326 research outputs found
Gravitational backreaction of anti-D branes in the warped compactification
We derive a low-energy effective theory for gravity with anti-D branes, which
are essential to get de Sitter solutions in the type IIB string warped
compactification, by taking account of gravitational backreactions of anti-D
branes. In order to see the effects of the self-gravity of anti-D branes, a
simplified model is studied where a 5-dimensional anti-de Sitter ({\it AdS})
spacetime is realized by the bulk cosmological constant and the 5-form flux,
and anti-D branes are coupled to the 5-form field by Chern-Simon terms. The
{\it AdS} spacetime is truncated by introducing UV and IR cut-off branes like
the Randall-Sundrum model. We derive an effective theory for gravity on the UV
brane and reproduce the familiar result that the tensions of the anti-D branes
give potentials suppressed by the forth-power of the warp factor at the
location of the anti-D branes. However, in this simplified model, the potential
energy never inflates the UV brane, although the anti-D-branes are inflating.
The UV brane is dominated by dark radiation coming from the projection of the
5-dimensional Weyl tensor, unless the moduli fields for the anti-D branes are
stabilized. We comment on the possibility of avoiding this problem in a
realistic string theory compactification.Comment: typos corrected, 11 pages, 3 figure
Experience with pharmacy academic programmes and career aspirations of pharmacy students and young pharmacists-an international cross-sectional study
OBJECTIVES: This study aims to assess pharmacy students and young pharmacistsâ motives to pursue pharmacy degrees, their overall experiences and satisfaction with their pharmacy academic programmes, and their career aspirations and future plans. METHODS: Between May-2019 and March-2020, a self-administered online questionnaire was distributed via the International Pharmaceutical Students Federation and the Young Pharmacists Group at the International Pharmaceutical Federation. The questionnaire targeted pharmacy students and young pharmacists worldwide. Data were analysed descriptively and inferentially. RESULTS: In total, 1,423 pharmacy students and young pharmacists participated in the study. Almost 70% (993) of respondents reported that pharmacy was their first choice subject for study. Intentions for studying pharmacy were driven by an interest in healthcare, wanting to help people as well as an interest in science. In general, more than 60% of the participants had a satisfactory education experience. However, dissatisfaction was more prevalent among current pharmacy students in comparison to young pharmacists. Out of 1,423 participants, 1,110 (78%) showed a continuing desire to practice pharmacy. Being female and resident of a middle-income country increased the likelihood of being more satisfied with the academic programme. Having pharmacy as the subject first-choice and being generally satisfied with the academic programmes were positively associated with participantsâ willingness to practice pharmacy. CONCLUSIONS: Our study revealed that the majority of this extensive sample had pharmacy as their profession of choice and wanted to continue to practice in the future. In addition most of the targeted population indicated satisfaction with their pharmacy academic programmes
Positional Coincidence of H2O Maser and a Plasma Obscuring Torus in Radio Galaxy NGC 1052
We present multi-frequency simultaneous VLBA observations at 15, 22 and 43
GHz towards the nucleus of the nearby radio galaxy NGC 1052. These three
continuum images reveal a double-sided jet structure, whose relative intensity
ratios imply that the jet axis is oriented close to the sky plane. The steeply
rising spectra at 15-43 GHz at the inner edges of the jets strongly suggest
that synchrotron emission is absorbed by foreground thermal plasma. We detected
H2O maser emission in the velocity range of 1550-1850 km/s, which is redshifted
by 50-350 km/s with respect to the systemic velocity of NGC 1052. The
redshifted maser gas appears projected against both sides of the jet, in the
same manner as the HI seen in absorption. The H2O maser gas are located where
the free-free absorption opacity is large. This probably imply that the masers
in NGC 1052 are associated with a circumnuclear torus or disk as in the nucleus
of NGC 4258. Such circumnuclear structure can be the sence of accreting onto
the central engine.Comment: 18 pages, 7 figures, accepted for publication in Ap
Gestational and Chronic Low-Dose PFOA Exposures and Mammary Gland Growth and Differentiation in Three Generations of CD-1 Mice
Background: Prenatal exposure to perfluorooctanoic acid (PFOA), a ubiquitous industrial surfactant, has been reported to delay mammary gland development in female mouse offspring (F1) and the treated lactating dam (P0) after gestational treatments at 3 and 5 mg PFOA/kg/day
Strong Coupling Quantum Gravity and Physics beyond the Planck Scale
We propose a renormalization prescription for the Wheeler-DeWitt equation of
(3+1)-dimensional Einstein gravity and also propose a strong coupling expansion
as an approximation scheme to probe quantum geometry at length scales much
smaller than the Planck length. We solve the Wheeler-DeWitt equation to the
second order in the expansion in a class of local solutions and discuss
problems arising in our approach.Comment: 27 pages, LaTeX file. To be published in Phys. Rev.
Comparison of polyfluoroalkyl compound concentrations in maternal serum and amniotic fluid: A pilot study
The extent to which polyfluoroalkyl compounds (PFCs) are detectable in amniotic fluid is unknown. Using paired samples from 28 women, we compared the concentration of 8 PFCs measured in serum, the standard matrix for assessing human exposure, amniotic fluid from routine amniocentesis, and urine. Perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) were detected in all maternal serum samples. The number of amniotic fluid samples with detectable concentrations differed by PFC (PFOA n=24; PFNA n=10; PFOS n=9; PFHxS n=4). The correlation coefficient between maternal serum and amniotic PFC levels varied considerably by PFC (PFOA Ï=0.64, p<0.001; PFNA Ï=0.05, p=0.9; PFOS Ï=0.76, p=0.01; PFHxS Ï=0.80, p=0.2). Using linear regression, PFOA appeared to be commonly detected in amniotic fluid if the serum concentration exceeded approximately 1.5 ng/mL whereas PFOS was rarely detected in amniotic fluid until the serum concentration was about 5.5 ng/mL. No PFCs were detected in urine
Polyfluoroalkyl Compounds in Texas Children from Birth through 12 Years of Age
Background: For > 50 years, polyfluoroalkyl compounds (PFCs) have been used worldwide, mainly as surfactants and emulsifiers, and human exposure to some PFCs is widespread
Upregulation of P2Y2 receptors by retinoids in normal human epidermal keratinocytes
Retinoids, vitamin A derivatives, are important regulators of the growth and differentiation of skin cells. Although retinoids are therapeutically used for several skin ailments, little is known about their effects on P2 receptors, known to be involved in various functions in the skin. DNA array analysis showed that treatment of normal human epidermal keratinocytes (NHEKs) with all-trans-retinoic acid (ATRA), an agonist to RAR (retinoic acid receptor), enhanced the expression of mRNA for the P2Y2 receptor, a metabotropic P2 receptor that is known to be involved in the proliferation of the epidermis. The expression of other P2 receptors in NHEKs was not affected by ATRA. ATRA increased the mRNA for the P2Y2 receptor in a concentration-dependent fashion (1Â nM to 1Â ÎŒM). Am80, a synthesized agonist to RAR, showed a similar enhancement, whereas 9-cis-retinoic acid (9-cisRA), an agonist to RXR (retinoid X receptor), enhanced P2Y2 gene expression to a lesser extent. Ca2+ imaging analysis showed that ATRA also increased the function of P2Y2 receptors in NHEKs. Retinoids are known to enhance the turnover of the epidermis by increasing both proliferation and terminal differentiation. The DNA microarray analysis also revealed that ATRA upregulates various genes involved in the differentiation of NHEKs. Our present results suggest that retinoids, at least in part, exert their proliferative effects by upregulating P2Y2 receptors in NHEKs. This effect of retinoids may be closely related to their therapeutic effect against various ailments or aging events in skins such as over-keratinization, pigmentation and re-modeling
Two-year efficacy and safety of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA)
Risdiplam is an oral, survival of motor neuron 2 (SMN2) pre-mRNA splicing modifier approved for the treatment of spinal muscular atrophy (SMA). SUNFISH (NCT02908685) Part 2, a Phase 3, randomized, double-blind, placebo-controlled study, investigated the efficacy and safety of risdiplam in type 2 and nonâambulant type 3 SMA. The primary endpoint was met: a significantly greater change from baseline in 32-item Motor Function Measure (MFM32) total score was observed with risdiplam compared with placebo at month 12. After 12 months, all participants received risdiplam while preserving initial treatment blinding. We report 24-month efficacy and safety results in this population. Month 24 exploratory endpoints included change from baseline in MFM32 and safety. MFMâderived results were compared with an external comparator. At month 24 of risdiplam treatment, 32% of patients demonstrated improvement (a change ofââ„â3) from baseline in MFM32 total score; 58% showed stabilization (a change ofââ„â0). Compared with an external comparator, a treatment difference of 3.12 (95% confidence interval [CI] 1.67-4.57) in favor of risdiplam was observed in MFM-derived scores. Overall, gains in motor function at month 12 were maintained or improved upon at month 24. In patients initially receiving placebo, MFM32 remained stable compared with baseline (0.31 [95% CI - 0.65 to 1.28]) after 12 months of risdiplam; 16% of patients improved their score and 59% exhibited stabilization. The safety profile after 24 months was consistent with that observed after 12 months. Risdiplam over 24 months resulted in further improvement or stabilization in motor function, confirming the benefit of longer-term treatment
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