cssi/SciSciGPT-SciSciNet huggingface dataset:
Keystone Sector Identification

This chapter presents a new a method for identifying keystone sectors in communities, where sectors are broadly defined to include churches, clubs, associations, and public institutions as well as different types of businesses and industries. In an arch, the keystone is the one with the unique shape at the top of the arch that is critical for the arch’s structural stability. The term keystone species was first coined by ecologists in the late 1960s with respect to the species responsibility for the structure and integrity of an ecosystem. We now coin the term for use in community development analysis. In a community, the keystone sector is one that plays a unique role and without which the community is fundamentally and detrimentally altered.
Valve Corporation: Composing Internal Markets

Discussions of the Valve Corporation are always enlightening. The skeptic wonders how much is rhetoric and recruiting ploy and how much is real. Is there clear evidence that this organizational design actually works – that it is efficient in this setting? While revenues per employee are quite remarkable, cause and effect are unclear. Is “boss-less-ness” the cause of high sales per employee or simply the result of high sales per employee, fueled from earlier success? The same question could be asked of Google’s unusual organizational approach. Is Google’s success the result of its extensive autonomy granted to employees, or is its past success the enabling cause of such autonomy? Such questions, of course, are empirically unanswerable here. I therefore set them aside and assume this organizational specimen is efficient – well-suited to its environment – and proceed with further commentary.
Analysis of Instability in Electrical Machines

While there exist numerous studies of electromechanical instabilities of specific electrical machines in constant or periodic speed operation, a broader perspective is not commonly offered. In contrast, a general machine model is used here to present essential and common features of these stability analyses. Fundamental issues are illuminated at this level of generality before specialization to the details of a specific machine. To begin, Park-transformable machines in constant-speed operation are considered. The local dynamics of these machines are linear and time-invariant. For such machines it is shown that instability may be analyzed in a useful way via systematically obtained reduced-order models. This is illustrated by significantly expanding an earlier study of a hybrid stepping motor. The more general situation in which the linearized models that govern local behavior are periodically varying is considered next. Classical Floquet theory is reviewed to provide the tools needed for stability analysis in this situation.
Stabilization on zero-error manifolds and the nonlinear servomechanism problem

The extended-linearization methodology is applied to the nonlinear servomechanism problem for the case of time-varying exogenous signals. This yields a novel approach to establishing exponential manifold, known as the zero-error manifold. Advantages of the approach are that the underlying theory is relatively simple, and that a requirement of small derivatives for the exogenous signals is used rather than a requirement that the exogenous signals remain small. Thus certain cases of unbounded exogenous signals can be treated. A transmission zero condition for existence of the requisite zero-error manifold is given. >
Beam dynamics enhancement due to accelerating field symmetrization in the BNL/SLAC/UCLA 1.6 cell S-band photocathode RF gun

A 1.6 cell photocathode S-Band gun developed by the BNL/SLAC/UCLA collaboration is now in operation at the Brookhaven Accelerator Test Facility (ATF). One of the main features of this RF gun is the symmetrization of the RF coupling iris with a identical vacuum pumping port located in the full cell. The effects of the asymmetry caused by the RF coupling iris were experimentally investigated by positioning a metallic plunger at the back wall of the vacuum port iris. The higher order modes produced were studied using electron beamlets with 8-fold symmetry. The 8-fold beamlets were produced by masking the laser beam. These experimental results indicate that the integrated electrical center and the geometrical center of the gun are within 175 /spl mu/m,. which is within the laser alignment tolerance of 250 /spl mu/m.
MicroRNA signature of cis-platin resistant vs. cis-platin sensitive ovarian cancer cell lines

Ovarian cancer is the leading cause of death from gynecologic cancer in women worldwide. According to the National Cancer Institute, ovarian cancer has the highest mortality rate among all the reproductive cancers in women. Advanced stage diagnosis and chemo/radio-resistance is a major obstacle in treating advanced ovarian cancer. The most commonly employed chemotherapeutic drug for ovarian cancer treatment is cis-platin. As with most chemotherapeutic drugs, many patients eventually become resistant to cis-platin and therefore, diminishing its effect. The efficacy of current treatments may be improved by increasing the sensitivity of cancer cells to chemo/radiation therapies. The present study is focused on identifying the differential expression of regulatory microRNAs (miRNAs) between cis-platin sensitive (A2780), and cis-platin resistant (A2780/CP70) cell lines. Cell proliferation assays were conducted to test the sensitivity of the two cell lines to cis-platin. Differential expression patterns of miRNA between cis-platin sensitive and cis-platin resistant cell lines were analyzed using novel LNA technology. Our results revealed changes in expression of 11 miRNAs out of 1,500 miRNAs analyzed. Out of the 11 miRNAs identified, 5 were up-regulated in the A2780/CP70 cell line and 6 were down regulated as compared to cis-platin sensitive A2780 cells. Our microRNA data was further validated by quantitative real-time PCR for these selected miRNAs. Ingenuity Pathway Analysis (IPA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was performed for the selected miRNAs and their putative targets to identify the potential pathways and networks involved in cis-platin resistance. Our data clearly showed the differential expression of 11 miRNAs in cis-platin resistant cells, which could potentially target many important pathways including MAPK, TGF-β signaling, actin cytoskeleton, ubiquitin mediated proteasomal pathway, Wnt signaling, mTOR signaling, Notch signaling, apoptosis, and many other signaling pathways. Manipulation of one or more of these miRNAs could be an important approach for ovarian cancer chemotherapy.
On Translating Camfranglais and Other Camerounismes

Post-colonial creative writers constantly resort to creolization and indigenization as modes of linguistic and cultural appropriation. In other words, these writers tend to transpose the imprint of their cultural backgrounds onto their fictional works.This paper addresses the challenges posed by language mixing to the literary translator. Rather than interrogate the theories of translation, the paper seeks to bring new insights to the pragmatics of translation – ways in which the literary translator grapples with meaning discernment and rendition when faced with texts couched in indigenized and hybridized linguistic forms, namely creoles, pidgins, camfranglais, and other forms of hybrid languages. There are clear and obvious benefits in literary indigenization (i.e., a larger audience, self-representation, etc) but how do these benefits transform when these languages are contextualized in literature? In what ways is pidginization complicit or at variance with imperial languages? And what are the ramifications of such complicity or variance for the translator? What forms of discursive agencies are made available through translation?
Transcriptional network classifiers

Gene interactions play a central role in transcriptional networks. Many studies have performed genome-wide expression analysis to reconstruct regulatory networks to investigate disease processes. Since biological processes are outcomes of regulatory gene interactions, this paper develops a system biology approach to infer function-dependent transcriptional networks modulating phenotypic traits, which serve as a classifier to identify tissue states. Due to gene interactions taken into account in the analysis, we can achieve higher classification accuracy than existing methods. Our system biology approach is carried out by the Bayesian networks framework. The algorithm consists of two steps: gene filtering by Bayes factor followed by collinearity elimination via network learning. We validate our approach with two clinical data. In the study of lung cancer subtypes discrimination, we obtain a 25-gene classifier from 111 training samples, and the test on 422 independent samples achieves 95% classification accuracy. In the study of thoracic aortic aneurysm (TAA) diagnosis, 61 samples determine a 34-gene classifier, whose diagnosis accuracy on 33 independent samples achieves 82%. The performance comparisons with three other popular methods, PCA/LDA, PAM, and Weighted Voting, confirm that our approach yields superior classification accuracy and a more compact signature. The system biology approach presented in this paper is able to infer function-dependent transcriptional networks, which in turn can classify biological samples with high accuracy. The validation of our classifier using clinical data demonstrates the promising value of our proposed approach for disease diagnosis.
Robust fitting of ellipses and spheroids

Ellipse and ellipsoid fitting has been extensively researched and widely applied. Although traditional fitting methods provide accurate estimation of ellipse parameters in the low-noise case, their performance is compromised when the noise level or the ellipse eccentricity are high. A series of robust fitting algorithms are proposed that perform well in high-noise, high-eccentricity ellipse/spheroid (a special class of ellipsoid) cases. The new algorithms are based on the geometric definition of an ellipse/spheroid, and improved using global statistical properties of the data. The efficacy of the new algorithms is demonstrated through simulations.
Vertebral artery injury in C1-2 transarticular screw fixation : results of a survey of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves

Object. The 847 active members of the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Section on Disorders of the Spine and Peripheral Nerves were surveyed to quantitate the risk of vertebral artery (VA) injury during C1–2 transarticular screw placement. Methods. This retrospective study elicited the number of patients treated with transarticular screws, the number of screws placed, the incidence of VA injury and subsequent neurological deficit, and the management of known or suspected VA injury. Two hundred thirteen (25.1%) of the 847 surgeons responded. One hundred one respondents (47.4%) had placed a total of 2492 C1–2 transarticular screws in 1318 patients. Thirty-one patients (2.4%) had known VA injuries and an additional 23 patients (1.7%) were suspected of having injuries. However, only two (3.7%) of the 54 patients with known or suspected VA injuries exhibited subsequent neurological deficits and only one (1.9%) died of bilateral VA injury. Other iatrogen...
ANGULAR MOMENTUM AND GALAXY FORMATION REVISITED

Motivated by a new wave of kinematical tracers in the outer regions of early-type galaxies (ellipticals and lenticulars), we re-examine the role of angular momentum in galaxies of all types. We present new methods for quantifying the specific angular momentum j, focusing mainly on the more challenging case of early-type galaxies, in order to derive firm empirical relations between stellar j and mass M (thus extending earlier work by Fall). We carry out detailed analyses of eight galaxies with kinematical data extending as far out as 10 effective radii, and find that data at two effective radii are generally sufficient to estimate total j reliably. Our results contravene suggestions that ellipticals could harbor large reservoirs of hidden j in their outer regions owing to angular momentum transport in major mergers. We then carry out a comprehensive analysis of extended kinematic data from the literature for a sample of ~100 nearby bright galaxies of all types, placing them on a diagram of j versus M . The ellipticals and spirals form two parallel j -M tracks, with log-slopes of ~0.6, which for the spirals are closely related to the Tully-Fisher relation, but for the ellipticals derives from a remarkable conspiracy between masses, sizes, and rotation velocities. The ellipticals contain less angular momentum on average than spirals of equal mass, with the quantitative disparity depending on the adopted K-band stellar mass-to-light ratios of the galaxies: it is a factor of ~3-4 if mass-to-light ratio variations are neglected for simplicity, and ~7 if they are included. We decompose the spirals into disks and bulges and find that these subcomponents follow j -M trends similar to the overall ones for spirals and ellipticals. The lenticulars have an intermediate trend, and we propose that the morphological types of galaxies reflect disk and bulge subcomponents that follow separate, fundamental j -M scaling relations. This provides a physical motivation for characterizing galaxies most basically with two parameters: mass and bulge-to-disk ratio. Next, in an approach complementary to numerical simulations, we construct idealized models of angular momentum content in a cosmological context, using estimates of dark matter halo spin and mass from theoretical and empirical studies. We find that the width of the halo spin distribution cannot account for the differences between spiral and elliptical j , but that the observations are reproduced well if these galaxies simply retained different fractions of their initial j complement (~60% and ~10%, respectively). We consider various physical mechanisms for the simultaneous evolution of j and M (including outflows, stripping, collapse bias, and merging), emphasizing that the vector sum of all such processes must produce the observed j -M relations. We suggest that a combination of early collapse and multiple mergers (major or minor) may account naturally for the trend for ellipticals. More generally, the observed variations in angular momentum represent simple but fundamental constraints for any model of galaxy formation.
On the Critical Ionization Velocity Effect in Interstellar Space and Possible Detection of Related Continuum Emission

Interstellar neutral hydrogen (HI) emission spectra manifest several families of linewidths whose numerical values (34, 13, and 6 km/s) appear to be related to the critical ionization velocities (CIVs) of the most abundant interstellar atomic species. Extended new analysis of HI emission profiles shows that the 34-km/s-wide component, which probably corresponds to the CIV for helium, is pervasive. The 34-km/s-wide linewidth family is found in low-velocity (local) HI profiles and in the so-called high-velocity clouds (HVCs). In addition, published studies of HI linewidths found in the Magellanic Stream, Very High Velocity Clouds, and Compact HVCs, all of which are believed to be intergalactic, have noted that the typical values are of the same order. If the CIV effect does play a role in interstellar space, it may be expected to produce locally enhanced electron densities where rapidly moving neutral gas masses interact with the surrounding plasma. Evidence that suggests that this phenomenon is occurring in interstellar space is presented. It manifests as a spatial association between peaks in HI structure offset with respect to peaks in high-frequency radio continuum data obtained with the Wilkinson Microwave Anisotropy Probe.
Complex rare-earth tetrelides, RE5(SixGe1−x)4: New materials for magnetic refrigeration and a superb playground for solid state chemistry

A “giant magnetocaloric effect” discovered in 1997 for Gd5Si2Ge2 near room temperature has triggered optimism that environmentally-friendly, solid-state magnetic refrigeration may be viable to replace gas-compression technology in the near future. Gd5Si2Ge2 is one member of an extensive series of rare-earth compounds, RE5(SixGe1−x)4. Due to the complexity of their structures and flexibility associated with chemical compositions, this series is an attractive “playground” to study the interrelationships among composition, structure, physical properties and chemical bonding. This tutorial review, which is directed toward students and researchers interested in structure–property relationships in solids, summarizes recent efforts concerning the synthesis, structure, physical properties, chemical bonding and chemical modifications of RE5(SixGe1−x)4. A brief history of refrigerants, to present certain motivating factors for this research effort, as well as a brief overview of the magnetocaloric effect serves to introduce this review.
AGE DIFFERENCES AND MACROECONOMIC EFFECTS ON FOOD STAMP PROGRAM PARTICIPATION

This study examines Food Stamp Program (FSP) participation patterns with an emphasis on macroeconomic effects and age differences. Entry into and exit out of the program are examined with data from the Survey of Income and Program Participation 2004 panel using probit techniques. The results indicate that young adults easily enter the FSP but quickly move out. Older people are hesitant to enter the FSP but they stay on longer compared to their younger counterparts. The estimation results confirm the common belief that economic dynamics and FSP participation are negatively related. When the unemployment rates rise, the likelihood of entry and continuation on food stamps increases. This study also documents that the macroeconomic effects on FSP transitions vary by age.
Adaptive, optical, radial basis function neural network for handwritten digit recognition

An adaptive, optical, radial basis function classifier for handwritten digit recognition is experimentally demonstrated. We describe a spatially multiplexed system that incorporates an on-line adaptation of weights and basis function widths to provide robustness to optical system imperfections and system noise. The optical system computes the Euclidean distances between a 100-dimensional input vector and 198 stored reference patterns in parallel by using dual vector–matrix multipliers and a contrast-reversing spatial light modulator. Software is used to emulate an electronic chip that performs the on-line learning of the weights and basis function widths. An experimental recognition rate of 92.7% correct out of 300 testing samples is achieved with the adaptive training, versus 31.0% correct for nonadaptive training. We compare the experimental results with a detailed computer model of the system in order to analyze the influence of various noise sources on the system performance.
Advantages of improved timing accuracy in PET cameras using LSO scintillator

PET scanners based on LSO have the potential for significantly better coincidence timing resolution than the 6 ns fwhm typically achieved with BGO. This study analyzes the performance enhancements made possible by improved timing as a function of the coincidence time resolution. If 500 ps fwhm coincidence timing resolution can be achieved in a complete PET camera, the following four benefits can be realized for wholebody FDG imaging: 1) The random event rate can be reduced by using a narrower coincidence timing window, increasing the peak NECR by /spl sim/50%. 2) Using time-of-flight in the reconstruction algorithm will reduce the noise variance by a factor of 5. 3) Emission and transmission data can be acquired simultaneously, reducing the total scan time. 4) Axial blurring can be reduced by using time-of-flight to determine the correct axial plane that each event originated from. While time-of-flight was extensively studied in the 1980's, practical factors limited its effectiveness at that time and little attention has been paid to timing in PET since then. As these potential improvements are substantial and the advent of LSO PET cameras gives us the means to obtain them without other sacrifices, efforts to improve PET timing should resume after their long dormancy.
On weight matrix and free energy models for sequence motif detection.

Abstract The problem of motif detection can be formulated as the construction of a discriminant function to separate sequences of a specific pattern from background. In computational biology, motif detection is used to predict DNA binding sites of a transcription factor (TF), mostly based on the weight matrix (WM) model or the Gibbs free energy (FE) model. However, despite the wide applications, theoretical analysis of these two models and their predictions is still lacking. We derive asymptotic error rates of prediction procedures based on these models under different data generation assumptions. This allows a theoretical comparison between the WM-based and the FE-based predictions in terms of asymptotic efficiency. Applications of the theoretical results are demonstrated with empirical studies on ChIP-seq data and protein binding microarray data. We find that, irrespective of underlying data generation mechanisms, the FE approach shows higher or comparable predictive power relative to the WM approach wh...
Metric Entropy of Nonautonomous Dynamical Systems

We introduce the notion of metric entropy for a nonautonomous dynamical system given by a sequence (Xn,µn) of probability spaces and a sequence of measurable maps fn : Xn ! Xn+1 with fnµn = µn+1. This notion generalizes the classical concept of metric entropy established by Kolmogorov and Sinai, and is related via a variational inequality to the topological entropy of nonautonomous systems as defined by Kolyada, Misiurewicz and Snoha. Moreover, it shares several properties with the classical notion of metric entropy. In particular, invariance with respect to appropriately defined isomorphisms, a power rule, and a Rokhlin-type inequality are proved.
Phylogenetic Networks Based on the Molecular Clock Hypothesis

A classical result in phylogenetic trees is that a binary phylogenetic tree adhering to the molecular clock hypothesis exists if and only if the matrix of distances between taxa is ultrametric. The ultrametric condition is very restrictive. In this paper, we study phylogenetic networks that can be constructed assuming the molecular clock hypothesis. We characterize distance matrices that admit such networks for three and four taxa. We also design two algorithms for constructing networks optimizing the least-squares fit.
Two theories of the civil burden of persuasion

Several judicial opinions and commentators have suggested that the more-probable-thannot burden of persuasion in civil cases reflects a policy of equalizing the rate or risk of factually erroneous verdicts as between plaintiffs and defendants. Concluding an exchange with Ronald Allen, this paper adheres to the view that the legal standard is better understood in terms of minimizing the expected losses due to such errors.
Cross sections for leptophobic topcolor Z decaying to top-antitop

We present numerical calculations of the production cross section of a heavy Z′ resonance in hadron–hadron collisions with subsequent decay into top–antitop pairs. In particular, we consider the leptophobic topcolor Z′ discussed under Model IV of hep-ph/9911288, which has predicted cross sections large enough to be experimentally accessible at the Fermilab Tevatron and the Large Hadron Collider at CERN. This article presents an updated calculation valid for the Tevatron and all proposed LHC collision energies. Cross sections are presented for various Z′ widths, in \(p\bar{p}\) collisions at \(\sqrt{s}=2\mbox{~TeV}\), and in pp collisions at \(\sqrt{s}=7, 8, 10 \mbox{ and } 14\mbox{~TeV}\).
Atoms as many-body systems

Abstract Some personal recollections: It is my pleasure to present this article in the volume, dedicated to the 70th birthday of Academician S.T. Belyaev. I have known him personally since 1961 and admire his profound contributions to the theory of Bose-liquids, to the theory of superconductivity of atomic nuclei and some other important scientific works. He is well known also as an organizer of science and education. For years he was, and is still the Chairman of the Synchrotron Radiation Commission of the Russian Academy of Science, a body which was established long ago to promote construction of high intensity light sources, and technological as well as scientific research using this light. One of the important directions of this study is investigation of photoabsorbtion by multielectron atoms in order to obtain information about their structure. S.T. Belyaev strongly supported this direction, which gives me the right to choose as a title of my contribution “Atoms as Many-Body Systems”.
On the Enhanced Interstellar Scattering toward B1849+005

This paper reports new Very Large Array (VLA) and Very Long Baseline Array (VLBA) observations of the extragalactic source B1849+005 (Galactic coordinates l = 3344, b = +021) at frequencies between 0.33 and 15 GHz and the reanalysis of archival VLA observations at 0.33, 1.5, and 4.9 GHz. The structure of this source is complex, confirming previous suggestions, but interstellar scattering dominates the structure of the central component at least to 15 GHz. An analysis of the phase structure functions of the interferometric visibilities shows the density fluctuations along this line of sight to be anisotropic (axial ratio = 1.3) with a frequency-independent position angle and having an inner scale of roughly a few hundred kilometers. The anisotropies occur on length scales of order 1015 cm (D/5 kpc), which within the context of certain magnetohydrodynamic turbulence theories indicates the length scale on which the kinetic and magnetic energy densities are comparable. A conservative upper limit on the velocity of the scattering material is 1800 km s-1, based on the lack of changes in the shapes of the 0.33 GHz images. In the 0.33 GHz field of view, there are a number of other sources that might also be heavily scattered, which would suggest that there are large changes in the scattering strength on lines of sight separated by a degree or less. Both B1849+005 and PSR B1849+00 are highly scattered, and they are separated by only 13'. If the lines of sight are affected by the same "clump" of scattering material, it must be at least 2.3 kpc distant. However, a detailed attempt to account for the scattering observables toward these sources (angular broadening of the extragalactic source, pulse broadening of the pulsar, and upper limits on the angular broadening of the pulsar) does not produce a self-consistent set of parameters for a clump that can reproduce all three measured scattering observables. A clump of Hα emission, possibly associated with the H II region G33.418-0.004, lies between these two lines of sight, but it seems unable to account for all of the required excess scattering.
Fitting a Two-Component Scattering Model to Polarimetric SAR Data From Forests

Two simple scattering mechanisms are fitted to polarimetric synthetic aperture radar (SAR) observations of forests. The mechanisms are canopy scatter from a reciprocal medium with azimuthal symmetry and a ground scatter term that can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a moderately rough surface, which is seen through a layer of vertically oriented scatterers. The model is shown to represent the behavior of polarimetric backscatter from a tropical forest and two temperate forest sites by applying it to data from the National Aeronautic and Space Agency/Jet Propulsion Laboratory's Airborne SAR (AIRSAR) system. Scattering contributions from the two basic scattering mechanisms are estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. This model fit approach is justified as a simplification of more complicated scattering models, which require many inputs to solve the forward scattering problem. The model is used to develop an understanding of the ground-trunk double-bounce scattering that is present in the data, which is seen to vary considerably as a function of incidence angle. Two parameters in the model fit appear to exhibit sensitivity to vegetation canopy structure, which is worth further exploration. Results from the model fit for the ground scattering term are compared with estimates from a forward model and shown to be in good agreement. The behavior of the scattering from the ground-trunk interaction is consistent with the presence of a pseudo-Brewster angle effect for the air-trunk scattering interface. If the Brewster angle is known, it is possible to directly estimate the real part of the dielectric constant of the trunks, a key variable in forward modeling of backscatter from forests. It is also shown how, with a priori knowledge of the forest height, an estimate for the attenuation coefficient of the canopy can be obtained directly from the multi-incidence-angle polarimetric observations. This attenuation coefficient is another key variable in forward models and is generally related to the canopy density.
Public opinion regarding economic and cultural globalization: evidence from a cross-national survey

ABSTRACT Empirical studies of public opinion regarding globalization have to date addressed only economic integration. By way of comparison, we know much less about public opinion regarding cultural globalization. In addition, there has been little head-to-head testing of alternative explanations for public opinions in these areas. I contrast four arguments: skills, partisanship, economic evaluations, and beliefs about the free market, consumerism, and modern life, which I test using survey information taken from 17 developed and developing countries from 2002. I find that values are a powerful and understudied explanation for variations in public opinion. Regardless of whether the question dealt with economic or cultural globalization, views about the free market, consumerism, and modern life had more explanatory power than evaluations of the economy or partisanship, and roughly the same explanatory powers as skill levels. These findings provide important insights into the sources of the globalization ba...
Awarding Price, Contract Performance, and Bids Screening: Evidence from Procurement Auctions †

Abstract This paper presents evidence on the perverse trade-off that first price auctions induce between low prices at the awarding stage and poor ex post performance when bids are not binding commitments. By exploiting the different timing with which first price auctions were introduced in Italy to procure public works, this study finds that at least half of the cost savings from lower winning prices are lost because of ex post renegotiation. Screening the lowest price bid for its responsiveness prevents performance worsening but also reduces the initial cost savings by a third and induces delays in awarding the contract. (JEL D44, H54, H57, R42)
Development of a PC-based Radiological Imaging Workstation

Low-cost image processing systems which can provide convenient access to image processing and analysis techniques hold great potential as diagnostic and research tools in medical imaging. At the University of Washington, we have developed a PC-based medium performance image processing system for use as an experimental radiological workstation. The workstation uses a standard IBM PC/AT personal computer augmented with a custom designed image processor implemented on two IBM PC/AT prototyping boards. Features of the system include up to 52 512 × 512 × 8 bit frame buffers (4 on the image processor board and up to 48 in the host computer memory) and a 512 × 512 × 4 bit graphics overlay memory, hardware zoom, pan and scroll, pseudo coloring, and a 60 Hz noninterlaced display. Many image processing and analysis functions are provided in this workstation, and all user requests are supported in an interactive fashion. For example, arithmetic and logical point operations between two 512 × 512 frame buffers require approximately 170 ms, while computationally intensive functions such as an 11 × 11 convolution or a full screen geometric transformation (warping) can be completed in less than 10 seconds. A full screen 2-D Fast Fourier Transform (FFT) and Inverse FFT (IFFT) based on the row-column method can be completed in less than 20 seconds. The developed system can easily be configured into a DIN/PACS workstation or a biological imaging system. Hardware and software details of this workstation as well as user interface functions implemented will be discussed in the paper.
Thin Teflon-like films for eliminating adhesion in released polysilicon microstructures

This paper presents a method for depositing thin Teflon-like films using a commercial plasma reactor to eliminate adhesion or stiction in released polysilicon microstructures. A Lam 384T oxide etch system is used in a remote plasma mode with commercially available trifluoromethane (CHF/sub 3/) to deposit thin hydrophobic films around and under released microstructures. Hard, uniform, Teflon-like films which penetrate into undercuts beneath structures have been produced. Thus far, surfaces beneath gears as large as 1600 micron diameter with a gap of 2.0 microns are hydrophobic after being exposed to plasma treatment. These Teflon-like coatings have been shown to reduce the coefficient of friction from 1.0 to 0.07.
Cleavage of the carbon–carbon bond in biphenylene using transition metals

Abstract Biphenylene has proven to have a rich chemistry with transition metals. In many cases, the aryl–aryl CC bond is cleaved to give a metallocycle complex, which can go on to give a variety of reaction products. Insertion reactions with small molecules lead to the formation of new polycyclic aromatic derivatives with the incorporation of functional groups. In several cases, these reactions are selective and catalytic.
Hydrodynamic forces regulate platelet activation and self-association of vWF in suspension

Shear-induced platelet aggregation (SIPA) occurs under conditions of abnormally high shear rates such as those encountered in stenosed arteries. This has been associated with a variety of pathological conditions such as cerebral ischemia and acute myocardial infarction. SIPA is initiated by the flow induced binding of a plasma protein von Willebrand factor (vWF) to the platelet receptor GpIb. We quantitatively examined the aspects of fluid flow that regulate this interaction by following the time-course of platelet activation. Platelet rich plasma (PRP) was subjected to a range of shear conditions in a cone-plate viscometer and platelet activation levels were determined by measuring Annexin V binding to the platelet surface. These experiments revealed that i) Fluid shear stress rather than shear rate controls platelet activation, and a threshold shear stress of /spl sim/60 dyn/cm/sup 2/ is necessary to induce significant activation. Under these conditions, forces of the order of 1 pN are applied on soluble vWF molecules. ii) Nonlinear and time-variant shear flow do not significantly enhance the rate of cell activation. iii) Fluid forces may regulate platelet activation levels by enhancing vWF proteolysis. In other experiments, purified vWF was subjected to shear in the viscometer and vWF morphology was assessed using light scattering spectroscopy. These studies demonstrate, for the first time, the ability of hydrodynamic forces to induce vWF self-association in suspension. This result raises the possibility that vWF self-association may be an additional feature involved in controlling thrombus formation rates in circulation.
Resonator surface contamination-a cause of frequency fluctuations?

The mass loading effects of adsorbing and desorbing contaminant molecules on the magnitude and characteristics of frequency fluctuations in a thickness-shear resonator are studied. The study is motivated by the observation that the frequency of a thickness-shear resonator is determined predominantly by such mechanical parameters as the thickness of the resonator, elastic stiffnesses, mass loading of the electrodes, and energy trapping. An equation was derived relating the spectral density of frequency fluctuations to: (1) rates of adsorption and desorption of one species of contaminant molecules; (2) mass per unit area of a monolayer of molecules: (3) frequency constant; (4) thickness of resonator; and (5) number of molecular sites on one resonator surface. The induced phase noises were found to be significant in very-high-frequency resonators and are not simple functions of the percentage of area contaminated. The spectral density of frequency fluctuations was inversely proportional to the fourth power of the thickness if other parameters were held constant. >
De novo discovery of mutated driver pathways in cancer

Next-generation DNA sequencing technologies are enabling genome-wide measurements of somatic mutations in large numbers of cancer patients. A major challenge in the interpretation of these data is to distinguish functional “driver mutations” important for cancer development from random “passenger mutations.” A common approach for identifying driver mutations is to find genes that are mutated at significant frequency in a large cohort of cancer genomes. This approach is confounded by the observation that driver mutations target multiple cellular signaling and regulatory pathways. Thus, each cancer patient may exhibit a different combination of mutations that are sufficient to perturb these pathways. This mutational heterogeneity presents a problem for predicting driver mutations solely from their frequency of occurrence. We introduce two combinatorial properties, coverage and exclusivity, that distinguish driver pathways, or groups of genes containing driver mutations, from groups of genes with passenger mutations. We derive two algorithms, called Dendrix, to find driver pathways de novo from somatic mutation data. We apply Dendrix to analyze somatic mutation data from 623 genes in 188 lung adenocarcinoma patients, 601 genes in 84 glioblastoma patients, and 238 known mutations in 1000 patients with various cancers. In all data sets, we find groups of genes that are mutated in large subsets of patients and whose mutations are approximately exclusive. Our Dendrix algorithms scale to whole-genome analysis of thousands of patients and thus will prove useful for larger data sets to come from The Cancer Genome Atlas (TCGA) and other large-scale cancer genome sequencing projects.
Analysis of Electromagnetic Propulsion of Nonionized Dipole Gases

A means by which the thrust-producing electromagnetic acceleration of a nonionized gas could be achieved was suggested recently. This acceleration is accomplished through the interaction of an alternating polarization in the exhaust medium with a synchronized alternating magnetic field. Two derivations of this force are presented along with quantitative experimental evidence of its existence. The thrust produced by such an interaction is proportional to the product of the polarization amplitude, the magnetic field strength, and the frequency of the field oscillation. Estimates of the thrust obtainable with naturally occurring atoms and molecules proved too small to provide for a variable thruster concept, therefore, artificial means of increasing the dipole moment were examined. Electronically excited or Rydberg atoms and molecules provide a proven means of obtaining increased polarization amplitudes; however, the decreased ionization potential negated their use as potential propellants. Comparison of alternating polarization thrusters with other electric propulsion concepts indicated that this method is not a viable advanced propulsion scheme at this time.
Separate and Unequal: Post-Tsunami Aid Distribution in Southern India

Objective. Disasters are a regular occurrence throughout the world. Whether all eligible victims of a catastrophe receive similar amounts of aid from governments and donors following a crisis remains an open question.Methods. I use data on 62 similarly damaged inland fishing villages in five districts of southeastern India following the 2004 Indian Ocean tsunami to measure the causal influence of caste, location, wealth, and bridging social capital on the receipt of aid. Using two-limit tobit and negative binomial models, I investigate the factors that influence the time spent in refugee camps, receipt of an initial aid packet, and receipt of 4,000 rupees.Results. Caste, family status, and wealth proved to be powerful predictors of beneficiaries and nonbeneficiaries during the aid process.Conclusion. While many scholars and practitioners envision aid distribution as primarily a technocratic process, this research shows that discrimination and financial resources strongly affect the flow of disaster aid.
The cyclical behavior of prices

Abstract The procyclical behavior of prices has been a staple of business cycle lore since the work of the early NBER business cycle researchers. This paper reexamines that empirical fact. The aggregate data do not support procyclical price movements as a stable feature of the business cycle. The only episode where it is a robust feature of the data is the period between the two world wars, particularly the period of the Great Depression.
Presolar grains from meteorites: Remnants from the early times of the solar system

Abstract This review provides an introduction to presolar grains – preserved stardust from the interstellar molecular cloud from which our solar system formed – found in primitive meteorites. We describe the search for the presolar components, the currently known presolar mineral populations, and the chemical and isotopic characteristics of the grains and dust-forming stars to identify the grains’ most probable stellar sources.
Three-point correlations in weak lensing surveys: Model predictions and applications

We use the halo model of clustering to compute two- and three-point correlation functions for weak lensing, and apply them in a new statistical technique to measure properties of massive haloes. We present analytical results on the eight shear three-point correlation functions constructed using a combination of the two shear components at each vertex of a triangle. We compare the amplitude and configuration dependence of the functions with ray-tracing simulations and find excellent agreement for different scales and models. These results are promising, since shear statistics are easier to measure than the convergence. In addition, the symmetry properties of the shear three-point functions provide a new and precise way of disentangling the lensing E mode from the B mode due to possible systematic errors. We develop an approach based on correlation functions to measure the properties of galaxy-group and cluster haloes from lensing surveys. Shear correlations on small scales arise from the lensing matter within haloes of mass M ? 10 1 3 M O .. Thus, the measurement of two- and three-point correlations can be used to extract information on halo density profiles, primarily the inner slope and halo concentration. We demonstrate the feasibility of such an analysis for forthcoming surveys. We include covariances in the correlation functions due to sample variance and intrinsic ellipticity noise to show that 10 per cent accuracy on profile parameters is achievable with surveys such as the CFHT Legacy survey, and significantly better with future surveys. Our statistical approach is complementary to the standard approach of identifying individual objects in survey data and measuring their properties. It can be extended to perform a combined analysis of the large-scale, perturbative regime down to small, subarcminute scales, to obtain consistent measurements of cosmological parameters and halo properties.
The Distance to the Massive Galactic Cluster Westerlund 2 from a Spectroscopic and HST Photometric Study

We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters
Carbonyl ylide formation in the reaction of methylene with acetone

Abstract Photolysis of diazomethane in acetone yields a carbonyl ylide as an intermediate.
Free and mixed convection in horizontal porous layers with multiple heat sources

Free and mixed convection has been studied numerically for horizontal porous layers heated from below by multiple, isothermal, discrete sources. Steady-state results have been obtained for natural convection with up to eight sources and for mixed convection with up to four sources. Rayleigh numbers are varied from 10 to 500, and Peclet numbers from 0.1 to 100. For natural convection, the vertical sidewalls for the two-dimensional domain considered have little effect on Nusselt numbers if the distance between the outermost source and wall is greater than three times the length of the heat source. As the number of heat sources increases, heat-transfer coefficients for the second outermost sources are a minimum. In mixed convection, overall Nusselt numbers increase with both the number of sources and Rayleigh number. If the individual heat source is considered, heat-transfer coefficients are determined only by its location. For Rayleigh numbers greater than 50, there exists a critical Peclet number for which the overall Nusselt number is a minimum. Unstable, oscillatory flow and temperature fields are observed for Rayleigh numbers greater than 50. Nomenclature c = specific heat of fluid at constant pressure, J/kg-K D - length of the heat sources, m DN = nth discrete heat source d = distance between two discrete heat sources, m g = acceleration of gravity, m/s2 H = height of the porous layer, m h = local heat-transfer coefficient, W/m2-K h = average heat-transfer coefficient for the bottom sur
Costly Buyer Search in a Differentiated Products Model: An Experimental Study

This study examines whether the content of buyer information and the timing of its dissemination affects seller market power. We construct laboratory markets with differentiated goods and costly buyer search in which sellers simultaneously post prices. The experiment varies the information on price or product characteristics that buyers learn under different timing assumptions (pre- and postsearch), generating four information treatments. Theory predicts that price information lowers the equilibrium price, but information about product characteristics increases the equilibrium price. That is, contrary to intuition, the presence of informed buyers may impart a negative externality on other uninformed buyers. Data support the model's negative externality result when sellers face a large number of robot buyers that are programmed to search optimally. Observed prices conform to the model's comparative statics and are broadly consistent with predicted levels. With human buyers, however, excessive search instigates increased price competition, and sellers post prices that are significantly lower than predicted.
A novel synthesis of 7-aryl-8-fluoro-pyrrolo[1,2-a]pyrimid-4-ones as potent, stable GnRH receptor antagonists.

A new class of small molecule GnRH antagonists, the 7-aryl-8-fluoro-pyrrolo[1,2-a]pyrimid-4-ones, was designed and a novel synthesis for these compounds was developed. The synthesis utilizes a base-catalyzed intramolecular cyclization of fluoromethyl pyrimidone 5 to generate the bicyclic core. Amongst the compounds synthesized, we discovered some highly potent GnRH receptor antagonists (e.g., 12, K(i)=9 nM), which showed enhanced stability towards acidic physiological conditions compared to the des-fluoro analogues.