Flow-driven sound generation in fipple-type instruments arises from complex coupling between a jet, a sharp edge, and an acoustic resonator. In this work, we experimentally investigate the flow-dependent acoustic behavior of a Kaps-style whistle driven by nitrogen gas over a wide range of volumetric flow rates. Spectral measurements reveal four distinct regimes. At low-flow rates (3-4.6 l/min), the system exhibits passive resonance excitation governed by the fundamental pipe mode. As the flow increases, the oscillation transitions to a Strouhal-controlled edge-tone regime characterized by St approximate to 0.6. At intermediate flow rates (9-30 l/min), a pronounced resonance lock-in occurs, where the oscillation frequency becomes weakly dependent on the flow rate, while acoustic amplitude continues to grow, indicating strong jet-resonator coupling. Beyond a critical flow rate, an abrupt transition to second-harmonic dominance is observed, accompanied by a reduction of the effective Strouhal number to approximately 0.36. Two-dimensional numerical simulations are used to visualize jet deflection and recirculation patterns, providing a physical interpretation of the regime transitions. The results demonstrate that flow-dependent coupling governs frequency selection, as described by a flow-corrected resonance relation, resonance locking, and harmonic mode switching in fipple-type aeroacoustic systems, offering insight into nonlinear acoustic mode selection in wind instruments.
Precise wavelength calibration is essential for high-precision radial velocity spectrographs, necessitating a stable calibrator that provides a dense grid of uniformly spaced lines to accurately determine stellar line positions and monitor instrumental drifts. In this work, we present the development of a cost-effective Fabry-P & eacute;rot (FP) etalon-based wavelength calibrator designed to overcome the limitations of conventional sources such as hollow cathode lamps (HCLs) and iodine cells. This FP calibrator, combined with a xenon (Xe) arc lamp assembly, has been integrated with the PRL Advanced Radial-velocity Abu-sky Search-2 spectrograph on the Physical Research Laboratory 2.5 m telescope at Mount Abu Observatory. Operated under controlled temperature and pressure conditions, the system generates a dense, comb-like spectrum covering 62 echelle orders with more than 10,000 well-defined and stable spectral lines, enabling precise measurement of instrumental drift. Initial results show that the free spectral range varies from 0.16 angstrom near 4000 angstrom to 0.49 angstrom near 7000 angstrom, with a value of 0.3 angstrom around the central wavelength of 5500 angstrom. The estimated finesse ranges from 9 near 4000 angstrom to 19 near 6900 angstrom, with an approximate value of 17 at 5500 angstrom. The temperature and pressure stability tests demonstrate RMS variations of 0.002 degrees C and 5 & times;10(-4) mbar, respectively. Based on these values, the theoretical stability of the FP wavelength calibrator is estimated to be within 10 cm/s, establishing it as a reliable alternative to laser frequency combs for high-resolution spectroscopic calibration. We present an initial assessment of the RV stability of the Fabry-P & eacute;rot calibrator, yielding 40 to 70 cm/s of relative drift, which are up for further investigations. The observed excess over the theoretically estimated limit is likely attributable to instabilities arising from arc wandering in the Xe arc lamp.
We study the BOOLEAN SATISFIABILITY PROBLEM (SAT) in the framework of diversity, where one asks for multiple solutions that are mutually far apart (i.e., sufficiently dissimilar from each other) for a suitable notion of distance/dissimilarity between solutions. Interpreting assignments as bit vectors, we take their Hamming distance to quantify dissimilarity, and we focus on the problem of finding two solutions. Specifically, we define the problem MAX DIFFER SAT (resp. EXACT DIFFER SAT) as follows: Given a Boolean formula cent on n variables, decide whether cent has two satisfying assignments that differ on at least (resp. exactly) d variables. We study the classical and parameterized (in parameters d and n-d) complexities of MAX DIFFER SAT and EXACT DIFFER SAT, when restricted to some classes of formulas on which SAT is known to be polynomial-time solvable. In particular, we consider affine formulas, Krom formulas (i.e., 2-CNF formulas) and hitting formulas. For affine formulas, we show the following: Both problems are polynomial-time solvable when each equation has at most two variables. EXACT DIFFER SAT is NP-hard, even when each equation has at most three variables and each variable appears in at most four equations. Also, MAX DIFFER SAT is NP-hard, even when each equation has at most four variables. Both problems are W[1]-hard in the parameter n-d. In contrast, when parameterized by d, EXACT DIFFER SAT is W[1]-hard, but MAX DIFFER SAT admits a single-exponential FPT algorithm and a polynomial-kernel. For Krom formulas, we show the following: Both problems are polynomial-time solvable when each variable appears in at most two clauses. Also, both problems are W[1]-hard in the parameter d (and therefore, it turns out, also NP-hard), even on monotone inputs (i.e., formulas with no negative literals). Finally, for hitting formulas, we show that both problems can be solved in polynomial-time.
We show how the 2-Higgs Doublet Model (2HDM) Type-I can explain some excesses recently seen at the Large Hadron Collider (LHC) in γγ and τ+τ− final states in turn matching Large Electron Positron (LEP) data in bb¯ signatures, all anomalies residing around 95 GeV. The explanation to such anomalous data is found in the aforementioned scenario when in inverted mass hierarchy, in two configurations: i) when the lightest CP-even Higgs state is alone capable of reproducing the excesses; ii) when a combination of such a state and the CP-odd Higgs boson is able to do so. To test further this scenario, we present some Benchmark Points (BPs) of it amenable to phenomenological investigation.
Nanoparticle-based phototherapy represents a paradigm shift in precision medicine, harnessing light-activated mechanisms to modulate cellular pathways across a spectrum of diseases. By integrating nanoparticles, phototherapeutic modalities achieve enhanced light absorption and improved targeting and amplification effects, such as reactive oxygen species generation in photodynamic therapy and localized heating in photothermal therapy. Gold nanoparticles and hybrid constructs have attracted considerable attention in both photothermal and photodynamic therapies, while delivery platforms, such as liposomes and dendrimers, fine-tune biodistribution and release kinetics. At the molecular level, phototherapy induces oxidative stress, triggers apoptotic and autophagic cascades and modulates immune responses by altering cytokine profiles and T-cell activity processes, which are critical not only in cancer therapy but also in managing various chronic conditions, including cardiovascular, neurodegenerative, metabolic and autoimmune disorders. In this review, we chart the evolution of nanoparticle-based phototherapy systems by examining their core components, classification schemes and delivery platforms that drive treatment specificity. We then dissect the underlying signaling pathways, highlighting how light-triggered interventions intersect with key molecular networks in chronic disease contexts. Additionally, we critically evaluate FDA-approved agents and insights from recent clinical trials, outlining the major challenges to clinical translation, including nanoparticle optimization, efficient light delivery and regulatory hurdles. By integrating molecular insights with clinical advancements, nanoparticle-based phototherapy has emerged as a transformative, noninvasive strategy poised to revolutionize therapeutic approaches for a wide range of diseases.
