Supersymmetric Yang-Mills and Supergravity Amplitudes at One Loop

By applying the known expressions for SYM and SUGRA tree amplitudes, we write generating functions for the NNMHV box coefficients of SYM as well as the MHV, NMHV, and NNMHV box coefficients for SUGRA. The all-multiplicity generating functions utilize covariant, on-shell superspace whereby the contribution from arbitrary external states in the supermultiplet can be extracted by Grassmann operators. In support of the relation between dual Wilson loops and SYM scattering amplitudes at weak coupling, the SYM amplitudes are presented in a manifestly dual superconformal form. We introduce ordered box coefficients for calculating SUGRA quadruple cuts and prove that ordered coefficients generate physical cut amplitudes after summing over permutations of the external legs. The ordered box coefficients are produced by sewing ordered subamplitudes, previously used in applying on-shell recursion relations at tree level. We describe our verification of the results against the literature, and a formula for extracting the contributions from external gluons or gravitons to NNMHV superamplitudes is presented.Comment: 46 pages, 2 figures, additional references and clarifications include

Use of Residential Care in Europe for Children Aged Under Three: Some Lessons from Neurobiology

This critical commentary reviews the research into the use of residential care for children aged under three years and looks at some of the explanations that can be found for this in neurobiology. There continue to be high numbers and rates of these vulnerable children in institutions not only in the former Soviet states, but also in Western Europe. The new research provides strong evidence on the negative consequences for these children, particularly for those who remain in institutional care beyond the age of six months. Explanations from neurobiology sit well beside understandings drawn from attachment theory and start to show the mechanisms for this and also the ability of the brain to compensate

AgRISTARS: Supporting research. Spring small grains planting date distribution model

A model was developed using 996 planting dates at 51 LANDSAT segments for spring wheat and spring barley in Minnesota, Montana, North Dakota, and South Dakota in 1979. Daily maximum and minimum temperatures and precipitation were obtained from the cooperative weather stations nearest to each segment. The model uses a growing degree day summation modified for daily temperature range to estimate the beginning of planting and uses a soil surface wetness variable to estimate how a fixed number of planting days are distributed after planting begins. For 1979, the model predicts first, median, and last planting dates with root mean square errors of 7.91, 6.61, and 7.09 days, respectively. The model also provides three or four dates to represent periods of planting activity within the planting season. Although the full model was not tested on an independent data set, it may be suitable in areas other than the U.S. Great Plains where spring small grains are planted as soon as soil and air temperatures become warm enough in the spring for plant growth

Linear-phase approximation in the triangular facet near-field physical optics computer program

Analyses of reflector antenna surfaces use a computer program based on a discrete approximation of the radiation integral. The calculation replaces the actual surface with a triangular facet representation; the physical optics current is assumed to be constant over each facet. Described here is a method of calculation using linear-phase approximation of the surface currents of parabolas, ellipses, and shaped subreflectors and compares results with a previous program that used a constant-phase approximation of the triangular facets. The results show that the linear-phase approximation is a significant improvement over the constant-phase approximation, and enables computation of 100 to 1,000 lambda reflectors within a reasonable time on a Cray computer

Tree-level Split Helicity Amplitudes in Ambitwistor Space

We study all tree-level split helicity gluon amplitudes by using the recently proposed BCFW recursion relation and Hodges diagrams in ambitwistor space. We pick out the contributing diagrams and find that all of them can be divided into triangles in a suitable way. We give the explicit expressions for all of these amplitudes. As an example, we reproduce the six gluon split NMHV amplitudes in momentum space.Comment: 20 pages, 16 figures; minor changes; clarifications added, 22 pages, 16 figure

Extending Quantum Coherence in Diamond

We experimentally demonstrate over two orders of magnitude increase in the coherence time of nitrogen vacancy centres in diamond by implementing decoupling techniques. We show that equal pulse spacing decoupling performs just as well as non-periodic Uhrig decoupling and has the additional benefit that it allows us to take advantage of "revivals" in the echo (due to the coherent nature of the bath) to explore the longest coherence times. At short times, we can extend the coherence of particular quantum states out from T_2*=2.7 us out to an effective T_2 > 340 us. For preserving arbitrary states we show the experimental importance of using pulse sequences, that through judicious choice of the phase of the pulses, compensate the imperfections of individual pulses for all input states. At longer times we use these compensated sequences to enhance the echo revivals and show a coherence time of over 1.6 ms in ultra-pure natural abundance 13C diamond.Comment: 7 pages, 7 figures; minor syntax/typo. changes and updated reference

On the nonlinear deformation geometry of Euler-Bernoulli beams

Nonlinear expressions are developed to relate the orientation of the deformed beam cross section, torsion, local components of bending curvature, angular velocity, and virtual rotation to deformation variables. The deformed beam kinematic quantities are proven to be equivalent to those derived from various rotation sequences by identifying appropriate changes of variable based on fundamental uniqueness properties of the deformed beam geometry. The torsion variable used is shown to be mathematically analogous to an axial deflection variable commonly used in the literature. Rigorous applicability of Hamilton's principle to systems described by a class of quasi-coordinates that includes these variables is formally established

Hingeless helicopter rotor with improved stability

Improved stability was provided in a hingeless helicopter rotor by inclining the principal elastic flexural axes and coupling pitching of the rotor blade with the lead-lag bending of the blade. The primary elastic flex axes were inclined by constructing the blade of materials that display non-uniform stiffness, and the specification described various cross section distributions and the resulting inclined flex axes. Arrangements for varying the pitch of the rotor blade in a predetermined relationship with lead-lag bending of the blade, i.e., bending of the blade in a plane parallel to its plane of rotation were constructed

New design of hingeless helicopter rotor improves stability

Cantilever blades are attached directly to rotor hub, thereby substantially reducing cost and complexity and increasing reliability of helicopter rotor. Combination of structural flap-lag coupling and pitch-lag coupling provides damping of 6 to 10%, depending on magnitude of coupling parameters

Dyspraxia in a patient with corticobasal degeneration: the role of visual and tactile inputs to action

Objectives-To investigate the roles of visual and tactile information in a dyspraxic patient with corticobasal degeneration (CBD) who showed dramatic facilitation in miming the use of a tool or object when he was given a tool to manipulate; and to study the nature of the praxic and neuropsychological deficits in CBD. Methods-The subject had clinically diagnosed CBD, and exhibited alien limb behaviour and striking ideomotor dyspraxia. General neuropsychological evaluation focused on constructional and visuospatial abilities, calculation, verbal fluency, episodic and semantic memory, plus spelling and writing because impairments in this domain were presenting complaints. Four experiments assessed the roles of visual and tactile information in the facilitation of motor performance by tools. Experiment I evaluated the patient's performance of six limb transitive actions under six conditions: (1) after he described the relevant tool from memory, (2) after he was shown a Line drawing of the tool, (3) after he was shown a real exemplar of the tool, (4) after he watched the experimenter perform the action, (5) while he was holding the tool, and (6) immediately after he had performed the action with the tool but with the tool removed from his grasp. Experiment 2 evaluated the use of the same six tools when the patient had tactile but no visual information (while he was blindfolded). Experiments 3 and 4 assessed performance of actions appropriate to the same six tools when the patient had either neutral or inappropriate tactile feedback-that is, while he was holding a non-tool object or a different tool. Results-Miming of tool use was not facilitated by visual input; moreover, lack of visual information in the blindfolded condition did not reduce performance. The principal positive finding was a dramatic facilitation of the patient's ability to demonstrate object use when he was holding either the appropriate tool or a neutral object. Tools inappropriate to the requested action produced involuntary performance of the stimulus relevant action. Conclusions-Tactile stimulation was paramount in the facilitation of motor performance in tool use by this patient with CBD. This outcome suggests that tactile information should be included in models which hypothesise modality specific inputs to the action production system. Significant impairments in spelling and letter production that have not previously been reported in CBD have also been documented