Remarks on Finite W Algebras

The property of some finite W algebras to be the commutant of a particular subalgebra of a simple Lie algebra G is used to construct realizations of G. When G=so(4,2), unitary representations of the conformal and Poincare algebras are recognized in this approach, which can be compared to the usual induced representation technique. When G=sp(2,R) or sp(4,R), the anyonic parameter can be seen as the eigenvalue of a W generator in such W representations of G. The generalization of such properties to the affine case is also discussed in the conclusion, where an alternative of the Wakimoto construction for sl(2) level k is briefly presented. This mini review is based on invited talks presented by P. Sorba at the ``Vth International Colloquium on Quantum Groups and Integrable Systems'', Prague (Czech Republic), June 1996; ``Extended and Quantum Algebras and their Applications to Physics'', Tianjin (China), August 1996; ``Selected Topics of Theoretical and Modern Mathematical Physics'', Tbilisi (Georgia), September 1996; to be published in the Proceedings.Comment: LaTeX, 16 pages, references adde

W-algebras from symplectomorphisms

It is shown how $W$-algebras emerge from very peculiar canonical transformations with respect to the canonical symplectic structure on a compact Riemann surface. The action of smooth diffeomorphisms of the cotangent bundle on suitable generating functions is written in the BRS framework while a $W$-symmetry is exhibited. Subsequently, the complex structure of the symmetry spaces is studied and the related BRS properties are discussed. The specific example of the so-called $W_3$-algebra is treated in relation to some other different approaches.Comment: LaTex, 25 pages, no figures, to appear in Journ. Math. Phy

Yangians, finite W-algebras and the Non Linear Schrodinger hierarchy

We show an algebra morphism between Yangians and some finite W-algebras. This correspondence is nicely illustrated in the framework of the Non Linear Schrodinger hierarchy. For such a purpose, we give an explicit realization of the Yangian generators in terms of deformed oscillators.Comment: LaTeX2e, 10 pages, Talk presented by E. Ragoucy at ACTP-Nankai Symposium on Yang-Baxter systems, non linear models and their applications, Seoul (Korea) October 20-23, 199

Problem-solving, resource utilization, and community involvement in a black and a white community

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44084/1/10464_2004_Article_BF00896061.pd

Parents' Perspectives on the School Experiences of Children with Cancer

Interviews with 59 parents of school age children with cancer indicate problems children encountered in returning to school: missing significant amounts of school due to illness and treatments, teasing by classmates and peers, and strained relations with teachers. Most parents report that despite missing much school their child was caught up with schoolwork, suggesting that academic difficulties are not paramount. Most parents also report receiving substantial help from sympathetic and competent educators. However, parents also indicate that some teachers were insensitive to their child's condition, while others were overprotective, suggesting the need for a delicate balance in defining appropriate teacher behavior. A responsive yet normalizing school environment can be facilitated by vigorous and proactive partnerships among the medical staff, family, and school system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68682/2/10.1177_027112148600500405.pd

A monolithic 20GHz integrated extended cavity mode-locked quantum well ring laser at 1.58µm fabricated in the JEPPIX platform

We report on a passively modelocked InP/InGaAsP quantum well semiconductor ring laser which operates at 20GHz repetition rate and at 1.58µm output wavelength. A number of devices with varying relative positions of the absorbers and amplifiers have been realized using active-passive integration technology in the JEPPIX fabrication platform. The 4mm-long laser ring cavity incorporates a 750µm-long optical amplifier section, a separate 40µm-long saturable absorber section, passive waveguide sections and a passive MMI-type 50% output coupler. We investigate operation regimes of the laser and explore conditions for single mode lasing and mode-locked operation

Calcification response of a key phytoplankton family to millennial-scale environmental change

Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO2 concentrations ([CO2(aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO2(aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments

The Social and Cultural Context of Coping with Sickle Cell Disease: I. A Review of Biomedical and Psychosocial Issues

Sickle cell disease (SCD) is widely conceived in the United States as a group of blood disorders that principally affect African Americans. Although pain is its principal feature, strokes, lung problems, sepsis, anxiety, depression, impaired social functioning, and maladjustment at work are frequent concomitants. This article selectively reviews biomedical and psychosocial aspects of SCD related to pain assessment, medical treatment, genetic counseling, education, and employment. The strongest support exists for claims of social deficits among adolescents and depression and work-related problems among adults. The social context of SCD, including issues related to socioeconomic status (SES), urbanicity, ethnicity, cultural values, and racial stigmatization, are important to include in empirical assessments and theoretical analyses of the effects of SCD on children and their families. The adverse psychosocial functioning often described as an effect of SCD might indeed be a consequence of these factors acting alone or in concert with the strains of SCD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67048/2/10.1177_0095798499025003002.pd

Polynomial super-gl(n) algebras

We introduce a class of finite dimensional nonlinear superalgebras $L = L_{\bar{0}} + L_{\bar{1}}$ providing gradings of $L_{\bar{0}} = gl(n) \simeq sl(n) + gl(1)$. Odd generators close by anticommutation on polynomials (of degree $>1$) in the $gl(n)$ generators. Specifically, we investigate `type I' super-$gl(n)$ algebras, having odd generators transforming in a single irreducible representation of $gl(n)$ together with its contragredient. Admissible structure constants are discussed in terms of available $gl(n)$ couplings, and various special cases and candidate superalgebras are identified and exemplified via concrete oscillator constructions. For the case of the $n$-dimensional defining representation, with odd generators $Q_{a}, \bar{Q}{}^{b}$, and even generators ${E^{a}}_{b}$, $a,b = 1,...,n$, a three parameter family of quadratic super-$gl(n)$ algebras (deformations of $sl(n/1)$) is defined. In general, additional covariant Serre-type conditions are imposed, in order that the Jacobi identities be fulfilled. For these quadratic super-$gl(n)$ algebras, the construction of Kac modules, and conditions for atypicality, are briefly considered. Applications in quantum field theory, including Hamiltonian lattice QCD and space-time supersymmetry, are discussed.Comment: 31 pages, LaTeX, including minor corrections to equation (3) and reference [60