10,880 research outputs found
Still flat after all these years
The Universe could be spatially flat, positively curved or negatively curved.
Each option has been popular at various times, partly affected by an
understanding that models tend to evolve away from flatness. The curvature of
the Universe is amenable to measurement, through tests such as the
determination of the angles of sufficiently large triangles. The angle
subtended by the characteristic scale on the Cosmic Microwave sky provides a
direct test, which has now been realised through a combination of exquisite
results from a number of CMB experiments.
After a long and detailed investigation, with many false clues, it seems that
the mystery of the curvature of the Universe is now solved. It's an open and
shut case: the Universe is flat.Comment: 7 pages, 2 figures, submitted to the Gravity Research Foundation
Essay Competition for 200
Symplectic connections, Noncommutative Yang Mills theory and Supermembranes
In built noncommutativity of supermembranes with central charges in eleven
dimensions is disclosed. This result is used to construct an action for a
noncommutative supermembrane where interesting topological terms appear. In
order to do so, we first set up a global formulation for noncommutative Yang
Mills theory over general symplectic manifolds. We make the above constructions
following a pure geometrical procedure using the concept of connections over
Weyl algebra bundles on symplectic manifolds. The relation between
noncommutative and ordinary supermembrane actions is discussed.Comment: 18 page
The Role Body-Esteem Plays in Impairment Associated with Hair-Pulling and Skin Picking in Adolescents
Trichotillomania (hair pulling disorder, HPD) and pathological skin picking (PSP) are associated with significant rates of psychosocial impairment and distress. Little research has addressed the physical consequences and associated impairment in youth (e.g., poor body-esteem). The present study explores the relationship between body-esteem, skin picking (SP), and pulling-related impairment in a sample of adolescents with primary HPD. Ninety four adolescents who pull their hair, 40 of whom also pick their skin, were recruited via internet-sampling as part of the Child and Adolescent Trichotillomania Impact Study (CA-TIP). All youth and a parent completed anonymous questionnaires online assessing psychiatric symptoms, repetitive behaviors, and psychosocial impairment, among other variables. Appearance-based body-esteem was not found to be predictive of more severe psychosocial impairment in these youth. However, SP, in combination with HPD, contributed to worse appearance-based body-esteem above and beyond symptoms of HPD alone. The current study suggests that psychosocial functioning in youth with HPD is less impacted by body-esteem or pulling than other factors (e.g., depression and anxiety), and that SP contributes to lowered body-esteem. These findings suggest the importance of addressing body-esteem in case conceptualization for youth with both HPD and SP. Further research is required to confirm these suggestions
What's black and white about the grey matter?
In 1873 Camillo Golgi discovered his eponymous stain, which he called la reazione nera. By adding to it the concepts of the Neuron Doctrine and the Law of Dynamic Polarisation, Santiago Ramon y Cajal was able to link the individual Golgi-stained neurons he saw down his microscope into circuits. This was revolutionary and we have all followed Cajal's winning strategy for over a century. We are now on the verge of a new revolution, which offers the prize of a far more comprehensive description of neural circuits and their operation. The hope is that we will exploit the power of computer vision algorithms and modern molecular biological techniques to acquire rapidly reconstructions of single neurons and synaptic circuits, and to control the function of selected types of neurons. Only one item is now conspicuous by its absence: the 21st century equivalent of the concepts of the Neuron Doctrine and the Law of Dynamic Polarisation. Without their equivalent we will inevitably struggle to make sense of our 21st century observations within the 19th and 20th century conceptual framework we have inherite
Quantum Geometry and its Implications for Black Holes
General relativity successfully describes space-times at scales that we can
observe and probe today, but it cannot be complete as a consequence of
singularity theorems. For a long time there have been indications that quantum
gravity will provide a more complete, non-singular extension which, however,
was difficult to verify in the absence of a quantum theory of gravity. By now
there are several candidates which show essential hints as to what a quantum
theory of gravity may look like. In particular, loop quantum gravity is a
non-perturbative formulation which is background independent, two properties
which are essential close to a classical singularity with strong fields and a
degenerate metric. In cosmological and black hole settings one can indeed see
explicitly how classical singularities are removed by quantum geometry: there
is a well-defined evolution all the way down to, and across, the smallest
scales. As for black holes, their horizon dynamics can be studied showing
characteristic modifications to the classical behavior. Conceptual and physical
issues can also be addressed in this context, providing lessons for quantum
gravity in general. Here, we conclude with some comments on the uniqueness
issue often linked to quantum gravity in some form or another.Comment: 16 pages, Plenary talk at ``Einstein's Legacy in the New Millenium,''
Puri, India, December 200
The JBoss Integration Plug-in for IntelliJ IDEA, Part 2
This paper describes how to add a stateless session bean. It is stateless because we are not concerned with remembering values of attributes between successive calls from the client. This paper also demonstrates that our session bean can be either remote (i.e., a bean with a remote interface) or it can be local (a bean with a local interface)
The JBoss Integration Plug-in for IntelliJ IDEA, Part 3
This column builds upon our project by describing how to add a servlet for accessing the EJB methods implemented previously
The JBoss Integration Plug-in for IntelliJ IDEA, Part 1
The IntelliJ IDEA is an Integrated Development Environment (IDE) used for Java development. It is known for its strong refactoring capabilities. It is a closed-source, proprietary product, which is used in both educational and industrial settings. IntelliJ functionality is extended by a set of open APIs that third-party developers can use to integrate their solutions by the development of plug-ins
The JBoss Integration Plug-in for IntelliJ IDEA, Part 4
Without an automated environment, deployment is often a painful process resulting in developers spending a great deal of time performing application deployment tasks. Most organizations strive for better management of this critical phase in the development cycle
New fabrication technique for highly sensitive qPlus sensor with well-defined spring constant
A new technique for the fabrication of highly sensitive qPlus sensor for
atomic force microscopy (AFM) is described. Focused ion beam was used to cut
then weld onto a bare quartz tuning fork a sharp micro-tip from an
electrochemically etched tungsten wire. The resulting qPlus sensor exhibits
high resonance frequency and quality factor allowing increased force gradient
sensitivity. Its spring constant can be determined precisely which allows
accurate quantitative AFM measurements. The sensor is shown to be very stable
and could undergo usual UHV tip cleaning including e-beam and field evaporation
as well as in-situ STM tip treatment. Preliminary results with STM and AFM
atomic resolution imaging at of the silicon
surface are presented.Comment: 5 pages, 3 figure
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