The collection of seismic station readings

1966 ◽  
Vol 290 (1422) ◽  
pp. 461-471
Keyword(s):  
Reference Point ◽  
Arrival Time ◽  
Seismic Station ◽  
Reference Points ◽  
Origin Time ◽  
Arrival Times ◽  
Starting Point ◽  
Recording Station ◽  
Set Up ◽  
International Seismological Centre

The chief problem of the International Seismological Centre in Edinburgh is to determine focal parameters of seismic events from a stream of station reports. These station reports are identifiable only by the arrival time of the seismic impulse at the given station, as the source location and tim e are not, in general, known when the readings are made. As several events may sometimes occur within a few minutes of each other, and as the P waves from each event may take up to 20 min to reach the points of detection, considerable overlapping is to be expected. One proposal, which will be discussed, is to set up a pattern of reference points covering the Earth, and to subtract the travel time between each reference point and the recording station from the arrival time given in the station report. Each subtraction yields an estimate of what the origin time would have been if the source had been located close to the reference point. If a source actually is close to one of the reference points, the apparent source times form a much sharper ‘bunch’ in a time series than do the arrival times from which they were derived. In addition to assisting recognition, the process yields a provisional epicentre and a set of first residuals and, as such, provides a favourable starting point for the following computations.

scholarly journals Times of arrival and gauge invariance

2021 ◽  
Vol 477 (2250) ◽  
pp. 20210101
Author(s):  
Siddhant Das ◽  
Markus Nöth
Keyword(s):  
Magnetic Field ◽  
Quantum Mechanics ◽  
Arrival Time ◽  
Free Particle ◽  
Natural Generalization ◽  
Arrival Times ◽  
Quantum Flux ◽  
Freely Moving ◽  
Set Up ◽  
Aharonov Bohm

We revisit the arguments underlying two well-known arrival-time distributions in quantum mechanics, viz., the Aharonov–Bohm–Kijowski (ABK) distribution, applicable for freely moving particles, and the quantum flux (QF) distribution. An inconsistency in the original axiomatic derivation of Kijowski’s result is pointed out, along with an inescapable consequence of the ‘negative arrival times’ inherent to this proposal (and generalizations thereof). The ABK free-particle restriction is lifted in a discussion of an explicit arrival-time set-up featuring a charged particle moving in a constant magnetic field. A natural generalization of the ABK distribution is in this case shown to be critically gauge-dependent. A direct comparison to the QF distribution, which does not exhibit this flaw, is drawn (its acknowledged drawback concerning the quantum backflow effect notwithstanding).

A P Travel-Time Model for the Canadian Shield obtained by a Joint Epicenter Determination Method

1974 ◽  
Vol 11 (5) ◽  
pp. 611-618 ◽  
Author(s):  
M. Hashizume
Keyword(s):  
Travel Time ◽  
Canadian Shield ◽  
Time Model ◽  
Time Curve ◽  
Origin Time ◽  
Arrival Times ◽  
Shallow Earthquakes ◽  
Starting Point ◽  
Order Polynomial

The P arrival-times for nine very shallow earthquakes under the Canadian Shield and the surrounding area were studied. P arrival-times were assumed to be a function of the hypocenter, origin-time, and specified travel-time curve. Using as starting point the hypocenters and origin times taken from the Preliminary Determination of Epicenters (PDE) listings and the travel-time curve from the "Seismological Tables for P Phases" by Herrin et al. (1968), calculations were conducted so as to minimize the residuals between the observed P arrival-times and the calculated travel-times in a search for the best hypocenters, origin-times, and travel-time curve. The deviations from the travel-time curve were assumed to be represented by a sixth-order polynomial. The differences of the new epicenters from those of the PDE listings are small and generally less than about 10 km. The significant result is that the new travel-time curve obtained by this technique is similar to those obtained from seismic explosion studies in the eastern part of North America.

Seismological measurements and measurement error

1968 ◽  
Vol 58 (4) ◽  
pp. 1261-1271 ◽  
Author(s):  
Helen W. Freedman
Keyword(s):  
Probability Distribution ◽  
Related Problem ◽  
Arrival Time ◽  
Focal Depth ◽  
Degree Of Contamination ◽  
Origin Time ◽  
Arrival Times ◽  
Time Estimates ◽  
Error Variable ◽  
Hypocentral Location

Abstract A seismological measurement, such as arrival time or, less directly origin time, is an example of a measurement variable which can be considered as the sum of a parameter—the quantity being measured—and an error variable. Optimal methods for the estimation of this parameter vary with the probability distribution of the error variable. In particular, estimation in the presence of bias or of gross errors is discussed, together with the related problem of precision versus accuracy of the estimate. Errors in estimates of arrival times, origin times and hypocentral location contribute to variation in travel-time estimates; these are analyzed separately. Each of these, with the exception of focal depth, has a distribution which can be fitted to a mixture of a normal distribution and some contamination. The degree of contamination varies; methods for truncation are suggested. The presence of possible, often undetectable, bias in locations and travel times may make confidence statements about these parameters unreliable.

Cognitive Reflection Effects on Time Discounting

2018 ◽  
Vol 39 (2) ◽  
pp. 99-106 ◽  
Author(s):  
Michał Białek ◽  
Przemysław Sawicki
Keyword(s):  
Individual Differences ◽  
Individual Difference ◽  
Delay Discounting ◽  
Reference Point ◽  
Reference Points ◽  
Cognitive Reflection Test ◽  
Process Information ◽  
Time Discounting ◽  
Cognitive Reflection ◽  
The Way

Abstract. In this work, we investigated individual differences in cognitive reflection effects on delay discounting – a preference for smaller sooner over larger later payoff. People are claimed to prefer more these alternatives they considered first – so-called reference point – over the alternatives they considered later. Cognitive reflection affects the way individuals process information, with less reflective individuals relying predominantly on the first information they consider, thus, being more susceptible to reference points as compared to more reflective individuals. In Experiment 1, we confirmed that individuals who scored high on the Cognitive Reflection Test discount less strongly than less reflective individuals, but we also show that such individuals are less susceptible to imposed reference points. Experiment 2 replicated these findings additionally providing evidence that cognitive reflection predicts discounting strength and (in)dependency to reference points over and above individual difference in numeracy.

‘[T]his world is now thy pilgrimage’: William Michael Rossetti's Cognitive Maps of France and Italy

2018 ◽  
Vol 8 (1) ◽  
pp. 84-99
Author(s):  
Eleonora Sasso
Keyword(s):  
Cognitive Linguistics ◽  
Venice Lagoon ◽  
Cognitive Map ◽  
Reference Points ◽  
Late Nineteenth Century ◽  
Mental Picture ◽  
Historical Figures ◽  
Starting Point ◽  
Cognitive Semantic ◽  
St Helena

This paper takes as its starting point the conceptual metaphor ‘life is a journey’ as defined by Lakoff and Johnson (1980) in order to advance a new reading of William Michael Rossetti's Democratic Sonnets (1907). These political verses may be defined as cognitive-semantic poems, which attest to the centrality of travel in the creation of literary and artistic meaning. Rossetti's Democratic Sonnets is not only a political manifesto against tyranny and oppression, promoting the struggle for liberalism and democracy as embodied by historical figures such as Napoleon, Mazzini, Cavour, and Garibaldi; but it also reproduces Rossetti's real and imagined journeys throughout Europe in the late nineteenth century. This essay examines these references in light of the issues they raise, especially the poet as a traveller and the journey metaphor in poetry. But its central purpose is to re-read Democratic Sonnets as a cognitive map of Rossetti's mental picture of France and Italy. A cognitive map, first theorised by Edward Tolman in the 1940s, is a very personal representation of the environment that we all experience, serving to navigate unfamiliar territory, give direction, and recall information. In terms of cognitive linguistics, Rossetti is a figure whose path is determined by French and Italian landmarks (Paris, the island of St. Helena, the Alps, the Venice Lagoon, Mount Vesuvius, and so forth), which function as reference points for orientation and are tied to the historical events of the Italian Risorgimento. Through his sonnets, Rossetti attempts to build into his work the kind of poetic revolution and sense of history which may only be achieved through encounters with other cultures.

Do You Need to be Risk-Tolerant to Become an Entrepreneur? The Importance of the Reference Point

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Lucio Fuentelsaz ◽  
Juan P. Maicas ◽  
Javier Montero
Keyword(s):  
Reference Point ◽  
New Ventures ◽  
Risk Tolerance ◽  
High Educational Level ◽  
Risk And Uncertainty ◽  
Global Entrepreneurship Monitor ◽  
Entrepreneurial Entry ◽  
Global Entrepreneurship ◽  
Set Up ◽  
High Educational

AbstractThe creation of new ventures involves a great deal of risk and uncertainty. However, research has been theoretically divergent and empirically inconclusive about the influence of individuals’ risk tolerance on entrepreneurial entry. In this paper, we argue that this relationship is contingent on the reference point of individuals, taking into account the human capital and the opportunity cost of individuals when they decide to start a venture. This approach allows us to clarify some of the previous mixed results in the literature. We use a sample of almost 600,000 individuals from 90 countries that have participated in the Global Entrepreneurship Monitor project between 2010 and 2014. Our results show that individuals with previous experience as entrepreneurs do not need to be so risk-tolerant to set up their own venture, while individuals with a job and/or a high educational level need to be especially risk-tolerant to become entrepreneurs.

scholarly journals Reconciling Loss Aversion and Gain Seeking in Judged Emotions

2021 ◽  
pp. 096372142199204
Author(s):  
Barbara A. Mellers ◽  
Siyuan Yin ◽  
Jonathan Z. Berman
Keyword(s):  
Loss Aversion ◽  
Reference Point ◽  
Emotional Reactions ◽  
Status Quo ◽  
New Approach ◽  
Negative Change ◽  
Starting Point ◽  
The Status ◽  
Positive Feelings ◽  
Negative Feelings

Is the pain of a loss greater in magnitude than the pleasure of a comparable gain? Studies that compare positive feelings about a gain with negative feelings about a comparable loss have found mixed answers to this question. The pain of a loss can be greater than, less than, or equal to the pleasure of a comparable gain. We offer a new approach to test hedonic loss aversion. This method uses emotional reactions to the reference point, a positive change, and a negative change. When we manipulated the reference point (i.e., pleasurable and painful), two distinct patterns emerged. Pain surpassed pleasure (loss aversion) when the reference point was positive, and pleasure exceeded pain (gain seeking) when the reference point was negative. A reference-dependent version of prospect theory accounts for the results. If the carriers of utility are changes from a reference point—not necessarily the status quo—both loss aversion and gain seeking are predicted. Loss aversion and gain seeking can be reconciled if you take the starting point into account.

scholarly journals ILRS Reference Point Determination Using Close Range Photogrammetry

2021 ◽  
Vol 11 (6) ◽  
pp. 2785
Author(s):  
Michael Lösler ◽  
Cornelia Eschelbach ◽  
Thomas Klügel ◽  
Stefan Riepl
Keyword(s):  
Reference Point ◽  
Reference Points ◽  
Geodetic Reference System ◽  
Unscented Transformation ◽  
Local Ties ◽  
Close Range Photogrammetry ◽  
Crucial Component ◽  
Space Geodetic Techniques ◽  
Close Range ◽  
Point Determination

A global geodetic reference system (GGRS) is realized by physical points on the Earth’s surface and is referred to as a global geodetic reference frame (GGRF). The GGRF is derived by combining several space geodetic techniques, and the reference points of these techniques are the physical points of such a realization. Due to the weak physical connection between the space geodetic techniques, so-called local ties are introduced to the combination procedure. A local tie is the spatial vector defined between the reference points of two space geodetic techniques. It is derivable by local measurements at multitechnique stations, which operate more than one space geodetic technique. Local ties are a crucial component within the intertechnique combination; therefore, erroneous or outdated vectors affect the global results. In order to reach the ambitious accuracy goal of 1 mm for a global position, the global geodetic observing system (GGOS) aims for strategies to improve local ties, and, thus, the reference point determination procedures. In this contribution, close range photogrammetry is applied for the first time to determine the reference point of a laser telescope used for satellite laser ranging (SLR) at Geodetic Observatory Wettzell (GOW). A measurement campaign using various configurations was performed at the Satellite Observing System Wettzell (SOS-W) to evaluate the achievable accuracy and the measurement effort. The bias of the estimates were studied using an unscented transformation. Biases occur if nonlinear functions are replaced and are solved by linear substitute problems. Moreover, the influence of the chosen stochastic model onto the estimates is studied by means of various dispersion matrices of the observations. It is shown that the resulting standard deviations are two to three times overestimated if stochastic dependencies are neglected.

The Chelmsford-Lowell, Massachusetts, earthquake of 23 November 1980: Depth control and fault plane solution

1981 ◽  
Vol 71 (4) ◽  
pp. 1369-1372
Author(s):  
Jay J. Pulli ◽  
Michael J. Guenette
Keyword(s):  
New England ◽  
Fault Plane ◽  
Seismic Station ◽  
Focal Depth ◽  
Strike Slip ◽  
Fault Plane Solution ◽  
Origin Time ◽  
Small Magnitude ◽  
Depth Control ◽  
Plane Solution

abstract On 23 November 1980, a small (magnitude 2.9) earthquake occurred on the Chelmsford-Lowell, Massachusetts, border, approximately 10 km northeast of the MIT seismic station at Westford, Massachusetts (WFM). Thus we were able to accurately determine the focal depth, which is generally not the case in New England. Our hypocentral solution was latitude 41.63, longitude −71.36, depth 1.5 km, at origin time 00:39:32.0 UTC. The fault plane solution shows either strike-slip or dip-slip faulting with a P axis trending NE-SW, which is in agreement with overcoring measurements in a nearby granite quarry.

An Alternative Perspective on Recruitment Overfishing and Biological Reference Points

1987 ◽  
Vol 44 (4) ◽  
pp. 913-918 ◽  
Author(s):  
M. P. Sissenwine ◽  
J. G. Shepherd
Keyword(s):  
Fisheries Management ◽  
Reference Point ◽  
Reference Points ◽  
Fishing Mortality ◽  
Alternative Perspective ◽  
Conventional Models ◽  
Definition Of ◽  
Yield Per Recruit ◽  
Spawning Biomass

Biological reference points are used to guide fisheries management decisions. The reference points most often used are expressed in terms of fishing mortality rate (F). Fmsy relates to the maximization of sustainable yield. In principle, it is a most useful reference point, but in practice it is difficult to estimate. Fmax and F0.1 relate to certain levels of yield per recruit and are easily estimated, but they ignore conservation of the resource. Recruitment overfishing has usually been understood to occur when a population has been fished down to a point where recruitment is substantially reduced or fails. It has not been used as a basis for a biological reference point because the definition is vague and cannot be readily related to fishing mortality. Levels of spawning biomass below which recruitment seems to be reduced have been used, but their determination from available data is usually difficult and controversial. We propose an alternative definition of recruitment overfishing in terms of the level of fishing pressure that reduces the spawning biomass of a year class over its lifetime below the spawning biomass of its parents on average. Conventional models and types of data can be used to determine this level of F, denoted as Frep, which clearly relates to the replacement of spawning biomass and thus to sustainability of a population and yield in the long term.

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