cssi/SciSciGPT-SciSciNet huggingface dataset:
Initial state resolved electronic spectroscopy of HNCO: Stimulated Raman preparation of initial states and laser induced fluorescence detection of photofragments

Stimulated Raman excitation (SRE) efficiently prepares excited vibrational levels in the ground electronic state of isocyanic acid, HNCO. Photofragment yield spectroscopy measures the electronic absorption spectrum out of initially selected states by monitoring laser induced fluorescence (LIF) of either NCO (X 2Π) or NH (a 1Δ) photofragments. Near threshold, the N–H bond fission is predissociative, and there is well-resolved rotational and vibrational structure in the NCO yield spectra that allows assignment of Ka rotational quantum numbers to previously unidentified vibrational and rotational levels in the ν1 N–H stretch and ν3 N–C–O symmetric stretch fundamentals in the ground electronic state of HNCO. The widths of NCO yield resonances depend on the initial vibrational state, illustrating one way in which initial vibrational state selection influences dissociation dynamics. Initial excitation of unperturbed ν1 (N–H stretch) states leads to diffuse NCO yield spectra compared to excitation of mixed vibra...
Atomic-scale observation of polarization switching in epitaxial ferroelectric thin films

The thin-film x-ray standing wave (XSW) technique is used for an atomic-scale study of polarization switching in ferroelectric Pb(Zr0.3Ti0.7)O3 (PZT)/electrode heterostructures grown on SrTiO3(001). The XSW is selectively generated in the PZT by the interference between the incident x-ray wave and the weak (001) Bragg diffracted wave from the film. The XSW excites a fluorescence signal from the Pb ions in the PZT film, that is used to determine their subangstrom displacements after polarization switching has occurred. This experimental method yields unique information on the underlying atomic configurations for different polarization domain states.
Perineural invasion of prostate carcinoma cells is associated with reduced apoptotic index

BACKGROUND Prostate carcinoma is often associated with perineural (PN) invasion. The common occurrence of this phenomenon has led to speculation regarding the mechanisms of this association, yet to date there have been no studies that clearly define biologic differences between PN and nonperineural (NPN) carcinoma cells. To explore the mechanisms underlying PN invasion by prostate carcinoma cells, the authors investigated the influence of neural components on the growth potential of prostate carcinoma cells. METHODS Proliferative and apoptotic activities of PN and NPN carcinoma cells were analyzed on whole-mount sections of human prostates using immunohistochemical techniques in conjunction with a polyclonal Ki-67 antiserum, and the terminal deoxynucleotidyl transferase (TdT) mediated dUTP biotin nick end labeling (TUNEL) technique, respectively. RESULTS The proliferative index (Ki-67 positive cells per 100 carcinoma cells) of PN carcinoma cells (median, 4.10) was higher than that of their intraprostatic, NPN counterparts (median, 3.25), although the difference was not statistically significant (median difference, 0.38; 95% confidence interval [CI] = −0.99 to 1.32; P = 0.52). In contrast, the apoptotic index (AI = apoptotic bodies per 1000 carcinoma cells) in the NPN carcinoma cells was significantly lower (median, 4.10), than the PN carcinoma cells (median, 7.23) with a median difference of −3.45 (95% CI = −5 to −1.39; P = 0.02). The authors also found that AI was lower in the carcinoma cells surrounding nerves with a large diameter (P = 0.0005). CONCLUSIONS These results suggest that PN invasion by prostate carcinoma cells may not be only a volume effect of growing carcinomas; the neural components may favor the growth of carcinoma cells by inhibiting apoptosis, presumably through a paracrine mechanism, and thereby facilitate the spread of carcinoma cells along nerves. The data also suggest that heterogeneity in growth potential of prostate carcinoma cells may be determined by their local microenvironments, such as an association with neural components. Cancer 1996;78:1267-71.
Identification of a 100‐kDa protein associated with nuclear ribonuclease P activity in Schizosaccharomyces pombe

Ribonuclease P from the fission yeast Schizosaccharomyces pombe has been purified to apparent homogeneity. A purification of 23000-fold was achieved by four fractionation steps with DEAE-cellulose chromatography, phosphocellulose chromatography, glycerol-gradient fractionation and finally tRNA-affinity chromatography. A 100-kDa protein was present in the most pure preparations in amounts approximately stoichiometric with the previously identified RNA components of the enzyme, K1-RNA and K2-RNA [Krupp, G., Cherayil, B., Frendeway, D., Nishikawa, S. & Soll, D. (1986) EMBO J. 5, 1697–1703]. A cross-linking experiment utilizing a 4-thiouridine-substituted precursor tRNA demonstrated that the 100-kDa protein interacts with the ribonuclease P substrate in a specific fashion. We therefore conclude that the protein component of S. pombe ribonuclease P is a 100-kDa protein.
Visions of nature: conflict and compatibility in urban park restoration

Although various disciplines have developed "objective" principles and practices for landscape restoration in recent decades, the concept of restoration itself often rests on subjective questions of cultural value. Issues related to restoring the naturalness of urban open spaces were explored in a planning effort for an area of parkland along Chicago's lakifront. Four different "visions of nature" emerged through dialogue with stakeholders, each emphasizing a different set of characteristics related to the landscape's perceived structure and function as well as its human values and uses: (I) nature as designed landscape, where the concern was to restore the original 1938 naturalistic design for the site by a noted landscape architect; (2) nature as habitat, where individuals sought to restore a hedgerow created during the 1950s that has since become a magnet for migrating birds; (3) nature as recreation, where a variety of interests sought to balance nature restoration goals with the preservation of established recreational activities occurring on and adjacent to the site; and (4) nature as pre-Eut-opean settlement landscape, where individuals sought to restore the site as a reflection of the regional landscape as it may have existed before development of Chicago in the 1830s. It became clear during the course of the effort that the landscape features some individuals sought to restore had attained an iconic status, symbolizing for them meanings and values deeper than what might be discerned by those not intimately knowledgeable of the site and its social context, and that the preservation and enhancement of these features needed to be a central part of any final plan for the site. Trying to maintain these icons in accommodating the various visions of nature did give rise to some conflicts, but stakeholder negotiations also showed how the visions were compatible and how iconic features might "nest" within each other as a result of different scales and locations of concern, Implications for landscape design and management are discussed. Published by Elsevier Science B.V.
Hormone signaling in plant development

Hormone signaling plays diverse and critical roles during plant development. In particular, hormone interactions regulate meristem function and therefore control formation of all organs in the plant. Recent advances have dissected commonalities and differences in the interaction of auxin and cytokinin in the regulation of shoot and root apical meristem function. In addition, brassinosteroid hormones have recently been discovered to regulate root apical meristem size. Further insights have also been made into our understanding of the mechanism of crosstalk among auxin, cytokinin, and strigolactone in axillary meristems.
A new detergent for the solubilization of the vitamin K-dependent carboxylation system from liver microsomes: comparison with triton X-100.

Abstract A new nondenaturing zwitterion detergent has been used to solubilize the vitamin K-dependent carboxylating system from rat liver microsomes. The optimal conditions for solubilization were 1% 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) and 1 m NaCl while maximum carboxylating activity was achieved with 0.5% CHAPS, 0.75 m NaCl for a microsomal protein concentration varying from 7.5 to 10 mg/ml. Using CHAPS, high levels of carboxylase activity can be found not only in liver microsomes from vitamin K-deficient rats, but also in microsomes prepared from the livers of normal animals, normal animals supplemented with vitamin K1, or vitamin K-deficient animals supplemented with vitamin K1, while little if any activity is detected after Triton X-100 solubilization of the microsomes of such livers. Thus, the new zwitterion detergent proves to be more effective and less denaturing in solubilizing the vitamin K-dependent carboxylase from rat liver microsomes than other detergents used in this system.
The determinants of export performance: a review of the empirical literature between 1987 and 1997

Export performance research has proliferated in the last decade. Significant progress has been made in developing better theory and knowledge of the export performance of firms. However, the field of inquiry is characterized by a diversity of conceptual, methodological, and empirical approaches that inhibit the development of clear conclusions regarding the determinants of export performance. In this article, an updated review and synthesis of the empirical literature on determinants of export performance between 1987 and 1997 is offered. Using a combination of the narrative and vote‐counting approaches, 50 studies were identified, reviewed, and synthesized. Major directions for future research are also discussed.
Dimensionality reduction in quadratic discriminant analysis

Abstract One common objective of many multivariate techniques is to achieve a reduction in dimensionality while at the same time retain most of the relevant information contained in the original data set. This reduction not only provides a parsimonious description of the data but, in many cases, also increases the reliability of subsequent analyses of the data. In this paper we consider the problem of determining the minimum dimension necessary for quadratic discrimination in normal populations with heterogeneous covariance matrices. Some asymptotic chi-squared tests are obtained. Simulations are used to investigate the adequacy of the chi-squared approximations and to compare the misclassification probabilities of reduced-dimension quadratic discrimination with full-dimension quadratic discrimination.
The use of neoadjuvant platinum-based chemotherapy in locally advanced breast cancer that is triple negative: retrospective analysis of 144 patients

Triple-negative breast cancers comprise about 20 % of breast cancers. They have poor prognosis and have no standard therapy. The aim of this study was to evaluate pathologic complete response (pCR), progression-free survival (PFS), and overall survival (OS) in patients with TNBC treated with neoadjuvant platinum-based chemotherapy. This is a retrospective study of one hundred and forty-four women with TNBC treated with neoadjuvant platinum-containing chemotherapy for locally advanced breast cancer at the University of Miami between January 1, 1999, and January 1, 2011. The medical record was reviewed to obtain data on clinical characteristics, including ethnicity, race, age, clinical stage, treatment regimen, and vital status. This study was approved by the University of Miami IRB. All patients had locally advanced breast cancer with at least one of the following features at presentation: T3, T4, N2, and N3. The mean tumor size by palpation was 9.4 cm. The clinical T-stage at presentation was 1.4 % T1, 8.3 % T2, 52.8 % T3, and 37.5 % T4 (19.4 % T4d). The nodal status by physical exam at presentation was 23 % N0, 37.5 % N1, 34 % N2, and 5.5 % N3. pCR in breast and axilla was seen in 31 %. PFS and OS were 55 and 59 %, respectively, at 7 years. Cisplatin offered a survival advantage over carboplatin in both PFS (P = 0.007) and OS (P = 0.018). Node positivity was the most important predictor of survival. Cisplatin/docetaxel neoadjuvant therapy was well tolerated and an effective therapy in locally advanced TNB.
Statistical inference based on ranks

This paper develops a unified approach, based on ranks, to the statistical analysis of data arising from complex experimental designs. In this way we answer a major objection to the use of rank procedures as a major methodology in data analysis. We show that the rank procedures, including testing, estimation and multiple comparisons, are generated in a natural way from a robust measure of scale. The rank methods closely parallel the familiar methods of least squares, so that estimates and tests have natural interpretations.
Photoacoustic detection of plasmon surface polaritons in heavily doped polyacetylene films

Abstract We have observed plasmon surface polaritons in heavily doped polyacetylene films using a combined photoacoustic-attenuated total reflection (ATR) method. Photoacoustic techniques were used to detect the non-radiative decay of the plasmon generated in the polyacetylene films in the Kretschmann configuration of ATR. From the data we were able to determine the values of the complex optical dielectric constant ϵ~(ω) of the doped polyacetylene film in the visible region. This combined method offers a direct and convenient way to estimate ϵ~ for such highly reactive films, and can readily be extended to the i.r. region.
Bledta II: Synthesis of a new tumor-visualizing derivative of CO(III)-bleomycin

A new bifunctional chelating agent, (S)-l-(p-bromoacetamidobenzyl) ethylenedinitrilotetraacetic acid, has been prepared from L-phenylalanine. Reaction of the chelating agent with the Co(III) complex of the antitumor antibiotic bleomycin-A2DM was used to generate a new derivative of Co(III)-bleomycin, BLEDTA II. The product can be radiolabeled quickly by binding a radioactive metal ion to the EDTA group. The in vivo distribution of 111 In-BLEDTA II in tumor-bearing mice was determined and found to be indistinguishable from that of the clinically useful 111 In(III)-BLEDTA I complex (J. Med. Chem. 22: 1019 (1979)).
Cdx2 Ectopic Expression Induces Gastric Intestinal Metaplasia in Transgenic Mice

Abstract Background & Aims: Intestinal-type gastric cancer is often preceded by intestinal metaplasia in humans. The genetic events responsible for the transdifferentiation that occurs in intestinal metaplasia are not well understood. Cdx2 , a transcription factor whose expression is normally limited to the intestine, has been detected in gastric intestinal metaplasia. Cdx2 induces differentiation of intestinal epithelial cells in vitro; therefore, we sought to establish whether a causal relationship exists between Cdx2 activation and intestinal metaplasia. Methods: Cdx 2 expression was directed to the gastric mucosa in transgenic mice using cis -regulatory elements of Foxa3 ( Hnf3γ ). Transgenic mice were analyzed for histologic and gene expression changes. Results: Histologic examination of the gastric mucosa of the Foxa3/Cdx2 mice revealed the presence of alcian blue–positive intestinal-type goblet cells, a hallmark of intestinal metaplasia. In addition, Cdx 2 induced the expression of intestine-specific genes. Conclusions: Gastric expression of Cdx 2 alone was sufficient to induce intestinal metaplasia in mice. These mice represent a powerful tool to investigate the molecular mechanisms that promote intestinal metaplasia. Moreover, as gastric cancer in humans is often preceded by intestinal metaplasia, the phenotype described here strongly suggests involvement of Cdx2 in the initiation of the process leading to intestinal neoplasia of the gastric mucosa. GASTROENTEROLOGY 2002;122:689-696
Lattice thermal conductivity in bulk and nanosheet NaxCoO2

Abstract In this paper we present the results of calculations of the lattice thermal conductivity of layered complex metal oxide Na x CoO 2 within the Green–Kubo theory. Using Na x CoO 2 we identify the two competing mechanisms responsible for the favorable scaling properties of the Green–Kubo method for calculating the lattice thermal conductivity. The artificial correlations of the heat flux fluctuations due to the finite size of the supercells are partially cancelled by the missing long wavelength acoustic phonon modes. We compute the lattice thermoelectric properties of bulk Na x CoO 2 with varying stoichiometry, structural defects, and temperature. We also calculate the thermal conductivity of Na x CoO 2 in the nanosheet geometry. While the dependence of thermal conductivity on Na fractions x in the middle range (0.5 x x CoO 2 . However, the weak inter-layer binding also results in the insensitivity of thermal conductivity to the nanosheet thickness.
2D quantum antiferromagnet at low temperatures

Abstract The low-temperature behavior of the two-dimensional spin- 1 2 Heisenberg antiferromagnet is accurately computed through the Monte Carlo method. The energy density behaves as E =−0.6693+0.402 T 3 and the uniform susceptibility χ = 0.0438+0.0322 T +0.0711 T 2 . Comparisons with approximate analytical results are discussed.
Analysis of Parawing Canopy Behavior in Free-Flight Depolyment

An analysis is made of certain parawing data obtained during the deployment of 400and 4000-ft parawing canopies in free flight at dynamic pressures to 100 psf and altitudes to 20,000 ft. Special attention is given to the first reefed stage of deployment because it constrains the minimum load that can be achieved at high dynamic pressure and because structural damage to the fabric was most prevalent in this stage. An improved reefing concept is described, and its flexibility, in terms of meeting various requirements, is discussed.
The concept of parasite-derived resistance—Deriving resistance genes from the parasite's own genome

A broadly-applicable strategy is proposed for genetically engineering resistance to parasites. The strategy involves deriving resistance genes from the genome of the parasite itself. Key gene products from the parasite, if present in a dysfunctional form, in excess, or at the wrong developmental stage, should disrupt the function of the parasite while having minimal affect on the host. Therefore, resistance might be routinely achieved by cloning the appropriate parasite gene, modifying its expression if necessary, and transforming it into the host genome. The QB bacteriophage is used to illustrate, specifically, how parasite-derived resistance might be engineered. Examples are given of pathogen-derived resistance as it already functions in nature, and potential applications of this strategy in agriculture are discussed. The advantages and limitations of parasite-derived resistance are outlined.
Rectal cancer patients benefit from implementation of a dedicated colorectal cancer center in a Veterans affairs medical center

BACKGROUND: A dedicated colorectal cancer (CRC) center was created in a Veterans Affairs Medical Center with the intent of improving quality of patient care and multidisciplinary cooperation. METHODS: Retrospective and prospective databases before and after creation of the CRC center, respectively, were created. Patients entered in each database included those requiring surgical intervention for CRC treatment. Statistical analyses included Fisher's exact, chi-square, and unpaired Student t tests as well as analysis of variance. RESULTS: The overall quality of care of CRC patients has improved as evidenced by a larger percentage of complete, margin-negative resections (P <.05) as well as an increase in the number of lymph nodes excised at surgery (P <.0001). Furthermore, a multidisciplinary approach is clearly beneficial as evidenced by the increased number of CRC patients receiving appropriate multidisciplinary therapy (P <.0001). CONCLUSIONS: A dedicated CRC center has significantly improved quality of care for CRC patients.
The effects of unilateral carotid body excision on ventilatory control in goats.

Abstract The purpose of this study was to determine whether or not unilateral carotid body excision (UCBE) alters normal respiratory control in awake and otherwise intact goats. We measured resting V E and blood gas tensions and pH and ventilatory responses (V R ) to NaCN, dopamine and Doxapram in awake goats before and after UCBE. Resting ventilation, blood gas tensions and pH, and the V R to the above stimuli were not altered by UCBE. During exposure to hypoxia in a hypobaric chamber ( P B =450 Torr ) , PaCO2 in UCBE goats over the first hour, indicating acute hypoxic hyperventilation. During the subsequent 8 h, PaCO2 decreased an additional 5–6 torr, suggesting ventilatory acclimatization to chronic hypoxia (VACH). The response was similar to that observed in intact goats. Acute normoxia following 6 and 8 hr did not completely alleviate the hypocapnia of prolonged hypoxia, further suggesting VACH. We conclude that sufficient redundancy exists in teh inputs from the paired carotid body chemoreceptors so that normal ventilatory responsiveness to acute and chronic stimuli is present in goats possessing only a single carotid body.
Aging chromosome telomeres: parallel studies with terminal repeat and telomere associated DNA probes.

Abstract Human chromosome telomeres consist of tandemly repeated (TTAGGG) n sequences with variant and more complex telomere-associated DNA sequences proximal to the terminal repeats. Terminal restriction fragment (TRF) sizes have been evaluated by Southern blot analysis using a terminal repeat probe, (TTAGGG) 3 that will simultaneously detect all telomeres and with a telomere-associated DNA probe, TelBaml1, that identifies a specific sub-group of chromosome ends. For DNA extracted from in vitro aging fibroblasts, a progressive reduction in the size of the TRFs could be demonstrated using both probes. For both fibroblasts and adult lymphocyte DNA, there were differences in the size of the fragments detected with the two probes. Studies were carried out to determine whether this difference might, in part, be attributable to variability in terminal repeat lengths as well as heterogeneity in the location of terminal restriction enzyme recognition sites. Using the (TTAGGG) 3 probe to identify all telomeres, the terminal repeat lengths from lymphocytes of two adults appeared to be highly variable with sizes upto 20 kb. For the sub-group of telomeres identified by TelBaml1 the terminal repeat lengths were estimated to be 2–4 kb and appeared to show relatively little size diversity. If it assumed that the molecular weights of the DNA fragments identified in these studies do accurately reflect individual telomere structures, then it can be concluded that some specific telomere repeat arrays are substantially shorter than others. Variation in terminal repeat length may be related to the extent that telomeres participate in chromosome rearrangement.
A model for high-pressure ultrafiltration of blood.

A semi-analytic model to predict the permeate flux during high-pressure ultrafiltration of blood with highly permeable membranes is proposed. This model explicitly considers the hydraulic resistance of the retained particles that limits the flux. An empirically derived relationship between particle surface concentration and hydraulic resistance is used. This model incorporates the axial variations in blood cell and solute surface concentrations (or concentration polarization), shear-induced diffusion coefficient for the blood cells, effective diffusion coefficient for the blood solutes, hydraulic (lumen) pressure, and flow rate. This model agrees well with experimental results in the pressure-independent filtration flux region.
Frequency Measures of Behavior for Assistive Technology and Rehabilitation

Documenting assistive technology outcomes has grown in importance, but outcome measurement remains problematic. A new approach uses natural science measures and a model (selectionism) from the field of Behavior Analysis. Selectionism defines behaviors by their effects (functional performance) and the environment (including technology) within which they occur, and explicitly treats variation in patterns of behavior over time for individuals (intervention effects). Its basic metric is frequency of behaviors (count per unit time) which is similar to robust engineering measures like centimeters, grams, and seconds. This approach eliminates many of the problems inherent to more traditional psychometrics. Selectionism based on frequencies also provides an empirical structure or taxonomy to organize efforts and outcomes, unified by the notion of fluency. Composite behaviors are combinations of smaller component behaviors that are required for performance of the composite. A frequency above which a component beha...
Corpus Callosum Maturation and Line Bisection Performance in Healthy Children

Line bisection performance in children has been hypothesized to be a measure of corpus callosum maturation. Several previous studies have shown that normal prepubescent children bisect lines to the right of true center with their right hand and to the left with their left hand (symmetrical neglect). In contrast, children entering puberty reportedly bisect lines to the left with both the right and left hands (pseudoneglect). The shift from symmetrical to pseudoneglect has been hypothesized to reflect corpus callosum maturation and its involvement in the transfer of attention-based visuospatial processes. In the current study, line bisection performance and MR quantitative corpus callosum volumes were examined in 46 healthy children ages 8-18 years. A linear relationship between corpus callosum volume and age was found. However, the expected age-contingent line bisection performance pattern was not observed. In addition to the expected two patterns of line bisection bias, pseudoneglect and symmetric neglect, two additional distinct patterns of line bisection were identified. These findings, and other findings in the literature, raise important questions about the reliability and validity of the line bisection test. No relationship was found between corpus callosum volume and amount or direction of line bisection deviation. Our findings do not support previous hypotheses regarding line bisection-corpus callosum relationship.
Preparation of quaternized organic–inorganic hybrid brush polyphosphazene-co-poly[2-(dimethylamino)ethyl methacrylate] electrospun fibers and their antibacterial properties

Densely grafted star- and comb-shaped molecular brushes composed of poly[2-(dimethylamino)ethyl methacrylate] were prepared via atom transfer radical polymerization (ATRP) using either cyclotriphosphazenes or polyphosphazenes as initiators. The grafting conditions were optimized in order to obtain well controlled brush structures. The kinetics of the reactions were first-order with respect to the monomer concentration in both cyclotriphosphazene and polyphosphazene systems. The resultant star- and comb-shaped brushes were quaternized with iodomethane, iodobutane, iodoheptane, iododecane and iodododecane, and the products were characterized by NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Electrospinning of the quaternized brushes gave rise to microfibers with diameters in range of 700 nm to 1.1 μm, evidenced by scanning electron microscopy (SEM). The antibacterial activity of the quaternized brush species in both aqueous solution and as fibrous solids against Escherichia coli (E. coli) has been evaluated. In aqueous solution, star-shaped brushes quaternized with iodoheptane showed the best antibacterial effect, with a minimum inhibitory concentration (MIC) as low as 250 μg mL−1. In the fibrous solid state, more than 99% of E. coli were killed within 2 h after contacting 100 mg of microfibers electrospun from the star-shaped brush polymers quaternized with either iododecane or iodododecane.
Nox Enzymes and New Thinking on Reactive Oxygen: A Double-Edged Sword Revisited

Reactive oxygen species (ROS) are a chemical class of molecules that have generally been conceptualized as deleterious entities, albeit ones whose destructive properties could be harnessed as antimicrobial effector functions to benefit the whole organism. This appealingly simplistic notion has been turned on its head in recent years with the discovery of the NADPH oxidases, or Noxes, a family of enzymes dedicated to the production of ROS in a variety of cells and tissues. The Nox-dependent, physiological generation of ROS is highly conserved across virtually all multicellular life, often as a generalized response to microbes and/or other exogenous stressors. This review discusses the current knowledge of the role of physiologically generated ROS and the enzymes that form them in both normal biology and disease.
The Analysis of a Statistical Multiplexer with Nonindependent Arrivals and Errors

Most stochastic models for discrete time statistical multiplexers make the assumption that 1) arrivals are governed by a Bernoulli process and that 2) transmission errors or multiplexer failures are described by an independent error process. We study a multiplexer operating in a two state Markovian environment in which each state is characterized by its own Bernoulli arrival process and independent error process. We derive the probability generating function for the queue length distribution for such a system. We also consider two special cases of this model. One referred to as the saturated arrival model corresponds to a system in which during one of the two states, the saturated state, at least one arrival occurs during each discrete time unit. The other model, the breakdown model, corresponds to a system in which during one of the two states, the breakdown state, the multiplexer is inoperative. For both models, we generalize the analysis to cases in which the durations of the saturated state and breakdown state may take on values described by arbitrary distributions. Finally, we study the effects of different arrival processes and error processes on queue length behavior.
Quantifying the energetic interplay of RNA tertiary and secondary structure interactions.

To understand the RNA-folding problem, we must know the extent to which RNA structure formation is hierarchical (tertiary folding of preformed secondary structure). Recently, nuclear magnetic resonance (NMR) spectroscopy was used to show that Mg 21 -dependent tertiary interactions force secondary structure rearrangement in the 56-nt tP5abc RNA, a truncated subdomain of the Tetrahymena group I intron. Here we combine mutagenesis with folding computations, nondenaturing gel electrophoresis, high-resolution NMR spectroscopy, and chemical-modification experiments to probe further the energetic interplay of tertiary and secondary interactions in tP5abc. Point mutations predicted to destabilize the secondary structure of folded tP5abc greatly disrupt its Mg 21 -dependent folding, as monitored by nondenaturing gels. Imino proton assignments and sequential NOE walks of the two-dimensional NMR spectrum of one of the tP5abc mutants confirm the predicted secondary structure, which does not change in the presence of Mg 21 . In contrast to these data on tP5abc, the same point mutations in the context of the P4‐P6 domain (of which P5abc is a subdomain) shift the Mg 21 dependence of P4‐P6 folding only moderately, and dimethyl sulfate (DMS) modification experiments demonstrate that Mg 21 does cause secondary structure rearrangement of the P4‐P6 mutants’ P5abc subdomains. Our data provide experimental support for two simple conclusions: (1) Even single point mutations at bases involved only in secondary structure can be enough to tip the balance between RNA tertiary and secondary interactions. (2) Domain context must be considered in evaluating the relative importance of tertiary and secondary contributions. This tertiary/secondary interplay is likely relevant to the folding of many large RNA and to bimolecular snRNA‐snRNA and snRNA‐intron RNA interactions.
Genetically distinct pathways guide effector export through the type VI secretion system

Bacterial secretion systems often employ molecular chaperones to recognize and facilitate export of their substrates. Recent work demonstrated that a secreted component of the type VI secretion system (T6SS), hemolysin co-regulated protein (Hcp), binds directly to effectors, enhancing their stability in the bacterial cytoplasm. Herein, we describe a quantitative cellular proteomics screen for T6S substrates that exploits this chaperone-like quality of Hcp. Application of this approach to the Hcp secretion island I-encoded T6SS (H1-T6SS) of Pseudomonas aeruginosa led to the identification of a novel effector protein, termed Tse4 (type VI secretion exported 4), subsequently shown to act as a potent intra-specific H1-T6SS-delivered antibacterial toxin. Interestingly, our screen failed to identify two predicted H1-T6SS effectors, Tse5 and Tse6, which differ from Hcp-stabilized substrates by the presence of toxin-associated PAAR-repeat motifs and genetic linkage to members of the valine-glycine repeat protein G (vgrG) genes. Genetic studies further distinguished these two groups of effectors: Hcp-stabilized effectors were found to display redundancy in interbacterial competition with respect to the requirement for the two H1-T6SS-exported VgrG proteins, whereas Tse5 and Tse6 delivery strictly required a cognate VgrG. Together, we propose that interaction with either VgrG or Hcp defines distinct pathways for T6S effector export.
Multiple Effects of Trehalose on Protein Folding In Vitro and In Vivo

Abstract The disaccharide trehalose is produced in large quantities by diverse organisms during a variety of stresses. Trehalose prevents proteins from denaturing at high temperatures in vitro, but its function in stress tolerance in vivo is controversial. We report that trehalose stabilizes proteins in yeast cells during heat shock. Surprisingly, trehalose also suppresses the aggregation of denatured proteins, maintaining them in a partially-folded state from which they can be reactivated by molecular chaperones. The continued presence of trehalose, however, interferes with refolding, suggesting why it is rapidly hydrolyzed following heat shock. These findings reconcile conflicting reports on the role of trehalose in stress tolerance, provide a novel tool for accessing protein folding intermediates, and define new parameters for modulating stress tolerance and protein aggregation.
Enhancement of creativity via free-imagery and hypnosis.

Abstract Thirty-six male, highly susceptible subjects, divided into hypnosis, simulation and waking groups, were given the Torrance Test of Creativity with modified instructions requiring them to wait passively for visual images in response to the test stimuli. Twelve waking subjects received the same test under standard instructions. The hypnotized group scored higher than all control groups on over-all creativity and on Figural creativity, but not on Verbal creativity. The results seem to support the application of the ego-analytic concept of “adaptive regression” to both hypnosis and creativity. They also seem to confirm the association found between hypnosis and the activation of the non-verbal cerebral hemisphere.
NEURAL AND PHOTOCHEMICAL MECHANISMS OF VISUAL ADAPTATION IN THE RAT.

The effects of light adaptation on the increment threshold, rhodopsin content, and dark adaptation have been studied in the rat eye over a wide range of intensities. The electroretinogram threshold was used as a measure of eye sensitivity. With adapting intensities greater than 1.5 log units above the absolute ERG threshold, the increment threshold rises linearly with increasing adapting intensity. With 5 minutes of light adaptation, the rhodopsin content of the eye is not measurably reduced until the adapting intensity is greater than 5 log units above the ERG threshold. Dark adaptation is rapid (i.e., completed in 5 to 10 minutes) until the eye is adapted to lights strong enough to bleach a measurable fraction of the rhodopsin. After brighter light adaptations, dark adaptation consists of two parts, an initial rapid phase followed by a slow component. The extent of slow adaptation depends on the fraction of rhodopsin bleached. If all the rhodopsin in the eye is bleached, the slow fall of threshold extends over 5 log units and takes 2 to 3 hours to complete. The fall of ERG threshold during the slow phase of adaptation occurs in parallel with the regeneration of rhodopsin. The slow component of dark adaptation is related to the bleaching and resynthesis of rhodopsin; the fast component of adaptation is considered to be neural adaptation.
A Hopfield network for solving a complex scheduling problem in behavioral synthesis

Hopfield type neural networks have shown success in solving hard optimization problems. As problems become more complex, it is increasingly difficult to find a suitable encoding of constraints into an energy function, which will effectively guide the network to a desired solution. This paper describes how a difficult scheduling problem was encoded into a Hopfield type neural network, and reports the results. The neural network devised is one of the most complex ones to date.
Regulation of stalk and spore antigen expression in monolayer cultures of Dictyostelium discoideum by pH

The terminal differentiation of Dictyostelium discoideum cells plated as monolayers with cyclic AMP is dramatically affected by developmental buffer conditions. High pH and addition of weak bases induces spore differentiation while low pH and weak acids favour stalk cell formation. In order to analyse the timing and nature of this regulation we have raised and characterized an anti-stalk serum which we have used together with an anti-spore serum to monitor developmental progression in the monolayer system and to detect the phenotypic effects of pH at earlier stages of development. The stalk serum detects both polysaccharide and protein antigens expressed during the terminal stages of normal development. In monolayer culture, the stalk-specific protein antigen appears precociously, while the timing of prespore vacuole appearance is unaffected. Expression of stalk polysaccharide antigens in monolayer cultures occurs as early as 12 h and is localized in a single subset of cells or region of extracellular space within the small cell clumps that form. The effects of pH (and acid/base) on these phenotype-specific antigens can be detected early in development, shortly after their first appearance. In monolayers of wild-type V12 M2 cells, the low pH regimes appear to act more by suppressing the spore than enhancing the stalk pathway, while the high pH regimes both suppress stalk and enhance spore antigen expression. In monolayers of the sporogenous mutant HM29, low pH regimes both enhance stalk antigen and suppress spore antigen expression. These results show that extracellular pH regulates phenotypic expression during a large part of the differentiation process and is not simply restricted to terminal cytodifferentiation.
Strong shocks in nonisentropic gas dynamics

Abstract In nonisentropic gas dynamics, with general equations of state, strong com-pressive shocks satisfying the Liu E-condition may violate the Second Law of thermodynamics.
Oral health activities of Early Head Start teachers directed toward children and parents

Objectives: This cross-sectional study examined Early Head Start (EHS) teachers' oral health program activities and their association with teacher and program characteristics. Methods: Self-completed questionnaires were distributed to the staff in all EHS programs in North Carolina. Variables for dental health activities for parents (four items) and children (four items) were constructed as the sum of responses to a 0-4 Likert-type scale (never to very frequently). Ordinary least squares regression models examined the association between teachers' oral health program activities and modifiable teacher (oral health knowledge, values, self-efficacy, dental health training, perceived barriers to dental activities) and program (director and health coordinator knowledge and perceived barriers to dental activities) characteristics. Results: Teachers in the parent (n = 260) and child (n = 231) analyses were a subset of the 485 staff respondents (98 percent response rate). Teachers engaged in child oral health activities (range = 0-16; mean = 9.0) more frequently than parent activities (range = 0-16; mean = 6.9). Teachers' oral health values, perceived oral health self-efficacy, dental training, and director and health coordinator knowledge were positively associated with oral health activities (P < 0.05). Perceived barriers were negatively associated with child activities (P < 0.05). Conclusion: The level of oral health activity in EHS programs is less than optimal. Several characteristics of EHS staff were identified that can be targeted with education interventions. Evidence for effectiveness of EHS interventions needs to be strengthened, but results of this survey provide encouraging findings about the potential effects of teacher training on their oral health practices.
A Partial History of Planning Workshops: The Experience of Ten Schools from 1955 to 1984:

This paper examines the changing role of the workshop or studio course in the planning curriculum over the period of 1955 to 1984 Telephone interviews were conducted with twenty faculty members at ten of the sixteen schools which had established Masters degrees in 1955 It was found that the central element of the curriculum in 1955 at all ten schools was a sequence of two or three workshops After 1960 there was a decline in the number of workshops at most schools, and some curricula dropped the workshop as a requirement in the 1970s The emergence of three diverse roles is analyzed for the workshop by 1984 Trends in five aspects of the workshop activity — workshop requirements, workshop objectives, faculty role, the use of clients, and space allocation — are examined Reasons for the changes between 1955 and the present are suggested
Dimorphic Mating-Type Chromosomes in the Fungus Microbotryum violaceum

Fungi often mate as haploids, and sex chromosomes (i.e., mating-type chromosomes) that are dimorphic for their size or overall DNA content have never been reported in this kingdom. Using electrophoretic techniques for karyotype analysis, a highly dimorphic chromosome pair that determines mating compatibility is shown to occur in populations of the fungus Microbotryum violaceum. This substantiates the evolution of such dimorphism as a general feature associated with haploid determination of mating compatibility, which previously had been known only in haplodioecious plants (mosses and liverworts). Size-dimorphic sex chromosomes are present in a lineage of M. violaceum native to Europe, as well as a lineage native to North America. However, they are very different in size between these lineages, indicating either independent evolution of the dimorphism or a large degree of divergence since their isolation. Several DNA sequences that show sequence similarity to transposons were isolated from these sex chromosomes.
Noninvasive measurement of the tension-time index in children with neuromuscular disease.

Respiratory muscle weakness is common in children with neuromuscular disease (NMD). We hypothesized that weakness puts them at risk for respiratory muscle fatigue, a harbinger of chronic respirator...
A new index of glacier area change: a tool for glacier monitoring

Since the mid-19th century, most glaciers have been losing area and volume. This loss of area has not been homogeneous in time and space, and direct observations are sparse, making regional and global estimates of glacier change difficult. This paper focuses on developing a single index for monitoring glacier change, one that would be particularly useful for remote-sensing applications. We combine the results of direct glacier mass-balance observations B, total glacier area S and accumulation area Sc derived from maps or remotely sensed images. Using the accumulation-area ratio (AAR = Sc/S), we note the differences between observed AAR, time-averaged AAR hi and the equilibrium state AAR0, as determined by its value at B = 0 from a regression of B(AAR). We suggest that d = ( AAR hi - AAR0)/ AAR0 quantifies the difference between the currently observed state of glaciers and their equilibrium state and measures the delay in the dynamic response of S relative to the climatic response of Sc. Using all available observations for the period 1961-2004, d � -65% for tropical glaciers, which implies their rapid shrinkage as S continues to decrease and 'catch up' with Sc. During the same period, mid- latitude and polar glaciers show less negative values of d. Of 86 glaciers from all latitudes and regions, only 11 show positive d at any time between 1961 and 2004. Averaged over 1961-2004, d is -15.1 � 2.2%, and B hi is -360 � 42 mm a -1 w.e. Values for AAR0 range between about 40% and 80%, but the bulk of the equilibrium values are between 50% and 60%. The average AAR0 is 57.9 � 0.9% and has remained stable over time (the equilibrium AAR has not changed with climate). Overall, the observed negative d suggests a committed retreat of glaciers and their continuing contribution to sea level even if global temperature is held constant.
Earth's 2006 Encounter with Comet 73P/Schwassmann-Wachmann: Products of Nucleus Fragmentation Seen in Closeup

The large numbers of nucleus fragments observed are a spectacular illustration of the process of cascading fragmentation in progress, a concept introduced to interpret the properties of the Kreutz system of sungrazers and comet D/1993 F2. The objective is to describe the fragmentation sequence and hierarchy of comet 73P, the nature of the fragmentation process and observed events, and the expected future evolution of this comet. The orbital arc populated by the fragments refers to an interval of 3.74 days in the perihelion time. This result suggests that they all could be products (but not necessarily first-generation fragments) of two 1995 events, in early September (involving an enormous outburst) and at the beginning of November. The interval of perihelion times is equivalent to a range of about 2.5 m/s in separation velocity or 0.00012 the Sun's attraction in nongravitational deceleration. Their combined effect suggests minor orbital momentum changes acquired during fragmentation and decelerations compatible with survival over two revolutions about the Sun. Fragment B is a likely first-generation product of one of the 1995 events. From the behavior of the primary fragment C, 73P is not a dying comet, even though fragment B and others were episodically breaking up into many pieces. Each episode began with the sudden appearance of a starlike nucleus condensation and a rapidly expanding outburst, followed by a development of jets, and a gradual tailward extension of the fading condensation, until the discrete masses embedded in it could be resolved. In April-May, this debris traveled first to the southwest, but models show their eventual motion toward the projected orbit. Fainter fragments were imaged over limited time, apparently because of their erratic activity (interspersed with periods of dormancy) rather than improptu disintegration. A dust trail joining the fragments and reminiscent of comet 141P/Machholz suggests that cascading fragmentation exerts itself profoundly over an extremely broad mass range of particulate debris.