cssi/SciSciGPT-SciSciNet huggingface dataset:
THE IMPACT OF NON-EQUIPARTITION ON COSMOLOGICAL PARAMETER ESTIMATION FROM SUNYAEV-ZEL'DOVICH SURVEYS

The collisionless accretion shock at the outer boundary of a galaxy cluster should primarily heat the ions instead of electrons since they carry most of the kinetic energy of the infalling gas. Near the accretion shock, the density of the intracluster medium is very low and the Coulomb collisional timescale is longer than the accretion timescale. Electrons and ions may not achieve equipartition in these regions. Numerical simulations have shown that the Sunyaev-Zel'dovich observables (e.g., the integrated Comptonization parameter Y) for relaxed clusters can be biased by a few percent. The Y versus mass relation can be biased if non-equipartition effects are not properly taken into account. Using a set of hydrodynamical simulations we have developed, we have calculated three potential systematic biases in the Y versus mass relations introduced by non-equipartition effects during the cross-calibration or self-calibration when using the galaxy cluster abundance technique to constraint cosmological parameters. We then use a semi-analytic technique to estimate the non-equipartition effects on the distribution functions of Y (Y functions) determined from the extended Press-Schechter theory. Depending on the calibration method, we find that non-equipartition effects can induce systematic biases on the Y functions, and the values of the cosmological parameters {Omega}{submore » 8}, {sigma}{sub 8}, and the dark energy equation of state parameter w can be biased by a few percent. In particular, non-equipartition effects can introduce an apparent evolution in w of a few percent in all of the systematic cases we considered. Techniques are suggested to take into account the non-equipartition effect empirically when using the cluster abundance technique to study precision cosmology. We conclude that systematic uncertainties in the Y versus mass relation of even a few percent can introduce a comparable level of biases in cosmological parameter measurements.« less
Modeling credit value adjustment with downgrade-triggered termination clause using a ruin theoretic approach

Abstract Downgrade-triggered termination clause is a recent innovation in credit risk management to control counterparty credit risk. It allows one party of an over-the-counter derivative to close off its position at marked-to-market price when the other party’s credit rating downgrades to an agreed alarming level. Although the default risk is significantly reduced, the non-defaulting party may still suffer losses in case that the other party defaults without triggering the termination clause prior to default. At the heart of the valuation of credit risk adjustment(CVA) is the computation of the probability of default. We employ techniques from ruin theory and complex analysis to provide solutions for probabilities of default, which in turn lead to very efficient and accurate algorithms for computing CVA. The underlying risk model in question is an extension of the commercially available KMV–Merton model and hence can be easily implemented. We provide a hypothetical example of CVA computation for an interest-rate swap with downgrade-triggered termination clause. The paper also contributes to ruin theory by presenting some new results on finite-time ruin probabilities in a jump-diffusion risk model.
Costly price discrimination

Abstract Standard theory neglects that enacting price discrimination is costly to firms. When this costliness is accounted for, perfect price discrimination is often socially inefficient. For pure monopolists it is sometimes socially inefficient. For monopolistic competitors it is always socially inefficient.
A way-halting cache for low-energy high-performance systems

Caches contribute to much of a microprocessor system's power and energy consumption. Numerous new cache architectures, such as phased, pseudo-set-associative, way predicting, reactive-associative, way-shutdown, way-concatenating, and highly-associative, are intended to reduce power and/or energy, but they all impose some performance overhead. We have developed a new cache architecture, called a way-halting cache, that reduces energy further than previously mentioned architectures, while imposing no performance overhead. Our way-halting cache is a four-way set-associative cache that stores the four lowest-order bits of all ways' tags into a fully associative memory, which we call the halt tag array. The lookup in the halt tag array is done in parallel with, and is no slower than, the set-index decoding. The halt tag array predetermines which tags cannot match due to their low-order 4 bits mismatching. Further accesses to ways with known mismatching tags are then halted, thus saving power. Our halt tag array has an additional feature of using static logic only, rather than dynamic logic used in highly associative caches, making our cache simpler to design with existing tools. We provide data from experiments on 29 benchmarks drawn from Powerstone, Mediabench, and Spec 2000, based on our layouts in 0.18 micron CMOS technology. On average, we obtained 55p savings of memory-access related energy over a conventional four-way set-associative cache. We show that savings are greater than previous methods, and nearly twice that of highly associative caches, while imposing no performance overhead and only 2p cache area overhead.
How do quotes and prices evolve around isolated informed trades

This article investigates the order imbalance and price behavior of trades and quotes around isolated informed trades intraday. Different patterns of order flows around informed trades are documented because of the originating stock exchange, the type of informed trader, the size of the order, and the type of the firm whose shares are traded. The informed trader acts contrarian to prior trades. Informed purchases follow price declines, and sales are after price increases. The informed trade is recognized by the market maker. The purchase is executed at a significantly higher price, while the sale is executed at a significantly lower price. Trades contain more information if the insiders are at small firms. Larger orders and orders by top executives also contain more information. The order imbalance changes around an informed trade. Orders are seller-initiated prior to the purchase and become buyer-initiated after the trade. On the other hand, the order imbalance changes from buyer- to seller-initiated right around insider sales. Reversals in order imbalance are more pronounced for informed trades in small firms, for larger trades, and by top executives. There are important policy implications of the results. The recognition of informed trades by market makers justifies more scrutiny by the Securities and Exchange Commission in order to ensure fair trading.
Developmental origins of diabetes: The role of oxidative stress

The 'thrifty phenotype' hypothesis proposes that the fetus adapts to an adverse intrauterine milieu by optimizing the use of a reduced nutrient supply to ensure survival, but by favoring the development of certain organs over that of others, this leads to persistent alterations in the growth and function of developing tissues. This concept has been somewhat controversial, however recent epidemiological, clinical, and animal studies provide support for the developmental origins of disease hypothesis. Underlying mechanisms include reprogramming of the hypothalamic-pituitary-adrenal axis, islet development, and insulin signaling pathways. Emerging data suggests that oxidative stress and mitochondrial dysfunction may also play a critical role in the pathogenesis of type 2 diabetes in individuals who were growth retarded at birth.
Adam Smith on Instincts, Affection, and Informal Learning: Proximate Mechanisms in Multilevel Selection

Abstract Why do people give away knowledge in tutoring other people's children or when mentoring junior employees? Neoclassical economists explain informal learning as rational behavior that arises out of enlightened self-interest. They can also justify it as acts that satisfy the agent's preferences for the utility of others. By contrast, this paper shows that Smith's moral sentiments model anticipates a biological approach that explains additional and deeper motives for such exchanges. Instincts and emotions serve consequentialist ends because the ultimate causes of behavior are grounded in adaptations useful for survival and procreation. But man is largely innocent of this knowledge. The proximate causes of behavior—that is, the adaptive mechanisms actually at work in human society—are psychologically obscure—not left to the conscious mind. Social and moral capital develop through instincts and affection, and mentoring and collaboration are examples of social exchanges that arise from them.
Bufferless Routing in Optical Gaussian Macrochip Interconnect

The ever increasing intra-chip and inter-chip traffic load in computing systems has been pushing traditional electronic interconnects to their limit in communication bandwidth, latency, and energy consumption. In order to achieve the high bandwidth and low latency required by intra-chip and inter-chip communications and mitigate the high interconnect power dissipation, optical interconnects have been considered as a promising candidate for intra-chip and inter-chip interconnections in next generation computing systems. In addition, packet switching is an efficient switching paradigm to fully utilize the communication bandwidth. However, due to lack of random access optical memory, it is challenging to implement all-optical packet switching in optical interconnects. In this paper, we exploit bufferless routing, a special type of packet-switching, to overcome the problem of lack of random access optical buffer. More specifically, we study bufferless routing in a novel optical multichip system, called Gaussian macrochip, where embedded chips are interconnected by an optical Gaussian network. By taking advantage of the underlying Hamiltonian cycles in the Gaussian network, we design a bufferless routing algorithm for the Gaussian macrochip, which routes packets along the shortest path in the absence of deflection, and guarantees that deflected packets reach their destinations within ${{N}}$ hops. Our extensive simulation results demonstrate that by adopting the proposed routing algorithm, Gaussian macrochip can support much higher inter-chip communication bandwidth, has much shorter average packet delay, and is more power efficient than the previously proposed architectures for optical multichip systems.
Distributed State Space Generation of Discrete-State Stochastic Models

High-level formalisms such as stochastic Petri nets can be used to model complex systems. Analysis of logical and numerical properties of these models often requires the generation and storage of the entire underlying state space. This imposes practical limitations on the types of systems that can be modeled. Because of the vast amount of memory consumed, we investigate distributed algorithms for the generation of state space graphs. The distributed construction allows us to take advantage of the combined memory readily available on a network of workstations. The key technical problem is to find effective methods for on-the-fly partitioning, so that the state space is evenly distributed among processors. In this article we report on the implementation of a distributed state space generator that may be linked to a number of existing system modeling tools. We discuss partitioning strategies in the context of Petri net models, and report on performance observed on a network of workstations, as well as on a distributed memory multicomputer.
Qubit complexity of continuous problems

The number of qubits used by a quantum algorithm will be a crucial computational resource for the foreseeable future. We show how to obtain the classical query complexity for continuous problems. We then establish a simple formula for a lower bound on the qubit complexity in terms of the classical query complexity.
Palladium-Catalyzed Synthesis of N-Aryl Carbamates

An efficient synthesis of aryl carbamates was achieved by introducing alcohols into the reaction of palladium-catalyzed cross-coupling of ArX (X = Cl, OTf) with sodium cyanate. The use of aryl triflates as electrophilic components in this transformation allowed for an expanded substrate scope for direct synthesis of aryl isocyanates. This methodology provides direct access to major carbamate protecting groups, S-thiocarbamates, and diisocyanate precursors to polyurethane materials.
A compact symmetric symplectic non-kaehler manifold

In this paper I construct, using off the shelf components, a compact symplectic manifold with a non-trivial Hamiltonian circle action that admits no Kaehler structure. The non-triviality of the action is guaranteed by the existence of an isolated fixed point. The motivation for this work comes from the program of classification of Hamiltonian group actions. The Audin-Ahara-Hattori-Karshon classification of Hamiltonian circle actions on compact symplectic 4-manifolds showed that all of such manifolds are Kaehler. Delzant's classification of $2n$-dimensional symplectic manifolds with Hamiltonian action of $n$-dimensional tori showed that all such manifolds are projective toric varieties, hence Kaehler. An example in this paper show that not all compact symplectic manifolds that admit Hamiltonian torus actions are Kaehler. Similar technique allows us to construct a compact symplectic manifold with a Hamiltonian circle action that admits no invariant complex structures, no invariant polarizations, etc.
Does the 2D Higgs-Yukawa model have a symmetric phase at small Yukawa coupling region?

Abstract We show that at arbitrary values of the scalar self coupling and the small Yukawa coupling y the 2D Higgs-Yukawa model with Z(2) symmetry remains in the broken phase and the model is asymptotically free: y → 0 as the cut-off Λ → ∞. This is in agreement with a recent conjecture based on numerical simulation results.
Electromagnetic energy transfer and switching in nanoparticle chain arrays below the diffraction limit

Electromagnetic energy transfer in plasmon wires consisting of chains of closely spaced metal nanoparticles can occur below the diffraction limit by means of coupled plasmon modes. Coherent propagation with group velocities that exceed 0.1 c is possible in straight wires and around sharp corners (bending radius much less than wavelength of visible light). Energy transmission through chain networks is possible at high efficiencies and is a strong function of the frequency and polarization direction of the plasmon mode. Although these structures exhibit transmission losses due to heating of about 3 dB/500 nm, they have optical functionality that cannot be obtained in other ways at a length scale \ensuremath{\ll}1 \ensuremath{\mu}m.
Quantum random walks with multiphoton interference and high-order correlation functions

We show a simulation of quantum random walks (QRWs) with multiple photons using a staggered array of 50/50 beam splitters with a bank of detectors at any desired level. We discuss the multiphoton interference effects that are inherent to this setup, and introduce one, two, and threefold coincidence detection schemes. Feynman diagrams are used to intuitively explain the unique multiphoton interference effects of these QRWs.
Optical System With Fiber Optical Elements

Many reflecting and refracting elements are required in the construction of a conventional optical system with a low f/number. Such a system poses problems in alignment and mechanical stabilty when operating in severe environments over a wide temerature range. A fiber bundle designed in the form of a cone with larger entrance diameter than the exit diameter transmits and reduces the uimage size. A simple lens of longer focal length and larger effective aperture can be used to produce an imageat the entrance of the cone. Since there is a gain in flux per unit area, this system intesifies as well as trasmits an image. It also enables the use of a detector of smaller size to achieve a higher signal-to-noise ratio. An effective optical systen for doing this is described and demonstrated.
TS/Scheme: distributed data structures in Lisp

We describe a parallel object-oriented dialect of Scheme called TS/SCHEME that provides a simple and expressive interface for building asynchronous parallel programs. The main component in TS/SCHEME's coordination framework is an abstraction that serves the role of a distributed data structure. Distributed data structures are an extension of conventional data structures insofar as many tasks may simultaneously access and update their contents according to a well-defined serialization protocol. The semantics of these structures also specifies that consumers which attempt to access an as-of-yet undefined element are to block until a producer provides a value. TS/SCHEME permits the construction of two basic kinds of distributed data structures, those accessed by content, and those accessed by name. These structures can be further specialized and composed to yield a number of other synchronization abstractions. Our intention is to provide an efficient medium for expressing concurrency and synchronization that is amenable to modular programming, and which can be used to succinctly and efficiently describe a variety of diverse concurrency paradigms useful for parallel symbolic computing.
Neutrinos from binary pulsars

It is shown that binary systems containing moderately young pulsars may emit high-energy neutrinos (between 1 and 100 TeV) at detectable levels. The pulsars are assumed to have total luminosities of the order of 10 to the 38th erg/sec. The neutrinos are produced by high energy particles (e.g. protons) from the pulsar striking the companion. Cyg X3 may be detectable in high-energy neutrinos if it emits greater than about 10 to the 35th erg/sec in high-energy protons. There may be a whole class of objects like Cyg X3, but obscured by thick accretion clouds.
Iterated homotopy fixed points for the Lubin–Tate spectrum

Abstract When G is a profinite group and H and K are closed subgroups, with H normal in K, it is not known, in general, how to form the iterated homotopy fixed point spectrum ( Z h H ) h K / H , where Z is a continuous G-spectrum and all group actions are to be continuous. However, we show that, if G = G n , the extended Morava stabilizer group, and Z = L ˆ ( E n ∧ X ) , where L ˆ is Bousfield localization with respect to Morava K-theory, E n is the Lubin–Tate spectrum, and X is any spectrum with trivial G n -action, then the iterated homotopy fixed point spectrum can always be constructed. Also, we show that ( E n h H ) h K / H is just E n h K , extending a result of Devinatz and Hopkins.
Pathwidth, trees, and random embeddings

We prove that, for every integer k?1, every shortest-path metric on a graph of pathwidth k embeds into a distribution over random trees with distortion at most c=c(k), independent of the graph size. A well-known conjecture of Gupta, Newman, Rabinovich, and Sinclair [12] states that for every minor-closed family of graphs F, there is a constant c(F) such that the multi-commodity max-flow/min-cut gap for every flow instance on a graph from F is at most c(F). The preceding embedding theorem is used to prove this conjecture whenever the family F does not contain all trees.
Myocardial drug distribution generated from local epicardial application: Potential impact of cardiac capillary perfusion in a swine model using epinephrine

Prior studies in small mammals have shown that local epicardial application of inotropic compounds drives myocardial contractility without systemic side effects. Myocardial capillary blood flow, however, may be more significant in larger species than in small animals. We hypothesized that bulk perfusion in capillary beds of the large mammalian heart not only enhances drug distribution after local release, but also clears more drug from the tissue target than in small animals. Epicardial (EC) drug releasing systems were used to apply epinephrine to the anterior surface of the left heart of swine in either point-sourced or distributed configurations. Following local application or intravenous (IV) infusion at the same dose rates, hemodynamic responses, epinephrine levels in the coronary sinus and systemic circulation, and drug deposition across the ventricular wall, around the circumference and down the axis, were measured. EC delivery via point-source release generated transmural epinephrine gradients directly beneath the site of application extending into the middle third of the myocardial thickness. Gradients in drug deposition were also observed down the length of the heart and around the circumference toward the lateral wall, but not the interventricular septum. These gradients extended further than might be predicted from simple diffusion. The circumferential distribution following local epinephrine delivery from a distributed source to the entire anterior wall drove drug toward the inferior wall, further than with point-source release, but again, not to the septum. This augmented drug distribution away from the release source, down the axis of the left ventricle, and selectively toward the left heart follows the direction of capillary perfusion away from the anterior descending and circumflex arteries, suggesting a role for the coronary circulation in determining local drug deposition and clearance. The dominant role of the coronary vasculature is further suggested by the elevated drug levels in the coronary sinus effluent. Indeed, plasma levels, hemodynamic responses, and myocardial deposition remote from the point of release were similar following local EC or IV delivery. Therefore, the coronary vasculature shapes the pharmacokinetics of local myocardial delivery of small catecholamine drugs in large animal models. Optimal design of epicardial drug delivery systems must consider the underlying bulk capillary perfusion currents within the tissue to deliver drug to tissue targets and may favor therapeutic molecules with better potential retention in myocardial tissue.
Mirror symmetry in 2+1 and 1+1 dimensions

We study the Coulomb-Higgs duality of = 2 supersymmetric abelian Chern-Simons theories in 2+1 dimensions, by compactifying dual pairs on a circle of radius R and comparing the resulting = (2,2) theories in 1+1 dimensions. Below the compactification scale, the theory on the Higgs branch reduces to the non-linear sigma model on a toric manifold. In the dual theory on the Coulomb branch, the Kaluza-Klein modes generate an infinite tower of contributions to the superpotential. After resummation, in the limit R?0 the superpotential becomes that of the Landau-Ginzburg model which is the two-dimensional mirror of the toric sigma model. We further examine the conjecture of all-scale three-dimensional mirror symmetry and observe that it is consistent with mirror symmetry in 1+1 dimensions.
Stability of volume comparison for complex convex bodies

We prove the stability of the affirmative part of the solution to the complex Busemann–Petty problem. Namely, if K and L are origin-symmetric convex bodies in \({{\mathbb C}^n}\), n = 2 or n = 3, \({\varepsilon >0 }\) and \({{\rm Vol}_{2n-2}(K\cap H) \le {\rm Vol}_{2n-2}(L \cap H) + \varepsilon}\) for any complex hyperplane H in \({{\mathbb C}^n}\) , then \({({\rm Vol}_{2n}(K))^{\frac{n-1}n}\le({\rm Vol}_{2n}(L))^{\frac{n-1}n} + \varepsilon}\) , where Vol2n is the volume in \({{\mathbb C}^n}\) , which is identified with \({{\mathbb R}^{2n}}\) in the natural way.
INDUCED RAMAN SCATTERING IN PULSAR MAGNETOSPHERES

It is shown that induced Raman scattering of electromagnetic waves in the strongly magnetized electron–positron plasma of pulsar magnetospheres may be important for wave propagation and as an effective saturation mechanism for electromagnetic instabilities. The frequencies at which strong Raman scattering occurs in the outer parts of a magnetosphere fall into the observed radio band. The typical threshold intensities for the strong Raman scattering are of the order of the observed intensities, implying that pulsar magnetospheres may be optically thick to Raman scattering of electromagnetic waves.
Treatment of cyclic vomiting syndrome.

Cyclic vomiting syndrome (CVS) is a relatively rare but highly incapacitating disorder. It is seen both in children and adults, although classically it has been perceived as a pediatric gastrointestinal disorder. Recent studies have demonstrated that this disorder indeed can be seen in adults and is highly disabling. Although classically associated with migraine headaches in the pediatric form, this relationship is less well established in adults. This has major implications for management in that traditionally, one of the major avenues for treatment of pediatric CVS has been antimigraine drugs. An additional factor that obscures a review of CVS treatment is the fact that because of its relative rarity, no randomized controlled trials (RCTs) have been performed. In the absence of RCTs, it is difficult to make definitive recommendations regarding treatment. The literature to date consists of case reports and open-ended case series. However, despite these limitations, it is the goal of this article to present in a comprehensive manner the options available for the treatment of CVS. Recognizing the limitations in the literature, it is clear that a number of treatment strategies that can often prove effective for the treatment of these complicated and often-challenging patients are available. Treatment is divided between acute intervention, when a patient is actively and severely vomiting, and prophylactic treatment for patients in their “interictal” phase, the goal of which is reducing frequency and intensity of subsequent episodes. Finally, we are beginning to identify possible mechanisms of the cause of CVS. Once these are better understood, this will provide the basis for further improvement in treatment.
A Cutoff in the X-Ray Fluctuation Power Density Spectrum of the Seyfert 1 Galaxy NGC 3516

During 1997 March-July, RXTE observed the bright, strongly variable Seyfert 1 galaxy NGC 3516 once every approx. 12.8 hr for 4.5 months and nearly continuously (with interruptions due to SAA passage but not Earth occultation) for a 4.2 day period in the middle. These were followed by ongoing monitoring once every approx. 4.3 days. These data are used to construct the first well-determined X-ray fluctuation power density spectrum (PDS) of an active galaxy to span more than 4 decades of usable temporal frequency. The PDS shows no signs of any strict or quasi-periodicity, but does show a progressive flattening of the power-low slope from -1.74 at short time scales to -0.73 at longer time scales. This is the clearest observation to date of the long-predicted cutoff in the PDS. The characteristic variability time scale corresponding to this cutoff temporal frequency is approx. 1 month. Although it is unclear how this time scale may be interpreted in terms of a physical size or process, there are several promising candidate models. The PDS appears similar to those seen for Galactic black hole candidates such as Cyg X-1, suggesting that these two classes of objects with very different luminosities and putative black hole masses (differing by more than a factor of 10(exp 5)) may have similar X-ray generation processes and structures.
Robust edge detection

Abstract In this paper, we have described a new robust edge detection algorithm which performs equally well under a wide variety of noisy situations and a broad range of edges. The algorithm is executed in three phases. In phase 1, the step and linear edges are detected from the noise corrupted image. The corrupting noise is assumed to be additive with two components: (1) A symmetric, continuous, exponential type noise component such as Gaussian, Laplacian or uniform noise and (2) an impulsive noise component. While well-known edge operators use smoothing before edge detection, phase 1 of the new operator uses a statistical classification technique to detect the step and linear edges. The statistical classification technique is based on two salient characteristics of natural edges: (1) Near and around the step and linear edges, the pixels, when classified into two nearly equal groups, display markedly different average intensity values, (2) the members of each group show strong spatial correlation. The advantage with the new technique is that the weak edges are not blurred, and the presence of impulse noise is easily accounted for. In phase 2, all the thin-line edges, i.e. edges which are lines less than two pixels wide, are detected by a supplementary technique since these edges cannot be detected simultaneously with the other step and linear edges. In order to do so, the problem of thin-line edge detection is posed as a series of outlier detection problem. The solution is provided in the framework of Dixon's r -test. In phase 3, the spurious edge elements are suppressed, and the isolated missing edge elements are interpolated using a number of hypothesized edge-segments. Finally, some experimental results are provided to illustrate the success of the algorithm.
Associative retrieval trie hash-coding*

In this paper, data base designs for retrieval from a file of k -letter records when queries may be only partially specified are examined. A family of data base designs referred to as the H αβκ PMF-trie designs which yield a data structure with good worst case and average case performances and require an amount of storage space essentially equal to that required of the records themselves is introduced. The analysis of the designs including bounds on the worst case performance and an explicit expression for the average performance is presented. Previously known families of PMF-trie designs are seen to be special cases within the H αβκ family.
A facile route to α-imino acetals and the corresponding monoacetal derivatives of α-diketones with complete regiochemical control.

Abstract Treatment of representative orthoesters ( 2 ) with pyruvonitrile ( 3 ) afforded the corresponding α, α-diethoxynitriles ( 4 ) in 65–80% yields. Depending upon the conditions used to protonate the initial adduct, subsequent addition of an organolithium ( 5 ) or Grignard reagent to the latter ( 4 ) led to the obtention of either α-imino acetals ( 6 ) or the corresponding monoprotected α-diketones ( 7 ) in >90% yield.
Osmotic opening of the blood-brain barrier.

SUMMARY Cerebrovascular permeability of nonelectrolytes and organic electrolytes is directly proportional to the octanol/water parti­ tion coefficient of these substances, as was determined by a new method of compartmental analysis which is suffici~§tly sen~itive to examine permeability coefficients a~4low as !2 em sec (i.e., sucrose permeability) or as high as 10 em sec (i.e., antipyrine and caffeine permeabilities). In the latter case, cerebral blood flow must be taken into account to correct for extraction of tracer during its passage through the brain. The compartmental analysis method was employed in conscious rats, when radiotracer was injec­ ted i.v. as a bolus and tracer entry into the brain was analyzed in terms of a permeability coefficient and cerebral distribution vol­ ume. The proportionality between cerebrovascular permeability and octanol/water partition coefficient suggests that substances enter the brain by dissolving in the lipoid membranes of the continuous cerebrovascular endothelium (blood-brain barrier) and not by passing through aqueous pores within the endothelium. In order to overcome permeability limitations to intravascular water-soluble compounds, furthermore, it is possible to open the blood-brain barrier by in­ fusing, into the carotid artery, a hypertonic solution of a water­ soluble solute such as arabinose. Physiological and ultrastructural evidence indicates that osmotic opening of the blood-brain barrier is mediated by widening of tight junctions between cerebrovascular endothelial cells. In the rat, osmotic barrier opening occurs a­ bruptly at a threshold arabin~~e concentration of 1.6 molal, and at an infusion time of 20 sec. C-sucrose permeability is increased 10-20 fold by osmotic treatment, but the increase disappears
The chemistry of C-aromatic taxane derivatives atropisomer control of reaction stereochemistry

Abstract The atropselective synthesis of tricyclo [9.3.1.03,8] pentadecane ring systems is reported. Substrate conformation is utilized for the stereoselective elaboration of functional groups. The conformational dynamics of intermediates are also reported.
Critical Race Realism: Re-Claiming the Antidiscrimination Principle through the Doctrine of Good Faith in Contract Law

This Article comprises the last leg of a larger project I have undertaken on the implied obligation of good faith in contract law. I have argued elsewhere that, as a descriptive matter, the doctrine of good faith and fair dealing in contract law, despite some theoretical controversy in the established scholarship on the doctrine, functions in contemporary contract law not as an implied contract term—as it was originally conceived—but as a rhetorical proxy for judicial analyses of material breach and constructive conditions relating to underlying breach of contract claims. While such applications of good faith have been of great functional value to courts, lawyers, and students of contract law, I have argued that these developments have caused good faith jurisprudence to languish in an impoverished state and to further detach from the doctrine’s equitable roots in implicit contractual obligation. As such, I also have argued from a critical race perspective that, as a normative matter and due to the inadequacies of civil rights remedies, good faith should be used to prohibit discriminatory conduct based on race, gender, sexual identity, age, and/or other categories of identity in the contractual context.
K-homology and index theory on contact manifolds

This paper applies K-homology to solve the index problem for a class of hypoelliptic (but not elliptic) operators on contact manifolds. K-homology is the dual theory to K-theory. We explicitly calculate the K-cycle (i.e., the element in geometric K-homology) determined by any hypoelliptic Fredholm operator in the Heisenberg calculus. The index theorem of this paper precisely indicates how the analytic versus geometric K-homology setting provides an effective framework for extending formulas of Atiyah–Singer type to non-elliptic Fredholm operators.
Ordering events in Minkowski space

Let p"1,...,p"k be k points (events) in (n+1)-dimensional Minkowski space R^1^,^n. Using the theory of hyperplane arrangements and chromatic polynomials, we obtain information on the number of different orders in which the events can occur in different reference frames if the events are sufficiently generic. We consider the question of what sets of orderings of the points are possible and show a connection with sphere orders and the allowable sequences of Goodman and Pollack.
An Expert System for Wind Shear Avoidance

A study of intelligent guidance and control concepts for protecting against the adverse effects of wind shear during aircraft takeoffs and landings is being conducted, with current emphasis on developing an expert system for wind shear avoidance. Principal objectives are to develop methods for assessing the likelihood of wind shear encounter (based on real-time information in the cockpit), for deciding what flight path to pursue (e.g., takeoff abort, landing go-around, or normal climbout or glide slope), and for using the aircraft's full potential for combating wind shear. This study requires the definition of both deterministic and statistical techniques for fusing internal and external information, for making "go/no-go" decisions, and for generating commands to the aircraft's autopilot and flight directors for both automatic and manually controlled flight. The program has begun with the development of the WidShear Safety Advisor, an expert system for pilot aiding that is based on the FAA Windshear Training Aid, a two-volume manual that presents an overview, pilot guide, training program, and substantiating data provides guidelines for this initial development. The WindShear Safety Advisor expert system currently contains over 200 rules and is coded in the LISP programming language.
ASTROMETRY WITH THE HUBBLE SPACE TELESCOPE: TRIGONOMETRIC PARALLAXES OF SELECTED HYADS*

We present absolute parallaxes and proper motions for seven members of the Hyades open cluster, pre-selected to lie in the core of the cluster. Our data come from archival astrometric data from fine guidance sensor (FGS) 3 and newer data for three Hyads from FGS 1r, both white-light interferometers on the Hubble Space Telescope (HST). We obtain member parallaxes from six individual FGS fields and use the field containing van Altena 622 and van Altena 627 (= HIP 21138) as an example. Proper motions, spectral classifications, and VJHK photometry of the stars comprising the astrometric reference frames provide spectrophotometric estimates of reference star absolute parallaxes. Introducing these into our model as observations with error, we determine absolute parallaxes for each Hyad. The parallax of vA 627 is significantly improved by including a perturbation orbit for this previously known spectroscopic binary, now an astrometric binary. Compared to our original (1997) determinations, a combination of new data, updated calibration, and improved analysis lowered the individual parallax errors by an average factor of 4.5. Comparing parallaxes of the four stars contained in the Hipparcos catalog, we obtain an average factor of 11 times improvement with the HST. With these new results, we also have better agreement with Hipparcos for the four stars in common. These new parallaxes provide an average distance for these seven members, D = 47.5 pc, for the core, a ±1σ dispersion depth of 3.6 pc, and a minimum depth from individual components of 16.0 ± 0.9 pc. Absolute magnitudes for each member are compared to established main sequences with excellent agreement. We obtain a weighted average distance modulus for the core of the Hyades of m – M = 3.376 ± 0.01, a value close to the previous Hipparcos values, m – M = 3.33 ± 0.02.
The adsorption and decomposition of ethylene on Pt(210), (1 · 1)Pt(110) and (2 · 1)Pt(110)

This paper summarizes the results of a series of previous papers where the adsorption and decomposition of ethylene were examined using mainly TPD and EELS. The results show that at 110 K the ethylene adsorbs into a type 2 π-bound complex on Pt(210). Some of the π-bound ethylene desorbs upon annealing to 250 K, and a small fraction is converted into ethane, and adsorbed methyl groups. However, the majority of the π-bound ethylene is stable to almost 300 K. At 330 K, the π-bound ethylene is converted to ethylylidyne (μ 4 ≡ CCH 2 −). Upon further heating, the ethylylidyne and methyl groups undergo a series of dehydrogenations and carbon-carbon bond scission processes. Only adsorbed carbon atoms and C 2 species (−[C ≡ C] x −) are seen at 700 K. Ethylene also adsorbs into a π-boud complex on a 93 K (1 × 1)Pt(110) smaple. However, the π-bound ethylene is partially converted to a di-σ species upon heating to 160 K. Some of the di-σ and π-bound ethylene reacts to form to methane and carbon atoms between 270 and 330 K, while the remainder reacts to form ethylylidyne. The ethylylidyne quickly dehydrogenates upon further heating so that only adsorbed carbon atoms and C 2 species (−[C ≡ C] x −) are seen at 450 K. The chemistry is more complex on (2 × 1)Pt(110). A mixture of di-σ and π-bound ethylene forms when ethylene adsorbs on (2 × 1) Pt(110) at 93 K. At low coverage, the mixture is converted to ethylidyne upon heating to 330 K. However, at high coverages, mixture of ethylidyne (μ 3 ≡ CCH 3 ) and ethylylidyne is seen. Again there are a series of dehydrogenations and carbon-carbon bond scission processes upon further heating. Only adsorbed carbon atoms and C 2 species (−[C ≡ C] x −) are seen at 750 K.
Towards establishing the spin of warped gravitons

We study the possibility of experimental verification of the spin=2 nature of the KaluzaKlein (KK) graviton which is predicted to exist in the extra-dimensional Randal-Sundrum (RS) warped models. The couplings of these gravitons to the particles located on or near the TeV brane is the strongest as the overlap integral of their profiles in the extra-dimension is large. Among them are unphysical Higgses (W ± L and ZL) and KK excitations of the Standard Model (SM) gauge bosons. We consider the possibility to confirm the spin-2 nature of the first KK mode of the warped graviton (G1) based on the angular distribution of the Z bozon in the graviton rest frame in the gg→ G1 → W KK (Z KK )W(Z) → W W Z, gg→ G1 → ZZ and gg→ G1 → Z KK Z → ZZH decay channels. Using Wigner Dmatrix properties, we derive the relationship between the graviton spin, signal angular distribution peak value, and other theoretically calculable quantities. We then study the LHC signals for these decay modes and find that with 1000 fb −1 of data, spin of the RS graviton up to ∼ 2 TeV may be confirmed in the pp → W KK (Z KK )W(Z) → W W Z → 3 leptons + jet + / E T and pp → ZZ → 4 leptons decay modes.
Relationship between gravity and gauge scattering in the high energy limit

Investigations of high-energy graviton-graviton and gluon-gluon scattering are performed in the leading eikonal approximation for the kinematic regime of large center of mass energy and low momentum transfer. When we retain only a set of gauge theory diagrams for which the collinear divergences cancel amongst themselves, we find a double copy relation between the amplitudes of the two theories to all loop orders. For this to happen the color structure of all diagrams in a set must be arranged to be identical. Using standard field theoretic methods, it is shown that this relation is reflected in a similar double copy relationship between the classical shockwaves of the two theories as well.
The Accretion Disk Limit Cycle Mechanism in the Black Hole X-Ray Binaries: Toward an Understanding of the Systematic Effects

We examine in detail several aspects of the physics of accretion disks that are of possible relevance to the outburst mechanism of the black hole X-ray transients. We adopt the one-dimensional, time-dependent model described in detail by Cannizzo, Chen, and Livio with parameters appropriate for a system such as A0620-00. We investigate (1) the effect of the grid spacing, utilizing a logarithmic radial spacing Δr ∝ r in addition to the spacing Δr ∝ r1/2, (2) the dependence of the local flow speed of gas within the hot part of the disk on radius and time during the time of the cooling wave propagation, (3) the shape of the outburst light curve as a function of the triggering location for the instability, (4) the long-term light curves of outbursts taken from trials in which complete cycles of quiescence and outburst are followed, both including and excluding the effect of evaporation or removal of matter from the inner edge of the disk, and (5) the strength of the self-irradiation of the outer parts of the disk by the X-rays from the inner disk. Our primary findings in each of these areas are that (1) low-resolution runs taking N 20 grid points using the logarithmic spacing produce decay timescales that are artificially slow by factors of ~2-3 and slower than exponential; (2) the deviation from steady state within the outer part of the inner hot disk appears to be in accord with the discussion given in Vishniac and Wheeler—far from the transition front, the flow speed is ~αcs(h/r), whereas at the interface between the transition front and the cold disk, the flow speed is ~αcs; (3) the outburst-triggering location must be 100rinner for the rise time of the resulting outburst to be as short as is observed in the standard, bright systems; (4) the long-term light curves using the standard model produce frequent outbursts that are triggered near the inner disk edge and that have slow rise times, and the long-term light curves calculated assuming evaporation of matter from the inner disk exhibit outbursts with longer recurrence times and somewhat (but not significantly) shorter rise times; and (5) for a system with parameters relevant to A0620-00, our "standard" system, irradiation is not a dynamically significant effect, in accord with recent results of van Paradijs.
RAYLEIGH-TAYLOR STABILITY OF A STRONG VERTICAL MAGNETIC FIELD AT THE GALACTIC CENTER CONFINED BY A DISK THREADED WITH HORIZONTAL MAGNETIC FIELD

Observations of narrow radio-emitting filaments near the Galactic center have been interpreted in previous studies as evidence of a pervasive vertical (i.e., perpendicular to the Galactic plane) milligauss magnetic field in the central ~150 pc of the Galaxy. A simple cylindrically symmetric model for the equilibrium in this central region is proposed in which horizontal (i.e., parallel to the Galactic plane) magnetic fields embedded in an annular band of partially ionized molecular material of radius ~150 pc are wrapped around vertical magnetic fields threading low-density hot plasma. The central vertical magnetic field, which has a pressure that significantly exceeds the thermal pressure of the medium, is confined by the weight of the molecular material. The stability of this equilibrium is studied indirectly by analyzing a uniformly rotating cylinder of infinite extent along the z-axis in cylindrical coordinates (r,θ,z), with low-density plasma and an axial magnetic field at r 150 pc, and a gravitational acceleration g* ∝ r directed in the - direction. Simple profiles are assumed for the density ρ, pressure p, and field strength B, with the sound speed and Alfven speeds ∝r within the dense plasma. The density profile and gravity tend to destabilize the plasma, but the plasma tends to be stabilized by rotation and magnetic tension—since the interface between the high- and low-density plasmas cannot be perturbed without bending either the horizontal or vertical field. Normal modes proportional to e with kz = 0 and m ≠ 0 are studied. Such modes neither bend nor compress the axial field at r < 150 pc but allow compressions of the dense plasma along the azimuthal magnetic field that enhance the destabilizing role of gravity. It is shown analytically that when β = 8πp/B2 is small and the dense plasma is supported against gravity primarily by rotation, the necessary and sufficient condition for stability to kz = 0 modes is |g| < 2|Ω|a, where g = g* - Ω2r is the effective gravity, Ω is the uniform angular velocity, and a is the sound speed in the dense plasma. Since the effective gravity is determined by the degree to which magnetic (and to a lesser degree pressure) forces support the dense plasma, the stability criterion gives an upper limit on the strength of the axial magnetic field, which is ~1 mG for Galactic center parameters.
Building Consistent Regression Trees From Complex Sample Data

In the past several years a wide range of methods for the construction of regression trees and other estimators based on the recursive partitioning of samples have appeared in the statistics literature. Many applications involve data collected through a complex sample design. At present, however, relatively little is known regarding the properties of these methods under complex designs. This article proposes a method for incorporating information about the complex sample design when building a regression tree using a recursive partitioning algorithm. Sufficient conditions are established for asymptotic design L2 consistency of these regression trees as estimators for an arbitrary regression function. The proposed method is illustrated with Occupational Employment Statistics establishment survey data linked to Quarterly Census of Employment and Wage payroll data of the Bureau of Labor Statistics. Performance of the nonparametric estimator is investigated through a simulation study based on this example.