cssi/SciSciGPT-SciSciNet huggingface dataset:
MAGNETIC CYCLES IN THE SUN: MODELING THE CHANGES IN RADIUS, LUMINOSITY, AND p-MODE FREQUENCIES

We report on the results obtained with a stellar evolution code in which cyclic magnetic fields are imposed in the convection zone of a 1.0 M☉ star. Magnetic effects are incorporated in two ways: (1) the field pressure and energy density are included in the equations of hydrostatic equilibrium and conservation of energy; and (2) the field inhibits the onset of convection according to a prescription derived by Gough & Tayler (1966). Inserting magnetic fields into the convection zone with strengths comparable to the observed global fields in the Sun, and assuming a simple depth dependence for the field strength, we find differences in luminosity and radius between nonmagnetic and magnetic models that are consistent in amplitude with the observed activity-related changes in the Sun. Using the same magnetic fields, and computing p-mode frequencies for nonmagnetic and magnetic models, we find that the frequencies in a magnetic model are larger than those for a nonmagnetic model. The frequency differences between nonmagnetic and magnetic models agree in sign, and overlap in magnitude and frequency dependence, with the shifts in frequency which have been observed in the Sun between solar minimum and solar maximum. We find that the luminosity variations are out of phase with the magnetic variations: in order to help reconcile this result with empirical solar data, we note that the global (poloidal) fields in the Sun are observed to pass through minimum values at times that correspond roughly with times of maximum toroidal fields.
Lord Monboddo's “letter on rhetorick”: Defense of Aristotle

James Burnett, Lord Monboddo (1714-1799) enjoyed considerable recognition as a Scottish advocate and judge; however, a passion for the ancient Greeks occupied much of his attention and contributed to his lasting reputation as a man of letters. It is likely that his initial exposure to the Greek philosophers was under the tutelage of Dr. Francis Skene, a classical scholar who worked early in his career as Burnett's private tutor and then became a professor of philosophy at Marischal College where Burnett was a student. Burnett found ancient doctrines to be appealing because of their attention to first principles and he remained a devoted advocate of Greek thinking throughout his life.' Monboddo's views on the ancients and their significance for the Scottish Enlightenment are best preserved in two lengthy works. Origin and Progress of Language (1774-92) consists of six volumes and is best known to students of composition, rhetoric, and criticism for its defense of Greek literary style in general; its efforts to apply ancient doctrines of style, logic and composition to the needs of the Scottish Enlightenment; and its praise of Aristotle in particular as the philosopher who bridged the gulf separating the sophists and Plato. Ancient Metaphysics (1779-99), also six volumes, was Monboddo's second contribution to the world of letters and further proclaimed his admiration for the Greeks and his distaste for alternative schools of thought that had become popular among his contemporaries.2 By the latter years of the Eighteenth Century, Aristotle and other Greek rhetors were largely ignored by British rhetorical theorists. Even among those exponents of a classical doctrine early in the century, including John Ward (A System of Oratory, 1759) and John Holmes (The Art of Rhetoric Made Easy, 1755), it was the Roman model of rhetoric, organized around Cicero's officia that was popular. By mid-century, even Roman doctrine had been obscured by the "new rhetorics," reflecting new assumptions and organizing doctrine along three new lines. The psychological school, most clearly illustrated by George Campbell's Philosophy of Rhetoric (1776), was influenced by Baconian and Lockean thinking. These theorists, using the Baconian empirical method, explored relationships between thought and expression, creating an array of new terms to account for mental processes that govern rhetorical acts.3
Wavelength Generalization after Discrimination Learning with and without Errors

Pigeons were trained to discriminate between 580 mk (S+) and 540 mµ (S-) by procedures which resulted in either a large amount of responding to S-or in little or no responding to S-. A shift in the peak of a postdiscrimination generalization gradient, away from S-, was obtained only if the discrimination was learned with a large amount of responding to S-.
Preoperative relative abdominal aortic aneurysm thrombus burden predicts endoleak and sac enlargement after endovascular anerysm repair.

Background Endoleak and sac growth remain unpredictable occurrences after EVAR, necessitating regular surveillance imaging, including CT angiography. This study was designed to identify preoperative CT variables that predict AAA remodeling and sac behavior post-EVAR. Methods Pre- and postoperative CT scans from 136 abdominal aortic aneurysms treated with EVAR were analyzed using M2S (West Lebanon, NH) software for size measurements. Preoperative total sac volume and proportion of thrombus and calcium in the sac were assessed. Sac change was defined as a 3-mm difference in diameter and a 10-mm3 difference in volume when compared with preoperative measurements. Univariate analysis was performed for age, gender, AAA size, relative thrombus/calcium volume, device type, presence of endoleak, and the effects on sac size. Results Gender, device type, age, AAA size, and percent calcium were not predictive of sac change post-EVAR. Increased proportion of thrombus on pre-EVAR resulted in a greater likelihood of sac shrinkage (P = 0.002). Patients with aneurysms that grew on postoperative CT scan had less sac thrombus on pre-EVAR (mean 27.5%) than patients without evidence of endoleak (mean 41.9%, P 50% pre-EVAR thrombus developed endoleak. A >50% thrombus burden resulted in endoleak in significantly fewer patients (6.7%) compared with those who had <50% thrombus (43.1%). Conclusions The proportion of thrombus on preoperative CT may predict sac behavior after EVAR and development of an endoleak. Greater than 50% thrombus appears to predict absence of endoleak after EVAR. Aneurysms with large thrombus burden are less likely to grow and may require less vigilant postoperative surveillance than comparable AAA with relatively little thrombus.
Surgical debridement and intralesional steroid injection in the treatment of idiopathic AIDS-related anal ulcerations

background The treatment of idiopathic anal ulcerations in AIDS patients is still evolving. These patients suffer with severe incapacitating anal pain. patients and methods Relief of pain was achieved with the use of intralesional steroid injections. Twenty-one patients from 1990 to 1993 presented with severe anal pain of 4.5 months average durations (range 3 weeks to 2 years). The average CD4 count was 52.1 (range 0 to 150). Fourteen (67%) patients had a solitary ulcer, while 7 (33%) had complex ulcerations. results All patients were treated by debridement of the ulcer, biopsy, and intralesional injection of steroids. Microscopic evaluation revealed nonspecific inflammatory changes, without histopathologic evidence of viral infection or malignancy. Viral tissue cultures were negative. Fifty-seven percent of patients required only one injection to achieve dramatic relief of pain. Forty-three percent necessitated additional injections at 2-week intervals. The average patient was injected 1.9 times (range 1 to 7), with 20 of 21 patients (95%) reporting good to excellent pain relief. conclusion AIDS anal ulcerations should be treated aggressively with surgical debridement, biopsy and intralesional steroids. The efficacy of this therapy suggests that symptoms are partially due to inflammatory mediators.
Mass singularities of Feynman amplitudes

Feynman amplitudes, regarded as functions of masses, exhibit various singularities when masses of internal and external lines are allowed to go to zero. In this paper, properties of these mass singularities, which may be defined as pathological solutions of the Landau condition, are studied in detail. A general method is developed that enables us to determine the degree of divergence of unrenormalized Feynman amplitudes at such singularities. It is also applied to the determination of mass dependence of a total transition probability. It is found that, although partial transition probabilities may have divergences associated with the vanishing of masses of particles in the final state, they always cancel each other in the calculation of total probability. However, this cancellation is partially destroyed if the charge renormalization is performed in a conventional manner. This is related to the fact that interacting particles lose their identity when their masses vanish. A new description of state and a new approach to the problem of renormalization seem to be required for a consistent treatment of this limit.
Laser vaporization /FTMS as a probe of silicon surface reactivity

Abstract Exposure of a silicon surface to several reagent gases followed by laser vaporization produces unusual ions in addition to the silicon cluster ion (Si+n) distribution typical for clean silicon surfaces. The appearance of these ions is correlated to silicon surface reactions. Laser vaporization of silicon following exposure to the gases NH3, XeF2, CF3I, O2, NO, CH3OH, H2O, C2H4, D2, and CH4 has been studied. Changes in the relative intensities of product ions as a function of exposure are measured for some of the reagent gases. The results from laser vaporization/Fourier transform mass spectrometry (FTMS) are compared to studies of silicon surface reactions using other experimental techniques and to some secondary ion mass spectrometry (SIMS) results.
Experimental evidence for multiple post-ionization of field-evaporated ions

The charge-state distribution of field-evaporated tungsten ions has been measured as a function of electric field using the pulsed-laser atom probe. The results confirm the recent post-ionization model of Haydock and Kingham and give the first experimental evidence for multiple post-ionization. At low field strengths ( 3.0 V/\AA{}) and high surface temperatures (g 1000 K), field-evaporated triply charged dimers are detected, and built-up regions which significantly enhance the local electric field at the desorption site are observed.
Increased vagal cardiac nerve traffic prolongs ventricular refractoriness in patients undergoing electrophysiology testing

Abstract Stimulation of the vagus nerve in animals causes prolongation of sinus cycle length, abioventricular nodal conduction and ventricular refractoriness. Vagal stimulation appears to have a protective effect in animal models of sudden death. The electrophysiologic effects of enhanced vagal activity on right ventricular (RV) refractoriness in man have not been studied previously. The comparative effects of enhanced vagal tone (neck suction to −60 mm Hg) on sinus cycle length and RV refractoriness were assessed in 26 patients. The electrophysiologic effects of vagal activation by stimulation of carotid baroreceptors with neck suction were compared to the effect of carotid and aortic baroreceptor stimulation with phenylephrine infusion in 12 patients. During neck suction, mean sinus cycle length (819 ± 32 ms) was prolonged by 146 ± 20 ms (p These results show that reflex vagal stimulation with neck suction or phenylephrine infusion causes a small but significant prolongation in RV refractoriness. These findings imply that the potential benefits of enhanced vagal tone in preventing sudden death may be indirectly mediated by changes in ventricular refractoriness.
Lipids noncovalently associated with keratins and other cytoskeletal proteins of mouse mammary epithelial cells in primary culture.

Abstract Lipids noncovalently associated with cytoskeletal (CS) proteins of mouse mammary epithelial cells (MMEC) grown in primary culture were analyzed. A CS fraction, preapred by subjecting MMEC to 1.5 KCl and 1% Triton X-100 in phosphate buffered saline (pH 7.4), was extracted 4–6 times with chloroform/methanol. Thin-layer chromatography (TLC) indicated that in comparison to whole cell lipid extracts, CS lipids consisted mostly of neutral lipids, especially triacylglycerols and, possibly cholesteryl esters. TLC analysis of chloroform/methanol CS extracts prepared from MMEC that had been incubated 4 h in [ 3 H]palmitate revealed similar results, with the majority of label appearing in triacylglycerols and other neutral lipids. By autoradiography of sodium dodecyl sulfate polyacrylamide gels, all of the major CS proteins appeared labelled. The major regions of autoradiographic density of the gel were excised, the protein solubilized, and the lipids extracted and subjected to TLC. Most of the radiolabel appeared at the origin and ion front and resolved as neutral lipids. In contrast, keratins of 54–55 kDa and 46 kDa appeared to be associated noncovalently with a higher ratio of polar lipids (possibly phospholipids) to nonpolar (neutral lipids). Very little radioactivity, mostly neutral lipid, was associated with actin. A previously unidentified CS component of 30 kDa had primarily noncovalently bound neutral lipid. The results are discussed in terms of the apparent interactions of keratin filaments with the plasma membrane, nuclear envelope and cytoplasmic organelles.
AFM FABRICATION OF SUB-10-NANOMETER METAL-OXIDE DEVICES WITH IN SITU CONTROL OF ELECTRICAL PROPERTIES

Metal wires and metal-oxide-metal junctions were fabricated by anodic oxidation with the conducting tip of an atomic force microscope (AFM). The width of the wires and resistance of the junctions were controlled by real-time, in situ measurement of the device resistance during fabrication. Because the properties of nanometer-scale devices are very sensitive to size variations, such measurements provide a more accurate method of controlling device properties than by controlling geometry alone. In this way, structures with critical dimensions of less than 10 nanometers were fabricated with precisely tailored electrical properties.
Corrected ISICS program versions available due to a minor calculation error involving M3 X-ray production cross sections

Abstract The Coster–Kronig enhancement factor for M3 shell X-ray production cross sections was found to be incorrectly calculated in all versions of ISICS. The affected program has been corrected and replaced in all versions of ISICS. New version program summary Program title: ISICS2011 and predecessor versions. Catalogue identifier: ADDS_v1_1, ADDS_v2_1, ADDS_v3_1, ADDS_v4_1, ADDS_v5_1 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADDS_v1_1.html etc. Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc. : 4470, 4529, 4529, 4526, 6011 No. of bytes in distributed program, including test data, etc.: 91829, 120319, 122150, 107399, 127625 Distribution format: tar.gz Programming language: C. Computer: PC. Operating system: Windows systems with a 32-bit processor. RAM: 4Mb Classification: 16.7. Catalogue identifier of previous version: ADDS_v1_0, ADDS_v2_0, ADDS_v3_0, ADDS_v4_0, ADDS_v5_0 Journal reference of previous version: Comput. Phys. Comm. 97(1996)315, 176(2007)157, 179(2008)616, 180(2009)1716, 182(2011)2439 Does the new version supersede the previous version?: Yes Nature of problem: Ionization and X-ray production cross sections for ion–atom collisions. Solution method: Numerical integration of form factor using a logarithmic transform and Gaussian quadrature, plus exact integration limits. Reasons for new version: The Coster–Kronig enhancement factor for M3 shell X-ray production cross sections was found to be incorrectly calculated in all versions of ISICS (including ISICSoo, addressed separately in this issue). Summary of revisions: The affected program was corrected and has been replaced in each version of ISICS. The affected program for each version of ISICS is as follows: CLC3.C (ADDS_v1_0), CLChseV2.C (ADDS_v2_0, ADDS_v3_0), CLC_Rhs2.C (ADDS_v4_0, ADDS_v5_0). A newly compiled executable file has replaced existing files in all versions. Restrictions: Same as in previous versions Additional comments: The corrected program can also be accessed from the author upon request. Running time: Same as in previous versions
Mutagenesis of AS52 cells by low concentrations of lead(II) and mercury(II)

Little is known at the molecular level concerning the genotoxic effects following the acute exposure of eukaryotic cells to low concentrations of lead (II) or mercury (II). There have been conflicting reports concerning the mutagenic potential of these heavy metals, and there have not been any studies performed to determine the molecular mechanism(s) by which these metals are mutagenic. The Chinese hamster ovary cell line, AS52, contains a stably integrated single functional copy of the Eschericia coli xanthine-guanine phosphoribosyltransferase (gpt) gene. Mutations in the gpt gene confer resistance to 6-thioguanine (TG). There was little effect on viability, as measured by relative cloning efficiency, of AS52 cells exposed to lead(II) or mercury(II) up to concentrations of 0.5 {mu}M and 0.3 {mu}M, respectively, However, higher concentrations of the metals caused a significant increase in cell death. There was also a dose-dependent increase in the isolation of mutants resistant to TG in treated cells when compared to nontreated controls. Concentrations of the metals as low as 0.1 {mu}M caused a significant increase in the number of mutants resistant to TG when compared to the number of spontaneous mutants obtained in nontreated controls. While the molecular mechanism(s) by which lead and mercury (II) aremore » genotoxic is unknown, the results of this study demonstrate that low concentrations of lead (II) and mercury (II) are mutagenic in eukaryotic cells. 18 refs., 3 figs., 2 tabs.« less
On the determination of minority carrier lifetime from the transient response of an MOS capacitor

Minority carrier lifetime greater than 10-10seconds can be determined for silicon at room temperature by observing the transient response of the MOS capacitance after the application of a large depleting voltage. The waveform is exponential for heavily doped samples and nonexponential for lightly doped samples. The transition occurs when the oxide capacitance approximately equals the space-charge capacitance. Results are presented for a lightly doped bulk silicon wafer exhibiting an effective minority carrier lifetime of 7.6 microseconds and a thin silicon-on-sapphire film with a lifetime of 4.5 nanoseconds. The ratio of transient time constant to lifetime is typically 105-108at room temperature. Lower lifetime may be determined by cooling the sample. A graphical method is presented to rapidly extract lifetime from the transient response of lightly doped samples when the waveform is nonexponential.
Flame synthesis of coiled carbon nanotubes

Abstract A flame synthesis technique of coiled carbon nanotubes using acetylene jet flames and iron catalyst is presented. It was found that acetylene flames generate single wall coiled nanotubes within in a narrow pyrolysis zone above the burner for a limited range of fuel flow rates. The corresponding local convective time scale corresponding to the coiled nanotube formation zone is around 0.04 ms. The yield of the coiled carbon nanotubes was further increased by changing the local convective time scale with the addition of controlled turbulence.
Induction of cell division: role of cell membrane sites.

Density dependent inhibition of cell replication is released in stationary cultures of BALB/c-3T3 fibroblasts by the potent tumor promoter for mouse skin, phorbol myristate acetate (PMA). The saturation density of these cultures, which is dependent on the serum concentration of the medium, is increased by PMA. Cell division, which can be induced by PMA or serum in stationary monolayers of BALB/c-3T3 cells, is not blocked by several inhibitors of proteolytic enzymes or the plant lectins, concanavalin A or wheat germ agglutinin. Induction of cell replication by PMA or serum does not appear to be dependent on proteolytic activity, and the membrane sites associated with this induction appear to be distinct from the agglutinin-binding sites.
Spectroscopy and Electronic Structures of Mono- And Binuclear High-Valent Non-Heme Iron-Oxo Systems

Abstract High-valent iron–oxo intermediates are known or believed to be key oxidizing species in the catalytic mechanisms of many mononuclear and binuclear non-heme iron enzymes. So far only limited experimental data on their electronic structures are available. In this study we extend knowledge from the experimentally well characterized mononuclear FeIV=O (S = 1) biomimetic model system to computational insight into the spectroscopy and electronic structures of mono-and binuclear high-valent iron–oxo enzyme intermediates. In the mononuclear FeIV=O complexes, we predict the spectroscopy and energies of the electronic transitions to be very different for the S = 1 and S = 2 spin states, but the iron–oxo bonding for both spin states to be very similar. A comparison of the S = 2 mono- and binuclear high-valent iron-sites predicts similar electronic transitions. However, the bent iron–oxo bridge and interactions with the second iron-center in the dimer shift the transitions to higher energies and splits the d(xz/yz) orbital set. These electronic structure and TD-DFT results provide a basis for understanding the spectroscopy and electronic structures of high-valent intermediates in mono- and binuclear non-heme iron enzymes.
Improved slow-light delay performance of a broadband stimulated Brillouin scattering system using fiber Bragg gratings

We present a technique for improving the pulse-delay performance of a stimulated Brillouin scattering (SBS) based broadband slow-light system by combining it with fiber Bragg gratings (FBG). We optimize the physical device parameters of three systems: (1) broadband SBS, (2) broadband SBS + a single FBG, and (3) broadband SBS + a double FBG for maximizing the delay performance. The optimization is performed under distortion and system resource constraints for a range of bit rates from 0.5 to 8.5 Gbps. We find that an optimized broadband SBS + a double FBG system improves the fractional delay 1.8 times that of the broadband SBS system at an optimum bit rate of 3 Gbps. Also, pump power consumption is reduced by 15% as compared to the broadband SBS system at the same bit rate.
Relationship of Mitochondrial Swelling to Thyroxine-Stimulated Mitochondrial Protein Synthesis

The effects of thyroid hormones and other swelling agents upon mitochondrial volume and upon uptake and incorporation of leucine by normal rat liver mitochondria have been studied in vitro in the medium usually employed for protein synthesis. The lowest concentration of T4 (10 μM) which consistently caused swelling also stimulated amino acid incorporation; both increased as the concentration of T4 was increased to 50 μM. High levels of T4 (ξ100 μM) caused further swelling but inhibited incorporation.The ability of analogues of T4 to stimulate incorporation paralleled their ability toproduce swelling. Inhibition of protein synthesis by chloramphenicol did not alter T4-induced swelling. Of other agents tested, Pi and Fe+ caused swelling without affecting incorporation. Other cations (Ca+, Zn+, Cu+, Ag+ and Hg+) and steroid hormones (progesterone and deoxycorticosterone acetate) markedly inhibited incorporation while causing variable degrees of swelling. The fatty acids (myristic and palmitic acid) also inhi...
Skinning cubic Bézier splines and Catmull-Clark subdivision surfaces

Smooth space deformation has become a vital tool for the animation and design of 2D and 3D shapes. Linear methods, under the umbrella term of "linear blend skinning", are the de facto standard for 3D animations. Unfortunately such approaches do not trivially extend to deforming vector graphics, such as the cubic Bezier splines prevalent in 2D or subdivision surfaces in 3D. We propose a variational approach to reposition the control points of cubic Bezier splines and Catmull-Clark subdivision surfaces---or any linear subdivision curves or surfaces---to produce curves or surfaces which match a linear blend skinning deformation as closely as possible. Exploiting the linearity of linear blend skinning, we show how this optimization collapses neatly into the repeated multiplication of a matrix per handle. We support C0, C1, G1, and fixed-angle continuity constraints between adjacent Bezier curves in a spline. Complexity scales linearly with respect to the number of input curves and run-time performance is fast enough for real-time editing and animation of high-resolution shapes.
A review: Using nanoparticles to enhance absorption and bioavailability of phenolic phytochemicals

Abstract Phenolic phytochemicals have been of particular interests in food and pharmaceutical fields because they have potential to reduce the incidences of coronary heart disease, diabetes, cancers, and other chronic diseases. However, extremely low absorption rate of phenolic phytochemicals restricts their bioactivity in vivo . Such low absorption and bioavailability are due to their low water solubility, poor stability, passive diffusion, and active efflux in the gastrointestinal tract. Nanoparticle delivery system has been widely applied in pharmaceutical field to enhance absorption of bioactive compounds. This review explains absorption barriers of phenolic phytochemicals in the gastrointestinal tract. Nanoparticles delivery systems are emphasized regarding fabrication methods and their potential benefits on phenolic phytochemical absorption. Particularly, absorption mechanisms of nanoparticles by epithelial cells and biodistribution of nanoparticles after absorption are mainly discussed. Moreover, the potential challenges of nanoparticles as delivery system for phenolic phytochemicals in the gastrointestinal tract are also discussed.
Efficacy of a modified live Edwardsiella ictaluri vaccine in channel catfish as young as seven days post hatch

Channel catfish (Ictalurus punctatus) were vaccinated by immersion at 12, 14, 16 and 31 days post hatch with modified live Edwardsiella ictaluri RE-33 vaccine in 1997 and 7 and 10 days post hatch in 1998. At 20 to 21 days post vaccination, the groups of vaccinates and non-vaccinates were challenged with virulent E. ictaluri and monitored for mortality for at least 14 days following challenge. Results showed the vaccine to be efficacious in channel catfish as young as 7 days post hatch with relative percent survival ranging from 58.4 to 77.5.
Dielectric Properties of Polymer/Ferroelectric Ceramic Composites from 100 Hz to 10 GHz

Dielectric properties of model BaTiO3/polymer composites were measured over a broad frequency and temperature range. A series of BaTiO3/monomer suspensions were photocured into thin wafers. The wafers were equipped with aluminum electrodes, and the dielectric permittivity of the composites was investigated at frequencies from 100 Hz to 10 GHz and at temperatures from −140 to +150 °C. It has been found that for the same BaTiO3 loading dielectric characteristics of the composites strongly depend of the type of polymer. Polar polymers increase dielectric constant of the composites at low frequencies but have little effect at gigahertz frequencies. Dielectric losses of the composites show a maximum at some intermediate frequency within megahertz to gigahertz range that reflects the relaxation behavior of the polymer matrix. The magnitude of the losses increases with increasing polarity of the polymer component. At constant frequency and temperature, the composites follow a linear relationship between logarith...
Cellular actions and pharmacology of calcium-channel blockers

The calcium-channel blockers represent a diverse group of chemical structures that block calcium-selective channels in the plasma membrane of a variety of excitable cells. As the calcium fluxes carried by these channels allow ionic calcium (Ca2+) to gain access to the cell interior, where Ca2+ serves as an activator--messenger, calcium-channel blockers generally act to inhibit cell function. By reducing the depolarizing currents caused by the entry of positively charged Ca2+ into the negatively charged interior of resting cells, the calcium-channel blockers also inhibit excitatory processes that depend on calcium entry across the plasma membrane. These principles account for most of the effects of calcium-channel blockers on the cardiovascular system. In vivo, the calcium-channel blockers inhibit contractile function in the heart and vascular smooth muscle and, because the initial depolarizing currents in the sinoatrial and atrioventricular nodes are carried by calcium channels, slow the heart rate and prolong atrioventricular conduction. However, in vivo in human studies, there are differences among the calcium-channel blockers. The vasodilatory effects of the calcium channel blockers, which can reduce systemic blood pressure, offer a primary basis for their potential use in the treatment of hypertension. The tissue specificity exhibited by some of the calcium-channel blockers may enhance their therapeutic value in selected hypertensive patients. Of the three calcium-channel blockers now available for use in the United States (diltiazem, nifedipine, and verapamil), diltiazem and verapamil are approximately equipotent in inhibiting calcium-channel function in cardiac and vascular smooth muscle, whereas nifedipine is more potent in vascular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
Assessing Patient Evaluation Skills: A Structured versus Traditional Approach.

The purpose of the study on which this article is based was to determine differences in interviewing skills between third-year medical students who were provided structured, evaluative feedback and those assessed via traditional feedback methods. Experimental group students received a written assessment for every orthopedic hospital patient worked up, while the control group received traditional assessment feedback. Comparison measures were made based on student performance on a simulated patient examination. Results indicated that students who were provided structured feedback scored significantly higher (p less than .05) than those assessed by traditional assessment means.
Drag reduction and turbulent structure in two- dimensional channel flows

A two-component laser velocimeter has been used to determine the effect of wall strain rate, polymer concentration and channel height upon the drag reduction and turbulent structure in fully developed, low concentration, two-dimensional channel flows. Water flows at equal wall shear stress and with Reynolds numbers from 14430 to 34640 were measured for comparison. Drag reduction levels clearly depended upon wall strain rate, polymer concentration and channel height independently.However, most of the turbulent structure depended only upon the level of drag reduction. The slope of the logarithmic law of the wall increased as drag reduction increased. Similarly, the root-mean-square of the fluctuations in the streamwise velocity increased while the r.m.s. of the fluctuations in the wall-normal velocity decreased with drag reduction. The production of the streamwise normal Reynolds stress and the Reynolds shear stress decreased in the drag-reduced flows. Therefore it appears that the polymer solutions inhibit the transfer of energy from the streamwise to the wall-normal velocity fluctuations. This could occur through inhibiting the newtonian transfer mechanism provided by the pressure-strain correlation. In six drag-reducing flows, the sum of the Reynolds stress and the mean viscous stress was equal to the total shear stress. However, for the combination of highest concentration (5 p.p.m.), smallest channel height (25 mm) and highest wall strain rate (4000 s - 1 ), the sum of the Reynolds and viscous stresses was substantially lower than the total stress indicating the presence of a strong non-newtonian effect. In all drag-reducing flows the correlation coefficient for uv decreased as the axes of principal stress for the Reynolds stress rotated toward the streamwise and wall-normal directions.
Numerical study on the dopant concentration and refractive index profile evolution in an optical fiber manufacturing process

The index of refraction is an important property of optical fibers, since it directly affects the bandwidth and optical loss during information transmission. The refractive index is governed by the dopant concentration distribution across the fiber cross section, which is strongly influenced by the processing conditions. An understanding of the effects of process parameters on the dopant concentration profile evolution is important to design the drawing process for tailored refractive index and optical transmission characteristics. Although the heat and momentum transport in optical fiber drawing have been studied extensively, little has been reported in the open literature on dopant concentration and index of refraction profile development during processing. This paper presents a two-dimensional numerical analysis on the flow, heat and mass transfer phenomena involved in the drawing and cooling process of glass optical fibers using a finite difference approach based on primitive variables. The effects of several important parameters are investigated in terms of nondimensional groups, including: fiber draw speed, inert gas velocity, furnace dimensions, gas properties, and dopant properties on the flow, temperature and dopant concentration distribution.
Taking Parnas's Principles to the Next Level: Declarative Language Design

SequenceL is a general-purpose functional programming language that exploits information hiding in language design, shielding the programmer from the need to know how the language is implemented.
Effects of radar system parameters, population, and environmental modulation on settlement visibility

Abstract. The detectability of settlements and factors influencing their visibility are explored using imagery from two side-looking airborne radar systems. K-band and X-band imagery of diverse areas in the United States are examined to discover the minimum population needed for a settlement to be consistently detected. The percentage of settlements visible by size of population are calculated and omission/commission errors analysed. Particular attention is devoted to the effects of environmental modulation and a near-, mid-, or far-range location, but the factors of scale, resolution, and system are also addressed.
The effectiveness of managerial leadership development programs: A meta‐analysis of studies from 1982 to 2001

Eighty-three studies from 1982 to 2001 with formal training interventions were integrated via meta-analytic techniques to determine the effectiveness of interventions in their enhancement of performance, knowledge, and expertise at the individual, team or group, or organizational level. The studies were separated by research design, with the outcome measure of the intervention as the unit of analysis. The effect size for knowledge outcomes ranged from .96 to 1.37; expertise outcomes from .35 to 1.01; and system outcomes averaged .39. Interventions with knowledge outcomes were found to be more effective than in the Burke and Day (1986) meta-analysis, with the most effective interventions using a single group pretest-posttest research design. Methodological and conceptual differences in Burke and Day's meta-analysis on the effectiveness of managerial training make historical comparisons risky. The data suggest that practitioners can attain substantial improvements in both knowledge and skills if sufficient front-end analysis is conducted to assure that the right development is offered to the right leaders.
Ligand-dependent and -independent processes in B-cell-receptor-mediated signaling.

The B cell antigen receptor (BCR) is a protein complex expressed on the surface of immature and mature B cells. After ligand-induced aggregation, this complex generates signals that lead to a variety of biological outcomes, including survival, proliferation and differentiation. During B cell development intermediate forms of the BCR are expressed on the surface. The composition of these pro- and preBCR complexes reflects the ordered assembly of the BCR complex and they exist to generate signals for positive selection at defined developmental checkpoints. Because these receptors lack the ability to bind conventional ligands, the pro- and preBCR have been postulated to signal via ligand-independent processes. This ligand-inde-pendent or constitutive signal may also play a role in the survival of peripheral mature B cells. Here we discuss the evidence for ligand-independent functions for the BCR and postulate how it may be regulated and linked to biological processes associated with B cell development and survival.
Viral hepatitis as an occupational hazard of dentists

Dentists on the part-time faculty of the University of Southern California School of Dentistry were surveyed to estimate the risk of viral hepatitis for practicing dentists. Measures to reduce the hazard of infection are given. Hepatitis had been diagnosed in 4.5% of 242 respondents to a survey of practicing dentists. Oral surgeons, periodontists, and endodontists had a higher risk than general dental practitioners, and auxiliary personnel had a lower risk. Measures to reduce the hazard are given. To estimate the risk of viral hepatitis for practicing dentists, a questionnaire survey was conducted in the greater Los Angeles area among the part-time faculty of the University of Southern California School of Dentistry. An icteric episode diagnosed as hepatitis had been experienced by 11, representing 3.9% of the 285 dentists to whom questionnaires were mailed or 4.5% of the 242 respondents. All illnesses occurred after graduation from dental school, and five were after 1967. For general dentists, the minimal frequency was 2.7 (5 of 187 in the sample). Specialists with emphasis in surgical forms of dentistry had hepatitis with a significantly higher frequency: 3 of 19 oral surgeons; 1 of 13 periodontists; and 1 of 9 endodontists. The risk did not vary in this sample with the proportion of young adult patients (15 to 29 years of age) in the practice or recognizable illicit self-injection among patients. Auxiliary dental personnel seem to have a lower risk than dentists themselves. Measures to reduce the hazard are indicated, but at present these are confined to greater care in avoiding percutaneous introduction.
Design and testing of a MEMS acoustic emission sensor system

We present four new findings pertaining to MEMS sensors for acoustic emission detection. Our sensors are resonant-type capacitive transducers, operating with a frequency between 100 kHz and 500 kHz, fabricated in the PolyMUMPS process. The sensitivity of a resonant transducer is related to the sharpness of its resonance, measured by the quality factor Q, and operating in a coarse vacuum will increase Q. We describe a practical laboratory method for sealing and evacuating our MEMS sensor, and present measurements showing Q in the evacuated packages to be 2.4 to 3.6 times greater than under atmospheric pressure. We also describe our theoretical analysis of noise sources in the electromechanical behavior of a resonant, capacitive-type transducer sensitive to out-of-plane motion, with particular interest in noise resulting from mechanical excitation of the moving plate by air molecule impact. We report on a new transducer design to sense out-of-plane motion featuring a moving plate constructed as an open grill rather than as a plate perforated by etch holes. Characterization measurements show the open grill design to have a higher Q than a comparable perforated plate transducer. Finally, we report on another novel transducer designed to sense in-plane motion. The sensor is a comb finger capacitive transducer, and theoretical predications predict the in-plane sensor to have a much higher Q than the out-of-plane sensors. We show experimental measurements confirming these design characteristics, and we show results from pencil lead break experiments.
Fever and immunoregulation. III: Hyperthermia augments the primary in vitro humoral immune response

We have examined the possibility that hyperthermia, such as that occurring during fever, may benefit the immune response. The effect of temperature on the in vitro immune response of unprimed murine spleen cells against the antigen sheep erythrocytes was tested. Hyperthermia potently augmented the plaque-forming cell response. Temperature-sensitive events occurred early in the culture period. Subsets of lymphocytes were independently assessed for effects of temperature on their activation and function. We showed that the beneficial effect of elevated temperature on the plaque-forming cell response probably occurs during the priming stage of T helper cells, and neither improves the delivery of help or the activation of B cells, nor impairs suppressor T cell generation or function. We propose that this powerful immunopotentiating effect of hyperthermia may account for the selective value of the fever response. This suggests taht the monokine interleukin 1, which is the endogenous mediator of fever, may promote immune responses both through a direct action on lymphocytes, and indirectly by an action on the central nervous system resulting in fever.
Crack-size dependence of overall responses of fiber-reinforced composites with matrix cracking

Abstract Development of a micromechanics model capable of providing overall macroscopic responses for directionally fiber-reinforced composites undergoing matrix cracking (in terms of microgeometric features) is the principal objective of this paper. It is shown that fiber bridging plays an important role, and the effective moduli of a composite may be significantly influenced by the crack size. Bridging effects are negligible for infinitesimally small cracks (or a → 0), and closed-form effective moduli are obtained via standard micromechanics approach for a hybrid composite system with two distinct inclusion phases (fibers and cracks). When crack size exceeds a threshold value a s ( a s , being the crack size for saturated bridging), the bridging effect is significant, and a closed-form solution for effective moduli is again possible using a self-consistent approach accommodating bridging effects within the micromechanics framework. In the transition regime (0 a a s ), however, the effective moduli become crack-size dependent. A full three-dimensional bridging solution, involving discrete fibers and penny-shaped cracks, is developed to numerically determine the effective moduli in this regime. The procedure also allows numerical determination of the saturated crack size, a s . The important of crack-size dependence is then discussed. It is observed that the effective longitudinal modulus for a silicon carbide reinforced intermetallic may be significantly underestimated by standard micromechanics model. In the transition range (0 a a s ), the present model also provides an avenue for estimation of crack sizes based on observations of overall macro-moduli of damaged composite systems.
Mitochondrial DNA, chloroplast DNA and the origins of development in eukaryotic organisms.

Background Several proposals have been made to explain the rise of multicellular life forms. An internal environment can be created and controlled, germ cells can be protected in novel structures, and increased organismal size allows a "division of labor" among cell types. These proposals describe advantages of multicellular versus unicellular organisms at levels of organization at or above the individual cell. I focus on a subsequent phase of evolution, when multicellular organisms initiated the process of development that later became the more complex embryonic development found in animals and plants. The advantage here is realized at the level of the mitochondrion and chloroplast.
Creep events preceding small to moderate earthquakes on the San Andreas fault

THE San Andreas fault in central California is unusual in that much of the fault displacement occurs as aseismic slip, also known as creep. Changes in creep have been suggested as a possible earthquake precursor1–6, but clear associations between creep changes and subsequent earthquakes are uncommon. Here I report a test of the hypothesis that episodes of rapid creep ('creep events'1–3) precede small to moderate earthquakes on the creeping portion of the San Andreas. The test consists of a comparison of archival creep data to the earthquake catalogue for this area, and an earthquake prediction experiment. Between 1970 and 1994, creep events occurred in the five days preceding half or more of the earthquakes of magnitude > 3.3 in three 1-yr periods of above-average seismic activity. Of five predictions based on the occurrence of creep events between October 1995 and mid-January 1996, four were fulfilled; there were also two 'misses' (earthquakes not preceded by a creep event). If the relationship reported here holds for the entire creeping segment of the San Andreas, and applies to larger earthquakes, these results suggest that a prediction based on precursory creep may be possible at Parkfield, California.
Impurity effects on adhesion: Nb, C, O, B, and S at a Mo/MoSi2 interface.

We report a quantum-mechanical calculation of impurity effects on adhesion between two materials. Adhesive properties of the Mo(001)/${\mathrm{MoSi}}_{2}$(001) heterophase interface with and without monolayers of C, O, B, S, and Nb impurities are calculated using a first-principles local-density-functional approach. Adhesive energies, peak interfacial strengths, and bonding characteristics are found to be strongly dependent upon impurity-atom type. The interfacial spacings increase in proportion to impurity covalent radii. All of the impurities were found to decrease the Mo/${\mathrm{MoSi}}_{2}$ adhesive energy, with S lowering it by approximately a factor of 2. The substitutional impurities S and Nb decrease the peak interfacial strength, while the interstitial impurities C, O, and B increase it. Our results are discussed in terms of experimental results on impurity effects in adhesion and embrittlement in other metallic systems.
VP and VS structure of the Yellowstone hot spot from teleseismic tomography: Evidence for an upper mantle plume

[1] The movement of the lithosphere over a stationary mantle magmatic source, often thought to be a mantle plume, explains key features of the 16 Ma Yellowstone–Snake River Plain volcanic system. However, the seismic signature of a Yellowstone plume has remained elusive because of the lack of adequate data. We employ new teleseismic P and S wave traveltime data to develop tomographic images of the Yellowstone hot spot upper mantle. The teleseismic data were recorded with two temporary seismograph arrays deployed in a 500 km by 600 km area centered on Yellowstone. Additional data from nearby regional seismic networks were incorporated into the data set. The VP and VS models reveal a strong low-velocity anomaly from � 50 to 200 km directly beneath the Yellowstone caldera and eastern Snake River Plain, as has been imaged in previous studies. Peak anomalies are � 2.3% for VP and � 5.5% for VS. A weaker, anomaly with a velocity perturbation of up to � 1.0% VP and � 2.5% VS continues to at least 400 km depth. This anomaly dips 30� from vertical, west-northwest to a location beneath the northern Rocky Mountains. We interpret the low-velocity body as a plume of upwelling hot, and possibly wet rock, from the mantle transition zone that promotes small-scale convection in the upper � 200 km of the mantle and long-lived volcanism. A high-velocity anomaly, 1.2% VP and 1.9% VS, is located at � 100 to 250 km depth southeast of Yellowstone and may represent a downwelling of colder, denser mantle material.