169,826 research outputs found
Properties of the adenovirus IVa2 gene product, an effector of late-phase-dependent activation of the major late promoter.
No full textInternational audienceThe adenovirus major late promoter is strongly activated after the onset of viral DNA replication. Sequence elements located downstream of the major later promoter start site have previously been shown to be essential for this activation. Two proteins (DEF-A and DEF-B) bind to these elements in a late-phase-dependent manner. DEF-B has been identified as the product of adenovirus intermediate gene IVa2 (pIVa2) (C. Tribouley, P. Lutz, A. Staub, and C. Kedinger, J. Virol. 68:4450-4457, 1994). Here we show that pIVa2, while monomeric in solution, binds to its recognition sequence as a dimer and that two 20-residue amphipathic alpha helices play an essential role in this DNA-binding activity. Attempts to purify DEF-A have failed, but its chromatographic behavior, together with its immunological properties, established that pIVa2 is also a component of this heteromeric protein. In addition, the time course of pIVa2 synthesis during infection correlated with simultaneous detection of the binding of both DEF-A and DEF-B complexes to the downstream elements. Finally, as revealed by immunomicroscopy, pIVa2 is targeted to the nucleus, where it distributes to restricted locations in the nucleoplasm, as well as to the nucleoli. Altogether, these results demonstrate that pIVa2 plays a critical role in the transition from the early to the late phase of the lytic cycle. Furthermore, pIVa2 may serve additional functions yet to be uncovered, as suggested by its presence within the cell nucleolus
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Aerobic nitrogen fixation in Azotobacter vinelandii
No full textI ELECTRON DONATION TO NITROGENASEPaper I shows that the hypothesis, that a high ratio of (NADH + NADPH) / (NAD + + NADP + ) is the source of reducing power for nitrogenase in intact A.vinelandii, is invalid. On the contrary, with a decreasing ratio of reduced to oxidized pyridine nucleotides, the nitrogenase activity of whole cells increases. The experiments described in paper I, indicate that the reducing power necessary for nitrogen fixation in A.vinelandii is generated within the cytoplasmic membrane. It is demonstrated that transport of reducing equivalents to the nitrogenase requires a high energy level of the cytoplasmic membrane. The energy level of the cytoplasmic membrane was measured by the intracellular Alp concentration and by using 9-amino acridine as a fluorescent probe. Other regulating factors of the nitrogenase activity in A.vinelandii are shown to be the intracellular ATP/ ADP ratio and the presence of oxygen.Paper III shows that toluene makes A.vinelandii cells permeable for small molecules but not for enzymes. In toluene-treated cells, enzyme activities can be measured by adding the appropriate cofactors and substrates. It is possible to restore the oxidation of organic substrates but no concomitant nitrogenase activity can be observed. We suggest that an observed lack of energization of the cytoplasmic membranes is the missing link between oxidation and generation of the reducing equivalents for nitrogen fixation. In paper III and IV we show that the endogenous low potential electron carriers in toluene-treated cells are not reduced. In paper IV a membrane-bound NAD(P)H-flavodoxin oxidoreductase is demonstrated and a proposal is given in which NADH is the electron donor for nitrogenase. The electron carrier flavodoxin is reduced by the membrane-bound NADH-flavodoxin oxidoreductase at a low pH, that is developed in an energy-linked process.II OXYGEN PROTECTION OF NITROGENASEIn paper II the source of respiration protection is investigated. Experiments with radioactive pyruvate and sucrose show that the rate of sucrose oxidation by A.vinelandii is associated with the sucrose translocator activity. We show that the respiration protection of the nitrogen-fixing system in A.vinelandii is dependent of the oxygen input during growth. The oxidation capacity intrinsically depends on the type of substrate and can be partly adapted.Membranes rich in cytochromes c 4 + c 5 and o and with phosphorylation between NADH and c 4 + c 5 and oxygen and cytochrome c 4 + c 5 and oxygen, can be isolated from A.vinelandii grown O 2 -limited. Cytochromes b and d can be detected in addition when A.vinelandii cells are grown N 2 limited. The activity of the NADH oxidase system is increased in such cells and phosphorylation is only observed between CoQ and oxygen. Under saturating oxygen concentrations the type of respiratory membranes was not observed to influence the intracellular energy charge.In paper III and IV the mechanism of the conformational protection of nitrogenase was investigated. It is shown that nitrogenase can be isolated as an oxygen-stable complex form A.vinelandii independent of the cell rupture method. Also no influence of the cell rupture method on the rate of sedimentation of the nitrogenase can be observed. The rate of sedimentation of the nitrogenase is found to be concentration and pH dependent. At pH=7.4 the rate of sedimentation of the nitrogenase complex is comparable with that of the pyruvate dehydrogenase complex.No evidence was found for a particulate nitrogenase, it is demonstrated that the oxygen stability of nitrogenase in crude extracts is caused by complexation. of the nitrogenase components with an Fe-S protein. An alternative proposal for the switch-on switch-off phenomenon in whole Azotobacter cells is given. Nitrogenase is present in vivo as an active and oxygen tolerent complex but nitrogen fixation in whole cells is inhibited by the oxidation of flavodoxin hydroquinone.<p/
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
A ±25A Versatile Shunt-Based Current Sensor with 10kHz Bandwidth and ±0.25% Gain Error from -40°C to 85°C Using 2-Current Calibration
No full textAccurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25%) with both low-cost PCB and stable metal-alloy shunts.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
An Article About Albertus C. Van Raalte, Author Unknown, Except for Parts Taken from an Article by Anna C. Post
No full textAn article about Albertus C. Van Raalte, author unknown, except for parts taken from an article by Anna C. Post. The author knew first generation persons in the Holland settlement and therefore, the article has some value.https://digitalcommons.hope.edu/vrp_1890s/1012/thumbnail.jp
Archivist, Archaeologist, Author and the Tactile Window
No full textThe idea that the predominant way of engaging with architecture is through vision is not uncommon but also not always the most appropriate given that buildings are also experienced through tactile interventions. This consequence that emphasises visual aesthetics in order to appreciate and understand architecture probably has much to do with the assumed but rather vaguely defined role of the architect as designer in the practice of architectural design. A resulting misapprehension is that architects designing for visual appreciation think that they are actually designing physical space for embodied tactile engagement.
This prioritisation of vision in the way architects think about and approach design is questioned through the design project of the Tactile Window in which the position of the architect is redefined through inhabiting the roles of archivist, archaeologist and author during the design process.
A 16th century portrait of Queen Elizabeth I known as the Ditchley portrait, currently on display at the National Portrait Gallery is used as the source from which the design of the Tactile Window is derived from and refers back to. Questioning the validity of vision as the sole means of engaging with the work, information about the portrait and working methods gathered from the three carefully chosen positions mentioned above are drawn on and applied to the making of this Tactile Window that becomes an alternative Ditchley portrait. Through exploring the hidden historical and current narratives of and in the existing portrait, the presence of the portrait is alluded to on an alternative physical site. Key to this are the working methods of an invented archival system of design reasoning, the unearthing of archaeological texts and assuming of authorship within the individual frameworks of the roles of archivist, archaeologist and author.
The redefined role of the architect as archaeologist takes onboard the unearthing of associated drawings and writings as well as the methods of organising and applying the recovered information to the system set up by the archivist. This analysis of the graphic and text based information is used to formulate historical narratives that are woven into the design project. Whereas traditional archaeology stresses on the study of a site from a site with quantifiable limits to the physical context, the notion of archaeological sites in this instance refers to the places where the stored information is unearthed. Through the careful process of archiving and analysing this information, a new site that is located within both the physical and historical contexts of interest is discovered. The author then draws upon the elements in the archival system that includes the findings of the archaeologist to construct the alternative Ditchley portrait in this new site of the Echoing Cedar, the result of which bears no visual resemblance to the existing work.
The Tactile Window is a reading of the Ditchley portrait in which information about and in the painting is transformed into a design proposal for an inhabited structure. The intended method of interaction with this alternative portrait is not merely restricted to vision but relies on engagement with the other senses. This experience is enhanced by the interplay with certain site conditions such as wind and rain in order to allude to specific aspects of the Ditchley portrait that are not visually apparent in the existing work.
In the processes of excavating, finding and revealing the hidden information to create this alternative portrait, the effects of the visuals afforded by the existing portrait inadvertently begin to fade as the validity of a single means of visual expression is questioned
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