choice in a Bayesian task. We implement an ecologically valid sleep manipulation, and our main result is the increased use of a simple reinforcement-heuristic when sleepy. While use of this heuristic leads to errors in difficult decision environments where Bayes rule and reinforcement conflict, it does not harm choice accuracy in easier environments where Bayes rule and reinforcement coincide. Our results overall are consistent with the hypothesis that individuals make decisions in a relatively less deliberative manner under common adverse sleep states, which gives rise to a relative increase in automatic or heuristic-based decision making. While such heuristic-based decisions that are promoted by sleepiness need not be suboptimal in all contexts, our results show that the accuracy of a Bayesian assessment in more complex decision environments will likely suffer when sleepy.
Optimal Data Acquisition for Statistical Estimation

We consider a data analyst's problem of purchasing data from strategic agents to compute an unbiased estimate of a statistic of interest. Agents incur private costs to reveal their data and the costs can be arbitrarily correlated with their data. Once revealed, data are verifiable. This paper focuses on linear unbiased estimators. We design an individually rational and incentive compatible mechanism that optimizes the worst-case mean-squared error of the estimation, where the worst-case is over the unknown correlation between costs and data, subject to a budget constraint in expectation. We characterize the form of the optimal mechanism in closed-form. We further extend our results to acquiring data for estimating a parameter in regression analysis, where private costs can correlate with the values of the dependent variable but not with the values of the independent variables.
Ishmael's Bane The Sin and Crime of Illegitimacy Reconsidered

This essay offers a critical rereading of the western theological and legal doctrine of illegitimacy or bastardy. The author traces the western stigma against bastards to the Bible, particularly to the story of Ishamel, the illegitimate son of Abraham and Hagar. He then shows the systematic discrimination against bastards in classic canon law and in early modern Anglo-American common law, and the slow amelioration of their plight in legal reforms in the United States in the past century. The author concludes that the western doctrine of illegitimacy is theologically illegitimate and suggests a few historically-informed legal remedies, notably adoption, that would help mitigate the plight of illegitimates today.
A Principled Approximation Framework for Optimal Control of Semi-Markov Jump Linear Systems

We consider continuous-time, finite-horizon, optimal quadratic control of semi-Markov jump linear systems (S-MJLS), and develop principled approximations through Markov-like representations for the holding-time distributions. We adopt a phase-type approximation for holding-time distributions, which is known to be consistent, and translates an S-MJLS into a specific MJLS with partially observable modes (MJLSPOM), where the modes in a cluster have the same dynamic, the same cost weighting matrices, and the same control policy. For a general MJLSPOM, we give necessary and sufficient conditions for optimal (switched) linear controllers. When specialized to our particular MJLSPOM, we additionally establish the existence of an optimal linear controller, as well as its optimality within the class of general controllers satisfying standard smoothness conditions. The known equivalence between phase-type distributions and positive linear systems allows us to leverage existing modeling tools, but possibly with large computational costs. Motivated by this, we propose a matrix-exponential approximation of holding-time distributions, resulting in pseudo -MJLSPOM representation, wherein the transition rates could be negative. Such a representation is of relatively low order, and maintains the same optimality conditions as for the MJLSPOM representation, but could violate nonnegativity of holding-time density functions. A two-step procedure consisting of a local pulling-up modification and a filtering technique is constructed to enforce nonnegativity.
Dark energy density predicted and explained

It has recently been shown that the observed Hubble function for cosmological expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with only one free constant, while neglecting cosmic curvature and mass density, using the modified Friedmann equation implied by subjecting the Higgs scalar field model to conformal Weyl scaling symmetry. It is shown here that the implied dark energy parameter is produced by dressing the bare scalar field by the neutral gauge boson field induced by weak cosmological time dependence of the conformal Higgs model. Predicted persistent cosmic acceleration is consistent with the nonclassical acceleration parameter inferred by conformal theory from observed excessive galactic rotation velocities and dark galactic halos, all without dark matter.
Norm Conflict Resolution in Stochastic Domains

Artificial agents will need to be aware of human moral and social norms, and able to use them in decision-making. In particular, artificial agents will need a principled approach to managing conflicting norms, which are common in human social interactions. Existing logic-based approaches suffer from normative explosion and are typically designed for deterministic environments; reward-based approaches lack principled ways of determining which normative alternatives exist in a given environment. We propose a hybrid approach, using Linear Temporal Logic (LTL) representations in Markov Decision Processes (MDPs), that manages norm conflicts in a systematic manner while accommodating domain stochasticity. We provide a proof-of-concept implementation in a simulated vacuum cleaning domain.
Leukotriene B4 Driven Neutrophil Recruitment to the Skin Is Essential for Allergic Skin Inflammation

Scratching triggers skin flares in atopic dermatitis. We demonstrate that scratching of human skin and tape stripping of mouse skin cause neutrophil influx. In mice, this influx was largely dependent on the generation of leukotriene B4 (LTB4) by neutrophils and their expression of the LTB4 receptor BLT1. Allergic skin inflammation in response to epicutaneous (EC) application of ovalbumin to tape-stripped skin was severely impaired in Ltb4r1(-/-) mice and required expression of BLT1 on both T cells and non-T cells. Cotransfer of wild-type (WT) neutrophils, but not neutrophils deficient in BLT1 or the LTB4-synthesizing enzyme LTA4H, restored the ability of WT CD4(+) effector T cells to transfer allergic skin inflammation to Ltb4r1(-/-) recipients. Pharmacologic blockade of LTB4 synthesis inhibited allergic skin inflammation elicited by cutaneous antigen challenge in previously EC-sensitized mice. Our results demonstrate that a neutrophil-T cell axis reliant on LTB4-BLT1 interaction is required for allergic skin inflammation.
Human Ska complex and Ndc80 complex interact to form a load-bearing assembly that strengthens kinetochore–microtubule attachments

Accurate segregation of chromosomes relies on the force-bearing capabilities of the kinetochore to robustly attach chromosomes to dynamic microtubule tips. The human Ska complex and Ndc80 complex are outer-kinetochore components that bind microtubules and are required to fully stabilize kinetochore–microtubule attachments in vivo. While purified Ska complex tracks with disassembling microtubule tips, it remains unclear whether the Ska complex–microtubule interaction is sufficiently strong to make a significant contribution to kinetochore–microtubule coupling. Alternatively, Ska complex might affect kinetochore coupling indirectly, through recruitment of phosphoregulatory factors. Using optical tweezers, we show that the Ska complex itself bears load on microtubule tips, strengthens Ndc80 complex-based tip attachments, and increases the switching dynamics of the attached microtubule tips. Cross-linking mass spectrometry suggests the Ska complex directly binds Ndc80 complex through interactions between the Ska3 unstructured C-terminal region and the coiled-coil regions of each Ndc80 complex subunit. Deletion of the Ska complex microtubule-binding domain or the Ska3 C terminus prevents Ska complex from strengthening Ndc80 complex-based attachments. Together, our results indicate that the Ska complex can directly strengthen the kinetochore–microtubule interface and regulate microtubule tip dynamics by forming an additional connection between the Ndc80 complex and the microtubule.
Hair regeneration by small molecules that activate autophagy

Hair plays important roles, ranging from the conservation of body heat to the preservation of psychological well-being. Hair loss or alopecia affects millions worldwide and can occur because of aging, hormonal dysfunction, autoimmunity, or as a side effect of cancer treatment (Gilhar et al., 2012; Petukhova et al., 2010). Methods that can be used to regrow hair are highly sought after, but lacking. Here we report that hair regeneration can be stimulated by small molecules that activate autophagy, including the longevity metabolites α-ketoglutarate and α-ketobutyrate, and the prescription drugs rapamycin and metformin which impinge on TOR and AMPK signaling.
Value of neutrophil to lymphocyte ratio as a predictor of mortality in patients undergoing aortic valve replacement

Background: Neutrophil to lymphocyte ratio (NLR) has been studied as a measure of inflammation and as a prognosticating factor in various medical conditions including neoplastic, inflammatory and cardiovascular. The prognostic role of NLR in predicting mortality in patients with aortic stenosis undergoing surgical aortic valve replacement (AVR) has not been studied. The aim of our study is to explore the utility of NLR as a predictor of both, short and long-term mortality, in patients undergoing surgical AVR. Methods: Consecutive patients with aortic stenosis admitted for AVR to our institution were evaluated for study inclusion. Of the 335 patients admitted from January 2007 to September 2011, 234 met study inclusion criteria. Patients were divided into two groups depending on their initial preoperative NLR level with a cutoff value of 3. Three-year vital status was accessed with electronic medical records and Social Security Death Index. Survival analysis, stratified by NLR, was used to evaluate the predictive value of preoperative NLR levels. Results: Patients with NLR ≥3, when compared to those with NLR vs . 0, P=0.0006), 6-month (19.54% vs . 0.95%, P vs . 3.78%, P Conclusions: NLR is an independent predictor of short-term and long-term mortality in patients with aortic stenosis undergoing AVR surgery, especially those with NLR ≥3. We strongly suggest the use of NLR as a tool to risk stratify patients with aortic stenosis undergoing AVR surgery.
Firm location, transport connectivity, and agglomeration economies : Evidence from Liberia

Transport connectivity is among the most important factors in increasing firm productivity and accelerating economic development. The literature generally supports the idea of agglomeration economies, although there is little evidence of their effectiveness in Africa. There are often empirical challenges, such as spatial externalities and endogeneity of infrastructure development. Using firm registry data in Liberia, this study used the instrumental variable spatial autoregressive model to examine the effects of transport connectivity on firms' decisions on where to locate. The study found significant spatial autocorrelation and possible endogeneity related to transport infrastructure, and that firms are more likely to be located where market accessibility is better. The data indicated strong agglomeration economies, indicating that the primary city, Monrovia, is likely to continue to grow and attract more people and firms, and that secondary cities can also grow with greater transport connectivity between populated areas, such as district centers.