2,144 research outputs found
Traveling sealer for contoured table Patent
Sealing apparatus for joining two pieces of frangible material
Transcription factor-dependent loading of the E1 initiator reveals modular assembly of the papillomavirus origin melting complex
Replication of bovine papillomavirus type 1 DNA absolutely requires the viral transcription factor E2 as well as the initiator Fl, although Fl alone has all the activities expected of an initiator protein. El assembles on the DNA in a stepwise fashion and undergoes a transition in activities from site-specific DNA-binding protein to mobile helicase. Complex assembly is assisted by the viral transcription factor E2 at two levels. E2 acts generally as a specificity factor, which through cooperative binding with El generates an initial Fl complex containing three Fl dimers bound to ori on one face of the DNA, El-ori. Furthermore, E2 can promote the transition to an ori melting complex by recruiting additional Fl molecules to ori, effectively reducing the Fl concentration required for ori melting. This reaction is dependent on an Ea-binding site positioned distal to the precursor E1-ori complex. The final origin melting complex has two subunits that each encircle the DNA and function independently to melt ori. The assembly pathway we describe has implication for understanding DNA melting and unwinding reactions, which are generally poorly understood
A DNA-binding activity in BPV initiator protein E1 required for melting duplex ori DNA but not processive helicase activity initiated on partially single-stranded DNA
The papillomavirus replication protein E1 assembles on the viral origin of replication (ori) as a series of complexes. It has been proposed that the ori DNA is first melted by a head-to-tail double trimer of E1 that evolves into two hexamers that encircle and unwind DNA bi-directionally. Here the role of a conserved lysine residue in the smaller tier or collar of the E1 helicase domain in ori processing is described. Unlike the residues of the AAA+ domain DNA-binding segments (β-hairpin and hydrophobic loop; larger tier), this residue functions in the initial melting of duplex ori DNA but not in the processive DNA unwinding of partially single-stranded test substrates. These data therefore define a new DNA-binding related activity in the E1 protein and demonstrate that separate functional elements for DNA melting and helicase activity can be distinguished. New insights into the mechanism of ori melting are elaborated, suggesting the coordinated involvement of rigid and flexible DNA-binding components in E1
A strong pair correlation bound implies the CLT for Sinai Billiards
For Dynamical Systems, a strong bound on multiple correlations implies the
Central Limit Theorem (CLT) [ChMa]. In Chernov's paper [Ch2], such a bound is
derived for dynamically Holder continuous observables of dispersing Billiards.
Here we weaken the regularity assumption and subsequently show that the bound
on multiple correlations follows directly from the bound on pair correlations.
Thus, a strong bound on pair correlations alone implies the CLT, for a wider
class of observables. The result is extended to Anosov diffeomorphisms in any
dimension.Comment: 13 page
Search for direct photons in p+Pb and p+C collisions at sqrt(sNN) = 17.4 GeV
Upper limits on direct photon production were determined as a function of the
transverse momentum for 0.7 < pT <= 3.2 GeV/c with the WA98 experiment in p+C
and p+Pb collisions at sqrt(sNN) = 17.4 GeV. The results are compared to direct
photon measurements in Pb+Pb collisions at sqrt(sNN) = 17.3 GeV by WA98.
Implications for a possible thermal direct photon contribution are discussed.Comment: 4 pages, 3 figures, to appear in the proceedings of the Quark Matter
2008 conference, Jaipur, India, 4-10 Feb 200
Measuring and modelling retrofit fabric performance in solid wall conjoined dwellings
There remains a significant number of occupied and uninsulated solid wall dwellings in the UK. Deep retrofit is often required for these buildings to become energy efficient but it is difficult to determine how these buildings will respond to retrofit without a detailed understanding of their fabric thermal performance Greater certainty can however be achieved by combining theoretical models and practical field tests, prior to the design of retrofit programmes. This type of approach can then be used to inform and optimize the design of retrofit interventions. This paper presents results from a series of in situ fabric performance tests undertaken on two no-fines concrete, conjoined dwellings pre- and post-retrofit and demonstrates how empirical data can be used to inform and calibrate the thermal performance of dynamic simulation models (DSMs). This is a particularly pragmatic calibration method as it eliminates the need for actual weather data, which is expensive and prohibitive to collect and collate. The DSM inputs and outputs were compared with those obtained from Standard Assessment Procedure (SAP) calculations. The results illustrate how the fabric performance of no-fines concrete can vary between similar house types within the same development. This research also validates the effectiveness of the calibration methodology that uses the whole house Heat Transfer Coefficient (HTC) as the qualifying metric. Furthermore, results also emphasize the importance of appropriately characterizing the physical properties of existing buildings before designing retrofit strategies. This paper contributes to the growing knowledge base concerned with the energy performance gap. In this instance, SAP predicts higher absolute savings then measured in situ which is problematic when assessing the financial viability of retrofits
Viral-E1 and Viral-E2 Proteins Support Replication of Homologous and Heterologous Papillomaviral Origins
We have shown that E1 and E2 proteins of human papillomavirus type 11 (HPV-11) were essential to support the replication of the homologous viral origin (ori) in a transient replication assay, similar to reports on bovine papillomavirus type 1 (BPV-1). Unexpectedly, matched or even mixed combinations of E1 and E2 proteins from HPV-11 or BPV-1 replicated either ori in human, monkey, and rodent cell lines of epithelial or fibroblastic lineage, albeit with varied efficiencies. Either set of viral proteins was also able to initiate replication of ori-containing plasmids from many other human and animal papillomaviruses. Thus the interactions among the cis elements and trans factors of papillomaviruses are more conserved than expected from the other members of the papovavirus family, simian virus 40 and polyomavirus, for which large tumor antigen does not replicate a heterologous ori in either permissive or nonpermissive cells. We infer that the stringent species and tissue specificities observed for papillomaviruses in vivo are not entirely due to direct restrictions on viral DNA replication. Rather, transcriptional control of viral gene expression must play a dominant role
The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events
The design, construction, and commissioning of the ALICE Time-Projection
Chamber (TPC) is described. It is the main device for pattern recognition,
tracking, and identification of charged particles in the ALICE experiment at
the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and
is operated in a 0.5 T solenoidal magnetic field parallel to its axis.
In this paper we describe in detail the design considerations for this
detector for operation in the extreme multiplicity environment of central
Pb--Pb collisions at LHC energy. The implementation of the resulting
requirements into hardware (field cage, read-out chambers, electronics),
infrastructure (gas and cooling system, laser-calibration system), and software
led to many technical innovations which are described along with a presentation
of all the major components of the detector, as currently realized. We also
report on the performance achieved after completion of the first round of
stand-alone calibration runs and demonstrate results close to those specified
in the TPC Technical Design Report.Comment: 55 pages, 82 figure
Interferometry of Direct Photons in Central 280Pb+208Pb Collisions at 158A GeV
Two-particle correlations of direct photons were measured in central
208Pb+208Pb collisions at 158 AGeV. The invariant interferometric radii were
extracted for 100<K_T<300 MeV/c and compared to radii extracted from charged
pion correlations. The yield of soft direct photons, K_T<300 MeV/c, was
extracted from the correlation strength and compared to theoretical
calculations.Comment: 5 pages, 4 figure
Signatures of Quark-Gluon-Plasma formation in high energy heavy-ion collisions: A critical review
A critical review on signatures of Quark-Gluon-Plasma formation is given and
the current (1998) experimental status is discussed. After giving an
introduction to the properties of QCD matter in both, equilibrium- and
non-equilibrium theories, we focus on observables which may yield experimental
evidence for QGP formation. For each individual observable the discussion is
divided into three sections: first the connection between the respective
observable and QGP formation in terms of the underlying theoretical concepts is
given, then the relevant experimental results are reviewed and finally the
current status concerning the interpretation of both, theory and experiment, is
discussed. A comprehensive summary including an outlook towards RHIC is given
in the final section.Comment: Topical review, submitted to Journal of Physics G: 68 pages,
including 39 figures (revised version: only minor modifications, some
references added
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