cssi/SciSciGPT-SciSciNet huggingface dataset:
Enzymatic catalysis of proton transfer and decarboxylation reactions

Deprotonation of carbon and decarboxylation at enzyme active sites proceed through the same carbanion intermediates as for the uncatalyzed reactions in water. The mechanism for the enzymatic reactions can be studied at the same level of detail as for nonenzymatic reactions, using the mechanistic tools developed by physical organic chemists. Triosephosphate isomerase (TIM) catalyzed interconversion of D-glyceraldehyde 3-phosphate and dihydroxyacetone phosphate is being studied as a prototype for enzyme catalyzed proton transfer, and orotidine monophosphate decarboxylase (OMPDC) catalyzed decarboxylation of orotidine 5′-monophosphate is being studied as a prototype for enzyme-catalyzed decarboxylation. 1H NMR spectroscopy is an excellent analytical method to monitor proton transfer to and from carbon catalyzed by these enzymes in D2O. Studies of these partial enzyme-catalyzed exchange reactions provide novel insight into the stability of carbanion reaction intermediates, that is not accessible in studies of the full enzymatic reaction. The importance of flexible enzyme loops and the contribution of interactions between these loops and the substrate phosphodianion to the enzymatic rate acceleration are discussed. The similarity in the interactions of OMPDC and TIM with the phosphodianion of bound substrate is emphasized.
Discovery and measurement of sleptons, binos, and winos with a Z'

Extensions of the MSSM could significantly alter its phenomenology at the LHC. We study the case in which the MSSM is extended by an additional U(1) gauge symmetry, which is spontaneously broken at a few TeV. The production cross-section of sleptons is enhanced over that of the MSSM by the process pp→Z'→*, so the discovery potential for sleptons is greatly increased. The flavor and charge information in the resulting decay, →l+LSP, provides a useful handle on the identity of the LSP. With the help of the additional kinematical constraint of an on-shell Z', we implement a novel method to measure all of the superpartner masses involved in this channel. For certain final states with two invisible particles, one can construct kinematic observables bounded above by parent particle masses. We demonstrate how output from one such observable, mT2, can become input to a second, increasing the number of measurements one can make with a single decay chain. The method presented here represents a new class of observables which could have a much wider range of applicability.
Overexpression of type VI collagen in neoplastic lung tissues

Type VI collagen (COL6), an extracellular matrix protein, is important in maintaining the integrity of lung tissue. An increase in COL6 mRNA and protein deposition was found in the lungs of patients with pulmonary fibrosis, a chronic inflammatory condition with a strong association with lung cancer. In the present study, we demonstrated overexpres- sion of COL6 in the lungs of non-small cell lung cancers. We hypothesized that excessive COL6 in the lung interstitium may exert stimulatory effects on the adjacent cells. In vitro stimulation of monocytes with COL6 resulted in the produc- tion of IL-23, which may promote tumor development in an environment of IL-23-mediated lung inflammation, where tissue modeling occurs concurrently with excessive COL6 production. In addition, COL6 was capable of stimulating signaling pathways that activate focal adhesion kinase and extracellular signal-regulated kinase 1/2 in lung epithelial cells, which may also facilitate the development of lung neoplasms. Taken together, our data suggest the potential role of COL6 in promoting lung neoplasia in diseased lungs where COL6 is overexpressed.
A FACILE SYNTHESIS OF FLUORINATED 4-HYDROXYCOUMARINS

Abstract Fluorinated 4-hydroxycoumarins were prepared from readily available fluorinated phenols via a AlCl3 catalyzed Friedel-Crafts ring closure and followed by sequential one pot decarboxylation and deacetylation with 90% H2SO4.
An exceptionally brief synthesis of eupolauramine

Abstract A three-step synthesis of the azaphenanthrene alkaloid eupoulauramine ( 1 ) has been achieved from 3-bromopyridine. The key step in the synthesis was a one-pot conversion of 4 to O -demethyleupolauramine ( 9 ) via an intramolecular S RN 1 reaction followed in situ stilbene photocyclization. Methylation by the procedure of Weinreb gave the natural product.
Image segmentation and classification based on a 2D distributed hidden Markov model

In this paper, we propose a two-dimensional distributed hidden Markovmodel (2D-DHMM), where dependency of the state transition probability on any state is allowed as long as causality is preserved. The proposed 2D-DHMM model is result of a novel solution to a more general non-causal two-dimensional hidden Markovmodel (2D-HMM) that we proposed. Our proposed models can capture, for example, dependency among diagonal states, which can be critical in many image processing applications, for example, image segmentation. A new sets of basic image patterns are designed to enrich the variability of states, which in return largely improves the accuracy of state estimations and segmentation performance. We provide three algorithms for the training and classification of our proposed model. A new Expectation-Maximization (EM) algorithm suitable for estimation of the new model is derived, where a novel General Forward-Backward (GFB) algorithm is proposed for recursive estimation of the model parameters. A new conditional independent subset-state sequence structure decomposition of state sequences is proposed for the 2D Viterbi algorithm. Application to aerial image segmentation shows the superiority of our model compared to the existing models.
Irrigation and Global Water Outlook

While the earth's renewable water resources are finite, the earth's population continues to increase and requires more and more water for municipal, industrial, agricultural, environmental, recreational and other needs. Water resources must be better managed on a local, regional, national, and international scale. This includes providing more storage of water during times of water surplus, minimizing water losses, increasing food production per unit of water, transferring water to uses with higher socio-economic returns, and reusing wastewater. Sewage effluent often already is indirectly used, but water reuse in the future must be better planned as sewage flows increase, the public health and surface water quality need to be protected, and edible crops need to be irrigated. Planned water reuse requires adequate treatment so as to meet the quality requirements of the intended reuse. Agricultural and urban irrigation will play an important role in water reuse, especially in dry climates.
Adrenal steroidogenesis in "low renin" or hyporeninemic hypertension.

Abstract Suppressed plasma renin activity (PRA) and volume dependent hypertension have been associated with adrenocortical structural abnormalities, excessive deoxycorticosterone, 18-hydroxydeoxycorticosterone (18-OH-DOC) hypersecretion or non-suppressible aldosterone secretion and may be observed in patients thought to have “essential” hypertension. Dale and Melby (1973) encountered an additional alteration in steroid metabolism in two such patients while studying steroidogenesis in vitro by their sectioned adrenals. Conversion of labeled 18-OH-DOC to a new structure 16α,18-dihydroxydeoxycorticosterone was demonstrated to be greatly accelerated by the adrenal tissue in these patients as compared to normal adrenal tissue (70–80% vs 15% conversion). Hypersecretion of 16α,18-dihydroxy-deoxycorticosterone occurred in each. This steroid exerted no effect on sodium metabolism in adrenalectomized rats and in the toad bladder assay, but markedly enhanced activity of subthreshold doses of aldosterone in reducing sodium excretion in urine of adrenalectomized rats. We have concluded that excessive 16α,18-dihydroxydeoxycorticosterone secretion may be important in the genesis of suppressed renin in some patients with hypertension because of the unique activity of this steroid which appears to function as a cooperative or positive allosteric effector of aldosterone.
Infrared speckle imaging : data reduction with application to binary stars

The extended Knox-Thompson reduction scheme currently in use at Kitt Peak National Observatory and Steward Observatory for the reduction of infrared speckle interferometry is described in detail. Applications of this algorithm and the less computationally intensive shift-and-add analysis to both simulated and real binary star data is presented demonstrating that the latter may be successfully used for image reconstruction by using a separately measured point source. The performance of both techniques is shown to improve by application of an iterative deconvolution algorithm to apply a priori image constraints without degradation of photometric information.
Conventional and Stuffed Bergman-Type Phases in the Na–Au–T (T = Ga, Ge, Sn) Systems: Syntheses, Structures, Coloring of Cluster Centers, and Fermi Sphere–Brillouin Zone Interactions

Bergman-type phases in the Na–Au–T (T = Ga, Ge, and Sn) systems were synthesized by solid-state means and structurally characterized by single-crystal X-ray diffraction studies. Two structurally related (1/1) Bergman phases were found in the Na–Au–Ga system: (a) a conventional Bergman-type (CB) structure, Na26AuxGa54–x, which features empty innermost icosahedra, as refined with x = 18.1 (3), Im3, a = 14.512(2) A, and Z = 2; (b) a stuffed Bergman-type (SB) structure, Na26AuyGa55–y, which contains Ga-centered innermost icosahedra, as refined with y = 36.0 (1), Im3, a = 14.597(2) A, and Z = 2. Although these two subtypes have considerable phase widths along with respective tie lines at Na ≈ 32.5 and 32.1 atom %, they do not merge into a continuous solid solution. Rather, a quasicrystalline phase close to the Au-poor CB phase and an orthorhombic derivative near the Au-rich SB phase lie between them. In contrast, only Au-rich SB phases exist in the Ge and Sn systems, in which the innermost icosahedra are cen...
Dense Periodic Packings of Tetrahedra with Small Repeating Units

We present a one-parameter family of periodic packings of regular tetrahedra, with the packing fraction 100/117≈0.8547, that are simple in the sense that they are transitive and their repeating units involve only four tetrahedra. The construction of the packings was inspired from results of a numerical search that yielded a similar packing. We present an analytic construction of the packings and a description of their properties. We also present a transitive packing with a repeating unit of two tetrahedra and a packing fraction $\frac{139+40\sqrt{10}}{369}\approx0.7194$.
Generation and intramolecular cationic cyclizations of N-tosylimines derived from enolizable aldehydes

Abstract Boron trifluoride etherate promotes both in situ formation of N-tosyliminium complexes from olefinic enolizable aldehydes and N-sulfinyl-p-toluenesulfonamide, and subsequent intramolecular electrophilic cyclization to afford homoallylic amines.
Lower Bounds on Streaming Algorithms for Approximating the Length of the Longest Increasing Subsequence

We show that any deterministic streaming algorithm that makes a constant number of passes over the input and gives a constant factor approximation of the length of the longest increasing subsequence in a sequence of length $n$ must use space $\Omega(\sqrt{n})$. This proves a conjecture made by Gopalan et al. [Proceedings of the 18th Annual ACM-SIAM Symposium on Discrete Algorithms, 2007, pp. 318-327] who proved a matching upper bound. Our results yield asymptotically tight lower bounds for all approximation factors, thus resolving the main open problem from their paper. Our proof is based on analyzing a related communication problem and proving a direct sum type property for it.
Testing hypotheses about the common mean of two normal populations

Two simple tests which allow for unequal sample sizes are considered for testing hypothesis for the common mean of two normal populations. The first test is an exact test of size a based on two available t-statistics based on single samples made exact through random allocation of α among the two available t-tests. The test statistic of the second test is a weighted average of two available t-statistics with random weights. It is shown that the first test is more efficient than the available two t-tests with respect to Bahadur asymptotic relative efficiency. It is also shown that the null distribution of the test statistic in the second test, which is similar to the one based on the normalized Graybill-Deal test statistic, converges to a standard normal distribution. Finally, we compare the small sample properties of these tests, those given in Zhou and Mat hew (1993), and some tests given in Cohen and Sackrowitz (1984) in a simulation study. In this study, we find that the second test performs better than...
Contributors to Human Errors and Breaches in National Security Applications

Los Alamos National Laboratory has recognized that security infractions are often the consequence of various types of human errors (e.g., mistakes, lapses, slips) and/or breaches (i.e., deliberate deviations from policies or required procedures with no intention to bring about an adverse security consequence) and therefore has established an error reduction program based in part on the techniques used to mitigate hazard and accident potentials. One cornerstone of this program, definition of the situational and personal factors that increase the likelihood of employee errors and breaches, is detailed here. This information can be used retrospectively (as in accident investigations) to support and guide inquiries into security incidents or prospectively (as in hazard assessments) to guide efforts to reduce the likelihood of error/incident occurrence. Both approaches provide the foundation for targeted interventions to reduce the influence of these factors and for the formation of subsequent “lessons learned...
Enantioselective Synthesis of Diversely Substituted Quaternary 1,4-Benzodiazepin-2-ones and 1,4-Benzodiazepine-2,5-diones

Benzodiazepines are privileged scaffolds in medicinal chemistry, but enantiopure examples containing quaternary stereogenic centers are extremely rare. We demonstrate that installation of the di(p-anisyl)methyl (DAM) group at N1 of 1,4-benzodiazepin-2-ones and 1,4-benzodiazepine-2,5-diones derived from enantiopure proteinogenic amino acids allows retentive replacement of the C3-proton via a deprotonation/trapping protocol. A wide variety of carbon and nitrogen electrophiles function well in this reaction, providing the corresponding quaternary benzodiazepines with excellent enantioselectivity. Deprotonation/trapping experiments on a pair of diastereomeric 1,4-benzodiazepine-2,5-diones provide evidence for a key role of conformational chirality in these enantioselective reactions. Acidic removal of the DAM group is fast and high-yielding and can be performed selectively in the presence of a N-Boc indole. Thus the synthesis of quaternary benzodiazepines with diverse N1 functionality can now be accomplished.
A Representation of the Euclidean Group by Spin Groups, and Spatial Kinematics Mappings

A new derivation of the spin and biquaternion representation of the Euclidean group is presented. The derivation is based upon the even Clifford algebra representation of the orientation preserving orthogonal automorphisms of nondegenerate orthogonal spaces, also called spin representation. Embedding the degenerate orthogonal space IR1,0,3 into the nondegenerate orthogonal space IR1,4 , and imposing certain conditions on the orthogonal automorphisms of IR1,4 , one obtains a subgroup of the spin group. The action of this subgroup, on a subspace of IR1,4 , is isomorphic to IR1,0,3 , is precisely a Euclidean motion. The conditions imposed on the orthogonal automorphisms of IR1,4 lead to the biquaternion representation. Furthermore, the invariants of the representations are easily obtained. The derivation also allows the spin representation to be related to the action of the representation over an element of a three-dimensional vector space proposed by Porteous, and used by Selig. As a byproduct, the derivation provides an insightful interpretation of the dual unit used in both the spin representation and the biquaternion representation.
Stock-Based Compensation and CEO (Dis)Incentives

The use of stock-based compensation as a solution to agency problems between shareholders and managers has increased dramatically since the early 1990s. We show that in a dynamic rational expectations model with asymmetric information, stock-based compensation not only induces managers to exert costly effort, but also induces them to conceal bad news about future growth options and to choose suboptimal investment policies to support the pretense. This leads to a severe overvaluation and a subsequent crash in the stock price. Our model produces many predictions that are consistent with the empirical evidence and are relevant to understanding the current crisis.
Next-to-leading order parton model calculations in the massless Schwinger model

Abstract We carry out next-to-leading order (NLO) parton model calculations for the standard hard “QCD” processes in the massless Schwinger model. The asymptotic expansion of the exact result for the deep inelastic cross-section is used to infer the NLO distribution function. These distribution functions are then used to calculate the NLO Drell-Yan parton model cross-section and it is found to agree with the corresponding term in the expansion of the exact result for the Drell-Yan cross-section. Finally, by using the bosonization formula and the exact solutions we study the interference betweem different partonic processes.
Representations of Invariant Manifolds for Applications in Three-Body Systems

The lunar L1 and L2 libration points have been proposed as gateways granting inexpensive access to interplanetary space. To date, individual transfers between three-body systems have been determined. The methodology to solve the problem for arbitrary three-body systems and entire families of orbits is currently being studied. This paper presents an initial approach to solve the general problem for single and multiple impulse transfers. Two different methods of representing and storing the invariant manifold data are developed. Some particular solutions are presented for two types of transfer problems, though the emphasis is on developing the methodology for solving the general problem.
Cosmological Simulations with Scale-Free Initial Conditions I: Adiabatic Hydrodynamics

We analyze hierarchical structure formation based on scale-free initial conditions in an Einstein-de Sitter universe, including a baryonic component with Ωbary = 0.05. We present three independent, smoothed particle hydrodynamics (SPH) simulations, performed at two resolutions (323 and 643 dark matter and baryonic particles) and with two different SPH codes (TreeSPH and P3MSPH). Each simulation is based on identical initial conditions, which consist of Gaussian-distributed initial density fluctuations that have a power spectrum P(k) ∝ k-1. The baryonic material is modeled as an ideal gas subject only to shock heating and adiabatic heating and cooling; radiative cooling and photoionization heating are not included. The evolution is expected to be self-similar in time, and under certain restrictions we identify the expected scalings for many properties of the distribution of collapsed objects in all three realizations. The distributions of dark matter masses, baryon masses, and mass- and emission-weighted temperatures scale quite reliably. However, the density estimates in the central regions of these structures are determined by the degree of numerical resolution. As a result, mean gas densities and Bremsstrahlung luminosities obey the expected scalings only when calculated within a limited dynamic range in density contrast. The temperatures and luminosities of the groups show tight correlations with the baryon masses, which we find can be well represented by power laws. The Press-Schechter (PS) approximation predicts the distribution of group dark matter and baryon masses fairly well, though it tends to overestimate the baryon masses. Combining the PS mass distribution with the measured relations for T(M) and L(M) predicts the temperature and luminosity distributions fairly accurately, though there are some discrepancies at high temperatures/luminosities. In general the three simulations agree well for the properties of resolved groups, where a group is considered resolved if it contains more than 32 particles.
Constraining cosmological models by the cluster mass function

We present a comparison between two observational mass functions and three theoretical mass functions for eight cosmological models suggested by the data from the recently completed BOOMERANG-98 and MAXIMA-1 cosmic microwave background (CMB) anisotropy experiments as well as from peculiar velocities (PVs) and Type Ia supernova (SN) observations. The cosmological models have been proposed as the best-fit models by several groups. We show that no model is in agreement with the abundances of X-ray clusters at ~1014.7 h-1 M☉. On the other hand, we find that the BOOM + MAX + COBE: I, Refined Concordance, and ΛMDM models are in a good agreement with the abundances of optical clusters. The P11 model and especially the Concordance model predict slightly lower abundances than observed at ~1014.6 h-1 M☉. The BOOM + MAX + COBE: II and PV + CMB + SN models predict slightly higher abundances than observed at ~1014.9 h-1 M☉. The nonflat MAXIMA-1 is in a fatal conflict with the observational cluster abundances and can be safely ruled out.
Balanced Graph Partitioning

We consider the problem of partitioning a graph into k components of roughly equal size while minimizing the capacity of the edges between different components of the cut. In particular we require that for a parameter ν ≥ 1, no component contains more than ν · n/k of the graph vertices.For k = 2 and ν = 1 this problem is equivalent to the well-known Minimum Bisection problem for which an approximation algorithm with a polylogarithmic approximation guarantee has been presented in [FK]. For arbitrary k and ν ≥ 2 a bicriteria approximation ratio of O(log n) was obtained by Even et al. [ENRS1] using the spreading metrics technique.We present a bicriteria approximation algorithm that for any constant ν > 1 runs in polynomial time and guarantees an approximation ratio of O(log1.5n) (for a precise statement of the main result see Theorem 6). For ν = 1 and k ≥ 3 we show that no polynomial time approximation algorithm can guarantee a finite approximation ratio unless P = NP.
Surface-Shadow Generation For The Preparation Of Synthetic Imagery

Shadows can add significant edge and surface detail to imagery and thus substantially increase the performance of automated correlation guidance systems. A shadow-generation algorithm was implemented to increase the accuracy of synthetic imagery used to simulate visible, near-infrared, and far-infrared sensors. Initially, a data base was established in which all surfaces were represented by a list of vertices and material codes and arranged according to a scheme of a priori masking priority. Each surface was then clipped against updated clipping polygons representing the silhouette of all previous surfaces that had higher masking priorities as viewed from the position of the light source. The resulting hidden surface was inserted into the data base and flagged as a shadow for gray-scale prediction by the appropriate sensor model. Because each surface is compared to a union of polygons rather than to individual surfaces, this algorithm is computationally efficient for use with large data bases.
Restructuring for large data bases: three levels of abstraction

The development of a powerful restructuring function involves two important components - the unambiguous specification of the restructuring operations and the realization of these operations in a software system. We direct our efforts to the first component in the belief that a precise specification will provide a firm foundation for restructuring algorithms and implementations. This paper defines completely the semantics of the restructuring of tree structured data bases.The delineation of the restructuring function is accomplished by formulating three different levels of abstraction, with each level of abstraction representing successively more detailed semantics of the function.At the first level of abstraction, the schema modification, three types are identified: naming, combining and relating, and are further divided into eight schema operations. The second level of abstraction, the instance operations, constitutes the transformations on the data instances. They are divided into group operations such as replication, factoring, union and group relation operations such as collapsing, refinement, fusion etc. The final level, the item values operations, includes the actual item operations such as copy value, delete value, or create a null value.
Self‐Discharge in Acid‐Starved Lead‐Acid Batteries

A lead-acid battery stored in an acid-starved condition, rather than in a totally flooded state, shows a well-behaved and predictable decline in open-circuit voltage with time. The voltage-time curves of such batteries can be used to determine the rates of the predominant self-discharge reactions and to study the reaction mechanisms. An abrupt change in the slope of the curve indicates a change in the dominant self-discharge process. Acid-starved automotive (SLI) batteries with antimonial-lead grids show a slope change at 1.85 V/cell. This apparently corresponds to a change in the grid corrosion mechanism. Measurements of gas evolution from these SLI batteries show that the rate of hydrogen evolution is dependent on the acid concentration whereas the rate of evolution of carbon dioxide is independent of acid concentration. Oxygen reacts rapidly at the negative plate. 26 refs.
Pd(II)-catalyzed hydroxyl-directed C-H olefination enabled by monoprotected amino acid ligands.

A novel Pd(II)-catalyzed ortho-C–H olefination protocol has been developed using spatially remote, unprotected tertiary, secondary, and primary alcohols as the directing groups. Mono-N-protected amino acid ligands were found to promote the reaction, and an array of olefin coupling partners could be used. When electron-deficient alkenes were used, the resulting olefinated intermediates underwent subsequent Pd(II)-catalyzed oxidative intramolecular cyclization to give the corresponding pyran products, which could be converted into ortho-alkylated alcohols under hydrogenolysis conditions. The mechanistic details of the oxidative cyclization step are discussed and situated in the context of the overall catalytic cycle.
Ginsenosides from American ginseng: Chemical and pharmacological diversity

Ginseng occupies a prominent position in the list of best-selling natural products in the world. Compared to the long history of use and widespread research on Asian ginseng, the study of American ginseng is relatively limited. In the past decade, some promising advances have been achieved in understanding the chemistry, pharmacology and structure-function relationship of American ginseng. To date, there is no systematic review of American ginseng. In this review, the different structures of the ginsenosides in American ginseng are described, including naturally occurring compounds and those resulting from steaming or biotransformation. Preclinical and clinical studies published in the past decade are also discussed. Highlighted are the chemical and pharmacological diversity and potential structural-activity relationship of ginsenosides. The goal is that this article is a useful reference to chemists and biologists researching American ginseng, and will open the door to agents in drug discovery.
Normative Creativity and Global Legal Pluralism: Reflections on the Democratic Critique of Transnational Law

The globalization process has changed the nature of the “social.” Social interactions have become much more varied and flexible—transgressing traditional political and cultural boundaries (and expectations). The emergence of new forms of global law, which evolve and operate across these traditional lines, is a major aspect of globalization. This expanding network of transnational “legalities” is not based on a coherent set of normative or institutional hierarchies. Rather, it represents a highly pluralistic mixture of legal regimes, with variable organizational and thematic structures: from state-oriented systems—such as the dispute settlement system of the WTO, or the adjudicative system of the Law of the Sea Convention—to hybrid or private regimes. The latter category includes, for example, the expanding field of technical standardization, the new governance structure of the Internet, and the field of transnational arbitration.
Chip-based frequency comb with microwave repetition rate

A silicon-chip microcomb accessing the important microwave-rate FSR range is reported. A broadband microcomb with rep rate 33GHz and span 66THz is shown with pump power of 200mW. Microcombs with rep rates ranging from 132GHz to 2.6GHz are demonstrated.
Analysis of single erythrocytes by injection-based capillary isoelectric focusing with laser-induced native fluorescence detection

Abstract A modified version of capillary isoelectric focusing (cIEF) was developed to separate hemoglobin variants contained within single human erythrocytes. Laser-induced native fluorescence with 275 nm excitation was used to detect the separated hemoglobins. In this method, baseline fluctuations were minimized and detection sensitivity was improved by using dilute solutions of anolyte, catholyte, and carrier ampholytes (with methylcellulose). Since electrosmotic flow was used for mobilization of the focused bands, separation and detection were integrated into a single step. The capillary was first filled with only ampholyte solution, and the cell (or standard) was injected as in capillary zone electrophoresis. The ∼90 fl injection volume for individual cells is 7×104 times lower than those previously reported. Adult (normal and elevated A1), sickle (heterozygous), and fetal erythrocytes were analyzed, with the amounts of hemoglobins A0, A1c, S and F determined. The pH gradient for cIEF was linear (r2 = 0.9984), which allowed tentative identification of Hb Fac. Variants differing by as little as 0.025 pI units were resolved.
The Width-Volume Inequality

We prove that a bounded open set U in $${\mathbb{R}}^n$$ has k-width less than C(n) Volume(U) k/n . Using this estimate, we give lower bounds for the k-dilation of degree 1 maps between certain domains in $${\mathbb{R}}^n$$ . In particular, we estimate the smallest (n – 1)-dilation of any degree 1 map between two n-dimensional rectangles. For any pair of rectangles, our estimate is accurate up to a dimensional constant C(n). We give examples in which the (n – 1)-dilation of the linear map is bigger than the optimal value by an arbitrarily large factor.
Stability trends and fragmentation patterns of gaseous yttrium oxide clusters studied by fast atom bombardment tandem mass spectrometry

Abstract The fragmentation patterns of yttrium oxide cluster species YO+, Y2O2+, Y2O3+, Y3O4+, Y4O6+, Y5O7+, Y6O8+ and Y7O10+ were investigated at collision energies 30–110 and 170 eV by fast atom bombardment tandem mass spectrometry. The collision activated dissociation (CAD) spectra obtained revealed higher thermodynamic stability for the clusters of general formula YαO(3α−1)/2+, where a is an odd number (e.g. YO+, Y3O4+, Y5O7+, Y7O10+) which are also the preferred CAD products for all oxide clusters studied. These most stable oxides are constituted by trivalent yttrium only whereas those containing formally tetravalent yttrium YaO3a/2+, (where a is even) e.g. Y2O3+ and Y4O6+, are extremely unstable. The clusters YaO(3a−2)/2+, (where a is even) containing divalent yttrium, e.g. Y2O2+ and Y6O8+, have considerable stability but their CAD products are again the thermodynamic products YaO(3a−1)/2+. Electronic structures appear to have overriding significance in determining the thermo- dynamic stabilities of the oxide cluster species.
Strong Comparative Statics of Equilibria

Some results in the monotone comparative statics literature tell us that if a parameter increases, some old equilibria are smaller than some new equilibria. We give a sufficient condition such that at a new parameter value every old equilibrium is smaller than every new equilibrium. We also adapt a standard algorithm to compute a minimal such newer parameter value and apply this algorithm to a game of network externalities. Our results are independent of a theory of equilibrium selection and are valid for games of strategic complementarities.
Wire-reference configurations in vehicle lateral control

Lateral control is an essential function for all forms of individual automated ground transport. Here two aspects of such control--the magnetic field distributions associated with a guideway-based, wire-reference configuration, and the associated vehicle-based sensors--are reviewed. Two wire-reference schemes have thus far been suggested. In the first, the amplitude characteristics of the magnetic field are employed to obtain the lateral control signal. In this paper, a theoretical analysis and detailed field measurements are used to define both "ideal" characteristics and those which would be encountered in a realistic operating environment. The resulting problems, which involve amplitude distortions of the field due to the proximity of steel-reinforcing materials, are defined, and their effects on vehicle control--poor tracking and passenger discomfort--are discussed. In the second approach, the lateral control signal is primarily dependent on the phase characteristics of the magnetic field. A theoretical analysis and a corresponding experimental field study, which are discussed herein, indicated that the problems associated with the first approach were largely overcome, as evidenced by successful full-scale tests of an automatically steered vehicle.
Palladium-Catalyzed N-Arylation of 2-Aminothiazoles

A method for the Pd-catalyzed coupling of 2-aminothiazole derivatives with aryl bromides and triflates is described. Significantly, for this class of nucleophiles, the coupling exhibits a broad substrate scope and proceeds with a reasonable catalyst loading. Furthermore, an interesting effect of acetic acid as an additive is uncovered that facilitates catalyst activation.
Extreme multiphoton coupling in molecular systems

Compared to single-photon rates, multiphoton excitation rates of atoms and molecules are generally quite small, even at high laser intensities, at least in a 2-level system. Small multiphoton coupling strengths, large ac Stark shifts, and ionization all inhibit real population transfer between bound states. However, it has recently been shown that a 3-level system consisting of a ground state and a pair of nearly degenerate strongly coupled upper states greatly enhances the multiphoton coupling with the ground state, while also greatly reducing the ac Stark shift of the ground state. In this paper I will derive an analytic expression for the n-photon Rabi frequency, for this system, in the case of degenerate upper states, as well as an expression for the level shifts induced in the case of nondegenerate upper states. Numerical calculations based on the 3-level system are presented to verify the analytic results and to show that high-order {pi} pulses can be driven at moderate field strengths. To demonstrate the feasibility of this process in a real physical system, I will present fully correlated 2-electron calculations in a model one-dimensional molecular potential, including ionization that show a 12-photon {pi} pulse driven with near-infrared photons. In other words, amore » single excited state 18.6 eV above the ground state can be populated with over 90% efficiency with little ionization while the ground state is almost completely depopulated. Besides the possibility of producing an amplifying medium in the vacuum ultraviolet, this 3-level configuration may open the door to other strong field effects previously restricted to single-photon interactions, such as adiabatic passage and inner-shell ionization.« less
A formula for damping interarea oscillations with generator redispatch

We derive a new formula for the sensitivity of electromechanical oscillation damping with respect to generator redispatch. The formula could lead to some combination of observations, computations and heuristics to more effectively damp interarea oscillations.
Effectiveness of Active Constrained Layer Damping Treatments in Attenuating Resonant Oscillations

This paper highlights the importance of considering the piezoelectric constraining layer voltage limits when evaluating the effectiveness of an active constrained layer damping treatment in attenuating resonant vibration. It is seen that when position feedback is used, intermediate viscoelastic layer stiffness values are always optimal, and maximum control gains and possible vibration attenuation progressively decrease with increasing excitation levels. On the other hand, with velocity feedback, the optimal viscoelastic layer stiffness is dependent on the excitation level. For low excitation force amplitudes, stiff viscoelastic layers are most effective and very large velocity feedback gains are permissible (producing substantial vibration attenuation without exceeding piezoelectric layer voltage limits). However, for higher excitation force levels, stiff viscoelastic layers result in excess voltages even at very small velocity feedback gains, and are unable to provide any vibration attenuation. In such a case, intermediate viscoelastic layer stiffness values are preferable, and maximum velocity feedback gains and possible vibration attenuation progressively decrease with increasing excitation level, as in the case of position feedback.
Synthesis of Pterostilbene by Julia Olefination

Abstract A simple, E-stereoselective route for the synthesis of the biologically active compounds trans-pterostilbene and tetramethoxy stilbene from the readily available starting materials 3,5-dimethoxy benzyl alcohol and 4-hydroxy benzaldehyde was developed using Julia olefination as a key reaction. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]
Flipping the Classroom and Student Performance in Advanced Statistics: Evidence from a Quasi-Experiment

I administer a quasi-experiment using undergraduate political science majors in statistics classes to evaluate whether “flipping the classroom” (the treatment) alters students’ applied problem-solving performance and satisfaction relative to students in a traditional classroom environment (the control). I also assess whether general student characteristics such as when and where students took the prerequisite course, grade point average (GPA), and gender influence performance. I find flipping the classroom gives students statistically significant advantages in difficult, applied areas emphasized in class. Furthermore, students in the flipped classroom feel they learned more and enjoyed the course more than those in a traditional classroom. I argue students’ affective preference for a flipped classroom is important for student motivation, recollection, and future use of quantitative data analysis. Flipping the classroom entails high start-up costs, but it can merit implementing to improve both effective an...
Deoxyribozymes: Selection Design and Serendipity in the Development of DNA Catalysts†

One of the chemist’s key motivations is to explore the forefront of catalysis. In this Account, we describe our laboratory’s efforts at one such forefront: the use of DNA as a catalyst. Natural biological catalysts include both protein enzymes and RNA enzymes (ribozymes), whereas nature apparently uses DNA solely for genetic information storage. Nevertheless, the chemical similarities between RNA and DNA naturally lead to laboratory examination of DNA as a catalyst, especially because DNA is more stable than RNA and is less costly and easier to synthesize. Many catalytically active DNA sequences (deoxyribozymes, also called DNAzymes) have been identified in the laboratory by in vitro selection, in which many random DNA sequences are evaluated in parallel to find those rare sequences that have a desired functional ability. Since 2001, our research group has pursued new deoxyribozymes for various chemical reactions. We consider DNA simply as a large biopolymer that can adopt intricate three-dimensional stru...
New heterocycles from tetrazines and oxadiazoles

The reactivity of 3,4-diamino-1,2,5-oxadiazole () toward nucleophilic substitution of 3,6-bis(3,5-dimethylpyrazol-1yl)-1,2,4,5-tetrazine () was studied. A new class of high nitrogen heterocyclic systems was prepared. It was determined that 3,4-diamino-1,2,5-oxadiazole did not display the required nucleophilicity to be reactive. However, the anion of 3,4-diamino-1,2,5-oxadiazole, prepared by treatment with strong base, was sufficiently reactive to act as a nucleophile. J. Heterocyclic Chem., (2009).
Crystal of Semiconducting Quantum Dots Built on Covalently Bonded T5 [In28Cd6S54]-12: The Largest Supertetrahedral Cluster in Solid State

Periodic array of nanoparticles is essential for practical applications in optical devices. Periodic dot arrays often exhibit very interesting collective phenomenon. We report a periodic crystal of InCdS pseudo-T5 nanocluster, the largest supertetrahedral cluster found thus far in solid state. Each InCdS cluster behaves like a nanoparticle with the same size. Unlike the array of colloidal dots in which the dot-dot separation is large ( approximately 5 nm), the neighboring T5 clusters in [In28Cd6S54].[(CH3)4N]12[(HSCH2COOH)2]3.5 crystal form a natural point contact by sharing covalently bonded S atoms. Both experimental and theoretical studies show that this crystal is a semiconductor with a band gap of 3.0 eV.
On some ternary operations in knot theory

We introduce a way to color the regions of a classical knot diagram using ternary operations, so that the number of colorings is a knot invariant. By choosing appropriate substitutions in the algebras that we assign to diagrams, one obtains the relations from the knot group, and from the core group. Using the ternary operator approach, we generalize the Dehn presentation of the knot group to extra loops, and a similar presentation for the core group to the variety of Moufang loops.
Recent improvements in MADCAP

MADCAP is a programming language admitting subscripts, superscripts and certain forms of displayed formulas. The basic implementation of this language was described in a previous paper [MADCAP: A scientific compiler for a displayed formula textbook language, Comm. ACM 4 (Jan. 61), 31-36]. This paper discusses recent improvements in the language in three areas: complex display, logical control, and subprogramming. In the area of complex display, the most prominent improvements are a notation for integration and for the binomial coefficients. In the area of logical control the chief new feature is a notation for variably nested looping. The discussion of subprogramming is focused on MADCAP's notation for and use of “procedures.”
Detection and avoidance of main rotor hub moment limits on rotorcraft

There is interest in developing carefree maneuvering capability on future rotorcraft. This has driven the need for advanced algorithms that predict the onset of structural limits and cue the pilot using tactile feedback. A new method is presented for the detection and avoidance of static load limits on the main rotor hub. An algorithm was developed that uses linear models to estimate constraints on longitudinal and lateral cyclic stick positions that ensure the transient response of hub moments remain bounded within prescribed limits. The system was tested using a high-fidelity nonlinear simulation of a UH-60A helicopter (GENHEL). The system was shown to be successful in simultaneously constraining stick travel in both lateral and longitudinal axes to prevent hub moment limit violations. The most critical conditions occurred during control reversals, at which point the system effectively imposed rate limits on the stick motion. The algorithm was shown to be robust to changes in aircraft weight and c.g. location.
A Fourth-Order Accurate Method for the Incompressible Navier-Stokes Equations on Overlapping Grids

A method is described to solve the time-dependent incompressible Navier-Stokes equations with finite differences on curvilinear overlapping grids in two or three space dimensions. The scheme is fourth-order accurate in space and uses the momentum equations for the velocity coupled to a Poisson equation for the pressure. The boundary condition for the pressure is taken as � � u = 0. Extra numerical boundary conditions are chosen to make the scheme accurate and stable. The velocity is advanced explicitly in time; any standard time stepping scheme such as Runge-Kutta can be used. The Poisson equation is solved using direct or iterative sparse matrix solvers or by the multigrid algorithm. Computational results in two and three space dimensions are given.
A validation of the OSI session layer protocol

Abstract The session layer of the ISO Open-System-Interconnection (OSI) Protocol has been validated using an automated state-exploration technique. The validation methodology is described, together with the particular way it has been applied to the session layer. A number of the protocol errors found is presented.
Noise and distortion characteristics of cryogenic vertical cavity lasers

The noise and linearity properties of oxide-apertured vertical cavity lasers optimised for low-power cryogenic operation is reported. The relative intensity noise is lower than -140 dB/Hz and the spur-free dynamic range is between 90-100 dB-Hz/sup 2/3/.
Testing the Disk Regulation Paradigm with Spitzer Observations. I. Rotation Periods of Pre-Main-Sequence Stars in the IC 348 Cluster

We present 105 stellar rotation periods in the young cluster IC 348, 75 of which are new detections, increasing the total number of known periods in this cluster to 143. The period distribution resembles that seen in the heart of the Orion Nebula cluster by Herbst and colleagues. Stars estimated to be less massive than 0.25 M☉ show a unimodal distribution of fast rotators (P ~ 1-2 days) and a tail of slower rotators, while stars estimated to be more massive than 0.25 M☉ show a bimodal distribution with peaks at ~2 and ~8 days. We combine all published rotation periods in IC 348 with Spitzer mid-IR (3.6, 4.5, 5.8, and 8.0 μm) photometry, an unprecedentedly efficient and reliable disk indicator, in order to test the disk-braking paradigm. We find no evidence that the tail of slow rotators in low-mass stars or the long-period peak in high-mass stars are preferentially populated by objects with disks as might be expected based on the current disk-braking model. We find some indication that the disk fraction decreases significantly for stars with very short periods (P 1.5 days), which is the only feature of our sample that could potentially be interpreted as evidence for disk braking. It has been proposed that the observational signatures of disk braking might be significantly masked by the intrinsic breadth of the initial period distribution. We argue that more rigorous modeling of angular momentum evolution and a quantitative analysis of the observational data are required before the disk-braking model can be regarded as inconsistent with observations.
A new wheel control system for the omnidirectional HERMIES-III robot

We have designed, built, and tested a new wheel control system for the HERMIES-III robot. HERMIES-III is a large mobile robot with omnidirectional steering that is designed for human scale experiments. During each cycle (at 20 Hz), the wheel control system moves the robot toward a goal and calculates the current position of the robot. The system has seven modes for moving to a goal and the goal may be changed during motion of the robot.