976 research outputs found
The role of Hand2 in branchial arch and head-shoulder patterning
Comprehending gnathostome evolution requires insights into key cellular and molecular components of craniofacial and shoulder development.
For the work of this PhD, I made use of genetically modified mouse models to study aspects of mammalian head and shoulder morphogenesis by triple fluorescent RNA in situ hybridisation, immunohistochemistry and high resolution imaging.
First- I use a genetically defined sentinel cell population labelled by the Hand2-Cre transgene to establish the expansion of the distal-most branchial arch domain and correlate this by triple fluorescent RNA in situ hybridisation with the system controlling proximo-distal branchial arch patterning, the Dlx system. I find that the axis of the Dlx system does not correspond to the proximo-distal but an endodermal-ectodermal axis of the arch and rotates during development; the overall expansion of the arch is explicable by telescopic outgrowth along this new axis.
Second- I study the cellular and molecular characteristics of head/ shoulder skeleto-muscular connectivity and the contribution of limb lateral plate mesoderm to the shoulder girdle, which allows me to identify part of the manubrium sterni as the ‘lost’ mammalian procoracoid and to demonstrate that the interaction between lateral plate mesodermal subpopulations is non-random.
Third- I establish novel roles for Hand2 in lower incisor ameloblasts and in laminar dermal bone formation, suggesting a fundamental role for Hand2 in epithelial and mesenchymal cell layer arrangements. My detailed study of the murine frontal bone reveals that the establishment of an internal and an external layer initiates dermal bone formation; the latter shows intermediate molecular periosteal/ perichondrial characteristics and generates the intermediate layer by a Hand2-dependent invagination process.
For a comparative amphibian data set, I begin to establish genetic lineage labelling as technique in Xenopus tropicalis. I generate and test a Xenopus Hand2-Cre transgene and establish a stable generic Xenopus tropicalis Cre-reporter line by I-SceI mediated transgenesis
Measurement instruments for the early detection of unilateral cerebral palsy and evaluation of bimanual performance
Infants with early brain lesions are at risk of developing unilateral cerebral palsy (CP) and valid
and reliable measurement instruments for their early detection as well as evaluation of their
bimanual performance at later age are needed. Such identification allows for early family
support and intervention, while evaluation of hand function at later ages enables to tackle
primary challenges children and adolescents with unilateral CP face continuously while
performing everyday activities that require the use of both hands.
This thesis focuses on two measurement instruments, the Hand Assessment for Infants (HAI)
and the Children’s Hand-use Experience Questionnaire (CHEQ), as applied to infants at risk
of developing unilateral CP and children and adolescents with this condition, respectively. The
overall aim was to determine the validity of HAI scores to predict unilateral CP and the ability
of the CHEQ scores to capture perceptions of bimanual performance, both at a single point in
time and over time, in comparison to other assessments serving as external criteria.
The HAI is the first standardized test designed to evaluate both uni- and bimanual functions in
infants from 3-12 months of age at risk of developing unilateral CP. In combination with
neonatal magnetic resonance imaging, and considerations of gestational age and sex, the HAI
can predict unilateral CP in infants with asymmetric perinatal brain injury as young as 3.5-4.5
months of age. In addition, HAI scores exhibit very good to excellent overall accuracy in
predicting the development of unilateral CP in infants at risk at various time-points from 3.5-12
months of age.
Impaired hand function presents a continuous challenge when performing daily activities
requiring the use of both hands, especially as children with unilateral CP grow older. The
CHEQ, is an online patient-reported questionnaire of how children and adolescents with
unilateral hand impairment experience the use of the affected hand in connection with activities
requiring both hands. The AHA is a standardized test based on observation of the use of the
affected hand by children with unilateral CP during bimanual activities. The CHEQ and the
AHA were found to measure different constructs that are only related to a minor extent,
emphasizing the need to utilize both of these complementary tools to obtain a more complete
picture of the perceived and observed performance of bimanual activities by children and
adolescents with unilateral CP. The CHEQ scores captured some change in perceived bimanual
performance, with good accuracy for the scale feeling bothered, but only limited accuracy for
the scales grasp efficacy and time utilization. Consequently, CHEQ scores can be recommended
primarily for describing perceived bimanual performance
Towards Efficient Full Pose Omnidirectionality with Overactuated MAVs
Omnidirectional MAVs are a growing field, with demonstrated advantages for
aerial interaction and uninhibited observation. While systems with complete
pose omnidirectionality and high hover efficiency have been developed
independently, a robust system that combines the two has not been demonstrated
to date. This paper presents VoliroX: a novel omnidirectional vehicle that can
exert a wrench in any orientation while maintaining efficient flight
configurations. The system design is presented, and a 6 DOF geometric control
that is robust to singularities. Flight experiments further demonstrate and
verify its capabilities.Comment: 10 pages, 6 figures, ISER 2018 conference submissio
Why Wouldn’t You Tell? Telling donor-conceived children about their conception
Research studies show that while an increasing
number of parents of children conceived as a result
of donor conception procedures appear to be telling
- or planning to tell - their child about their conception
(see Golombok et al., 2004; Brewaeys et al.,
2005 for an overview), a large proportion of parents
choose not to do so. Since the overwhelming majority
of parents normally support truth-telling within
their families, the decision to conceal the nature of
the child’s conception - and deception to maintain
its concealment - requires explanation
Pose-Following with Dual Quaternions
This work focuses on pose-following, a variant of path-following in which the
goal is to steer the system's position and attitude along a path with a moving
frame attached to it. Full body motion control, while accounting for the
additional freedom to self-regulate the progress along the path, is an
appealing trade-off. Towards this end, we extend the well-established dual
quaternion-based pose-tracking method into a pose-following control law.
Specifically, we derive the equations of motion for the full pose error between
the geometric reference and the rigid body in the form of a dual quaternion and
dual twist. Subsequently, we formulate an almost globally asymptotically stable
control law. The global attractivity of the presented approach is validated in
a spatial example, while its benefits over pose-tracking are showcased through
a planar case-study.Comment: This paper has been accepted for publication at the IEEE Conference
on Decision and Control (CDC), 2023. Copyright @ IEE
Fermentative Gewinnung von Paramylon aus Euglena gracilis auf Nebenprodukten der Stärkeindustrie in einer Pilotanlage
[no abstract
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