2,185 research outputs found
Ecological restoration and dike relocation on the river Elbe, Germany
Floodplain restoration has been successfully initiated on a 420 hectare area on the Middle Elbe River in the German Federal State of Brandenburg. Within a federally funded “Large Scale Conservation Project”, grassland dominated agricultural landscape was converted into a natural floodplain area between 2002 and 2011. The relocation of a dike was essential to re-establish natural flooding conditions as a prerequisite for the rehabilitation of floodplain specific animal and plant communities. At the same time the dike relocation proved to be of great benefit to flood protection, restoring retention capacity, broadening a narrow of dikes and eliminating a hydraulic bottleneck situation in a dangerous river bent. Alluvial forest was initiated by scattered plantations of autochthonous woody species leaving much of the area subject to spontaneous succession. Excavation of alluvial water bodies and maintenance of a extensively grazed horse pasture area add to a diversity of landscape elements with the aim to restore a broad range of floodplain habitats with a high level of biodiversity. The initiated landscape change quickly set off successional processes, mostly related to the altered hydrological conditions among which extended periods of inundation are of major importance. Severe changes in vegetation communities, birdlife and fish communities could be assessed by evaluation investigations and prove the success of the restoration project. Research activities and public environmental education continue to play an important role in the management of the project
Does growing up in a high crime neighborhood affect youth criminal behavior?
This paper investigates the effect of early exposure to neighborhood crime on subsequent criminal behavior of youth exploiting a unique natural experiment between 1986 and 1998 when refugee immigrants to Denmark were assigned to neighborhoods quasi-randomly. We find strong evidence that the share of young people convicted for crimes, in particular violent crimes, in the neighborhood increases convictions of male assignees later in life. No such effects are found for other measures of neighborhood crime including the rate of committed crimes. Our findings suggest social interaction as a key channel through which neighborhood crime is linked to individual criminal behavior
Balanced Truncation of k-Positive Systems
This paper considers balanced truncation of discrete-time Hankel -positive systems, characterized by Hankel matrices whose minors up to order k are nonnegative. Our main result shows that if the truncated system has order or less, then it is Hankel totally positive (-positive), meaning that it is a sum of first order lags. This result can be understood as a bridge between two known results: the property that the first-order truncation of a positive system is positive (), and the property that balanced truncation preserves state-space symmetry. It provides a broad class of systems where balanced truncation is guaranteed to result in a minimal internally positive system.T
We would like to thank the anonymous reviewers for their
outstanding support. The research leading to these results was
completed while the first author was a postdoctoral research
associate at the University of Cambridge. The research has
received funding from the European Research Council under
the Advanced ERC Grant Agreement Switchlet n.67
Potential of the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor for the monitoring of terrestrial chlorophyll fluorescence
Global monitoring of sun-induced chlorophyll fluorescence (SIF) is improving our knowledge about the photosynthetic functioning of terrestrial ecosystems. The feasibility of SIF retrievals from spaceborne atmospheric spectrometers has been demonstrated by a number of studies in the last years. In this work, we investigate the potential of the upcoming TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite mission for SIF retrieval. TROPOMI will sample the 675–775 nm spectral window with a spectral resolution of 0.5 nm and a pixel size of 7 km × 7 km. We use an extensive set of simulated TROPOMI data in order to assess the uncertainty of single SIF retrievals and subsequent spatio-temporal composites. Our results illustrate the enormous improvement in SIF monitoring achievable with TROPOMI with respect to comparable spectrometers currently in-flight, such as the Global Ozone Monitoring Experiment-2 (GOME-2) instrument. We find that TROPOMI can reduce global uncertainties in SIF mapping by more than a factor of 2 with respect to GOME-2, which comes together with an approximately 5-fold improvement in spatial sampling. Finally, we discuss the potential of TROPOMI to map other important vegetation parameters at a global scale with moderate spatial resolution and short revisit time. Those include leaf photosynthetic pigments and proxies for canopy structure, which will complement SIF retrievals for a self-contained description of vegetation condition and functioning
Finite automata with advice tapes
We define a model of advised computation by finite automata where the advice
is provided on a separate tape. We consider several variants of the model where
the advice is deterministic or randomized, the input tape head is allowed
real-time, one-way, or two-way access, and the automaton is classical or
quantum. We prove several separation results among these variants, demonstrate
an infinite hierarchy of language classes recognized by automata with
increasing advice lengths, and establish the relationships between this and the
previously studied ways of providing advice to finite automata.Comment: Corrected typo
Towards Model Checking Executable UML Specifications in mCRL2
We describe a translation of a subset of executable UML (xUML) into the process algebraic specification language mCRL2. This subset includes class diagrams with class generalisations, and state machines with signal and change events. The choice of these xUML constructs is dictated by their use in the modelling of railway interlocking systems. The long-term goal is to verify safety properties of interlockings modelled in xUML using the mCRL2 and LTSmin toolsets. Initial verification of an interlocking toy example demonstrates that the safety properties of model instances depend crucially on the run-to-completion assumptions
Opportunistic hip fracture risk prediction in Men from X-ray: Findings from the Osteoporosis in Men (MrOS) Study
Osteoporosis is a common disease that increases fracture risk. Hip fractures,
especially in elderly people, lead to increased morbidity, decreased quality of
life and increased mortality. Being a silent disease before fracture,
osteoporosis often remains undiagnosed and untreated. Areal bone mineral
density (aBMD) assessed by dual-energy X-ray absorptiometry (DXA) is the
gold-standard method for osteoporosis diagnosis and hence also for future
fracture prediction (prognostic). However, the required special equipment is
not broadly available everywhere, in particular not to patients in developing
countries. We propose a deep learning classification model (FORM) that can
directly predict hip fracture risk from either plain radiographs (X-ray) or 2D
projection images of computed tomography (CT) data. Our method is fully
automated and therefore well suited for opportunistic screening settings,
identifying high risk patients in a broader population without additional
screening. FORM was trained and evaluated on X-rays and CT projections from the
Osteoporosis in Men (MrOS) study. 3108 X-rays (89 incident hip fractures) or
2150 CTs (80 incident hip fractures) with a 80/20 split were used. We show that
FORM can correctly predict the 10-year hip fracture risk with a validation AUC
of 81.44 +- 3.11% / 81.04 +- 5.54% (mean +- STD) including additional
information like age, BMI, fall history and health background across a 5-fold
cross validation on the X-ray and CT cohort, respectively. Our approach
significantly (p < 0.01) outperforms previous methods like Cox
Proportional-Hazards Model and \frax with 70.19 +- 6.58 and 74.72 +- 7.21
respectively on the X-ray cohort. Our model outperform on both cohorts hip aBMD
based predictions. We are confident that FORM can contribute on improving
osteoporosis diagnosis at an early stage.Comment: Accepted at MICCAI 2022 Workshop (PRIME
The Impact of Olfactory Disorders in the United Kingdom
Olfactory disorders are believed to affect 5% of the general population and have been shown to bear significant psychosocial consequences to sufferers. Although more common than blindness and profound deafness in the United Kingdom, the impact of these disorders has not been assessed to date and the plight of British patients has yet to be quantified. In 2012, a patient support organization, Fifth Sense, was founded to provide information and support to sufferers of chemosensory disorders. Following a recent members conference, a survey of the membership was conducted anonymously using a series of questions based on an existing olfactory disorders questionnaire. From 496 respondents, this has demonstrated high rates of depression (43%) and anxiety (45%), impairment of eating experience (92%), isolation (57%), and relationship difficulties (54%). Women appear to have significantly more issues than men in terms of social and domestic dysfunction relating to olfactory loss (P = 0.01). Qualitative disorders also affected more than 1 in 5 members with parosmia reported in 19% and phantosmia in 24%. This paper discusses the details of the British story of anosmia and other related disorders as depicted by those most affected
Processing Succinct Matrices and Vectors
We study the complexity of algorithmic problems for matrices that are
represented by multi-terminal decision diagrams (MTDD). These are a variant of
ordered decision diagrams, where the terminal nodes are labeled with arbitrary
elements of a semiring (instead of 0 and 1). A simple example shows that the
product of two MTDD-represented matrices cannot be represented by an MTDD of
polynomial size. To overcome this deficiency, we extended MTDDs to MTDD_+ by
allowing componentwise symbolic addition of variables (of the same dimension)
in rules. It is shown that accessing an entry, equality checking, matrix
multiplication, and other basic matrix operations can be solved in polynomial
time for MTDD_+-represented matrices. On the other hand, testing whether the
determinant of a MTDD-represented matrix vanishes PSPACE$-complete, and the
same problem is NP-complete for MTDD_+-represented diagonal matrices. Computing
a specific entry in a product of MTDD-represented matrices is #P-complete.Comment: An extended abstract of this paper will appear in the Proceedings of
CSR 201
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