164 research outputs found
Land Administration Systems Development Trends – A Case Study
Land management is aimed at generating optimal social, economic and environmental benefits while promoting sustainable development principles. An essential element of this process is the knowledge of the geospatial situation to support public decision-making at different levels: local, regional, national and global. Hence, there is a need for rapid access to complete and updated information about the physical characteristics of a property, rights, restrictions, responsibilities and interrelations. This information is provided by land administration systems (LAS). LAS are built and maintained by governments. The core of LAS is a multi-purpose cadastral system integrated with other spatial information systems and public registers. In this paper, the authors present the functional architecture and the assumptions of land administration systems built in Poland and Germany. The analysis results show the specificity of the systems' design in relation to socio-economic condition
Emergence of rigid Polycrystals from atomistic Systems with Heitmann-Radin sticky disk energy
We investigate the emergence of rigid polycrystalline structures from
atomistic particle systems. The atomic interaction is governed by a suitably
normalized pair interaction energy, where the `sticky disk' interaction
potential models the atoms as hard spheres that interact when they are
tangential. The discrete energy is frame invariant and no underlying reference
lattice on the atomistic configurations is assumed. By means of
-convergence, we characterize the asymptotic behavior of configurations
with finite surface energy scaling in the infinite particle limit. The
effective continuum theory is described in terms of a piecewise constant field
delineating the local orientation and micro-translation of the configuration.
The limiting energy is local and concentrated on the grain boundaries, i.e., on
the boundaries of the zones where the underlying microscopic configuration has
constant parameters. The corresponding surface energy density depends on the
relative orientation of the two grains, their microscopic translation misfit,
and the normal to the interface. We further provide a fine analysis of the
surface energies at grain boundaries both for vacuum-solid and solid-solid
phase transitions. The latter relies fundamentally on a structure result for
grain boundaries showing that due to the extremely brittle setup interpolating
boundary layers near cracks are energetically not favorable
Development of a model for the separation characteristics of a deflector wheel classifier including particle collision and rebound behavior
Deflector wheel classifiers are widespread in industry for the separation of powders into fine and coarse powders. Even though this separation process has been known for quite some time, it is not yet fully understood, and existing models fail to precisely predict the separation characteristics. Due to the high throughput of deflector wheel classifiers, it is greatly beneficial to estimate the separation characteristics before the experiment. Here, the developed model critically examines the usual assumptions, such as ideal airflow, neglection of particle–wall and particle–particle interactions, or spherically-shaped particles. First, the investigation of the air flow using a Particle Image Velocimetry (PIV) system showed significant differences to the assumed ideal flow field, then particle sphericity and its influence on the interaction between the particles and the paddles of the deflector wheel was investigated and compared with particle rebound behavior on a static wall. Surprisingly, comminuted glass behaves similarly to comminuted limestone in multiple aspects and not like glass beads. To determine the number of particle–particle collisions, Discrete Element Method (DEM) simulations were performed. The aforementioned aspects found application in the model and the separation behavior was well-estimated
Chemically detaching hBN crystals grown at atmospheric pressure and high temperature for high-performance graphene devices
In this work, we report on the growth of hexagonal boron nitride (hBN)
crystals from an iron flux at atmospheric pressure and high temperature and
demonstrate that (i) the entire sheet of hBN crystals can be detached from the
metal in a single step using hydrochloric acid and that (ii) these hBN crystals
allow the fabrication of high carrier mobility graphene devices. By combining
spatially-resolved confocal Raman spectroscopy and electrical transport
measurements, we confirm the excellent quality of these crystals for
high-performance hBN-graphene-based van der Waals heterostructures. The full
width at half maximum of the graphene Raman 2D peak is as low as 16 cm,
and the room temperature charge carrier mobilitiy is around 80000 cm/(Vs)
at a carrier density 110cm. This is fully comparable
with devices of similar dimensions fabricated using crystalline hBN synthesized
by the high pressure and high temperature method. Finally, we show that for
exfoliated high-quality hBN flakes with a thickness between 20 nm and 40 nm the
line width of the hBN Raman peak, in contrast to the graphene 2D line width, is
not useful for benchmarking hBN in high mobility graphene devices.Comment: 7 pages, 4 figure
Nano-structured transmissive spectral filter matrix based on guided-mode resonances
Background: In this work, a nanostructured guided-mode resonance filter matrix with high transmission efficiency and narrow bandwidth is demonstrated. The developed nano-filter arrays have various usages, e.g., combined with the CMOS image sensors to realize compact spectrometers for biomedical sensing applications. Methods: In order to optimize the filter performance, the spectral responses of filters with different structural parameters are carefully studied based on the variable-controlling method. A quality factor is carried out for quantitative characterization. Results: In this case, a high fill factor of 0.9 can strongly suppress sidebands, while buffer layer thickness can be adjusted to mainly control the bandwidth. The transmission peaks shift from 386 nm to 1060 nm with good linearity when periods vary from 220 nm to 720 nm. The incident angle dependence is simulated to be ~ 1.1 nm/degree in ±30° range. The filters are then fabricated and characterized. The results obtained from both simulations and experiments agree well, where the filters with the period of 352 nm exhibit simulated and measured transmission peaks of 564 nm and 536 nm, the FWHM of 13 nm and 17 nm, respectively. In terms of metal material, besides aluminum, silver is also investigated towards optimization of the transmission efficiency. Conclusion: The transmission spectra of designed filters have high transmission and low sideband; its peaks cover the whole visible and near infrared range. These characteristics allow them to have the possibility to be integrated into image sensors for spectrometer applications
Early electroencephalography in patients with Emergency Room diagnoses of suspected new-onset seizures: Diagnostic yield and impact on clinical decision-making
AbstractPurposeTo assess the utility of acute electroencephalography (EEG) performed in the emergency room (ER) and its impact on subsequent management of patients with new-onset seizures. Adults who recover fully in the ER following suspected isolated new-onset seizures are usually discharged to the neurology clinic for further review. An EEG at that stage may be normal. We sought to assess the feasibility and yield of early EEG in the ER setting, its impact on management.MethodsA prospective study from January 2008 to January 2011 of patients diagnosed by ER physicians with uncomplicated suspected first episodes of unprovoked convulsive seizures. All patients underwent routine 30-min EEG in the ER prior to discharge and specialist review was arranged in the epilepsy clinic within 2 weeks of presentation. Management decisions were at the discretion of the treating neurologist. Seizure recurrence was assessed during a follow up period between 9 months and 3 years.Results136 patients were included in the study (92 males). Mean age was 32 years (range 16–73). Forty had abnormal EEGs: 16 focal epileptiform discharges, 12 focal slowing, 10 generalized spike-wave discharges and 2 generalized slowing. Using multivariate analysis, those with abnormal EEG (51% vs 11%, p=0.003) and abnormal MRI (53% vs 28%, p<0.001) were more likely to be commenced on anticonvulsant therapy. Abnormal MRI (p=0.001) was independently associated with a higher risk of recurrence.ConclusionsFollowing an ER diagnosis of new-onset uncomplicated seizure, early EEG had a high diagnostic yield. Abnormal EEG and abnormal MRI significantly contributed to decision-making regarding treatment at specialist review. Abnormal MRI was associated with significantly higher risks of subsequent seizures
Development of a Model for the Separation Characteristics of a Deflector Wheel Classifier Including Particle Collision and Rebound Behavior
Deflector wheel classifiers are widespread in industry for the separation of powders into fine and coarse powders. Even though this separation process has been known for quite some time, it is not yet fully understood, and existing models fail to precisely predict the separation characteristics. Due to the high throughput of deflector wheel classifiers, it is greatly beneficial to estimate the separation characteristics before the experiment. Here, the developed model critically examines the usual assumptions, such as ideal airflow, neglection of particle–wall and particle–particle interactions, or spherically-shaped particles. First, the investigation of the air flow using a Particle Image Velocimetry (PIV) system showed significant differences to the assumed ideal flow field, then particle sphericity and its influence on the interaction between the particles and the paddles of the deflector wheel was investigated and compared with particle rebound behavior on a static wall. Surprisingly, comminuted glass behaves similarly to comminuted limestone in multiple aspects and not like glass beads. To determine the number of particle–particle collisions, Discrete Element Method (DEM) simulations were performed. The aforementioned aspects found application in the model and the separation behavior was well-estimated.DFG, 313858373, SPP 2045: Hochspezifische mehrdimensionale Fraktionierung von technischen Feinstpartikelsysteme
Gonadotropin-releasing hormone analogs during chemotherapy for preservation of ovarian function and fertility in premenopausal early breast cancer patients: a systematic review and meta-analysis of individual patient-level data
Purpose The role of temporary ovarian suppression with gonadotropin-releasing hormone agonists (GnRHa) during chemotherapy as a strategy to preserve ovarian function and fertility in premenopausal women remains controversial. This systematic review and meta-analysis using individual patient\u2013level data was conducted to better assess the efficacy and safety of this strategy in patients with early breast cancer. Methods The trials in which premenopausal women with early breast cancer were randomly assigned to receive (neo)adjuvant chemotherapy alone or with concurrent GnRHa were eligible for inclusion. Primary end points were premature ovarian insufficiency (POI) rate and post-treatment pregnancy rate. Disease-free survival and overall survival were secondary end points. Because each study represents a cluster, statistical analyses were performed using a random effects model. Results A total of 873 patients from five trials were included. POI rate was 14.1% in the GnRHa group and 30.9% in the control group (adjusted odds ratio, 0.38; 95% CI, 0.26 to 0.57; P, .001). A total of 37 (10.3%) patients had at least one post-treatment pregnancy in the GnRHa group and 20 (5.5%) in the control group (incidence rate ratio, 1.83; 95% CI, 1.06 to 3.15; P = .030). No significant differences in disease-free survival (adjusted hazard ratio, 1.01; 95% CI, 0.72 to 1.42; P = .999) and overall survival (adjusted hazard ratio, 0.67; 95% CI, 0.42 to 1.06; P = .083) were observed between groups. Conclusion Our findings provide evidence for the efficacy and safety of temporary ovarian suppression with GnRHa during chemotherapy as an available option to reduce the likelihood of chemotherapy-induced POI and potentially improve future fertility in premenopausal patients with early breast cancer
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