cssi/SciSciGPT-SciSciNet huggingface dataset:
Dynamic Mechanisms with Martingale Utilities

We study the dynamic mechanism design problem of a seller who repeatedly sells independent items to a buyer with private values. In this setting, the seller could potentially extract the entire buyer surplus by running efficient auctions and charging an upfront participation fee at the beginning of the horizon. In some markets, such as internet advertising, participation fees are not practical since buyers expect to inspect items before purchasing them. This motivates us to study the design of dynamic mechanisms under successively more stringent requirements that capture the implicit business constraints of these markets. We first consider a periodic individual rationality constraint, which limits the mechanism to charge at most the buyer's value in each period. While this prevents large upfront participation fees, the seller can still design mechanisms that spread a participation fee across the first few auctions. These mechanisms have the unappealing feature that they provide close-to-zero buyer utility in earlier auctions in exchange for higher utility in later auctions. To address this problem, we introduce a {martingale utility constraint, which imposes the requirement that from the perspective of the buyer, the next item's expected utility is equal to the present one's. Our main result is providing a dynamic auction satisfying martingale utility and periodic individual rationality whose loss in profit with respect to first-best (full extraction of buyer surplus) is optimal up to polylogarithmic factors. The proposed mechanism is a dynamic two-tier auction with a hard floor and a soft floor that allocates the item whenever the buyer's bid is above the hard floor and charges the minimum of the bid and the soft floor.
Dysfunctional uterine bleeding in adolescents

This retrospective, multicenter analysis was conducted on all adolescents admitted to three pediatric hospitals in Montreal, Quebec, Canada, over a 10-year period (1981-1991) with a primary diagnosis of dysfunctional uterine bleeding. The purpose was to assess the frequency of underlying medical disorders and their response to medical therapy. Sixty-one patient charts were identified. Newly diagnosed hematologic abnormalities were found in two patients (one with immune thrombocytopenic purpura and one with acute promyelocytic leukemia). Furthermore, all patients who were evaluated had normal factor VIII levels, partial thromboplastin times and prothrombin times. Twenty-nine percent of the patients had a past history of a significant medical problem. The mean age at presentation was 13.8 +/- 2.1 (SD) years. More than 50% of the patients had a history of irregular bleeding. Most patients (93.4%) responded to medical management. Only five (8.2%) required dilation and curettage. The history of irregular cycles, the early presentation after menarche, the infrequency of hematologic problems but high frequency of significant medical problems led us to conclude that the etiology of dysfunctional uterine bleeding in adolescence is often related to persistent immaturity of the hypothalamic-pituitary-ovarian axis. Medical therapy is highly effective in controlling such bleeding. Dilation and curettage is rarely required.
Vpu is responsible for HIV-1 evasion of natural killer cells

August 20-22, 2012 N killer (NK) cells are recognized as being crucial in the defense against viruses. NK cells interaction with virus-infected cells ultimately leads to the death of the virus-infected cells. However, HIV-infected cells are refractory to lysis by NK cells. We have found that resistance to lysis is not due to the failure of HIV to activate NK cells but rather to HIV’s ability to prevent NK cell release of its lytic granules. These outcomes are the result of the combined action of viral proteins that both lead to NK activation but ultimately act to suppress the lytic function of NK cells. The key findings from our laboratories, demonstrate that: 1) HIV-1 Nef down modulates HLA-A and –B and 2) HIV-1 Vpr induces ligands to NK cell activation receptor NKG2D. Both of these events lead to NK cell activation. However, HIV-1 Vpu counters NK cells’ ability to degranulate by down modulation of NTB-A a homotypic ligand to the NK cell coactivation receptor, NTB-A. NTB-A on the infected cells is critical for eliciting NK cell cytolytic response because degranulation requires both simultaneous engagement of activation with coactivation receptors. Vpu acts to prevent NTB-A surface expression by retention of NTB-A within the trans-Golgi network of the infected cell. Vpu actions on NTB-A are independent of Vpu’s activity against CD4. Vpu acts on NTB-A in a similar fashion as Vpu mediated suppression of the host cell innate factor tetherin/BST-2. The ultimate goal will be to use the knowledge gained from studies on Vpu-NTB-A interactions to devise novel therapeutic approaches aimed at rendering HIV-infected cells sensitive to NK cell killing.
Do nuclear collisions create a locally equilibrated quark–gluon plasma?

Experimental results on azimuthal correlations in high energy nuclear collisions (nucleus–nucleus, proton–nucleus, and proton–proton) seem to be well described by viscous hydrodynamics. It is often argued that this agreement implies either local thermal equilibrium or at least local isotropy. In this note, I present arguments why this is not the case. Neither local near-equilibrium nor near-isotropy are required in order for hydrodynamics to offer a successful and accurate description of experimental results. However, I predict the breakdown of hydrodynamics at momenta of order seven times the temperature, corresponding to a smallest possible QCD liquid drop size of 0.15 fm.
The Impact of Emergency Department Census on the Decision to Admit

Objective We evaluated the effect of emergency department (ED) census on disposition decisions made by ED physicians. Methods We performed a retrospective analysis using 18 months of all adult patient encounters seen in the main ED at an academic tertiary care center. Patient census information was calculated at the time of physician assignment for each individual patient and included the number of patients in the waiting room (waiting room census) and number of patients being managed by the patient's attending (physician load census). A multiple logistic regression model was created to assess the association between these census variables and the disposition decision, controlling for potential confounders including Emergency Severity Index acuity, patient demographics, arrival hour, arrival mode, and chief complaint. Results A total of 49,487 patient visits were included in this analysis, of whom 37% were admitted to the hospital. Both census measures were significantly associated with increased chance of admission; the odds ratio (OR) per patient increase for waiting room census was 1.011 (95% confidence interval [CI] = 1.001 to 1.020), and the OR for physician load census was 1.010 (95% CI = 1.002 to 1.019). To put this in practical terms, this translated to a modeled rise from 35.3% to 40.1% when shifting from an empty waiting room and zero patient load to a 12-patient wait and 16-patient load for a given physician. Conclusion Waiting room census and physician load census at time of physician assignment were positively associated with the likelihood that a patient would be admitted, controlling for potential confounders. Our data suggest that disposition decisions in the ED are influenced not only by objective measures of a patient's disease state, but also by workflow-related concerns.
Understanding the Mechanisms of Deep Transfer Learning for Medical Images

The ability to automatically learn task specific feature representations has led to a huge success of deep learning methods. When large training data is scarce, such as in medical imaging problems, transfer learning has been very effective. In this paper, we systematically investigate the process of transferring a Convolutional Neural Network, trained on ImageNet images to perform image classification, to kidney detection problem in ultrasound images. We study how the detection performance depends on the extent of transfer. We show that a transferred and tuned CNN can outperform a state-of-the-art feature engineered pipeline and a hybridization of these two techniques achieves 20 % higher performance. We also investigate how the evolution of intermediate response images from our network. Finally, we compare these responses to state-of-the-art image processing filters in order to gain greater insight into how transfer learning is able to effectively manage widely varying imaging regimes.
A Continuous Model of Cortical Connectivity

We present a continuous model for structural brain connectivity based on the Poisson point process. The model treats each streamline curve in a tractography as an observed event in connectome space, here a product space of cortical white matter boundaries. We approximate the model parameter via kernel density estimation. To deal with the heavy computational burden, we develop a fast parameter estimation method by pre-computing associated Legendre products of the data, leveraging properties of the spherical heat kernel. We show how our approach can be used to assess the quality of cortical parcellations with respect to connectivty. We further present empirical results that suggest the “discrete” connectomes derived from our model have substantially higher test-retest reliability compared to standard methods.
Minimal models of compact symplectic semitoric manifolds

Abstract A symplectic semitoric manifold is a symplectic 4-manifold endowed with a Hamiltonian ( S 1 × R ) -action satisfying certain conditions. The goal of this paper is to construct a new symplectic invariant of symplectic semitoric manifolds, the helix, and give applications. The helix is a symplectic analogue of the fan of a nonsingular complete toric variety in algebraic geometry, that takes into account the effects of the monodromy near focus–focus singularities. We give two applications of the helix: first, we use it to give a classification of the minimal models of symplectic semitoric manifolds, where “minimal” is in the sense of not admitting any blowdowns. The second application is an extension to the compact case of a well known result of Vũ Ngọc about the constraints posed on a symplectic semitoric manifold by the existence of focus–focus singularities. The helix permits to translate a symplectic geometric problem into an algebraic problem, and the paper describes a method to solve this type of algebraic problem.
An analysis of instructional design and technology departments

In this paper we explore the academic productivity of universities in the field of Instructional Design and Technology according to three types of publically available data: (1) publication in 20 leading journals, (2) representation in the Handbook of Educational Communications Technology, and (3) reception of professional organization awards. We then identified five of these programs and analyzed the attributes of these departments to better understand the trends in how they are preparing the instructional technologists of tomorrow. While previous studies have compared leading instructional design and technology (IDT) programs by looking at publication in a single journal, we believe our approach provides a well-rounded perspective. In addition, we hope this study helps IDT departments learn from each other by discussing trends in department curricula.
New algorithms for maximizing cellular wireless network energy efficiency

In this paper, we aim to maximize the energy efficiency of cellular wireless networks. Specifically, we address the power allocation problem in multi-cell multi-carrier systems. Considering realistic base station power consumption models, we formulate a network-wide energy efficiency maximization problem. Using tools from fractional programming, we cast this problem in the framework of bi-criterion optimization where rate maximization and power minimization are weighted accordingly. Interference pricing mechanism is applied to reduce the inter-cell interference and to achieve a higher network performance. We decompose the main problem into subproblems via dual decomposition. These subproblems are independently solved per sector using limited information exchange between base stations. We first derive our expressions and present algorithms for the single-tier networks. Then, we extend our analysis to two-tier networks where picocell base stations are deployed to improve the network performance and reduce the link distances. Lastly, we extend our framework and include the quality-of-service constraints. We obtain closed-form expressions for the power level updates which are determined by the multi-level water-filling algorithm, or, as it is sometimes called as, the modified water-filling algorithm. Based on our simulation results, we demonstrate that the proposed algorithms can outperform the benchmark approaches in terms of energy efficiency by a factor of 2.7.
Dynamic thermal/acoustic response for human bone materials at different energy levels: A diagnosis approach.

Abstract Background The non-invasive diagnostic approaches have gained high attention in recent years, utilizing high technology sensor systems, including infrared, microwave devices, acoustic transducers, etc. The patient safety, high resolution images, and reliability are among the driving forces toward high technology approaches. The thermal and acoustic responses of the materials may reflect the important research parameters such as penetration depth, power consumption, and temperature change used for the practical models of the system. This paper emphasizes the approach for orthopedic application where the bone densities were considered in simulation to designate the type of human bones. Methods Thermal energy pulses were applied in order to study the penetration depth, the maximum temperature change; spatially and dynamically, and the acoustic pressure distribution over the bone thickness. The study was performed to optimize the amount of energy introduced into the materials that generate the temperature value for high resolution beyond the noise level. Results Three different energy pulses were used; 1 J, 3 J and 5 J. The thermal energy applied to the four bone materials, cancellous bone, cortical bone, red bone marrow, and yellow bone marrow were producing relative changes in temperature. The maximum change ranges from 0.5 K to 2 K for the applied pulses. The acoustic pressure also ranges from 210 to 220 dB among the various types of bones. Conclusion The results obtained from simulation suggest that a practical model utilizing infra-red scanning probe and piezoelectric devices may serve for the orthopedic diagnostic approach. The simulations for multiple layers such as skin interfaced with bone will be reserved for future considerations.
Zooming in: A practical manual for identifying geographic clusters

Research summary: This paper advances strategic management research by taking a close look at the reasons, procedures, and results of cluster identification methods, focusing on a density-based algorithm that organically define clusters from actual locations of economic activities. Despite being a popular research topic and analytical tool, geographic clusters are often studied with little consideration given to the underlying economic activities, the unique cluster boundaries, or the appropriate benchmark of economic concentration. Our goal is to increase awareness of the complexities behind cluster identification, and to provide concrete insights and methodologies applicable to various empirical settings. The method we propose is especially useful when researchers work in global settings, where data available at different geographic units complicates comparisons across countries. Managerial summary: Geographic proximity has been recognized as a fundamental factor driving firm performance, especially in knowledge-intensive industries. However, despite increasing interest in the study of geographic clusters—locations with a high concentration of economic activity—we as researchers have not given sufficient consideration to the underlying economic activity, the unique cluster boundaries, or even the definition of economic concentration. In this paper, we carefully examined the existing methodologies for cluster identification and proposed a method that defines clusters based on the actual location of economic activity. This new method is applicable to various empirical settings beyond geographic clusters. In addition, because clusters are defined by actual economic activity rather than administrative boundaries, it allows for meaningful comparison across countries. Copyright © 2015 John Wiley & Sons, Ltd.
The Digital Sin City: An Empirical Study of Craigslist's Impact on Prostitution Trends

Do solicitation sites lead to an increase in prostitution trends in United States? We shed light on this issue by examining the impact that Craigslist (via its Erotic Service section) has on prosti...
Penalized component hub models

Abstract Social network analysis presupposes that observed social behavior is influenced by an unobserved network. Traditional approaches to inferring the latent network use pairwise descriptive statistics that rely on a variety of measures of co-occurrence. While these techniques have proven useful in a wide range of applications, the literature does not describe the generating mechanism of the observed data from the network. In a previous article, the authors presented a technique which used a finite mixture model as the connection between the unobserved network and the observed social behavior. This model assumed that each group was the result of a star graph on a subset of the population. Thus, each group was the result of a leader who selected members of the population to be in the group. They called these hub models. This approach treats the network values as parameters of a model. However, this leads to a general challenge in estimating parameters which must be addressed. For small datasets there can be far more parameters to estimate than there are observations. Under these conditions, the estimated network can be unstable. In this article, we propose a solution which penalizes the number of nodes which can exert a leadership role. We implement this as a pseudo-Expectation Maximization algorithm. We demonstrate this technique through a series of simulations which show that when the number of leaders is sparse, parameter estimation is improved. Further, we apply this technique to a dataset of animal behavior and an example of recommender systems.
EXPANDING THE CATALOG: CONSIDERING THE IMPORTANCE OF CARBON, MAGNESIUM, AND NEON IN THE EVOLUTION OF STARS AND HABITABLE ZONES

Building on previous work, we have expanded our catalog of evolutionary models for stars with variable composition; here we present models for stars of mass 0.5–1.2 M⊙, at scaled metallicities of 0.1–1.5 Z⊙, and specific C/Fe, Mg/Fe, and Ne/Fe values of 0.58–1.72 C/Fe⊙, 0.54–1.84 Mg/Fe⊙, and 0.5–2.0 Ne/Fe⊙, respectively. We include a spread in abundance values for carbon and magnesium based on observations of their variability in nearby stars; we choose an arbitrary spread in neon abundance values commensurate with the range seen in other low Z elements due to the difficult nature of obtaining precise measurements of neon abundances in stars. As indicated by the results of Truitt et al., it is essential that we understand how differences in individual elemental abundances, and not just the total scaled metallicity, can measurably impact a star's evolutionary lifetime and other physical characteristics. In that work, we found that oxygen abundances significantly impacted the stellar evolution; carbon, magnesium, and neon are potentially important elements to individually consider due to their relatively high (but also variable) abundances in stars. We present 528 new stellar main-sequence models, and we calculate the time-dependent evolution of the associated habitable zone boundaries for each based on mass, temperature, and luminosity. We also reintroduce the 2 Gyr "Continuously Habitable Zone" (CHZ2) as a useful tool to help gauge the habitability potential for a given planetary system.
Polynomial Bounds for the Grid-Minor Theorem

One of the key results in Robertson and Seymour’s seminal work on graph minors is the grid-minor theorem (also called the excluded grid theorem). The theorem states that for every grid H, every graph whose treewidth is large enough relative to vV(H)v contains H as a minor. This theorem has found many applications in graph theory and algorithms. Let f(k) denote the largest value such that every graph of treewidth k contains a grid minor of size (f(k) × f(k)). The best previous quantitative bound, due to recent work of Kawarabayashi and Kobayashi, and Leaf and Seymour, shows that f(k)=Ω(√log k/log log k). In contrast, the best known upper bound implies that f(k) = O(√k/log k). In this article, we obtain the first polynomial relationship between treewidth and grid minor size by showing that f(k) = Ω(kδ) for some fixed constant δ > 0, and describe a randomized algorithm, whose running time is polynomial in vV(G)v and k, that with high probability finds a model of such a grid minor in G.
Cardiovascular consequences of metabolic syndrome

The metabolic syndrome (MetS) is defined as the concurrence of obesity-associated cardiovascular risk factors including abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, decreased HDL cholesterol, and/or hypertension. Earlier conceptualizations of the MetS focused on insulin resistance as a core feature, and it is clearly coincident with the above list of features. Each component of the MetS is an independent risk factor for cardiovascular disease and the combination of these risk factors elevates rates and severity of cardiovascular disease, related to a spectrum of cardiovascular conditions including microvascular dysfunction, coronary atherosclerosis and calcification, cardiac dysfunction, myocardial infarction, and heart failure. While advances in understanding the etiology and consequences of this complex disorder have been made, the underlying pathophysiological mechanisms remain incompletely understood, and it is unclear how these concurrent risk factors conspire to produce the variety of obesity-associated adverse cardiovascular diseases. In this review, we highlight current knowledge regarding the pathophysiological consequences of obesity and the MetS on cardiovascular function and disease, including considerations of potential physiological and molecular mechanisms that may contribute to these adverse outcomes.
LAXITY ENVELOPE BEFORE AND AFTER TKA: IS THERE A RELATIONSHIP BETWEEN THE CONTACT FORCES ON THE TIBIAL PLATEAU AND THE LAXITY OF THE KNEE AFTER SURGERY?

INTRODUCTION During TKA surgery, the usual goal is to achieve equal balancing between the lateral and medial side, which can be achieved by ligament releases or “pie crusting”. However little is known regarding a relationship between the balancing forces on the medial and lateral plateaus during TKA surgery, and the varus and valgus and rotational laxities when the TKA components are inserted. It seems preferable that the laxity after TKA is the same as for the normal intact knee. Hence the first aim of this study was to compare the laxity envelope of a native knee, with the same knee after TKA surgery. The second aim was to examine the relationship between the Varus-Valgus (VV) laxity and the contact forces on the tibial plateau. METHODS A special rig that reproduced surgical conditions and fit onto an operating table was designed (Figure 1) (Verstraete et al. 2015). The rig allows application of a constant varus/valgus moment, and an internal-external (IE) torque. A series of heel push tests under these loading conditions were performed on 12 non-arthritic half semibodies hip-to-toe cadaveric specimens. Five were used for method development. To measure laxities, the flexion angle, the VV and the IE angle were measured using a navigation system. After testing the native knee, a TKA was performed using the Journey II BCS implant, the navigation assuring correct alignments. Soft tissue balancing was achieved by measuring compressive forces on the lateral and medial condyles with an instrumented tibial trial (Orthosensor, Dania Beach, Florida). At completion of the procedure, the laxity tests were repeated for VV and IE rotation and the contact forces on the tibial plateau were recorded, for the full range of flexion. RESULTS The average of the varus-valgus and the IE laxity envelope is plotted for the native (yellow), the TKA (pink) and the overlap between the two (orange) (Figure 2). The average for six specimens of the contact force ratio (medial/medial+lateral force) during the varus and valgus test is plotted as a function of the laxity for each flexion angle (Figure 3). DISCUSSION The Journey II implant replicated the VV laxity of the native knee except for up to 3 degrees more valgus in high flexion. For the IE, the TKA was equal in internal rotation, but up to 5 degrees more constrained in varus in mid range. Plotting contact force ratio against VV laxity (figure 3), as expected during the varus test the forces were clustered in a 0.85–0.95 ratio, implying predominant medial force with likely lateral lift-off. For the valgus test, the force ratio is more spread out, with all the values below 0.6. This could be due to the different stiffness of the MCL and LCL ligaments which are stressed during the VV test. During both tests the laxity increases progressively with flexion angle. Evidently the geometry knee reproduces more lateral laxity at higher flexion as in the anatomic situation. For figures/tables, please contact authors directly.
Red flags in data: learning from failed data reuse experiences

This study examined the data reusers' failed or unsuccessful experience to understand what constituted reusers' failure. Learning from failed experiences is necessary to understand why the failure occurred and to prevent the failure or convert the failure to success. This study offers an alternative view on data reuse practices and provides insights for facilitating data reuse processes by eliminating core components of failure. From the interviews with 23 quantitative social science data reusers who had failed data reuse experiences, the study findings suggest: (a) ease of reuse, particularly the issue of access and interoperability, is the important initial condition for a successful data reuse experience; (b) understanding data through documentation may be less of an issue, at least for experienced researchers to make their data reuse unsuccessful, although the process can still be challenging; and (c) the major component of failed experience is the lack of support in reusing data, which emphasizes the need to develop a support system for data reusers.
Beam search for learning a deep Convolutional Neural Network of 3D shapes

This paper addresses 3D shape recognition. Recent work typically represents a 3D shape as a set of binary variables corresponding to 3D voxels of a uniform 3D grid centered on the shape, and resorts to deep convolutional neural networks (CNNs) for modeling these binary variables. Robust learning of such CNNs is currently limited by the small datasets of 3D shapes available - an order of magnitude smaller than other common datasets in computer vision. Related work typically deals with the small training datasets using a number of ad hoc, hand-tuning strategies. To address this issue, we formulate CNN learning as a beam search aimed at identifying an optimal CNN architecture - namely, the number of layers, nodes, and their connectivity in the network - as well as estimating parameters of such an optimal CNN. Each state of the beam search corresponds to a candidate CNN. Two types of actions are defined to add new convolutional filters or new convolutional layers to a parent CNN, and thus transition to children states. The utility function of each action is efficiently computed by transferring parameter values of the parent CNN to its children, thereby enabling an efficient beam search. Our experimental evaluation on the 3D ModelNet dataset demonstrates that our model pursuit using the beam search yields a CNN with superior performance on 3D shape classification than the state of the art.
Active Subspaces of Airfoil Shape Parameterizations

Design and optimization benefit from understanding the dependence of a quantity of interest (e.g., a design objective or constraint function) on the design variables. A low-dimensional active subsp...
Pneumococcal Pneumonia Requiring Hospitalization in US Children in the 13-Valent Pneumococcal Conjugate Vaccine Era.

Background. The impact of PCV13 on a number of clinical aspects of pneumococcal pneumonia (PP) in children has not been reported. We compared the serotype distribution, antibiotic susceptibility, and outcomes of children with PP 4 years before and 4 years after the introduction of PCV13. Methods. We identified patients ≤18 years with PP at 8 children's hospitals in the United States (2006-2014). Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory. Clinical and laboratory data were collected retrospectively. Annual pneumococcal pneumonia hospitalization rates per 100 000 admissions with 95% confidence intervals were calculated. Dichotomous variables were analyzed by χ2 test and continuous variables with Mann-Whitney U test. Results. A total of 377 patients with PP requiring hospitalization were identified. Hospitalization rates of PP decreased from 53.6 to 23.3 per 100000 admissions post PCV13 (P < .0001). Complicated PP rates also decreased (P < .0001). Need for intensive care, mechanical ventilation, and invasive procedure remained unchanged after the introduction of PCV13. Comorbidities were more common among children with uncomplicated than complicated pneumonia (52.2% vs. 22.5%, P < .001). Overall, PCV13 serotypes 19A, 3, 7F, and 1 caused 80% of PP. Hospitalization rates of PCV13 serotype pneumonia decreased from 47.2 to 15.7 per 100000 admissions post PCV13. In 2014, the most common serotypes were 3, 19A and 35B. Conclusions. PP requiring hospitalization significantly decreased in children after PCV13 introduction. Complicated PP rates decreased steadily in 2011-2014. PCV13 serotypes 19A and 3 were still responsible for half of the cases of PP in 2011-2014.
False-Positive Citations:

We describe why we wrote “False-Positive Psychology,” analyze how it has been cited, and explain why the integrity of experimental psychology hinges on the full disclosure of methods, the sharing o...
THE TWO-STAGE EXCHANGE, 70% OF THE TIME: TECHNIQUES AND TIMING

Two stage exchange treatment of the infected TKA involves two separate surgical procedures separated by an interval of several weeks of pathogen specific antibiotic therapy. The first stage involves removal of all of the infected arthroplasty components and any cement or foreign material, followed by aggressive debridement of nonviable bone and soft tissues. This is followed by placement of an antibiotic-laden spacer which may be either static (molded solid PMMA block) or mobile (shaped blocks or implants that allow knee motion). With both static and mobile spacers high local doses of antibiotic are delivered from the cement in addition to systemic antibiotic therapy usually employing an IV for around 6 weeks post debridement. The choice between static and mobile spacers is dictated by surgeon preference, soft tissue status (i.e. need for adjunctive muscle flaps), and by the severity of bone loss present with static spacers more likely to be used for more major soft tissue or bone defect cases. Mobile spacers have the advantage of allowing interval motion of the knee which may improve final range of motion. Static spacers usually require adjunctive brace or cast immobilization to prevent migration and bone damage. The second stage is performed at around 6 to 8 weeks after completion of systemic antibiotic therapy and preferably after normalization (or improvement) in laboratory indicators such as ESR and CRP. Routine repeat aspiration of all knees before reimplantation is not usual, but selective aspiration for culture may be helpful if concern exists that infection may still be present due to systemic signs, wound appearance or abnormal laboratory parameters. The second stage procedure involves removal of the antibiotic-laden spacer, repeat complete debridement of the knee, and insertion of revision knee components. Frequently adjunctive stems, blocks, cones or sleeves are needed to achieve adequate implant fixation due to associated bone loss. Careful attention to soft tissue balancing is required at the time of reimplantation in order to optimise motion and function while also avoiding laxity or maltracking. Two stage exchange remains the gold standard in North America for the management of infected TKA. While this method is used by some surgeons for all chronically infected TKA patients, it is employed even by most one stage exchange devotees when the infecting organism is unknown, infection involves a highly resistant or difficult to manage pathogen (i.e. fungal), is associated with a sinus track or marginal soft tissues, or in many cases of immunocompromised patients or those with multiple comorbidities.
Cosmological evolution of primordial black holes

Abstract The cosmological evolution of primordial black holes (PBHs) is considered. A comprehensive view of the accretion and evaporation histories of PBHs across the entire cosmic history is presented, with focus on the critical mass holes. The critical mass of a PBH for current era evaporation is M c r ∼ 5.1 × 10 14 g. Across cosmic time such a black hole will not accrete radiation or matter in sufficient quantity to hasten the inevitable evaporation, if the black hole remains within an average volume of the universe. The accretion rate onto PBHs is most sensitive to the mass of the hole, the sound speed in the cosmological fluid, and the energy density of the accreted components. It is not easy for a PBH to accrete the average cosmological fluid to reach 30 M ⊙ by z ∼ 0.1 , the approximate mass and redshift of the merging BHs that were the sources of the gravitational wave events GW150914 and GW151226. A PBH located in an overdense region can undergo enhanced accretion leading to the possibility of growing by many orders of magnitude across cosmic history. Thus, two merging PBHs are a plausible source for the observed gravitational wave events. However, it is difficult for isolated PBHs to grow to supermassive black holes (SMBHs) at high redshift with masses large enough to fit observational constraints.
FUNCTIONAL IMPROVEMENT AND PAIN RELIEF AFTER TOTAL JOINT ARTHROPLASTY

Purpose Total and partial joint arthroplasty has been clinically proven to successfully relieve pain and improve function in patients with hip and knee degenerative arthrosis. It has been shown that early return to ambulation correlates well with functional scores. Moreover, the benefits of reduced narcotic use are multi-fold and range from reduced risk of addiction, gastrointenstinal and cardiopulmonary side effects. Establishing realistic pre-operative expectations regarding functional improvement and pain control will nevertheless impact patient satisfaction. Thus, the purpose of this study was to establish safe, achievable and data-driven benchmarks for post-operative ambulation and pain control in patients undergoing elective total joint arthroplasty. Methods A retrospective chart review was performed for of all patients who underwent elective primary total or partial joint replacement by a single fellowship trained academic joint replacement surgeon from 2/1/2015 to 2/29/16. Patients under the age of 18 as well as those who underwent arthroplasty to treat a traumatic injury or to revise an arthroplasty were excluded. Charts were reviewed for the method of ambulation (no ambulation, wheelchair, assistive devices, no devices) and use of prescription pain medications by 6 weeks post-operatively. Results 82 patient undergoing elective primary arthroplasty were identified and included in the analysis. 38% of patients underwent TKA (31 of 82) and 62% of patients (51 of 82) underwent THA via the direct anterior approach. Post-operatively 63% (52 of 82) patients were ambulating without assist device. An additional 24% (20 of 82) of patients were ambulating with a single point assist device by 6 weeks. 77% (63 of 82) of patients were pain free by 6 weeks post operatively and denied taking any prescription pain medications. Conclusions Our analysis demonstrates that approximately 80% of patients undergoing elective total joint arthroplasty can be pain free without a need for prescription pain medication by 6 weeks post operatively. Moreover, while close to 90% of patients can expect to ambulate with at most , a single point assist, the majority (62%) can reliably expect to ambulate freely just 6 weeks after surgery. These results aid our understanding of post-operative return to function, and pain control. What is more, these data can inform a clinician in setting realistic, data-driven goals and expectations with patients undergoing elective total joint arthroplasty, thereby ultimately improving patient satisfaction with these commonly performed procedures.
A q-enumeration of lozenge tilings of a hexagon with four adjacent triangles removed from the boundary

Abstract MacMahon proved a simple product formula for the generating function of plane partitions fitting in a given box. The theorem implies a q -enumeration of lozenge tilings of a semi-regular hexagon on the triangular lattice. In this paper we generalize MacMahon’s classical theorem by q -enumerating lozenge tilings of a new family of hexagons with four adjacent triangles removed from their boundary.
EphB2 and EphB4 receptors forward signaling promotes SDF-1-induced endothelial cell chemotaxis and branching remodeling

AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA 2146 The complex molecular mechanisms that drive endothelial cell movement and the formation of new vessels are poorly understood and require further investigation. Eph receptor tyrosine kinases and their membrane-anchored ephrin ligands regulate cell movements mostly by cellâ\#8364;“cell contact, whereas the G-proteinâ\#8364;“ coupled receptor CXCR4 and its unique SDF-1 chemokine ligand regulate cell movement mostly through soluble gradients. By using biochemical and functional approaches, we investigated how ephrinB and SDF-1 orchestrate endothelial cell movement and morphogenesis into capillary-like structures. We describe how endogenous EphB2 and EphB4 signaling are required for the formation of extracellular matrixâ\#8364;“dependent capillarylike structures in primary human endothelial cells. We further demonstrate that EphB2 and EphB4 activation enhance SDF-1â\#8364;“induced signaling and chemotaxis that are also required for extracellular matrixâ\#8364;“dependent endothelial cell clustering. These results support a model in which SDF-1 gradients first promote endothelial cell clustering and then EphB2 and EphB4 critically contribute to subsequent cell movement and alignment into cordlike structures. This study reveals a requirement for endogenous Eph signaling in endothelial cell morphogenic processes, uncovers a novel link between EphB forward signaling and SDF-1â\#8364;“induced signaling, and demonstrates a mechanism for cooperative regulation of endothelial cell movement.
Confronting preferential sampling when analysing population distributions: diagnosis and model-based triage

Summary Population surveys are often used to estimate the density, abundance, or distribution of natural populations. Recently, model-based approaches to analyzing survey data have become popular because one can more readily accommodate departures from pre-planned survey routes and construct more detailed maps than one can with design-based procedures. Spatial models for population distributions often make the implicit assumption that locations chosen for sampling and animal abundance at those locations are conditionally independent given modeled covariates. However, this assumption may be violated when survey effort is non-randomized, leading to preferential sampling. We develop a hierarchical statistical modeling framework for detecting and alleviating the biasing effects of preferential sampling in spatial distribution models fitted to count data. The approach works by specifying a joint model for population density and the locations selected for sampling, and specifying a dependent correlation structure between the two processes. Using simulation, we show that moderate levels of preferential sampling can lead to large (e.g. 40%) bias in estimates of animal density and that our modeling approach can considerably reduce this bias. In contrast, preferential sampling did not appear to bias inferences about parameters informing species-habitat relationships (i.e. slope parameters). We apply our approach to aerial survey counts of bearded seals (Erignathus barbatus) in the eastern Bering Sea. As expected, models with a preferential sampling effect led to lower abundance than those without. However, several lines of reasoning (better predictive performance, higher biological realism) led us to prefer models without a preferential sampling effect for this data set. When population surveys break from traditional scientific survey design principles, ecologists should recognize the potentially biasing effects of preferential sampling when estimating population density or occurrence. Joint models, such as those described in this paper, can be used to test and correct for such biases. However, such models can be unstable; ultimately the best way to avoid preferential sampling bias is to incorporate design-based principles such as randomization and/or systematic sampling into survey design. This article is protected by copyright. All rights reserved.
Long-Range Dependence and Self-Similarity

This modern and comprehensive guide to long-range dependence and self-similarity starts with rigorous coverage of the basics, then moves on to cover more specialized, up-to-date topics central to current research. These topics concern, but are not limited to, physical models that give rise to long-range dependence and self-similarity; central and non-central limit theorems for long-range dependent series, and the limiting Hermite processes; fractional Brownian motion and its stochastic calculus; several celebrated decompositions of fractional Brownian motion; multidimensional models for long-range dependence and self-similarity; and maximum likelihood estimation methods for long-range dependent time series. Designed for graduate students and researchers, each chapter of the book is supplemented by numerous exercises, some designed to test the reader's understanding, while others invite the reader to consider some of the open research problems in the field today.
Decentralized Anonymous Micropayments

Micropayments (payments worth a few pennies) have numerous potential applications. A challenge in achieving them is that payment networks charge fees that are high compared to “micro” sums of money.
A Note on Perfect Correctness by Derandomization

We show a general compiler that transforms a large class of erroneous cryptographic schemes (such as public-key encryption, indistinguishability obfuscation, and secure multiparty computation schemes) into perfectly correct ones. The transformation works for schemes that are correct on all inputs with probability noticeably larger than half, and are secure under parallel repetition. We assume the existence of one-way functions and of functions with deterministic (uniform) time complexity \(2^{O(n)}\) and non-deterministic circuit complexity \(2^{\varOmega (n)}\).
Evaluation of Drinking Water Disinfectant Byproducts Compliance Data as an Indirect Measure for Short-Term Exposure in Humans

In the absence of shorter term disinfectant byproducts (DBPs) data on regulated Trihalomethanes (THMs) and Haloacetic acids (HAAs), epidemiologists and risk assessors have used long-term annual compliance (LRAA) or quarterly (QA) data to evaluate the association between DBP exposure and adverse birth outcomes, which resulted in inconclusive findings. Therefore, we evaluated the reliability of using long-term LRAA and QA data as an indirect measure for short-term exposure. Short-term residential tap water samples were collected in peak DBP months (May–August) in a community water system with five separate treatment stations and were sourced from surface or groundwater. Samples were analyzed for THMs and HAAs per the EPA (U.S. Environmental Protection Agency) standard methods (524.2 and 552.2). The measured levels of total THMs and HAAs were compared temporally and spatially with LRAA and QA data, which showed significant differences (p < 0.05). Most samples from surface water stations showed higher levels than LRAA or QA. Significant numbers of samples in surface water stations exceeded regulatory permissible limits: 27% had excessive THMs and 35% had excessive HAAs. Trichloromethane, trichloroacetic acid, and dichloroacetic acid were the major drivers of variability. This study suggests that LRAA and QA data are not good proxies of short-term exposure. Further investigation is needed to determine if other drinking water systems show consistent findings for improved regulation.
The importance of federal earmarks to state coffers: An examination of distribution trends over the decade

Earmarks have long been the subject of controversy, touted by pundits and politicians on one hand as the means for bringing home the bacon and on the other as pork-barrel spending. In relation to federal spending, the amount of annual earmarked dollars is insignificant; at its zenith in FY 2005 earmarked spending comprised only 6 percent of the year’s total appropriations. Yet preliminary research indicates that earmarks are an increasingly important source of funding for essential state services, such as infrastructure, social services, and economic development. Especially in times of fiscal stress, earmarks save state governments hundreds of millions of dollars in agency program funds and intergovernmental transfers. This study examines the congressional earmarks contained in appropriations legislation for FY 2000 through 2009 to assess trends in categorical distributions across and within the states during the period. The data illustrate a shift in allocations over the decade, from infrastructure, community development and environmental priorities to social and emergency services, higher education and energy needs.
Contextualizing Citations for Scientific Summarization using Word Embeddings and Domain Knowledge

Citation texts are sometimes not very informative or in some cases inaccurate by themselves; they need the appropriate context from the referenced paper to reflect its exact contributions. To address this problem, we propose an unsupervised model that uses distributed representation of words as well as domain knowledge to extract the appropriate context from the reference paper. Evaluation results show the effectiveness of our model by significantly outperforming the state-of-the-art. We furthermore demonstrate how an effective contextualization method results in improving citation-based summarization of the scientific articles.
Adaptive Classification for Prediction Under a Budget

We propose a novel adaptive approximation approach for test-time resource-constrained prediction motivated by Mobile, IoT, health, security and other applications, where constraints in the form of computation, communication, latency and feature acquisition costs arise. We learn an adaptive low-cost system by training a gating and prediction model that limits utilization of a high-cost model to hard input instances and gates easy-to-handle input instances to a low-cost model. Our method is based on adaptively approximating the high-cost model in regions where low-cost models suffice for making highly accurate predictions. We pose an empirical loss minimization problem with cost constraints to jointly train gating and prediction models. On a number of benchmark datasets our method outperforms state-of-the-art achieving higher accuracy for the same cost.