cssi/SciSciGPT-SciSciNet huggingface dataset:
Chest CBCT-based synthetic CT using cycle-consistent adversarial network with histogram matching

Image-guided radiation therapy (IGRT) is an important technological advancement that has significantly contributed to the accuracy of radiation oncology treatment plan delivery in the last decade. However, the current standard IGRT technique of linac-mounted kilovoltage (kV) cone-beam Computed Tomography (CBCT) has limited soft tissue contrast and is prone to image artifacts, which detract from its clinical utility. It is even worse in chest CBCT compared to other anatomic sites due to respiratory motion, which could lead to mistreatment. Therefore, it is highly desirable to improve CBCT image quality to the level of a planning CT scan. In this study, we propose a novel deep learning-based method, which integrates histogram matching (HM) into a cycle-consistent adversarial network (CycleGAN) framework called HM-CycleGAN, to learn a mapping between chest CBCT images and paired planning CT images obtained at simulation. Histogram matching is performed via an informative maximizing (MaxInfo) loss calculated between planning CT and the synthetic CT (sCT) derived by feeding CBCT into the HM-CycleGAN. The proposed algorithm was evaluated using 15 sets of patient chest CBCT data, each of which has 3-5 daily CBCTs. The planning/simulation CT was used as ground truth for sCTs derived from CBCTs. The mean absolute error (MAE), peak signal-to-noise ratio (PSNR), and normalized cross-correlation (NCC) indices were used to quantify the correction accuracy of the proposed algorithm. The mean MAE, PSNR and NCC were 63.2 HU, 30.2 dB, 0.96 over all CBCT fractions. The proposed method showed superior image quality, reduced noise, and artifact severity compared to the scatter correction method. Upon further improvement and clinical assessment, this method could further enhance accuracy of the current IGRT technique. The CBCT-based synthetic CT could be the critical component to achieve online adaptive radiation therapy.
Parainfluenza Virus 5 Priming Followed by SIV/HIV Virus-Like-Particle Boosting Induces Potent and Durable Immune Responses in Nonhuman Primates.

The search for a preventive vaccine against HIV infection remains an ongoing challenge, indicating the need for novel approaches. Parainfluenza virus 5 (PIV5) is a paramyxovirus replicating in the upper airways that is not associated with any animal or human pathology. In animal models, PIV5-vectored vaccines have shown protection against influenza, RSV, and other human pathogens. Here, we generated PIV5 vaccines expressing HIV envelope (Env) and SIV Gag and administered them intranasally to macaques, followed by boosting with virus-like particles (VLPs) containing trimeric HIV Env. Moreover, we compared the immune responses generated by PIV5-SHIV prime/VLPs boost regimen in naive vs a control group in which pre-existing immunity to the PIV5 vector was established. We demonstrate for the first time that intranasal administration of PIV5-based HIV vaccines is safe, well-tolerated and immunogenic, and that boosting with adjuvanted trimeric Env VLPs enhances humoral and cellular immune responses. The PIV5 prime/VLPs boost regimen induced robust and durable systemic and mucosal Env-specific antibody titers with functional activities including ADCC and neutralization. This regimen also induced highly polyfunctional antigen-specific T cell responses. Importantly, we show that diminished responses due to PIV5 pre-existing immunity can be overcome in part with VLP protein boosts. Overall, these results establish that PIV5-based HIV vaccine candidates are promising and warrant further investigation including moving on to primate challenge studies.
The Transcendental Quality of Digital Health and Social Media

In this paper we will be discussing the ethical risks of the transcendental quality of virtual spaces as they apply to digital health, especially in relation to new attempts to construct a “social mediome.” As we will discuss in the following section, phenomenology has raised criticisms against the context-lessness and ethical opacity of technology. The creation of a social mediome seems to come as an answer to this criticism as it creates a context that gives voice and flesh to human beings within their virtual lives. Yet, as we will discuss in this paper, the transcendental quality of this social mediome might involve the risk of normalizing health in a way that would prevent individuals from achieving well-being according to the meaning that they personally attribute to it.
Anesthetic and Surgical Dilemmas During Repair of Congenital Abdominal Wall Defects – Gastroschisis/Omphalocele in Newborns

Two of the most common neonatal surgical procedures in the United States are gastroschisis and omphalocele repair. The anesthetic considerations required for these infants must include temperature control, glucose management, positioning, blood loss, circulating blood volume, pain control, and drug metabolism. Abdominal procedures frequently require intubation; thus, the neonatal airway, respiratory, and cardiac physiology are crucial elements in the management of these patients. Detailed preoperative preparation, intraoperative vigilance with appropriate anesthetic adjustments, and constant communication with the surgeon during surgery are necessary. Neonatal intensive care unit (NICU) postoperative plans and a detailed handoff are crucial to good outcomes.
Racial discrimination and depressive symptoms mediated by conversations about race among students of color.

Racial discrimination is associated with adverse mental health outcomes among Students of Color. In order to address racial tensions, it is important to consider students' dialogues about race. The current study tested whether having positive and negative conversations about one's ethnic-racial group mediated the relation between racial discrimination at T1 and depressive symptoms 5 months later at T2 among 94 college Students of Color. Findings indicated that greater racial discrimination at T1 was associated with more frequent negative conversations about race at T2 (b = .38, p = .00), which was, in turn, associated with greater depressive symptoms at T2 (b = 2.73, p = .04); this pathway demonstrated significant mediation. However, positive conversations about race was not a significant mediator in this association. The current study highlights the importance of focusing on racial conversations after racial discrimination in order to minimize adverse effects on mental health among Students of Color.
Scintillation Light from Cosmic-Ray Muons in Liquid Argon

This paper reports the results of an experiment to directly measure the time-resolved scintillation signal from the passage of cosmic-ray muons through liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches. The experiment was carried out at the TallBo dewar facility at Fermilab using prototype light guide detectors and electronics developed for the Deep Underground Neutrino Experiment. Two models are presented for the time structure of the scintillation light, a phenomenological model and a composite model. Both models find τT = 1.52 μs for the decay time constant of the Ar2* triplet state. These models also show that the identification of the ``early'' light fraction in the phenomenological model, FE ≈ 25% of the signal, with the total light from singlet decays is an underestimate. The total fraction of singlet light is FS ≈ 36%, where the increase over FE is from singlet light emitted by the wavelength shifter through processes with long decay constants. The models were further used to compute the experimental particle identification parameter Fprompt, the fraction of light coming in a short time window after the trigger compared with the light in the total recorded waveform. The models reproduce quite well the typical experimental value ~0.3 found by dark matter and double β-decay experiments, which suggests this parameter provides a robust metric for discriminating electrons and muons from more heavily ionizing particles.
Simulation of diabetic retinopathy neovascularization in color digital fundus images

Diabetic retinopathy (DR) has been identified as a leading cause of blindness. One type of lesion, neovascularization (NV), indicates that the disease has entered a vision-threatening phase. Early detection of NV is thus clinically significant. Efforts have been devoted to use computer-aided analyses of digital retina images to detect DR. However, developing reliable NV detection algorithms requires large numbers of digital retinal images to test and refine approaches. Computer simulation of NV offers the potential of developing lesion detection algorithms without the need for large image databases of real pathology. In this paper, we propose a systematic approach to simulating NV. Specifically, we propose two algorithms based on fractal models to simulate the main structure of NV and an adaptive color generation method to assign photorealistic pixel values to the structure. Moreover, we develop an interactive system that provides instant visual feedback to support NV simulation guided by an ophthalmologist. This enables us to combine the low level algorithms with high-level human feedback to simulate realistic lesions. Experiments suggest that our method is able to produce simulated NVs that are indistinguishable from real lesions.
Probabilistic evaluation of counterfactual queries

Evaluation of counterfactual queries (e.g., "If A were true, would C have been true?") is important to fault diagnosis, planning, and determination of liability. We present a formalism that uses probabilistic causal networks to evaluate one's belief that the counterfactual consequent, C, would have been true if the antecedent, A, were true. The antecedent of the query is interpreted as an external action that forces the proposition A to be true, which is consistent with Lewis' Miraculous Analysis. This formalism offers a concrete embodiment of the "closest world" approach which (1) properly reflects common understanding of causal influences, (2) deals with the uncertainties inherent in the world, and (3) is amenable to machine representation.
Protective and damaging effects of stress mediators: central role of the brain.

The mind involves the whole body, and two-way communication between the brain and the cardiovascular, immune, and other systems via neural and endocrine mechanisms. Stress is a condition of the mind-body interaction, and a factor in the expression of disease that differs among individuals. It is not just the dramatic stressful events that exact their toll, but rather the many events of daily life that elevate and sustain activities of physiological systems and cause sleep deprivation, overeating, and other health-damaging behaviors, producing the feeling of being “stressed out.” Over time, this results in wear and tear on the body, which is called “allostatic load,” and it reflects not only the impact of life experiences but also of genetic load, individual lifestyle habits reflecting items such as diet, exercise, and substance abuse, and developmental experiences that set life-long patterns of behavior and physiological reactivity. Hormones associated with stress and allostatic load protect the body in the short run and promote adaptation by the process known as allostasis, but in the long run allostatic load causes changes in the body that can lead to disease. The brain is the key organ of stress, allostasis, and allostatic load, because it determines what is threatening and therefore stressful, and also determines the physiological and behavioral responses. Brain regions such as the hippocampus, amygdala, and prefrontal cortex respond to acute and chronic stress by undergoing structural remodeling, which alters behavioral and physiological responses. Translational studies in humans with structural and functional imaging reveal smaller hippocampal volume in stress-related conditions, such as mild cognitive impairment in aging and prolonged major depressive illness, as well as in individuals with low self-esteem. Alterations in amygdala and prefrontal cortex are also reported. Besides Pharmaceuticals, approaches to alleviate chronic stress and reduce allostatic load and the incidence of diseases of modern life include lifestyle change, and policies of government and business that would improve the ability of individuals to reduce their own chronic stress burden.
Trust based Approach for Improving Data Reliability in Industrial Sensor Networks

The resource constraints and unattended operation of wireless sensor networks make it difficult to protect nodes against capture and compromise. While cryptographic techniques provide some protection, they do not address the complementary problem of resilience to corrupted sensor data generated by failed or compromised sensors. Trusting data from unattended sensor nodes in critical applications can have disastrous consequences. We propose a behavior-based trust mechanism to address this problem in static sensor networks, in which the location of nodes is known. We take advantage of domain knowledge which includes: (i) physical constraints imposed by the local environment where sensors are located, (ii) expectations of the monitored physical phenomena; and (iii) sensor design and deployment characteristics. The system diagnoses and isolates faulty/malicious nodes even when readings of neighboring nodes are faulty. The goal of this system is to increase work effort and capabilities required by an attacker. The framework and related techniques of behavior-based trust are discussed in this paper.
Concurrent probabilistic temporal planning

Probabilistic planning problems are often modeled as Markov decision processes (MDPs), which assume that a single action is executed per decision epoch and that actions take unit time. However, in the real world it is common to execute several actions in parallel, and the durations of these actions may differ. This paper presents efficient methods for solving probabilistic planning problems with concurrent, durative actions. We adapt the formulation of Concurrent MDPs, MDPs which allow multiple instantaneous actions to be executed simultaneously. We add explicit action durations into the concurrent MDP model by encoding the problem as a concurrent MDP in an augmented state space. We present two novel admissible heuristics and one inadmissible heuristic to speed up the basic concurrent MDP algorithm. We also develop a novel notion of hybridizing an optimal and an approximate algorithm to yield a hybrid algorithm, which quickly generates high-quality policies. Experiments show that all our heuristics speedup the policy construction significantly. Furthermore, our approximate hybrid algorithm runs up to two orders of magnitude faster than other methods, while producing policies whose make-spans are typically within 5% of optimal.
A formal specification of an authorization model for object-oriented databases

We present here a formal specification, using Z, of an authorization model for object-oriented databases. We assume that the database and the authorization rules have already been defined and we describe the structure and the properties the rules should satisfy to represent a secure system. In this way, each new access rule can be tested for compliance with the requirement of maintaining a secure system. The use of implicit access rules (i.e., rules derived from others using data associations) makes this security model unique, and its representation in a formal model is of interest.
CHEMICAL SYNTHESIS OF GLYCOSYLPHOSPHATIDYLINOSITOL ANCHORS

Many eukaryotic cell-surface proteins and glycoproteins are anchored to the plasma membrane by glycosylphosphatidylinositols (GPIs), a family of glycolipids that are post-translationally attached to proteins at their C-termini. GPIs and GPI-anchored proteins play important roles in many biological and pathological events, such as cell recognition and adhesion, signal transduction, host defense, and acting as receptors for viruses and toxins. Chemical synthesis of structurally defined GPI anchors and GPI derivatives is a necessary step toward understanding the properties and functions of these molecules in biological systems and exploring their potential therapeutic applications. In the first part of this comprehensive article on the chemical synthesis of GPIs, classic syntheses of naturally occurring GPI anchors from protozoan parasites, yeast, and mammals are covered. The second part of the article focuses on recent diversity-oriented strategies for the synthesis of GPI anchors containing unsaturated lipids, “click chemistry” tags, and highly branched and modified structures.
Electron transfer in transition metal-pteridine systems

The combination of a pterin and a transition metal in many enzymes is the motivation for exploring the chemistry of pteridine complexes in detail. Unlike other biological ligands for essential transition metals, pterin is unique in displaying multi-electron redox reactivity, an ability that resembles the redox capabilities of transition metals. It is perhaps because these two partners, metal and pterin, have this chemical similarity that their compounds defy traditional categorization by formal oxidation number. The result challenges the chemist to formulate fresh interpretations of these deceptively ordinary complexes. This review concerns reports of metal-pterin complexes that appeared from the early 1980s through 1996. In a few cases older literature is briefly mentioned to build a context for the newer work. The review comprises four sections. Section 1 introduces the pteridine family and its important contributions to biochemistry. Section 2 is devoted to studies of molybdenum (6+) complexes reacted with reduced pterins. Section 3 describes redox interactions between reduced pterins and the first row metals copper and iron. Finally, Section 4 turns to a discussion of the electronic interactions in flavin complexes of various metals. An Epilogue closes the review.
Parallelizing MCMC with Random partition trees

The modern scale of data has brought new challenges to Bayesian inference. In particular, conventional MCMC algorithms are computationally very expensive for large data sets. A promising approach to solve this problem is embarrassingly parallel MCMC (EP-MCMC), which first partitions the data into multiple subsets and runs independent sampling algorithms on each subset. The subset posterior draws are then aggregated via some combining rules to obtain the final approximation. Existing EP-MCMC algorithms are limited by approximation accuracy and difficulty in resampling. In this article, we propose a new EP-MCMC algorithm PART that solves these problems. The new algorithm applies random partition trees to combine the subset posterior draws, which is distribution-free, easy to re-sample from and can adapt to multiple scales. We provide theoretical justification and extensive experiments illustrating empirical performance.
Translating Neuroethics: Reflections from Muslim Ethics

Muslim ethics is cautiously engaging developments in neuroscience. In their encounters with developments in neuroscience such as brain death and functional magnetic resonance imaging procedures, Muslim ethicists might be on the cusp of spirited debates. Science and religion perform different kinds of work and ought not to be conflated. Cultural translation is central to negotiating the complex life worlds of religious communities, Muslims included. Cultural translation involves lived encounters with modernity and its byproduct, modern science. Serious ethical debate requires more than just a mere instrumental encounter with science. A robust Muslim approach to neuroethics might require an emulsion of religion and neuroscience, thought and body, and body and soul. Yet one must anticipate that Muslim debates in neuroethics will be inflected with Muslim values, symbols and the discrete faith perspectives of this tradition with meanings that are specific to people who share this worldview and their concerns.
Forecasting uncertain events with small groups

We present a novel methodology for predicting future outcomes that uses small numbers of individuals participating in an imperfect information market. By determining their risk attitudes and performing a nonlinear aggregation of their predictions, we are able to assess the probability of the future outcome of an uncertain event and compare it to both the objective probability of its occurrence and the performance of the market as a whole. Experiments show that this nonlinear aggregation mechanism vastly outperforms both the imperfect market and the best of the participants.
The tate pairing via elliptic nets

We derive a new algorithm for computing the Tate pairing on an elliptic curve over a finite field. The algorithm uses a generalisation of elliptic divisibility sequences known as elliptic nets, which are maps from Zn to a ring that satisfy a certain recurrence relation. We explain how an elliptic net is associated to an elliptic curve and reflects its group structure. Then we give a formula for the Tate pairing in terms of values of the net. Using the recurrence relation we can calculate these values in linear time. Computing the Tate pairing is the bottleneck to efficient pairing-based cryptography. The new algorithm has time complexity comparable to Miller's algorithm, and should yield to further optimisation.
Imaging of a Complete Sample of IR-Excess PG QSOS

Sanders et al. (1988) proposed an evolutionary connection between Ultraluminous Infrared Galaxies (ULIGs) and optically-selected QSOs. In this scenario, mergers of dust and gas-rich galaxies provide the fuel to create and/or fuel an AGN and circumnuclear starburst. This dust completely enshrouds the AGN, and subsequent reradiation of the short-wavelength AGN emission produces the high far-IR luminositiy that defines ULIGs as a class. Dust clearing by superwinds eventually begins to unveil the central AGN, which is then perceived as a QSO. Surace et al. (1998, 2000) carried out a comprehensive program of multi-wavelength high spatial resolution observations using HST and ground-based tip/tilt in order to characterize the morphology and colors of ULIGs. Particular emphasis was given to ULIGs with “warm” mid-IR colors, whose spectral energy distributions (SEDs) and emission line features suggested that they were the most evolved ULIGs in the process of becoming QSOs. These studies showed that ULIGs were the merger of two L* galaxies, and that they had compact central sources whose luminosity and colors are similar to reddened AGN. They also possess “knots” of star formation distributed in the circumnuclear regions and along the merger-generated tidal debris.
MAXIMUM LIKELIHOOD ESTIMATION OF A RANDOM COEFFICIENT MEAT DEMAND SYSTEM

The paper demonstrates that random coefficient models can be estimated by maximum likelihood if they are specified as generalized least squares models. The paper uses maximum likelihood estimation on a random-coefficient, meat-demand system. Statistical tests show that price elasticities are random, but expenditure elasticities are not. The statistical tests allow one to count the number of factors that cause randomness without requiring one to know what they are. There appear to be only two factors that make the price elasticities random.
Type Inference for Parameterized Race-Free Java

We study the type system introduced by Boyapati and Rinard in their paper “A Parameterized Type System for Race-Free Java Programs” and try to infer the type annotations (“lock types”) needed by their type checker to show that a program is free of race conditions. Boyapati and Rinard automatically generate some of these annotations using default types and static inference of lock types for local variables, but in practice, the programmer still needs to annotate on the order of 1 in every 25 lines of code. We use run-time techniques, based on the lockset algorithm, in conjunction with some static analysis to automatically infer most or all of the annotations.
Unitary cavity spin squeezing by quantum erasure

Deterministic light-induced spin squeezing in an atomic gas is limited by photon shot noise or, equivalently, by atomic state information escaping with the light field mediating the effective atom-atom interaction. We show theoretically that the performance of cavity spin squeezing [M. H. Schleier-Smith, I. D. Leroux, and V. Vuleti\ifmmode \acute{c}\else \'{c}\fi{}, Phys. Rev. A 81, 021804(R) (2010)] can be substantially improved by erasing the light-atom entanglement, and propose several methods for doing so. Accounting for light scattering into free space, quantum erasure improves the scaling of cavity squeezing from ${S}^{\ensuremath{-}1/2}$ to ${S}^{\ensuremath{-}2/3}$, where $S$ is the total atomic spin.
Montroseite, a new vanadium oxide from the Colorado plateaus

Report discussing the properties of montroseite, a new vanadium mineral that was found in four mines in western Colorado and in two mines in eastern Utah.
Teaching a schema translator to produce O/R views

This paper describes a rule-based algorithm to derive a relational schema from an extended entity-relationship model. Our work is based on an approach by Atzeni and Torlone in which the source EER model is imported into a universal metamodel, a series of transformations are performed to eliminate constructs not appearing in the relational metamodel, and the result is exported. Our algorithm includes novel features that are needed for practical object to relational mapping systems: First, it generates forward-and reverse-views that transform instances of the source model into instances of the target and back again. These views automate the object-to-relational (O/R) mapping. Second, it supports a flexible mapping of inheritance hierarchies to flat relations that subsumes and extends prior approaches. Third, it propagates incremental updates of the source model into incremental updates of the target. We prove the algorithm's correctness and demonstrate its practicality in an implementation.
Sample Size and Power Calculation

The precision with which sample statistics estimate population parameters is strongly influenced by the number of observations. Statistical power analysis provides a method of determining the sample sizes needed to control for errors in hypothesis testing. Power is largest when the effects being studied are large and the sample is large. Keywords: power; standard error; effect size; noncentral F; analysis of variance
Sustaining economic welfare : estimating changes in per capita wealth

With the notable exception of China, in most countries with below-median per capita income the growth rate of the population is greater than that of total wealth. This trend is ultimately unsustainable. For many of these countries, policies for sustainability will require both boosting savings and slowing population growth. The World Bank's World Development Indicators 1999 highlights for the first time the "genuine" rate of saving for more than 100 countries around the globe. Genuine saving values the total change in economic assets, thereby providing an indicator of whether an economy is on a sustainable path. The Bank's new estimates of genuine saving broaden the usual national accounts definitions of assets to include human capital, minerals, energy, forest resources, and the stock of atmospheric carbon dioxide. Genuine saving measures the change in total assets rather than the change in per capita assets. Genuine saving data may answer the question, "Did total wealth rise or fall over the accounting period?" But they do not address the question of whether an economy is sustainable with a growing population. Genuine saving could be positive even though per capita wealth is declining. Hamilton explores the issue of measuring changes in per capita wealth - factoring in both growth in total assets (as measured by genuine saving) and population growth - as a more comprehensive indicator of sustainability. First he develops a theoretical approach to estimating total wealth. Then he presents cross-country estimates of changes in per capita wealth. Based on preliminary estimates, he concludes that in the majority of countries below the median per capita income, wealth is accumulating more slowly than the population is growing. This paper - a product of the Office of the Director, Environment Department - is part of a larger effort in the department to apply economic approaches to environmental management. The author may be contacted at khamilton@worldbank.org.
Income composition, endogenous fertility and schooling investments in children

This paper studies how the composition of income between mothers and fathers affects fertility and schooling investments in children, using data from the 1976 and 1996 PNAD, a Brazilian household survey. Income composition affects the time cost of fertility because mothers and fathers allocate different amounts of time to child-rearing. These effects are in turn transmitted to investments in children through a tradeoff between quantity and quality of children. The main contribution of this paper is twofold. First, it derives new implications about the relationship between household income composition and schooling investments in children. Second, this paper devises and implements an empirical approach to assess these implications, using two cross-sections of fertility and schooling data from Brazil. The main empirical findings of the paper can be summarized as follows. First, the empirical analysis shows that a larger negative effect of the mother's labor income on fertility in 1996 is associated with a larger positive effect on the adult child's schooling, reflecting the interaction between quantity and quality of children. Second, the larger negative effect of the mother's labor income on fertility in 1996 is associated with a reduction in the effect of other determinants of number of children. This suggests that an increase in the relative importance of time costs of fertility may be an important determinant of variations in fertility over time in Brazil and other developing countries.
The ryotron - A new cryogenic device

This paper describes a cryogenic electronic variable inductor called the ryotron. This device may be represented as a dc-isolated two-port network useful for both digital and analog circuits. Included are 1) general introduction, 2) the principle of operation, 3) experimental results, 4) device applications, and 5) discussion.
Description of earthquake aftershock sequences using prototype point patterns

We introduce the use of prototype point patterns to characterize the behavior of a typical aftershock sequence from the global Harvard earthquake catalog. These prototypes are used not only for data description and summary but also to identify outliers and to classify sequences into groups exhibiting similar aftershock behavior. We find that a typical shallow earthquake of magnitude between 7.5 and 8.0 has five aftershocks of magnitude at least 5.5, and these aftershocks are roughly evenly distributed in logtime between 0.113 days and 2.0 years after the mainshock. The relative magnitudes and distances from the mainshock for the typical aftershock sequence are characterized as well.
A Low Power Pseudo-Random BIST Technique

Peak power consumption during testing is an important concern. For scan designs, a high level of switching activity is created in the circuit during scan shifts, which increases power consumption considerably. In this paper we propose a pseudo-random BIST scheme for scan designs, which reduces the peak power consumption as well as the average power consumption as measured by the switching activity in the circuit. The method reduces the switching activity in the scan chains and the activity in the circuit under test by limiting the scan shifts to a portion of the scan chain structure using scan chain disable. Experimental results on various benchmark circuits demonstrate that the technique reduces the switching activity caused by scan shifts.
Accreting Neutron Stars in Low-Mass X-Ray Binary Systems

Using the Rossi X-ray Timing Explorer (RossiXTE ), astronomers have discovered that disk-accreting neutron stars with weak magnetic fields produce three distinct types of high-frequency X-ray oscillations. These oscillations are powered by release of the binding energy of matter falling into the strong gravitational field of the star or by the sudden nuclear burning of matter that has accumulated in the outermost layers of the star. The frequencies of the oscillations reflect the orbital frequencies of gas deep in the gravitational field of the star and/or the spin frequency of the star. These oscillations can therefore be used to explore fundamental physics, such as strong-field gravity and the properties of matter under extreme conditions, and important astrophysical questions, such as the formation and evolution of millisecond pulsars. Observations using RossiXTE have shown that some two dozen in low-mass X-ray binary systems have the spin rates and magnetic fields required to become millisecond radio-emitting pulsars when accretion ceases, but that few have spin rates above about 600 Hz. The properties of these stars show that the paucity of spin rates greater than 600 Hz is due in part to the magnetic braking component of the accretion torque and to the limited amount of angular momentum that can be accreted in such systems. Further study will show whether braking by gravitational radiation is also a factor. Analysis of the kilohertz oscillations has provided the first evidence for the existence of the innermost stable circular orbit around dense relativistic stars that is predicted by strong-field general relativity. It has also greatly narrowed the possible descriptions of ultradense matter.
Studying aesthetics in photographic images using a computational approach

Aesthetics, in the world of art and photography, refers to the principles of the nature and appreciation of beauty. Judging beauty and other aesthetic qualities of photographs is a highly subjective task. Hence, there is no unanimously agreed standard for measuring aesthetic value. In spite of the lack of firm rules, certain features in photographic images are believed, by many, to please humans more than certain others. In this paper, we treat the challenge of automatically inferring aesthetic quality of pictures using their visual content as a machine learning problem, with a peer-rated online photo sharing Website as data source. We extract certain visual features based on the intuition that they can discriminate between aesthetically pleasing and displeasing images. Automated classifiers are built using support vector machines and classification trees. Linear regression on polynomial terms of the features is also applied to infer numerical aesthetics ratings. The work attempts to explore the relationship between emotions which pictures arouse in people, and their low-level content. Potential applications include content-based image retrieval and digital photography.
Novel Approaches to the Construction of Miniaturized Analytical Instrumentation

This paper focuses on the design, construction, preliminary testing, and potential applications of three forms of miniaturized analytical instrumentation. The first is an optical fiber instrument for monitoring pH and other cations in aqueous solutions. The instrument couples chemically selective indicators that were immobilized at porous polymeric films with a hardware package that provides the excitation light source, required optical components, and detection and data processing hardware. The second is a new form of a piezoelectric mass sensor. The sensor was fabricated by the deposition of a thin (5.5 micron) film of piezoelectric aluminum nitride (AIN). The completed deposition process yields a thin film resonator (TFR) that is shaped as a 400 micron square and supports a standing bulk acoustic wave in a longitudinal mode at frequencies of approx. 1 GHz. Various deposition and vapor sorption studies indicate that the mass sensitivity of the TFR's rival those of the most sensitive mass sensors currently available, though offering such performance in a markedly smaller device. The third couples a novel form of liquid chromatography with microlithographic miniaturization techniques. The status of the miniaturization effort, the goal of which is to achieve chip-scale separations, is briefly discussed.
Private non-state sector engagement in the provision of educational services at the primary and secondary levels in South Asia : an analytical review of its role in school enrollment and student achievement

Private (non-state) sector engagement in the provision of educational services at the primary and secondary levels in South Asia has recently undergone remarkable growth. This type of education comes in various forms, such as schools financed and managed by the private sector, schools financed by the government and managed by the private sector, private school vouchers, and tutoring outside the classroom. According to recent household survey data, almost one-third of school-goers aged 6 to 18 years in South Asia go to private schools, with a high concentration in Bangladesh, India, Nepal, and Pakistan. Data for India, Nepal, and Pakistan show that on average, private schools perform at least as well as government schools on student test scores, after controlling for socioeconomic factors, and they do so at significantly lower costs to society. However, student achievement varies greatly across schools of each type, with many weak private schools as well as strong government schools. Substantial, albeit indirect, evidence points to teacher behavior and accountability as an important driver of the effectiveness of private schools. In the long run, however, many factors may play important roles in sustaining the private sector's advantage. Another risk is that overall poor quality in a large government sector may set a low benchmark for the private sector. The findings cast doubt on the effectiveness of government regulations for private schools, given weak institutional capacity. Public-private partnerships with effective accountability mechanisms could leverage both equity and efficiency. Finally, it appears important to understand and customize teaching to the child's individual level.
Iteration bound analysis and throughput optimum architecture of SHA-256 (384,512) for hardware implementations

The hash algorithm forms the basis of many popular cryptographic protocols and it is therefore important to find throughput optimal implementations. Though there have been numerous published papers proposing high throughput architectures, none of them have claimed to be optimal. In this paper, we perform iteration bound analysis on the SHA2 family of hash algorithms. Using this technique, we are able to both calculate the theoretical maximum throughput and determine the architecture that achieves this throughput. In addition to providing the throughput optimal architecture for SHA2, the techniques presented can also be used to analyze and design optimal architectures for some other iterative hash algorithms.
Learning to Verify Safety Properties

We present a novel approach for verifying safety properties of finite state machines communicating over unbounded FIFO channels that is based on applying machine learning techniques. We assume that we are given a model of the system and learn the set of reachable states from a sample set of executions of the system, instead of attempting to iteratively compute the reachable states. The learnt set of reachable states is then used to either prove that the system is safe or to produce a valid execution of the system leading to an unsafe state (i.e. a counterexample). We have implemented this method for verifying FIFO automata in a tool called Lever that uses a regular language learning algorithm called RPNI. We apply our tool to a few case studies and report our experience with this method. We also demonstrate how this method can be generalized and applied to the verification of other infinite state systems.
Limits on achievable robustness against coprime factor uncertainty

Abstract We consider the problem of robustness optimization against normalized coprime factor uncertainty in single-input, single-output systems. We show that loop shapes known from classical analysis to be inconsistent with closed-loop robust stability will tend to have poor optimal robustness. Such loop shapes include those with a high crossover frequency relative to a nonminimum phase zero, a low crossover frequency relative to an unstable pole, or a rapid rolloff rate near gain crossover. Our results consist of a set of lower bounds on the optimal cost of the robustness optimization problem, each lower bound being appropriate to one of these three problematic loop shapes. The lower bounds are derived using the Poisson integral, and display the qualitative relationship between the loop shape and the level of optimal robustness.
Three-dimensional radiative transfer

Radiative Transfer (RT) effects play a crucial role in the thermal history of the intergalactic medium. Here I discuss recent advances in the development of numerical methods that introduce RT to cosmological hydrodynamics. These methods can also readily be applied to time dependent problems on interstellar and galactic scales.
Current Issues in Sampling-Based Motion Planning

In this paper, we discuss the field of sampling-based motion planning. In contrast to methods that construct boundary representations of configuration space obstacles, samplingbased methods use only information from a collision detector as they search the configuration space. The simplicity of this approach, along with increases in computation power and the development of efficient collision detection algorithms, has resulted in the introduction of a number of powerful motion planning algorithms, capable of solving challenging problems with many degrees of freedom. First, we trace how sampling-based motion planning has developed. We then discuss a variety of important issues for sampling-based motion planning, including uniform and regular sampling, topological issues, and search philosophies. Finally, we address important issues regarding the role of randomization in sampling-based motion planning.
A remark on Littlewood-Paley theory for the distorted Fourier transform

We consider the classical theorems of Mikhlin and Littlewood-Paley from Fourier analysis in the context of the distorted Fourier transform. The latter is defined as the analogue of the usual Fourier transform as that transformation which diagonalizes a Schrodinger operator -Δ+V. We show that for such operators which display a zero energy resonance the full range 1 < p < oo in the Mikhlin theorem cannot be obtained: in the radial, three-dimensional case it shrinks to 3 2 < p < 3.
Alcohol Consumption, Deterrence and Crime in New York City

This paper investigates the relationship between alcohol consumption, deterrence, and crime for New York City. We use monthly time-series data from 1983 to 2001 to analyze the impacts of variations in both alcohol consumption and deterrence on seven “index” crimes. We tackle the endogeneity of arrests and the police force by exploiting the temporal independence of crime and deterrence in these high-frequency data, and we address the endogeneity of alcohol by using instrumental variables where alcohol sales are instrumented with city and state alcohol taxes and minimum drinking age. We find that alcohol consumption is positively related to assault, rape, and larceny crimes but not murder, robbery, burglary, or motor vehicle theft. We find strong deterrence for all crimes except assault and rape. Generally, deterrence effects are stronger than alcohol effects.
3-manifolds with planar presentations and the width of satellite knots

We consider compact 3-manifolds M having a submersion h to R in which each generic point inverse is a planar surface. The standard height function on a submanifold of S 3 is a motivating example. To (M, h) we associate a connectivity graph Γ. For M ⊂ S 3 , Γ is a tree if and only if there is a Fox reimbedding of M which carries horizontal circles to a complete collection of complementary meridian circles. On the other hand, if the connectivity graph of S 3 - M is a tree, then there is a level-preserving reimbedding of M so that S 3 - M is a connected sum of handlebodies. Corollary. • The width of a satellite knot is no less than the width of its pattern knot and so • w(K 1 #K 2 ) > max(w(K 1 ), w(K 2 )).
Characterizing the set of coherent lower previsions with a finite number of constraints or vertices

The standard coherence criterion for lower previsions is expressed using an infinite number of linear constraints. For lower previsions that are essentially defined on some finite set of gambles on a finite possibility space, we present a reformulation of this criterion that only uses a finite number of constraints. Any such lower prevision is coherent if it lies within the convex polytope defined by these constraints. The vertices of this polytope are the extreme coherent lower previsions for the given set of gambles. Our reformulation makes it possible to compute them. We show how this is done and illustrate the procedure and its results.
Validation of Factors Influencing Successful Small Scale Farming in North Carolina

This phase of the research project involves developing a survey instrument to test the validity and predictive value of the variables identified in previous case studies. Given the importance of small farm viability, this research project focuses on identifying ways to further enhance successful small farming in North Carolina. The survey instrument was designed to solicit production and financial data, attitudes and beliefs about farming, as well as demographic questions. The results demonstrated that successful farmers indicators were the “love of farming” and “manageable debt”. Other strong indicators of successful farmers included a combination of marketing strategies that utilize technology such as websites as well as local farmers markets and educational level. Knowledge about the successful small farm is likely to provide valuable information about how to evaluate the “successfulness” of small farm operations and produce best practices models for small scale farm operations.
REAL-TIME FAULT DIAGNOSIS FOR PROPULSION SYSTEMS

Current research toward real time fault diagnosis for propulsion systems at NASA-Lewis is described. The research is being applied to both air breathing and rocket propulsion systems. Topics include fault detection methods including neural networks, system modeling, and real time implementations.