cssi/SciSciGPT-SciSciNet huggingface dataset:
Photonic Crystals: Shaping the Flow of Thermal Radiation

In this paper we explore theory, design, and fabrication of photonic crystal (PhC) based selective thermal emitters. In particular, we focus on tailoring spectral and spatial properties by means of resonant enhancement in PhC’s. Firstly, we explore narrow-band resonant thermal emission in photonic crystals exhibiting strong spectral and directional selectivity. We demonstrate two interesting designs based on resonant Q-matching: a vertical cavity enhanced resonant thermal emitter and 2D silicon PhC slab Fano-resonance based thermal emitter. Secondly, we examine the design of 2D tungsten PhC as a broad-band selective emitter. Indeed, based on the resonant cavity coupled resonant modes we demonstrate a highly selective, highly-spectrally efficient thermal emitter. We show that an emitter with a photonic cut-off anywhere from 1.8 μm to 2.5 μm can be designed.
Optimal Tests for Nested Model Selection with Underlying Parameter Instability

This paper develops optimal tests for model selection between two nested models in the presence of underlying parameter instability. These are joint tests for both parameter instability and a null hypothesis on a subset of the parameters. They modify the existing tests for parameter instability to allow the parameter vector to be unknown. These test statistics are useful if one is interested in testing a null hypothesis on some parameters but is worried about the possibility that the parameters may be time varying. The paper provides the asymptotic distributions of this class of test statistics and their critical values for some interesting cases.I thank M. Watson for the idea of this paper and for numerous discussions, suggestions, comments, and teaching. I am grateful to T. Clark, G. Chow, R. Gallant, F. Sowell, N. Swanson, E. Tamer, and A. Tarozzi and also to the co-editor and two referees and to seminar participants at the University of Virginia, ECARES Universite Libre de Brussels, the 2001 Triangle Econometrics Conference, the 2002 NBER Summer Institute, the 2003 Summer Meetings of the Econometric Society, and the 2003 EC2 Conference for comments. Financial support from IFS Summer Research, Princeton University, is gratefully acknowledged. All mistakes are mine.
Stormtime dynamics of the global thermosphere and equatorial ionosphere

Abstract. During magnetic storms the development of equatorial plasma bubbles (EPBs) and distributions of thermospheric densities are strongly influenced by the histories of imposed magnetospheric electric (e M ) fields. Periods of intense EPB activity driven by penetration e M fields in the main phase are followed by their worldwide absence during recovery. A new method is applied to estimate global thermospheric energy ( E th ) budgets from orbit-averaged densities measured by accelerometers on polar-orbiting satellites. During the main phase of storms E th increases as long as the stormtime e M operates, then exponentially decays toward quiet-time values during early recovery. Some fraction of the energy deposited at high magnetic latitudes during the main phase propagates into the subauroral ionosphere-thermosphere where it affects chemical and azimuthal-wind dynamics well into recovery. We suggest a scenario wherein fossils of main phase activity inhibit full restoration of quiet-time dayside dynamos and pre-reversal enhancements of upward plasma drifts near dusk denying bottomside irregularities sufficient time to grow into EPBs.
Cosmic Strings: A Problem or a Solution?

We address, by means of Numerical Simulations, the most fundamental issue in the theory of cosmic strings: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, we present our results which, though still preliminary, offer the best support to date of this scaling hypothesis.
Optimal Debt Management and Redistribution

This paper develops a theory of debt management in which government financing decisions have distributional consequences. We consider a constant aggregate endowment economy in which the government finances exogenous stochastic public spending needs with uniform lump sum taxes and state-contingent public debt. Households are heterogeneous with respect to their constant endowment and their access to private credit. Ricardian Equivalence holds if public debt is high but not if it is low since some households are borrowing constrained and public debt is traded at a premium. For low levels of debt, tax as opposed to debt financing raises current inequality but reduces future inequality since returns to savers decline. We show that optimal policy exploits this tradeoff by limiting the supply of public debt. Consequently, policies and allocations respond persistently to spending shocks along the equilibrium path even though debt markets are complete and taxes are lump sum. This is because households respond to government policy by saving into the future to protect themselves against borrowing constraints. Nonetheless, in the long run, borrowing constrained households accumulate enough wealth that allocations do not respond persistently to spending shocks and Ricardian Equivalence holds.
A demonstration of loss modulation and cavity dumping in a free-electron-laser oscillator

Abstract The performance of an intraactivity cadmium telluride electro-optic cell in a free-electron laser will be described. The cell, installed in the Stanford Mark III IRFEL, was used to either modulate the optical-cavity losses or to dump the stored optical-cavity energy or both. The results of the experiments will be presented.
Divisors on rational normal scrolls

Let A be the homogeneous coordinate ring of a rational normal scroll. The ring A is equal to the quotient of a polynomial ring S by the ideal generated by the two by two minors of a scroll matrix ψ with two rows and l catalecticant blocks. The class group of A is cyclic, and is infinite provided l is at least two. One generator of the class group is [J], where J is the ideal of A generated by the entries of the first column of ψ. The positive powers of J are well-understood; if l is at least two, then the nth ordinary power, the nth symmetric power, and the nth symbolic power coincide and therefore all three nth powers are resolved by a generalized Eagon–Northcott complex. The inverse of [J] in the class group of A is [K], where K is the ideal generated by the entries of the first row of ψ. We study the positive powers of [K]. We obtain a minimal generating set and a Grobner basis for the preimage in S of the symbolic power K(n). We describe a filtration of K(n) in which all of the factors are Cohen–Macaulay S-modules resolved by generalized Eagon–Northcott complexes. We use this filtration to describe the modules in a finely graded resolution of K(n) by free S-modules. We calculate the regularity of the graded S-module K(n) and we show that the symbolic Rees ring of K is Noetherian.
Chirped-beam two-stage SASE-FEL for high power femtosecond X-ray pulse generation

Abstract A method for generating femtosecond duration X-ray pulses using a single-pass free-electron laser (FEL) is presented. This method uses an energy-chirped electron beam propagating through an undulator to produce a frequency-chirped X-ray pulse through self-amplified spontaneous emission (SASE). After the undulator, we consider passing the radiation through a monochromator. The frequency is correlated to the longitudinal position within the pulse; therefore, by selecting a narrow bandwidth, a short temporal pulse will be transmitted. The short pulse radiation is used to seed a second undulator, where the radiation is amplified to saturation. In addition to short pulse generation, this scheme has the ability to control shot-to-shot fluctuations in the central wavelength due to electron beam energy jitter. We present calculations of the radiation characteristics produced by a chirped-beam two-stage SASE–FEL, and consider the performance of the chirped-beam two-stage option for the Linac Coherent Light Source.
Thermal Corrections to Entanglement Entropy from Holography

We use holographic techniques to calculate the first thermal correction to the entanglement entropy of a cap-like region of a CFT defined on a sphere, successfully reproducing the field theory result. Since this is an order-one correction to the entropy in the large-N expansion, quantum corrections to the holographic entanglement entropy formula are essential. The bulk calculation is made tractable using the same technical machinery recently used to derive the linearized Einstein equations in the bulk from the first law of entanglement entropy in the CFT.
The Tale of One-Way Functions

The existence of one-way functions (owf) is arguably the most important problem in computer theory. The article discusses and refines a number of concepts relevant to this problem. For instance, it gives the first combinatorial complete owf, i.e., a function which is one-way if any function is. There are surprisingly many subtleties in basic definitions. Some of these subtleties are discussed or hinted at in the literature and some are overlooked. Here, a unified approach is attempted.
Welfare Recipients' College Attendance and Consequences for Time -Limited Aid

Objective. I examine the association between total time on welfare and recipients' college attendance and graduation over a 20-year period. Methods. Using data from the National Longitudinal Survey of Youth, I model the determinants of college enrollment and graduation among welfare recipients, and the association between the total number of months a recipient receives aid and her college attendance and graduation. Models examine separately the effects associated with longer stays on aid while recipients attend school as well as reduced recidivism associated with college attendance and graduation. Results. Findings indicate that attending college is associated with more months on aid, but graduating largely offsets this increase through reductions in return to aid. Conclusions. Policymakers' concerns that including postsecondary education as a TANF activity would undermine the short-term focus of the program are not fully supported. A greater concern is the low rate of graduation among welfare recipients, who reap the most benefits from college attendance and sacrifice the fewest months on aid.
Focused on the Family? Religious Traditions, Family Discourse, and Pastoral Practice

The relationship between religion and the family has recently reemerged as an important object of sociological inquiry. However, research has largely overlooked the ways in which the family discourse produced by specific religious traditions is connected to family-focused pastoral practices of congregations. Using data from the National Congregations Study, we find that family discourse and pastoral practice are only “loosely coupled” to one another. Ideological differences among mainline Protestant, conservative Protestant, and Roman Catholic congregations do not translate directly into differences in family ministry offerings. These findings help explain why research often finds that religion exercises uniform effects on family life, insofar as most congregations offer a similar package of ministries even though their family discourse is markedly different.
Delay-Aware Cross-Layer Design for Network Utility Maximization in Multi-Hop Networks

We investigate the problem of designing delay-aware joint flow control, routing, and scheduling algorithms in general multi-hop networks for maximizing network utilization. Since the end-to-end delay performance has a complex dependence on the high-order statistics of cross-layer algorithms, earlier optimization-based design methodologies that optimize the long term network utilization are not immediately well-suited for delay-aware design. This motivates us in this work to develop a novel design framework and alternative methods that take advantage of several unexploited design choices in the routing and the scheduling strategy spaces. In particular, we reveal and exploit a crucial characteristic of back pressure-type controllers that enables us to develop a novel link rate allocation strategy that not only optimizes long-term network utilization, but also yields loop free multi-path routes between each source-destination pair. Moreover, we propose a regulated scheduling strategy, based on a token-based service discipline, for shaping the per-hop delay distribution to obtain highly desirable end-to-end delay performance. We establish that our joint flow control, routing, and scheduling algorithm achieves loop-free routes and optimal network utilization. Our extensive numerical studies support our theoretical results, and further show that our joint design leads to substantial end-to-end delay performance improvements in multi-hop networks compared to earlier solutions.
GRB 021004: A Possible Shell Nebula around a Wolf-Rayet Star Gamma-Ray Burst Progenitor*

The rapid localization of GRB 021004 by the HETE-2 satellite allowed nearly continuous monitoring of its early optical afterglow decay, as well as high-quality optical spectra that determined a redshift of z3 = 2.328 for its host galaxy, an active starburst galaxy with strong Lyα emission and several absorption lines. Spectral observations show multiple absorbers at z3A = 2.323, z3B = 2.317, and z3C = 2.293 blueshifted by ~450, ~990, and ~3155 km s-1, respectively, relative to the host galaxy Lyα emission. We argue that these correspond to a fragmented shell nebula that has been radiatively accelerated by the gamma-ray burst (GRB) afterglow at a distance 0.3 pc from a Wolf-Rayet star GRB progenitor. The chemical abundance ratios indicate that the nebula is overabundant in carbon and silicon. The high level of carbon and silicon is consistent with a swept-up shell nebula gradually enriched by a carbon-rich late-type Wolf-Rayet progenitor wind over the lifetime of the nebula prior to the GRB onset. The detection of statistically significant fluctuations and color changes about the jetlike optical decay further supports this interpretation, since fluctuations must be present at some level as a result of irregularities in a clumpy stellar wind medium or if the progenitor has undergone massive ejection prior to the GRB onset. This evidence suggests that the mass-loss process in a Wolf-Rayet star might lead naturally to an iron core collapse with sufficient angular momentum that could serve as a suitable GRB progenitor. Even though we cannot rule out definitely the alternatives of a dormant QSO, large-scale superwinds, or a several hundred year old supernova remnant responsible for the blueshifted absorbers, these findings point to the likelihood of a signature for a massive-star GRB progenitor.
Kinetics of Pyrolysis Mass Loss from Cured Phenolic Resin

Knowledge of the kinetics of phenolic resin pyrolysis is critical to the accurate modeling of ablatives used in rocket nozzle and re-entry environments. Most employ thermogravimetry to study this phenomena. Nearly all of the previous studies on ablative materials have utilized fairly slow heating with respect to the use environment. This has forced analysts to extrapolate to the much higher rates occurring in the use environment. The high heating rate predictions of these models suggest that pyrolysis can be postponed to much higher temperatures. This has had dramatic effects on the predicted mechanical response of the material under flight conditions. To avoid these large extrapolations, laboratory data was required at or near the high heating rates seen in the use environment. A new facility was constructed that is capable of obtaining data at substantially higher heating rates than are currently available. Cured SC 1008 phenolic resin in powdered form was heated at eight heating rates ranging from 0.25 to 2500°C/min. The data indicates that the weight loss behavior of this material at very high heating rates exhibits a much reduced kinetic response over what was previously predicted, and that this may be due to a change in chemical reaction mechanism.
Partial-sum queries in OLAP data cubes using covering codes

A partial-sum query obtains the summation over a set of specified cells of a data cube. We establish a connection between the covering problem in the theory of error-correcting codes and the partial-sum problem and use this connection to devise algorithms for the partial-sum problem with efficient space-time trade-offs. For example, using our algorithms, with 44 percent additional storage, the query response time can be improved by about 12 percent; by roughly doubling the storage requirement, the query response time can be improved by about 34 percent.
Contrast Leakage Patterns from Dynamic Susceptibility Contrast Perfusion MRI in the Grading of Primary Pediatric Brain Tumors

BACKGROUND AND PURPOSE: The pattern of contrast leakage from DSC tissue signal intensity time curves have shown utility in distinguishing adult brain neoplasms, but has limited description in the literature for pediatric brain tumors. The purpose of this study is to evaluate the utility of grading pediatric brain tumors with this technique. MATERIALS AND METHODS: A retrospective review of tissue signal-intensity time curves from 63 pediatric brain tumors with preoperative DSC perfusion MR imaging was performed independently by 2 neuroradiologists. Tissue signal-intensity time curves were generated from ROIs placed in the highest perceived tumor relative CBV. The postbolus portion of the curve was independently classified as returning to baseline, continuing above baseline (T1-dominant contrast leakage), or failing to return to baseline (T2*-dominant contrast leakage). Interobserver agreement of curve classification was evaluated by using the Cohen κ. A consensus classification of curve type was obtained in discrepant cases, and the consensus classification was compared with tumor histology and World Health Organization grade. RESULTS: Tissue signal-intensity time curve classification concordance was 0.69 (95% CI, 0.54–0.84) overall and 0.79 (95% CI, 0.59–0.91) for a T1-dominant contrast leakage pattern. Twenty-five of 25 tumors with consensus T1-dominant contrast leakage were low-grade (positive predictive value, 1.0; 95% CI, 0.83–1.00). By comparison, tumors with consensus T2*-dominant contrast leakage or return to baseline were predominantly high-grade (10/15 and 15/23, respectively) with a high negative predictive value (1.0; 95% CI, 0.83–1.0). For pilomyxoid or pilocytic astrocytomas, a T1-dominant leak demonstrated high sensitivity (0.91; 95% CI, 0.70–0.98) and specificity (0.90, 95% CI, 0.75–0.97). CONCLUSIONS: There was good interobserver agreement in the classification of DSC perfusion tissue signal-intensity time curves for pediatric brain tumors, particularly for T1-dominant leakage. Among patients with pediatric brain tumors, a T1-dominant leakage pattern is highly specific for a low-grade tumor and demonstrates high sensitivity and specificity for pilocytic or pilomyxoid astrocytomas.
A General Framework for Estimation and Inference From Clusters of Features

ABSTRACTApplied statistical problems often come with prespecified groupings to predictors. It is natural to test for the presence of simultaneous group-wide signal for groups in isolation, or for multiple groups together. Current tests for the presence of such signals include the classical F-test or a t-test on unsupervised group prototypes (either group centroids or first principal components). In this article, we propose test statistics that aim for power improvements over these classical approaches. In particular, we first create group prototypes, with reference to the response, and then test with likelihood ratio statistics incorporating only these prototypes. We propose a model, called the “prototype model,” which naturally models this two-step procedure. Furthermore, we introduce an inferential schema detailing the unique considerations for different combinations of prototype formation and univariate/multivariate testing models. The prototype model also suggests new applications to estimation and pr...
Phosphine-free palladium-catalyzed C-H bond arylation of free (N-H)-indoles and pyrroles.

This paper describes a phosphine-free palladium-catalyzed method for direct C-arylation of free (N−H)-indoles and pyrroles with iodo- and bromoarene donors. Employing commercially available materials, this new and operationally simple procedure provides a rapid entry to a wide range of C-arylated (N−H)-indoles including derivatives of tryptamine. In the course of this study, a profound halide effect was uncovered, affecting both the efficiency and regioselectivity of indole arylation.
Code transformations to improve memory parallelism

Current microprocessors incorporate techniques to exploit instruction-level parallelism (ILP). However, previous work has shown that these ILP techniques are less effective in removing memory stall time than CPU time, making the memory system a greater bottleneck in ILP-based systems than previous-generation systems. These deficiencies arise largely because applications present limited opportunities for an out-of-order issue processor to overlap multiple read misses, the dominant source of memory stalls. This work proposes code transformations to increase parallelism in the memory system by overlapping multiple read misses within the same instruction window, while preserving cache locality. We present an analysis and transformation framework suitable for compiler implementation. Our simulation experiments show substantial increases in memory parallelism, leading to execution time reductions averaging 23% in a multiprocessor and 30% in a uniprocessor. We see similar benefits on a Convex Exemplar.
What Role do Hurricanes Play in Sediment Delivery to Subsiding River Deltas

The Mississippi River Delta (MRD) has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50–100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply and delta geomorphology. In the MRD, hurricanes have been paradoxically identified as both substantial agents of widespread land loss, and vertical marsh sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the MRD that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.
Distributed Algorithms for TDMA Link Scheduling in Sensor Networks

The paper is devoted toÂ Time Division Multiple Access Link Scheduling Protocols in wireless sensor networks for full duplex (two-way) communication, where each sensor is scheduled on an incident link as a transmitter and as a receiver in two different time slots. We formulate the full duplex link scheduling problem (FDLSP) as distance-2 edge coloring in bi-directed graphs and prove tighter lower and upper bounds for the FDLSP problem. We formulate the FDLSP problem as an integer linear program (ILP).Â Then, we present two I”-approximation distributed algorithms for growth bounded graphs (GBG), for modeling the sensor networks, and for general graphs, I” being the maximum node degreeÂ in the network.Â The first algorithm is a synchronous $\Delta$-approximation algorithm based on finding maximal independent sets. The second is an asynchronous I”-approximation depth first search (DFS) based algorithm. The maximal independent set based algorithm requires only O(I” log * n) communication rounds (where n is the number of processors in the network) in growth bounded graphs. For general graphs, the maximal independent set based algorithm requires O(I” 4 +I” 3 log * n) communication rounds,Â improving upon the previous best known algorithm with O(nI” 2 + n 2 m) communication rounds (where m is the number of links in the network). The asynchronous DFS based algorithm requires only O(n) communication rounds for both general and growth bounded graphs. The simulations show that the proposed algorithms assign on average equal or fewer number of time slots compared to the best known distributed algorithm while being significantly faster.
Adverse pregnancy outcomes and subsequent risk of cardiovascular disease in women with systemic lupus erythematosus

Background/objective Patients with systemic lupus erythematosus (SLE) are at increased risk for adverse pregnancy outcomes and cardiovascular disease (CVD). The objective of this exploratory study was to investigate the association between a history of adverse pregnancy outcomes and subsequent risk of subclinical CVD assessed by imaging studies and verified clinical CVD events in 129 women with SLE. Methods The occurrence of adverse pregnancy outcomes, specifically pre-eclampsia, preterm birth and low birth weight was ascertained by questionnaire. Subclinical CVD was assessed by coronary artery calcium (CAC) as measured by electron beam CT and carotid plaque measured by B mode ultrasound. Clinical CVD events were verified by medical record review. Logistic regression was used to estimate the association of pregnancy complications with occurrence of subclinical CVD and clinical CVD with a priori adjustment for age, which is associated with CVD and SLE disease duration as a measure of SLE disease burden. Results Fifty-six women reported at least one pregnancy complication while 73 had none. Twenty-six women had at least one pregnancy complicated by pre-eclampsia and were more likely to have a CAC score greater than or equal to 10 (adjusted OR=3.7; 95% CI 1.2 to 11.9), but the presence of plaque was not associated with this pregnancy complication, OR=1.1, (95% CI 0.4 to 2.8). Low birth weight and preterm birth were not associated with CAC or plaque. Conclusions Patients with SLE with a history of pre-eclampsia had a higher rate of subclinical CVD as measured by CAC score. Future studies are needed to confirm the relationship between adverse pregnancy outcomes and subsequent subclinical CVD and clinical CVD events.
Fertility and Female Labor Force Participation: Evidence from One Child Policy in China

Unlike in the United States where fertility is found to be negatively correlated with female labor force participation, China has witnessed a decrease in both fertility and female labor force participation since the 1980s. Does fertility play a different role in female labor force participation in China than in the U.S.? To answer this question, this paper exploits plausibly exogenous variations in fertility created by the afffirmative One-Child Policy in China to estimate the effect of having two or more children on the mother's labor force participation. Using a large data set from the 1990 Population Census, we find that though OLS shows positive effects of fertility, 2SLS will report negative effects of having two or more children on female labor force participation in rural China.
Molecular markers in uterine papillary serous carcinoma: Correlation between endometrial biopsy and hysterectomy specimens

e16503 Background: Uterine papillary serous carcinoma (UPSC) has a poor prognosis and a distinct molecular profile characterized by alterations in p53, Her2/neu and PIK3/AKT/mTOR signaling. Neoadju...
Double metric, generalized metric, and α ′ -deformed double field theory

We relate the unconstrained ``double metric'' of the ``${\ensuremath{\alpha}}^{\ensuremath{'}}$-geometry'' formulation of double field theory to the constrained generalized metric encoding the spacetime metric and $b$-field. This is achieved by integrating out auxiliary field components of the double metric in an iterative procedure that induces an infinite number of higher-derivative corrections. As an application, we prove that, to first order in ${\ensuremath{\alpha}}^{\ensuremath{'}}$ and to all orders in fields, the deformed gauge transformations are Green-Schwarz\char21{}deformed diffeomorphisms. We also prove that to first order in ${\ensuremath{\alpha}}^{\ensuremath{'}}$ the spacetime action encodes precisely the Green-Schwarz deformation with Chern-Simons forms based on the torsionless gravitational connection. This seems to be in tension with suggestions in the literature that T-duality requires a torsionful connection, but we explain that these assertions are ambiguous since actions that use different connections are related by field redefinitions.
Mesoporous Manganese Oxide Catalyzed Aerobic Oxidative Coupling of Anilines To Aromatic Azo Compounds

Herein we introduce an environmentally friendly approach to the synthesis of symmetrical and asymmetrical aromatic azo compounds by using air as the sole oxidant under mild reaction conditions in the presence of cost-effective and reusable mesoporous manganese oxide materials.
Towards On-Line Services Based on a Holistic Analysis of Human Activities

Very often computer scientists view computerization of services in terms of the logistics of human-machine interaction, including establishing a contract, accessing records, and of course designing an interface. But this analysis often moves too quickly to tactical details, failing to frame the entire service in human terms, and not recognizing the mutual learning required to define and relate goals, constraints, and the personalized value of available services. In particular, on-line services that "computerize communication" can be improved by constructing an activity model of what the person is trying to do, not just filtering, comparing, and selling piece-meal services. For example, from the customer s perspective the task of an on-line travel service is not merely to establish confirmed reservations, but to have a complete travel plan, usually integrating many days of transportation, lodging, and recreation into a happy experience. The task of the travel agent is not merely "ticketing", but helping the customer understand what they want and providing services that will connect everything together in an enjoyable way.
Factors Influencing Exit Rate of US Farms

USDA conducts mandatory census survey every 5 year. According to the report the total amount of farms drops to 1,717,898 in 2012, which is 23.34% less then that in 1982. The number of farm exits varies from 906,100 to 652,597 during the 30 years. What are the factors influencing farm exit rates will be studied with logistic regression.
Comparison of Commercial and Self-Initiated Weight Loss Programs in People With Prediabetes: A Randomized Control Trial

Objectives. To determine if a widely available weight-management program (Weight Watchers) could achieve sufficient weight loss in persons with prediabetes compared with a Diabetes Prevention Program–based individual counseling program supported by National Diabetes Education Program materials.Methods. We conducted an individual, randomized intervention trial in Indianapolis, Indiana, in 2013 to 2014, in 225 persons with prediabetes. We compared the Weight Watchers weight-management program (n = 112) with Your Game Plan to Prevent Type 2 Diabetes, a program developed by the National Diabetes Education Program. Outcomes were weight and metabolic markers measured at baseline, 6 months, and 12 months.Results. Intervention participants lost significantly more weight than controls at 6 months (5.5% vs 0.8%) and 12 months (5.5% vs 0.2%; both P < .001). The intervention group also had significantly greater improvements in hemoglobin A1c and high-density lipoprotein cholesterol level than did controls.Conclusions...
Differentially-private learning of low dimensional manifolds

In this paper, we study the problem of differentially-private learning of low dimensional manifolds embedded in high dimensional spaces. The problems one faces in learning in high dimensional spaces are compounded in a differentially-private learning. We achieve the dual goals of learning the manifold while maintaining the privacy of the dataset by constructing a differentially-private data structure that adapts to the doubling dimension of the dataset. Our differentially-private manifold learning algorithm extends random projection trees of Dasgupta and Freund. A naive construction of differentially-private random projection trees could involve queries with high global sensitivity that would affect the usefulness of the trees. Instead, we present an alternate way of constructing differentially-private random projection trees that uses low sensitivity queries that are precise enough for learning the low dimensional manifolds. We prove that the size of the tree depends only on the doubling dimension of the dataset and not its extrinsic dimension.
Human capital accumulation in a federation

Abstract More than half of the variation across U.S. school districts in real K-12 education expenditures per student is due to differences between, rather than within, states. I study the welfare implications of redistribution of education expenditures by the Federal government, using an analytically tractable model of human capital accumulation with heterogeneous agents and endogenous state policies. The net welfare effect of Federal redistribution depends on a trade-off between the positive effect of redistributing resources toward poorer states and the negative effect resulting from misallocation of population across states. Federal redistribution increases welfare in a calibrated version of the model.
Improved approximation for node-disjoint paths in planar graphs

We study the classical Node-Disjoint Paths (NDP) problem: given an n-vertex graph G and a collection =(s1,t1),…,(sk,tk) of pairs of vertices of G called demand pairs, find a maximum-cardinality set of node-disjoint paths connecting the demand pairs. NDP is one of the most basic routing problems, that has been studied extensively. Despite this, there are still wide gaps in our understanding of its approximability: the best currently known upper bound of O(√n) on its approximation ratio is achieved via a simple greedy algorithm, while the best current negative result shows that the problem does not have a better than Ω(log1/2−δn)-approximation for any constant δ, under standard complexity assumptions. Even for planar graphs no better approximation algorithms are known, and to the best of our knowledge, the best negative bound is APX-hardness. Perhaps the biggest obstacle to obtaining better approximation algorithms for NDP is that most currently known approximation algorithms for this type of problems rely on the standard multicommodity flow relaxation, whose integrality gap is Ω(√n) for NDP, even in planar graphs. In this paper, we break the barrier of O(√n) on the approximability of NDP in planar graphs and obtain an O(n9/19)-approximation. We introduce a new linear programming relaxation of the problem, and a number of new techniques, that we hope will be helpful in designing more powerful algorithms for this and related problems.
Discriminative embeddings of latent variable models for structured data

Kernel classifiers and regressors designed for structured data, such as sequences, trees and graphs, have significantly advanced a number of interdisciplinary areas such as computational biology and drug design. Typically, kernels are designed beforehand for a data type which either exploit statistics of the structures or make use of probabilistic generative models, and then a discriminative classifier is learned based on the kernels via convex optimization. However, such an elegant two-stage approach also limited kernel methods from scaling up to millions of data points, and exploiting discriminative information to learn feature representations. We propose, structure2vec, an effective and scalable approach for structured data representation based on the idea of embedding latent variable models into feature spaces, and learning such feature spaces using discriminative information. Interestingly, structure2vec extracts features by performing a sequence of function mappings in a way similar to graphical model inference procedures, such as mean field and belief propagation. In applications involving millions of data points, we showed that structure2vec runs 2 times faster, produces models which are 10, 000 times smaller, while at the same time achieving the state-of-the-art predictive performance.
A Laplace stochastic frontier model

We propose a Laplace stochastic frontier model as an alternative to the traditional model with normal errors. An interesting feature of the Laplace model is that the distribution of inefficiency conditional on the composed error is constant for positive values of the composed error, but varies for negative values. A simulation study suggests that the model performs well relative to the normal-exponential model when the two-sided error is misspecified. An application to U.S. Airlines is provided.
Electrochemical Techniques in Corrosion: Status, Limitations, and Needs

The corrosion of metals occurs primarily by electrochemical processes involving metal oxidation and simultaneous reduction of some other species. The fundamental understanding of these processes has allowed the development of a number of electrochemical techniques for the study of the corrosion phenomena and assessment of the corrosion rate. In fact, electrochemical techniques are so ingrained in the field that many practitioners think of corrosion rates first in terms of current density rather than thickness or mass loss per unit time. Standard approaches for electrochemical corrosion rate determination are commonly used in the field for on-line monitoring of systems and facilities. Electrochemistry also provides powerful tools for developing fundamental understanding of corrosion phenomena. However, there are some limitations to the abilities of current electrochemical techniques and some needs for the future. This paper describes the status of electrochemical techniques, their limitations, where non-electrochemical methods are required, and future needs in the field.
High power breakdown testing of a photonic band-gap accelerator structure with elliptical rods

An improved single-cell photonic band-gap (PBG) structure with an inner row of elliptical rods (PBG-E) was tested with high power at a 60 Hz repetition rate at X-band (11.424 GHz), achieving a gradient of $128\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ at a breakdown probability of $3.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ per pulse per meter at a pulse length of 150 ns. The tested standing-wave structure was a single high-gradient cell with an inner row of elliptical rods and an outer row of round rods; the elliptical rods reduce the peak surface magnetic field by 20% and reduce the temperature rise of the rods during the pulse by several tens of degrees, while maintaining good damping and suppression of high order modes. When compared with a single-cell standing-wave undamped disk-loaded waveguide structure with the same iris geometry under test at the same conditions, the PBG-E structure yielded the same breakdown rate within measurement error. The PBG-E structure showed a greatly reduced breakdown rate compared with earlier tests of a PBG structure with round rods, presumably due to the reduced magnetic fields at the elliptical rods vs the fields at the round rods, as well as use of an improved testing methodology. A post-testing autopsy of the PBG-E structure showed some damage on the surfaces exposed to the highest surface magnetic and electric fields. Despite these changes in surface appearance, no significant change in the breakdown rate was observed in testing. These results demonstrate that PBG structures, when designed with reduced surface magnetic fields and operated to avoid extremely high pulsed heating, can operate at breakdown probabilities comparable to undamped disk-loaded waveguide structures and are thus viable for high-gradient accelerator applications.
Boronic esters in asymmetric synthesis.

The author’s work on (α-haloalkyl)boronic esters as reagents for asymmetric synthesis is reviewed. Diastereomeric ratios exceeding 1000 can be achieved with this chemistry, and ratios around 100 are commonplace. The method allows sequential installation of a series of stereocenters and tolerates a wide variety of suitably protected functional substituents. (α-Amidoalkyl)boronic acids include biochemically significant serine protease inhibitors, one of which is the clinically successful proteasome inhibitor bortezomib, used for treatment of multiple myeloma and mantle cell lymphoma.
Stereoselective Synthesis of Dioxolanes and Oxazolidines via a Desymmetrization Acetalization/Michael Cascade.

The desymmetrization of p-quinols using a Bronsted acid catalyzed acetalization/Michael cascade was achieved in high yields and diastereoselectivities for aldehydes and imines. Use of a chiral Bronsted acid allowed for the synthesis of 1,3-dioxolane and 1,3-oxazolidine products in modest enantioselectivity.
A panic foretold: Ebola in the United States

AbstractThis paper reconsiders the Ebola response in the US as a panic that was both predictable and problematic. Public health professionals and policy-makers have historically drawn attention to and prepared for emerging infectious diseases by raising the specter of catastrophe, generating fears that the media and politicians are often willing to amplify. Although this approach can increase awareness of and funding for global health threats, it also sows the seeds of panic, stigmatizing people associated with the disease, and compromising an effective, evidence-based response. We offer lessons for public health leaders as they review the US Ebola response in order to prepare more responsibly for future disease scares such as that posed by the Zika virus.
Elastic Stability of Rubber Compression Springs

Experimental measurements are described of the critical (buckling) compressive loads for columns of rubber springs under various loading conditions. They are shown to be in good accord with the theoretical treatment of Haringx, in which the classical theory of buckling is modified to take into account the shear deflection of column elements. Measurements are also described of the shape of the buckled column and of the shear stiffness of columns under compressive loads smaller than the buckling load. They are found to be satisfactorily described by the theory also.
Higher regularity of the free boundary in the parabolic Signorini problem

We show that the quotient of two caloric functions which vanish on a portion of an $$H^{k+ \alpha }$$ regular slit is $$H^{k+ \alpha }$$ at the slit, for $$k \ge 2$$ . In the case $$k=1$$ , we show that the quotient is in $$H^{1+\alpha }$$ if the slit is assumed to be space-time $$C^{1, \alpha }$$ regular. This can be thought of as a parabolic analogue of a recent important result in De Silva and Savin (Boundary Harnack estimates in slit domains and applications to thin free boundary problems, 2014), whose ideas inspired us. As an application, we show that the free boundary near a regular point of the parabolic thin obstacle problem studied in Danielli et al. (Optimal regularity and the free boundary in the parabolic Signorini problem. Mem. Am. Math. Soc., 2013) with zero obstacle is $$C^{\infty }$$ regular in space and time.
Airborne Electromagnetic Surveys for Groundwater Characterization

Airborne electromagnetic (AEM) surveys provide densely sampled data over large areas (typically several hundred sq. km) that cannot be covered effectively using ground-based methods. AEM data are inverted to estimate the three-dimensional distribution of electrical resistivity structures from shallow depths to several hundred meters. These models convey unparalleled details that are used to make inferences about hydrogeologic properties and processes at the watershed and local scale. This information is being used in groundwater models that are critical to water management decisions, to better understand geologic frameworks, and to improve climate change models. The U.S. Geological Survey (USGS) has been engaged in the application of AEM to many watershed and local scale groundwater projects within United States. We present the results of several frequency- and time-domain AEM surveys acquired by the USGS that have been used for mapping alluvial valleys, buried glacial aquifers, fault-bounded basins, and understanding permafrost distributions.
Characterization of single and colliding laser-produced plasma bubbles using Thomson scattering and proton radiography

Time-resolved measurements of electron and ion temperatures using Thomson scattering have been combined with proton radiography data for comprehensive characterization of individual laser-produced plasma bubbles or the interaction of bubble pairs, where reconnection of azimuthal magnetic fields occurs. Measurements of ion and electron temperatures agree with lasnex simulations of single plasma bubbles, which include the physics of magnetic fields. There is negligible difference in temperatures between a single plasma bubble and the interaction region of bubble pairs, although the ion temperature may be slightly higher due to the collision of expanding plasmas. These results are consistent with reconnection in a $\ensuremath{\beta}\ensuremath{\sim}8$ plasma, where the release of magnetic energy ($l$5$%$ of the electron thermal energy) does not appreciably affect the hydrodynamics.
Iridium-catalyzed borylation of secondary C-H bonds in cyclic ethers.

The borylation of secondary C–H bonds, specifically secondary C–H bonds of cyclic ethers, with a catalyst generated from tetramethylphenanthroline and an iridium precursor is reported. This borylation occurs with unique selectivity for the C–H bonds located β to the oxygen atoms over the weaker C–H bonds located α to oxygen atoms. Mechanistic studies imply that the C–H bond cleavage occurs directly at the β position rather than at the α position followed by isomerization of a reaction intermediate.
NMR Techniques for Noble Metal Nanoparticles

Solution phase noble metal nanoparticle growth reactions are comprised of deceptively simple steps. Analytical methods with high chemical, spatial, and temporal resolution are crucial to understanding these reactions and subsequent nanoparticle properties. However, approaches for the characterization of solid inorganic materials and solution phase molecular species are often disparate. One powerful technique to address this gap is nuclear magnetic resonance (NMR) spectroscopy, which can facilitate routine, direct, molecular-scale analysis of nanoparticle formation and morphology in situ, in both the solution and the solid phase. A growing body of work indicates that NMR analyses should yield an exciting complement to the existing canon of routine nanoparticle characterization methods such as electron microscopy and optical absorption spectroscopy. Here, we discuss recent developments in the application of NMR techniques to the study of noble metal nanoparticle growth, surface chemistry, and physical prope...