Pi Alpha Research Articles

D = 5 rotating black holes in Einstein-Gauss-Bonnet gravity: mass and angular momentum in extremality

We consider perturbative solutions in Einstein gravity with higher-derivative extensions and address some subtle issues of taking extremal limit. As a concrete new result, we construct the perturbative rotating black hole in five dimensions with equal angular momenta J and general mass M in Einstein-Gauss-Bonnet gravity, up to and including the linear order of the standard Gauss-Bonnet coupling constant α. We obtain the near horizon structure of the near extremal solution, with the blackening factor of the order α. In the extremal limit, the mass-angular momentum relation reduces to M=frac{3}{2}{pi}^{frac{1}{3}}{J}^{frac{2}{3}}+pi alpha . The positive sign of the α-correction implies that the centrifugal repulsion associated with rotations becomes weaker than the gravitational attraction under the unitary requirement for the Gauss-Bonnet term.

Heavy-Tailed Random Walks on Complexes of Half-Lines

We study a random walk on a complex of finitely many half-lines joined at a common origin; jumps are heavy-tailed and of two types, either one-sided (towards the origin) or two-sided (symmetric). Transmission between half-lines via the origin is governed by an irreducible Markov transition matrix, with associated stationary distribution mu _k. If chi _k is 1 for one-sided half-lines k and 1 / 2 for two-sided half-lines, and alpha _k is the tail exponent of the jumps on half-line k, we show that the recurrence classification for the case where all alpha _k chi _k in (0,1) is determined by the sign of sum _k mu _k cot ( chi _k pi alpha _k ). In the case of two half-lines, the model fits naturally on {{mathbb {R}}} and is a version of the oscillating random walk of Kemperman. In that case, the cotangent criterion for recurrence becomes linear in alpha _1 and alpha _2; our general setting exhibits the essential nonlinearity in the cotangent criterion. For the general model, we also show existence and non-existence of polynomial moments of return times. Our moments results are sharp (and new) for several cases of the oscillating random walk; they are apparently even new for the case of a homogeneous random walk on {{mathbb {R}}} with symmetric increments of tail exponent alpha in (1,2).

Andrew DiRosa, MPA ‘02, Section Chief (Acting) of the Executive Intelligence Section of the Federal Bureau of Investigation

Mr. DiRosa obtained a Master’s in Public Administration (MPA), with a focus on managing federal agencies, from The George Washington University in 2002. While at GWU, Andy served as editor of Policy Perspectives, and was awarded the Leadership Award and was inducted into the Pi Alpha Alpha public administration honor society. Andy obtained a BA from Old Dominion University (Norfolk, VA) in English and Political Science in 1987. While at ODU he was elected to two terms on the student senate.Presently, Andy is the assistant section chief of the Executive Intelligence Section in the FBI’s Directorate of Intelligence at FBI Headquarters. In this capacity he helps oversee daily operation of 24-hour units that prepare the daily intelligence briefing materials for the FBI Director, US Attorney General, and other senior executives. Andy has also worked in the FBI’s Counterterrorism Division, as an intelligence analyst and supervisor, and in the FBI’s training division and office of public affairs, as managing editor of the FBI Law Enforcement Bulletin, a widely read criminal justice journal. He authored book reviews and journal articles, including features on street gangs and the impact of the Second World War on US law enforcement. While in the Counterterrorism Division Andy served in an international intelligence cell at NATO headquarters in Brussels. Mr. DiRosa has also represented the FBI at bilateral intelligence exchanges with Canada and the United Kingdom. (Views expressed are those of Mr. DiRosa and do not necessarily reflect the views of the FBI.)

Intermediate Theory: The Missing Link in Successful Student Scholarship

Since 1998, five Texas State University students’ capstone papers have won the Pi Alpha Alpha master’s student paper award. This success rate is attributed to students’ mastery of the the art of building and using intermediate theory or conceptual frameworks in the early stages of the Applied Research Project. This article introduces the notion of micro-conceptual frameworks and explains how students use them to connect all aspects of empirical inquiry—problem definition, purpose, literature review, methodology, data collection, and analysis. These conceptual frameworks act like maps that give coherence to the enterprise, and they are a critical missing link in successful student empirical research.

Inertial mass of the Abrikosov vortex.

We show that a large contribution to the inertial mass of the Abrikosov vortex comes from transversal displacements of the crystal lattice. The corresponding part of the mass per unit length of the vortex line is M(l)=(m(2)(e)c(2)/64 pi alpha(2)mu lambda(4)(L))ln((lambda(L)/xi), where m(e) is the bare electron mass, c is the speed of light, alpha=e(2)/Planck's over 2 pi c approximately 1/137 is the fine structure constant, mu is the shear modulus of the solid, lambda(L) is the London penetration length, and xi is the coherence length. In conventional superconductors, this mass can be comparable to or even greater than the vortex core mass computed by Suhl [Phys. Rev. Lett. 14, 226 (1965)]].

Parameter scaling in the decoherent quantum-classical transition for chaotic systems.

The quantum to classical transition for a system depends on many parameters, including a scale length for its action, variant Planck's over 2 pi, a measure of its coupling to the environment, D, and, for chaotic systems, the classical Lyapunov exponent, lambda. We propose measuring the proximity of quantum and classical evolutions as a multivariate function of (Planck's over 2 pi,lambda,D) and searching for transformations that collapse this hypersurface into a function of a composite parameter zeta= Planck's over 2 pi alpha)lambda beta D gamma. We report results for the quantum Cat Map and Duffing oscillator, showing accurate scaling behavior over a wide parameter range, indicating that this may be used to construct universality classes for this transition.

Analysis of two common alpha 1-antitrypsin deficiency alleles (PI*Z and PI*S) in subjects with periodontitis.

pi alpha 1-Antitrypsin deficiency is a genetically determined condition resulting in predisposition to certain inflammatory diseases due to a protease: antiprotease imbalance that is exacerbated by tobacco smoking. Limited evidence suggests that there may be a significant enrichment of mild alpha 1-antitrypsin deficiency phenotypes in subjects with chronic inflammatory periodontal disease. To examine the prevalence of two common alpha1-antitrypsin deficiency alleles (PI*Z and PI*S) in a UK population of subjects with periodontitis. The prevalence of PI*M, PI*S and PI*Z allele combinations was determined in 31 subjects with periodontitis and compared with 31 healthy control subjects matched for smoking status, ethnicity, age and gender. alpha 1-Antitrypsin genotyping was performed by multiplex real-time fluorescence polymerase chain reaction (PCR) using DNA extracted from whole blood. There was no difference in the proportion of any alpha 1-antitrypsin genotype found in the diseased and control populations. We did not find evidence to support an association between mutant PI* alleles and periodontitis in a small, controlled study. Larger studies will be required to clarify the relationship between alpha1-antitrypsin genotype and susceptibility to inflammatory periodontal disease.

Search for single leptoquark and squark production in electron-photon scattering at $\sqrt{s_{\rm ee}}=189$ GeV at LEP

A search for first generation scalar and vector leptoquarks (LQ) as well as for squarks in R-parity violating SUSY models has been performed using e+e- collisions collected with the OPAL detector at LEP at an e+e- centre-of-mass energy sqrt(s_ee) of 189 GeV. The data correspond to an integrated luminosity of about 160 pb-1. The dominant process for this search is e q -> LQ/squark -> e q, nu q, where a photon, which has been radiated by one of the beam electrons, serves as a source of quarks. The numbers of selected events found in the two decay channels are in agreement with the expectations from Standard Model processes. This result allows to set lower limits at the 95% confidence level on the mass of first generation scalar and vector leptoquarks, and of squarks in R-parity violating SUSY models. For Yukawa couplings lambda to fermions larger than sqrt{4 pi alpha_em}, the mass limits range from 121 GeV/c^2 to 175 GeV/c^2 (149 GeV/c^2 to 188 GeV/c^2) depending on the branching ratio beta of the scalar (vector) leptoquark state. Furthermore, limits are set on the Yukawa couplings lambda for leptoquarks and lambda'_1jk for squarks, and on beta as a function of the scalar leptoquark/squark mass.

Pi Alpha Xi—A Tradition of Excellence in Floriculture, Landscape Horticulture, and Ornamental Horticulture

Pi Alpha Xi, founded in 1923, is the national honor society for floriculture, landscape horticulture and ornamental horticulture. Since its founding, it has grown to 36 chapters at baccalaureate-granting institutions. Its mission is to promote scholarship, fellowship, professional leadership, and the enrichment of human life through plants.

Pi Alpha Alpha activities and effectiveness: results from a national survey of chapter advisors

Pi Alpha Alpha (PAA) is the national academic honor society for public administration. This study presents the results of a comprehensive survey of PAA Chapter advisors focusing on inductee characteristics, induction requirements, chapter activities, chapter officers, and suggestions for improving PAA chapter effectiveness. NASPAA sponsored the survey and provided relevant logistical support. The results indicate that PAA is meeting its major objectives, but several areas require attention including enhancing the activity mix, improving recruitment practices for chapter officers, and a dedicated means for disseminating information on chapter activities through a newsletter and a chapter directory.

Who Should Regulate Nature? An Examination of the Philosophies That Inform U.S. Wilderness Policy

No abstract available.

Spatial expression of alpha and beta tubulin genes in the late embryogenesis of the sea urchin Paracentrotus lividus.

In Paracentrotus lividus sea urchin embryos, at blastula stage, there is an abrupt increase in the abundance of alpha and beta tubulin transcripts in particular of the PI beta 1, PI beta 2 and PI alpha 2 forms. In order to assign specific functions to the various embryonic tubulin genes, we have used whole-mount in situ hybridization to determine spatial patterns of expression of five different alpha and beta tubulin embryonic genes. The PI beta 3 transcripts, as previously shown for PI alpha 2, start to localize in a few founder cells from which the neurogenic territory differentiates. The other four embryonic tubulin mRNAs (PI beta 1/2 and PI alpha 1/10), are localized in the ciliated band- and gut-territory. These territories originate by morphogenetic processes, which occur in late embryogenesis in the sea urchin and depend on cellular interactions. In particular, the interactions between the oral and aboral ectoderm specify the position of the ciliated band, whereas the invagination of the vegetal plate forms the gut territory. We suppose that the increase in alpha and beta tubulin transcripts could be functionally related to these two morphogenetic events. Our results show in fact that specific tubulin isotypes, or a mix of them, are expressed in and mark the ciliated band and the neighboring oral/aboral ectoderm cells of the ciliated band, in addition to the cells of the gut territory. The same localization of all these tubulin transcripts has been confirmed by whole-mount in situ hybridization experiments performed on embryos treated with agents able to induce deciliation or exogastrulation. Furthermore a putative correlation of PI beta 2 with cilium formation has been shown by the results obtained on deciliated embryos.

Localization properties of general pseudo-random dimer models

We study localization of states and transmittance of a one-dimensional lattice with incommensurate rapidly varying pseudo-random potential, when site energies are dimerized. The chosen model potential, V=V0 cos (2 pi alpha nnu ), alpha irrational, nu >1 and dimerization, is a peculiar generalization of the random-dimer binary model and allows careful control of the localization properties for varying degrees of disorder. We find that insertion of short-range order in the form of adjacent site energy dimerization, causes, in general, a strong increase of the localization lengths and the behaviour of the Lyapunov exponent as a function of the energy is similar to commensurate situations. In particular for nu >2, the binary alloy situation is reproduced and we confirm the presence of extended states near the two-site energies.

Fractal patterns of cracks during a dynamic process

In this paper the author has analysed a simple crack propagation lattice model which incorporates the bond-breaking probability Pi alpha ( delta i- delta c)eta , where delta i is the ith bond elongation and delta c is the bond-breaking threshold below which the bond is unbroken. A two-dimensional triangular lattice has been employed with nearest-neighbour central forces. The cases of a uniform small dilation strain and of a small shear in the horizontal direction with different exponents eta have been considered. He has found that the crack patterns during the breaking process are fractal structures with the fractal dimensions depending on the bond-breaking probability exponent eta in a limited large lattice.

Gonadotrophin concentrations and ovulation rates in Suffolk ewes actively or passively immunized against inhibin alpha

Mature Suffolk ewes were either actively or passively immunized against the synthetic fragment of porcine inhibin alpha, pI alpha(1-30), to determine the effects on gonadotrophin secretion and ovulation rate. Thirteen control ewes were immunized against human serum albumin, 12 ewes were actively immunized against pI alpha(1-30) and 36 ewes were passively immunized with pI alpha(1-30) antiserum. Blood samples were collected at 4-h intervals for 72 h from oestrus-synchronized ewes following the withdrawal of the progestagen pessaries. Mean gonadotrophin concentrations measured during the oestrous cycle of control ewes, ewes actively immunized against pI alpha(1-30) and ewes passively immunized against pI alpha(1-30) were similar, but their secretory profiles differed. Serum concentrations of follicle-stimulating hormone (FSH) were highest in ewes which had received antiserum at the time of pessary withdrawal; FSH concentrations did not decrease during the follicular phase of the oestrous cycle in ewes given antiserum 24 h after pessary withdrawal. Subtle but significant increments in serum FSH concentrations were observed in all passively immunized ewes in which sampling commenced at the time of treatment. The amplitude of the preovulatory luteinizing hormone (LH) peak, but not of the FSH peak, and the postovulatory secondary rise in FSH were lower (P less than 0.05) in actively immunized ewes than in control ewes. The mean (+/- s.e.) ovulation rate for actively immunized ewes (6.6 +/- 1.0) was 3 times higher (P less than 0.05) than that for control ewes (2.0 +/- 0.2), but was unaffected by passive immunization (range, 1.8-2.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Pituitary and testicular responses of beef bulls to active immunization against inhibin alpha.

Prepubertal crossbred beef bulls served as controls or were actively immunized against the N-terminal, 30-amino acid synthetic fragment of porcine inhibin alpha, pI alpha (1-30). Antibody titers were detected in sera (greater than 40% B/BO in sera diluted 1,000-fold) but not in rete testis fluid of 390-d-old bulls. Serum FSH and inhibin remained static during a 5-h intensive bleed; inhibin was not acutely affected by a 15-fold LH rise and a threefold FSH rise induced by exogenous GnRH. Serum FSH, but not LH or testosterone, was consistently elevated (P less than .05) in immunized bulls compared with control bulls. Neither pituitary weight, pituitary gonadotropin content nor pituitary FSH/LH ratios were affected (P greater than .10) by pI alpha(1-30) active immunization. Testicular sperm density was greater (60 x 10(6) vs 45 x 10(6) sperm/g testis; P less than .10) in immunized bulls, but testes weight, epididymides weight and total daily sperm production remained unchanged. These results suggest that inhibin is important for regulation of FSH secretion and testicular function. Immunization with suitable inhibin vaccines may improve bull fertility.

Inhibin: studies of stored and secreted forms by biosynthetic labeling and immunodetection in cultured rat granulosa cells.

The biosynthesis of inhibin in rat granulosa cells was studied by biosynthetic labeling, immunoblotting, and immunocytochemical techniques. Granulosa cells from immature hypophysectomized estrogen-treated rats were cultured in the presence of [35S]cysteine. Both conditioned media and cell extracts were subjected to immunoprecipitation with an antibody directed against the N-terminal 26 amino acids of the alpha-chain of porcine inhibin (pI alpha 1-26), followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography. Treatment with FSH (100 ng/ml) and delta 4-androstenedione (10(-7) M) increased the secretion of 35S-labeled inhibin immunoreactivity by 2.6-fold over that in control cultures treated with androstenedione alone. The radiolabeled inhibin had mol wt (Mr) values of 45,000 and 30,000. Upon reduction, the 45,000 Mr polypeptide remained (with increased apparent Mr of 49,000), but the 30,000 Mr species disappeared with the concomitant appearance of two bands with 18,000 and 11,000 Mr. Competition studies with pI alpha 1-26 confirmed that these polypeptides were all related to inhibin. Furthermore, immunoblotting with an antibody directed against the porcine inhibin beta-A chain (pI beta A81-113) indicated that the 11,000 Mr peptide was the inhibin beta-A chain. Extracts of cells treated with FSH contained only a high Mr alpha-related species (Mr, 41,000 nonreduced; 49,200 reduced). The inhibin alpha antibody was also used to immunocytochemically stain cultured granulosa cells. Cells that had been treated with FSH or the adenyl cyclase activator forskolin (3 x 10(-5) M), but not untreated cells, exhibited positive staining. These results indicate that granulosa cells synthesize and store inhibin alpha-chain precursor with 49,000 Mr. Although some of the high Mr alpha-form was secreted, the majority of the alpha-subunit was processed to the 18,000 Mr form and dimerized with the 11,000 Mr beta-chain to form the mature inhibin dimer immediately before secretion. The cultured granulosa cells may provide a model for future studies on the hormonal regulation of inhibin alpha- and beta-gene expression as well as subunit dimerization and secretion.

Inhibin production by primary Sertoli cell-enriched cultures: regulation by follicle-stimulating hormone, androgens, and epidermal growth factor.

Inhibin levels in the serum-free media of primary Sertoli cell-enriched (SCE) cultures were studied as a function of time and hormonal treatment. SCE cultures were established from 20-day-old rats and maintained in SF media supplemented with insulin, transferrin, epidermal growth factor (EGF), and bacitracin. Radioimmunoassayable inhibin was measured using an antibody directed against a synthetic porcine inhibin-alpha (pI alpha) and measured using this same synthetic peptide as well as a highly purified ovine inhibin standard. Results of these determinations are expressed in terms of a synthetic peptide as femtomoles of pI alpha-(1-26)-G-Y-per ml/10(6) cells. Inhibin levels (+/- SEM) that accumulated at this rate in media from control cultures were 184.9 +/- 6.1 and 167.4 +/- 5.2 on days 0-4 and 4-8, respectively. When FSH (oFSH 17; 1-1000 ng/ml) was added, a dose-dependent increase in inhibin levels was significant at all time points beyond the initial 24 h. The simultaneous addition of 2 x 10(-7) M testosterone (T) with low doses of FSH addition of 2 x 10(-7) m testosterone (T) with low doses of FSH suppressed the inhibin response to FSH, but when T was combined with 300 ng/ml FSH, there was no effect of T on inhibin levels compared to FSH alone, regardless of time in culture. In spite of the modest effect of T, androstenedione (A; 2 x 10(-13) to x 10(-5) M) produced a dose-dependent suppression of inhibin levels. This inhibition was also observed at all doses of FSH. The action of A was not due to its conversion to estrogens, as 17 beta-estradiol had no effect on inhibin production by SCE cultures in either the presence or absence of FSH. The effect of EGF, a component of the basal serum-free medium, was next examined; it produced a 1.5-fold higher level of inhibin (188.7 +/- 9.5) compared to cultures without EGF (135.6 +/- 5.0). When SCE cultures were plated with FSH plus EGF, the stimulation of inhibin levels was additive. We conclude that in Sertoli cell cultures established from immature rats (1) the accumulation of inhibin in medium declines from 90 fmol/10(6) cells.day (initial 24 h) to 40-50 fmol/10(6) cells.day (over the first 48 h) and continues to accumulate in the medium for 8 days of culture; (2) FSH regulates the production of inhibin by Sertoli cells; the best dose response is observed over a 3-day period.(ABSTRACT TRUNCATED AT 400 WORDS)

Deglycosylation of alpha 1-proteinase inhibitor by endo-beta-N-acetylglucosaminidase F.

The glycosidase endo-beta-N-acetylglucosaminidase F (endo F) from Flavobacterium meningosepticum was used for the deglycosylation of rat alpha 1-proteinase inhibitor (alpha 1 PI). alpha 1 PI containing three oligosaccharide side chains of the complex type was isolated from rat serum or from the medium of rat hepatocyte primary cultures. High-mannose-type alpha 1 PI or hybrid-type alpha 1 PI was isolated from the media of hepatocytes treated with 1-deoxymannojirimycin or swainsonine, respectively. The susceptibility of complex-type alpha 1 PI to endo F was studied in the presence of various detergents. 3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate and octyl glucopyranoside turned out to be most effective. In the absence of detergents, digestion of alpha 1 PI with high concentrations of endo F and/or long times of incubation led to the formation of alpha 1 PI with one and two oligosaccharide side chains. In the presence of 0.5% octyl glucopyranoside, the major cleavage products were unglycosylated alpha 1 PI and alpha 1 PI carrying one carbohydrate side chain. In contrast to the complex-type alpha 1 PI, the high-mannose type can be totally deglycosylated by endo F even in the absence of detergents. The susceptibility of the hybrid-type alpha 1 PI to endo F is between that of the complex and the high-mannose types.

PI (?1-antitrypsin) subtypes: Frequency of PI*M4 in several populations

Sera from different populations (Dutch, Northern and Southern Italians and Spaniards) were screened for PI (alpha 1-antitrypsin) types and subtypes. A polyacrylamide isoelectric focusing method was applied, which consisted of the combined use of an ultra-thin highly cross-linked gel, restricted pH range carrier ampholytes and a separator. This technique enabled easy typing and subtyping of all known PI phenotypes including PI*M subtypes. The frequency of the new PI*M4 allele was lowest of all PI*M alleles (0.0476 in The Netherlands, 0.0371 in Northern Italy, 0.0308 in Southern Italy and 0.0146 in Spain).