11,654 research outputs found
Conway's subprime Fibonacci sequences
It's the age-old recurrence with a twist: sum the last two terms and if the
result is composite, divide by its smallest prime divisor to get the next term
(e.g., 0, 1, 1, 2, 3, 5, 4, 3, 7, ...). These sequences exhibit pseudo-random
behaviour and generally terminate in a handful of cycles, properties
reminiscent of 3x+1 and related sequences. We examine the elementary properties
of these 'subprime' Fibonacci sequences.Comment: 18 pages, 5 figure
Characterisation of the dynamical quantum state of a zero temperature Bose-Einstein condensate
We describe the quantum state of a Bose-Einstein condensate at zero
temperature. By evaluating the Q-function we show that the ground state of
Bose-Einstein condensate under the Hartree approximation is squeezed. We find
that multimode Schroedinger cat states are generated as the condensate evolves
in a ballistic expansion.Comment: 13 pages, 6 figure
Comparing radio-tracking and visual detection methods to quantify group size measures
1. Average values of animal group sizes are prone to be overestimated in traditional field studies because small groups and singletons are easier to overlook than large ones. This kind of bias also applies for the method of locating groups by tracking previously radio-collared individuals in the wild. If the researcher randomly chooses a collared animal to locate a group to visit, a large group has higher probability to be selected than a small one, simply because it has more members.2. The question arises whether location of groups by means of finding collared animals has smaller or greater bias than searching for groups by visual observation. If the bias is smaller or same, this method can be recommended for finding groups. However, such a comparison cannot be made by speculation, only by empirical investigation.3. The present study compares the two methods empirically, by statistically comparing group size measures (mean, median, quantiles, frequency distribution, and ‘typical group size’) between two data sets. These data sets comprise of Rocky Mountain mule deer group size values collected in the same area during the same period of time, referring either to groups located by the traditional ‘search and observe method’ or located by tracking formerly collared individuals.4. All group size measures are statistically similar in the two samples, thus we conclude that the two methods yielded similar biases. Although the true group size measures are not known, we presume that both methods have overestimated them. We propose that these results do not necessary apply to other species, thus cannot be generalized. The reason for this is that bias may depend on factors specific to the species: bias of visual observation may depend on how well the species conceals itself in the existing habitat, and the bias associated with finding groups using collared animals is likely dependent on group size distribution and also on the proportion of collared animals in the population
Direct measurements of the magnetocaloric effect in pulsed magnetic fields: The example of the Heusler alloy NiMnIn
We have studied the magnetocaloric effect (MCE) in the shape-memory Heusler
alloy NiMnIn by direct measurements in pulsed magnetic
fields up to 6 and 20 T. The results in 6 T are compared with data obtained
from heat-capacity experiments. We find a saturation of the inverse MCE,
related to the first-order martensitic transition, with a maximum adiabatic
temperature change of K at 250 K and a conventional
field-dependent MCE near the second-order ferromagnetic transition in the
austenitic phase. The pulsed magnetic field data allow for an analysis of the
temperature response of the sample to the magnetic field on a time scale of
to 100 ms which is on the order of typical operation frequencies (10
to 100 Hz) of magnetocaloric cooling devices. Our results disclose that in
shape-memory alloys the different contributions to the MCE and hysteresis
effects around the martensitic transition have to be carefully considered for
future cooling applications.Comment: 5 pages, 4 figure
Multistate Outbreaks of Foodborne Illness in the United States associated With Fresh Produce From 2010 to 2017
In the United States, the consumption of fresh fruits and vegetables has increased during recent years as consumers seek to make healthier lifestyle choices. However, the number of outbreaks associated with fresh produce that involve cases in more than one state (multistate) has increased concomitantly. As the distance along the farm-to-fork continuum has lengthened over time, there are also more opportunities for fresh produce contamination with bacterial pathogens before it reaches the consumer. This review provides an overview of the three bacterial pathogens (i.e., pathogeni
Tourism planning: impacts as benchmarks for sustainable development plans
Purpose: The purpose of this paper is to provide a comprehensive list of indicators to be used in the tourism sector, in support of the development of sustainable strategic plans. Specific objectives include making a comprehensive assessment and categorization of those indicators and facilitating an easier to use system that guarantees the use of those benchmarks as a base for objectives definition and performance standards monitorization. Design/methodology/approach: This research adopted a descriptive design using secondary data. The data was analysed using content analysis and a posteriori categorization system, resulting in 87 indicators divided into positive and negative within six categories. Findings: The results showed that there are six key factors that may have a significant impact on tourism development suggesting they could be used for setting objectives and performance indicators when developing a strategic plan, and therefore, ensuring the sustainability of a destination and its stakeholders. Practical implications: The framework adopted in this study offers a practical tool to be used by destination and organizations planners to improve sustainable tourism performance in relation to economic, socio-cultural, psychological, political/administrative, tourism/commercial and environmental/physical measurement standards. This guidance may help decision-makers to design, manage and control sustainable strategic plans in a more effective way. Originality/value: This paper links the academic debate on the impacts of tourism with the designing and implementation of sustainable tourism policies and strategies.info:eu-repo/semantics/acceptedVersio
Reconciling Environmentalism and the Left: Perspectives on Democracy and Social Justice in British Columbia\u27s Environmental Movement
The article examines how political ideas of environmentalists support as well as impede relations between the environmental movement and other progressive movements. This requires examination of the role and meaning of social justice and democracy in the discourse of environmentalism. Ibis study focuses such an examination on a sample of environmental activists in British Columbia. Q methodology is used to discern patterns of association between particular sets of environmental ideas, and beliefs and values related to democracy and social justice. The authors identify four environmental/political perspectives: alienated ecocentrism, civic communitarianism, insider preservationism and green egalitarianism. These perspectives share a perception of justice focused on fair democratic procedures. Fairness is linked to inclusion and equal treatment
Control System for the LEDA 6.7-MeV Proton Beam Halo Experiment
Measurement of high-power proton beam-halo formation is the ongoing
scientific experiment for the Low Energy Demonstration Accelerator (LEDA)
facility. To attain this measurement goal, a 52-magnet beam line containing
several types of beam diagnostic instrumentation is being installed. The
Experimental Physics and Industrial Control System (EPICS) and commercial
software applications are presently being integrated to provide a real-time,
synchronous data acquisition and control system. This system is comprised of
magnet control, vacuum control, motor control, data acquisition, and data
analysis. Unique requirements led to the development and integration of
customized software and hardware. EPICS real-time databases, Interactive Data
Language (IDL) programs, LabVIEW Virtual Instruments (VI), and State Notation
Language (SNL) sequences are hosted on VXI, PC, and UNIX-based platforms which
interact using the EPICS Channel Access (CA) communication protocol.
Acquisition and control hardware technology ranges from DSP-based diagnostic
instrumentation to the PLC-controlled vacuum system. This paper describes the
control system hardware and software design, and implementation.Comment: LINAC2000 Conference, 4 pg
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