20,505 research outputs found
One-loop Corrections to the S Parameter in the Four-site Model
We compute the leading chiral-logarithmic corrections to the S parameter in
the four-site Higgsless model. In addition to the usual electroweak gauge
bosons of the Standard Model, this model contains two sets of heavy charged and
neutral gauge bosons. In the continuum limit, the latter gauge bosons can be
identified with the first excited Kaluza-Klein states of the W^\pm and Z bosons
of a warped extra-dimensional model with an SU(2)_L \times SU(2)_R \times
U(1)_X bulk gauge symmetry. We consider delocalized fermions and show that the
delocalization parameter must be considerably tuned from its tree-level ideal
value in order to reconcile experimental constraints with the one-loop results.
Hence, the delocalization of fermions does not solve the problem of large
contributions to the S parameter in this class of theories and significant
contributions to S can potentially occur at one-loop.Comment: 28 pages, 7 figure
Higgs Triplets, Decoupling, and Precision Measurements
Electroweak precision data has been extensively used to constrain models
containing physics beyond that of the Standard Model. When the model contains
Higgs scalars in representations other than SU(2) singlets or doublets, and
hence rho not equal to one at tree level, a correct renormalization scheme
requires more inputs than the three needed for the Standard Model. We discuss
the connection between the renormalization of models with Higgs triplets and
the decoupling properties of the models as the mass scale for the scalar
triplet field becomes much larger than the electroweak scale. The requirements
of perturbativity of the couplings and agreement with electroweak data place
strong restrictions on models with Higgs triplets. Our results have important
implications for Little Higgs type models and other models with rho not equal
to one at tree level.Comment: 23 page
Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 44
Dawson, C.E. 1981. Review of the Indo-Pacific Pipefish Genus Doryrhamphus Kaup (Pisces: Syngnathidae), with Descriptions of a New Species and a New Subspecies. Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology, No. 44, 27 pages, 17 figures. Doryrhamphus, a genus of trunk-pouch pipefishes commonly associated with rock or coral habitats, is diagnosed and a key is provided to the five species and five subspecies recognized. The genus Dentirostrum Herald and Randall is synonymized with Doryrhamphus, treated species and subspecies are diagnosed and illustrated, distribution (based on material examined) is delineated and comprehensive synonymies are provided. The genus includes two species groups which, (in subadults and adults) differ in having either one or two spines on principal ridges of the posterior predorsal rings. Species of the single-spine group are distinguished by differences in meristic values and preserved coloration, as well as by the presence of one or two ventrolateral projections on the snout of males, or the absence thereof. Species of the two-spine group are distinguished by differences in meristic values and preserved coloration, as well as by the presence of either one or two spines on principal ridges of tail rings. The single-spine group includes the type-species, D. excisus (three subspecies), with one ventrolateral projection on snout in males, A japonicus with no projection on snout, and D. bicarinatus n. sp. with two projections on snout. Doryrhamphus e. excisus (a senior synonym of D. melanopleura), with modally 17-18 trunk rings ranges from eastern Africa and Persian Gulf to the west coast of the Americas. This pipefish, the most widely distributed syngnathid, exhibits some west-east clinal increase in counts of total rings and dorsal-fin rays. Doryrhamphus e. abbreviatus n. ssp. is a Red Sea endemic characterized by modally 16 trunk rings as well as by 26-28 total rings and 18-20 dorsal-fin rays. D. e. paulus (Revillagegido Is., Mexico) shares the modal count of 16 trunk rings, but has 30-32 total rings and 23-27 dorsal-fin rays. D. japonicus (19-20 trunk rings) is known only from the main islands of Japan, whereas D. bicarinatus (16 trunk rings) is known from Indian Ocean coasts of South Africa and Mozambique. The two-spine group includes D. negrosensis (2 subspecies) with 2 spines on ridges of tail rings in subadults and adults and A janssi (one spine on ridges of tail rings. A n. negrosensis (modally 15 trunk and 29 total rings) is known from Borneo to the Ryukyu Is. and southeastward to the New Hebrides, excluding Australia. D. n. malus (modally, 16 trunk and 31 total rings) is an Australian Great Barrier Reef endemic. D. janssi, with more tail rings than D. negrosensis (21-23 versus 13-16), is known from the eastern Indian Ocean (off NW Australia) and from the Gulf of Thailand and Philippines southeastward to New Guinea and NE Australia in the western Pacific Ocean. Planktonic young of A excisus and early juveniles of D. negrosensis are illustrated and briefly described.Rhodes University Libraries (Digitisation
Use of AlInN layers in optical monitoring of growth of GaN-based structures on free-standing GaN substrates
When lattice matched to GaN, the AlInN ternary alloy has a refractive index ~7% lower than that of GaN. This characteristic can be exploited to perform in situ reflectometry during epitaxial growth of GaN-based multilayer structures on free-standing GaN substrates, by insertion of a suitable Al0.82In0.18N layer. The real-time information on growth rates and cumulative layer thicknesses thus obtainable is particularly valuable in the growth of optical resonant cavity structures. We illustrate this capability with reference to the growth of InGaN/GaN multiple quantum-well structures, including a doubly periodic structure with relatively thick GaN spacer layers between groups of wells. Al0.82In0.18N insertion layers can also assist in the fabrication of resonant cavity structures in postgrowth processing, for example, acting as sacrificial layers in a lift-off process exploiting etch selectivity between Al0.82In0.18N and GaN
The roots of "Western European societal evolution". A concept of Europe by JenĆ SzƱcs
JenĆ SzƱcs wrote his essay entitled Sketch on the three regions of Europe in the early 1980s in Hungary. During these years, a historically well-argued opinion emphasising a substantial difference between Central European and Eastern European societies was warmly received in various circles of the political opposition. In a wider European perspective SzƱcs used the old âliberty toposâ which claims that the history of Europe is no other than the fulfillment of liberty. In his Sketch, SzƱcs does not only concentrate on questions concerning the Middle Ages in Western Europe. Yet it is this stream of thought which brought a new perspective to explaining European history. His picture of the Middle Ages represents well that there is a way to integrate all typical Western motifs of post-war self-definition into a single theory. Mainly, the âliberty motifâ, as a sign of âEuropeanismâ â in the interpretation of BibĂłâs concept, Anglo-saxon Marxists and Weberâs social theory â, developed from medieval concepts of state and society and from an analysis of economic and social structures. SzƱcsâs historical aspect was a typical intellectual product of the 1980s: this was the time when a few Central European historians started to outline non-Marxist aspects of social theory and categories of modernisation theories, but concealing them with Marxist terminology
Enhancement and evaluation of Skylab photography for potential land use inventories, part 1
The author has identified the following significant results. Three sites were evaluated for land use inventory: Finger Lakes - Tompkins County, Lower Hudson Valley - Newburgh, and Suffolk County - Long Island. Special photo enhancement processes were developed to standardize the density range and contrast among S190A negatives. Enhanced black and white enlargements were converted to color by contact printing onto diazo film. A color prediction model related the density values on each spectral band for each category of land use to the spectral properties of the various diazo dyes. The S190A multispectral system proved to be almost as effective as the S190B high resolution camera for inventorying land use. Aggregate error for Level 1 averaged about 12% while Level 2 aggregate error averaged about 25%. The S190A system proved to be much superior to LANDSAT in inventorying land use, primarily because of increased resolution
Marked expansion of exocrine and endocrine pancreas with incretin therapy in humans with increased exocrine pancreas dysplasia and the potential for glucagon-producing neuroendocrine tumors.
Controversy exists regarding the potential regenerative influences of incretin therapy on pancreatic ÎČ-cells versus possible adverse pancreatic proliferative effects. Examination of pancreata from age-matched organ donors with type 2 diabetes mellitus (DM) treated by incretin therapy (n = 8) or other therapy (n = 12) and nondiabetic control subjects (n = 14) reveals an âŒ40% increased pancreatic mass in DM treated with incretin therapy, with both increased exocrine cell proliferation (P < 0.0001) and dysplasia (increased pancreatic intraepithelial neoplasia, P < 0.01). Pancreata in DM treated with incretin therapy were notable for α-cell hyperplasia and glucagon-expressing microadenomas (3 of 8) and a neuroendocrine tumor. ÎČ-Cell mass was reduced by âŒ60% in those with DM, yet a sixfold increase was observed in incretin-treated subjects, although DM persisted. Endocrine cells costaining for insulin and glucagon were increased in DM compared with non-DM control subjects (P < 0.05) and markedly further increased by incretin therapy (P < 0.05). In conclusion, incretin therapy in humans resulted in a marked expansion of the exocrine and endocrine pancreatic compartments, the former being accompanied by increased proliferation and dysplasia and the latter by α-cell hyperplasia with the potential for evolution into neuroendocrine tumors
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