Arrival Of Units Research Articles

Neoproterozoic palaeogeography in the North Atlantic Region: Inferences from the Akkajaure and Seve Nappes of the Scandinavian Caledonides

The Scandinavian Caledonides exposes increasingly far travelled nappes upwards (westwards). The Lower- to Middle Allochthon are widely regarded as indigenous to the pre-Caledonian margin of Baltica (Fennoscandia), while higher thrust sheets (e.g. lower Upper Allochthon) have more controversial ancestries. Recent studies have suggested that thick early-Neoproterozoic (Tonian-Cryogenian) metasedimentary sequences hosted in thrust sheets of the Scandinavian, Greenland, British and Svalbard Caledonides represent two cycles of sedimentation along the peri-Rodinia (Laurentia–Baltica) margin of the supercontinent; alimented by erosion of the Grenvillian and Sveconorwegian orogenic belts. To test and expand this model, we report zircon U–Pb and whole rock Sm–Nd data from orthogneisses and siliciclastic metasediments in a transect from the (para)autochthonous Dividal Group, through the crystalline Middle Allochthon Akkajaure Nappes and into the overlying Seve Nappes (lower Upper Allochthon).The Akkajaure Nappe Complex (Middle Allochthon) is dominated by Precambrian crystalline rocks, of granitic to dioritic composition, that yield ages of 1788±6, 1806±15, and 1876±10Ma. These rocks are thrust over an imbricated basement (Lower Allochthon), which contains rocks of similar age, including a rhyolite dated at 1790±6Ma. The ages and Nd isotope chemistry of these rocks are identical to those from other Fennoscandian basement units and imply derivation from west of the Lofoten islands. A sample of sediment, originally attributed to the lowest unit of the overlying Seve Nappe Complex, has a detrital population dissimilar to all other Seve-Kalak Nappe samples and has a significant 1800Ma volcanic component. This sediment was intruded by granite at 1797±4Ma. Its provenance and rapid depositional timing indicates it is better considered as part of the tectonically captured Fennoscandian basement (Middle or Lower Allochthon).Metasediments from higher Seve nappes, in Jämtland, were deposited after 730Ma and contain a detrital zircon population indistinguishable from many sediments within the wider North Atlantic Region (NAR). Based on the similarity in detrital zircon age populations, depositional timings, and the apparent lack of material from the local Fennoscandian crystalline basement, these Jämtland Seve sediments are interpreted as peri-Rodinian deposits, which were carried along the passive margin of Baltica during the opening of Iapetus (after 610Ma). The strong similarity of detritus across NAR sedimentary units and the Rodinian paleogeography this implies, indicates that the exotic versus endemic derivation of nappes is more relevant in terms of which side of Iapetus these rocks were sitting after rifting; Baltica side (endemic) versus Laurentia side or microplate (exotic).The detrital zircon population from the early Cambrian part of the (para)autochthonous Dividal Group is identical to that from the Jämtland Seve and modern river sands flowing off the nappes. This indicates that the Seve Nappes were in sufficient proximity to Baltica by the Cambrian to shed detritus into the Dividal Group. This supports the notion of Ordovician arrival of peri-Rodinian units onto Baltica.

The 90‐Second Collaboration: A Critical Study of Collaboration Exercises at Extensive Accident Sites

In this study, a critical examination of collaboration, focusing on the alternatives, is carried out. The study is based on empirical data from four inter‐organizational exercises involving ambulance police and fire departments. We studied collaboration between the three organizations, from the arrival of the first units, until the mission was completed. It was found that collaboration was practiced to a relatively small degree, and that it primarily took place due to understaffing. In summary, the different organizational phenomena are sorted on a scale of stability vs. change. The result of the study shows that the organizations observed strive for stability, preferring repeated and well‐known behaviour.

Search Area Determination and Search Unit Deployment

In any maritime emergency where time elapses from the start of the incident to the arrival of rescue units it is necessary to establish the most probable survivor area. The procedure for establishing a most probable area is known as search area determination and requires the calculation of one position from another, known respectively as the datum point (DP) – the most probable position of survivors – and the last known position (LKP) – the incident position with recourse to the effects of tide and wind. Under the present manual methodology of the search and rescue planning system (USCG 1973), the DP is given an error treatment comprising drift initial position and search and rescue unit navigational (SRU) errors. Error calculations produce a search area radius (R) which is ‘boxed’ and referenced by four corner coordinates given in latitude and longitude.

A Priority Queue with General Bulk Service

This paper deals with priority queue with general bulk service rule. Priority and non-priority units are served by two identical servers. If a priority unit on arrival finds that (i) both the servers are busy, it balks and is considered lost to the system, (ii) one or both servers are free, it immediately goes to selvice. The non-priority units are served only when both the servers are free. Arrival of units are taken in batches of variable size whereas the service process follows general bulk service rule. Laplace transforms of generating functions of probabilities are obtained. The expressions for the steady-state probabilities and the mean queue length in the system are obtained.

The Social Responsibility of Insurance: A Case Study at Watts

The Watts Riots were a disaster of the first magnitude because of their destructive impact on lives and property and because they represented a new kind of hazard akin to insurrection. The involvement of the population was much more substantial than most persons realized. For the insurance industry this crisis posed the problem of maintaining continuous markets in an extreme form. The Watts Pool, a voluntary reinsurance program was put into operation and helped provide fire and extended coverage markets. The magnitude and intensity of the ghetto revolts in the United States in the 1960's raise a serious question whether, in the present regulatory framework, private carriers can provide continuous insurance markets without more government intervention. At 7:00 p.m. August 11, 1965 the trigger which led to the Watts riots was pulled. Marquette Frye, driving recklessly approximately 50 miles per hour in a 35 mile zone was flagged by police officer Lee Minikus for drunk driving. Frye pulled over to the curb. Lena Frye, mother of the drunk driver, came onto the scene at once to argue with the police officer. Her comments led her son to refuse to accept his arrest. A crowd gathered and at 7:19 p.m. a call was placed for emergency help. Help arrived immediately in considerable force. More than 27 squad cars arrived on the scene within a matter of minutes. The flashing red lights and sirens of the police cars served to stimulate the gathering of an ever increasing crowd at the scene of the arrest. The continuing resistance to arrest made it appear to onlookers that there was an excessive amount of force Irving Pfeffer, Ph.D., C.L.U., C.P.C.U., is Professor of Insurance in the Graduate School of Business Administration of the University of California, Los Angeles. Dr. Pfeffer is author of Insurance and Economic Theory and has contributed articles to the C.L.U. Journal, the C.P.C.U. Annals, and this Journal. This paper was presented at the 1967 Annual Meeting of A.R.I.A. used and, with the arrival of additional units of police, the mood of the crowd changed from curious to grumbling to hostile. Several women began to shout trash at the officers. A woman barber who joined the crowd spat on some of the officers and an attempt was made to arrest her. Some people in the crowd grabbed her arms in order to resist arrest and there was a kind of tug-of-war. The police were uncertain as to what strategy was appropriate in view of the fact that the crowd had now increased to several hundred persons and the police were seriously outnumbered. Some felt that the appropriate action was to get out of the situation rather than attempt to make the arrests. Others were trapped in the crowd and compelled to continue with what they were doing. The female barber fought vigorously to resist arrest. Her foul language and resistance made it difficult to get her into the police car. The crowd tended to look on her being led away as an additional humiliation on the Negro by the white policemen and the final insult. Distorted versions of this arrest spread quickly and wild rumors devel-

A General Model of a Single-Channel Queue: Discrete and Continuous Time Cases

In Part I, a single-channel service system consisting of a service facility and queue, in which the possible times of arrival of units and the possible service times are discrete, is analyzed. A method of calculating the moments of the total service time of units in the system is developed. This total service time is related to the delay caused by the system. When arrivals at different times are assumed to be independent, the “values” of the resulting Markov process can be calculated. These values lead to information about the transient behavior, autocorrelation function, expected first passage time, and expected extra delay that arises if another unit is inserted into the system. An expression for the geometric transform or moment generating function of the probability distribution of the total service time of units in the system is determined. The results are derived for arbitrary arrival and service time distributions. In Part II, the continuous time analog of the system of Part I is considered and analogous results are determined.

Priority Assignment in Waiting Line Problems

There are several commonly occurring situations in which the position of a unit or member of a waiting line is determined by a priority assigned to the unit rather than by its time of arrival in the line. An example is the line formed by messages awaiting transmission over a crowded communication channel in which urgent messages may take precedence over routine ones. With the passage of time a given unit may move forward in the line owing to the servicing of units at the front of the line or may move back owing to the arrival of units holding higher priorities. Though it does not provide a complete description of this process, the average elapsed time between the arrival in the line of a unit of a given priority and its admission to the facility for servicing is useful in evaluating the procedure by which priority assignments are made. Expressions for this quantity are derived for two cases—the single-channel system in which the unit servicing times are arbitrarily distributed (Eq. 3) and the multiple-channel system in which the servicing times are exponentially distributed (Eq. 6). In both cases it is assumed that arrivals occur at random. Operations Research, ISSN 0030-364X, was published as Journal of the Operations Research Society of America from 1952 to 1955 under ISSN 0096-3984.