1,198 research outputs found
Process, System, Causality, and Quantum Mechanics, A Psychoanalysis of Animal Faith
We shall argue in this paper that a central piece of modern physics does not
really belong to physics at all but to elementary probability theory. Given a
joint probability distribution J on a set of random variables containing x and
y, define a link between x and y to be the condition x=y on J. Define the {\it
state} D of a link x=y as the joint probability distribution matrix on x and y
without the link. The two core laws of quantum mechanics are the Born
probability rule, and the unitary dynamical law whose best known form is the
Schrodinger's equation. Von Neumann formulated these two laws in the language
of Hilbert space as prob(P) = trace(PD) and D'T = TD respectively, where P is a
projection, D and D' are (von Neumann) density matrices, and T is a unitary
transformation. We'll see that if we regard link states as density matrices,
the algebraic forms of these two core laws occur as completely general theorems
about links. When we extend probability theory by allowing cases to count
negatively, we find that the Hilbert space framework of quantum mechanics
proper emerges from the assumption that all D's are symmetrical in rows and
columns. On the other hand, Markovian systems emerge when we assume that one of
every linked variable pair has a uniform probability distribution. By
representing quantum and Markovian structure in this way, we see clearly both
how they differ, and also how they can coexist in natural harmony with each
other, as they must in quantum measurement, which we'll examine in some detail.
Looking beyond quantum mechanics, we see how both structures have their special
places in a much larger continuum of formal systems that we have yet to look
for in nature.Comment: LaTex, 86 page
Discrete Physics and the Dirac Equation
We rewrite the 1+1 Dirac equation in light cone coordinates in two
significant forms, and solve them exactly using the classical calculus of
finite differences. The complex form yields ``Feynman's Checkerboard''---a
weighted sum over lattice paths. The rational, real form can also be
interpreted in terms of bit-strings.Comment: LaTex 16 pages, 10 figures. To obtain a copy, send e-mail to
[email protected]
Interactions between nutrition and gastrointestinal infections with parasitic nematodes in goats
Parasitic nematodes of the digestive tract remain one of the main constraints to goat production both in temperate and tropical
countries. The usual mode of control of these gastrointestinal nematodes (GIN) based on the repeated use of anthelmintics
is now strongly questioned because of the increasing development of resistance to these molecules. Among the alternative
methods to anthelmintics currently available, the manipulation of host nutrition in order to improve the host resistance and/or
resilience to parasitic infections seems to represent one of the most promising options to reduce the dependence on conventional
chemotherapy and to favour the sustainable control of gastro intestinal nematode infections. This paper will review the available
information on the interactions between nutrition and nematode parasitism in dairy or meat goats both in temperate and tropical
conditions. It will refer to quantitative aspects of the diet (influence of the protein and/or energy parts) as well as to qualitative
components (effects of plant secondary metabolites on worm biology) and will discuss the specificities of goats in regard of
theses interactions
Demo Abstract: R.A.V.E.N. â Remote Autonomous Vehicle Explorer Network
Unmanned aerial vehicles (UAVs) have recently become a viable platform for surveillance and exploration tasks. Several commercial quadrotor aircraft have been successfully used as surveillance equipment with groups such as United States and Canadian police forces, and additional applications for this technology could include exploration of ra-dioactive/hazmat environments, naval search and rescue, or surveying a building on fire, to name a few. Despite the agility and speed of the quadrotor platform, current systems lack the redundancy and collaboration of a multi-unit team; current implementations of quadrotor UAV flocks require expensive equipment, limiting the system to operation within range of external sensors. We propose a system for intelligently controlling multiple quadrotor UAVs using a combination of on-board vision tracking and wireless communication of attitude measurements. The proposed system uses a lead, human-controlled quadrotor and one or more quadro-tors that track and follow the lead unit autonomously. The forthcoming system aims to improve the execution time required to complete missions and increase both breadth of search and platform effectiveness
Cooperative Flight Guidance of Autonomous Unmanned Aerial Vehicles
As robotic platforms and unmanned aerial vehicles (UAVs) increase in sophistication and complexity, the ability to determine the spatial orientation and placement of the platform in real time (localization) becomes an important issue. Detecting and extracting locations of objects, barriers, and openings is required to ensure the overall effectiveness of the device. Current methods to achieve localization for UAVs require expensive external equipment and limit the overall applicable range of the platform. The system described herein incorporates leader-follower unmanned aerial vehicles using vision processing, radio-frequency data transmission, and additional sensors to achieve flocking behavior. This system targets search and rescue environments, employing controls, vision processing, and embedded systems to allow for easy deployment of multiple quadrotor UAVs while requiring the control of only one. The system demonstrates a relative localization scheme for UAVs in a leader-follower configuration, allowing for predictive maneuvers including path following and estimation of the lead UAV in situations of limited or no line-of-sight
COOP Charts in French: translation and preliminary data on instrument properties
This paper describes the procedure used to translate the COOP Charts into French and provides preliminary information on the instrument's acceptability, reliability and validity. The charts were translated in several steps: seven initial translations were combined into a first pilot version, which was then tested for acceptability, clarity and alternate wordings in two convenience samples taken from the general population (n=53). The modified version was then reviewed by a lay panel and another translator and submitted by mail to 209 congress participants to test several construct validity hypotheses through known-groups comparisons. A panel of public health professionals discussed the content validity of the charts. Finally, test-retest reliability and concurrent validity with SF-36 Health Survey scores were examined among 65 patients with end-stage renal disease. The translation process identified a wide variability in translation options for several items. The acceptability of the charts was excellent. The test-retest correlations ranged from 0.60 to 0.87. Content validity appeared to be appropriate, except for the chart on âsocial support', which combines the questions of need and availability of social support. The utility of illustrations was questioned by some respondents: many claimed not to have used the illustrations in selecting their response, while others found them to be not expressive enough. Most preliminary tests of construct validity were consistent with theory. This French translation of the COOP Charts appears to be ready for more extensive testing in the intended target population of ambulatory patient
Accuracy of crowdsourced streamflow and stream level class estimates
Streamflow data are important for river management and the calibration of hydrological models. However, such data are only available for gauged catchments. Citizen science offers an alternative data source, and can be used to estimate streamflow at ungauged sites. We evaluated the accuracy of crowdsourced streamflow estimates for 10 streams in Switzerland by asking citizens to estimate streamflow either directly, or based on the estimated width, depth and velocity of the stream. Additionally, we asked them to estimate the stream level class by comparing the current stream level with a picture that included a virtual staff gauge. To compare the different estimates, the stream level class estimates were converted into streamflow. The results indicate that stream level classes were estimated more accurately than streamflow, and more accurately represented high and low flow conditions. Based on this result, we suggest that citizen science projects focus on stream level class estimates instead of streamflow estimates
Value of crowdâbased water level class observations for hydrological model calibration
While hydrological models generally rely on continuous streamflow data for calibration, previous studies have shown that a few measurements can be sufficient to constrain model parameters. Other studies have shown that continuous water level or water level class (WLâclass) data can be informative for model calibration. In this study, we combined these approaches and explored the potential value of a limited number of WLâclass observations for calibration of a bucketâtype runoff model (HBV) for four catchments in Switzerland. We generated synthetic data to represent citizen science data and examined the effects of the temporal resolution of the observations, the numbers of WLâclasses, and the magnitude of the errors in the WLâclass data on the model validation performance. Our results indicate that on average one observation per week for a oneâyear period can significantly improve model performance compared to the situation without any streamflow data. Furthermore, the validation performance for model parameters calibrated with WLâclass observations was similar to the performance of the calibration with precise water level measurements. The number of WLâclasses did not influence the validation performance noticeably when at least four WLâclasses were used. The impact of typical errors for citizenâscienceâbased estimates of WLâclasses on the model performance was small. These results are encouraging for citizen science projects where citizens observe water levels for otherwise ungauged streams using virtual or physical staff gauges
Identification of a new cocrystal of citric acid and paracetamol of pharmaceutical relevance
Cocrystals have been increasingly recognized as an attractive alternative delivery form for solid drug products. In this work, Raman spectroscopy, X-ray powder diffraction/X-ray crystallography, and differential scanning calorimetry have been used to study the phenomenon of cocrystal formation in stoichiometric mixtures of citric acid with paracetamol. Raman spectroscopy was particularly useful for the characterization of the products and was used to determine the nature of the interactions in the cocrystals. It was observed that little change in the vibrational modes associated with the phenyl groups of the respective reactants took place upon cocrystal formation but changes in intensities of the vibrational modes associated with the amide and the carboxylic acid groups were observed upon cocrystal formation. Several new vibrational bands were identified in the cocrystal which were not manifest in the raw material and could be used as diagnostic features of cocrystal formation. An understanding of the effects of cocrystal formation on the vibrational modes was obtained by the complete assignment of the spectra of the starting materials and of the cocrystal component. The results show that the cocrystals was obtained in a 2:1 molar ratio of paracetamol to citric acid. The asymmetric unit of the crystal contains two paracetamol molecules hydrogen-bonded to the citric acid; one of these acts as a phenolic-OH hydrogen bond donor to the carbonyl of a carboxylic acid arm of citric acid. In contrast, the other phenolic-OH acts as a hydrogen bond acceptor from the quaternary C-OH of citric acid. Ă© 2011 The Royal Society of Chemistry
IFKIS - a basis for managing avalanche risk in settlements and on roads in Switzerland
After the avalanche winter of 1999 in Switzerland, which caused 17 deaths and damage of over CHF 600 mill. in buildings and on roads, the project IFKIS, aimed at improving the basics of organizational measures (closure of roads, evacuation etc.) in avalanche risk management, was initiated. <P style='line-height: 20px;'> The three main parts of the project were the development of a compulsory checklist for avalanche safety services, a modular education and training course program and an information system for safety services. The information system was developed in order to improve both the information flux between the national centre for avalanche forecasting, the Swiss Federal Institute for Snow and Avalanche Research SLF, and the local safety services on the one hand and the communication between avalanche safety services in the communities on the other hand. <P style='line-height: 20px;'> The results of this project make a valuable contribution to strengthening organizational measures in avalanche risk management and to closing the gaps, which became apparent during the avalanche winter of 1999. They are not restricted to snow avalanches but can also be adapted for dealing with other natural hazard processes and catastrophes
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