721 research outputs found
Lepton Flavour Violation in Unparticle Physics
Recently H. Georgi has introduced an unparticle \unpart in order to
describe the low energy physics of a nontrivial scale invariant sector of an
effective theory. In this work we have explored the phenomenology of an
unparticle using the lepton flavour violating decay , and found that the branching ratio of this decay is strongly dependent
on the scaling dimension.Comment: 7 pages, 3 figures; typographical errors corrected and references
added in version
Catalytic conversion of methanol to larger organic molecules over crystalline forsterite: laboratory study and astrophysical implications
Laboratory catalytic reactions of methanol over heated crystalline silicates (forsterite) lead to the formation of gas-phase olefinic and polycyclic aromatic hydrocarbon (PAH) molecules, and are of potential importance in astrophysical environments including hot molecular cores, protoplanetary disks and shocks. In our experiments the methanol reagent, together with intermediate and product gas-phase molecular species were detected using time-of-flight mass-spectrometry (TOF-MS). A solid deposited on the crystalline forsterite surface was examined subsequently using high-resolution transmission electron microscopy and thermal gravimetric techniques and found to comprise amorphous and graphitic carbon. The chemical players in this work – gas-phase methanol, crystalline silicates and PAHs, have been identified spectroscopically in a range of astrophysical environments including young and evolved stars, protoplanetary disks, comets, captured dust particles and meteorites. It is envisaged that reactions on bare dust grains as studied here both experimentally and theoretically through DFT calculations, can have implications for chemical transformations and conversions, in forming PAH molecules and potentially in the synthesis of prebiotic molecules
Diminished Virulence Of A Sar-lagr- Mutant Of Staphylococcus Aureus In The Rabbit Model Of Endocarditis
Microbial pathogenicity in Staphylococcus aureus is a complex process involving a number of virulence genes that are regulated by global regulatory systems including sar and agr. To evaluate the roles of these two loci in virulence, we constructed sar-lagr- mutants of strains RN6390 and RN450 and compared their phenotypic profiles to the corresponding single sar- and agr- mutants and parents. The secretion of all hemolysins was absent in the sar-lagr- mutants while residual β-hemolysin activity remained in single agr- mutants. The fibronectin binding capacity was significantly diminished in both single sar- mutants and double mutants when compared with parents while the reduction in fibrinogen binding capacity in the double mutants was modest. In the rabbit endocarditis model, there was a significant decrease in both infectivity rates and intravegetation bacterial densities with the double mutant as compared to the parent (RN6390) at 103-106 CFU inocula despite comparable levels of early bacteremia among various challenge groups. Notably, fewer bacteria in the double mutant group adhered to valvular vegetations at 30 min after challenge (106 CFU) than the parent group. These studies suggest that both the sar and agr loci are involved in initial valvular adherence, intravegetation persistence and multiplication of S. aureus in endocarditis.94518151822Waldvogel, F.A., Staphylococcus aureus (1985) Principles and Practice of Infectious Diseases, pp. 1097-1116. , G. L. Mandell, R. G. Douglas, Jr., and J. E. Bennett, editors. John Wiley & Sons, New YorkNeu, H.C., The crisis in antibiotic resistance (1992) Science (Wash. DC), 257, pp. 1064-1072Cohen, M.L., Epidemiology of drug resistance: Implications for a post-antibiotic era (1992) Science (Wash. DC), 257, pp. 1050-1055Easmon, C.S.F., Adlam, C., (1983) Staphylococci and Staphylococcal Infections, pp. 705-740. , Academic Press, New YorkCheung, A.L., Krishnan, M., Jaffe, E.A., Fischetti, V.A., Fibrinogen acts as a bridging molecule in the adherence of Staphylococcus aureus to cultured human endothelial cells (1991) J. Clin. Invest., 87, pp. 2236-2245Herrmann, M., Vaudaux, P.E., Pittet, D., Auckenthaler, R., Lew, P.D., Schumacher Perdreau, F., Peters, G., Waldvogel, F.A., Fibronectin, fibrinogen, and laminin act as mediators of adherence of clinical staphylococcal isolates to foreign material (1988) J. Infect. Dis., 158, pp. 693-701Kuypers, J.M., Proctor, R.A., Reduced adherence to traumatized rat heart valves by a low-fibronectin-binding mutant of Staphylococcus aureus (1989) Infect. Immun., 57, pp. 2306-2312DeRita, V.J., Mekalanos, J.J., Genetic regulation of bacterial virulence (1989) Annu. Rev. Genet., 23, pp. 455-482Kornblum, J., Kreiswirth, B., Projan, S.J., Ross, H., Novick, R.P., Agr: A polycistronic locus regulating exoprotein synthesis in Staphylococcus aureus (1990) Molecular Biology of the Staphylococci, pp. 373-402. , R. P. Novick, editor. VCH Publishers, New YorkNixon, B.T., Ronson, C.W., Ausubel, R.M., Two component regulatory systems responsive to environmental stimuli share strongly conserved domains with the nitrogen assimilation regulatory genes ntrB and btrC (1986) Proc. Natl. Acad. Sci. USA, 83, pp. 7850-7854Smeltzer, M.S., Hart, M.E., Iandolo, J.J., Phenotypic characterization of xpr, a global regulator of extracellular virulence factors in Staphylococcus aureus (1993) Infect. Immun., 61, pp. 919-925Cheung, A.L., Koomey, J.M., Butler, C.A., Projan, S.J., Fischetti, V.A., Regulation of exoprotein expression in Staphylococcus aureus by a locus (sar) distinct from agr (1992) Proc. Natl. Acad. Sci. USA, 89, pp. 6462-6466Cheung, A.L., Yeaman, M., Bayer, A.S., The role of the sar locus of Staphylococcus aureus in the induction of endocarditis in rabbits (1994) Infect. Immun., 62, pp. 1719-1725Vandenesch, F., Kornblum, J., Novick, R.P., A temporal signal, independent of agr, is required for hla but not spa transcription in Staphylococcus aureus (1991) J. Bacteriol., 173, pp. 6313-6320Cheung, A.L., Ying, P., Regulation of α and β hemolysins by the sar locus of Staphylococcus aureus (1994) J. Bacteriol., 176, pp. 580-585Rescei, P., Kreiswirth, B., O'Reilly, M., Schlievert, P., Gruss, A., Novick, R.P., Regulation of exoprotein gene expression in Staphylococcus aureus by agr (1986) Mol. & Gen. Genet., 202, pp. 58-61Fröman, G., Switalski, L., Speziale, P., Höök, M., Isolation and characterization of a fibronectin receptor from Staphylococcus aureus (1987) J. Biol. Chem., 262, pp. 6564-6571Lantz, M., Allen, R.D., Bounelis, P., Switalski, L.M., Höök, M., Bacteroides gingivalis and Bacteroides intermedius recognize different sites on human fibrinogen (1990) J. Bacteriol., 172, pp. 716-726Yeaman, M.R., Sullam, P.M., Dazin, P.F., Norman, D.C., Bayer, A.S., Characterization of Staphylococcus aureus-platelet binding by quantitative flow cytometric analysis (1992) J. Infect. Dis., 166, pp. 65-73Clawson, C.C., White, J.G., Herzberg, M.C., Platelet interaction with bacteria. VI. Contrasting the role of fibrinogen and fibronectin (1980) Am. J. Hematol., 9, pp. 43-53Yeaman, M.R., Norman, D.C., Bayer, A.S., Staphylococcus aureus susceptibility to thrombin-induced platelet microbicidal protein is independent of platelet adherence and aggregation in vitro (1992) Infect. Immun., 60, pp. 2368-2374Sullam, P.M., Payan, D.G., Dazin, P.F., Valone, F.H., Binding of viridans group streptococci to human platelets: A quantitative analysis (1990) Infect. Immun., 58, pp. 3802-3806Yeaman, M.R., Puentes, S.M., Norman, D.C., Bayer, A.S., Partial characterization and staphylocidal activity of thrombin-induced platelet microbicidal protein (1992) Infect. Immun., 60, pp. 1202-1209Kornblum, J., Projan, S.J., Moghazeh, S.L., Novick, R., A rapid method to quantitate non-labeled RNA species in bacterial cells (1988) Gene, 63, pp. 75-85Maniatis, T., Fritsch, E.F., Sambrook, J., (1989) Molecular Cloning, a Laboratory Manual, , Cold Spring Harbor Laboratory, Cold Spring Harbor, NYDurack, D.T., Beeson, P.B., Experimental bacterial endocarditis. I. Colonization of a sterile vegetation (1972) Br. J. Exp. Pathol., 53, pp. 44-49Scheld, W.M., Valone, J.A., Sande, M.A., Bacterial adherence in the pathogenesis of endocarditis. Interaction of bacterial dextran, platelets and fibrin (1978) J. Clin. Invest., 61, pp. 1394-1404Herzberg, M.C., Gong, K., McMarlane, G.D., Phenotypic characterization of Streptococcus sanguis virulence factors associated with bacterial endocarditis (1990) Infect. Immun., 58, pp. 515-522Cheung, A.L., Fischetti, V.A., The role of fibrinogen in staphylococcal adherence to catheters in vitro (1990) J. Infect. Dis., 161, pp. 1177-1186Herrmann, M., Vaudaux, P.E., Pittet, D., Auckenthaler, R., Lew, P.D., Schumacher Perdreau, F., Peters, G., Waldvogel, F.A., Fibronectin, fibrinogen, and laminin act as mediators of adherence of clinical staphylococcal isolates to foreign material (1988) J. Infect. Dis., 158, pp. 693-701Cheung, A.L., Projan, S.J., Cloning and sequencing of sarA: A gene required for the expression of agr (1994) J. Bacteriol., 176, pp. 4168-4172Scheld, W.M., Strunk, R.W., Balian, G., Calderone, R.A., Microbial adhesion to fibronectin in vitro correlates with production of endocarditis in rabbits (1985) Proc. Soc. Exp. Biol. Med., 180, pp. 474-482Durack, D.T., Beeson, P.B., Pathogenesis of infective endocarditis (1980) Infective Endocarditis, pp. 1-53. , S. H. Rahimtoola, editor. Grune and Stratton, Inc., New YorkJaffe, E., Cell biology of endothelial cells (1987) Hum. Pathol., 18, pp. 234-239Lopes, J.D., Reis, M.D., Bretani, R.R., Presence of laminin receptors in Staphylococcus aureus (1985) Science (Wash. DC), 229, pp. 275-277Patti, J.M., Bremell, T., Krajewska-Paetrasik, D., Adelnour, A., Tarkowski, A., Ryden, C., Höök, M., The Staphylococcus aureus collagen adhesin is a virulence determinant in experimental septic arthritis Infect. Immun., 62, pp. 152-161Herrmann, M., Suchard, S.J., Boxer, L.A., Waldvogel, F.A., Lew, P.D., Thrombospondin binds to Staphylococcus aureus and promotes staphylococcal adhesion to surfaces (1991) Infect. Immun., 59, pp. 279-288Bhakdi, S., Muhly, M., Mannhardt, U., Hugo, F., Klapettek, K., Muller-Eckhardt, C., Roka, L., Staphylococcal α-toxin promotes blood coagulation via attack on human platelets (1988) J. Exp. Med., 168, pp. 527-542Suttorp, N., Hessz, T., Seeger, W., Wilke, A., Koob, R., Lutz, F., Drenckhahn, D., Bacterial exotoxins and endothelial permeability for water and albumin in vitro (1988) Am. J. Physiol., 255, pp. C368Novick, R.P., Genetic systems in staphylococci (1991) Methods Enzymol., 204, pp. 587-636O'Reilly, M., De Azavedo, J.C.S., Kennedy, S., Foster, T.J., Inactivation of the alpha-hemolysin of Staphylococcus aureus 8325-4 by site directed mutagenesis and studies on the expression of its haemolysins (1986) Microb. Pathog., 1, pp. 125-138Projan, S.J., Kornblum, J., Kreiswirth, B., Moghazeh, S., Eisner, W., Novick, R.P., The β hemolysin gene of Staphylococcus aureus (1989) Nucleic Acids Res., 17, p. 3305Camilli, A., Portnoy, D.A., Youngman, P., Insertional mutagenesis of Listeria monocytogenes with a novel Tn917 derivative that allows direct cloning of DNA flanking transposon insertions (1990) J. Bacteriol., 172, pp. 3738-3744Nesin, M., Svec, P., Lupski, J.R., Godson, G.N., Kreiswirth, B., Kornblum, J., Projan, S.J., Cloning and nucleotide sequencing of a chromosomally encoded tetracycline resistance determinant, tetA(M), from a pathogenic, methicillin resistant strain of Staphylococcus aureus (1990) Antimicrob. Agents Chemother., 34, pp. 2273-227
Torsion Constraints in the Randall--Sundrum Scenario
Torsion appears due to fermions coupled to gravity and leads to the strongest
particle physics bounds on flat extra dimensions. In this work, we consider
torsion constraints in the case of a warped extra dimension with brane and bulk
fermions. From current data we obtain a 3-sigma bound on the TeV--brane mass
scale scale \Lambda_\pi > 2.2 (10) TeV for the AdS curvature k=1 (0.01) in
(reduced) Planck units. If Dirac or light sterile neutrinos reside on the
brane, the bound increases to 17 (78) TeV.Comment: typos corrected, matches the Phys. Rev. D versio
Effects of low-dose oral micronised progesterone on sleep, psychological distress, and breast development in transgender individuals undergoing feminising hormone therapy: a prospective controlled study
Objective: The role of micronised progesterone in hormone regimens for transgender individuals undergoing feminising hormone therapy remains uncertain. We aimed to determine the effect of oral micronised progesterone on sleep quality, psychological distress, and breast development in transgender individuals undergoing feminising hormone therapy. Design: Prospective case–control study. Twenty-three transgender individuals on stable oestradiol treatment newly commencing 100 mg oral progesterone (n = 23) and controls continuing standard care (n = 19) were assessed over 3 months. Methods: Pittsburgh Sleep Quality Index (PSQI), Kessler psychological distress scale (K10), and Tanner stage to assess breast development were assessed at 0 and 3 months. Nonparametric analysis of covariance was used to compare difference s between groups. Results: Compared with controls over 3 months, there was no difference i n PSQI (P = 0.35), K10 (P = 0.64), or Tanner stage (P = 0.42). There was no significant difference in the proportion of individuals with clinically significant improvement in PSQI (25% vs 22%, P = 0.84). One individual had a significant deterioration in psychological distress that improved following the cessation of progesterone. Conclusions: Low-dose progesterone was not associated with changes in sleep quality, psychological distress, or breast development over 3 months follow-up, though there was significant inter-individual variability. Larger, placebo-controlled trials are required to further evaluate different doses of progesterone in feminising hormone therapy regimens.Brendan J Nolan, Aviva S Frydman, Shalem Y Leemaqz, Meg Carroll, Mathis Grossmann, Jeffrey D Zajac and Ada S Cheun
Short-Term Effects of Gender-Affirming Hormone Therapy on Dysphoria and Quality of Life in Transgender Individuals: A Prospective Controlled Study
Background: Gender affirming hormone therapy (GAHT), whilst considered the standard of care in clinical guidelines for the treatment of many transgender (trans) people is supported by low quality evidence. In this prospective longitudinal controlled study, we aimed to examine the effect of newly commencing GAHT on gender dysphoria and quality of life (QoL) over a 6 month period. Methods: Adult trans (including those with binary and/or non-binary identities) people newly commencing standard full-doses of masculinising (n = 42; 35 = trans masculine, 7 = non-binary) or feminising (n = 35; 33 = trans feminine, 2 = non-binary) GAHT and cisgender participants (n=53 male, n=50 female) were recruited to participate in this longitudinal prospective study. This analysis of gender dysphoria measured by the Gender Preoccupation and Stability Questionnaire and QoL measured by the RAND Short-Form 36 Health survey at baseline, 3 and 6 months after commencement of GAHT was a prespecified secondary outcome. Dysphoria and QoL over time in those starting GAHT compared to cisgender comparison group matched for their presumed sex at birth is reported as the mean difference (95% confidence interval) adjusted for age. Results: In trans people initiating masculinising GAHT, there was a decrease in gender dysphoria with adjusted mean difference -6.80 (-8.68, -4.91), p < 0.001, and a clinically significant improvement in emotional well-being [adjusted mean difference 7.48 (1.32, 13.64), p = 0.018] and social functioning [adjusted mean difference 12.50 (2.84, 22.15), p = 0.011] aspects of QoL over the first 6 months of treatment relative to the cisgender female comparison group. No significant differences were observed in other QoL domains. In trans people initiating feminising GAHT, there was a decrease in gender dysphoria [adjusted mean difference -4.22 (-6.21, -2.24), p < 0.001] but no differences in any aspects of QoL were observed. Conclusions: In the short-term, our findings support the benefit of initiating masculinising or feminising GAHT for gender dysphoria. Masculinising GAHT improves emotional wellbeing and social functioning within 6 months of treatment. Multidisciplinary input with speech pathology and surgery to support trans people seeking feminisation is likely needed. Further longitudinal studies controlled for other confounders (such as the presence of social supports) contributing to QoL are needed.Lucas Foster Skewis, Ingrid Bretherton, Shalem Y. Leemaqz, Jeffrey D. Zajac, and Ada S. Cheun
Strong duality in conic linear programming: facial reduction and extended duals
The facial reduction algorithm of Borwein and Wolkowicz and the extended dual
of Ramana provide a strong dual for the conic linear program in the absence of any constraint qualification. The facial
reduction algorithm solves a sequence of auxiliary optimization problems to
obtain such a dual. Ramana's dual is applicable when (P) is a semidefinite
program (SDP) and is an explicit SDP itself. Ramana, Tuncel, and Wolkowicz
showed that these approaches are closely related; in particular, they proved
the correctness of Ramana's dual using certificates from a facial reduction
algorithm.
Here we give a clear and self-contained exposition of facial reduction, of
extended duals, and generalize Ramana's dual:
-- we state a simple facial reduction algorithm and prove its correctness;
and
-- building on this algorithm we construct a family of extended duals when
is a {\em nice} cone. This class of cones includes the semidefinite cone
and other important cones.Comment: A previous version of this paper appeared as "A simple derivation of
a facial reduction algorithm and extended dual systems", technical report,
Columbia University, 2000, available from
http://www.unc.edu/~pataki/papers/fr.pdf Jonfest, a conference in honor of
Jonathan Borwein's 60th birthday, 201
Brane Decay of a (4+n)-Dimensional Rotating Black Hole. II: spin-1 particles
The present works complements and expands a previous one, focused on the
emission of scalar fields by a (4+n)-dimensional rotating black hole on the
brane, by studying the emission of gauge fields on the brane from a similar
black hole. A comprehensive analysis of the particle, energy and angular
momentum emission rates is undertaken, for arbitrary angular momentum of the
black hole and dimensionality of spacetime. Our analysis reveals the existence
of a number of distinct features associated with the emission of spin-1 fields
from a rotating black hole on the brane, such as the behaviour and magnitude of
the different emission rates, the angular distribution of particles and energy,
the relative enhancement compared to the scalar fields, and the magnitude of
the superradiance effect. Apart from their theoretical interest, these features
can comprise clear signatures of the emission of Hawking radiation from a
brane-world black hole during its spin-down phase upon successful detection of
this effect during an experiment.Comment: 35 pages, 19 figures, Latex fil
Iridium-catalyzed C–H borylation of pyridines
The iridium-catalysed C–H borylation is a valuable and attractive method for the preparation of aryl and heteroaryl boronates. However, application of this methodology for the preparation of pyridyl and related azinyl boronates can be challenged by low reactivity and propensity for rapid protodeborylation, particularly for a boronate ester ortho to the azinyl nitrogen. Competition experiments have revealed that the low reactivity is due to inhibition of the active catalyst through coordination of the azinyl nitrogen lone pair at the vacant site on the iridium. This effect can be overcome through the incorporation of a substituent at C-2. Moreover, when this is sufficiently electron-withdrawing protodeborylation is sufficiently slowed to permit isolation and purification of the C-6 boronate ester. Following functionalization, reduction of the directing C-2 substituent provides the product arising from formal ortho borylation of an unhindered pyridine ring
Temperature enhanced persistent currents and " periodicity"
We predict a non-monotonous temperature dependence of the persistent currents
in a ballistic ring coupled strongly to a stub in the grand canonical as well
as in the canonical case. We also show that such a non-monotonous temperature
dependence can naturally lead to a periodicity of the persistent
currents, where =h/e. There is a crossover temperature , below
which persistent currents increase in amplitude with temperature while they
decrease above this temperature. This is in contrast to persistent currents in
rings being monotonously affected by temperature. is parameter-dependent
but of the order of , where is the level spacing
of the isolated ring. For the grand-canonical case is half of that for
the canonical case.Comment: some typos correcte
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