743 research outputs found
Practical Alternatives to Estimate Opportunity Costs of Forest Conservation
Numerous studies have shown the merits of targeting the costs of conservation besides environmental benefits and aligning payments for ecosystem services with incurred costs. However, cost-effective and precise estimation of site specific opportunity costs is a major challenge. In this paper we test two approaches to estimate opportunity costs of conservation: One approach derives opportunity costs from annual land rents, and the other models regresses opportunity costs on easily obtainable and difficult to manipulate spatial and socio-economic independent variables such as soil quality. None of these approaches appeared to estimate opportunity costs sufficiently well. But since this judgment is based on how well the estimates compare to the reference opportunity costs, which were computed from farm budgets, we also considered potential flaws in the reference data and tested their plausibility. The tests confirmed the plausibility of data. Based on the results presented in this paper none of the two cost estimation approaches can be recommended for practical application in conservation programs. Yet, further research is necessary to confirm these findings giving special attention to the techniques that are applied to deliver reference point data on opportunity costs.Resource /Energy Economics and Policy,
Opportunity Costs as a Determinant of Participation in Payments for Ecosystem Service Schemes
Landholders are generally assumed to be willing to participate in payments for ecosystem service (PES) schemes if the offered payment exceeds the opportunity cost of participation. The calculation of opportunity costs is often based on historic financial data such as net returns of the formerly practiced land use. Reliable estimates of opportunity costs are required especially in flexible, cost-aligned payment schemes with differentiated payments at the farm scale. We question whether opportunity cost estimates that do not consider personal landholder characteristics such as risk considerations, information access and non-monetary personal preferences (e.g. for traditional land use practices) are sufficient to explain a landholder's decision to enrol land in PES. To test these assumptions, a PES adoption model was developed for hypothetical adoption decisions by 178 landholders in Costa Rica. The model explained up to 73.5% (Nagelkerkes pseudo R2) of adoption variance. The results confirm that adoption is not determined by financial costs alone. Trust in state institutions, for example, was highly significant. The results call for more integrated methods of opportunity cost estimation such as inverse auctions. Their strength lies, among others, in that all adoption determinants are potentially expressed in the landholder's bid.Resource /Energy Economics and Policy,
Cyber equipping 4.0 – fe-simulation-based setting instructions for a rotary draw-bending machine
The tool setting process for rotary draw-bending is very complex. Only experienced machine operators know which settings lead to a good result in relation to the bending task. Up to seven individual tools can be installed, positioned and set in the process independently. A complete set of tools consists of: pressure die, mandrel, wiper die, inner and outer clamp die as well as the bend die and the collet or piston bend. [1] Furthermore there are the axis settings, which can be adjusted with the parameters distance, force, angle, torque and time. If a defect occurs after the successful set-up process the machine operator has various possibilities to solve the problem. The effects of the different setting parameters and the procedure for the fastest possible elimination of the error are often unclear. The goal is to be able to use an adjustment support for the setting process by means of physical-analytical principles and systematically constructed FE simulations at the bending machine. In order to evaluate the bending result, the condition of the bending component is examined concerning the quality characteristics, cracking, wrinkling, cross-section deformation and elastic deformation. [2] Based on performed and analyzed FE simulations, adjustment recommendations regarding the respective quality characteristics are to be established as well as predictions about possible defects. The simulation and calculation results flow into a database. This is used for the implementation of an electronic expert, who uses a visualization aid to provide the machine operator with information and recommendations on the setup settings. This avoids errors during the equipping process and saves set-up time. Machine operators and particularly trained employees are guided and supported in their work
Involving Motor Capabilities in the Formation of Sensory Space Representations
A goal of sensory coding is to capture features of sensory input that are behaviorally relevant. Therefore, a generic principle of sensory coding should take into account the motor capabilities of an agent. Up to now, unsupervised learning of sensory representations with respect to generic coding principles has been limited to passively received sensory input. Here we propose an algorithm that reorganizes an agent's representation of sensory space by maximizing the predictability of sensory state transitions given a motor action. We applied the algorithm to the sensory spaces of a number of simple, simulated agents with different motor parameters, moving in two-dimensional mazes. We find that the optimization algorithm generates compact, isotropic representations of space, comparable to hippocampal place fields. As expected, the size and spatial distribution of these place fields-like representations adapt to the motor parameters of the agent as well as to its environment. The representations prove to be well suited as a basis for path planning and navigation. They not only possess a high degree of state-transition predictability, but also are temporally stable. We conclude that the coding principle of predictability is a promising candidate for understanding place field formation as the result of sensorimotor reorganization
Model Dependence of Lateral Distribution Functions of High Energy Cosmic Ray Air Showers
The influence of high and low energy hadronic models on lateral distribution
functions of cosmic ray air showers for AUGER energies is explored. A large
variety of presently used high and low energy hadron interaction models are
analysed and the resulting lateral distribution functions are compared. We show
that the slope as well as the signal at 1000 m distance from the shower axis
depend on both the high and low energy hadronic model used. The models are
confronted with available hadron-nucleus data from accelerator experiments.Comment: 8 pages, 18 figures, accepted version, Journal of Astroparticle
Physic
Free-Flap Reconstruction in Early-Stage Squamous Cell Carcinoma of the Oral Cavity : A Prospective Monocentric Trial to Evaluate Oncological Outcome and Quality of Life
Surgery is generally accepted as standard treatment in oral cancer, but the reconstructive
procedures remain a matter of debate. The aim of this study was to evaluate oncological outcome
and quality of life following surgical resection and free-flap reconstruction in patients with early oral
squamous cell carcinoma. The presented trial was performed as a prospective, single-center observation study. Inclusion criteria were primary surgery in early-stage oral squamous cell carcinoma
with free-flap reconstruction. Endpoints were overall and progression-free survival and quality of
life up to 24 months after surgery. Twenty-six patients were included. Overall survival was 100%
and progression-free survival was 92.3% in a maximum follow-up time of 21 months. Global quality
of life showed no significant alteration after surgery. Patients reported a significant reduction in
pain (p = 0.048) and a decreasing impairment of speech one year after surgery (p = 0.021). Free-flap
reconstruction is a safe procedure that results in excellent oncological outcome and quality of life.
Functional outcome is of high relevance in early-stage tumors of the head and neck and may mostly
be affected by reconstructive procedures. Therefore, a prospective evaluation to explore success and
the effects of surgical therapy is highly warranted
Pivot duality of universal interpolation and extrapolation spaces
It is a widely used method, for instance in perturbation theory, to associate
with a given C0-semigroup its so-called interpolation and extrapolation spaces.
In the model case of the shift semigroup acting on L^2(R), the resulting chain
of spaces recovers the classical Sobolev scale. In 2014, the second named
author defined the universal interpolation space as the projective limit of the
interpolation spaces and the universal extrapolation space as the completion of
the inductive limit of the extrapolation spaces, provided that the latter is
Hausdorff.
In this note we use the notion of the dual with respect to a pivot space in
order to show that the aforementioned inductive limit is Hausdorff, already
complete, and can be represented as the dual of the projective limit whenever a
power of the generator of the initial semigroup is a self-adjoint operator. In
the case of the classical Sobolev scale we show that the duality holds, and
that the two universal spaces were already studied by Laurent Schwartz in the
1950s.
Our results and examples complement the approach of Haase, who in 2006 gave a
different definition of universal extrapolation spaces in the context of
functional calculi. Haase avoids the inductive limit topology precisely for the
reason that it a priori cannot be guaranteed that the latter is always
Hausdorff. We show that this is indeed the case provided that we start with a
semigroup defined on a reflexive Banach space.Comment: 9 page
Local Resection of Primary Tumor in Upfront Stage IV Breast Cancer
Background: This study aimed to identify the association of local surgery of the primary tumor in metastatic breast cancer (MBC) patients with overall survival (OS) and prognostic factors. Patients and Methods: Patients with primary MBC (1990-2006) were included in our retrospective analysis (n = 236). 83.1% had surgery for the primary tumor. OS was evaluated using Kaplan-Meier estimates. Predictive factors for OS were determined. Results: Median follow-up was 123 months for all patients still alive at the time of analysis. In univariate analysis, patients with surgery of the primary tumor had significantly prolonged OS (28.9 vs. 23.9 months). Within the surgery group, patients with MBC limited to 1 organ system had a better outcome (39.3 vs. 24.9 months), as did asymptomatic patients. Independent risk factors for shorter OS were hormone receptor negativity, symptoms, and involvement of > 1 organ system. Conclusion: Patient selection for local therapy was confounded by a more favorable profile and a lesser tumor burden before surgery, which might implicate a bias. Nevertheless, our univariate results indicate that local surgery of the primary tumor in MBC patients could be considered as part of the therapeutic regimen in selected patients. However, larger patient numbers are needed to prove these findings in the multivariate model. (C) 2016 S. Karger GmbH, Freibur
Full-Thickness Tumor Resection of Oral Cancer Involving the Facial Skin—Microsurgical Reconstruction of Extensive Defects after Radical Treatment of Advanced Squamous Cell Carcinoma
Advanced tumors of the head and neck are challenging for the treatment specialist due to
the need to synergize oncological and functional requirements. Free flap reconstruction has been
established as the standard of care for defects following tumor resection. However, depending on the
affected anatomic subsite, advanced tumors may impose specific difficulties regarding reconstruction,
especially when full-thickness resection is required. This study aimed to evaluate reconstructive
strategies and oncological outcomes in patients with full-thickness resection of the oral cavity. A
total of 33 patients with extensive defects due to squamous cell carcinoma of the oral cavity were
identified. Indications, reconstructive procedures, and clinical outcome were evaluated. Thirty-two
patients (97%) presented locally advanced tumors (T3/T4). Complete tumor resection was achieved
in 26 patients (78.8%). The anterolateral thigh flap was the most frequently used flap (47.1%), and the
primary flap success rate was 84.8%. The cohort demonstrated a good local control rate and moderate
overall and progression-free survival rates. Most patients regained full competence regarding oral
alimentation and speech. Full-thickness tumor resections of the head and neck area may be necessary
due to advanced tumors in critical anatomic areas. In many cases, radical surgical treatment leads
to good oncological results. Free flap reconstruction has been shown to be a suitable option for
extensive defects in aesthetically challenging regions
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