Expected Time Delay Research Articles

A review of the quantitative links between CMEs and magnetic clouds

Abstract. Magnetic clouds (MCs), and more generally, interplanetary coronal mass ejections (ICMEs), are believed to be the interplanetary counterparts of CMEs. The link has usually been shown by taking into account the CME launch position on the Sun, the expected time delay and by comparing the orientation of the coronal and interplanetary magnetic field. Making such a link more quantitative is challenging since it requires a relation between very different kinds of magnetic field measurements: (i) photospheric magnetic maps, which are observed from a distant vantage point (remote sensing) and (ii) in-situ measurements of MCs, which provide precise, directly measured, magnetic field data merely from one-dimensional linear samples. The association between events in these different domains can be made using adequate coronal and MC models. Then, global quantities like magnetic fluxes and helicity can be derived and compared. This review paper describes all the general trends found in the above association criteria. A special focus is given for the cases which do not follow the earlier derived mean laws since interesting physics is usually involved.

TC1 and Cluster observation of an FTE on 4 January 2005: A close conjunction

Observations of a Flux Transfer Event (FTE) signature at the dayside magnetopause are reported, which was consecutively observed on 4 January 2005 by both the Double Star/TC1 spacecraft and the Cluster quartet, while the spacecraft were traversing through the northern‐dusk magnetopause. The event occurred as a magnetosheath FTE first at the Cluster spacecraft at about 07:13 UT on 4 January 2005 and crossed each of the others within 2 minutes. The spatial separations between the Cluster spacecraft were of the order of 200 km. The TC1 signature occurred about 108s after Cluster. All findings including magnetic fluxes, orientations and hot ion velocity distributions strongly suggest that Cluster and TC1 encountered the magnetosheath branch of the same flux tube at two different positions along its length and this is borne out by computation of the expected time delay. Four‐spacecraft timing is used to obtain the velocity of FTE.

The NORwegian study on DIstrict treatment of ST-Elevation Myocardial Infarction (NORDISTEMI)

Objectives. Thrombolysis is the treatment of choice for patients with ST-elevation myocardial infarction (STEMI) living in rural areas with long transfer delays to percutaneous coronary intervention (PCI). This trial compares two different strategies following thrombolysis: to transfer all patients for immediate coronary angiography and intervention, or to manage the patients more conservatively. Design. The NORwegian study on DIstrict treatment of STEMI (NORDISTEMI) is an open, prospective, randomized controlled trial in patients with STEMI of less than 6 hours of duration and more than 90 minutes expected time delay to PCI. A total of 266 patients will receive full-dose thrombolysis, preferably prehospitally, and then be randomized to either strategy. Our primary endpoint is the one year combined incidence of death, reinfarction, stroke or new myocardial ischaemia. The study is registered with ClinicalTrials.gov, number NCT00161005. Results. By April 2006, 109 patients have been randomized. Thrombolysis has been given prehospitally to 52% of patients. The median transport distance from first medical contact to catheterization laboratory was 155 km (range 90–396 km). Results of the study are expected in 2008.Trial registration: ClinicalTrials.gov identifier: NCT00161005.

GRB 051221A and tests of Lorentz symmetry

Various approaches to quantum gravity suggest the possibility of violation ofLorentz symmetry at very high energies. In these cases we expect a modificationat low energies of the dispersion relation of photons that contains extra powersof the momentum suppressed by a high energy scale. These terms break boostinvariance and can be tested even at relatively low energies. We use the lightcurves of the very bright short gamma-ray burst GRB 051221A and compare thearrival times of photons at different energies with the expected time delay due to amodified dispersion relation. As no time delay was observed, we set a lower bound of0.0066 Epl ∼ 0.66 × 1017 GeV on the scale of Lorentz invariance violation.

Performance evaluation of control networks: Ethernet, ControlNet, and DeviceNet

Many different network types have been promoted for use in control systems. In this article, we compare three of them: the Ethernet bus, with carrier sense multiple access with collision detection, token-passing bus (e.g., ControlNet), and controller area network bus (e.g., DeviceNet). We consider how each control network can be used as a communication backbone for a networked control system connecting sensors, actuators, and controllers. A detailed discussion of the medium access control sublayer protocol for each network is provided. For each protocol, we study the key parameters of the corresponding network when used in a control situation, including network utilization, magnitude of the expected time delay, and characteristics of time delays. Simulation results are presented for several different scenarios, and the advantages and disadvantages of each network are summarized.

RX J0911+05: A Massive Cluster Lens at [ITAL]z[/ITAL] = 0.769

We report the detection of a massive high-redshift cluster of galaxies near the quadruple quasar RX J0911+05, using the LRIS instrument on the Keck-II telescope. The cluster is found to have a mean redshift of <z>=0.7689+/-0.002 and a velocity dispersion of sigma=836{+180-200} km/s, based on redshift measurements for 24 member galaxies. This massive high-redshift cluster is the origin of the unusually large external shear required by lensing models of the quadruple quasar system. We predict the expected time delay depending on the exact contribution of the cluster. A measurement of the time delay and further deep lensing and X-ray observations will unravel useful properties of this serendipitously discovered high-redshift cluster, and may put interesting cosmological constraints on H0.

Optimal Information Gathering on the Internet with Time and Cost Constraints

The World Wide Web provides access to vast amounts of information, but content providers are considering charging for the information and services they supply. Thus the consumer may face the problem of balancing the benefit of asking for information against the cost (in terms of both money and time) of acquiring it. We study information-gathering strategies that maximize the expected value to the consumer. In our model there is a single information request, which has a known benefit to the consumer. To satisfy the request, queries can be sent simultaneously or in sequence to any of a finite set of independent information sources. For each source we know the monetary cost of making the query, the amount of time it will take, and the probability that the source will be able to provide the requested information. A policy specifies which sources to contact at which times, and the expected value of the policy can be defined as some function of the likelihood that the policy will yield an answer, the expected benefit, and the monetary cost and time delay associated with executing the policy. The problem is to find an expected-value-maximizing policy. We explore four variants of the objective function V: (i) V consists only of the benefit term subject to threshold constraints on both total cost and total elapsed time, (ii) V is linear in the expected total cost of the policy subject to the constraint that the total elapsed time never exceeds some deadline, (iii) V is linear in the expected total elapsed time subject to the constraint that the total cost never exceeds some threshold, and (iv) V is linear in the expected total monetary cost and the expected time delay of the policy. The problems of devising an optimal querying policy for all four variants and approximating an optimal querying policy for variants (iii) and (iv) are shown to be NP-hard. For (i), and with a mild simplifying assumption for (iii), we give a fully polynomial time approximation scheme. For (ii), we consider batched querying policies, and design an O(n2) time approximation algorithm with ratio $\frac{1}{2}$ and a polynomial time approximation scheme for optimal single-batch policies, and an O(kn2) time approximation algorithm with ratio $\frac{1}{5}$ for optimal k-batch policies.

Expected time delay in multi-item inventory systems with correlated demands

This paper considers multi-item inventory systems where a customer order may require several different items (i.e., demands are correlated across items) and customer satisfaction is measured by the time delays seen by the customers. Most inventory models on time delay in the literature assume each demand only requires one item (i.e., demands are not correlated across items or are independent). In this paper, we derive an exact expression for the expected total time delay. We show that when items are actually correlated, assuming items are independent leads to an overestimate of the total time delay. However, (1) it is extremely difficult in practice to obtain the demand information for all demand types (especially in a system with tens of thousands of part numbers), and (2) the problem becomes too complicated to be of practical interest when the correlation is considered. We then explore the possibility of including the demand information partially and develop bounds for the time delays. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 671–688, 1999

The Variability Of PG1115+080

PG1115+080 (Weymann et al. 1980), the first quadruple lens system, remains the most promising for an optical measurement of the Hubble constant through a time delay. Factors contributing to this assessment include the well constrained geometry, the apparent magnitudes of the four components (Christian et al. 1987), the expected time delay (Narasimha &amp; Chitre 1992), and the position of the lensing galaxy (Kristian et al. 1993). There are nonetheless many factors which combine to render this a difficult measurement, among them the small separation of the images and the small variability amplitude and long variability time scale of the “typical” optically selected quasar (Hook et al 1994). The measurement is further complicated by the likelihood of microlensing of the individual components (Witt et al. 1995), which depends upon the degree to which the quasar is resolved and the fraction of the lens mass in microlenses.

Large-scale structure effects on the gravitational lens image positions and time delay

We compute the fluctuations in gravitational lens image positions and time delay caused by large-scale structure correlations. We show that these fluctuations can be expressed as a simple integral over the density power spectrum. Using the Cosmic Background Explorer (COBE) normalization we find that positions of objects at cosmological distances are expected to deviate from their true positions by few arcminutes. These deflections are not directly observable. The positions of the images relative to one another fluctuate by a few percent of the relative separation, implying that one does not expect multiple images to be produced by large-scale structure. Nevertheless, the fluctuations are larger than the observational errors on the positions and affect reconstructions of the lens potential. The time delay fluctuations have a geometrical and a gravitational contribution. Both are much larger than the expected time delay from the primary lens, but partially cancel each other. We find that large-scale structure weakly affects the time delay and time delay measurements can be used as a probe of the distance scale in the universe.

Time Delay in Random Scattering

This work treats the time delay in scattering for the Schrodinger equation with a random potential. The time delay is related to the energy derivative of the phase shift. In the white noise limit, the phase shift and time delay satisfy a system of stochastic differential equations. In the high-frequency limit, the time delay is governed by a single stochastic differential equation. In this limit, the expected time delay is zero, but the variance of the time delay is the square of a kinematical time multiplied by a function of the ratio of the length of the scatterer to the localization length.

A new method for studying some statistical failure detection algorithms

A class of dynamical algorithms for detecting a change of parameter in a statistical model is described. Using large deviation results, the author approximates the expected time between false alarms. The expected time delay for failure detection is approximated. These approximations provide a criterion to measure the delay for detection, which is easily computable within the whole class.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Therapeutic problems arising from the use of the intravenous route for drug administration

The kinetics of drug delivery were studied under conditions of varying iv flow rates and varying sites of drug administration into an iv system. The iv sites and rates were selected on the basis of questionnaire data obtained from nursing personnel. The rate of drug delivery from the iv system was dependent upon the iv flow rate and site of injection of the drug into the iv system. Under conditions of slow iv flow rates (3 ml/hour) there was the expected time delay required for the drug to begin to be infused but an unanticipated protracted time required for actual completion of the drug infusion. Calculation of theoretical drug blood levels based on the results of these iv studies revealed very different blood levels of drug at respective times, including different peak concentrations, depending on the iv flow rate and site at which the drug was injected into the system. Failure to appreciate the effects of slow iv rates and distal iv injection sites on actual rates of drug administration can adversely affect pharmacokinetic decisions and conceivably influence therapeutic success or failure.

Predictors of Resistance to Persuasion: Propensity of Persuasive Attack, Pretreatment Language Intensity, and Expected Delay of Attack

Summary This investigation extended earlier research investigating predictors of resistance to persuasion. Ss were 113 male and female college students enrolled in undergraduate social science courses. The first hypothesis predicted a curvilinear relationship between propensity of attack (i.e., likelihood of having present attitudes attacked) and expected time delay of the attack in conferring resistance to persuasion. As predicted, in the condition of 50% probability of subsequent attack and no expected delay, maximum resistance to persuasion obtained; moreover, as hypothesized, resistance to persuasion decreased as expected delay increased. The predicted main effect for the superiority of moderately intense language in pretreatment messages did not receive support.

Laser Beam Directed at the Lunar Retro-Reflector Array: Observations of the First Returns

On 1 August between 10:15 and 12:50 Universal Time, with the Lick Observatory 120-inch (304-cm) telescope and a laser operating at 6943 angstroms, return signals from an optical retro-reflector array placed on the moon by the Apollo 11 astronauts were successfully detected. After the return signal was first detected it continued to appear with the expected time delay for the remainder of the night. The observed range is in excellent agreement with the predicted ephemeris. Transmitting between 7 and 8 joules per pulse, we found that each return signal averaged more than one photoelectron. This is in good agreement with calculations of the expected signal strength.