159 research outputs found
Enlargeability and index theory
Let M be a closed enlargeable spin manifold. We show non-triviality of the
universal index obstruction in the K-theory of the maximal -algebra of the
fundamental group of M. Our proof is independent from the injectivity of the
Baum-Connes assembly map for the fundamental group of M and relies on the
construction of a certain infinite dimensional flat vector bundle out of a
sequence of finite dimensional vector bundles on M whose curvatures tend to
zero.
Besides the well known fact that M does not carry a metric with positive
scalar curvature, our results imply that the classifying map
sends the fundamental class of M to a nontrivial homology class in H_n(B
\pi_1(M) ; \Q). This answers a question of Burghelea (1983).Comment: 32 pages, final version accepted for publication, added relation to
Gromov's 1-systole, typos corrected; to appear in Journal of Differential
Geometr
The space of metrics of positive scalar curvature
We study the topology of the space of positive scalar curvature metrics on
high dimensional spheres and other spin manifolds. Our main result provides
elements of infinite order in higher homotopy and homology groups of these
spaces, which, in contrast to previous approaches, are of infinite order and
survive in the (observer) moduli space of such metrics.
Along the way we construct smooth fiber bundles over spheres whose total
spaces have non-vanishing A-hat-genera, thus establishing the
non-multiplicativity of the A-hat-genus in fibre bundles with simply connected
base.Comment: 24 pages, v2: minor additions and corrections, based in particular on
comments of referees, v3: minor corrections, final version, to appear in
Publ.Math. IHE
The strong Novikov conjecture for low degree cohomology
We show that for each discrete group G, the rational assembly map
K_*(BG) \otimes Q \to K_*(C*_{max} G) \otimes \Q is injective on classes dual
to the subring generated by cohomology classes of degree at most 2 (identifying
rational K-homology and homology via the Chern character). Our result implies
homotopy invariance of higher signatures associated to these cohomology
classes. This consequence was first established by Connes-Gromov-Moscovici and
Mathai.
Our approach is based on the construction of flat twisting bundles out of
sequences of almost flat bundles as first described in our previous work. In
contrast to the argument of Mathai, our approach is independent of (and indeed
gives a new proof of) the result of Hilsum-Skandalis on the homotopy invariance
of the index of the signature operator twisted with bundles of small curvature.Comment: 11 page
Thunder and lightning-a report on firework-associated acoustic trauma at New Year 2021/2022
Background: This cross-sectional study aimed to assess the frequency and type of
firework-associated acoustic trauma occurring in Germany on New Year’s Eve 2021,
despite the ban on firework sales due to the COVID-19 pandemic.
Materials and methods: The survey period lasted 7 days, from 28 December 2021
to 03 January 2022. A questionnaire inquired date, type and treatment of trauma,
sex, and age of the patient, and whether the trauma occurred when lighting or
watching fireworks. Hearing impairment was classified according to the World Health
Organization (WHO grades 0 to 4), and concomitant tinnitus, vertigo, or other injuries
were recorded. The questionnaire was sent to the otorhinolaryngology departments of
171 hospitals in Germany.
Results: Of 37 otorhinolaryngology departments, 16 reported no and 21 reported
50 patients with firework-associated acoustic trauma. Mean age was 29 ± 16 years and
41 of 50 patients were males. Of these 50 patients, 22 presented without and 28 with
hearing loss, 32 reported tinnitus and 3 vertigo; 20 patients were injured when lighting
fireworks and 30 when watching. Hearing impairment was classified as 14 × WHO
grade 0, 5 × WHO grade 1, 4 × WHO grade 2, 2 × WHO grade 3, and 3 × WHO grade 4.
Inpatient treatment was received by 8 patients and 11 suffered from concomitant burn
injuries.
Conclusion: Despite the sales ban, some firework-associated acoustic traumas occurred
at New Year 2021/2022 in Germany. Some instances led to hospitalization, but an even
higher number of unreported cases can be assumed. This study can serve as a baseline
for further annual surveys to raise the awareness of the danger of seemingly harmless
fireworks for the individual
Self-Perception Versus Objective Driving Behavior: Subject Study of Lateral Vehicle Guidance
Advancements in technology are steering attention toward creating comfortable
and acceptable driving characteristics in autonomous vehicles. Ensuring a safe
and comfortable ride experience is vital for the widespread adoption of
autonomous vehicles, as mismatches in driving styles between humans and
autonomous systems can impact passenger confidence. Current driving functions
have fixed parameters, and there is no universally agreed-upon driving style
for autonomous vehicles. Integrating driving style preferences into automated
vehicles may enhance acceptance and reduce uncertainty, expediting their
adoption. A controlled vehicle study (N = 62) was conducted with a variety of
German participants to identify the individual lateral driving behavior of
human drivers, specifically emphasizing rural roads. We introduce novel
indicators for assessing stationary and transient curve negotiation, directly
applicable in developing personalized lateral driving functions. To assess the
predictability of these indicators using self-reports, we introduce the
MDSI-DE, the German version of the Multidimensional Driving Style Inventory.
The correlation analysis between MDSI factor scores and proposed indicators
showed modest but significant associations, primarily with acceleration and
jerk statistics while the in-depth lateral driving behavior turned out to be
highly driver-heterogeneous. The dataset including the anonymized
socio-demographics and questionnaire responses, the raw vehicle measurements
including labels, and the derived driving behavior indicators are publicly
available at
https://www.kaggle.com/datasets/jhaselberger/spodb-subject-study-of-lateral-vehicle-guidance.Comment: 33 pages, 6 figures, under revie
Выбор способа хранения результатов научных экспериментов в базе данных на примере MS SQL Server
This article describes the use of MS SQL server as file storage to store files of scientific researches. The article describes the advantages and disadvantages of different methods of storing files to MS SQL Server
Homotopy groups of the moduli space of metrics of positive scalar curvature
We show by explicit examples that in many degrees in a stable range the homotopy groups of the moduli spaces of Riemannian metrics of positive scalar curvature on closed smooth manifolds can be non-trivial. This is achieved by further developing and then applying a family version of the surgery construction of Gromov–Lawson to certain nonlinear smooth sphere bundles constructed by Hatcher
Neural Crest Stem Cells in Juvenile Angiofibromas
The etiology of juvenile angiofibroma (JA) has been a controversial topic for more than
160 years. Numerous theories have been proposed to explain this rare benign neoplasm arising
predominately in adolescent males, focusing mainly on either the vascular or fibrous component. To
assess our hypothesis of JA’s being a malformation arising from neural crest cells/remnants of the
first branchial arch plexus, we performed immunohistochemical analyses of neural crest stem cells
(NCSC) and epithelial-mesenchymal transition (EMT) candidates. Immunoexpression of the NCSC
marker CD271p75 was observed in all investigated JA’s (n = 22), mainly around the pathological
vessels. Close to CD271p75-positive cells, high MMP3-staining was also observed. Additionally, from
one JA with sufficient material, RT-qPCR identified differences in the expression pattern of PDGFRβ,
MMP2 and MMP3 in MACS®-separated CD271p75positive vs. CD271p75 negative cell fractions.
Our results, together with the consideration of the literature, provide evidence that JA’s represent
a malformation within the first branchial arch artery/plexus remnants deriving from NCSC. This
theory would explain the typical site of tumor origin as well as the characteristic tumor blood supply,
whereas the process of EMT provides an explanation for the vascular and fibrous tumor component
Masked Discriminators for Content-Consistent Unpaired Image-to-Image Translation
A common goal of unpaired image-to-image translation is to preserve content
consistency between source images and translated images while mimicking the
style of the target domain. Due to biases between the datasets of both domains,
many methods suffer from inconsistencies caused by the translation process.
Most approaches introduced to mitigate these inconsistencies do not constrain
the discriminator, leading to an even more ill-posed training setup. Moreover,
none of these approaches is designed for larger crop sizes. In this work, we
show that masking the inputs of a global discriminator for both domains with a
content-based mask is sufficient to reduce content inconsistencies
significantly. However, this strategy leads to artifacts that can be traced
back to the masking process. To reduce these artifacts, we introduce a local
discriminator that operates on pairs of small crops selected with a similarity
sampling strategy. Furthermore, we apply this sampling strategy to sample
global input crops from the source and target dataset. In addition, we propose
feature-attentive denormalization to selectively incorporate content-based
statistics into the generator stream. In our experiments, we show that our
method achieves state-of-the-art performance in photorealistic sim-to-real
translation and weather translation and also performs well in day-to-night
translation. Additionally, we propose the cKVD metric, which builds on the sKVD
metric and enables the examination of translation quality at the class or
category level.Comment: 24 pages, 22 figures, under revie
Ausläufe in der Schweinehaltung - Planungsempfehlungen, Bewirtschaftung und Kosten
Betriebsleiter und Berater erhalten umfassende Informationen zur Planung, zum Bau und zur Bewirtschaftung von Ausläufen in der Schweinehaltung mit Angaben zum Investitions- und Arbeitszeitbedarf
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