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Adsorption of water vapor in nanoporous carbons is rather complex due to an interplay between the pore structure and surface chemistry of these materials. Deciphering the mechanism of adsorption requires the knowledge of the spatial distribution and the filling fraction of the adsorbed water. Characteristics of ultrasonic wave propagation through a nanoporous sample provides a wealth of information such as properties of fluids confined in the pores and spatial distribution of adsorbate in the pores. Here we studied water vapor adsorption on carbon xerogel, with a bimodal pore size distribution consisting of micropores (1 nm) and mesopores (8 nm) and overall porosity 68%. The relative humidity was increased in steps and the amount of water adsorbed by the sample was measured gravimetrically at each step, producing a type V isotherm, characteristic of water adsorption to weakly interacting carbon nanopores. Concurrently, we recorded the waveforms for longitudinal and transverse ultrasonic waves that passed through the sample at each saturation step. These measurements provided the wave amplitudes and speeds as a function of relative humidity, and these data were used to calculate the elastic moduli and ultrasonic attenuation of the xerogel-water composite. Analysis of the elastic moduli evolution suggested that confined water shows nearly bulk-like properties in mesopores, while in micropores its modulus noticeably differs from that of bulk water, consistent with theoretical predictions. Furthermore, the observed increase in ultrasonic attenuation during micropore filling indicated the spatial heterogeneity of the water-filled pore space within the overall sample volume. Overall, this study demonstrates the successful utilization of nondestructive ultrasonic testing to probe the fluid adsorption mechanism in a nanoporous medium and the properties of adsorbed phase.

We study the dynamics of multipulse solutions in mode-locked lasers in presence of time-delayed feedback stemming, e.g., from reflections upon optical elements, and carrier dynamics. We demonstrate that the dynamics of such a high dimensional problem can be successfully described by some effective equations of motion for the pulses' phases and positions. Analyzing the reduced vector field permits disclosing a highly complex dynamics where coherent and incoherent interactions compete. The latter lead to regimes in which pulses can be equidistant or non-equidistant and also have different phase relations. Multi-stability between regimes is also observed as well as emerging limit cycles and global heteroclinic bifurcations in phase space.

Quantum differential operators on Reflection Equation Algebras, corresponding to Hecke symmetries R were introduced in previous publications. In the present paper we are mainly interested in quantum analogs of the Laplace and Casimir operators, which are invariant with respect to the action of the Quantum Groups U_q(sl(N)), provided R is the Drinfeld-Jimbo matrix. We prove that any such operator maps the characteristic subalgebra of a Reflection Equation algebra into itself. Also, we define the notion of normal ordering for the quantum differential operators and prove an analog of the Wick theorem. As an important corollary we find a universal matrix Capelli identity generalizing the results of [Ok2] and [JLM]., Comment: The proof of Theored 13 is given, misprints are corrected, some parts of presentation are given in more detailed form

We investigate the nonlinear dynamics of vertically emitting Kerr microcavities under detuned optical injection, considering the impact of slow thermal effects. Our model integrates thermal detuning caused by refractive index shifts due to heating. Through numerical and analytical approaches, we uncover a rich spectrum of dynamical behaviors, including excitable thermo-optical pulses, mixed-mode oscillations, and chaotic spiking, governed by a higher-dimensional canard scenario. Introducing a long external feedback loop with time delays comparable to the microcavity photon lifetime but shorter than thermal relaxation timescales, reveals how delay affects excitability and stabilizes temporal localized states. Our findings extend the understanding of excitable systems, demonstrating how thermal and feedback mechanisms interplay to shape nonlinear optical dynamics. Further, our approach paves the way for the study of cavity stabilization and cavity cooling using an additional control beam.

Let $f: {\mathbb Z}_N^d \to {\mathbb C}$ be a signal with the Fourier transform $\widehat{f}: \Bbb Z_N^d\to \Bbb C$. A classical result due to Matolcsi and Szucs (\cite{MS73}), and, independently, to Donoho and Stark (\cite{DS89}) states if a subset of frequencies ${\{\widehat{f}(m)\}}_{m \in S}$ of $f$ are unobserved due to noise or other interference, then $f$ can be recovered exactly and uniquely provided that $$ |E| \cdot |S|<\frac{N^d}{2},$$ where $E$ is the support of $f$, i.e., $E=\{x \in {\mathbb Z}_N^d: f(x) \not=0\}$. In this paper, we consider signals that are Dirac combs of complexity $\gamma$, meaning they have the form $f(x)=\sum_{i=1}^{\gamma} a_i 1_{A_i}(x)$, where the sets $A_i \subset {\mathbb Z}_N^d$ are disjoint, $a_i$ are complex numbers, and $\gamma \leq N^d$. We will define the concept of effective support of these signals and show that if $\gamma$ is not too large, a good recovery condition can be obtained by pigeonholing under additional reasonable assumptions on the distribution of values. Our approach produces a non-trivial uncertainty principle and a signal recovery condition in many situations when the support of the function is too large to apply the classical theory.

We consider the so-called generalized Harish-Chandra morphism, taking the center of the enveloping algebra U(gl(N)) to the commutative algebra generated by eigenvalues of the generating matrix of this algebra, and generalize this construction to Reflection Equation algebras. To this end we introduce the eigenvalues of the generating matrix of the Reflection Equation algebra (modified or not), corresponding to a skew-invertible Hecke symmetry and define the generalized Harish-Chandra morphism in a similar way. We use this map in order to introduce quantum analogs of the so-called weight systems., Comment: Minor changes: some typos were corrected

Visual models play a crucial role in both science and science communication. However, the distinction between mere analogies and mathematically sound graphical representations is not easy and can be misunderstood not only by laypeople but also within academic literature itself. Moreover, even when the graphical representation exactly corresponds to the mathematical model, its interpretation is often far from obvious. In this paper we discuss the "potential landscape" visualization commonly used for tipping points in the context of nonlinear dynamics and reveal potential pitfalls, in particular when distinguishing bifurcation induced tipping (B-tipping) from noise-induced tipping (N-tipping). We propose new visualization techniques for tipping dynamics, carefully distinguishing between B- and N-tipping as well as between single systems and ensembles of systems. Explicitly, we apply these visualizations both to molecular cell biology and to climate science in order to reveal the crucial differences in the interpretation of the visual models. We find that it is crucial to explicitly discuss the assumptions made within the visual model and to be aware of the risk of misinterpretation. Based on these findings, we propose as a next step to investigate individual mental models induced by these visualizations in the framework of empirical research., Comment: 20 pages, 11 figures

Recent analysis of classical algorithms resulted in their axiomatization as transition systems satisfying some simple postulates, and in the formulation of the Abstract State Machine Theorem, which assures us that any classical algorithm can be emulated step-by-step by a most general model of computation, called an ``abstract state machine''. We refine that analysis to take details of intra-step behavior into account, and show that there is in fact an abstract state machine that not only has the same state transitions as does a given algorithm but also performs the exact same tests on states when determining how to proceed to the next state. This enhancement allows the inclusion -- within the abstract-state-machine framework -- of algorithms whose states only have partially-defined equality, or employ other native partial functions, as is the case, for instance, with inversion of a matrix of computable reals.

The Fall 2024 Logic in Computer Science column of the Bulletin of EATCS is a little discussion on intelligence, measuring intelligence, and related issues, provoked by a fascinating must-read article ``On the measure of intelligence'' by Fran\c{c}ois Chollet. The discussion includes a modicum of critique of the article.

A hundred years ago, logic was almost synonymous with foundational studies. The ongoing AI revolution raises many deep foundational problems involving neuroscience, philosophy, computer science, and logic. The goal of the following dialog is to provoke young logicians with a taste for foundations to notice the foundational problems raised by the AI revolution.

We study the steady-state properties of quantum channels with local Kraus operators. We consider a large family that consists of general ergodic 1-local (non-interacting) terms and general 2-local (interacting) terms. Physically, a repeated application of these channels can be seen as a simple model for the thermalization process of a many-body system. We study its steady state perturbatively by interpolating between the 1-local and 2-local channels with a perturbation parameter $\epsilon$. We prove that under very general conditions, these states are Gibbs states of a quasi-local Hamiltonian. Expanding this Hamiltonian as a series in $\epsilon$, we show that the $k$'th order term corresponds to a $(k+1)$-local interaction term in the Hamiltonian, which follows the same interaction graph as the Kraus channel. We also prove a complementary result suggesting the existence of an interaction strength threshold, under which the total weight of the high-order terms in the Hamiltonian decays exponentially fast. This result also implies a quasi-polynomial classical algorithm for computing the expectation value of local observables in such steady states. Finally, we also present numerical simulations of various channels that support our theoretical claims., Comment: 26 pages

Of the many applications of whispering-gallery mode (WGM) microresonators, Single-atom cavity-QED poses the most extreme demands on mode-volume and quality factor. Here we present a model-based procedure for the fabrication of small mode-volume ultrahigh Q silica WGM microresonators of varying geometries, from toroidal to micro-spheres. We experimentally demonstrate WGM resonators with ultra-high qualities as high as $1.7\times 10^8$ at 780nm. We present a theoretical model that allows tailoring the recipe to attain the desired geometry of the fabricated WGM microresonators., Comment: 15 pages, 9 figure

We report numerical simulations of coupled sine-Gordon and heat diffusion equations describing dynamic states stimulated by a trapped vortex driven by dc current in a stack of up to $N=321$ Josephson junctions. It is shown that the Cherenkov wake behind the vortex shuttle trapped in the stack can trigger proliferation of counter-propagating vortices and antivortices which get synchronized and form large-amplitude standing electromagnetic waves. This happens if the dc current density $J$ exceeds a threshold value $J_s$ which can be well below the Josephson interlayer critical current density $J_c$ for underdamped junctions. The cavity modes stimulated by the vortex-antivortex pair production cause peaks in the radiated power $P_N(J)$ with a nearly monochromatic spectrum at discrete values of $J$ corresponding to the zero-field Fiske resonances. The power $P_N(J)$ was evaluated for small rectangular stacks in the magneto-dipole approximation and for large stacks in a single mode state. For small stacks, the highest peak in $P_N(J)$ increases rapidly, $P_N\propto N^6$, with the number of junctions at $N\leq 81$ and gradually slows down to $P_N\propto N^2$ at $161\leq N\leq 321$. For stacks larger than the radiated wavelength, we obtained $P_N\propto N^5$ at $N\lesssim 200-300$ and $P_N\propto N^2$ at larger $N$. For stacks with up to $321$ junctions and representative parameters of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$, we observed moderate overheating and no hotspots. The vortex-antivortex pair production can amplify THz radiation from Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ mesas for which trapping Josephson vortices could be used to stimulate THz emission at subcritical currents and optimize the radiation output.

We describe interrelations between a topology structure of closed manifolds (orientable and non-orientable) of the dimension $n\geq 4$ and the structure of the non-wandering set of regular homeomorphisms, in particular, Morse-Smale diffeomorphisms., Comment: 26 pages, 2 figures

We predict the existence of a novel type of temporal localized structure in injected Kerr--Gires--Tournois interferometers (KGTI). These bright pulses exist in the normal dispersion regime, yet they do not correspond to the usual scenario of domain wall locking that induces complex shape multistability, weak stability, and a reduced domain of existence. The new states are observed beyond the mean-field limit and out of the bistable region. Their shape is uniquely defined, with peak intensities beyond that of the upper steady state, and they are stable over a broad range of the injection field, highlighting their potential for optical frequency comb (OFC) generation., Comment: 5 pages 4 figures

We report the existence of localized states in dipolar Bose-Einstein condensates confined to a tubular geometry. We first perform a bifurcation analysis to track their emergence in a one-dimensional domain for numerical feasibility and find that localized states can become the ground state in suitable parameter regions. Their existence for parameters featuring a supercritical primary bifurcation shows that the latter is not sufficient to conclude that the phase transition is of second order, hence density modulations can jump rather than emerging gradually. Finally, we show that localized states also exist in a three-dimensional domain.

We obtain two explicit formulas for the full local character expansion of any irreducible representation of a p-adic general linear group in principal blocks. The first, generalizing previous work of the author on the Iwahori-spherical case, expresses the expansion in terms of dimensions of degenerate Whittaker models. The second gives a closed expression in terms of values of Kazhdan-Lusztig polynomials of a suitable permutation group., Comment: to appear in the IMS Lecture Note Series for "Representations and Characters: Revisiting the Works of Harish-Chandra and Andr\'e Weil"

Robust access to trustworthy information is a critical need for society with implications for knowledge production, public health education, and promoting informed citizenry in democratic societies. Generative AI technologies may enable new ways to access information and improve effectiveness of existing information retrieval systems but we are only starting to understand and grapple with their long-term social implications. In this chapter, we present an overview of some of the systemic consequences and risks of employing generative AI in the context of information access. We also provide recommendations for evaluation and mitigation, and discuss challenges for future research.

According to Dirac's bra-ket notation, in an inner-product space, the inner product $\langle x\,|\,y\rangle$ of vectors $x,y$ can be viewed as an application of the bra $\langle x|$ to the ket $|y\rangle$. Here $\langle x|$ is the linear functional $|y\rangle \mapsto \langle x\,|\,y\rangle$ and $|y\rangle$ is the vector $y$. But often -- though not always -- there are advantages in seeing $|y\rangle$ as the function $a \mapsto a\cdot y$ where $a$ ranges over the scalars. For example, the outer product $|y\rangle\langle x|$ becomes simply the composition $|y\rangle \circ \langle x|$. It would be most convenient to view kets sometimes as vectors and sometimes as functions, depending on the context. This turns out to be possible. While the bra-ket notation arose in quantum mechanics, this note presupposes no familiarity with quantum mechanics., Comment: Bulletin of the EATCS 141 October 2023

Weak Arthur packets have long been instrumental in the study of the unitary dual and automorphic spectrum of reductive Lie groups, and were recently introduced in the p-adic setting by Ciubotaru - Mason-Brown - Okada. For split odd orthogonal and symplectic p-adic groups, we explicitly determine the decomposition of weak Arthur packets into Arthur packets that arise from endoscopic transfer. We establish a characterization of the Arthur packets that partake in such decompositions by means of ramification properties of their constituents. A notion of weak sphericity for an irreducible representation is introduced: The property of containing fixed vectors with respect to a (not necessarily hyperspecial) maximal compact subgroup. We show that this property determines the weak Arthur packets in a precise sense. As steps towards this description, we explore alignments between Langlands-type reciprocities for finite and p-adic groups, and their dependence on the geometry of the unipotent locus of the dual Langlands group. Weak sphericity is shown to match with Lusztig's canonical quotient spaces that feature in the geometric theory for Weyl group representations, while the fine composition of weak Arthur packets is found to be governed by the partition of the unipotent locus into special pieces., Comment: 77 pages

Let $G$ be a split simply-connected group of type $D$ or $E$. The minimal automorphic representation $\Pi$ of $G(\mathbb A)$ admits a realization on a space of functions $\mathcal S(X(\mathbb A))$ for a variety $X$. In this paper we write explicitly an automorphic, i.e. $G(F)$-invariant, functional on $\mathcal S(X(\mathbb A)).$, Comment: The introduction has been rewritten. The mathematics is mainly unchanged

Background: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment but can result in severe immune-related adverse events (IrAEs). Monitoring IrAEs on a large scale is essential for personalized risk profiling and assisting in treatment decisions. Methods: In this study, we conducted an analysis of clinical notes from patients who received ICIs at the Tel Aviv Sourasky Medical Center. By employing a Natural Language Processing algorithmic pipeline, we systematically identified seven common or severe IrAEs. We examined the utilization of corticosteroids, treatment discontinuation rates following IrAEs, and constructed survival curves to visualize the occurrence of adverse events during treatment. Results: Our analysis encompassed 108,280 clinical notes associated with 1,635 patients who had undergone ICI therapy. The detected incidence of IrAEs was consistent with previous reports, exhibiting substantial variation across different ICIs. Treatment with corticosteroids varied depending on the specific IrAE, ranging from 17.3% for thyroiditis to 57.4% for myocarditis. Our algorithm demonstrated high accuracy in identifying IrAEs, as indicated by an area under the curve (AUC) of 0.89 for each suspected note and F1 scores of 0.87 or higher for five out of the seven IrAEs examined at the patient level. Conclusions: This study presents a novel, large-scale monitoring approach utilizing deep neural networks for IrAEs. Our method provides accurate results, enhancing understanding of detrimental consequences experienced by ICI-treated patients. Moreover, it holds potential for monitoring other medications, enabling comprehensive post-marketing surveillance to identify susceptible populations and establish personalized drug safety profiles.

In our previous publications we have developed some elements of Noncommutative calculus on the enveloping algebras of $A_m$ type, in particular, analogs of the partial derivatives and de Rham complex were defined. Also, we introduced the notion of quantization with Noncommutative configuration space and quantized a few dynamical models in this sense. In the current paper we propose a method of quantizing the Yang-Mills models in same sense.

We report the RF performance of several single-cell superconducting radio-frequency cavities subjected to low temperature heat treatment in nitrogen environment. The cavities were treated at temperature 120 - 165 $^{\circ}$C for an extended period of time (24 - 48 hours) either in high vacuum or in a low partial pressure of ultra-pure nitrogen. The improvement in $Q_0$ with a Q-rise was observed when nitrogen gas was injected at $\sim$300 $^{\circ} $C during the cavity cooldown from 800 $^{\circ}$C and held at 165 $^{\circ}$C, without any degradation in accelerating gradient over the baseline performance. The treatment was applied to several elliptical cavities with frequency ranging from 0.75 GHz to 3.0 GHz, showing an improved quality factor as a result of low temperature nitrogen treatments. The Q-rise feature is similar to that achieved by nitrogen alloying Nb cavities at higher temperature, followed by material removal by electropolishing. The surface modification was confirmed by the change in electronic mean free path and tuned with the temperature and duration of heat treatment. The decrease of the temperature-dependent surface resistance with increasing RF field, resulting in a Q-rise, becomes stronger with increasing frequency and decreasing temperature. The data suggest a crossover frequency of $\sim 0.95$~GHz above which the Q-rise phenomenon occurs at 2~K. Some of these results can be explained qualitatively with an existing model of intrinsic field-dependence of the surface resistance with both equilibrium and nonequilibrium quasiparticle distribution functions. The change in the Q-slope below 0.95 GHz may result from masking contribution of trapped magnetic flux to the residual surface resistance.

We demonstrate the existence of a multiplicity of co-existing frequency combs in a harmonically mode-locked laser that we link to the splay phases of the Kuramoto model with short range interactions. These splay states are multistable and the laser may wander between them under the influence of stochastic forces. Consequently, the many pulses circulating in the cavity are not necessarily coherent with each other. We show that this partially disordered state for the phase of the optical field features regular train of pulses in the field intensity, a state that we term an incoherent crystal of optical pulses. We provide evidence that the notion of coherence should be interpreted by comparing the duration of the measurement time with the Kramers' escape time of each splay state. Our results are confirmed experimentally by studying a passively mode-locked vertical external-cavity surface-emitting laser., Comment: Main manuscript (5 pages + 5 figures) & Supplementary material (10 pages + 6 figures)

We report the measurement of the helicity asymmetry $E$ for the $p\pi^0$ and $n\pi^+$ final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g.~$G$) and circularly polarized photons (e.g.~$E$) and a longitudinally polarized target. The new data cover a photon energy range 270 - 1400 MeV for the $p\pi^0$ final state (230 - 842 MeV for the $n\pi^+$ final state) and the full range of pion polar angles, $\theta$, providing the most precise measurement of the observable $E$. A moment analysis gives a clear observation of the $p\eta$ cusp in the $p\pi^0$ final state.

We study the dynamics of an optoelectronic circuit composed of an excitable nanoscale resonant-tunneling diode (RTD) driving a nanolaser diode (LD) coupled via time-delayed feedback. Using a combination of numerical path-continuation methods and time simulations, we demonstrate that this RTD-LD system can serve as an artificial neuron, generating pulses in the form of temporal localized states (TLSs) that can be employed as memory for neuromorphic computing. In particular, our findings reveal that the prototypical delayed FitzHugh-Nagumo model previously employed to model the RTD-LD resembles our more realistic model only in the limit of a slow RTD. We show that the RTD time scale plays a critical role in memory capacity as it governs a shift in pulse interaction from repulsive to attractive, leading to a transition from stable to unstable multi-pulse TLSs. Our theoretical analysis uncovers features and challenges previously unknown for the RTD-LD system, including the multistability of TLSs and attractive interaction forces, stemming from the previously neglected intrinsic dynamics of the laser. These effects are crucial to consider since they define the memory properties of the RTD-LD., Comment: 17 pages, 9 figures. V2: corrected typos, clarified passages

We propose a time-delayed model for the study of active mode-locking that is valid for large values of the round-trip gain and losses. It allows us to access the typical regimes encountered in semiconductor lasers and to perform an extended bifurcation analysis. Close to the harmonic resonances and to the lasing threshold, we recover the Hermite-Gauss solutions. However, the presence of the linewidth enhancement factor induces complex regimes in which even the fundamental solution becomes unstable. Finally, we discover a global bifurcation scenario in which a single pulse can jump, over a slow time scale, between the different minima of the modulation potential.

We present a polynomial basis that exactly tridiagonalizes Teukolsky's radial equation for quasi-normal modes. These polynomials naturally emerge from the radial problem, and they are "canonical" in that they possess key features of classical polynomials. Our canonical polynomials may be constructed using various methods, the simplest of which is the Gram-Schmidt process. In contrast with other polynomial bases, our polynomials allow for Teukolsky's radial equation to be represented as a simple matrix eigenvalue equation that has well-behaved asymptotics and is free of non-physical solutions. We expect that our polynomials will be useful for better understanding the Kerr quasinormal modes' properties, particularly their prospective spatial completeness and orthogonality. We show that our polynomials are closely related to the confluent Heun and Pollaczek-Jacobi type polynomials. Consequently, our construction of polynomials may be used to tridiagonalize other instances of the confluent Heun equation. We apply our polynomials to a series of simple examples, including: (1) the high accuracy numerical computation of radial eigenvalues, (2) the evaluation and validation of quasinormal mode solutions to Teukolsky's radial equation, and (3) the use of Schwarzschild radial functions to represent those of Kerr. Along the way, a potentially new concept, "confluent Heun polynomial/non-polynomial duality", is encountered and applied to show that some quasinormal mode separation constants are well approximated by confluent Heun polynomial eigenvalues. We briefly discuss the implications of our results on various topics, including the prospective spatial completeness of Kerr quasinormal modes., Comment: 19 pages, 7 figures

A new data set for the helicity-dependent differential cross section of the single-meson photoproduction reaction $\gamma p \to p \pi^{0}$ was obtained for the photon energy interval 150-400 MeV. The experiment was performed at the A2 tagged photon facility of the Mainz Microtron MAMI using a circularly polarized photon beam and a longitudinally polarized proton target. The reaction products were detected with the large acceptance Crystal Ball/TAPS calorimeter covering 97\% of the full solid angle. These new results, obtained with a fine energy and polar angle binning, greatly increase both the existing quantity and quality of the data available for this observable. A moment analysis, based on a finite expansion in Legendre polynomials, was applied to these data by using a bootstrap-based fitting method to correctly account for their systematic uncertainties. From the resulting decomposition of the differential cross sections, the $E2/M1$ ratio for the $N\to \Delta(1232)$ transition was determined to be $[-2.38 \pm 0.16{\hbox{ (stat.+sys.)}} \pm 0.10 {\hbox{ (model)}}] \%$. Combining this value with previous results also allowed us to evaluate the most precise available estimate of the $E2/M1$ ratio to be used for all further reference and model comparisons., Comment: 16 pages, 14 figures

This book was created as part of the SIRIUS B VERGE program to orient students to astrophysics as a broad field. The 2023-2024 VERGE program and the printing of this book is funded by the Women and Girls in Astronomy Program via the International Astronomical Union's North American Regional Office of Astronomy for Development and the Heising-Simons Foundation; as a result, this document is written by women in astronomy for girls who are looking to pursue the field. However, given its universal nature, the material covered in this guide is useful for anyone interested in pursuing astrophysics professionally., Comment: Introductory guide for students interested in pursuing astrophysics; to be submitted to BAAS

Here, upon systematic studies of femtosecond-laser processing of monocrystalline Si in oxidation-preventing methanol, we showed that the electromagnetic processes dominating at initial steps of the progressive morphology evolution define the onset of the hydrodynamic processes and resulting morphology upon subsequent multi-pulse exposure. In particular, under promoted exposure quasi-regular subwavelength laser-induced periodic surface structures (LIPSSs) were justified to evolve through the template-assisted development of the Rayleigh-Plateau hydrodynamic instability in the molten ridges forming quasi-regular surface patterns with a supra-wavelength periodicity and preferential alignment along polarization direction of the incident light. Subsequent exposure promotes fusion-assisted morphology rearrangement resulting in a spiky surface with a random orientation, yet constant inter-structure distance correlated with initial LIPSS periodicity. Along with the insight onto the physical picture driving the morphology evolution and supra-wavelength nanostructure formation, our experiments also demonstrated that the resulting quasi-regular and random spiky morphology can be tailored by the intensity/polarization distribution of the incident laser beam allowing on-demand surface nanotexturing with diverse hierarchical surface morphologies exhibiting reduced reflectivity in the visible and shortwave IR spectral ranges. Finally, we highlighted the practical attractiveness of the suggested approach for improving near-IR photoresponse and expanding operation spectral range of vertical p-n junction Si photo-detector operating under room temperature and zero-bias conditions via single-step annealing-free laser nanopatterning of its surface., Comment: 13 pages, 6 figures

Photoproduction of $\pi^0\pi^{\pm}$-pairs from quasifree nucleons bound in the deuteron has been investigated to study the helicity dependence of this reaction. Measurements with a liquid deuterium target were used to extract the unpolarized cross sections for reactions on protons and neutrons. A deuterated, longitudinally polarized solid-butanol target, together with a circularly polarized photon beam, determined the double polarization observable $E$. From these results the spin-dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$, corresponding to the anti-parallel and parallel spin configurations of the beam photon and target nucleon, have been derived. The measurements were performed at the Mainz MAMI accelerator with tagged, circularly-polarized photon beams produced via bremsstrahlung from longitudinally polarized electron beams. The reaction products were detected with an almost $4\pi$ solid-angle covering calorimeter composed of the Crystal Ball and TAPS detectors, supplemented by plastic scintillation detectors for charged particle identification. The results are sensitive to sequential decays of nucleon resonances via intermediate states and also to the decay of nucleon resonances by emission of charged $\rho$ mesons, and are compared to recent model results., Comment: 9 pages, 6 figures

We study theoretically the mechanisms of square wave formation of a vertically emitting micro-cavity operated in the Gires-Tournois regime that contains a Kerr medium and that is subjected to strong time-delayed optical feedback and detuned optical injection. We show that in the limit of large delay, square wave solutions of the time-delayed system can be treated as relative homoclinic solutions of an equation with an advanced argument. Based on this, we use concepts of classical homoclinic bifurcation theory to study different types of square wave solutions. In particular, we unveil the mechanisms behind the collapsed snaking scenario of square waves and explain the formation of complex-shaped multistable square wave solutions through a Bykov T-point. Finally we relate the position of the T-point to the position of the Maxwell point in the original time-delayed system.

Parkinsons disease (PD) diagnosis is challenging due to subtle early clinical signs. F-DOPA PET is commonly used for early PD diagnosis. We explore the potential of machine-learning (ML) based EEG features extracted from single-channel EEG during auditory cognitive assessment as a noninvasive, low-cost support for PD diagnosis. The study included data collected from 32 participants who underwent an F-DOPA PET scan as part of their standard treatment and 20 cognitively healthy controls. Participants performed an auditory cognitive assessment recorded with Neurosteer EEG device. Data processing involved wavelet-packet decomposition and ML. First, a prediction model was developed to predict 1/3 of the undisclosed F-DOPA results. Then, generalized linear mixed models were calculated to distinguish between PD and non-PD subjects on the frequency bands and ML-based EEG features (A0 and L1) previously associated with cognitive functions. The prediction model accurately labeled patients with unrevealed scores as positive F-DOPA. Novel EEG feature A0 and the Delta band showed significant separation between study groups, with healthy controls exhibiting higher activity than PD patients. EEG feature L1 activity was significantly lower in resting state compared to high-cognitive load. This effect was absent in the PD group, suggesting that lower activity in resting state is lacking in PD patients. This study successfully demonstrated the ability to separate patients with positive vs. negative F-DOPA PET results with an easy-to-use single-channel EEG during an auditory cognitive assessment. Future longitudinal studies should further explore the potential utility of this tool for early PD diagnosis and as a potential biomarker in PD.