Phase transitions in soft-committee machines

Equilibrium statistical physics is applied to layered neural networks with differentiable activation functions. A first analysis of off-line learning in soft-committee machines with a finite number (K) of hidden units learning a perfectly matching rule is performed. Our results are exact in the limit of high training temperatures. For K=2 we find a second order phase transition from unspecialized to specialized student configurations at a critical size P of the training set, whereas for K > 2 the transition is first order. Monte Carlo simulations indicate that our results are also valid for moderately low temperatures qualitatively. The limit K to infinity can be performed analytically, the transition occurs after presenting on the order of N K examples. However, an unspecialized metastable state persists up to P= O (N K^2).Comment: 8 pages, 4 figure

Upadacitinib treatment in a real-world difficult-to-treat atopic dermatitis patient cohort

Background: Upadacitinib was the first JAK-1 selective inhibitor registered for the treatment of moderate-to-severe atopic dermatitis (AD). Although efficacy and safety have been shown in clinical trials, real-world data on the use of upadacitinib in patients that have been treated with other immunosuppressants and targeted therapies is limited. Objectives: To provide real-world evidence on the use of upadacitinib treatment in moderate-to-severe atopic dermatitis. Methods: In this prospective observational single-centre study, all AD patients treated with upadacitinib treatment in the context of standard care were included between August 2021 and September 2022. Clinical outcome measures and adverse events (AEs) were analysed. Results: Forty-eight patients were included. The majority (n = 39; 81%) had failed (ineffectiveness) on other targeted therapies, including other JAK inhibitors and biologics. Thirty-four (71%) patients were still using upadacitinib treatment at last follow up (median duration 46.5 weeks). Fourteen (29%) patients discontinued treatment due to ineffectiveness or AE. Upadacitinib treatment led to a significant decrease of disease severity during a median follow up of 37.5 weeks. Median IGA at baseline decreased from 3 (IQR 2–3) to 1.5 (IQR 1–2) at last review (p &lt; 0.001). Median NRS itch decreased from 7 (IQR 5–8) at baseline to 2.25 (IQR 0.25–6.5) at last review (p &lt; 0.001). Three patients discontinued treatment due to AE. Forty-eight AEs were reported, including acne-like eruptions (25%), nausea (13%) and respiratory tract infections (10%). Conclusions: In this real-world cohort, we confirmed that upadacitinib is an effective treatment in a subset of AD patients that have failed several previous systemic immunosuppressive and biologic treatments. Overall, AE were mostly well tolerated and not a reason to discontinue treatment for most patients.</p

Light scattering from a periodically modulated two dimensional electron gas with partially filled Landau levels

We study light scattering from a periodically modulated two dimensional electron gas in a perpendicular magnetic field. If a subband is partially filled, the imaginary part of the dielectric function as a function of frequency contains additional discontinuities to the case of completely filled subbands. The positions of the discontinuities may be determined from the partial filling factor and the height of the discontinuity can be directly related to the modulation potential. The light scattering cross section contains a new peak which is absent for integer filling.Comment: RevTex, 4 figures. To appear in Phys. Rev. B as a brief repor

A Laterally Modulated 2D Electron System in the Extreme Quantum Limit

We report on magnetotransport of a two-dimensional electron system (2DES), located 32 nm below the surface, with a surface superlattice gate structure of periodicity 39 nm imposing a periodic modulation of its potential. For low Landau level fillings $\nu$, the diagonal resistivity displays a rich pattern of fluctuations, even though the disorder dominates over the periodic modulation. Theoretical arguments based on the combined effects of the long-wavelength, strong disorder and the short-wavelength, weak periodic modulation present in the 2DES qualitatively explain the data.Comment: 4 pages, 5 figures. to appear in Phys. Rev. Let

Real-world effectiveness of abrocitinib treatment in patients with difficult-to-treat atopic dermatitis

Background: Abrocitinib is a JAK-1 selective inhibitor registered for the treatment of moderate-to-severe atopic dermatitis (AD). Although efficacy and safety have been shown in phase 3 clinical trials, data on real-world patients with a treatment history of advanced systemics are scarce. Objectives:The objective of the study was to evaluate the effectiveness and safety of abrocitinib treatment in patients with difficult-to-treat AD in daily practice. Methods: In this prospective observational single-centre study, all AD patients who started abrocitinib treatment in the context of standard care between April 2021 and December 2022 were included. Effectiveness was assessed using clinician- and patient-reported outcome measures. Adverse events were evaluated. Results: Forty-one patients were included. The majority (n = 30; 73.2%) had failed (ineffectiveness) on other targeted therapies, including JAK inhibitors (n = 14, 34%) and biologics (n = 16, 39%). Abrocitinib treatment resulted in a significant decrease in disease severity during a median follow-up period of 25 weeks (IQR 16–34). Median EASI score at baseline decreased from 14.7 (IQR 10.4–25.4) to 4.0 (IQR 1.6–11.4) at last review (p &lt; 0.001). Median NRS itch decreased from 7.0 (IQR 5–8) to 3.0 (IQR 1–2) at last review (p &lt; 0.001). The most frequently reported AEs included gastrointestinal symptoms (27.6%), acne (20.7%) and respiratory tract infections (17.2%). 16 (39%) patients discontinued abrocitinib treatment due to ineffectiveness, AEs or both (41.2%, 41.2% and 11.8%, respectively). Conclusion: Abrocitinib can be an effective treatment for patients with moderate-to-severe AD in daily practice, including non-responders to other targeted therapies.</p

Monitoring of tritium purity during long-term circulation in the KATRIN test experiment LOOPINO using laser Raman spectroscopy

The gas circulation loop LOOPINO has been set up and commissioned at Tritium Laboratory Karlsruhe (TLK) to perform Raman measurements of circulating tritium mixtures under conditions similar to the inner loop system of the neutrino-mass experiment KATRIN, which is currently under construction. A custom-made interface is used to connect the tritium containing measurement cell, located inside a glove box, with the Raman setup standing on the outside. A tritium sample (purity > 95%, 20 kPa total pressure) was circulated in LOOPINO for more than three weeks with a total throughput of 770 g of tritium. Compositional changes in the sample and the formation of tritiated and deuterated methanes CT_(4-n)X_n (X=H,D; n=0,1) were observed. Both effects are caused by hydrogen isotope exchange reactions and gas-wall interactions, due to tritium {\beta} decay. A precision of 0.1% was achieved for the monitoring of the T_2 Q_1-branch, which fulfills the requirements for the KATRIN experiment and demonstrates the feasibility of high-precision Raman measurements with tritium inside a glove box

Duality Relation among Periodic Potential Problems in the Lowest Landau Level

Using a momentum representation of a magnetic von Neumann lattice, we study a two-dimensional electron in a uniform magnetic field and obtain one-particle spectra of various periodic short-range potential problems in the lowest Landau level.We find that the energy spectra satisfy a duality relation between a period of the potential and a magnetic length. The energy spectra consist of the Hofstadter-type bands and flat bands. We also study the connection between a periodic short-range potential problem and a tight-binding model.Comment: 6 pages, 3 figures, final version to appear in PR

Magnetization in short-period mesoscopic electron systems

We calculate the magnetization of the two-dimensional electron gas in a short-period lateral superlattice, with the Coulomb interaction included in Hartree and Hartree-Fock approximations. We compare the results for a finite, mesoscopic system modulated by a periodic potential, with the results for the infinite periodic system. In addition to the expected strong exchange effects, the size of the system, the type and the strength of the lateral modulation leave their fingerprints on the magnetization.Comment: RevTeX4, 10 pages with 14 included postscript figures To be published in PRB. Replaced to repair figure