cssi/SciSciGPT-SciSciNet huggingface dataset:
The Potential Duration of Unemployment Benefits and the Duration of Unemployment

Western European countries with relatively generous unemployment insurance (UI) systems (such as Belgium, France, Germany, the Netherlands, and the UK) have suffered much larger and more persistent increases in unemployment in the 1980s than has the USA. These differences in West European and US unemployment experience are largely explained by the substantially longer duration of unemployment spells in Europe. Furthermore, much microeconomic evidence indicates that there is a positive relation between the level of UI benefits received and the duration of the unemployment spells of UI recipients.2 These observations have generated much interest among both academics (for example, Minford, 1985) and the press (for example The Economist, 14–20 May 1988, p. 69) in the hypothesis that work disincentives arising from generous unemployment insurance (UI) systems have played an important role in high and persistent European unemployment in the 1980s.
Ambient Sound Provides Supervision for Visual Learning

The sound of crashing waves, the roar of fast-moving cars – sound conveys important information about the objects in our surroundings. In this work, we show that ambient sounds can be used as a supervisory signal for learning visual models. To demonstrate this, we train a convolutional neural network to predict a statistical summary of the sound associated with a video frame. We show that, through this process, the network learns a representation that conveys information about objects and scenes. We evaluate this representation on several recognition tasks, finding that its performance is comparable to that of other state-of-the-art unsupervised learning methods. Finally, we show through visualizations that the network learns units that are selective to objects that are often associated with characteristic sounds.
Impacts of Dengue Epidemics on Household Labor Market Outcomes

Existing research on the economic impact of dengue among households focuses on individuals with clinically confirmed disease and their families. However, caregiving activities, avoidance behaviors, and changes in labor demand may cause the potential labor market impacts of an epidemic to extend beyond households that directly experience illness. I exploit exogenous fluctuations in the timing and scale of dengue epidemics in the Amazonian city of Iquitos, Peru from July 2005 to June 2010 to isolate changes in the work hours of all primary male and female residents in the region. I find that dengue epidemics are associated with large, statistically significant decreases in work hours for those who work positive hours. In aggregate, females reduce work hours more than males, both in levels of the point estimates and relative to mean hours. Furthermore, the decrease in female work hours during epidemics extends beyond households experiencing illness. This research contributes to the infectious disease literature by assessing the impact of epidemics on the labor market outcomes of all households in an affected region and by assessing the differential impacts on the outcomes of male and female residents.
The effects of bank and nonbank provider locations on household use of financial transaction services

Abstract We examine the influence that geographic proximity to bank branches and nonbank financial providers has on use of financial transaction services among U.S. households. We specify a bivariate probit model of bank account ownership and nonbank transaction product use to reflect the joint nature of these choices, and estimate the model on a large, nationally representative dataset. Our results indicate that households with reasonable geographic access to bank branches are more likely to have a bank account and less likely to use nonbank transaction products. The influence of bank and nonbank provider locations is fairly modest overall, although effects are bigger for households that are more likely to be on the margin of bank account ownership. Even among such households, however, the effects of bank and nonbank provider locations on financial transaction services use are not as large as those associated with key household-level attributes, such as income, education, or race.
The effects of minimum wages on the health of working teenagers

This article examines the effect of minimum wage increases on the self-reported health of teenage workers. We use a difference-in-differences estimation strategy and data from the Current Population Survey, and disaggregate the sample by race/ethnicity and gender to uncover the differential effects of changes in the minimum wage on health. We find that white women are more likely to report better health with a minimum wage increase while Hispanic men report worse health.
Incremental change in the set of coactive cortical assemblies enables mental continuity

This opinion article explores how sustained neural firing in association areas allows high-order mental representations to be coactivated over multiple perception-action cycles, permitting sequential mental states to share overlapping content and thus be recursively interrelated. The term "state-spanning coactivity" (SSC) is introduced to refer to neural nodes that remain coactive as a group over a given period of time. SSC ensures that contextual groupings of goal or motor-relevant representations will demonstrate continuous activity over a delay period. It also allows potentially related representations to accumulate and coactivate despite delays between their initial appearances. The nodes that demonstrate SSC are a subset of the active representations from the previous state, and can act as referents to which newly introduced representations of succeeding states relate. Coactive nodes pool their spreading activity, converging on and activating new nodes, adding these to the remaining nodes from the previous state. Thus, the overall distribution of coactive nodes in cortical networks evolves gradually during contextual updating. The term "incremental change in state-spanning coactivity" (icSSC) is introduced to refer to this gradual evolution. Because a number of associated representations can be sustained continuously, each brain state is embedded recursively in the previous state, amounting to an iterative process that can implement learned algorithms to progress toward a complex result. The longer representations are sustained, the more successive mental states can share related content, exhibit progressive qualities, implement complex algorithms, and carry thematic or narrative continuity. Included is a discussion of the implications that SSC and icSSC may have for understanding working memory, defining consciousness, and constructing AI architectures.
HERSCHEL OBSERVATIONS AND UPDATED SPECTRAL ENERGY DISTRIBUTIONS OF FIVE SUNLIKE STARS WITH DEBRIS DISKS

Observations from the Herschel Space Observatory have more than doubled the number of wide debris disks orbiting Sunlike stars to include over 30 systems with R > 100 AU. Here we present new Herschel PACS and re-analyzed Spitzer MIPS photometry of five Sunlike stars with wide debris disks, from Kuiper belt size to R > 150 AU. The disk surrounding HD 105211 is well resolved, with an angular extent of >14" along the major axis, and the disks of HD 33636, HD 50554, and HD 52265 are extended beyond the PACS PSF size (50% of energy enclosed within radius 4.23"). HD 105211 also has a 24-micron infrared excess that was previously overlooked because of a poorly constrained photospheric model. Archival Spitzer IRS observations indicate that the disks have small grains of minimum radius ~3 microns, though the minimum grain gradius is larger than the radiation pressure blowout size in all systems. If modeled as single-temperature blackbodies, the disk temperatures would all be <60 K. Our radiative transfer models predict actual disk radii approximately twice the radius of model blackbody disks. We find that the Herschel photometry traces dust near the source population of planetesimals. The disk luminosities are in the range 0.00002 <= L/L* <= 0.0002, consistent with collisions in icy planetesimal belts stirred by Pluto-size dwarf planets.
TOTAL KNEE REVISION: A DAY IN THE LIFE OF …

The designs available today have greatly improved our ability as surgeons to perform successful total knee revision surgery. However, as more and more knee replacements are in service for longer periods of time, the numbers of revisions have increased and have required us as surgeons to address challenging problems including infection, instability and bone loss from wear, osteolysis and loosening. Understanding the problems needed to be addressed is paramount. Careful preoperative planning is key. Knowing the cause of failure and the aspects of reconstruction that need to be addressed including skin, soft tissues, extensor mechanisms, bone and ligament loss is critical. Intraoperatively, understanding and applying principles related to establishing joint lines, balancing flexion extension gaps, addressing bone loss and ligament instability and constructing stable knee replacements with the use of stabilising implant articulations, bone deficiency reconstruction with augments and grafts as well as cones and sleeves, and stems for implant stability is also essential. Postoperatively, rehabilitation and follow-up must be tailored to the individual patient because of the marked nuances of construct in the various revision scenarios.
MARKETS, EXTERNALITIES, AND THE DYNAMIC GAINS OF OPENNESS

Inflows of foreign knowledge can be the key for developing countries to catch up with the world technology frontier. In this paper, I construct a simple tractable model to analyze (a) the incentives of foreign firms to bring their know-how to a developing country and (b) the incentives of domestic firms to invest in their own know-how. The model embeds the two mechanisms typically considered separately in the literature for the diffusion of knowledge: Externalities and Markets. The relative preponderance of these mechanisms significantly changes the dynamic implications of openness. Notably, openness allows developing countries to fully catch up only when market transactions fully dominate the diffusion of ideas. While externalities can also push domestic firms to upgrade their productivity, the equilibrium exposure to ideas in the country is always below the frontier and asymptotically the country would remain importing foreign know-how. However, in general, the dynamic gains of openness are substantial.
Marketing and Data Science: Together the Future is Ours

Author(s): Chintagunta, Pradeep; Hanssens, Dominique M; Hauser, John R | Abstract: The synergistic use of computer science and marketing science techniques offers the best avenue for knowledge development and improved applications. A broad area of complementarity between the typical focus in statistics and computer science and that in marketing offers great potential. The former fields tend to focus on pattern recognition, control and prediction. Many marketing analyses embrace these directions, but also contribute by modeling structure and exploring causal relationships. Marketing has successfully combined foci from management science with foci from psychology and economics. These fields complement each other because they enable a broad spectrum of scientific approaches. Combined, they provide both understanding and practical solutions to important and relevant managerial marketing problems, and marketing science is already very successful at obtaining unique insights from big data.
A coded shared atomic memory algorithm for message passing architectures

This paper considers the communication and storage costs of emulating atomic (linearizable) multi-writer multi-reader shared memory in distributed message-passing systems. The paper contains three main contributions: (1) we present an atomic shared-memory emulation algorithm that we call Coded Atomic Storage (CAS). This algorithm uses erasure coding methods. In a storage system with N servers that is resilient to f server failures, we show that the communication cost of CAS is $$\frac{N}{N-2f}$$NN-2f. The storage cost of CAS is unbounded. (2) We present a modification of the CAS algorithm known as CAS with garbage collection (CASGC). The CASGC algorithm is parameterized by an integer $$\delta $$ź and has a bounded storage cost. We show that the CASGC algorithm satisfies atomicity. In every execution of CASGC where the number of server failures is no bigger than f, we show that every write operation invoked at a non-failing client terminates. We also show that in an execution of CASGC with parameter $$\delta $$ź where the number of server failures is no bigger than f, a read operation terminates provided that the number of write operations that are concurrent with the read is no bigger than $$\delta $$ź. We explicitly characterize the storage cost of CASGC, and show that it has the same communication cost as CAS. (3) We describe an algorithm known as the Communication Cost Optimal Atomic Storage (CCOAS) algorithm that achieves a smaller communication cost than CAS and CASGC. In particular, CCOAS incurs read and write communication costs of $$\frac{N}{N-f}$$NN-f measured in terms of number of object values. We also discuss drawbacks of CCOAS as compared with CAS and CASGC.
On-chip cancellation of parasitic effects for dielectric permittivity measurement

A new approach for parasitic effects cancellation is proposed, analyzed, and experimentally evaluated. The method exploits the symmetry of the proposed test structures. It greatly improves measurement sensitivity for small dielectric permittivity changes. The experimental results agree well with theoretical and simulation results.
Kimura-finiteness of quadric fibrations over smooth curves

Abstract Making use of the recent theory of noncommutative mixed motives, we prove that the Voevodsky's mixed motive of a quadric fibration over a smooth curve is Kimura-finite.
Survivability in Time-Varying Networks

Time-varying graphs are a useful model for networks with dynamic connectivity such as vehicular networks, yet, despite their great modeling power, many important features of time-varying graphs are still poorly understood. In this paper, we study the survivability properties of time-varying networks against unpredictable interruptions. We first show that the traditional definition of survivability is not effective in time-varying networks, and propose a new survivability framework. To evaluate the survivability of time-varying networks under the new framework, we propose two metrics that are analogous to MaxFlow and MinCut in static networks. We show that some fundamental survivability-related results such as Menger's Theorem only conditionally hold in time-varying networks. Then, we analyze the complexity of computing the proposed metrics and develop approximation algorithms. Finally, we conduct trace-driven simulations to demonstrate the application of our survivability framework in the robust design of a real-world bus communication network.
Analysis of Packet Delay for an Integrated Voice-Data System

The performance of an integrated voice-data system using a movable boundary multi-plexing scheme is analyzed. In this scheme, channel time is divided into slots, grouped into equal length frames. A voice call arriving in a slot is served in the next frame, whereas a data packet is served in the next available slot. Voice calls are blocked calls cleared, while data packets may be buffered. Our approach is based on a discrete-time queueing model with periodic interruptions. An exact analysis of the average delay for data packets is given. The bounds of this delay time are also discussed.
The Effects of Single-sex Mathematics Classrooms on African-American Males in the Ninth Grade

High dropout rates and poor academic performance are frequent characteristics of the educational experience for African-American male youths (Bailey & Paisley, 2004). With increased accountability standards to raise the academic achievement levels, single-sex educational environments have taken a central role in school reform agendas and initiatives in many school districts (Herr & Arms, 2004). The incorporation of a single-sex grouping served as a conduit for teachers to deliver instruction based on the varied learning styles of the students. This study was designed to determine the effect single-sex classroom instruction has on African American males’ achievement in ninth-grade mathematics compared to that of the other student groups. The researcher investigated a public school in a North Texas school district that offered alternative educational options for the students. Single-sex classrooms were created in mathematics. Teachers taught single-sex classes of students from varied ethnic backgrounds during at least one double-blocked period each day. Ex post facto data were analyzed. An independent samples t-test and a two-way factorial Analysis of Variance (ANOVA) were utilized to test each hypothesis to determine whether significant differences existed in the scale scores of comparison groups on state-mandated assessments over a period of 3 years. The instrument used to measure academic achievement is the Texas Assessment of Knowledge and Skills. This study found that the mathematics scores of African American males in single-sex classes did not significantly differ from the scores of African American males in coeducational classes. The scores for the males in single-sex classes were slightly higher than that of males in coeducational classes at each grade level throughout the 3-year period. The mathematics scores of African American females in single-sex learning environments were not significantly different than those of African American males in single-sex classes. The scores for the female students were consistently higher throughout the 3-year period. This study identified the need for single-sex instructional opportunities for students as a means of eliminating the achievement gap.
A dual-modality optical coherence tomography and selective plane illumination microscopy system for mouse embryonic imaging

Both optical coherence tomography (OCT) and selective plane illumination microscopy (SPIM) are frequently used in mouse embryonic research for high-resolution three-dimensional imaging. However, each of these imaging methods provide a unique and independent advantage: SPIM provides morpho-functional information through immunofluorescence and OCT provides a method for whole-embryo 3D imaging. In this study, we have combined rotational imaging OCT and SPIM into a single, dual-modality device to image E9.5 mouse embryos. The results demonstrate that the dual-modality setup is able to provide both anatomical and functional information simultaneously for more comprehensive tissue characterization.
CAUSES OF HIP INSTABILITY: AN ALGORITHMIC APPROACH TO TREATMENT

Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. At our center, we have tried to approach the unstable hip by identifying the primary cause of instability and correcting that at the time of revision surgery. Type 1: Malposition of the acetabular component treated with revision of the acetabular component and upsizing the femoral head. Type 2: Malposition of the femoral component treated with revision of the femur and upsizing the femoral head. Type 3: Abductor deficiency treated with a constrained liner or dual mobility bearing. Type 4: Soft tissue or bony impingement treated with removal of impingement sources and upsizing the femoral head. Type 5: Late wear of the bearing treated with bearing surface exchange and upsizing the femoral head. Type 6: Unclear etiology treated with a constrained liner or dual mobility articulation. The most common etiologies of instability in our experience include cup malposition (Type 1) and abductor deficiency (Type 3). We reviewed 75 hips revised for instability and at a mean 35.3 months 11 re-dislocations occurred (14.6%). Acetabular revisions were protective against re-dislocation (p Although instability can be multifactorial, by identifying the primary cause of instability, a rational approach to treatment can be formulated. In general the poorest results were seen in patients with abductor deficiency. Given the high rate of failure of constrained liners (9 of the 11 failures were constrained), we currently are exploring alternatives such as dual mobility articulations.
Why only hole conductors can be superconductors

The conventional theory of superconductivity says that charge carriers in a metal that becomes superconducting can be either electrons or holes. I argue that this is incorrect. In order to satisfy conservation of mechanical momentum and of entropy of the universe in the superconductor to normal transition in the presence of a magnetic field it is necessary that the normal state charge carriers are holes. I will also review the empirical evidence in favor of the hypothesis that all superconductors are hole superconductors, and discuss the implications of this for the search for higher Tc superconductors.
Interaction of oxygen interstitials with lattice faults in Ti

Abstract Oxygen greatly affects the mechanical properties of titanium. In addition, dislocations and twin boundaries influence the plastics deformation of hexagonal close-packed metals. As part of a systematic study of defects interactions in Ti, we investigate the interactions of oxygen with ( 10 1 ¯ 2 ) twin boundaries and ( 10 1 ¯ 0 ) prism plane stacking faults. The energetics of four interstitial sites in the twin geometry are compared with the bulk octahedral site. We show that two of these sites located at the twin boundary are more attractive to oxygen than bulk, while the sites away from the boundary are repulsive. Moreover, we study the interaction of oxygen with the prismatic stacking fault to approximate oxygen–dislocation interaction. We show that oxygen increases the stacking fault energy and therefore is repelled by the faulted geometry and consequently a dislocation core.
Computing in Memory With Spin-Transfer Torque Magnetic RAM

In-memory computing is a promising approach to addressing the processor-memory data transfer bottleneck in computing systems. We propose spin-transfer torque compute-in-memory (STT-CiM), a design for in-memory computing with spin-transfer torque magnetic RAM (STT-MRAM). The unique properties of spintronic memory allow multiple wordlines within an array to be simultaneously enabled, opening up the possibility of directly sensing functions of the values stored in multiple rows using a single access. We propose modifications to STT-MRAM peripheral circuits that leverage this principle to perform logic, arithmetic, and complex vector operations. We address the challenge of reliable in-memory computing under process variations by extending error-correction code schemes to detect and correct errors that occur during CiM operations. We also address the question of how STT-CiM should be integrated within a general-purpose computing system. To this end, we propose architectural enhancements to processor instruction sets and on-chip buses that enable STT-CiM to be utilized as a scratchpad memory. Finally, we present data mapping techniques to increase the effectiveness of STT-CiM. We evaluate STT-CiM using a device-to-architecture modeling framework, and integrate cycle-accurate models of STT-CiM with a commercial processor and on-chip bus (Nios II and Avalon from Intel). Our system-level evaluation shows that STT-CiM provides the system-level performance improvements of 3.93 times on average (up to 10.4 times), and concurrently reduces memory system energy by 3.83 times on average (up to 12.4 times).
Intrinsic accuracy in 3-dimensional photoemission band mapping

Abstract Fundamental principles of mapping 3-dimensional quasiparticle dispersions in the valence band using angle-resolved photoemission spectroscopy are discussed. Such mapping is intrinsically limited in accuracy owing to damping of the final states, resulting in equivalent broadening in the surface-perpendicular wavevector. Mechanisms of the intrinsic accuracy are discussed in depth based on a physically transparent picture involving interplay of the final- and initial-state spectral functions, and illustrated by photoemission simulations and experimental examples. Other interesting effects of 3-dimensional dispersions include ‘ghost’ photoemission peaks outside the Fermi surface and finite peak width at the Fermi level. Finally, optimization of the experiment on the intrinsic accuracy is discussed.
Probabilistic database summarization for interactive data exploration

We present a probabilistic approach to generate a small, query-able summary of a dataset for interactive data exploration. Departing from traditional summarization techniques, we use the Principle of Maximum Entropy to generate a probabilistic representation of the data that can be used to give approximate query answers. We develop the theoretical framework and formulation of our probabilistic representation and show how to use it to answer queries. We then present solving techniques and give three critical optimizations to improve preprocessing time and query accuracy. Lastly, we experimentally evaluate our work using a 5 GB dataset of flights within the United States and a 210 GB dataset from an astronomy particle simulation. While our current work only supports linear queries, we show that our technique can successfully answer queries faster than sampling while introducing, on average, no more error than sampling and can better distinguish between rare and nonexistent values.
Frequency Dependence of Resonant Tunneling

The time scale in coherent resonant tunneling is investigated by calculating the Ohmic conductance versus frequency, in one-dimensional single-electron terms, for a resonant-tunneling diode. When the Fermi level is at the resonance energy, the conductance rolls off near the frequency equal to (resonance width)/(Planck’s constant). However, for a non-symmetrical diode structure it first rises to a sharp peak. When the Fermi level is displaced from the resonance energy, there is a conductance peak before roll off for both symmetical and non-symmetrical structures, with a peak frequency then approximately equivalent to the Fermi level displacement. At high frequencies, all cases coincide in a universal curve. For the overall three-dimensional diode, in the symmetrical case there is no frequency dependence on the resonance-width scale. The effect of the screening due to the space charge is investigated.
On the Capacity Requirement for Arbitrary End-to-End Deadline and Reliability Guarantees in Multi-hop Networks

It has been shown that it is impossible to achieve both stringent end-to-end deadline and reliability guarantees in a large network without having complete information of all future packet arrivals. In order to maintain desirable performance in the presence of uncertainty of future packet arrivals, common practice is to add redundancy by increasing link capacities. This paper studies the amount of capacity needed to provide stringent performance guarantees and propose a low-complexity online algorithm. Without adding redundancy, we further propose a low-complexity order-optimal online policy for the network.
Unsupervised action proposal ranking through proposal recombination

Abstract Recently, action proposal methods have played an important role in action recognition tasks, as they reduce the search space dramatically. Most unsupervised action proposal methods tend to generate hundreds of action proposals which include many noisy, inconsistent, and unranked action proposals, while supervised action proposal methods take advantage of predefined object detectors (e.g., human detector) to refine and score the action proposals, but they require thousands of manual annotations to train. Given the action proposals in a video, the goal of the proposed work is to generate a few better action proposals that are ranked properly. In our approach, we first divide action proposal into sub-proposal and then use Dynamic Programming based graph optimization scheme to select the optimal combinations of sub-proposals from different proposals and assign each new proposal a score. We propose a new unsupervised image-based actionness detector that leverages web images and employs it as one of the node scores in our graph formulation. Moreover, we capture motion information by estimating the number of motion contours within each action proposal patch. The proposed method is an unsupervised method that neither needs bounding box annotations nor video level labels, which is desirable with the current explosion of large-scale action datasets. Our approach is generic and does not depend on a specific action proposal method. We evaluate our approach on several publicly available trimmed and untrimmed datasets and obtain better performance compared to several proposal ranking methods. In addition, we demonstrate that properly ranked proposals produce significantly better action detection as compared to state-of-the-art proposal based methods.
A unified internal model theory to resolve the paradox of active versus passive self-motion sensation

When seated in a car, we can detect when the vehicle begins to move even with our eyes closed. Structures in the inner ear called the vestibular, or balance, organs enable us to sense our own movement. They do this by detecting head rotations, accelerations and gravity. They then pass this information on to specialized vestibular regions of the brain. Experiments using rotating chairs and moving platforms have shown that passive movements – such as car journeys and rollercoaster rides – activate the brain’s vestibular regions. But recent work has revealed that voluntary movements – in which individuals start the movement themselves – activate these regions far less than passive movements. Does this mean that the brain ignores signals from the inner ear during voluntary movements? Another possibility is that the brain predicts in advance how each movement will affect the vestibular organs in the inner ear. It then compares these predictions with the signals it receives during the movement. Only mismatches between the two activate the brain’s vestibular regions. To test this theory, Laurens and Angelaki created a mathematical model that compares predicted signals with actual signals in the way the theory proposes. The model accurately predicts the patterns of brain activity seen during both active and passive movement. This reconciles the results of previous experiments on active and passive motion. It also suggests that the brain uses similar processes to analyze vestibular signals during both types of movement. These findings can help drive further research into how the brain uses sensory signals to refine our everyday movements. They can also help us understand how people recover from damage to the vestibular system. Most patients with vestibular injuries learn to walk again, but have difficulty walking on uneven ground. They also become disoriented by passive movement. Using the model to study how the brain adapts to loss of vestibular input could lead to new strategies to aid recovery.
A parallel algorithm for the maximal path problem

In this paper we present anO (log5 n) time parallel algorithm for constructing a Maximal Path in an undirected graph. We also give anO (log1/2+e) time parallel algorithm for constructing a depth first search tree in an undirected graph.
How (Not) to Allocate Affordable Housing

We consider a setting in which agents and items match dynamically over time. We show that repeated independent lotteries with unlimited entry (which are commonly used in practice) encourage agents to enter many lotteries, and may result in low match value. We consider three alternate mechanisms: allowing agents to save unused tickets, limiting agents to entering at most one lottery, and allocating developments using a waiting list. We show that these three mechanisms are equivalent: for each agent, the probability of matching and expected value conditioned on matching are identical. Compared to a repeated lottery, these mechanisms result in higher-quality matches for matched agents. However, in some cases, a repeated lottery is more likely to match agents with the worst outside options, and thus may outperform the other mechanisms in terms of utilitarian welfare. We discuss the implications of these findings for two systems in New York City that currently use a repeated lottery: the allocation of affordable housing and of discounted tickets to broadway shows.
Mars double-aeroflyby free returns

Abstract Mars double-flyby free-return trajectories that pass twice through the Martian atmosphere are documented. This class of trajectories is advantageous for potential Mars atmospheric sample return missions because of its low geocentric energy at departure and arrival, because it would enable two sample collections at unique locations during different Martian seasons, and because of its lack of deterministic maneuvers. Free return opportunities are documented over Earth departure dates ranging from 2015 through 2100, with viable missions available every Earth-Mars synodic period. After constraining the maximum lift-to-drag ratio to be less than one, the minimum observed Earth departure hyperbolic excess speed is 3.23 km/s, the minimum Earth atmospheric entry speed is 11.42 km/s, and the minimum round-trip flight time is 805 days. An algorithm using simplified dynamics is developed along with a method to derive an initial estimate for trajectories in a more realistic dynamic model. Multiple examples are presented, including free returns that pass outside and inside of Mars's appreciable atmosphere.
ELLIPSOID ZONE MAPPING AND OUTER RETINAL ASSESSMENT IN STARGARDT DISEASE.

PURPOSE To quantify and correlate ellipsoid zone and photoreceptor outer segment changes with visual acuity in Stargardt disease. METHODS An institutional review board-approved study of 32 eyes with Stargardt disease was performed. After spectral domain optical coherence tomography, the macular cube was exported into a novel analysis tool and volumetric assessment from the ellipsoid zone to the retinal pigment epithelium was performed. Using this information, mapping was completed with en face representation of the height between the ellipsoid zone and retinal pigment epithelium. This analysis provided quantification of ellipsoid zone and photoreceptor outer segments, including atrophy (ellipsoid zone to retinal pigment epithelium thickness = 0 μm) and attenuation (ellipsoid zone to retinal pigment epithelium thickness <20 μm). These parameters were compared with visual acuity and controls (n = 12 eyes). RESULTS Visual acuity ranged from 20/30 to 20/250. The central foveal B-scan area of ellipsoid and photoreceptor outer segments was significantly less than controls (0.13 ± 0.05 mm vs. 0.17 ± 0.03 mm, respectively, P = 0.0074). The central foveal B-scan mean thickness measured 22.52 ± 9.0 μm in Stargardt versus 30.0 ± 5.08 μm (P = 0.0096). Atrophy and attenuation were significantly higher in Stargardt patients (22% vs. 1%, P = 0.005 and 43% vs. 1%, P = 0.0002). Visual acuity directly correlated with ellipsoid zone/outer segment volume (R = 0.57, P < 0.005) and inversely correlated with attenuation and atrophy (R = -0.53 and -0.57; P < 0.005 for all). CONCLUSION Eyes with Stargardt disease frequently have significant disruption of the ellipsoid zone and outer segments. This degenerative change was successfully quantified with a novel assessment platform and identified correlates with visual function. This software provides the opportunity for quantitative assessment and possible longitudinal surveillance.
Nonlinear Kalman filtering for censored observations

Abstract The use of Kalman filtering, as well as its nonlinear extensions, for the estimation of system variables and parameters has played a pivotal role in many fields of scientific inquiry where observations of the system are restricted to a subset of variables. However in the case of censored observations, where measurements of the system beyond a certain detection point are impossible, the estimation problem is complicated. Without appropriate consideration, censored observations can lead to inaccurate estimates. Motivated by previous work on censored filtering in linear systems, we develop a modified version of the extended Kalman filter to handle the case of censored observations in nonlinear systems. We validate this methodology in a simple oscillator system first, showing its ability to accurately reconstruct state variables and track system parameters when observations are censored. Finally, we utilize the nonlinear censored filter to analyze censored datasets from patients with hepatitis C and human immunodeficiency virus.
Dynamic Pricing for Heterogeneous Time-Sensitive Customers

Problem definition: A core problem in the area of revenue management is pricing goods in the presence of strategic customers. We study this problem when customers are heterogeneous with respect to ...
Increased Pyrophosphate Rib Uptake: Clinical Correlation

Two hundred and thirty-one patients had 270 bone scans. Increased rib uptake was correlated with radiological findings. Interpretation of results whether due to benign or to metastatic disease depends on other observations. These include whether the uptake is localized or along the rib outline, single or multiple, and associated with other abnormal uptake in the rest of the skeleton. Abnormal rib uptake was encountered in 23% of patients scanned for malignant disease and 10% of patients scanned for benign conditions. In the first group 34% were true positive and of these, rib lesions were multiple in 32% and solitary in 2%. In 20% the rib uptake was due to benign conditions and in 46% it was indefinite because of absent radiological findings. In this last difficult group 17% were due to probably early rib metastases and 29% were due to benign causes. Rib metastases were missed in only two cases, 1.1%. One case was multiple myeloma and the other was direct extension from underlying anaplastic lung carcinoma.
Outpatient Endourologic Procedures

Many endourologic procedures can be performed routinely on an outpatient basis, including flexible cystoscopy, ureterorenoscopy, and percutaneous nephroscopy through a mature tract. Others, such as percutaneous nephrostomy, nephrostolithotomy, and antegrade ureteral stent placement, can sometimes be done on an outpatient basis. This article describes the indications, techniques, postoperative care, and results of these procedures.
Throughput-Optimal Multi-Hop Broadcast Algorithms

We design throughput-optimal dynamic broadcast algorithms for multi-hop networks with arbitrary topologies. Most of the previous broadcast algorithms route packets along spanning trees. For large time-varying networks, computing and maintaining a set of spanning trees is not efficient, as the network-topology may change frequently. In this paper, we design a class of dynamic algorithms, which make simple packet-by-packet scheduling and routing decisions, and hence obviate the need for maintaining any global topological structures, such as spanning trees. Our algorithms may be conveniently understood as a non-trivial generalization of the familiar back-pressure algorithm for unicast traffic, which performs packet routing and scheduling based on queue lengths. However, in the broadcast setting, due to packet duplications, it is difficult to define appropriate queuing structures. We design and prove the optimality of a virtual queue-based algorithm, where virtual queues are defined for subsets of nodes. We then propose a multi-class broadcast policy, which combines the above scheduling algorithm with in-class-in-order packet forwarding, resulting in significant reduction in complexity. Finally, we evaluate the performance of the proposed algorithms via extensive numerical simulations.
Preoperative and Postoperative Medical Evaluation of Surgical Patients

Summary The purpose of this study was to analyze the cost-benefit of routine preoperative and postoperative medical evaluation of surgical patients. We analyzed the records of 70 patients who underwent selected common general and vascular surgical procedures according to their surgical risk, and assessed the potential change in outcome from medical evaluation. Our findings suggest that for low-risk surgical patients undergoing these procedures, medical evaluation is unlikely to affect outcome and, thus, may be unnecessary. There appears to be some benefit, however, for medium-risk surgical patients. Although we do not suggest the abolishment of all preoperative and postoperative medical evaluations, we do recommend the much more selective use of this valuable resource. Our data suggest that significant improvement in efficiency for many hospitals may be possible by omitting routine preoperative and postoperative medical evaluation for certain patients and by obtaining medical evaluation only in selected medium and higher risk surgical patients (ASA class 3 and above).
Renal Calcification Incidence in Very Low Birth Weight Infants

Serial ultrasound examinations were performed on 31 neonates with birth weights of less than 1,500 g for the detection of renal calcifications. Renal calcifications occurred in 20 (64%) of the infants at a mean age of 39.3 +/- 26.7 days of life. Infants with renal calcifications had shorter gestations (28.2 +/- 1.8 v 31 +/- 1.4 weeks, P less than .004) and lighter birth weights (924 +/- 195 v 1,338 +/- 100 g, P less than .004) than those infants without renal calcifications (n = 11). Furosemide administration was more common in the infants with renal calcifications (65% v 9.1%, P less than .001). The mean total dose of furosemide administered before renal calcifications were noted was 9.59 +/- 7.25 mg/kg. The 20 neonates with renal calcifications had a mean urine calcium level of 12.0 +/- 6.8 mg/kg/24 hours, mean urine calcium to creatinine ratio of 1.32 +/- 1.03 (range 0.3 to 4.45), and a mean alkaline phosphatase concentration of 961 +/- 327 IU. Initial parathyroid hormone levels were not different between the two groups, and subsequent determinations in infants with renal calcifications did not differ significantly from initial values. Renal calcifications are fairly common among very low birth weight infants, particularly in those receiving supplemental calcium and furosemide therapy. Although long-term implications of such findings are not known, close monitoring of renal function by serial determinations of urine calcium and urine calcium to creatinine ratios may identify those infants at risk for renal calcifications.
Ureteral Involvement Secondary to Diverticulitis of the Colon

Ureteral involvement in instances of diverticulitis of the colon is quite unusual. The left ureter is more commonly involved but right sided and bilateral instances have been reported. There are three types of involvement: fistula, stricture and compression, the latter being the most frequent. Roentgenographic characteristics and the effects of various treatment modalities on the affected ureter are presented herein.
Factors associated with child passenger motorcycle helmet use in Cambodia.

ABSTRACTThis study examines factors associated with child passenger helmet use in five Cambodian provinces. We performed an analysis of periodic roadside observations of helmet use over a four-year period. A total of 62,039 child passengers 12 years of age and younger met inclusion criteria and were included in the analysis. Overall, 1369 (2.1%) of child passengers were observed to be wearing a helmet. Most significantly, children were six times more likely to wear a helmet if the driver was wearing a helmet (OR 6.2; 95% CI 5.1–7.5). In addition, the odds of helmet use were noted to be significantly different depending on province, day of the week, time of day and number of passengers on the motorcycle. This study highlights the extremely low rate of child passenger helmet use in Cambodia, and provides priorities for interventions and enforcement to ensure all children are protected from head injury.
Unsupervised Extraction of Stable Expression Signatures from Public Compendia with an Ensemble of Neural Networks

Cross-experiment comparisons in public data compendia are challenged by unmatched conditions and technical noise. The ADAGE method, which performs unsupervised integration with denoising autoencoder neural networks, can identify biological patterns, but because ADAGE models, like many neural networks, are over-parameterized, different ADAGE models perform equally well. To enhance model robustness and better build signatures consistent with biological pathways, we developed an ensemble ADAGE (eADAGE) that integrated stable signatures across models. We applied eADAGE to a compendium of Pseudomonas aeruginosa gene expression profiling experiments performed in 78 media. eADAGE revealed a phosphate starvation response controlled by PhoB in media with moderate phosphate and predicted that a second stimulus provided by the sensor kinase, KinB, is required for this PhoB activation. We validated this relationship using both targeted and unbiased genetic approaches. eADAGE, which captures stable biological patterns, enables cross-experiment comparisons that can highlight measured but undiscovered relationships.
Intensification of rare gas halide lasers with application to laser fusion

The two techniques of backward-wave Raman pulse compression and pulse stacking are reviewed in the context of using KrF lasers as drivers in inertial confinement fusion. Experimental and theoretical results on Raman pulse compression in methane are presented including data on 70 to 75% pump energy extraction by the counter propagating Stokes wave. Results from on-going pulse stacker/Raman compressor experiments are also described, along with future investigations in this general area.
The lattices of invariant subspaces of a class of operators on the Hardy space

In the authors’ first paper, a Beurling-Rudin-Korenbljum type characterization of the closed ideals in a certain algebra of holomorphic functions was used to describe the lattice of invariant subspaces of the shift plus a complex Volterra operator. The current work is an extension of the previous work and it describes the lattice of invariant subspaces of the shift plus a positive integer multiple of the complex Volterra operator on the Hardy space. Our work was motivated by a paper by Ong who studied the real version of the same operator.
Promotions and the Peter Principle

The best worker is not always the best candidate for manager. In these cases, do firms promote the best potential manager or the best worker in their current job? Using microdata on the performance of sales workers at 131 firms, we find evidence consistent with the Peter Principle, which proposes that firms prioritize current job performance in promotion decisions at the expense of other observable characteristics that better predict managerial performance. We estimate that the costs of promoting workers with lower managerial potential are high, suggesting either that firms are making inefficient promotion decisions or that the benefits of promotion-based incentives are great enough to justify the costs of managerial mismatch. We find that firms manage the costs of the Peter Principle by placing less weight on sales performance in promotion decisions when managerial roles entail greater responsibility and when frontline workers are incentivized by strong pay for performance.