The objectives of this study were to develop a high-density chromosome bin map of homoeologous group 7 in hexaploid wheat, to identify gene distribution in these chromosomes, and to perform comparative studies of wheat with rice and barley. We mapped 2148 loci from 919 EST clones onto group 7 chromosomes of wheat. In the majority of cases the numbers of loci were significantly lower in the centromeric regions and tended to increase in the distal regions. The level of duplicated loci (...) in this group was 24% with most of these loci being localized toward the distal regions. One hundred nineteen EST probes that hybridized to three fragments and mapped to the three group 7 chromosomes were designated landmark probes and were used to construct a consensus homoeologous group 7 map. An additional 49 probes that mapped to 7AS, 7DS, and the ancestral translocated segment involving 7BS also were designated landmarks. Landmark probe orders and comparative maps of wheat, rice, and barley were produced on the basis of corresponding rice BAC/PAC and genetic markers that mapped on chromosomes 6 and 8 of rice. Identification of landmark ESTs and development of consensus maps may provide a framework of conserved coding regions predating the evolution of wheat genomes. (shrink)

A total of 1918 loci, detected by the hybridization of 938 expressed sequence tag unigenes from 26 Triticeae cDNA libraries, were mapped to wheat homoeologous group 4 chromosomes using a set of deletion, ditelosomic, and nulli-tetrasomic lines. The 1918 EST loci were not distributed uniformly among the three group 4 chromosomes; 41, 28, and 31% mapped to chromosomes 4A, 4B, and 4D, respectively. This pattern is in contrast to the cumulative results of EST mapping in all homoeologous groups, as reported (...) elsewhere, that found the highest proportion of loci mapped to the B genome. Sixty-five percent of these 1918 loci mapped to the long arms of homoeologous group 4 chromosomes, while 35% mapped to the short arms. The distal regions of chromosome arms showed higher numbers of loci than the proximal regions, with the exception of 4DL. This study confirmed the complex structure of chromosome 4A that contains two reciprocal translocations and two inversions, previously identified. An additional inversion in the centromeric region of 4A was revealed. A consensus map for homoeologous group 4 was developed from 119 ESTs unique to group 4. Forty-nine percent of these ESTs were found to be homoologous to sequences on rice chromosome 3, 12% had matches with sequences on other rice chromosomes, and 39% had no matches with rice sequences at all. Limited homology was found between wheat ESTs on homoeologous group 4 and the Arabidopsis genome. Forty-two percent of the homoeologous group 4 ESTs could be classified into functional categories on the basis of blastX searches against all protein databases. (shrink)

The complex hexaploid wheat genome offers many challenges for genomics research. Expressed sequence tags facilitate the analysis of gene-coding regions and provide a rich source of molecular markers for mapping and comparison with model organisms. The objectives of this study were to construct a high-density EST chromosome bin map of wheat homoeologous group 2 chromosomes to determine the distribution of ESTs, construct a consensus map of group 2 ESTs, investigate synteny, examine patterns of duplication, and assess the colinearity with rice (...) of ESTs assigned to the group 2 consensus bin map. A total of 2600 loci generated from 1110 ESTs were mapped to group 2 chromosomes by Southern hybridization onto wheat aneuploid chromosome and deletion stocks. A consensus map was constructed of 552 ESTs mapping to more than one group 2 chromosome. Regions of high gene density in distal bins and low gene density in proximal bins were found. Two interstitial gene-rich islands flanked by relatively gene-poor regions on both the short and long arms and having good synteny with rice were discovered. The map locations of two ESTs indicated the possible presence of a small pericentric inversion on chromosome 2B. Wheat chromosome group 2 was shown to share syntenous blocks with rice chromosomes 4 and 7. (shrink)

DBS Think Tank IX was held on August 25–27, 2021 in Orlando FL with US based participants largely in person and overseas participants joining by video conferencing technology. The DBS Think Tank was founded in 2012 and provides an open platform where clinicians, engineers and researchers can freely discuss current and emerging deep brain stimulation technologies as well as the logistical and ethical issues facing the field. The consensus among the DBS Think Tank IX speakers was that DBS expanded in (...) its scope and has been applied to multiple brain disorders in an effort to modulate neural circuitry. After collectively sharing our experiences, it was estimated that globally more than 230,000 DBS devices have been implanted for neurological and neuropsychiatric disorders. As such, this year’s meeting was focused on advances in the following areas: neuromodulation in Europe, Asia and Australia; cutting-edge technologies, neuroethics, interventional psychiatry, adaptive DBS, neuromodulation for pain, network neuromodulation for epilepsy and neuromodulation for traumatic brain injury. (shrink)

Quomodo versus lyrici legendi sint, plerumque inter metricos constat, licet de origine singulorum versuum vel colorum dubia moveantur; at ne illud quidem confirmari potest in genere illo peculiari, quo multae strophae Pindari et Bacchylidis et nonnullae poétarum scenicorum compositae sunt. Quod in talibus versibus maxime conspicuum est, hoc est, quod metra τоû σоυ et διπλασíоυ γéνоυς; in eis coniunguntur vel coniungi videntur, ita, ut ambitus utriusque partis aut par aut non multum maior minorve sit. lam antiqui metrici parum compertum habebant, (...) qua ratione eiusmodi versus explicarent. Cum maior pars ceterorum versuum lyricorum etiam post Alexandri aetatem in usu essent et doctrina grammaticorum hanc quoque materiam complecteretur, pauca versuum illorum vestigia remanebant, postquam chori lyrici et dramatici conticuerunt. Habemus quidem Meliambos Cercidae eodem genere carmina pangere conati, quo clarissimi illi veteres, sed eos perlegentes statim sentimus artem intermortuam non ab isto Megalopolitano nova vita donatam esse; nihil enim frigidius cogitari potest, quam si quis oda pindarica recitata ad Cercidae versus se convertat eosque alta voce pronuntiare conetur. Metrici graeci et romani praeter paucos versus eosque singillatim genus nostrum non tractant nee quisquam ex eorum numero de genere toto disseruit. Horatium et suamet ipsum arte prae ceteris excellentem et doctrina metrica haud mediocriter imbutum non aliter ac nos huius aevi philologos nescire, quomodo carmina pindarica ab ipso poeta componerentur, ex Oda notissima patet, in qua Pindarum quisquis studet aemulari frustra in re desperata desudare perhibetur. Ad universam lyricorum graecorum artem pertinent, quae a Cicerone in Oratore affirmantur, qui tamen clausulis orationis numerosae operam dans rem metricam non neglexit: sed in versibus res est apertior, quamquam etiam a modis quibusdam cantu remoto soluta esse videatur oratio, maximeque id in optima quoque eorum poëtarum, qui λυρικоí a graecis nominantur, quos, cum cantu spoliaveris, nuda paene remanet oratio. Causam hanc vel maximam esse puto in nullo alio carmina pangendi genere musicam, saltationem, metrum tam arte cohaesisse; cum poësis non iam pars habebatur υθμιξου, quod φθγγοδ, σχμα, συλλαβ definiebant, ut Aristoxeni terminis utar , via stabilita ambitum singulorum versuum ac colorum statuere conarentur et indoloem pedum metricorum conicendo indicarent. (shrink)

This paper outlines the qualitative foundations of a “quasiclassical” theory in which particles are pictured as spatially extended periodic excitations of a universal background field, interacting with each other via nonlinearity in the equations of motion for that field, and undergoing collapse to a much smaller volume if and when they are detected. The theory is based as far as possible directly on experiment, rather than on the existing quantum mechanical formalism, and it offers simple physical interpretations of such concepts (...) as mass, 4-momentum, interaction, potentials, and quantization; it may lead directly to the standard equations of quantum theory, such as the multiparticle Schrödinger equation, without going through the conventional process of “quantizing” a classical theory. The theory also provides an alternative framework in which to discuss wave-particle duality and the quantum “measurement problem”; in particular, it is suggested that the unpredictability of quantum phenomena may arise from “deterministic chaos” in the behavior of the background field. (shrink)

In this paper an attempt is made to interpret inertial mass as a consequence of the invariant periodicity associated with physical de Broglie waves. In the case of a free particle, such waves, observed from an arbitrary reference frame, would exhibit the velocity-dependent wavelength given by de Broglie's relation; and it is conjectured that the inertial and additive properties of mass (or, more precisely, the conservation of momentum and energy) can be related to nonlinear interference effects occurring between the de (...) Broglie waves for different particles. This picture could throw light on the physical meaning of quantization and suggests the possibility of reformulating classical and quantum mechanics in terms of a “quasi-classical” nonlinear field theory in which both inertial and quantization effects result essentially from the periodicity of de Broglie waves. (shrink)

The author has recently proposed a “quasi-classical” theory of particles and interactions in which particles are pictured as extended periodic disturbances in a universal field χ(x, t), interacting with each other via nonlinearity in the equation of motion for χ. The present paper explores the relationship of this theory to nonrelativistic quantum mechanics; as a first step, it is shown how it is possible to construct from χ a configuration-space wave function Ψ(x 1,x 2,t), and that the theory requires that (...) Ψ satisfy the two-particle Schrödinger equation in the case where the two particles are well separated from each other. This suggests that the multiparticle Schrödinger equation can be obtained as a direct consequence of the quasi-classical theory without any use of the usual formalism (Hilbert space, quantization rules, etc.) of conventional quantum theory and in particular without using the classical canonical treatment of a system as a “crutch” theory which has subsequently to be “quantized.” The quasi-classical theory also suggests the existence of a preferred “absolute” gauge for the electromagnetic potentials. (shrink)

It is shown that an approach to quantum phenomena in which charged particles are treated as macroscopically extended periodic disturbances in a nonlinear c-number field, interacting with each other via massless excitations of that field, leads almost uniquely to the five basic equations of classical electrodynamics: the Lorentz force law and Maxwell's equations. The fundamental electromagnetic quantity in this approach is the 4-vector potential Aα—interpreted absolutely as a measure of the local shift of each particle off its mass shell—rather than (...) theE andB fields, and it thus provides a new viewpoint on the questions of Aharonov-Bohm phase shifts, the existence of magnetic monopoles, and the role of gauge invariance. (shrink)