cssi/SciSciGPT-SciSciNet huggingface dataset:
Nucleation of super-critical carbon dioxide in a venturi nozzle

Abstract Pressure reduction at the entrance of the compressor in supercritical CO2 Brayton cycles may cause nucleation and create a mixture of vapor and liquid droplets due to operation near the saturation conditions. Transient behavior of the flow after nucleation may cause serious issues in operation of the cycle and degrade the materials used in the design. The nucleation behavior of supercritical carbon-dioxide inside a venturi nozzle near the critical point is computationally studied. A transient compressible 3D Navier–Stokes solver, coupled with continuity, and energy equations have been implemented. In order to expedite the simulations, Fluid property Interpolation Tables (FIT) based on a piecewise biquintic spline interpolation of Helmholtz energy have been integrated with OpenFOAM to model S-CO2 properties. The mass fraction of vapor created in the venturi nozzle has been calculated using homogeneous equilibrium model (HEM). Nucleation behavior has been shown to be very sensitive to the inlet pressure, inlet temperature, and flow rate. The flow conditions that led to nucleation were identified. Nucleation was observed in the throat area and divergent section of the nozzle for mass flow rates from 0.050 kg/s to 0.065 kg/s, inlet pressure from 7.8 to 7.4 MPa for fixed exit pressure equal to 7.28 MPa. The inception of high-vapor-content nucleation was first observed in the throat area away from the side walls that remained confined to the throat region in later times. However, near the walls, a high liquid-content two-phase region was detected, first in the divergent section. At later times, the two-phase region was convected downstream toward the nozzle exit. Nucleation in central plane was associated with larger pressure drop and higher vapor-content (higher volume fraction); whereas lower pressure drop and more liquid-content (lower volume fraction) was observed near the walls.
The Affordable Care Act as Retiree Health Insurance: Implications for Retirement and Social Security Claiming

This paper investigates the effects of the Affordable Care Act (ACA) on retirement. The first part of the paper is a difference-in-difference analysis of changes in retirement (and retirement expectations) before and after adoption of the ACA. We find no statistically significant evidence that ACA increased the propensity to retire or changed retirement expectations. The second part of the analysis is based on a structural retirement model. For those age 50 at the time ACA was introduced, the overall reduction in full-time work over the age span 54–65 is simulated to be about 0.1 percentage points. Data are from the Health and Retirement Study.
Price Doubling and Item Halving: Robust Revenue Guarantees for Item Pricing

We study approximation algorithms for revenue maximization based on static item pricing, where a seller chooses prices for various goods in the market, and then the buyers purchase utility-maximizing bundles at these given prices. We formulate two somewhat general techniques for designing good pricing algorithms for this setting: Price Doubling and Item Halving. Using these techniques, we unify many of the existing results in the item pricing literature under a common framework, as well as provide several new bicriteria algorithms for approximating both revenue and social welfare simultaneously. The main technical contribution of this paper is a O((log m + log k)2)-approximation algorithm for revenue maximization based on the item halving technique, for settings where buyers have XoS valuations, where m is the number of goods and k is the average supply. Surprisingly, ours is the first known item pricing algorithm with polylogarithmic approximation for such general classes of valuations, and partially resolves an important open question from the algorithmic pricing literature about the existence of item pricing algorithms with logarithmic factors for general valuations
What Do Recurrent Neural Network Grammars Learn About Syntax

Recurrent neural network grammars (RNNG) are a recently proposed probablistic generative modeling family for natural language. They show state-of-the-art language modeling and parsing performance. We investigate what information they learn, from a linguistic perspective, through various ablations to the model and the data, and by augmenting the model with an attention mechanism (GA-RNNG) to enable closer inspection. We find that explicit modeling of composition is crucial for achieving the best performance. Through the attention mechanism, we find that headedness plays a central role in phrasal representation (with the model’s latent attention largely agreeing with predictions made by hand-crafted head rules, albeit with some important differences). By training grammars without nonterminal labels, we find that phrasal representations depend minimally on nonterminals, providing support for the endocentricity hypothesis.
A Comparison of the Prevalence of Dementia in the United States in 2000 and 2012

Importance The aging of the US population is expected to lead to a large increase in the number of adults with dementia, but some recent studies in the United States and other high-income countries suggest that the age-specific risk of dementia may have declined over the past 25 years. Clarifying current and future population trends in dementia prevalence and risk has important implications for patients, families, and government programs. Objective To compare the prevalence of dementia in the United States in 2000 and 2012. Design, Setting, and Participants We used data from the Health and Retirement Study (HRS), a nationally representative, population-based longitudinal survey of individuals in the United States 65 years or older from the 2000 (n = 10 546) and 2012 (n = 10 511) waves of the HRS. Main Outcomes and Measures Dementia was identified in each year using HRS cognitive measures and validated methods for classifying self-respondents, as well as those represented by a proxy. Logistic regression was used to identify socioeconomic and health variables associated with change in dementia prevalence between 2000 and 2012. Results The study cohorts had an average age of 75.0 years (95% CI, 74.8-75.2 years) in 2000 and 74.8 years (95% CI, 74.5-75.1 years) in 2012 ( P = .24); 58.4% (95% CI, 57.3%-59.4%) of the 2000 cohort was female compared with 56.3% (95% CI, 55.5%-57.0%) of the 2012 cohort ( P P P Conclusions and Relevance The prevalence of dementia in the United States declined significantly between 2000 and 2012. An increase in educational attainment was associated with some of the decline in dementia prevalence, but the full set of social, behavioral, and medical factors contributing to the decline is still uncertain. Continued monitoring of trends in dementia incidence and prevalence will be important for better gauging the full future societal impact of dementia as the number of older adults increases in the decades ahead.
Consumer Outcomes After Implementing CommonGround as an Approach to Shared Decision Making.

Objective:The authors examined consumer outcomes before and after implementing CommonGround, a computer-based shared decision-making program.Methods:Consumers with severe mental illness (N=167) were interviewed prior to implementation and 12 and 18 months later to assess changes in active treatment involvement, symptoms, and recovery-related attitudes. Providers also rated consumers on level of treatment involvement.Results:Most consumers used CommonGround at least once (67%), but few used the program regularly. Mixed-effects regression analyses showed improvement in self-reported symptoms and recovery attitudes. Self-reported treatment involvement did not change; however, for a subset of consumers with the same providers over time (N=83), the providers rated consumers as more active in treatment.Conclusions:This study adds to the growing literature on tools to support shared decision making, showing the potential benefits of CommonGround for improving recovery outcomes. More work is needed to better enga...
A Field Study on Small Accounting Firm Membership in Associations and Networks: Implications for Audit Quality

ABSTRACT Small accounting firms represent important participants in the audit market, yet details of how they operate and develop competencies remain unexplored. Small firms often join forces through accounting associations and networks (AANs), which may help them overcome significant challenges commonly faced by smaller firms. We interview 37 partners from 18 firms representing nine AANs to examine how small firms leverage their AAN membership and to understand the related implications for audit quality. Our findings indicate that small firms acquire needed resources and enhance their market legitimacy through AAN membership; however, the nature and extent to which they do so varies by AAN type. Importantly, we also find that the majority of respondents perceive AAN resources, especially access to expertise, as critical to their firms' audit quality. Our research, informed by a theoretical lens based on resource dependence and legitimacy, enriches existing auditing literature, provides a new perspective ...
A users’ guide to the 2016 Surviving Sepsis Guidelines

The 2016 Surviving Sepsis Guidelines have arrived, a remarkable document, all 67 pages with 655 references (1, 2). We congratulate the lead authors and contributing committee members. With each iteration, the guidelines grow more complex and perhaps more challenging to utilize. We offer guidance tow
Category effects on stimulus estimation: Shifting and skewed frequency distributions - A reexamination

Duffy, Huttenlocher, Hedges, and Crawford (Psychonomic Bulletin & Review, 17(2), 224-230, 2010) report on experiments where participants estimate the lengths of lines. These studies were designed to test the category adjustment model (CAM), a Bayesian model of judgments. The authors report that their analysis provides evidence consistent with CAM: that there is a bias toward the running mean and not recent stimuli. We reexamine their data. First, we attempt to replicate their analysis, and we obtain different results. Second, we conduct a different statistical analysis. We find significant recency effects, and we identify several specifications where the running mean is not significantly related to judgment. Third, we conduct tests of auxiliary predictions of CAM. We do not find evidence that the bias toward the mean increases with exposure to the distribution. We also do not find that responses longer than the maximum of the distribution or shorter than the minimum become less likely with greater exposure to the distribution. Fourth, we produce a simulated dataset that is consistent with key features of CAM, and our methods correctly identify it as consistent with CAM. We conclude that the Duffy et al. (2010) dataset is not consistent with CAM. We also discuss how conventions in psychology do not sufficiently reduce the likelihood of these mistakes in future research. We hope that the methods that we employ will be used to evaluate other datasets.
Marital Infidelity: A Game-Theoretic Analysis

In this paper we focus on a married couple and analyze a game of marital infidelity. The husband can either be faithful to or cheat on his wife. The wife decides how much effort to expend monitoring her husband and she chooses monitoring effort \(m\in [ {0,1} ]\). Our analysis of this strategic interaction leads to five results. First, we solve for the optimal m when the wife believes that her husband is certainly cheating on her. Second, we solve for the optimal m when the wife believes that her husband is faithful for sure. Third, given that the wife believes her husband is faithful with probability p, we determine the best response level of m as a function of p. Fourth, we explain why there is no pure strategy Nash equilibrium in the game between the husband and the wife. Finally, we show that there exists a mixed strategy Nash equilibrium in the same husband–wife game.
Alignment of a vector magnetometer to an optical prism.

A method for alignment of a vector magnetometer to a rigidly attached prism is presented. This enables optical comparison of the magnetometer axes to physical surfaces in the apparatus, and thus an absolute determination of the magnetic field direction in space. This is in contrast with more common techniques, which focus on precise determination of the relative angles between magnetometer axes, and so are more suited to measuring differences in the direction of magnetic fields. Here we demonstrate precision better than 500 μrad on a fluxgate magnetometer, which also gives the coil orthogonality errors to a similar precision. The relative sensitivity of the three axes is also determined, with a precision of about 5 × 10−4.
CRPS M-estimation for max-stable models

Max-stable processes provide canonical models for the dependence of multivariate extremes. Inference with such models has been challenging due to the lack of tractable likelihoods which has motivated use of composite likelihood methods Padoan et al. (J. Amer. Stat. Assoc. 105(489):263–277, 2010). In contrast, the finite dimensional cumulative distribution functions (CDFs) appear natural to work with, and are readily available or can be approximated well. Motivated by this fact, in this work we develop an M-estimation framework for max-stable models based on the continuous ranked probability score (CRPS) of multivariate CDFs. We start by establishing conditions for the consistency and asymptotic normality of the CRPS-based estimators in a general context. We then implement them in the max-stable setting and provide readily computable expressions for their asymptotic covariance matrices. The resulting point and asymptotic confidence interval estimates are illustrated over popular simulated models. They enjoy accurate coverages and offer an alternative to composite likelihood based methods.
SGD Learns the Conjugate Kernel Class of the Network

We show that the standard stochastic gradient decent (SGD) algorithm is guaranteed to learn, in polynomial time, a function that is competitive with the best function in the conjugate kernel space of the network, as defined in Daniely, Frostig and Singer. The result holds for log-depth networks from a rich family of architectures. To the best of our knowledge, it is the first polynomial-time guarantee for the standard neural network learning algorithm for networks of depth more that two. As corollaries, it follows that for neural networks of any depth between 2 and log(n), SGD is guaranteed to learn, in polynomial time, constant degree polynomials with polynomially bounded coefficients. Likewise, it follows that SGD on large enough networks can learn any continuous function (not in polynomial time), complementing classical expressivity results.
Stability of Viscous Weak Detonation Waves for Majda’s Model

Continuing the program initiated by Humpherys et al. (Physica D 259:63–80, 2013) for strong detonation waves, we use a combination of analytical and numerical Evans-function techniques to analyze the spectral stability of weak detonation waves in a simplified model for gas-dynamical combustion. Combining these new spectral stability results with the pointwise Green function analysis of Lyng et al. (J Differ Equ 233(2):654–698, 2007), we conclude that these waves are nonlinearly stable. The principal novelty of this analysis is the treatment of weak detonation waves. In contrast to the case of strong detonation waves, weak detonation waves are under compressive and the stability of these waves is delicate and has not been treated by standard weighted-norm techniques. The present analysis thus provides a case study illustrating the flexibility and power of the Evans-function-based approach to stability. As in the case of strong detonations, we find that all tested waves are spectrally stable, hence nonlinearly stable.
Online Learning for Offloading and Autoscaling in Energy Harvesting Mobile Edge Computing

Mobile edge computing (also known as fog computing) has recently emerged to enable in-situ processing of delay-sensitive applications at the edge of mobile networks. Providing grid power supply in support of mobile edge computing, however, is costly and even infeasible (in certain rugged or under-developed areas), thus mandating on-site renewable energy as a major or even sole power supply in increasingly many scenarios. Nonetheless, the high intermittency and unpredictability of renewable energy make it very challenging to deliver a high quality of service to users in energy harvesting mobile edge computing systems. In this paper, we address the challenge of incorporating renewables into mobile edge computing and propose an efficient reinforcement learning-based resource management algorithm, which learns on-the-fly the optimal policy of dynamic workload offloading (to the centralized cloud) and edge server provisioning to minimize the long-term system cost (including both service delay and operational cost). Our online learning algorithm uses a decomposition of the (offline) value iteration and (online) reinforcement learning, thus achieving a significant improvement of learning rate and run-time performance when compared to standard reinforcement learning algorithms such as ${Q}$ -learning. We prove the convergence of the proposed algorithm and analytically show that the learned policy has a simple monotone structure amenable to practical implementation. Our simulation results validate the efficacy of our algorithm, which significantly improves the edge computing performance compared to fixed or myopic optimization schemes and conventional reinforcement learning algorithms.
Effect of well trajectory on liquid removal in horizontal gas wells

Abstract A systematic experimental study on two-phase air-water was carried out to evaluate effect of well trajectory on liquid removal in horizontal gas wells. Experiments were conducted in a facility with a 2-in. ID and 62.6-ft. long lateral section and a 41-ft. vertical section, which mimics a horizontal well. Four well configurations were considered; namely, toe-down, toe-up, one-undulation with a sump and one-undulation with a hump. Additionally, different flow conditions were used to simulate the well production as the reservoir pressure depletes. The effect of well trajectory on the liquid removal was evaluated measuring the pressure gradient, liquid holdup, film reversal, and flow pattern. Experimental results indicate that under stable conditions, toe-up is the best configuration for the displacement of the produced fluids from the toe to the kick-off point. However, at very low gas flow rates, severe slugging is observed in this configuration. Furthermore, for the toe-down, one-undulation with a sump, and one- undulation with a hump configurations liquid loading is observed in both lateral and vertical sections of the well. Consequently, significant liquid accumulation and an eventual slugging condition are observed in the well. It was observed that the measured critical gas velocity to avoid liquid loading is lower than gas velocity at the minimum pressure gradient, indicating that minimum pressure gradient criterion is not enough to determine whether the well will be under stable or unstable conditions. Finally, toe-down configuration presents the largest liquid accumulation in the lateral section, indicating lower efficiency to remove liquids from the toe to the kick-off point.
Outcome-robust mechanisms for Nash implementation

Mechanisms for Nash implementation in the literature are fragile in the sense that they fail if just one or two players do not follow their equilibrium strategy. A mechanism is outcome-robust if its equilibrium outcome is not affected by any deviating minority of players. Is Nash implementation possible with outcome-robust mechanisms? I first show that in the standard environment, it is impossible to Nash-implement any nonconstant social choice rule with outcome-robust mechanisms even if a small number of players are partially honest. If simple transfers are used and if at least one player is partially honest, however, any social choice rule is Nash implementable using an outcome-robust mechanism. The mechanism presented in this paper makes no assumptions about how transfers enter players’ preferences except that transfers are valuable. Moreover, it has: no transfers in equilibrium, arbitrarily small off-equilibrium transfers, and no integer or modulo games.
Singularities in nonlocal interface dynamics

An effective interface dynamics is derived for a Stefan-type moving-boundary-value problem corresponding to electrostatic aggregation in two dimensions. With the help of conformal-mapping techniques the problem may be reduced to a many-body-type problem described by a system of ordinary differential equations. The method allows one to show that the Mullins-Sekerka instability in this case leads to generation of cusp singularities in the interface in a finite time.
Pseudorandomness of ring-LWE for any ring and modulus

We give a polynomial-time quantum reduction from worst-case (ideal) lattice problems directly to decision (Ring-)LWE. This extends to decision all the worst-case hardness results that were previously known for the search version, for the same or even better parameters and with no algebraic restrictions on the modulus or number field. Indeed, our reduction is the first that works for decision Ring-LWE with any number field and any modulus.
Asymptotically Reliable Serial Production Lines: Analysis, Synthesis and a Case Study

Abstract This paper presents a model of asymptotically reliable serial production lines and develops a theory for its ana.lysis and synthesis along with a case study of a specific application. As far as the a.nalysis is concerned, a complete asymptotic theory is developed for calculation of the average production rate a.nd steady state buffer occupancy. As far as the synthesis is concerned, a new method of optimal design, referred to as dynamic balancing, is derived and applied to specific synthesis problems. As for the case study, the paper gives the results of the performance analysis of a. pa.int shop operation in a modern automobile assembly plant and shows that the difference between the actual and theoretical data is within 3%. Improvement measures, developed on the basis of the theory presented, brought about 11% increase in the pa.int shop production rate.
The Improving Utility of Renal Transplantation in the Management of End-Stage Renal Disease

The results achieved by treating patients with end-stage renal failure with allotransplantation have improved dramatically since the 1950s when immunosuppression was induced by total body irradiation and there was a lack of HLA typing. Although long-term hemodialysis offers prolonged survival and partial rehabilitation for many individuals with end-stage renal disease, the technique is inconvenient and time consuming. Patients are restricted by necessary proximity to the machine, dietary limitations, potential failure of access sites, and complications of various organ systems. Despite the availability of dialysis and the federal funds to partially pay for treatment, long-term dialysis still remains a costly process for the individual in need of care. During the same period when dialysis techniques improved and became widely available, transplantation of the human kidney became an established and justified treatment for some patients with end-stage renal disease. Those with successful kidney allografts may achieve remarkable recovery and are often able to return to normal lives. One of the more striking improvements in the results of renal transplantation in recent years had been the decline in morbidity and mortality. Mortality by the end of the first year after transplantation during which time most deaths occur, is currently less than 5 percent in a number of major medical units. In part, this decline represents a change in philosophy by transplant teams, who now tend to decrease immunosuppression and sacrifice the kidney rather than the patient in instances of inexorable rejection. In addition, declining mortality is directly attributable to improved methods of preventing, discovering, and treating patients with potential or real infections. More recently, in some centers, the rate of successful engraftment has shown gratifying improvement due to refinements in tissue typing, improved cross matching, new immunosuppressive therapies, and pretransplant conditioning with blood products. These recent improvements are the primary focus of this review. Unfortunately, until very recently, rates of functional survival of allografts have not been satisfactory.
Single-Stage Percutaneous Extraction of Renal Calculi

The routine application of percutaneous techniques to the management of patients with renal calculous disease is evolving rapidly. Of 74 patients requiring surgery for renal calculous disease, 64 (86%) were deemed suitable candidates for percutaneous stone removal rather than standard open surgical intervention. The percutaneous procedure was successful in 60 (94%) of these patients. Compared to a standard surgical procedure, the percutaneous extraction technique resulted in shorter hospitalization and an earlier return to prehospital activity.
Systems Approach Toward Implementation of a Multiassembly, Multilot-Size, Multitechnology, Manufacturing Facility

Abstract This paper deals with the systems engineering of an electronic packaging plant for printed-circuit cards. The facility is designed to efficiently and concurrently build an assortment of product part-number assemblies of differing complexities and of varying lot sizes. A flexible, manufacturing-system architecture with modular elements providing for rapid movement of individual units between operations is key to improved productivity. Component verification and visual inspection with closed-loop feedback are included in the system. The concept of shared physical queues is discussed as it relates to scheduling mixed assemblies into the line for optimal machine utilization with minimum time through the process. Various algorithms for optimizing machine setup, as well as an extensive modeling tool, are addressed.
Renal Syndromes in the Acquired Immunodeficiency Syndrome (AIDS): Lessons Learned From Analysis Over 5 Years

Renal syndromes associated with the Acquired immunodeficiency syndrome include: potentially reversible acute renal failure, AIDS associated nephropathy which leads to end stage renal disease, and AIDS developing in patients who are being treated by maintenance hemodialysis. The longitudinal study of 95 patients with AIDS and various forms of renal syndrome at two urban institutions indicates that both acute and chronic renal failure is increasing yearly. While some patients with acute renal failure recover renal function and survive for prolonged period, the mortality of dialyzed patients with irreversible renal failure continues to be unsatisfactory. There is a great need for collecting data from high risk areas to analyze the results of maintenance dialysis therapy in patients with AIDS, to assess the economic impact of uremia therapy, and for long-term planning of available resources.
Oral Estramustine Phosphate (Estracyt): A Broad Phase II Study

Thirty-five patients with advanced cancers were treated with estramustine phosphate tablets (Estracyt). Doses ranged between 420 mg and 700 mg daily. One partial response was documented in a hormone resistant prostatic cancer patient. Four minor responses (less than 50% responses, or less than one month more than 50% response) were obtained; one in a hormone resistant prostatic cancer, two in metastatic colorectal cancers; and another in a malignant melanoma. Toxicity phenomena included nausea (9/35 - 25%), water retention (4/35 - 11.5%) and mild elevation of alkaline phosphatase (2/35 - 6%). Other toxicity effects were vaginal bleeding in two women, acne in one woman and mild pruritus in another patient. Myelosuppression and immune suppression were not significantly detected.
Expert Knowledge-Based Traction Control of a Truck Using Fuzzy Logic

Abstract This paper describes a fuzzy logic (FL) approach for incorporating an expert knowledge-based Traction Control System (TCS) for a four-wheel drive vehicle. The knowledge base is provided by a survey of existing TCS methods, understanding of the TCS hardware components and tyre adhesion characteristics, evaluation of applicable control methods, computer simulation studies, and feedback information from experienced traction test drivers in the automotive industry. The developed FL-bascd TCS was implemented on a Pentium PC system- level traction controller computer installed on a 4x4 pickup truck. Extensive experiments for traction control was conducted at available test facilities and proving grounds. The system-level fuzzy logic approach readily permits modification of old and incorporation of new ideas. The success of this fuzzy logic-based design approach was demonstrated to the government sponsor and industrial partners.
FRICTION AND WEAR IN PHOSPHOLIPID POLYMER SURFACE-TREATED CERAMIC-ON-POLYETHYLENE TOTAL HIP REPLACEMENTS

To improve the longevity of total hip replacements (THR), it is necessary to prevent wear of the ultra-high molecular weight polyethylene (UHMWPE) bearing, as wear debris can cause osteolysis and aseptic loosening. Highly cross-linked UHMWPE reduces wear, sometimes stabilized with vitamin E to preserve its mechanical properties and prevent oxidative degeneration. An extra novel solution has been grafting the surface of UHMWPE with poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC). This treatment uses a hydrophilic (wettable) phospholipid polymer to improve lubrication and reduce friction and wear of the bearing material. We set out to test the wear and friction of ceramic-on-polyethylene (COP) THRs that had the PMPC surface treatment, or left untreated for control. Four groups of UHMWPE bearings were tested against identical 40mm ceramic heads (zirconia-toughened alumina). The UHMWPE bearings were highly cross-linked with/without vitamin E (HXL Vit. E: 125 kGy radiation dose / HXL: 75 kGy). In each group, half underwent the PMPC treatment (n = 3 for all four groups). Testing was conducted on an AMTI hip simulator for 10 million walking cycles of ISO-14242-1, at 1 Hz, with diluted bovine serum (30 g/L protein concentration) as lubricant, at 37oC, and with fluid absorption errors corrected with active soak controls. Using a previously published method, frictional torques and a frictional factor around three orthogonal axes about the femoral head were measured/computed, by data processing of the measurements of a 6-DOF load cell on each station of the hip simulator. Such friction measurements and stops for specimen weighing were carried out at regular intervals throughout the wear test. The HXL liners without and with the PMPC treatment wore at 5.86±0.402 mg/Mc and 1.70±1.36 mg/Mc, respectively (p=0.013) (Fig. 1). The HXL Vit. E liners without and with the PMPC treatment wore at 2.14±0.269 mg/Mc and 0.736±0.750 mg/Mc, respectively (p=0.035). The wear rates of the untreated HXL and HXL Vit. E liners were significantly different (p=0.0002) but no difference in wear rate was found between the two PMPC treated groups (p=0.179), although, as mentioned above, the PMPC treatment very significantly reduced wear in each case. The ceramic femoral heads showed little wear (weight loss) themselves. In general, the THRs showed decreasing friction over the 10 Mc, with the PMPC types showing a slight increase in friction towards the end of the test (Fig. 2). PMPC HXL liners showed the lowest friction factor (0.022±0.001) which was significantly lower (p PMPC successfully reduced both the friction and the wear in these COP THRs during this extended 10 Mc test. This likely would translate to improved implant longevity in patients. For any figures or tables, please contact authors directly (see Info & Metrics tab above).
Entrepreneurship and network externalities

Abstract Studies on agglomeration show that economic characteristics explain only a portion of variance in entrepreneurship rates across regions. To complement these studies, I argue that entrepreneurship tends to concentrate geographically, in part, because of the social environment. I suggest that, when making decisions, individuals follow social cues and are influenced by what others have chosen, especially when facing ambiguous situations. Such influence may be described as a non-pecuniary network externality. Using a non-linear path-dependent stochastic process, I build a model of entrepreneurial dynamics showing why communities with initially similar economic characteristics may end up with different levels of entrepreneurial activity.
Mapping spiral waves and other radial features in Saturn’s rings

Abstract We have analyzed the highest-quality images to be obtained by Cassini of Saturn’s main rings after the Saturn Orbit Insertion (SOI) and before the Ring Grazing Orbits (RGO) and Grand Finale (GF). These images are comparable to those of SOI in fidelity, though not in nominal resolution, due to their high signal-to-noise. We have systematically searched for radial structure in these images by reducing them to a single dimension (distance from Saturn’s center) and using the continuous wavelet transform technique. We discuss the resonant theory of spiral waves and discuss the proper method for deriving the local surface mass density from the wavelet signature of a spiral wave. We present 1) individual features of interest found in our data, including several classes of waves that have not previously been reported; 2) a radial profile of surface mass density in Saturn’s rings, which is more definitive for the A ring than any previously presented and which corrects some errors in previous profiles; and 3) an atlas of resonant features that indicates whether each feature is or is not expressed in the rings and that is organized graphically by resonance strength.
THE POST-OPERATIVE PAINFUL KNEE: DIAGNOSIS AND DELIVERANCE

TKA is one of the most common orthopaedic operations performed worldwide and it is largely successful in pain relief and functional recovery. However, when pain persists post-operatively the thorough evaluation must be instituted. Extra-articular causes of knee pain include; hip pathology, lumbar spine degenerative disease or radicular symptoms, focal neuropathy, vascular disease, and chronic regional pain syndrome. Intra-articular causes of knee pain: infection, crepitation/ clunk, patella osteonecrosis, patella mal-tracking, soft tissue imbalance, malalignment, arthrofibrosis, component loosening, implant wear, ilio-tibial band irritation, and bursitis. Other causes of pain to rule out are component overhang with soft tissue irritation, recurrent hemarthrosis secondary to synovial impingement or entrapment, non-resurfaced patella, and metal sensitivity. A careful history may reveal previous knee surgeries with delayed healing or prolonged drainage, chronology of sign and symptoms, co-morbid medical conditions, jewel or metal sensitivity. Physical exam should help with specific signs in the operated knee. Targeted local anesthetic blocks are helpful and response to lumbar sympathetic blocks determines presence of CRPS. Lab tests are important: ESR, CRP, WBC, aspiration with manual cell count and diff, leukocyte esterase dipstick, RA titers, metal derm patch testing, nuclear scans, CT best for rotational malalignment,, and MARS MRI. More recently patient satisfaction as an outcome measure has shown TKA results not satisfactory in 11 – 18% of patients. A discordance of patient vs. surgeon satisfaction exists so the following factors may help improve this: correct patient selection, establishing and correlating surgeon-patient expectations, peri-operative optimisation of patient comorbidities to help avoid preventable complications, use of pre- and post-operative pathways. Satisfaction rates can best be improved by addressing the previous points with patients prior to TKA surgery.
Vocational and Career Tech Education in American High Schools: The Value of Depth over Breadth.

Vocational education is a large part of the high school curriculum, yet we have little understanding of what drives vocational enrollment or whether these courses help or harm early careers. To add...
The Role of Costimulation Blockade in Solid Organ and Islet Xenotransplantation

Pig-to-human xenotransplantation offers a potential bridge to the growing disparity between patients with end-stage organ failure and graft availability. Early studies attempting to overcome cross-species barriers demonstrated robust humoral immune responses to discordant xenoantigens. Recent advances have led to highly efficient and targeted genomic editing, drastically altering the playing field towards rapid production of less immunogenic porcine tissues and even the discussion of human xenotransplantation trials. However, as these humoral immune barriers to cross-species transplantation are overcome with advanced transgenics, cellular immunity to these novel xenografts remains an outstanding issue. Therefore, understanding and optimizing immunomodulation will be paramount for successful clinical xenotransplantation. Costimulation blockade agents have been introduced in xenotransplantation research in 2000 with anti-CD154mAb. Most recently, prolonged survival has been achieved in solid organ (kidney xenograft survival > 400 days with anti-CD154mAb, heart xenograft survival > 900 days, and liver xenograft survival 29 days with anti-CD40mAb) and islet xenotransplantation (>600 days with anti-CD154mAb) with the use of these potent experimental agents. As the development of novel genetic modifications and costimulation blocking agents converges, we review their impact thus far on preclinical xenotransplantation and the potential for future application.
Economically Motivated Adulteration in Farming Supply Chains

Economically motivated adulteration (EMA) is a serious threat to public health. In this paper, we develop a modeling framework to examine farms’ strategic adulteration behavior and the resulting EM...
Nursing Home Regulations Redefined: Implications for Providers

The Centers for Medicare and Medicaid Services (CMS) finalized a comprehensive update to nursing home requirements of participation in October 2016. Nearly 10,000 public comments were received regarding the proposed rule, and CMS made multiple modifications based on comments from providers, advocacy organizations, and others before issuing the final rule. The final rule describing nursing home requirements of participation modernizes nursing home regulation. It is being implemented in three phases-beginning in November 2016, November 2017, and November 2019. There are multiple provisions that have implications for clinicians caring for nursing home residents, particularly in terms of management of infections, medication prescribing and monitoring, and delegation of medical orders.
Arabidopsis ACTIN-DEPOLYMERIZING FACTOR3 Is Required for Controlling Aphid Feeding from the Phloem

The actin cytoskeleton network has an important role in plant cell growth, division, and stress response. Actin-depolymerizing factors (ADFs) are a group of actin-binding proteins that contribute to reorganization of the actin network. Here, we show that the Arabidopsis (Arabidopsis thaliana) ADF3 is required in the phloem for controlling infestation by Myzus persicae Sulzer, commonly known as the green peach aphid (GPA), which is an important phloem sap-consuming pest of more than fifty plant families. In agreement with a role for the actin-depolymerizing function of ADF3 in defense against the GPA, we show that resistance in adf3 was restored by overexpression of the related ADF4 and the actin cytoskeleton destabilizers, cytochalasin D and latrunculin B. Electrical monitoring of the GPA feeding behavior indicates that the GPA stylets found sieve elements faster when feeding on the adf3 mutant compared to the wild-type plant. In addition, once they found the sieve elements, the GPA fed for a more prolonged period from sieve elements of adf3 compared to the wild-type plant. The longer feeding period correlated with an increase in fecundity and population size of the GPA and a parallel reduction in callose deposition in the adf3 mutant. The adf3-conferred susceptibility to GPA was overcome by expression of the ADF3 coding sequence from the phloem-specific SUC2 promoter, thus confirming the importance of ADF3 function in the phloem. We further demonstrate that the ADF3-dependent defense mechanism is linked to the transcriptional up-regulation of PHYTOALEXIN-DEFICIENT4, which is an important regulator of defenses against the GPA.
Diverse Pre-Treatment Effects in Survey Experiments

Researchers using survey experiments typically assume respondents are blank slates, encountering information for the first time. We study how prior real-world information dissemination through the mass media shapes experimental results. We show prior exposure can lead us to both under- and overestimate true framing effects in experiments. Message clarity moderates the impact of pre-treatment, with clear information more likely to produce pre-treatment effects than unclear information.
Base Transit Time in Abrupt GaN/InGaN/GaN and AlGaN/GaN/AlGaN HBTs

Base transit time, τb, in abrupt npn GaN/InGaN/GaN and AlGaN/GaN/AlGaN double heterojunction bipolar transistors (DHBTs) is reported. Base transit time strongly depends not only on the quasi-neutral base width, but also on the low field electron mobility, μn, in the neutral base region and the effective electron velocity, Sc, at the edge of base-collector heterojunction. μn and Sc are temperature-dependent parameters. A unity gain cut-off frequency of 10.6 GHz is obtained in AlGaN/GaN/AlGaN DHBTs and 19.1 GHz in GaN/InGaN/GaN DHBTs for a neutral base width of 0.05um. It is also shown that non-stationary transport is not required to study τb for neutral base width in the range of 0.05um for GaN-based HBTs.
Women and Migration

While scholars have long studied the economics of migration, increasing waves of international and regional migration around the world have placed greater focus on the varied impacts of migration in recent years. Critical to this line of research is an examination of the important role that women play in both sending and destination areas. This chapter addresses various aspects of the relationship between women and migration, including key ways in which non-migrant women are affected by migration, as well as how female migrants affect families and labor markets in both source and destination communities. Selection factors and determinants of female migration, as well as the gendered impacts of migrant networks, are also discussed.
The Crisis in Content Validity Among Existing Measures of Transphobia.

What might be suggested by Morrison et al.’s review of existing transphobia scales is that we should offer further methodological validation of the scales we already have. However, I would argue that, due to the particular crisis in content validity, this is not the answer. All the statistics in the world can’t redeem a scale that, at its most basic level, fails to reflect the construct it purports to measure. As such, what is needed is not the further statistical validation of existing measures, but the generation of entirely new measures developed on solid foundations of qualitative data assessing both the breadth and depth of current public attitudes (as I have done in the development and validation of the Attitudes Toward Transgender Men and Women scale [ATTMW]; Billard, 2018). And while Morrison et al.’s content validity criteria may provide methodological resources to lead us to greater content validity, these suggestions are not boxes to tick to say we have validity, nor even necessarily the best or only route to valid scale items. But one thing is certain: among all the issues Morrison et al. noted in their review, none is so grave as the crisis in content validity.
Optimal Segregation of Proteins: Phase Transitions and Symmetry Breaking.

Asymmetric segregation of key proteins at cell division---be it a beneficial or deleterious protein---is ubiquitous in unicellular organisms and often considered as an evolved trait to increase fitness in a stressed environment. Here, we provide a general framework to describe the evolutionary origin of this asymmetric segregation. We compute the population fitness as a function of the protein segregation asymmetry $a$, and show that the value of $a$ which optimizes the population growth manifests a phase transition between symmetric and asymmetric partitioning phases. Surprisingly, the nature of phase transition is different for the case of beneficial proteins as opposed to deleterious proteins: a smooth (second order) transition from purely symmetric to asymmetric segregation is found in the former, while a sharp transition occurs in the latter. Our study elucidates the optimization problem faced by evolution in the context of protein segregation, and motivates further investigation of asymmetric protein segregation in biological systems.
Ranking Forecasts by Stochastic Error Distance, Information and Reliability Measures

The stochastic error distance (SED) introduced by Diebold and Shin () ranks forecast models by divergence between distributions of the errors of the actual and perfect forecast models. The basic SED is defined by the variation distance and provides a representation of the mean absolute error, but by basing ranking on the entire error distribution and divergence, the SED moves beyond the traditional forecast evaluations. First, we establish connections between ranking forecast models by the SED, error entropy and some partial orderings of distributions. Then, we introduce the notion of excess error for forecast errors of magnitudes larger than a tolerance threshold and give the SED representation of the mean excess error (MEE). As a function of the threshold, the MEE is a local risk measure. With the distribution of the absolute error as a prior for the threshold, its Bayes risk is the entropy functional of the survival function, which is a known measure in the information theory and reliability. Notions and results are illustrated using various distributions for the error. The empirical versions of SED, MEE and its Bayes risk are compared with the mean squared error in ranking regression and autoregressive integrated moving average models for forecasting bond risk premia.
Using Temperature to Reduce Noise in Quantum Frequency Conversion

A main source of noise in quantum frequency conversion is spontaneous Raman scattering, which can be reduced by lowering the operating temperature. We show reduction in dark count rates that agrees well with theory.