It has been proposed that the P3b component of event-related potentials (ERPs) reflects linking of responses to target stimuli. This proposal was tested by disconnecting the temporal link between ...target stimuli and responses, and by applying residue iteration decomposition (RIDE) for separating the ERP components into stimulus-locked, response-locked, and “intermediate” clusters. Left or right keys had to be pressed in response to frequent (80%) and rare (20%) target letters, but responses had to wait for “go” signals (appearing in 90% of trials). Between blocks, stimulus-onset asynchronies (SOAs) from targets to go-signals varied from 0ms to 800ms. Rare targets with their rare responses were expected to evoke large P3bs (“oddball effect”). If related to stimulus processing only, this effect will be equally large across all SOAs and will be modeled by RIDE's stimulus-cluster. If related to response initiation only, the oddball effect will be evoked by go-signals rather than by targets and will be modeled by RIDE's response-cluster. If indicating integration of rare stimuli with their rare responses, the oddball effect will be evoked by targets but will be reduced and stretched in time across SOAs and will be modeled by RIDE's intermediate cluster. RIDE analysis confirmed this latter view, for the most part. SOA effects matched best, though not perfectly, predictions made by the stimulus–response-link view. These results call for a refined account of the oddball effect on P3b in terms of stimulus–response coupling.
Display omitted
•We used the oddball effect: P3b is increased by infrequent events.•Does this effect reflect infrequency of stimuli (S), responses (R), or S–R links?•The oddball effect is stretched and even gets inherited by delayed go signals.•Its bulk is assigned by RIDE to the S- and R-independent “intermediate” cluster•P3b may consist of S- and R-related parts, with both parts reflecting S–R linking.
End artefacts play a major role in uniaxial compression tests with cancellous bone specimens. They lead to misinterpretation of mechanical parameters of bones due to uncontrolled introduction of ...bending moments into the free ends of trabeculae. This work aims to simplify current methods preventing end-artefacts and furthermore to investigate the influence of end artefacts on plateau stress.
176 cylindrical cancellous bone specimens were taken from human femoral condyles and tested in uniaxial compression. The specimens were divided into 2 groups (direct, end-cap) and compressive modulus, maximum stress, plateau stress, energy absorbtion as well as apparent density were evaluated. Density values are from separate specimens which are immediately adjacent to the mechanical specimen.
All mechanical parameters were significantly higher in the end-cap specimens than in the direct ones by about 30 – 40 %, thus reaching similar differences as the previous studies. Greatest differences between groups were determined for compressive modulus (45 %) and plateau stress (35 %). Energy absorbtion can be explained with great accuracy by plateau stress (P < 0.001; R2 = 0.95). Among all parameters plateau stress can be best explained by apparent density using an exponential function (P < 0.001; R2 = 0.38).
The end-cap method used here to prevent end artefacts showed variations consistent with the literature when compared to the direct method. Additionally it was shown that the way in which the force is applied to the specimen has a major influence on the failure progression behavior, which was characterized using the plateau stress.
•Compressive testing of human femoral condylar bone.•Verification of a simplified setup preventing end-artefacts during compression test.•Plateau stress is most sensitive to force initiation method.
Abstract
Data collection of mechanical parameters from compressive tests play a fundamental role in FE modelling of bone tissues or the developing and designing of bone implants, especially referring ...to osteoporosis or other forms of bone loss. A total of 43 cylindrical samples (Ø8 × 16 mm) were taken from 43 freshly frozen proximal femora using a tenon cutter. All femora underwent BMD measurement and additionally apparent- and relative- and bulk density (ρ
app
, ρ
r
, ρ
b
) were determined using samples bordering the compressive specimen on the proximal and distal regions. All samples were classified as "normal", "osteopenia" and "osteoporosis" based on the DEXA measurements. Distal apparent density was most suitable for predicting bone strength and BMD. One novel aspect is the examination of the plateau stress as it describes the stress at which the failure of spongious bone progresses. No significant differences in mechanical properties (compressive modulus E; compressive stress σ
max
and plateau stress σ
p
) were found between osteopenic and osteoporotic bone. The results suggest that already in the case of a known osteopenia, actions should be taken as they are applied in the case of osteoporosis A review of the literature regarding extraction and testing methods illustrates the urgent need for standardized biomechanical compressive material testing.
Replicating the mechanical behavior of human bones, especially cancellous bone tissue, is challenging. Typically, conventional bone models primarily consist of polyurethane foam surrounded by a solid ...shell. Although nearly isotropic foam components have mechanical properties similar to cancellous bone, they do not represent the anisotropy and inhomogeneity of bone architecture. To consider the architecture of bone, models were developed whose core was additively manufactured based on CT data. This core was subsequently coated with glass fiber composite. Specimens consisting of a gyroid-structure were fabricated using fused filament fabrication (FFF) techniques from different materials and various filler levels. Subsequent compression tests showed good accordance between the mechanical behavior of the printed specimens and human bone. The unidirectional fiberglass composite showed higher strength and stiffness than human cortical bone in 3-point bending tests, with comparable material behaviors being observed. During biomechanical investigation of the entire assembly, femoral prosthetic stems were inserted into both artificial and human bones under controlled conditions, while recording occurring forces and strains. All of the artificial prototypes, made of different materials, showed analogous behavior to human bone. In conclusion, it was shown that low-cost FFF technique can be used to generate valid bone models and selectively modify their properties by changing the infill.
Punzi-loss Abudinén, F.; Bertemes, M.; Bilokin, S. ...
The European physical journal. C, Particles and fields,
2022/2, Letnik:
82, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present the novel implementation of a non-differentiable metric approximation and a corresponding loss-scheduling aimed at the search for new particles of unknown mass in high energy physics ...experiments. We call the loss-scheduling, based on the minimisation of a figure-of-merit related function typical of particle physics, a Punzi-loss function, and the neural network that utilises this loss function a Punzi-net. We show that the Punzi-net outperforms standard multivariate analysis techniques and generalises well to mass hypotheses for which it was not trained. This is achieved by training a single classifier that provides a coherent and optimal classification of all signal hypotheses over the whole search space. Our result constitutes a complementary approach to fully differentiable analyses in particle physics. We implemented this work using PyTorch and provide users full access to a public repository containing all the codes and a training example.
Punzi-loss Abudinén, F; Bertemes, M; Bilokin, S ...
The European physical journal. C, Particles and fields,
02/2022, Letnik:
82, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present the novel implementation of a non-differentiable metric approximation and a corresponding loss-scheduling aimed at the search for new particles of unknown mass in high energy physics ...experiments. We call the loss-scheduling, based on the minimisation of a figure-of-merit related function typical of particle physics, a Punzi-loss function, and the neural network that utilises this loss function a Punzi-net. We show that the Punzi-net outperforms standard multivariate analysis techniques and generalises well to mass hypotheses for which it was not trained. This is achieved by training a single classifier that provides a coherent and optimal classification of all signal hypotheses over the whole search space. Our result constitutes a complementary approach to fully differentiable analyses in particle physics. We implemented this work using PyTorch and provide users full access to a public repository containing all the codes and a training example.
In the original publication of the article, two of the author names “L. A. Schröder, F. Metzner” and email address of the authors “J. Devine, J. Moon, A. C. Haller” were missed out. The correct ...author group with affiliations are provided in this correction.
The P3b component of ERPs has been proposed to reflect decisions or, alternatively, activation of stimulus‐response links or, alternatively, to depend on stimulus processing only. These three views ...make different predictions about how difficulty of response selection will affect the oddball effect. In three experiments, frequent and rare targets were accompanied by ancillary stimuli. Large oddball‐P3bs, evoked by rare targets, were greatly reduced when responses had to be selected by combining information from targets and ancillary stimuli. Difficult response selection with rare targets was also reflected by a large frontocentral negativity, which could be separated from P3b when intervals were varied between targets and ancillary stimuli, and, therefore, did not cause P3b reduction. It is concluded that the usual increase of P3b with rare task‐relevant targets depends on the existence of readily available stimulus‐response links.
Families with migrant backgrounds (MB) are exposed to several psychosocial risk factors that increase the likelihood of impaired child development, in particular.
We investigated whether families ...with MB differ from families without MB regarding their psychosocial stressors in the period of pregnancy and birth.
As part of a social early warning system in an obstetrics clinic in Germany n=502 families with MB were compared with n=349 families without MB with respect to the degree of stress and stress factors on the basis of an initial screening of risk factors for child maltreatment by a midwife or physician and a subsequent structured clearing interview by social education workers during the mothers' inpatient hospitalisation.
For families without MB, a significantly higher total score was found in the risk screening (M=3,9 points vs. M=2,9 points) in comparison to families with MB. While families with MB compared to families without MB were faced more frequently by social stressors, e. g., financial problems or a difficult housing situation (81 vs. 37%), they were less frequently impacted by mental strain (27 vs. 48%), young fathers (2 vs. 10%) and maternal psychiatric diseases (3 vs. 17%), according to the risk screening. Socio-economic determinants such as social inclusion and living environment were found to be important factors influencing the psychosocial stress level of families.
Explanations and implications for research and practice are discussed.
Representatives of the statutory health insurance (n=46) and policy makers at the local, federal and state level (n=136) were interviewed in 2 nationwide online surveys about the significance and ...degree of implementation of prevention. The group comparison between the decision-makers shows significant differences in terms of attitudes towards health prevention. The political leaders are demanding an improvement of the GKV-benefit package and the obstacles require the cooperation of urgent attention.
PDF
