Comments on "A New CT-Aided Stereotactic Neurosurgery Technique"

The method given for finding the position of a target in three-dimensional space from a CT image is incorrect. The solution is based on representation of the target vector as a linear combination of two coplanar nonparallel vectors. This results in a single linear equation with two unknowns. An alternative formulation is offered, solved, and the existence and uniqueness of the solution is proved.     

The problems in quantum foundations in the light of gauge theories

We review the issues of nonseparability and seemingly acausal propagation of information in EPR, as displayed by experiments and the failure of Bell's inequalities. We show that global effects are in the very nature of the geometric structure of modern physical theories, occurring even at the classical level. The Aharonov-Bohm effect, magnetic monopoles, instantons, etc. result from the topology and homotopy features of the fiber bundle manifolds of gauge theories. The conservation of probabilities, a supposedly highly quantum effect, is also achieved through global geometry equations. The EPR observables all fit in such geometries, and space-time is a truncated representation and is not the correct arena for their understanding. Relativistic quantum field theory represents the global action of the measurement operators as the zero-momentum (and therefore spatially infinitely spread) limit of their wave functions (form factors). We also analyze the collapse of the state vector as a case of spontaneous symmetry breakdown in the apparatus-observed state interaction.Work supported in part by U.S. DOE Grant DE-FG05-85ER40200.Wolfson Chair Extraordinary in Theoretical Physics, TAUP N-161-85.     

On the symmetric square Unstable twisted characters

We provide a purely local computation of the (elliptic) twisted (by “transpose-inverse”) character of the representationπ=I(1) of PGL(3) over ap-adic field induced from the trivial representation of the maximal parabolic subgroup. This computation is independent of the theory of the symmetric square lifting of [IV] of automorphic and admissible representations of SL(2) to PGL(3). It leads — see [FK] — to a proof of the (unstable) fundamental lemma in the theory of the symmetric square lifting, namely that corresponding spherical functions (on PGL(2) and PGL(3)) are matching: they have matching orbital integrals. The new case in [FK] is the unstable one. A direct local proof of the fundamental lemma is given in [V].     

A simple derivation of Borland's locality result

A new proof of Borland's localization theorem is given, which is simpler, less rigorous, but gives more quantitative results.     

Quantizing gravity and spacetime: Where do we stand ?

We review five possible solutions to the riddle posed by Quantum Gravity: (1) Gravity should stay as a classical theory (L. Rosenfeld); (2) Quantum Gravity requires a formalism which will take the human mind (or the intelligent observer) into account, resolving at the same time the riddle of the collapse of the wave function/state vector in Quantum Mechanics in general (Penrose); (3) Perturbative Quantization; (4) Hamiltonian Quantization (Dirac, Ashtekar); (5) String Theory. We also discuss the quantization of spacetime.     

Gravity from symmetry breakdown of a gauge affine theory

We construct a gauge field theory based on GA(4, ) space-time symmetry containing spinorial and tensorial (infinite-component) matter manifields. We break the dilation symmetry and thus trigger a spontaneous breaking of the SL(4, )/SO(1, 3), also generating Newton's constant. The resulting ‘large-scale” space-time (a compared to Planck length) is of Riemann-Cartan type and in the flat limit we recover special relativity.     

Foliar Delivery of siRNA Particles for Treating Viral Infections in Agricultural Grapevines

Grapevine leafroll disease (GLD) is a globally spreading viral infection that causes major economic losses by reducing crop yield, plant longevity, and berry quality, with no effective treatment. Grapevine leafroll associated virus-3 (GLRaV-3) is the most severe, prevalent GLD strain affecting wine production. Here, the ability of RNA interference (RNAi), a non-GMO gene-silencing pathway, to treat GLRaV-3 in infected Cabernet Sauvignon grapevines is evaluated. Lipid-modified polyethylenimine (lmPEI) is synthesized as the carrier for long double-stranded RNA (dsRNA, 250-bp-long) that targets RNA polymerase and coat protein is a gene target that are conserved in the GLRaV-3 genome. Self-assembled dsRNA–lmPEI particles, 220 nm in diameter, display inner ordered domains spaced 7.3 ± 2 nm from one another, correlating to lmPEI wrapping spirally around the dsRNA. The particles effectively protect RNA from degradation by ribonucleases and show to increase uptake rate into plant cells as a result of the lipid component comprising the RNA carrier. In three field experiments, a single dose of foliar sprayed treatment of the RNA-particles knocks down GLRaV-3 titer, and multiple doses of the treatment keep the viral titer at baseline and trigger recovery of the vine and berries. This study demonstrates RNAi as a promising platform for treating viral diseases in agriculture.