410 research outputs found
Approximate Self-Assembly of the Sierpinski Triangle
The Tile Assembly Model is a Turing universal model that Winfree introduced
in order to study the nanoscale self-assembly of complex (typically aperiodic)
DNA crystals. Winfree exhibited a self-assembly that tiles the first quadrant
of the Cartesian plane with specially labeled tiles appearing at exactly the
positions of points in the Sierpinski triangle. More recently, Lathrop, Lutz,
and Summers proved that the Sierpinski triangle cannot self-assemble in the
"strict" sense in which tiles are not allowed to appear at positions outside
the target structure. Here we investigate the strict self-assembly of sets that
approximate the Sierpinski triangle. We show that every set that does strictly
self-assemble disagrees with the Sierpinski triangle on a set with fractal
dimension at least that of the Sierpinski triangle (roughly 1.585), and that no
subset of the Sierpinski triangle with fractal dimension greater than 1
strictly self-assembles. We show that our bounds are tight, even when
restricted to supersets of the Sierpinski triangle, by presenting a strict
self-assembly that adds communication fibers to the fractal structure without
disturbing it. To verify this strict self-assembly we develop a generalization
of the local determinism method of Soloveichik and Winfree
Chaos and flights in the atom-photon interaction in cavity QED
We study dynamics of the atom-photon interaction in cavity quantum
electrodynamics (QED), considering a cold two-level atom in a single-mode
high-finesse standing-wave cavity as a nonlinear Hamiltonian system with three
coupled degrees of freedom: translational, internal atomic, and the field. The
system proves to have different types of motion including L\'{e}vy flights and
chaotic walkings of an atom in a cavity. It is shown that the translational
motion, related to the atom recoils, is governed by an equation of a parametric
nonlinear pendulum with a frequency modulated by the Rabi oscillations. This
type of dynamics is chaotic with some width of the stochastic layer that is
estimated analytically. The width is fairly small for realistic values of the
control parameters, the normalized detuning and atomic recoil
frequency . It is demonstrated how the atom-photon dynamics with a
given value of depends on the values of and initial
conditions. Two types of L\'{e}vy flights, one corresponding to the ballistic
motion of the atom and another one corresponding to small oscillations in a
potential well, are found. These flights influence statistical properties of
the atom-photon interaction such as distribution of Poincar\'{e} recurrences
and moments of the atom position . The simulation shows different regimes of
motion, from slightly abnormal diffusion with at to a superdiffusion with at that
corresponds to a superballistic motion of the atom with an acceleration. The
obtained results can be used to find new ways to manipulate atoms, to cool and
trap them by adjusting the detuning .Comment: 16 pages, 7 figures. To be published in Phys. Rev.
Galaxy And Mass Assembly (GAMA): understanding the wavelength dependence of galaxy structure with bulge-disc decompositions
With a large sample of bright, low-redshift galaxies with optical–near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behaviour of single-Sersic structural measurements. We denote the variation in single-Sersic index with wavelength as N, likewise for effective radius we use R. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of N. The increase in Sersic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from radial variations in stellar population and/or dust reddening. Similarly, low values of R (< 1) are found to be ubiquitous, implying an element of universality in galaxy colour gradients. We also study how bulge and disc colour distributions vary with galaxy type. We find that, rather than all bulges being red and all discs being blue in absolute terms, both components become redder for galaxies with redder total colours. We even observe that bulges in bluer galaxies are typically bluer than discs in red galaxies, and that bulges and discs are closer in colour for fainter galaxies. Trends in total colour are therefore not solely due to the colour or flux dominance of the bulge or disc
Infections in Dupilumab Clinical Trials in Atopic Dermatitis : A Comprehensive Pooled Analysis
Background: Patients with moderate-to-severe atopic dermatitis (AD) have increased infection risk, including skin infections and systemic infections. Immunomodulators (e.g., anti-tumor necrosis factors, anti-interleukin [anti-IL]-23, anti-IL-17, Janus kinase inhibitors) increase risk of infections. Dupilumab (a monoclonal antibody blocking the shared receptor component for IL-4 and IL-13) is approved for inadequately controlled moderate-to-severe AD and for moderate-to-severe eosinophilic or oral corticosteroid-dependent asthma. Objective: The aim was to determine the impact of dupilumab on infection rates in patients with moderate-to-severe AD. Methods: This analysis pooled data from seven randomized, placebo-controlled dupilumab trials in adults with moderate-to-severe AD. Exposure-adjusted analyses assessed infection rates. Results: Of 2932 patients, 1091 received placebo, 1095 dupilumab 300 mg weekly, and 746 dupilumab 300 mg every 2 weeks. Treatment groups had similar infection rates overall per 100 patient-years (placebo, 155; dupilumab weekly, 150; dupilumab every 2 weeks, 156; dupilumab combined, 152), and similar non-skin infection rates. Serious/severe infections were reduced with dupilumab (risk ratio 0.43; p < 0.05), as were bacterial and other non-herpetic skin infections (risk ratio 0.44; p < 0.001). Although herpesviral infection rates overall were slightly higher with dupilumab than placebo, clinically important herpesviral infections (eczema herpeticum, herpes zoster) were less common with dupilumab (risk ratio 0.31; p < 0.01). Systemic anti-infective medication use was lower with dupilumab. Conclusions: Dupilumab is associated with reduced risk of serious/severe infections and non-herpetic skin infections and does not increase overall infection rates versus placebo in patients with moderate-to-severe AD. ClinicalTrials.gov Identifiers: NCT01548404, NCT02210780, NCT01859988, NCT02277743, NCT02277769, NCT02260986, and NCT02755649
Two Phase 3 Trials of Dupilumab versus Placebo in Atopic Dermatitis.
BACKGROUND
Dupilumab, a human monoclonal antibody against interleukin-4 receptor alpha, inhibits
signaling of interleukin-4 and interleukin-13, type 2 cytokines that may be important
drivers of atopic or allergic diseases such as atopic dermatitis.
METHODS
In two randomized, placebo-controlled, phase 3 trials of identical design (SOLO 1
and SOLO 2), we enrolled adults with moderate-to-severe atopic dermatitis whose
disease was inadequately controlled by topical treatment. Patients were randomly
assigned in a 1:1:1 ratio to receive, for 16 weeks, subcutaneous dupilumab (300 mg)
or placebo weekly or the same dose of dupilumab every other week alternating
with placebo. The primary outcome was the proportion of patients who had both
a score of 0 or 1 (clear or almost clear) on the Investigator’s Global Assessment
and a reduction of 2 points or more in that score from baseline at week 16.
RESULTS
We enrolled 671 patients in SOLO 1 and 708 in SOLO 2. In SOLO 1, the primary
outcome occurred in 85 patients (38%) who received dupilumab every other week and
in 83 (37%) who received dupilumab weekly, as compared with 23 (10%) who received
placebo (P<0.001 for both comparisons with placebo). The results were similar in
SOLO 2, with the primary outcome occurring in 84 patients (36%) who received dupilumab
every other week and in 87 (36%) who received dupilumab weekly, as compared
with 20 (8%) who received placebo (P<0.001 for both comparisons). In addition,
in the two trials, an improvement from baseline to week 16 of at least 75% on the
Eczema Area and Severity Index was reported in significantly more patients who received
each regimen of dupilumab than in patients who received placebo (P<0.001 for
all comparisons). Dupilumab was also associated with improvement in other clinical
end points, including reduction in pruritus and symptoms of anxiety or depression
and improvement in quality of life. Injection-site reactions and conjunctivitis were
more frequent in the dupilumab groups than in the placebo groups.
CONCLUSIONS
In two phase 3 trials of identical design involving patients with atopic dermatitis,
dupilumab improved the signs and symptoms of atopic dermatitis, including
pruritus, symptoms of anxiety and depression, and quality of life, as compared
with placebo. Trials of longer duration are needed to assess the long-term effectiveness
and safety of dupilumab. (Funded by Sanofi and Regeneron Pharmaceuticals;
SOLO 1 ClinicalTrials.gov number, NCT02277743; SOLO 2 ClinicalTrials
.gov number, NCT02277769.
Dupilumab significantly modulates pain and discomfort in patients with atopic dermatitis : a post hoc analysis of 5 randomized clinical trials
Background
Pain is a frequent symptom of atopic dermatitis (AD).
Objectives
The aims of the study were to evaluate the effects of dupilumab on pain/discomfort in AD and to determine whether pain correlates with other outcomes.
Methods
This was a post hoc analysis of 5 randomized, placebo-controlled clinical trials in which adults with chronic AD received placebo or dupilumab 300 mg every 2 weeks or once weekly with and without topical corticosteroids. Proportions of patients with no pain/discomfort on this dimension of the 5-dimension EuroQoL (EQ-5D) at week 16 (all trials) and week 52 (CHRONOS) were compared between placebo and dupilumab. Correlations were evaluated between pain/discomfort and signs and symptoms of AD.
Results
Among 2632 evaluated patients, 72.9% to 83.1% reported at least moderate pain/discomfort at baseline. Higher proportions treated with dupilumab reported no pain/discomfort at week 16 relative to placebo; risk differences ranged from 22.3% (95% confidence interval = 11.5%–33.1%) to 42.2% (95% confidence interval = 26.6%–57.8%, all P ≤ 0.0001), with similar effects observed at week 52. Correlations at baseline of pain/discomfort with signs and symptoms of AD were low to moderate.
Conclusions
Pain/discomfort, present in a substantial proportion of patients with moderate-to-severe AD, was significantly reduced by dupilumab treatment. Given the low-to-moderate correlations with other AD symptoms at baseline, pain likely represents a distinct AD symptom.
Trial Registration: ClinicalTrials.gov identifiers NCT01859988, NCT02277743, NCT02277769, NCT02260986, and NCT02755649
Galaxy And Mass Assembly (GAMA): the wavelength-dependent sizes and profiles of galaxies revealed by MegaMorph
We investigate the relationship between colour and structure within galaxies using a large, volume-limited sample of bright, low-redshift galaxies with optical–near-infrared imaging from the Galaxy And Mass Assembly survey. We fit single-component, wavelength-dependent, elliptical Sérsic models to all passbands simultaneously, using software developed by the MegaMorph project. Dividing our sample by n and colour, the recovered wavelength variations in effective radius (Re) and Sérsic index (n) reveal the internal structure, and hence formation history, of different types of galaxies. All these trends depend on n; some have an additional dependence on galaxy colour. Late-type galaxies (nr 2.5), even though they maintain constant n with wavelength, revealing that ellipticals are a superimposition of different stellar populations associated with multiple collapse and merging events. Processes leading to structures with larger Re must be associated with lower metallicity or younger stellar populations. This appears to rule out the formation of young cores through dissipative gas accretion as an important mechanism in the recent lives of luminous elliptical galaxies
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