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"Frank, Matthias"
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A supermassive black hole in an ultra-compact dwarf galaxy
Dynamical modelling of the ultra-compact dwarf galaxy M60-UCD1 reveals the presence of a supermassive black hole; this suggests the object is a stripped galaxy nucleus and implies the existence of supermassive black holes in many other ultra-compact dwarf galaxies.
Smallish galaxy hosts supermassive black hole
The object M60-UCD1 is the brightest ultracompact dwarf galaxy (UCD) currently known and — at about 200 million solar masses — one of the most massive. Anil Seth
et al
. have used adaptive optics spectra to resolve the kinematics of M60-UCD1. They detect a supermassive black hole of 21 million solar masses at its centre. M60-UCD1 is thus the lowest-mass system known to host a supermassive black hole. The authors suggest that it may once have been at the centre of a larger galaxy that was later tidally torn apart by a massive neighbour. Their analysis also shows that M60-UCD1's stellar mass is consistent with its luminosity, implying that many other ultra-compact dwarf galaxies may contain previously unrecognized supermassive black holes.
Ultra-compact dwarf galaxies are among the densest stellar systems in the Universe. These systems have masses of up to 2 × 10
8
solar masses, but half-light radii of just 3–50 parsecs
1
. Dynamical mass estimates show that many such dwarfs are more massive than expected from their luminosity
2
. It remains unclear whether these high dynamical mass estimates arise because of the presence of supermassive black holes or result from a non-standard stellar initial mass function that causes the average stellar mass to be higher than expected
3
,
4
. Here we report adaptive optics kinematic data of the ultra-compact dwarf galaxy M60-UCD1 that show a central velocity dispersion peak exceeding 100 kilometres per second and modest rotation. Dynamical modelling of these data reveals the presence of a supermassive black hole with a mass of 2.1 × 10
7
solar masses. This is 15 per cent of the object’s total mass. The high black hole mass and mass fraction suggest that M60-UCD1 is the stripped nucleus of a galaxy. Our analysis also shows that M60-UCD1’s stellar mass is consistent with its luminosity, implying a large population of previously unrecognized supermassive black holes in other ultra-compact dwarf galaxies
2
.
Journal Article
Effect of HRTFs and head motion on auditory-visual localization in real and virtual studio environments
When localizing sound sources in natural or virtual environments, multisensory integration that combines auditory and visual cues is often involved. This study aims to determine the effect of (non-)individual head-related transfer functions (HRTFs) on sound source localization in the presence of visual cues. Participants (N = 16) were seated in a hemispherical loudspeaker arrangement, and their task was to indicate the perceived direction of pink-noise bursts. The conditions included localization of real loudspeakers and virtualized loudspeakers based on binaural rendering with (non-)individual HRTFs. The horizontal spacing of the visible loudspeakers was 30 degrees or larger and the vertical spacing was varied between 30 degrees and 15 degrees, to focus on vertical discrimination. The results of a static localization experiment (no head movements during playback) demonstrated an increased rate of vertical local confusions using non-individual binaural room impulse responses (BRIRs) of the KU100 dummy head compared to individual BRIRs. Dynamic auditory-visual localization with non-individual HRTFs suffered from vertical uncertainty and bias in the frontal area, where local confusion rates were consistent with the static experiment. In conclusion, the horizontal localization mapping of dynamic binaural rendering with non-individual HRTFs was comparable to real loudspeaker reproduction, while the vertical mapping was significantly impaired.
Journal Article
Diffuse sound field synthesis: Towards practical source layouts
In an ideal isotropic diffuse sound field, uncorrelated plane waves arrive uniformly from all directions. Recent theoretical work has shown that uncorrelated sources arranged on a spherical surface can also be used to synthesize diffuse fields that exhibit a uniformly vanishing active sound intensity, albeit without position-independent isotropy. How the principles extend to finite-sized rectangular cuboid and discrete source layouts remains an open question. This study considers the multi-axial superellipsoid as a flexible parametric geometry for uncorrelated acoustic source distributions. By tuning its shape parameter p, the superellipsoid transitions from an ellipsoid p=2 to a rectangular cuboid p→∞, enabling a systematic analysis of active intensity using differential geometry, Gegenbauer expansion, and numerical simulations. Findings indicate that a superellipsoidal source layer of directionally uniform density requires to be driven by a non-uniform source variance, for which a generic solution is proposed. For the ellipsoid, the proposed variance is exact and emphasizes distant sources, while for the rectangular cuboid, it remains an approximation, but still effectively emphasizes sources near edges and corners. For discrete source layouts, zero active intensity can be approximately synthesized within a domain shrunk by a factor of N/(N+1) provided that (i) sources are arranged in uniform directions of a tight spherical 2N+1 design and sample the proposed variance, or (ii) a comparable number of sources with uniform variance is distributed in a minimum potential energy configuration.
Journal Article
Source Width of Frontal Phantom Sources: Perception, Measurement, and Modeling
Phantom sources are known to be perceived similar to real sound sources but with some differences. One of the differences is an increase of the perceived source width. This article discusses the perception, measurement, and modeling of source width for frontal phantom sources with different symmetrical arrangements of up to three active loudspeakers. The perceived source width is evaluated on the basis of a listening test. The test results are compared to technical measures that are applied in room acoustics: the inter-aural cross correlation coefficient (IACC) and the lateral energy fraction (LF). Adaptation of the latter measure makes it possible to predict the results by considering simultaneous sound incidence. Finally, a simple model is presented for the prediction of the perceived source width that does not require acoustic measurements as it is solely based on the loudspeaker directions and gains.
Journal Article
Structured reporting of B-mode, color Doppler, and CEUS in testicular tumor assessment: a reader study with urologist ratings
Purpose
Structured reporting (SR) offers standardized radiological documentation, enhancing clarity and reproducibility. However, its role in contrast-enhanced ultrasound (CEUS) for testicular tumors remains underexplored. This study evaluates urologist-perceived clarity, completeness, and clinical usefulness of SR compared to free-text reporting (FTR).
Methods and materials
In this retrospective, single-center study, 65 male patients with suspected testicular tumors underwent CEUS at LMU University Hospital. Reports were initially documented as FTRs by an experienced radiologist and later converted into SRs using Smart Reporting software. Four board-certified urologists independently assessed both formats using a structured questionnaire. Completeness, readability, trust, and impact on clinical decision-making were evaluated. Statistical analysis included McNemar’s test and the Wilcoxon signed-rank test, with α = 0.05.
Results
SRs significantly improved readability (97.3% vs. 10.0%,
p
< 0.001) and information extraction (98.8% vs. 91.9%,
p
< 0.001). However, completeness (56.9% vs. 60.8%,
p
= 0.427) and clinical decision support (85.7% vs. 84.9%,
p
= 0.152) were comparable. Trust in SRs was lower than in FTRs (4.92 vs. 5.22,
p
< 0.001), likely due to missing diagnostic parameters and retrospective SR generation.
Conclusions
SR was associated with improved reporting clarity and consistency but did not outperform FTR in completeness or clinical decision-making. Interdisciplinary collaboration in template development and the integration of classification systems could improve SR’s diagnostic value. Future prospective, multicenter studies should assess real-time SR implementation and its potential impact on reporting quality, communication, and outcome-based endpoints in prospective settings.
Clinical relevance/application
Structured reporting in multiparametric testicular ultrasound including CEUS improved perceived readability and facilitated information access for referring clinicians. However, SR showed no clear advantage over free-text reporting regarding completeness or clinical decision-making. The lower clinician trust in SR highlights the need for clinically tailored templates developed in interdisciplinary collaboration. The broader clinical value of SR in testicular imaging should be confirmed in prospective real-time studies incorporating outcome-based and workflow-related endpoints.
Journal Article
Metabolic Profiling of Volatile Organic Compounds (VOCs) Emitted by the Pathogens Francisella tularensis and Bacillus anthracis in Liquid Culture
We conducted comprehensive (untargeted) metabolic profiling of volatile organic compounds (VOCs) emitted in culture by bacterial taxa
Francisella tularensis (F. tularensis)
subspecies
novicida
and
Bacillus anthracis (B. anthracis)
Sterne, surrogates for potential bacterial bioterrorism agents, as well as selective measurements of VOCs from their fully virulent counterparts,
F. tularensis
subspecies
tularensis
strain SCHU S4 and
B. anthracis
Ames.
F. tularensis
and
B. anthracis
were grown in liquid broth for time periods that covered logarithmic growth, stationary, and decline phases. VOCs emitted over the course of the growth phases were collected from the headspace above the cultures using solid phase microextraction (SPME) and were analyzed using gas chromatography-mass spectrometry (GC-MS). We developed criteria for distinguishing VOCs originating from bacteria versus background VOCs (originating from growth media only controls or sampling devices). Analyses of collected VOCs revealed methyl ketones, alcohols, esters, carboxylic acids, and nitrogen- and sulfur-containing compounds that were present in the bacterial cultures and absent (or present at only low abundance) in control samples indicating that these compounds originated from the bacteria. Distinct VOC profiles where observed for
F. tularensis
when compared with
B. anthracis
while the observed profiles of each of the two
F. tularensis
and
B. anthracis
strains exhibited some similarities. Furthermore, the relative abundance of VOCs was influenced by bacterial growth phase. These data illustrate the potential for VOC profiles to distinguish pathogens at the genus and species-level and to discriminate bacterial growth phases. The determination of VOC profiles lays the groundwork for non-invasive probes of bacterial metabolism and offers prospects for detection of microbe-specific VOC biomarkers from two potential biowarfare agents.
Journal Article
Diffuse sound field synthesis: Ideal source layers
Can uncorrelated surrounding sound sources be used to generate extended diffuse sound fields? By definition, targets are a constant sound pressure level, a vanishing active sound intensity, and uncorrelated sound waves arriving isotropically from all directions. Are there ideal source layouts to synthesize a maximum diffuse sound field within? As methods, we employ numeric simulations and undertake a series of considerations based on uncorrelated source layouts at a finite radius. Statistically expected active sound intensity and sound energy density are insightful and highlight the relation of active sound intensity to potential theory. Correspondingly, both Gauß’ divergence and Newton’s spherical shell theorem apply, and they provide valuable insights. In a circular layout, uncorrelated elementary point-source fields decaying by 1/√r ideally compose an extended sound field of vanishing active sound intensity; in spherical layouts this is the case with a 1/r decay. None of the layouts synthesizes a perfectly constant sound energy density inside. Theory and simulation offer a broad basis for understanding the synthesis of diffuse sound fields with uncorrelated sources in the free sound field.
Journal Article
Binaural Rendering with Measured Room Responses: First-Order Ambisonic Microphone vs. Dummy Head
To improve the limited degree of immersion of static binaural rendering for headphones, an increased measurement effort to obtain multiple-orientation binaural room impulse responses (MOBRIRs) is reasonable and enables dynamic variable-orientation rendering. We investigate the perceptual characteristics of dynamic rendering from MOBRIRs and test for the required angular resolution. Our first listening experiment shows that a resolution between 15 ∘ and 30 ∘ is sufficient to accomplish binaural rendering of high quality, regarding timbre, spatial mapping, and continuity. A more versatile alternative considers the separation of the room-dependent (RIR) from the listener-dependent head-related (HRIR) parts, and an efficient implementation thereof involves the measurement of a first-order Ambisonic RIR (ARIR) with a tetrahedral microphone. A resolution-enhanced ARIR can be obtained by an Ambisonic spatial decomposition method (ASDM) utilizing instantaneous direction of arrival estimation. ASDM permits dynamic rendering in higher-order Ambisonics, with the flexibility to render either using dummy-head or individualized HRIRs. Our comparative second listening experiment shows that 5th-order ASDM outperforms the MOBRIR rendering with resolutions coarser than 30 ∘ for all tested perceptual aspects. Both listening experiments are based on BRIRs and ARIRs measured in a studio environment.
Journal Article
Chemical Profiling of Volatile Organic Compounds in the Headspace of Algal Cultures as Early Biomarkers of Algal Pond Crashes
Algae ponds used in industrial biomass production are susceptible to pathogen or grazer infestation, resulting in pond crashes with high economic costs. Current methods to monitor and mitigate unhealthy ponds are hindered by a lack of early indicators that precede culture crash. We used solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) to identify volatiles emitted from healthy and rotifer infested cultures of
Microchloropsis salina
. After 48 hours of algal growth, marine rotifers,
Brachionus plicatilis
, were added to the algae cultures and volatile organic compounds (VOC) were sampled from the headspace using SPME fibers. A GC-MS approach was used in an untargeted analysis of VOCs, followed by preliminary identification. The addition of
B
.
plicatilis
to healthy cultures of
M
.
salina
resulted in decreased algal cell numbers, relative to uninfected controls, and generated
trans
-β-ionone and β-cyclocitral, which were attributed to carotenoid degradation. The abundances of the carotenoid-derived VOCs increased with rotifer consumption of algae. Our results indicate that specific VOCs released by infected algae cultures may be early indicators for impending pond crashes, providing a useful tool to monitor algal biomass production and pond crash prevention.
Journal Article