cssi/SciSciGPT-SciSciNet huggingface dataset:
Far-ultraviolet spectral images of comet Halley from sounding rockets

Far-ultraviolet images of comet Halley obtained from sounding rockets launched from White Sands Missile Range, New Mexico, on 24 February and 13 March, 1986, are presented. Direct electrographic images of the hydrogen coma of the comet were obtained at the Lyman-alpha wavelength along with objective spectra containing images of the coma at the oxygen, carbon, and sulfur resonance multiplets. Analysis of the Lyman-alpha images yields hydrogen atom production rates of 1.9 x 10 to the 30th/s and 1.4 x 120 to the 30th/s for the two observations. Images of oxygen, carbon, and sulfur emissions obtained with the objective grating spectrograph are presented for the first set of observations and preliminary production rates are derived for these elements.
Picosecond Time Resolved Hard X-Ray Diffraction from Laser Heated Metallic Crystals

We report the development of a novel hard X-ray diffraction system with picosecond time resolution. Picosecond X-ray pulses are produced by excitation of an X-ray diode with picosecond ultraviolet light pulses at a repetition rate of 300 Hz. The X-ray pulses are synchronized to the optical pulses with picosecond accuracy. The system has been utilized in picosecond time resolved X-ray diffraction of laser pulse heated gold and platinum single crystals.
Combinatorial Hodge Theory and Signature Operator.

This paper represents an detailed version of our paper [12] presented at the Hawaii Conference on the Geometry of the Laplace Operator, March 1979. In this paper we present the solution to the following problem posed by Singer in [8], w 4, concerning elliptical operators on PL-maifolds: "If M is a PL-manifold, the L-polynomials are still well defined (Thom [13]) from which one can still define the rational Pontrjagin classes. The Hirzebruch signature theorem still holds. Is there an associated elliptic operator (as in the smooth case) whose index is the signature? On what spaces does it operate? Does it have a symbol and where does the symbol lie?"
High-order aberrations and preoperative associated factors.

. Purpose: The purpose of this study was to determine which preoperative factors are associated with the presence of high-order aberrations. Methods: A total of 93 eyes of 52 subjects were evaluated preoperatively between 1 January and 31 March 2003, using a Hartmann−Shack-based aberrometer. Age, gender, cycloplegic refraction, pupil size, keratometry readings, anterior chamber depth, white-to-white tests, intraocular pressure and basic secretion tests were evaluated. Results: Factors associated with high-order aberrations included age ≥ 40 years (mean 4.39 ± 2.95 µm; p = 0.03, Mann–Whitney test), higher keratometry values (44.96 ± 1.57 D) (r = 0.447, p < 0.001, Spearman's correlation coefficient), higher degrees of myopia (≥ − 6.1 D) (p < 0.001, Kruskall−Wallis test) and increasing pupil size (p < 0.001, anova). Other factors including anterior chamber depth, white-to-white results, intraocular pressure and basic secretion test results did not correlate with the presence of high-order aberrations preoperatively. Conclusions: Ocular wavefront aberrations varied greatly from subject to subject. Treatment should be customized for each laser based on patient characteristics in order to ensure the optimal treatment profile for the aberration.
Magma mixing at Nisyros volcano, as inferred from incompatible trace-element systematics

Abstract Rocks of the calc-alkaline volcanic complex of Nisyros, at the eastern end of the Quaternary South Aegean volcanic arc, range in composition from basaltic andesite to rhyodacite. Major- and compatible trace-element systematics are dominated by crystal fractionation, involving olivine, clinopyroxene, plagioclase, and magnetite in the mafic to intermediate compositional range and plagioclase, clinopyroxene, hypersthene, Fe-Ti oxides, and apatite in the intermediate to silicic range, although there is a marked paucity of lavas with 60–66 wt.% SiO 2 . The occurrence of andesitic inclusions in pre- and post-caldera dacites as well as reversely zoned and/or partly resorbed phenocrysts, exotic mineralogy (e.g., forsteritic olivine), compositionally bimodal plagioclase phenocryst populations, and the observation of two distinct glass phases in melt inclusions and pumices all indicate that magma mixing processes have played a role in the petrogenesis of Nisyros. Incompatible trace-element systematics are consistent with mixing between mafic and silicic end members. Major-element binary mixing calculations between end members successfully reproduce the dacite composition. The eruptive sequence at Nisyros suggests the existence of a compositionally zoned magma chamber, in which mixing between underlying more mafic magma and overlying rhyodacitic melt result in the formation of dacitic magmas. Inherent mineral assemblages in basaltic andesites indicate that mixing between mafic liquids and between mafic and more silicic liquids played also a role in their petrogenesis.
Drought Tolerance Aspects in Pearl Millet

Different indices for selection of lines grown under low and high water levels were examined from both theoretical and practical standpoints. Pearl millet (Pennisetum americanum (L.) K. Schum) was planted under a sprinkler irrigation gradient in 1983 and 1984. Equations were developed for drought tolerance for both yield and forage production. Correlation coefficients were developed for yield and yield components. The equations showed that drought will generally result in decreased productivity of both grain and forage. Grain yield was found to be positively correlated with seed weight and with the number of seeds in the main head, and negatively correlated with plant height under low water level. Dry matter was positively correlated with tiller number.
Correlation of the Competition between Neutron Emission and Fission

Values of the ratio of the fission cross section divided by the total cross section for 3-Mev neutrons are correlated with the fission parameter $\frac{{Z}^{2}}{A}$. For compound nuclei excited 8 to 12 Mev above their ground states, the fission width ${\ensuremath{\Gamma}}_{f}$ derived from neutron- and gamma-induced fission data increases linearly with $\frac{{Z}^{2}}{A}$. The quantity $\frac{{\ensuremath{\Gamma}}_{f}}{{\ensuremath{\Gamma}}_{n}}$ is independent of energy for a particular nuclide excited between 8 and 12 Mev.
Site-directed Mutagenesis Identifies Residues Involved in Ligand Recognition in the Human A2a Adenosine Receptor

The A2a adenosine receptor is a member of the G-protein coupled receptor family, and its activation stimulates cyclic AMP production. To determine the residues which are involved in ligand binding, several residues in transmembrane domains 5-7 were individually replaced with alanine and other amino acids. The binding properties of the resultant mutant receptors were determined in transfected COS-7 cells. To study the expression levels in COS-7 cells, mutant receptors were tagged at their amino terminus with a hemagglutinin epitope, which allowed their immunological detection in the plasma membrane by the monoclonal antibody 12CA5. The functional properties of mutant receptors were determined by measuring stimulation of adenylate cyclase. Specific binding of [3H]CGS 21680 (15 nM) and [3H]XAC (4 nM), an A2a agonist and antagonist, respectively, was absent in the following Ala mutants: F182A, H250A, N253A, I274A, H278A, and S281A, although they were well expressed in the plasma membrane. The hydroxy group of Ser-277 is required for high affinity binding of agonists, but not antagonists. An N181S mutant lost affinity for adenosine agonists substituted at N6 or C-2, but not at C-5′. The mutant receptors I274A, S277A, and H278A showed full stimulation of adenylate cyclase at high concentrations of CGS 21680. The functional agonist potencies at mutant receptors that lacked radioligand binding were >30-fold less than those at the wild type receptor. His-250 appears to be a required component of a hydrophobic pocket, and H-bonding to this residue is not essential. On the other hand, replacement of His-278 with other aromatic residues was not tolerated in ligand binding. Thus, some of the residues targeted in this study may be involved in the direct interaction with ligands in the human A2a adenosine receptor. A molecular model based on the structure of rhodopsin, in which the 5′-NH in NECA is hydrogen bonded to Ser-277 and His-278, was developed in order to visualize the environment of the ligand binding site.
Limits to photonics for information

The talk will discuss some of the limits we know, and some we don't, and how these can influence what we can or should do in using photonics to help handle information.
Growth of acceleration waves in an unstrained non-linear isotropic elastic medium

Abstract A wave is taken as a singular surfaȩ across which second derivatives of the displacement vector suffer discontinuities. Use of compatibility conditions, equation of continuity and the equations of motion gives the relations between the acoustic tensor, amplitude of the discontinuity vector and the normal speed of propagation. Separability of modes and corresponding propagation speeds are then discussed. Use of compatibility conditions on the differentiated forms of the basic equations then leads to the basic equation that governs the growth of the amplitude for each mode. In an unstrained medium the shear wave, as in linear theory, does not grow; the dilatational mode may grow, depending on the elasticities. Comparison is made with known results.
Macromolecular substrate affinity for the tissue factor-factor VIIa complex is independent of scissile bond docking.

Next Section Abstract The upstream coagulation enzymes are homologous trypsin-like serine proteases that typically function in enzyme-cofactor complexes, exemplified by coagulation factor VIIa (VIIa), which is allosterically activated upon binding to its cell surface receptor tissue factor (TF). TF cooperates with VIIa to create a bimolecular recognition surface that serves as an exosite for factor X binding. This study analyzes to what extent scissile bond docking to the catalytic cleft contributes to macromolecular substrate affinity. Mutation of the P1 Arg residue in factor X to Gln prevented activation by the TF·VIIa complex but did not reduce macromolecular substrate affinity for TF·VIIa. Similarly, mutations of the S and S′ subsites in the catalytic cleft of the enzyme VIIa failed to reduce affinity for factor X, although the affinity for small chromogenic substrates and the efficiency of factor X scissile bond cleavage were reduced. Thus, docking of the activation peptide bond to the catalytic cleft of this enzyme-cofactor complex does not significantly contribute to affinity for macromolecular substrate. Rather, it appears that the creation of an extended macromolecular substrate recognition surface involving enzyme and cofactor is utilized to generate substrate specificity between the highly homologous, regulatory proteases of the coagulation cascade.
Methylation of 2’-Deoxyguanosine by a Free Radical Mechanism

The mechanistic aspects of the methylation of guanine in DNA initiated by methyl radicals that are derived from the metabolic oxidation of some chemical carcinogens remain poorly understood. In this work, we investigated the kinetics and the formation of methylated guanine products by two methods: (i) the combination of *CH3 radicals and guanine neutral radicals, G(-H)*, and (ii) the direct addition of *CH3 radicals to guanine bases. The simultaneous generation of *CH3 and dG(-H)* radicals was triggered by the competitive one-electron oxidation of dimethyl sulfoxide (DMSO) and 2'-deoxyguanosine (dG) by photochemically generated sulfate radicals in deoxygenated aqueous buffer solutions (pH 7.5). The photolysis of methylcob(III)alamin to form *CH3 radicals was used to investigate the direct addition of these radicals to guanine bases. The major end products of the radical combination reactions are the 8-methyl-dG and N2-methyl-dG products formed in a ratio of 1:0.7. In contrast, the methylation of dG by *CH3 radicals generates mostly the 8-methyl-dG adduct and only minor quantities of N2-methyl-dG (1:0.13 ratio). The methylation of the self-complementary 5'-d(AACGCGAATTCGCGTT) duplexes was achieved by the selective oxidation of the guanines with carbonate radical anions in the presence of DMSO as the precursor of *CH3 radicals. The methyl-G lesions formed were excised by the enzymatic digestion and identified by LC-MS/MS methods using uniformly 15N-labeled 8-methyl-dG and N2-methyl-dG adducts as internal standards. The ratios of 8-methyl-G/N2-methyl-G lesions derived from the combination of methyl radicals with G(-H)* radicals positioned in double-stranded DNA or that with the free nucleoside dG(-H)* radicals were found to be similar. Utilizing the photochemical method and dipropyl or dibutyl sulfoxides as sources of alkyl radicals, the corresponding 8-alkyl-dG and N2-alkyl-dG adducts were also generated in ratios similar to those obtained with DMSO.
ROC comparison of compressed images to original analog film and digital hardcopy

A receiver operating characteristic (ROC) experiment is used to compare the diagnostic performance of analog film to digital hardcopy and compressed hardcopy. The compression is done using a full-frame bit-allocation algorithm carried through on a custom designed board residing on a SUN computer bus. Image set included thirthy-one radiographs with septal lines (n=18) and/or parenchymal nodules (n=14), with six radiographs that had neither abnormality. Six radiologists viewed the image set under each modality. There is no statistically significant difference between the three modalities.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Mass storage of evoked potential data on a home microcomputer system.

Abstract A technique is described to adapt an inexpensive microcomputer (the Apple ][) to provide a low cost data storage system for a clinical signal averager. It can be easily modified to accomodate other commercially available clinical signal averagers.
Spatial modulation in cross-linked binary polymer blends

Spatial modulation means that the free energy of the composite mixture is minimized at a finite wavenumber, which defines the primary length scale, the maximum size possible, of the evolving phases. Although spatial modulation may appear in different systems in different ways and is not necessarily a thermodynamic precept, here it is expressed as a thermodynamic consequence of short-range interfacial forces pitted against long-range elastic forces. Cross-linked chains bring about new thermodynamic interactions based on their conformations and the fractal dimensions of the chain networks to which they tether and belong. Interplay among these different interactions during phase ordering brings about the spatial modulation and the spatial pattern. Here, the underlying processes are only succinctly outlined.
Bimanual coordination in natural orifice transluminal endoscopic surgery: comparing the conventional dual-channel endoscope, the R-Scope, and a novel direct-drive system.

Background The devices used for natural orifice transluminal endoscopic surgery procedures are endoscopes or inspired by endoscopic design, which makes it difficult to accomplish bimanual coordination. Objective We evaluated 3 operating systems in simulated natural orifice transluminal endoscopic surgery procedures requiring complex bimanual coordination. Design Operators were required to perform an identical bimanual task by using 3 operating systems: a dual-channel endoscope (DCE); the R-Scope, which has 2 elevators for independent movement of endoscopic instruments; and the Direct Drive Endoscopic System (DDES), which allows separation of instruments and vision, emulating more of a laparoscopic surgery paradigm. Setting A bench-top simulation was used. Twelve teams were recruited for DCE and R-Scope testing. Twelve individuals participated in the DDES setup. The task included 3 steps: picking up a ring, passing it between endoscopic instruments, and placing it on a designated location. Main Outcome Measurements Task performance was evaluated by movement speed and accuracy. Results Task performance was significantly faster when using the DDES system (29 ± 28 seconds) compared with the other operating systems (DCE: 140 ± 55 seconds, R-Scope: 160 ± 71 seconds; P P = .370). Conclusion Designs that separate vision and motion have more degrees of freedom at the tip of the instruments, and an ergonomic user interface provides benefits for bimanual performance compared with more traditional endoscopic designs. With the DDES, a single operator can perform complex endoscopic tasks faster than 2 operators with a DCE or R-Scope.
Planning and simulation of the ring rolling process for improved productivity

Abstract Rolling of rectangular rings often leads to flow related defects such as fish tail or dog bone. This paper presents a computer aided program, ERCRNGROL, for the planning and simulation of the rectangular ring rolling on a radial-axial mill to achieve a defect free ring. Given the final dimensions of the ring, the process planning section of this program allows for the determination of the dimensions for the rolled ring, the ring blank and the cut billet. Based on these dimensions, the “simulation” section of this program calculates the values of the process parameters including rolling forces and torques, wall thickness and height of the ring, and ring temperature as a function of rolling time. To compare the predictions of this program with the production results, a ring rolling mill was instrumented and production data recorded for 61 rectangular rings with varying dimensions. These comparisons indicate that when the rolling schedules of the production mill differ considerably from those of the simulations, flow related defects start developing and the operator has to make large corrective actions to avoid rolling a defective ring. Therefore, this computer aided program will be of great value for ring mill operators in process planting, and in the determination of desired rolling schedules for reduced rejection rates.
Unusual dynamics of a reactor/preheater process with deadtime, inverse response and openloop instability

This paper presents a mathematical analysis of the unusual dynamics found in a coupled reactor/preheater process. The outlet temperature of the reactor exhibits inverse response (wrong-way behaviour) for a change in the inlet reactor temperature and a large deadtime. The coupling of the preheater with the reactor produces positive feedback, which makes the coupled process openloop unstable. Both theoretical linear analysis and simulation studies reveal some unusual dynamics and some interesting frequency response plots. The Nyquist plot of the openloop characteristic equation of the reactor itself is used to determine the number of poles in the right half of the s-plane (RHP) of the openloop characteristic equation of the coupled reactor/preheater system. For small values of reactor gain and small values of the positive-zero time constant, there is one pole; so the closedloop system is stable if the total openloop system (process plus controller) Nyquist plot encircles negatively the (−1,0) point. As the gain and positive-zero time constant are increased, a point of discontinuity is reached. This occurs when the Nyquist plot of the openloop reactor indicates two poles instead of one in the RHP. Now there must be two negative encirclements of the (−1,0) point for closedloop stability. For small values of the positive-zero time constant and reactor gain, the Nyquist plot of the coupled system does show two encirclements. However, for a given deadtime, there are maximum values for the positive-zero time constant and the reactor gain beyond which the closeloop system cannot be stabilized. One of the most unusual dynamic features of this system is the effect that reset (integral action) in the controller has on closedloop stability. Conventional wisdom says that adding integral action in a feedback controller always degrades dynamic stability and performance. However, in this coupled reactor/preheater process the addition of integral action can improve closedloop stability.
My Class Activities Instrument as Used in Saturday Enrichment Program Evaluation.

My Class Activities (MCA) is an instrument that has been used for evaluation of university-based Saturday enrichment programs, but was originally normed using students in regular schools. A sample of MCA scores from 826 students in grades 3-8 from a Saturday enrichment program was used. Four different MCA models were evaluated: (a) the original MCA model containing interest, challenge, choice, and enjoyment; (b) a model including a second-order term connecting enjoyment and interest; (c) a three-factor model containing a combination of interest and enjoyment, challenge, and choice; and (d) the original MCA model after two items were removed. Results indicated that the original MCA four-factor structure provided a better fit when used with the Saturday enrichment sample than did the second-order and the three first-order factor models. However, the best solution regarding model fit was found using the original model, but with the removal of two poorly functioning items. This study highlighted the importanc...
New heavens and new earth: debating values in public forum and Christian responses to the environmental issues

Demonization of Environmentalism by conservative critics, both secular and religious, has been an aspect of the "values" strategy of American politics over the last thirty years. Whereas at one time Conservation, Preservation and Environmentalism were considered bi–partisan issues, in more recent times a wedge has been successfully driven between many Conservatives and the Environmental movement. This schism did not occur accidentally but as part of a deliberate strategy pushed by a coalition of political, social and religious Conservatives. This paper explores what caused many Americans to move away from voting Green and supporting Green policies on religious grounds and how Progressive Christians are responding to this social and political phenomenon.
Double crucible LEC growth of In-doped GaAs using inner crucibles with a bottom tube

In order to reduce InAs segregation along In-doped GaAs single crystals, the liquid encapsulated Czochralski (LEC) process commonly used for GaAs was modified, by using an improved double crucible technique and the concept of zone leveling. This avoided the long-existing dilemma of the double crucible technique: the hole in the inner crucible either is too small to let the replenishing melt go through or too large to suppress mixing between the growth melt and the replenishing melt through the hole. A tube was provided at the bottom of the inner crucible; its 6 mm inside diameter was large enough for the replenishing melt to pass through without being blocked by B 2 O 3 , and its 70 mm length was more than long enough to suppress mixing. The initial growth melt was leveled (enriched) to C o /k, where C o is the targeted crystal composition of 0.04 mol% InAs and k is the effective segregation coefficient 0.116. Effective segregation reduction was obtained and a crystals was grown with a uniform InAs concentration of 0.0422 ± 0.0024 mol% InAs. A similar crystal was grown by using the conventional LEC process; the InAs concentration rose monotonically from 0.0463 mol% at the starting end to 0.245 mol% at the finishing end.
Crystallization behavior of Ge-doped eutectic Sb70Te30 films in optical disks.

We report laser-induced crystallization behavior of binary Sb–Te and ternary Ge-doped eutectic Sb70Te30 thin film samples in a typical quadrilayer stack as used in phase-change optical disk data storage. Several experiments have been conducted on a two-laser static tester in which one laser operating in pulse mode writes crystalline marks on amorphous film or amorphous marks on crystalline film, while the second laser operating at low-power cw mode simultaneously monitors the progress of the crystalline or amorphous mark formation in real time in terms of the reflectivity variation. The results of this study show that the crystallization kinetics of this class of film is strongly growth dominant, which is significantly different from the crystallization kinetics of stochiometric Ge–Sb–Te compositions. In Sb–Te and Ge-doped eutectic Sb70Te30 thin-film samples, the crystallization behavior of the two forms of amorphous states, namely, as-deposited amorphous state and melt-quenched amorphous state, remains approximately same. We have also presented experiments showing the effect of the variation of the Sb/Te ratio and Ge doping on the crystallization behavior of these films.
Managing the storage and battery resources in an image capture device (digital camera) using dynamic transcoding

Advances in hardware imaging technology and user demand for convenient mobile electronic image capture are fueling the development of inexpensive image capture devices that can acquire images rivaling the image quality of photographic film. Improvements in the hardware imaging technology have to be matched with intelligent image storage mechanisms that are aware of local storage and battery constraints. In this paper, we explore using a dynamic, informed image transcoding technique to manage the consumed battery and storage resources in digital cameras. Such application aware technologies are fundamental for the mass consumer acceptance of these newer digital technologies.We show that this technique can allow the camera to store an order of magnitude more images. For a moderate number of images (e.g. 40), transcoding techniques can also maintain high quality images. The availability of fast wireless networks can allow the camera to capture 58 high quality images (51 uploaded) before running out of battery power. Storage technologies with expensive read and write operations (such as micro disks) can have a minor negative impact on battery life because of the extra read and write operations associated with transcoding operations. We show that the ability to effectively communicate the power vs. size vs. quality tradeoff to the end user is important for applications to adapt to the prevailing operating conditions.
Temperature dependence of transmission proton channeling in Ag

Channeling measurements have been made on four Ag single crystals at T = 300 K, T = 90 K, and T = 20 K in the transmission configuration with 1-MeV protons. Effects due to temperature, crystal thickness, and crystal perfection were investigated through the use of large-angle (45$sup 0$) Rutherford scattering and small-angle transmitted intensity and energy measurements. The majority of the measurements were for the axis but some measurements were also performed on the axis. The results for the temperature dependence of psi$sub 1$/$sub 2$( ) (the angular half-width) and the channeling minimum yield agree well with the theoretical expectations and show effects due to crystal thickness and imperfections. The transmission measurements of the channeled-particle stopping power provide a spread in the values for $beta$ (the ratio of the energy loss for channeled particles to that for random particles) from 0.43 to 0.75 primarily owing to variations in specimen perfection. A study of the exit-particle energy distributions for various crystal positions near the axis correlates with the transmitted particle intensity distribution data and is in qualitative agreement with the E/sub perpendicular/ diffusion model of dechanneling. (AIP)
Electrochemical codeposition of indium and antimony from a chloroindate molten salt

The electrochemical codeposition of In and Sb from a novel low temperature molten salt electrolyte is reported. The melt, which consists of InCl3 and 1-methyl-3-ethylimidazolium chloride, allows the codeposition to be accomplished at 45 °C. XPS shows that InSb can be deposited from this system. Electrochemical experiments are provided along with an interpretation that draws on the importance of In(I) species in the melt.
Measurement of turbulence in ocean boundary layers

This paper is concerned with the acquisition of information on turbulent mixing in the boundary layers of the ocean, that is, near the sea surface, near the sea bed, in coastal regions and in estuaries. In such problems, natural fluctuations with periods ranging from a few tenths of a second to a few weeks are of greatest concern, with specific emphasis on continuous time series over periods of at least 30 minutes. For useful measurements in this area, accuracies of 0.1 cm/sec often are required. Presently, my group is using mechanical, acoustic and electromagnetic meters. Only the mechanical units meet the desired specifications, and they have too high a threshold velocity (1.0 cm/sec), are too large when deployed in groups of three, and are too often contaminated by filaform seaweed to be considered satisfactory. However, it is not just the suitability of the flow sensors themselves but also the nature of the devices on which they are mounted and the care with which they are deployed that determines the accuracy of current measurements in general and turbulence data in particular. Precise flow meters located in the wake of a frame part or deployed in the disturbed pressure field caused by a support arm produce results that are just as inaccurate as judiciously spaced sensors with less desirable response characteristics. Furthermore, unresolved frame motion can render velocity fluctuation measurements useless. When deployed from a properly designed support device and with a good understanding of their assets and shortcomings, instruments such as our pulse output mechanical current meters often can be used to obtain results of the scientifically required accuracy. When used in this fashion, however, it is essential that the investigator have a thorough understanding of the instruments based on a comprehensive testing program. Also he must have a good theoretical understanding of their operation and of the flows to be examined in order to permit exploitation of the test results and to avoid misinterpreting their implications in regard to field deployment.
Long-Term Response Patterns of Tallgrass Prairie to Frequent Summer Burning

Knowledge of how tallgrass prairie vegetation responds to fire in the late growing season is relatively sparse and is based upon studies that are either spatially or temporally limited. To gain a more robust perspective of vegetation response to summer burning and to determine if repeated summer fire can drive vegetational changes in native tallgrass prairie, we evaluated species cover and richness over a 14-yr period on different topographic positions from ungrazed watersheds that were burned biennially in the growing season. We found that annual forbs were the primary beneficiaries of summer burning, but their fluctuations varied inconsistently among years. Concomitantly, species richness and diversity increased significantly with summer burning but remained stable through time with annual spring burning. After 14 yr, species richness was 28% higher in prairie that was burned in the summer than in prairie burned in the spring. Canopy cover of big bluestem (Andropogon gerardii Vitman) and Indiangrass (Sorghastrum nutans [L.] Nash) increased significantly over time with both summer and spring burning, whereas heath aster (Symphyotrichum ericoides [L.] Nesom), aromatic aster (Symphyotrichum oblongifolium [Nutt.] Nesom), and sedges (Carex spp.) increased in response to only summer burning. Kentucky bluegrass (Poa pratensis L.) cover declined in both spring-burned and summer-burned watersheds. Repeated burning in either spring or summer did not reduce the cover or frequency of any woody species. Most perennial species were neutral in their reaction to summer fire, but a few species responded with large and inconsistent temporal fluctuations that overwhelmed any clear patterns of change. Although summer burning did not preferentially encourage spring-flowering forbs or suppress dominance of the warm-season grasses, it is a potentially useful tool to increase community heterogeneity in ungrazed prairie.
Arrhythmogenic remodeling of β2 versus β1 adrenergic signaling in the human failing heart.

Background— Arrhythmia is the major cause of death in patients with heart failure, for which β-adrenergic receptor blockers are a mainstay therapy. But the role of β-adrenergic signaling in electrophysiology and arrhythmias has never been studied in human ventricles. Methods and Results— We used optical imaging of action potentials and [Ca2+]i transients to compare the β1- and β2-adrenergic responses in left ventricular wedge preparations of human donor and failing hearts. β1-Stimulation significantly increased conduction velocity, shortened action potential duration, and [Ca2+]i transients duration (CaD) in donor but not in failing hearts, because of desensitization of β1-adrenergic receptor in heart failure. In contrast, β2-stimulation increased conduction velocity in both donor and failing hearts but shortened action potential duration only in failing hearts. β2-Stimulation also affected transmural heterogeneity in action potential duration but not in [Ca2+]i transients duration. Both β1- and β2-stimulation augmented the vulnerability and frequency of ectopic activity and enhanced substrates for ventricular tachycardia in failing, but not in donor, hearts. Both β1- and β2-stimulation enhanced Purkinje fiber automaticity, whereas only β2-stimulation promoted Ca-mediated premature ventricular contractions in heart failure. Conclusions— During end-stage heart failure, β2-stimulation creates arrhythmogenic substrates via conduction velocity regulation and transmurally heterogeneous repolarization. β2-Stimulation is, therefore, more arrhythmogenic than β1-stimulation. In particular, β2-stimulation increases the transmural difference between [Ca2+]i transients duration and action potential duration, which facilitates the formation of delayed afterdepolarizations.
THE ABSOLUTE MAGNITUDES OF THE RR LYRAE STARS

We present a new calibration of the relationship between the absolute magnitudes and metal abundances, [Fe/H], of RR Lyrae stars. Temperatures inferred from optical and near infrared color indices and the new Kurucz models are utilized in conjunction with Baade-Wesselink solutions to derive absolute magnitudes. Temperature inferred from the optical and near infrared photometry are ~ 200K - 300K higher for the variables than those given from (V-K) color indices and the older Kurucz models. We find Mv = 0.287 [Fe/H] + 0.964. This equation gives higher luminosities (~ 0.2 mag) for the metal-poor variables than previous B-W calibrations. The RR Lyrae stars in the Large Magellanic Cloud in conjunction with our calibration yield a distance modulus of 18.53. Thus, the Cepheids and RR Lyrae stars give identical distance moduli at ≤q 0.1 mag level. The repercussions of the higher temperatures and higher luminosities of RR Lyrae stars on the distances and ages of Globular clusters, distance to the galactic center, the Hubble constant and age of the universe, and the masses of RR Lyrae stars are discussed.
Some applications of the empirical force field method to stereochemistry

The empirical force field (or molecular mechanics) method has become increasingly popular as a computational tool in chemistry. Examples are adduced from work in our laboratories to illustrate some of the power and scope of this method as applied to problems in static and dynamic stereochemistry.
Complexity of care needs and unstaged cancer in elders: a population-based study.

Abstract Background : Little is known about the contribution of older patients' complexity of care needs (COCN) to unstaged cancer, or incomplete evaluation of the extent of disease. We aimed at examining the association between the patients' COCN at baseline and unstaged cancer. Methods : The study used linked databases consisting of the Ohio Cancer Incidence Surveillance System (OCISS), Medicare and Medicaid enrollment files, the home health care Outcome and Assessment Information Set (OASIS), and the Long Term Care Minimum Data Set (MDS). The study population included patients 65 years of age or older diagnosed with incident breast ( n =4404), prostate ( n =5334), or colorectal cancer ( n =4822) in year 2000. The outcome of interest was unstaged cancer. Patients were identified with high COCN if they were admitted to a nursing home, with moderate COCN if they received home health services, and with low COCN if they were neither admitted to a nursing home nor received home health services, at baseline, or in the 6 months prior to cancer diagnosis. We employed logistic regression analyses to evaluate the independent association between COCN and unstaged cancer after adjusting for patient demographics and socioeconomic attributes. Results : The proportion of unstaged cases increased significantly with older age, by Medicaid status, and by COCN at baseline. Compared with patients with low COCN, those with higher complexity were four to five times as likely to have unstaged cancer. Conclusion : The occurrence of unstaged cancer follows a systematic pattern of increase by age, Medicaid status, and COCN at baseline.
Nucleotide sequence of Escherichia coli isochorismate synthetase gene entC and evolutionary relationship of isochorismate synthetase and other chorismate-utilizing enzymes.

Abstract Biochemical analysis of the enzymatic activity catalyzing the conversion of chorismate to isochorismate in the enterobactin biosynthetic pathway attributed the reaction to the isochorismate synthetase enzyme, designated EntC. However, the lack of mutations defining this activity has hampered the precise identification of the entC structural gene. In this study, we engineered a stable insertion mutation into the chromosomal region between the enterobactin genes fepB and entE. This mutation disrupted the structural gene for a previously identified 44-kilodalton protein and eliminated production of 2,3-dihydroxybenzoic acid, the catechol precursor of enterobactin. The complete nucleotide sequence of this gene was determined and compared with the sequences of other genes encoding chorismate-utilizing proteins. The similarities observed in these comparisons not only indicated that the locus is entC but also supported the premise that these enzymes constitute a family of related proteins sharing a common evolutionary origin. In addition, in this and the accompanying paper (M. S. Nahlik, T. J. Brickman, B. A. Ozenberger, and M. A. McIntosh, J. Bacteriol. 171:784-790, 1989), evidence is presented indicating that the entA product is potentially a secondary factor in the chorismate-to-isochorismate conversion and that the prototypic entC lesion (entC401) resides in the structural gene for the EntA protein. Finally, polarity effects from the insertion mutation in entC on downstream biosynthetic genes indicated that this locus is the promoter-proximal cistron in an ent operon comprising at least five genes. Appropriate regulatory signals upstream of entC suggest that this operon is regulated by iron through interaction with the Fur repressor protein.
The origins and evolution of freeze-etch electron microscopy

The introduction of the Balzers freeze-fracture machine by Moor in 1961 had a much greater impact on the advancement of electron microscopy than he could have imagined. Devised originally to circumvent the dangers of classical thin-section techniques, as well as to provide unique en face views of cell membranes, freeze-fracturing proved to be crucial for developing modern concepts of how biological membranes are organized and proved that membranes are bilayers of lipids within which proteins float and self-assemble. Later, when freeze-fracturing was combined with methods for freezing cells that avoided the fixation and cryoprotection steps that Moor still had to use to prepare the samples for his original invention, it became a means for capturing membrane dynamics on the millisecond time-scale, thus allowing a deeper understanding of the functions of biological membranes in living cells as well as their static ultrastructure. Finally, the realization that unfixed, non-cryoprotected samples could be deeply vacuum-etched or even freeze-dried after freeze-fracturing opened up a whole new way to image all the other molecular components of cells besides their membranes and also provided a powerful means to image the interactions of all the cytoplasmic components with the various membranes of the cell. The purpose of this review is to outline the history of these technical developments, to describe how they are being used in electron microscopy today and to suggest how they can be improved in order to further their utility for biological electron microscopy in the future.
Second Births and the Second Shift: A Research Note on Gender Equity and Fertility

In a set of propositions on fertility transition, Peter McDonald recently proposed that the decline from replacement-level fertility to low fertility is associated with a combination of high levels of gender equity in individual-oriented institutions, such as education and market employment, and low levels of gender equity in the family and family-oriented institutions. Similarly, the “second shift,” or the share of domestic work performed by formally employed women, forms a critical piece of current cross-national explanations for low fertility. Building on this scholarship, the authors explore whether there is empirical evidence at the individual level for a relationship between gender equity at home, as indicated by the division of housework among working couples with one child, and the transition to a second birth. Results, based on a sample of US couples, indicate a U-shaped relationship between gender equity and fertility. Both the most modern and the most traditional housework arrangements are positively associated with fertility. This empirical test elaborates the family-fertility relationship and underscores the need to incorporate family context, including gender equity, into explanations for fertility change.
Psychological Dilemmas of Medical Progress

The psychological dilemmas created by medical progress are ambiguous and complex. In the selection of patients for chronic hemodialysis there is little evidence that psychiatric screening prevents behavioral disturbances associated with the rigors of dialysis; and in view of the ethical objections to selecting one patient over another for life-saving procedures, psychiatric contraindications are limited and should not be confused with value judgments to rationalize rejection of some patients. With living unrelated and related donors for organ transplants the basic psychological issue relates to whether the donation is based on altruism or neuroticism. The increased use of artificial and transplanted organs also raises questions related to quest for immortality and the role of the psychiatrist in working with the patient caught in the bind of the “too long” life.
Estimation of size‐specific mortality rates in zooplankton populations by periodic sampling1

Many populations of small, mobile organisms cannot be analyzed with standard demographic techniques. A method is introduced for estimating patterns of size-specific mortality for such species from periodic samples. The technique does not require that individuals be marked or recaptured and may be extended to age and other quantitative characters so long as the class distribution of the population and the rate of flux of individuals between classes can be accurately determined. The most serious difficulty in applying the technique seems to be the ability to sample adequately populations that are patchy in space. However, even if the problem of patchiness cannot be eliminated, so long as the size-frequency distribution can be accurately described, the technique generates the correct pattern of size-specific mortality and will provide minimum estimates of mortality for the different classes. Preliminary results presented for four species of planktonic cladocerans suggest that more widespread application of the technique may allow an empirical test of the assumptions on which zooplankton community theory is based.
Alteration of TGA factor activity in rice results in enhanced tolerance to Xanthomonas oryzae pv. oryzae.

*† Summary In dicotyledonous plants broad-spectrum resistance to pathogens is established after the induction of the systemic acquired resistance (SAR) response. In Arabidopsis the NPR1 protein can regulate SAR by interacting with members of the TGA class of basic, leucine-zipper transcription factors to alter pathogenesis-related (PR) gene expression. Overexpression of (At)NPR1 in Arabidopsis enhances resistance to multiple pathogens. Similarly, overexpression of (At)NPR1 in rice enhances resistance to the bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo). These results suggest that components of the (At)NPR1-mediated SAR defense response may be conserved between monocots and dicots. To determine whether or not rice TGA factors are involved in disease resistance responses, the effect of altering the function of rice TGA2.1 was analyzed in transgenic plants. Transgenic rice overexpressing an rTGA2.1 mutant, that can no longer bind DNA, and transgenic rice that have the endogenous rTGA2.1 silenced by dsRNA-mediated silencing were generated. Both types of transgenic rice displayed increased tolerance to Xoo, were dwarfed, and had altered accumulation of PR genes. The results presented in this study suggest that wild-type rTGA2.1 has primarily a negative role in rice basal defense responses to bacterial pathogens.
Relation Between Scald of Montmorency Cherries and Oxygen Content in Soak Tanks

SUMMARY In studies of oxygen concentration and scald in commercial soak tanks, scald developed in bruised cherries in tanks with low oxygen concentration in the water. Laboratory experiments with bruised cherries in water or in a nitrogen atmosphere showed that 2 ppm of oxygen is the critical level below which scald develops. No scald developed on bruised cherries kept in water with an almost constant oxygen level of 8.6 ppm, obtained by saturating the water with air at room temperature (23°C) for 91/2 hr. In 1965 the Air-Aqua aeration system was tested under controlled tank storage conditions in Pennsylvania. It proved to be an effective means of increasing the oxygen level of water, thus controlling cherry scald. Aeration also provided more uniform temperatures in the tanks.
An analysis of the errors in recorded heart rate and blood pressure in the ICU using a complex set of signal quality metrics

We analyzed over 95,000 individual values of heart rate and blood pressure derived from 118,000 hours of electrocardiogram (ECG) and 71,000 hours of Arterial Blood Pressure (ABP) data from 1,071 patients using two methods. One method was a nursing-staff verified automatic measurement transmitted from the bedside monitor to central nursing station at intervals of 5 to 60 minutes. The other method involved re-deriving the estimates from continuous ECG and ABP waveforms using independent algorithms and a set of previously described signal quality metrics to reject noisy and untrustworthy data. Results demonstrate that after the removal of obvious artifactual derived HR and ABP estimates, the two measurement sources disagree, on average, by a clinically insignificant amount. Furthermore, after rejection of data using signal quality metrics, the error distribution curve significantly tightens. The clinically-verified BP values exhibit a small but significant bias towards overestimation, both as a function of time of day and as a function of day of the week. Differences in values between time of day and day of week were small but statistically significant. Inter-nurse differences are also described.