Quantum Mechanics on Manifolds Embedded in Euclidean Space

Quantum particles confined to surfaces in higher dimensional spaces are acted upon by forces that exist only as a result of the surface geometry and the quantum mechanical nature of the system. The dynamics are particularly rich when confinement is implemented by forces that act normal to the surface. We review this confining potential formalism applied to the confinement of a particle to an arbitrary manifold embedded in a higher dimensional Euclidean space. We devote special attention to the geometrically induced gauge potential that appears in the effective Hamiltonian for motion on the surface. We emphasize that the gauge potential is only present when the space of states describing the degrees of freedom normal to the surface is degenerate. We also distinguish between the effects of the intrinsic and extrinsic geometry on the effective Hamiltonian and provide simple expressions for the induced scalar potential. We discuss examples including the case of a 3-dimensional manifold embedded in a 5-dimensional Euclidean space.Comment: 12 pages, LaTe

Quarkonium production via recombination

The contrast between model predictions for the transverse momentum spectra of J/Psi observed in Au-Au collisions at RHIC is extended to include effects of nuclear absorption. We find that the difference between initial production and recombination is enhanced in the most central collisions. Models utilizing a combination of these sources may eventually be able to place constraints on their relative magnitudes.Comment: Based on invited plenary talk at the 2nd International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, Asilomar, CA, June 9-16, 2006, to be published in Nucl. Phys.

Characterizing Width Uniformity by Wave Propagation

This work describes a novel image analysis approach to characterize the uniformity of objects in agglomerates by using the propagation of normal wavefronts. The problem of width uniformity is discussed and its importance for the characterization of composite structures normally found in physics and biology highlighted. The methodology involves identifying each cluster (i.e. connected component) of interest, which can correspond to objects or voids, and estimating the respective medial axes by using a recently proposed wavefront propagation approach, which is briefly reviewed. The distance values along such axes are identified and their mean and standard deviation values obtained. As illustrated with respect to synthetic and real objects (in vitro cultures of neuronal cells), the combined use of these two features provide a powerful description of the uniformity of the separation between the objects, presenting potential for several applications in material sciences and biology.Comment: 14 pages, 23 figures, 1 table, 1 referenc

Genetic Transformation of Quercus ilex Somatic Embryos with a Gnk2-like Protein That Reveals a Putative Anti-Oomycete Action

Holm oak is a key tree species in Mediterranean ecosystems, whose populations have been increasingly threatened by oak decline syndrome, a disease caused by the combined action of Phytophthora cinnamomi and abiotic stresses. The aim of the present study was to produce holm oak plants that overexpress the Ginkbilobin-2 homologous domain gene (Cast_Gnk2-like) that it is known to possess antifungal properties. Proembryogenic masses (PEMs) isolated from four embryogenic lines (Q8, E2, Q10-16 and E00) were used as target explants. PEMs were co-cultured for 5 days with Agrobacterium EHA105pGnk2 and then cultured on selective medium containing kanamycin (kan) and carbenicillin. After 14 weeks on selective medium, the transformation events were observed in somatic embryos of lines Q8 and E2 and a total of 4 transgenic lines were achieved. The presence of the Cast_Gnk2-like gene on transgenic embryos was verified by PCR, and the number of transgene copies and gene expression was estimated by qPCR. Transgenic plants were obtained from all transgenic lines after cold storage of the somatic embryos for 2 months and subsequent transfer to germination medium. In an in vitro tolerance assay with the pathogen P. cinnamomi, we observed that transgenic plants were able to survive longer than wild typeinfo:eu-repo/semantics/publishedVersio

Andrological, pathologic, morphometric, and ultrasonographic findings in rams experimentally infected with Brucella ovis

AbstractBrucella ovis is considered the most important infectious cause of reproductive disorders in sheep. The disease is characterized by epididymitis, subfertility and infertility in rams. B. ovis occasionally results in abortion in ewes, as well. The aim of this study was to evaluate kinetic changes in the reproductive organs of rams experimentally infected with B. ovis. Nine rams were experimentally inoculated intrapreputially with 2mL of a suspension containing 1.2×109CFU (colony-forming units)/mL of B. ovis (strain ATCC25840). In addition, 50μL of a suspension containing 1.2×1010CFU/mL of the same B. ovis strain was inoculated into each conjunctival sac, resulting in 3.6×109CFU total per ram. Six of nine infected rams had developed clinical changes in the tail of the epididymis at 30 days post-infection (dpi), but these changes regressed in 50% of these rams. Ultrasound demonstrated an increase in the area of the tail of the epididymis (P<0.001), reduction in the area of the testes (P<0.001), and an increased length and width of the seminal vesicles (P<0.001) during the course of infection. A sperm granuloma was diagnosed on the basis of ultrasonography findings. Microscopically, there was epididymitis, testicular degeneration, and seminal vesiculitis. Inflammatory cells were detected in the semen even before the development of epididymitis. Moreover, inflammatory cells were also found in the semen of asymptomatic rams, indicating that the presence of leukocytes in the ejaculate is a valuable method for screening potential carriers of infections in the genital tract

Distance technical education: Brazilian case study

This paper presents research results about online distance technical courses. The aim of the research was to analyze the online pedagogical practices developed as the need for technical training of each course. The main question was: Is it possible to develop technical training at a distance? We followed four different distance technical courses in three different regions of Brazi

Dynamic regulation of GATA transcription factors in hematopoiesis

The hematopoietic system is composed of a variety of cells, whose activity is essential for the normal functioning of an organism. Erythrocytes, or red blood cells, transport oxygen and carbon dioxide throughout the body, platelets are essential for coagulation and white blood cells (lymphocytes, granulocytes and macrophages) are responsible for the protection of the organism against pathogens. All these different cells originate from a single cell type, the hematopoietic stem cell (HSC), through a process denominated hematopoiesis. To understand how the HSC can originate so many different cell type has been the aim of many scientists over the years. Advances in molecular biology tools allowed the gathering of vast amounts of information about the hematopoietic system and the process of hematopoiesis. However, many questions remain without answers. The HSC gives rise to the different hematopoetic cell lineages via a series of steps. HSCs are rare cells that have the capacity to duplicate themselves (self-renewal) as well as to give rise to all the different hematopoietic cell types (pluripotency). The descendants of the HSC are still able to give rise to all hematopoietic lineages but they lose the ability to self-renew. These cells will further differentiate into other cells that can give rise to an increasingly restricted number of hematopoietic lineages until they reach a stage were they can only differentiate into a single lineage. Such process is called lineage-commitment and its accuracy is essential for the normal function of the hematopoietic system. How this lineage commitment occurs is as yet not clear. It is known that it is dependent on environmental cues as

Identification of Radial Glia-like Cells in the Adult Mouse Olfactory Bulb

Immature neurons migrate tangentially within the rostral migratory stream (RMS) to the adult olfactory bulb (OB), then radially to their final positions as granule and periglomerular neurons; the controls over this transition are not well understood. Using adult transgenic mice with the human GFAP promoter driving expression of enhanced GFP, we identified a population of radial glia-like cells that we term adult olfactory radial glia-like cells (AORGs). AORGs have large, round somas and simple, radially oriented processes. Confocal reconstructions indicate that AORGs variably express typical radial glial markers, only rarely express mouse GFAP, and do not express astroglial, oligodendroglial, neuronal, or tanycyte markers. Electron microscopy provides further supporting evidence that AORGs are not immature neurons. Developmental analyses indicate that AORGs are present as early as P1, and are generated through adulthood. Tracing studies show that AORGs are not born in the SVZa, suggesting that they are born either in the RMS or the OB. Migrating immature neurons from the adult SVZa are closely apposed to AORGs during radial migration in vivo and in vitro. Taken together, these data indicate a newly-identified population of radial glia-like cells in the adult OB that might function uniquely in neuronal radial migration during adult OB neurogenesis.Stem Cell and Regenerative Biolog

J/ψJ/\psi production in PHENIX

Heavy quarkonia production is expected to be sensitive to the formation of a quark gluon plasma (QGP). The PHENIX experiment has measured $J/\psi$ production at $\sqrt{s_{NN}}=$~200 GeV in Au+Au and Cu+Cu collisions, as well as in reference p+p and d+Au runs. $J/\psi$'s were measured both at mid ($|y|<0.35$) and forward ($1.2<|y|<2.2$) rapidity. In this letter, we present the A+A preliminary results and compare them to normal cold nuclear matter expectations derived from PHENIX d+Au and p+p measurements as well as to theoretical models including various effects (color screening, recombination, sequential melting...).Comment: 5 pages, 7 figures. To appear in the proceedings of Hot Quarks 2006: Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions, Villasimius, Italy, 15-20 May 200

Convergence to equilibrium for the discrete coagulation-fragmentation equations with detailed balance

Under the condition of detailed balance and some additional restrictions on the size of the coefficients, we identify the equilibrium distribution to which solutions of the discrete coagulation-fragmentation system of equations converge for large times, thus showing that there is a critical mass which marks a change in the behavior of the solutions. This was previously known only for particular cases as the generalized Becker-D\"oring equations. Our proof is based on an inequality between the entropy and the entropy production which also gives some information on the rate of convergence to equilibrium for solutions under the critical mass.Comment: 28 page