529,321 research outputs found
J. B. Crick correspondence with John T. Wilder, 1864 March 22
No full textLetter from J. B. Crick to Colonel Wilder describing Confederate troop movements. Crick also mentions the problems arming the soldiers in Wilder's Brigade during Wilder's absence
J. B. Crick correspondence with John T. Wilder, 1864 March 22
No full textLetter from J. B. Crick to Colonel Wilder describing Confederate troop movements. Crick also mentions the problems arming the soldiers in Wilder's Brigade during Wilder's absence
Of the Helmholtz Club, South-Californian seedbed for visual and cognitive neuroscience, and its patron Francis Crick
No full textTaking up the view that semi-institutional gatherings such as clubs, societies, research schools, have been instrumental in creating sheltered spaces from which many a 20th-century project-driven interdisciplinary research programme could develop and become established within the institutions of science, the paper explores the history of one such gathering from its inception in the early 1980s into the 2000s, the Helmholtz Club, which brought together scientists from such various research fields as neuroanatomy, neurophysiology, psychophysics, computer science and engineering, who all had an interest in the study of the visual system and of higher cognitive functions relying on visual perception such as visual consciousness. It argues that British molecular biologist turned South Californian neuroscientist Francis Crick had an early and lasting influence over the Helmholtz Club of which he was a founding pillar, and that from its inception, the club served as a constitutive element in his long-term plans for a neuroscience of vision and of cognition. Further, it argues that in this role, the Helmholtz Club served many purposes, the primary of which was to be a social forum for interdisciplinary discussion, where ‘discussion’ was not mere talk but was imbued with an epistemic value and as such, carefully cultivated. Finally, it questions what counts as ‘doing science’ and in turn, definitions of success and failure—and provides some material evidence towards re-appraising the successfulness of Crick’s contribution to the neurosciences
crick
No full textcrick[PT] ...an' travelled all round every crick an' corner in th' Exploits Bay, an' 'twas in-draft places as far from this nearly to th'islands, you know.(creek ???)YesJ. D. A. WIDDOWSONNot usedNot usedWithdrawnChecked by Jordyn Hughes on Thu 07 Jul 201
Citizenship education: an investigation of Crick’s model and citizenship coordinators’ perceptions of the subject’s purpose
No full textIn 2002 the delivery of Citizenship Education, at Key Stages Three and Four, became
compulsory in English Schools. The National Curriculum Order (QCA, 1999), which
defined the nature of this new subject, drew heavily on the report by the Advisory Group
on Education for Citizenship and the Teaching of Democracy (The Crick Report) (QCA,
1998). This thesis examines Crick’s model of citizenship education and the way that it is
perceived by citizenship coordinators, those teachers most directly responsible for its
delivery. The research methodology involved two major components; a literature based
analysis of Crick’s model and semi structured interviews with ten citizenship
coordinators.
My findings relate to four key research questions. What underlying principles and
philosophies exist regarding the purpose of citizenship education in a Liberal
Democracy? Which principles and philosophies did the Crick Report adopt and how are
these reflected in the National Curriculum subject of ‘Citizenship Education’? What do
citizenship coordinators perceive as the purpose of Citizenship Education, and to what
extent is their approach influenced by theory and policy issues? And finally, Could a
greater understanding of the philosophical underpinnings of Citizenship Education
among citizenship coordinators, improve its provision?
With regard to the first two questions I argue that Crick established a sensible
compromise position between competing conservative and progressive interpretations of
the subject’s purpose. With regard to the third, the interviews with citizenship
coordinators indicate that whilst all showed progressive intentions for the subject the
majority (80%) showed a lack of consistency in their approach, often demonstrating a
much more conservative approach than they intended. I suggest that the reason for this is
a combination of two factors; a lack of conceptual understanding and the impact of
various policy pressures. Finally, addressing the fourth question, I argue that a clear
understanding of the subject’s philosophical underpinnings could have a positive impact
on the problem, and make recommendations about how this may be achieve through
adjustments to both government policy and schools’ training programmes
Deep Engagement as a Complex System:Identity, Learning Power and Authentic Enquiry
No full textThis chapter develops a definition of engagement which is underpinned by a participatory enquiry paradigm and invites an exploration of patterns and relationships between variables rather than a focus on a single variable. It suggests that engagement is best understood as a complex system including a range of inter-related factors internal and external to the learner, in place and in time, which shape his or her engagement with learning opportunities. The implications of this approach are explored first in terms of student identity, learning power and competences; second in terms of student participation in the construction of knowledge through authentic enquiry. Examples are used to illustrate the argument which have been generated from research into the theory and practice of Learning Power and from the Learning Futures programme, in the UK and Australia. The chapter argues that what is necessary for deep engagement in the 21st century is a pedagogy and an assessment system which empowers individuals to become aware of their identity as learners through making choices about both what, where and how they learn, and to make meaningful connections with their life stories and aspirations in authentic pedagogy. In this context the teacher is a facilitator or coach for learning, rather than a purveyor of expert knowledge.This chapter develops a definition of engagement which is underpinned by a participatory enquiry paradigm and invites an exploration of patterns and relationships between variables rather than a focus on a single variable. It suggests that engagement is best understood as a complex system including a range of inter-related factors internal and external to the learner, in place and in time, which shape his or her engagement with learning opportunities. The implications of this approach are explored first in terms of student identity, learning power and competences; second in terms of student participation in the construction of knowledge through authentic enquiry. Examples are used to illustrate the argument which have been generated from research into the theory and practice of Learning Power and from the Learning Futures programme, in the UK and Australia. The chapter argues that what is necessary for deep engagement in the 21st century is a pedagogy and an assessment system which empowers individuals to become aware of their identity as learners through making choices about both what, where and how they learn, and to make meaningful connections with their life stories and aspirations in authentic pedagogy. In this context the teacher is a facilitator or coach for learning, rather than a purveyor of expert knowledge
Isotope-edited variable temperature infrared spectroscopy for measuring transition temperatures of single A-T Watson-Crick base pairs in DNA duplexes
No full textExperimental methods to determine transition temperatures for individual base pair melting events in DNA duplexes are lacking despite intense interest in these thermodynamic parameters. Here, we determine the dimensions of the thymine (T) C2=O stretching vibration when it is within the DNA duplex via iso-topic substitutions at other atomic positions in the structure. After determining that this IR difference probe was localized enough to measure sub-molecular scale structures in high molecular weight complexes, we used this probe to develop a new isotope edited variable temperature infrared method to measure melting at various locations in a DNA structure. As an initial test of this “sub-molecular-scale thermometer”, we first applied our T13C2 difference infrared signal to measure location-dependent melting temperatures (TmL) in a DNA duplex via variable temperature attenuated total reflectance Fourier transform infrared (VT-ATR-FTIR) spectroscopy. We report that the TmL of a single Watson-Crick A-T base pair at the end of an A-T rich duplex is ~34.9±0.7˚C. This is slightly lower than the TmL of a single base pair at the middle position of the duplex (TmL ~35.6±0.2˚C), providing direct physical evidence for end fraying in A-T-rich DNA sequences
How a Low-Fidelity DNA Polymerase Chooses Non-Watson–Crick from Watson–Crick Incorporation
No full textA dogma for DNA polymerase catalysis
is that the enzyme binds DNA
first, followed by MgdNTP. This mechanism contributes to the selection
of correct dNTP by Watson–Crick base pairing, but it cannot
explain how low-fidelity DNA polymerases overcome Watson–Crick
base pairing to catalyze non-Watson–Crick dNTP incorporation.
DNA polymerase X from the deadly African swine fever virus (Pol X)
is a half-sized repair polymerase that catalyzes efficient dG:dGTP
incorporation in addition to correct repair. Here we report the use
of solution structures of Pol X in the free, binary (Pol X:MgdGTP),
and ternary (Pol X:DNA:MgdGTP with dG:dGTP non-Watson–Crick
pairing) forms, along with functional analyses, to show that Pol X
uses multiple unprecedented strategies to achieve the mutagenic dG:dGTP
incorporation. Unlike high fidelity polymerases, Pol X can prebind
purine MgdNTP tightly and undergo a specific conformational change
in the absence of DNA. The prebound MgdGTP assumes an unusual syn conformation stabilized by partial ring stacking with
His115. Upon binding of a gapped DNA, also with a unique mechanism
involving primarily helix αE, the prebound syn-dGTP forms a Hoogsteen base pair with the template anti-dG. Interestingly, while Pol X prebinds MgdCTP weakly, the correct
dG:dCTP ternary complex is readily formed in the presence of DNA.
H115A mutation disrupted MgdGTP binding and dG:dGTP ternary complex
formation but not dG:dCTP ternary complex formation. The results demonstrate
the first solution structural view of DNA polymerase catalysis, a
unique DNA binding mode, and a novel mechanism for non-Watson–Crick
incorporation by a low-fidelity DNA polymerase
Deformed Watson-Crick Base Pair
No full textIn 1953, James Watson and Francis Crick deduced the double helical structure of DNA and immediately inferred its mechanism of replication. This brilliant accomplishment is ranked as one of the most significant stepping stone in the history of biology because it leads to the understanding of gene function at molecular level. Thus, it has been well known that Watson-Crick base pairing is very stable. However, we have found that it is not always the case; Watson-Crick pairing can sometimes form alternate conformations, i.e. the canonical Watson-Crick G/C or A/T hydrogen-bonded base pairs can be either induced to become perpendicular with the base plane or be transformed into stacked pair. Such facile manipulation of Watson-Crick pair in either trans or cis way greatly increases the repertoire for unusual nucleic acid structural motifs and for sequence-specific DNA recognitions.In 1953, James Watson and Francis Crick deduced the double helical structure of DNA and immediately inferred its mechanism of replication. This brilliant accomplishment is ranked as one of the most significant stepping stone in the history of biology because it leads to the understanding of gene function at molecular level. Thus, it has been well known that Watson-Crick base pairing is very stable. However, we have found that it is not always the case; Watson-Crick pairing can sometimes form alternate conformations, i.e. the canonical Watson-Crick G/C or A/T hydrogen-bonded base pairs can be either induced to become perpendicular with the base plane or be transformed into stacked pair. Such facile manipulation of Watson-Crick pair in either trans or cis way greatly increases the repertoire for unusual nucleic acid structural motifs and for sequence-specific DNA recognitions.Abstract 1
1. Introduction 2
2. Experiments Theory
2.1DNA Synthesis 8
2.1.1 Solid phase approach 8
2.1.2 Protection Group Strategy 9
2.1.3 Chemical Synthesis 9
2.2 Sample Purification 13
2.2.1 Reverse phase HPLC 13
2.2.2 Anion exchange HPLC 14
2.2.3 Gel-filtration 14
2.3 NMR Theory 15
2.3.1 NMR phenomenon 15
2.3.2 Vector Model 17
2.3.3 Product Operator Approach 19
2.3.4 Nuclear Overhauser Effect (NOE) 21
2.3.5 One-Dimension Fourier Transform NMR Experiment 21
2.3.6 Two-Dimension Fourier Transform NMR Experiment 22
2.3.7 NMR Experiments in H2O 26
(A) Water suppression method 26
(B) 1D Imino Proton Spectrum 28
(C) 2D NOESY/ H2O 28
2.3.8 NMR Experiments in D2O 31
(a) 2D NOESY 31
(b) DQF-COSY 33
(c) 1H-31P Heteronuclear Correlation Spectrum 33
3. Materials and Methods
3.1 DNA Sample Preparation 34
3.2 Sample Purification 36
3.3 Thermodynamics Studies 38
3.4 NMR experiments 39
3.5 Structure Determination 40
(a) Distance geometry calculation 40
(b) Docking and molecular dynamics 41
4. Results and Discussion
4.1 Novel ActD/5''-GXC/CYG-5'' Complex Structure
4.1.1 Thermodynamics Studies 43
4.1.2 NMR Studies in H2O 45
4.1.3 NMR Studies in D2O 48
4.1.4 Structural Features of the Novel ActD/TA Complex 49
4.1.5 Structural Comparison Between the Novel ActD/5-(GGC)/(CCG)-5''Complex and the Classic ActD/5-(GC)/ (CG)-5'Complex 52
4.1.6 Discussion 53
4.2 Zipper-like Watson-Crick Base Pairs
4.2.1 Thermodynamics Studies 55
4.2.2 NMR Studies in H2O 57
4.2.3 NMR Studies in D2O 58
4.2.4 Structural Determination 63
4.2.5 Structural Features 63
4.2.5 Discussion 65
5. Conclusions 69
Reference
crick (creek)
No full textcreek[PT] From Cape Harrison to Change Islands I _ I don't think there's a crick that was safe to _ for a schooner to stop overnight but I got into. I'm sure o' that. There n'ar crevice.YesJ. D. A. WIDDOWSON JUL 1973Not usedNot usedWithdrawnChecked by Jordyn Hughes on Thu 07 Jul 201
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