2,931 research outputs found
Production Of Dna Minicircles Less Than 250 Base Pairs Through A Novel Concentrated Dna Circularization Assay Enabling Minicircle Design With Nf-Îșb Inhibition Activity
Double-stranded DNA minicircles of less than 1000 bp in length have great interest in both fundamental research and therapeutic applications. Although minicircles have shown promising activity in gene therapy thanks to their good biostability and better intracellular trafficking, minicircles down to 250 bp in size have not yet been investigated from the test tube to the cell for lack of an efficient production method. Herein, we report a novel versatile plasmidfree method for the production of DNA minicircles comprising fewer than 250 bp. We designed a linear nicked DNA double-stranded oligonucleotide bluntended substrate for efficient minicircle production in a ligase-mediated and bending protein-assisted circularization reaction at high DNA concentration of 2M. This one pot multi-step reaction based-method yields hundreds of micrograms of minicircle with sequences of any base composition and position and containing or not a variety of site-specifically chemical modifications or physiological supercoiling. Biochemical and cellular studies were then conducted to design a 95 bp minicircle capable of binding in vitro two NF-ÎșB transcription factors per minicircle and to efficiently inhibiting NF-ÎșB-dependent transcriptional activity in human cells. Therefore, our production method could pave the way for the design of minicircles as new decoy nucleic acids. © The Author(s) 2016.45
Testing the equivalence principle: why and how?
Part of the theoretical motivation for improving the present level of testing
of the equivalence principle is reviewed. The general rationale for optimizing
the choice of pairs of materials to be tested is presented. One introduces a
simplified rationale based on a trichotomy of competing classes of theoretical
models.Comment: 11 pages, Latex, uses ioplppt.sty, submitted to Class. Quantum Gra
Inelastic collisions in molecular nitrogen at low temperature (2<T<50 K)
Theory and experiment are combined in a novel approach aimed at establishing a set of two-body state-to-state rates for elementary processes ij->lm in low temperature N2:N2 collisions involving the rotational states i, j, l, m. First, a set of 148 collision cross sections is calculated as a function of the collision energy at the converged close-coupled level via the MOLSCAT code, using a recent potential energy surface for N2âN2. Then, the corresponding rates for the range of 2<T<50 K are derived from the cross sections. The link between theory and experiment, aimed at assessing the calculated rates, is a master equation which accounts for the time evolution of rotational populations in a reference volume of gas in terms of the collision rates. In the experiment, the evolution of rotational populations is measured by Raman spectroscopy in a tiny reference volume 2E-3 mm3 of N2 traveling along the axis of a supersonic jet. The calculated collisional rates are assessed experimentally in the range of 4<T<35 K by means of the master equation, and then are scaled by averaging over a large set of experimental data. The scaled rates account accurately for the evolution of the rotational populations measured in a wide range of conditions. Accuracy of 10%
is estimated for the main scaled rates.This work has been supported by the Spanish Ministerio de EducaciĂłn y Ciencia, research Project Nos. FIS2004-02576, HF2004-232, ESP2004-21060-E, and ASTROCAM network. J.P.F. is indebted to the CSIC for an I3P grant.Peer reviewe
Investigation of wall normal electromagnetic actuator for seawater flow control
Submitted versio
The Voices of History: theorising the interpersonal semantics of historical discourses
âThe individual consumer, the learner of history, is offered an impressive array of discursive products geared to catch his or her attention, to persuade him or her of the truth of whatever message is transmittedâ (Blanco and
Rosa 1997: 197. In this article I examine these discursive products from the perspective of âvoiceâ. I do this as a way of bringing to conscious attention the strategies that historians use in order to persuade and position the âconsumerâ. âVoiceâ in recent systemic linguistic theorizing refers to distinctive configurations of APPRAISAL choices. Within the domain of history, research to date has identified three main configurations or
voicesâârecorderâ, âinterpreterâ, and âadjudicatorâ.
Central to the research reported on in this article is Martinâs APPRAISAL framework (Martin 1997, 2000). APPRAISAL
1 systems are the semantic resources used to negotiate emotions, judgments, and valuations. In this article I will examine how choices from these systems vary in ways that are systematic â different history texts speak with different âvoicesâ. These voices, I argue, are a key rhetorical strategy in history discourse. Different combinations of APPRAISAL resources are drawn on to negotiate the heteroglossic positions of their audiences. As such they are a key resource for both the professional and apprentice historian in their assessment of
interpretations of the past
A cryogenic liquid-mirror telescope on the moon to study the early universe
We have studied the feasibility and scientific potential of zenith observing
liquid mirror telescopes having 20 to 100 m diameters located on the moon. They
would carry out deep infrared surveys to study the distant universe and follow
up discoveries made with the 6 m James Webb Space Telescope (JWST), with more
detailed images and spectroscopic studies. They could detect objects 100 times
fainter than JWST, observing the first, high-red shift stars in the early
universe and their assembly into galaxies. We explored the scientific
opportunities, key technologies and optimum location of such telescopes. We
have demonstrated critical technologies. For example, the primary mirror would
necessitate a high-reflectivity liquid that does not evaporate in the lunar
vacuum and remains liquid at less than 100K: We have made a crucial
demonstration by successfully coating an ionic liquid that has negligible vapor
pressure. We also successfully experimented with a liquid mirror spinning on a
superconducting bearing, as will be needed for the cryogenic, vacuum
environment of the telescope. We have investigated issues related to lunar
locations, concluding that locations within a few km of a pole are ideal for
deep sky cover and long integration times. We have located ridges and crater
rims within 0.5 degrees of the North Pole that are illuminated for at least
some sun angles during lunar winter, providing power and temperature control.
We also have identified potential problems, like lunar dust. Issues raised by
our preliminary study demand additional in-depth analyses. These issues must be
fully examined as part of a scientific debate we hope to start with the present
article.Comment: 35 pages, 11 figures. To appear in Astrophysical Journal June 20 200
Phenomenology of the Equivalence Principle with Light Scalars
Light scalar particles with couplings of sub-gravitational strength, which
can generically be called 'dilatons', can produce violations of the equivalence
principle. However, in order to understand experimental sensitivities one must
know the coupling of these scalars to atomic systems. We report here on a study
of the required couplings. We give a general Lagrangian with five independent
dilaton parameters and calculate the "dilaton charge" of atomic systems for
each of these. Two combinations are particularly important. One is due to the
variations in the nuclear binding energy, with a sensitivity scaling with the
atomic number as . The other is due to electromagnetism. We compare
limits on the dilaton parameters from existing experiments.Comment: 5 page
A Delphi study to strengthen research methods training in undergraduate psychology programmes
Psychology programmes often emphasise inferential statistical tests over a solid understanding of data and research design. This imbalance may leave graduates under-equipped to effectively interpret research and employ data to answer questions. We conducted a two-round modified-Delphi to identify the research methods skills that the UK psychology community deems essential for undergraduates to learn. Participants included 103 research methods instructors, academics, students, and non-academic psychologists. Of 78 items included in the consensus process, 34 reached consensus. We coupled these results with a qualitative analysis of 707 open-ended text responses to develop nine recommendations for organisations that accredit undergraduate psychology programmesâsuch as the British Psychological Society (BPS). We recommend that accreditation standards emphasise (1) dataskills, (2) research design, (3) descriptive statistics, (4) critical analysis, (5) qualitative methods, and (6) both parameter estimation and significance testing; as well as (7) give precedence to foundational skills, (8) promote transferable skills, and (9) create space in curricula to enable these recommendations. Our data and findings can inform modernised accreditation standards to include clearly-defined, assessable, and widely-encouraged skills that foster a competent graduate body for the contemporary world
Zero-sum, the niche,and metacommunities: long-term dynamics of community assembly
Recent models of community assembly, structure, and dynamics have incorporated, to varying degrees, three mechanistic processes: resource limitation and interspecific competition, niche requirements of species, and exchanges between a local community and a regional species pool. Synthesizing 30 years of data from an intensively studied desert rodent community, we show that all of these processes, separately and in combination, have influenced the structural organization of this community and affected its dynamical response to both natural environmental changes and experimental perturbations. In addition, our analyses suggest that zero-sum constraints, niche differences, and metacommunity processes are inextricably linked in the ways that they affect the structure and dynamics of this system. Explicit consideration of the interaction of these processes should yield a deeper understanding of the assembly and dynamics of other ecological communities. This synthesis highlights the role that long-term data, especially when coupled with experimental manipulations, can play in assessing the fundamental processes that govern the structure and function of ecological communities
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