Showing papers by "Lehigh University published in 2015"

The eleventh and twelfth data releases of the Sloan Digital Sky Survey: final data from SDSS-III

Abstract: The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 sq. deg of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-Object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include measured abundances of 15 different elements for each star. In total, SDSS-III added 2350 sq. deg of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 sq. deg; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5,513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.

A Multi-resolution Gaussian process model for the analysis of large spatial data sets

Abstract: We develop a multiresolution model to predict two-dimensional spatial fields based on irregularly spaced observations. The radial basis functions at each level of resolution are constructed using a Wendland compactly supported correlation function with the nodes arranged on a rectangular grid. The grid at each finer level increases by a factor of two and the basis functions are scaled to have a constant overlap. The coefficients associated with the basis functions at each level of resolution are distributed according to a Gaussian Markov random field (GMRF) and take advantage of the fact that the basis is organized as a lattice. Several numerical examples and analytical results establish that this scheme gives a good approximation to standard covariance functions such as the Matern and also has flexibility to fit more complicated shapes. The other important feature of this model is that it can be applied to statistical inference for large spatial datasets because key matrices in the computations are spars...

Identification of molybdenum oxide nanostructures on zeolites for natural gas conversion

Abstract: Direct methane conversion into aromatic hydrocarbons over catalysts with molybdenum (Mo) nanostructures supported on shape-selective zeolites is a promising technology for natural gas liquefaction. We determined the identity and anchoring sites of the initial Mo structures in such catalysts as isolated oxide species with a single Mo atom on aluminum sites in the zeolite framework and on silicon sites on the zeolite external surface. During the reaction, the initial isolated Mo oxide species agglomerate and convert into carbided Mo nanoparticles. This process is reversible, and the initial isolated Mo oxide species can be restored by a treatment with gas-phase oxygen. Furthermore, the distribution of the Mo nanostructures can be controlled and catalytic performance can be fully restored, even enhanced, by adjusting the oxygen treatment.

High performing and stable supported nano-alloys for the catalytic hydrogenation of levulinic acid to γ-valerolactone

Abstract: The catalytic hydrogenation of levulinic acid, a key platform molecule in many biorefinery schemes, into γ-valerolactone is considered as one of the pivotal reactions to convert lignocellulose-based biomass into renewable fuels and chemicals. Here we report on the development of highly active, selective and stable supported metal catalysts for this reaction and on the beneficial effects of metal nano-alloying. Bimetallic random alloys of gold-palladium and ruthenium-palladium supported on titanium dioxide are prepared with a modified metal impregnation method. Gold-palladium/titanium dioxide shows a marked,~27-fold increase in activity (that is, turnover frequency of 0.1 s(-1)) compared with its monometallic counterparts. Although ruthenium-palladium/titanium dioxide is not only exceptionally active (that is, turnover frequency of 0.6 s(-1)), it shows excellent, sustained selectivity to γ-valerolactone (99%). The dilution and isolation of ruthenium by palladium is thought to be responsible for this superior catalytic performance. Alloying, furthermore, greatly improves the stability of both supported nano-alloy catalysts.

Thin-Film Materials for the Protection of Semiconducting Photoelectrodes in Solar-Fuel Generators

Abstract: The electrochemical instability of semiconductors in aqueous electrolytes has impeded the development of robust sunlight-driven water-splitting systems. We review the use of protective thin films to improve the electrochemical stability of otherwise unstable semiconductor photoelectrodes (e.g., Si and GaAs). We first discuss the origins of instability and various strategies for achieving stable and functional photoelectrosynthetic interfaces. We then focus specifically on the use of thin protective films on photoanodes and photocathodes for photosynthetic reactions that include oxygen evolution, halide oxidation, and hydrogen evolution. Finally, we provide an outlook for the future development of thin-layer protection strategies to enable semiconductor-based solar-driven fuel production.

Kepler Eclipsing Binary Stars. VII. The Catalog of Eclipsing Binaries Found in the Entire Kepler Data-Set

Abstract: The primary Kepler Mission provided nearly continuous monitoring of ~200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 square degree Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets. An online version of this catalog with downloadable content and visualization tools is maintained at this http URL

From Board Composition to Corporate Environmental Performance Through Sustainability-Themed Alliances

Abstract: A growing body of work suggests that the presence of women and of independent directors on boards of directors is associated with higher corporate environmental performance. However, the mechanisms linking board composition to corporate environmental performance are not well understood. This study proposes and empirically tests the mediating role of sustainability-themed alliances in the relationship between board composition and corporate environmental performance. Using the population of public oil and gas firms in the United States as the sample, the study relies on renewable energy alliances to measure sustainability-themed alliances and longitudinally analyzes lagged data for independent and control variables. The study found that (1) the higher the representation of women on a firm’s board, the more likely the firm is to form sustainability-themed alliances, and (2) the higher the representation of independent directors on a firm’s board, the more likely the firm is to form sustainability-themed alliances. Such alliances, in turn, positively contribute to corporate environmental performance. This paper discusses the study’s contributions to the board composition-social performance literature.

PTFE Tribology and the Role of Mechanochemistry in the Development of Protective Surface Films

Abstract: The wear and friction behavior of ultralow wear polytetrafluoroethylene (PTFE)/α-alumina composites first described by Burris and Sawyer in 2006 has been heavily studied, but the mechanisms responsible for the 4 orders of magnitude improvement in wear over unfilled PTFE are still not fully understood. It has been shown that the formation of a polymeric transfer film is crucial to achieving ultralow wear on a metal countersurface. However, the detailed chemical mechanism of transfer film formation and its role in the exceptional wear performance has yet to be described. There has been much debate about the role of chemical interactions between the PTFE, the filler, and the metal countersurface, and some researchers have even concluded that chemical changes are not an important part of the ultralow wear mechanism in these materials. Here, a “stripe” test allowed detailed spectroscopic studies of PTFE/α-alumina transfer films in various stages of development, which led to a proposed mechanism which accounts ...

The impact of climate extremes and irrigation on US crop yields

Abstract: Climate variability and extremes are expected to increase due to climate change; this may have significant negative impacts for agricultural production. Previous work has primarily focused on the impact of mean growing season temperature and precipitation on rainfed crop yields with little work on irrigated crop yields or climate extremes and their timing. County-level crop yields and daily precipitation and temperature data are pooled to quantify the impact of climate variability and extremes on four major staple crops in the United States. Conditional density plots are used to graphically explore the relationship between climate extremes and crop yields, thereby avoiding assumptions about linearity or underlying probability distributions. Non-linear and threshold-type relationships exist between yields and both precipitation and temperature climate indices; irrigation significantly reduces the impact of all climate indices. In some cases, this occurs by shifting the threshold, such that a more extreme weather event is necessary to negatively impact yields. In other cases, irrigation essentially decouples the crop yields from climate. This work demonstrates that irrigation may be a beneficial adaptation mechanism to changes in climate extremes in coming decades.

Effect of Customer Participation on Service Outcomes: The Moderating Role of Participation Readiness

Abstract: Prior empirical evidence on the role of customer participation (CP) on service outcomes is limited and inconsistent. The authors add new insights by investigating the boundary conditions of the CP-service outcome link. Using two experiments, the article examines the moderating effect of three CP readiness factors: ability, perceived benefits of participation, and role identification. The results show that when CP readiness is high, increasing CP enhances service outcomes including customer satisfaction and perceived service quality; however, when CP readiness is low, the effect of CP on service outcomes tapers off or becomes negative. The results highlight the contingent nature of CP’s effect, demonstrate that CP could indeed be a double-edged sword, and provide managerial guidelines to enhance CP’s benefits through appropriate targeting and service design.

Measuring dynamic cell–material interactions and remodeling during 3D human mesenchymal stem cell migration in hydrogels

Abstract: Biomaterials that mimic aspects of the extracellular matrix by presenting a 3D microenvironment that cells can locally degrade and remodel are finding increased applications as wound-healing matrices, tissue engineering scaffolds, and even substrates for stem cell expansion. In vivo, cells do not simply reside in a static microenvironment, but instead, they dynamically reengineer their surroundings. For example, cells secrete proteases that degrade extracellular components, attach to the matrix through adhesive sites, and can exert traction forces on the local matrix, causing its spatial reorganization. Although biomaterials scaffolds provide initially well-defined microenvironments for 3D culture of cells, less is known about the changes that occur over time, especially local matrix remodeling that can play an integral role in directing cell behavior. Here, we use microrheology as a quantitative tool to characterize dynamic cellular remodeling of peptide-functionalized poly(ethylene glycol) (PEG) hydrogels that degrade in response to cell-secreted matrix metalloproteinases (MMPs). This technique allows measurement of spatial changes in material properties during migration of encapsulated cells and has a sensitivity that identifies regions where cells simply adhere to the matrix, as well as the extent of local cell remodeling of the material through MMP-mediated degradation. Collectively, these microrheological measurements provide insight into microscopic, cellular manipulation of the pericellular region that gives rise to macroscopic tracks created in scaffolds by migrating cells. This quantitative and predictable information should benefit the design of improved biomaterial scaffolds for medically relevant applications.

Per-Input Control-Flow Integrity

Abstract: Control-Flow Integrity (CFI) is an effective approach to mitigating control-flow hijacking attacks. Conventional CFI techniques statically extract a control-flow graph (CFG) from a program and instrument the program to enforce that CFG. The statically generated CFG includes all edges for all possible inputs; however, for a concrete input, the CFG may include many unnecessary edges. We present Per-Input Control-Flow Integrity (PICFI), which is a new CFI technique that can enforce a CFG computed for each concrete input. PICFI starts executing a program with the empty CFG and lets the program itself lazily add edges to the enforced CFG if such edges are required for the concrete input. The edge addition is performed by PICFI-inserted instrumentation code. To prevent attackers from arbitrarily adding edges, PICFI uses a statically computed all-input CFG to constrain what edges can be added at runtime. To minimize performance overhead, operations for adding edges are designed to be idempotent, so they can be patched to no-ops after their first execution. As our evaluation shows, PICFI provides better security than conventional fine-grained CFI with comparable performance overhead.

Adding vs. Averaging in Distributed Primal-Dual Optimization

Abstract: Distributed optimization methods for large-scale machine learning suffer from a communication bottleneck. It is difficult to reduce this bottleneck while still efficiently and accurately aggregating partial work from different machines. In this paper, we present a novel generalization of the recent communication-efficient primal-dual framework (COCOA) for distributed optimization. Our framework, COCOA+, allows for additive combination of local updates to the global parameters at each iteration, whereas previous schemes with convergence guarantees only allow conservative averaging. We give stronger (primal-dual) convergence rate guarantees for both COCOA as well as our new variants, and generalize the theory for both methods to cover non-smooth convex loss functions. We provide an extensive experimental comparison that shows the markedly improved performance of COCOA+ on several real-world distributed datasets, especially when scaling up the number of machines.

Pull-based load distribution in large-scale heterogeneous service systems

Abstract: The model is motivated by the problem of load distribution in large-scale cloud-based data processing systems. We consider a heterogeneous service system, consisting of multiple large server pools. The pools are different in that their servers may have different processing speeds and/or different buffer sizes (which may be finite or infinite). We study an asymptotic regime in which the customer arrival rate and pool sizes scale to infinity simultaneously, in proportion to some scaling parameter n. Arriving customers are assigned to the servers by a "router," according to a pull-based algorithm, called PULL. Under the algorithm, each server sends a "pull-message" to the router, when it becomes idle; the router assigns an arriving customer to a server according to a randomly chosen available pull-message, if there are any, or to a random server, otherwise. Assuming subcritical system load, we prove asymptotic optimality of PULL. Namely, as system scale $$n\rightarrow \infty $$n??, the steady-state probability of an arriving customer experiencing blocking or waiting, vanishes. We also describe some generalizations of the model and PULL algorithm, for which the asymptotic optimality still holds.

Savings in Medical Expenditures Associated with Reductions in Body Mass Index Among US Adults with Obesity, by Diabetes Status

Abstract: The prevalence of obesity has more than doubled in the USA in the past 30 years Obesity is a significant risk factor for diabetes, cardiovascular disease, and other clinically significant co-morbidities This paper estimates the medical care cost savings that can be achieved from a given amount of weight loss by people with different starting values of body mass index (BMI), for those with and without diabetes This information is an important input into analyses of the cost effectiveness of obesity treatments and prevention programs Two-part models of instrumental variables were estimated using data from the Medical Expenditure Panel Survey (MEPS) for 2000–2010 Models were estimated for all adults as well as separately for those with and without diabetes We calculated the causal impact of changes in BMI on medical care expenditures, cost savings for specific changes in BMI (5, 10, 15, and 20 %) from starting BMI levels ranging from 30 to 45 kg/m2, as well as the total excess medical care expenditures caused by obesity In the USA, adult obesity raised annual medical care costs by $US3,508 per obese individual, for a nationwide total of $US3158 billion (year 2010 values) However, the relationship of medical care costs over BMI is J-shaped; costs rise exponentially in the range of class 2 and 3 obesity (BMI ≥35) The heavier the obese individual, the greater the reduction in medical care costs associated with a given percent reduction in BMI Medical care expenditures are higher, and rise more with BMI, among individuals with diabetes than among those without diabetes The savings from a given percent reduction in BMI are greater the heavier the obese individual, and are greater for those with diabetes than for those without diabetes The results provide health insurers, employers, government agencies, and health economists with accurate estimates of the change in medical care expenditures resulting from weight loss, which is important information for calculating the cost effectiveness of interventions to prevent and treat obesity

Centralization versus decentralization: Risk pooling, risk diversification, and supply chain disruptions

Abstract: We investigate optimal system design in a multi-location system in which supply is subject to disruptions. We examine the expected costs and cost variances of the system in both a centralized and a decentralized inventory system. We show that, when demand is deterministic and supply may be disrupted, using a decentralized inventory design reduces cost variance through the risk diversification effect, and therefore a decentralized inventory system is optimal. This is in contrast to the classical result that when supply is deterministic and demand is stochastic, centralization is optimal due to the risk-pooling effect. When both supply may be disrupted and demand is stochastic, we demonstrate that a risk-averse firm should typically choose a decentralized inventory system design.

A Research Agenda for Geospatial Technologies and Learning

Abstract: Knowledge around geospatial technologies and learning remains sparse, inconsistent, and overly anecdotal. Studies are needed that are better structured; more systematic and replicable; attentive to progress and findings in the cognate fields of science, technology, engineering, and math education; and coordinated for multidisciplinary approaches. A proposed agenda is designed to frame the next generation of research in this field, organized around four foci: (1) connections between GST and geospatial thinking; (2) learning GST; (3) curriculum and student learning through GST; and (4) educators’ professional development with GST. Recommendations for advancing this agenda are included.

Virtual groundwater transfers from overexploited aquifers in the United States

Abstract: The High Plains, Mississippi Embayment, and Central Valley aquifer systems within the United States are currently being overexploited for irrigation water supplies. The unsustainable use of groundwater resources in all three aquifer systems intensified from 2000 to 2008, making it imperative that we understand the consumptive processes and forces of demand that are driving their depletion. To this end, we quantify and track agricultural virtual groundwater transfers from these overexploited aquifer systems to their final destination. Specifically, we determine which US metropolitan areas, US states, and international export destinations are currently the largest consumers of these critical aquifers. We draw upon US government data on agricultural production, irrigation, and domestic food flows, as well as modeled estimates of agricultural virtual water contents to quantify domestic transfers. Additionally, we use US port-level trade data to trace international exports from these aquifers. In 2007, virtual groundwater transfers from the High Plains, Mississippi Embayment, and Central Valley aquifer systems totaled 17.93 km3, 9.18 km3, and 6.81 km3, respectively, which is comparable to the capacity of Lake Mead (35.7 km3), the largest surface reservoir in the United States. The vast majority (91%) of virtual groundwater transfers remains within the United States. Importantly, the cereals produced by these overexploited aquifers are critical to US food security (contributing 18.5% to domestic cereal supply). Notably, Japan relies upon cereals produced by these overexploited aquifers for 9.2% of its domestic cereal supply. These results highlight the need to understand the teleconnections between distant food demands and local agricultural water use.

Metal forming beyond shaping: Predicting and setting product properties

Abstract: Metal forming is not only shaping the form of a product, it is also influencing its mechanical and physical properties over its entire volume. Advanced analysis methods recently enable accurate prediction of these properties and allow for setting these properties deterministically during the forming process. Effective measurement methods ensure the setting of these predicted properties. Several real examples demonstrate the impressive achievements and indicate the necessity of a paradigm change in designing products by including manufacturing-induced effects in the initial dimensioning. This paradigm change will lead to lightweight components and serve environmentally benign designs.

Enhancing School-Based Mental Health Services with a Preventive and Promotive Approach to Universal Screening for Complete Mental Health.

Abstract: Universal screening for complete mental health is proposed as a key step in service delivery reform to move school-based psychological services from the back of the service delivery system to the front, which will increase emphasis on prevention, early intervention, and promotion. A sample of 2,240 high school students participated in a schoolwide universal screening to identify behavioral and emotional distress as well as personal strengths. School psychologists, as part of a multidisciplinary team, coordinated the use of these screening data to engage in preventive consultation with administration to make decisions regarding the refinement and expansion of mental health service delivery options. Schoolwide and individual student prevention and intervention activities were tailored according to screening results. The roles of the school psychologist and multidisciplinary team members are discussed as critical components of this approach to service delivery change. Implications for future consultation res...

Paid maternity leave and breastfeeding practice before and after California's implementation of the nation's first paid family leave program.

Abstract: California was the first state in the United States to implement a paid family leave (PFL) program in 2004. We use data from the Infant Feeding Practices Study to examine the changes in breastfeeding practices in California relative to other states before and after the implementation of PFL. We find an increase of 3-5 percentage points for exclusive breastfeeding and an increase of 10-20 percentage points for breastfeeding at several important markers of early infancy. Our study supports the recommendation of the Surgeon General to establish paid leave policies as a strategy for promoting breastfeeding.

Proton beam radiation induces DNA damage and cell apoptosis in glioma stem cells through reactive oxygen species

Abstract: Glioblastoma multiforme (GBM) is among the most lethal of human malignancies. Most GBM tumors are refractory to cytotoxic therapies. Glioma stem cells (GSCs) significantly contribute to GBM progression and post-treatment tumor relapse, therefore serving as a key therapeutic target; however, GSCs are resistant to conventional radiation therapy. Proton therapy is one of the newer cancer treatment modalities and its effects on GSCs function remain unclear. Here, by utilizing patient-derived GSCs, we show that proton radiation generates greater cytotoxicity in GSCs than x-ray photon radiation. Compared with photon radiation, proton beam irradiation induces more single and double strand DNA breaks, less H2AX phosphorylation, increased Chk2 phosphorylation, and reduced cell cycle recovery from G2 arrest, leading to caspase-3 activation, PARP cleavage, and cell apoptosis. Furthermore, proton radiation generates a large quantity of reactive oxygen species (ROS), which is required for DNA damage, cell cycle redistribution, apoptosis, and cytotoxicity. Together, these findings indicate that proton radiation has a higher efficacy in treating GSCs than photon radiation. Our data reveal a ROS-dependent mechanism by which proton radiation induces DNA damage and cell apoptosis in GSCs. Thus, proton therapy may be more efficient than conventional x-ray photon therapy for eliminating GSCs in GBM patients.

Home Numeracy Environments of Preschoolers: Examining Relations Among Mathematical Activities, Parent Mathematical Beliefs, and Early Mathematical Skills

Abstract: Research Findings: Early mathematical skills and knowledge are strongly related to long-term achievement, and yet the knowledge base regarding the mechanisms through which young children develop these skills and knowledge is limited. Although research has examined the relation of the home numeracy environment and children's early mathematics performance, results have been equivocal. The purpose of this study was 2-fold: (a) to describe parent-reported home mathematical activities and beliefs about mathematics and (b) to examine the relation between these constructs and preschool-age children's general school readiness skills as well as specific numeracy-related skills. Practice or Policy: Descriptive results suggest that parents engage in a range of mathematical activities in the home with varying frequency. Furthermore, results indicate relations between parent-reported mathematical activities and beliefs, but no statistically significant relations with preschool children's early mathematics performance ...