1. Vibrational noise disrupts Nezara viridula communication, irrespective of spectral overlapRok Janža, Nataša Stritih Peljhan, Aleš Škorjanc, Jernej Polajnar, Meta Virant-Doberlet, 2024, izvirni znanstveni članek Povzetek: Insects rely on substrate vibrations in numerous intra- and interspecific interactions. Yet, our knowledge of noise impact in this modality lags behind that in audition, limiting our understanding of how anthropogenic noise affects insect communities. Auditory research has linked impaired signal perception in noise (i.e., masking) to spectral overlap. We investigated the impact of noise with different spectral compositions on the vibrational communication of the stink bug Nezara viridula, examining courtship behaviour and signal representation by sensory neurons. We found negative effects of vibrational noise regardless of spectral overlap, challenging common expectations. Noise impaired the ability of males to recognize the female signal and localise its source: overlapping noise decreased sensitivity of receptor neurons to the signal and disrupted signal frequency encoding by phase-locking units, while non-overlapping noise only affected frequency encoding. Modelling neuronal spike triggering in sensory neurons linked disrupted frequency encoding to interference-induced alterations of the signal waveform. These alterations also affected time delays between signal arrivals to different legs, crucial for localisation. Our study thus unveils a new masking mechanism, potentially unique to insect vibrosensory systems. The findings highlight the higher vulnerability of vibration-mediated behaviour to noise, with implications for insect interactions in natural and anthropogenically altered environments.
Ključne besede: biotremology, vibrations, noise, communication, neurons, masking, entomology, neurobiology
Objavljeno v DiRROS: 21.11.2024; Ogledov: 132; Prenosov: 2474
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2. Image reconstruction using small-voxel size improves small lesion detection for positron emission tomographySebastijan Rep, Petra Tomše, Luka Jensterle, Leon Jarabek, Katja Zaletel, Luka Ležaič, 2022, izvirni znanstveni članek Povzetek: Background. PET/CT imaging is widely used in oncology and provides both metabolic and anatomic information. Because of the relatively poor spatial resolution of PET, the detection of small lesions is limited. The low spatial resolution introduces the partial-volume effect (PVE) which negatively affects images both qualitatively and quantitatively. The aim of the study was to investigate the effect of small-voxel (2 mm in-line pixel size) vs. standard-voxel (4 mm in-line pixel size) reconstruction on lesion detection and image quality in a range of activity ratios. Materials and methods. The National Electrical Manufacturers Association (NEMA) body phantom and the Micro Hollow-Sphere phantom spheres were filled with a solution of [18F]fluorodeoxyglucose ([18F]FDG) in sphere-to-background ratios of 2:1, 3:1, 4:1 and 8:1. In all images reconstructed with 2 mm and 4 mm in-line pixel size the visual lesion delineation, contrast recovery coefficient (CRC) and contrast-to-noise ratio (CNR) were evaluated. Results. For smaller (≤ 13 mm) phantom spheres, significantly higher CRC and CNR using small-voxel reconstructions were found, also improving visual lesion delineation. CRC did not differ significantly for larger (≥ 17 mm) spheres using 2 mm and 4 mm in-line pixel size, but CNR was significantly lower; however, lower CNR did not affect visual lesion delineation. Conclusions. Small-voxel reconstruction consistently improves precise small lesion delineation, lesion contrast and image quality.
Ključne besede: PET/CT, voxel size, contrast recovery coefficient, contrast-to-noise ratio
Objavljeno v DiRROS: 24.07.2024; Ogledov: 326; Prenosov: 205
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3. Leafhopper males compensate for unclear directional cues in vibration-mediated mate localizationJernej Polajnar, Ana Kuhelj, Rok Janža, Nada Žnidaršič, Tatjana Simčič, Meta Virant-Doberlet, 2023, izvirni znanstveni članek Povzetek: Ambient noise and transmission properties of the substrate pose challenges in vibrational signal-mediated mating behavior of arthropods, because vibrational signal production is energetically demanding. We explored implications of these challenges in the leafhopper Aphrodes makarovi (Insecta: Hemiptera: Cicadellidae) by exposing males to various kinds of vibrational noise on a natural substrate and challenging them to find the source of the female playback. Contrary to expectations, males exposed to noise were at least as efficient as control males on account of similar searching success with less signaling effort, while playing back male–female duets allowed the males to switch to satellite behavior and locate the target without signaling, as expected. We found altered mitochondrial structure in males with high signaling effort that likely indicate early damaging processes at the cellular level in tymbal muscle, but no relation between biochemical markers of oxidative stress and signaling effort. Analysis of signal transmission revealed ambiguous amplitude gradients, which might explain relatively low searching success, but it also indicates the existence of behavioral adaptations to complex vibrational environments. We conclude that the observed searching tactic, emphasizing speed rather than thorough evaluation of directional cues, may compensate for unclear stimuli when the target is near.
Ključne besede: biotremology, vibrational communication, sexual behavior of insects, impact of noise on behavior, metabolism of vibrational production
Objavljeno v DiRROS: 12.07.2024; Ogledov: 271; Prenosov: 252
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4. Appropriate sound insulation of facades as a measure to ensure acceptable acoustic comfort in residential buildingsMihael Ramšak, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: Wherever possible, the environment with residential buildings should be protected from the effects of noise sources by environmental noise reduction measures. If such measures cannot reduce the noise level in the environment to an acceptable level, acceptable acoustic comfort in the residential buildings shall be ensured by adequate sound insulation of the facades, which is the main topic of this paper. The paper outlines some of the criteria for providing good acoustic comfort in the residential buildings, on the basis of which the conditions and necessary measures for providing sufficient sound insulation of the facade elements are discussed. Since, in addition to the noise from the environment, the acoustic comfort in apartments is also affected by the noise from adjacent apartments in the building, the link between the sound insulation performance of facades and audibility of the speech noise form adjacent apartments is also discussed.
Ključne besede: acoustic comfort, traffic noise, soun levels, sound insulation
Objavljeno v DiRROS: 19.01.2024; Ogledov: 594; Prenosov: 247
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5. Elucidating nucleation stages of transgranular stress corrosion cracking in austenitic stainless steel by in situ electrochemical and optical methodsSarmiento Klapper Helmuth, Bojan Zajec, Andreas Heyn, Andraž Legat, 2019, izvirni znanstveni članek Povzetek: The pitting and environmentally assisted cracking resistance of austenitic stainless steels (SS) is challenged in several industrial applications particularly those involving hot chloride-concentrated streams. Directional drilling used in the oil and gas exploration is one of these applications. Indeed, high strength CrMn-SS commonly used in drilling technology have a high tendency to fail by stress corrosion cracking (SCC) preceded by localized corrosion once subjected to highly chloride-concentrated drilling fluids at elevated temperatures. A comprehensive understanding regarding the mechanisms governing the transition from pitting into SCCis not currently available, though. Therefore, mechanistic aspects such as the effect of loading conditions on pit nucleation and repassivation as well as the synergistic effect between pit stabilization and the nucleation of a stress corrosion crack are of great practical significance. To investigate this an electrochemical-, optical- and mechanical- monitored SCC test was conducted on a CrMn-SS in an alkaline brine at elevated temperature. The transition from metastable to stable pitting and subsequently to SCC in this system was documented in-situ for the first time. Results supported H.S. Isaacs postulates regarding the interpretation of electrochemical signals and demonstrated that loading conditions affect pit nucleation and repassivation leading to a higher susceptibility of the material to pitting, which preceded SCC.
Ključne besede: pitting corrosion, stress corrosion cracking, monitoring, elektrochemical noise, austenitic stainless steel
Objavljeno v DiRROS: 23.11.2023; Ogledov: 675; Prenosov: 434
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6. Tribocorrosion susceptibility and mechanical characteristics of as-received and long-term in-vivo aged nickel-titanium and stainless-steel archwiresJasmina Primožič, Miha Hren, Uroš Mezeg, Andraž Legat, 2022, izvirni znanstveni članek Povzetek: To evaluate the effect of long-term in-vivo aging on orthodontic archwires, we aimed to assess the triboelectrochemical and mechanical characteristics of as-received and in-vivo aged nickel-titanium (NiTi) and stainless-steel (SS) orthodontic archwires. Four consecutive tribocorrosion cycles on six NiTi and six SS archwires, as-received and in-vivo aged, were performed on a reciprocal tribometer. Electrochemical noise and friction coefficient measurements, three-dimensional surface profiling, and hardness measurements were performed. Repassivation times of as-received archwires were longer than of the in-vivo aged; however, were shorter for NiTi. Friction coefficients were higher for NiTi than for SS archwires. Sudden major current drops concomitant with inverse potential shifts and friction coefficients’ fluctuations, were seen for as-received (last cycle) and in-vivo aged (last three cycles) NiTi archwires. More pronounced tribocorrosion damage was observed on in-vivo aged NiTi than on other archwires. Hardness was generally higher inside the wear track of archwires. Long-term in-vivo exposure decreases the corrosion susceptibility of archwires, more evidently for the NiTi ones. Sudden major fluctuations in electrochemical current, potential, and friction coefficient detected for NiTi archwires, might be related to localized residual parts of the oxide layer persisting due to increased surface roughness or to phase transformations of the alloy’s crystal structure.
Ključne besede: tribocorrosion, orthodontic archwires, electrochemical noise, open access
Objavljeno v DiRROS: 26.04.2023; Ogledov: 773; Prenosov: 361
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