cssi/SciSciGPT-SciSciNet huggingface dataset:
DNA unwinding heterogeneity by RecBCD results from static molecules able to equilibrate

Single-molecule studies can overcome the complications of asynchrony and ensemble-averaging in bulk-phase measurements, provide mechanistic insights into molecular activities, and reveal interesting variations between individual molecules. The application of these techniques to the RecBCD helicase of Escherichia coli has resolved some long-standing discrepancies, and has provided otherwise unattainable mechanistic insights into its enzymatic behaviour. Enigmatically, the DNA unwinding rates of individual enzyme molecules are seen to vary considerably, but the origin of this heterogeneity remains unknown. Here we investigate the physical basis for this behaviour. Although any individual RecBCD molecule unwound DNA at a constant rate for an average of approximately 30,000 steps, we discover that transiently halting a single enzyme-DNA complex by depleting Mg(2+)-ATP could change the subsequent rates of DNA unwinding by that enzyme after reintroduction to ligand. The proportion of molecules that changed rate increased exponentially with the duration of the interruption, with a half-life of approximately 1 second, suggesting that a conformational change occurred during the time that the molecule was arrested. The velocity after pausing an individual molecule was any velocity found in the starting distribution of the ensemble. We suggest that substrate binding stabilizes the enzyme in one of many equilibrium conformational sub-states that determine the rate-limiting translocation behaviour of each RecBCD molecule. Each stabilized sub-state can persist for the duration (approximately 1 minute) of processive unwinding of a DNA molecule, comprising tens of thousands of catalytic steps, each of which is much faster than the time needed for the conformational change required to alter kinetic behaviour. This ligand-dependent stabilization of rate-defining conformational sub-states results in seemingly static molecule-to-molecule variation in RecBCD helicase activity, but in fact reflects one microstate from the equilibrium ensemble that a single molecule manifests during an individual processive translocation event.
The mystery of gold's chemical activity: local bonding, morphology and reactivity of atomic oxygen

Recently, gold has been intensely studied as a catalyst for key synthetic reactions. Gold is an attractive catalyst because, surprisingly, it is highly active and very selective for partial oxidation processes suggesting promise for energy-efficient “green” chemistry. The underlying origin of the high activity of Au is a controversial subject since metallic gold is commonly thought to be inert. Herein, we establish that one origin of the high activity for gold catalysis is the extremely reactive nature of atomic oxygen bound in 3-fold coordination sites on metallic gold. This is the predominant form of O at low concentrations on the surface, which is a strong indication that it is most relevant to catalytic conditions. Atomic oxygen bound to metallic Au in 3-fold sites has high activity for CO oxidation, oxidation of olefins, and oxidative transformations of alcohols and amines. Among the factors identified as important in Au–O interaction are the morphology of the surface, the local binding site of oxygen, and the degree of order of the oxygen overlayer. In this Perspective, we present an overview of both theory and experiments that identify the reactive forms of O and their associated charge density distributions and bond strengths. We also analyze and model the release of Au atoms induced by O binding to the surface. This rough surface also has the potential for O2 dissociation, which is a critical step if Au is to be activated catalytically. We further show the strong parallels between product distributions and reactivity for O-covered Au at low pressure (ultrahigh vacuum) and for nanoporous Au catalysts operating at atmospheric pressure as evidence that atomic O is the active species under working catalytic conditions when metallic Au is present. We briefly discuss the possible contributions of oxidants that may contain intact O–O bonds and of the Au–metal oxide support interface in Au catalysis. Finally, the challenges and future directions for fully understanding the activity of gold are considered.
Cell proliferation on hydrogels.

The adhesion and proliferation of mammalian fibroblasts (Flow 7000) on the surface of hydrophilic (copolymer ofN-vinyl-2-pyrrolidone and methyl methacrylate) and hydrophobic [polymethylmethacrylate (PMMA) stereocomplex] hydrogels with a wide range in water content were studied morphologically and quantitatively. It was demonstrated that cell proliferation on hydrogels by a static culture method decreased as the water content of the gels increased. However, it is remarkable that the cell proliferation on PMMA hydrogels with a high water content is equivalent to that on glass Petri dishes. The results obtained in the proliferation of cells on the surface of these hydrogels closely correspond to the state of cell adhesion. When fresh medium or air was perfused from the popposite side of the PMMA hydrogel membrane on which the cells were proliferating (perfusion method), the cells continued to grow into a higher density than with the conventional static culture method. In the case of fresh medium perfusion, the amount of proliferated cell was dependent on both the permeability of the membrane and the density of the membrane “scaffolding”. Virus multiplication in the cultured cells increased in proportion to the cell density, whereas the cell function was similar in both culture methods.
On Education and Geographers: The Role of Cognitive Developmental Theory in Geographic Education

Abstract The current focus on geographic ignorance within the discipline and within the mass media offers another opportunity to reform the teaching of geography at all grade levels. Previous reforms have met with little success. We argue that current efforts will succeed only if we integrate ideas from geography, child development, and education. Programs of geographic education must link geographic content with an understanding of the nature of the learner and with the expectations and knowledge of the teacher. We illustrate this argument using the Guidelines for Geographic Education: Elementary and Secondary Schools (1984). The concept of a map is central to the Guidelines: of 30 suggested learning outcomes for kindergarten through second grade, 13 depend upon understanding maps. We explore early map understanding by linking Piagetian developmental theory, cartographic theory, and educational practice. We discuss empirical data on the young child's (1) understanding of maps as graphic representations, ...
Cell Cycle Re-Entry and Mitochondrial Defects in Myc-Mediated Hypertrophic Cardiomyopathy and Heart Failure

While considerable evidence supports the causal relationship between increases in c-Myc (Myc) and cardiomyopathy as a part of a “fetal re-expression” pattern, the functional role of Myc in mechanisms of cardiomyopathy remains unclear. To address this, we developed a bitransgenic mouse that inducibly expresses Myc under the control of the cardiomyocyte-specific MHC promoter. In adult mice the induction of Myc expression in cardiomyocytes in the heart led to the development of severe hypertrophic cardiomyopathy followed by ventricular dysfunction and ultimately death from congestive heart failure. Mechanistically, following Myc activation, cell cycle markers and other indices of DNA replication were significantly increased suggesting that cell cycle-related events might be a primary mechanism of cardiac dysfunction. Furthermore, pathological alterations at the cellular level included alterations in mitochondrial function with dysregulation of mitochondrial biogenesis and defects in electron transport chain complexes I and III. These data are consistent with the known role of Myc in several different pathways including cell cycle activation, mitochondrial proliferation, and apoptosis, and indicate that Myc activation in cardiomyocytes is an important regulator of downstream pathological sequelae. Moreover, our findings indicate that the induction of Myc in cardiomyocytes is sufficient to cause cardiomyopathy and heart failure, and that sustained induction of Myc, leading to cell cycle re-entry in adult cardiomyocytes, represents a maladaptive response for the mature heart.
25 years ago

This letter to the editor is reprinted from IEEE Control Systems Magazine, vol. 4, p. 30, May 1984. Contributed by Kent Lundberg.
Driver Behavior at Vehicle Arresting Barriers: Compliance and Violations During the First Year at the McLean Site

Compliance and violation behavior of drivers at one of three vehicle arresting barriers (VABs) in Illinois is presented. VABs are traffic control and safety devices that function as an impenetrable barrier to highway vehicles at railroad grade crossings on high-speed passenger rail corridors. Driver behavior on approach and at the VABs is analyzed to determine compliance and violation behaviors regarding this new device and related signage and signals. During 1999, the first year of operation, the VABs were in operation less than 50 percent of their scheduled time. This diminished the expected data and definable periods for study of driver behavior. Only one site had sufficient data to initiate a qualitative analysis of compliance and violation rates. The early findings suggest that drivers showed less risk-taking behavior during the initial period of operation and that compliance levels were slightly better than those of other innovative highway-rail safety devices studied in recent years. However, over ...
On stochastic parameter estimation using data assimilation

Abstract Data assimilation-based parameter estimation can be used to deterministically tune forecast models. This work demonstrates that it can also be used to provide parameter distributions for use by stochastic parameterization schemes. While parameter estimation is (theoretically) straightforward to perform, it is not clear how one should physically interpret the parameter values obtained. Structural model inadequacy implies that one should not search for a deterministic “best” set of parameter values, but rather allow the parameter values to change as a function of state; different parameter values will be needed to compensate for the state-dependent variations of realistic model inadequacy. Over time, a distribution of parameter values will be generated and this distribution can be sampled during forecasts. The current work addresses the ability of ensemble-based parameter estimation techniques utilizing a deterministic model to estimate the moments of stochastic parameters. It is shown that when the system of interest is stochastic the expected variability of a stochastic parameter is biased when a deterministic model is employed for parameter estimation. However, this bias is ameliorated through application of the Central Limit Theorem, and good estimates of both the first and second moments of the stochastic parameter can be obtained. It is also shown that the biased variability information can be utilized to construct a hybrid stochastic/deterministic integration scheme that is able to accurately approximate the evolution of the true stochastic system.
Developing key performance indicators for supply chain: an industry perspective

Purpose – Measuring or monitoring supply chain performance reveals the gap between planning and execution and helps companies to identify potential problems and areas for improvement. However, it is recognized that developing key performance indicators (KPIs), or metrics, is very challenging and a set of practical guidelines is not readily available for companies and supply chain management (SCM) practitioners. This paper seeks to offer a practical approach to performance measurement and to present a list of essential KPIs.Design/methodology/approach – This paper offers insights from industry in the area of supply chain performance measurement and a practical approach to developing performance metrics.Findings – The experience from, and the review of, industry standards and best practices in supply chain performance measurement suggest that “less is better” as to developing performance metrics. Companies should focus on only a small list of KPIs which are critical for their operations management, customer...
Dexamethasone suppression test identifies a subset of elderly depressed patients with reduced platelet serotonin transport and resistance to imipramine inhibition of transport

Dysregulation of the hypothalamus-pituitary-adrenal axis (HPA) is more common in elderly patients with depression than in younger depressed patients, and glucocorticoids are known to influence serotonergic function. Elderly depressed patients are also reportedly more resistant to therapeutic effects of antidepressants. In the current study, we measured platelet serotonin transporter binding sites and transport function in young and elderly depressed patients and determined the relationship to HPA status as assessed with the dexamethasone suppression test (DST). The density and affinity of transporter molecules showed no differences between young and elderly depressed patients, regardless of DST results. Nevertheless, transporter function showed a substantial interaction of aging with DST: elderly DST suppressors showed a deficit in [3H]serotonin uptake capabilities and resistance to imipramine inhibition of uptake. No such defects were seen in the young depressed cohort, regardless of DST status, nor in elderly depressed DST non-suppressors. These results are consistent with the view that depression in the elderly exhibits basic biological differences from depression in earlier life, and that such distinctions may account in part for therapeutic ineffectiveness of antidepressants in specific subgroups, associated with the presence or absence of appropriate HPA regulation.
Influence of Follicle-Stimulating Hormone on the Prostate Assay of Luteinizing Hormone (LH, ICSH)

In view of previous reports on the augmenting effect of prolactin and growth hormone (GH) on the measurement of luteinizing hormone (LH, ICSH) by the hypophysectomized rat prostate (HRP) bio-assay of Greep, the influence of ovine follicle-stimulating hormone (FSH) on this method was examined. LH potency of various preparations obtained from ovine pituitary glands determined by the HRP method was compared with that obtained by the ovarian ascorbic acid depletion (OAAD) bio-assay of Parlow, as the latter method is unaffected by prolactin, GH or FSH. The LH potency of an aqueous homogenate of whole, unfractionated ovine pituitary glands, in terms of NIH-LH-S1, was found to be 4.9 times higher in the HRP system than in the OAAD system. On the other hand, the potencies of 2 partially purified ovine LH preparations determined by the HRP and OAAD methods were in excellent agreement. However, the amount of LH contamination of 4 partially purified ovine FSH preparations determined by the HRP method was always high...
End-user programmers in trouble: Can the Idea Garden help them to help themselves?

End-user programmers often get stuck because they do not know how to overcome their barriers. We have previously presented an approach called the Idea Garden, which makes minimalist, on-demand problem-solving support available to end-user programmers in trouble. Its goal is to encourage end users to help themselves learn how to overcome programming difficulties as they encounter them. In this paper, we investigate whether the Idea Garden approach helps end-user programmers problem-solve their programs on their own. We ran a statistical experiment with 123 end-user programmers. The experiment's results showed that, even when the Idea Garden was no longer available, participants with little knowledge of programming who previously used the Idea Garden were able to produce higher-quality programs than those who had not used the Idea Garden.
Cancer vaccines: a new therapeutic alternative for lung cancer therapy?

10.2217/IMT.09.57 © 2009 Future Medicine Ltd “Owing to their relative low-toxicity profile, cancer vaccines represent an interesting alternative to be studied in early stages (adjuvant setting), as well as for maintenance treatment after definitive first-line therapy for lung cancer.” Luis E Raez University of Miami/Sylvester Comprehensive Cancer Center, FL, USA Tel.: +1 305 243 3286 Fax: +1 305 243 3289
Injury in the Elderly and End-of-Life Decisions

The elderly constitute the fastest growing sector of the population of the United Stated and geriatric trauma patients are presenting for care with increasing frequency. These patients are challenging particularly because of their vulnerability to severe injury, limited physiologic response to stress, and frequent presence of comorbid medical conditions complicating care. Many elderly trauma victims require prolonged intensive care and some fail to improve or succumb despite the best efforts because of the extent of their injuries and their underlying disease. These patients may present profound ethical challenges for trauma surgeons as the goals of care shift from salvage to end-of-life care.
Consumer investment preferences and the Chinese real estate market

Purpose – This paper aims to investigate the relationships between several macro‐economic indicators and real estate investment in China.Design/methodology/approach – This study proposes the “investment preference theory” to explain that bank deposits, stock investment and real estate investment are three important investment vehicles to Chinese households.Findings – The authors find that interest rate, an important monetary aggregate indicator – M2 – and the size of new equity offering are negatively related to real estate investment, which may imply that Chinese investors would prefer to channel their funds to stock market and high‐interest‐rate‐bearing bank deposits to keep a good balance between risk and high return on investment while higher interest rate also increases the cost of borrowing for the property buyers.Originality/value – This is one of the first studies which investigated the connections behind Chinese consumers' real estate investment and empirically tested the choices among bank depos...
A comparative study of cytochrome ratios in mitochondria from organs of the rat, chicken, and guinea pig.

Abstract The concentrations of mitochondrial cytochromes aa3, b, c1, and c have been studied in liver, kidney, brain, heart, and intestine of the rat, guinea pig, and chicken, as well as in beef heart. The ratios of concentrations of cytochromes b, c1, and c concentrations to aa3 have also been calculated. Although in rat liver and beef heart mitochondria the ratios of cytochromes aa3:b:c1:c lie near the values of 2:2:1:2, in all other organs of the species studied this pattern is not followed. However, the ratios for the same organ from any one species are reproducible. It is concluded that mitochondrial cytochrome ratios cannot in general be expressed in simple whole numbers and that different organs differ markedly with respect to these ratios. The ratios for all organs of the species studied are of the same order of magnitude, the greatest variation being 7.7:1:1 for rat intestinal cytochromes aa3:c1:c. In no case are the ratios for cytochromes b, c1, or c to aa3 significantly greater than 1.
Stability of field emission current from various types of carbon nanotube films

Abstract A series of emission current measurements were taken from various types of multiwalled carbon nanotube (MWCNT) films in order to examine their stability for electron field emission. We found that the MWCNTs films grown by the catalytic thermal chemical vapor deposition (CVD) method exhibited much improved emission stability as compared to MWCNT films grown by the plasma-enhanced CVD (PECVD) method. We explain this difference of performance by referring to the graphitic order of these MWCNTs as detected by transmission electron microscopy and Raman spectroscopy. Results indicate that MWCNTs with high-order tubular structures demonstrate stable electron field emission. The best performing sample exhibits a constant current degradation of ∼3% per hour at an emission current density of ∼1 mJ/cm2.
Pulse Oximetry: A Potential Aid in Endodontic Diagnosis?

Article Title and Bibliographic Information Pulse oximetry: review of a potential aid in endodontic diagnosis. Jafarzadeh H, Rosenberg PA. J Endod 2009;35(3):329-33. Reviewer Dan Caplan, DDS, PhD Purpose/Question This article provided a description of pulse oximetry, its use in patient care settings, and its potential for use in endodontic diagnosis. Source of Funding Information not available. Type of Study/Design Comprehensive literature review Level of Evidence Level 3: Other evidence Strength of Recommendation Grade Not applicable
CLASI-FISH: principles of combinatorial labeling and spectral imaging.

Abstract Although the number of phylotypes present in a microbial community may number in the hundreds or more, until recently, fluorescence in situ hybridization has been used to label, at most, only a handful of different phylotypes in a single sample. We recently developed a technique, CLASI-FISH for combinatorial labeling and spectral imaging – fluorescence in situ hybridization, to greatly expand the number of distinguishable taxa in a single FISH experiment. The CLASI technique involves labeling microbes of interest with combinations of probes coupled with spectral imaging to allow the use of fluorophores with highly overlapping excitation and emission spectra. Here, we present the basic principles and theory of CLASI-FISH along with some guidelines for performing CLASI-FISH experiments. We further include a protocol for creating fluorescence spectral reference standards, a vital component of successful CLASI-FISH.
Single-beam trapping of micro-beads in polarized light: Numerical simulations.

Using numerical solutions of Maxwell’s equations in conjunction with the Lorentz law of force, we compute the electromagnetic force distribution in and around a dielectric micro-sphere trapped by a focused laser beam. Dependence of the optical trap’s stiffness on the polarization state of the incident beam is analyzed for particles suspended in air or immersed in water, under conditions similar to those realized in practical optical tweezers. A comparison of the simulation results with available experimental data reveals the merit of one physical model relative to two competing models; the three models arise from different interpretations of the same physical picture.
Lending to developing countries revisited: changing nature of lenders and payment problems

Abstract A review of the lending literature shows the lack of a general study regarding the changing nature of the coexistence among the various sources of disbursement. Empirical evidence from 110 developing countries indicates that, during the past three decades, some sources of disbursement have lost their relevance. During the post-debt crisis period, there has been a substantial reduction in the low-income countries’ access to private capital markets in favor of official lending. In the middle- and high-income countries, the decline in commercial bank lending has been replaced by bonds, portfolio, and FDI flows. In terms of payment problems, while default represented the major concern during the debt crisis period, the likelihood of arrears has increased substantially during the post-crisis period. The paper argues that the changing nature of lenders and payment problems have important policy implications.
Generalized eruption in a liver transplant patient

REPORT OF A CASE A 7-year-old boy with chronic cirrhosis of the liver secondary to extrahepatic biliary hypoplasia was admitted to Children's Hospital, Pittsburgh, Pa. He underwent an uncomplicated liver transplantation, but 10 days postoperatively fever and elevated liver enzyme values developed. His therapy was begun with ampicillin, tobramycin, and clindamycin. A computed tomographic scan showed pancreatitis. A liver biopsy specimen revealed cytomegalovirus (CMV) hepatitis but no evidence of rejection. Two weeks later, the patient experienced respiratory insufficiency that re- quired intubation. Sulfamethoxazole and trimethoprim therapy was started empirically. The following day, a generalized blanching erythema was noted. This progressed to a diffuse petechial and purpuric eruption with a few palpable lesions (Fig 1). The palms and soles were involved, but all mucous membranes were spared. Other medications included ranitidine, nystatin, salt-poor albumin, dopamine, antacids, and bumetanide. Pertinent laboratory values were as follows: hematocrit, 0.27 (normal, 0.34 to 0.40);
Flow cytometric analysis of protein content in Taxus protoplasts and single cells as compared to aggregated suspension cultures

Plant suspension cultures are highly aggregated, preventing the direct application of flow cytometry for the study of population dynamics. The utility of single cells to accurately represent aggregated suspension cultures was tested through the analysis of total protein content. Specifically, protein content of two Taxus cuspidata suspension culture lines was studied using the Bradford assay for aggregated suspension cultures, and flow cytometry with fluorescein isothiocyanate staining for protoplasts and single cells. Taxus protein levels were measured at 75–160 mg per gram dry weight via the Bradford assay. Aggregated suspension cultures, protoplasts, and single cells predicted the same trend of protein content over the culture period (21 days). Normalized protein content of isolated single cells was statistically equivalent to aggregated suspensions for both cell lines. However, normalized protein content of isolated protoplasts showed significant differences from aggregated suspensions for one of the two cell lines. Elicitation with methyl jasmonate (MJ) is commonly utilized to increase paclitaxel accumulation in suspension cultures, and therefore the effect of MJ elicitation on protein content in aggregated suspensions, isolated single cells and protoplasts was assessed. Aggregated suspension cultures, protoplasts, and single cells did not show any change in total protein content following elicitation with MJ at 200 μM on day 7. This study illustrates the usefulness of flow cytometry for obtaining culture population information and the value of using intact single cells for the study of plant metabolism.
Maximizing productivity of CHO cell-based fed-batch culture using chemically defined media conditions and typical manufacturing equipment

A highly productive chemically defined fed-batch process was developed to maximize titer and volumetric productivity for Chinese hamster ovary cell-based recombinant protein manufacturing. Two cell lines producing a recombinant antibody (cell line A) and an Fc-fusion protein (cell line B) were used for development. Both processes achieved product titers of 10 g/L on day 18 under chemically defined conditions. For cell line B, the use of plant derived hydrolysates combined with the optimized chemically defined medium increased the titer to 13 g/L. Volumetric productivities were increased from a base line of about 200 mg/L/d to about 500 mg/L/d under chemically defined conditions and as high as 700 mg/L/d with cell line B using plant derived hydrolysates. Peak cell densities reached greater than 20E6 vc/mL, and cell viabilities were maintained above 80% on day 18 without the use of antiapoptotic genes or temperature shift. A rapid compound screening method was developed to effectively test positive factors within 72 h. Peak volumetric oxygen uptake rates (OUR) more than tripled from the baseline condition. Oxygen demand continued to increase after maximum cell density was reached with a maximal OUR of 3.7 mmol/L/h. The new process format was scaled up and verified at 100 L pilot scale using reactor equipment of similar configuration as used at manufacturing scale.
Evaluation and classification of the potential carcinogenicity of organic air pollutants

Abstract Data on the carcinogenicity and Ames Salmonella test muta‐genicity were compiled for 671 organic chemicals reported to be potential air pollutants. Development of the data base entailed an evaluation of published reports of carcinogenicity and mutagenicity test results available in the open literature. Criteria were established for classifying the chemicals as recognized carcinogens, suspected carcinogens, tumor promoters or cocarcinogens, and mutagens or suspected mutagens. Confirmation of chemicals as ambient air pollutants was attempted only for the chemicals classified into a category of potential carcinogenicity other than unknown. Primary and secondary literature sources were searched for the reported detection of the chemicals as ambient air pollutants. This work resulted in the classification of 77 air pollutants as potential human carcinogens, as demonstrated by the categorization of 25 air pollutants as recognized carcinogens, 20 air pollutants as suspected carcinogens, 15 air pollutant...
Electromechanical performance and other characteristics of IPMCs fabricated with various commercially available ion exchange membranes

Ionic polymer–metal composites (IPMCs) are considered as some of the favorable candidates to be used as biomimetic actuators and sensors in an aqueous environment. Amongst all components that compose an IPMC, the ion exchange membrane is where hydrated cations migrate when an electric field is applied across the membrane and it eventually produces the deformation of the IPMC. Nafion® is the most commonly used ion exchange membrane. Many studies have been conducted on IPMCs made with Nafion®. In this study, three other commercially available ion exchange membranes were used to fabricate IPMCs and their performance as actuators was compared with IPMCs made with Nafion® membrane. Their potential for use in IPMC actuators was investigated by conducting various characterizations such as water uptake, ion exchange capacity, morphology, thermal property, blocking force and bending displacement.
In vitro effects of argon laser radiation on blood: quantitative and morphologic analysis

Use of the argon laser to recanalize stenosed arteries may require delivery of the beam through blood. To assess the degree of hemolysis and debris formation, 84 samples of citrated whole blood were exposed to argon laser radiation with varying power (1, 2 and 3 watts) and duration (5, 10, 20 and 40 seconds). Compared with control samples, only blood samples exposed to a power of 3 watts for 40 seconds showed a marked decrease in hematocrit (from 37 ± 1.3 to 33 ± 1.4%, p These data indicate that: 1) argon laser radiation with a power of 3 watts does not produce apparent hemolysis or debris formation for exposure periods up to 20 seconds, and 2) the effects of laser radiation on blood are probably mediated by thermal denaturation of cell membranes, as suggested by the same morphologic changes produced by thermal injury from a “hot tip.”
Syntheses of Ditopic Calix[4]arene Receptor Molecules Containing Silicon on the Upper Rim

Abstract Calix[4]arene molecules containing two and four silicon atoms appended to the upper rim of the cone conformation were synthesized via hydrosilation of the corresponding di- and tetra-p-allyl calixarene ethers. The p-allyl calixarene ethers were prepared via the well known Claisen rearrangement which transferred the allyl groups originally on the lower rim of the cone to the upper rim. The silated calix[4]arenes were designed to function as ditopic receptor molecules that will bind cations through the oxygen atoms at the lower rim and anions through the silicon atoms on the upper rim. The hydrosilation reaction provided an easy method for introducing different functionality on the silicon atoms in order to attenuate their relative stability and Lewis acidity.
Oral Secondary Syphilis

Secondary syphilis develops in approximately 25% of patients infected with the spirochete bacterium Treponema pallidum. It typically develops several weeks to several months after the primary infection, which is recognized by a painless chancre. Secondary syphilis is characterized by systemic symptoms, such as malaise and fever as well as a maculopapular rash involving the trunk and extremities including the palms and soles. Condyloma lata, which are raised, fleshy lesions, tend to develop at the site of the primary chancre. Diagnosis is achieved primarily through screening and confirmational serologic testing. Histologic findings seen in condyloma lata are largely non-specific. Therefore, a high index of suspicion should be maintained and immunohistochemical stains specific for T. pallidum should be utilized.
The Old English Exodus and the Read Sea

AbstractThis essay suggests that the Old English Exodus, a poem that focuses on the events that precede the reception of the law at Mount Sinai, presents Moses as reading the Red Sea in order to emphasize his identity as a literate and literary figure. Moses reads the sea just as medieval Christians endeavored to read the world, looking to find the divine meaning inscribed within it. The method he applies, peeling back the obscuring waves, fashioning shining walls of water, and revealing ealde staðolas — old foundations, or even foundational truths — models the sort of interpretation a reader might then apply to the notoriously difficult Old English poem. The poet plays with the imagery of the parting sea to hint at what this interpretive method might look like, suggesting ways in which literal and metaphoric depth begin to blur, how waves of water work like layers of language, and how the swirling sea acts as a riddling text to be fathomed. But to really get to the bottom of things, the poem implies, one...
Molecular characterization of the polymerization of acetylene-functional benzoxazine resins

Abstract High char yield polybenzoxazines are obtained from acetylene-functional benzoxazine monomers. Polymerization of acetylene functional group, in addition to oxazine ring opening polymerization, contributes greatly to the exceptional thermal stability. A significant change in char yield is found for these polybenzoxazines by different polymerization environments. The polymerization behaviour of these compounds under air and nitrogen atmosphere has been studied by Fourier transform infra-red spectroscopy, ultra-violet–visible spectroscopy, differential scanning calorimetry and proton nuclear magnetic resonance spectroscopy.
Patrons and Pedagogy: A Look at the Theory of Connectivism

At a recent conference on technology and education, the theory of connectivism was a hot topic. Proponents of this educational theory argue that technology has changed so substantially in the past ...
Metallinduzierte Cyclotrimerisierung eines λ3‐Phosphaalkins: Bildung eines Molybdän‐komplexierten 1,3,5‐Triphosphabenzols

Preparation du complexe par reaction de [(η 6 -C 7 H 8 )Mo(CO) 3 ] avec t-BuCP dans THF. Donnees RMN et IR
Downstream fining in gravel bed rivers

The special session Equal Mobility and Downstream Fining in Gravel Bed Rivers held May 8, 1989, at the AGU Spring Meeting in Baltimore, Md., examined the apparent contradiction between two observations: that bed grain size in aggrading rivers decreases downstream, mainly through selective deposition of the coarse clasts, but that measurements in gravel channels and flumes indicate that all grain sizes in a mixture are transported at the same rate, when scaled according to their proportion in the bed. If all sizes are transported at equal rates, how are the coarser clasts selectively deposited during aggradation?.
Mediastinitis after pediatric cardiac surgery: a 15-year experience at a single institution

Abstract Background The spectrum of sternal wound infections after cardiac surgery ranges from superficial infections to a deep sternal infection known as mediastinitis. Mediastinitis is a rare but clinically relevant source of postoperative morbidity and mortality in adult and pediatric patients after cardiac surgery. Methods We retrospectively identified all patients diagnosed with mediastinitis after cardiac surgery from January 1987 to December 2002 (17 patients/7,616 surgeries=0.2%). Demographic data, cardiac diagnosis, cardiac surgery, hospital length of stay, associated medical diagnosis, and surgical treatment for mediastinitis were collected. Results Fifteen pediatric patients (age Staphylococcus species (n = 9). Six patients had an associated bacteremia. The median hospital length of stay for all patients was 42.5 days (range 16 to 163 days). The hospital mortality was 1 of 15 (6%). Each patient was treated with intravenous antibiotics; sternal debridement; and rectus abdominus flap reconstruction (n = 7), pectoralis muscle flap reconstruction (n = 3), omentum reconstruction (n = 1), or primary sternal closure (n = 4). Three patients have undergone redo-sternotomy with orthotopic heart transplantation, bidirectional cavopulmonary anastomosis, and replacement of a right ventricle to pulmonary artery homograft. Conclusions Timely diagnosis, aggressive sternal debridement, and liberal use of rotational muscle flaps can potentially minimize the morbidity and mortality in pediatric postoperative cardiac patients. Subsequent redo-sternotomy has not been problematic.
Proposed methods of addressing some rate and range limits in quantum cryptography

Progress in the last decade has enabled the generation and detection of both single and entangled photons for use in new applications of quantum cryptography, secure key distribution in particular, Nevertheless, fundamental and practical restrictions restrict the implementation to protoype systems. Methods of circumvent certain of those are presented in configurations that retain the features essential to single photon and photon pair signal processing.
Identification of a negative regulatory element in the 5′-flanking region of the human dopamine β-hydroxylase gene

Abstract Transient transfection experiments indicate that a 5′-flanking upstream domain, residing between −437 and −262 bp of the human dopamine β-hydroxylase (DBH) gene, has a cell type-specific silencer function. This domain contains a putative silencer motif (which we designate DBH negative regulatory element, DNRE), showing sequence homology with the neural-restrictive silencer element (NRSE or RE-1) recently characterized in type II sodium channel, SCG10 and synapsin I genes. When the DNRE was placed at the proximal 262 bp of the homologous (DBH) promoter, it exhibited strong silencer activity both in DBH-expressing SK-N-BE(2)C as well as in DBH-nonexpressing HeLa cells. In addition, the DNRE also exhibited modest silencer activity upon a heterologous tk (herpes simplex virus thymidine kinase) promoter in both cell lines. Electrophoretic mobility shift assay demonstrated that nuclear extracts from both SK-N-BE(2)C and HeLa cells contain protein(s) that specifically bind to the DNRE. Formation of this DNRE/protein complex was specifically inhibited by an excess of unlabeled DNRE or NRSE. Finally, a similar sequence motif residing in the corresponding upstream area of the rat DBH gene also had a negative regulatory function, indicating that the silencer function of the DNRE is conserved in human and rat DBH genes.
Earth Satellite Perturbation Theories as Approximate KAM Tori

Several standard Earth satellite general perturbation models can be converted into KAM tori, and are compared to KAM tori constructed from full geopotential integrations. Converting perturbation theories into tori allows absolute identification of spectral lines with the classical orbital elements. Comparisons are made of each torus representation against numerical integrations, and the torus spectra are also compared. The torus canonical coordinates Q i , are identified as the analogues of the “mean” mean anomaly $$\bar M$$ , the longitude of the mean node $$\bar \Omega - {\theta _g}$$ , and the mean argument of perigee $$\bar \omega $$ . The associated torus canonical momenta P i are approximately the usual Delaunay momenta. A norm on multiply-periodic functions allows the actual “distance” between perturbation theory tori and actual geopotential tori to be measured, and the frequency errors can be estimated. KAM tori and numerical integration can agree to meter level accuracy over time intervals of a decade.
Closed-Form Representation of Beam Response to Moving Line Loads

Fourier transform is used to solve the problem of steady-state response of a beam on an elastic Winkler foundation subject to a moving constant line load. Theorem of residue is employed to evaluate the convolution in terms of Green's function. A closed-form solution is presented with respect to distinct Mach numbers. It is found that the response of the beam goes to unbounded as the load travels with the critical velocity. The maximal displacement response appears exactly under the moving load and travels at the same speed with the moving load in the case of Mach numbers being less than unity.
Chemosensory Behaviour of Strombidium purpureum, an Anaerobic Oligotrich with Endosymbiotic Purple Non‐Sulphur Bacteria

. Strombidium purpureum Kahl, is an anaerobic oligotrichous ciliate with endosymbiotic phototrophic bacteria. Like other anaerobic ciliates, S. purpureum reacts to O2-pressure. In the light, the ciliates avoid even traces of O2 (< 1% atmospheric saturation). In the dark, however, the ciliates accumulate in water with a pO2 of 1–4% atmospheric saturation. Experiments show that ciliates which have accumulated in the dark under microaerophilic conditions react when the light is turned on, and their ability to escape is enhanced by steep O2-gradients. The ciliates orient themselves in O2-gradients by a series of phobic responses. They tumble whenever they swim towards a higher O2-tension and thus they eventually all swim in the direction of lower pO2. The ecological implications of such behaviour are discussed.
Rare-earth organic complexes for amplification in polymer optical fibers and waveguides

The optical properties of rare-earth organic complexes have been studied because of their possible application to polymer optical fibers and waveguides. Er3+, Nd3+, and Sm3+ ions are encapsulated in tetrakis(benzoyltrifluoroacetonate) and tetrakis(dibenzoylmethide) chelates, and their radiative properties are evaluated in several organic solvents. Analysis reveals that tetrakis(benzoyltrifluoroacetonate) chelates are promising dopants for use in rare-earth-doped polymer devices. These rare-earth complexes can be doped to high concentrations in polymer systems without quenching, providing the means for short-length amplification devices. Numerical simulations reveal that gains as high as and exceeding 20 dB should be realizable in rare-earth-doped polymer fiber amplifiers having lengths <60 cm. Similar calculations reveal threshold pump powers of tens of milliwatts for rare-earth-doped polymer fiber lasers.
Derivative securities and cash market stability

This study investigates the effect of introducing interest-rate futures and options on the price variances in related financial cash markets. Standard research approaches to this issue relate cash-price stability before the introduction of futures and options trading to cash-price stability after trading in the derivative security begins. However, controlling for the additional factors that may also effect cash markets is difficult. The approach employed here to deal with this obstacle is motivated by recent theoretical research relating cash and futures markets, but hitherto not operationalized to empirically test for a relationship between the markets. Varying-parameter models of (1) the demand for short-term Treasury securities, (2) the demand for large time-deposits, and (3) the supply of large time-deposits are specified such that changes in the parameters imply changes in the volatility of the cash price. These parameters are modelled as functions of the trading volume of interest-rate futures and o...
The mass spectra of small-ring heterocycles. IV

Both the high and low resolution mass spectra of fourteen isomeric trans- and cis-aroylaziridines are presented. In contrast to earlier low resolution mass spectral work on these compounds [1], a new fragmentation pathway for the loss of hydroxyl is presented. Also, the simple fission of the N-alkylnitrogen bond is described. Detailed fragmentation mechanisms are presented and discussed for the major ions found in the mass spectra.
On-line trajectory generation: Nonconstant motion constraints

A concept of on-line trajectory generation for robot motion control systems enabling instantaneous reactions to unforeseen sensor events was introduced in a former publication. This previously proposed class of algorithms requires constant kinematic motion constraints, and this paper extends the approach by the usage of time-variant motion constraints, such that low-level trajectory parameters can now abruptly be changed, and the system can react instantaneously within the same control cycle (typically one millisecond or less). This feature is important for instantaneous switchings between state spaces and reference frames at sensor-dependent instants of time, and for the usage of the algorithm as a control submodule in a hybrid switched robot motion control system. Real-world experimental results of two sample use-cases highlight the practical relevance of this extension.
The impact of parental cancer on the adolescent: an analysis of the literature

Research has revealed the impact of the diagnosis of cancer on an individual, their spouse, and their family. One dimension that has received little attention is the impact of the cancer diagnosis on the patient's adolescent. This article offers an analysis of descriptive studies, intervention studies, and databased book chapters, published between 1966 and 2006, that examined the impact of parental cancer on the adolescent. The results of 45 studies and three databased book chapters are organized around four themes: adolescents' (1) emotions and behaviors (2) perceptions and knowledge of parental cancer (3) changes in roles and (4) ways of coping. These themes will assist the reader in understanding the application of the knowledge gained from the analysis of the literature to directions for future research.
RNA and DNA content of isolated cell nuclei measured by multiparameter flow cytometry

Nuclei were isolated from various cell types including Chinese hamster ovary (CHO) and L1210 leukemia cell lines, primary cultures of fibroblasts, nonstimulated and stimulated human lymphocytes and mouse liver cells, by using different isolation techniques. The isolated nuclei were subsequently stained with acridine orange (AO) and their fluorescence was measured by flow cytometry. Various procedures designed to stain DNA versus RNA differentially with AO were tested, and the staining of isolated nuclei was compared with that of whole cells. Control incubations with RNase and DNase were performed to estimate in whole cells and in nuclei the contribution of DNA and RNA to the fluorescence intensity at the respective wavelength bands of maximum emission for DNA (F530) and RNA (F greater than 600). Depending on the cell type, 10-20% of total cell RNase-sensitive F greater than 600 is localized in the nuclei. The RNase-resistant portion of F greater than 600 of isolated nuclei represents the stainability of DNA. Suppression of cell proliferation in subconfluent cultures results in a decrease in both whole cell and in nuclear RNA content. Nonstimulated lymphocyte nuclei have considerably lower RNA content than nuclei from lymphocytes stimulated by pokeweed mitogen. Two subpopulations of nuclei having the same (2C) DNA content but differing in RNA content, are present in mouse liver; the cells entering S phase originate from the high RNA population.