cssi/SciSciGPT-SciSciNet huggingface dataset:
Expression in Escherichia coli of cryptic tetracycline resistance genes from bacteroides R plasmids

The putative clindamycin resistance region of the Bacteroides fragilis R plasmid pBF4 was cloned in the vector R300B in Escherichia coli. This 3.8-kb EcoRI D fragment from pBF4 expressed noninducible tetracycline resistance in E. coli under aerobic but not anaerobic growth conditions. The fragment does not express tetracycline resistance in Bacteroides, a strict anaerobe. The separate tetracycline resistance transfer system in the Bacteroides host strain V479-1 has no homology to the cryptic determinant on pBF4. In addition, this aerobic tetracycline resistance determinant is not homologous to the three major plasmid mediated tetracycline resistance regions found in facultative gram-negative bacteria, represented by R100, RK2, and pBR322. A similar cryptic tetracycline resistance fragment was cloned from pCP1, a separate clindamycin resistance plasmid from Bacteroides that shares homology with the EcoRI D fragment of pBF4. This study identifies cryptic drug resistance determinants in Bacteroides that are expressed when inserted into an aerobically growing organism.
Evolution of Planetary Ringmoon Systems

The last few decades have seen an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of these systems as our intuition (and our computers) catch up with the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems [1–5]. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is an emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system.
Nonlinguistic Learning in Individuals With Aphasia: Effects of Training Method and Stimulus Characteristics

Purpose The purpose of the current study was to explore nonlinguistic learning ability in individuals with aphasia, examining the impact of stimulus typicality and feedback on success with learning...
Present and future of flexible automation: Towards new paradigms

Abstract Automation has been one of the key drivers of the modern Manufacturing Industry and it has been present in various forms from the beginning of the industrial era until today passing through different evolutions responding to human's needs. Therefore automation and the manufacturing industry have undergone several paradigm changes in the last century. They were driven by the market conditions and society needs and were realized by timely developed engineering enabling technologies that fitted the paradigm requirements. This paper maps the different paradigms in terms of market and societal drivers and process technology enablers in order to show a consistent model of paradigm development, a model that links the product, and the process with the appropriate business model. The Flexible Manufacturing Systems (FMS) have been especially analysed as the major enabler to the mass customization paradigm. Summing up, a mapping methodology, able to map all past, present and future production paradigms, is presented. An example on the footwear sector has also been mapped and presented. The analysis is based on a survey conducted in Europe and the USA mechanical industries during 2002. The analysis, carried out within the CIRP Working Group on “Flexible Automation - Assessment and Future” has shown that new paradigms are emerging beyond flexible automation, paradigms that require addressing new technological challenges. Developing these new enabling technologies requires the establishment of new national RTD programmes. Therefore, the role of past national RTD programmes in developing previous enabling technologies that eventually elevated human wealth and life quality is also briefly mentioned. Foresight scenario building and “roadmapping” activities -taking place in different relevant economic regions- are presented. They point to new paradigms and technologies to be developed and call for new RTD programmes to be launched.
Synchronous bilateral invasive breast cancer

Synchronous bilateral invasive breast cancer is a rare event. The etiology of bilateral breast cancer is uncertain, but most evidence supports independent tumors and not metastasis spread from one of the primary tumors. The prognosis of bilateral breast cancer was once thought to be poor, but recent data has suggested a similar survival for bilateral breast cancers as compared to unilateral disease.
The synthesis and crystal and molecular structure of mer-tris(3-trimethylsilyl-2-pyridinethiolato)cobalt(III)

Abstract The room temperature reaction of [Co(H2O)6]Cl2 with 3-trimethylsilyl-2-pyridinethiol in methanol yields [Co(2-SC5H3N-3-SiMe3)3]. The crystal structure determination revealed the meridional ligand arrangement, as previously reported for the analogous [Co(2-SC5H4N]. Crystal data: C24H36N3Si3S3Co, monoclinic space group P21/c, a = 9.416(2), b = 29.163(4), c = 12.371(2) A. β = 106.81(1)°, Z = 4, Dcalc = 1.23 g cm−3; structure solution and refinement based on 1032 reflections with Fo⩾6o(Fo) (Mo Kα, λ = 0.71073 A) converged at R = 0.069.
Safety of Atrial Defibrillation Shocks Synchronized to Narrow and Wide QRS Complexes During Atrial Pacing Protocols Simulating Atrial Fibrillation in Dogs

Background The potential ventricular proarrhythmic effect of atrial defibrillation shocks (ADS) remains a concern with automatic internal atrial defibrillation. Optimal R-wave synchronization alone may not be sufficient to prevent the induction of ventricular fibrillation (VF). Methods and Results The proarrhythmic effect of ADS synchronized to normally conducted QRS complexes (NQRS) and to supraventricular complexes with left or right bundle-branch block (L/RBBB) was investigated in a canine atrial pacing study. Short-long-short, single premature, and burst pacing protocols from the high right atrium were performed at baseline, during isoproterenol infusion, and after intravenous procainamide. The ADS were delivered between decapolar catheters in the coronary sinus and lateral right atrium. They were initially delivered 20 milliseconds (ms) after the end of the last conducted QRS complex and then scanned decrementally through that complex until VF was induced. For NQRS complexes, VF occurred only when th...
Experimenting with French Election Rules: Initial Results

The impact of the French double-ballot is controversial. Some have argued that it performs as a plurality system, while others have said that it mimics a proportional representation system. Still another group says it yields its own unique effect. These conclusions have come from theoretical and observational studies. But no one has presented any real experimental evidence on the question. That is our purpose. We wish to carry out laboratory experiments on electoral outcomes, where the voting groups essentially differ only in the number of times they vote — one-ballot vs two. Here we report the results from two such experimental investigations. They suggest that there are double-ballot effects, namely the encouragement of ideological extremism. Further, these pilots serve as foundation for more extensive experimentation.
7S(1/2) ? 9S(1/2) two-photon spectroscopy of trapped francium.

We report on the spectroscopic measurement of the 210Fr 9S1/2 energy obtained by two-photon excitation of atoms confined and cooled in a magneto-optic trap. The resonant intermediate level 7P3/2 is the upper state of the trapping transition. We have measured the energy difference between the 9S1/2 state and the 7S1/2 ground state to be 25 671.021 ± 0.006 cm−1.
Probing the antioxidant action of selenium and sulfur using Cu(I)-chalcogenone tris(pyrazolyl)methane and -borate complexes.

Hydroxyl radical generated from the reaction of Cu(+) with hydrogen peroxide results in oxidative DNA damage, and this damage is implicated in aging, cancer, and many other diseases. Selenium- and sulfur-containing compounds can act as antioxidants, and coordination of selenium and sulfur to copper is one explanation for this antioxidant activity. To determine how copper coordination results in antioxidant activity, biologically relevant tris(pyrazolyl)methane and borate Cu(+) complexes of the formulas Tp*Cu(L) and [Tpm(R)Cu(L)](+), where (L = N, N'-dimethylimidazole selone, dmise; N, N'-dimethylimidazole thione, dmit; Tp* = hydrotris(3,5-dimethylpyrazolyl)borate; Tpm(R) = tris(pyrazolyl)methane, R = H; Tpm, R = Me; Tpm*, R = iPr; Tpm(iPr)), have been synthesized and characterized. The structures of complexes Tp*Cu(Dmit), Tp*Cu(dmise), [Tpm(R)Cu(dmise)][BF(4)], and [Tpm(R)Cu(Dmit)][BF(4)] (where R = H; Tpm, R = Me; Tpm*, R = iPr; Tpm(iPr)) were determined by X-ray crystallography. All the Cu(+) centers adopt distorted tetrahedral coordination geometry, and Cu-Se and Cu-S distances for all the complexes are approximately 2.30 A, and 2.20 A, respectively. The effects of counterion and steric bulk at the 3 and 5 positions of the pyrazolyl ring on the structural and spectroscopic properties are discussed. Selone or thione coordination to copper significantly alters the Cu(+/2+) redox potential: Cu-selone complexes have Cu(2+/+) potentials from -283 to -390 mV, whereas those of Cu-thione complexes range from 70 to -232 mV versus NHE. The Cu-selone complexes have Cu(2+/+) potentials near or below that of the cellular reductant NADH (-324 mV). Thus, selenium and sulfur coordination to copper in biological systems may prevent the Cu(2+) reduction by NADH required for the catalytic formation of damaging hydroxyl radical.
Limited impact of free ammonia on Nitrobacter spp. inhibition assessed by chemical and molecular techniques

Free ammonia has long been identified as a nitrite oxidation inhibitor. However, past attempts to use this compound to eliminate nitrite oxidation and thereby promote more efficient nitrogen removal strategies during biological wastewater treatment have often failed. Additionally, contradictory results exist in the literature where direct measurements of free ammonia inhibition of nitrite oxidation have been reported. In this study, suspended biomass samples (nitrifier enriched activated sludge) were collected from a bench scale nitrification reactor with Nitrobacter spp. as the dominant nitrite oxidizer and subjected to batch respirometric experiments designed to quantify free ammonia inhibition of nitrite oxidization. A variety of data including ammonia, nitrite, and nitrate conversion rates, oxygen consumption rates, and Nitrobacter ribosomal RNA transcript abundance, a molecular indicator of growth activity, were used to assess nitrite oxidation and growth activity. Both the traditional and molecular activity assessments indicated that free ammonia had a limited inhibitory effect on Nitrobacter spp. In fact, the pH changes necessary to induce high free ammonia concentrations (>10 mg-N/L) had a demonstrably more important inhibiting effect on nitrite oxidation than free ammonia. In contrast, during high ammonia oxidizing activity (5.3 mg-N/L/h), low nitrite oxidation rates (0.2 mg-N/L/h) and severely impaired Nitrobacter spp. growth activity, indicated by a low abundance of the Nitrobacter spp. ribosomal gene transcript relative to the ribosomal gene (0.08), were measured. The findings suggest that pH changes and ammonia oxidizing bacteria activity are more important factors limiting Nitrobacter spp. mediated nitrite oxidation, rather than the free ammonia concentration.
Highly sensitive hydrogen sulfide (H2 S) gas sensors from viral-templated nanocrystalline gold nanowires

A facile, site-specific viral-templated assembly method was used to fabricate sensitive hydrogen sulfide (H2S) gas sensors at room temperature. A gold-binding M13 bacteriophage served to organize gold nanoparticles into linear arrays which were used as seeds for subsequent nanowire formation through electroless deposition. Nanowire widths and densities within the sensors were modified by electroless deposition time and phage concentration, respectively, to tune device resistance. Chemiresistive H2S gas sensors with superior room temperature sensing performance were produced with sensitivity of 654%/ppmv, theoretical lowest detection limit of 2 ppbv, and 70% recovery within 9 min for 0.025 ppmv. The role of the viral template and associated gold-binding peptide was elucidated by removing organics using a short O2 plasma treatment followed by an ethanol dip. The template and gold-binding peptide were crucial to electrical and sensor performance. Without surface organics, the resistance fell by several orders of magnitude, the sensitivity dropped by more than a factor of 100 to 6%/ppmv, the lower limit of detection increased, and no recovery was detected with dry air flow. Viral templates provide a novel, alternative fabrication route for highly sensitive, nanostructured H2S gas sensors.
Plexin-A3 Mediates Semaphorin Signaling and Regulates the Development of Hippocampal Axonal Projections

Plexins are receptors implicated in mediating signaling by semaphorins, a family of axonal chemorepellents. The role of specific plexins in mediating semaphorin function in vivo has not, however, yet been examined in vertebrates. Here, we show that plexin-A3 is the most ubiquitously expressed plexin family member within regions of the developing mammalian nervous system known to contain semaphorin-responsive neurons. Using a chimeric receptor construct, we provide evidence that plexin-A3 can transduce a repulsive signal in growth cones in vitro. Analysis of plexin-A3 knockout mice shows that plexin-A3 contributes to Sema3F and Sema3A signaling and that plexin-A3 regulates the development of hippocampal axonal projections in vivo.
INFLUENCE OF SEX ON CARBOHYDRATE METABOLISM

THAT THERE is a disparity between the liver-glycogen content in the male and female has been known for some time. Thus, Greisheimer (1), studying the effect of various dietary constituents on glycogen formation, found higher concentrations of glycogen in the livers of male rats than in those of females, particularly after the feeding of lard and of glycerol. Likewise, Stohr (2) reported that, with the exception of very old animals, the livers of males consistently maintained a higher level of glycogen after various periods of fasting. Similar differences were observed by Sjogren (3) during the course of an investigation of the diurnal variations in the glycogen content of the livers of male and female rabbits. More recently, Deuel, Gulick, Grunewald and Cutler (4) administered measured amounts of glucose by stomach tube to male and female rats and determined the liver-glycogen content after fasting the animals for o, 24, 48 and 72 hours.
Defoliation responses of western wheatgrass populations with diverse histories of prairie dog grazing.

Photosynthesis and regrowth were compared over a 10-day period following defoliation of about 75% of the tillers of western wheatgrass (Agropyron smithii) plants collected from a black-tailed prairie dog (Cynomys ludovicianus) town and a grazing exclosure at Wind Cave National Park, South Dakota. Prior to defoliation, dog town plants had more tillers, but fewer leaves per tiller, shorter and narrower leaf blades, more horizontal leaves, and higher leaf blade/leaf sheath ratios than plants from the grazing exclosure. Rates of net photosynthesis (PN) did not differ significantly among plants of the two populations, either prior to or following defoliation. From Days 2–10 following defoliation, PN of remaining undamaged leaves averaged 104% of predefoliation rates while PN of similar leaves on non-defoliated plants declined steadily with time. averaging only 79% predefoliation rates during this period. Following defoliation, transpiration rates followed similar trends to CO2 exchange, and rates did not differ between plants of the two populations. Absolute rates of leaf elongation and shoot production were greater in plants from the exclosure. However, defoliation of plants from the exclosure population resulted in a 20% reduction in their cumulative shoot dry weight, while cumulative shoot dry weight of plants from the prairie dog town was not significantly affected by defoliation. This apparent ability of plants from the prairie dog town population to withstand defoliation better than plants from the exclosure was atributed to factors such as the higher leaf blade/leaf sheath ratio and more horizontal leaf angles of plants from the former population.
A baculovirus polyhedral envelope-associated protein: genetic location, nucleotide sequence, and immunocytochemical characterization.

Abstract Using a polyclonal mouse antiserum produced against purified virions of the multicapsid nuclear polyhedrosis virus of Orgyia pseudotsugata (OpMNPV), two immunoreactive λgtII clones were identified which contained nonoverlapping insert DNAs which mapped to a single open reading frame (ORF) in the HindIII-M fragment. Analysis of nucleotide sequence data indicates that this ORF encodes a protein with a MW of 32.4 kDa. A trpE-p32 gene fusion containing the entire p32 ORF was constructed, and the fusion protein was purified and used to immunize rabbits. Western blot analysis and immunofluorescence studies using the anti-TrpE-p32 antiserum detected a polyhedra-derived virus (PDV)-associated protein of 32 kDa at 24 hr postinfection (hr p.i.). The protein was observed in the cytoplasm nuccleus at 24 hr p.i. and became concentrated in the cytoplasm late in infection. Western blot analysis and immunofluorescent microscopy of polyhedra solubilized under various conditions indicated that p32 is associated with the polyhedral envelope. The predicted amino acid sequence for p32 showed 58% amino acid identity with the predicted amino acid sequence for an ORF (ORF 3) in a similar region of the genome of the MNPV of Autographa californica (AcMNPV). The solubility properties of the p32 protein and reciprocal immunoblotting experiments indicate the OpMNPV p32 gene encodes a protein which is homologous to the polyhedral envelope-associated phosphoprotein of AcMNPV, pp34, recently reported by M. A. Whitt and J. S. Manning [(1988) Virology 163, 33–42].
Catalytic amination of methyl tertiary-butyl ether to tertiary-butylamine over pentasil molecular sieves

Abstract Pentasil molecular sieves Catalyze the addition of ammonia to methyl tertiary-butyl ether to give tertiary -butylamine. By-products include methylamines, isobutene (IBE), methanol, and trace amounts of other organic producta. All analyzed products were confirmed through gas chromatography-mass spectrometry identification. The ether amination reaction proceeds under supercritical conditions (> 300 ° C and > 19.3 MPa) in a batch autoclave reactor. A description of the supercritical state reaction thermodynamics is given and compared to that for ammonia and IBE, two other low-cost raw materials for a new Catalytic commercial route to TBA. Details of the reactor and analytical system are reported. The molecular sieve Catalysts are characterized through elemental analyses, powder X-ray diffraction, and variable-temperature Fourier transform infrared spectroscopy with adsorbed ammonia. A plausible Catalytic cycle is presented for amination of a C 4 substrate to give TBA mediated by a molecular sieve surface.
Ovarian Lipoid Cell Tumor: Urinary Steroid Response to Adrenocorticotropin and Chorionic Gonadotropin

ABSTRACT The excretion of 17-hydroxycorticosteroids, total and fractional 17-ketosteroids, pregnanetriol, pregnanediol and testosterone were determined in the urine of a 34-yr-old Negro woman with virilization caused by an ovarian lipoid cell tumor. Urinary levels of 17-ketosteroids (17-KS), androsterone (A) and etiocholanolone (E) were significantly elevated, were not suppressed by dexamethasone, but were augmented by metyrapone, presumably through increased ACTH secretion. Human chorionic gonadotropin (HCG) administration also resulted in a marked increase in 17-KS. Basal levels of pregnanetriol and testosterone glucuronide, significantly above normal, were further elevated by HCG and metyrapone. These findings are interpreted to indicate that the tumor secreted 17-hydroxyprogesterone and an androgen which may have been androstenedione, testosterone or both. 11-Hydroxylase function characteristic of adrenal steroid synthesis was not proved for the tumor, but the increased excretion of pregnanetriol and ...
Role for intracellular proteases in the processing and transport of class II HLA antigens

Abstract Human B-lymphoblastoid cell lines (B-LCL) incubated with the protease inhibitor leupeptin accumulate complexes of class II HLA antigens with a series of Mr 21,000-23,000 basic proteins termed leupeptin-induced proteins (LIP). The appearance of class II antigen-associated LIP coincides with the disappearance of class II antigen-associated invariant (I) chain. Glycopeptides generated by in vitro proteolysis of LIP and I chain using Staphylococcus aureus V8 protease are identical as determined by electrophoresis in sodium dodecyl sulfate. These results suggest that LIP is a proteolytic product derived from the I chain and are consistent with the view that further in vivo proteolysis of LIP by a leupeptin-sensitive enzyme normally facilitates its release from class II antigens. Incubation of B-LCL with monensin, which traps class II antigens and associated I chain in the Golgi apparatus, or chloroquine, which neutralizes intracellular acidic compartments and inhibits I-chain dissociation, blocks the leupeptin-induced appearance of LIP. Treatment of LIP with endoglycosidases F and H shows that both of its N-linked oligosaccharides are in the complex form, indicating that proteolysis of class II antigen-associated I chain to generate LIP occurs in a late-Golgi or post-Golgi compartment. The compartment in which these proteolytic events occur may be identical to the site in macrophages and B lymphocytes where foreign antigens are processed and interact with class II HLA molecules.
Valuing Exit Options

This article examines an important aspect of federalism: the effect of a secession threat on the union's productivity. Productivity requires a compliance maintenance regime with credible punishment. An exit option gives a government the alternative of opting out of the union rather than suffer the disutility of a punishment. Equilibria are characterized over a continuous range of exit option values. The results indicate that only exit options that are superior to union membership improve utility; those of moderate value decrease net and individual government utility due to their harmful effect on compliance maintenance. A prescription that emerges from these results is that if the exit option is inferior to the benefit from a thriving union, member governments should voluntarily submit to measures that make exit as costly as possible. Copyright 2007, Oxford University Press.
A Discussion of the Two-Way Mixed Model

In his text on the analysis of variance, Sheffe (1959) presents a detailed development of the mixed model for two factors. The model, as initially described, appears to be quite general and is capable of accomodating a wide variety of experimental situations in which one factor is assumed fixed and the other random. Other authors have proposed different models which appear to differ from Scheff6's model in various ways. These models have been the subject of considerable discussion, with much of the controversy focusing on the expressions for the expected value of the mean square associated with the random factor. The purpose of this paper is to relate some of the existing models to the Scheffe model in an attempt to provide the user with some guidance in the choice of an appropriate model. The question of the correct expressions for the expected mean squares is also resolved. Although primary consideration is given to the relations between contending, infinite population models, one relation to the limiting form of the finite model is also noted. For ease of reference, the models are formally stated in Section 2. These statements also contain the basic relations between the models. These relations are then discussed in Section 3, and in Section 4, the correct expressions for the expected means squares are given.
Evaluating the Evaluators: Accrediting Knowledge and the Ranking of Political Science Journals

The nature of the scientific enterprise requires that we, as professionals in the discipline of political science, do all we can to improve the quality of our collective endeavors. This means that we must give serious attention to practical concerns about how to evaluate our departments, our scholars in the field, and our individual research. As Christenson and Sigelman (1985, 964) note, "not all ideas win equal acceptance, and neither do all the scholars who generate these ideas or all the institutions that house these scholars." Giles, Mizel, and Patterson (1989, 613) state, "publication in refereed journals is taken as a sine qua non for success in the discipline." It is generally accepted that tenure and promotion decisions, as well as merit salary increases, are heavily influenced by the quantity and quality of articles published in social science journals (Kawar, 1983; Giles, Patterson and Mizell, 1989). In addition, many library professionals are interested in the accreditation of knowledge for practical reasons. They assume that the quality of a journal affects user demand (Christenson and Sigelman, 1985). This recognition has stimulated recent attempts to rank political science journals to assist decisionmakers in evaluating faculty (see, for example, Giles, Mizel, and Patterson 1989) and presumably to assist library personnel in journal selection. In the first generation of research on this issue, two approaches have been used: the "reputational" approach by Giles (1975; 1989) and his colleagues; and the "impact" approach used by Christenson and Sigelman (1985). The reputational approach surveys a representative sample of political scientists and asks them to evaluate selected journals. Respondents are typically asked to rate each journal in terms of the quality of its articles on a scale from 0 to 10 (i.e., poor to outstanding). The impact approach relies on assessing political science journals by ranking them by the number of citations of articles published in a particular year, divided by the total number of articles published (i.e., the ratio of citations to citable items for a given journal; see Christenson and Sigelman, 1985). Whether or not such attempts assist departmental chairpersons, faculty, and librarians depends, in part, on the credibility of the indices. While both of these approaches have been useful in the initial evaluation of a journal's status, they have limitations: they are based on "soft data" of rather limited utility or they are based on criteria too restricted for evaluating a journal's total significance.
Design considerations for infrared imaging radiometers

An error analysis for IR imaging radiometers is summarized. In all, a total of 14 different sources of error are considered in the determination of a total cumulative error. Since the accuracy of a radiometer is the best judge of its usefulness, such an error analysis can be used in the design of an imaging radiometric system. Trade-off studies can be performed in such a way as to minimize the total cumulative error of the system. Examples of how minimizing the total error impacts the design of a number of radiometer sub-systems are presented.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The Crowning of the American Landscape: Eight Great Spaces and Their Buildings

(1989). The Crowning of the American Landscape: Eight Great Spaces and Their Buildings. Journal of Architectural Education: Vol. 42, No. 2, pp. 54-55.
TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT: V. XIPHOPHORUS, PLATYPOECILIUS, AND THEIR HYBRIDS

For the teleosts Xiphophorus montezuma, Platypoecilius maculatus, and their F1 hybrids the temperature characteristics (µ in Arrhenius' equation) are the same for the shift of the low intensity and the high intensity segments of the respective and different flicker response contours (critical intensity I as a function of flash frequency F, with light time fraction constant, at 50 per cent). The value of µ is 12,500 calories or a very little less, over the range 12.5 to 36°. This shows that 1/I can be understood as a measure of excitability, with F fixed, and that the excitability is governed by the velocity of a chemical process common to both the classes of elements represented in the duplex performance curve (rods and cones). It is accordingly illegitimate to assume that the different shapes of the rod and cone branches of the curves are determined by differences in the chemical mechanisms of excitability. It is also forbidden to assume that the differing form constants for the homologous segments in the curves for two forms (X. and P.) are the reflections of a difference in the chemical factors of primary excitability. These differences are determined by statistical factors of the distribution of excitabilities among the elements implicated in the sensory effect vs. intensity function, and are independent of temperature and of the temperature characteristic. It must be concluded that the physicochemical nature of the excitatory process cannot be deduced from the shape of the performance contour. The form constants (σ'log I and Fmax.) for F vs. log I are specifically heritable in F1, although µ is here the same as for X. and P. In an intergeneric cross one cannot in general expect Mendelian simplicity of segregation in subsequent generations, and in the present case we find that F2 individuals are indistinguishable from F1, both as regards F vs. log I and as regards the variation of I within a group of 17 individuals. The result in F2 definitely shows, however, that certain specific statistical form constants for the F-log I contour are transmissible in inheritance. It is pointed out that there thus is provided an instance in which statistical (distribution) factors in performance characteristics involving the summating properties of assemblages of cellular units are heritable in a simple manner without the implication of detectable differences in chemical organization of the units involved. This has an important bearing upon the logic of the theory of the gene.
Learning after the end of knowledge: Instructional technology in the age of interpretive meaning

Raymond G. Taylor is an instructional designer and consultant based in Montreal, Canada. He is developing a self-directed learning technology based on the ideas in his book and is interested in hearing from practitioners interested in participating in preliminary testing. He may be reached at ray.taylor@acorda.ca. Learning After the End of Knowledge: Instructional Technology in the Age of Interpretive Meaning (ISBN: 978–3639024876) is published by VDM Verlag. It is available from Amazon.com, Barnes & Noble, and other online booksellers.
Hierarchical storage systems for on-demand video servers

On-demand video servers based on hierarchical storage system offer high-capacity and low- cost video storage. In such a system, video files are stored in the tertiary level and transferred to the secondary level to be displayed. We have studied the architecture and performance of a hierarchical storage system for an on-demand video server. Our objectives are to understand its performance characteristics, and to design such a server to meet specific application requirements. The secondary level in the hierarchical storage system is characterized by its bandwidth and storage capacity, while the tertiary level is characterized by its number of drives, drive bandwidth and exchange latency. The performance measure we mainly consider here is user delay. We show that, given a certain delay requirement, non-uniform video popularity can reduce the secondary storage requirement tremendously compared with the uniform-popularity case. We also found that secondary bandwidth, secondary storage capacity and tertiary bandwidth can generally be traded with each other to achieve the same average delay performance. However, there is a limit in such 'trade-off.' Furthermore, our study indicates that increasing a system resource (e.g., secondary bandwidth, secondary storage capacity or tertiary bandwidth) in the hierarchical storage system does not always lead to better performance. Therefore, in designing a server based on hierarchical storage system, balancing various system resources is very important. We finally provide some methodologies in designing a server given a certain delay requirement, by taking into account current storage technologies.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The Effect of Uniform Particle Size Distribution on Pt Stability

The present study aims to address the effect of the uniformity of particle size distribution on Pt stability. A theoretical model based on the chemical reactions of Pt oxidation and precipitation in the membrane is presented. The incorporation of a particle size distribution function and a population balance allows the investigation of different initial particle size distributions. Initial results demonstrate the change of platinum ions concentration across the electrode and membrane and reveal the shift of particle size distribution towards larger diameters under potential hold and potential cycling simulations.
Feeding behavior in sexual and clonal strains of Poeciliopsis

Sexual and clonal fish of the genus Poeciliopsis occur together in desert streams of Sonora, Mexico. Their coexistence has been explained in terms of niche partitioning for food and space. We examined predatory behavior that might influence niche relationships, and found significant differences among two coexisting sperm-dependent clonal strains and their two sexual progenitors. Handling time and prey manipulation of free-swimming (Artemia) and benthic (chironomid larvae) prey differed significantly among sexual and clonal strains. Analyses of gut contents from field-collected fish revealed that the laboratory estimates of predatory efficiency were related to their feeding behavior in nature. Behavior differences, such as those described herein, contribute to our understanding of the mechanisms of unisexual/bisexual coexistence in Poeciliopsis.
Sit-to-stand biomechanics of individuals with multiple sclerosis.

Abstract Background It is unclear how people with multiple sclerosis, who often have compromised strength and balance, compare to healthy controls during sit-to-stand movements. The purpose of this study was to compare sit-to-stand biomechanics among three groups: people with multiple sclerosis who exhibit leg weakness, people with multiple sclerosis who have comparable strength to controls, and healthy controls. Methods Twenty-one individuals with multiple sclerosis (n = 10 exhibiting leg weakness: n = 11 exhibiting comparable strength to controls), and 12 controls performed five sit-to-stand trials while kinematic data and ground reaction forces were captured. ANOVAs followed by Tukey's post-hoc tests (α = 0.05) were used to determine group and limb differences for leg strength, movement time, and sagittal-plane joint kinematics and kinetics. Findings Persons with multiple sclerosis exhibiting leg weakness displayed decreased leg strength, greater trunk flexion, faster trunk flexion velocity and decreased knee extensor power compared to the other two groups (p Interpretation Participants with multiple sclerosis exhibiting leg weakness took longer to stand and appeared to use a trunk-flexion movement strategy when performing the sit-to-stand. The majority of group differences appear to be a result of leg extension weakness. Treatment that includes leg strengthening may be necessary to improve sit-to-stand performance for people with multiple sclerosis.
Action Spectrum for Developmental Photo-Induction of the Blue-Green Alga Nostoc muscorum

The dark-grown cyanophyte requires a brief exposure to light from the 650 mµ region of the spectrum before it can complete its developmental cycle. Induction is reversed by exposure to green light. A blue protein, presumably allophycocyanin (absorption maximum, 650 mµ) has been demonstrated in aqueous extracts of the cyanophycean cells.
Implementation of current source inverter for power line conditioning

A current source inverter (CSI) designed to operate as a power line conditioner (PLC) is presented. Only six power switches are required for the CSI. A 5 kVA test model of the CSI has been built using insulated gate bipolar transistors (IGBTs) controlled by a digital signal processor (DSP). To determine system performance, experimental results are compared with computer simulations of an innovative adaptive frequency domain control for pulse width modulated (PWM) switching of the CSI. The adaptive frequency domain control algorithm performs quite well in both steady-state and transient conditions. The steady-state distortion factor of the line current is reduced from 28% to 5% or less. The displacement power factor is corrected from 0.5 lagging to unity. Single cycle PLC response time to a step change in load is demonstrated. >
Virtual wires: overcoming pin limitations in FPGA-based logic emulators

Existing FPGA-based logic emulators only use a fraction of potential communication bandwidth because they dedicate each FPGA pin (physical wire) to a single emulated signal (logical wire). Virtual wires overcome pin limitations by intelligently multiplexing each physical wire among multiple logical wires and pipelining these connections at the maximum clocking frequency of the FPGA. A virtual wire represents a connection from a logical output on one FPGA to a logical input on another FPGA. Virtual wires not only increase usable bandwidth, but also relax the absolute limits imposed on gate utilization. The resulting improvement in bandwidth reduces the need for global interconnect, allowing effective use of low dimension inter-chip connections (such as nearest-neighbor). Nearest-neighbor topologies, coupled with the ability of virtual wires to overlap communication with computation, can even improve emulation speeds. The authors present the concept of virtual wires and describe their first implementation, a 'softwire' compiler which utilizes static routing and relies on minimal hardware support. Results from compiling netlists for the 18 K gate Sparcle microprocessor and the 86 K gate Alewife Communications and Cache Controller indicate that virtual wires can increase FPGA gate utilization beyond 80 percent without a significant slowdown in emulation speed. >
Anomalous Right Coronary Artery and Sudden Cardiac Death

Sudden cardiac death (SCD) in association with anomalous coronary arteries is a rare phenomenon. When described it is most often associated in patients with anomalous left coronary arteries, although anomalous right coronary arteries are incidentally found more frequently.1 Current theories posit ischemia as the etiology of SCD in these patients. The proposed mechanisms of ischemia induced SCD are as follows: (1) acute angulation at the ostium of the coronary artery and kinking; (2) an abnormal slit-like opening; (3) mechanical compression of the anomalous artery if it courses between the aorta and pulmonary artery during exertion; and (4) vasospasm of the anomalous artery.2 ### Case Report A 37-year-old woman with a history of 2 uneventful vaginal deliveries, 2 and 5 years before presentation, experienced a witnessed collapse while in a train station. The patient was found pulseless, and cardiopulmonary resuscitative measures were initiated immediately by bystanders. An automated external defibrillator was applied, and the patient eventually received 1 shock via the automated external defibrillator (Figure 1). Analysis of the automated external defibrillator …
A single amino acid mutation attenuates rundown of voltage‐gated calcium channels

The activity of voltage-gated calcium channels (VGCCs) decreases with time in whole-cell and inside-out patch-clamp recordings. In this study we found that substituting a single amino acid (I1520) at the intracellular end of IIIS6 in the α1 subunit of P/Q-type Ca2+ channels with histidine or aspartate greatly attenuated channel rundown in inside-out patch-clamp recordings. The homologous mutations also slowed rundown of N- and L-type Ca2+ channels, albeit to a lesser degree. In P/Q-type channels, the attenuation of rundown is accompanied by an increased apparent affinity for phosphatidylinositol-4,5-bisphosphate, which has been shown to be critical for maintaining Ca2+ channel activity [L. Wu, C.S. Bauer, X.-G. Zhen, C. Xie, J. Yang, Dual regulation of voltage-gated calcium channels by PtdIns(4,5)P2. Nature 419 (2002) 947–952]. Furthermore, the histidine mutation significantly stabilized the open state, making the channels easier to open, slower to close, harder to inactivate and faster to recover from inactivation. Our finding that mutation of a single amino acid can greatly attenuate rundown provides an easy and efficient way to slow the rundown of VGCCs, facilitating functional studies that require direct access to the cytoplasmic side of the channel.
Hemodynamic Predictors of Myocardial Oxygen Consumption During Static and Dynamic Exercise

Hemodynamic predictors of myocardial oxygen consumption (MVO2) during static and dynamic exercise were examined in ten normal subjects. Studies were done under the following circumstances: 1) during upright bicycle exercise at an average heart rate of 147 beats/min, 2) during static exercise with an isometric load in the left hand equal to 17% of the maximal voluntary contraction (MVC), and 3) during combined dynamic exercise (average heart rate 147 beats/min) and static exercise using 17% MVC of the left hand. Mean myocardial blood flow (MBF) was 181 ml/100 gm LV/min during dynamic exercise, 98 ml/100 gm LV/min during static exercise, and 201 ml/100 gm LV/min during combined static and dynamic exercise. Addition of a static load to the dynamic load resulted in a higher blood pressure (average 12 mm Hg), MVO2 and MBF than during dynamic exercise alone. MVO2 correlated best with products of heart rate and blood pressure regardless of whether the blood pressure was obtained by a central aortic catheter (r =...
Carbon flow to acetate and C1 compounds in northern wetlands

High latitude wetlands are significant sources of atmospheric methane, with emission rates that are susceptible to effects of climate change. Our data demonstrate that unlike mid-latitude wetlands, methane in northern peatlands is not derived from acetate or C1 compounds. These latter compounds accumulate to high levels with acetate as the primary organic end product of anaerobic decomposition. Acetate is ultimately degraded aerobically to carbon dioxide after diffusion into oxic regions of peat. Therefore, organic precursors destined for methane in mid-latitude wetlands are degraded to carbon dioxide in northern wetlands. A warming-induced initiation of acetoclastic methanogenesis could substantially increase methane production.
Volterra filters for perceptual edge extraction

We investigate a class of quadratic Volterra filters, which can be used as computationally efficient edge detectors. Filters from this class are approximately equal to mean-weighted highpass filters, and therefore, they extract fewer edges from dark areas, which is a desirable property for many image enhancement applications. We study the one-dimensional case first and then generalize the results to two dimensions. Since the four-dimensional frequency response yields little insight in the properties of these filters, we also develop a technique for characterizing these filters in a more intuitive way. Using the observation that they map sinusoidal inputs to constant outputs, we employ two-dimensional oriented sinusoids to assess both the frequency characteristics and the degree to which a filter is isotropic, i.e., independent of the input orientation. >
Surjectivity of the Taylor map for complex nilpotent Lie groups

A Hermitian form q on the dual space, g, of the Lie algebra, g, of a simply connected complex Lie group, G, determines a sub-Laplacian, �, on G. Assuming H¨ ormander’s condition for hypoellipticity, there is a smooth heat kernel measure, ρt , on G associated to e t�/ 4 . In a companion paper [6], we proved the existence of a unitary “Taylor” map from the space of holomorphic functions in L 2 (G ,ρ t ) onto J 0 t (a subspace of) the dual of the universal enveloping algebra of g. Here we give a very different proof of the surjectivity of the Taylor map under the assumption that G is nilpotent. This proof provides further insight into the structure of the Taylor map. In particular we show that the finite rank tensors are dense in J 0 t when the Lie algebra is graded and the Laplacian is adapted to the gradation. We also show how the Fourier–Wigner transform produces a natural family of holomorphic functions in L 2 (G ,ρ t ), for appropriate t, when G is the complex Heisenberg group.
Squeakers: a report on real kids using real computers to learn real math

What have Alan Kay and his research team been up to for the past few years? Our Spring issue of ACM Computers in Entertainment will include a report from Alan and his colleagues on their work with children and adults around the globe.In 2001 Kay founded Viewpoints Research Institute, Inc. -- a non-profit organization that serves as the umbrella for further research and development of new learning and media development systems. In 2002 Kay joined the Hewlett-Packard Company as a Sr. Fellow at HP Labs while maintaining the non-profit organization.Alan and his team have been working in their Labs and in classrooms, community-learning centers, and with universities worldwide to continue R&D of Squeak and other collaborative, online learning environments. Look for a report on their work and findings this Spring!For a sneak peek, visit http://www.squeakland.org/sqmedia/movies/html/clips.html
Computer aided analysis of the radio-frequency birdcage resonator

Computer analysis has been used to investigate electrical and physical properties of the birdcage coil used in MRI (magnetic resonance imaging). These studies are based on electrical circuit analysis using SPICE software and on Biot-Savart calculations of the radiated RF field distribution. Significant results include verification of resonance mode peaks according to the Brillouin formula and determination of a nonlinear dependence of RF field homogeneity on number of column elements in the coil. These studies are aimed at providing an improved theoretical understanding of the relation between performance and the electrical and physical parameters of the MRI coil device. >
A kernelized maximal-figure-of-merit learning approach based on subspace distance minimization

We propose a kernelized maximal-figure-of-merit (MFoM) learning approach to efficiently training a nonlinear model using subspace distance minimization. In particular, a fixed, small number of training samples are chosen in a way that the distance between function spaces constructed with a subset of training samples and with the entire training data set is minimized. This construction of the subset enables us to learn a nonlinear model efficiently while keeping the resulting model nearly optimal compared to the model from the whole training data set. We show that the subspace distance can be minimized through the Nystrom extension. Experimental results on various machine learning problems demonstrate clear advantages of the proposed technique over the case where the function space is built with randomly selected training samples. Additional comparisons with the model trained with the entire training samples show that the proposed technique achieves comparable results while reducing training time tremendously.