cssi/SciSciGPT-SciSciNet huggingface dataset:
Interactions as a driver of galaxy evolution

Gravitational interactions and mergers are shaping and reshaping galaxies throughout the observable Universe. While observations of interacting galaxies at low redshifts yield detailed information about the processes at work, observations at high redshifts suggest that interactions and mergers were much more frequent in the past. Major mergers of nearby disc galaxies form remnants that share many properties with ellipticals and are, in essence, present–day proto–ellipticals. There is also tantalizing evidence that minor mergers of companions may help build bulges in disc galaxies. Gas plays a crucial role in such interactions. Because of its dissipative nature, it tends to get crunched into molecular form, turning into fuel for starbursts and active nuclei. Besides the evidence for ongoing interactions, signatures of past interactions and mergers in galaxies abound: tidal tails and ripples, counter–rotating discs and bulges, polar rings, systems of young globular clusters, and ageing starbursts. Galaxy formation and transformation is clearly a prolonged process, occurring up to the present–day. Overall, the currently available observational evidence points towards Hubble's morphological sequence being mainly a sequence of decreasing merger damage.
A BINARY ADDITIVE EQUATION INVOLVING FRACTIONAL POWERS

Let c be a real number with 1 < c < 2. We study the representations of a large integer n in the form $$ [m^c] + [p^c] = n, $$ where m is an integer and p is a prime number. We prove that when $1 < c < \frac{16}{15}$, all sufficiently large integers are thus representable.
The Public Regulation of Baseball Labor Relations and the Public Interest

This essay discusses the limited role played by the law in the regulation of baseball labor relations. What is termed the legal architecture of the baseball business is a superstructure of federal labor statutes that supported unionization to thereby facilitate the efforts of the Players Association to achieve the aspirations of the players. Protection of the public interest in baseball is primarily the obligation of the marketplace and of collective bargaining. In one instance, however, the law played a direct and immediate role in support of the public's interest in the continuity of baseball entertainment. The 1994 strike that almost ended the national pastime is described. A federal district court judge, however, at the behest of the National Labor Relations Board, saved baseball from itself. Whether the public interest has been served by this system of regulation is assessed, and it is concluded that the picture is mixed and the ultimate outcome remains uncertain.
Melt Infiltration Approach to Ceramic Matrix Composites

Melt infiltration offers an alternative route to the synthesis of fully dense ceramic matrix composites. Necessary conditions with respect to chemical reactivity, melt viscosity, and wetting must be satisfied. Other properties of the reinforcement and matrix constituents must also be considered. With these restrictions this generic approach is applicable to a wide range of composite systems. Preliminary structure and property results are presented for the representative systems based on particulate and whisker SiC reinforcement in combination with CaSiO3, SrSiO3, and strontium feldspar matrices.
Heavy-Ion Induced Single Event Upsets in a Bipolar Logic Device

We present heavy ion test results for a bipolar logic device of moderate complexity. Such devices require the implementation of special techniques for testing circuits of varying upset sensitivity, and unlike similar MOS devices, present problems with test data interpretation.
Sharp Recovery Bounds for Convex Demixing, with Applications

Demixing refers to the challenge of identifying two structured signals given only the sum of the two signals and prior information about their structures. Examples include the problem of separating a signal that is sparse with respect to one basis from a signal that is sparse with respect to a second basis, and the problem of decomposing an observed matrix into a low-rank matrix plus a sparse matrix. This paper describes and analyzes a framework, based on convex optimization, for solving these demixing problems, and many others. This work introduces a randomized signal model that ensures that the two structures are incoherent, i.e., generically oriented. For an observation from this model, this approach identifies a summary statistic that reflects the complexity of a particular signal. The difficulty of separating two structured, incoherent signals depends only on the total complexity of the two structures. Some applications include (1) demixing two signals that are sparse in mutually incoherent bases, (2) decoding spread-spectrum transmissions in the presence of impulsive errors, and (3) removing sparse corruptions from a low-rank matrix. In each case, the theoretical analysis of the convex demixing method closely matches its empirical behavior.
Neutron experiments with a tandem accelerator

Abstract The Wisconsin tandem accelerator is used part of the time for experiments in neutron physics. In these experiments the properties of neutrons from charged-particle reactions as well as the interaction of neutrons with nuclei are studied. Some of the techniques used and some of the results obtained are described.
Catalytic Quantum Error Correction

We develop the theory of entanglement-assisted quantum error-correcting (EAQEC) codes, a generalization of the stabilizer formalism to the setting in which the sender and receiver have access to preshared entanglement. Conventional stabilizer codes are equivalent to self-orthogonal symplectic codes. In contrast, EAQEC codes do not require self-orthogonality, which greatly simplifies their construction. We show how any classical binary or quaternary block code can be made into an EAQEC code. We provide a table of best known EAQEC codes with code length up to 10. With the self-orthogonality constraint removed, we see that the distance of an EAQEC code can be better than any standard quantum error-correcting code with the same fixed net yield. In a quantum computation setting, EAQEC codes give rise to catalytic quantum codes, which assume a subset of the qubits are noiseless. We also give an alternative construction of EAQEC codes by making classical entanglement-assisted codes coherent.
The LevelArray: A Fast, Practical Long-Lived Renaming Algorithm

The long-lived renaming problem appears in shared-memory systems where a set of threads need to register and deregister frequently from the computation, while concurrent operations scan the set of currently registered threads. Instances of this problem show up in concurrent implementations of transactional memory, flat combining, thread barriers, and memory reclamation schemes for lock-free data structures. In this paper, we analyze a randomized solution for long-lived renaming. The algorithmic technique we consider, called the Level Array, has previously been used for hashing and one-shot (single-use) renaming. Our main contribution is to prove that, in long-lived executions, where processes may register and deregister polynomially many times, the technique guarantees constant steps on average and O (log log n) steps with high probability for registering, unit cost for deregistering, and O (n) steps for collect queries, where n is an upper bound on the number of processes that may be active at any point in time. We also show that the algorithm has the surprising property that it is self-healing: under reasonable assumptions on the schedule, operations running while the data structure is in a degraded state implicitly help the data structure re-balance itself. This subtle mechanism obviates the need for expensive periodic rebuilding procedures. Our benchmarks validate this approach, showing that, for typical use parameters, the average number of steps a process takes to register is less than two and the worst-case number of steps is bounded by six, even in executions with billions of operations. We contrast this with other randomized implementations, whose worst-case behavior we show to be unreliable, and with deterministic implementations, whose cost is linear in n.
Ionospheric and plasmaspheric effects in satellite navigation systems

A satellite navigation concept requires determination of time (or phase) delays that satellite-emitted signals experience when traversing the distance between satellite and observer. A pulse propagating this distance is slowed down somewhat from its free space velocity-by an amount directly proportional to the total number of free electrons (TEC) along its path. Ranging accuracy requirements mandate compensation for this additional signal delay. The total electron content for high-orbit satellites includes the ionospheric as well as the plasmaspheric electron content. The Radio Beacon Experiment (RBE) aboard the geostationary ATS-6 Satellite provides the opportunity to determine the ionospheric content (up to heights of \sim 1500 km), the total electron content (from observer to satellite), and the plasmaspheric content (the difference of the two). Observations of ionospheric contents were carried out at Fort Monmouth from the launch of the ATS-6 in May 1974 to its planned drift eastward in June 1975. Diurnal, day-to-day, and seasonal variations of the contents were observed. Diurnal plasmaspheric changes were smaller in percent and in absolute terms than ionospheric changes. While, in general, ionospheric contents were larger during the fall than during the spring, the plasmaspheric contents exhibited the opposite behavior. The diurnal behavior of the ratio of plasmaspheric-to-total contents exhibited variations from \sim 45 percent at night to \gsim 10 percent during the day, with rapid changes after local sunrise and after local sunset.
DQIT: /spl mu/-synthesis without D-scale fitting

A new approach called D-Q iteration (DQIT) for synthesizing robust H/sub /spl infin// controllers is proposed to avoid D-scale fitting in D-K iteration (DKIT). Each iteration includes a D-step and a Q-step. In the D-step, the D-scale at each frequency is optimized as in DKIT, but D-scale fitting is not required. In the Q-step, the scaled H/sub /spl infin// problem is approximated by a finite-dimensional Q-parameter optimization problem in the frequency domain, using D-scales directly. Numerical examples show significant improvement in some cases.
Relative Inflation-Forecast as Monetary Policy Target for Convergence to the Euro

Abstract A monetary policy framework based on targeting a relative inflation-forecast is proposed for the economies converging to the euro. Such strategy aims at containing the differentials between the domestic and the implicit monetary union inflation-forecasts. Hence, these differentials become a basis for setting an operational policy target. The proposed framework can be viewed as an extension of flexible inflation targeting that prioritizes low and stable inflation over the exchange rate stability. It is believed to be consistent with the Maastricht convergence criteria and can be implemented in concurrence with the exchange rate stability benchmark for the ERM2. Several empirical tests are conducted to determine feasibility of adopting an instrument rule for the proposed policy framework in the three largest inflation-targeting candidates to the euro: the Czech Republic, Hungary and Poland. The stability tests as well as the volatility dynamics tests suggest that adoption of the relative inflation-forecast targeting framework is possible in these countries.
(47171) 1999 TC36, A transneptunian triple

Abstract We present new analysis of HST images of (47171) 1999 TC36 that confirm it as a triple system. Fits to the point-spread function (PSF) consistently show that the apparent primary is itself composed of two similar-sized components. The two central components, A1 and A2, can be consistently identified in each of nine epochs spread over 7 years of time. In each instance, the component separation, ranging from 0.023 ± 0.002 to 0.031 ± 0.003 arcsec, is roughly one half of the Hubble Space Telescope’s diffraction limit at 606 nm. The orbit of the central pair has a semi-major axis of a ∼ 867 km with a period of P ∼ 1.9 days. These orbital parameters yield a system mass that is consistent with Msys = 12.75 ± 0.06 × 1018 kg derived from the orbit of the more distant secondary, component B. The diameters of the three components are d A 1 = 286 - 38 + 45 km, d A 2 = 265 - 35 + 41 km and d B = 139 - 18 + 22 km . The relative sizes of these components are more similar than in any other known multiple in the Solar System. Taken together, the diameters and system mass yield a bulk density of ρ = 542 - 211 + 317 kg m - 3 . HST photometry shows that component B is variable with an amplitude of ⩾0.17 ± 0.05 magnitudes. Components A1 and A2 do not show variability larger than 0.08 ± 0.03 magnitudes approximately consistent with the orientation of the mutual orbit plane and tidally distorted equilibrium shapes. The system has high specific angular momentum of J/J′ = 0.93, comparable to most of the known transneptunian binaries.
Radioxenon Production and Transport from an Underground Nuclear Detonation to Ground Surface

Radioxenon isotopes are considered as possible indicators for detecting and discriminating underground nuclear explosions. To monitor and sample the release of radioxenon isotopes, both independent and chain-reaction yields need to be considered together with multiphase transport in geological systems from the detonation point to the ground surface. For the sake of simplicity, modeling of radioxenon isotopic radioactivities has typically been focused either on chain reactions in a batch reactor without considering multiphase transport or on radionuclide transport with simplified reactions. Although numerical methods are available for integrating coupled differential equations of complex decay networks, the stiffness of ordinary differential equations due to greatly differing decay rates may require substantial additional effort to obtain solutions for the fully coupled system. For this reason, closed-form solutions for sequential reactions and numerical solutions for multiparent converging and multidaughter branching reactions were previously developed and used to simulate xenon isotopic radioactivities in the batch reactor mode. In this paper, we develop a fully coupled numerical model, which involves tracking 24 components (i.e., 22 radionuclide components plus air and water) in two phases to enhance model predictability of simultaneously simulating xenon isotopic transport and fully coupled chain reactions. To validate the numerical model and verify the corresponding computer code, we derived closed-form solutions for first-order xenon reactions in a batch reactor mode and for single-gas phase transport coupled with the xenon reactions in a one-dimensional column. Finally, cylindrical 3-D simulations of two-phase flow within a dual permeability fracture-matrix medium, simulating the geohydrologic regime of an underground nuclear explosion, indicate the existence of both a strong temporal and spatial dependence of xenon isotopic ratios sampled at the surface. In the example presented here, temporally evolving subsurface xenon isotopic ratios are found to migrate across the discrimination line delineating civilian nuclear activities from an underground nuclear explosion in the KALINOWSKI Multi-Isotope Ratio Chart.
Aftershock Characteristics as a Means of Discriminating Explosions from Earthquakes

Abstract The behavior of aftershock sequences around the Nevada Test Site (NTS) in the southern Great Basin is characterized as a potential discriminant between explosions and earthquakes. The aftershock model designed by Reasenberg and Jones (1989, 1994) allows for a probabilistic statement of earthquakelike aftershock behavior at any time after the mainshock. We use this model to define two types of aftershock discriminants. The first defines M X , or the minimum magnitude of an aftershock expected within a given duration after the mainshock with probability X . Of the 67 earthquakes with M >4 in the study region, 63 of them produce an aftershock greater than M 99 within the first 7 days after a mainshock. This is contrasted with only six of 93 explosions with M >4 that produce an aftershock greater than M 99 for the same period. If the aftershock magnitude threshold is lowered and the M 90 criteria is used, then no explosions produce an aftershock greater than M 90 for durations that end more than 17 days after the mainshock. The other discriminant defines N X , or the minimum cumulative number of aftershocks expected for a given time after the mainshock with probability X . Similar to the aftershock magnitude discriminant, five earthquakes do not produce more aftershocks than N 99 within 7 days after the mainshock. However, within the same period, all but one of the explosions produce fewer aftershocks than N 99 . One explosion is added if the duration is shortened to 2 days after the mainshock. The cumulative number aftershock discriminant is more reliable, especially at short durations, but requires a low magnitude of completeness for the given earthquake catalog. These results at NTS are quite promising and should be evaluated at other nuclear test sites to understand the effects of differences in the geologic setting and nuclear testing practices on its performance.
Halftone patterns for arbitrary screen periodicities

Ordered dither has long been considered to be a simple and effective method of image binarization. If ft is the two-dimensional continuous signal to be halftoned, then ordered dither consists of thresholding the discrete space signal fn against a periodic spatial screen σn whose periodicity is defined by a periodicity matrix N. Although in some dithering schemes used in practice, N is not assumed to be a diagonal matrix, most theory on dithering does include this assumption. Consequently, the majority of optimal dither patterns are designed for rectangularly periodic screen functions. In this paper the benefits of altering N are analyzed in an effort to improve the ordered dither algorithm. Optimal dither patterns for several representative nonrectangular screen periodicities are derived. It is shown that the optimal pattern sequences for these periodicities have gray-scale-rendition capabilities superior to those of previously considered dither patterns, resulting in substantially improved image fidelity.
Localization and Conjectures from String Duality

We describe the applications of localization methods, in particular the functorial localization formula, in the proofs of several conjectures from string theory. Functorial localization formula pushes the computations on complicated moduli spaces to simple moduli spaces. It is a key technique in the proof of the general mirror formulas, the proof of the Hori-Vafa formulas for explicit expressions of basic hypergeometric series of homogeneous manifolds, the proof of the Marino-Vafa formula, its generalizations to two partition analogue. We will also discuss our development of the mathematical theory of topological vertex and simple localization proofs of the ELSV formula and Witten conjecture.
Effects of noise level in fitting in situ optical reflectance spectroscopy data

Abstract Curve fitting of simulated optical reflectance spectroscopy data is used to evaluate the accuracy of parameters derived from the fits of actual data. These simulations show that to determine the index of refraction n to an accuracy of 0.0015 (corresponding 0.044% for Al 0.5 Ga 0.5 As at growth temperature), a reflectance noise with standard deviation σ ⩽0.00005 is required if the absolute reflectance calibration is unknown. The simulations also show that when the absolute reflectance is known within ±0.05%, a noise of up to σ =0.0008 would result in the same desired accuracy for n . The factors contributing to the uncertainty of the reflectance scaling factor include the temperatures of the photodetectors, stability of light intensity, and deposits on the window of the growth chamber. These factors are investigated experimentally and possible solutions that will allow calibration within the goal range are discussed.
Definition of database transactions by the casual user

Database management systems have been in general use for more than a decade. However, only recently have advances in technology and reduction in cost made such systems feasible for the small enterprise. Experience with database systems over the years indicates that the definition of a schema, design and implementation of a set of application programs, and maintenance of the system are far from trivial tasks. Consequently, the ability to perform effectively any of the above three tasks has become a highly marketable skill.
Robust Lasso With Missing and Grossly Corrupted Observations

This paper studies the problem of accurately recovering a $k$ -sparse vector $\beta^{\star}\in\BBR^{p}$ from highly corrupted linear measurements $y=X\beta^{\star}+e^{\star}+w$ , where $e^{\star}\in\BBR^{n}$ is a sparse error vector whose nonzero entries may be unbounded and $w$ is a stochastic noise term. We propose a so-called extended Lasso optimization which takes into consideration sparse prior information of both $\beta^{\star}$ and $e^{\star}$ . Our first result shows that the extended Lasso can faithfully recover both the regression as well as the corruption vector. Our analysis relies on the notion of extended restricted eigenvalue for the design matrix $X$ . Our second set of results applies to a general class of Gaussian design matrix $X$ with i.i.d. rows ${\cal N}(0,\Sigma)$ , for which we can establish a surprising result: the extended Lasso can recover exact signed supports of both $\beta^{\star}$ and $e^{\star}$ from only $\Omega(k\log p\log n)$ observations, even when a linear fraction of observations is grossly corrupted. Our analysis also shows that this amount of observations required to achieve exact signed support is indeed optimal.
Takeover Bidding with Toeholds: The Case of the Owner's Curse

This article demonstrates that a potential acquirer with a toehold bids aggressively and possibly overpays in equilibrium. The aggressiveness of a bidder with a toehold increases further if he is able to renege on his winning bid. A bidder without a toehold, however, responds by shading his bids. The target firm can increase competition and the expected sale price if it only entertains nonretractable bids. This article provides testable implications on the probability of bidder success, stock price reactions on bid revisions and on resolution of the contest, and expected gains to bidders and the target firm.
On the Space of Conics on Complete Intersections

We get sharp degree bound for generic smoothness and connectedness of the space of lines and conics in low degree complete intersections which generalizes the old work about Fano scheme of lines on hypersurfaces. As a consequence, we prove that for a Fano complete intersection $$X$$ with index $$\ge 2$$ , the $$1$$ -Griffiths group generated by algebraic $$1$$ -cycles homologous to $$0$$ modulo algebraic equivalence is trivial, which is a conjecture for general rationally connected varieties.
Imaging the temporal fossa

The purpose of our study was to delineate the interconnections in the temporal fossa that are visible on high-resolution clinical images.Thin-section MR images and CT scans of the temporal fossa in two normal volunteers were obtained in coronal and axial sections. MR images, CT scans, or both of 20 patients with demonstrable spread of disease were reviewed.The imaging studies of patients with disease proved more informative than images of the normal subject or the published anatomic and surgical descriptions of the temporal fossa. We recognized five discrete radiographically defined regions: the connective tissue layer, compartment of the superficial fat pad, compartment of the deep fat pad, compartment of the temporal muscle (superior recess of the suprazygomatic masticator), and subperiosteal zone. Important, tortuous, and to our knowledge undescribed interconnections between the scalp, posterior neck, eyelid, face, and the suprazygomatic masticator were delineated.Imaging studies of the temporal fossa ...
Conformationally restricted analogs of histamine H1 receptor antagonists: trans and cis-1-benzyl-3-dimethylamino-6-phenylpiperidine.

Abstract The syntheses of trans- and cis-1-benzyl-3-dimethylamino-6-phenylpiperidine (1 and 2) are described. Compounds 1 and 2 were found to be inhibitors to histamine, acetylcholine, and barium chloride induced contractions of the isolated guinea pig ileum. Compounds 1 and 2 do not exhibit appreciable stereoselectivity in their ability to inhibit smooth muscle contractions. The cis compound 2 is a more effective inhibitor of histamine N-methyltransferase than the trans isomer 1.
A POSSIBLE SIGNATURE OF LENSE-THIRRING PRECESSION IN DIPPING AND ECLIPSING NEUTRON-STAR LOW-MASS X-RAY BINARIES

Relativistic Lense-Thirring precession of a tilted inner accretion disk around a compact object has been proposed as a mechanism for low-frequency (~0.01-70 Hz) quasi-periodic oscillations (QPOs) in the light curves of X-ray binaries. A substantial misalignment angle (~15°-20°) between the inner-disk rotation axis and the compact-object spin axis is required for the effects of this precession to produce observable modulations in the X-ray light curve. A consequence of this misalignment is that in high-inclination X-ray binaries the precessing inner disk will quasi-periodically intercept our line of sight to the compact object. In the case of neutron-star systems, this should have a significant observational effect, since a large fraction of the accretion energy is released on or near the neutron-star surface. In this Letter, I suggest that this specific effect of Lense-Thirring precession may already have been observed as ~1 Hz QPOs in several dipping/eclipsing neutron-star X-ray binaries.
A Classification of Cube-Connected Networks with a Simple Control Scheme

The correspondence presents three classes of cube-connected networks with individual stage control based on a group theoretic modeling of interconnection networks. It is shown that these classes of networks retain nonisomorphic groups of permutations. Although the permutations realizable by such networks are rather limited in number, the simplicity of their control scheme makes them attractive. Moreover, the interconnection power of these networks can be enhanced by simulating the networks which belong to one class by any member of that class.
Two Timescale Dispersal of Magnetized Protoplanetary Disks

Protoplanetary disks are likely to be threaded by a weak net flux of vertical magnetic field that is a remnant of the much larger fluxes present in molecular cloud cores. If this flux is approximately conserved its dynamical importance will increase as mass is accreted, initially by stimulating magnetorotational disk turbulence and subsequently by enabling wind angular momentum loss. We use fits to numerical simulations of ambipolar dominated disk turbulence to construct simplified one-dimensional evolution models for weakly magnetized protoplanetary disks. We show that the late onset of significant angular momentum loss in a wind can give rise to ''two timescale'' disk evolution in which a long phase of viscous evolution precedes rapid dispersal as the wind becomes dominant. The wide dispersion in disk lifetimes could therefore be due to varying initial levels of net flux. Magnetohydrodynamic (MHD) wind triggered dispersal differs from photoevaporative dispersal in predicting mass loss from small (<1 AU) scales, where thermal winds are suppressed. Our specific models are based on a limited set of simulations that remain uncertain, but qualitatively similar evolution appears likely if mass is lost from disks more quickly than flux, and if MHD winds become important as the plasma β decreases.
Shielding Applications from an Untrusted Cloud with Haven

Today’s cloud computing infrastructure requires substantial trust. Cloud users rely on both the provider’s staff and its globally distributed software/hardware platform not to expose any of their private data.We introduce the notion of shielded execution, which protects the confidentiality and integrity of a program and its data from the platform on which it runs (i.e., the cloud operator’s OS, VM, and firmware). Our prototype, Haven, is the first system to achieve shielded execution of unmodified legacy applications, including SQL Server and Apache, on a commodity OS (Windows) and commodity hardware. Haven leverages the hardware protection of Intel SGX to defend against privileged code and physical attacks such as memory probes, and also addresses the dual challenges of executing unmodified legacy binaries and protecting them from a malicious host. This work motivated recent changes in the SGX specification.
Numerical modeling of elastic-wave scattering by near-surface heterogeneities

ABSTRACTIn land seismic data, scattering from surface and near-surface heterogeneities adds complexity to the recorded signal and masks weak primary reflections. To understand the effects of near-surface heterogeneities on seismic reflections, we simulated seismic-wave scattering from arbitrary-shaped, shallow, subsurface heterogeneities through the use of a perturbation method for elastic waves and finite-difference forward modeling. The near-surface scattered wavefield was modeled by looking at the difference between the calculated incident (i.e., in the absence of scatterers) and the total wavefields. Wave propagation was simulated for several earth models with different near-surface characteristics to isolate and quantify the influence of scattering on the quality of the seismic signal. The results indicated that the direct surface waves and the upgoing reflections were scattered by the near-surface heterogeneities. The scattering took place from body waves to surface waves and from surface waves to b...
Enantiopure N-Acyldihydropyridones as Synthetic Intermediates: Asymmetric Syntheses of Indolizidine Alkaloids (-)-205A, (-)-207A, and (-)-235B.

Concise asymmetric syntheses of indolizidine alkaloids (−)-205A, (−)-207A, and (−)-235B were accomplished with a high degree of stereocontrol in eleven steps. Addition of 4-(1-butenyl)magnesium bromide to 1-acylpyridinium salt 5, prepared in situ from 4-methoxy-3-(triisopropylsilyl)pyridine and the chloroformate of (+)-trans-2-(α-cumyl)cyclohexanol, gave a 91% yield of diastereomerically pure dihydropyridone 6. Oxidative cleavage of 6 and subsequent reduction provided alcohol 7 in 81% yield. Removal of the chiral auxilliary and TIPS group (NaOMe; 10% HCl), N-acylation with BnOCOCCl, and treatment with NCS/Ph3P gave chloride 10. Methylation at C-3, copper-mediated conjugate addition of 4-(benzyloxy)butylmagnesium bromide, and vinyl triflate formation provided 13 in a stereoselective fashion. Catalytic reduction of the vinyl triflate moiety, simultaneous cleavage of the benzyl ether and Cbz groups, and cyclization to give amino alcohol 14 was effected via a one-pot reaction. Oxidation of 14 with the Dess−Ma...
Posttraumatic Renovascular Hypertension After Occult Renal Injury

Objective: Hypertension secondary to renal injury is an unusual problem, but one that occurs with some frequency in an active trauma unit. The incidence and management of posttraumatic renovascular hypertension at our Level I trauma center was reviewed. Methods: A retrospective review of a trauma database was performed on patients treated by our trauma service between 1977 and 1996. Seven patients were identified who developed arterial hypertension as a direct result of a renal injury. Results: All of the patients sustained multiple injuries, with five requiring celiotomy to control bleeding. Renal injuries were occult, and there was no compelling reason to suspect injury to the kidney. No patient had a history of hypertension or elevated arterial pressure on admission; however, sustained arterial hypertension was noted within 2 weeks to 8 months of injury. Arteriography was positive in all seven patients, with findings that included lacerations of the main renal artery, its major branches, or intrarenal constriction of the renal artery (presumably from scarring). Renal-vein renin assays localized to the injured kidney in six patients. Treatment included nephrectomy in four cases, revascularization in one case, and medical management in two cases. All of the patients treated operatively had prompt relief of their hypertension. The two patients treated soley by medical therapy had prompt, durable control of their arterial pressure with a single medication. However, medical treatment had failed before operation in several of the patients. Conclusions: Because of the serious complications associated with undiagnosed hypertension, new-onset or sustained hypertension after major trauma should be evaluated with attention to a possible renal cause.
2-cancellative hypergraphs and codes

A family of sets (and the corresponding family of 0-1 vectors) is called t-cancellative if, for all distinct t + 2 members A1,.i¾ .i¾ ., At and B, C ∈ , A_1\cup\cdots \cup A_t\cup B \neq A_1\cup \cdots \cup A_t \cup C. \] Let ct(n) be the size of the largest t-cancellative family on n elements, and let ct(n, r) denote the largest r-uniform family. We improve the previous upper bounds, e.g., we show c2(n) â¤ 20.322n (for n >n0). Using an algebraic construction we show that c2(n, 2k) = I(nk) for each k when n â ∞.
Circulating Luteinizing Hormone Pulse Frequency in Women with Polycystic Ovary Syndrome

To determine whether pulsatile LH frequency is altered in patients with the polycystic ovary syndrome (PCO) serum LH was measured every 10 min for 12 h (0800-2000 h) in nine patients. Six cycling women studied in the midfollicular (MF) or early follicular (EF) phases of their cycle served as controls. Three of these women were studied in both phases, yielding a total of nine control studies. In the PCO patients the mean LH pulse frequency was 12.1 +/- 0.7 (+/- SE) pulses/12 h. This value was indistinguishable from that of normal EF (12.1 +/- 0.4 pulses/12 h) or MF women (12.0 +/- 0.7 pulses/12 h). In contrast, the mean LH pulse amplitude in the PCO patients (12.2 +/- 2.7 mIU/mL) was higher (P less than 0.05) than that in normal women in either phase (EF, 6.2 +/- 0.8 mIU/mL; MF, 6.4 +/- 0.6 mIU/mL). These results suggest that the elevations in serum LH levels that occur in PCO patients are due primarily to increased LH pulse amplitude rather than increased pulse frequency.
Halogen exchange reactions of perhalo-3-azaalkenes and their subsequent dehalogenation to form hetero-1,3-dienes

Abstract Treatment of the perhalogenated azaalkenes, R x CFNCF 2 CFXBr (R x CF 3 , C 2 F 5 , ClCF 2 ; XF, CF 3 ) with AlCl 3 readily produces new imines of the type R x CClNCCl 2 CFXBr and R x CCl 2 NCClCFXBr. Dehalogenation of these new imines using activated zinc dust affords a series of novel hetero-1,3-dienes (R x CClNCClCFX).
Quantum information processing with atoms and photons

Quantum information processors exploit the quantum features of superposition and entanglement for applications not possible in classical devices, offering the potential for significant improvements in the communication and processing of information. Experimental realization of large-scale quantum information processors remains a long-term vision, as the required nearly pure quantum behaviour is observed only in exotic hardware such as individual laser-cooled atoms and isolated photons. But recent theoretical and experimental advances suggest that cold atoms and individual photons may lead the way towards bigger and better quantum information processors, effectively building mesoscopic versions of 'Schrodinger's cat' from the bottom up.
Eliminating the fanout bottleneck in parallel long BCH encoders

Long BCH codes can achieve about 0.6-dB additional coding gain over Reed-Solomon codes with similar code rate in long-haul optical communication systems. BCH encoders are conventionally implemented by a linear feedback shift register architecture. Encoders of long BCH codes may suffer from the effect of large fanout, which may reduce the achievable clock speed. The data rate requirement of optical applications require parallel implementations of the BCH encoders. In this paper, a novel scheme based on look-ahead computation and retiming is proposed to eliminate the effect of large fanout in parallel long BCH encoders. For a (2047, 1926) code, compared to the original parallel BCH encoder architecture, the modified architecture can achieve a speedup of 132%.
Theoretical analysis of subtractive color mixture characteristics

Understanding the characteristics of the stimulus values of colors obtained by subtractive color mixture is not easy, compared with those obtained by additive color mixture, since the relationship between superimposed absorption media and the stimulus values is not simple. In this article, using the assumption of the Lambert-Beer model for subtractive color mixture, we prove several theorems regarding the stimulus values of colors obtained by subtractive color mixture. Although these theorems are proved theoretically, numerical illustrations are also shown to confirm the theorems. The results of this paper will contribute to a systematization of subtractive color mixture. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 175–181, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10143
Supernova Remnants in the Fossil Starburst in M82

We report the discovery of 10 compact Hα-bright sources in the poststarburst region northeast of the center of M82, called M82 B. These objects have Hα luminosities and sizes consistent with Type II supernova remnants (SNRs). They fall on the same Hα surface brightness–diameter relation (Σ-D) defined by SNRs in other nearby star-forming galaxies, with the M82 candidates lying preferentially at the small-diameter end. These are the first candidates for optically visible SNRs in M82 outside the heavily obscured central starburst within about 250 pc from the galactic center. If these sources are SNRs, they set an upper limit to the end of the starburst in region B2, about 500 pc from the galaxy's core, of about 50 Myr. Region B1, about 1000 pc from the core, lacks good SNR candidates and is evidently somewhat older. This suggests that star formation in the galaxy has propagated inward toward the present-day intense starburst core.
Latest results on weak semi-leptonic hyperon decays in KTeV

Abstract The KTeV experiment at Fermilab has finished its Ξ 0 semi-leptonic decay analysis from the 1997 run and presented here are the final numbers for the branching ratio and form factors. A new run with three times the statistics was taken in 1999 and a first look at the data shows the quality and consistency of the results, predicting a similar improvement in these measurements.
Towards Addressing Model Uncertainty: Robust Execution-Time Coordination for Teamwork

Despite their worst-case NEXP-complete planning complexity, DEC-POMDPs remain a popular framework for multiagent teamwork. This paper introduces effective teamwork under model uncertainty (i.e., potentially inaccurate transition and observation functions) as a novel challenge for DEC-POMDPs and presents MODERN, the first execution-centric framework for DEC-POMDPs explicitly motivated by addressing such model uncertainty. MODERN's shift of coordination reasoning from planning-time to execution-time avoids the high cost of computing optimal plans whose promised quality may not be realized in practice. There are three key ideas in MODERN: (i) it maintains an exponentially smaller model of other agents' beliefs and actions than in previous work and then further reduces the computation-time and space expense of this model via bounded pruning, (ii) it reduces execution-time computation by exploiting BDI theories of teamwork, and limits communication to key trigger points, and (iii) it limits its decision-theoretic reasoning about communication to trigger points and uses a systematic markup to encourage extra communication at these points -- thus reducing uncertainty among team members at trigger points. We empirically show that MODERN is substantially faster than existing DEC-POMDP execution-centric methods while achieving significantly higher reward.
A Threat Model for Security Specification in Security Evaluation by ISO/IEC 19791

ISO/IEC TR 19791 is an international standard that must be used as the basis for the security evaluation of operational systems. This standard has been recently developed, and the first version was made available in May 2006. ISO/IEC TR 19791 is intended to be an extension of ISO/IEC 15408, known as “Common Criteria” (CC). In order to evaluate an IT product or system using CC or ISO/IEC TR 19791, developers must create a Security Target (ST), or a System Security Target (SST). However, a problem encountered in creating these is the determination of the Security Problem Definitions (SPDs), because the SPDs fall outside of the scope of CC. Neither ISO/IEC 15408 nor ISO/IEC TR 19791 provides a framework for risk analysis or the specification of threats. In this paper, we propose a threat model based on multiple international standards and evaluated ST information, and describe a Web application that can be used for security specifications in the production of STs and SSTs which are to be evaluated by CC and ISO/IEC TR 19791, respectively.
A Controlled Trial of Nonoxynol 9 Film to Reduce Male-to-Female Transmission of Sexually Transmitted Diseases

Background Nonoxynol 9 is a proved spermicide, but whether it is also a microbicide is uncertain. A truly effective vaginal microbicide would reduce the susceptibility of women to sexually transmitted diseases, including infection with the human immunodeficiency virus (HIV). Methods We enrolled 1292 HIV-negative female sex workers in Cameroon in a double-blind, placebo-controlled study in which the participants were randomly assigned to use either a film containing 70 mg of nonoxynol 9 or a placebo film, inserted into the vagina before intercourse. All of the women were provided with latex condoms and were instructed to have their male sexual partners use them. At monthly follow-up visits, we examined the women with a colposcope for genital lesions, tested endocervical specimens for gonorrhea and chlamydia infection with DNA probes, tested for HIV infection, and treated the women for curable sexually transmitted diseases. Results The rates of HIV infection (cases per 100 woman-years) were 6.7 in the nonox...
Carbon, water, and heat flux responses to experimental burning and drought in a tallgrass prairie

Abstract Drought and fire are common disturbances to grassland ecosystems. We report two years of eddy covariance ecosystem–atmosphere fluxes and biometric variables measured in nearby burned and unburned pastures in the US Southern Great Plains. Over the course of the experiment, annual precipitation (∼600 mm yr−1) was lower than the long term mean (∼860 mm yr−1). Soil moisture decreased from productive conditions in March 2005 dry, unproductive conditions during the growing season starting in March 2006. Just prior to the burn in early March 2005, burned and unburned pastures contained 520 ± 60 and 360 ± 40 g C m−2 of total above ground biomass (AGB) and litter, respectively. The fire removed approximately 200 g C m−2 of litter and biomass. In the 2005 growing season following the burn, maximum green AGB was 450 ± 60 and 270 ± 40 g C m−2, with corresponding cumulative annual net ecosystem carbon exchange (NEE) of −330 and −150 g C m−2 for the burned and unburned pastures, respectively. In contrast to NEE, cumulative mean sensible heat and water fluxes were approximately equal in both pastures during the growing season, suggesting either an increase in water use efficiency or a decrease in evaporation in the burned relative to the unburned pasture. In the 2006 growing season, dry conditions decreased carbon uptake and latent heat, and increased sensible heat fluxes. Peak AGB was reduced to 210 ± 30 g C m−2 and 140 ± 30 g C m−2 in the burned and unburned pastures, respectively, while NEE was near zero. These results suggest that the lack of precipitation was responsible for most of the interannual variation in carbon exchange for these un-irrigated prairie pastures.
Evolution of Heuristics by Human Operators in Control Systems

This paper presents a mathematical model for decision making in control systems. The model is constructed to perform four modes of control: 1) probing, 2) gradient, 3) heuristic, and 4) terminal. The operation of the model switches from one mode to another by following certain decision logic, which simulates the function of a human operator in a control system and the evolution of heuristics for control. The simulation results compare favorably with the data obtained from experiments with subjects.
Simulations of Noise in Phase-Separated Transition-Edge Sensors for SuperCDMS

We briefly review a simple model of superconducting-normal phase-separation in transition-edge sensors (TESs) in the SuperCDMS experiment. After discussing some design considerations relevant to the TESs in the experiment, we study noise sources in both the phase-separated and phase-uniform cases. Such simulations will be valuable for optimizing the critical temperature and TES length of future SuperCDMS detectors.
Do Executives' Backgrounds Matter to IPO Investors? Evidence from the Life Science Industry

In this study, we focus on the impact of senior executives' industry backgrounds on the amount of capital raised in the stock market. The primary contribution of the study entails applying the upper echelon theory to the initial public offering (IPO) phenomenon. Specifically, we hypothesize that the industry backgrounds of corporate executives affect the amount of capital that the firm raised in the primary stock market. We argue that the firm's future investment strategies are unobserved by the investors ex-ante and investors expect firms' investment strategies to be based on the executives' industry backgrounds. As a result, the executives' industry backgrounds influence the investors' expectations about what investment strategies the firm is likely to deploy. Furthermore, the above logic also suggests that executives of different industry backgrounds should prefer different investment strategies corresponding with demand for different amount of capital. As a result, we expect the industry backgrounds to covary with the capital raised from both the supply and demand perspectives. To test the hypotheses, we ran a reduced econometric model wherein the executives' background predicts the amount of capital raised. Regression analyses suggest that the capital raised is negatively associated with the number of senior executives with prior career experience in the healthcare and genomic sectors but positively associated with the number of senior executives with prior career experience in regulatory affairs. The results provide tentative support for the notion that investors infer corporate strategies from senior executives' industry backgrounds.
A new derivation of the Picard-Fuchs equations for effective N = 2 super Yang-Mills theories

Abstract A new method to obtain the Picard-Fuchs equations of effective, N = 2 supersymmetric gauge theories in 4 dimensions is developed. It includes both pure super Yang-Mills and supersymmetric gauge theories with massless matter hypermultiplets. It applies to all classical gauge groups, and directly produces a decoupled set of second-order, partial differential equations satisfied by the period integrals of the Seiberg-Witten differential along the 1-cycles of the algebraic curves describing the vacuum structure of the corresponding N = 2 theory.